Growth enhancement and food conversion efficiency of transgenic fish Labeo rohita

Three family lines of fast growing transgenic rohu Labeo rohita (rohu) were generated by electroporated-sperm-mediated transfer of the vectors harboring CMV promoter or grass carp beta-actin promoter fused to endogenous rohu GH (rGH) cDNA. The gene transfer efficiency was 25%. The transgenic rohu (family line 1) with CMV promoter showed a growth enhancement of four times normal size, whereas those (family lines 2 and 3) generated with beta-actin promoter grew 4.5 and 5.8 times faster than their respective control siblings. Southern analysis confirmed the transgene extrachromosomal (Te) persistence until the 60th week in family 1. The individuals of family lines 2 and 3, however, showed integration (Ti), as well as persistence as extrachromosomal copies (Te) until the age of 30 weeks. Mosaicism of the transgene was shown at the levels of its presence and expression. The ectopic expression of rGH mRNA was confirmed by RT-PCR. Feeding experiments revealed that the transgenic rohu ate food at a lower rate but grew more efficiently than their control siblings.     

Enhanced expression of beta-thymosin mRNA in the ovary of GnRH analog or estradiol-17beta-treated paradise fish,Macropodus opercularis

cDNA clones were isolated as expressed sequence tags (ESTs) from the ovarian cDNA library of Macropodus opercularis. The EST sequences showed similarity with many housekeeping genes and ribosomal proteins. One of the ESTs showed similarity to beta-thymosin, a 5-kDa polypeptide expressed under different physiological conditions. The cDNA corresponding to beta-thymosin of M. opercularis is 368 bp in length and codes for a putative polypeptide of 42 amino acids. Multiple alignment of the deduced amino acid sequence showed 61% similarity with piscine beta-thymosins and 56% similarity with mammalian beta-thymosins. Administration of a gonadotropin releasing hormone analog or estradiol-17beta induced an increase in the gonadosomatic index, oocyte diameter and also enhanced expression of beta-thymosin m-RNA in the recrudizing ovary. This report indicates that both GnRH analog and E(2) might induce similar pathways for the differentiation of ovarian cells for the maturation of oocytes.     

Antihepatotoxic effect of beta-carotene on paracetamol induced hepatic damage in rats

Enzyme levels of serum glutamate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT) and alkaline phosphatase (ALP) increased following paracetamol induction were significantly lowered due to pretreatment with the beta-carotene (BC). This supplementation reversed the trend inducing a significant decrease in bilirubin and urea levels. Paracetamol administration significantly reduced hepatic glycogen, glutathione (GSH), glutathione-S-transferase (GST), glutathione peroxidase (GPX) and glutathione reductase (GSH-R). Pretreatment of rats with BC significantly increased the enzyme activities. The results suggest hepatoprotective activity of BC.     

Cloning and Characterization of the Crystal Protein-Encoding Gene of Bacillus thuringiensis subsp. yunnanensis

Molecular cloning and characterization of a novel cry gene, cry32Aa, of Bacillus thuringiensis subsp. yunnanensis was carried out. The Cry32Aa protein was predicted to have a molecular mass of 139.2 kDa and was found to have an unusual 42-amino-acid-long tail at the C terminus. The cry32Aa gene was localized on the 103-MDa plasmid of the organism. Bioassays showed no toxicity against several moths and mosquitoes. However, it exhibited weak toxicity against larvae of the diamondback moth, Plutella xylostella.     

Relationship between beta-endorphin/beta-lipotropin, hyperglycemia, and hyperinsulinemia in obese male Zucker rats

The relationship between beta-endorphin(beta-EP)/beta-lipotropin(beta-LP) and insulin secretion in the basal state and after glucose challenge was studied in obese male Zucker rats and their lean littermates. Baseline plasma beta-EP/beta-LP concentrations were similar in the two groups of animals. Baseline plasma insulin and serum glucose concentrations were significantly higher in the obese animals. Following glucose challenge, the increase in plasma beta-EP/beta-LP concentrations was significantly lower in the obese animals than in their lean littermates. Opioid blockade with naloxone failed to alter the baseline hyperinsulinemia and hyperglycemia seen in the obese animals. The data suggest that the hyperinsulinemia in the obese Zucker rat is not due to endogenous hyperendorphinemia as shown in humans with polycystic ovary syndrome. The obese rats showed dissociation between glucose-stimulated plasma levels of beta-EP/beta-LP and insulin levels which may contribute to the hyperinsulinemia and insulin resistance in these animals.     

Estimation of absorption efficiency in polychaetes using nitrogen content of food

From 14 values reported for nine species of polychaetes, a highly significant (P < 0.0005) multiple correlation (r = 0.987) between the nitrogen content of food (N) and absorption efficiency (Ae) is observed and is adequately fitted by the polynomial cubic equation: Ae = 11.744−13.353 N+6.510 N²−0.458 N³.     

Restriction/Modification systems and restriction endonucleases are more effective on lactococcal bacteriophages that have emerged recently in the dairy industry

Recently, eight lytic small isometric-headed bacteriophages were isolated from cheese-manufacturing plants throughout North America. The eight phages were different, but all propagated on one strain, Lactococcus lactis NCK203. On the basis of DNA homology, they were classified in the P335 species. Digestion of their genomes in vitro with restriction enzymes resulted in an unusually high number of type II endonuclease sites compared with the more common lytic phages of the 936 (small isometric-headed) and c2 (prolate-headed) species. In vivo, the P335 phages were more sensitive to four distinct lactococcal restriction and modification (R/M) systems than phages belonging to the 936 and c2 species. A significant correlation was found between the number of restriction sites for endonucleases (purified from other bacterial genera) and the relative susceptibility of phages to lactococcal R/M systems. Comparisons among these three phage species indicate that the P335 species may have emerged most recently in the dairy industry.     

Direct detection of lactococcal bacteriophages in cheese whey using DNA probes

Abstract We have designed a new method for the rapid detection of lactococcal phage directly in milk samples. The method was based on a dot blot analysis and did not require a biological assay with sensitive indicator strains. Culture media or whey permeate samples containing phage were spotted directly onto a nylon membrane and the phage were lysed in situ prior to hybridization. For skim milk, whole milk and whey samples, the samples were first treated with 50 mM EDTA, 20% Triton X-100 and heated at 60°C for 5 min, prior to spotting on the membrane. The detection limit was approximately between 10⁵ and 10⁷ pfu/spot. A large number of samples could be processed simultaneously and the results were obtained within 24 h.     

Larval abundance of Chironomus circumdatus in relation to biotic and abiotic factors

Larval abundance of Chironomus circumdatus in sewage canal and pond systems was studied during 1988–1990. Monthly changes in the morphometric features of the pond revealed that both total and littoral areas progressively decreased from 1063 and 107 m² in December 1988 to 151 and 43 m² in May '89; the decrease during the year 1989–1990 was from 1116 and 92 m² in October to 109 and 31 m² in May. A significant negative correlation (r= – 0.52) was obtained for the relation between littoral area and larval density in the pond. Larval density and biomass depended generally on the nature of the substrate and quantity of organic matter. Larval density of Ch. circumdatus was positively correlated with O₂, bacterial count and organic matter content, but negatively correlated with CO₂ level. Daily removal of organic matter by the larvae ranged from 20 to 31 % of the available organic matter in the sewage canal and from 3 to 11 % in the pond.