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Articles by P.S. Lyla
Total Records ( 11 ) for P.S. Lyla
  Eldose P. Mani , B. Ravikumar , P.J. Antony , P.S. Lyla and S. Ajmal Khan
  As part of the environmental impact assessment studies of brackish water aquaculture, the effect of benthic disturbance caused by manual removal of overlying sediment near to the suction sump of an aquaculture pond was studied in the Vellar estuary. The abundance and vertical distribution of meiofauna before and after disturbance were compared. Sediment core and water samples from the pre-and post-disturbance stages were analyzed for meiofaunal abundance, TOC, texture, porosity and physicochemical parameters. Immediately after one day of the benthic disturbance, a drastic decrease in meiofaunal numbers was observed, indicating the deleterious effect of disturbance. On the other hand considerable increase in TOC and meiofaunal numbers from the adjacent sites was observed vouching for the positive impact of such disturbances.
  S. Ajmal Khan , P.S. Lyla , B. Akbar John , C. Prasanna Kuamr , S. Murugan and K.C.A. Jalal
  Three teleost fishes, Stolephorus indicus, Stolephorus commersonnii and Terapon jarbua occurring in Parangipettai waters, were barcoded (sequenced) for 648 bp region of the mitochondrial cytochrome oxidase subunit I gene (COI) for phylogenetic analysis. All the possible barcode sequences of these three fishes were also extracted via FASTA format from NCBI (National Centre for Biotechnological Information). The genetic distances within the species was small compared to the genetic distances between the species i.e., the genetic distances within S. indicus was 7.67% and the average genetic distance between S. indicus and S. commersonnii was 9.11%. The genetic distance between the families Engraulidae and Terapontidae was 26.48% which was found higher than the genetic distance calculated within the family of Engraulidae (9.11%). This clearly showed that when organisms from distantly placed families are taken, the genetic distance increases. In the present study some phylogeographical signal was apparent in the data. In the neighbor-joining tree for all 10 sequences, two major groups were apparent: clade A comprising of Terapon jarbua and clade B comprising of Stolephorus species. The grouping pattern of clade A showed some phylogeographical signals. The barcode sequence of Lates calcarifer shuffled within other sequences during phylogram constructions was unambiguously placed as an out group in the phylogram. The clades after bootstrapping corresponded well with the expectations. We conclude that precise and accurate identification of Stolephorus indicus, S.commersonnii and Terapon jarbua could be performed using the barcode sequences of the mitochondrial DNA (in the COI gene) of these fishes.
  C.P. Kumar , B.A. John , S.A. Khan , P.S. Lyla and A.S. Kamaleson
  Recent emergence of Chikungunya virus has attracted the researchers to explore its whole genome to predict the structural changes at the genetic level during disease outbreak. Present study was aimed to investigate the mutational patterns at the genome level in Chikungunya virus using advanced software programs. Pair-wise analysis of whole genome (n = 84) of Chikungunya virus revealed that structural genes mutated 2.6 times higher than non-structural genes. The chronological analysis showed that the Chikungunya virus prevalent during 2008 mutated higher than any other outbreaks recorded so far. Number of singleton sites in the variable region of viral genome was found higher when compared to number of parsimonous sites. Chronological and geographical scale analysis of the viral outbreak showed that about 30% of viral genome was subjected to mutation so far. Chikungunya virus isolated from Malaysian geography had underwent more mutations when compared anyother geographical locations. Highest number of singleton mutations were observed in Chikungunya viruses isolated from Malayasian geography whereas highest number of parsimonous informative sites were observed in Chikungunya isolates of India. The mutational analysis also revealed that viral genome contained two times more singleton sites compared to parsimonious sites. About 1207 nucleotides in the structural protein coding region of Chikungunya virus genome was identified as a unique DNA signature witch could be used in precise and fast diagnosing of Chikungunya virus in future.
