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E Breininger BE Vecchi Galenda GM Alvarez C Gutnisky PD Cetica 《Reproduction in domestic animals》2014,49(6):1068-1073
Oocyte maturation depends on the metabolic activity of cumulus–oocyte complex (COC) that performs nutritive and regulatory functions during this process. In this work, the enzymes [phosphofructokinase (PFK) and malate dehydrogenase (MDH)] were tested to elucidate the metabolic profile of porcine COCs during the in vitro maturation (IVM). Enzymatic activity was expressed in U/COC and U/mg protein (specific activity) as mean ± SEM. In vitro maturation was performed with 2‐oxoglutarate (5, 10 and 20 mm ) or hydroxymalonate (30, 60 and 100 mm ) inhibitors of PFK and MDH, respectively. The PFK and MDH activities (U) remained constant during maturation. For PFK, the U were (2.48 ± 0.23) 10?5 and (2.54 ± 0.32) 10?5, and for MDH, the U were (4.72 ± 0.42) 10?5 and (4.38 ± 0.25) 10?5 for immature and in vitro matured COCs, respectively. The specific activities were significantly lower after IVM, for PFK (4.29 ± 0.48) 10?3 and (0.94 ± 0.12) 10?3, and for MDH (9.08 ± 0.93) 10?3 and (1.89 ± 0.10) 10?3 for immature and in vitro matured COCs, respectively. In vitro maturation percentages and enzymatic activity diminished with 20 mm 2‐oxoglutarate or 60 mm hydroxymalonate (p < 0.05). Viability was not affected by any concentration of the inhibitors evaluated. The U remained unchanged during IVM; however, the increase in the total protein content per COC provoked a decrease in the specific activity of both enzymes. Phosphofructokinase and MDH necessary for oocyte IVM would be already present in the immature oocyte. The presence of inhibitors of these enzymes impairs the meiotic maturation. Therefore, the participation of these enzymes in the energy metabolism of the porcine oocyte during IVM is confirmed in this study. 相似文献
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Participation of phosphofructokinase,malate dehydrogenase and isocitrate dehydrogenase in capacitation and acrosome reaction of boar spermatozoa 
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下载免费PDF全文 E Breininger D Dubois VE Pereyra PC Rodriguez MM Satorre PD Cetica 《Reproduction in domestic animals》2017,52(5):731-740
The aim of this work was to determine the enzymatic activity of phosphofructokinase (PFK), malate dehydrogenase (MDH) and isocitrate dehydrogenase (IDH) in boar spermatozoa and study their participation in bicarbonate‐induced capacitation and follicular fluid‐induced acrosome reaction. Enzymatic activity of these enzymes was determined spectrophotometrically in extracts of boar spermatozoa. Sperm suspensions were incubated in the presence of bicarbonate (40 mM), a well‐known capacitation inducer, or follicular fluid (30%), as an acrosome reaction inducer, and different concentrations of oxoglutarate, oxalomalate and hydroxymalonate, inhibitors of PFK, IDH and MDH, respectively. Capacitation percentages were determined by the fluorescence technique of chlortetracycline (CTC), and true acrosome reaction was determined by trypan blue and differential–interferential contrast, optical microscopy. The activity of PFK in boar spermatozoa enzymatic extracts was 1.70 ± 0.19 U/1010 spermatozoa, the activity of NAD‐ and NADP‐dependent IDH was 0.111 ± 0.005 U/1010 and 2.22 ± 0.14 U/1010 spermatozoa, respectively, and the activity of MDH was 4.24 ± 0.38 U/1010 spermatozoa. The addition of the specific inhibitors of these enzymes prevented sperm capacitation and decreased sperm motility during capacitation and inhibited the acrosome reaction (AR), without affecting the sperm motility during this process. Our results demonstrate the participation of PFK, IDH and MDH in bicarbonate‐induced capacitation and follicular fluid‐induced acrosome reaction in boar spermatozoa, contributing to elucidate the mechanisms that produce energy necessary for these processes in porcine spermatozoa. 相似文献
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Relation between respiratory activity and sperm parameters in boar spermatozoa cryopreserved with alpha‐tocopherol and selected by Sephadex 下载免费PDF全文
下载免费PDF全文 Our aim was to evaluate the effect of Sephadex filtration on respiratory activity of porcine spermatozoa and its relation with quality and functional sperm parameters. Samples were evaluated regarding oxygen uptake and sperm parameters: motility, plasma and acrosome membrane integrity, capacitation and acrosome reaction induction in vitro, plasma membrane functionality, determined by the hypo‐osmotic swelling test (HOST), and lipid peroxidation assessed by thiobarbituric acid assay. Sephadex filtration improved all routine quality parameters (motility, plasma and acrosome membrane integrity) and functional parameters (HOST, in vitro capacitation and true acrosome reaction levels) and produced a significant decrease in cryocapacitation and lipid peroxidation. Oxygen uptake increased in Sephadex samples (41 ± 7%) respect to single washing. Oxygen addition of carbonyl‐cyanide‐m‐chlorophenylhydrazone (CCCP) confirmed mitochondrial coupling in washed and Sephadex samples; showing an increase of 2.6 and 4.2 times for oxygen consumption in single washing and Sephadex ones, respectively. The increase in oxygen uptake with succinate addition with respect to basal oxygen uptake was significantly lower in Sephadex samples (63 ± 25%) than in the washed ones (183 ± 35%). Sephadex samples showed higher mitochondrial activity measured by oxygen consumption and improved quality and functional parameters. Our study recommends this protocol due to the fact that this filtration method removes dead or damaged spermatozoa allowing to obtain cryopreserved boar spermatozoa with optimized fertilizing capacity. 相似文献
