Nitric Oxide and Superoxide Anion Production During Heparin‐Induced Capacitation in Cryopreserved Bovine Spermatozoa     

PC Rodriguez  LB Valdez  T Zaobornyj  A Boveris  MT Beconi 《Reproduction in domestic animals》2011,46(1):74-81

The aim of this work was to quantify NO, O₂^? and ONOO^? production during heparin‐induced capacitation of cryopreserved bovine spermatozoa. A time dependent hyperbolic increase was observed for heparin‐dependent capacitation, O₂ uptake, and NO production. Conversely, O₂^? production was increased during the first 15 min of incubation, showing a decrease from this time until 45 min. At 15 min of heparin incubation, a threefold increase in O₂ consumption (5.9 ± 0.6 nmol/min × 10⁷ cells), an enhancement in NO release (1.1 ± 0.2 nmol/min × 10⁷ cells), and a five‐fold increase in O₂^? production (1.3 ± 0.07 nmol/min × 10⁷ cells), were observed. Peroxynitrite production rate was estimated taking into account NO and O₂^? generation and the second‐order rate constant of the reaction between these species. To conclude, heparin‐induced capacitation of cryopreserved bovine spermatozoa activates (i) mitochondrial O₂ uptake by high ADP levels due to increased energy requirements, (ii) NO production by a constitutive NOS and (iii) O₂^? production by a membrane‐bound NAD(P)H oxidase. The products of both enzymes are released to the extracellular space and could be involved in the process of sperm capacitation.  相似文献   

Impact of lower atmospheric carbon dioxide on tropical mountain ecosystems   总被引：1，自引：0，他引：1  

FA Street-Perrott  Y Huang  RA Perrott  G Eglinton  P Barker  LB Khelifa  DD Harkness  DO Olago 《Science (New York, N.Y.)》1997,278(5342):1422-1426

Carbon-isotope values of bulk organic matter from high-altitude lakes on Mount Kenya and Mount Elgon, East Africa, were 10 to 14 per mil higher during glacial times than they are today. Compound-specific isotope analyses of leaf waxes and algal biomarkers show that organisms possessing CO2-concentrating mechanisms, including C4 grasses and freshwater algae, were primarily responsible for this large increase. Carbon limitation due to lower ambient CO2 partial pressures had a significant impact on the distribution of forest on the tropical mountains, in addition to climate. Hence, tree line elevation should not be used to infer palaeotemperatures.  相似文献   

Decision support system for economic analysis of grasshopper treatment operations in the African Sahel     

Leonard B. Coop  Brian A. Croft  Christopher F. Murphy  Stanley F. Miller 《Crop Protection》1991,10(6):485-495

A decision support system for benefit/cost analysis of chemical treatment of the Senegalese grasshopper, Oedaleus senegalensis (Krauss) (OSE), was created to assist in the training, analysis, and management of grasshopper treatment programmes. The system, known as GHLSIM, has linked simulation models, databases, and a user interface. Millet and sorghum phenology and yields are estimated by an FAO (Food and Agriculture Organization, United Nations) soil water deficit model. Outputs from the PRIFAS (Programme de Recherches Interdisciplinaire Français sur les Acridiens du Sahel) OSE biomodel, including daily grasshopper life stages and favourability for development, are converted to density estimates using survey data, oviposition rates, and natural and insecticide-caused mortality. Crop loss is estimated through crop injury units — a function of grasshopper stage densities, consumption rates, crop preference, crop stage susceptibility, and non-crop vegetation greenness. Second-year benefits of treatment are estimated from end-of-season egg-pod densities. The model was calibrated using published economic thresholds for four crop stages. Yield increases from a late-season grasshopper aerial treatment campaign, 22 September — 19 October 1987, at 13 sites in eastern Chad were estimated at 33%±20% (s.e.). Benefit/cost ratios were 2.6±0.5 for the first season, and 3.8±0.7 with second-year effects added. The analysis indicated that optimal timing was 5–10 days earlier than the actual treatments. Crop yield reports from treated and non-treated areas, a crop loss assessment conducted in Batha, Chad in October 1987 and a break-even analysis provide further evidence that the campaign was successful and cost-effective at most sites, as indicated by model results.  相似文献   

Effects of dietary molybdenum on nematode and host during Trichostrongylus vitrinus infection in lambs.     

N F Suttle  D P Knox  F Jackson  R L Coop  K W Angus 《Research in veterinary science》1992,52(2):224-229

The addition of molybdenum (0.05 mmol kg-1 dry matter) to the diet of lambs exposed for four weeks to a trickle (2500 third stage larvae per day) infection with Trichostrongylus vitrinus reduced the number and length of adult worms retrieved from the small intestine 11 days later: both effects were particularly marked in female worms from female lambs (P less than 0.01). Worms from lambs given molybdenum contained less proteinase enzyme activity and secreted less proteinases in culture irrespective of the sex of the host. Pathogenicity was not attenuated by molybdenum. Damage to the intestinal mucosa was severe in both dietary groups but infected females given molybdenum developed lower plasma albumin concentrations and lighter dressed carcases than those not given molybdenum. Neither the effects on the parasite nor those on the host could be attributed simply to molybdenum-induced copper depletion, using conventional measures of copper status. Molybdenum may be toxic to T vitrinus but may also facilitate or enhance the inflammatory process limiting larval establishment or increasing parasite rejection.  相似文献   

