Biology subjects

de Silva, N.

Publications and source records attributed to de Silva, N..

4 recordsLinked to original sources

bioRxiv2024

Exploring the uncharted: Novel potential filariasis vectors unveiled in Sri Lanka

Brugian filariasis (BF) has reemerged in Sri Lanka recently. Studies suggest the emergence of a variant brugian parasite. Knowledge on transmission dynamics is important in restraining the spread of infection. This study investigated the potential vector mosquitoes of this variant brugian parasite around six indexed human BF cases in five BF endemic districts in Sri Lanka. A total of 1711 mosquitoes from 20 species were analyzed. Potential infective mosquitoes were detected by the presence of L3 larval stage of brugian parasites within the head and thorax regions upon dissections and confirmed by amplification of the Brugia species-specific HhaI region. Twelve (12) mosquito species that could potentially serve as vectors for BF transmission in selected endemic areas in the country were identified due to the presence of L3 larvae in the head and thorax regions. This is the first report of Ma. indiana, Ar. subalbatus, Ae. albopictus, Cq. crassipes, Cx. tritaeniorhynchus, Cx. bitaeniorhynchus, Cx. quinquefasciatus, Cx. gelidus, Cx. lopoceraomyia and Cx. vishnui with the potential of serving as vectors for BF transmission in Sri Lanka and Cx. bitaeniorhynchus, Cx. gelidus, Cx. lopoceraomyia and Cx. vishnui in the world through a field study. Of these, Ma. indiana, Cx. tritaeniorhynchus, Cx. quinquefasciatus and Ar. subalbatus together with Ma. uniformis, Ma. annulifera had the highest prevalence and infection rate at certain study sites. The recovery of parasite-positive Ma. indiana, Cx. quinquefasciatus and Ar. subalbatus mosquitoes from window traps demonstrate the probable anthropophilic nature of these species, and their high prevalence in the respective areas deems further investigation on their vector potentiality essential. Author SummaryLymphatic filariasis (LF) is a debilitating disease affecting over 120 million people worldwide. Of the two types of LF, Brugian Filariasis (BF) has a wide range of definitive hosts, making it possible for the rapid spread of the disease. BF was considered eliminated from Sri Lanka in 1969 but is on the rise after four decades of quiescence. Effective vector control is an integral part of infection control. We carried out entomological investigations for potential vectors of re-emerged BF in five BF-endemic areas in Sri Lanka. Here we report Ma. indiana, Cx. tritaeniorhynchus, Cx. bitaeniorhynchus, Cx. quinquefasciatus, Cx. gelidus, Cx. lopoceraomyia, Cx. vishnui, Ar. subalbatus, Ae. albopictus and Cq. crassipes with the potential to serve as vectors for BF transmission in Sri Lanka due to the presence of L3 larvae in the head and thorax regions and Cx. bitaeniorhynchus, Cx. quinquefasciatus, Cx. gelidus, Cx. lopoceraomyia and Cx. vishnui in the world. The high prevalence and infection rate of Ma. indiana, Cx. quinquefasciatus and Ar. subalbatus mosquitoes and their anthropophagic nature in certain BF endemic areas are worrisome. This study emphasizes the importance of a comprehensive analysis of BF vectors for vector control strategies tailored to each region and season.

zoology↗

bioRxiv2024

Human Vascularized Macrophage-Islet Organoids to Model Immune-Mediated Pancreatic β cell Pyroptosis upon Viral Infection

There is a paucity of human models to study immune-mediated host damage. Here, we utilized the GeoMx spatial multi-omics platform to analyze immune cell changes in COVID-19 pancreatic autopsy samples, revealing an accumulation of proinflammatory macrophages. Single cell RNA-seq analysis of human islets exposed to SARS-CoV-2 or Coxsackievirus B4 (CVB4) viruses identified activation of proinflammatory macrophages and {beta} cell pyroptosis. To distinguish viral versus proinflammatory macrophage-mediated {beta} cell pyroptosis, we developed human pluripotent stem cell (hPSC)-derived vascularized macrophage-islet (VMI) organoids. VMI organoids exhibited enhanced marker expression and function in both {beta} cells and endothelial cells compared to separately cultured cells. Notably, proinflammatory macrophages within VMI organoids induced {beta} cell pyroptosis. Mechanistic investigations highlighted TNFSF12-TNFRSF12A involvement in proinflammatory macrophage-mediated {beta} cell pyroptosis. This study established hPSC- derived VMI organoids as a valuable tool for studying immune cell-mediated host damage and uncovered mechanism of {beta} cell damage during viral exposure.

developmental biology↗

bioRxiv2024

GATA6 regulates WNT and BMP programs to pattern precardiac mesoderm during the earliest stages of human cardiogenesis

Haploinsufficiency for GATA6 is associated with congenital heart disease (CHD) with variable comorbidity of pancreatic or diaphragm defects, although the etiology of disease is not well understood. Here, we used cardiac directed differentiation from human embryonic stem cells (hESCs) as a platform to study GATA6 function during early cardiogenesis. GATA6 loss-of-function hESCs had a profound impairment in cardiac progenitor cell (CPC) specification and cardiomyocyte (CM) generation due to early defects during the mesendoderm and lateral mesoderm patterning stages. Profiling by RNA-seq and CUT&RUN identified genes of the WNT and BMP programs regulated by GATA6 during early mesoderm patterning. Furthermore, interactome analysis detected GATA6 binding with developmental transcription factors and chromatin remodelers suggesting cooperative regulation of cardiac lineage gene accessibility. We show that modulating WNT and BMP inputs during the first 48 hours of cardiac differentiation is sufficient to partially rescue CPC and CM defects in GATA6 heterozygous and homozygous mutant hESCs. This study provides evidence of the regulatory functions for GATA6 directing human precardiac mesoderm patterning during the earliest stages of cardiogenesis to further our understanding of haploinsufficiency causing CHD and the co-occurrence of cardiac and other organ defects caused by human GATA6 mutations.

developmental biology↗

bioRxiv2024

Atacama Clear for Complex 3D Imaging of Organs

3-dimensional (3D) imaging is a powerful tool for interrogation of intact tissues, but can suffer from poor resolution due to impediments such as high tissue autofluorescence that remains a significant challenge in imaging cleared samples, including human clinical specimens. We developed Atacama Clear (ATC), a 3D imaging technology that increases signal-to-noise ratios (SNRs) while simultaneously augmenting the capacity of tissue to be cleared. ATC exhibited SNRs that are up to 200% of widely used 3D imaging methods, potentiated all tested optical clearing solutions by up to 600%, decreased the time of optical clearing by up to a factor of 8, and enabled detection of poorly recognized antigens with a remarkable 4-fold increase in signal detection while using up to 10-fold lower antibody concentrations. Strikingly, ATC produced up to a 5x increase in transgenic fluorescent reporter protein signal detection, which is instead often diminished with currently used 3D imaging methods. This increased imaging efficacy enabled multiplex interrogation of tough fibrous tissue and specimens that naturally exhibit high levels of background noise, including the heart, kidney, and human biopsies. Indeed, ATC facilitated the use of AI based auto-segmentation with simple low tech stereo fluorescence microscopy, visualization of previously undocumented adjacent nephron segments that exhibit notoriously high autofluorescence, elements of the cardiac conduction system, and distinct human glomerular tissue layers, with cellular resolution. Taken together, these studies establish ATC as a platform for complex 3D imaging studies of basic and clinical specimens with superior resolution.

molecular biology↗