Meiotic characterization and sex determination system of neotropical primates: Bolivian squirrel monkey Saimiri boliviensis (primates: Cebidae)

The chromosomal sex determination system differs among platyrrhine monkeys more than any other group of primates. Although a number of studies have investigated mitotic chromosomes across platyrrhine species, the meiotic chromosomes of many genera have not yet been described. The goal of this study was to characterize the sex determination system of Saimiri boliviensis. We described for the first time the meiotic cycle, confirming the sexual system in germ cells from testicular biopsies of four adult male S. boliviensis. All specimens were weighed and testicular volume was measured. We observed 22 bivalents corresponding to 2N = 44, and a "human-like" XY bivalent was found in diakinesis/metaphase I. In addition, mitotic studies from blood samples of both sexes were performed and G- and C-banding patterns agreed with previously reported karylogy of S. boliviensis boliviensis. Further meiotic studies should be performed in New World primates based on the great value of those studies for systematic evolutionary biology and conservation programs.     

ASB-1, a germline-specific isoform of mitochondrial ATP synthase b subunit, is required to maintain the rate of germline development in Caenorhabditis elegans

The developmental timing of all types of cells must be synchronized and spatially coordinated to achieve the organized development of a multicellular organism. Previously, we found RNAi of asb-1, encoding a germline-specific isoform of mitochondrial ATP synthase b subunit, caused 100% penetrant sterility in Caenorhabditis elegans. ATP synthase is one of the five complexes of the mitochondrial respiratory chain, and defects in some of the components of the chain are known to slow the growth and extend the lifespan of worms. We found that development of asb-1 mutant germ line was not arrested at any stage, but did slow to half the rate of wild type, whereas the rate of somatic development was the same in asb-1 mutants as that of wild type, indicating that asb-1 is required to maintain the rate of germline development but has no effect on somatic development. Among ATP synthase subunit genes, RNAi of asg-1, encoding a germline-specific isoform of the g subunit, also caused asb-1-like sterility, indicating that some other germline-specific components are also required to maintain the rate of germline development. Both asb-1 and asg-1 are located on autosomes while they possess counterparts, asb-2 and asg-2, respectively, on X chromosome, which are both required for somatic development. Chromosomal locations of the genes may be the basis of the segregation of germline/somatic functions of each gene, as were demonstrated for other autosomal/X-linked duplicated gene pairs.     

Brefeldin A or monensin inhibits the 3D organizer in gastropod,polyplacophoran, and scaphopod molluscs

In molluscs, the 3D vegetal blastomere acts as a developmental signaling center, or organizer, and is required to establish bilateral symmetry in the embryo. 3D is similar to organizing centers in other metazoans, but detailed comparisons are difficult, in part because its organizing function is poorly understood. To elucidate 3D function in a standardized fashion, we used monensin and brefeldin A (BFA) to rapidly and reversibly interfere with protein processing and secretion, thereby inhibiting the signaling interactions that underlie its specification and patterning. In the gastropods, Patella vulgata and Lymnaea stagnalis, the polyplacophoran, Mopalia muscosa, and the scaphopod, Antalis entalis, treatments initiated before the organizer-dependent onset of bilateral cleavage resulted in radialization of subsequent development. In radialized P. vulgata, L. stagnalis, and M. muscosa, organizer specification was blocked, and embryos failed to make the transition to bilateral cleavage. In all four species, the subsequent body plan was radially symmetric and was similarly organized about a novel aboral–oral axis. Our results demonstrate that brefeldin A (BFA) and monensin can be used to inhibit 3D’s organizing function in a comparative fashion and that, at least in M. muscosa, the organizer-dependent developmental architecture of the embryo predicts subsequent patterns of morphogenetic movements in gastrulation and, ultimately, the layout of the adult body plan.     

Study on nuclear and cytoplasmic genome expression in wheat by two-dimensional gel electrophoresis

Summary Two-dimensional gel electrophoresis of denaturated proteins were performed at five developmental stages or organs (hereafter referred to as stage-organs) on two wheat lines with four different cytoplasms. Five hundred and fifty to 712 reproducible spots were scored depending on the stage-organ. Each stage-organ is unambiguously characterized and several types of control of protein quantity are recorded. Post-translational modifications are hypothetized and may sometimes be stagespecific. Two cytoplasmic patterns are found: one for the euplasmic lines with Triticum aestivum cytoplasm and one for the alloplasmic lines with Aegilops juvenalis, Ae. ventricosa and Ae. kotschyi cytoplasms. Cytoplasmic variation is observed for 28 spots showing position difference, all of which are probably products of the LS gene, and for four spots showing differences for regulation of protein quantity. Nuclear variation between Chinese Spring and Selkirk is found for 20 allelic differences and for 20 regulatory systems, the latter number being probably underestimated.     

