The effect of dietary administration of Lactococcus lactis MM1 and Enterococcus faecium MM4, two strains of lactic acid bacteria isolated from the gut of juvenile grouper Epinephelus coioides, on the growth, feed utilization, digestive enzymes and immune response of juvenile E. coioides was evaluated. The fish were fed for 60 days with three different diets: control diet (without probiotic), diet P1 supplemented with 1.0 × 108 CFU g?1L. lactis or diet P2 with 1.0 × 108 CFU g?1E. faecium. Although growth and feed intake decreased slightly, significant improvement of feed utilization was observed in fish fed diet P1 and diet P2 for 60 days. The hepatopancreatic protease activities in the two probiotic treatments were significantly higher than that in the control. The phagocytic activity, serum superoxide dismutase activity and complement component 4 (C4) and IgM levels were not significantly affected by diet P1 and diet P2. Serum complement component 3 (C3) levels in the two treatments were significantly higher than that in the control. Significant increased serum lysozyme activity was observed in fish fed the diet P1, while significant decreased lysozyme activity was observed in fish fed the diet P2 compared with the fish fed the control diet. There was a significant interaction effect between diet and administration date for the complement C4. The study demonstrates potential for L. lactis MM1 and E. faecium MM4 to improve the feed utilization and modulate the immune function in E. coioides. 相似文献
The effects of aromatizable 17α-methyltestosterone (MT) and non-aromatizable 17α-methyldihydrotestosterone (MDHT) on sex inversion
in red-spotted grouper, Epinephelus akaara, were investigated. Fish were implanted with MT, MDHT and MT+AI (aromatase inhibitor, AI) respectively for one month. The
results showed that the three treated groups turned into transitional stage with intersex gonads, which contained atretic
oocytes and spermatogenic germ cells at all stages of spermatogenesis. The controls did not change sex. The gonads of more
than half MT-implanted fish were in early transitional stages of sex inversion, whereas those of more than half MDHT and MT+AI-implanted
fish were in late transitional stages of sex inversion. No difference in serum estradiol-17β (E2) levels between the controls and the treated groups were observed, whereas 11-ketotestosterone (11-KT) and testosterone (T)
levels increased in all treated groups. Significantly lower gonadosomatic index (GSI) and gonadal aromatase activity were
observed in the treated groups, which were in accordance with the lower mRNA expression of P450aromA. However, P450aromB mRNA
expression increased in the MT group, while it did not change in the MDHT group. These results suggest that the sex inversion
of red-spotted grouper by MT and MDHT implantation might be due to the suppression of P450aromA gene expression, and resulting
in both the decrease of the ovarian estrogen –secretion, as well as the increase in the 11-KT levels. Furthermore, the main
reason for MT being less effective than MDHT might be due to partial aromatization of MT to estrogen. 相似文献
Regulators of G protein signaling (RGS) are GTPase-activating proteins (GAP) which act as modulators of G protein-coupled receptors. We isolated a RGS16 homologue in yellow grouper (Epinephelus awoara) spleen using suppression subtractive hybridization and RACE-PCR. The nucleotide sequence of yellow grouper RGS16 full-length cDNA was 700 bp and contained an open reading frame of 537 bp, encoding a putative protein of 178 amino acids. The encoded protein shows 47–61% identities to other homologues. RT-PCR analysis demonstrated that RGS16 was expressed in yellow grouper spleen and up-regulated in kidney heart, liver, and anterior kidney by lipopolysaccharide. This study will help towards validating the specific function of RGS in marine fish. 相似文献