In most eukaryotic cells mitochondria are essential organelles involved in a great variety of cellular functions. One of the physiological processes linked to mitochondria is aging, a gradual process of damage accumulation that eventually promotes cell death. Aging depends on a balance between mitochondrial biogenesis, function and degradation. It has been previously shown that Tor1, Sch9 and Ras2 are activated in response to nutrient availability and regulate cell growth and division. A deficiency in any of these genes promotes lifespan extension and cell protection during oxidative and heat shock stress. In this work we report that in Saccharomyces cerevisiae, the uncharacterized mitochondrial protein Slm35 is functionally linked with the TOR signaling pathway. A Δtor1Δslm35 strain shows a severe decrease in lifespan and is unable to contend with oxidative and heat shock stresses. Specifically, this mutant shows decreased catalase activity indicating a misregulation of ROS scavenging mechanisms. In this study we show that Slm35 is also relevant for mitochondrial network dynamics and mitophagy. The results presented here suggest that Slm35 plays an important role connecting mitochondrial function with cytosolic responses and cell adaptation to stress and aging.

Worldwide, one in every three species of amphibian is endangered, 39 species have gone extinct in the last 500 years and another 130 species are suspected to have gone extinct in recent decades. Of the amphibians, salamanders have the highest portion of their species in one of the risk categories, even higher than the frogs. To date there have been few studies that have used recent field data to examine the status of populations of endangered salamanders. In this study we evaluate the current situation of two tiny salamanders, Parvimolge townsendi and Thorius pennatulus, both of which are distributed at intermediate elevations in the mountains of the northern Neotropics and are considered to be critically endangered; the first has been proposed as possibly extinct. By carrying out exhaustive surveys in both historical and potentially suitable sites for these two species, we evaluated their abundance and the characteristics of their habitats, and we estimated their potential geographic distribution. We visited 22 sites, investing 672 person-hours of sampling effort in the surveys, and found 201 P. townsendi salamanders in 11 sites and only 13 T. pennatulus salamanders in 5 sites. Both species were preferentially found in cloud forest fragments that were well conserved or only moderately transformed, and some of the salamanders were found in shade coffee plantations. The potential distribution area of both species is markedly fragmented and we estimate that it has decreased by more than 48%. The results of this study highlight the importance of carrying out exhaustive, systematic field surveys to obtain accurate information about the current situation of critically endangered species, and help us better understand the crisis that amphibians are facing worldwide.

The Uxpanapa-Chimalapas region, with one of the most extensive and best preserved tropical forest areas in Mexico, is undergoing major anthropogenic changes, and only some portions of the territory are under the protection of local communities. Although the biodiversity of the region is known to be high, no study has yet analyzed the diversity of amphibian species in the region or contributed to valuing the region in a context of amphibian conservation. Based on a review of databases and the existing scientific literature, as well as our own fieldwork, in this study, we analyze the amphibian species richness, species composition, their spatial distribution, and their conservation status in the Uxpanapa-Chimalapas region. Additionally, we compare this information with the available data for seven other tropical regions in central-northern Mesoamerica. The amphibian fauna recorded at the study region comprises 51 species, which makes it the richest tropical region in amphibian species in central-northern Mesoamerica and Mexico. Among the regions compared, this one stands out as the one with the most distinctive composition of amphibian species, sharing on average only 35% of its species with the other regions. However, it is also the region with the highest number of threatened species since one third of its species are in higher extinction risk categories. These characteristics turn the Uxpanapa-Chimalapas into a high-priority region for both Mexico and Mesoamerica, and a regional conservation plan is necessary for the immediate protection of areas where the forest is being replaced and to promote or to support community protected areas.

β-diversity has been under continuous debate, with a current need to better understand the way in which a new wave of measures work. We assessed the results of 12 incidence-based β-diversity indices. Our results of gradual species composition overlap between paired assemblages considering progressive differences in species richness show the following: (i) four indices (β-2, β-3, β-3.s, and βr) should be used cautiously given that results with no shared species retrieve results that could be misinterpreted; (ii) all measures conceived specifically as partitioned components of species compositional dissimilarities ought to be used as such and not as independent measures per se; (iii) the non-linear response of some indices to gradual species composition overlap should be interpreted carefully, and further analysis using their results as dependent variables should be performed cautiously; and (iv) two metrics (βsim and βsor) behave predictably and linearly to gradual species composition overlap. We encourage ecologists using measures of β-diversity to fully understand their mathematical nature and type of results under the scenario to be used in order to avoid inappropriate and misleading inferences.

La composición de la dieta en anfibios puede ser influenciada por diversos factores que causan su variación intraespecífica, como pueden ser la distribución geográfica, ontogenia, estacionalidad, y el sexo de los organismos. El objetivo de este estudio fue analizar la composición de la dieta en adultos de la Craugastor rhodopis (rana hojarasquera común) en la región montañosa del centro de Veracruz, México. Un total de 77 individuos adultos fueron colectados durante la época de lluvias de 2012, de los cuales 66 tuvieron contenido estomacal. Se realizó un análisis de la variación intersexual en la diversidad de la dieta, y el volumen, número de presas, y número de categorías de presa consumidas. La dieta de C. rhodopis estuvo compuesta por 20 categorías, de las cuales predominó Orthoptera en cuanto a número, volumen, frecuencia de ocurrencia e importancia relativa. Los machos consumieron presas de menor tamaño en relación a las hembras. Aunque ambos sexos consumieron similar número de presas, se encontró un efecto significativo de la interacción del sexo y el tamaño de las ranas sobre esta variable de la dieta, en la cual las hembras pequeñas consumen más presas que las grandes, y los machos grandes consumen más presas que los pequeños. El alto consumo de ortópteros (al menos en cuanto a volumen) es un fenómeno común dentro de la familia Craugastoridae y posiblemente está relacionado con el éxito de algunas especies en los ecosistemas donde habitan. A pesar de que la composición de la dieta fue similar entre sexos en C. rhodopis, se sugiere que la competencia intersexual por los recursos tróficos es mínima, dadas las diferencias en el tamaño de presas consumidas por machos y hembras.