Biology subjects

Sharif, B.

Publications and source records attributed to Sharif, B..

5 recordsLinked to original sources

bioRxiv2026

G-ALN: a GPU-accelerated BWA-aln algorithm for palaeogenomics

Abstract Summary: The most commonly used method to achieve optimal mapping for short and damaged ancient DNA (aDNA) reads is the BWA-aln algorithm with seeding disabled. However, this CPU-based algorithm is computationally demanding, as the aligner must tolerate mismatches and indels across the entire read. To improve alignment speed, we present G-ALN: a GPU implementation of the BWA-aln and indexing algorithms. G-ALN first searches all reads on GPU cores, with reads that need a long search being shared dynamically between the GPU and any spare CPU cores. Every read is searched using the same algorithm as BWA, so the output is byte-identical, which we confirmed here using woolly mammoth and Neanderthal datasets with aDNA-specific parameters. In our benchmarking, G-ALN indexed a reference genome ~32 times faster than BWA, and read alignment speed increased ~6-fold. G-ALN was developed through AI-assisted coding (Claude Opus 5.5). It processes thousands of reads in parallel on each GPU and aligns more than twice as many aDNA reads per unit of energy. These results show that G-ALN offers a practical route to using GPU resources in established aDNA analysis workflows. Availability and Implementation: G-ALN is implemented in C++ and CUDA and is freely available under the GPLv3 license at https://github.com/bilalbioinfo/galn. It requires an NVIDIA GPU with compute capability 7.0 or higher and CUDA 11.8 or later.

bioinformatics↗

bioRxiv2026

MitoDate: a Nextflow pipeline for molecular clock dating and phylogenetic inference using ancient mitogenomes

SummaryAncient DNA studies are increasingly targeting samples that are beyond the limit of radiocarbon dating (>50 thousand years old) and are often difficult or impossible to date using other geochronological methods. In cases where complete mitochondrial genomes (mitogenomes) can be recovered from such samples, Bayesian molecular clock dating approaches are routinely used as an alternative method for estimating their age. However, molecular clock dating of ancient mitogenomes lacks a standardised, reproducible computational framework, and existing approaches rely heavily on graphical interfaces that limit automation and scalability. To address these gaps, we developed MitoDate, an automated Nextflow pipeline for reproducible molecular clock dating of ancient mitochondrial genomes. The workflow standardises Bayesian time-calibrated phylogenetic inference within a portable, containerised framework, reducing manual intervention and improving analytical consistency. Availability and implementationMitoDate is implemented in Nextflow and is freely available at https://github.com/CpgSthlm/MitoDate. The pipeline is distributed with containerised dependencies and detailed documentation, including example datasets and usage guidelines.

bioinformatics↗

bioRxiv2026

DNAharvester: A Nextflow Pipeline for Analysing Highly Degraded DNA from Ancient and Historical Specimens

Ancient DNA (aDNA) research has advanced rapidly with the development of high-throughput sequencing, enabling genome-wide analyses of large collections of prehistoric specimens. However, analysing palaeontological and archaeological material with highly degraded DNA constitutes a major bioinformatic challenge. DNA from such samples is characterised by short fragment lengths, low endogenous content, post-mortem damage, and cross-species contamination, which can increase spurious mapping and reference bias, affecting downstream population genetic inferences. We present DNAharvester, a modular and reproducible pipeline designed specifically for processing highly degraded DNA from ancient and historical specimens. DNAharvester integrates metagenomic filtering, competitive mapping, adaptive aligner selection (incorporating BWA-aln, BWA-mem, and Bowtie2), and systematic evaluation of reference bias and spurious mapping. By incorporating flexible mapping and filtering strategies, the pipeline can be adapted to varying sample preservation, focusing on maximising authentic data recovery. DNAharvester features subworkflows for iterative assembly of mitogenomes, identification of genomic repeats and CpG sites, taxonomic classification, microbial/pathogen screening, genetic sex determination, and variant calling. To accommodate varying sequencing depths, the pipeline supports diploid variant calling, genotype likelihood estimation, and pseudo-haploid random allele calling. Implemented in Nextflow, DNAharvester provides a highly scalable, containerised framework that enhances reproducibility, portability, and robustness in aDNA analyses. We validated the pipeline using simulated and empirical datasets, demonstrating its ability to systematically mitigate complex background contamination while preserving authentic genomic signals. By streamlining complex bioinformatic tasks through simple configuration files, DNAharvester establishes a standardised approach for analysing aDNA datasets and makes genomic analyses of ancient remains accessible to the broader research community.

bioinformatics↗

bioRxiv2025

Microglia regulate neuronal activity via structural remodeling of astrocytes

Neuron-glia interactions play a central role in regulating synaptic transmission and neuronal excitability. Structural plasticity of astrocytes is associated with numerous physiological and pathological conditions, however, the mechanism underlying this process remains unknown. To examine the basis for structural astrocyte plasticity, we used the classic example of the loss of astrocytic processes that takes place in the hypothalamic magnocellular system during chronic high-salt intake. We discovered that a high-salt diet triggers a local accumulation of reactive microglia around vasopressin-secreting neurons, but not in other brain areas. Microglia phagocytose astrocytic processes, reducing astrocytic coverage of vasopressin neurons. The pruning of astrocytic processes impairs synaptic glutamate clearance, enabling activation of extrasynaptic glutamate NMDA receptors and increasing the activity of vasopressin neurons. Inhibiting microglia-mediated astrocyte pruning attenuates the increased neuronal activity and vasopressin-dependent hypertensive phenotype of rats fed high-salt diet. Thus, microglia orchestrate neuron-glia interactions and regulate neuronal activity through astrocyte pruning.

neuroscience↗

bioRxiv2023

Gut microbiota promotes pain in fibromyalgia

Fibromyalgia is a chronic syndrome characterized by widespread pain in the absence of evident tissue injury or pathology, making it one of the most mysterious chronic pain conditions. Despite affecting 2-4% of the population, primarily women1, the cause and underlying mechanisms of fibromyalgia remain elusive, and effective targeted treatments are currently unavailable. The gut microbiota of women with fibromyalgia differs from healthy controls2,3. However, it is unknown whether changes in gut microbiota have a causal role in mediating pain and other symptoms of fibromyalgia. Here, we show that fecal microbiota transplantation (FMT) from individuals with fibromyalgia, but not from healthy controls, into germ-free mice induces persistent pain hypersensitivity. FMT from fibromyalgia patients led to a reduction in intraepidermal nerve fiber density and alterations in the peripheral immune profile, and induced activation of spinal microglia, which contributed to the development of pain in mice. Notably, the pain hypersensitivity in mice that were administered microbiota from fibromyalgia patients resolved after FMT from healthy controls. Consistent with these findings, an open-label pilot study showed that transplanting microbiota from healthy individuals to humans with fibromyalgia alleviated pain and reduced overall symptom severity. Thus, altered gut microbiota has a causal role in fibromyalgia pain, highlighting it as a promising target for therapeutic interventions.

neuroscience↗