  C. Prasanna Kumar , B. Akbar John , S. Ajmal Khan , P.S. Lyla , B.Y. Kamaruzzaman and K.C.A. Jalal
  Cultivable marine bacteria associated with the sponge Hyattella cribriformis (Hyatt, 1877) was studied through 16S rRNA gene sequencing. These marine bacterial colonies produced on Zobell Marine agar plates were distinguished based on phenotypic characters viz., colony morphology and pigmentations of the individual colonies. The extracted DNA from the individual bacterial isolates was PCR amplified using universal 16S primers and subjected to DNA sequencing. BLAST (Basic Local Alignment Tool) analysis finds that Vibrio diazotrophicus, Bacillus subtilis, B. firmus, Thalassomonas agarivorans, Oleiphilus messinensis, Planococcus maritimus and Brevundimonas vesicularis are the culturable marine bacteria associated with the sponge Hyattella cribriformis. The phylogram constructed clearly delineated the bacterial isolates into its corresponding phylum. The cultivable bacterial density of Hyattella cribriformis was found to be 65x10-5 CFU mL-1. Submitted sequences in NCBI were assigned with accession numbers (FJ834327, FJ834328, FJ834329, FJ845392, FJ845393, FJ845394 and FJ845395). It could be concluded that, application of 16S rRNA sequencing approach would yield novel insights into the diversity of bacteria associated with sponges and hence would help in exploring the commercial importance and their industrial applications.
  S. Murugan , S. Ajmal Khan , P.S. Lyla , C. Prasanna Kumar , K.C.A. Jalal , B.Y. Kamaruzzaman and B. Akbar John
  A detailed study on the length weight relationship of Mugil cephalus in Vellar estuary was conducted between January 2004 and December 2005. Statistical tests such as regression coefficient ‘b’ and ‘a’ tests were performed to compare the b values of males and females from the hypothetical value of 3. The b value of male (2.7658) differed significantly from the hypothetical value of 3 (t = -2.8586<0.05), the b value of female (2.8586) did not differ significantly from the hypothetical value (t = -1.0158>0.05). Values of both males and females were less than 3 which proved the negative allometry growth pattern.
  M. Ashiq Ur Rahman , S. Ajmal Khan , P.S. Lyla , K. Kadharsha , P. Mohan Chander and B. Akbar John
  Determination of Length-weight Relationship (LWR) of any commercially important fish is crucial to validate the wild stock level, to predict their wellbeing in the natural habitat and for various sustainable fishery management practices. Liza subviridis (Valenciennes) is noted to be highly abundant along the coast of Parangipettai, South east coast of India. Hence, the present study was aimed to establish Length-weight relationship and condition factor of Greenback mullet, Liza subviridis (Valenciennes) occurring in Vellar estuary, Parangipettai (lat. 11°30' N, long. 79°46' E) using least square method. To determine the actual relationship between length and weight of L. subviridis exponent coefficient or equilibrium constant (b) and relative condition factor (Kn) analysis were adopted. The females were found to be heavier than males at similar length. The equilibrium constant ‘b’ was found to be 2.7106 in males and 2.8927 in females. The corresponding parabolic representation for male was W = 0.0462L2.7106 and for female W = 0.0382L2.8927. The equilibrium constant did not obey the cube law as it deviated significantly from 3 in the case of males. The relative condition factor around 1 and little over it revealed the well-being of L. subviridis in Parangipettai waters.
  K. Kadharsha , P. Mohanchander , P.S. Lyla and S.A. Khan
  The feeding biology, spawning season, size at first maturity, sex ratio and fecundity of the commercially important lizardfish (Saurida undosquamis) were studied in Parangipettai waters of the southeast coast of India. Fishes formed the predominant food item. Diversity of the prey items showed maximum value (H’log 2-3.61±0.11) during the postmonsoon season and minimum during the monsoon season (2.89±0.17). The richness (1-lambda’) also showed a similar trend and varied from 0.81±0.13 (monsoon) to 0.91±0.01 (postmonsoon). The size at first maturity (50% incidence of mature fish) was 195 mm. But when the size at first maturity was calculated by adjusting the proportion of maturity percentages, the maturity size was found to be 140 mm. This method is advantageous from the point of view of fisheries management as this species can be exploited above 140 mm rather than above 195 mm. The gastrosomatic index was found maximum during postmonsoon and minimum during the monsoon season showing the inverse relationship between feeding and spawning. This species was found to spawn from August to January with a peak in November. The fecundity ranged from 19, 856 in a fish measuring from 20.1 cm in length (97 g) to 79,282 in a fish of 29 cm (290 g). The overall sex ratio (1:1.19) was found to deviate significantly from the expected 1:1 ratio. (χ2 = 19.1, p<0.005). Month- wise, it conformed to the expected 1:1 ratio during most of the months except January, June, September, November and December. Higher gonado-somatic index values observed during October-December suggested spawning activity during this period. This species is found to a total spawner in the Parangipettai waters.
