Responses of isolated scale melanophores of a fresh water carp,Cirrhinus mrigala (Ham.) to zidovudine

Zidovudine (AZT) induced concentration related aggregation in C. mrigala melanophores. Denervated melanophores failed to respond to AZT. Specific and nonspecific alpha adrenoceptor antagonists completely blocked the responses of fish melanophores to AZT. Histamine and prostaglandin antagonists also inhibited aggregation of the melanophores induced by AZT. The results suggest that AZT may release a mixture of neurotransmitter like substances, which cause the aggregation of this fish melanophores.     

Seasonal variations in the histology of the pituitary gland of Cirrhinus mrigala (Ham.) an Indian freshwater major carp, in relation to gonadal activity.

1. Seasonal variations in the histology of the pituitary gland of Cirrhinus mrigala (Ham.), an Indian freshwater major carp, in relation to gonadal activity has been studied during a one year period commencing, January, 1971. 2. The proximal pars distalis undergoes a great deal of seasonal variation in size, weight and nature of pituicytes. 3. The percentage composition of acidophils and cyanophils in the proximal pars distalis show a reciprocal relationship during the year. The acidophils predominate during the restitution phase of the gonads while the cyanophils preponderate among the different cell types during the breeding season. 4. The chromophobes do not show any significant fluctuation in numerical abundance in relation to gonadal activity. 5. Cyanophils of the proximal pars distalis undergo changes with change in gonadal activity Concentration of glycoproteinaceous material is extremely low during the restitution phase but high during the maturation phase. The cyanophils also undergo hypertrophy and hyperplasia during the spawning period. The latter discharge their contents and become vacuolated during the post spawning period. 6. The number and size of the globules in the cyanophils are related to gonadal activity. 7. Acidophils present in the rostral pars distalis and pars intermedia do not appear to be related to gonadal activity in C. mrigala. 8. The average weight of the gland is directly related to the state of maturation of the gonads, an observation being recorded here for the first time.     

Identification of microsatellite DNA markers for population structure analysis in Indian major carp, Cirrhinus mrigala (Hamilton-Buchanan, 1882)

Forty‐four primer sequences available for four cyprinid fishes were tested to amplify microsatellite loci in Indian major carp, Cirrhinus mrigala. A total of 12 loci were successfully amplified with clear scorable patterns and five thereof were polymorphic. Suitability of the identified polymorphic loci in population structure analysis of C. mrigala was assessed. Genetic variation was examined in 76 specimens collected from five different rivers. The mean observed heterozygosity ranged from 0.247 to 0.333. Significant heterogeneity in allele frequencies was detected, indicating that the samples analysed did not belong to homogenous populations. The identified microsatellite markers are promising for the analysis of intraspecific divergence in C. mrigala across its distribution range.     

Phosphorus requirements and optimum calcium/phosphorus ratio in the diet of mrigal Cirrhinus mrigala (Ham.) fingerlings

An experiment was conducted to investigate phosphorus requirements and the optimal calcium/phosphorus (Ca/P) ratio on growth and carcass tissue composition of mrigal Cirrhinus mrigala (c. 6 g). Five purified diets were formulated to contain Ca/P ratios of 1 : 0 (0.35 : 0), 1 : 1 (0.35 : 0.35), 1 : 2 (0.31 : 0.63), 1 : 3 (0.24 : 0.71), and 1 : 4 (0.19 : 0.75), respectively. Growth performance and feed conversion ratio of mrigal responded significantly (P < 0.01) to the Ca =0.19 : P = 0.75 diet. Carcass protein, lipid, and P percentage also increased significantly with the higher P level. Based on this study, it may be concluded under the given conditions that the optimum Ca : P ratio in mrigal feed is 0.19 : 0.75.     

Dietary requirement of tryptophan for growth and survival of the Indian major carp, Cirrhinus mrigala (Hamilton-Buchanan) fry

The experimental diets (40% protein) contained graded levels of tryptophan (0.60, 0.75, 1.00, 1.25, 1.50, 1.75%) of dietary protein. Each test diet was fed to triplicate groups of mrigal fry twice daily at 10% of the total biomass for 8 weeks. The dietary tryptophan requirement was estimated by plotting weight gain against dietary levels of tryptophan using two separate regression equations, the point of intersection of two equations was taken as optimum level, which occurred at 0.48% of the diet (1.20% of dietary protein).     

Oilcakes as protein sources in supplementary diets for the growth of Cirrhinus mrigala (Ham.) fingerlings: laboratory and field studies

Five isonitrogenous diets (1-5) with 40% protein using oilcakes as protein sources were formulated and fed to Cirrhinus mrigala fingerlings maintained both under laboratory and field conditions. Water soaking of oilcakes for 24 h before incorporation in the diets helped in the reduction of antinutrient factors (phytase and tannins). Live weight gain in fish fingerlings fed on a diet containing groundnut oilcake (GNOC) was significantly (P < 0.05) enhanced in comparison to the other dietary treatments when examined at the end of a feeding schedule. Laboratory studies have further revealed that APD, PER, GPR and GER values were significantly (P < 0.05) enhanced, while those of feed conversion ratio were significantly (P < 0.05) reduced in fish fed on diet 1 containing GNOC. An analysis of water samples collected at two hourly interval from the aquaria revealed low levels of total ammonia (N-NH4+) excretion and reactive phosphate (O-PO4) production in fish fed on diet 1. Proximate carcass composition also revealed high accumulation of protein, fat, energy and phosphorus in fingerlings fed on a diet containing GNOC. Even in field studies a significant (P < 0.05) increase in mean fish weight gain and specific growth rate (SGR% d(-1)) was observed in fingerlings fed on diet 1, followed by canola (2), sunflower (3), mustard oilcake (4) and sesame (5). Water and sediment quality characteristics also correlated well with fish growth.     

Effect of 17α-methyl testosterone incorporated diets on growth of spotted snakehead,Channa punctatus and white carp,Cirrhinus mrigala

The effect of different concentrations of 17α-methyl testosterone incorporated diet on growth performance in the fry of Channa punctatus and Cirrhinus mrigala was evaluated. Four different doses of hormone such as 60, 80, 100 and 120?mg/kg in C. punctatus and 40, 60, 80 and 100?mg/kg in C. mrigala were administered through diet for a period of 90?days.Fifth group on a hormone free diet served as a control. The growth performance in terms of length and weight gain of the fry receiving 100?mg/kg in C. punctatus and 60?mg/kg in C. mrigala were significantly higher than those receiving 80, 120 and 0 (untreated control) mg hormone per kg feed. The highest specific growth rate (0.864?±?1.18%WG d^?1) at 100?mg/Kg diet and (2.47?±?1.26%WG d^?1) at 60?mg/kg diet were observed in C. punctatus and C. mrigala respectively, showing positive influence of hormone incorporated diet on the growth performance. However, the survival rate of both the species remained unaffected by different dosages of 17α-methyl testosterone.     

Effect of asiaticoside on the healing of skin wounds in the carp Cirrhinus mrigala: An immunohistochemical investigation

In the present study effect of asiaticoside, on healing of skin wounds in Cirrhinus mrigala is reported. Skin wound, approx. 2 mm in diameter was excised using sterile disposable biopsy punch. Immediately after infliction of the wound, epidermis from wound edge starts migrating as thin sheet toward wound gap. Fronts of migrating epidermis gradually advance, and results in complete epithelialization of wound. Experiments were conducted for 30 days and fishes were divided into control, sham, vehicle control and asiaticoside treated groups. Immunohistochemical localization of proliferating cell nuclear antigen positive cells indicating cellular proliferation and caspase 3 positive cells reflecting apoptosis was carried out and their density at different post wound intervals in each fish group was analyzed. Significant increase in cellular proliferation as well as decrease in apoptosis in both epidermis and dermis in fish treated with asiaticoside compared to sham and vehicle control fish is observed at different intervals of wound repair. This suggests that in treated group healing of skin wounds in fish is enhanced than in sham and vehicle control groups. Asiaticoside treatment in healing of skin wounds would greatly be beneficial to fish farmers as it could protect fish from invasion of pathogens and check fish mortality.     

Short-term mercury exposure on Na+/K+-ATPase activity and ionoregulation in gill and brain of an Indian major carp,Cirrhinus mrigala

Recently mercury pollution has been increased considerably in aquatic resources throughout the world and it is a growing global concern. In this study, the 96 h LC50 value of waterborne mercuric chloride for Cirrhinus mrigala was found to be 0.34 mg/L (with 95% confidence limits). Fingerlings of C. mrigala were exposed to 0.068 and 0.034 mg/L of mercuric chloride for 96 h to assess the Na⁺/K⁺-ATPase activity and ionoregulation (Na⁺, K⁺ and Cl^?) in gill and brain. Results showed that Na⁺/K⁺-ATPase activity and ionic levels (Na⁺, K⁺ and Cl^?) in gill and brain of fish exposed to different concentrations of mercuric chloride were found to be significantly (p < 0.05) decreased throughout the study period. Mercury inactivates many enzymes by attaching to sulfur atoms in which the enzyme Na⁺/K⁺-ATPase is highly sensitive to mercury. The inhibition of gill and brain Na⁺/K⁺-ATPase activity might have resulted from the physicochemical alteration of the membrane due to mercury toxicity. Moreover, inhibition of Na⁺/K⁺-ATPase may affect the ion transport and osmoregulatory function by blocking the transport of substances across the membrane by active transport. The present study indicates that the alterations in these parameters can be used in environmental biomonitoring of mercury contamination in aquatic ecosystem.     

Dietary total aromatic amino acid requirement and tyrosine replacement value for phenylalanine in Indian major carp: Cirrhinus mrigala (Hamilton) fingerlings

Two 8‐week growth trials were conducted to determine total aromatic amino acid requirement and tyrosine replacement value for phenylalanine in Cirrhinus mrigala fingerlings. To determine the phenylalanine requirement, 20 fish were randomly stocked in triplicate groups in 55‐L indoor polyvinyl flow‐through circular tanks and fed six experimental diets containing graded levels of phenylalanine (5.0, 7.5, 10.0, 12.5, 15.0 and 17.5 g kg^?1, dry diet) with 10 g kg^?1 tyrosine. Maximum weight gain (287%), best FCR (1.44) and PER (1.74) occurred at 12.5 g kg^?1 dietary phenylalanine. Quadratic regression analysis of weight gain, FCR and PER data indicated phenylalanine requirement at 13.5, 12.9 and 12.7 g kg^?1 of dry diet, respectively. Protein deposition was significantly (P < 0.05) higher at 12.5 g kg^?1 dietary phenylalanine. Based on the above results, phenylalanine requirement of C. mrigala is recommended at 13.0 g kg^?1 of dry diet, corresponding to 32.5 g kg^?1 of protein. On the basis of the above requirement, a second experiment with a similar design was conducted using six diets containing graded levels of tyrosine (2.1, 4.0, 6.0, 8.0, 10.0 and 12.0 g kg^?1) with 13.0 g kg^?1 phenylalanine fixed in all diets to determine the phenylalanine replacement value with that of tyrosine. Maximum weight gain (315%), best FCR (1.47) and PER (1.69) was at 8.0 g kg^?1 dietary tyrosine. Quadratic regression analysis of weight gain, FCR and PER data indicated tyrosine requirement at 9.0, 8.4 and 8.2 g kg^?1 of dry diet, respectively. Protein deposition was significantly (P < 0.05) higher at 8.0 g kg^?1 dietary tyrosine. On the basis of the above results, 8.5 g kg^?1 tyrosine, corresponding to 21.3 g kg^?1 of protein, is taken as the optimum requirement and the replacement value is 39.53% on a weight and 36% on a molar basis. Thus, the total aromatic amino acid requirement is 21.5 g kg^?1 of diet, corresponding to 53.8 g kg^?1 of protein for optimum C. mrigala growth.     

Morphological specializations of the buccal cavity in relation to the food and feeding habit of a carp Cirrhinus mrigala: A scanning electron microscopic investigation

The buccal cavity of an herbivorous fish, Cirrhinus mrigala, was investigated by scanning electron microscopy to determine its surface ultrastructure. The buccal cavity shows significant adaptive modifications in relation to food and feeding ecology of the fish. The buccal cavity of the fish is of modest size and limited capacity, which is considered an adaptation with respect to the small‐sized food items primarily consumed by the fish that could be accommodated in a small space. Modification of surface epithelial cells, on the upper jaw, into characteristic structures—the unculi—is considered an adaptation to browse or scrap, to grasp food materials, e.g., algal felts, and to protect the epithelial surface against abrasions, likely to occur during their characteristic feeding behavior. Differentiation of the highly specialized lamellar organ on the anterior region of the palate could be an adaptation playing a significant role in the selection, retention, and sorting out of palatable food particles from the unpalatable items ingested by the fish. The filamentous epithelial projections and the lingulate epithelial projections on the palatal organ in the posterior region of the palate are considered to serve a critical function in final selection, handling, maneuvering, and propelling the food particles toward the esophagus. The abundance of different categories of taste buds in the buccal cavity suggests that gustation is well developed and the fish is highly responsive in the evaluation and the selection of the preferred palatable food items. The secretions of mucous cells in the buccal cavity are associated with multiple functions—particle entrapment, lubrication of the buccal epithelium and food particles to assist smooth passage of food, and to protect the epithelium from possible abrasion. These morphological characteristics ensure efficient working of the buccal cavity in the assessment of the quality and palatability of ingested food, their retention and transport toward the esophagus. Such an adaptation may be essential in conducting the function most basic to the survival of the individuals and species—feeding. J. Morphol. 2009. © 2009 Wiley‐Liss, Inc.     

Evidence for invasive carp mediated trophic cascade in shallow lakes of western Victoria,Australia

Hydrobiologia - Lakes of western Victoria are typically shallow (2–3 m), slightly saline (3–8 ppt) and eutrophic (total phosphorus 0.1–5&nbsp;mg l?1 and total nitrogen...     

Comparative studies on carcass characteristics of marketable size farmed mrigal Cirrhinus mrigala, (Hamilton, 1822), and silver carp Hypophthalmichthys molitrix, (Val., 1844)

The carcass traits and commercial characteristics of farmed freshwater Cirrhinus mrigala and Hypophthalmichthys molitrix were investigated to calculate yield data useful for programming semi‐automated processing units. Specimens with average weights of 2500 and 3400 g were collected from both mrigal and silver carps, respectively. Samples were taken from grow‐out culture ponds of the Central Institute of Freshwater Aquaculture (CIFA), Odisha State, India. Carcass and offal yields as well as carcass cutability were assessed. Head yields were recorded as 14.9 and 27.5% for mrigal and silver carp, respectively. The gutted yield, headless yield and skinless dressed round percentages were determined as 89.4, 74.5 and 67.6% for mrigal and 92.8, 65.4 and 62.0% for silver carps, respectively. The meat: bone ratio in filleting averaged 4.8 for mrigal and 3.1 for silver carp. The middle cut of mrigal had both the highest total yield percentage and highest meat yield, whereas this was equally distributed between both the fore and middle cuts in silver carp. In both mrigal and silver carp the dry matter, ether extract and protein percentages were highest in the fore cut followed by middle and hind cut. In silver carp the percentage fat content was found to be significantly higher than in mrigal.     

Seasonal changes in the blood parameters of two major carps, Labeo rohita (Ham.) and Cirrhina mrigala (Ham.).

Seasonal changes in blood properties of two Indian major carps, L. rohita and C. mrigala, were investigated. Haematocrit values, haemoglobin concentrations and erythrocyte numbers showed seasonal fluctuations, being high from September to November and again in April-May, and low from January to March. Males had generally higher blood values than the females.     

5-HT receptor subtypes as key targets in mediating pigment dispersion within melanophores of teleost,Oreochromis mossambicus

The presence of distinct class of 5-HT receptors in the melanophores of tilapia (Oreochromis mossambicus) is reported. The cellular responses to 5-HT (5-hydroxytryptamine), 5-HT₁, and 5-HT₂, agonists on isolated scale melanophores were observed with regard to pigment translocation within the cells. It was found that 5-HT exerted rapid and strong concentration dependent pigment granule dispersion within the melanophores. The threshold pharmacological dose of 5-HT that could elicit a measurable response was as low as 4.7 × 10^? 12 M/L. Selective 5-HT₁ and 5-HT₂ agonists, sumatriptan and myristicin were investigated and resulted in dose-dependent pigment dispersion. The dispersing effects were effectively antagonized by receptor specific antagonists. It is suggested that 5-HT-induced physiological effects are mediated via distinct classes of receptors that possibly participate in modulation of pigmentary responses of the fish.     

Acute and sublethal effects in an Indian major carp Cirrhinus mrigala exposed to silver nitrate: Gill Na+/K+-ATPase, plasma electrolytes and biochemical alterations

Due to prolonged use of silver in many applications, it enters into the freshwater and affects the aquatic organisms. Fingerlings of Cirrhinus mrigala were exposed to acute and sublethal concentrations of silver nitrate and the alterations of gill Na(+)/K(+)-ATPase, plasma electrolytes and biochemical parameters were assessed. The median lethal concentration of silver nitrate to the fish C. mrigala for 96 h was found to be 0.107 mg/l (with 95% confidence limits). 1/10th of LC 50 96 h value (0.0107 mg/l) was selected for sublethal study. During acute treatment branchial Na(+)/K(+)-ATPase activity was inhibited approximately 44.34% after 96 h of exposure. In sublethal treatment, silver nitrate could not produce a significant change in the activity of the enzyme at the end of 7th day. However, after 14th day, significant (p < 0.05) decrease was noted showing 22.52%-49.11% in rest of the study period. Silver intoxication resulted hyponatremia, hypokalemia, hypochloremia, and hypoproteinemia in both the treatments. Despite the decrease in these parameters, plasma glucose level was found to be increased in both the treatments to endure the silver toxicity. We suggest that the alterations in branchial Na(+)/K(+)-ATPase activity, plasma electrolytes, and biochemical parameters of fish may be useful in environmental biomonitoring and to assess the health of fish in freshwater habitat contaminated with silver.