Phylogenetic Analysis Of Major Fresh Water Carps Of Pakistan Through DNA Barcoding
Material type: Book ; Literary form:
Publisher: 2014 Dissertation note: Pakistan is bestowed with the land of geological and topographic diversity. The ecological variation is uniformly reflected in all water lands of the country. Pakistan has significantly huge natural inland water resources in the form of ocean, rivers, networks of canals and lakes (Mirza and Rafique 1994). The country is blessed with one of the largest freshwater resources in the world correspondingly large number of freshwater living vertebrates is available from which fishes are quite significant considering the ecological balance and its consumption as food. It is one of the food sources which solely provide all the essential nutrients, minerals and high quality protein which is not common from other food items (Muhammad Rafique 2007). Out of 33,100 fish species identified worldwide as per Fish Base organization report published in April 2015 (http://www.fishbase.org). Out of 233 (indigenous and exotic) freshwater fish species, 78 economically important indigenous fish species are available in the water bodies of the Pakistan. According to this report fishes are the largest vertebrate group, constituting about 50% of all vertebrate species. Systematically fishes are widely spread in nature, ranging from prehistoric jawless fishes to cartilaginous fishes and also from old to current day bony fishes. The taxonomic placement of these fishes shows their belonging to class Actinopterygii, sub-class Teleostei, 3 cohorts, 6 superorders, 13 orders, 30 families and 86 genera (Rafique 2007; Rafique and Khan 2012).
Demand of fish is increasing day by day not only being the naturally available source of food rather the health benefits associated with its consumption. This necessitates to develop a more efficient and sustainable system to increase their growth. DNA based technologies are being competently employed in aquaculture production fields for pedigree information.
Moreover, tagging each fish individually is not an easy task so these DNA based methods help in avoiding intrusion of environmental factors which may result from raising fish families in separate reservoirs (Martinez 2007). Fish identification has been traditionally based on phenotypic features. However, due to high multiplicity and morphological similarity, in many cases, fish at its different developmental stages are hard to be identified by relying only on morphological characteristics (Victor et al. 2009).
For phylogenetic studies of the animals the use of mt-DNA is very common and reliable compared to nuclear DNA due to its high evaluation capabilities, which results in gathering of differences even between closely related species (Moore 1995; Mindell et al. 1997).“Bar-coding gap" is the name given to the property that is inter-specific variation in this region is markedly higher than intra-specific variability (Hebert et al. 2003).
Approximately each and every animal contain 13 protein-coding genes (PCGs) as an essential component of their mt-genome (mitochondrial genome), which helps in encoding of several proteins responsible for the oxidative phosphorylation machinery (Richly A et al. 2004, Song H et al. 2008). Being maternally inherited, mt-DNA is better as compared to genomic DNA such as quick evolution, less exposure to recombination, high copy number, high conservation, little duplications and negligible intergenic regions (Waugh J 2007, Xu J 2005). Clonal inheritance is the main property which makes it more worthy and suitable marker in comparison with other available molecular bio-diversity tools (Galtier et al. 2009).
DNA barcoding is one of the taxonomic tools. It is being used to distinguish animal species based on the small segment of their genome such as mitochondrial DNA, designated as an identification tag or barcode of particular species (Herbert et al. 2003). Identification of species using DNA barcoding is quite debatable. Still many researchers consider it as a reliable
basic tool to ascertain the genetic characterization of diverse eukaryotic species, especially after establishment of the Consortium for the Barcode of Life (CBOL) in 2004 [http: //www. barcodeoflife.org/].
Ideally DNA barcoding should provide quick, reliable and cost effective species identification, even to those user who has little or negligible knowledge of taxonomy (Herbert et al. 2003, Hajibabaei M et al. 2005, Herbert et al. 2005). Identification of unknown source is possible by using distance based tree which can be created by comparing unidentified sequences against retrieved known sequences of different species (Hebert et al. 2003, 2004a, 2004b). DNA barcoding identification system has been recognized universally as standardized method to recognize species and unveil their genetic diversity (Herbert et al. 2003; Herbert et al. 2004). The ideal DNA barcoding is robust, with conserved, universal primer binding sites, reliable DNA amplification and sequencing.
From whole mitochondrial genome, Cytb (Cytochrome b) is considered as one of the most promising gene due to its function and structure, even it is composed of both conserved and rapidly evolving regions which are more related to evolutionary studies (Farias et al. 2001). To identify unknown or ambiguous species it is considered more reliable as it contain sequences which provide the specific information about particular species (Parson W et al. 2000a, 2000b). It is also one of the most useful genetic marker to identify the linkage within families and genera (Meyer 1994; Teletchea 2009). Cytb gene is involved in comparative studies which results in development of new classification schemes and been used to assign a genus to a newly described species as well as improve the understanding of evolutionary relationships of genra (Castresana 2001).
