(To watch the full press conference with sign language interpretation, click here.)

The relaxation of anti-epidemic measures is a step in the right direction, Chief Executive Carrie Lam said today.

Mrs Lam made the statement at a press conference this afternoon.

She said the Government will relax the requirement limiting group gatherings in public places to a maximum of four people. Starting from Friday, up to eight people can gather in public places.

"So raising the number from four to eight for the catering business and also for the prohibition against group gatherings under Cap 599G is not an exact science, but this is a step in the right direction of relaxation.

"Maybe in another 14 days’ time we will raise the number of eight to 10, to 12, to 15 and so on."

Regarding bars and pubs, Mrs Lam said these venues will be able to reopen but the Government will put in place requirements to prevent physical interactions.

"We have decided that perhaps to strike a pragmatic balance is to allow them to reopen for business but to put in far more stringent requirements."

Such requirements include no live music, band performances or dancing in bar premises.

"That would be another way to keep the social distance and prevent as much as possible physical interactions."

Click here for the latest measures.

(To watch the full press briefing with sign language interpretation, click here.)

A recovered COVID-19 patient has tested positive for the virus again, the Hospital Authority announced today.

The authority’s Chief Manager (Quality & Standards) Dr Lau Ka-hin told a media briefing this afternoon that the patient was first admitted to Queen Mary Hospital on March 24 after having fever for a week. He subsequently tested positive for COVID-19.

He was discharged on April 16 after two consecutive negative tests for the virus.

Dr Lau said: "The patient presented to the Accident & Emergency Department of Queen Mary Hospital on May 5 because of some abdominal pain and diarrhoea.

"He was admitted to our hospital and was found to have a positive result for COVID-19 in the throat saliva, but the cycle threshold value is very high - nearly 36.

"The experts consider that this is the residual virus left in the patient’s body, which is not infective, and it is not likely to be a reinfection at this moment."

He added that the patient is in a stable condition.

(To watch the full press briefing with sign language interpretation, click here.)

The Centre for Health Protection today said recovered COVID-19 patients or those who did not have any symptoms may be discharged from hospital 10 days after the onset of symptoms or a positive test result.

Its Communicable Disease Branch Head Dr Chuang Shuk-kwan told a press briefing that the revised discharge criteria was based on the latest scientific evidence.

“Our Scientific Committee on Emerging & Zoonotic Diseases met yesterday and examined the latest scientific evidence on whether the virus will be viable from a patient.

“And the available evidence showed that this virus is usually not detected after 10 days since the onset of symptoms of patients. Some patients may have persistent positive PCR (polymerase chain reaction) for a long period of time.”

Dr Chuang noted that patients still had to meet the criteria of having two clinical specimens test negative, or testing positive for the SARS-CoV-2 antibody to be discharged.

“We have revised the discharge criteria to include the patient who (must have) been staying in the hospital for at least 10 days after the onset of symptoms. So this is the additional criteria, in addition to the previous criteria of two consecutive negative specimens.

“We added another criteria (which is) in case a patient has stayed in the hospital for a long time, more than 10 days since the onset of symptoms, but he or she has persistent positive PCR despite the Ct (cycle threshold) value being very high, they can check their serology, the antibody. So if the antibody turns positive, usually it is after 10 days, then he or she can be discharged.

“So this is based on the latest scientific evidence.”

Subsidies to local primary producers and wholesale traders operating in fresh food wholesale markets are being disbursed from today, the Agriculture, Fisheries & Conservation Department announced.

The department said 2,847 applications for the subsidy scheme of $10,000 to each local primary producer under the second round of the Anti-epidemic Fund have been received, with 1,294 approved involving a total of $12,940,000.

A total of 346 applications to the scheme to provide a subsidy of $40,000 to each eligible wholesale trader operating in fresh food wholesale markets were also received with 148 approved involving a total of $5,920,000.

The application periods of the two schemes will end on June 1.

Additionally, 57 borrowers have participated in the arrangement of a one-off interest-free deferral of loan repayment for one year under the Fisheries Development Loan Fund, it said.

The transcription factor forkhead box P3 (FOXP3) is a biomarker for regulatory T cells and can also be expressed in cancer cells, but its function in cancer appears to be divergent. The role of hepatocyte-expressed FOXP3 in hepatocellular carcinoma (HCC) is unknown. Here, we collected tumor samples and clinical information from 115 HCC patients and used five human cancer cell lines. We examined FOXP3 mRNA sequences for mutations, used a luciferase assay to assess promoter activities of FOXP3's target genes, and employed mouse tumor models to confirm in vitro results. We detected mutations in the FKH domain of FOXP3 mRNAs in 33% of the HCC tumor tissues, but in none of the adjacent nontumor tissues. None of the mutations occurred at high frequency, indicating that they occurred randomly. Notably, the mutations were not detected in the corresponding regions of FOXP3 genomic DNA, and many of them resulted in amino acid substitutions in the FKH region, altering FOXP3's subcellular localization. FOXP3 delocalization from the nucleus to the cytoplasm caused loss of transcriptional regulation of its target genes, inactivated its tumor-inhibitory capability, and changed cellular responses to histone deacetylase (HDAC) inhibitors. More complex FKH mutations appeared to be associated with worse prognosis in HCC patients. We conclude that mutations in the FKH domain of FOXP3 mRNA frequently occur in HCC and that these mutations are caused by errors in transcription and are not derived from genomic DNA mutations. Our results suggest that transcriptional mutagenesis of FOXP3 plays a role in HCC.

The peroxisome is a subcellular organelle that functions in essential metabolic pathways, including biosynthesis of plasmalogens, fatty acid β-oxidation of very-long-chain fatty acids, and degradation of hydrogen peroxide. Peroxisome biogenesis disorders (PBDs) manifest as severe dysfunction in multiple organs, including the central nervous system (CNS), but the pathogenic mechanisms in PBDs are largely unknown. Because CNS integrity is coordinately established and maintained by neural cell interactions, we here investigated whether cell-cell communication is impaired and responsible for the neurological defects associated with PBDs. Results from a noncontact co-culture system consisting of primary hippocampal neurons with glial cells revealed that a peroxisome-deficient astrocytic cell line secretes increased levels of brain-derived neurotrophic factor (BDNF), resulting in axonal branching of the neurons. Of note, the BDNF expression in astrocytes was not affected by defects in plasmalogen biosynthesis and peroxisomal fatty acid β-oxidation in the astrocytes. Instead, we found that cytosolic reductive states caused by a mislocalized catalase in the peroxisome-deficient cells induce the elevation in BDNF secretion. Our results suggest that peroxisome deficiency dysregulates neuronal axogenesis by causing a cytosolic reductive state in astrocytes. We conclude that astrocytic peroxisomes regulate BDNF expression and thereby support neuronal integrity and function.

