Assessment of field fertility and several in vitro sperm characteristics following the use of different Angus sires in a timed-AI program with suckled Nelore cows

In order to provide information that may help researchers to understand the main cause(s) of differences in bull fertility frequently observed in field trials, this study aimed to investigate conception rates as well as several in vitro sperm characteristics of different sires of unknown fertility utilized in a Timed-AI (TAI) program. Suckled Nelore cows submitted to the same TAI protocol were allocated into eight breeding groups of approximately 120 animals each. Frozen semen doses from three Angus bulls and three different batches from each bull were utilized. Approximately 100 doses from each batch were used in TAI. Sires, batches and AI technicians were equally distributed across breeding groups. Cows were examined for pregnancy diagnosis 40 d after TAI. For in vitro sperm analyses, the same thawing procedure was repeated in the laboratory to mimic field conditions. The following in vitro sperm characteristics were assessed: computerized motility, thermal resistance, plasma and acrosomal membrane integrity, lipid peroxidation, morphology, morphometry and chromatin structure. No effect of breeding group, body condition score, AI technician and sire was observed. However, some significant differences among bulls were detected in laboratory analyses. Semen from sire presenting numerically lower (P > 0.05) pregnancy/AI also presented lower (P < 0.05) values in all sperm characteristics analyzed in thermal resistance test at 4 h (Total Motility, Progressive Motility, Average Path Velocity, Straight-Line Velocity, Curvilinear Velocity, Amplitude of Lateral Head Displacement, Beat Cross Frequency, Straightness, Linearity, and Percentage of Rapidly Moving Cells), higher (P < 0.05) Major and Total Defects in sperm morphological test, lower (P < 0.05) Length, Ellipticity and Fourier parameter (Fourier 0) in sperm morphometric analysis as well as higher (P < 0.05) chromatin heterogeneity. It was concluded that, although no bull effect was observed in the field experiment, the sire that presented numerically lower pregnancy/AI also presented lower semen quality according to the laboratory analyses performed. (C) 2012 Elsevier B.V. All rights reserved.

Impairment on sperm quality and fertility of adult rats after antiandrogen exposure during prepuberty

This study evaluated the effects of antiandrogen exposure during the prepubertal period on reproductive development and reproductive competence in adults. Male rats were divided into two groups: flutamide, receiving 25 mg/kg/day of flutamide by oral gavage and control, receiving vehicle daily. Dosing continued from PND 21 to 44, and animals were killed on PND 50 or PND 75-80. The epididymis, prostate, vas deferens and seminal vesicle weights were lower in Flutamide group on PND 50, while on PND 80 only seminal vesicle weight was reduced. Fertility assessed by IUI revealed a decrease in the fertility potential in the flutamide-treated adults. Flutamide accelerated sperm transit time through the epididymis, impairing sperm motility and storage. A quantitative analysis of the cauda sperm membrane proteome revealed a few significant changes in protein expression. Thus, exposure to flutamide during the prepubertal period compromises the function of the epididymis along with epididymal sperm quality at adulthood. (C) 2011 Elsevier Inc. All rights reserved.

The importance of plant life form on spatial associations along a subtropical coastal dune gradient

Questions Does the spatial association between isolated adult trees and understorey plants change along a gradient of sand dunes? Does this association depend on the life form of the understorey plant? Location Coastal sand dunes, southeast Brazil. Methods We recorded the occurrence of understorey plant species in 100 paired 0.25 m2 plots under adult trees and in adjacent treeless sites along an environmental gradient from beach to inland. Occurrence probabilities were modelled as a function of the fixed variables of the presence of a neighbour, distance from the seashore and life form, and a random variable, the block (i.e. the pair of plots). Generalized linear mixed models (GLMM) were fitted in a backward step-wise procedure using Akaike's information criterion (AIC) for model selection. Results The occurrence of understorey plants was affected by the presence of an adult tree neighbour, but the effect varied with the life form of the understorey species. Positive spatial association was found between isolated adult neighbour and young trees, whereas a negative association was found for shrubs. Moreover, a neutral association was found for lianas, whereas for herbs the effect of the presence of an adult neighbour ranged from neutral to negative, depended on the subgroup considered. The strength of the negative association with forbs increased with distance from the seashore. However, for the other life forms, the associational pattern with adult trees did not change along the gradient. Conclusions For most of the understorey life forms there is no evidence that the spatial association between isolated adult trees and understorey plants changes with the distance from the seashore, as predicted by the stress gradient hypothesis, a common hypothesis in the literature about facilitation in plant communities. Furthermore, the positive spatial association between isolated adult trees and young trees identified along the entire gradient studied indicates a positive feedback that explains the transition from open vegetation to forest in subtropical coastal dune environments.

