Biology subjects

Rehan, S.

Publications and source records attributed to Rehan, S..

4 recordsLinked to original sources

bioRxiv2026

Chromosome-level genome and caste transcriptomes for Africa's most widespread social wasp (Belonogaster juncea) reveal unexpected genomic diversity

Belonogaster is an African genus of primitively eusocial wasps. They are widespread and conspicuous across sub-Saharan Africa and yet are among the least studied groups of social wasps. Here, we present the first high-quality, chromosome-level genome assembly for a representative of this genus, Belonogaster juncea, complemented by an RNA-seq analysis of brain transcription among individuals representing reproductive and non-reproductive castes. The assembled genome spans 315.8 Mb with a scaffold N50 of 7.91 Mb. The annotation contained 15,159 protein-coding genes and 20,046 isoforms, with Benchmarking Universal Single-Copy Orthologs (BUSCO) completeness of 98.0% for the genome and 97.8% for the annotation. Using this new assembly, we show that the B. juncea genome differs notably from other social wasp genomes: a single satellite repeat makes up a fifth of its chromosome-scale sequence, it has the highest putative chromosome number in a sequenced wasp genome to date, and it shows high levels of syntenic breaks. We find caste neuro-transcription differences between queens and workers, revealing 573 differentially expressed genes (341 worker biased, 232 queen biased), with significant overlap in caste-specific genes when compared to Polistes dominula and Liostenogaster flavolineata. This genomic resource provides a foundation for understanding the molecular mechanisms underlying primitive eusociality and social evolution in wasps, and opens up new research opportunities for a genus of little-studied insects from the Global South.

genomics↗

bioRxiv2025

Oxidative Stress in two pollinators from Different Landscapes based on different pesticide residue profiles

Oxidative stress (OX) is a state of imbalance between antioxidants and reactive oxygen species, which are the byproducts of oxidative phosphorylation in the mitochondria. Different landscapes: conventional, organic, and roadside use different pesticides and pest control management practices pest control. The roadside landscape is a control for minimum application of herbicides and management. Two important pollinators, honey bees (Apis mellifera) and small carpenter bees (Ceratina calcarata) are studied here for their abiotic stress from different landscape. It is unknown whether the differences in these landscapes affect the oxidative stress of these two pollinators. Conventional farms offer the most exposure to pesticides, which have been related to increased stress levels. We hypothesized that honey bees and small carpenter bees (SCB) from conventional farms would experience the highest levels of OX. Results from the lipid assay indicated that honey bees and SCB of organic and roadside landscapes experienced the lowest and highest OX levels. The results of the protein carbonyl assay indicated a significant difference found between conventional and organic bees (p < 0.05), based on Tukeys post-hoc test. Previous research has shown that feral bees have a tolerance to high stress levels. The same could be true of honey bees and SCB from roadside landscapes, where the conditions imitate natural habitats. Organic farms use naturally derived pesticides and moderate management practices, likely contributing to their lower levels. Examining how these pollinators are affected by different farm landscapes can reveal the benefits and detriments of their corresponding management practices. This will lead to streamlined practices that are healthier for pollinators.

physiology↗

bioRxiv2022

Molecular view of ER membrane remodeling by the Sec61/TRAP translocon

Protein translocation across the endoplasmic reticulum (ER) membrane is an essential initial step in protein entry into the secretory pathway. The conserved Sec61 protein translocon facilitates polypeptide translocation and coordinates cotranslational polypeptide processing events. In cells, the majority of Sec61 is stably associated with a heterotetrameric membrane protein complex, the translocon associated protein complex (TRAP), yet the mechanism by which TRAP assists in polypeptide translocation or cotranslational modifications such as N-glycosylation remains unknown. Here, we demonstrate the structure of the core Sec61/TRAP complex bound to a mammalian ribosome by Cryo-EM. The interactions with ribosome anchor the Sec61/TRAP complex in a conformation that renders the ER membrane locally thinner by significantly curving its the lumenal leaflet. We propose a model for how TRAP stabilizes the ribosome exit tunnel to assist nascent polypeptide insertion through Sec61 and provides a ratcheting mechanism into the ER lumen by direct polypeptide interactions.

biochemistry↗

bioRxiv2022

Signal peptide mimicry primes Sec61 for client-selective inhibition

Preventing the biogenesis of disease-relevant proteins is an attractive therapeutic strategy, but attempts to target essential protein biogenesis factors have been hampered by excessive toxicity. Here, we describe KZR-8445, a cyclic depsipeptide that targets the Sec61 translocon and selectively disrupts secretory and membrane protein biogenesis in a signal peptide-dependent manner. KZR-8445 potently inhibits the secretion of proinflammatory cytokines in primary immune cells and is highly efficacious in a mouse model of rheumatoid arthritis. A cryo-EM structure reveals that KZR-8445 occupies the fully opened Se61 lateral gate and blocks access to the lumenal plug domain. KZR-8445 binding stabilizes the lateral gate helices in a manner that traps select signal peptides in the Sec61 channel and prevents their movement into the lipid bilayer. Our results establish a framework for the structure-guided discovery of novel therapeutics that selectively modulate Sec61-mediated protein biogenesis.

biochemistry↗