Stress response pathways in the male germ cells and gametes.

The unfolded protein response (UPR) is a conserved and essential cellular pathway involved in protein quality control that is activated in response to several cellular stressors such as diseases states, ageing, infection and toxins. The cytosol, endoplasmic reticulum (ER) and mitochondria are continuously exposed to new proteins and in situations of aberrant protein folding; one of three lines of defence may be activated: (i) heat-shock response, (ii) mitochondrial UPR and (iii) ER UPR. These pathways lead to different signal transduction mechanisms that activate or upregulate transcription factors that, in turn, regulate genes that increase the cell's ability to correct the conformation of poorly folded proteins or, ultimately, lead to apoptosis. Despite the recent progress in understanding such biological processes, few studies have focused on the implications of the UPR in male infertility, highlighting the need for a first approach concerning the presence of these components in the male reproductive system. In testis, there is a high rate of protein synthesis, and the UPR mechanisms are well described. However, the presence of these mechanisms in spermatozoa, apparently transcriptionally inactive cells, is contentious, and it is unclear how sperm cells deal with stress. Here, we review current concepts and mechanisms of the UPR and highlight the relevance of these stress response pathways in male fertility, especially the presence and functional activation of those components in male germinal cells and spermatozoa.

Digestibilidade aparente do farelo de palmiste em tambaqui (Colossoma macropomum) / Apparent digestibility of palm kernel meal to tambaqui (Colossoma macropomum)

O objetivo deste trabalho foi determinar a digestibilidade do farelo de palmiste (Elaeis guineensis) para o tambaqui (Colossoma macropomum), em duas classes de peso: 1 (210 alevinos de 4,45±1,18g) e 2 (54 juvenis de 115,91±4,01g). Os coeficientes de digestibilidade aparente (CDA) da matéria seca, proteína bruta e energia bruta do farelo de palmiste foram avaliados pela metodologia de substituição da dieta referência, utilizando-se 0,1% de óxido crômico como indicador externo. Os dados foram analisados pelo teste t de Student, a 5% de probabilidade. Os CDAs da matéria seca, proteína bruta e energia bruta do ingrediente foram iguais (P>0,05) nas classes de peso avaliadas. Os CDAs observados nas classes 1 e 2, respectivamente, foram: matéria seca (17,52% e 20,75%), proteína bruta (62,83% e 63,75%) e energia bruta (14,16% e 22,43%). A capacidade do tambaqui para digerir os nutrientes do farelo de palmiste não foi influenciada pelo peso corporal, e o aproveitamento satisfatório da proteína (63,29%) faz desse ingrediente uma potencial fonte alternativa de proteína em dietas para a espécie.(AU)

The objective of this work was to determine the digestibility of palm kernel meal (Elaeis guineensis) in tambaqui (Colossoma macropomum), in two weight classes: 1 (210 fingerlings of 4.45±1.18g) and 2 (54 juveniles of 115.91±4.01g). The apparent digestibility coefficients (ADC) of dry matter, crude protein and crude energy of the palm kernel meal were evaluated by the substitution of the reference diet methodology, using 0.1% chromic oxide as an external indicator. Data were analyzed by Student's t-test at 5% probability. The dry matter, crude protein and crude energy ADCs of the ingredient were the same (P> 0.05) in the weight classes evaluated. The ADCs observed in classes 1 and 2, respectively, were: dry matter (17.52% and 20.75%), crude protein (62.83% and 63.75%) and crude energy (14.16% and 22.43%). The ability of tambaqui to digest the nutrients of palm kernel meal was not influenced by body weight, and satisfactory protein utilization (63.29%) makes this ingredient a potential alternative source of protein in diets for the species.(AU)

Statistical, computational and visualization methodologies to unveil gene primary structure features.

OBJECTIVES: Gene sequence features such as codon bias, codon context, and codon expansion (e.g. trinucleotide repeats) can be better understood at the genomic scale level by combining statistical methodologies with advanced computer algorithms and data visualization through sophisticated graphical interfaces. This paper presents the ANACONDA system, a bioinformatics application for gene primary structure analysis. METHODS: Codon usage tables using absolute metrics and software for multivariate analysis of codon and amino acid usage are available in public databases. However, they do not provide easy computational and statistical tools to carry out detailed gene primary structure analysis on a genomic scale. We propose the usage of several statistical methods--contingency table analysis, residual analysis, multivariate analysis (cluster analysis)--to analyze the codon bias under various aspects (degree of association, contexts and clustering). RESULTS: The developed solution is a software application that provides a user-guided analysis of codon sequences considering several contexts and codon usage on a genomic scale. The utilization of this tool in our molecular biology laboratory is focused on particular genomes, especially those from Saccharomyces cerevisiae, Candida albicans and Escherichia coli. In order to illustrate the applicability and output layouts of the software these species are herein used as examples. CONCLUSIONS: The statistical tools incorporated in the system are allowing to obtain global views of important sequence features. It is expected that the results obtained will permit identification of general rules that govern codon context and codon usage in any genome. Additionally, identification of genes containing expanded codons that arise as a consequence of erroneous DNA replication events will permit uncovering new genes associated with human disease.