Inter-α-inhibitor is a proteoglycan essential for mammalian reproduction and also plays a less well-characterized role in inflammation. It comprises two homologous “heavy chains” (HC1 and HC2) covalently attached to chondroitin sulfate on the bikunin core protein. Before ovulation, HCs are transferred onto the polysaccharide hyaluronan (HA) to form covalent HC·HA complexes, thereby stabilizing an extracellular matrix around the oocyte required for fertilization. Additionally, such complexes form during inflammatory processes and mediate leukocyte adhesion in the synovial fluids of arthritis patients and protect against sepsis. Here using X-ray crystallography, we show that human HC1 has a structure similar to integrin β-chains, with a von Willebrand factor A domain containing a functional metal ion-dependent adhesion site (MIDAS) and an associated hybrid domain. A comparison of the WT protein and a variant with an impaired MIDAS (but otherwise structurally identical) by small-angle X-ray scattering and analytical ultracentrifugation revealed that HC1 self-associates in a cation-dependent manner, providing a mechanism for HC·HA cross-linking and matrix stabilization. Surprisingly, unlike integrins, HC1 interacted with RGD-containing ligands, such as fibronectin, vitronectin, and the latency-associated peptides of transforming growth factor β, in a MIDAS/cation-independent manner. However, HC1 utilizes its MIDAS motif to bind to and inhibit the cleavage of complement C3, and small-angle X-ray scattering–based modeling indicates that this occurs through the inhibition of the alternative pathway C3 convertase. These findings provide detailed structural and functional insights into HC1 as a regulator of innate immunity and further elucidate the role of HC·HA complexes in inflammation and ovulation.

β-Glucocerebrosidase (GBA) hydrolyzes glucosylceramide (GlcCer) to generate ceramide. Previously, we demonstrated that lysosomal GBA1 and nonlysosomal GBA2 possess not only GlcCer hydrolase activity, but also transglucosylation activity to transfer the glucose residue from GlcCer to cholesterol to form β-cholesterylglucoside (β-GlcChol) in vitro. β-GlcChol is a member of sterylglycosides present in diverse species. How GBA1 and GBA2 mediate β-GlcChol metabolism in the brain is unknown. Here, we purified and characterized sterylglycosides from rodent and fish brains. Although glucose is thought to be the sole carbohydrate component of sterylglycosides in vertebrates, structural analysis of rat brain sterylglycosides revealed the presence of galactosylated cholesterol (β-GalChol), in addition to β-GlcChol. Analyses of brain tissues from GBA2-deficient mice and GBA1- and/or GBA2-deficient Japanese rice fish (Oryzias latipes) revealed that GBA1 and GBA2 are responsible for β-GlcChol degradation and formation, respectively, and that both GBA1 and GBA2 are responsible for β-GalChol formation. Liquid chromatography–tandem MS revealed that β-GlcChol and β-GalChol are present throughout development from embryo to adult in the mouse brain. We found that β-GalChol expression depends on galactosylceramide (GalCer), and developmental onset of β-GalChol biosynthesis appeared to be during myelination. We also found that β-GlcChol and β-GalChol are secreted from neurons and glial cells in association with exosomes. In vitro enzyme assays confirmed that GBA1 and GBA2 have transgalactosylation activity to transfer the galactose residue from GalCer to cholesterol to form β-GalChol. This is the first report of the existence of β-GalChol in vertebrates and how β-GlcChol and β-GalChol are formed in the brain.

Numerous zinc ectoenzymes are metalated by zinc and activated in the compartments of the early secretory pathway before reaching their destination. Zn transporter (ZNT) proteins located in these compartments are essential for ectoenzyme activation. We have previously reported that ZNT proteins, specifically ZNT5–ZNT6 heterodimers and ZNT7 homodimers, play critical roles in the activation of zinc ectoenzymes, such as alkaline phosphatases (ALPs), by mobilizing cytosolic zinc into these compartments. However, this process remains incompletely understood. Here, using genetically-engineered chicken DT40 cells, we first determined that Zrt/Irt-like protein (ZIP) transporters that are localized to the compartments of the early secretory pathway play only a minor role in the ALP activation process. These transporters included ZIP7, ZIP9, and ZIP13, performing pivotal functions in maintaining cellular homeostasis by effluxing zinc out of the compartments. Next, using purified ALP proteins, we showed that zinc metalation on ALP produced in DT40 cells lacking ZNT5–ZNT6 heterodimers and ZNT7 homodimers is impaired. Finally, by genetically disrupting both ZNT5 and ZNT7 in human HAP1 cells, we directly demonstrated that the tissue-nonspecific ALP-activating functions of both ZNT complexes are conserved in human cells. Furthermore, using mutant HAP1 cells, we uncovered a previously-unrecognized and unique spatial regulation of ZNT5–ZNT6 heterodimer formation, wherein ZNT5 recruits ZNT6 to the Golgi apparatus to form the heterodimeric complex. These findings fill in major gaps in our understanding of the molecular mechanisms underlying zinc ectoenzyme activation in the compartments of the early secretory pathway.

The dextransucrase DSR-OK from the Gram-positive bacterium Oenococcus kitaharae DSM17330 produces a dextran of the highest molar mass reported to date (∼109 g/mol). In this study, we selected a recombinant form, DSR-OKΔ1, to identify molecular determinants involved in the sugar polymerization mechanism and that confer its ability to produce a very-high-molar-mass polymer. In domain V of DSR-OK, we identified seven putative sugar-binding pockets characteristic of glycoside hydrolase 70 (GH70) glucansucrases that are known to be involved in glucan binding. We investigated their role in polymer synthesis through several approaches, including monitoring of dextran synthesis, affinity assays, sugar binding pocket deletions, site-directed mutagenesis, and construction of chimeric enzymes. Substitution of only two stacking aromatic residues in two consecutive sugar-binding pockets (variant DSR-OKΔ1-Y1162A-F1228A) induced quasi-complete loss of very-high-molar-mass dextran synthesis, resulting in production of only 10–13 kg/mol polymers. Moreover, the double mutation completely switched the semiprocessive mode of DSR-OKΔ1 toward a distributive one, highlighting the strong influence of these pockets on enzyme processivity. Finally, the position of each pocket relative to the active site also appeared to be important for polymer elongation. We propose that sugar-binding pockets spatially closer to the catalytic domain play a major role in the control of processivity. A deep structural characterization, if possible with large-molar-mass sugar ligands, would allow confirming this hypothesis.

