bluuebunny/crossref_metadata_2025_split huggingface dataset:
The microscopic anatomy of the oesophagus, stomach and intestine of the channel catfish, Ictalurus punctatus
Authors: Sis R. F. , Ives P. J. , Jones D. M. , Lewis D. H. , Haensly W. E. 
Published: January 2006

An anatomical study of the digestive tract of the channel catfish revealed that the oesophageal mucosa was longitudinally folded and that secondary folds were occasionally located on the primary longitudinal folds. The infoldings were more numerous near the stomach. The stratified squamous epithelium covering the folds was made up of a basal layer, large mucous cells and simple squamous cells on the surface. The epithelium on the side of the folds consisted primarily of mucous secreting cells. Taste buds were observed between mucous cells on the apical portion of the oesophageal folds and were more prevalent in the cranial part of the oesophagus. The remaining layers of the oesophagus were: a lamina propria‐submucosa, tunica muscularis and adventitia or serosa.The J‐shaped stomach had two regions: a large sac‐shaped region containing gastric glands and a smaller, nonglandular pyloric region. The large rugae of the stomach became gradually smaller near the pylorus. There was a well developed pyloric sphincter. The mucosa included a simple columnar epithelium, a lamina propria and adventitia or serosa.The intestine could be differentiated into a thick ascending segment, a descending segment, a thin convoluted segment and a thicker terminal segment, the rectum. Many mucosal folds containing branched villi characterized the ascending segment of the intestine. The descending and convoluted segments contained fewer folds with shorter and less‐branching villi and were smaller in diameter and thinner walled. Descending and convoluted segments were also mildly convoluted and accounted for 80% of the total length of the intestine. An intestinal valve with a sphincter marked the beginning of the rectum. There was an approximately four‐fold increase in the thickness of the tunica muscularis of the terminal segment of the intestine.
New observations on the rodlet cell (Rhabdospora thelohani) in the white sucker Catostomus commersoni (Lacépède): LM and EM studies
Authors: Barber D. L. , Westermann J. E. Mills , Jensen D. N. 
Published: January 2006

Light and electron microscopic studies of the morphological features of immature and mature rodlet cells in Catostomus commersoni are presented emphasizing the cells' association with epithelial tissues. The peripheral fibrillar layer is lacking from the apex and from the base of the cell. A cytoplasmic extension from the base may be a feeding mechanism whereby the rodlet cell obtains nutrient at the expense of adjacent cells leaving intercellular spaces often containing myelin figures. RNAase digestion studies demonstrate the presence of RNA in the electron dense rodlet core.The structure and histochemistry of the rodlets which do not appear to disintegrate upon expulsion from the cell are compared to the cytoplasmic inclusions of both normal fish cells and protozoan parasites. The possible association of the rodlet cell with various pathological conditions is briefly reviewed and the authors conclude that it is premature to disregard the possibility that this cell could be a parasite or infective agent.
Light and electron microscopic studies on the absorptive cells of the intestine, caeca and rectum of the adult rainbow trout, Salmo gairdneri, Rich
Authors: Ezeasor D. N. , Stokoe W. M. 
Published: January 2006

The absorptive cells lining the mucosa of the intestine, caeca and rectum of farm‐reared adult rainbow trout (Salmo gairdneri Rich.) were studied by light and electron microscopy. Most of the intestinal absorptive cells showed morphological characteristics of lipid absorption. The cytoplasm of a few cells was closely packed with mitochondria. The caecal absorptive cells resembled those of the intestine but contained more apical dense bodies and more complex lamellar structures which, in conjunction with the intercellular spaces, appeared to play more active roles in lipid absorption. The rectal lumen was divided into peripheral and central parts by the complex mucosal folds. The surface of the peripheral part was mostly lined by vacuolated cells except for small patches of non–vacuolated (generative) cells between the bases of the folds. The central lumen was lined mainly by a second type of non‐vacuolated cell. The vacuolated cells showed structural indications of a function of absorption of protein macromolecules.There is morphological evidence to suggest that the pattern of absorption of lipids and proteins in the adult rainbow trout is similar to that demonstrated in stomachless teleosts and that both intraluminal and intracellular digestion of proteins co‐exist in this teleost.
Thyroid function, pituitary structure and serum lipids in Great Lakes coho salmon, Oncorhynchus kisutch Walbaum, ‘jacks’ compared with sexually immature spring salmon
Authors: Leatherland J. F. , Sonstegard R. A. 
Published: January 2006

