Biology subjects

Sumitha, M. K.

Publications and source records attributed to Sumitha, M. K..

4 recordsLinked to original sources

bioRxiv2025

Genetic differentiation in Anopheles stephensi from India and Ethiopia: insights from mitochondrial genome analysis

Anopheles stephensi is a primary malaria vector, particularly in urban areas of South Asia and the Middle East. Its recent spread into Africa has raised significant interest in understanding its genetic structure and evolutionary history. This study presents a comprehensive analysis of 98 mitochondrial genomes of An. stephensi from India, Pakistan, and Ethiopia, providing critical insights into the species genetic diversity patterns. High genetic diversity was observed among Indian samples, with two distinct genetic ancestries identified. While one ancestry was more prevalent in specific geographical regions, both lineages were found across all study sites, suggesting the co-existence of multiple lineages within these areas. Further analysis revealed significant genetic differentiation between Indian and Ethiopian populations, with limited overlap in shared mutations. Although some Ethiopian samples showed genetic relatedness to the SDA500 strain from Pakistan (used in genome sequencing by the Broad Institute), the majority of Ethiopian samples showed distinct genetic ancestry. The distinctiveness of Ethiopian populations, compared to other countries outside of Africa, was also reflected in the COI datasets analyzed in this study. However, further expanding the mitogenome dataset to include additional wild samples from regions such as Pakistan, Iran, Saudi Arabia, Sri Lanka and other African countries will provide a more comprehensive understanding of An. stephensis invasion history. Overall, the findings of this study highlight the significant genetic differentiation between Ethiopian and Indian An. stephensi populations, and existence of multiple lineages in Ethiopia indicating multiple independent introductions from different countries.

zoology↗

bioRxiv2024

Whole mitochondrial genome analysis of Aedes aegypti reveal association with Wolbachia infection

The mitochondrial genomes (mitogenomes) of nine Aedes aegypti samples from India were analysed along with 34 mitogenomes from global samples retrieved from GenBank. The mitogenome size of Indian samples ranged from 15,730 bp to 16,374 bp. A total of 199 genetic variants were identified among Indian samples, with the majority (90%) occurring in protein-coding genes, followed by rRNA and tRNA genes. Phylogenetic analysis of the 43 genomes revealed two major clades. The similar clustering pattern was observed in the traditional mitochondrial markers for which extensive global data is available, indicating that individual mitochondrial markers of Ae. aegypti share the common genealogy as reflected by the complete mitogenome. In addition to exploring genetic diversity, we investigated the relationship of these two mitochondrial clades with Wolbachia infection. Our analysis revealed that Wolbachia-infected samples were predominantly located within one of the mitochondrial clades, suggesting a potential association between specific mitochondrial lineage and Wolbachia infection. This analysis demonstrates the extent of genetic diversity in Ae. aegypti mitogenome and highlights how this diversity is associated with Wolbachia infection, a maternally inherited endosymbiont. These findings have implications for the effectiveness of Wolbachia-based mosquito control strategies.

genomics↗

bioRxiv2024

Genetic diversity in the IIS6 domain of Voltage Gated Sodium Channel (VGSC) gene among Aedes aegypti populations from different geographical regions in India

This study provides critical insights into the genetic diversity of the IIS6 domain of the VGSC gene in Aedes aegypti populations across various regions in India, focusing on two mutations: S989P and V1016G. Samples were collected from seven different cities across the country, including Dibrugarh, Kolkata, Berhampur, Bhopal, Bengaluru, Ghaziabad, and Aurangabad. The IIS6 domain was amplified and sequenced, revealing that the V1016G mutation was found at a higher frequency compared to the S989P mutation. The S989P mutation was most prevalent in Berhampur, followed by Bengaluru, while V1016G mutation showed high frequencies in Dibrugarh, followed by Berhampur. Additionally, the study identified intron polymorphisms within the VGSC gene, with the type A intron being relatively rare. However, the type A intron was observed in samples harbouring both mutant and wild alleles for both mutations. The regional variation in the frequencies of these mutations indicates complex evolutionary dynamics potentially influenced by local environmental factors and insecticide application practices. Interestingly, the high frequency of these alleles also correlated with the genetic structure of the mosquito populations, suggesting that gene flow might be playing a role in spreading these mutations. Regular monitoring of these mutations could serve as important indicators in assessing the status of resistance to pyrethroids and guide nationwide mosquito control efforts. This research underscores the necessity for localized vector control strategies and continuous genetic surveillance to manage insecticide resistance effectively.

genetics↗

bioRxiv2024

Genome-wide variant analysis reveals divergent genetic signatures in Aedes aegypti and its morphological variant Aedes aegypti var. luciensis

In this study, we analysed the genetic diversity between the two morphotypes of Aedes aegypti by identifying and characterizing genomic variants from low-coverage resequencing data. Four samples from each morphotype were sequenced, and high-quality variants were identified. Variants from the four samples of each morphotype were combined, considering only those present in all samples (missing variants were excluded). This resulted in 7,181 variants in the normal type and 4,513 in the variant type, with only 1,180 shared variants identified between the two morphotypes. Most variants in both types were found in non-coding regions. Chromosomal distribution showed comparable variant frequencies between morphotypes, with similar transition/transversion ratios. The neighbor-joining tree indicated distinct genetic clusters for each morphotype, likely driven by different demographic histories. We have not obtained much data on variations in the coding regions, probably due to low sequencing coverage. However, the significant genetic differentiation between the two morphotypes indicates important evolutionary processes at play. Understanding these variations is crucial from an epidemiological perspective, as they may lead to differences in vector competence for pathogens, potentially affecting transmission dynamics and disease risk.

genomics↗