VOLUME 295 (2020) PAGES 1898–1914Yichen Zhong's name was misspelled. The correct spelling is shown above.

VOLUME 292 (2017) PAGES 3531–3540This article has been withdrawn by Shuofeng Hu, Xiaomin Ying, Xiangming Zhang, and Ya Wang. Baocheng Hu, Xiang Wang, Ping Wang, Jian Wang, and Hongyan Wang could not be reached. In Fig. 1C, the DAPI and merged images for the no IR control were switched. The DNA-PKcs and actin immunoblots on the left appear to have been spliced. In Fig. 4C, the DNA-PKcs immunoblot appears to have been spliced. In Fig. 4D, lanes 1 and 5; lanes 2, 6, and 8; and lanes 3 and 7 of the DNA-PKcs immunoblot are the same. In the p-DNA-PKcs immunoblot, lanes 1 and 8, lanes 2 and 6, and lanes 3 and 7 are the same. In the CRY2 immunoblot, lanes 5 and 7 are the same. In the CDC25A immunoblot, lanes 3 and 8 are the same. In the GSK3B immunoblot, lanes 1 and 5 and lanes 3 and 7 are the same. Also in the GSK3B immunoblot, the upper GSK3B bands in lanes 6 and 8 are the same. Lanes 4 and 8 of the cyclin D1 immunoblot are the same. In Fig. 5A, the CDC25A immunoblot appears to have been spliced. Also in Fig. 5A, lanes 2–4 and lanes 6–8 of the CDC25A immunoblot are the same. Lanes 4–6 and 7–9 of the actin immunoblot are the same. In Fig. 5C, lane 1 of the CDC25A immunoblot was reused in lane 5, and lanes 3 and 4 were reused in lanes 7 and 8. In the...

VOLUME 289 (2014) PAGES 30635–30644This article has been withdrawn by Guangnan Chen, Dongkyoo Park, Francis A. Cucinotta, David S. Yu, Xingming Deng, William S. Dynan, Paul W. Doetsch, and Ya Wang. Hongyan Wang, Xiang Wang, Xiangming Zhang, and Xiaobing Tang could not be reached. The last two lanes of the actin immunoblot in Fig. 1A were reused in the last two lanes of the actin immunoblot in Fig. 1C. In Fig. 2A, the γ-H2AX and the merge with DAPI images for no IR treatment do not match. In Fig. 3A, lanes 3 and 4 of the γ-H2AX immunoblot were reused in lanes 7 and 8, and lanes 5 and 6 of the H2A immunoblot were reused in lanes 7 and 8. In Fig. 3B, lanes 5 and 6 of the H2A immunoblot were reused in lanes 7 and 8. In Fig. 3C, lanes 5 and 6 of the γ-H2AX immunoblot were reused in lanes 7 and 8. Additionally, lanes 1 and 2 of the H2A immunoblot were reused in lanes 3 and 4. In Fig. 3D, lanes 1 and 2 of the Mre11 immunoblot from lysates were reused in lanes 4 and 5. In the γ-H2AX immunoblot, lane 3 was reused in lane 7, and lane 4 was reused in lanes 6 and 8. Also in the H2A immunoblot, lanes 1 and 2 were reused in lanes 3 and 4. In Fig. 4B, lanes 2 and 6 of the Mre11 immunoblot from Ogg1−/− cells are the same. In the Ape1...

Hippo pathway signaling limits cell growth and proliferation and maintains the stem-cell niche. These cellular events result from the coordinated activity of a core kinase cassette that is regulated, in part, by interactions involving Hippo, Salvador, and dRassF. These interactions are mediated by a conserved coiled-coil domain, termed SARAH, in each of these proteins. SARAH domain–mediated homodimerization of Hippo kinase leads to autophosphorylation and activation. Paradoxically, SARAH domain–mediated heterodimerization between Hippo and Salvador enhances Hippo kinase activity in cells, whereas complex formation with dRassF inhibits it. To better understand the mechanism by which each complex distinctly modulates Hippo kinase and pathway activity, here we biophysically characterized the entire suite of SARAH domain–mediated complexes. We purified the three SARAH domains from Drosophila melanogaster and performed an unbiased pulldown assay to identify all possible interactions, revealing that isolated SARAH domains are sufficient to recapitulate the cellular assemblies and that Hippo is a universal binding partner. Additionally, we found that the Salvador SARAH domain homodimerizes and demonstrate that this interaction is conserved in Salvador's mammalian homolog. Using native MS, we show that each of these complexes is dimeric in solution. We also measured the stability of each SARAH domain complex, finding that despite similarities at both the sequence and structural levels, SARAH domain complexes differ in stability. The identity, stoichiometry, and stability of these interactions characterized here comprehensively reveal the nature of SARAH domain–mediated complex formation and provide mechanistic insights into how SARAH domain–mediated interactions influence Hippo pathway activity.

The protein-tyrosine phosphatase SHP2 is an allosteric enzyme critical for cellular events downstream of growth factor receptors. Mutations in the SHP2 gene have been linked to many different types of human diseases, including developmental disorders, leukemia, and solid tumors. Unlike most SHP2-activating mutations, the T507K substitution in SHP2 is unique in that it exhibits oncogenic Ras-like transforming activity. However, the biochemical basis of how the SHP2/T507K variant elicits transformation remains unclear. By combining kinetic and biophysical methods, X-ray crystallography, and molecular modeling, as well as using cell biology approaches, here we uncovered that the T507K substitution alters both SHP2 substrate specificity and its allosteric regulatory mechanism. We found that although SHP2/T507K exists in the closed, autoinhibited conformation similar to the WT enzyme, the interactions between its N-SH2 and protein-tyrosine phosphatase domains are weakened such that SHP2/T507K possesses a higher affinity for the scaffolding protein Grb2-associated binding protein 1 (Gab1). We also discovered that the T507K substitution alters the structure of the SHP2 active site, resulting in a change in SHP2 substrate preference for Sprouty1, a known negative regulator of Ras signaling and a potential tumor suppressor. Our results suggest that SHP2/T507K's shift in substrate specificity coupled with its preferential association of SHP2/T507K with Gab1 enable the mutant SHP2 to more efficiently dephosphorylate Sprouty1 at pTyr-53. This dephosphorylation hyperactivates Ras signaling, which is likely responsible for SHP2/T507K's Ras-like transforming activity.

