Comportamiento reproductivo y desarrollo de los estadios tempranos del bagre marino Aphos porosus, de la bahía de Valparaíso, Chile

Con el objetivo de estudiar el comportamiento reproductivo y describir los huevos y larvas del bagre Aphos porosus (Pisces: Batrachoididae), se realizaron observaciones durante 6 temporadas de desove en la zona intermareal rocoso de Montemar, bahía de Valparaíso, Chile. Se mantuvieron peces adultos en el laboratorio y se controló el desarrollo de huevos y larvas. También se realizó la fertilización artificial de huevos en el laboratorio. Se observó la llegada de los machos a la costa a partir de octubre, seguidos de las hembras en noviembre y diciembre de cada año. Los huevos fueron adheridos a las paredes verticales o inferiores de las piedras y grietas de las pozas del intermareal de Montemar y en las paredes de los estanques. Su diámetro fue de 5,3 ± 0,3 mm. La eclosión se produjo a los 18 d a 18,6°C y a los 21 d a 16,3°C. Las larvas recién eclosionadas midieron en promedio 4,8 mm de longitud total (LT) (rango entre 4,3 a 5,1 mm LT) y realizaron parte de su desarrollo adheridas al sustrato por el saco vitelino. Antes de consumir completamente el vitelo, las larvas ya presentaban el patrón de pigmentación y la forma del cuerpo similar a la de los juveniles. Al terminar de absorber el vitelo, las larvas midieron 20,5 a 24,0 mm LT y se liberaron del sustrato entre los 60 y 65 d de edad. Este trabajo constituye un aporte sobre aspectos no descritos del comportamiento reproductivo y la ontogenia de A. porosus, dentro del conjunto de especies de peces de la costa de Chil

Feeding ecology of fish larvae from Chilean Patagonia during austral winter

Feeding habits of the ichthyoplankton from Chilean Patagonia (44-46°30’S) were studied during June-July 2012 (austral winter). Ichthyoplankton assemblage was composed by 10 species, with low abundance (3.8 to 16.73 ind. 1000 m-3). Most abundant larvae were Maurolicus parvipinnis, Leptonotus blainvilleanus and Sprattus fuegensis. These three species fed mainly on calanoid copepodites, Paracalanus indicus and Calanus sp. copepodites, and cyphonautes. Trophic overlap among dominant fish larvae was high (Schoener’s D > 0.69) and no significant differences were detected in prey composition and size. Therefore, no resource partitioning occurred in planktonic fish larvae during winter 2012 in Chilean Patagonia

Updating known distribution models for forecasting climate change impact on endangered species

To plan endangered species conservation and to design adequate management programmes, it is necessary to predict their distributional response to climate change, especially under the current situation of rapid change. However, these predictions are customarily done by relating de novo the distribution of the species with climatic conditions with no regard of previously available knowledge about the factors affecting the species distribution. We propose to take advantage of known species distribution models, but proceeding to update them with the variables yielded by climatic models before projecting them to the future. To exemplify our proposal, the availability of suitable habitat across Spain for the endangered Bonelli’s Eagle (Aquila fasciata) was modelled by updating a pre-existing model based on current climate and topography to a combination of different general circulation models and Special Report on Emissions Scenarios. Our results suggested that the main threat for this endangered species would not be climate change, since all forecasting models show that its distribution will be maintained and increased in mainland Spain for all the XXI century. We remark on the importance of linking conservation biology with distribution modelling by updating existing models, frequently available for endangered species, considering all the known factors conditioning the species’ distribution, instead of building new models that are based on climate change variables only.Ministerio de Ciencia e Innovación and FEDER (project CGL2009-11316/BOS

Higher education students’ achievement emotions and their antecedents in e-learning amid COVID-19 pandemic: A multi-country survey

The outbreak of the COVID-19 pandemic has had a wide range of negative consequences for higher education students. We explored the generalizability of the control-value theory of achievement emotions for e-learning, focusing on their antecedents. We involved 17019 higher education students from 13 countries, who completed an online survey during the first wave of the pandemic. A structural equation model revealed that proximal antecedents (e-learning self-efficacy, computer self-efficacy) mediated the relation between environmental antecedents (cognitive and motivational quality of the task) and positive and negative achievement emotions, with some exceptions. The model was invariant across country, area of study, and gender. The rates of achievement emotions varied according to these same factors. Beyond their theoretical relevance, these findings could be the basis for policy recommendations to support stakeholders in coping with the challenges of e-learning and the current and future sequelae of the pandemic.info:eu-repo/semantics/publishedVersio

An integrated whole genome analysis of Mycobacterium tuberculosis reveals insights into relationship between its genome, transcriptome and methylome.

