摘要:

In iced dressed swordfish, inosine monophosphate, initially the predominant nucleotide (5.2 μmole/g), was dephosphorylated to inosine during 19 days storage. Hypoxanthine increased very slowly to about 1 μmole/g while quality (taste panel) showed no significant decrease to 15 days but was near borderline at 19 days. These changes occurred more slowly than in cod and related species. The sequence of nucleotide changes occurred much earlier in the red muscle. Rapid freezing and storage at −26 C for 4–5 months inhibited nucleotide enzymic activity, and quality remained unchanged. Slow freezing and storage for 1 week at −4 C significantly reduced quality to borderline or unacceptable levels, but only slightly affected the nucleotide degradation, indicating that other factors were responsible for the loss in quality. Dephosphorylation and hypoxanthine accumulation continued during further storage at −4 C. The levels of hypoxanthine reached during 19 days iced storage or 4–5 months frozen storage were not sufficiently high to impart bitter flavors, except possibly in the red muscle. A simple measure of inosine (+ hypoxanthine) may be useful as a quality test; a supplementary hypoxanthine test could be used to confirm spoilage.

ISSN:0706-652X    

DOI:10.1139/f66-172

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The gut contents of two cod were analysed for isomeric glycerides. Ten times more α,β-diglyceride than α,α′-diglyceride was found, and five to ten times more β-monoglyceride than α-monoglyceride.A fat labelled with tritiated oleic acid in position 1 and with C-14-oleic acid in position 2 ofL-glycerol was fed to two cod, and the diglycerides were then isolated from the gut content. Radioactive analyses showed them to be mixtures of the 1,2 and the 2,3 isomers.In cod, therefore, dietary fat is degraded to diglycerides and monoglycerides by a digestive lipase which preferentially attacks the α-bound fatty acid esters but is not stereospecific. This enzyme corresponds in its action to the pancreatic lipase of mammals and of skate.

ISSN:0706-652X    

DOI:10.1139/f66-173

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Electronmicrographs showed that the free border of the epithelial cells of the pyloric caeca, ileum, and rectum of the cod,Gadus morhua, is made up of microvilli. Elongated microorganisms aligned parallel to the microvilli and with one end fitting into the bases of the inter-microvillus spaces were frequently found in the rectum. Such organisms corresponded in position to peripheral interlacing filaments visible with the light microscope.

ISSN:0706-652X    

DOI:10.1139/f66-174

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

In 14 cohabiting fish species in a small freshwater lake, mouth and body structures combine with food specializations and habitat preferences to greatly restrict interspecific competition within the fauna.The species differ quantitatively in a large number of structures and, individually and in combination, these are clearly adapted for distinctive roles. The mouth is particularly plastic, varying in position, in aperture width, and in overall form, with structures as diverse as a scoop, a beak, and a tube being found. Six basic body types occur and these, combined with varying fin morphologies, result in a range of distinctive forms, including the following.Micropterus salmoides, with a compressed fusiform body and a wide mouth, is a strong-swimming, widely ranging piscivore.Notemigonus crysopterus, with a long, slender caudal peduncle, subfalcate pectoral fins, and a deeply forked caudal fin, has great maneuverability that permits it to catch individual zooplankters.Lepomis macrochirusis a "sedentary," gibbose-bodied water-hanger.Umbra limihas a stubby, cylindrical body that favours life in dense vegetation.Labidesthes sicculus, with an almost straight dorsal line to the body, a low dorsal fin, and a beak-like snout with tweezer-like teeth, is modified for surface feeding and leaping out of the water.Ictalurus nebulosushas chemotactile barbels that favour bottom feeding and paired fins that function partly as hydrofoils, keeping the body inclined downwards as the mouth sweeps the bottom.The structural specializations give their owners a decided ecological advantage in certain situations. Only a few species, however, are limited by them to restricted ways of life. In most cases, a considerable measure of feeding flexibility is retained, presumably important for survival in cold temperate lakes.

ISSN:0706-652X    

DOI:10.1139/f66-175

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Within a restricted geographical area of British Columbia, detailed examination in 1960 and 1961 of nine lakes having similar morphometric and climatic characteristics but exhibiting a wide range in dissolved nutrients (50 to 1463 ppm) suggested that, standing crops of plankton were related to oxygen deficits and perimeter-to-area ratios of the lakes. Total dissolved solid contents of the lakes were not closely correlated to standing crops of plankton, bottom fauna, or fish. Ranking by selected physical or chemical indices of productivity failed to agree with ranking based on standing crops or various biological measurements of productivity. Water level fluctuation, perimeter-to-area ratios, lake basin shape, and the size and nature of the drainage area are discussed as some of the possible factors which interact to modify the expression of the primary factors in productivity.

