Indian Journal of Geo-Marine Sciences Vol. 45(9), September 2016, pp. 1110-1115

Molecular and cytogenetic description of four marine fish from Indian coast

Basdeo Kushwaha1*, Ravindra Kumar1, Akhilesh Kumar Mishra1, N S Nagpure1, V S Basheer2 & M K Anil3 1Molecular Biology and Biotechnology Division, National Bureau of Fish Genetic Resources Canal Ring Road, PO: Dilkusha, Lucknow-226 002, India 2Cochin Unit of National Bureau of Fish Genetic Resources CMFRI Campus, Post Box No. 1603, PO- Ernakulam North, Kochi – 682 018, India 3Vizhinjam Research Centre of CMFRI, Post Box No. 9, PO: Vizhinjam, Thiruvananthapuram-692 521, India *[E-mail: [email protected]]

Received 10 December 2013; revised 25 February 2014

In the present study, cytogenetic and molecular characterization of four ornamental marine fish species, namely Chaetodon collare, gibbosus, Scarus ghobban and Siganus canaliculatus inhabiting Arabian Sea, were carried out. Karyotype analyses of these species revealed diploid chromosome number 48 with all acrocentric, except in S. ghobban having karyotypic formula of 10m+4sm+12st+22t. Chromosomal configuration of C. collare, P. gibbosus and S. canaliculatus indicated more or less similar genetic makeup among them, than that of S. ghobban. Analyses of ITS 2 region in these species indicated phylogenetic closeness of P. gibbosus with S. ghobban and C. collare with S. canaliculatus with an average evolutionary divergence of 6.8% among them.

[Keywords: Characterization; Cytogenetics; ITS 2; Marine fishes, Molecular]

Introduction Marine fish Chaetodon collare, Plectorhinchus The marine ornament fish trade, started in Sri gibbosus, Scarus ghobban and Siganus canaliculatus Lanka in the 1930s, has spread over in more than 45 are some of the important ornamental species countries from the tropical Pacific, Indian and commonly occurring in Indian western coasts. P. Atlantic Ocean. This sector has grown up as multi- gibbosus, commonly known as dog faced sweetlips, billion dollar industry. Indonesia and Philippines are belongs to family: and order: the leading suppliers, whereas some other countries . The body colour and stripes, which like Brazil, Maldives, Vietnam, Sri Lanka, Hawaii changes throughout their lives, make it ornamentally and India are also contributing significantly. It is important. They are generally found in groups or in estimated that more than 1,400 fish species globally pairs in coral reefs. Adults grow to a maximum are part of marine ornamental fish trade1. In India, length of 45 cm (Fig. 1A). The C. collare, commonly more than 300 fish species belonging to around 35 known as Redtail-butterfly fish, belongs to family: families are known for their attractive colors and Chaetodontidae and order: Paciformes. Colour is shapes. The wrasses (Labridae), constitute the largest brown to black, with lighter scales giving it a spotted group with 45 species followed by damsel fishes appearance. It has characteristics of vertical white (Pomacentridae; 35 species), cardinal fishes streak behind the eyes, a dark stripe over the eyes, (Apogonidae; 22 species), groupers (Serranidae; 21 and smaller white stripe in front of the eyes. Base of species), blennies (Blennidae; 20 species), surgeons the tail being bright red, followed by a black stripe or unicorn (Acanthuridae; 19 species), butterfly fish and diffused white tip make it attractive (Fig. 1B). S. (Chaetodontidae; 16 species), goat fish (Mullidae; 14 ghobban, popular as the Blue-barred parrotfish, species), gobies (Gobiidae; 14 species), scorpion fish belongs to family: Scaridae and order: Paciformes. It (Scorpaenidae; 14 species), trigger fish (Balistidae; looks very attractive due to bluish appearance of fin 10 species), squirrel fish (Holocentridae; 9 species) margins and body surface (Fig. 1C). Parrotfishes have and others fishes2. characteristic pharyngeal dentition which helps in scraping into algal covered limestone. S. KHUSHWAHA et al.: MOLECULAR AND CYTOGENETIC DESCRIPTION OF FOUR MARINE FISH SPECIES 1111

