GABA-ergic control of prolactin release in rainbow trout (Oncorhynchus mykiss) pituitaries in vitro

The involvement of γ-aminobutyric acid (GABA) in the control of prolactin (PRL) release was investigated in rainbow trout using both perifused pituitary fragments and pituitary cells in primary culture. In our perifusion system, infusion of GABA (10⁻⁶ to 10⁻⁴ M) caused an inhibition of PRL release (between 20 and 40%). Administration on perifused pituitary fragments of 3APS, a GABAa agonist, mimicked this inhibitory effect. Moreover, bicuculline, a specific antagonist of GABAa receptors, totally abolished GABA effect. When tested on cultured pituitary cells during 40h exposure, GABA (10⁻⁵ M) caused a significant decrease in PRL release (24.5%). Baclofen, a specific agonist for GABAb receptor tested at 10⁻⁶ and 10⁻⁵ M, also inhibited PRL released from cultured pituitary cells. These results demonstrate that GABA inhibits PRL release by acting directly on pituitary cells and that probably both types of GABA receptor (a and b) are involved in this regulation.

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Résumé Nous avons étudié l'implication de l'acide γ-aminobutirique (GABA) dans le controle de la sécrétion de prolactine (PRL) chez la truite arc-en-ciel en utilisant à la fois des fragments d'hypophyse perifusés et des cellules hypophysaires en culture. Dans notre système de périfusion, le GABA (10⁻⁶ à 10⁻⁴ M) inhibe la libération de PRL (entre 20 et 40%). L'administration sur les fragments d'hypophyse périfusés de 3APS, un agoniste des récepteurs GABAa, reproduit ces effets inhibiteurs. De plus, la bicuculline, un antagoniste spécifique des récepteurs de type GABAa, abolie complètement les effets du GABA. Lorsqu'il est testé pendant 40h sur des cellules en culture, le GABA (10⁻⁵ M) réduit de manière significative la libération de PRL (24.5%). Le Baclofen, un agoniste spécifique des récepteurs GABAb testé à 10⁻⁶ et 10⁻⁵ M, inhibe aussi la libération de PRL par les cellules en culture. Ces résultats démontrent que le GABA inhibe la libération de PRL en agissant directement sur les cellules hypophysaires et que les 2 types de récepteurs GABA (a et b) sont impliqués dans cette régulation.

     

Growth, fatness and gross biochemical composition of the Japanese oyster, Crassostrea gigas, in Stanway cylinders in the Bay of Arcachon, France

A new method of oyster cultivation, the Stanway oyster cylinder, has been investigated in the Bay of Arcachon since 1989. A comparative study was carried out between the growth of spat and 18-month-old Crassostrea gigas oysters, in cylinders and in traditional bags. The growth in height and in whole weight was lower in cylinders. In contrast, the tests showed a better quality of the meat, with higher condition index and higher carbohydrate content, and a better quality of the shell, with higher density and better shape. Therefore, because of the improvement in oyster quality, the use of the cylinder seems to be advantageous for the Arcachon oyster industry.     

Improvements required for the detection of Salmonella Pullorum and Gallinarum

Detection of the specific Salmonella serovar Gallinarum, which is divided into the biovars Pullorum and Gallinarum, is compulsory under the national hygienic and sanitary control regulations of France for breeding flocks whose offspring are exported. Our aim was to examine the suitability of bacteriologic and serologic methods routinely used in France to screen serum samples and organs for S. Gallinarum. Since bacteriologic reference techniques are designed to isolate the commonly occurring non-typhoid serovars, such as S. Typhimurium, S. Enteritidis, and others that cause outbreaks of foodborne illness, they may not be particularly suitable for detecting S. Pullorum and S. Gallinarum. This hypothesis was confirmed by the inoculation of 10-wk-old chickens and 1-d-old chicks with various strains of S. Pullorum and S. Gallinarum. The most reliable enrichment media were selenite cystine and Rappaport-Vassiliadis broths. Moreover, on the usual plating media, colonies were small, grew more slowly than the common serovars (in 48 h instead of 24 h), and had an unusual appearance. Since the rapid slide agglutination (RSA) test is based only on antigens from standard and variant strains of S. Pullorum, it may not readily detect S. Gallinarum. In our study, it detected infection in all 10-wk-old chickens inoculated with S. Pullorum strains but did not detect any antibodies against S. Gallinarum. Therefore, S. Gallinarum antigens must be added to the S. Pullorum antigens used in the RSA test in order to detect antibodies produced by birds infected with either biovar.     

Evaluation of papillomaviruses associated with cyclosporine-induced hyperplastic verrucous lesions in dogs

OBJECTIVE: To determine whether cyclosporine A-induced hyperplastic skin lesions of dogs were associated with papillomavirus infections. ANIMALS: 9 dogs that were treated with cyclosporine A and developed hyperplastic skin lesions. PROCEDURE: History and clinical and histopathologic data were collected. Paraffin-embedded skin biopsy specimens from hyperplastic skin lesions were immunostained for common papillomavirus genus-specific structural antigens by use of a polyclonal rabbit anti-bovine papillomavirus type 1 antiserum. Sections from each tissue block underwent DNA extraction, and polymerase chain reaction (PCR) assays were performed with several sets of primers to amplify a wide range of papillomavirus DNA from humans and other animals. RESULTS: In 7 of 9 dogs, there were more than 10 hyperplastic skin lesions that microscopically resembled those of psoriasiform lichenoid dermatosis. In those dogs, results of testing for papillomavirus via immunohistochemical analyses and PCR assays were negative. In the other 2 dogs, there were only 1 and 3 verrucous lesions, and in those dogs, histologic evaluation revealed koilocytes and nuclear viral inclusions that were immunoreactive for papillomavirus antigens. Papillomavirus DNA was amplified from both dogs. One of the sequences was characteristic for the canine oral papillomavirus, whereas the other had similarities with the recently described canine papillomavirus 2. CONCLUSIONS AND CLINICAL RELEVANCE: In dogs, hyperplastic skin lesions occasionally develop during treatment with cyclosporine A. Most of the lesions resemble those of psoriasiform lichenoid dermatosis, although papillomavirus can be detected in some instances.     

Relative expression of matrix metalloproteinase-2 and -9 in synovial fluid from healthy calves and calves with experimentally induced septic arthritis

OBJECTIVE: To identify changes over time in relative expression of matrix metalloproteinase-2 (MMP-2) and -9 (MMP-9) in synovial fluid from healthy calves and calves with experimentally induced septic arthritis. ANIMALS: 12 Holstein calves. PROCEDURES: In 7 calves, Escherichia coli was injected in the right tarsal joint on day 1. Joint lavage was performed on day 2, and calves were treated with ceftiofur from days 2 through 21. Synovial fluid samples were collected on days 1 (before inoculation), 2 (before joint lavage), 3, 4, 8, 12, 16, 20, and 24. In the remaining 5 calves, joint lavage was performed on day 2 and synovial fluid samples were collected from the left tarsal joint. Relative expression of MMP-2 and MMP-9 was determined by means of gel zymography. RESULTS: On day 1, MMP-2 was detected in all synovial fluid samples but MMP-9 was not detected. In calves with septic arthritis, values for relative expression of MMP-9 monomer and dimer were significantly increased on days 2 through 20 and days 2 through 24, respectively, and relative expression of MMP-2 was significantly increased on days 3 through 20. There were significant linear associations between relative expression of the monomer and dimer forms of MMP-9 and between neutrophil count and relative expression of the MMP-9 monomer and dimer forms. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that relative expression of MMP-9 and MMP-2 increased in synovial fluid from calves with experimentally induced septic arthritis, with relative expression remaining high for several days after infection.     