The developing nervous system is remarkably sensitive to environmental signals, including disruptive toxins, such as polybrominated diphenyl ethers (PBDEs). PBDEs are an environmentally pervasive class of brominated flame retardants whose neurodevelopmental toxicity mechanisms remain largely unclear. Using dissociated cortical neurons from embryonic Rattus norvegicus, we found here that chronic exposure to 6-OH–BDE-47, one of the most prevalent hydroxylated PBDE metabolites, suppresses both spontaneous and evoked neuronal electrical activity. On the basis of our previous work on mitogen-activated protein kinase (MAPK)/extracellular signal-related kinase (ERK) (MEK) biology and our observation that 6-OH–BDE-47 is structurally similar to kinase inhibitors, we hypothesized that certain hydroxylated PBDEs mediate neurotoxicity, at least in part, by impairing the MEK–ERK axis of MAPK signal transduction. We tested this hypothesis on three experimental platforms: 1) in silico, where modeling ligand–protein docking suggested that 6-OH–BDE-47 is a promiscuous ATP-competitive kinase inhibitor; 2) in vitro in dissociated neurons, where 6-OH–BDE-47 and another specific hydroxylated BDE metabolite similarly impaired phosphorylation of MEK/ERK1/2 and activity-induced transcription of a neuronal immediate early gene; and 3) in vivo in Drosophila melanogaster, where developmental exposures to 6-OH–BDE-47 and a MAPK inhibitor resulted in offspring displaying similarly increased frequency of mushroom-body β–lobe midline crossing, a metric of axonal guidance. Taken together, our results support that certain ortho-hydroxylated PBDE metabolites are promiscuous kinase inhibitors and can cause disruptions of critical neurodevelopmental processes, including neuronal electrical activity, pre-synaptic functions, MEK–ERK signaling, and axonal guidance.

Incorporation of ribonucleotides into DNA can severely diminish genome integrity. However, how ribonucleotides instigate DNA damage is poorly understood. In DNA, they can promote replication stress and genomic instability and have been implicated in several diseases. We report here the impact of the ribonucleotide rATP and of its naturally occurring damaged analog 1,N6-ethenoadenosine (1,N6-ϵrA) on translesion synthesis (TLS), mediated by human DNA polymerase η (hpol η), and on RNase H2–mediated incision. Mass spectral analysis revealed that 1,N6-ϵrA in DNA generates extensive frameshifts during TLS, which can lead to genomic instability. Moreover, steady-state kinetic analysis of the TLS process indicated that deoxypurines (i.e. dATP and dGTP) are inserted predominantly opposite 1,N6-ϵrA. We also show that hpol η acts as a reverse transcriptase in the presence of damaged ribonucleotide 1,N6-ϵrA but has poor RNA primer extension activities. Steady-state kinetic analysis of reverse transcription and RNA primer extension showed that hpol η favors the addition of dATP and dGTP opposite 1,N6-ϵrA. We also found that RNase H2 recognizes 1,N6-ϵrA but has limited incision activity across from this lesion, which can lead to the persistence of this detrimental DNA adduct. We conclude that the damaged and unrepaired ribonucleotide 1,N6-ϵrA in DNA exhibits mutagenic potential and can also alter the reading frame in an mRNA transcript because 1,N6-ϵrA is incompletely incised by RNase H2.

Bacterial type VII secretion systems secrete a wide range of extracellular proteins that play important roles in bacterial viability and in interactions of pathogenic mycobacteria with their hosts. Mycobacterial type VII secretion systems consist of five subtypes, ESX-1–5, and have four substrate classes, namely, Esx, PE, PPE, and Esp proteins. At least some of these substrates are secreted as heterodimers. Each ESX system mediates the secretion of a specific set of Esx, PE, and PPE proteins, raising the question of how these substrates are recognized in a system-specific fashion. For the PE/PPE heterodimers, it has been shown that they interact with their cognate EspG chaperone and that this chaperone determines the designated secretion pathway. However, both structural and pulldown analyses have suggested that EspG cannot interact with the Esx proteins. Therefore, the determining factor for system specificity of the Esx proteins remains unknown. Here, we investigated the secretion specificity of the ESX-1 substrate pair EsxB_1/EsxA_1 in Mycobacterium marinum. Although this substrate pair was hardly secreted when homologously expressed, it was secreted when co-expressed together with the PE35/PPE68_1 pair, indicating that this pair could stimulate secretion of the EsxB_1/EsxA_1 pair. Surprisingly, co-expression of EsxB_1/EsxA_1 with a modified PE35/PPE68_1 version that carried the EspG5 chaperone-binding domain, previously shown to redirect this substrate pair to the ESX-5 system, also resulted in redirection and co-secretion of the Esx pair via ESX-5. Our results suggest a secretion model in which PE35/PPE68_1 determines the system-specific secretion of EsxB_1/EsxA_1.

Kindlins are focal adhesion proteins that regulate integrin activation and outside-in signaling. The kindlin family consists of three members, kindlin-1, -2, and -3. Kindlin-2 is widely expressed in multiple cell types, except those from the hematopoietic lineage. A previous study has reported that the Drosophila Fit1 protein (an ortholog of kindlin-2) prevents abnormal spindle assembly; however, the mechanism remains unknown. Here, we show that kindlin-2 maintains spindle integrity in mitotic human cells. The human neuroblastoma SH-SY5Y cell line expresses only kindlin-2, and we found that when SH-SY5Y cells are depleted of kindlin-2, they exhibit pronounced spindle abnormalities and delayed mitosis. Of note, acetylation of α-tubulin, which maintains microtubule flexibility and stability, was diminished in the kindlin-2–depleted cells. Mechanistically, we found that kindlin-2 maintains α-tubulin acetylation by inhibiting the microtubule-associated deacetylase histone deacetylase 6 (HDAC6) via a signaling pathway involving AKT Ser/Thr kinase (AKT)/glycogen synthase kinase 3β (GSK3β) or paxillin. We also provide evidence that prolonged hypoxia down-regulates kindlin-2 expression, leading to spindle abnormalities not only in the SH-SY5Y cell line, but also cell lines derived from colon and breast tissues. The findings of our study highlight that kindlin-2 regulates mitotic spindle assembly and that this process is perturbed in cancer cells in a hypoxic environment.