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Javan M. Bauder David R. Breininger M. Rebecca Bolt Michael L. Legare Christopher L. Jenkins Betsie B. Rothermel Kevin McGarigal 《Landscape Ecology》2018,33(5):743-763
Context
Although multi-scale approaches are commonly used to assess wildlife-habitat relationships, few studies have examined selection at multiple spatial scales within different hierarchical levels/orders of selection [sensu Johnson’s (1980) orders of selection]. Failure to account for multi-scale relationships within a single level of selection may lead to misleading inferences and predictions.Objectives
We examined habitat selection of the federally threatened eastern indigo snake (Drymarchon couperi) in peninsular Florida at the level of the home range (Level II selection) and individual telemetry location (Level III selection) to identify influential habitat covariates and predict relative probability of selection.Methods
Within each level, we identified the characteristic scale for each habitat covariate to create multi-scale resource selection functions. We used home range selection functions to model Level II selection and paired logistic regression to model Level III selection.Results
At both levels, EIS selected undeveloped upland land covers and habitat edges while avoiding urban land covers. Selection was generally strongest at the finest scales with the exception of Level II urban edge which was avoided at a broad scale indicating avoidance of urbanized land covers rather than urban edge per se.Conclusions
Our study illustrates how characteristic scales may vary within a single level of selection and demonstrates the utility of multi-level, scale-optimized habitat selection analyses. We emphasize the importance of maintaining large mosaics of natural habitats for eastern indigo snake conservation.6.
Leaching of nutrients out of young intact spruce (Picea abies) by acid fog The effect of acid fog on the leaching of minerals and carbohydrates out of needles of five year old spruce trees (Picea abies) was studied. The fogs were prepared from H2SO4 and HNO3 (2:1) with a pH of 2.75 (acid treatment) and 5 (control treatment). The acid fog leached significantly higher amounts of K, Ca, Mg, Mn, and Zn as well as carbohydrates as compared with the control fog. The absolute quantities of minerals leached, however, were low and amounted to only some percent of the minerals generally present in needles. Except Zn, of which the quantity leached was about as high as the Zn needle content. Nevertheless the Zn concentration in the needles treated with acid fog was not lower than the Zn concentration in the control needles suggesting that the lost Zn was quickly compensated by Zn uptake. In the treatments with acid fog damage symptoms appeared at the end of the experimental period. In the older needles a weak chlorosis occurred; from the needles of the 1st year some turned redish brown. In the acid fog treatments all needles lacked brightness while the control needles looked bright. These symptoms were similar to those under field conditions of older spruce trees with the ?lametta syndrom”?. Electron microscopic investigation revealed that the wax layer of the needles treated with acid fog was badly damaged. 相似文献
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Duncan Brean W. Boyle Shannon Breininger David R. Schmalzer Paul A. 《Landscape Ecology》1999,14(3):291-309
Historic landcover dynamics in a scrubby flatwoods (Tel-4) and scrub landscape (Happy Creek) on John F. Kennedy Space Center were measured using aerial images from 1943, 1951, 1958, 1969, 1979, and 1989. Landcover categories were mapped, digitized, geometrically registered, and overlaid in ARC/INFO. Both study sites have been influenced by various land use histories, including periods of range management, fire suppression, and fire management. Several analyses were performed to help understand the effects of past land management on the amount and spatial distribution of landcover within the study sites. A chi-squared analysis showed a significant difference between the frequency of landcover occurrence and management period. Markov chain models were used to project observed changes over a 100-year period; these showed current management practices being effective at Tel-4 (restoring historic landscape structure) and much less effective at Happy Creek. Documenting impacts of past management regimes on landcover has provided important insight into current landscape composition and will provide the basis for improving land management on Kennedy Space Center and elsewhere. 相似文献
