No Evidence of SARS-CoV-2 Infection in Neotropical Primates Sampled During COVID-19 Pandemic in Minas Gerais and Rio Grande do Sul,Brazil

EcoHealth - In 2019, a new coronavirus disease (COVID-19) was detected in China. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was capable to infect domestic and captive mammals like...     

A Passiflora homolog of a D-type cyclin gene is differentially expressed in response to sucrose, auxin, and cytokinin

In higher plants, one of the major components of developmental processes is cell division. The cell division cycle in plants is controlled by cyclins and cyclin-dependend kinases. Nutrient and hormonal signals can influence the roles that D-type cyclins play in the G1-to-S phase transition. Auxins and cytokinins are long known to be important plant hormones controlling plant growth. Additionally, as sucrose is the major transported carbon source in higher plants, it is possible that it plays a major role in cell division. To access the molecular aspects of the effect of auxin, cytokinin and sucrose on the regulation of cell cycle machinery and plant development, we cloned a Passiflora morifolia putative homolog to a D-type cyclin, PmCYCD1, which showed high sequence similarity to other known plant D-type cyclins. We examined the expression patterns of PmCYCD1 during callus induction and growth in in vitro conditions. We observed incremented expression levels of PmCYCD1 correlated to increasing concentrations of sucrose, α-naphthalene acetic acid and 6-benzyladenine in the culture medium. Additionally, the results of in situ hybridization experiments indicated a dynamic spatial expression pattern for PmCYCD1 during callus growth.     

Processes that drive the population structuring of Jenynsia lineata (Cyprinidontiformes,Anablepidae) in the La Plata Basin

1. The distribution of genetic diversity across a species distribution range is rarely homogeneous, as the genetic structure among populations is related to the degree of isolation among them, such as isolation by distance, isolation by barrier, and isolation by environment.
2. Jenynsia lineata is a small viviparous fish that inhabits a wide range of habitats in South America. To decipher the isolation processes that drive population structuring in J. lineata, we analyzed 221 sequences of the mitochondrial cytochrome c oxidase I gene (COI), from 19 localities. Then, we examined the influence of the three most common types of isolation in order to explain the genetic variation found in this species.
3. Our results revealed a marked structuration, with three groups: (a) La Plata/Desaguadero Rivers (sampling sites across Argentina, Uruguay, and Southern Brazil), (b) Central Argentina, and (c) Northern Argentina. A distance‐based redundancy analysis, including the explanatory variables geographical distances, altitude, latitude, and basin, was able to explain up to 65% of the genetic structure. A variance partitioning analysis showed that the two most important variables underlying the structuration in J. lineata were altitude (isolation by environment) and type of basin (isolation by barrier).
4. Our results show that in this species, the processes of population diversification are complex and are not limited to a single mechanism. The processes that play a prominent role in this study could explain the high rate of diversity that characterizes freshwater fish species. And these processes in turn are the basis for possible speciation events.

     

α,β-dicarbonyl reduction by Saccharomycesd-arabinose dehydrogenase

An α,β-dicarbonyl reductase activity was purified from Saccharomyces cerevisiae and identified as the cytosolic enzyme d-Arabinose dehydrogenase (ARA1) by MALDI-TOF/TOF. Size exclusion chromatography analysis of recombinant Ara1p revealed that this protein formed a homodimer. Ara1p catalyzed the reduction of the reactive α,β-dicarbonyl compounds methylglyoxal, diacetyl, and pentanedione in a NADPH dependant manner. Ara1p had apparent K_m values of ∼ 14 mM, 7 mM and 4 mM for methylglyoxal, diacetyl and pentanedione respectively, with corresponding turnover rates of 4.4, 6.9 and 5.9 s^− 1 at pH 7.0. pH profiling showed that Ara1p had a pH optimum of 4.5 for the diacetyl reduction reaction. Ara1p also catalyzed the NADP⁺ dependant oxidation of acetoin; however this back reaction only occurred at alkaline pH values. That Ara1p was important for degradation of α,β-dicarbonyl substrates was further supported by the observation that ara1-Δ knockout yeast mutants exhibited a decreased growth rate phenotype in media containing diacetyl.     

Linking human impacts to community processes in terrestrial and freshwater ecosystems

Human impacts such as habitat loss, climate change and biological invasions are radically altering biodiversity, with greater effects projected into the future. Evidence suggests human impacts may differ substantially between terrestrial and freshwater ecosystems, but the reasons for these differences are poorly understood. We propose an integrative approach to explain these differences by linking impacts to four fundamental processes that structure communities: dispersal, speciation, species-level selection and ecological drift. Our goal is to provide process-based insights into why human impacts, and responses to impacts, may differ across ecosystem types using a mechanistic, eco-evolutionary comparative framework. To enable these insights, we review and synthesise (i) how the four processes influence diversity and dynamics in terrestrial versus freshwater communities, specifically whether the relative importance of each process differs among ecosystems, and (ii) the pathways by which human impacts can produce divergent responses across ecosystems, due to differences in the strength of processes among ecosystems we identify. Finally, we highlight research gaps and next steps, and discuss how this approach can provide new insights for conservation. By focusing on the processes that shape diversity in communities, we aim to mechanistically link human impacts to ongoing and future changes in ecosystems.