Whereas spring salmon, Oncorhynchus kisutch, from Lake Ontario had no overt thyroid goiters, comparable Lake Erie spring salmon had a 44% goitre incidence. Goitre incidence in sexually precocious ‘jacks’ from Lakes Ontario and Michigan was 43–45% and 100% in ‘jacks’ from Lake Erie.All fish displayed thyroid hyperplasia. The degree of hyperplasia (as indicated by thyroid follicle colloid content, thyroid follicle size and shape and thyroid follicle epithelial cell size) in Lake Ontario fish tended to be greater in the ‘jacks’ than in the spring fish; the reverse was true in Lake Erie fish. Serum total L‐thyroxine (T4) concentrations in Lake Ontario spring fish were higher than in any other group. There were no differences in serum T, levels between the groups of ‘jacks’, nor were serum T, levels in ‘jacks’ and spring salmon from Lake Ontario significantly different. Serum total triiodo‐thyronine (T) concentrations in Lake Ontario spring salmon were significantly higher than in all other groups and that in Lake Erie spring salmon greater than in all groups of ‘jacks’. Serum T, levels in Lake Ontario ‘jacks’ were higher than in Lake Erie ‘jacks’. Serum free fatty acid (FFA) and cholesterol levels showed significant interlake differences with lower levels present in Lake Erie salmon. Lake Erie ‘jacks’ appeared to have fewer and less well vacuolated pituitary gonadotropic basophils than ‘jacks’ from Lakes Michigan and Ontario. Putative thyrotrop cells appeared to be more numerous and more active in the Lake Erie spring salmon compared with Lake Ontario spring salmon. Prolactin, corticotrop and melanotrop cells appeared less active in spring salmon than in the ‘jacks’.
The histogenesis of the lymphoid organs in the carp Cyprinus carpio L. and the ontogenetic development of allograft reactivity
Authors: Botham Jane W. , Manning Margaret J. 
Published: January 2006

A functional T cell population matures rapidly in the carp, Cyprinus carpio L. At 22 ± 1° C, the thymus first appears at two days post‐hatch and becomes actively lymphopoietic by day 5. The kidney, which contains haemopoietic tissue at day 2, shows differentiating lymphoid cells by day 6–8. The spleen first appears at day 5 but develops more slowly than the kidney.Lymphocytes are capable of effecting allograft rejection as early as day 16 post‐hatch but the number of cells invading a skin allograft is low if the graft is applied in the first month of life. Thereafter the numbers increase rapidly, possibly correlated with the large increase in lymphocytes in the pronephric and mesonephric kidneys at this time.
Effect of a commercial trout diet on liver ultrastructure of fed and fasted yearling coho salmon, Oncorhynchus kisutch Walbaum
Authors: Leatherland J. F. 
Published: January 2006

Yearling coho salmon were fed either a commercial trout (TC) diet or a diet consisting of homogenized adult Pacific Ocean coho salmon (PS), supplemented with vitamins and minerals. The hepatosomatic index of the TC‐fed fish killed 12 h after the last feed or after 4 or 8 weeks of fasting were significantly larger (P 0.05) than comparable PS‐fed groups.‘Light’ and‘dark’ hepatocyte cell types were evident in all groups although the dark cells were less numerous in the fasted fish. Hepatocytes of fasted fish contained markedly more endoplasmic reticulum than fed fish. Hepatocytic glycogen content of the TC‐fed fish was higher than in PS‐fed fish. Whereas in the TC‐fed group hepatic glycogen was still evident in fish fasted for 8 weeks, the hepatocytes of the fasted PS‐fed group contained little or no glycogen. The suitability of commercial fish diets for salmonids is discussed.
Infestation of the jack mackerel, Trachurus declivis (Jenyns), with the cymothoid isopod, Ceratothoa imbricatus (Fabricus), in south eastern Australian waters
Authors: Maxwell J. Garrey H. 
Published: January 2006

The tongue biter, Ceratothoa imbricatus, a cymothoid isopod, commonly found on a number of Australian inshore temperate fish species, was recorded in the pelagic jack mackerel, Trachurus declivis, in 26 of 43 trawls. The infestation rate was low (1·76%) in the 26 trawls where the association was noted. It is suggested that infestation occurs at an early age and that subsequent growth by the isopod is mediated by the host. Estimates of the growth parameters indicate that the isopods are long lived, and can remain for at least nine years on the host fish. Protandrous hermaphroditism, common in the Cymothoidae, is found in C. imbricatus with females attaining a large size in the bucco‐pharyngeal cavity while the male, with suppressed growth, is restricted to the branchial arches.Although cymothoid isopods are commonly described as parasites, observable damage on the jack mackerel was restricted to the tissues at the points of attachment of the isopods. The effect of the isopod on the jack mackerel may not be as debilitating as might be expected and it is argued that the relationship may best be described as commensalism.
Reproductive biology of Gambusia affinis holbrooki Baird and Girard, Xiphophorus helleri (Gunther) and X. maculatus (Heckel) (Pisces; Poeciliidae) in Queensland, Australia
Authors: Milton D. A. , Arthington A. H. 
Published: January 2006

The reproductive biology of three introduced Poeciliidae, Gambusia affinis holbrooki Baird and Girard, Xiphophorus helleri (Günther) and X. maculatus (Heckel) was studied over a 14‐month period in Brisbane, Queensland. Photoperiod and water temperature determined the length of the breeding season in G. affinis, which produced up to nine broods between August and March, with the peak of reproductive activity in October. Fecundity was linearly related to body weight in G. affinis (mean fecundity = 22.78 ± 1.02, range = 3–108 offspring per brood). Xiphophorus helleri bred from August to May, producing eight to nine broods, with peak reproductive activity from October to December. Fecundity was curvilinearly related to body weight (mean fecundity = 60.15 ± 3.8, range = 7–183 offspring per brood. Xiphophorus maculatus bred between September and March, producing five to six broods during the study period. Fecundity was linearly related to standard length (s.l.) (mean fecundity = 27.27 ± 2.4, range = 3–92 offspring per brood). Although the reproductive strategy of the three species differs, all have the capacity to build up large populations in south‐eastern Queensland. Their present distributions and relative abundance are discussed.
The critical swimming speed of the sand smelt (Atherina presbyter Cuvier) in relation to capture at a power station cooling water intake
Authors: Turnpenny A. W. H. , Bamber R. N. 
Published: January 2006

Critical swimming speeds (CSS) of sand smelt, Atherina presbyter, were measured in a laboratory flume. Individuals of all age classes (0+ to III +) found in the vicinity of Fawley power station, Hampshire, were tested at temperatures covering the seasonal range. The median CSS was 2.7 body lengths per second (bl s−1) at 5.8 °C, rising to 5.7 bl s−1 at 18.5°C.A two‐variable (water temperature and body length) regression model was fitted to the data, and this was used to assess escape potential of fish coming into contact with the power station cooling water intake currents and the extent of possible bias in fish length data collected from this source. It is concluded that the sand smelt remains vulnerable to entrainment at the power station over its whole length range and over the full range of seasonal temperatures and that size‐dependent swimming performance will not lead to significant bias in sample length distributions.
Uptake and loss of nitrite from the blood of rainbow trout, Salmo gairdneri Richardson, and Atlantic salmon, Salmo salar L. in fresh water and in dilute sea water
Authors: Eddy F. B. , Kunzlik P. A. , Bath R. N. 
Published: January 2006

The acute toxicity of nitrite (NO−2) to salmonids is strongly ameliorated by chloride (Cl−) ions rendering it almost harmless in most fresh waters apart from those with low Cl− content. In Cl− poor fresh water external NO−2 is concentrated in the blood plasma until it is at approximately the same molar concentration as haemoglobin (about 8 mmol) and at this point most of the haemoglobin has been oxidized to methaemoglobin this being a contributory cause of death.Two theories are advanced to account for NO−2 concentration in the blood. The first supposes that gills are impermeable to NO−2 but allow its conjugate acid nitrous acid (HNO2) to diffuse into the blood where it dissociates according to the blood pH value. Thus NO−2 will accumulate in the blood plasma if it has a higher pH value than the water. The second supposes that the Cl− uptake mechanism in the freshwater gill has an affinity for NO−2 and accounts for the fact that NO−2 entry to the blood is suppressed when external Cl− is present in significant amounts.The results also suggest that NO−2 and Cl− behave similarly as diffusing ions. Thus NO−2 diffusion into the blood of seawater fish and from the blood of NO−2 loaded freshwater fish occurs at approximately the same rate as the corresponding Cl− fluxes. Nitrite loss from seawater fish is thought to be mainly by diffusion although there is some evidence for the active Cl− extrusion mechanism having a weak affinity for nitrite.
The food and feeding ecology of Gerreidae, Bleeker 1859, in the estuaries of Natal
Authors: Cyrus D. P. , Blaber S. J. M. 
Published: January 2006

The food and feeding ecology of five species of Genes in the estuaries of Natal, were investigated from 1978 to 1980. The Kosi system, consisting of an estuary and three main lakes was selected as the main study area due to an abundance of Genes. Four other estuarine systems were sampled.At Kosi polychaetes were important at the estuary, siphon tips (distal ±5 mm) of the bivalve Hiatula lunulata were most commonly taken in Lakes Makhawulani and Mpungwini, while chironomid larvae were important in Lake Nhlange. Ivlev's electivity test showed that Genes positively selected bivalve siphon tips when searching for food. The food taken by Genes from other estuaries was similar to that at Kosi, although the proportions of the different prey varied. At Kosi between three and five species occurred sympatri‐cally. Resource segregation was through differences in diet and feeding periodicity and a superabundance of food (H. lunulata siphon tips) during summer and autumn. During winter and spring when food may be limiting, most Genes leave shelf areas of the Kosi system, only G. acinaces remains in large numbers. Little is known of the diet of other fish which feed on benthic invertebrates in Kosi but there is probably little direct competition with Gerreidae, although Acanthopagrus berda and Pomadasys commersonni have been recorded feeding on the siphons of the bivalve Solen corneus, the former in Durban Bay and the latter at Kosi. In areas where the bivalve H. lunulata occurs it is suggested that Gerreidae have developed optimal foraging techniques which enhance resource partitioning.
The effects of a settled industrial–domestic sewage works effluent from percolating filters on the survival and growth of various stages of rainbow trout, Salmo gairdneri (Richardson)
Authors: Fraser J. A. L. , Clark E. R. 
Published: January 2006

Comparisons were made of the mortality, growth and condition factor over a 50‐day period of eleutheroembryos, alevins, 2‐month fry, 4‐month fry and 1 + rainbow trout, Salmo gairdneri, in water of three qualities–Birmingham tap‐water, 50% and 100% settled effluent from percolating filters (Minworth Effluent Treatment Works) when dissolved oxygen levels were maintained near 100% ASV.There was no significant mortality among life stages in control tap‐water but the LT50 values of life stages in both 50% effluent and 100% effluent revealed significant differences. Inter‐treatment comparisons showed similar mortalities of eleutheroembryos, of 2‐month fry and of 1 + fish in the three treatments but LT50 values of 4‐month fry showed significant differences. Growth rates of 2‐month and 4‐month fry were suppressed in both effluents after 7 days and there was a significant deterioration in the K factor of these life stages after 14 days. Predicted toxicities (the sum of the proportions of the 48‐h LC50 of the individual poisons to rainbow trout) were compared with the observed toxicity in 50% and 100% effluent. The relevance of in vivo testing in comparison to predictive techniques is compared.
Chitinase activity in the digestive tract of the cod, Gadus morhua (L.)
Authors: Danulat E. , Kausch H. 
Published: January 2006

The study was made to determine if enzymatic degradation of chitin occurs in the digestive tract of the cod, Gadus morhua. The method employed corresponds to the end product measurement of Jeuniaux (1966), using ‘native’ chitin as the substrate. The following results were obtained.

Chitinolytic enzyme of high activity is present in enzyme solutions from the stomach contents, gastric mucosa and intestinal contents.
Lower chitinase activities are found in samples of the intestinal mucosa and the pyloric caeca.
The optimum pH ranges for the action of the enzymes in the stomach and the intestine differ: 4.5–5.1 and 5.1–6.5, respectively.
The role of chitin‐decomposing bacteria is discussed, based on bacterial numbers and pH conditions in the digestive tract. The existence of two different enzyme systems is indicated.
Population biology of the myctophid fish Gymnoscopelus nicholsi (Gillbert, 1911) from the western South Atlantic
Authors: Linkowski T. B. 
Published: January 2006

Thirty‐three collections of Gymnoscopelus nicholsi were made between 1976 and 1981 in the South Atlantic using both krill and bottom trawls. In the Antarctic waters the main part of the stock consisted of adult fish 3–7 years old, characterized by a benthopelagic mode of life. Fish of year‐class I were observed only in the vicinity of South Georgia, South Sandwich Islands and the Scotia Sea; year‐class II individuals were absent from Antarctic samples. In the notal zone of the western South Atlantic, fish aged 1–5 years were found. The existence of only one population in the region is a possible explanation of these findings: this population is divided into a pelagic stock of juveniles and sub‐adults which occur in the offshore waters of the western South Atlantic and benthopelagic stocks of adults distributed over the slope regions off Argentina, South Georgia and Antarctic archipelagos.The computed values of K (von Bertalanffy growth) were 0.48, 0.41 and estimated total annual instantaneous mortality rates (Z) were 0.45, 0.67, and 0.70 for South Georgia, South Shetlands and notal zone of western South Atlantic stocks, respectively.
Survey methodology for fish population assessment within Anglian water
Authors: Coles T. F. , Wortley J. S. , Noble P. 
Published: January 2006

Basic data required for the maintenance, improvement and development of inland fisheries within the Anglian Water Authority area are derived from surveys carried out since 1977. All open river systems are sampled on a 3‐year cycle and basic data are obtained on species composition, density and biomass as well as year‐class structure and growth rates of dominant species.The netting and electrofishing gear and techniques used to obtain quantitative and semi‐quantitative samples from rivers, drainage channels and the Norfolk Broads are described and their advantages and disadvantages discussed. The mark and recapture and multiple removal techniques employed with these methods are described and an assessment given of sampling efficiency in different situations.
Estimation of food consumption from field observations of fish feeding cycles
Authors: Sainsbury K. J. 
Published: January 2006

The available methods of estimating food consumption by fish require that experiments be performed on confined animals and that experimental results may be validly applied to free fish. A method is described by which food consumption in periodically feeding fish may be estimated without performing laboratory experiments. A relatively simple input–output model of stomach contents is fitted to the observed time trajectory of stomach fullness, and food consumption is calculated from the estimated model parameters. Feeding is considered to be restricted to a distinct feeding period, and the rate of feeding during that period can be either constant or linearly decreased with the quantity of food already present in the stomach.The method is applied to three examples. The model appears robust, and generally provides very similar food consumption estimates to those obtained from methods requiring an independent estimate of gastric evacuation rate. However, the described method is sensitive to violation of the assumption that feeding occurs only during a discrete feeding period.
Cannibalism in pike fry, Esox lucius L.: some experiments with fry densities
Authors: Giles N. , Wright R. M. , Nord M. E. 
Published: January 2006

Pike fry were kept in 0.054‐m3 tanks at densities of 50, 100 and 150 (277, 555, 833 fry m−2) for seven weeks during which the development of social and feeding behaviour was observed. Zooplankton, macro‐invertebrates and perch fry were provided sequentially as food; the pike fry were allowed to feed ad libitum.Zooplanktivorous fry stopped growing at 22 mm whilst, in the presence of abundant suitable alternative prey, 1–4% turned cannibalistic at 5 weeks of age; cannibals subsequently grew rapidly (mean 1.88 mm day−1). Cannibalism ensued in all tanks when the ratio of predator size: prey size was c.2:1.Fry tended to space‐out evenly in the tanks with no overt aggression or territoriality. Behaviour was typified by remaining still for long periods, particularly subsequent to the onset of cannibalism. Cannibals were attracted by fry movements which often initiated attacks.Daily per capita mortality rates showed no crowding effects before cannibalism but significant density‐dependent mortality due to cannibals. Consumption rates of cannibals varied between 0.63 and 6.0 fry per cannibal per day. Cannibals accounted for 54–96% of daily mortality in the experimental tanks. These results are discussed in relation to proposed mechanisms of pike population density regulation.