The main objective of the present study is to improve the immune power of Cyprinus carpio by using Euphorbia hirta plant leaf extract as immunostimulants. The haematological, immunological and enzymatic studies were conducted on the medicated fish infected with Aeromonas hydrophila pathogen. The results obtained from the haematological studies show that the RBC count, WBC count and haemoglobin content were increased in the infected fish at higher concentration of leaf extract. The feeds with leaf extract of Euphorbia hirta were able to stimulate the specific immune response by increasing the titre value of antibody. It was able to stimulate the antibody production only up to the 5th day, when fed with higher concentrations of (25 g and 50 g) plant leaf extract. The plant extract showed non-specific immune responses such as lysozyme activity, phagocytic ratio, NBT assay, etc. at higher concentration (50 g) and in the same concentration (50 g), the leaf extract of Euphorbia hirta significantly eliminated the pathogen in blood and kidney. It was observed that fish have survival percentage significantly at higher concentration (50 g) of Euphorbia hirta, when compared with the control. The obtained results are statistically significant at P < 0.05 and P < 0.01 levels. This research work suggests that the plant Euphorbia hirta has immunostimulant activity by stimulating both specific and non-specific immunity at higher concentrations.

These results indicate that Aegle marmelos stimulates the immunity and makes the freshwater fish Cyprinus carpio more resistant to Aeromonas hydrophila.

No abstract

The study is aimed at developing appropriate media for the mantle explant culture of abalone Haliotis varia. The effect of different media viz., L-15, Ham's F12, M199 was studied in combination with 10% Fetal Calf Serum (FCS) and 10% tissue extracts of gonad, mantle and whole body of abalone, H. varia to understand cell behaviour, cell yield and cell adherence in mantle explant culture of H. varia. Cultures with L-15 media gave better cell yield and M199 promoted better cell adherence. Addition of mantle extract to all media enhanced the cell yield to a maximum followed by whole body extract. Addition of whole body extract facilitated in cell adherence followed by the addition of mantle extract.

This study reports the results on induced meiotic diploid gynogenesis and female homogametic nature in the Indian cat¢sh, Heteropneustes fossilis. The eggs of H. fossilis were inseminated with conspe-ci¢c sperm. The sperm suspension was diluted to 1 Â 10 7 sperm mL À 1 in Hanks balanced salt solution. Sperm were irradiated under UV light, with the exposure time ranging from 15 to 360 s (7500 ergs mm À 2 for 60 s). The genetic inactivation of paternal chromosomes was con¢rmed by chromosome counting from the larval cells and the larvae also had a characteristic haploid syndrome. A typical 'Hertwig e¡ect' in the yield of hatched larvae was observed with doses of UV exposure 475 s (9375 ergs mm 2 ). Larvae resulting from sperm UV irradiated above 120 s (15000 ergs mm 2 ) were 100% haploids. Application of heat shock to the activated eggs was e¡ective in suppressing the release of the second polar body (meiotic gynogenesis) and resulted in diploid gynogenetic larvae morphologically identical to those of the control. The best yield of diploid gynogens (49.3% with respect to the control) was found to be at 6 min after egg activation and the heat shock at 41 1C for a 1-min duration, at an ambient water temperature of 27 1C. A total of 113 diploid gynogenetic fry from seven di¡erent female ¢sh were reared and subjected to sexing. All gynogenetic ¢sh were female in contrast to the control, which had a mean sex ratio of 56.7% females (which was not signi¢cantly di¡erent from 50% female). From these results, the sex determination mechanism in H. fossilis was presumed to be female homogamety.