摘要:

The induced spawning of gravid roach was investigated using the antioestrogens clomiphene and tamoxifen. Three dose levels ofeach were used: 0·1, l or 10 mgkg‐1, given twice with a 4‐day interval to groups of eight fish with saline controls. Running males were randomly distributed. Tamoxifen, when injected at a rate of l mg kg‐1was found to be most successful. This treatment induced ovulation in five of the six females, and profuse spawning on 3 consecutive days, 4 days after the first injection. Clomiphene induced ovulation and spawning in one of six females at 2 × 10 mg kg‐1, and two of eight females at 2 × l mg kg‐1, respectively 6 and 7 days after the first injection. The eggs produced showed normal devel‐opment. No control fish ovulated or spawned. Both drugs probably act by indirect mechanisms, blocking sex steroid feedback inhibition of gonadotropin (GtH) secretion at the pituitary, thereby inducing a plasma GtH surge. The results of this experiment suggest that tamoxifen may be an effective substitute for pituitary preparations in the induced sp

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1983.tb04748.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Plasma insulin and glucose responses to a secretin‐like factor, extracted from pike intestines, have been investigatedin vivoin European eels,Anguilla anguillaL. Intra‐arterial injection of pike secretin elicited a dose‐related, significant increase of plasma insulin after 30 min at 100 and 250 μgkg‐1body weight, but was without effect at 40μgkg‐1. Plasma glucose levels, however, remained unchanged over this dose range. These results suggest that hormonal factors of gastrointestinal origin may modify pancreatic endocrine function in t

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1983.tb04749.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

A new species of macrourid,Coryphaenoides paramarshalliis described from mid to lower slope waters (l 13–160 m) off West Africa, in the area 04°S‐21°N and 10°E‐18°W. The species is very closely related toC. marshalli. Indeed, two of the paratypes of that species are incorporated among the paratypes ofC. paramarshalli, as they are referrable to the new species. The features distinguishing the two species are discussed in conjuction with those separatingC. paramarshallifrom other relate

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1983.tb04750.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

A technique is described using separated peripheral blood lymphocytes from fish which yields cultures giving good chromosome spreads suitable for convential karyotyping and the subsequent application of banding techniques.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1983.tb04751.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Using histological and cytological criteria, it has been shown that in the ovotestisof Serranus hepatus, a synchronous hermaphrodite, the differentiation of the ovary is earlier than that of the testis. Primordial germ cells (PGC) exhibit the same ultrastructural features in the ovary and the testis. These cells migrate from the ovary to colonize the testicular anlage.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1983.tb04752.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Lampreys are important research animals. This study investigates some of the Parameters important for culturing the Suspension feeding larvae: food concentration, temperature and crowding. Large larvae (Lampetra(Entosphenus)tridentataRichardson) were used, weigh‐ing from l·5 to 3·0 g (wet). Two food types were employed: suspended yeast cells (Saccharo‐myces cerevisiae, 0–20 mg1 – (dry), or, in a few tests, a fine particulate fish food, Liquifry® (Interpet LTD, 0–13 mg l‐1). At both 14 and 4°C, yeast could sustain weight increases comparable to those in nature:>6% month‐1for up to 6 months, the duration of the study. In a single lest, a vitamin Supplement failed to improve growth on yeast. Growth‐was fastest at 14°C (+41% month‐1, max. weight increase), although also substantial at 4°C (+11% month‐1, max). Growth could not be sustained at 20°C, due perhaps to difficulty in removing products of food decay from the aquaria. Food level being constant, growth rate varied inversely with animal density. It is suggested that larval lampreys release a growth‐inhibiting substance into the sand which they inhabit. Overall, the best growth was obtained at 14° C, with<0·05g of animal (wet weight) – aquarium water and average daily yeast concentrations between 4 and 13 mg –. Liquifry was associated with lowered growth rates when present continually above 4 mg (dry weight) – (14° C), although gro

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1983.tb04753.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

In myotomes of the stickleback three main complexes of muscle fibres were present. They comprised dwarf, intermediate and white fibres, which differed in regard to histochemical, immunohistochemical and ultrastructural features. In addition, dwarf fibres were divided into two categories on the basis of myofibrillar ATPase activity and cross‐reactions with specific antisera. Among intermediate muscle fibres it was possible to observe some ‘aberrant fibres’, which were characterized by low reactivity with and P‐myosi

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1983.tb04754.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The reproductive biology of poor‐cod,Trisoptems minutusL., whiting,Merlangius merlangusL., and Norway pout,Trisoptems esmarkiiNilsson, was studied in western Scottish waters. Sex ratios, size and age at maturation and spawning seasons were determined and compared with other areas. The large juvenile stocks found in inshore areas at the western entrance of the Great Glen were derived from spawning grounds west of Mull, in poor‐Cod. In whiting and Norway pout the location of spawning grounds was inferred from the occurrence of planktonic larvae and postlarvae and the hydrography of the a

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1983.tb04755.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

A large natural fish kill which resulted in the deaths of a total of more than 3400 fish comprising eight different species occurred in a freshwater billabong (lagoon or small permanent waterbody) on the Magela Creek in the subtropical Northern Territory of Australia in January, 1980. The fish deaths were assessed to be the result of a combination of natural acid water runoff into the billabong and resultant elevated aquatic biotoxic aluminium levels. Details of water quality changes which occurred during the event and analytical data for the fish killed are provided, together with some explanation of the sequences of occurrence of the fish kill.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1983.tb04756.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The milt composition of six freshwater teleosts was studied, and the measured parameters showed clear specific differences between species. The highest spermatocrits and sperm densities were observed in perch,Perc afluviatilis, and burbot,Lota lota, and the lowest in rainbow trout,Salmo gairdneri, and whitefish,Coregonus lavaretus. Fructose concentrations in the seminal plasma were small compared to mammalian values. The glucose concentrations in the seminal plasma were five times higher than those of fructose, and higher in landlocked salmon and rainbow trout than in the other species. The citric acid concentration of all species except whitefish showed a significantly positive correlation to either spermatocrit or sperm density. The role of citric acid in the seminal plasma of fishes was also assumed to be important. The glycerol concentration in the seminal plasma was comparatively high, and highest in whitefish. This was assumed to be related to the high applicability value of glycerol as a cryoprotective agent for whitefish sperm. The high glycerol concentration was also assumed to be related to the lipolytic capacity of the testis in the studied species.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1983.tb04757.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY