摘要:

Lymphocytes, plasma cells, granulocytes (three to four types), macrophages and monocyte‐like cells were ultrastructurally distinguished in the intestinal mucosa of carp. Neutrophilic granulocytes and lymphoid cells were present in and under the epithelium throughout the gut. In contrast to macrophages which dominated in the epithelium of the second segment, basophilic and eosinophilic granulocytes (and their intermediates) were mainly found in the connective tissue of the first segment. Applying monoclonal antibodies against serum immunoglobulin (Ig) in an immunogold technique, only a minority of lymphoid cells appeared to be Ig‐immunoreactive at their external membrane, suggesting the presence of many more T than B cells in the intestinal mucosa. Except for cells which resembled immature plasma cells, plasma cells did not show, or hardly showed, Ig at their surface. In contrast with the head kidney, plasma cells with an Ig‐immunoreactive cytoplasm were scarce in the intestinal mucosa. As mucosa plasma cells were regularly found with the electron microscope, they possibly contain another class of Ig. Macrophages and monocyte‐like cells were also found to be Ig‐immunoreactive, suggesting the presence of immune complexes at their external membrane. The immunological significance of B‐ and T‐like lymphocytes next to immune complex‐binding and antigen‐presenting macrophages in the second gut seg

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb02966.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Mucosal and systemic (serum) immune responses were studied after oral, anal or intramuscular (i.m.) immunization with particulate (Vibrio anguillarum) or soluble (ferritin) antigen. Antigen specific antibodies were found by ELISA in skin mucus after repeated oral or anal administration of bacteria, but not after immunization with ferritin. Daily feeding with bacteria did not give detectable antibodies in serum, while regular oral administration of ferritin resulted in an increase of specific antibodies during the first 3 weeks. From that time immunosuppression was observed, as the antibody titre decreased despite the continued ferritin feeding. Immunosuppression was also found after a second anal intubation or i.m. injection with ferritin, independent of the route of priming (i.m. or anal). On the contrary, a second anal intubation of bacteria resulted in a secondary serum response. These results combined with those reported in Parts I and II of the study indicate an important immunological role for the second gut segment. Because mucosal as well as serum responses can be obtained by anal immunization with bacteria, the significance for oral vaccination is discussed.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb02967.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Recently hatched fry of brown trout were exposed to each of eight trace metals (Al, Cd, Cu, Fe, Mn, Ni, Pb, Zn) and to a mixture of all eight, at concentrations typical of soft acid waters, in flowing artificial soft water medium at pH 4·5 and 6·5, for 30 days. At pH 4·5, in the absence of trace metals, net uptake of Ca, Na and K and skeletal calcification were impaired but mortalities were low (10%). At pH 4·5, in the presence of Al, Cu, Pb and Zn individually and the mixture, mortalities were high (87–100%). Cd, Fe, Mn and Ni at pH 4·5 each caused some mortalities (17–43%) and impaired skeletal calcification. At pH 6·5, each of Al, Cd, Cu, Fe, Mn, Pb and the mixture of metals impaired net Ca uptake and (except Al, Fe and Pb) skeletal calcification. Net K uptake was impaired by Al and by the mixture, and less severely by Cu and by Fe. Net Na uptake was impaired by Al and by the mixture, and less severely by Fe and by Mn. The role of trace metals other than Al in fisheries’decline in soft acid waters i

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb02968.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Plasma thyroid hormone levels were measured in pink salmon,Oncorhynchus gorbuscha, during their spawning migration in the Fraser River, British Columbia. The plasma levels of both l‐thyroxine (T4) and triiodo‐l‐thyronine (T3) were significantly higher in males than in females. In both sexes the hormone levels were maintained, or increased somewhat, during the early stages of migration, but fell thereafter. In females the plasma T4and T3levels of salmon collected on the spawning grounds were at or below detectable levels of the assays. The changes in thyroid hormone levels are correlated with changes in plasma insulin, gonadotropin, gonadal steroid hormones, cortisol and vitellogenin levels measured in the same spec

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb02969.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Growth dynamics of white fibres from axial muscle has been investigated in Argentine hake,Merluccius hubbsi, discriminating between sexes for the first time. The frequency distributions of fibre diameters are remarkably different in both sexes at sizes between 42 and 63·9 cm total length (T.l.). Males have a much lower proportion of newly recruited fibres (0–10 μm) than females; at 52–53·9 cm T.l., females have 4% of fibres in that category and males 0·5%. It appears that, from this size interval onwards, the increase in muscle mass is due only to the increase in diameter of individual fibres, which may exceed 300 μm. The lower recruitment rate of new fibres in males, and its relationship to lower growth rates and smaller final sizes, are discussed, and possible effects of reproductive activity are co