Human tuberculosis disease (TB), caused by Mycobacterium tuberculosis (Mtb), is a complex disease, with a spectrum of outcomes. Genomic, transcriptomic and methylation studies have revealed differences between Mtb lineages, likely to impact on transmission, virulence and drug resistance. However, so far no studies have integrated sequence-based genomic, transcriptomic and methylation characterisation across a common set of samples, which is critical to understand how DNA sequence and methylation affect RNA expression and, ultimately, Mtb pathogenesis. Here we perform such an integrated analysis across 22 M. tuberculosis clinical isolates, representing ancient (lineage 1) and modern (lineages 2 and 4) strains. The results confirm the presence of lineage-specific differential gene expression, linked to specific SNP-based expression quantitative trait loci: with 10 eQTLs involving SNPs in promoter regions or transcriptional start sites; and 12 involving potential functional impairment of transcriptional regulators. Methylation status was also found to have a role in transcription, with evidence of differential expression in 50 genes across lineage 4 samples. Lack of methylation was associated with three novel variants in mamA, likely to cause loss of function of this enzyme. Overall, our work shows the relationship of DNA sequence and methylation to RNA expression, and differences between ancient and modern lineages. Further studies are needed to verify the functional consequences of the identified mechanisms of gene expression regulation

Efectos ambientales sobre la variabilidad espacial del ictioplancton de Chile austral durante noviembre de 2005 Environmental effects on the spatial variability of the ichthyoplankton from southern Chile during November 2005

Se analiza la distribución y abundancia del ictioplancton de Chile austral (41-45° S) durante noviembre de 2005 en relación a las características oceanógraficas de la columna de agua (temperatura, salinidad y estratificación). Durante el periodo de estudio, se recolectó un total de 44.606 huevos de peces y 2.016 larvas correspondientes a 28 taxa. Los estados tempranos de peces pelágicos pequeños dominaron en las muestras, con densidades de ~ 14.000 huevos 10 m-2 de anchoveta (Engraulis ringens) y > 100 larvas 10 m-2 de clupeidos. Análisis multivariados indicaron la formación de dos grupos de estaciones, uno asociado a la zona de fiordos, de mayor profundidad, con fuertes gradientes verticales de temperatura y salinidad y mayor estratificación, y otro grupo asociado al borde oriental de la isla Chiloé, de menor profundidad y mayor mezcla en la columna de agua. En las zonas de mayor estratificación (Le., mayor frecuencia de Brunt-Váisála, N-2), se encontraron mayores densidades de huevos y larvas de peces pelágicos y mesopelágicos (Strangomera bentincki y Maurolicus parvipinnis). Al comparar esta información con un crucero oceanógrafico llevado a cabo 10 años antes en la misma zona (octubre de 1995), se detectaron cambios en la composición específica de ictioplancton, lo que puede indicar diferencias en las especies de peces marinos que utilizan la zona de fiordos y canales como área de desove y crianza larval.The distribution and abundance of ichthyoplankton from southern Chile (41-45°S) during November 2005 were analyzed, in relation to the oceanographic features of the water column (temperature, salinity, stratification). During the sampling period, 44.606 fish eggs and 2.016 fish larvae were collected, belonging to 28 taxa. Early life stages of small pelagic fishes dominated the plankton samples, with mean densities of ~ 14,000 eggs 10 m-2 of anchovy (Engraulis ringens) and > 100 larvae 10 m-2of clupleids. Multivariate analysis showed the conformation of two groups of stations, one associated to deeper fjord áreas, with strong vertical gradients of temperature and salinity, and higher stratification. The other group was associated to the shallow and well-mixed eastern border of Chiloé Island. In áreas with strong stratification (Le., higher Brunt-Váisála frequency, N²), significant higher densities of pelagic and mesopelagic fish eggs and larvae were collected (Le., Strangomera bentincki, Maurolicus parvipinnis). Comparing these results with an oceanographic cruise carried out 10 years before in the same área (October 1995), changes in the ichthyoplankton composition were detected; this may be caused by potential differences in the marine fish species which utilize fjords and channels of southern Chile as spawning and early nursery zone