Biology subjects

Robles, C.

Publications and source records attributed to Robles, C..

4 recordsLinked to original sources

bioRxiv2022

Urbanisation impacts the diversity, coloration, and body size of wild bees in a Mediterranean city

Urbanisation is a growing phenomenon causing the decline of wild bees globally. Yet, bees manage to persist in the urban matrix thanks to islands of vegetation in public parks and private gardens. While we begin to comprehend the impact of urbanisation on bees diversity and abundance, our understanding of its impact on the functional diversity of wild bees is limited. Here, we use an integrative approach to investigate the response of wild bees to urbanisation at the community, species, and individual levels. To do so, we sampled wild bees in 24 public parks along an urbanisation gradient in the Mediterranean city of Marseille. We found that species richness and abundance decreased in more urbanised areas, but increased in larger city parks. Moreover, larger individuals within species, but not larger species, were found in larger city parks, suggesting that park size is crucial for the persistence of bees in cities. Interestingly, we show that brighter species were found in parks surrounded by a large amount of impervious surface, highlighting the importance of colour traits in the response to environmental changes. Finally, our results revealed that larger species, but not larger individuals, were also more colourful. In summary, our study not only confirmed that urbanisation negatively impacts community-level traits, but that it also affects species coloration and individuals body size, thus improving our understanding of the functional response of wild bees to urbanisation. We suggest that increasing park size may compensate for the negative effects of urbanisation on wild bees.

ecology↗

bioRxiv2022

Functional unknomics: closing the knowledge gap to accelerate biomedical research

The human genome encodes [~]20,000 proteins, many still uncharacterised. Scientific and social factors have resulted in a focus on well-studied proteins, leading to a concern that poorly understood genes are unjustifiably neglected. To address this, we have developed an "Unknome database" that ranks proteins based on how little is known about them. We applied RNAi in Drosophila to 260 unknown genes that are conserved between flies and humans. About a quarter are required for viability, and functional screening of the rest revealed hits for fertility, development, locomotion, protein quality control and resilience to stress. CRISPR/Cas9 gene disruption validated a component of Notch signalling and two genes contributing to male fertility. Our work demonstrates the importance of poorly understood genes, provides a resource for future research acceleration, and highlights a need for our awareness of ignorance to be protected from erosion by automated database annotation.

molecular biology↗

bioRxiv2022

The lingering effects of Neanderthal introgression on human complex traits

The mutations introduced into the ancestors of modern humans from interbreeding with Neanderthals have been suggested to contribute an unexpected extent to complex human traits. However, testing this hypothesis has been challenging due to the idiosyncratic population genetic properties of introgressed mutations. We developed rigorous methods to assess the contribution of introgressed Neanderthal mutations to heritable trait variation relative to that of modern human variants. We applied these methods to analyze 235,592 introgressed Neanderthal mutations and 96 distinct phenotypes measured in about 300,000 unrelated white British individuals in the UK Biobank. Introgressed Neanderthal mutations have a significant contribution to trait variation consistent with the polygenic architecture of complex phenotypes (contributing 0.1% of heritable variation averaged across phenotypes; p = 9.59x10-9). However, the contribution of introgressed mutations tends to be significantly depleted relative to modern human mutations matched for allele frequency and linkage disequilibrium (about 57% depletion on average), consistent with purifying selection on introgressed mutations. Different from previous studies (McArthur 2021), we find no evidence for elevated heritability across the phenotypes examined. We identified 348 independent significant associations of introgressed Neanderthal mutations with 64 phenotypes (p < 1 x10-10). Previous work (Skov 2021) has suggested that a majority of such associations are likely driven by statistical association with nearby modern human variants that are the true causal variants. We therefore developed a customized statistical fine-mapping methodology for introgressed mutations that led us to identify 112 regions (at a false discovery proportion of 16%) across 47 phenotypes containing 4,303 unique genetic variants where introgressed mutations are highly likely to have a phenotypic effect. Examination of these mutations reveal their substantial impact on genes that are important for the immune system, development, and metabolism. Our results provide the first rigorous basis for understanding how Neanderthal introgression modulates complex trait variation in present-day humans.

genetics↗

bioRxiv2021

Green synthesis of silver nanoparticles using psychrotolerant strains of Tulasnella albida from South Orkney Islands (Antarctica)

Nanoparticles are widely studied due to their possible uses in biological and technological systems. Four psychrotolerant strains of Tulasnella albida isolated from Antarctica were tested and compared in their ability to synthesize silver nanoparticles. The four strains were capable of synthesizing silver nanoparticles with the addition of AgNO3 (final concentration of 0.5 mM), showing similar results under the same conditions: 28{degrees}C, 200 rpm, pH 9. Additionally, we registered the synthesis of nanoparticles at 6{degrees}C using biomass generated at the same temperature. For the characterization of synthesized nanoparticles, TEM and SEM microscopy analyses were performed. The images obtained showed the existence of spherically shaped silver nanoparticles with a log-normal size distribution centered at 2 nm diameter for 28{degrees}C. The largest ones showed a capping shell around them, appearing associated with the formation of small silver nanoparticles. Theoretical calculations of optical absorption based on core-shell Ag-Ag2O nanoparticles were used to characterize the experimental absorption spectra of silver nanoparticles colloids. This work contributes to expanding the studies and possible technological applications of psychrotolerant organisms in the industry, particularly in the green synthesis of nanoparticles at suboptimal conditions.

bioengineering↗