A mutation in the endonuclease domain of mouse MLH3 reveals novel roles for MutLγ during crossover formation in meiotic prophase I

During meiotic prophase I, double-strand breaks (DSBs) initiate homologous recombination leading to non-crossovers (NCOs) and crossovers (COs). In mouse, 10% of DSBs are designated to become COs, primarily through a pathway dependent on the MLH1-MLH3 heterodimer (MutLγ). Mlh3 contains an endonuclease domain that is critical for resolving COs in yeast. We generated a mouse (Mlh3DN/DN) harboring a mutation within this conserved domain that is predicted to generate a protein that is catalytically inert. Mlh3DN/DN males, like fully null Mlh3-/- males, have no spermatozoa and are infertile, yet spermatocytes have grossly normal DSBs and synapsis events in early prophase I. Unlike Mlh3-/- males, mutation of the endonuclease domain within MLH3 permits normal loading and frequency of MutLγ in pachynema. However, key DSB repair factors (RAD51) and mediators of CO pathway choice (BLM helicase) persist into pachynema in Mlh3DN/DN males, indicating a temporal delay in repair events and revealing a mechanism by which alternative DSB repair pathways may be selected. While Mlh3DN/DN spermatocytes retain only 22% of wildtype chiasmata counts, this frequency is greater than observed in Mlh3-/- males (10%), suggesting that the allele may permit partial endonuclease activity, or that other pathways can generate COs from these MutLγ-defined repair intermediates in Mlh3DN/DN males. Double mutant mice homozygous for the Mlh3DN/DN and Mus81-/- mutations show losses in chiasmata close to those observed in Mlh3-/- males, indicating that the MUS81-EME1-regulated crossover pathway can only partially account for the increased residual chiasmata in Mlh3DN/DN spermatocytes. Our data demonstrate that mouse spermatocytes bearing the MLH1-MLH3DN/DN complex display the proper loading of factors essential for CO resolution (MutSγ, CDK2, HEI10, MutLγ). Despite these functions, mice bearing the Mlh3DN/DN allele show defects in the repair of meiotic recombination intermediates and a loss of most chiasmata

Risk of secondhand smoke exposure and severity of COVID-19 infection: multicenter case–control study

IntroductionExposure to secondhand smoke (SHS) is an established causal risk factor for cardiovascular disease (CVD) and chronic lung disease. Numerous studies have evaluated the role of tobacco in COVID-19 infection, severity, and mortality but missed the opportunity to assess the role of SHS. Therefore, this study was conducted to determine whether SHS is an independent risk factor for COVID-19 infection, severity, mortality, and other co-morbidities.MethodologyMulticentric case–control study was conducted across six states in India. Severe COVID-19 patients were chosen as our study cases, and mild and moderate COVID-19 as control were evaluated for exposure to SHS. The sample size was calculated using Epi-info version 7. A neighborhood-matching technique was utilized to address ecological variability and enhance comparability between cases and controls, considering age and sex as additional matching criteria. The binary logistic regression model was used to measure the association, and the results were presented using an adjusted odds ratio. The data were analyzed using SPSS version 24 (SPSS Inc., Chicago, IL, USA).ResultsA total of 672 cases of severe COVID-19 and 681 controls of mild and moderate COVID-19 were recruited in this study. The adjusted odds ratio (AOR) for SHS exposure at home was 3.03 (CI 95%: 2.29–4.02) compared to mild/moderate COVID-19, while SHS exposure at the workplace had odds of 2.19 (CI 95%: 1.43–3.35). Other factors significantly related to the severity of COVID-19 were a history of COVID-19 vaccination before illness, body mass index (BMI), and attached kitchen at home.DiscussionThe results of this study suggest that cumulative exposure to secondhand cigarette smoke is an independent risk factor for severe COVID-19 illness. More studies with the use of biomarkers and quantification of SHS exposure in the future are needed

Tasar silkworm pupal oil: An excellent source of edible oil for industrial and therapeutic applications

