1Department of Aquatic Animal Health, Faculty of Fishery Sciences, West Bengal University of Animal and Fishery Sciences, Chakgaria, Kolkata, India
2298/1 BG patuli
Myxozoans are an economically important group of microscopic parasites best known for the diseases they cause in commercially important fish hosts. The classification of myxosporeans is generally based on the morphology of their myxospores. Without molecular data, it is very difficult to identify new or existing species. DNA sequence information is therefore, a prerequisite to taxonomic and phylogenic studies of myxosporeans. In the present study, a myxozoan parasite, Myxobolus carnaticus,infecting the gill lamellae of mrigal carp, Cirrhinus mrigala,was characterized by the 18S rRNA gene sequence. The DNA sequence of M. carnaticus clustered phylogenetically with other gill infecting Myxobolus spp. of freshwater clades, forming a dichotomy with closely related M. pavlovskii (HM991164) that infects the gill lamellae epithelium of silver carp, Hypophthalmichthys molitrix with 95% similarity. Evolutionary pair-wise distances among M. carnaticus and other species of myxosporeans indicated high genetic diversity among myxosporeans. The present study demonstrated that tissue tropism, host specificity and habitat play important roles in phylogenetic relationships among myxozoan species.
1. Kent ML, Andree KB, Bartholomew JL, El-Matbouli M, Desser SS, Devlin RH, Feist SW, Hedrick RP, Hoffmann RW, Khattra J, Hallett SL, Lester RJG, Longshaw M, Palenzeula O, Siddall ME, Xiao C. Recent advances in our knowledge of the Myxozoa. J Eukary Microbiol 2001;48:395–413.
2. Lom J, Dyková I. Myxozoan genera: definition and notes on taxonomy, life-cycle terminology, and pathogenic species. Folia Parasitol 2006;53:1-36.
3. Chandra KJ, Begum AA, Ahmed GU, Wootten R. Infection of Myxosporean ectoparasites of juvenile carps in nurseries of Mymensingh, Bangladesh. Bangla J Aquacult 1996;18:39-44.
4. Smothers JF, Van Dohlen CD, Smith Jr LH, Spall RD. Molecular evidence that the myxozoan protists are metazoans. Science 1994;265:1719-1721.
5. Lom J, Arthur JR. A guideline for the preparation of species descriptions in Myxosporea. J Fish Dis 1989;12:151-156
6. Mondal A, Banerjee S, Patra A, Adikesavalu H, Ramudu KR, Dash G, Joardar SN, Abraham TJ. Molecular and morphometric characterization of Thelohanellus caudatus (Myxosporea: Myxobolidae) infecting the caudal fin of Labeo rohita (Hamilton). Protistology 2014;8:41-52.
7. Barta JR, Martin DS, Liberator PA, Dashkevicz M, Anderson JW, Feighner SD, Elbrecht A, Perkins-Barrow A, Jenkins MC, Danforth HD, Ruff MD, Profous-Juchelka H. Phylogenetic relationships among eight Eimeria species infecting domestic fowl inferred using complete small subunit ribosomal DNA sequences. J Parasitol 1997;83:262-271.
8. Abraham TJ, Banerjee S, Patra A, Sarkar A, Adikesavalu H, Dash G. Molecular phylogeny of Myxobolus orissae (Myxosporea: Myxobolidae) infecting the gill lamellae of mrigal carp Cirrhinus mrigala (Actinopterygii: Cyprinidae). Mol Biol Res Commun 2015;4:15-24.
9. Edgar, Robert C. MUSCLE: multiple sequence alignment with high accuracy and high throughput. Nucleic Acids Res 2004;32:1792-1797.
10. Tamura K, Stecher G, Peterson D, Filipski A, Kumar S. MEGA6: Molecular evolutionary genetics analysis version 6.0. Mol Biol Evol2013;30:2725-2729.
12. Milne I, Lindner D, Bayer M, Husmeier D, McGuire G, Marshall DF, Wright F. TOPALi v2: a rich graphical interface for evolutionary analyses of multiple alignments on HPC clusters and multi-core desktops. Bioinformatics 2008;25:126-127.
13. Kimura M. A Simple method for estimating evolutionary rate of base substitutions through comparative studies of nucleotide sequences. J Mol Evol 1980;16:111-120.Seenappa D, Manohar L. Two new species of Myxobolus (Myxosporidia: Protozoa) parasitic on Cirrhina mrigala (Hamilton) and Puntius curmuca (Hamilton). Curr Sci 1980;49:204-206.
14. Fiala I. The phylogeny of Myxosporea (Myxozoa) based on small subunit ribosomal RNA gene analysis. Int J Parasitol 2006;36:1521-1534.
15. Rajesh SC, Banerjee S, Patra A, Dash G, Abraham TJ. Molecular characterization of Myxobolus cuttacki (Myxozoa, Myxosporea, Bivalvulida) infecting gill lamellae of minor carp Labeo bata (Ham.). Mol Biol Res Commun 2014;3:1-9.
16. Molnár K. Comments on the host, organ and tissue specificity of fish myxosporeans and the types of their intrapiscine development. Parasitol Hung 1994;27:5-20.
17. Eszterbauer E. Genetic relationship among gill-infecting Myxobolus species (Myxosporea) of cyprinids: molecular evidence of importance of tissue-specificity. Dis Aquat Org 2004;58:35-40.
18. Kaur H, Singh R. A synopsis of the species of Myxobolus Bütschli, 1882(Myxozoa: Bivalvulida) parasitizing Indian fishes and a revised dichotomous key to myxosporean genera. Syst Parasitol 2012;81:17-37.