Biology subjects

Ajay, A.

Publications and source records attributed to Ajay, A..

3 recordsLinked to original sources

bioRxiv2026

Independent evolutionary trajectories of genomic repeats and non-repeat genome features in Actinomycetota

Genomic repeats, particularly simple sequence repeats, influence genome stability and gene regulation. While many genomic traits exhibit phylogenetic signal and pulsed evolution, repeat elements have rarely been examined in a comparative framework, and their evolutionary relationships with other genome features remain poorly understood. We contrasted the trait evolution of genomic repeats with non-repeat traits across diverse actinobacterial orders, testing for phylogenetic signal, evolutionary mode, and pulsed dynamics using time-calibrated, 16S rRNA, and whole-genome sequence (WGS) trees. Non-repeat traits consistently exhibited signs of punctuated evolution, with larger pulses in species-rich orders such as Mycobacteriales and Actinomycetales; repeats, by contrast, were evolutionarily labile, lacking phylogenetic signal and largely decoupled from other genomic traits. Bifidobacteriales was the sole exception, with repeats exhibiting phylogenetic signal only under the WGS tree. The WGS tree also recovered a stronger signal for genome-level traits, highlighting its utility in comparative analyses. Genome size evolution in Actinomycetota appears driven primarily by protein-coding gene expansion rather than repeat accumulation.

evolutionary biology↗

bioRxiv2025

The Duality of Insect Macroevolution: Pulsed Genomes and Gradual Morphology Shape Lineage Diversification

Insects, comprising over half of all known species, are pivotal to ecosystems and ideal for studying trait evolution due to their morphological and genomic diversity. Yet, the macroevolutionary interplay between their phenotypic traits and genomic architecture is poorly resolved. Using a Tree of Life framework and phylogenetic comparative methods, we investigated the evolutionary dynamics of morphological and genomic traits across multiple insect orders with trait-specific taxonomic sampling optimized for data availability. Critically, while traditional metrics showed no correlation between species richness and evolutionary mode, the pattern of pulsed evolution revealed a clear macroevolutionary signal. Morphological diversification tended towards gradualism, whereas genomic evolution was predominantly pulsed. Notably, this pulsed signal manifested differently: large morphological pulses were associated with species-poor clades like Odonata, while species-rich clades exhibited major pulses in genome size. These results demonstrate that interpreting pulsed evolutions contribution to diversification requires careful consideration of both trait identity and phylogenetic context. Further, for both morphological and genomic traits, the degree of phylogenetic conservatism was independent of the evolutionary distance between orders.

evolutionary biology↗

bioRxiv2020

Green tea and Spirulina extracts inhibit SARS, MERS, and SARS-2 spike pseudotyped virus entry in vitro

Coronaviruses (CoVs) infect a wide range of animals and birds. Their tropism is primarily determined by the ability of the spike (S) protein to bind to a host cell surface receptor. The rapid outbreak of emerging novel coronavirus, SARS-CoV 2 in China inculcates the need for the development of hasty and effective intervention strategies. Medicinal plants and natural compounds have been traditionally used to treat viral infections. Here, we generated VSV based pseudotyped viruses (pvs) of SARS-, MERS-, and SARS-2 CoVs to screen entry inhibitors from natural products. In the first series of experiments, we demonstrated that pseudotyped viruses specifically bind on their receptors and enter into the cells. SARS and MERS polyclonal antibodies neutralize SARSpv and SARS-2pv, and MERSpv respectively. Incubation of soluble ACE2 inhibited entry of SARS and SARS-2 pvs but not MERSpv. In addition, expression of ACE2 and DPP4 in non-permissive BHK21 cells enabled infection by SARSpv, SARS-2pv, and MERSpv respectively. Next, we showed the antiviral properties of known enveloped virus entry inhibitors, Spirulina and Green tea extracts against CoVpvs. SARSpv, MERSpv, and SARS-2pv entry were blocked with higher efficiency when preincubated with either green tea or spirulina extracts. Green tea provided a better inhibitory effect than the spirulina extracts by binding to the S1 domain of spike and blocking the interaction of spike with its receptor. Further studies are required to understand the exact mechanism of viral inhibition. In summary, we demonstrate that pseudotyped virus is an ideal tool for screening viral entry inhibitors. Moreover, spirulina and green tea could be promising antiviral agents against emerging viruses.

microbiology↗