Deepak Jose

Identification of Diploid and Triploid Red Tilapia by Using Erythrocyte Indices

Abstract The individuals of diploid and triploid red tilapia Oreochromis mossambicus (Peters, 1852) X Oreochromis niloticus (Linnaeus, 1758) were identified by using erythrocyte indices. The major cell and minor cell axis of the erythrocyte were 27.7 and 11.5%, respectively higher in triploids as compared to diploid fishes. The increase in nucleus size of the erythrocytes of triploid was also greater by 31.7% for the major axis and 17.2% for the minor axis with respect to the erythrocytes of diploid fishes. Similarly the increase in nucleus cell surface and volume of the nucleus were also higher by 50.4 and 68.5%, respectively in the triploid fishes as compared to the diploids fishes. Moreover the erythrocyte cell surface area and cell volume of triploids were higher by 42% and 59% respectively to diploid ones. The cytoplasmic volume of erythrocyte cell was also increased by 57.9% in the triploids fishes with respect to diploid individuals. The present study clearly showed that the nuclear volume, cytoplasmic volume and nucleus surface area of the erythrocytes are significantly greater (p < 0.005) in the triploids as compared to the diploid fishes. These parameters thus can successfully be used in discriminating diploid and triploid red tilapia.

Triploidy induction by heat-shock treatment in red tilapia

The possible use of sterile triploid red tilapia is an interesting option for culture due to their proliferating breeding activities. The aim of the present study was to investigate and optimize the time of heat-shock treatment to prevent second polar body extrusion from the newly fertilized eggs of red tilapia, to produce a maximum number of triploid individuals. Heat-shock treatment was applied at a temperature of 41°C for a total duration of 3.5 minutes after 2, 3, 4, 4.5, 5 and 6 minutes of fertilization. The best survival rate (67.0%) and triploid percentage (89.7%) was observed for the treatment at 4 minutes after fertilization. It is thus successfully demonstrated that 4 minutes after fertilization was the most suitable timing of heat-shock treatment for second polar body retention in newly fertilized eggs of red tilapia.

Non-homologous COI barcode regions: a serious concern in decapod molecular taxonomy

Abstract Biodiversity is well defined with the assistance of taxonomy, the science which classifies organisms with “species” as the basic unit. Presently, in taxonomy, morphological type specimen is complimented with its molecular data from “type” gene sequences and species status is granted. For this, DNA barcoding using standardized DNA gene(s) is performed in which Cytochrome c oxidase I gene of mitochondrial DNA is referred as the primary barcode region for animal kingdom. Being a popular mitochondrial marker, this gene is reported to possess two barcode regions with limited overlap, “Folmer” and “Palumbi” regions particularly in decapod crustaceans. Here we demonstrate the issues originated as a result of incorporation of both these barcode regions together in addressing various aspects of DNA barcoding like specimen identification, population analysis, and phylogeny in decapod crustaceans using COI sequences (“Folmer” and “Palumbi”) of Macrobrachium rosenbergii as reference sequences.

A molecular approach towards the taxonomy of fresh water prawns Macrobrachium striatum and M. equidens (Decapoda, Palaemonidae) using mitochondrial markers.

Abstract Genus Macrobrachium includes freshwater prawns which inhabit most diverse habitats ranging from low saline areas to inland hill streams and impounded water bodies. Being morphologically conserved, this genus has been exposed to severe disputes related to their taxonomy, systematics and phylogeny. Macrobrachium striatum and M. equidens represent two morphologically related congeneric species within this genus. Earlier, M. striatum was considered as a striped form of M. equidens. Though these species are now well-described morphologically and differentiated into two species, no molecular level investigation has been carried out in support of their speciation. We report a study on M. striatum and M. equidens with emphasis to their molecular data through mitochondrial markers (16S ribosomal RNA and cytochrome oxidase subunit I). Results obtained from developed molecular markers of the two species revealed considerable genetic differentiation between them. Phylogram generated using Minimum evolution and Neighbour joining analyses differentiated M. striatum and M. equidens as two independent species. Genetic distance data showed high interspecific divergence (ranging from 3.9% to 17.0% for 16S rRNA sequences and 13.8% to 21.0% for COI sequences) between M. striatum and M. equidens confirming the findings of phylogram. Hence, it could be delineated that M. striatum and M. equidens represent two distinct species within genus Macrobrachium with emphasis to their morphology and genetics.

Evolutionary history of genus Macrobrachium inferred from mitochondrial markers: a molecular clock approach

Abstract Caridea, an infraorder of shrimps coming under Pleocyemata was first reported from the oceans before 417 million years followed by their radiation recorded during the Permian period. Hitherto, about 3877 extant caridean species were accounted within which one quarter constitute freshwater species. Freshwater prawns of genus Macrobrachium (Infraorder Caridea; Family Palaemonidae), with more than 240 species are inhabitants of diverse aquatic habitats like coastal lagoons, lakes, tropical streams, ponds and rivers. Previous studies on Macrobrachium relied on the highly variable morphological characters which were insufficient for accurate diagnosis of natural species groups. Present study focuses on the utility of molecular markers (viz. COI and 16S rRNA) for resolving the evolutionary history of genus Macrobrachium using a combination of phylogeny and timescale components. It is for the first time a molecular clock approach had been carried out towards genus Macrobrachium in a broad aspect with the incorporation of congeners inhabiting diverse geographical realms including endemic species M. striatum from South West coast of India. Molecular results obtained revealed the phylogenetic relationships between congeners of genus Macrobrachium at intra/inter-continental level along with the corresponding evolutionary time estimates.

Re-description of Lysirude channeri (Decapoda Crustacea: Raninidae) from Bay of Bengal, Indian Ocean

Frog crabs (Family Raninidae) are cryptic, burying marine brachyuran crabs adapted for inhabiting soft and sandy bottoms across a wide bathymetric range of tropical to low-latitude temperate regions. The present account encompasses re-description of Lysirude channeri from a depth range of 614–655 m in Bay of Bengal, India. Morphological examination of 76 specimens agreed with earlier type descriptions in having two antero-lateral spines, but this contradicts with the specimens from the South China Sea and off the Philippines. In addition, some specimens from the present study revealed the presence of two carpal spines instead of one described before. However, the genetic congruency of the collected specimens were inferred by developing molecular marker viz. mitochondrial cytochrome oxidase subunit I (mtCOI) gene sequences, representing the first molecular data for Lysirude channeri . Phylogram and genetic distance data (up to 0.60%) justified the genetic congruency of Lysirude channeri as well as the interspecific divergence (up to 15.2%) between Lysirude channeri and Lyreidus brevifrons . Hence, the present study provides complete morphological and molecular data for re-describing the frog crab Lysirude channeri and also delineates its speciation from other related brachyuran crabs.

Reproductive traits of deep-sea armoured shrimp, Glyphocrangon investigatoris from Bay of Bengal, Indian Ocean

Details on size at first maturity, embryo number and size, brood chamber volume and reproductive output of deep-sea armoured shrimp, Glyphocrangon investigatoris caught off the south-east coast of India by using EXPO trawl from 633 m depth in FORV ‘Sagar Sampada’ are reported here. Eighty-four female shrimps ranging from 17.29–36.31 mm carapace length and 2.28–16.54 g weight formed 7.73% of total catch, 30% of which was constituted by embryo-bearing females. Regression of weight on carapace length revealed negatively allometric growth (r 2 = 0.85, P

Morphological and molecular description for Glyphocrangon investigatoris Wood-Mason & Alcock, 1891 emphasizing its phylogenetic relationship

Abstract Genus Glyphocrangon, the only representative of Family Glyphocrangonidae, comprises about 89 species. According to previous records, this species is known to inhabit a depth range of 145–410 fathoms in Bay of Bengal. A thorough scrutiny of literature revealed a detailed morphological description of G. investigatoris and little molecular database. As part of an exploratory research survey conducted in Bay of Bengal, specimens of this species were collected from trawl catches off Paradeep, Orissa. In our present study, an attempt was made to develop its DNA barcode based on mitochondrial Cytochrome oxidase subunit I (mtCOI) and to establish its phylogenetic relationship with other species of genus Glyphocrangon. The developed mtCOI sequences of G. investigatoris exhibited its genetic identity favoring its morphological description.