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Title:	Phylogenetic characterisation of Asian seabass (Lates calcarifer) transferrin
Authors:	Hirzahida Mohd Padil (P45172)
Supervisor:	Adura Mohd. Adnan, Dr.
Keywords:	Transferrin
Issue Date:	26-Sep-2012
Description:	Transferrin is a protein superfamily involved in iron binding and transport. Throughout the evolution of vertebrates, transferrin members have diversified into distinct sub-families including serotransferrin, ovotransferrin, lactoferrin, melanotransferrin, the inhibitor of carbonic anhydrase, pacifastin and the major yolk protein in sea urchin. In this study, a cDNA sequence encoding the transferrin of the Asian seabass (Lates calcarifer) was analyzed and identified to characterise its subfamily and function. The cDNA sequence of L. calcarifer transferrin, which consists of 2398 base pairs, was translated into its open reading frame (ORF) sequence of 690 amino acids in size. Two transferrin domains have been identified contained in the protein sequence, similar to transferrin sequences from other species studied so far. A comprehensive phylogenetic analysis of transferrin homologs has been carried out using Neighbor-Joining, Maximum-Parsimony, Maximum-Likelihood and Bayesian methods. The phylogenetic analysis of L. calcarifer transferrin and its homologous sequences from various organisms in Swiss-Prot and Ensembl database clustered the L. calcarifer transferrin as serotransferrin. Additionally, fish serotransferrin clustered according to the ecological habitat of the species. This suggests that the evolution of fish transferrin might caused by their adaptation to the environment where it is found. The phylogenetic analysis in this study also revealed the presence of one transferrin novel group consisting of sequences from fish, avian and amphibian but absent from mammals. This group diverged after the melanotransferrin, thus, proposing that another duplication event might have occurred before the melanotransferrin and serotransferrin split. Most of the functional residues that responsible for iron binding protein, which are acid aspartic, two tyrosine and histidine have been substituted with other residues in those sequences clustered in this newly-identified group. This observation thus suggests that they might perform a different role than those functions that have been characterised. Transferrin merupakan superfamili protein yang berfungsi sebangai pengikat dan pengangkut ion ferum. Melalui proses evolusi, transferrin telah berkembang membentuk beberapa subfamili iaitu serotransferin, ovotransferin, laktoferin, melanotransferin, perencat karbonik anhidrase, pasifastin and protein utama dalam kuning telur landak laut. Dalam kajian ini, jujukan cDNA yang mengekodkan protein transferin dari ikan siakap (Lates calcarifer) telah dianalisis dan dikenalpasti untuk mencirikan taburan dan fungsinya. Jujukan cDNA transferin bagi L. calcarifer yang mengandungi 2398 pasangan bes telah ditranslasikan kepada jujukan rangka bacaan terbukanya yang bersaiz 690 asid amino. Dua jujukan domain transferin telah dijumpai dimana domain tersebut merupakan domain yang biasa dijumpai dalam protein transferin spesies yang lain. Analisis filogenetik yang komprehensif telah dijalankan menggunakan kaedah Neighbor-Joining, Maximum-Parsimony, Maximum- Likelihood dan Bayesian. Analisis filogenetik yang mengandungi jujukan transferin dari L. calcarifer dan jujukan-jujukan berhomolog dari pelbagai organisma dalam pangkalan data Swiss-Prot dan Ensembl menunjukkan jujukan transferin dari L. calcarifer telah dikelaskan sebagai serotransferin. Selain itu, Serotransferin dari ikan boleh dikelaskan berdasarkan habitat sesuatu spesies tersebut. Ini mencadangkan bahawa evolusi transferin dalam ikan adalah disebabkan oleh penyesuaian terhadap persekitaran mereka. Analisis filogenetik dalam kajian ini juga menunjukkan terdapat satu subkumpulan transferin baru (novel) yang terdiri daripada ikan, burung dan amfibia tetapi telah hilang dalam mamalia. Kumpulan baru ini telah mencapah daripada kumpulan melanotransferrin seterusnya mencadangkan kemungkinan terdapat satu lagi kejadian duplikasi berlaku di antara kumpulan melanotransferin dan serotransferin. Kebanyakan residu-residu berfungsi yang terlibat dalam pengikatan ferum iaitu asid aspartik, dua tirosin dan histidin telah digantikan dengan residu yang lain dalam jujukan-jujukan transferin homolog yang baru ditemui ini. Pemerhatian ini seterusnya mencadangkan bahawa kumpulan ini mungkin memainkan peranan yang berbeza dengan fungsi-fungsi yang telah dikenalpasti sebelum ini,Master / Sarjana
Pages:	103
Call Number:	QP552.T7 H538 2012
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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