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291.
Norton SF 《Science (New York, N.Y.)》1988,241(4861):92-94
In contrast to the diets of other cottid fishes and most teleosts, the diet of Asemichthys taylori is dominated by gastropod mollusks. Access to this underused prey appears to be made possible by morphological speializations of the neurocanium that allow Asemichthys to puncture the shells of its prey during mastication. Unpunched, the shell and operculum act as a barrier to digestion; more than 40% of the unpunched gastropods emerged alive in the feces. Asemichthys adjusted its punching behavior in an apparently adaptive way; other prey lacking such barriers to digestion were rarely punched. The ability of some shelled invertebrates to avoid digestion may make them less desirable as prey for many fishes that cannot masticate this kind of prey. The ability of shelled mollusks to survive in the digestive tracts of vertebrates may provide a dispersal mechanism for otherwise sedentary species. 相似文献
292.
293.
Decreased proportion of CD4+ and CD8+ T lymphocytes in peripheral blood likely contributed to susceptibility to Pneumocystis carinii in a foal. Cytological evaluation of bronchoalveolar lavage was required for identification of the pathogen and serial flow-cytometric analysis of peripheral blood lymphocytes documented transient low expression of CD4+ and CD8+ T lymphocytes. Although immunodeficiency is uncommon, it must be included in the differential diagnosis for patients suffering from chronic or opportunistic infections and may provide an indication for immunostimulant therapy. 相似文献
294.
Shear WA Bonamo PM Grierson JD Rolfe WD Smith EL Norton RA 《Science (New York, N.Y.)》1984,224(4648):492-494
A new fossil site near Gilboa, New York, is one of only three where fossils of terrestrial arthropods of Devonian age have been found. The new Gilboan fauna is younger than the other two but richer in taxa. Fragmentary remains and nearly whole specimens assigned to Eurypterida, Arachnida (Trigonotarbida, Araneae, Amblypygi, and Acari), Chilopoda [Craterostigmatomorpha(?) and Scuterigeromorpha(?)], and tentatively to Insecta (Archaeognatha) have been found. The centipedes and possible insects may represent the earliest records known for these groups. 相似文献
295.
BPB Rambags AW van Rossem EE Blok E de Graaf-Roelfsema H Kindahl JH van der Kolk TAE Stout 《Reproduction in domestic animals》2008,43(4):422-428
Insulin is a pancreatic hormone that classically regulates carbohydrate and fat metabolism, but also appears to play a role in various reproductive processes. A preliminary study suggested insulin production by day 10 to 18 equine conceptuses. The aim of the present study was to examine the hypothesis that insulin is the conceptus signal responsible for maternal recognition of pregnancy (MRP) in the mare, or otherwise influences reproductive cyclicity during the MRP period. Six Warmblood mares were treated daily during days 7 to 17 after ovulation of two successive oestrous cycles with either (short and intermediate acting) insulin or control saline. Mares were assigned randomly to treatment, and crossed over during the subsequent cycle. Time of ovulation and corpus luteum surface area were determined by serial transrectal ultrasonographic examination of the mares' ovaries, and daily jugular vein blood samples were analysed for progesterone and luteinizing hormone (LH) concentrations. On day 14 of dioestrus, the luteolytic drive was examined by measuring systemic 15-ketodihydroprostaglandin F2 α (PG-metabolite) release in response to oxytocin challenge. In addition, yolk sac fluid recovered from 32 day 10 to 14 equine conceptuses was analysed for insulin concentrations. Insulin administration did not affect luteal size, dioestrus length, the interovulatory interval, or circulating LH concentrations. Insulin administration also failed to suppress oxytocin-induced PGF2 α release, and tended to depress systemic progesterone concentrations. Finally, insulin could not be detected in the yolk sac fluid of day 10 to 14 equine conceptuses by radio-immunoassay. It is concluded that insulin administered daily during days 7 to 17 of dioestrus has little or no effect on reproductive cyclicity in the mare, and is unlikely to be the MRP signal. 相似文献
296.
Donovan DC Jackson CA Colahan PT Norton N Hurley DJ 《Veterinary immunology and immunopathology》2007,118(3-4):263-269
Using an established standardized exercise test on a high-speed treadmill, thirteen Thoroughbred racehorses were exercised to fatigue (failure); blood samples were obtained before exercise, at failure, and at 2, 6, 24, 48, and 72 h after exercise. The exercise test induced a systemic inflammatory response characterized by a mild transient endotoxemia, leukocytosis, increased leukocyte expression of mRNA for tumor necrosis factor-alpha (TNF-alpha), IL-1 beta, and IL-6, and increased circulating concentrations of TNF-alpha and prostaglandin F2 alpha (PGF 2 alpha), with the most pronounced changes being evident at failure and 2h after exercise. Expression of mRNA for IL-6, TNF-alpha, and IL-1 beta was increased by 120-fold, three-fold, and four-fold, respectively, when compared to pre-exercise values. Plasma concentrations of 6-keto-PGF1alpha and PGE2 did not change in response to the exercise test. Collectively, these findings indicate that brief, strenuous exercise induces endotoxemia and a systemic pro-inflammatory response in horses that persists for at least 2h. 相似文献
297.