Effects of discontinuous Percoll gradient centrifugation on the quality of bovine spermatozoa evaluated with computer-assisted semen analysis and fluorescent probes association

The objective of this study was to evaluate the quality of bovine frozen-thawed sperm cells after Percoll gradient centrifugation. Frozen semen doses were obtained from six bulls of different breeds, including three taurine and three Zebu animals. Four ejaculates per bull were evaluated before and after discontinuous Percoll gradient centrifugation. Sperm motility was assessed by computer-assisted semen analysis and the integrity of the plasma and acrosomal membranes, as well as mitochondrial function, were evaluated using a combination of fluorescent probes propidium iodide, fluorescein isothiocyanate-conjugated Pisum sativum agglutinin and 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolcarbocyanine iodide. The procedure of Percoll gradient centrifugation increased the percentage of total and progressive sperm motility, beat frequency, rectilinear motility, linearity and rapidly moving cells. In addition, the percentage of cells with intact plasma membrane and mitochondrial membrane potential was increased in post-centrifugation samples. However, the percentage of sperm cells with intact acrosomal membrane was markedly reduced. The method used selected the motile cells with intact plasma membrane and higher mitochondrial functionality in frozen-thawed bull semen, but processing, centrifugation and/or the Percoll medium caused damage to the acrosomal membrane.

The local power of the gradient test

The asymptotic expansion of the distribution of the gradient test statistic is derived for a composite hypothesis under a sequence of Pitman alternative hypotheses converging to the null hypothesis at rate n(-1/2), n being the sample size. Comparisons of the local powers of the gradient, likelihood ratio, Wald and score tests reveal no uniform superiority property. The power performance of all four criteria in one-parameter exponential family is examined.

Local power and size properties of the LR, Wald, score and gradient tests in dispersion models

We derive asymptotic expansions for the nonnull distribution functions of the likelihood ratio, Wald, score and gradient test statistics in the class of dispersion models, under a sequence of Pitman alternatives. The asymptotic distributions of these statistics are obtained for testing a subset of regression parameters and for testing the precision parameter. Based on these nonnull asymptotic expansions, the power of all four tests, which are equivalent to first order, are compared. Furthermore, in order to compare the finite-sample performance of these tests in this class of models, Monte Carlo simulations are presented. An empirical application to a real data set is considered for illustrative purposes. (C) 2012 Elsevier B.V. All rights reserved.

Use of passive diffusion sampling method for defining NO2 concentrations gradient in São Paulo, Brazil

Abstract Background Air pollution in São Paulo is constantly being measured by the State of Sao Paulo Environmental Agency, however there is no information on the variation between places with different traffic densities. This study was intended to identify a gradient of exposure to traffic-related air pollution within different areas in São Paulo to provide information for future epidemiological studies. Methods We measured NO2 using Palmes' diffusion tubes in 36 sites on streets chosen to be representative of different road types and traffic densities in São Paulo in two one-week periods (July and August 2000). In each study period, two tubes were installed in each site, and two additional tubes were installed in 10 control sites. Results Average NO2 concentrations were related to traffic density, observed on the spot, to number of vehicles counted, and to traffic density strata defined by the city Traffic Engineering Company (CET). Average NO2concentrations were 63μg/m3 and 49μg/m3 in the first and second periods, respectively. Dividing the sites by the observed traffic density, we found: heavy traffic (n = 17): 64μg/m3 (95% CI: 59μg/m3 – 68μg/m3); local traffic (n = 16): 48μg/m3 (95% CI: 44μg/m3 – 52μg/m3) (p < 0.001). Conclusion The differences in NO2 levels between heavy and local traffic sites are large enough to suggest the use of a more refined classification of exposure in epidemiological studies in the city. Number of vehicles counted, traffic density observed on the spot and traffic density strata defined by the CET might be used as a proxy for traffic exposure in São Paulo when more accurate measurements are not available.