Fatty acid esters of hydroxy fatty acids (FAHFAs) are a newly discovered class of signaling lipids with anti-inflammatory and anti-diabetic properties. However, the endogenous regulation of FAHFAs remains a pressing but unanswered question. Here, using MS-based FAHFA hydrolysis assays, LC-MS–based lipidomics analyses, and activity-based protein profiling, we found that androgen-induced gene 1 (AIG1) and androgen-dependent TFPI-regulating protein (ADTRP), two threonine hydrolases, control FAHFA levels in vivo in both genetic and pharmacologic mouse models. Tissues from mice lacking ADTRP (Adtrp-KO), or both AIG1 and ADTRP (DKO) had higher concentrations of FAHFAs particularly isomers with the ester bond at the 9th carbon due to decreased FAHFA hydrolysis activity. The levels of other lipid classes were unaltered indicating that AIG1 and ADTRP specifically hydrolyze FAHFAs. Complementing these genetic studies, we also identified a dual AIG1/ADTRP inhibitor, ABD-110207, which is active in vivo. Acute treatment of WT mice with ABD-110207 resulted in elevated FAHFA levels, further supporting the notion that AIG1 and ADTRP activity control endogenous FAHFA levels. However, loss of AIG1/ADTRP did not mimic the changes associated with pharmacologically administered FAHFAs on extent of upregulation of FAHFA levels, glucose tolerance, or insulin sensitivity in mice, indicating that therapeutic strategies should weigh more on FAHFA administration. Together, these findings identify AIG1 and ADTRP as the first endogenous FAHFA hydrolases identified and provide critical genetic and chemical tools for further characterization of these enzymes and endogenous FAHFAs to unravel their physiological functions and roles in health and disease.

The ribosome biogenesis factor Las1 is an essential endoribonuclease that is well-conserved across eukaryotes and a newly established member of the higher eukaryotes and prokaryotes nucleotide-binding (HEPN) domain-containing nuclease family. HEPN nucleases participate in diverse RNA cleavage pathways and share a short HEPN nuclease motif (RφXXXH) important for RNA cleavage. Most HEPN nucleases participate in stress-activated RNA cleavage pathways; Las1 plays a fundamental role in processing pre-rRNA. Underscoring the significance of Las1 function in the cell, mutations in the human LAS1L (LAS1-like) gene have been associated with neurological dysfunction. Two juxtaposed HEPN nuclease motifs create Las1's composite nuclease active site, but the roles of the individual HEPN motif residues are poorly defined. Here using a combination of in vivo experiments in Saccharomyces cerevisiae and in vitro assays, we show that both HEPN nuclease motifs are required for Las1 nuclease activity and fidelity. Through in-depth sequence analysis and systematic mutagenesis, we determined the consensus HEPN motif in the Las1 subfamily and uncovered its canonical and specialized elements. Using reconstituted Las1 HEPN-HEPN' chimeras, we defined the molecular requirements for RNA cleavage. Intriguingly, both copies of the Las1 HEPN motif were important for nuclease function, revealing that both HEPN motifs participate in coordinating the RNA within the Las1 active site. We also established that conformational flexibility of the two HEPN domains is important for proper nuclease function. The results of our work reveal critical information about how dual HEPN domains come together to drive Las1-mediated RNA cleavage.

The cellular energy sensor AMP-activated protein kinase (AMPK) is a metabolic regulator that mediates adaptation to nutritional variations to maintain a proper energy balance in cells. We show here that suckling-weaning and fasting-refeeding transitions in rodents are associated with changes in AMPK activation and the cellular energy state in the liver. These nutritional transitions were characterized by a metabolic switch from lipid to glucose utilization, orchestrated by modifications in glucose levels and the glucagon/insulin ratio in the bloodstream. We therefore investigated the respective roles of glucose and pancreatic hormones on AMPK activation in mouse primary hepatocytes. We found that glucose starvation transiently activates AMPK, whereas changes in glucagon and insulin levels had no impact on AMPK. Challenge of hepatocytes with metformin-induced metabolic stress strengthened both AMPK activation and cellular energy depletion under limited-glucose conditions, whereas neither glucagon nor insulin altered AMPK activation. Although both insulin and glucagon induced AMPKα phosphorylation at its Ser485/491 residue, they did not affect its activity. Finally, the decrease in cellular ATP levels in response to an energy stress was additionally exacerbated under fasting conditions and by AMPK deficiency in hepatocytes, revealing metabolic inflexibility and emphasizing the importance of AMPK for maintaining hepatic energy charge. Our results suggest that nutritional changes (i.e. glucose availability), rather than the related hormonal changes (i.e. the glucagon/insulin ratio), sensitize AMPK activation to the energetic stress induced by the dietary transition during fasting. This effect is critical for preserving the cellular energy state in the liver.

(Institute for Operations Research and the Management Sciences) Job performance has long been understood to be the primary equalizing factor affecting promotions for men and women in the workplace, but research shows, women don't gain as much from the same performance improvements as men do. New research in the INFORMS journal Information Systems Research shows training plays an important part in promotions for women in the field of information technology.

(Carnegie Mellon University) Intelligent tutoring systems have been shown to be effective in helping to teach certain subjects, such as algebra or grammar, but creating these computerized systems is difficult and laborious. Now, researchers at Carnegie Mellon University have shown they can rapidly build them by, in effect, teaching the computer to teach.

A pet dog repeatedly tested weak positive for the COVID-19 virus, indicating a low-level of infection with the virus, the Agriculture, Fisheries & Conservation Department said today.

The department first collected test samples from the dog on February 26. It detected low levels of COVID-19 virus from its nasal and oral cavity samples on February 27.

The dog also tested weak positive for the virus when the department repeated the test on February 28 and March 2.