  S. Raja , S. Ajmal Khan , P.S. Lyla and S. Manokaran
  The present study was undertaken to study the benthic productivity of shelf region off Krishna River mouth. Standing stock of macrobenthos and its distribution were studied. Sampling was done onboard FORV Sagar Sampada from depths as 30, 50, 75, 100, 150 and 200 m using Smith-McIntyre grab having a bite area of 0.2 m2. After identification, data were treated using statistical package PRIMER v6. The nature of the sediment was medium sand up to 150 m depth and fine silt at 200 m. The benthic biomass (0.2977-3.1091 mg 0.2 m-2), abundance (58-289 nos. 0.2 m-2 and number of species (12-48) decreased with increase in depth. The total number of species recorded was 69. Species estimators showed the possibility of collecting 129 species (Chao1) with intense sampling. Polychaetes formed the largest group with 40 species followed by molluscs (15 species) and crustaceans (14 species). The Spearman rank correlation (Rho) value (0.513) which was significant at 1.1% showed gradual change in species composition with increase in depth. The Pi value (3.78) comparing the similarity of benthos at 200 m depth with those of other depths (30, 150, 100, 75 and 50 m) showed significant differences (0.6%). Matching of biotic variables with that of environment showed the influence of dissolved oxygen on the distribution of macrobenthos (Rho 0.757). Intense sampling should be done to record all the species as shown by species estimators besides studying shelf productivity off other rivers and relating it with nutrient discharge and other environmental factors including sediment nature.
  Akbar John , C. Prasannakuma , P.S. Lyla , S. Ajmal Khan and K.C.A. Jalal
  An effort to assess the utility of 650 bp Cytochrome oxidase subunit I (DNA barcode) gene in delineating the members closely resembled marine fin fishes belonging to the family Latidae was made. To address the issue, all 40 barcode sequences of fishes belonging to Latidae family available at NCBI (National Centre for Biotechnological Information) along with the barcode data generated from commonly available fish Asian sea bass (Lates calcarifer) from Parangipettai coastal waters was used. The average GC content of selected three fishes belongs to Latidae was found to be 48.87%. Lates niloticus from Tanzanian waters showed less GC content (47.70%) whereas L. calcarifer from South China sea showed high GC content (49.61%) among the Latidae species studied. Compare to Australian, Indian and Singapore (48.1-48.89%) water L. calcarifer, Myanmar and South China species shows high average GC content (49.38-49.41%). The phylogenetic and genetic distance data showed that the maximum genetic distance is present in 3rd codon position in all the selected species. It is apparent from the genetic distance that the GD between L. calcarifer and L. niloticus was observed to be higher than the GD between P. waigiensis and L. niloticus in all the codon positions. The expected clustering of the species in separate internal branches was well observed in the constructed phylogram with high bootstraps. We conclude that COI sequencing (barcoding) in identifying the morphologically similar species of the family Latidae.
  Sourav Kundu , Surajit Das , Nityananda Mondal , P.S. Lyla and S. Ajmal Khan
  Halophilic actinomycetes Actinopolyspora sp. was evaluated for osmolyte production. Different concentrations of NaCl were used in the medium for osmolyte synthesis and the growth started declining from 28th day onwards. Poor growth was noticed in the medium containing 15 and 25% NaCl concentrations. At 20% NaCl concentration, protein content of the strain was higher (14 µg mLG-1) on the 20th day and most of the halophilic proteins have been recorded to be higher in content during the late exponential period. SDS-PAGE profile showed a distinct band of protein with a molecular weight 92 kDa on 20% NaCl concentration.
  C. Prasanna Kumar , B. Akbar John , S. Ajmal Khan , P.S. Lyla , S. Murugan , M. Rozihan and K.C.A. Jalal
  An effort was made to assess the utility of 650 bp partial Cytochrome C oxidase subunit I (DNA barcode) gene in delineating the members of taxonomically ambiguous marine fin fishes (Family: Mugilidae). To address the issue we used all the 95 barcode sequences of Mugilidae family available at NCBI (National Centre for Biotechnological Information) along with the barcode data generated from Mugilidae fishes of Parangipettai coastal waters. The average GC content of Mugilidae was found to be 46.46%. Crenimugil crenilabis showed less GC content (44.55%) whereas Liza macrolepis showed high GC content (48.53%) among the mullet species studied. The phylogenetic and genetic distance data showed that Mugil platanus and M. liza represent the continuum of same species. Among the members of family Mugilidae, the genus Mugil might possibly contains more haplotype diversity as revealed by intra-species genetic distance data. Species within genera of Mugilidae family invariably clustered in single clade with high bootstrap value. We conclude that partial COI sequencing (barcoding) in identifying the members of the family and that way has resolved the taxonomic ambiguity among the members of the family Mugilidae.
 
 
 
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