The following is a post by Kristi Finefield, Reference Specialist in the Prints & Photographs Division, and member of the Picture This blog team. As the Library of Congress marks its 220th year, we take the opportunity to explore one example of its efforts to sustain and celebrate the arts in its physical spaces. Above […]

This rapid and efficient method to prepare highly purified recombinant adeno-associated viruses (rAAVs) is based on binding of negatively charged rAAV capsids to an anion-exchange resin that is pH dependent.

This is a simple method for rapid preparation of recombinant adeno-associated virus (rAAV) stocks, which can be used for in vivo gene delivery. The purity of these vectors is considerably lower than that obtained by either CsCl gradient centrifugation or by combination of iodixanol gradient ultracentrifugation followed by column chromatography.

The most commonly used method for production of recombinant adeno-associated virus (rAAVs) in research laboratories is by transient triple transfection of 293 cells with AAV cis and trans plasmids and an adenovirus helper plasmid. This protocol describes the processes required to prepare the transfected cell suspension for virus purification.

For most immunoblots developed with chemiluminescence or with fluorochrome-based detection systems, it is possible to remove the primary and secondary antibodies from the membrane without affecting the bound antigen. This allows you to reuse the membrane for detection of another protein antigen. The blots developed with chromogenic substrates can also be stripped of antibodies and reprobed, but the bands detected in the first round of immunoblotting will remain unaffected. Stripping and reprobing of the membrane are particularly useful when the amount of sample is limited or when it is important to accurately compare the signal between two different protein antigens in the same sample. Examples of such experiments include determining the levels of a protein antigen in a series of samples relative to the loading control and comparison of the phosphorylated form to the total levels of the protein in the sample.

Before probing blots for the presence of an antigen, the total composition of the transferred proteins can be determined by staining the nitrocellulose or polyvinylidene fluoride (PVDF) membrane. Staining for proteins is useful to determine the position of the non-prestained molecular weight markers or individual lanes on the gel and to ensure that efficient transfer has occurred. It can be also used to verify equal loading of the samples in the gel when a comparison of the protein of interest between the different samples is important. The conventional procedures such as Coomassie Blue and silver staining methods used for staining polyacrylamide gels are incompatible with immunoblotting. Ponceau S is the more common staining method in immunoblotting protocols because it is compatible with antibody–antigen binding, is cost efficient, and provides a good contrast between the stained bands and background. In this protocol, nitrocellulose or PVDF membrane is rinsed with ultrapure H₂O after the transfer of proteins. Ponceau S dye is applied as an acidic aqueous solution, and the proteins on the membrane are stained with red color. The membrane is briefly destained with water and can be photographed or scanned to obtain the image of the total protein staining. Individual lane positions or the molecular weight standards can be marked with a pencil, if required.

The Bradford assay is a quick and fairly sensitive method for measuring the concentrations of proteins. It is based on the shift in absorbance maximum of Coomassie Brilliant Blue G-250 dye from 465 to 595 nm following binding to denatured proteins in solution.

Colloidal gold–antibody conjugates are easy to prepare and are an excellent choice for microscopic applications. Colloidal gold is an aqueous suspension of nanometer-sized particles of gold. Typically, chloroauric acid, HAuCl₄, is reduced with dilute solutions of sodium citrate, as described here. This will cause the gold to form small aggregates that will associate with proteins. Gold particles of specific sizes can be isolated and differentiated microscopically, allowing these particles to be used for multiple-label experiments. Colloidal gold-labeled antibodies are widely used in electron microscopy (EM), and can be used for light microscopy but require additional steps (silver enhancement).

There are many uses for antibodies labeled with metal ions. Most of these methods involve first attaching a metal chelator to the antibody molecule. This is achieved using standard cross-linking chemistry and then adding the desired metal at appropriate concentration and pH. The method described here outlines a basic procedure for creating a lanthanide conjugate. Lanthanide conjugates are used for proximity assays, as MRI contrast agents, or for mass cytometry experiments. Different metals and chelators can be substituted, but the basic procedures are similar.

Successful modification of the bacterial artificial chromosome (BAC) after two-step BAC engineering is confirmed in two separate polymerase chain reactions (PCRs). The first reaction (5' co-integrate PCR) uses a forward 5' co-integrate primer (a sequence located upstream of the 5' end of the A-box) and a reverse 3' primer on the vector (175PA+50AT) or within the reporter sequence or mutated region as appropriate. The second reaction (3' co-integrate PCR) uses a forward 5' primer on the recA gene (RecA1300S) and a reverse 3' co-integrate primer (a sequence located downstream from the 3' end of the B-box). Those colonies shown to be positive in PCR analysis are further tested for sensitivity to UV light. After the resolution, colonies that have lost the excised recombination vector including sacB and recA genes become UV light sensitive.