ISSN:0706-652X    

DOI:10.1139/f66-176

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Previously known by only one fossil bone from Oregon, the record of the sea otter is supplemented by description of 11 bones newly found in Late Pleistocene deposits at San Pedro and on Santa Rosa Island and one tooth from an Early Pleistocene deposit at San Pedro, southern California, all considered representative of the living speciesEnhydra lutris. Faunal associations suggest that the animals lived with cool-water faunas in areas of shallow to moderate depth near islands. The long-accepted hypothesis thatE.lutrisevolved from "Lutra reevei" during the Pliocene in the North Atlantic and migrated to the North Pacific is rejected on chronologic and zoogeographic grounds. The sea otter may be a North Pacific endemic autochthon.

ISSN:0706-652X    

DOI:10.1139/f66-177

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

This study describes the histopathology and the associated gross pathological alterations of experimentally induced acute inflammation in the oyster,Crassostrea gigas, after turpentine injections into two different tissues, the adductor muscle and the Leydig cell area. Under optimum conditions the oyster can successfully combat a toxic substance such as turpentine, with the adductor muscle being more capable of handling such an irritant than the Leydig cell area. Inflammation in vertebrates is compared with that in the oyster.

ISSN:0706-652X    

DOI:10.1139/f66-178

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Eight lake populations of the bluegill sunfish (Lepomis macrochirus) with widely varying growth rates exhibited a surge of growth in the spring followed by a progressively declining growth rate in late summer and autumn. The growth rate declined as age increased; in no case did the growth of an older age group exceed that of a younger age group in the same year. Increase in length was estimated from marginal growth of scales collected at various times throughout 1962 and 1963.The beginning of the growing season, assumed to correspond in time with the formation of the annulus, was estimated to average April 8 in 1962 and April 26 in 1963. The time of annulus formation was observed in one lake by collecting scales when the mark was appearing, and in the others it was estimated by extrapolation of a regression between marginal scale growth and time. The end of the growing season, or the time when 90% of annual growth had been achieved, came on September 10 in 1962 and on September 27 in 1963. The length of the growing season varied among the lakes and between years in the same lake. The range was from 98 to 189 days with an average of 152 days. In one lake the season was a month longer in 1963 than in 1962, but this difference was not evident in the others.The annual rate of growth and the length of the growing season were related. Populations with a rapid growth rate had a longer growing season than those with a slow growth rate. A long season was typified by a somewhat earlier time of annulus formation than a short one and by a considerably longer period of growth in the late summer and autumn.All populations had the same growth potential as judged by weight increment of group III fish during the first month of the season. The first month's increments were 12.6, 12.9, and 13.9 g for populations with rapid, intermediate, and slow annual growth rates respectively. The population with the shortest growing season and the lowest annual growth had the greatest increment during the first month.The strong relationship between size and the time of annulus formation suggested a possible mechanism of growth compensation. Since the smaller fish of a year class begin to grow earlier than do their larger companions, growth compensation may result from the advantage in time gained by the smaller group, assuming that the growing seasons of it and the faster growing members of the cohort end at the same time. Most of the mechanisms offered heretofore have depended upon a difference in the time of hatching between two groups of fish.Consideration is given to an explanation of the annual growth cycle in terms of temperature, photoperiod, and the possible influence of growth hormone at different times of the year.

ISSN:0706-652X    

DOI:10.1139/f66-179

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Rainbow trout serum was shown to be made up of three major protein components. These three major components did not coincide by electrophoretic mobility or by relative salt solubility with the classic albumin, α-, β-, and γ-globulin separation of the sera of higher animals. A component equivalent to γ-globulin of higher animals was found to be completely lacking in the sera of both immunized and non-immunized rainbow trout.Specific humoral antibodies in rainbow trout immune sera were found to be contained in the electrophoretically least mobile proteins. These proteins coincided most nearly to the β-globulins and possibly the least electrophoretically mobile α-globulins of higher animals. Salt solubility of the serum proteins containing the specific antibody assisted in this conclusion. The electrophoretically least mobile major serum protein components were found to contain all of the antibody activity. These proteins could be removed from immune serum by 20% sodium sulfate. The assumption was made thatAeromonas hydrophilaantibodies in immunized rainbow trout blood serum may be made up of a complex of serum proteins with a broad range of salt solubility and electrophoretic mobilities.Serum proteins of rainbow trout could also be classified as euglobulins or pseudoglobulins. The serum proteins which contained theA.hydrophilaantibodies were found to be euglobulins.

ISSN:0706-652X    

DOI:10.1139/f66-180

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

not available

ISSN:0706-652X    

DOI:10.1139/f66-181

出版商:NRC Research Press    

年代:1966

数据来源: NRC