摘要:

A study of enzyme polymorphism by electrophoretical techniques permitted the genetic structure and the homogeneity degree of the plaice population present in the Abers Wrac'h and Benoit along the north‐west coast of Brittany to be determined. Thirteen enzymic systems encoded by 21 loci were analysed and nine of these loci were polymorphic at the 5% level. The comparison of allelic frequencies and of observed heterozygosityhobsdid not show significant differences between these two individual groups. Nei's genetic identity (I= 0.998) and distance (D= 0.002) as estimated from allelic frequencies showed that the plaice of the two estuaries are very similar.Thus, the plaice of A. Wrac'h and of A. Benoit belong to the same population in which the average level of polymorphism per locusPis 47% and the observed average heterozygosity per individualHobsis 0.163 ± 0.0

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb03013.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

An account is given of certain aspects of the biology of the garfish,Belone belone, captured by sea anglers from Courtmacsherry Bay, Co. Cork. Fish were aged by otoliths, and found to grow most rapidly in their first 2 years, females attaining a greater mean size than males. Most of the fish caught had already spawned. From examination of their gonads and lengths of juveniles collected in the neuston, spawning would appear to take place there mostly in the month of June.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb03014.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The testicular gland (t.g.) is a glandular tissue situated adjacent to the testis of blenniid and several gobiid species. In the present study the t.g. ofBlennius pavoRisso andGobius nigerL. were compared by histological and histochemical methods. InB. pavothe spermatozoa have to cross the t.g. to reach the vas deferens and thus they come into contact with the gland cells, whereas in G.nigerthe vas deferens is situated between the testis and the t.g. The fine structure and histo‐chemistry of the t.g. cells reveal that inB.pavothe cells of the t.g. have exocrine as well as endocrine functions. The t.g. cells ofB. pavocontain large amounts of lipids, form a secretion containing acid mucopolysaccharides, show positive reaction for acid phosphatase, and some cells stain for 3β‐HSD and G6PD. The function of the t.g. ofG. nigeris exclusively endocrine. Characteristics of the gland cells of this species are well developed smooth ER and tubulovesicular or paracristal‐line mitochondria. The stainings for 3β‐HSD, G6PD and UDPGD give strong positive results in the whole t.g., indicating the presence of steroids and steroid glu

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb03015.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The fish assemblage on the shallow coralligenous shelf (16‐30m depth) off Haifa, Israel was sampled using trammel nets throughout a period of 1 year. Complementary data were obtained via underwater censuses of fish on an artificial reef established later in the sampling area. Fortythree species of fish were sampled by trammel nets, 79% of which were observed also during the underwater censuses. Although fish of Red Sea origin constituted only 11.6% of the species composition in the net samples, they contributed 46.2% of the fish abundance and 40.6% of the biomass in these samples. This was supported by the finding that species of Red Sea origin contributed 64% of the abundance of large fish counted on the artificial reef.Siganus luridas, S. rivulatusandSargocentron rubrumare the main contributors in number and biomass among fish of Red Sea origin. It is suggested that the biogenic rocky bottom of this area contains several components which are similar to biogenic habitats favoured by these benthic species in the Red Sea; this may explain the high abundance of these species in the studied are

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb03016.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

TheLdh‐5locus, which codes for the eye‐specific lactate dehydrogenase in brown trout, has been shown to be polymorphic for two codominant alleles,Ldh‐5 (100) and Ldh‐5 (90).TheLdh‐5 (100) allele is present in 11 other salmonid species and is therefore likely to be the ancestral one, whereas the unique brown troutLdh‐5 (90) allele would seem to be the result of a mutation in that lineage. TheLdh‐5 (90) allele appears to have arisen in north‐west Europe during or after the last glaciation, with allelic substitution taking place under the action of natural selection. TheLdh‐5 (90) allele can be used as a phylogeographic marker to trace the post‐glacial spread of the populations possessing it. Examination of the current distribution of the two alleles suggests that, in the formerly glaciated area of north‐west Europe, there have been two post‐glacial colonizations by brown trout. The first was by an ‘ancestral’ race fixed for theLdh‐5(100) allele. This was later replaced by, or introgressed with, the later‐arriving ‘modern’ race characterized by theLdh‐5 (90) allele, except where physical barriers prevented colonization by this latter form. Artificial stocking has resulted in ‘genetic contamination’ of many populations of the ancestral race and there is an urgent need to conserve the remaining pristine populations, especially in view of the likely genetic propensity for longevity and u