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb02970.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Investigations into the biology of the roach,Rutilus rutilus(L.), andLigula intestinalis(L.) populations at Slapton Ley, Devon were carried out between October 1982 and December 1984, and additional data collected from the lake since 1977 have been re‐analysed. TheLigulapopulation exhibited some unusual features: a limited specificity, a persistently low abundance and a scarcity of multiple infections. The population dynamics of the roach were also unusual in that the individual growth rate was one of the fastest in Britain, the survival was very poor and the year classes tended to alternate in strength. Whether the unusual epidemiology ofLigulacould be explained by the unusual population dynamics of the roach is investigated.The transmission period ofLigulato the roach was limited to their first few months of life, probably due to a limited period of feeding on copepods by the fry. This narrow transmission window was almost certainly the major factor that has prevented the abundance ofLigulaplerocercoids attaining high levels in the fry or of increasing in subsequent years, and has resulted in their abundance being determined entirely by transmission events to the fry. The limited transmission period has also caused the life‐cycles of the roach andLigulapopulations to become synchronized. At other localities, the abundance ofLigulais typically high, and can have a significant effect on the mortality of the host population, but, with the low abundance at Slapton,Ligula‐inducedroach mortality was insignificant. The rapid growth of the roach fry was the most likely explanation for the limited period of feeding on copepods, and the large size, short life‐span and low abundance of the roach probably also constrained the build‐up of theLigulapopulation in the lake. The random frequency distribution and scarcity of multiple infections was not considered unusual in view of the very low plerocercoid abundance. The very low abundance ofLigula, the separation of the spawning of roach and rudd in time and space, and the scarcity of rudd may account for the absence of infection in this species. It was concluded that theLigulapopulation in Slapton Ley was being constrained by the atypical population dynamics of the roach, and notvice versaas theory

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb02971.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Adult rainbow trout were acclimated to three different temperature and photoperiod regimes: 17°C, 14 h light: 10 h dark (summer); 7° C, 14 h light: 10 h dark; and 5° C, 8 h light: 16 h dark (winter). Blood was collected from these fish after 40 days acclimation, and the response of red blood cells toin vitroadrenergic stimulation was assessed. To examine potential seasonal variations in endogenous levels of circulating catecholamines, plasma levels of adrenaline (Ad) and noradrenaline (NAd) were measured at rest and after exercise. At rest, there were no differences between groups in plasma levels of either Ad or NAd, but, after exercise, the pattern of catecholamine elevation differed. In fish acclimated to 17 and 7° C in summer, Ad and NAd increased by about the same amount (10–15 times). In fish acclimated to 5° C in winter, NAd increased about three‐fold, compared to the near 50‐fold increase in Ad levels. Whether this difference between groups can be attributed to seasonal influences is unclear. At both low (0·5%) and high (2%)PCO2, adrenergic stimulation (2 × 10‐7M Ad) of trout red cellsin vitroled to a significant reduction in MCHC (mean cell [haemoglobin]), compared to non‐stimulated cells. However, only at the highPCO2were pHe and red cell pHi significantly different from those in the non‐stimulated cells: the latter was higher and the former lower in the stimulated cells. There were no differences in the response of red cells to adrenergic stimulation between groups of fish. Under the conditions of the present study no influence of season and/or temperature on thein vitroresponse of trout red cells to adrenergic sti

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb02972.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Groups of pre‐smolt Atlantic salmon were reared under three experimental photoperiods. Growth rate was significantly enhanced under 24 h of light: 0 h of darkness per diem (24 L: 0 D) compared with 16 L: 8 D and 8 L: 16 D from early January to early May. From the beginning of May until the termination of the experiment on 27 May, growth rate was highest under 8 L: 16 D.All groups developed bimodal length‐frequency distributions during the experiment. The proportion of the population in each of the two growth modes was significantly affected by photoperiod treatment.The level of plasma cortisol increased significantly from February to May. There were no differences in levels of plasma cortisol among photoperiod treatments.Judged by development in plasma cortisol, changes in condition factor and external appearance, the parr‐smolt transformation was not completed under any of the experimental photope

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb02973.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Using histochemical methods, morphofunctional aspects of the alimentary tract of larval coregonids were investigated. Larvae ofCoregonus lavaretuswere reared for 34 days with either zooplankton or one of two dry diets. Ontogeny, localization and diet‐related modifications of the following enzymes were examined: trypsin (luminal digestion), aminopeptidase, maltase, alkaline phosphatase (brush border‐bound digestion) and unspecific esterase (intracellular nutrient processing). All of the enzymes studied were present in 13‐day‐old larvae. Except for the intracellularly located unspecific esterase, there was an ontogenetic enhancement of enzyme staining intensities accompanied by a significant increase in the volume of the intestinal mucosa. Enzyme activities differed within and between intestinal regions. This finding suggests that a spatial gradient of nutrient breakdown and absorption already exists in the morphologically and physiologically incompletely developed digestive system of larval coregonids. Digestive enzyme activities were modified in response to the dietary regimen. There was no obvious correlation between enzymic response and growth performance of the

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb02974.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Brook trout were subjected to soft water at pH 6·5, 5·5 or 5·0 without aluminium added, or to water at pH 5·5 with 200,300 or 500 μg Al I‐1added. The response of the caudal neurosecretory system to low pH or aluminium was evaluated after one week by measuring the urotensin I and urotensin II concentrations in the urophysis by radioimmunoassay, and by morphometric analysis of the caudal neurosecretory cells. A positive correlation was found between urotensin I concentrations and acidity, and a negative correlation was found between urotensin II concentrations and total aluminium in the water. Morphometric indices (cell size and proportion of lobed nuclei in the caudal neurosecretory cells) suggested increased synthetic activity in the caudal neurosecretory cells of fish at pH 5·5 compared to

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb02975.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY