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31.
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Etiënne L. M. Vermeirssen Carlos Mazorra de Quero Robin J. Shields Birgitta Norberg David E. Kime Alexander P. Scott 《Aquaculture (Amsterdam, Netherlands)》2004,230(1-4):547-567
In broodstocks of Atlantic halibut, Hippoglossus hippoglossus, male and female gamete production often becomes unsynchronised towards the end of the spawning season—milt becomes very viscous and difficult to express while the females are still producing batches of good quality eggs. Gonadotrophin-releasing hormone agonist (GnRHa) has been shown to stimulate spermiation in a number of fish species. Therefore, we conducted two experiments where male halibut were implanted intramuscularly with pellets containing GnRHa. The effect of the pellets was tested at three periods: before, at the height of and at the end of spermiation. In the middle period, GnRHa was tested at two doses (5 and 25 μg/kg bodyweight). Measurements were made of milt hydration, sperm motility and fertilisation rate. Implanted males began spermiation at least 4 weeks before control males. Both doses of GnRHa increased the fluidity of the milt. This effect lasted for at least 20 days in the low dose group and for 40 days in the high dose group. When applied at the end of the season, GnRHa reversed the normal trend for the milt to become more viscous. GnRHa treatments did not affect fertilisation rates obtained with the sperm. However, towards the end of the spawning season, sperm motility was enhanced in males treated with the high dose of GnRHa (25 μg/kg) compared to controls. As described previously, plasma concentrations of the gonadal steroids, 5β-pregnane-3β,17,20β-triol 20-sulphate and 17,20-dihydroxy-4-pregnen-3-one, were significantly enhanced by GnRHa treatment. Concentrations of testosterone on the other hand decreased when spermiating males were treated with GnRHa. Our data suggest that 17,20β-dihydroxy-4-pregnen-3-one or its metabolites are involved in milt hydration, possibly through affecting ion transport. 相似文献
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Rotifers were fed on a laboratory-cultured alga, Platymonas (= Tetraselmis) suecica, and/or a diet composed of commercial single-cell proteins. They were given to sea-bass larvae up to day 15–20 after hatching, while Artemia nauplii were supplied from day 9–13. At day 21, the survival rate of fish obtained with rotifers fed on compound diet ranged between 32 and 82%, and their mean weight between 5.0 and 7.8 mg. When rotifers were fed either only on algae or on a mixture of 33% algae and 67% compound diet, the growth and survival rates of sea-bass were not clearly different to those obtained with rotifers fed on compound diet. No significant difference was observed when these rotifers were enriched with nutrients just before distributing them to fish. However, these rates appeared to be quite high in comparison to those obtained by several other authors. We can therefore recommend rotifers fed on compound diet as being, even without enrichment, convenient and low-cost food for sea-bass larvae. 相似文献
35.
- Tracking of juvenile sea turtles is a research priority to inform the protection of relevant habitats and ensure sustainable rates of recruitment into adult populations. Based on satellite tracking, mixed stock analysis, and mark–recapture studies, Drini Bay in the South Adriatic Sea, Central Mediterranean, has been confirmed as an important foraging site used by loggerhead turtles from all major rookeries in the Mediterranean subpopulation.
- Three juvenile loggerhead turtles (Caretta caretta) from Drini Bay were tracked for 763, 364, and 211 days respectively. All turtles exhibited different movement patterns.
- The two smaller turtles ranged widely beyond the bay. One of these (69.5 cm curved‐carapace length; CCL) used the coldest region of the Mediterranean during the first winter of tracking where mean weekly temperatures dipped below 12°C but moved southwards to warmer waters during the second winter. In comparison, the other (66 cm CCL) individual moved south to winter in warmer waters from the outset. Both individuals returned to Drini Bay during summer, demonstrating fidelity to the study site. The third turtle, which was larger (76 cm CCL), remained in Drini Bay for the duration of tracking. These results support the findings of other mark–recapture studies at Drini Bay, which have suggested that the foraging site is being used in a transient way by immature turtles.
- All three turtles preferentially used the shallow waters (<30 m) in the south of Drini Bay. The study demonstrates a high degree of overlap between the habitat use of the three tracked turtles and that of adult turtles tracked from nesting sites, and although based on a small sample size, contributes to a growing knowledge base regarding the wider habitat use of the Mediterranean loggerhead population.
36.
Biodiversity conservation in human-modified landscapes of Mesoamerica: Past, present and future 总被引:1,自引:0,他引:1
Fabrice A.J. DeClerck Robin Chazdon Jeffrey C. Milder Alejandra Martinez-Salinas 《Biological conservation》2010,143(10):2301-2313
Mesoamerica provides a unique context for biodiversity conservation in managed landscapes because of its geography, history of human intervention, and present conservation and development initiatives. The long and narrow form of the Mesoamerican landmass, and its division by a central mountain range, has served as both a bridge and a barrier. Conservation efforts in Mesoamerica are unique for the emphasis they place on regional connectivity through the Mesoamerican Biological Corridor and on biodiversity conservation in managed landscapes. The emphasis on conservation in agricultural systems has fostered innovations in payment for ecosystem services, and provides novel insights on the functional role that biodiversity plays in the provisioning of ecosystem services. The increasing rate of economic development in the region and the advent of new payment for ecosystem service schemes have provided new opportunities for forest regeneration and restoration. However, the small scale of private landholdings and the diversity of land uses featured in the region, while contributing to biodiversity conservation due to their structural and floristic complexity, present challenges for biodiversity monitoring and management. 相似文献
37.
