Metabolic regulation of oocyte cell death through the CaMKII-mediated phosphorylation of caspase-2

Vertebrate female reproduction is limited by the oocyte stockpiles acquired during embryonic development. These are gradually depleted over the organism's lifetime through the process of apoptosis. The timer that triggers this cell death is yet to be identified. We used the Xenopus egg/oocyte system to examine the hypothesis that nutrient stores can regulate oocyte viability. We show that pentose-phosphate-pathway generation of NADPH is critical for oocyte survival and that the target of this regulation is caspase-2, previously shown to be required for oocyte death in mice. Pentose-phosphate-pathway-mediated inhibition of cell death was due to the inhibitory phosphorylation of caspase-2 by calcium/calmodulin-dependent protein kinase II (CaMKII). These data suggest that exhaustion of oocyte nutrients, resulting in an inability to generate NADPH, may contribute to ooctye apoptosis. These data also provide unexpected links between oocyte metabolism, CaMKII, and caspase-2.     

PERMANENT GENETIC RESOURCES: Twelve polymorphic microsatellite markers for the bonefish, Albula vulpes and two congeners

Twelve polymorphic microsatellite loci were isolated for the bonefish, Albula vulpes using a polymerase chain reaction‐based procedure. The number of alleles ranged from two to 23 (mean = 8.8) in 37 specimens from south Florida. Observed and expected heterozygosities ranged from 0.07 to 0.77 (mean = 0.42) and from 0.07 to 0.84 (mean = 0.48), respectively. There were no significant departures from Hardy–Weinberg equilibrium and no evidence of genotypic disequilibrium between any pair of loci. In a cross‐amplification test, all markers yielded appropriately sized alleles for specimens of the provisional Albula sp. B and 11 of the 12 loci amplified for those of Albula glossodonta.     

Development of 15 polymorphic microsatellite markers in the Atlantic tarpon (Megalops atlanticus) for capture-recapture studies

Fifteen polymorphic microsatellite DNA loci for Atlantic tarpon, Megalops atlanticus, were isolated by using PIMA, a polymerase chain reaction‐based technique. The number of alleles at each locus ranged from two to 24 (mean = 7.7) in 65 specimens from Tampa Bay, Florida. Observed and expected heterozygosities ranged from 0.27 to 0.92 (mean = 0.60) and from 0.28 to 0.95 (mean = 0.62), respectively. Genotypes at one locus deviated significantly from Hardy–Weinberg equilibrium. In exact tests for genotypic disequilibrium, there was no evidence of associations between any pair of loci. Overall, loci were well resolved and highly polymorphic, confirming their suitability for DNA fingerprinting applications and other genetic studies.     

Comparative study of a new composite biomaterial fluor-hydroxyapatite on fibroblast cell line NIH-3T3 by direct test

The number of biomaterials used in biomedical applications has rapidly increased in the past two decades. Fluorapatite (FA) is one of the inorganic constituents of bone or teeth used for hard tissue repairs and replacements. Fluor-hydroxyapatite (FHA) is a new synthetically prepared composite that in its structure contains the same molecular concentration of OH⁻ groups and F⁻ ions. The aim of this experimental investigation was to use the embryonal mouse fibroblast cell line NIH-3T3 for comparative study of basal cytotoxicity of fluoridated biomaterials FHA and FA discs. Hydroxyapatite (HA) disc, high-density polyethylene as negative control and polyvinyl chloride (PVC) containing organotin stabilizer as positive control were used as standard biomaterials. The appropriateness of the use of NIH-3T3 cells and their sensitivity for tested biomaterials were evaluated on the basis of five cytotoxic end points: cell proliferation, cell morphology, lactate dehydrogenase (LDH) released, protein and DNA cell content. The basal cytotoxicity of FHA, FA and HA discs was measured by direct contact method. FHA composite, FA and HA demonstrated in cell line NIH-3T3 nearly similar basal cytotoxicity increasing with the time of treatment. After 72 h of biomaterials treatment, about 25% inhibition of cell number, unchanged morphology of dividing cells, 6.31–0.16% increase of released LDH, about 10% inhibition of cell protein content and about 20% inhibition of DNA content was found. On the other hand, from the growth rates it resulted that NIH-3T3 cells, affected by tested biomaterials, divided about 20% slowlier than the control (untreated cells). Using the linear regression analysis we found out that deviations in measurements of cytotoxicity by four methods were as follows: less than 10% for cell number, protein and DNA content methods and 12.4% for released LDH method. Based on a good correlation of the cytotoxicity of biomaterials obtained from all end points we could conclude that fibroblast NIH-3T3 cell line was appropriate for measuring the basal cytoxicity of tested biomaterials.     