Polyunsaturated fatty acids are widely recognized due to their remedial properties. In our previous studies, we reported that Tasar silkworm pupal oil (TSPO) is rich in polyunsaturated fatty acids, particularly alpha-linolenic acid (ALA). Further we also extracted ALA from TSPO and reported its significant anticancer activity. In the present study, extraction of TSPO and physico-chemical characterizations including saponification, acid, peroxide, iodine pH values, and colour determination were carried out to investigate the edible properties of TSPO for commercialization as a therapeutically active functional food. Further, the anti-diabetic activity of TSPO were analyzed by α-amylase inhibition assay. The saponification (154.75 ± 0.581mg KOH/g), acid (6.24 ± 0.421 mg KOH/g), peroxide (16.20 ± 0.265 meq/kg), iodine (40.33 ± 0.577g/100 ml), pH (6.17), and colour (14 Y+1.2 R) values were within the permissible range for commercialization. In addition to this, the results of the α-amylase inhibition assay showed that TSPO exhibited an IC50 value of 207339 µg/ml.  The results may facilitate the use of TSPO oil in therapeutic and functional food applications Keywords: Characterization; Commercialization; Tasar pupal oil; Silkworm pupae

Isolation of Alpha-linolenic acid (ALA) from tasar, Antherea mylitta pupal oil and its anticancer activity

Previously, we reported that tasar silkworm pupal oil (TPO) is a rich source of alpha-linolenic acid (ALA) (37%). In this study, we have used three chromatographic techniques, namely preparative HPLC, gas chromatography-mass spectroscopy (GC-MS), and gas chromatography flame ionization detection (GC-FID), to purify, determine, and quantify alpha-linolenic acid (ALA), respectively, from TPO.  Additionally, to determine the potential of the purified ALA as an anticancer drug, the sulforhodamine B (SRB) assay was utilised for in vitro investigation. Results revealed that ALA was successfully purified in a fraction of TPO by preparatory HPLC. It was discovered that only ALA was present in the purified fraction of ALA when it underwent GC-MS analysis, further confirming its purity. In addition, the quantification analysis using GC-FID showed that the concentration of ALA was 11760 ppm. Furthermore, anticancer analysis revealed purified ALA significantly inhibited the growth of a colon cancer cell line, (COLO-205) with a GI 50 ≤20.  This is the initial investigation into isolating and purifying ALA from Tasar pupal oil. Keywords: Alpha-linolenic acid; GC-FID; HPLC; Omega-3Preparative, Tasar pupal oil

Characterization, antibacterial and anticancer study of silk fibroin hydrogel

Purpose: Protein-based hydrogels such as silk fibroin hydrogel, are used in tissue engineering and regenerative medicine applications as they showed striking characteristics like biocompatibility and offered various benefits as biomaterials. The current study sought to prepare silk fibroin hydrogel and characterise it in order to assess its antibacterial and anticancer activity. Methodology: Silk fibroin hydrogel was prepared and characterized by using different microscopy methods, namely Scanning Electron Microscopy (SEM), Phase Contrast Electron (PCM) microscopy, and foldscope analysis. Further, it was characterized through 1H-NMR analysis, Fourier Transform Infrared spectroscopy (FTIR) analysis, and swelling properties. A Current study also covers an antimicrobial and anticancer analysis of silk fibroin hydrogel by disk diffusion method and SRB (Sulforhodamine B) assay respectively. Results: The antibacterial study confirmed that SF hydrogel has a moderate antibacterial activity for Streptococcus mutans, and Salmonella typhi. Additionally, the SRB assay test showed that silk fibroin hydrogels had moderate anticancer activity against the human lung cancer cell line (A549). Conclusion: The current study unequivocally demonstrates that silk fibroin hydrogel has antibacterial and anti-cancerous properties, making it a suitable scaffold for future studies that seek to target a specific drug delivery site. Keywords: Silk fibroin; Swelling behaviour; Anticancer; Drug carrier; Wound healin

Involvement of general public in biomedical research

Biomedical research is crucial for any country′s progress and the health of its ethnic population. This effort needs to be sustained and well supported for it to bear optimum results. The major stakeholders in medical research are the general public, patients, researchers, physicians (and medical institutions), the pharmaceutical industry, regulatory authorities, and the government. Much of the pressure to perform cutting edge research in developed countries is driven by the general public; however, this has been conspicuous by its absence in India. This is largely due to misconceptions that medical research in developing countries is an experimental exercise using human beings as guinea pigs, primarily benefiting only the pharmaceutical industry and a general lack of awareness about the importance of original research within the country. This editorial addresses various issues related to public involvement in biomedical research and suggests the need for solutions and imperative remedial measures