Experts from Hong Kong University’s School of Public Health, City University’s College of Veterinary Medicine & Life Sciences and the World Organisation for Animal Health have been consulted, and unanimously agreed that these results suggest that the dog has a low-level of infection and it is likely to be a case of human-to-animal transmission, the department noted.

The dog has not shown any signs of disease related to COVID-19. It is currently under quarantine at the animal keeping facility at the Hong Kong Port of Hong Kong-Zhuhai-Macao Bridge. The department will closely monitor the dog and repeat the test later.

To ensure public and animal health, the department strongly advises that mammalian pets from households with COVID-19 infected people, or close contacts of infected individuals, should be put under quarantine in the department’s facilities.

The department emphasised that there is currently no evidence that pets can be a source of infection of COVID-19 and under no circumstances should people abandon their pets.

People living in units 13 and 14 of the top six floors of Heng Tai House in Fu Heng Estate, Tai Po need to be quarantined as a precaution.

Hong Kong University Chair of Infectious Disease Prof Yuen Kwok-yung made the statement at a media briefing today after an expert team conducted initial epidemiological investigations in the building to find the cause of a new COVID-19 infection.

The new case announced this afternoon involves a 59-year-old man who lives on the 34th floor of the building.

Prof Yuen said: “There is a possibility that when the patients on the 32nd floor are defecating - we know now that the fecal material actually contains the virus - while they’re defecating the fecal material goes into the sewer system.

“There is a vent of air that comes through the venting pipe, which goes to the top floor and maybe aerosolised in the air and then the droplets try to settle but, while at the same time, when there’s a light wind blowing, in which the air current going over the rooftop carries the particles back into the top floors.

“And of course, the 34th floor is the top floor. That is the most dangerous, followed by the 33rd and 32nd floors.”

Prof Yuen added he is uncertain if the venting pipe will continue to produce more infected aerosolised particles.

“So it is just a precautionary measure that we must remove the residents from the top six floors in units 13 and 14 for a period of time.”

For information and health advice on COVID-19, visit the Government's dedicated webpage.

The Agriculture, Fisheries & Conservation Department (AFCD) announced today that country park barbecue sites and campsites will remain closed until April 23.

The 163 barbecue sites and 41 campsites managed by AFCD have been closed since March 28. Given the latest development of COVID-19, the department has decided to extend the closure.

During the closure of these facilities, no barbecuing or camping activities are allowed in country parks.

AFCD staff will step up patrols of these sites and violation of relevant regulations will be subject to prosecution.

Call 1823 for enquiries or visit the Enjoy Hiking website for updates.

The department also reminded people visiting country parks to maintain personal and environmental hygiene and maintain social distancing.

The maximum monthly rental subsidy for each recycler under the One-off Rental Support Scheme will be increased from $25,000 to $37,500, the Environmental Protection Department announced today.

To help the recycling industry cope with the current economic situation and operational difficulties due to the COVID-19 epidemic, the Recycling Fund has allocated $50 million in additional funds to raise the scheme’s subsidy level.

The fund has now earmarked up to $250 million in total funding to fight the virus and help the recycling industry ride out difficult times.

On April 15, the Advisory Committee on Recycling Fund agreed to strengthen support under the scheme by increasing the rental assistance from 50% to 75% for the subsidy period from April to September.

The maximum monthly rental subsidy for each recycler will be increased to $37,500, while the maximum total rental subsidy for the 12 months will be increased from $300,000 to $375,000.

The scheme was launched last year to benefit about 500 street-corner recycling shops and 400 recycling sites.

In the face of current economic difficulties, the fund announced in February an extension of the subsidy period from six months to 12 months, lasting until September.     

As of April 9, the scheme has approved 103 applications, involving subsidies of more than $20 million.

The application deadline for the scheme is September 30. Enquiries can be made to 2788 5658 or via email.

Non-residential and residential electricity accounts are benefitting from government relief measures, the Environmental Bureau announced today.

Under the measures, nearly 90% of non-residential electricity bills obtained a 75% subsidy for electricity charges in March, while 40% of residential electricity accounts enjoyed zero electricity charges in the first quarter of the year.

The Government announced about $2.3 billion in provisions last December to provide an electricity charge subsidy to each eligible non-residential electricity account holder to cover 75% of their monthly electricity charges for four months, subject to a monthly cap of $5,000.

The Budget further provided $2.9 billion to extend the subsidy period to eight months.

According to the bills issued by the two power companies in March, 360,000 non-residential bills obtained a 75% subsidy. This is close to 90% of the total eligible non-residential tariff bills.

To balance the impact on people's livelihood of the recent transition to cleaner electricity generating systems in Hong Kong, the bureau implemented the electricity charges relief scheme in January 2019.

A monthly electricity charge relief of $50 has been granted to each eligible residential electricity account for 60 months.

To help the public cope with the challenging economic environment, the Government implemented a new round of one-off electricity charge subsidy schemes in January.

A subsidy of $160 will be credited to each residential electricity account from January to November, while $240 will be credited in December.

From early this year, over 2.7 million households have been benefitting from both the electricity charges relief measures and the electricity charges subsidy. The bills of the two power companies indicated that 40% of residential electricity accounts, representing 1 million households, enjoyed zero electricity charges.

The bureau called on the community to cherish environmental resources, including saving energy and electricity to mitigate climate change and improve air quality.

The Agriculture, Fisheries & Conservation Department (AFCD) today announced that its barbecue sites and campsites in country parks will be closed until May 7.

It made the decision in light of the latest development of the COVID-19 epidemic and to reduce social contact.

All of these sites have been closed since 6pm on March 28.

During the closure of these facilities, no one should carry out barbecuing or camping activities in country parks.

AFCD staff will step up patrols of the sites and violation of relevant regulations may be subject to prosecution.

In the past two weeks, AFCD took enforcement action against 34 people who carried out barbecuing or camping activities in country parks.

The department will continue to closely monitor the situation and review the arrangement as appropriate.

For the latest updates on facilities in country parks, visit the Enjoy Hiking website.

Tenants of the EcoPark, country park refreshment kiosks and the Hong Kong Wetland Park will benefit from increased rental concessions for government premises.

To help tenants cope with the economic impact of the COVID-19 epidemic, rental concessions of government premises from April to September will be increased from 50% to 75%.

The Environment Bureau said tenants of the EcoPark, country park refreshment kiosks and the Hong Kong Wetland Park will receive additional rental concessions of about $3.6 million.

Together with the 50% rental concessions provided by the Government from last October to March, these tenants will receive concessions of more than $17 million within 12 months, the bureau said.

Meanwhile, tenants of the Hong Kong Wetland Park will receive a full rental waiver during the park’s closure.

Vladimir Dragović and Irina Goryuchkina
Bull. Amer. Math. Soc. 57 (2020), 293-299.
Abstract, references and article information

In March, Hong Kong International Airport (HKIA) became the first in the world to be certified as an International Air Transport Association (IATA) Center of Excellence for Perishable Logistics (CEIV Fresh) Partner Airport.

Two of the airport’s cargo terminal operators, Hong Kong Air Cargo Terminals Limited (HACTL) and Cathay Pacific Services Limited (CPSL) have achieved IATA CEIV Fresh Certification, while Cathay Pacific recently became the world’s first airline to be certified.

IATA created the Centre of Excellence for Independent Validators (CEIV) to help organisations involved in the air cargo supply chain achieve handling excellence.

The certification underscores the speed, consistency and efficiency of all HKIA stakeholders when it comes to the treatment and transportation of perishable products.

It also helps to ensure food safety, and reduce food wastage and loss along the supply chain.

Quality benchmark

Hong Kong Air Cargo Terminals Limited Chief Executive Wilson Kwong said the main value of the accreditation is that it provides a universally recognised standard.

“It gives assurance to the various stakeholders that we have, and we are adhering to the highest possible standards.”

Both accredited cargo terminal operators HACTL and CPSL have set up perishable cargo handling areas with truck docks next to the apron.

As soon as the perishable goods are unloaded from the aircraft, they are immediately transported to the handling area.

The clearance and sampling checks have been streamlined to minimise the time taken to unload the goods. There are cold rooms set at tailored temperatures for various kinds of perishable cargo.

Their staff training and handling process have also been assessed and certified for their compliance with the global industry standards.

Cathay Pacific Services Limited Chief Executive Officer Jenny Lam noted that one of the challenges in meeting the certification standard is training its 2,000 employees in handling and storing perishable goods.

“They first have to identify what types of perishables they are, such as are they flowers, are they fruits, are they meat, so that they know how to segregate the storage.

“Secondly, they gain knowledge about certain fruits that cannot be put close to each other such as bananas and apples.”

Growth opportunities

In 2018, the airport handled about 380,000 tonnes of perishable cargo - a rise of 12% on 2017, with perishables accounting for about 8% of total air cargo volume.

Airport Authority Commercial Executive Director Cissy Chan explained that temperature-controlled air freight is one of the fastest growing segments in the air cargo market.

She believes with the new certification, the airport is well-placed to capture the increasing growth opportunities in the market for fresh and perishable goods.

“With the opening of the Hong Kong-Zhuhai-Macao Bridge, the transport time between the airport and the Greater Bay Area, notably the western part of the Pearl River Delta, will be further cut down.

“So this will put us in an even better position to become the transhipment hub for these perishables for the entire bay area.”

Extra backing

To support the growing demand for perishables, the Airport Authority has provided additional cool dollies, so there are now more than 30 for use by the whole airport community. It is also building apron shelters to protect the perishables from ambient weather elements.

Cathay Pacific Cargo Service Delivery General Manager Frosti Lau said they would work closely with the authority and its cargo terminal to see what new investments are required to handle the increasing demand.

Stretching from Sai Kung on the east coast to Tuen Mun in the west, the whopping 100 km-long MacLehose Trail is the longest and first long-distance hiking trail in Hong Kong.

The trail is divided into 10 sections and traverses eight country parks which embrace magnificent natural scenery, interesting historical relics and a wide range of wild fauna and flora, winding past the coastline, rugged mountains, valleys and reservoirs to provide a diverse outdoor experience for hikers.

It was even named as one of the world's 20 dream trails by National Geographic.

A lot of hard work went into building the trail, with Agriculture, Fisheries & Conservation Department workers out in the elements without much shelter, often carrying heavy equipment uphill and downhill over varied terrain.

Building bonds

Wan Keung and Lai Hing joined the department around 40 years ago. They both took part in the MacLehose Trail project which was started in 1979 to promote hiking activities in Hong Kong.

The project was named after the then-Governor Sir Murray MacLehose - who was himself a keen walker - for his significant efforts to conserve Hong Kong’s countryside.

“I have contributed a lot to the trail. I am happy as it is packed with people now,” said Mr Wan.

While Mr Lai added: “We are going to retire, but the trail will be here for a long time.”

Despite working on the same project, the pair - now in their 60s - only met for the first time recently because they were assigned to different work stations back then. However, they became firm friends instantly.

From setting up the many signposts along the way, to hand-building the heavy stone steps, the two men eagerly shared all the skills and techniques they learnt on the project.

Listening to their conversations now it is hard to imagine that when they first started work, both had little practical knowledge about constructing a trail. They acquired welding, plastering and woodwork skills through hands-on experience and with the support of their seniors. But that was not the biggest challenge they encountered.

“Building the trail was really difficult, as there were so many sections. We were either drowned in sweat or drenched by rain while working,” Mr Lai explained.

One poignant memory for Mr Wan was of working during wildfires that raged through the countryside.

“There was only one thing for it: we stayed until the fire was extinguished. That was really hard.”

Lasting legacy

After nine months’ hard work the MacLehose Trail was finally opened on October 26, 1979.

These days Mr Wan and Mr Lai enjoy the trail for leisure instead of work.

Both said receiving compliments from family and friends or witnessing the sheer enjoyment of hikers on the trail made their hard work worthwhile.

They now hope to pass on their skills to the younger workers, so that a new generation of Hong Kong people can take care of the trail and ensure it lasts for decades to come.

The Airport Authority expanded the scope of its food waste recycling programme in 2011 to cover Hong Kong International Airport business partners, including restaurants and lounges operating in terminal buildings, as well as airline catering companies, hotels and cargo terminals.

In 2017-18, over 2,000 tonnes of food waste from 17 airport business partners were collected for recycling.

Rainie Ho, the supervisor of one participating restaurant, said staff make every effort to collect food waste on a constant basis.

“We have three bins of recycled food waste, including eggs, toast, bread, chicken, meat, pork bones, tea and coffee every day.”