Yield mapping, soil fertility and tree gaps in an orange orchard

The current high competition on Citrus industry demands from growers new management technologies for superior efficiency and sustainability. In this context, precision agriculture (PA) has developed techniques based on yield mapping and management systems that recognize field spatial variability, which contribute to increase profitability of commercial crops. Because spatial variability is often not perceived the orange orchards are still managed as uniform and adoption of PA technology on citrus farms is low. Thus, the objective of the present study was to characterize the spatial variability of three factors: fruit yield, soil fertility and occurrence of plant gaps caused by either citrus blight or huanglongbing (HLB) in a commercial Valencia orchard in Brotas, São Paulo State, Brazil. Data from volume, geographic coordinates and representative area of the bags used on harvest were recorded to generate yield points that were then interpolated to produce the yield map. Soil chemical characteristics were studied by analyzing samples collected along planting rows and inter-rows in 24 points distributed in the field. A map of density of tree gaps was produced by georeferencing individual gaps and later by counting the number of gaps within 500 m² cells. Data were submitted to statistical and geostatistical analyses. A t test was used to compare means of soil chemical characteristics between sampling regions. High variation on yield and density of tree gaps was observed from the maps. It was also demonstrated overlapping regions of high density of plant absence and low fruit yield. Soil fertility varied depending on the sampling region in the orchard. The spatial variability found on yield, soil fertility and on disease occurrence demonstrated the importance to adopt site specific nutrient management and disease control as tools to guarantee efficiency of fruit production.

Spatial variability of soil fertility and its relationship with seed physiological potential in a soybean production area

The correlation of soil fertility x seed physiological potential is very important in the area of seed technology but results published with that theme are contradictory. For this reason, this study to evaluate the correlations between soil chemical properties and physiological potential of soybean seeds. On georeferenced points, both soil and seeds were sampled for analysis of soil fertility and seed physiological potential. Data were assessed by the following analyses: descriptive statistics; Pearson's linear correlation; and geostatistics. The adjusted parameters of the semivariograms were used to produce maps of spatial distribution for each variable. Organic matter content, Mn and Cu showed significant effects on seed germination. Most variables studied presented moderate to high spatial dependence. Germination and accelerated aging of seeds, and P, Ca, Mg, Mn, Cu and Zn showed a better fit to spherical semivariogram: organic matter, pH and K had a better fit to Gaussian model; and V% and Fe showed a better fit to the linear model. The values for range of spatial dependence varied from 89.9 m for P until 651.4 m for Fe. These values should be considered when new samples are collected for assessing soil fertility in this production area.

Tracing latitudinal gradient, river discharge and water masses along the subtropical South American coast using benthic Foraminifera assemblages

More than 30% of Buccella peruviana (D'Orbigny), Globocassidulina crassa porrecta (Earland & Heron-Allen), Cibicides mackannai (Galloway & Wissler) and C. refulgens (Montfort) indicate the presence of cold Sub Antarctic Shelf Water in winter, from 33.5 to 38.3º S, deeper than 100 m, in the southern part of the study area. In summer, the abundance of this association decreases to less than 15% around 37.5-38.9º S where two species (Globocassidulina subglobosa (Brady), Uvigerina peregrina (Cushman) take over. G. subglobosa, U. peregrina, and Hanzawaia boueana (D'Orbigny) are found at 27-33º S in both seasons in less than 55 m deep in the northern part, and are linked with warm Subtropical Shelf Water and Tropical Water. Freshwater influence was signalized by high silicate concentration and by the presence of Pseudononion atlanticum (Cushman), Bolivina striatula (Cushman), Buliminella elegantissima (D'Orbigny), Bulimina elongata (D'Orbigny), Elphidium excavatum (Terquem), E. poeyanum (D'Orbigny), Ammobaculites exiguus (Cushman & Brönnimann), Arenoparrella mexicana (Kornfeld), Gaudryina exillis (Cushman & Brönnimann), Textularia earlandi (Parker) and thecamoebians in four sectors of the shelf. The presence of Bulimina marginata (D'Orbigny) between 34.1-32.8º S in the winter and 34.2-32.7º S in the summer indicates that the influence of the Subtropical Shelf Front on the sediment does not change seasonally, otherwise, the presence of Angulogerina angulosa (Williamson) in the winter, only in Mar del Plata (38.9º S), show that Malvinas currents are not influencing the sediment in the summer.

Sintering and model of thermal residual stress for getting cutting tools from functionally gradient materials

Cutting tools with higher wear resistance are those manufactured by powder metallurgy process, which combines the development of materials and design properties, features of shape-making technology and sintering. The annual global market of cutting tools consumes about US$ 12 billion; therefore, any research to improve tool designs and machining process techniques adds value or reduces costs. The aim is to describe the Spark Plasma Sintering (SPS) of cutting tools in functionally gradient materials, to show this structure design suitability through thermal residual stress model and, lastly, to present two kinds of inserts. For this, three cutting tool materials were used (Al2O3-ZrO2, Al2O3-TiC and WC-Co). The samples were sintered by SPS at 1300 °C and 70 MPa. The results showed that mechanical and thermal displacements may be separated during thermal treatment for analysis. Besides, the absence of cracks indicated coherence between experimental results and the residual stresses predicted.

Biogenic habitat structure provided by temperate macroalgae change along a latitudinal gradient in ocean climate

[EN] Global warming is affecting all major ecosystems, including temperate reefs where canopy-forming seaweeds provide biogenic habitat. In contrast to the rapidly growing recognition of how climate affects the performance and distribution of individuals and populations, relatively little is known about possible links between climate and biogenic habitat structure. We examined the relationship between several ocean temperature characteristics, expressed on time-scales of days, months and years, on habitat patch characteristics on 24 subtidal temperate reefs along a latitudinal gradient (Western Australia; ca 34 to 27º S). Significant climate related variation in habitat structure was observed, even though the landscape cover of kelp and fucalean canopies did not change across the climate gradient: monospecific patches of kelp became increasingly dominant in warmer climates, at the expense of mixed kelp-fucalean canopies. The decline in mixed canopies was associated with an increase in the abundance of Sargassum spp., replacing a more diverse canopy assemblage of Scytothalia doryocarpa and several other large fucoids. There were no observed differences in the proportion of open gaps or gap characteristics. These habitat changes were closely related to patterns in minimum temperatures and temperature thresholds (days > 20 °C), presumably because temperate algae require cool periods for successful reproduction and recruitment (even if the adults can survive warmer temperatures). Although the observed habitat variation may appear subtle, similar structural differences have been linked to a range of effects on canopy-associated organisms through the provision of habitat and ecosystem engineering. Consequently, our study suggests that the magnitude of projected temperature increase is likely to cause changes in habitat structure and thereby indirectly affect numerous habitat-dependent plants and animals

Frugivores, seed dispersal and tree regeneration along a human disturbance gradient in East African tropical rainforests

Samenausbreitung und Regeneration von Bäumen sind wichtig für den langfristigen Bestand von Baum- und Frugivorengemeinschaften in tropischen Regenwäldern. Zunehmende Rohdung und Degradation gefährden den Ablauf dieser mutualistischen Prozesse in diesem Ökosystem. Um den Einfluss von kleinräumiger menschlicher Störung auf die Frugivorengemeinschaft und die zentralen Ökosystemprozesse Samenausbreitung und Regeneration zu erforschen, habe ich 1) die Frugivorengemeinschaft und die Samenausbreitungsrate von Celtis durandii (Ulmaceae) und 2) den Zusammenhang zwischen Baumarten mit fleischigen Früchten, Frugivoren und der Etablierung von Keimlingen dieser Baumarten in unterschiedlich stark gestörten Flächen dreier ostafrikanischer tropischer Regenwälder untersucht. Insgesamt konnte ich 40 frugivore Vogel- und Primatenarten in den drei untersuchten Waldgebieten nachweisen. Auf gering gestörten Flächen wurden mehr Frugivore als auf stark gestörten Flächen aufgenommen. Auch die Beobachtungen an C. durandii ergaben mehr frugivore Besucher in Bäumen auf gering gestörten als auf stark gestörten Flächen. Dies führte zu einer marginal signifikant höheren Samenausbreitungsrate auf den gering gestörten Flächen. Diese Ergebnisse waren auf regionaler Ebene in allen drei untersuchten Wäldern konsistent. Dies zeigt, dass kleinräumige Störung einen umfassenderen negativen Einfluss auf Frugivore und ihre Funktion als Samenausbreiter hat als zuvor angenommen. Bei der Vegetationserfassung nahm ich 131 verschiedene Baumarten mit fleischigen Früchten in den drei Regenwäldern auf. Kleinräumige menschliche Störung erhöhte den Artenreichtum dieser Baumarten marginal signifikant, hatte jedoch keinen direkten Einfluss auf die Frugivorendichte und den Artenreichtum von Keimlingen dieser Baumarten. Der Artenreichtum von Baumarten mit fleischigen Früchten zeigte einen marginal signifikant positiven Einfluss auf die Frugivorendichte, allerdings nicht auf die Keimlinge. Allerdings führte die Dichte der Frugivoren zu signifikant erhöhtem Artenreichtum der Keimlinge. Folglich scheint kleinräumige Störung die Keimlingsetablierung indirekt durch erhöhten Baumartenreichtum und erhöhte Frugivorendichte zu beeinflussen. Die Frugivorendichte hatte einen größeren Einfluss auf die Waldregeneration als kleinräumige Störung und Baumartenreichtum. Demnach scheint kleinräumige menschliche Störung sowohl positive als auch negative Effekte auf Samenausbreitung und Regeneration zu haben. Somit sind weitere Studien notwendig, die den Einfluss von kleinräumiger menschlicher Störung auf Mutualismen tropischer Regenwälder aufklären.