An increase in nitric oxide produced by rat peritoneal neutrophils is not involved in cell apoptosis

Polymorphonuclear neutrophils (PMN) obtained from carrageenin-stimulated peritoneal cavities of rats, but not blood PMN, spontaneously produced nitric oxide (NO) when incubated in vitro. Incubation of the cells with the NO synthase inhibitors, L-imino-ethyl-L-ornithine (L-NIO) or N(G)-monomethyl-L-arginine (L-NMMA), inhibited NO production. This inhibition could be reversed by L-arginine. Incubation of PMN with lipopolysaccharide (LPS) failed to enhance NO production. Pretreatment of the rats with dexamethasone (DEXA) prior to carrageenin injection or incubation of PMN with the glucocorticoid in vitro partially inhibited the spontaneous release of NO. On the other hand, when PMN obtained from DEXA pretreated rats were incubated in vitro with DEXA, NO synthase activity and hence NO generation were almost abolished. A similar inhibition was also observed following the addition of L-NIO or cycloheximide to cultures of carrageenin-elicited PMN. The NO production by PMN did not appear to be related to cell viability or apoptosis. Indeed, neither the blockade of NO generation by L-NIO nor the incubation of the neutrophils with a NO donor, S-nitroso-acetylpenicillamine (SNAP) modified the pattern of LDH release or DNA fragmentation. In summary, it appears that PMN migration triggers a continuous NO synthesis, and that NO produced by these cells is not related to their apoptosis.     

Nuclear behaviour during ascus formation in Saccharomyces rosei (Guilliermond) Lodder et Kreger-van Rij

Stained cells of Saccharomyces rosei prepared from 4 to 10-day-old cultures were studied under the light microscope. Mitotic and meiotic divisions involving a ring-like structure as well as preceding and subsequent stages were observed. Cells presenting supernumerary mitoses in a varying number were frequent. These mitoses, having terminated their multiplication activity, suspended the process shortly before its conclusion and, in a development which was identical at all, assumed a curious arrangement forming a mitoses-ring. Meiosis-buds were detected. These especial buds, where karyogamy and meiosis took place, resulted from the development of the mitoses-ring, whose mitoses upon resuming their activity moved toward the cell wall giving rise to the appearance of these appendices. Each one of these buds received the corresponding pair of daughter nuclei, diploidization occurring subsequently. Meiosis was usually processed in a single bud (effective-meiosis-bud) and all four meiotic nuclei migrated to the mother cell, and gave rise to a tetra-nucleate spore or binucleate spores if two were formed.Other modalities of sporulation were observed. These may result either from the association of two cells, in which one assumed the function of meiosis-bud (false-meiosis-bud), or from a cell association in which this function was performed for several linearly arranged cells forming a protuberance.Conjugation between mother cell and an attached bud, or between independent cells, was not observed.     

Pre-column derivatization of free bile acids for high-performance liquid chromatographic and gas chromatographic—mass spectrometric analysis

Pentachlorophenyl (PCP) esters of five free bile acids (FBA) were obtained by reacting the FBA and Kovacs' complex (KC) in a 1:8 molar ratio in acetone at 65°C, and were purified by column chromatography on silica gel. The esters were crystallized from benzene—hexane, derivatized as trimethylsilyl ethers for gas chromatography on a DB-1 capillary column and for gas chromatography—mass spectrometry with a DB-5 column, and mass spectrometry (MS) in the electron-impact (EI) positive-ion mode at 70 eV. The reaction is specific for FBA even in the presence of glycine and taurine conjugates of bile acids. The PCP esters were treated with benzylamine in chloroform or methanol to produce N-benzyl derivatives of FBA. The N-benzylamides were separated by high-performance liquid chromatography (HPLC) on a 4-μm Nova-Pak C₁₈ column, studied by thermospray—LC—MS, and in the direct insertion probe—EI positive-ion mode.     

Evolution des activités protéolytiques digestives chez les Jeunes Mulgilidae

Proteolytic activity in the stomach, pyloric caeca and intestine decreases with increasing size in the three fish species Mugil auratus, M. capito and M. saliens. Differences between these species are found mainly in the gastric proteolytic activity which appears to be related to diet. This activity is pronounced in M. saliens whose diet is mainly carnivorous. Comparison of regression lines relating gastric proteolytic activity to size reveals differences which distinguish M. auratus from both of the other species. Total proteolytic activity exhibits high variability depending on the types of diet.     

Reconfiguration of a Multi-oscillator Network by Light in the Drosophila Circadian Clock

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Lipid content and apoptosis of in vitro-produced bovine embryos as determinants of susceptibility to vitrification

The objective was to evaluate supplementation of fetal calf serum (FCS) and phenazine ethosulfate (PES), a metabolic regulator that inhibits fatty acid synthesis, in culture media during in vitro production (IVP) of bovine embryos. Taking oocyte fertilization (n = 4,320) as Day 0, four concentrations of FCS (0, 2.5, 5, and 10%) and three periods of exposure to PES (without addition—Control; after 60 h—PES Day 2.5 of embryo culture; and after 96 h—PES Day 4) were evaluated. Increasing FCS concentration in the culture media enhanced lipid accumulation (P < 0.05), increased apoptosis in fresh (2.5%: 19.1 ± 1.8 vs 10%: 28.4 ± 2.3, P < 0.05; mean ± SEM) and vitrified (2.5%: 42.8 ± 2.7 vs 10%: 69.2 ± 3.4, P < 0.05) blastocysts, and reduced blastocoele re-expansion after vitrification (2.5%: 81.6 ± 2.5 vs 10%: 67.3 ± 3.5, P < 0.05). The addition of PES in culture media, either from Days 2.5 or 4, reduced lipid accumulation (P < 0.05) and increased blastocoele re-expansion after vitrification (Control: 72.0 ± 3.0 vs PES Day 2.5: 79.9 ± 2.8 or PES Day 4: 86.2 ± 2.4, P < 0.05). However, just the use of PES from D4 reduced apoptosis in vitrified blastocysts (Control: 52.0 ± 3.0 vs PES Day 4: 39.2 ± 2.4, P < 0.05). Independent of FCS withdrawal or PES addition to culture media, the in vivo control group had lesser lipid accumulation, a lower apoptosis rate, and greater cryotolerance (P < 0.05). The increased lipid content was moderately correlated with apoptosis in vitrified blastocysts (r = 0.64, P = 0.01). In contrast, the increased apoptosis in fresh blastocysts was strongly correlated with apoptosis in vitrified blastocysts (r = 0.94, P < 0.0001). Therefore, using only 2.5% FCS and the addition of PES from Day 4, increased the survival of IVP embryos after vitrification. Moreover, embryo quality, represented by the fresh apoptosis rate, was better than lipid content for predicting embryo survival after vitrification.