canaliculatus (order: Perciformes; family: Siganidae), were collected from the areas nearby Vizhinjam in commonly known as white-spotted spinefoot with Kerala. The average wet weight of the specimens nostrils resembling to rabbit’s nose, is very much were 51.6 g (range 50-53 g), 32.8 g (range 20-50 g), amusing (Fig. 1D). Its body is silvery grey above and 52.8 g (range 48-58 g) and 32.5 g (range 30-35 g), is generally found near the vicinity of river mouth, respectively. Specimens were in juvenile stage and especially around sea grass beds in groups of about the sex was unidentifiable by visual examination. 20 individuals. The specimens were injected 0.05% colchicine intramuscularly @ 1 ml/ 100 g body weight and the anterior kidney was dissected out after 2 h of injection for metaphase chromosome preparation using conventional hypotonic treatment – fixation (methanol: acetic acid) – flame drying technique. Metaphase chromosomes were stained with 6% Giemsa in phosphate buffer (pH 6.8). Approximately, 200 chromosome complements were analyzed for establishing the diploid chromosome number (2n) and characteristic chromosome morphology in each species. Homologous chromosomes were paired based on their morphology and centromeric position Fig. 1: Images of voucher specimens: P. gibbosus (A), C. collare (B), S. ghobban (C) and S. canaliculatus (D). and arranged in decreasing order of their size using Lieca CW4000Karyo software. Karyotypes were Developing species-specific taxonomic markers prepared from the cells exhibiting the complete for ornamental fish species is a pre-requisite for this chromosome complement and characteristic morphology using the classification proposed by trade as it helps the stakeholders in verifying the 4 identity and purity of the species for culture in Levan et al. . captivity and conservation purposes. Now-a-days, the Total genomic DNA was extracted from ethanol characterization and cataloguing of fish fauna using preserved muscle/ blood samples of the subject suitable tools has colossal importance for species following the protocol of Ruzzante et al.5 safeguarding the intellectual property rights. with minor modifications ( i.e. tissue incubated in Although, India has rich diversity of ichthyofauna, incubation buffer at 37°C overnight instead of 45°C but merely around 42 species from marine for 15 min). DNA quality and quantity were ecosystems have cytogenetically been characterized3. determined by agarose gel electrophoresis and UV Cytogenetic as well as DNA sequence information spectrophotometer. Amplification of ITS 2 region are very helpful in resolving taxonomic ambiguities was carried out in a 50-µl reaction mixture, among the species, unfolding genetic identity of the containing 100 ng template DNA, 10X buffer (Tris organisms as well as in evolutionary and with 15 mM MgCl2), 10 mM dNTPs mix (2.5 mM of phylogenetic studies. Internal transcribed spacer 2 each dNTPs), 25 mM of MgCl2, 10 pmoles of each (ITS 2) of nuclear rDNA cistron is regarded as one of primers (ITS 2 F1: the candidate DNA barcode due to availability of GCAGGACACATTGATCATCGACAC and ITS 2 conserved regions and sufficient variability to R1: GGCTCTTCCCTCTTCGCT CGC), 2U Taq distinguish even closely related species. The present DNA polymerase (Chromous, India). PCR was study comprised characterization of P. gibbosus, C. performed in Eppendorf Thermal Cycler (Master collare, S. ghobban and S. canaliculatus with a view Cycler Gradient), with initial denaturation at 95ºC for to document their chromosomal as well as molecular 4 min followed by 32 cycles of denaturation at 94ºC diversity and evolutionary relationship. for 45 sec, annealing at 55ºC for 30 sec, elongation at 72ºC for 45 sec, with a final extension at 72ºC for 10 Materials and Methods min. Product was checked on agarose gel and Live specimens of C. collare (n=6), P. gibbosus sequenced using custom service. (n=6), S. ghobban (n=6) and S. canaliculatus (n=6) 1112 INDIAN J. MAR. SCI., VOL. 45, NO.9 SEPTEMBER 2016

Table 1: Details of sequences among the species studied.

Species Sequence length (bp) GC% NCBI Acc. No.

