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A few bacterial Cas9 nucleases have been repurposed as genome editing tools. Here, the authors use bioinformatic and biochemical analyses to characterize 79 Cas9 proteins, revealing substantial functional diversity and thus expanding the available toolbox of RNA-programmable CRISPR-associated nucleases.

A variant of 9°N DNA polymerase [Genbank ID (AAA88769.1)] with three mutations (D141A, E143A, A485L) and commercialized under the name “Therminator DNA polymerase” has the ability to incorporate a variety of modified nucleotide classes. This Review focuses on how Therminator DNA Polymerase has enabled new technologies in synthetic biology and DNA sequencing. In addition, we discuss mechanisms for increased modified nucleotide incorporation.

In this paper we study the important period where many thrifts shifted from traditional mortgage products into consumer loan products. Specifically, we examine the impact of this move toward consumer banking on the risk and return profiles of thrift institutions. One reason given for this shift was the shrinldng margins associated with the traditional mortgage lending business of the thrift industry. Other reasons are increased competition from pure-play competitors and the increased merger activity among commercial banks enabling thrifts to market themselves as consumer banks. All of these reasons help to explain why the traditional thrift model became less viable. What strategic changes are necessary for thrift institutions to survive and compete effectively in the today’s financial environment? Thrifts may choose to rearrange their product mix, expand their investment portfolio, manage the enterprise more efficiently, or some combination of these, strategies. One strategy chosen by certain thrifts has been to shift from the traditional model of a mortgage-oriented lender to that of a consumer bank. Using market data from the first quarter of 1985 to the fourth quarter of 1992, we examine whether thrift organizations that followed this consumer banking strategy increased or decreased their overall exposure to risk. Employing the volatility of equity returns as our measure of total thrift risk, we find that thrifts that specialized in consumer lending exhibited lower risk while maintaining similar common stock returns, relative to thrifts that did not specialize in consumer lending. This suggests that thrifts employing a strategy of significantly diversifying their asset portfolios by specializing in consumer lending were rewarded by the equity market. Conversely, thrifts that invested only a small proportion of their assets in the consumer banking strategy did not receive a similar reward from the equity market for diversifying into consumer banking.

Effective management of the COVID-19 pandemic requires widespread and frequent testing of the population for SARS-CoV-2 infection. Saliva has emerged as an attractive alternative to nasopharyngeal samples for surveillance testing as it does not require specialized personnel or materials for its collection and can be easily provided by the patient. We have developed a simple, fast, and sensitive saliva-based testing workflow that requires minimal sample treatment and equipment. After sample inactivation, RNA is quickly released and stabilized in an optimized buffer, followed by reverse transcription loop-mediated isothermal amplification (RT-LAMP) and detection of positive samples using a colorimetric and/or fluorescent readout. The workflow was optimized using 1,670 negative samples collected from 172 different individuals over the course of 6 months. Each sample was spiked with 50 copies/μL of inactivated SARS-CoV-2 virus to monitor the efficiency of viral detection. Using pre-defined clinical samples, the test was determined to be 100% specific and 97% sensitive, with a limit of detection of 39 copies/mL. The method was successfully implemented in a CLIA laboratory setting for workplace surveillance and reporting. From April 2021-February 2022, more than 30,000 self-collected samples from 755 individuals were tested and 85 employees tested positive mainly during December and January, consistent with high infection rates in Massachusetts and nationwide.

Sulfolobus islandicus rod shaped virus 2 (SIRV2) infects the archaeon Sulfolobus islandicus at extreme temperature (70°C-80°C) and acidity (pH 3). SIRV2 encodes a Holliday junction resolving enzyme (SIRV2 Hjr) that has been proposed as a key enzyme in SIRV2 genome replication. The molecular mechanism for SIRV2 Hjr four-way junction cleavage bias, minimal requirements for four-way junction cleavage, and substrate specificity were determined. SIRV2 Hjr cleaves four-way DNA junctions with a preference for cleavage of exchange strand pairs, in contrast to host-derived resolving enzymes, suggesting fundamental differences in substrate recognition and cleavage among closely related Sulfolobus resolving enzymes. Unlike other viral resolving enzymes, such as T4 endonuclease VII or T7 endonuclease I, that cleave branched DNA replication intermediates, SIRV2 Hjr cleavage is specific to four-way DNA junctions and inactive on other branched DNA molecules. In addition, a specific interaction was detected between SIRV2 Hjr and the SIRV2 virion body coat protein (SIRV2gp26). Based on this observation, a model is proposed linking SIRV2 Hjr genome resolution to viral particle assembly.