Allozyme Variation in a Threatened Freshwater Fish, Spotted Murrel (Channa punctatus) in a South Indian River System

Samples of the spotted murrel (Channa punctatus) were collected from three rivers of Tamil Nadu and Kerala. The allozyme variation of C. punctatus was investigated by polyacrylamide gel electrophoresis. Eighteen enzymes were detected, but only 10 (EST, PGM, G3PDH, G6PDH, SOD, GPI, ODH, GDH, XDH, and CK) showed consistent phenotypic variations. Allele frequencies were estimated at the 18 polymorphic loci representing 10 enzymes. Two rare alleles, EST-4*C and G6PDH-2*C, were noted in the Tamirabarani and Kallada populations but were absent in the Siruvani population. The allele frequencies of the Tamirabarani and Kallada populations were similar, except for a few loci. Among the three populations, the maximum genetic distance (0.026) and FST (0.203) were found between the geographically distant Siruvani and Kallada populations. Overall the study showed that among the three populations, the Tamirabarani and Kallada have similar genetic structures.     

Modulatory effect of copper on nonenzymatic antioxidants in freshwater fish Channa punctatus (Bloch.)

Effect of the low level of copper exposure on nonenzymatic antioxidants was studied in a freshwater fish Channa punctatus (Bloch.). Fish were exposed to cupric chloride at the concentration of 10 ppb for 4 wk (28 d) in a static culture condition. Copper significantly (p < 0.001) increased the serum ceruloplasmin level and total iron-binding capacity. A significant (p < 0.05) increase in reduced glutathione level was recorded in all of the tissues. With regard to nonprotein thiols, copper decreased their level in the liver, but increased it in the gill. The protein-bound thiols remained unaltered except for an increase in the liver. Metallothionein (MT) induction was observed in liver only. Copper exposure had no significant effect on the ascorbic acid level and induced no lipid peroxidation over control values. It is suggested that by modulating the ceruloplasmin level, copper indirectly protects the fish, as it facilitates conversion of pro-oxidant iron to nonoxidant iron. It also induces an array of antioxidants that may be beneficial to fish in the case of oxidative stress resulting from chemical pollutants.     

Seasonal variations in the blood constituents of an air-breathing fish, Channa punctatus Bloch

A year long study based on monthly observations on the haematology of female Channa punctatus with respect to haemoglobin, haematocrit values, total erythrocyte and leucocyte numbers together with a differential enumeration of various leucocytes viz. thrombocytes small and large lymphocytes, monocytes, neutrophils, eosinophils and basophils is recorded. The study showed that the total erythrocytic number, haemoglobin and haematocrit values decrease during the breeding time i.e. July to September. The thrombocyte number significantly increased while the neutrophilic number showed a decrease. The physiological significance of these changes is discussed with reference to the available literature.     

Seasonal variation of ammonia-quotient in an Indian air-breathing freshwater teleost, Channa punctatus

The ammonia-quotient, calculated from the data on the levels of ammonia excreted and oxygen consumed from the water, is a potent tool for understanding the utilization of macromolecules as metabolic fuel. The fish, Channa punctatus, utilizes more protein in the summer and spawning months for getting its metabolic energy but in the winter and post-spawning months it also utilizes other substrates like lipid and carbohydrate for its metabolic energy.     

The effects of calcitonin on plasma calcium levels and bone metabolism in the fresh water teleost Channa punctatus

Administration of salmon calcitonin (sCT) caused significant reduction in total and ultrafiltrable plasma calcium content in the plasma of a fresh water female teleost Channa punctatus. A time-bound analysis on the effect of sCT showed a highly significant short duration reduction in total and ultrafiltrable plasma calcium content in fish kept in normal tap water and low-calcium water and a moderate hypocalcemia in fish kept in high-calcium water. Sexually immature adult fish showed a greater response than the sexually mature ones. Using tartrate-resistant acid phosphatase (TRACP) and alkaline phosphatase (ALP) activities in plasma and hydroxyproline (HYP) excretion in urine, the effect of sCT on the inhibition of bone calcium resorption were examined. In both sexually mature and immature adult fish, kept in normal tap water, sCT significantly suppressed TRACP and ALP activities in plasma and excretion of HYP in urine within 2-6 h with a maximum at 4 h after injection. Salmon CT treatment to sexually immature adult fish caused significant increase in skeletal bone calcium concentration. Taken together, all this information indicates that CT in a fresh water female teleost is an effective regulator of plasma calcium levels, and its action, at least in part, operates through inhibition of bone calcium resorption.     

Retinopetal neuronal system in the brain of an air-breathing teleost fish,Channa punctata

Summary Retinopetal neurons were visualised in the telencephalon and diencephalon of an air-breathing teleost fish, Channa punctata, following administration of cobaltous lysine to the optic nerve. The labelled perikarya (n=45–50) were always located on the side contralateral to the optic nerve that had received the neuronal tracer. The rostral-most back-filled cell bodies were located in the nucleus olfactoretinalis at the junction between the olfactory bulb and the telencephalon. In the area ventralis telencephali, two groups of telencephaloretinopetal neurons were identified near the ventral margin of the telencephalon. The rostral hypothalamus exhibited retrogradely labelled cells in three discrete areas of the lateral preoptic area, which was bordered medially by the nucleus praeopticus periventricularis and nucleus praeopticus, and laterally by the lateral forebrain bundle. In addition to a dorsal and a ventral group, a third population of neurons was located ventral to the lateral forebrain bundle adjacent to the optic tract. The dorsal group of neurons exhibited extensive collaterals; a few extended laterally towards the lateral forebrain bundle, whereas others ran into the dorsocentral area of the area dorsalis telencephali. A few processes extended via the anterior commissure into the telencephalon ipsilateral to the optic nerve that had been exposed to cobaltous lysine. However, the ventral cell group did not possess collaterals. In the diencephalon, retinopetal cells were visualised in the nucleus opticus dorsolateralis located in the pretectal area; these were the largest retinopetal perikarya of the brain. The caudal-most nucleus that possessed labelled somata was the retinothalamic nucleus; it contained the largest number of retinopetal cells. The limited number of widely distributed neurons in the forebrain, some with extensive collaterals, might participate in functional integration of different brain areas involved in feeding, which in this species is influenced largely by taste, not solely by vision.     

Haematological and haematopoietic response to acid stress in an air-breathing freshwater fish, Channa punctatus Bloch

Response of Channa punctatus to acidic water was studied by exposing fishes to pH 3.5, 4.5, 5.5 and 6.5 for 6 weeks. Growth and mortality data indicated increasing stress as the acid level in the ambient water increased. While no mortality was recorded at pH 6.5, a distinct loss of weight compared to continuous gain in body weight in control fish indicated stress. As the pH level decreased, the rate of loss in body weight increased accompanied by mortality which rose to as high as 60% within 3 weeks in fishes exposed to water at pH 3.5.
Haematological investigations confirmed the general stress indicated by growth and mortality data. Thus. RBC and related values indicated overall polycythemia. However, eosinophils, basophils. and large and small lymphocytes showed a distinct fall in number as compared to the control.
Correlated haematopoietic studies revealed that both the initial and penultimate stages in RBC and neutrophil development recorded an increase parallel to that observed in peripheral blood, but intermediate stages, probably because they were unable to keep pace with the fast turnover, showed a relative decrease.
Biochemical investigations showed an increase not only in blood glucose level but also in liver glycogen content. However, there was a significant decrease in muscle glycogen reserves.
The significance of these changes is discussed.     

Effect of ammonia-stress on the total autolytic levels of proteins in tissues of an air-breathing fish,Channa punctatus (Bloch)

G season-specific effect of a sub-lethal ambient ammonium chloride concentration on the total autolysis of protein in different tissues of the Indian air-breathing murrel,Chauna punctatos (Bloch), has been demonstrated. While its effect on the autotytie levels of protein of different tissues (except white muscle) was marginal in the winter-adapted fish, the same in the summer-adapted fish was more pronounced. In general a reduction in the autolysic levels of the tissue protein of the ammonium chloride-stressed fish was observed. In certain tissues like white muscle of an ammonium chloride-stressed fish and gill of the ammonium hydroxide-stressed fish, augmented levels of autolysis were noticed. The present findings suggest that the accumulation of amino acids in different tissues of the ammonia-stressed fish, as observed earlier, can be explained best by mechanisms other than ammonia induced increased breakdown of proteins.     

Oxygen uptake through water during early life in Channa punctatus (Bloch) (Pisces; Ophicephaliformes)

Oxygen uptake in relation to body size during the early life of the fish Channa punctatus shows a significant two-component curve: one related to the fully aquatic phase and the other to the bimodal phase of respiration. The onset of the air-breathing habit around the 18–20th day after hatching brings about a 45% drop in O₂ uptake through the gill/skin in water.     

Focusing and accommodation in tuatara (Sphenodon punctatus)

Summary Photorefraction and photokeratometry were performed on two juvenile tuatara (Sphenodon punctatus, 7 years of age, total length approx. 27 cm). Sphenodon is the only surviving genus of the Rhynchocephalia, an order of reptiles. Both existing species are endangered and are found only in New Zealand. Even though Walls (1942) has stated that the ciliary muscle is relatively weak in tuataras, we observed 8 D of accommodation. The eyes were found to focus independently and we could induce an anisometropia of 6 D. The average corneal power of the tuatara was found to be 101 D.     

Proline metabolism in response to nitrogen deficiency in French Bean plants (Phaseolus vulgaris L. cv Strike)

The objective of the present work was to determine the impact ofnitrogen deficiency on proline metabolism in French Bean plants(Phaseolus vulgaris L. cv. Strike). The nitrogen wasapplied to the nutrient solution in the form of NH₄NO₃ at1.45 mM (N1), 2.90mM (N2) and 5.80mM (N3, optimal level). Our results indicateNdeficiency is characterised by a decline in proline accumulation both in theroot and leaves, fundamentally because proline degradation is encouraged by thestimulation of the enzyme proline dehydrogenase. By contrast, under conditionsof adequate N (N3), proline levels rise due to the action of ornithine,suggesting predominance of the ornithine pathway over the glutamine pathway, inaddition to the inhibition of proline dehydrogenase activity.     

Interrelationships between carbohydrate metabolism and nitrogen assimilation in cultured plant cells

In sycamore cells grown on nitrate as opposed to glutamate there is a higher pentose phosphate pathway carbon flux relative to glycolysis in the early stages of cell growth when nitrate assimilation is most active. The high pentose phosphate pathway activity compared with glycolysis in nitrate grown cells is accompanied by enhanced levels of hexokinase, pyruvate kinase, glucose-6-phosphate de-hydrogenase, 6-phosphogluconate dehydrogenase and transketolase. There is no significant increase in activity of the solely glycolytic enzyme, phosphofructokinase. It is suggested that the increased pentose phosphate pathway activity in nitrate grown cells is correlated with a demand by nitrite assimilation for NADPH.II=Jessup and Fowler, 1976 b     

A new record ofAchlya klebsiana from snakehead,Channa striatus,with fungal infection in Myanmar

This is the first record of the discovery in Myanmar ofAchlya klebsiana, belonging to the family Saprolegniaceae.     

Novel heme-binding component in the serum of the channel catfish (Ictalurus punctatus)

The serum of the channel catfish (Ictalurus punctatus) was examined for heme- and hemoglobin-binding proteins. Electrophoretic mobility retardation assays failed to detect a hemoglobin-binding material similar to mammalian haptoglobin; however, a heme-binding component (not previously described) was identified in catfish seru. The heme-binding component was purified by gel filtration chromatography; electrophoretic analyses suggested it to be composed of two polypeptide subunits of molecular masses about 115 and 98 kDa. This composition is inconsistent with hemopexin, the known heme-binding serum protein of mammals. Although it was not fully saturated with heme, the catfish component contained detectable heme in normal sera. When complexed by the binding material, heme was used as an iron source by isolates of the bacterial Gram-negative genusAeromonas; the capacity of other bacteria to use the complex was not tested. The physiological function of the catfish heme-binding serum protein is presently not clear.     

Inorganic nitrogen metabolism in two cellulose-degrading clostridia

Inorganic nitrogen metabolism in two cellulose degrading clostridia, the mesophile Clostridium cellobioparum and the thermophile Clostridium thermocellum was investigated. Both strains show acetylene reduction (i.e. possibly nitrogenase activity), contain glutamine synthetase, glutamate dehydrogenase and glutamate-dependent transaminases. C. cellobioparum additionally contains a NADH-dependent glutamate synthase and a NH₄⁺-repressible glycine dehydrogenase (NADPH). Remarkably, acetylene reduction in C. thermocellum is not repressed by ammonium, casting doubt whether this activity is due to nitrogenase. The results are compared with the data from other saccharolytic clostridia.Abbreviation GOGAT glutamine-oxoglutarate amidotransferase (glutamate synthase)     

Immunological identification of two female-specific proteins from the plasma of Indian freshwater murrel,Channa punctatus (Bloch)

Existence of a non-phosphorylated female-specific protein (FS II), in addition to phosphorylated vitellogenin (FS I), in the plasma of murrel by exogenous administration of estradiol-17beta is reported. Polyspecific rabbit antibodies were raised against estrogen-inducible murrel plasma proteins. This antiserum was absorbed with normal male serum in order to obtain female-specific antiserum (FSAS). Radial immunodiffusion studies suggested that both the proteins (FS I and FS II) were present in the plasma of E2-treated and normal vitellogenic females and in the ovarian homogenate from gravid females, but absent in normal male plasma. Autoradiographic experiments demonstrated that phosphorus moiety was attached with FS I only. Further, immunoelectrophoretic analysis and peptide maps supported the observation that FS I and FS II were discrete, unrelated female-specific proteins.     

Scanning electron microscopic evaluation of effects of low pH on gills of Channa punctata (Bloch)

Bioassay of Channa punctata (± 36 g) was carried out in acidic waters of different pH. A 96 h LC₅₀, value was obtained at pH 5.3. Scanning electron microscopy of gills of C. punctata showed fusion of adjacent secondary lamellae. At this low pH, dissociation of epithelium of branchial arches and gill filaments take place. At 360 h the branchial epithelium ruptures developing lesions in the gills exposing the efferent filament vessels. At pH 6.6 the tips of adjacent filaments belonging to both oral and aboral hemibranchs fuse in blocks.     

A study of the role of glutamate dehydrogenase in the nitrogen metabolism of Arabidopsis thaliana

Glutamate-dehydrogenase (GDH, EC 1.4.1.2) activity and isoenzyme patterns were investigated in Arabidopsis thaliana plantlets, and parallel studies were carried out on glutamine synthetase (GS, EC 6.3.1.2). Both NADH-GDH and NAD-GDH activities increased during plant development whereas GS activity declined. Leaves deprived of light showed a considerable enhancement of NADH-GDH activity. In roots, both GDH activities were induced by ammonia whereas in leaves nitrogen assimilation was less important. It was demonstrated that the increase in GDH activity was the result of de-novo protein synthesis. High nitrogen levels were first assimilated by NADH-GDH, while GS was actively involved in nitrogen metabolism only when the enzyme was stimulated by a supply of energy, generated by NAD-GDH or by feeding sucrose. When methionine sulfoximine, an inhibitor of GS, was added to the feeding solution, NADH-GDH activity remained unaffected in leaves whereas NAD-GDH was induced. In roots, however, there was a marked activation of GDH and no inactivation of GS. It was concluded that NADH-GDH was involved in the detoxification of high nitrogen levels while NAD-GDH was mainly responsible for the supply of energy to the cell during active assimilation. Glutamine synthetase, on the other hand was involved in the assimilation of physiological amounts of nitrogen. A study of the isoenzyme pattern of GDH indicated that a good correlation existed between the relative activity of the isoenzymes and the ratio of aminating to deaminating enzyme activities. The NADH-GDH activity corresponded to the more anodal isoenzymes while the NAD-GDH activity corresponded to the cathodal ones. The results indicate that the two genes involved in the formation of GDH control the expression of enzymes with different metabolic functions.Abbreviations GDH glutamate dehydrogenase - GS glutamine synthetase - MSO methionine sulfoximine     

Development of the gonads in Channa punctatus Bloch (Osteichthyes: Channidae)

The history of the germ cells is traced from the time of hatching. The germ cells are larger in size and have faintly staining cytoplasm, clear cell outline and a distinct nucleus. They migrate by ameboid movement to reach the genital ridge and aggregate to lie against the gonadal epithelium prior to the formation of gonads. The germ cells are distributed along the gonad primordia. The period of sex differentiation occurs between the 5.4 mm to 12 mm stage. The testis formation is recognized by the presence of germ cell nests and the sperm duct cord. The formation of the ovary is noted by the enlargement of the germ cells of uniform size and the development of the ovarian cavity. The ovaries are described in four stages ranging from 21 mm to 135 mm fish. At 21 mm stage the ovarian cavity is continuous but is obliterated at 35 mm stage due to the projection of the ovigerous lamellae. The common opening for both the ovaries develops at 35 mm stage. The testes are described in four stages ranging from 23 mm to 135 mm fish. They differentiate more slowly and the first maturation division is seen at 90 mm stage.