Ms Ho gave kudos to the Airport Authority for making the process simple.

“The Airport Authority provides us with garbage bags every month. We explain to our staff that the red bags are for food waste, while the black ones are for general rubbish. This makes it easier for them to remember and handle.”

Airport Authority Assistant General Manager (Sustainability) Mike Kilburn is the facilitator of the food waste recycling programme. He hoped to encourage more business partners to join by making the scheme as trouble-free as possible.

“This is an example of an easy, useful and free programme because the contractor comes to collect from each company and the contractor provides a clean rubbish bin for the food waste, they take the food waste away, they wash the bin and then they bring it back clean.

“And it is useful because the food waste is not just sent to the landfill, but it is turned into fish meal so it goes back into the food chain because the fish meal is fed to the fish and the people can eat the fish, so it is a very complete system.”

Surplus food collection

In addition to food waste recycling, the authority promotes the Food Rescue Programme in co-operation with a local non-governmental organisation called Food Angel.

In 2013, the authority helped Food Angel to purchase a refrigerated truck and covered the cost of collecting surplus food from business partners on the airport island.

By 2014, a central storage room was set up in the terminal building to collect even more surplus food from catering outlets.

By proving it can reduce its environmental impact by working closely with the entire airport community, the authority was recognised at the 2018 Hong Kong Awards for Environmental Excellence where it won the Gold Award for the Public & Community Services Sector.

Future prep

In 2018, the authority launched a voluntary municipal solid waste charging pilot scheme to achieve waste reduction.

It has assisted more than 200 tenants with measuring their waste generation and calculating what it would cost to dump it in the future.

Another participating restaurant manager Alfred Lau explained that the pilot scheme helps restaurants gear up for the polluter-pays principle.

“A mock monthly invoice was issued to us, showing the quantity of waste disposed and the estimated disposal charge. Now we understand that by reducing our waste, we will pay less in the end.”

Mr Lau believes the pilot scheme encourages eateries to alter their disposal behaviour by recycling as much food waste as possible.

“Our disposed waste amount fell sharply once we learnt useful ways to recycle. Our restaurant is located in the restricted area of the airport where drinks are not allowed to be brought inside. So many passengers buy bottled drinks and create a large amount of plastic waste. Just by recycling plastic bottles, our waste decreased significantly.”

The authority said it is proud to be the driving force behind waste reduction.

“We make it easy for them because we do all the organisation, we make it useful because they can help them to prepare, and it is free for them to join the programme. This is very important for us because as the Airport Authority, our job is to create a concept that other people can follow and if you address those three criteria, you make it very hard for them to say no to you. We take away their reasons to say no, so it is easy for them to join our scheme,” said Mr Kilburn.

The Hong Kong Awards for Environmental Excellence is led by the Environmental Campaign Committee alongside the Environmental Protection Department and in conjunction with nine organisations. The objective is to reduce Hong Kong’s environmental impact by promoting environmental management.

The Airport Authority’s current target is to reduce, recycle and recover 50% of all its waste by 2021.

The recent economic downturn has dealt a severe blow to many employees. However, for Shiu Yin-ming and Poon Man-kit, the crisis has brought them skill-upgrading opportunities.

Miss Shiu has over 30 years’ experience in the retail industry. Her last job was a salesperson at a lighting store. Struck by the competition with online stores and a series of protests, the shop closed in October last year and left her unemployed.

“I have got no choice. Many people in Hong Kong have mortgage burdens. It is the most worrying part. And it is frightening to see my account balance drop,” she said.

Miss Shiu spent several months trying to get a job but failed.

“Of course I was frustrated. Perhaps the employers think that young people are more hard-working. It is difficult for middle-aged people like me to get a job. It hurt my confidence and I hesitated to keep going."

Seeing the demand in the healthcare industry, Miss Shiu decided to swap careers. She joined the Love Upgrading Special Scheme and enrolled in the Foundation Certificate in Care-related Support Worker Training.

The course covered basic pathology and healthcare skills. It also arranged recruitment from the Hospital Authority in class. Miss Shiu said the special course helped her to find a job and she will soon work at a nursing home.

“It is like an admission ticket. During an interview at a nursing home, the interviewer asked how I would change a nappy for an elderly person. I answered what I had learnt from the course. Moreover, as I have not participated in an interview after so many years of work, the interview skills that I have learnt from the course have geared me up,” she said.

Better prospects

Young newcomers to the job market are also affected by the economic downturn.

Mr Poon has been engaged in casual work in the catering industry. The 19-year-old said there used to be plenty of casual job opportunities on career websites, but that is no longer the case. He has been underemployed in recent months and feels his family just see him as someone who is not in education, employment, or training.

“The full-time waiters have not got much work to do, and each of them is assigned to be responsible for a few positions. So, the restaurant does not need extra casual manpower. My relatives look down on me like I am a neet,” he said.

Mr Poon has enrolled in the Foundation Certificate in Barista Training to gain experience in different positions in the industry.

"Many coffee shops and hotels need people to make latte art. I think the course will help me get a job more easily. I plan to further enroll in other courses relating to pastry-making," he added.

Skills upgrade

The Love Upgrading Special Scheme, launched in last October, provides free training to employees affected by the recent economic downturn to upgrade their skills. The courses are conducted in full-time or part-time mode and offer special allowances.

According to the Employees Retraining Board, as of the end of March, more than 12,200 people have applied for the scheme. About one-third of them are aged between 50 to 59.

The applicants mainly come from the catering, retail, social and personal services industries.

The most popular course is the Foundation Certificate in Care-related Support Worker Training, followed by courses related to baker and pastry cook, barista and security training.

Employees Retraining Board Executive Director Byron Ng said the 66 courses under the scheme were specially selected.

“We want to help those employees in the hard-hit industries like tourism, catering, retail, hotel, construction, etc. Also, we want to provide courses in industries which demand heavy labour during this period, such as healthcare and innovative technology.”

The scheme does not impose any restrictions on the trainees’ industry and educational attainment.

“We hope to encourage all unemployed or underemployed employees, including those who are highly educated, and take these chances to upgrade their own skills so they can re-enter the market smoothly,” Mr Ng said.

He added that those who have completed a full-time vocational skills course will get a follow-up service that includes three months of employment.

The second phase of the scheme will be launched in July, and the monthly maximum allowance is expected to increase from $4,000 to $5,800.

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