A total of 180 Labeo rohita fry (1 g) were distributed into six treatment groups with three replicates each. Six isoenergetic (15.8 kJ g )1 ) diets were prepared with varying levels of protein (CP) and gelatinized carbohydrate (GC), viz. D 1 : 450 g kg )1 CP, 258 g kg )1 GC; D 2 : 400 g kg )1 CP, 302 g kg )1 GC; D 3 : 350 g kg )1 CP, 399 g kg )1 GC; D 4 : 301 g kg )1 CP, 447 g kg )1 GC; D 5 : 249 g kg )1 CP, 517 g kg )1 GC and control diet, D 6 : 400 g kg )1 CP, 468 g kg )1 GC and these were fed to fish at 40 g kg )1 wet body weight per day for 60 days. Highest growth was recorded for fish fed D 4 , decreasing for D 5 . Protein utilization, amylase activity and carbohydrate digestibility were significantly positively correlated with GC (P < 0.05) and were highest in fish fed D 5 . Hypertrophy of hepatic cells was only recorded for D 5 . Lysine, which may be affected during gelatinization, was estimated in diets and found to be above the minimum level required. Survival rate was unaffected by diet. The results of the present study indicate that a diet containing 450 g kg )1 GC and 300 g kg )1 CP was efficiently utilized by L. rohita fry. KEY WORDS

Despite identification of several sex-determining genes in non-mammalian vertebrates, their detailed molecular cascades of sex determination/differentiation are not known. Here, we used a novel RNAi to characterise the molecular mechanism of Dmy (the sex-determining gene of medaka)-mediated masculinity in XY fish. Dmy knockdown (Dmy-KD) suppressed male pathway (Gsdf, Sox9a2, etc.) and favoured female cascade (Rspo1, etc.) in embryonic XY gonads, resulting in a fertile male-to-female sex-reversal. Gsdf, Sox9a2, and Rspo1 directly interacted with Dmy, and co-injection of Gsdf and Sox9a2 re-established masculinity in XY-Dmy-KD transgenics, insinuating that Dmy initiates masculinity by stimulating and suppressing Gsdf/Sox9a2 and Rspo1 expression, respectively. Gonadal expression of Wt1a starts prior to Dmy and didn’t change upon Dmy-KD. Furthermore, Wt1a stimulated the promoter activity of Dmy, suggesting Wt1a as a regulator of Dmy. These findings provide new insights into the role of vertebrate sex-determining genes associated with the molecular interplay between the male and female pathways.

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RNA interference (RNAi) has emerged as a powerful tool to manipulate gene expression in the laboratory. The presence of a double-stranded RNA (dsRNA) in eukaryotic cells triggers this post-transcriptional gene-silencing mechanism, leading to a sequence-specific degradation of the target mRNA. Among its many potential biomedical applications, silencing of viral genes stands out as a promising therapeutic strategy. Marine shrimp viral diseases, especially white spot disease (WSD), represents one of the most attractive targets for the development of therapeutic RNAi owing to its widespread economic impact. This review summarizes the current knowledge in the therapeutic application of RNAi for combating viral diseases in shrimp. The basic principles of RNAi are described, focusing on features important for its therapeutic manipulation. Subsequently, a stepwise strategy for the development of therapeutic RNAi is presented.KEY WORDS: RNAi therapy · Shrimp diseases · Small interfering RNA · siRNA · Long hairpin RNA · lhRNA Resale or republication not permitted without written consent of the publisherDis Aquat Org 86: [263][264][265][266][267][268][269][270][271][272] 2009 exception of MSGS, are classified as OIE notifiable (OIE 2006). Among these, WSSV has had the greatest impact on shrimp farming and is currently considered the most important shrimp disease in terms of distribution and economic losses. Current therapeutic strategiesManaging viral diseases has been the greatest challenge to the shrimp industry because short-term strategies, such as the use of immunostimulants, bioremediators and probiotics, have their own limitations in terms of their efficacy, practicability, cost, and, above all, reproducibility. Unlike finfishes, the shrimps lack a developed adaptive immune system, which is a prerequisite for the development of any protein vaccines. Subunit vaccines (Witteveldt et al. 2004a(Witteveldt et al. ,b, 2006 have been reported to provide some degree of protection to shrimps from viral infection, but their field level potential is yet to be seen. In this scenario, RNAi, which seems to offer great promise in terms of treating human and animal diseases, is looked upon with great hope by shrimp health managers. ENDOGENOUS RNAi PATHWAYObservations were made in plants (Napoli et al. 1990, van der Krol et al. 1990) and nematodes (Lee et al. 1993),which hinted at the existence of the RNAi pathway years before double-stranded RNA (dsRNA) molecules were identified as the key component of this evolutionarily conserved post-transcriptional silencing pathway in eukaryotic cells (Fire et al. 1998). Since then, we have witnessed significant advances in the understanding of how RNAi functions and identified several effective ways to manipulate it in the laboratory. Although a detailed account on the mechanistic aspects of RNAi is beyond the scope of this review and can be found elsewhere (Bartel 2004, Carmell & Hannon 2004, Cullen 2004, Meister & Tuschl 2004, Murchison & Hannon 2004, Du & Zamore 2005, Kim 20...

The elasmobranchs (sharks, rays and skates) being the extant survivors of one of the earliest offshoots of the vertebrate evolutionary tree are good model organisms to study the primitive vertebrate conditions. They play a significant role in maintaining the ecological balance and have high economic value. Due to over-exploitation and illegal fishing worldwide, the elasmobranch stocks are being decimated at an alarming rate. Appropriate management measures are necessary for restoring depleted elasmobranch stocks. One approach for restoring stocks is implementation of conservation measures and these measures can be formulated effectively by knowing the evolutionary relationship among the elasmobranchs. In this study, a total of 30 species were chosen for molecular phylogeny studies using mitochondrial cytochrome c oxidase subunit I, 12S ribosomal RNA gene and nuclear Internal Transcribed Spacer 2. Among different genes, the combined dataset of COI and 12S rRNA resulted in a well resolved tree topology with significant bootstrap/posterior probabilities values. The results supported the reciprocal monophyly of sharks and batoids. Within Galeomorphii, Heterodontiformes (bullhead sharks) formed as a sister group to Lamniformes (mackerel sharks): Orectolobiformes (carpet sharks) and to Carcharhiniformes (ground sharks). Within batoids, the Myliobatiformes formed a monophyly group while Pristiformes (sawfishes) and Rhinobatiformes (guitar fishes) formed a sister group to all other batoids.

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