Fine structure and histochemistry of the venom gland in the Indian stinging catfish (Heteropneustes fossilis)

The venom glands of Heteropneustes lie deep in the epidermis at the sides of the pectoral fin spines, and consist of large cells that react positively to histochemical tests for proteins, histidine and tyrosine, negatively to periodic acid-Schiff and for serotonin and bombesin. The venom cells are of two types, appearing to have dense or lucent cytoplasm when seen by electron microscopy. The dense type has the better developed Golgi systems, the lucent type has more ribosomes. Both appear to differentiate from the basal layer of the epidermis. The epidermis over the glands has a zone with relatively few desmosomes and enlarged intercellular spaces. Both staining reactions and fine structure differentiate the venom gland cells from the club cells of the epidermis, to such an extent that they must be considered distinct secretory elements.     

Lipids in the skin of a cat-fish Heteropneustes fossilis (Bloch) (Heteropneustidae,Pisces)

Summary Localization and characterization of different lipids in the cellular constituents of the skin of Heteropneustes fossilis has been made using several histochemical techniques.High contents of cholesterol, its esters and phospholipids have been correlated with the metabolically active state of the basal cells undergoing cell proliferation and differentiation.The polygonal cells in the outermost layer of the epidermis, though rich in phospholipid contain small amounts of cholesterol and its esters. This has been correlated with the metabolically less active state of these cells.Neutral lipids and phospholipids in the polygonal cells of the outermost layer may contribute to the contents of surface slime and act as an efficient barrier for the penetration of water through the skin.The deposits of neutral lipids in the subcutis may provide energy during the period of fasting, act as a barrier for water diffusion through the skin and serve as shock absorbing pads protecting the fish from mechanical injury.Supported by a post doctoral fellowship sponsored by the Council of Scientific and Industrial Research, Government of IndiaSupported by a research scholarship sponsored by Banaras Hindu University     

Purification and immunological characterization of catfish (Heteropneustes fossilis) metallothionein

Catfish hepatic metallothionein was purified to homogeneity by Sephadex G-75 gel filtration, DEAE-Sephadex A-25 column chromatography and preparative polyacrylamide gel electrophoresis. Induction by cadmium and zinc, characteristic UV spectrum, cadmium binding property and its low MW established that it was a metallothionein. Antibody was raised in rabbit against catfish metallothionein. Catfish antimetallothionein cross-reacted with other fish metallothioneins but not with chicken or rodent metallothionein. Catfish metallothionein is more electronegative as compared to mouse, rat, chicken or hamster metallothionein. Catfish MT appeared to aggregate readily on storage and to be less electronegative.     

Purification and immunological characterization of catfish (Heteropneustes fossilis) metallothionein

Summary Catfish hepatic metallothionein was purified to homogeneity by Sephadex G-75 gel filtration, DEAF-Sephadex A-25 column chromatography and preparative polyacrylamide gel electrophoresis. Induction by cadmium and zinc, characteristic UV spectrum, cadmium binding property and its low MW established that it was a metallothionein. Antibody was raised in rabbit against catfish metallothionein. Catfish antimetallothionein cross-reacted with other fish metallothioneins but not with chicken or rodent metallothionein. Catfish metallothionein is more electronegative as compared to mouse, rat, chicken or hamster metallothionein. Catfish MT appeared to aggregate readily on storage and to be less electronegative.Abbreviations MT Metallothionein - PBS Phosphate Buffered Saline - SDS Sodium Dodecyl Sulfat - PAGE Polyacrylamide Gel Electrophoresis Part of the work was reported in Proceedings of 54th Annual General Meeting of the Society of Biological Chemists, India, 1985.     

Length–weight relationship of giant snakehead,Channa marulius and stinging catfish,Heteropneustes fossilis from the River Ganga,India

The present study describes the length–weight relationship of two commercially important freshwater fish species of India viz., Channa marulius and Heteropneustes fossilis collected from the Ganga River, during the period January 2009–December 2010.     

Thermal tolerance and preference of the Indian catfish Heteropneustes fossilis

Synopsis The catfish Heteropneustes fossilis tolerates a wide range of temperatures. The minimal (7.9°C) and maximal (39.8°C) lethal temperature values obtained during summer are higher than the minimal (4°C) and maximal (37.7°C) lethal temperature values obtained during winter; gradual heating or cooling versus abrupt exposure to various temperatures did not produce significant differences. Catfish acclimated to temperatures of 28° (summer) or 16°C (winter) finally selected temperatures ranging from 31.3° to 32° C, when placed in a temperature gradient of 15° to 35° C. Catfish avoid temperatures below 25° C regardless of seasonal acclimatization.     

Effects of stress and food deprivation on catfish, Heteropneustes fossilis (Bloch)

No significant changes in plasma cortisol and plasma osmolarity (the indicators of primary and secondary response respectively) were observed when the blood samples were obtained from unanaesthetized, anaesthetized and stressed catfish, H. fossilis. The results suggest that the catfish is fairly hardy and not easily susceptible to stress by routine laboratory handling. The sustained plasma glucose levels and decreased liver and muscle glycogen concentrations during cessation of feeding of the catfish suggest that during period of food deprivation, it draws its energy through glycogenolysis. Hence, in any study dealing with carbohydrate metabolism, the catfish needs to be fed during acclimation and experimental periods.     

Surface ultrastructure of the olfactory rosette of an air-breathing catfish,Heteropneustes fossilis (Bloch)

The surface architecture of the olfactory rosette ofHeteropneustes fossilis (Bloch) has been studied by scanning electron microscopy. The olfactory rosette is an oval structure composed of a number of lamellae arranged pinnately on a median raphe. The raphe is invested with epithelial cells and pits which represent goblet cell openings. On the basis of cellular characteristics and their distribution the lateral surface of each olfactory lamella is identified as sensory, ciliated non-sensory and non-ciliated non-sensory epithelium. The sensory epithelium is provided with receptor and supporting cells. The ciliated non-sensory epithelium is covered with dense cilia obscuring the presence of other cell types. The non-ciliated non-sensory epithelium is with many polygonal areas containing cells.     

Cloning, sequencing and expression of cDNA encoding growth hormone from Indian catfish (Heteropneustes fossilis)

A tissue-specific cDNA library was constructed using polyA⁺ RNA from pituitary glands of the Indian catfishHeteropneustes fossilis (Bloch) and a cDNA clone encoding growth hormone (GH) was isolated. Using polymerase chain reaction (PCR) primers representing the conserved regions of fish GH sequences the 3′ region of catfish GH cDNA (540 bp) was cloned by random amplification of cDNA ends and the clone was used as a probe to isolate recombinant phages carrying the full-length cDNA sequence. The full-length cDNA clone is 1132 bp in length, coding for an open reading frame (ORF) of 603 bp; the reading frame encodes a putative polypeptide of 200 amino acids including the signal sequence of 22 amino acids. The 5′ and 3′ untranslated regions of the cDNA are 58 bp and 456 bp long, respectively. The predicted amino acid sequence ofH. fossils GH shared 98% homology with other catfishes. Mature GH protein was efficiently expressed in bacterial and zebrafish systems using appropriate expression vectors. The successful expression of the cloned GH cDNA of catfish confirms the functional viability of the clone.     

Effects of hypophysectomy on some osmoregulatory parameters of the catfish, Heteropneustes fossilis (Bloch)

The catfish, H. fossilis, survives for long periods after hypophysectomy, although with impaired osmoregulatory mechanisms. Plasma osmolarity and cortisol levels decline significantly within 2 hr after hypophysectomy and attain the lowest values by about 27 hr. Hypophysectomy also results in a marked decrease in urine flow rate principally due to reduced glomerular filtration. The reduction in the ability of the kidney of hypophysectomized catfish to eliminate water results in hyperhydration of blood and muscle. Urine osmolarity and sodium concentration increase due to reduced tubular reabsorption of sodium. There is, however, no net change in the total urinary sodium loss. The catfish survives in fresh water after hypophysectomy presumably because its tissues can tolerate significant dilution of the body fluids.     

Gonadotropin releasing hormone (GnRH) neurones of triploid catfish,Heteropneustes fossilis (Bloch): an immunocytochemical study

Gonadotropin-releasing hormone (GnRH), a regulator of gonadal maturation in vertebrates, is primarily secreted by neurosecretory cells of the pre-optic area (POA) in the forebrain of teleosts. GnRH-immunoreactive (GnRH-ir) cells of this area demonstrate positive correlation in number and size of soma with gonadal maturity and directly innervate the pituitary in most teleosts. Gonadal development in triploid fish remains impaired due to genetic sterility. The gonadal immaturity in triploid fish may be due to low levels of gonadotropin and sex steroids during the vitellogenic phase of reproductive cycle. However, the nature of GnRH-ir cells in triploid fish is not yet known. Triploid catfish (H. fossilis) showed significant decrease (P<0.001) in size and number of immunoreactive-GnRH cells of POA and low immunoreactivity in pituitary in comparison to their diploid full-sibs during the late pre-spawning phase of ovarian cycle. This study suggests that low activity of GnRH-cells in triploid may be due to lack of positive feedback stimulation by sex steroids and/or reduced responsiveness of sensory cells to environmental cues required for gonadal maturation in teleosts.     

Role of ureogenesis in the mud-dwelled Singhi catfish (Heteropneustes fossilis) under condition of water shortage

The air-breathing Singhi catfish Heteropneustes fossilis was kept inside moist peat for 1 month mimicking their normal habitat in summer and the role of ureogenesis for their survival in a water-restricted condition was studied. The ammonia excretion rate by the mud-dwelled fish increased transiently between 6 and 12 h of re-immersion in water to approximately between eight and 10-fold, followed by a sharp decrease almost to the normal level at the later part of re-immersion. The urea-N excretion by the mud-dwelled fish increased to approximately 11-fold within 0-3 h of re-immersion, followed by a gradual decrease from 9 h onwards. The rate of urea-N excretion by the mud-dwelled fish, however, remained significantly higher (approx. threefold more) than the control fish even after 36-48 h of re-immersion. Although there was a significant increase of both ammonia and urea levels in the plasma and other tissues (except ammonia in the brain), the level of accumulation of urea was higher than ammonia in the mud-dwelled fish as indicated by the decrease in the ratio of ammonia: urea level in different tissues including the plasma. The activities (units/g tissue and /mg protein) of glutamine synthetase and three enzymes of the urea cycle, carbamyl phosphate synthetase, argininosuccinate synthetase and argininosuccinate lyase increased significantly in most of the tissues (except the brain) of the mud-dwelled fish as compared to the control fish. Higher accumulation of ammonia in vivo in the mud-dwelled Singhi catfish is suggested to be one of the major factors contributing to stimulation of ureogenesis. Due to this physiological adaptive strategy of ureogenesis, possibly along with other physiological adaptation(s), this air-breathing amphibious Singhi catfish is able to survive inside the moist peat for months in a water-restricted condition.