Sphecid wasps (Hymenoptera: Apoidea: Sphecidae) as potential control agents of acridid pests (Orthoptera: Acrididae) in Ethiopia

The possibility of using sphecid wasps to control acridid pests is discussed. A list of 19 Ethiopian species that could be utilized for this purpose is provided.     

Modern science and the explosion of new knowledge

The technological evolution of mankind accelerated enormously after the institutionalization of science in the 19th century. In parallel with the vast number of beneficial effects derived from the scientific revolution, the explosion of new knowledge and its centralization in only a few countries has generated a number of complex situations that present major challenges for the modern science. These include the asymmetrical distribution in the planet of young people and science, the super-specialization derived from the information overload and the difficulties in teaching the vast amount of new knowledge generated each year by science.     

Modeling human muscle disease in zebrafish

Zebrafish reproduce in large quantities, grow rapidly, and are transparent early in development. For these reasons, zebrafish have been used extensively to model vertebrate development and disease. Like mammals, zebrafish express dystrophin and many of its associated proteins early in development and these proteins have been shown to be vital for zebrafish muscle stability. In dystrophin-null zebrafish, muscle degeneration becomes apparent as early as 3 days post-fertilization (dpf) making the zebrafish an excellent organism for large-scale screens to identify other genes involved in the disease process or drugs capable of correcting the disease phenotype. Being transparent, developing zebrafish are also an ideal experimental model for monitoring the fate of labeled transplanted cells. Although zebrafish dystrophy models are not meant to replace existing mammalian models of disease, experiments requiring large numbers of animals may be best performed in zebrafish. Results garnered from using this model could lead to a better understanding of the pathogenesis of the muscular dystrophies and the development of future therapies.     

Cdc2 and Mos regulate Emi2 stability to promote the meiosis I-meiosis II transition

The transition of oocytes from meiosis I (MI) to meiosis II (MII) requires partial cyclin B degradation to allow MI exit without S phase entry. Rapid reaccumulation of cyclin B allows direct progression into MII, producing a cytostatic factor (CSF)-arrested egg. It has been reported that dampened translation of the anaphase-promoting complex (APC) inhibitor Emi2 at MI allows partial APC activation and MI exit. We have detected active Emi2 translation at MI and show that Emi2 levels in MI are mainly controlled by regulated degradation. Emi2 degradation in MI depends not on Ca(2+)/calmodulin-dependent protein kinase II (CaMKII), but on Cdc2-mediated phosphorylation of multiple sites within Emi2. As in MII, this phosphorylation is antagonized by Mos-mediated recruitment of PP2A to Emi2. Higher Cdc2 kinase activity in MI than MII allows sufficient Emi2 phosphorylation to destabilize Emi2 in MI. At MI anaphase, APC-mediated degradation of cyclin B decreases Cdc2 activity, enabling Cdc2-mediated Emi2 phosphorylation to be successfully antagonized by Mos-mediated PP2A recruitment. These data suggest a model of APC autoinhibition mediated by stabilization of Emi2; Emi2 proteins accumulate at MI exit and inhibit APC activity sufficiently to prevent complete degradation of cyclin B, allowing MI exit while preventing interphase before MII entry.     

Immunological characteristics associated with the protective efficacy of antibodies to ricin

A/B toxins, produced by bacteria and plants, are among the deadliest molecules known. The B chain binds the cell, whereas the A chain exerts the toxic effect. Both anti-A chain and anti-B chain Abs can neutralize toxins in vivo and in vitro. B chain Abs block binding of the toxin to the cell. It is not known how anti-A chain Abs function. Working with ricin toxin, we demonstrate that immunization with A chain induces greater protection than immunization with B chain. A panel of mAbs, binding to A chain, B chain, or both chains, has been produced and characterized. Immunologic characteristics evaluated include isotype, relative avidity, and epitope specificity. The ability to inhibit ricin enzymatic or cell binding activity was studied, as was the ability to block ricin-mediated cellular cytotoxicity on human and murine cell lines. Finally, the in vivo protective efficacy of the Abs in mice was studied. The Ab providing the greatest in vivo protective efficacy was directed against the A chain. It had the greatest relative avidity and the greatest ability to block enzymatic function and neutralize cytotoxicity. Interestingly, we also obtained an anti-A chain Ab that bound with high avidity, blocked enzymatic activity, did not neutralize cytotoxicity, and actually enhanced the in vivo toxicity of ricin. Anti-A chain Abs with moderate avidity had no in vivo effect, nor did any anti-B chain Abs.