No abstract

SUMMARYIn evolutionary physiology, studies of inter-individual variation (i.e. repeatability) in functional capacities are valuable as they indicate -within populations -what attributes could respond to natural selection. Although repeatability and quantitative genetics of physiological traits in energy metabolism of eutherian mammals have been well characterized, few or no studies have been performed on marsupials. We studied the repeatability (i.e. intraclass correlation coefficient, τ) of bioenergetics for Monito del Monte (Dromiciops gliroides), the sole living representative of an otherwise extinct marsupial order (Microbiotheria). We measured resting metabolic rate as CO 2 production (V CO2 ) and O 2 consumption (V O2 ) simultaneously, together with minimum thermal conductance (C), evaporative water loss (EWL) and respiratory quotient (RQ), in a sample of ca. 20 individuals. Our results suggest that D. gliroides exhibits poor control of body temperature (T b ), with a thermal amplitude of ca. 10°C in normothermia. As a consequence, repeatability of T b and metabolic rate (either as V CO2 or V O2 ) were relatively low (τ Tb =0.25±0.04, τ VCO2 =0.14±0.03, τ VO2 =0.24±0.02, jackknife estimations of standard errors). Thermal conductance exhibited near-zero or negative repeatability and was lower than expected for marsupials. However, we found significant repeatability for RQ and EWL (τ=0.32±0.03 and 0.49±0.09, respectively). In general, these results suggest that Monito del Monte exhibits some ʻreptilianʼ physiological characteristics. The relatively low repeatability of physiological variables, which otherwise exhibit large inter-individual and genetic variance in eutherian mammals, suggests that these capacities do not exhibit evolutionary potential in the ancient order Microbiotheria.

Plastic pollution levels have increased rapidly in recent years, due to the accumulation of plastic waste, including polyethylene terephthalate (PET). Both high production and the lack of efficient methods for disposal and recycling affect diverse aquatic and terrestrial ecosystems owing to the high accumulation rates of plastics. Traditional chemical and physical degradation techniques have caused adverse effects on the environment; hence, the use of microorganisms for plastic degradation has gained importance recently. This systematic review was conducted for evaluating the reported findings about PET degradation by wild and genetically modified microorganisms to make them available for future work and to contribute to the eventual implementation of an alternative, an effective, and environmentally friendly method for the management of plastic waste such as PET. Both wild and genetically modified microorganisms with the metabolic potential to degrade this polymer were identified, in addition to the enzymes and genes used for genetic modification. The most prevalent wild-type PET-degrading microorganisms were bacteria (56.3%, 36 genera), followed by fungi (32.4%, 30 genera), microalgae (1.4%; 1 genus, namely Spirulina sp.), and invertebrate associated microbiota (2.8%). Among fungi and bacteria, the most prevalent genera were Aspergillus sp. and Bacillus sp., respectively. About genetically modified microorganisms, 50 strains of Escherichia coli, most of them expressing PETase enzyme, have been used. We emphasize the pressing need for implementing biological techniques for PET waste management on a commercial scale, using consortia of microorganisms. We present this work in five sections: an Introduction that highlights the importance of PET biodegradation as an effective and sustainable alternative, a section on Materials and methods that summarizes how the search for articles and manuscripts in different databases was done, and another Results section where we present the works found on the subject, a final part of Discussion and analysis of the literature found and finally we present a Conclusion and prospects.

This work is part of a larger study whose main objective was to find a series of promising molecules to be used as glass-ionomer-type materials. The project was divided into 3 successive stages; the results of the first stage have been previously published and were used to continue the study. The molecules evaluated in the second stage were constructed by adding a glycidyl methacrylate molecule to the carboxylic groups of the polyacids selected in the previous stage. The modeling was done using the density functional theory for M06-2X/6-311G(d,p). The results indicate that the addition over the carboxylic groups of the fraction of the molecule, corresponding to itaconic acid, is thermodynamically favored. The final stage was modeled with the M06 functional and consisted of obtaining basic structures of glass-ionomer-type materials, by acid–base reaction between the molecules resulting from the second stage with individual ions of Ca (2 +), Zn (2 +), or Al (+ 3). It was concluded that aluminum atoms generate more compact structures that would correlate with more resistant materials.

REsuMEnIntroducción. El presente artículo muestra los resultados de una estrategia didáctica aplicada en una clase de Gestión Ambiental (GA) en el Instituto Tecnológico Metropolitano (ITM). Objetivo. Lograr en los estudiantes actitudes críticas y de apersonamiento frente a problemáticas ambientales locales. Metodología. Trabajo grupal sobre temas ambientales, expuestos en el aula de clase y orientados por la docente a partir de preguntas generadoras de polémicas. Resultados. Las temáticas más trabajadas y que generaron mayor polémica fueron manejo de residuos sólidos en barrios, y contaminación hídrica en quebradas municipales, ambas con un 23 % de ocurrencia. Conclusiones. Los estudiantes mostraron una mejora en cuanto a la capacidad de respuesta, coherencia de los argumentos, y análisis crítico de las problemáticas Artículo original / Original article / Artigo original