The structure of the upper atmosphere of mars: In situ accelerometer measurements from mars global surveyor

The Mars Global Surveyor (MGS) z-axis accelerometer has obtained over 200 vertical structures of thermospheric density, temperature, and pressure, ranging from 110 to 170 kilometers, compared to only three previous such vertical structures. In November 1997, a regional dust storm in the Southern Hemisphere triggered an unexpectedly large thermospheric response at mid-northern latitudes, increasing the altitude of thermospheric pressure surfaces there by as much as 8 kilometers and indicating a strong global thermospheric response to a regional dust storm. Throughout the MGS mission, thermospheric density bulges have been detected on opposite sides of the planet near 90 degreesE and 90 degreesW, in the vicinity of maximum terrain heights. This wave 2 pattern may be caused by topographically-forced planetary waves propagating up from the lower atmosphere.     

Effect of different mini‐volume colloid centrifugation configurations on flow cytometrically sorted sperm recovery efficiency and quality using a computer‐assisted semen analyzer

Straws of sex‐sorted sperm are usually packaged at a low concentration (e.g., ~2.1 × 10⁶ sperm/ml) and cost significantly more than unsorted conventional semen from the same sire. In order to maximize the efficiency of using sex‐sorted sperm under in vitro fertilization conditions, the selection of an appropriate sperm separation technique is essential. In this study, the effect of using different silane‐coated silica colloid dilutions and layering configurations during centrifugation of sex‐sorted sperm was examined over an extended period of incubation time. Sperm recovery and viability after centrifugation using the colloid separation technique were measured along with several sperm motility parameters using CASA. For this purpose, frozen and thawed sex‐sorted sperm samples were centrifuged using mini‐volume single‐layer (40%, 60% and 80%) and mini‐volume two‐layer (45%/90%, 40%/80% and 30%/60%) separation configurations using PureSperm^®. A single layer of 40% PureSperm^® recovered significantly more sex‐sorted sperm (78.07% ± 2.28%) followed by a single layer of 80% PureSperm^® (68.43% ± 2.33%). The lowest sperm recovery was obtained using a two‐layer PureSperm^® dilution of 45%/90% (47.57% ± 2.33%). Single‐layer centrifugation recovered more sorted sperm (68.67% ± 1.74%) than two layer (53.74% ± 1.74%) (p < .0001). A single layer of 80% PureSperm^® exhibited the highest sorted sperm viability (72.01% ± 2.90%) after centrifugation (p < .05). The mini‐volume single layer of 80% PureSperm^® was determined to be an effective alternative to a two‐layer centrifugation configuration for sex‐sorted sperm selection. In addition, single‐layer colloid dilution of 80% performed either as well as or significantly outperformed the other treatments, as well as the control, with regard to motility (MOT) for all time periods of analysis.     

Hyperostotic polyarthropathy in a rabbit - a suspected case of chronic hypervitaminosis A from a diet of carrots

Chronic hypervitaminosis A can occur in many species after excessive dietary intake of Vitamin A (retinol). The most common presentation of chronic hypervitaminosis A is a polyarthropathy with hyperostosis and ankylosis of various joints. This case report describes a probable case of naturally occurring hypervitaminosis A-induced polyarthropathy in a rabbit after chronic ingestion of a diet made up almost exclusively of carrots. Carrots do not contain retinol, but are rich in provitamin A (or beta-carotene). Rabbits are unique in that they can convert 100% of dietary beta-carotene into retinol. A syndrome of naturally occurring hypervitaminosis A-induced polyarthropathy has not been described in a rabbit before.     

Local Effect of the Corpus Luteum on Ovarian Follicular Functional and Morphological Features in the Goat

Ovaries of unilaterally ovulated goats (n=21) were used to study follicular morphological features (proportion and degree of atresia, oestradiol production in vitro and progesterone production of granulosa cells in culture). Follicles were dissected out and classified as small (1–2 mm), medium (2–4 mm) and large (>4 mm). Morphological and physiological features were compared in each size class between ovaries bearing and not bearing corpora lutea (CLO and NCLO, respectively). Within the same size class, there was no difference in proportion or in degree of atresia, between CLO and NCLO. A significant effect of follicular size on oestradiol production in vitro was detected, but no effect of the corpus luteum was found. Finally, progesterone production of granulosa cells in culture was significantly higher in CLO than in NCLO after 24 h (p < 0.05) and also after 90 h (p < 0.01) of culture. This higher progesterone production by CLO granulosa cells in culture could be explained by local influence of the corpus luteum stimulating the steroidogenic activity but not aromatase activity. Further studies are needed to clarify possible factors and pathways for this local effect of the corpus luteum upon follicular physiology.     

Effect of farmers' seed selection on genetic variation of a landrace population of pepper (Capsicum annuum L.), grown in North-West Italy

Recognition by the European Community of élite landraces encourages farmers to grow these and earn more than is possible by growing modern varieties. However, farmers often exercise strong selection by collecting seed from a limited number of plants which best embody a few characters of prime interest. This, in the long run, may be responsible for considerable genetic erosion. In Southern Piedmont, North-West Italy, a local landrace of pepper (Capsicum annuum L.) known as Cuneo is grown; it deserves particular attention because of its hardiness, late production and fruit quality. We used random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) markers to assess the effect, on genetic composition of a population, of seed sampling carried out using the selection criteria adopted by the farmer. After two reproductive cycles using selection, it was already possible to detect loss in genetic variation and a change in allele frequencies, while no significant effect was found after two cycles of random sampling. Over this period, farmer selection pressure led to disappearance of eight low-frequency alleles, while only three alleles were lost in randomly sampled populations. Our results stress the need to adopt appropriate techniques for seed sampling in order to avoid genetic erosion of local landrace gene pools.     

Characterisation of porcine haemophili isolated from Australian pigs between 1988 and 1992

SUMMARY A total of 362 haemophili, isolated from pigs throughout Australia, were characterised by phenotypic properties. Most were identified as Actinobacillus pleuropneumoniae (296 isolates) or Haemophilus parasuis (52 isolates). The remaining isolates were identified as Haemophilus Taxon ‘minor group’ (12 isolates) and Haemophilus Taxon D (two isolates). All 296 A pleuropneumoniae isolates were serotyped by slide agglutination and/or gel diffusion, using rabbit antisera against all 12 recognised serovars. Of these, only 156 (52.7%) could be assigned to a single serovar as follows: serovar 1–85 isolates, serovar 2–4 isolates, serovar 3–2 isolates, serovar 5–10 isolates, serovar 7–51 isolates, serovar 11–2 isolates and serovar 12–2 isolates. Of the remaining 140 isolates, 91 gave cross-reactions with serovars 3 and 6, one cross-reacted with serovars 9 and 10, one cross-reacted with serovars 9 and 11 whereas 47 gave no reaction with any of the antisera.