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb03017.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Tissue samples from a total of 617 Atlantic salmon from seven locations in north‐east Ireland were electrophoretically examined for genetic variation at 28 enzyme loci. Patterns of allelic variation at eight polymorphic loci indicated the existence of genetic differentiation within, as well as among, river systems. This suggests the presence of localized genetically differentiated populations of salmon in N. Ireland. Temporal variation in allelic frequencies was tested among three year classes of wild R. Bush salmon and found to be insignificant compared to the spatial variation. Examination of equivalent year classes of R. Bush hatchery‐reared salmon displayed significant temporal variation at five loci, and significant departures from Hardy‐Weinberg equilibrium at two loci. Heterozygosity was not reduced in the Bush hatchery population (mean 4.3%) compared to the wild populations sampled (range, 2.9‐5.4%; mean, 4.2%). These results are discussed in relation to management of wild populations and maintenance of hatchery

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb03018.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

It proved possible to determine the levels of Sr‐90 in the opercular bones of individual pike,Esox Iucius, and in pooled samples of bones from perch,Perca fluviatilis. Results from both species from Windermere demonstrated that Sr‐90 levels rose from below the detection limits in the 1940s to a peak in the 1960s, followed by a decline in the subsequent two decades. This decline was slower than would have been expected from the decline in northern hemisphere Sr‐90 fallout, indicating the likelihood of recycling within the environment. Sr‐90 levels were consistently lower in pike than in perch, their main prey fish. Thus, there is no concentration of Sr‐90 up this part of the aquatic food chain. Tracking Sr‐90 in bones taken in successive years from ages 3 to 8 for a single cohort of pike showed that the quantity of Sr‐90 was closely related to opercular bone (and hence fish) weight. No significant increase in Sr‐90 concentration in the bone with increasing age w

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb03019.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Mitochondrial DNA was examined in natural and hatchery‐reared stocks of brown trout, using different methods of restriction analysis. The methods included the development of a brown trout mt DNA hybridization probe through cloning part of the brown trout mitochondrial genome. In addition, fragments were analysed by ethidium bromide staining and end‐labelling. The relative merits of each of these methods in assessing levels of genetic relatedness between the natural and hatchery‐reared brown trout stocks were evaluated. In addition, the study revealed a diagnostic mtDNA restriction pattern which could be used as a genetic marker for the discrimination of these two groups of brown

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb03020.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Routine oxygen consumption rates of juvenile spot,Leiostomus xanthums, were measured over a range of temperatures, salinities and fish weights. As predicted,QO2increased with temperature and decreased with body weight. However,QO2decreased with decreasing salinity and did not show the expected minimum at isosmotic concentrations. The data are best described by the relationship: log10QO2(mg O2g−1h−1) = 0.129 loglosalinity (%0) + 1.604 log10temperature (°C)‐0.1401og10(g)

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb03021.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Growth and the development of gills, muscle fibres and 10 enzymes serving different metabolic functions were studied in larvae ofRutilus rutilus(L.) andChalcalburnus chalcoides(Agassiz, 1832).R. rutilusstarts swimming and feeding one to three days after hatching, whereas in C.chalcoidesthis process is delayed by about 10 days. This difference in behaviour is reflected in the time‐course of growth, the differentiation of the red muscle fibres and the activity of the enzymes of aerobic energy metabolism. On the other hand, the activity of the enzymes of anaerobic energy metabolism increases steadily throughout the period of observation (up to 60 days post‐hatch), this trend being more pronounced inC. chalcoidesthan inR. rutilus. A weight‐independent and a weight‐dependent phase of development can be distinguished in the enzymes of aerobic energy metabolism. It is suggested that, in accord with previous findings, the early phase of locomotor activity of cyprinid larvae is fuelled mainly by aerobic processes, and that the central muscle mass of the larvae is more aerobic than the white muscle fibres of the adults. The delayed development of aerobic enzyme activity inC. chalcoidesis compensated by the accelerated development of anaerobic enzyme activity, particularly of creatine kinase and lactate dehydrogenase. This difference between the two species studied suggests differences in the metabolic basis of burst a

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1989.tb03022.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY