Role of cathepsins B and D in proteolysis of yolk in the catfish Clarias gariepinus

Fish Physiology and Biochemistry - Yolk processing pathways vary in the oocytes of benthophil and pelagophil teleosts. The present study investigated the yolk processing pattern in the oocytes of...     

Growth and carcass composition of giant freshwater prawn, Macrobrachium rosenbergii (De Man), fed different isonitrogenous and isocaloric diets

A feeding experiment was conducted for 135 days to observe the effect of different isonitrogenous (35% crude protein) and isocaloric (385 kcal) diets on the growth and carcass composition of giant freshwater prawn, Macrobrachium rosenbergii ( De Man 1879 ). Three experimental diets (ED1, ED2 and ED3) were prepared using locally available ingredients. These diets differed mainly in terms of percent contribution of major protein sources such as fish meal, soybean meal, groundnut oil cake and mustard oil cake. Experimental diets were evaluated against a commercial diet, which served as the control (CD). Juveniles 1.87–2.44 g in size were stocked at a population density of 40 000 ha⁻¹ and fed thrice daily at 10% in the beginning and reducing gradually to 7% and 5% of the body weight during the experimental period. No significant differences (P>0.05) in the growth performance were observed; however, a significantly (P<0.05) higher yield (721.9 kg ha⁻¹ 135 days⁻¹) was recorded for prawn fed with control diet, followed by experimental diet 2 (676.5 kg ha⁻¹ 135 days⁻¹, having soybean meal as a major protein source). The survival ranged between 63.8% and 77.7%, with different diets showing significantly higher survival. The apparent feed conversion ratio values of diets ranged between 3.15 and 3.49, with experimental and control diets showing non‐significantly lower AFCR values. At the end of the experiment, representative specimens from each treatment were collected and their carcass composition was measured. Analysis of variance showed that carcass protein and total carbohydrate contents were significantly (P<0.05) higher in prawns fed on a fish–soybean meal‐based diet (ED3) and a control diet. The total lipid contents of prawns, however, did not differ significantly among the various dietary treatments. The results of our study suggest that the experimental diets could be used effectively for M. rosenbergii without compromising growth and flesh quality.     

Induction of AIDS in rhesus monkeys by molecularly cloned simian immunodeficiency virus

Better understanding of the pathogenesis of acquired immunodeficiency syndrome (AIDS) would be greatly facilitated by a relevant animal model that uses molecularly cloned virus of defined sequence to induce the disease. Such a system would also be of great value for AIDS vaccine research. An infectious molecular clone of simian immunodeficiency virus (SIV) was identified that induces AIDS in common rhesus monkeys in a time frame suitable for laboratory investigation. These results provide another strong link in the chain of evidence for the viral etiology of AIDS. More importantly, they define a system for molecular dissection of the determinants of AIDS pathogenesis.     

A circadian output in Drosophila mediated by neurofibromatosis-1 and Ras/MAPK

Output from the circadian clock controls rhythmic behavior through poorly understood mechanisms. In Drosophila, null mutations of the neurofibromatosis-1 (Nf1) gene produce abnormalities of circadian rhythms in locomotor activity. Mutant flies show normal oscillations of the clock genes period (per) and timeless (tim) and of their corresponding proteins, but altered oscillations and levels of a clock-controlled reporter. Mitogen-activated protein kinase (MAPK) activity is increased in Nf1 mutants, and the circadian phenotype is rescued by loss-of-function mutations in the Ras/MAPK pathway. Thus, Nf1 signals through Ras/MAPK in Drosophila. Immunohistochemical staining revealed a circadian oscillation of phospho-MAPK in the vicinity of nerve terminals containing pigment-dispersing factor (PDF), a secreted output from clock cells, suggesting a coupling of PDF to Ras/MAPK signaling.     

Induction of AIDS-like disease in macaque monkeys with T-cell tropic retrovirus STLV-III

The T-cell tropic retrovirus of macaque monkeys STLV-III has morphologic, growth, and antigenic properties indicating that it is related to HTLV-III/LAV, the etiologic agent of the acquired immune deficiency syndrome (AIDS) in humans. Four of six rhesus monkeys died within 160 days of STLV-III inoculation with a wasting syndrome, opportunistic infections, a primary retroviral encephalitis, and immunologic abnormalities including a decrease in T4+ peripheral blood lymphocytes. These data show that an immunodeficiency syndrome can be produced experimentally in a nonhuman primate by an agent from the HTLV-III/LAV group of retroviruses. The STLV-III-macaque system will thus provide a useful model for the study of antiviral agents and vaccine development for human AIDS.     

Quantitative Estimation of Genetic Variability in Morphological Characteristics of Eastern Cottonwood (Populus deltoides Bartr.) Clones

The study was carried out to analyze the genetic variability for different growth parameters in poplar clones at the age of 2 and 3 yr in the nursery. Forty-nine exotic and indigenous clones of poplar were evaluated for eight morphological traits. Clones were planted in randomized block design (RBD) with three replications with four clones in a block in each treatment. Observations for different characters were recorded on six selected competitive clones per genotype. Results showed a high interclonal variability for most parameters. Statistically significant differences among clones indicated that the majority of study characters are controlled by genetic factors, specific to each clone. Highly significant genotypic difference supported by wide range of variation of mean and range values were observed for the characters under study. Significant and positive correlation was observed between diameter at breast height (DBH) and plant height. Leaf lamina length showed positive and significant correlation with petiole length, total leaf length, leaf width, and L/B ratio. Total leaf length showed positive and significant correlation with leaf width and L/B ratio. High estimates of heritability (in a broad sense) were observed for almost all characters in the study. High genetic advance expressed as percent of mean was recorded for petiole length (60.90), followed by plant height (60.78) and collar diameter (44.19) at 2 yr. At the age of 3 yr, genetic advance was found maximum for petiole length (60.05), followed by collar diameter (47.62) and plant height (45.29). The efforts for selecting new clones and their field-testing must continue under a long-term improvement plan so that the best clones can be recommended for plantations and hybridization programs.     

Relative potencies of natural estrogens on vitellogenin and choriogenin levels in the Indian freshwater spotted snakehead, <Emphasis Type="Italic">Channa punctata</Emphasis>: in vivo and in vitro studies

The relative efficacies of three natural estrogens viz., estrone (E₁), estradiol-17β (E₂) and estriol (E₃) to induce synthesis of vitellogenin (Vg) and choriogenin (Chg) were assessed in primary hepatocyte cultures of the Indian freshwater spotted snakehead, Channa punctata. Hepatocytes were isolated from the spotted snakehead liver by a non-enzymatic protocol. Optimum culture conditions were standardized for ensuring their viability and functioning. Isolated hepatocytes were cultured for 48 h for monolayer formation and then exposed to various concentrations (0.001–10 μM) of the three estrogens. Competitive homologous ELISAs, developed and validated for spotted snakehead Vg and Chg were employed to determine the amounts of these two proteins secreted into the culture medium after 48 h of incubation. The results reveal that although all the three estrogens were effective in inducing the production of Vg and Chg in a dose-dependent manner, there were differences in their relative potencies. Of three estrogens, E₁ was the least potent and could induce synthesis of Vg and Chg only at a minimum concentration of 0.5 μM; whereas significant levels of both the proteins were quantified in culture medium by exposing the hepatocytes to E₂ or E₃ even at a concentration of 0.001 μM. All three estrogens were effective in inducing synthesis of Vg and Chg in vivo also. These results suggest the possibility of employing the above in vitro experimental design to monitor the presence of estrogens/estrogen-like chemicals in natural waters, which could interfere with the estrogen receptor system of fish. This study further points to the possibility of using Chg, in addition to Vg, as a parameter for screening various chemicals for their estrogenic activity.     

Seasonal Differences in Growth Performance of Four Strains of Common Carp,Cyprinus carpio in India

To assess strain related differences in growth performance and growth patterns under the same culture environment, four strains of common carp, two each of the scale carp, Cyprinus carpio var. communis (Chinese big-belly carp and long bodied carp) and mirror carp, C. carpio var. specularis (scattered carp and linear carp) were communally stocked in three fertilized earthen ponds of 0.14 ha each at 5,000 fish ha^?1 in the ratio of 1:1:1:1 during an 11-month (February to December) culture cycle. Chinese big-belly carp grew larger than other groups, among which there were no significant differences. Scale carp strains performed relatively better than mirror carp at higher temperatures and then essentially stopped growing as temperatures declined into winter. The strains of mirror carp, on the other hand continued growing well later into the cold season.