Cytoplasmic events in human meiotic arrest as revealed by immunolabelling of spermatocyte proacrosin

Abstract. Proacrosin appears in the Golgi complex as early as the mid-pachytene stage and immediately thereafter initiates partition to be equally distributed in sper-matids. The anti-proacrosin monoclonal antibody 4D4 (mAb 4D4) was used as a marker of these cytoplasmic events in ten men exhibiting spermatogenesis arrest in three specific stages: (i) leptotene/zygotene spermatocyte I with impaired chromosome pairing (six cases), (ii) early pachytene I (one case) and (iii) metaphase/anaphase I (three cases). Prophase arrest stages were identified on testis sections stained by silver nitrate. MAb 4D4 labelling revealed two types of leptotene/zygotene arrest depending on whether proacrosin was expressed or not. The data obtained enabled us to distinguish between: (i) nuclear blockages due to chromosome and/or nuclear matrix anomalies, when cytoplasmic events were either inhibited or not inhibited, and (ii) nuclear anomalies due to microtubular disturbances. In this latter case, cytokinesis was impaired as early as the prophase I, thus indicating a relationship between the Golgi partitioning and the microtubule network. Data show that meiotic arrest investigations, by means of an appropriate marker of the cytoplasmic events, provide valuable information on spermatogenic developmental processes.     

Degradation and fermentation of cellulose by the rumen anaerobic fungi in axenic cultures or in association with cellulolytic bacteria

Three rumen anaerobic fungi—Neocallinastix frontalis MCH3,Piromyces (Piromonas) communis FL, andCaecomyces (Sphaeromonas) communis FG10—were cultured on cellulose filter paper alone or in association with one of two rumen cellulolytic bacteria,Ruminococcus flavefaciens 007 andFibrobacter succinogenes S85. Cocultures ofN. frontalis orP. communis andR. flavefaciens were markedly less effective than the fungal monocultures in degrading cellulose but more effective than the bacterial monocultures.R. flavefaciens had an antagonistic effect against both of the fungal species. In contrast, no interaction was observed between the two fungal species andF. succinogenes. Cellulose was more effectively degraded by the cocultureC. communis-R. flavefaciens than by the corresponding fungal and bacterial monocultures. The effectiveness of degradation of the cocultureC. communis-F. succinogenes was comparable to that of the bacterial strains but greater than that of the fungi; no interaction was observed between these two microorganisms.     

Impact of phosphate concentration on the metabolome of biofilms of the marine bacterium Pseudoalteromonas lipolytica

Metabolomics - Recent advances in high-throughput methodologies in the ‘omics’ and synthetic biology fields call for rapid and sensitive workflows in the metabolic phenotyping of...     

Probability landscapes for integrative genomics

Background  

The comprehension of the gene regulatory code in eukaryotes is one of the major challenges of systems biology, and is a requirement for the development of novel therapeutic strategies for multifactorial diseases. Its bi-fold degeneration precludes brute force and statistical approaches based on the genomic sequence alone. Rather, recursive integration of systematic, whole-genome experimental data with advanced statistical regulatory sequence predictions needs to be developed. Such experimental approaches as well as the prediction tools are only starting to become available and increasing numbers of genome sequences and empirical sequence annotations are under continual discovery-driven change. Furthermore, given the complexity of the question, a decade(s) long multi-laboratory effort needs to be envisioned. These constraints need to be considered in the creation of a framework that can pave a road to successful comprehension of the gene regulatory code.     

Chromosomal patterns of gene expression from microarray data: methodology, validation and clinical relevance in gliomas

Background  

Expression microarrays represent a powerful technique for the simultaneous investigation of thousands of genes. The evidence that genes are not randomly distributed in the genome and that their coordinated expression depends on their position on chromosomes has highlighted the need for mathematical approaches to exploit this dependency for the analysis of expression data-sets.     

Susceptibility of Oryctes rhinoceros adults to Metarrhizium anisopliae

The susceptibility of Oryctes rhinoceros adults to infections due to entomopathogenic fungi (Beauveria bassiana, Beauveria tenella, Metarrhizium anisopliae, Paecilomyces fumoso-roseus, and Spicaria rileyi) was studied by spraying titrated spores suspensions on the insect integument. The results show a definite susceptibility of the adults to Metarrhizium anisopliae strains of the major type only.