Effect of parasitism with Nematodirus battus on the pharmacokinetics of levamisole, ivermectin and netobimin     

Q A McKellar  F Jackson  R L Coop  E Jackson  E Scott 《Veterinary parasitology》1991,39(1-2):123-136

The pharmacokinetics of levamisole, ivermectin and netobimin administered orally and by subcutaneous injection were compared in lambs exposed to a moderate challenge with Nematodirus battus and in parasite naive lambs. There were no significant differences (P greater than 0.05) in the bioavailability of any of the anthelmintics tested between parasitized and non-parasitized animals. Levamisole reduced nematode faecal egg output by more than 99% when administered by either route. Ivermectin was also highly effective (greater than 99%). Orally administered netobimin reduced egg output by more than 98% seven days after administration. However egg output was only reduced by 89% 21 days after administration, suggesting poor activity against the early parasitic stages of N. battus. Netobimin was not effective against N. battus when administered by the subcutaneous route and this was probably because very low plasma concentrations of its active albendazole metabolites were achieved.  相似文献   

On‐plant survival and inheritance of resistance to Cry1Ab toxin from Bacillus thuringiensis in a field‐derived strain of European corn borer,Ostrinia nubilalis     

André LB Crespo  Terence A Spencer  Analiza P Alves  Richard L Hellmich  Erin E Blankenship  Leonardo C Magalhães  Blair D Siegfried 《Pest management science》2009,65(10):1071-1081

  相似文献   

Fructooligosaccharide supplementation in diets for tropical gar (Atractosteus tropicus) juvenile: Effects on morphophysiology and intestinal barrier function     

Cesar Antonio Sepúlveda‐Quiroz  Emyr Saul Pea‐Marín  Alfredo Prez‐Morales  Rafael Martínez‐García  Carina Shianya Alvarez‐Villagomez  Claudia Ivette Maytorena‐Verdugo  Susana Camarillo‐Coop  Paula Gabriela Vissio  Daniela Prez Sirkin  Dariel Tovar‐Ramírez  Mario Galaviz  Carlos Alfonso lvarez‐Gonzlez 《Aquaculture Research》2021,52(1):37-50

Supplementary fructooligosaccharides (FOS) were evaluated on growth, survival, gut morphology, digestive enzyme activity and expression of intestinal barrier genes in tropical gar (Atractosteus tropicus). Four treatments were designed to include FOS (5, 10, 15 and 20 g/Kg) and were compared with a control (0 g/Kg) and the current commercial trout diet. Ten fish were stocked (0.25 ± 0.01 g and 4.2 ± 0.4 cm total length) per experimental unit by triplicate in a 45‐day experiment. Fish fed with 5 and 10 g/Kg of FOS had the highest average weight and total average length. Fish fed 5 g/Kg FOS showed the best growth indexes (absolute weight gain: 2.16; specific growth rate: 4.96; and feed conversion rate: 1.23) and survival (96.66%) and also had the highest acid protease, chymotrypsin and leucine aminopeptidase activities. Fish fed 5 g/Kg FOS had a high absorption area and accumulation of lipids in the liver. Finally, relative overexpression of occluding (occ), nucleotide‐binding oligomerization domain‐2 (nod2) and mucin 2 (muc2) was detected in fish fed 10 and 15 g/Kg FOS. The supplementation between 5 and 10 g/Kg FOS in diets for A. tropicus juveniles could be beneficial for growth, digestive enzyme activities, gut morphology and intestinal barrier function.  相似文献   

Darwinian selection on a selfing locus     

Shimizu KK  Cork JM  Caicedo AL  Mays CA  Moore RC  Olsen KM  Ruzsa S  Coop G  Bustamante CD  Awadalla P  Purugganan MD 《Science (New York, N.Y.)》2004,306(5704):2081-2084

The shift to self-pollination is one of the most prevalent evolutionary transitions in flowering plants. In the selfing plant Arabidopsis thaliana, pseudogenes at the SCR and SRK self-incompatibility loci are believed to underlie the evolution of self-fertilization. Positive directional selection has driven the evolutionary fixation of pseudogene alleles of SCR, leading to substantially reduced nucleotide variation. Coalescent simulations indicate that this adaptive event may have occurred very recently and is possibly associated with the post-Pleistocene expansion of A. thaliana from glacial refugia. This suggests that ancillary morphological innovations associated with self-pollination can evolve rapidly after the inactivation of the self-incompatibility response.  相似文献   

俄罗斯远东地区植物病毒名录     

吕文清 Γ.  РВ 《东北农业大学学报》1995,26(3):238-241

根据最近１５年中所报道的俄罗斯远东地区的植物病毒病整理为病毒名录．  相似文献   

Simultaneous Measurement of Local Gain and Electron Density in X-ray Lasers     

R Cauble  Da Silva LB  TW Barbee  P Celliers  C Decker  RA London  JC Moreno  JE Trebes  AS Wan  F Weber 《Science (New York, N.Y.)》1996,273(5278):1093-1096

X-ray lasers (XRLs) have experimental average gains that are significantly less than calculated values and a persistently low level of spatial coherence. An XRL has been used both as an injected signal to a short XRL amplifier and as an interferometer beam to measure two-dimensional local gain and density profiles of the XRL plasma with a resolution near 1 micrometer. The measured local gain is in agreement with atomic models but is unexpectedly spatially inhomogeneous. This inhomogeneity is responsible for the low level of spatial coherence observed and helps explain the disparity between observed and simulated gains.  相似文献