A Far-Field Hydrothermal Plume from Loihi Seamount

An extensive helium plume in the north central Pacific emanates from Loihi Seamount on the flanks of Hawaii. The maximum helium signal is found at a depth of about 1100 meters, the same depth as the near-field plume directly above Loihi Seamount. Although this helium plume is strongest near Hawaii, where the 3He/4He ratio at a depth of about 1100 meters reaches values 28 percent above the atmospheric ratio, it can be detected quite clearly at latitude 24°N, over 400 kilometers to the north. Excess 3He is also present on the same isopycnal between 15°N and 20°N at 135°W, some 2000 kilometers east of the Hawaiian Islands.     

Dopaminergic and Opioidergic Regulation of Gonadotropin and Prolactin Release in Stallions

In the non‐breeding season, LH release is reduced via dopaminergic systems in the ram. On the other hand, our previous studies demonstrated an opioidergic inhibition of LH release in stallions outside the breeding season. Thus, in the present study we investigated the dopaminergic regulation of LH and prolactin secretion in stallions, considering interactions between dopamine and opioids. To achieve this, stallions (n=8) were treated with the dopamine antagonist sulpiride (0.6 mg/kg), the opioid antagonist naloxone (0.5 mg/kg), sulpiride plus naloxone or saline in December, March and June. Two hours after the respective treatments, they received a GnRH agonist. Sulpiride induced a significant prolactin release which was most pronounced in December, indicating seasonal variations in the inhibition of prolactin secretion by dopaminergic systems. Prolactin concentrations were not changed by naloxone. Neither during nor outside the breeding season, a dopaminergic regulation of LH release could be demonstrated. In contrast, naloxone caused a significant (p < 0.05) LH release, confirming an opioidergic inhibition of LH release. In conclusion, opioidergic regulation of LH and dopaminergic inhibition of prolactin secretion undergo seasonal changes. Neither during nor outside the breeding season, dopaminergic effects on LH release exist in the stallion.     

Expression of Genes Associated with Apoptosis in the Porcine Corpus Luteum During the Oestrous Cycle

The corpus luteum (CL) of the pig lacks luteolytic sensitivity (LS) to prostaglandin (PG) F‐2α until after day 12 of the oestrous cycle, but the mechanisms underlying this phenomenon are poorly understood. As luteolysis involves apoptosis, we hypothesized that critical apoptotic proteins may be deficient in CLs that lack LS. The specific aim of these studies was to examine mRNA expression and protein levels of apoptosis genes/proteins (BAX/Bax, BCLX/Bcl‐x, CASP3/Caspase‐3, CASP8/Caspase‐8, NFΚB1/NFκB, TP53/p53) in porcine CLs collected at different stages of the oestrous cycle. CLs were collected surgically, mRNA and protein extracted, and expression/levels analyzed by semi‐quantitative (SQ) PCR and Western blots, respectively. At the mRNA expression level, only BAX (maximal on day 4) and TP53 (maximal on day 7) showed significant variations during the oestrous cycle. At the protein level, only Bcl‐x and Caspase‐3 showed significant changes during the cycle; Bcl‐x decreased on day 13 and Caspase‐3 increased on day 13. It is concluded that apoptosis‐associated proteins (i.e. Bcl‐x and Caspase 3) may play a critical role in luteolytic sensitivity in the pig.     

Dating pleistocene archeological sites by protein diagenesis in ostrich eggshell

Eggshells of the African ostrich (Struthio camelus), ubiquitous in archeological sites in Africa, have been shown by laboratory simulation experiments to retain their indigenous organic matrix residues during diagenesis far better than any other calcified tissue yet studied. The rate of L-isoleucine epimerization to D-alloisoleucine follows reversible first-order kinetics and has been calibrated for local temperature effects and used to estimate the age range of stratified archeological sites. Age estimates are consistent with radiocarbon dates from several stratified archeological sites. With adequate calibration, this technique can provide accurate ages to within 10 to 15 percent for strata deposited within the last 200,000 years in the tropics and the last 1,000,000 years in colder regions such as China.     

True polar wander as a mechanism for second-order sea-level variations

Long-term wander of the rotation pole can be a significant contributor to second-order (time scales of approximately 100 million years) sea-level variations. Numerical predictions based on realistic viscoelastic Earth models and paleomagnetically constrained polar motion yield global-scale, differential sea-level trends that can be as large as approximately 200 meters. From the results presented here, it is argued that the well-documented, second-order, Cretaceous-Tertiary sea-level cycle should be reinterpreted as some combination of a eustatic and a regionally varying rotational signal.     

Oxidized dietary fat,alkaline phosphatase concentrations and performance in racing greyhounds

Racing dogs are often fed raw meat. Raw meat may become oxidized because it contains no preservatives but few studies have examined the effect of feeding oxidized food to dogs. This study was originally designed to determine the effect of different concentrations of dietary fat on greyhound performance. After the experiment had been completed, however, it was discovered that the peroxide values (PV) of both diets were elevated indicating that fat oxidation had been present. This study was considered to have value, therefore, because it compared performance and blood parameters in eight trained Greyhounds fed either a high fat moderately oxidized (HFMO) diet (43%ME fat with PV of 44 mEq/kg) or a medium fat highly oxidized (MFHO) diet (31%ME fat with PV of 211 mEq/kg) for 8 weeks per diet in a randomized cross‐over design. Dogs were raced over 500 m twice weekly. Race times over the last 4 weeks of each diet period and blood parameters before racing during the last week of each diet period were compared. Dogs fed the MFHO food ran 0.04 m/s slower (p = 0.06) and serum alkaline phosphatase concentrations were higher (149 vs. 56 U/L; p < 0.0001) than in dogs fed the HFMO diet. Further evaluation is needed to determine whether lower dietary fat or increased oxidation was responsible for the altered performance but oxidation of the food should be considered as one possible explanation for an increase in serum alkaline phosphatase during a diet trial.     

Effects of Cryopreservation on Bull Spermatozoa Distribution in Morphometrically Distinct Subpopulations

Assisted sperm morphometry analysis (ASMA) was used in this study to determine the effects of cryopreservation on bull spermatozoa distribution in morphometrically distinct subpopulations. Ejaculates were collected from five bulls and were divided. One portion was diluted at 30 degrees C in a skim milk-egg yolk medium, containing glycerol. A microscope slide was prepared from single extended sperm samples prior to freezing. The remainder of each sample was frozen in nitrogen vapours. After thawing, sperm smears were prepared as described above. All slides were air dried and stained with Hemacolor. The sperm-head dimensions for a minimum of 200 sperm heads were analysed from each sample by means of the Sperm-Class Analyser (SCA), and the mean measurements recorded. Our results showed that applying the ASMA technology and multivariate cluster analyses, it was possible to determine that three separate subpopulations of spermatozoa with different morphometric characteristics coexist in bull ejaculates (large, average and small spermatozoa). The mean values of each sperm head dimension among the three subpopulations of spermatozoa were significantly different (p < 0.001). Besides, there were significant (p < 0.001) differences in the distribution of these three sperm subpopulations between fresh and thawed samples. Thus, the percentage of representation of the subpopulation that includes those spermatozoa whose dimensions are the biggest, decreased from 52.06% in extended fresh samples to 15.51% in the thawed ones. Contrarily, the percent of representation of the subpopulation containing the smallest spermatozoa, increased from 8.70% in extended fresh samples to 34.04% in the thawed ones. In conclusion, the present study confirms the heterogeneity of sperm head dimensions in bull semen, heterogeneity that vary through the cryopreservation procedure.