P. gibbosus 613 69.1 JQ766314

C. collare 588 68.2 JQ814470

S. ghobban 504 63.3 JX499020

S. canaliculatus 685 59.3 JX499021

R. rita 670 60.2 KC009840

phylogram grouping of P. gibbosus and S. ghobban in The forward and reverse sequences were aligned one cluster, while S. canaliculatus was placed with C. using online ClustalW software. Consensus collare in another cluster (Fig. 4) with good bootstrap sequences were submitted to the GenBank (Table 1). values (60 and 88, respectively) using 1000 Sequence analyses were carried out using MEGA 5.06 replications. Minimum evolutionary divergence (i.e. and DnaSP v57 softwares. ITS 2 sequence of Rita rita, 0.530±0.05) was found between sequences of P. retrieved from GenBank (Acc. No. KC009840) was gibbosus and S. ghobban, while maximum (i.e. used as out-group. 1.256±0.14) was found between S. canaliculatus and R. rita. Results In all the four studied species, the 2n was found to be Discussion 48 with all telocentric chromosomes (karyotype The presence of 2n= 48 in the undertaken species was in accordance with those observed in majority of formula, KF = 48t; Fig. 2A, B, D), except in S. 9,10,11 ghobban having KF = 10m+4sm+12st+22t (Fig. 2C). marine fish species from India . Occurrence of all 48 telocentric chromosomes seems to be a Consensus DNA sequences of P. gibbosus (613 bp), 12 C. collare (588 bp), S. canaliculatus (685 bp) and S. characteristic of majority of marine species . Among ghobban (504 bp) containing partial 5.8S, complete the Indian non-native fishes, approximately 60% of ITS 2 and partial 28S ribosomal gene regions were the perciform species, studied so far have shown to contain a karyotype characterized by 48 uni-armed obtained. Small and highly conserved 5.8S and the 13 small portion of the 28S gene regions were easy to (telocentric) chromosomes and this all uni-armed condition has been considered as primitive character align across the taxa along with the hyper variable 14,15 ITS 2 region to delineate marine fish species from the in marine fishes . Hence, in the present study, C. out-group R. rita. The sequences were found to collare, P. gibbosus and S. canaliculatus with uni- contain higher GC content with an average value of armed chromosomes may be considered primitive in 64.2%. Analysis of evolutionary relationship among evolution as compare to the S. ghobban having bi- the species based on ITS 2 sequences identified 581 armed chromosomes. collective aligning sites, and out of this 215 (37.0%) Sequence of ITS 2 region of nuclear rDNA evolves sites were found to be polymorphic and rest as comparably faster; hence, suitable for distinguishing conserved. A total number of 45 insertion-deletion even very closely related species. The success rates of (indel) events having average length of 3.3 using ITS 2 region to identify dicotyledons, nucleotides were found, excluding overlapping indel monocotyledons, gymnosperms, ferns, mosses and at the species level were found to be 76.1, events in sequences of all the species when aligned 16 together. 74.2, 67.1, 88.1, 77.4 and 91.7%, respectively . The maximum likelihood (ML) tree8 revealed

KHUSHWAHA et al.: MOLECULAR AND CYTOGENETIC DESCRIPTION OF FOUR MARINE FISH SPECIES 1113

A B

C D

Fig. 2: Geimsa stained karyotypes of: P. gibbosus (A), C. collare (B), S. ghobban (C) and S. canaliculatus (D).

Furthermore, structural feature of ITS 2 allows before assessing their taxonomical status. Karyotypic distinguishing different species from each other17. studies supplemented with nucleotide sequence Highly variable nature of ITS 2 region has been information of ITS 2 region could be more useful in attributed to the presence of a number of indels in the resolving taxonomic ambiguities among closely sequences, which perhaps is the real power of ITS 2 related fish species and it can also throw light on sequences to differentiate among the species as karyo-evolution and speciation of the marine fish evident in the present study. A high GC (%) content species. Cytogenetic markers have been found useful ranging from 59.3 (S. canaliculatus) to 69.1 (P. for identification of intra-specific stocks and gibbosus) (Table 1) ensures overall stability of the populations in some fish species18, and when ready sequences and, thus, robustness of the marker. with sequence information like that of ITS 2 region, In traditional , all the studied species they can identify suspected hybrids between closely (except out-group) belong to the order perciformes, related species. The information on the cytogenetic and separation on molecular basis is an indicative of markers can again be used for molecular cytogenetic their further evolution. Evolutionary divergence assignment of genes on chromosomes19. between sequences is essentially the transitional to In the present study, we provide the karyo- transversional distances per site between sequences morphological descriptions of the studied marine fish and is the rationale behind these species to have species as well as molecular evidence for their emerged as distinct species during the course of identification by means of ITS 2 sequences for the evolution. This work provides basis for future studies first time to document their identity and support using some other nuclear and mitochondrial genes to future studies on systematic relationships among validate the relatedness among these species 1114 INDIAN J. MAR. SCI., VOL. 45, NO.9 SEPTEMBER 2016

Fig. 3: ITS 2 sequence alignment among P. gibbosus, C. collare, S. ghobban, S. canaliculatus and R. rita (dots showing similarity in bases).

Fig. 4: Phylogenetic tree constructed by Maximum Likelihood using complete ITS2 sequences in the subject species taking R. rita as an out-group.

KHUSHWAHA et al.: MOLECULAR AND CYTOGENETIC DESCRIPTION OF FOUR MARINE FISH SPECIES 1115

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