Testosterone serum profile,semen characteristics and testicular biometry of Mangalarga Marchador stallions in a tropical environment

This study was conducted to characterize the daily profile of testosterone secretion and its mean concentrations in the four seasons as well as to evaluate the semen characteristics and testicular biometry of Mangalarga Marchador stallions throughout the year in a tropical region. Three stallions were submitted to semen collections and evaluation of testicular biometry every 14 days along a year. Blood samples were collected once at the middle of each season, in a 20‐min interval during 24 hr in order to evaluate the testosterone secretion profiles among seasons. Testosterone concentrations along the day were higher at the beginning of the afternoon (from 12:00 to 15:00 hr), but a circadian secretion was not clearly observed. Mean testosterone concentrations did not differ among seasons (p > .05), but a pattern of secretion along the day showed variations with higher concentrations in the afternoon during the winter. Ejaculate volume was higher during summer; however, sperm motility decreased in summer and spring. Total sperm in ejaculate, sperm morphology and testicular biometry kept constant along the year showing no differences among the seasons. The results demonstrated that in a tropical region, reproductive aspects of stallions did not show a clearly defined seasonal variation, and months of autumn and winter were not unsuitable for reproduction of the males.     

A New Approach to Modelling the Relationship Between Annual Population Abundance Indices and Weather Data

Weather has often been associated with fluctuations in population sizes of species; however, it can be difficult to estimate the effects satisfactorily because population size is naturally measured by annual abundance indices whilst weather varies on much shorter timescales. We describe a novel method for estimating the effects of a temporal sequence of a weather variable (such as mean temperatures from successive months) on annual species abundance indices. The model we use has a separate regression coefficient for each covariate in the temporal sequence, and over-fitting is avoided by constraining the regression coefficients to lie on a curve defined by a small number of parameters. The constrained curve is the product of a periodic function, reflecting assumptions that associations with weather will vary smoothly throughout the year and tend to be repetitive across years, and an exponentially decaying term, reflecting an assumption that the weather from the most recent year will tend to have the greatest effect on the current population and that the effect of weather in previous years tends to diminish as the time lag increases. We have used this approach to model 501 species abundance indices from Great Britain and present detailed results for two contrasting species alongside an overall impression of the results across all species. We believe this approach provides an important advance to the challenge of robustly modelling relationships between weather and species population size.Supplementary materials accompanying this paper appear online.     

Identification of the SP22 Sperm Protein in Santa Inês and Dorper Rams

The sperm membrane protein referred to as SP22 has been identified in different species and, at least in rats, is highly correlated with fertility. The goals of this study were to identify and to quantify the SP22 protein on spermatozoa from adult rams (Dorper and Santa Inês breeds), and to correlate its levels to morphological and kinematics parameters. SP22 on ram sperm was effectively quantified by both enzyme‐linked immunosorbent assay (ELISA) and fluorescein isothiocyanate immunostaining analysis and the two methods were significantly correlated (R² = 0.70). Clustering analysis of motility parameters obtained by computer‐assisted semen analysis system was used to establish that three distinct kinematic subpopulations with different vigour and progressiveness coexistent within ejaculate. While there were significant differences in the distribution of the three subpopulations in the rams, there was no significant correlation between the proportion of each subpopulation in the rams and the SP22 levels. Quantification of SP22 immunostaining intensity was not correlated with any of the sperm parameters. However, SP22 levels obtained by ELISA were negatively correlated with morphological abnormalities and positively correlated with membrane integrity (three variable R² = 0.47). Future breeding studies are now needed to validate that this protein is a biomarker of fertility in this species.     

Phytoplankton community structure and the drawdown of nutrients and CO2 in the southern ocean

Data from recent oceanographic cruises show that phytoplankton community structure in the Ross Sea is related to mixed layer depth. Diatoms dominate in highly stratified waters, whereas Phaeocystis antarctica assemblages dominate where waters are more deeply mixed. The drawdown of both carbon dioxide (CO2) and nitrate per mole of phosphate and the rate of new production by diatoms are much lower than that measured for P. antarctica. Consequently, the capacity of the biological community to draw down atmospheric CO2 and transport it to the deep ocean could diminish dramatically if predicted increases in upper ocean stratification due to climate warming should occur.     

Cardiopulmonary effects of xylazine and yohimbine in laterally recumbent sheep.

The effects of yohimbine (0.125 mg/kg) on cardiopulmonary parameters in six adult, xylazine treated (0.15 mg/kg), laterally recumbent sheep were studied. Following collection of baseline data, xylazine was administered intravenously and data were collected five and fifteen minutes later. At twenty minutes post-xylazine either yohimbine (0.125 mg/kg) or saline was given and further collection of data occurred at 25, 30, 40 and 50 minutes. Xylazine administration resulted in significant (P less than 0.05) respiratory depression, as reflected by a decrease in arterial oxygen partial pressure (PaO2). No significant changes in haemodynamic variables were observed. Yohimbine produced a significant improvement in PaO2 at the 50 minute period and abolished the paradoxical respiratory pattern when present. The results indicated that yohimbine can be used as an antagonist to control the duration of xylazine induced respiratory depression, although the degree of reversal was less than is clinically desirable.     

Clinical and magnetic resonance imaging (MRI) findings in 26 dogs with canine osseous-associated cervical spondylomyelopathy

The potential link between degenerative changes seen on magnetic resonance imaging (MRI) in osseous-associated cervical spondylomyelopathy (OA-CSM) and clinical signs has not been explored. Our goal was to retrospectively evaluate MRI findings, while investigating potential correlations between these changes, signalment, and clinical signs. Twenty-six dogs diagnosed with OA-CSM were included in the study. Clinical signs were converted into a Modified Frankel Score (MFS) and MRI findings were assessed and graded. Giant breeds had multiple compressed sites and presented at a younger age than large breeds, suggesting a different underlying pathophysiology. Spinal cord compression, most commonly bilateral, was present in 36.8% of intervertebral spaces. Synovial fluid loss and articular process sclerosis were the most common degenerative changes. Most dogs showed identical MFS scores, and no significant correlations were found between MFS and MRI changes. More detailed functional scales should be used to investigate this in the future.     

Follicle Deviation in Ovulatory Follicular Waves with One or Two Dominant Follicles in Mares

The follicle and hormone aspects of diameter deviation and development of one dominant (≥28 mm) follicle (1DF) vs two dominant follicles (2DF) were studied in 32 ovulatory follicular waves in mares. Follicles were ranked each day as F1 (largest) to F3. The beginning of deviation was designated day 0 and preceded the first increase in the differences in diameter between F1 and F2 in the 1DF group and between a combination of F1 and F2 vs F3 in the 2DF group. One dominant follicle and 2DF developed in 21 (66%) and 11 (34%) waves, respectively. Double ovulations occurred in only one of the waves with 2DF. In 8/11 waves with 2DF, a second deviation occurred between F1 and F2 on 2.5 ± 0.4 days after the first deviation. On day 0, 1DF and 2DF waves were similar in number of days after ovulation, number of follicles, difference in diameter between F1 and F2, and plasma concentrations of LH, estradiol and immunoreactive inhibin. The interval from maximum FSH concentration to day 0 was longer (p < 0.05) and FSH concentration was lower (p < 0.05) on days -1 to 4 in the 2DF group. The similarities on day 0 in the characteristics of 1DF and 2DF waves despite the differences in the declining portions of the FSH profile indicated that a specific day of the FSH decline or a specific concentration were not factors in initiating deviation. Unlike reported results in heifers, the results in mares did not indicate a hormonal basis for the development of 2DF or two deviations.     

Assessing the Suitability of Acid Neutralising Capacity as a Measure of Long-Term Trends in Acidic Waters Based on Two Parallel Datasets

Acid Neutralising Capacity (ANC), calculated as the difference between base cations and acid anions, is widely used as a measure of freshwater acid status, and an indicator of biological conditions. Unlike pH and alkalinity, ANC is conservative with respect to CO₂ degassing and reactions with aluminium or organic species. However, since ANC is calculated as the residual of a large number of individual ion determinations, it is potentially sensitive even to relatively small analytical errors. For the Round Loch of Glenhead, SW Scotland, consistency of ANC estimation has been assessed based on a duplicate set of major ion analyses undertaken at different laboratories over an 11 year period. Results indicate that, while the two sets of individual ion determinations correspond well, correlation between calculated ANC values is poor. Consequently, estimated ANC trends exhibit severe discrepancies between datasets; one indicates substantial recovery, the other no apparent trend. These problems with ANC estimation are believed to be general to acidic waters and are of particular concern for long-term monitoring, where ANC changes may be small and difficult to detect (although nonetheless potentially biologically significant). In these situations, it is possible that a more stable measurement of ANC may be obtainable based on titration alkalinity, DOC and aluminium concentrations. Using this method, a small but highly consistent increase in ANC is observed over the study period, although much of this can be attributed to a shift from mineral to organic acidity, rather than an overall reduction in acidity.     

Monitoring Acid Waters in the UK: 1988–1998 Trends

Since 1988, a network of lakes and streams has been monitored in areas of the UK sensitive to surface water acidification. Analysis of 10 years data has focused on the identification and quantification of time-trends in chemical parameters, to establish whether declines in emission of acidifying pollutants have resulted in recovery of acidified surface waters. A national decline in S deposition in the UK since 1988 has not generally been accompanied by a significant improvement in freshwater chemistry. At the three sites where xSO₄ concentrations have declined, NO₃ has increased and there has been no increase in pH or alkalinity. Upward trends in pH and alkalinity observed at several other sites are not associated with downward trends in acidic anions. Temporal variation in xSO₄, NO₃, acidity, DOC and other important meaures of surface water quality can all be linked to decadal-scale variation in climate, and this has important implications for the detection of recovery-related trends.