摘要:

The distribution of non‐specific carboxylic esterases (Ec 3.1.1) in the digestive tract of perch,Perca fluviatilisL., was investigated histochemically using 1‐naphthyl acetate as the substrate. Strong enzymatic activity was present in the gastric glands and surface cells of the stomach, intestinal mucosa of the pyloric caeca, upper and middle intestine, pancreas (exocrine cells) and liver. The enzymatic activity in the lower intestine and rectum was weak. The activity was not demonstrated in the oesophagus or pyloric sphincter. In the intestine, the activity was localized in the columnar cells especially in the supranuclear cytoplasm. The enzymatic activity demonstrated in the digestive tract of perch using 1 ‐naphthyl acetate represents combined esterolytic and lipoproteolytic act

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1983.tb04719.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Experiments were conducted to determine the adaptability of mosquito fish to various salt concentrations. Mosquito fish,Gambusia affinis, (total length (T.L.) 27–37 mm) were subjected to abrupt and gradual changes from fresh water to various salinities (S). Low mortality (10%) occurred when the fish were transferred from fresh water (S = 0·5‰) to 50% sea water (S = 19·5‰ Through gradual adaptation 65·0% of the fish were able to tolerate 100% sea water for 7 days. After a 7 ‐day stay in sea water, fish were readapted to fresh water during a 3‐h period. The results indicate that they were well able to tolerate the abrupt change. Through a gradual adaptation fish were also able to tolerate salinities ranging from 39·0‰ (100% sea

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1983.tb04720.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Five kinds of artificial sea water with similar salinity, pH and osmolarity were prepared with different concentrations of calcium and magnesium ions. They were complete sea water, calcium‐free sea water, half calcium‐free sea water, magnesium‐free sea water and half magnesium‐free sea water. The fertilized eggs from induced spawnings of grey mulletMugil cephalus, were transferred to these sea waters at two development stages, i.e. before the formation of 2‐blastomere stage and at the gastrula stage. Survivals of fertilized egg in different sea waters were checked after several hours incubation, the percentage survival was used as an index of the importance of calcium and magnesium to the embryonic development. The results showed that calcium is indispensable to the embryonic development of mullet egg. Magnesium, however, is not the necessary element in the incubati

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1983.tb04721.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The population of solenette,Buglossidium luteum, in the Solway Firth was studied from November 1977 until January 1979. The fish live in mobile, highly aggregated groupings, on sandy bottoms, in the outer Firth. A general offshore movement occurs in winter with a limited incursion of juveniles into the inner Solway in summer. Most growth occurs in the first few years of life and a length of 130 mm is attained. Longevity is 10 years. Females grow larger than males, but both sexes mature in their third year. Spawning starts in March/April, is most active in May/June and ends in August. Food intake is markedly reduced in winter. Small Crustacea, bivalve molluscs and polychaete worms form year‐round components of a varied diet. Juvenile forms, especially shrimp and fish are readily taken when availabl

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1983.tb04722.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

A nematode parasitePhilometra translucidaWalton (1927) was found in the ovaries ofPseudotolithus senegalensisCuvier&Valenciennes (1833),P. typusBleaker (1863) andP. elongatusBowditch (1863), the most abundant and commercial sciaenid species in the Nigerian inshore waters. The parasite measured 56·0–59·0 cm in length. It occupied one‐third to two‐thirds of the mesenteries of the matured ovaries in severe cases of infection. The incidence of infestation, highest during peak spawning, was 10·0% inP. senegalensis, 12·0% inP. typusand 20·0% inP. elongatus. Another nematode parasiteConiracaecumsp. Ralliet&Henry (1912) was observed in the ovaries of two specimens

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1983.tb04723.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Hybrid grass carp resulting from the cross of a female grass carp,Ctenopharyngodon idella(Val.), and a male bighead carp,Hypophthalmichthys(Aristichthys)nobilisRich., 12–18 months old (c. 300 mm T.L.) were studied in a two‐part experiment to determine feeding preference and total daily consumption fish‐1on selected species of aquatic plants. Fish were maintained in circular pools with 6840·8 1 of water inside a temperature‐controlled greenhouse. Preference tests were conducted at three temperature ranges; 25–28° C, 17–20° C and 12–15° C. Based on the time to complete consumption or the relative quantity consumed, the most preferred plant wasLemna gibbawhen in combination with six other species.Charasp.,Najas guadalupensisandPotamogeton peciinatuswere readily consumed and considered to be of about equal preference.Ceratophyllum demersumandMyriophyllum brasiliensewere least preferred. Hybrid grass carp generally consumed as much plant material species‐1and in the same order of preference at the 12–15°C range as they did at 25–28° C. In the second part, mean daily consumption (g) fish‐1at 25·7–31·0° C for five plant species tested separately was as follows:Charasp. 369·8;Lemna gibba178·2;Najas guadalupensis172·6;Hydrilla verticillat

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1983.tb04724.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Growth of tissues (heart, spleen, liver, gonad, gut, skin, visceral fat and carcase) in immature rainbow trout relative to growth of whole fish, was examined by means of allometric analysis (y=axb; Huxley, 1932) of wet and dry weights. Relative growth rates of tissues are compared in an initial sample of fingerlings (1·00), and carcase increased more slowly than body weight (b<1·00). Above fingerling size, the reverse holds: tissues other than carcase (with exception of visceral fat) increased less rapidly than body weight (bor<1·00 can cause important changes in the proportional (%) weights of major tissues as fish continue to increase in size. In low (4–5%) rations fish (without bGH) the slope (b) value for gut is less than for fish onad libitumrations with the result that gut proportional weight is significantly less among these fish. In fish onad libitumrations at 7°C, the slope (b) value for skin is greater than for all other (12°C) groups; skin proportional weight for the 7°C group is therefore, significantly greater. The overall impression of relative growth in immature rainbow trout is of remarkable conservativeness of body proportional weights regardless of overall s

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1983.tb04725.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Factors affecting the transformation of brown trout,Salmo trutta L., and carp,Cyprinus carpio L., lymphocytes in culture for subsequent karyotyping are examined. Optimum conditions for mitosis are established in respect of medium, mitogen, atmosphere, buffering system and serum.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1983.tb04726.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

A method for obtaining dividing cells for chromosome analysis from blood cultures of the rainbow trout,Salmo gairdneri, is described. The effects of different phytohaemagglutinin and foetal calf serum concentrations, oxygenation of the cultures, and varying the initial volume of cell inoculum on the number of mitoses obtained are described and discussed.

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1983.tb04727.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Egg‐case size, shape and pigmentation are distinctive features of each female lesser‐spotted dogfish,Scyliorhinus canicula.During 9 months captivity under constant conditions (water, temperature, photoperiod, food), a laying sequence reminiscent of an annual cycle was observed in three females. While oocyte size and (with exceptions) egg‐case weight remained constant, there was a marked decrease of the‘albumen’jelly secreted by the anterior halves of nidament

ISSN:0022-1112    

DOI:10.1111/j.1095-8649.1983.tb04728.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY