Studies of vertebrate kidney. VI. Histochemical localization of phospholipids in kidneys of fishes from different habitats.

Six fish species living in different habitats such as fresh water, estuarine, and marine were studied for the distribution of phospholipids in various regions of the kidney. Well known histochemical methods, including those for choline-containing phospholipids were employed. The distribution pattern of phospholipids in different parts of the kidney such as the brush border, basal border and cytoplasmic granules of the proximal tubule cells, the cytoplasmic granules of the distal tubule cells, glomeruli and interstitial cells is given. Choline-containing phospholipids are present in the brush border of the proximal tubules of all the species studied and in the basal border of some. In the discussion an attempt at correlation of this histochemical pattern with the excretory functions and osmoregulation in these fishes is given.     

Bone lipids of marine fishes.

Assessment of candidates for investigation of bone lipid metabolism yielded the following findings. (1) A tropical marine butterflyfish, Chaetodon ornatissimus, had oil-filled bones (66-80% lipid, percent dry weight) hence may be a suitable condidate. (2) The tropical marine fishes Exallias brevis, Pomacentrus jenkensi, and Chromus agilis, and a Canadian fish Sebastes ruberrimus, had intermediate quantities of oil in their bones (12-49% lipid). (3) In all the foregoing species the major bone lipid was triglyceride, usually more abundant in skull than spine. Sterol and phospholipid were also present. (4) The major fatty acids of the triglycerides (and phospholipids) were 16:0, 18:0, 18:1, and C20, C22 acids. Those acids were dominated by 20:4, 20:5, 22:5, and 22:6. (5) There was more total unsaturation in the bone lipids of S. ruberrimus (from 10 degrees C water; 67-72% unsaturation) compared to the tropical fish (from 25 degrees C water; 32-67% unsaturation) with the exception of E. brevis. (6) One of the tropical species (Arothron meleagris) and a Canadian Chimaeran (Hydrolagus colliei) contained only 1-3% lipid in their bones.     

牛山湖两种不同生境小型鱼类的种类组成、多样性和密度

研究了2003年春季浅水草型湖泊牛山湖小型鱼类空间分布（种类组成、多样性和密度等）与生境异质性之间的关系.根据水生植被状况、离岸距离和水深,选择了两种差异较大且有代表性的生境类型,即近岸沉水植物茂密的生境A和远岸沉水植物稀疏的生境B.使用围网（180 m²）在这两种生境中进行小型鱼类的采样,采用多次标志回捕法和Zippin去除法估算了围网内小型鱼类的密度.结果表明,两种不同生境中小型鱼类的种类组成、多样性度量值和密度估算值均存在一定程度的差异：1）生境A中的渔获物由5科14种小型鱼类组成,优势种类为生活在中、下水层的高体鳑鲏、彩副鱊和麦穗鱼;生境B中的渔获物由3科9种小型鱼类组成,优势种类为生活在湖底的子陵吻鰕虎鱼和小黄黝鱼.2）生境A和生境B小型鱼类群落间的Bray-Curtis指数为0.222,结构相似性较低;但二者的物种等级丰度分布则无显著差异,均属于对数级数分布.3）生境A中高体鳑鲏、彩副鱊、麦穗鱼等9种小型鱼类的总密度值为8.71 ind·m^-2,生境B中子陵吻鰕虎鱼、小黄黝鱼等5种小型鱼类的总密度值只有3.54 ind·m^-2.小型鱼类在这两种不同生境中的空间分布差异可能与其逃避捕食、觅食和繁殖等生态习性的生境需求有关,因此,水生植被生境对小型鱼类资源合理开发和多样性保护具有重要意义.     

Ion transport proteins and aquaporin water channels in the kidney of amphibians from different habitats

Amphibians are known to spend part of their life on land and return to water to reproduce. However, some urodeles spend their entire life in water, while others succeed in completely avoiding water even during reproduction. Osmoregulatory mechanisms must therefore be different in the diverse environmental conditions of their respective life histories. The architecture of the kidney is similar in all amphibians; as a consequence the ion-water equilibrium must be regulated in the different environmental conditions. We investigated the immunolocalisation of Na(+)/K(+)/Cl(-) cotransport proteins, sodium pump and water-channel proteins (aquaporins) in aquatic Amphiuma means means, Rana dalmatina, a species that returns to water to reproduce, and Speleomantes genei, a completely terrestrial species. The investigation was carried out with immunohistochemical methods using antibodies to Na(+)/K(+)/Cl(-) cotransport protein NKCC1 T4, Na(+)/K(+)ATPase alpha-subunit, water-channel aquaporin 3 and the inner mitochondrial membrane (AMA). Cotransport proteins and sodium pump, involved in ion reabsorption, are widely distributed in A. means and R. dalmatina and confined to the distal segment in S. genei; conversely water channels, involved in water reabsorption, are limited to the collecting duct in A. means and R. dalmatina and distributed in the proximal and collecting ducts in S. genei.     

Influence of lighting environment on social preferences in sticklebacks from two different photic habitats. II. Shoaling and mate preferences of lab-bred fishes

Different environmental conditions may lead to diverse morphological, behavioral, and physiological adaptations of different populations of the same species. Lighting conditions, for example, vary vastly especially between aquatic habitats, and have been shown to elicit adaptations. The availability of short-wave ultraviolet (UV) light is especially fluctuating, as UV wavelengths are attenuated strongly depending on water properties. The island of North Uist, Scotland, comprises 2 differential habitat types, tea-stained and clear-water lakes, varying considerably in UV transmission. In previous studies, wild-caught 3-spined stickleback Gasterosteus aculeatus populations (3 populations of each habitat type) were tested with respect to their shoaling and mate preferences for fish viewed under UV-present and UV-absent conditions. The results revealed a habitat-dependent preference of UV cues during shoal choice (tea-stained populations: preference for UV-absent condition in tea-stained water; clear-water populations: no preference in clear-water) but an overall preference for UV-present conditions during mate choice. To assess genetic influences on these behavioral patterns, similar experiments were conducted with lab-bred F1-generations of the same stickleback populations that were raised in a common environment (i.e. standardized clear-water conditions). Offspring of sticklebacks from tea-stained lakes tended to prefer shoals viewed under UV-absent conditions (only in tea-stained water), while sticklebacks from clear-water lakes showed a significant preference for the shoal viewed under UV-present conditions in clear-water but not in tea-stained water. Mate-preference experiments demonstrated that females from the tea-stained lakes significantly preferred and females from the clear-water lakes preferred by trend the male viewed under UV-present conditions in the clear-water treatment. The results for both shoaling- and mate-preference tests were largely similar for wild-caught and lab-bred sticklebacks, thus hinting at a genetic basis for the preference patterns.     

Studies on the development of endocrine glands in fishes. V. Development of the thyroid gland in two species of teleosts.

In Channa punctatus the thyroid anlage is seen 40 h after hatching and is recognized as cells aggregating in the form of follicles with no colloid. During subsequent stages of development the thyroid follicles increase in number and in 5 days old larva an active division of cells and many follicles in the form of epithelial cords are seen. In 2 months old juvenile fish several thyroid follicles and lymphatic vessels are seen enclosed by connective tissue capsule. In Clarias batrachus the thyroid anlage is seen as a group of cells around tiny colloid droplets and is situated just below the bifuration of the 1st branchial artery. This stage is seen in 60 h old larva and is developed into thyroid follicles which is a long chain along the jugular vein and ventral aorta during latter stages of development. It is concluded that during early larval period of these fishes, the thyroid cells begin to trap iodine from the blood and synthesize it in the form of thyroid hormone which is stored as colloid and is also liberated in blood stream simultaneously. The compact nature of the thyroid gland in C. punctatus is because of development of connective sheath around follicles during early stages.     

Diets and trophic guilds of small fishes from coastal marine habitats in western Taiwan

The diets and trophic guilds of small fishes were examined along marine sandy beaches and in estuaries at depths <1·5 m in western Taiwan, Republic of China. Copepods were the most frequently identified item in fish guts, indicating they are key prey for the fish assemblages studied. Piscivore, crustacivore, detritivore, omnivore, zooplanktivore and terrestrial invertivore trophic guilds were identified. The zooplanktivore guild contained the most fish species. Maximum prey size consumption was positively correlated with standard length (L_S) in seven species and at the assemblage level and negatively correlated with L_S in a single detritivorous species. The diet data and trophic guild scheme produced by this study contribute to an understanding of coastal marine food webs and can inform ecosystem‐based fisheries management.     

Convergent evolution of weakly electric fishes from floodplain habitats in Africa and South America

An assemblage of seven gymnotiform fishes in Venezuela was compared with an assemblage of six mormyriform fishes in Zambia to test the assumption of convergent evolution in the two groups of very distantly related, weakly electric, noctournal fishes. Both assemblages occur in strongly seasonal floodplain habitats, but the upper Zambezi floodplain in Zambia covers a much larger area. The two assemblages had broad diet overlap but relatively narrow overlap of morphological attributes associated with feeding. The gymnotiform assemblage had greater morphological variation, but mormyriforms had more dietary variation. There was ample evidence of evolutionary convergence based on both morphology and diet, and this was despite the fact that species pairwise morphological similarity and dietary similarity were uncorrelated in this dataset. For the most part, the two groups have diversified in a convergent fashion within the confines of their broader niche as nocturnal invertebrate feeders. Both assemblages contain midwater planktivores, microphagous vegetation-dwellers, macrophagous benthic foragers, and long-snouted benthic probers. The gymnotiform assemblage has one piscivore, a niche not represented in the upper Zambezi mormyriform assemblage, but present in the form of Mormyrops deliciousus in the lower Zambezi and many other regions of Africa.     

The visual pigment sensitivity hypothesis: further evidence from fishes of varying habitats

Summary Visual pigments were extracted from the retinas of 8 species of marine teleosts and 4 species of elasmobranchs and a comparison was made of the pigment properties from these fishes, some inhabiting surface waters, others from the mesopelagic zone, and a few migrating vertically between these two environments. An association was found between the spectral position of the absorbance curve and the habitat depth or habitat behavior, with the blue-shifted chrysopsins being the pigments of the twilight zone fishes and the rhodopsins with fishes living near the surface. The retina of the swell shark (Cephaloscyllium ventriosum) yielded extracts with two photopigments; one, a rhodopsin at 498 nm; the second, a chrysopsin at 478 nm. This fish has been reported to practice seasonal vertical migrations between the surface and the mesopelagic waters. In addition to the spectral absorbance, several properties of these visual pigments were examined, including the meta-III product of photic bleaching, regeneration with added 11-cis and 9-cis retinals, and the chromophoric photosensitivity. The chrysopsin properties were found to be fundamentally similar to those of typical vertebrate rhodopsins. Correlating the spectral data with the habitat and habitat behavior of our fishes gives us confidence in the idea that the scotopic pigments have evolved as adaptations to those aspects of their color environment that are critical to the survival of the species.     

Studies on groundnut proteins. V. Physico-chemical properties of arachin prepared by different methods.

ORD,¹ CD, and fluorescence spectra of arachin prepared by Tombs' (Biochem. J., 96, 119; 1965), Dawson's (Anal. Biochem., 41, 305; 1971) or Shetty and Rao's (Anal. Biochem., 62, 108; 1974) procedure were measured; the effect of denaturants such as SDS, GuHCl, and acid was also determined. ORD and CD spectra showed differences, whereas fluorescence spectra did not show any difference. The effect of the denaturants was the same on the three arachins. At low concentrations of GuHCl (<2 m), the denaturant was bound by the protein molecule without causing any conformational change. The binding affinity varied among the arachins.     

Site preference of myxozoans in the kidneys of Hungarian fishes

Myxozoans are common parasites of fish kidneys, with most having specific sites of development. Five specific sites of development include (1) the lumen of renal tubules, (2) the renal corpuscles followed by location in renal tubules, (3) intracellular location within the tubular epithelium followed by a stage in the lumen of the ducts, (4) haematopoietic tissue with dispersed trophozoites, and (5) haematopoietic tissue with large, localized plasmodia. A coelozoic development preceded by presporogonic multiplication characterises most Sphaerospora spp. Early plasmodial stages of Myxidium and Chloromyxum spp. are frequently found in the renal glomerules, while spores develop in the urinary channels in plasmodia released from the renal corpuscles. In Hoferellus and Myxobilatus spp., spores are formed in small plasmodia inside the lumen of the urinary ducts after several internal cleavages in the epithelium of renal tubules. The presence of dispersed trophozoites among haematopoietic tissue cells of the renal interstitium characterises the development of Sphaerospora tincae and Tetracapsuloides bryosalmonae, the causative agent of proliferative kidney disease (PKD). Spores of S. tincae are formed at the place of plasmodial development, while spore formation of PKD is in the renal tubules. A large mass of spores, often surrounded by a connective tissue capsule, can appear in the renal interstitium during infections by several Myxobolus spp.; furthermore, a large number of these spores formed in plasmodia in distant tissues can also accumulate in melano-macrophage centres.