Population genetics of Indian giant river-catfish, Sperata seenghala (Sykes, 1839) using microsatellite markers

The giant river-catfish Sperata seenghala is one of the commercially important freshwater catfishes of India with wide distribution in all major rivers and reservoirs. This fish has huge demand in domestic market due to high nutritional value and low number of intramuscular bones. Conversely, the culture practices for this fish have not yet been standardized and capture fisheries is the only source to meet the demand. This may lead to over exploitation of resources and subsequent population reduction. Knowledge on genetic structure of populations is prerequisite to formulate sustainable management and conservation measures. In the present study, 15 microsatellites were used to characterize population genetics of S. seenghala collected from river Brahmaputra, Ganga, Godavari, Mahanadi and Narmada. Locus-wise, the number of alleles varied from 8 to 19 with an average of 12 alleles per locus. The mean observed and expected heterozygosity values varied from 0.622 to 0.699 and 0.733 to 0.774, respectively. Several loci have shown deviation from Hardy–Weinberg equilibrium and no significant linkage disequilibrium between pairs of loci was detected. Pair-wise FST values between populations ranged from 0.135 (Brahmaputra–Ganga) to 0.173 (Brahmaputra–Narmada) and confirmed the moderate to high genetic differentiation among the populations. AMOVA, Structure and Principal Co-ordinate analyses showed significant genetic differentiation among the sampled populations of S. seenghala. A total of 65 private alleles were recorded across populations. This study confirmed the distinctiveness of each population of S. seenghala from five major rivers of India. These populations could be treated as distinct management units (MUs) for assessment and management purpose

Acta parasitologica

Not AvailablePolyopisthocotylean monogenean parasites of fishes are highly host specific and have been used as an appropriate model to study the host-parasite co-evolution. In the present study, eight monogeneans of the order Mazocraeidea were characterized by nuclear 28S rDNA sequences and their phylogenetic relationship with other polyopisthocotylean species was investigated. Neighbour- joining, maximum parsimony, maximum likelihood and Bayesian Inference methods were used for phylogenetic reconstruction. The topology sustained by high bootstrap was: (((Hexabothriidae) (Mazocraeidae) (Discocotylidae) (Diplozoidae) (Diclidophoridae) (Plectanocotylidae) (Heteromicrocotylidae) (Microcotylidae) (Heteraxinidae), (Thoracocotylidae), Gotocotylidae (Gastrocoylidae) (Allodiscocotylidae: Protomicrocotylidae))). In addition, we have also developed DNA barcodes (COI sequences) for six species and the barcodes clearly discriminated all the species. The polytomy within Protomicrocotylidae family is resolved in this study for the first time and it appears that within this family, Bilaterocotyloides species are basal compared to Neomicrocotyle and Lethacotyle species while the latter is the more derived

Developmental and Comparative Immunology

Not AvailableMitochondrial antiviral signaling protein (MAVS), an innate immune signaling adapter coordinates the signals received from two independent cytosolic pathogen recognition receptors (RIG-1 and MDA5) to induce antiviral genes. In the present study the MAVS gene of Lates calcarifer (LcMAVS) was cloned and characterized. The complete cDNA sequence of LcMAVS was 3160 bp and encodes a poly peptide of 577 amino acids. Structural analysis of LcMAVS revealed an N-terminal CARD-like domain, central proline-rich domain and a C-terminal transmembrane domain. Phylogenetic analysis indicated that LcMAVS exhibited the closest relationship to P. olivaceous MAVS. LcMAVS was ubiquitously expressed in all tested tissues of healthy fish viz., brain, gill, heart, liver, spleen, kidney and intestine, with highest transcript level in spleen. The mRNA transcript level of LcMAVS in different developmental stages showed constitutive expression in all the stages tested suggesting the maternal transfer of the gene. Significant up regulation in MAVS expression was observed post nervous necrosis virus (NNV) challenge in vivo in all the selected tissues. Further, time course analysis showed that LcMAVS transcripts significantly increased in the brain and spleen tissues after NNV infection. These findings provide useful information for further elucidating the function of LcMAVS in antiviral innate immune response against NNV in Asian seabass

Acute toxicity of copper sulphate on <em>Catla catla</em> larvae and its effect on expression of three commonly used housekeeping genes

12-16Pisces are commonly used to study the effects of metals, including copper on the environment. However, until now only scant information is available about the responses induced by waterborne copper during early life stages and housekeeping gene expression in fishes. In the present study, we evaluated acute toxicity of copper sulphate on larvae of Catla catla and also the stability of expression of three housekeeping genes, beta-actin (β-actin), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and elongation factor 1 alpha (EF1α). The results have shown increased mortality of Catla catla larvae with the increased concentration of copper sulphate. The median lethal concentration (LC50) of copper sulphate at the end of 96 h exposure was 1.032 ppm. During the challenge test of copper sulphate, the minimal coefficient of variation (CV) and stability index were observed for GAPDH and maximum for β-actin indicating minimum variation of GAPDH and maximum variation of β-actin. With the results, it can be concluded that GAPDH is most stable during copper sulphate challenge test on Catla catla larvae, followed by EF1α and β-actin

Population genetics of Indian giant river-catfish,

The giant river-catfish Sperata seenghala is one of the commercially important freshwater catfishes of India with wide distribution in all major rivers and reservoirs. This fish has huge demand in domestic market due to high nutritional value and low number of intramuscular bones. Conversely, the culture practices for this fish have not yet been standardized and capture fisheries is the only source to meet the demand. This may lead to over exploitation of resources and subsequent population reduction. Knowledge on genetic structure of populations is prerequisite to formulate sustainable management and conservation measures. In the present study, 15 microsatellites were used to characterize population genetics of S. seenghala collected from river Brahmaputra, Ganga, Godavari, Mahanadi and Narmada. Locus-wise, the number of alleles varied from 8 to 19 with an average of 12 alleles per locus. The mean observed and expected heterozygosity values varied from 0.622 to 0.699 and 0.733 to 0.774, respectively. Several loci have shown deviation from Hardy–Weinberg equilibrium and no significant linkage disequilibrium between pairs of loci was detected. Pair-wise FST values between populations ranged from 0.135 (Brahmaputra–Ganga) to 0.173 (Brahmaputra–Narmada) and confirmed the moderate to high genetic differentiation among the populations. AMOVA, Structure and Principal Co-ordinate analyses showed significant genetic differentiation among the sampled populations of S. seenghala. A total of 65 private alleles were recorded across populations. This study confirmed the distinctiveness of each population of S. seenghala from five major rivers of India. These populations could be treated as distinct management units (MUs) for assessment and management purpose

Indian Journal of Virology

Not AvailableWhite spot syndrome virus (WSSV) is one of the major pathogens in shrimp aquaculture. Four proteins of WSSV are predicted to encode a RING H2 domain, which in presence of ubiquitin conjugating enzyme (E2) in shrimps can function as viral E3 ligase and modulate the host ubiquitin proteasome pathway. Modulation of host ubiquitin proteasome pathway by viral proteins is implicated in viral pathogenesis. In the present study, expression profile of Penaeus monodon Ubiquitin conjugating enzyme (PmUbc) was studied at protein level in WSSV challenged shrimp. A time point analysis of the expression of PmUbc was carried out at 0, 3, 6, 12, 24, 48 and 72 h post WSSV challenge in P. monodon. Recombinant PmUbc (rPmUbc) was produced in prokaryotic expression vector, BL21 (DE3) pLys S. The PmUbc expression pattern was studied by ELISA with rPmUbc antibodies raised in rabbit. A significant increase in PmUbc expression at 24 h post infection (hpi) was observed followed by a decline till 72 hpi. Since the up-regulation and a tremendous decline of PmUbc protein expression was observed at 24 and in 72 hpi respectively in ELISA, it can be speculated that these proteins might interact with host ubiquitination pathway for viral pathogenesis. Many findings have shown that viral infection can up-regulate expression of ubiquitin and that the ubiquitin system plays a key role in the course of viral infection. The present study reveals the expression patterns of PmUbc at protein level in WSSV infected P. monodon. However, further studies are to be carried out to unfold the molecular mechanism of interaction between host and virus to devise efficient control strategies for this major culprit in shrimp culture industry

International Journal of Experimental Biology

Not AvailableThe decapod crustacean Penaeus monodon survives large fluctuations in salinity through osmoregulation in which Na+/ K+-ATPase (NKA) activity in the gills plays a central role, Adult P. monodon specimens were gradually acclimatized to 5, 25 and 35% salinities and maintained for 20 days to observe long term alterations in NKA expression. Specific NKA activity assayed in gill tissues was found to be 3 folds higher at 5% compared to 25% (isosmotic salinity) and 0.48 folds lower at 35%. The enzyme was immunolocalized in gills using mouse q-5 monoclonal antibody that cross reacts with P. monodon NKA a-subunit. At 5% the immunopositive cells were distributed on lamellar tips and basal lamellar epithelium of the secondary gill filaments and their number was visibly higher. At both 25% and 35% NKA positive cells were observed in the inter-lamellar region but the expression was more pronounced at 25% Gill architecture was normal at all salinities. However, the 1.5 fold increase in NKA a-subunit mRNA at 5% measured by quantitative RT-PCR (QRT-PCR) using EFIa as reference gene was not statistically significant. The study confirms the osmoregulating ability of P. monodon like other crustaceans at lower salinities. It is likely that significant increase in NKA transcript level happens at an earlier time point. At higher salinities all three methods record only marginal or no change from isosmotic controls confirming the hypothesis that the animal largely osmoconforms in hyperosmotic environment

Not Available

Not AvailableMorphotypic differentiation is the external manifestation of dominance hierarchy inMacrobrachiumrosenbergii. The intermediate morphotype orange claw (OC) male exhibits the highest growth rate and is subordinate in hierarchy to blue claw (BC) male while dominant on small male (SM). The present study was undertaken to examine the specific role of insulin-like androgenic gland (iag) hormone in morphotype differentiation of M. rosenbergii. To achieve this, RNAi mediated knockdown as well as augmentation of iag transcripts were effected in ∼60 g OC males using plasmid-based constructs pcD-IAGlh and pcD-IAGorf, respectively. The treatments were administered to animals maintained in isolation as well as in community. The knockdown plasmid construct that expresses iag-specific long hairpin RNA caused 16-fold reduction of iag transcripts in the SSN1 cell line in vitro. When injected into OC males living in a community, 2.3-fold iag knockdown was recorded, while in isolated OC males it was 4.2-fold initially, but returned to normal subsequently. Compared with the respective controls, OC to BC transformations in the iag silenced animals were significantly lower in the community-reared group, while no difference was observed in the isolated animals. It is reported here for the first time that iag augmentation in OC males resulted in significantly higher OC to BC transformations, when animals were reared in community. This plasmid-based IAG knockdown approach could be developed into a low stress, feed or immersion treatment for controlling heterogeneous individual growth of M. rosenbergii males in aquaculture.Not Availabl