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In literature, Nocardia cholesterolicum NRRL 5767 (NC NRRL5767) is well-known for its ability to transform ~95% of added oleic acid, an abundant agricultural commodity, to value-added product of 10-hydroxystearic acid (10-HSA). A small amount of unwanted 10-ketostearic acid (10-KSA) was also produced. This microbe also transforms ~80% of added linoleic acid to 10-hydroxy-12(Z)-octadecenoic acid (10-OH-12-OD) (an isomer of ricinoleic acid) with minor 10-oxo-12(Z)-octadecenoic acid (10-oxo-12-OD). The conversion of oleic acid to 10-HSA and then to 10-KSA (or linoleic acid to 10-OH-12-OD and then to 10-oxo-12-OD) is catalyzed by oleate hydratase and secondary alcohol dehydrogenase (2o-ADH), respectively. The objective of this project was to knockout the 2o-ADH gene in NC NRRL5767 so that the sole biotransformation product from oleic acid would be 10-HSA. Here, we report construction of CRISPR/Cas9/sgRNA chimeric plasmid that specifically target 5’ coding region of the 2o-ADH gene by Golden Gate Assembly. The construct was confirmed by DNA sequencing and transformed into NC NRRL 5767 via electroporation. The transformants were selected by apramycin resistance and screened for the presence of the target insert (crRNA) by PCR. The ability of the selected transformants to transform oleic acid to 10-HSA was screened by TLC and further confirmed by GC-MS. Our results showed that two of the transformants produced only 10-HSA with no detectable 10-KSA from oleic acid suggesting successful knockout of the 2o-ADH gene. Final confirmation came from the isolation of genomic DNA from these two transformants and the wild type NC NRRL5767 (used as DNA template) and using 17 primers (locate at different positions along the 2o-ADH gene and the 5’ upstream of this gene) for PCR. To our best knowledge, this is the first report to knockout the target gene in Nocardia species by CRISPR-Cas9 technology. 

Phytoestrogens are plant-derived compounds found in a variety of foods, most notably, soy. These compounds have been shown to improve immuno-metabolic health, yet mechanisms remain uncertain. We demonstrated previously that dietary phytoestrogen-rich soy (SOY) rescued metabolic dysfunction/inflammation following ovariectomy (OVX) in female rats; we also noted remarkable shifts in gut microbiota in SOY vs control diet-fed rats. Importantly, specific bacteria that significantly increased in those fed the SOY correlated positively with several favorable host metabolic parameters. One mechanism by which gut microbes might lead to such host effects is through production of bacterial metabolites. To test this possibility, we utilized non-targeted gas chromatography–mass spectrometry (GCMS) to assess the fecal metabolome in those previously studied animals. Partial least square discriminant analysis (PLSDA) revealed clear separation of fecal metabolomes based on diet and ovarian state. In particular, SOY-fed animals had greater fecal concentrations of the beneficial bacterial metabolite, S-equol, which was positively associated with several of the bacteria upregulated in the SOY group. S-equol was inversely correlated with important indicators of metabolic dysfunction and inflammation, suggesting that this metabolite might be a key mediator between SOY and gut microbiome-positive host health outcomes.

 

We present Fermi Gamma-ray Burst Monitor (Fermi-GBM) and Swift Burst Alert Telescope (Swift-BAT) searches for gamma-ray/X-ray counterparts to gravitational-wave (GW) candidate events identified during the third observing run of the Advanced LIGO and Advanced Virgo detectors. Using Fermi-GBM onboard triggers and subthreshold gamma-ray burst (GRB) candidates found in the Fermi-GBM ground analyses, the Targeted Search and the Untargeted Search, we investigate whether there are any coincident GRBs associated with the GWs. We also search the Swift-BAT rate data around the GW times to determine whether a GRB counterpart is present. No counterparts are found. Using both the Fermi-GBM Targeted Search and the Swift-BAT search, we calculate flux upper limits and present joint upper limits on the gamma-ray luminosity of each GW. Given these limits, we constrain theoretical models for the emission of gamma rays from binary black hole mergers.

 

Abstract Liquid xenon time projection chambers are promising detectors to search for neutrinoless double beta decay (0 $$\nu \beta \beta $$ ν β β ), due to their response uniformity, monolithic sensitive volume, scalability to large target masses, and suitability for extremely low background operations. The nEXO collaboration has designed a tonne-scale time projection chamber that aims to search for 0 $$\nu \beta \beta $$ ν β β of $$^{136}$$ 136 Xe with projected half-life sensitivity of $$1.35\times 10^{28}$$ 1.35 × 10 28  yr. To reach this sensitivity, the design goal for nEXO is $$\le $$ ≤ 1% energy resolution at the decay Q -value ( $$2458.07\pm 0.31$$ 2458.07 ± 0.31  keV). Reaching this resolution requires the efficient collection of both the ionization and scintillation produced in the detector. The nEXO design employs Silicon Photo-Multipliers (SiPMs) to detect the vacuum ultra-violet, 175 nm scintillation light of liquid xenon. This paper reports on the characterization of the newest vacuum ultra-violet sensitive Fondazione Bruno Kessler VUVHD3 SiPMs specifically designed for nEXO, as well as new measurements on new test samples of previously characterised Hamamatsu VUV4 Multi Pixel Photon Counters (MPPCs). Various SiPM and MPPC parameters, such as dark noise, gain, direct crosstalk, correlated avalanches and photon detection efficiency were measured as a function of the applied over voltage and wavelength at liquid xenon temperature (163 K). The results from this study are used to provide updated estimates of the achievable energy resolution at the decay Q -value for the nEXO design.