Bacterial artificial chromosome (BAC) clones are rendered electrocompetent and transformed with the recombinant shuttle vector, pLD53SCAB/AB-box. Cointegrates are selected by growth on chloramphenicol and ampicillin to ensure recombination of the shuttle vector into the BAC.

Plasmid DNA is prepared from the recombinant shuttle vector pLD53.SCAB/A-B created by cloning of the A and B homology arms for two-step bacterial artificial chromosome (BAC) engineering. To confirm that the A-box and B-box arms have been successfully incorporated into pLD53.SCAB, the pattern of enzyme digestion of the modified plasmid is compared with that of the unmodified pLD53.SCAB. Once the shuttle vector is shown to carry the proper sequences, it is ready for transfer into the BAC host.

This protocol describes the preparation of the shuttle vector before its introduction into bacterial artificial chromosome (BAC) host cells for BAC two-step engineering. The homology arm sequences, prepared previously, are introduced by ligation into the digested shuttle vector DNA to provide sites for recombination within the BAC clone. Crude lysates of individual bacterial transformants serve as templates in polymerase chain reaction (PCR) analysis to confirm the presence of the homology arms in the recombinant shuttle vector.

The 700-bp A homology arm (A-box) and the 700-bp B homology arm (B-box) are amplified by polymerase chain reaction (PCR) using purified bacterial artificial chromosome (BAC) DNA as template for two-step BAC engineering. The resulting A-box PCR product contains an AscI site at its 5' end (the 5' primer incorporates an AscI site, and the 3' primer does not incorporate any restriction sites). The B-box PCR product contains an XmaI site at its 3' end (the 5' primer does not incorporate any restriction sites, and the 3' primer incorporates an XmaI site). The amplification products are then digested with the appropriate restriction endonucleases to render them suitable for cloning into the shuttle vector.

In two-step bacterial artificial chromosome (BAC) engineering, a single plasmid is introduced into the BAC-carrying cell lines. The shuttle vector pLD53.SCAB (or pLD53.SCAEB) carries the recA gene and the R6K origin, which requires the protein to replicate. PIR2 cells, expressing , are typically used for the amplification of the vector and maintain about 15 copies/cell of the donor vector, which is relatively stable in this host.

We assess the dynamics of volatility spillovers among global systemically important banks (G-SIBs). We measure spillovers using vector-autoregressive models of range volatility of the equity prices of G-SIBs, together with machine learning methods. We then compare the size of these spillovers with the degree of systemic importance measured by the Basel Committee on Banking Supervision's G-SIB bucket designations.

Amid widespread sell-offs in risky asset classes, corporate bond exchange-traded funds (ETFs) traded at steep discounts to underlying asset values in March. Contributing factors were high market volatility, reduced risk-taking by dealers and investors' reaction to policy decisions. Policy interventions that improve market functioning in a given sector can have temporary yet important spillovers to other segments through portfolio rebalancing by investors.

Using a cross-country sample of bank-dependent public fi rms we study the international spillovers of a change in banking regulation on corporate borrowing. For identi cation we examine how US rms' liabilities vis-a-vis banks, non-bank lenders and bond markets evolve after an increase in capital requirements implemented by the European Banking Authority (EBA) in 2011. We find that US firms experience a reduction in credit lines but not in term loans from EU banks.

This paper studies the relationship between bank geographic complexity and risk. We use a unique dataset of 96 bank holding companies around the world to measure the geographic dispersion of their affiliates. We study how this dispersion interacts with economic and regulatory conditions to affect the riskiness of the bank.

FSI Briefs No 3, April 2020. In response to the 2007-09 Great Financial Crisis (GFC), accounting standard setters introduced a new methodology to value loans based on expected credit losses (ECL). The previous approach, based on incurred losses, was viewed as procyclical and inconsistent with prudential objectives. In the wake of the Covid-19 pandemic, several prudential authorities and the Basel Committee on Banking Supervision (BCBS), introduced a series of measures to clarify how banks should consider various public and private debt relief programmes in their ECL estimates and in their calculation of regulatory capital. These measures are intended to incentivise banks to continue supporting the real economy, while reducing pressure on banks' ECL provisions, earnings and regulatory capital. Supervisory initiatives that provide capital relief should be augmented by severe constraints on the payment of dividends, bonuses and share buybacks. These joint actions will simultaneously expand banks' lending capacity and enhance their ability to absorb losses. Prudential authorities face difficult trade-offs as they confront the most severe economic crisis in modern times. Encouraging the use of flexibility in applicable accounting standards, while preserving market trust and transparency in the reported financial statements of banks, will be key in fostering both economic and financial stability.

BIS Bulletin No 8, April 2020. Information on local labour markets and Google searches can be used to construct a measure of the vulnerability of employment in different regions of the United States to the Covid-19 shock. Regional exposure to Covid-19 varies significantly, ranging from a low of 2% to a high of 98% of total local employment. We test for the usefulness of the Covid-19 exposure measure by showing that areas with higher exposure report more Google search queries related to the pandemic and unemployment benefits.

