Tozer, M. | bioRxiv Science

bioRxiv2026

Asparagine availability differentially regulates early vs late CD4+ and CD8+ T cell activation, metabolism and autophagy

T cell activation is associated with, and dependent upon, the upregulation of amino acid uptake from the extracellular environment. Uptake of the non-essential amino acid asparagine (Asn) is mediated via amino transporters such as Slc1a5 whilst Asn can be synthesized within cells that express asparagine synthetase (ASNS). Previous work demonstrated that initial activation of CD8+ T cells is perturbed in the absence of Asn, whereas effector cytotoxic T cells cells upregulate ASNS and lose their dependence on Asn uptake. By contrast, less is known of the role of Asn uptake and ASNS in CD4+ T cell responses. Here we demonstrate that CD4+ T cells are more reliant than CD8+ T cells on Asn uptake for initial activation, differentiation, metabolic reprogramming and regulation of autophagy. These phenotypes are associated with enhanced expression of ASNS in CD8+ as compared to CD4+ effector T cells.

immunology↗

bioRxiv2024

What we can find in what's left behind: DNA metabarcoding of semi-aquatic insect exuviae

Semi-aquatic insects contribute to critical ecological functioning of freshwater habitats in both the aquatic and terrestrial phase of their life. Traditional methods of studying their emergence rely on the capture of insects as they emerge, and morphological identification with taxonomic keys. This is not only time consuming but can have large impacts on the study population, obstacles that can be removed by the use of DNA. This study investigated the potential of using exuviae collected from the water surface as DNA source. Both emergence trap samples and insect exuviae were collected from a constructed wetland and a small creek in southern Ontario. Metabarcoding provided a total of 40 samples with 254 distinct taxa from emergence traps (26 samples), and 135 from exuviae (14 samples). There were many similarities between both two sample types, especially for the rich chironomid diversity. Nonetheless, the exuviae samples were able to identify more orders containing semi-aquatic insects. Furthermore, they showed a higher level of diversity within these orders. This higher level of diversity seen in exuviae samples may be due to limitations of emergence traps, such as they only account for a small defined surface area. In contrast, exuviae are representing a much larger area and are free floating, thus collection of emerging taxa is not limited to the emerging site. We were able to show that identification of emerging aquatic insects through metabarcoding of exuviae is a useful method for the study of insect emergence.

ecology↗