Studies on the reproductive physiology of Lates calcarifer (Bloch)

Research on f i s h reproduction has progressed considerably during the last few years owing t o the development of new and varied techniques. However, i t s application t o acquaculture has largely been confined t o a few selected species for quite a long time. Recognition of acquaculture as a means t o provide easy access t o the desired species has led the awareness 2mong culturists, towards the di verisification in terms of variety of fishes being brought under the culture systems

Ultrastructure of egg membrane of rohu (Labeo rohita)

The fine structure of the egg envelope and micropyle of unfertilised spawned eggs of rohu (Labeo rohita) was observed using scanning electron microscope (SEM). The outer surface showed regularly arranged pores (dia. 0.20 - 0.25 μm) but was devoid of any filaments, fibrils or wrinkles. The micropyle was funnel shaped which exibited an outer pit (10 μm dia.) narrowing into a distinct canal (4.5 μm dia.). The larger diameter of the micropylar canal in comparison with the sperm head size of rohu and some other cyprinids make intergeneric and interspecific hybridisation easy in rohu

Fine structural changes of Rohu (Labeo rohita) sperm after dilution with cryoprotectants

Spermatozoa of rohu (Labeo rohita) were diluted in two cryodiluents and fine structural changes were investigated. Damages were observed in head, mid-piece and tail of about 51% spermatozoa immediately after dilution in one of the cryodiluents. After 10 minutes of equilibration period, the frequency of damaged sperms increased to 85%. The other diluent did not exhibit signif~cant structural changes unlike the former one and nearly 60% sperms remained visibly intact even after 10 minutes of equilibration time. The present investigation points out (1) diluents inhibiting sperm motility alone need not always be ideal for a species and (2) usefulness of ultrastructural images of fish sperms in determining the fertilizing ability of milt and in preliminary screening and selection of cryodiluents for deepfreezing programmes

Esterases in Indian major carps - 'Rohu' (Labeo rohita) and 'Mrigal' (Cirrhinus mrigala) (Teleostei, Cyprinidae)

Soluble esterases of rohu and mrigal were characterised by electrophoresis using different substrates and inhibitors. Four separable regions of esterolytic activity were observed in liver, brain and white muscle extracts of rohu and in three regions in mrigal, with liver of both species exhibiting maximum number of bands. Species-specific differences were observed in some of the regions. Striking substrate-specific reactions were not observed but based on sensitivity to inhibitors, the liver esterases of both species were classified into aryl, carboxyl, choline, ER and Esdp esterases

Egg production in the threatened seabass, Lates calcarifer (Bloch) along Tuticorin coast, Gulf of Mannar

The total annual potential fecundity of mature Lates calcarifer (n = 47) of 855 to 1,255 mm range along Tuticorin coast in Gult of Mannar was estimated. The lowest fecundity was observed to be 3.85 x 10^ and highest 30.18 x 10'^ eggs. The fecundity was positively correlated with the length and weight of the fish

Hypothalamo-neurosecretory system of the female sea bass, Lates calcarifer (Bloch), with special reference to gonadal maturation

Hypothalamus of Lates calcarifer (Family : Centropomidae) consists mainly of nucleus preopticus (NPO), nucleus lateralis tuberis (NLT) and their axonal tracts. NPO is a paired structure situated on either side of the third ventricle slightly above the optic chiasma. It is a highly vascularised structure and cytoarchitecturally divisible into dorsal pars magnocellularis (PMC) comprising larger neurons and ventral pars parvocellularis (PPC) with smaller neurosecretory cells. In the hypothalamus the NLT cells were found distributed uniformly in the infundibular floor adjacent to the pituitary stalk. Prominent phloxine-positive neurosecretory material (NSM) was encountered in PPC of matured female. Though neurosecretory cells of both NPO and NLT were positive to aldehyde fuchsin (AF), acid and chrome-alum-hematoxylin-phloxine (CAHP), cellular differentiation was more marked in the latter. Both NPO and NLT contributed beaded axons to form the neurohypophysial tract. Herring bodies (HB) of varying sizes were encountered in the anterior neurohypophysis (ANH). Neurosecretory cells of both NPO and NLT exhibited fluctuations in their secretory activity in response to the gonadal maturation

Population Genetic Structure of Endemic and Endangered Yellow Catfish, Horabagrus brachysoma, Using Allozyme Markers

The allozyme variation and population genetic structure of Horabagrus brachysoma in three natural populations from the southern part of theWestern Ghats region, India, were investigated by polyacrylamide gel electrophoresis. Variations at 14 loci from 14 enzyme systems were analyzed. The allozyme analysis revealed a high level of genetic variation in this species, with an average of observed alleles per locus of 2.357 and observed heterozygosity of 0.178. The positive value of the fixation index (FIS = 0.507) implied a significant deficiency of heterozygosity at the population level. The highly significant probability (P<0.0001) for the overall loci suggested that the three sample sets were not part of the same gene pool

Identification of female specific protein in seabass, Lates calcarifer (Bloch)

Electrophoretic serum protein profile of female Lates calcarifer reveals appearance of female specific protein during gonadotropic dependent stages of ovarian growth. The protein is conspicuously absent in the serum of maturing males. The protein stains positively for carbohydrate, lipids and calcium indicating it to be vitellogenin. The vitellogenin band first appears in fish with maturing ovaries (stage 3) and stain intense and sharp till stage 4. At stage 5 (ripe) the band appears diffused. The protein is lacking in the serum profile of immature (stage 1), resting preparatory (stage 2) and spent (stage 6) as well as in maturing male fish. The correlative pattern of vitellogenin band with ovarian maturation stages provides evidence of single spawning in L. calcarifer

Effect of humic acid and nutrients mixture on quality parameter of Tomato (Lycopersicon esculentum Mill.) under polyhouse condition

An experiment was conducted on Effect of humic acid and nutrients mixture on growth and yield parameter of Tomato (Lycopersicon esculentum Mill.) under polyhouse condition at Rajasthan College of Agriculture, Udaipur (Raj.). The data was analyzed statistically following completely randomized design. The results revealed that treatment T7 [(RDF + humic acid 10 kg/ha soil application + humic acid 0.1% foliar spray + nutrient mixture foliar spray (0.2% Ca + 0.5% Mg + 0.2% B + 0.5% Zn)] was recorded superior to enhance leaf nutrients analysis Ca (1.656%), Mg (0.763%), Zn (25.07ppm) and B (61.94ppm), fruit nutrient analysisCa (1.904%), Mg (0.877%), Zn (58.98ppm) and B (61.84ppm), total Soluble Solids (TSS) (6.020%), ascorbic acid content (39.85mg/100g), lycopene content (3.75 mg/100g) and cost benefit ratio (4.81)

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