Use of magnetic resonance imaging in the diagnosis of upper respiratory obstruction in a calf

In a calf with dyspnea, a mass located dorsal to the pharynx was visualized by ultrasonography. Magnetic resonance imaging (MRI) revealed a severe enlargement of the left medial retropharyngeal lymph node, compatible with an abscess. This is the first reported case of MRI use in bovine upper respiratory disease.     

Radiographic detection of thoracic lesions in adult cows: a retrospective study of 42 cases (1995-2002)

Medical records of 42 cows that underwent both thoracic radiographic and postmortem examinations within a period of 7 days were reviewed to develop an evaluation grid to interpret bovine thoracic radiographs and to determine the sensitivity and the specificity of thoracic radiographs for detection of thoracic lesions, based on postmortem examination. Most cows (64%) had clinical signs of respiratory disease, whereas 19% showed signs of cardiac problems. The sensitivity and specificity of radiographs for identifying cows with thoracic lesions were 94% and 50%, respectively. In this study, with a prevalence of thoracic lesions of 86%, the positive- and negative-predictive values were 92% and 57%, respectively. This study provides an evaluation grid that allows standardization of the reading of bovine thoracic radiographs and the identification of most thoracic lesions. Bovine thoracic radiographs are useful in detecting thoracic lesions in cows.     

Differentiation between two sub-species of <Emphasis Type="Italic">Acacia senegal</Emphasis> complex: <Emphasis Type="Italic">Acacia senegal</Emphasis> (L.) Willd. and <Emphasis Type="Italic">Acacia dudgeoni</Emphasis> Craib ex Holland using morphological traits and molecular markers

The Acacia senegal complex is formed by closely related species of Acacia senegal (L.) Willd. These species share several botanical characters, so from a morphological point of view, there is no clear discontinuity between some of them. A. dudgeoni Craib ex Holland is one species of the A. senegal complex that was formerly described as A. senegal ssp. senegalensis var. samoryana (A. Chev.) Rob. In order to differentiate Acacia senegal from A. dudgeoni, we analyzed a range of morphological traits such as tree height and diameter in natural stands, and, at the nursery stage, seedling height, number of branches, main root depth, biomass dry weight and leaf characteristics. Within addition, molecular polymorphism analyses were conducted using 11 microsatellite markers. Leaf characteristics and molecular markers appear to be the most effective tools to distinguish A. senegal from A. dudgeoni. These tools can improve our understanding of the relationship between two species belonging to the same species complex.     

Genetic diversity,population structure and differentiation of rice species from Niger and their potential for rice genetic resources conservation and enhancement

Rice genetic resources conservation and evaluation is crucial to ensure germplasm sources for further crop breeding. We conducted a wide collection of Oryza species in Niger and characterize its diversity with microsatellites (or simple sequence repeats, SSR). The aims of this research were to get a better understanding of the extent of genetic diversity, its structure and partition within rice eco-geographical zones of Niger. There were 264 accessions found in farmers’ and other fields: 173 O. sativa (Asia’s rice), 65 O. glaberrima (Africa’s rice), 25 O. barthii, and 1 O. longistaminata (weedy perennial rice), which were genotyped with 18 SSR. A total of 178 alleles were detected, with a mean of 9.89 alleles per locus. The polymorphism information content was 0.65 and heterozygosity was estimated as 0.14. Two main well-differentiate genotypic groups, which correspond to Asian and African rice species, were identified. The SSR set divided the Asia’s rice group (solely indica) into irrigated and floating rice, with rainfed lowland rice in between. The African rice species group was composed of O. glaberrima, O. longistaminata and O. barthii accessions, but without any clear genetic differentiation among them likely due admixtures within the samples of O. barthii. Five accessions that could be natural interspecific hybrids were too admixed for assigning them to any of the two well-differentiated groups. The partitioning of the overall diversity showed that maximum variation was within genotypic groups and subgroups or cropping ecologies, rather than between eco-geographical zones. The eco-geographical distribution of the diversity suggests germplasm exchange in Niger. Next-steps for conserving rice and crop wild relatives in Niger could be taken using the findings of this research.