Aprendizaxe baseada en problemas en Xenética Molecular

[Resumo] A aprendizaxe baseada en problemas (ABP) trátase dunha metodoloxía na que os alumnos, guiados polo profesor, deben resolver un problema. No proceso, os alumnos constrúen e aplican coñecementos en lugar de ser meros receptores. Neste traballo, propoñemos aplicar ABP na materia Xenética Molecular do Grao en Bioloxía e do Programa de Simultaneidade do Grao en Bioloxía e o Grao en Química, impartidos na Facultade de Ciencias da UDC. O obxectivo é espertar un maior interese pola Bioinformática, unha parte da materia considerada a miúdo ardua e tediosa. Tamén pretendemos incrementar a orientación da materia cara á práctica profesional. A actividade que se propón consta de tarefas prácticas estruturadas, idénticas ás que se realizan nun laboratorio típico de Xenética Molecular. Así, o problema a resolver enfronta aos alumnos a unha situación real que implica non só aplicar coñecementos senón tamén tomar decisións. Para resolver o problema, os alumnos recibirán unha explicación previa do profesor e disporán de orientación mediante titorías e un foro en Moodle. A actividade desenvolverase en grupos de 4-5 alumnos. A aprendizaxe avaliarase en base á exposición oral apoiada nunha presentación Power Point que realice un membro do grupo elixido polo profesor e aos comentarios críticos que realicen os demais membros do grupo. Para organizar as titorías de avaliación, usarase a ferramenta Doodle. A actividade de ABP que se presenta contribuirá a desenvolver competencias recollidas na guía docente da materia e debería axudar aos alumnos a ver a relevancia do traballo realizado en Xenética Molecula

Structural analysis of mitochondrial rRNA gene variants identified in patients with deafness

The last few years have witnessed dramatic advances in our understanding of the structure and function of the mammalian mito-ribosome. At the same time, the first attempts to elucidate the effects of mito-ribosomal fidelity (decoding accuracy) in disease have been made. Hence, the time is right to push an important frontier in our understanding of mitochondrial genetics, that is, the elucidation of the phenotypic effects of mtDNA variants affecting the functioning of the mito-ribosome. Here, we have assessed the structural and functional role of 93 mitochondrial (mt-) rRNA variants thought to be associated with deafness, including those located at non-conserved positions. Our analysis has used the structural description of the human mito-ribosome of the highest quality currently available, together with a new understanding of the phenotypic manifestation of mito-ribosomal-associated variants. Basically, any base change capable of inducing a fidelity phenotype may be considered non-silent. Under this light, out of 92 previously reported mt-rRNA variants thought to be associated with deafness, we found that 49 were potentially non-silent. We also dismissed a large number of reportedly pathogenic mtDNA variants, 41, as polymorphisms. These results drastically update our view on the implication of the primary sequence of mt-rRNA in the etiology of deafness and mitochondrial disease in general. Our data sheds much-needed light on the question of how mt-rRNA variants located at non-conserved positions may lead to mitochondrial disease and, most notably, provide evidence of the effect of haplotype context in the manifestation of some mt-rRNA variants

Phylogenetic and Multivariate Analyses To Determine the Effects of Different Tillage and Residue Management Practices on Soil Bacterial Communities▿ †

Bacterial communities are important not only in the cycling of organic compounds but also in maintaining ecosystems. Specific bacterial groups can be affected as a result of changes in environmental conditions caused by human activities, such as agricultural practices. The aim of this study was to analyze the effects of different forms of tillage and residue management on soil bacterial communities by using phylogenetic and multivariate analyses. Treatments involving zero tillage (ZT) and conventional tillage (CT) with their respective combinations of residue management, i.e., removed residue (−R) and kept residue (+R), and maize/wheat rotation, were selected from a long-term field trial started in 1991. Analysis of bacterial diversity showed that soils under zero tillage and crop residue retention (ZT/+R) had the highest levels of diversity and richness. Multivariate analysis showed that beneficial bacterial groups such as fluorescent Pseudomonas spp. and Burkholderiales were favored by residue retention (ZT/+R and CT/+R) and negatively affected by residue removal (ZT/−R). Zero-tillage treatments (ZT/+R and ZT/−R) had a positive effect on the Rhizobiales group, with its main representatives related to Methylosinus spp. known as methane-oxidizing bacteria. It can be concluded that practices that include reduced tillage and crop residue retention can be adopted as safer agricultural practices to preserve and improve the diversity of soil bacterial communities

Genotype to phenotype: Diet-by-mitochondrial DNA haplotype interactions drive metabolic flexibility and organismal fitness.

Diet may be modified seasonally or by biogeographic, demographic or cultural shifts. It can differentially influence mitochondrial bioenergetics, retrograde signalling to the nuclear genome, and anterograde signalling to mitochondria. All these interactions have the potential to alter the frequencies of mtDNA haplotypes (mitotypes) in nature and may impact human health. In a model laboratory system, we fed four diets varying in Protein: Carbohydrate (P:C) ratio (1:2, 1:4, 1:8 and 1:16 P:C) to four homoplasmic Drosophila melanogaster mitotypes (nuclear genome standardised) and assayed their frequency in population cages. When fed a high protein 1:2 P:C diet, the frequency of flies harbouring Alstonville mtDNA increased. In contrast, when fed the high carbohydrate 1:16 P:C food the incidence of flies harbouring Dahomey mtDNA increased. This result, driven by differences in larval development, was generalisable to the replacement of the laboratory diet with fruits having high and low P:C ratios, perturbation of the nuclear genome and changes to the microbiome. Structural modelling and cellular assays suggested a V161L mutation in the ND4 subunit of complex I of Dahomey mtDNA was mildly deleterious, reduced mitochondrial functions, increased oxidative stress and resulted in an increase in larval development time on the 1:2 P:C diet. The 1:16 P:C diet triggered a cascade of changes in both mitotypes. In Dahomey larvae, increased feeding fuelled increased β-oxidation and the partial bypass of the complex I mutation. Conversely, Alstonville larvae upregulated genes involved with oxidative phosphorylation, increased glycogen metabolism and they were more physically active. We hypothesise that the increased physical activity diverted energy from growth and cell division and thereby slowed development. These data further question the use of mtDNA as an assumed neutral marker in evolutionary and population genetic studies. Moreover, if humans respond similarly, we posit that individuals with specific mtDNA variations may differentially metabolise carbohydrates, which has implications for a variety of diseases including cardiovascular disease, obesity, and perhaps Parkinson's Disease