One of the core objectives of this study is to identify and classify four freshwater indigenous fish species of Pakistan, which includes Labeo rohita (Rohu), Labeo calbasu (Calbans), Catla catla (Thalla) and Cirrhinus mrigala (Mori) using Cytb gene. Morphologically, Labeo rohita shows compressed body with convex dorsal profile while mouth bears a pair of barbells and fins are gray and orange in color. Catla catla shows compressed body with broad head. Mouth is wide with thick lower lip. Labeo Calbasu`s dorsal profile is more convex than that of abdomen and two pairs of barbells are present on fringed upper lip. Cirrhinus mrigala has elongated and streamlined body shape which is grayish and silver in color (Bhuiyan AL 1964; Rahman AK 1989). All of these species are found in freshwater bodies mostly lakes, rivers and ponds except Labeo calbasu which is a bottom dweller. These fishes are harvested by using rod and line or by using nets (Talwar PK and Jhingran AG 1991). These fishes are known as major carps and economically very important for the country due to their high consumption as food. These fishes are also used for fish farming due to their greater muscle mass thus also possess very high commercial value for fish farming business.
Another objective of this study is to resolve the taxonomic anomalies related to above mentioned species. Selling of fish meat in mislabeled packaging is a serious issue now days. Most commonly Hypophthalmichthys molitrix (silver carp) and Ctenopharyngodon idella (grass carp) are sold under the label of Labeo rohita. DNA barcoding is also helpful in detecting such fraudulent mislabeling.
It would be the first study in Pakistan to genetically characterize commercially important fish species. It would help scientists to know about their phylogenetic and taxonomic status and also assist fish fanciers to genuinely identify their species of interest. Identification of fish species is also important for conservation of biodiversity as it helps in preservation and
identification of endangered species by generating their barcodes from even minimal evidence available. This study has paved the way for molecular biologists to study taxonomic ambiguities at sub species level using SNP (Single nucleotide polymorphism) based identifying marker.
Availability: Items available for loan: UVAS Library [ Call number: 2207-T] (1).
Genetic Identification And Molecular Classification Of Sub-Family Phasianinae Of Pakistani Bird Species Through Dna Barcoding
Material type: Book ; Literary form:
Publisher: 2015 Dissertation note: DNA barcoding is a precise technique that uses molecular genetics tools for accurate identification, categorizing, relating and separating the phylogenies of species. Being a small sized genome and agile enough to show rapid mutation, mtDNA has been used as a pertinent marker of molecular biodiversity.The aim of this study was to develop DNA barcode for genetic characterization and classification of Sub-family Phasianinaeof Pakistani bird species. Theyhave not been genetically identified yet in Pakistan. It includes birds like domestic chicken(Gallus gallusdomesticus), aseel chicken(Gallus gallusdomesticus strain),blue peafowl(Pavo cristatus), green peafowl (Pavo muticus), white peafowl (Pavo cristatus leuticus), Kalij pheasant (Lophura leucomelanos),monal pheasant (Lophophorus impejanus),koklass pheasant(Purcrasia macrolopha), ring necked pheasant (Phasianus colchicus), Tragopan (Tragopan melanocepals) andred junglefowl (Gallus gallus). These birds are considered an important part of an ecosystembecause they play a significant role in seed dissemination, pollination of plants and disease spread which are the basic constituents of an ecosystem. They are used for food, hunting and entertainment purposes.
Mitochondrial geneCytochrome c oxidase subunit 1 (CO1)of 500bps was used as a marker for identification at specie level.Genomic DNA was extracted by each blood and tissue sample of eleven bird species (33 samples). Amplification of CO1 gene was a done by using a universal set of primers (BIRDF1 and BIRDR1)containing region of almost 750 bps (Hebert et al. 2003).Amplicons were purified and sequenced Sanger sequencing method (Sanger et al. 1977). Forward and reverse sequences were analyzed using softwaresEMBOSS merger,ClustalW, BioEdit and nBLAST. Phylogenetic analysis of selected bird species was done. Each sequence was aligned
with its reference sequences of CO1 gene present on NCBI. Every nucleotide position which did not align with the reference sequence was studied to identify SNPs. Fixation index (FST) were used to measure species diversity within a same sub population relative to that found in the entire population. Consensus sequences (500bps) generated was used to construct their phylogenetic tree to see their evolutionary relationship with other bird species. All species showed their closest linkage with their respective species. Pakistani population of peafowl and chicken species showed the close relation with same sequences generated in China. Tranopans showed its closest linkage with T. temminckii.
In conclusion, seven species ofPhasianinaesub-family of Pakistani bird species was genetically characterized first time in Pakistan by using CO1 as a barcode. It proves that DNA barcoding is an efficient and accurate molecular tool for species identifica¬tion and phylogenetic implication. This study leads to establish a DNA Data Bank that helped scientists to investigate the biodiversity, taxonomic classification, specie identification, in forensic purposes and to study the genetic and phenotypic evolution of these species. DNA barcoding through CO1 gene works as a functional tool for detectingmeat mislabeling and preventing illegitimate trade. This study has established foundations for molecular biologists to study taxonomic uncertainties at sub species level using SNP based identifying marker. It helps in preservation and identification of endangered species by generating their barcodes from even minimal evidence available.
Availability: Items available for loan: UVAS Library [ Call number: 2376-T] (1).