Kadambi, N. | bioRxiv Science

bioRxiv2026

Differences in functional guild responses to elevation and topography in Himalayan ant communities

We investigated the influence of small-scale topographic and associated microclimatic drivers on the elevational patterns of functional alpha and beta diversity in ant communities of eastern Himalayas. Ants were sampled along three elevational transects spanning [~]1000-2000 m on two nearby mountain slopes, but differing in aspect, inclination and summit height. Ant genera were quantified at the quadrat level, yielding an abundance of 3090 genus-quadrats (from 22577 individuals in 1215 quadrats), almost evenly split between the two mountain slopes. Each ant was assigned to guilds along functional axes of thermal niche, trophic position and competitive abilities. Comparative analyses of functional diversity profiles along the two mountain slopes revealed no differences in the composite multi-guild alpha and beta diversity but significant differences amongst individual guild profiles. Seven of the eleven functional guilds showed strong elevational trends along the steeper north-facing slope, compared to only two of eleven on the shallower south-facing slope. These results indicate that similar functional space can be maintained despite taxonomic turnover within guilds or shifts in their relative abundances highlighting the influence of fine-scale topographic variation on community assembly. Alternatively, these findings demonstrate that the pattern of multivariate functional diversity across elevation does not necessarily provide an understanding of changing composition of the communities therein.

ecology↗

bioRxiv2020

The deacylase SIRT5 supports melanoma viability by regulating chromatin dynamics

Cutaneous melanoma remains the most lethal skin cancer, and ranks third among all malignancies in terms of years of life lost. Despite the advent of immune checkpoint and targeted therapies, only roughly half of patients with advanced melanoma achieves a durable remission. SIRT5 is a member of the sirtuin family of protein deacylases that regulate metabolism and other biological processes. Germline Sirt5 deficiency is associated with mild phenotypes in mice. Here we show that SIRT5 is required for proliferation and survival across all cutaneous melanoma genotypes tested, as well as uveal melanoma, a genetically distinct melanoma subtype that arises in the eye and is incurable once metastatic. Likewise, SIRT5 is required for efficient tumor formation by melanoma xenografts and in an autochthonous mouse Braf;Pten-driven melanoma model. Via metabolite and transcriptomic analyses, we find that SIRT5 is required to maintain histone acetylation and methylation levels in melanoma cells, thereby promoting proper gene expression. SIRT5-dependent genes notably include MITF, a key lineage-specific survival oncogene in melanoma, and the c-MYC proto-oncogene. SIRT5 may represent a novel, druggable genotype-independent addiction in melanoma.

cancer biology↗