Washburn KE Streeter RN Lehenbauer TW Snider TA Rezabek GB Ritchey JW Meinkoth JH Allison RW Rizzi TE Boileau MJ 《Journal of the American Veterinary Medical Association》2007,230(2):228-232
OBJECTIVE: To determine whether antemortem core needle biopsy and fine-needle aspiration of enlarged peripheral lymph nodes could be used to distinguish between inflammation and lymphosarcoma in cattle. DESIGN: Prospective study. ANIMALS: 25 cattle with enlarged peripheral lymph nodes. PROCEDURES: Antemortem biopsies of the selected lymph nodes were performed with an 18-gauge, 12-cm core needle biopsy instrument. Fine-needle aspirates were performed with a 20-gauge, 4-cm needle. Specimens were analyzed by pathologists who were unaware of clinical findings and final necropsy findings, and specimens were categorized as reactive, neoplastic, or nondiagnostic for comparison with necropsy results. RESULTS: Sensitivity and specificity of core needle biopsy ranged from 38% to 67% and from 80% to 25%, respectively. Sensitivity of fine-needle aspiration ranged from 41% to 53%, and specificity was 100%. Predictive values for positive test results ranged from 77% to 89% for core needle biopsy and were 100% for fine-needle aspiration. Predictive values for negative test results were low for both core needle biopsy and fine-needle aspiration. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that core needle biopsy and fine-needle aspiration can aid in the antemortem diagnosis of bovine enzootic lymphosarcoma. Results of fine-needle aspiration of enlarged peripheral lymph nodes were more specific and more predictive for a positive test result than were results of core needle biopsy. 相似文献
38.
Quantitative trait loci for phytate in rice grain and their relationship with grain micronutrient content 总被引:6,自引:0,他引:6
James C. R. Stangoulis Bao-Lam Huynh Ross M. Welch Eun-Young Choi Robin D. Graham 《Euphytica》2007,154(3):289-294
Phytate (inositol-hexa-phosphate) has an important role in plants but it also may have anti-nutritional properties in animals
and humans. While there is debate within the plant breeding and nutrition communities regarding an optimum level in grain,
there appears to be little information at the molecular level for the genetics of this trait, and its association with important
trace elements, in particular, Fe and Zn. In this preliminary study, quantitative trait loci (QTL) for grain phytates, Zn
and Fe in glasshouse-grown rice lines from an IR64 × Azucena doubled haploid population were identified. Correlations between
phytate and essential nutrients were also studied. Transgressive segregation was found for most traits. Phytate and total
P concentrations had one QTL in common located on chromosome five with the (high concentration) allele contributed from Azucena.
There were significant positive correlations between phytate and inorganic phosphorus (P), total P, Fe, Zn, Cu and Mn concentrations
for both grain concentration and content. However, the QTLs of phytate were not located on the same chromosomal regions as
those found for Fe, Zn and Mn, suggesting that they were genetically different and thus using molecular markers in breeding
and selection would modify the phytate level without affecting grain micronutrient density. 相似文献
39.
Annet Namayanja Robin Buruchara George Mahuku Patrick Rubaihayo Paul Kimani Stephen Mayanja Hellen Eyedu 《Euphytica》2006,151(3):361-369
Inheritance of resistance to angular leaf spot (ALS) disease caused by Phaeoisariopsis griseola (Sacc.) Ferr was investigated in two common bean cultivars, Mexico 54 and BAT 332. Both Andean and Mesoamerican backgrounds were used to determine the stability of the resistance gene in each of the two cultivars. Resistance to P. griseola was phenotypically evaluated by artificial inoculation with one of the most widely distributed pathotypes, 63–39. Evaluation of the parental genotypes, F1, F2 and backcross populations revealed that the resistance to angular leaf spot in the cultivars Mexico 54 and BAT 332 to pathotype 63–39 is controlled by a single dominant gene, when both the Andean and Mesoamerican backgrounds were used. Allelism test showed that ALS resistance in Mexico 54 and BAT 332 to pathotype 63–39 was conditioned by the same resistance locus. Resistant and susceptible segregating populations generated using Mexico 54 resistant parent were selected for DNA extraction and amplification to check for the presence /absence of the SCAR OPN02 and RAPD OPE04 markers linked to the Phg-2 resistance gene. The results indicated that the SCAR OPN02 was not polymorphic in the study populations and therefore of limited application in selecting resistant genotypes in such populations. On the other hand, the RAPD OPE04 marker was observed in all resistant individuals and was absent in those scored susceptible based on virulence data. Use of the RAPD OPE04 marker in marker-assisted selection is underway. 相似文献
40.