摘要:

SummaryTemporal variation and sexual dimorphism were found in the skin of the caudal fin of wild perch from the Baltic Sea. For most of the year males had thicker skin than females. Both sexes were found to have the highest recorded epidermal thickness in the pre‐spawnin period, indicating a relation with the reproductive cycle. However, the reverse pattern occurred in the dermis, i.e. an increased thickness in the post‐spawning period. The study also demonstrated that temporal variation and sexual dimorphism of the epidermis were, at least partially, the result of variation both in the number and in the size of epithelial cells. Temporal variation of the cellular components was also found, with an increased prevalence of vesicle‐containing epithelial cells during the pre‐spawning

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1994.tb00155.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryThe expressions of factorial (s̀2s) and stochastic (s̀2s) components of henotypic variance of bilateral characters are given, regarding simple connection of the latter to the fluctuating asymmetry indicator, being traditionally used for assessment of developmental stability. The values of both components were calculated for 5 meristic characters in 172 samples of bream collected over most of its geographic range. The s̀2svalues were to indicate possible effects of genetic disbalance and to measure environmental stress, while s̀2swas regarded as a rough estimate of the genetical heterogeneity. It was found that s̀2svalues tended to grow in following situations: a) zones of interpopulational contacts or in populations with unusual morphology; b) zones of increased anthropogeneous pollution, in particular In the lower parts of the artificial reservoirs as compared to the upper arts and the majority of rivers and lakes. On the other hand, s̀2fvalues in lakes appeared to be lower than in rivers, probably due to comparatively low genetic heterogeneity of the lake populations. The whole set of samples exhibits another clear trend: negative correlation between s̀2sand s̀2f, which seems to illustrate a well‐known connection between developmental homeostasis and heterozygosity. A conclusion may be made that the phenotypic variance components are useful in ecological and genetical monitoring of large population systems, although the data are often difficult to interpret properly for separate po

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1994.tb00156.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummarySpermiation was stimulated in the European catfishSilurus glanisL. by injection of carp pituitary preparation (5 mg kg‐1of body weight) and mammalian GnRH [(D‐Ala6) en‐RH ProNHEt] implanted at a dose of 75 μg and 150 μg per male, respectively. The total number of spermatozoa collected by daily sampling during 7 days post‐stimulation and expressed in millions per kg of body weight was 3.29 with carp pituitaries, 0.872 and 0.780 with 75 μg and 150 μgGnRH anjoue implant, respectively, and 0.387 in the control group treated with Ringer solution. In all groups, after sperm stripping there was a spontaneous activation by urine of the sermatozoa motility which was revented by collection of the sperm in an immobilizing solution (NaCl 200 mM, Tris 30 mM, pH 7). The percentage of motile spermatozoa ranged from 80 to 65% at days 1 to 5, and less than 50% at day 6 and 7. A similar decline of quality was observed with time for mass progressive movement (55 to 65 s on day 1, and 28 to 35 s on day 7) and total duration of displacement (66 to 77 s on day 1, and 45 to 5

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1994.tb00157.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryA cDNA fragment of 302 bp coding for the mature region of the gonadotropin α‐subunit of the yellowfin porgy (Acanthopagrus latusHouttuyn 1782) was isolated by polymerase chain reaction (PCR). This PCR product was engineered into theEscherichia coliexpression vector pRE1 which is based on the lambda PL/cIItranscription‐translation system. The resultant recombinant construct pREYP1 was introduced intoE. coliMZ‐1 and resulted in the expression of the recombinant α‐polypeptide of gonadotropin of 14 kilodaltons (kDa) in the cell extracts. The intensity of the 14 kDa protein band on the SDS‐polyacrylamide gel increased in relation to the length of the induction time periods. ThisE. coli‐produced 14 kDa protein showed a positive immunoreaction with the rabbit polyclonal antiserum against the natural carp

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1994.tb00158.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryThe resence of a rusty‐yellow discolouration of the skin of the two tilapia species being cultured at the African Regional Aquaculture Centre (ARAC) was studied using clinical and epizootiological methods. The condition affected the tilapia species only. Ante‐mortem and post‐mortem examination revealed that the discolouration was restricted to the surface of the cutaneous tissue; affecting the underside of the exposed part of the scales, the fins, and the skin flap covering the scale pockets, mostly in adult fish. Microbiological and histopathological studies, as well as experimental infection trials demonstrated that a rosette‐shaped, filamentous gram‐positive bacterium, was the aetiologic agent. This organism was characterised as anActinomycesspecies based on standard microbiological techniques. Correlation between physico‐chemical parameters of the pond water and the prevalence of the skin discolouration, suggested a possible relationship to low dissolved oxygen. The prevalence of the skin discolouration was observed to increase over the 4‐month culture period, being somewhat greater in a non‐integrated than in an integrated culture system at harvest. Efforts to control the condition with available chemotheraeutics (mostly disinfectants and antibiotics) were ineffective although the organism was observed to ge sensitiv

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1994.tb00159.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryAeromonas hydrophilawas the predominant bacteria isolated from the haemorrhagic lesions and necrotic ulcers in the seven species of fish,Etroplus suratensis, Ophicephalus striatus, Puntius sarana, Rasbora danicornius, Trichogaster pectoralis, Tor khudree lonispinnisandWallago attuaffected by eizootic ulcerative syndrome(EUS), during the 1990 and 1991 disease outbreaks in Sri Lanka. Severely affected fish were truly septicemic, asA. hydrophilawas recovered from their internal organs.A. hydrophilaisolated from diseased fish and injected intramuscularly into healthyE. suratensisand O.striatusinduced dermonecrotic lesions resemblin EUS. The results suggests thatA. hydrophilais consistently associated with EUS in Sri Lanka anf may play an important role in the patlogenesis of the disease.

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1994.tb00160.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

SummaryCuming's barb (Puntius cumingiiGunther) is an endangered endemic species of fish in Sri Lanka. A study was carried out on the reproductive biology and breeding of this species in captivity. At maturity, males and females measured 32.6 and 33.1 mm, respectively. In the ovaries, the egg‐diameter distribution pattern indicated the presence of large and small yolked eggs in two groups. Large mature eggs ranging from 0.45 to 0.80 mm in diameter were shed during spawning. Small eggs measurin 0.20–0.45 mm took 7–10 weeks to reach mature size, then were shed at the next spawning. The number of eggs shed per sawning cycle and total fecundity raned from 256 to 976 and from 383 to 1829, respectively. Hatckng rate varied from 5.3 to 97.1 %, with a mean value of 68.3 %. A majority (55 %) of the females completed spawning within 1 day. This investiation indicated thatP. cumingiicould be successfully reared and bred in captivity; the results would be useful in the development of breeding programmes for this sp

ISSN:0175-8659    

DOI:10.1111/j.1439-0426.1994.tb00161.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY