Biology subjects

Akhtar, M. S.

Publications and source records attributed to Akhtar, M. S..

5 recordsLinked to original sources

bioRxiv2026

Localized SARS-CoV-2 Infection Triggers a Tissue-Wide Antiviral Response and Functional Impairment of Olfactory Sensory Neurons

Olfactory dysfunction is a hallmark of COVID-19, yet the mechanisms by which severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection causes widespread sensory impairment remain incompletely understood. We compared the olfactory epithelial tropism of multiple SARS-CoV-2 variants in a mouse model and observed that Alpha and Beta variants exhibited the greatest infectivity for the olfactory epithelium (OE), whereas Omicron rarely infected this tissue despite comparable pulmonary viral titers. We further defined the effects of SARS-CoV-2 on olfactory sensory neurons (OSNs) using immunohistochemistry, single-cell RNA sequencing, spatial gene expression characterization, and functional odor stimulation. The localized infection of sustentacular cells triggered a tissue-wide interferon-stimulated antiviral response that extended beyond infected regions for Alpha and Beta but was largely absent following Omicron infection. Mature OSNs transiently adopted an interferon-responsive state before exhibiting persistent downregulation of odorant signal transduction, mitochondrial, and activity-dependent gene pathways. Consistent with these transcriptional changes, odor stimulation failed to elicit normal activity-dependent gene expression during SARS-CoV-2 infection, indicating impaired neuronal function without widespread neuronal loss. Progressive accumulation of macrophages further indicated sustained inflammatory remodeling of the OE. Together, these findings demonstrate that SARS-CoV-2 infection initiates tissue-wide antiviral signaling in the OE that persistently disrupts OSN function, providing a mechanistic framework for COVID-19-associated anosmia.

neuroscience↗

bioRxiv2026

Genetic and behavioural repertoires support olfactory communication in wild capuchin monkeys

Olfaction is a key sense for many mammals, but its role in the social lives of anthropoid primates (monkeys, apes, humans) is poorly understood. Studies of chemosensory receptor genes and olfactory behaviours can provide insight into the evolution and function of olfaction across social contexts. Vomeronasal receptor (VR) genes are especially relevant to social behaviour as they are specialized for the detection of pheromones and other cues involved in social signaling, reproductive behaviour, and individual recognition in mammals. Here, we examined the population genetics and gene repertoires of VR genes in wild white-faced capuchin monkeys (Cebus imitator) from Costa Rica and Panama using DNA sourced through both host tissues and through noninvasive fluorescence-activated cell sorting of fecal samples (fecalFACS). We compared VR diversity relative to putatively neutral reference loci (NRs) to investigate evidence of selection and potential effects of demography. To complement the genetic analysis, we also conducted a detailed observational study of capuchin olfactory behaviours. Combined, we find evidence of intact VRs subject to evolutionary constraint in capuchins, providing novel evidence that members of this gene family are maintained by evolutionary constraint in wild monkeys. We further document a rich and varied ethogram of olfactory behaviours that have clear potential for communication. Overall, our study provides compelling evidence for a role of olfaction in the complex social lives of capuchin monkeys, motivating future research on the contributions of olfaction to social communication and evolution in primates and other mammals.

animal behavior and cognition↗

bioRxiv2026

Discovering genetic loci associated with rate of vegetative index gain using UAV-based phenomics in spring wheat

In wheat, the pre-heading stage determines spikelet formation, floret fertility, and canopy development, making it a critical window for early stress detection and yield potential. The genetic basis of pre-heading canopy development in wheat has remained constrained by the conventional phenotyping due to the low temporal resolution. Here, we quantified the rate of vegetation index gain (RVIs) during tillering to heading stages using UAV-mounted multispectral sensor in 196 spring wheat cultivars representing 112 years of breeding history. RVIs were calculated using six vegetation indices for consecutive two growing seasons, and genome wide association study (GWAS) was performed on RVIs, grain yield (GY) and thousand grain weight (TGW) using a wheat 37K SNP array. RVIs showed significant positive correlations with grain yield (r=0.28-0.43; p<0.001) and consistently increased in the modern cultivars compared to old cultivars. This indicated that resource remobilization during pre-heading canopy development significantly contributed to GY during modern wheat breeding. GWAS identified 67 loci, including 12 Group-I loci associated only with RVIs, and 18 Group-II loci associated with both RVIs and yield traits. Two stable loci on chr1B and chr5D consistently increased GY and RVIs across environments, and the tag SNPs were converted to selectable KASP markers. The allelic distribution on global wheat collection of [~]3000 accessions showcased that favorable alleles on both loci were dominant in cultivars compared to landraces. Similarly, favorable alleles showed more frequency in winter type than spring type. Across breeding eras both alleles showed increasing trend with chr5D reaching near fixation and chr1B remaining partially enriched in modern cultivars. Our work on capturing pre-heading canopy development, discovery of two stable loci underpinning yield and RVIs, and development of KASP markers provided a strong foundation to HTP assisted genetic dissection of GY and facilitated the understanding of canopy dynamics and yield formation.

plant biology↗

bioRxiv2025

Effects of hCG or GnRH Treatment on Embryonic Mortality and Reproductive Performance in Buchi sheep of Cholistan Desert, Pakistan

The present study was conducted on Buchi sheep at Government livestock farm, Jugaitpeer, district Bahawalpur. The objectives of this study were to investigates the genetic potential, birth and adult body weights, growth and turnover rates, and seasonal reproductive performance, the effect of Dalmazin (PGF2) on synchronization, the effect of GnRH and hCG treatment given on the mating day on pregnancy rate, and embryonic mortality after plasma hormone concentrations and embryo development to improve litter size. Male lambs exhibited significantly higher (P<0.05) birth (3.40 {+/-} 0.16 kg) and adult weights (61.67 {+/-} 0.95 kg) compared to females (3.00 {+/-} 0.00 kg and 39.67 {+/-} 0.41 kg, respectively), along with faster growth and higher turnover rates. Seasonal variations showed superior pregnancy rates in spring (62.83%) but higher reproductive efficiency and lower mortality in autumn. In a second experiment, 30 ewes divided into hCG, GnRH, and control groups. hCG and GnRH groups were mated to ram at synchronized estrus by two injections of 2ml PGF2 analogue (Dalmazin) given at 11 days apart. The control group received only saline. The blood samples were collected from jugular venipuncture (3ml) with a disposable syringe from day 2 to 16 after treatment. Plasma progesterone concentrations detected by ELISA were higher (P<0.05) in sheep as compared with saline treated controls and improved reproductive outcomes. The hCG group showed the best performance with a litter size of 1.28%, no embryonic mortality, and increased twinning and fecundity rates. The GnRH group also demonstrated enhanced reproductive efficiency with a litter size of 1.25% and no embryonic loss. The control group had the lowest reproductive outcomes, including a higher embryonic mortality rate. Overall, hCG proved more effective than GnRH in enhancing progesterone levels, fecundity, and prolificacy in Buchi sheep.

zoology↗

bioRxiv2023

Critical Behavioral Traits Foster Peer Engagement in Online Mental Health Communities

Online Mental Health Communities (OMHCs), such as Reddit, have witnessed a surge in popularity as go-to platforms for seeking information and support in managing mental health needs. Platforms like Reddit offer immediate interactions with peers, granting users a vital space for seeking mental health assistance. However, the largely unregulated nature of these platforms introduces intricate challenges for both users and society at large. This study explores the factors that drive peer engagement within counseling threads, aiming to enhance our understanding of this critical phenomenon. We introduce BeCOPE, a novel behavior encoded Peer counseling dataset comprising over 10,118 posts and 58,279 comments sourced from 21 mental health-specific subreddits. The dataset is annotated using three major fine-grained behavior labels: (a) intent, (b) criticism, and (c) readability, along with the emotion labels. Our analysis indicates the prominence of "self-criticism" as the most prevalent form of criticism expressed by help-seekers, accounting for a significant 43% of interactions. Intriguingly, we observe that individuals who explicitly express their need for help are 18.01% more likely to receive assistance compared to those who present "surveys" or engage in "rants." Furthermore, we highlight the pivotal role of well-articulated problem descriptions, showing that superior readability effectively doubles the likelihood of receiving the sought-after support. Our study emphasizes the essential role of OMHCs in offering personalized guidance and unveils behavior-driven engagement patterns.

neuroscience↗