Wilson SM Norton P Haverson K Leigh J Bailey M 《Veterinary immunology and immunopathology》2007,117(1-2):116-123
Streptococcus suis is a major pathogen in pigs and causes significant morbidity and mortality in herds world-wide. A major problem with S. suis is the presence of asymptomatic carrier animals which can spread the organism within and between herds. The palatine tonsil is one of the main sites where the organism can be recovered, both in infected and carrier animals. The use of multiple-colour immunohistology allowed identification of the cell types associated with bacteria in the tonsils of infected gnotobiotic piglets. Bacteria were never associated with T-cells or B-cells but were always associated with cells of the myeloid lineage. Expression of CD16 and CD163 on these leukocytes suggested an association with mature macrophages in tonsil, which may lead to clearance or control of the micro-organism. 相似文献
298.
Integrated pest management has emerged as an important means of managing agricultural pests. Since the mid-1980s, the emphasis in IPM has shifted toward biologically-intensive and participatory research and extension approaches. Finding better means for solving pest problems is high on the agenda for most farmers, and farmers often have significant pest management knowledge and interest in IPM experimentation. This paper describes an approach to participatory IPM research that is being implemented by the IPM Collaborative Research Support Program (IPM CSRP). The approach emphasizes on-farm research with an extrapolation domain beyond the single farm, and in some cases beyond the local region or country. It considers many factors beyond the farm and research station that influence the generation and adoption of IPM technologies and strategies. It emphasizes linkages among farmers, scientists, consumers, bankers, marketers/processors, and policy makers in IPM research priority setting, conduct, and evaluation. The interdisciplinary approach described in the paper is illustrated with a case study from the Philippines. Lessons and conclusions draw on its recent application in other sites as well. 相似文献
299.
Histomoniasis was diagnosed in a commercial turkey flock. All morbidity and mortality occurred in one house. Birds exhibited lesions characteristic for histomoniasis, and the diagnosis was confirmed by histopathologic examination. Affected turkeys were infected with moderate levels of Ascaridia dissimilis but not Heterakis gallinarum. Compression smears of hepatic tissues showed typical histotrophic phase Histomonas meleagridis, whereas cecal smears exhibited large numbers of Trichomonas gallinarum. A challenge experiment was conducted in which turkey poults were placed on contaminated litter. Although histomoniasis was not reproduced in the experiment, the birds did become infected with low numbers of A. dissimilis. 相似文献
300.
Michael W. Pennington Shih Chieh Chang Satendra Chauhan Redwan Huq Rajeev B. Tajhya Sandeep Chhabra Raymond S. Norton Christine Beeton 《Marine drugs》2015,13(1):529-542
ShK, from the sea anemone Stichodactyla helianthus, is a 35-residue disulfide-rich peptide that blocks the voltage-gated potassium channel Kv1.3 at ca. 10 pM and the related channel Kv1.1 at ca. 16 pM. We developed an analog of this peptide, ShK-186, which is currently in Phase 1b-2a clinical trials for the treatment of autoimmune diseases such as multiple sclerosis and rheumatoid arthritis. While ShK-186 displays a >100-fold improvement in selectivity for Kv1.3 over Kv1.1 compared with ShK, there is considerable interest in developing peptides with an even greater selectivity ratio. In this report, we describe several variants of ShK that incorporate p-phophono-phenylalanine at the N-terminus coupled with internal substitutions at Gln16 and Met21. In addition, we also explored the combinatorial effects of these internal substitutions with an alanine extension at the C-terminus. Their selectivity was determined by patch-clamp electrophysiology on Kv1.3 and Kv1.1 channels stably expressed in mouse fibroblasts. The peptides with an alanine extension blocked Kv1.3 at low pM concentrations and exhibited up to 2250-fold selectivity for Kv1.3 over Kv1.1. Analogs that incorporates p-phosphono-phenylalanine at the N-terminus blocked Kv1.3 with IC50s in the low pM range and did not affect Kv1.1 at concentrations up to 100 nM, displaying a selectivity enhancement of >10,000-fold for Kv1.3 over Kv1.1. Other potentially important Kv channels such as Kv1.4 and Kv1.6 were only partially blocked at 100 nM concentrations of each of the ShK analogs. 相似文献