BIS Bulletin No 9, April 2020. By allowing banks to run down some of their buffers, policymakers are sending a strong signal about their resolve to lessen the economic fallout from the pandemic. Such prudential measures complement the main policy levers: monetary and fiscal instruments. To avoid a reduction in credit to the real economy, authorities need to ensure that banks have the capacity and willingness to make use of the flexibility afforded by the buffer release. Payout restrictions on banks and risk-sharing between banks and the public sector will be key. For banks to continue playing a positive role in the supply of funding during the recovery, they should maintain usable buffers for a long period, as losses from a severe recession will take time to materialise.

Recent literature has highlighted that international trade is mostly priced in a few key vehicle currencies, and is increasingly dominated by intermediate goods and global value chains (GVCs). Taking these features into account, this paper reexamines the business cycle dynamics of international trade and its relationship with monetary policy and exchange rates.

Our ongoing celebration of the Library of Congress National Book Festival continues with Poets Laureate Tracy K. Smith and Robert Hass discussing the making of poetry, the position of Poet Laureate and their new books, "American Journal: Fifty Poems for Our Time" (edited by Smith) and "A Little Book on Form: An Exploration into the Formal Imagination of Poetry" (Hass), on the Poetry & Prose stage at the 2018 Festival.

Our ongoing celebration of the Library of Congress National Book Festival continues with presidential scholar Annette Gordon-Reed discussing "The Hemingses of Monticello: An American Family" on the Special Programs stage at the 2015 Festival.

Our ongoing celebration of the Library of Congress National Book Festival continues with crime writer Patricia Cornwell discussing "Red Mist,” her 19th Kay Scarpetta novel, on the Fiction & Mystery stage at the 2012 Festival.

Our ongoing celebration of the Library of Congress National Book Festival continues with young adult and fantasy author Leigh Bardugo discussing "Crooked Kingdom" on the Genre Fiction stage at the 2018 Festival. This post includes prompts for writing and thinking that young readers, families and teachers can use to explore the author and the author’s work—recommended for ages 13+.

Our ongoing celebration of the Library of Congress National Book Festival continues with former Secretary of State Condoleezza Rice discussing "Democracy: Stories from the Long Road to Freedom" on the Main Stage at the 2017 Festival.

Our ongoing celebration of the Library of Congress National Book Festival continues with two-time Pulitzer Prize-winning novelist Colson Whitehead discussing "Zone One" on the Poetry & Prose stage at the 2012 Festival.

Our ongoing celebration of the Library of Congress National Book Festival continues with historian Michael Beschloss discussing “Presidents of War” on the Main Stage at the 2019 Festival.

Our ongoing celebration of the Library of Congress National Book Festival continues with crime and mystery writer Karin Slaughter discussing "Broken," part of her Will Trent series, on the Fiction & Mystery stage at the 2010 Festival.

Our ongoing celebration of the Library of Congress National Book Festival continues with actor and author Neil Patrick Harris discussing "The Magic Misfits: The Minor Third." The event, part of the new year-long National Book Festival Presents series, took place in the Library’s Coolidge Auditorium. This post includes prompts for writing and thinking that young readers, families and teachers can use to explore the author and the author’s work—recommended for ages 8+.

Even celebrity chef Julia Child said that the sleek appliance made mixing 'marvelous'

Rural educator Frank Cyr had the vision and pull to force the nation to standardize the color of the ubiquitous vehicle

Open for visitors, these houses model upcycling at its finest

A prototype deployed in San Francisco Bay imagines the underside of a floating building as an upside-down artificial reef

British product designer Lucy Hughes has invented a biodegradable plastic made from fish offcuts

Architects and planners from the Netherlands are advising coastal cities worldwide on how to live with water

From gas stations to public libraries, these celebrity architect-designed buildings are worth a road trip

Press release about the Basel Committee publishing consultation paper on revisions to the credit valuation adjustment risk framework, 28 November 2019.

BIS Press Release - Easing trade tensions lift sentiment: BIS Quarterly Review, 8 December 2019

Press release: Basel Committee invites comments on the design of a prudential treatment for crypto-assets, 12 December 2019.

Press release about the Basel Committee launching the consolidated Basel Framework, 16 December 2019.

The BIS Board of Directors has decided to invite the central banks of Kuwait, Morocco and Vietnam to become members of the BIS. This is the first such expansion since 2011 and will take the number of members to 63.

The Bank of Canada, the Bank of England, the Bank of Japan, the European Central Bank, the Sveriges Riksbank and the Swiss National Bank, together with the Bank for International Settlements (BIS), have created a group to share experiences as they assess the potential case for central bank digital currency (CBDC) in their home jurisdictions. (Press release, 21 January 2020)

Markets Committee calls for wider adoption of global code of conduct for foreign exchange markets (Press release, 30 January 2020)