An Interaction Network of RNA-Binding Proteins Involved in Drosophila Oogenesis

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Highlights

• •Label-free and dimethyl labeling MS analysis of 6 RBPs from Drosophila ovaries.
• •Functionally related RBPs show overlapping proteomes.
• •Selective co-purification of splicing factors and translational regulators.
• •Validation of 26 novel interactions by co-immunoprecipitation.

     

Hepatocyte-specific Ablation in Zebrafish to Study Biliary-driven Liver Regeneration

The liver has a great capacity to regenerate. Hepatocytes, the parenchymal cells of the liver, can regenerate in one of two ways: hepatocyte- or biliary-driven liver regeneration. In hepatocyte-driven liver regeneration, regenerating hepatocytes are derived from preexisting hepatocytes, whereas, in biliary-driven regeneration, regenerating hepatocytes are derived from biliary epithelial cells (BECs). For hepatocyte-driven liver regeneration, there are excellent rodent models that have significantly contributed to the current understanding of liver regeneration. However, no such rodent model exists for biliary-driven liver regeneration. We recently reported on a zebrafish liver injury model in which BECs extensively give rise to hepatocytes upon severe hepatocyte loss. In this model, hepatocytes are specifically ablated by a pharmacogenetic means. Here we present in detail the methods to ablate hepatocytes and to analyze the BEC-driven liver regeneration process. This hepatocyte-specific ablation model can be further used to discover the underlying molecular and cellular mechanisms of biliary-driven liver regeneration. Moreover, these methods can be applied to chemical screens to identify small molecules that augment or suppress liver regeneration.     

Astyanax hastatus Myers, 1928 (Teleostei,Characidae): A new species complex within the genus Astyanax?

Four populations of Astyanax hastatus Myers 1928 from the Guapimirim River basin (Rio de Janeiro State) were analyzed and three distinct cytotypes identified. These cytotypes presented 2n = 50 chromosomes, with 4M+8SM+10ST+28A (Cytotype A), 8M+10SM+14ST+18A (Cytotype B), 6M+8SM+4ST+32A (Cytotype C) and scanty heterochromatin, mainly located throughout pericentromeric regions of several chromosomal pairs. No homologies with the As-51 satellite DNA were observed in the three cytotypes, although all of them presented multiple 18S rDNA sites, as detected by both silver nitrate staining and FISH (fluorescent in situ hybridization). The application of the term "species complex" in Astyanax is discussed from a cytotaxonomic viewpoint.     

Neurotoxicity of 2,4-dichlorophenoxyacetic butyl ester in chick embryos

Fertilized hens' eggs were externally treated, before starting incubation, with a single dose of 2,4-Dichlorophenoxyacetic butyl ester (2,4-D b.e., 3.1 mg/egg). Chicks at different developmental stages were examined, extending from 10 day embryos to one day after hatching. Previously, we demonstrated that 2,4-D b.e. produces hypomyelination in chicks born from treated eggs. In search of the causes of this hypomyelination, myelin markers such as sulphatides, cerebrosides and 2 3-cyclic nucleotide 3-phosphohydrolase (CNPase) activity, as well as protein and nucleic acid contents were determined in the embryonic brains. We have shown in the present study that the chemical alterations occurred even before the period of active myelination, since myelin appears in chicken brain stem and cerebrum approximately after 17 days of incubation, and most of the chemical parameters studied are diminished before that time. The DNA content in brain of treated group is increased from the 14^th embryonic day (with a transient diminution at 12^th day) to the first hatching day, when compared to the control, suggesting a proliferation of glial cells, possibly oligodendrocytes.     

In vitro morphogenesis of arrested embryos from lethal mutants of Arabidopsis thaliana

Summary Arrested embryos from lethal (emb) mutants of Arabidopsis thaliana were rescued on a nutrient medium designed to promote plant regeneration from immature wild-type cotyledons. The best response was observed with mutant embryos arrested at the heart to cotyledon stages of development. Embryos arrested at a globular stage produced callus but failed to turn green or form normal shoots in culture. Many of the mutant plants produced in culture were unusually pale with abnormal leaves, rosettes, and patterns of reproductive development. Other plants were phenotypically normal except for the presence of siliques containing 100% aborted seeds following self-pollination. These results demonstrate that genes with essential functions during plant embryo development differ in their pattern of expression at later stages of the life cycle. Most of the 15 genes examined in this study were essential for embryogenesis but were required again for subsequent stages of development. Only EMB24 appeared to be limited in function to embryo development. These differences in the response of mutant embryos in culture may facilitate the classification of embryonic lethals and the identification of genes with developmental rather than housekeeping functions.     

厩真厉螨的生物学特性

厩真厉螨的生活史分五期:卵、幼虫、一期若虫、二期若虫和成虫。产卵极少且无生活力,以卵胎生为主,产幼虫或一期若虫。整个成虫期均有交配行为,未见孤雌生殖。该螨幼虫期有效积温常数11.53日度,发育起点6.27℃;一期若虫有效积温常数38.87日度,发育起点9.36℃;二期若虫有效积温常数48.14日度,发育起点7.92℃。最适温度在20—25℃间。