Development of Standard DNA Size Markers for Short Tandem Repeat Loci BM1818 and BM1824 of Cattle DNA Typing in Sri Lanka
No Thumbnail Available
Date
2013
Journal Title
Journal ISSN
Volume Title
Publisher
Uva Wellassa University of Sri Lanka
Abstract
Cattle are the most common type of livestock animal raised for meat, dairy, as draft animals and
various other purposes. Sri Lankan cattle population mainly consist of indigenous cattle
“Sinhala batu cattle”, European pure breeds (Jersey, Friesian, Ayrshire), Indian cattle breeds
(Sahiwal, Sindhi, Tharparkar), and their crosses. Identification and traceability of cattle and
their products is extremely important for proven of ownership, exploration of pedigree and
animal disease control. Traditional identification methods are less effective and associated with
many economic, cultural and ethical concerns and are not reliable methods of establishing
maternity or paternity of cattle. Deoxyribo Nucleic Acid (DNA) based identification is based on
the unique, unalterable, inherited DNA profile of an individual animal as an identifier. Testing
the Short Tandem Repeats (STR) of DNA in establishing the identity and parentage is widely
used for humans in Sri Lanka. However DNA based identity testing methods are needed to be
developed for cattle in order to use it as an accurate method than conventional methods to
address problems of cattle identity and traceability. Currently there is no proper procedure of
DNA based of identification in Sri Lanka due to the unavailability of standard DNA size
markers and there is an urgent need of developing standard DNA size markers for cattle STR
(allelic ladders) for accurate genotyping of an individual. Therefore the present study was
conducted to develop standard DNA size markers for STR loci BM1818 and BM1824.
Methodology
Selection of loci
Two bovine specific STR markers (BM1818, BM1824) recommended by the Food and
Agriculture Organization (FAO) and the International Society for Animal Genetics (ISAG)
(FAO, 2011) and previous studies done by Goor and Van de (2011) were selected for this
study.
Sample collection and DNA extraction
Blood samples (n=38) and tissue samples (n=12) were randomly collected from unrelated
animals from different areas of the country according to the recommendations provided by FAO
100 extraction protocol described by
Phillips (2009) with minor modifications. DNA from tissue samples was extracted by
ChargeSwitch Forensic DNA Purification Kit (Invitrogen™, Life Technologies Corporation)
according to the kit’s manual.
PCR amplification
PCR amplification of extracted DNA samples was carried out with 5 µL of genomic DNA in a
50 µL reaction volume, consisted of 5 µL of 10X STR buffer (DreamTaq Green Buffer -
Thermo Scientific), 5 µL of each dNTP (Guangzhou Geneshun Biotech Ltd.), 5 µL of primer
(FAO, 2011 and Goor and Van de 2011) (Integrated DNA Technology), 0.30 µL of Taq DNA
polymerase (DreamTaq-Thermo scientific) and 30 µL of sterilized distilled water. The PCR
reaction was carried out in a Veriti 96 well thermal cycler (Applied Biosystem, USA) under the
following PCR cycling conditions (Sodhi et al., 2006): 2 min at 94 °C, followed by 30 cycles of
1 min at 94 °C, 1 min at annealing temperature (56 to 62 °C) of each primer, 1 min at 72 °C, and
final extension of 10 min at 72 °C. Subsequent to PCR, the products were subjected to 3 % w/v
agarose gel electrophoresis to verify the success of the PCR reaction. Then the PCR products
were subjected to 7 % denaturing polyacrylamide gel electrophoresis. Amplified products were
detected using DNA Silver Staining procedure described by Bassam et al. (1991) and Promega
technical manual.
Allelic ladder construction
Allelic ladders were constructed by two methods as follows (1) DNA samples that can
contribute to maximum number of polymorphic alleles to each locus were selected, pooled and
amplified by PCR reaction (100 µL reaction volume), (2) PCR products that can contribute to
maximum number of polymorphic alleles to each locus were selected and pooled to create the
allelic ladders.
Results and Discussion
According to the Table 1, allelic range of the BM1818 locus was from allele 11 to 21. The
highest frequency was shown by allele No.18 at a percentage of 35.0 percent. Allele 11 had the
lowest frequency with 1.3 percent. When considering BM1824 locus, allelic range was from
allele 11 to 19. The highest frequency was shown by allele No.13 at a percentage of 34.1
percent. Two alleles (11 and 18) showed the lowest allelic frequency of 1.2 percent.
Description
Keywords
Animal Sciences, Indigenous Medicine, Genetics, Cattle, Animal Production Technology