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A basic element in the success of managing species of conservation concern is knowledge of the species’ habitat occupancy. Often, predictive species-habitat models are developed from GIS data sources that were intended for purposes other than predicting species habitat occupancy and are of inappropriate scale. In addition, the techniques used to quantify predictor variables from such data sources are often time consuming and cannot be repeated efficiently to reflect changing conditions. We used digital orthophotos and a grid cell classification scheme to develop an efficient technique to quantify predictor variables to model Florida scrub-jay habitat occupancy. We combined our classification scheme with a priori hypothesis development using expert knowledge and a previously published habitat suitability index and used an objective model selection procedure to choose candidate models. We classified a large area (43,000 ha) in a fraction of the time that would be required to map vegetation classes and were able to test models at varying scales using a grid-cell windowing process. Interpretation of the selected models confirmed existing knowledge of factors important to Florida scrub-jay habitat occupancy. The potential uses and advantages of using a grid cell classification scheme in conjunction with expert knowledge and an objective model selection procedure are discussed. 相似文献
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Landcover maps demarcate habitat but might underestimate it where species select features smaller than minimum mapping units used to produce maps. Habitat loss is magnified by fragmentation, which produces edge effects, alters dispersal and natural processes (i.e., fire). We quantified how Florida scrub-jay (Aphelocoma coerulescens) habitat varied using traditional landcover maps and methods that considered small focal habitat features (e.g., scrub ridges <2 ha) within an otherwise unsuitable matrix. We collected 7 years of data on color banded Florida scrub-jays to quantify dispersal and investigate how reproductive success and survival varied with habitat potential (scrub ridges), edge effects, and fire history. Landcover maps that identified only large scrub ridges resulted in a potential population of 354 pairs. Including small scrub ridges within an otherwise unsuitable matrix resulted in a potential population >774 pairs. Florida scrub-jays occupied less than half the potential habitat, and their population declined most from disrupted fire regimes. Almost 90% of all breeding dispersers remained within the same cluster of territories that they hatched in emphasizing the need to maximize local habitat quantity and quality. Reduced habitat quality, caused by disrupted fire regimes, was a major fragmentation effect that greatly magnified impacts of habitat loss. The disruption of natural processes is seldom identified as a major fragmentation effect, but studies worldwide have accumulated to demonstrate its significance. We advocated specific mapping approaches for species influenced by small habitat features and species dependent on matrix habitats that advance natural processes, such as fire. 相似文献
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J Peláez E Breininger B Alegre FJ Peña JC Domínguez 《Reproduction in domestic animals》2006,41(2):153-161
Twenty-two boar ejaculates were frozen in 0.25 ml straws using a controlled cooling rate, then evaluated in vitro in order to assess: (i) the extent to which a range of semen evaluation parameters accurately characterize sperm quality, (ii) the value of quality assessment in the characterization of long-term sperm survival and fertility and (iii) the suitability of the cryopreservation protocol used for yielding semen with good quality and fertilizing capacity. Motility with or without caffeine, plasma membrane integrity (PMI) evaluated with both propidium iodide (PI) and Hoechst 33258, and acrosome morphology were studied, the ejaculates being then classified into five quality groups. A thermoresistance test and a homologous in vitro fertilization test were applied to selected ejaculates of these groups. Caffeine-stimulated motility and PMI evaluated with PI provided better estimations of semen quality than the other tests of motility, PMI, or acrosome morphology, but this quality assessment could not reveal differences in fertilizing capacity or thermoresistance among ejaculates. Over 43% spermatozoa survived cryopreservation in 19 of the 22 ejaculates, with inter-boar and inter-ejaculate variability in the freezing success being observed. The fertilizing capacity, however, was seriously affected by the process regardless of the semen quality. It is concluded that caffeine-stimulated motility and PMI evaluated with PI give accurate information on sperm quality, but important aspects to the valuation of semen such as thermoresistance and fertilizing capacity are not revealed by this quality study. Moreover, the approach of selecting suitable protocols of cryopreservation does not appear to be sufficient for guaranteeing systematically good quality and fertilizing capacity in the frozen-thawed semen. 相似文献
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