Now showing 1 - 3 of 3
  • Publication
    Loop-mediated isothermal amplification of the toxR gene coupled with lateral flow dipstick (LAMP-LFD) for the novel, rapid and specific visual detection of Vibrio harveyi
    (Malaysian Society for Microbiology, 2023) ;
    Julian Ransangan
    ;
    Vijay Kumar Subbiah
    Vibrio harveyi is a serious pathogen for marine organisms particularly in hatcheries and grow-out ponds that attack their immune system. The rapid detection of V. harveyi is urgently needed to prevent bacterial spread. Here we described a rapid and specific visual detection method based on the Loop-Mediated Isothermal Amplification in combination with Lateral Flow Dipstick (LAMP-LFD). Methodology and results: A set of six novel primers were designed to target the toxR gene. These include the biotin-labelled inner primer that complements specifically to the target sequences. The resulting biotinylated LAMP amplicons were hybridised to the FAM-labelled probe resulting in lateral flow detection on the dipstick. The addition of loop primers improved the reaction time of LAMP by more than half and rapid detection was observed within 10-15 min. In comparison, the sensitivity of PCR-UV analysis was only at 104 copies while LAMP-LFD was able to detect lower amounts at 103 copies. The LFD provided higher specificity and selectivity since hybridization with specific probes to the LAMP amplicons was employed. In addition, detection of V. harveyi infected grouper was successful using the LAMP-LFD method described here. Conclusion, significance and impact of study: LAMP-LFD is specific to V. harveyi. Our method provides a useful tool to rapidly detect and monitor the outbreaks of the pathogen.
  • Publication
    Morphological variability identification of Harumanis Mango (Mangifera indica L.) harvested from different location and tree age
    (Penerbit Universiti Sains Malaysia, 2020-08)
    Siti Nur Arina Yusuf
    ;
    ; ;
    Vijay Kumar Subbiah
    ;
    ;
    Zakaria Wahab
    Harumanis is one of the main signatures of Perlis with regards to its delightful taste, pleasant aroma and expensive price. Harumanis authenticity and productivity had become the remarks among the farmers, entrepreneurs, consumers and plant breeders due to the existence of morphological characteristics variation among the fruits and high production cost. Assessment of Harumanis morphological characteristics of natural population and different tree ages may represent a possible source of important characteristics for development and breeding purposes of Harumanis. The aim of this study is to evaluate the morphological variation of Harumanis collected from different location in Perlis and tree age. A total of 150 Harumanis fruits from 50 trees with three different stages of development (young, middle-aged and old) were characterised using 11 traits; 10 quantitative and one qualitative morphological trait. The ANOVA analyses in combination with Dunn’s pairwise and Kruskal-Wallis multiple comparison test able to point out the existence of environmental factor and age influence towards the significant different of identified morphological traits except for Total Soluble Solid (TSS) and pulp percentage. Five clusters of 50 Harumanis accessions reflect a grouping pattern which not according to neither geographical region nor age. The result of Principal Component Analysis (PCA) using the first two principal components (PCs) provided a good approximation of the data explaining 84.09% of the total variance which majorly contributed by parameters of weight, fruit dimensional characteristics, peel percentage and hue angle, h. Preliminary screening of important morphological characteristics which contribute to the phenotypic diversity of Harumanis is successfully achieved. The findings can be employed by the plant breeders and farmers for the establishment of standard grading of Harumanis and advancement of breeding crop of Harumanis in future.
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  • Publication
    Chloroplast DNA sequence of trnR-N and trnL-F regions in Harumanis mango from different orchards in Perlis, Malaysia
    (IOP Publishing Ltd, 2020) ;
    SFM Sabri
    ;
    Yusuf, Arbai
    ;
    ;
    SV Kumar
    Harumanis is a premium mango cultivar widely known for its sweet taste, aroma and vibrant flesh colour. To date, the genetic identification of this mango based on multiple conserved DNA region using samples from different orchards has never been reported. The aim of this research is to identify the genetic signature of Harumanis mango at molecular level by analyzing chloroplast DNA sequences of the trnL-F and trnR-N regions. DNA samples were extracted from a total of 15 Harumanis samples collected from five selected orchards using Cetyl Trimethyl Ammonium Bromide (CTAB) extraction procedure. The extracted DNA and the PCR-amplified products were analyzed through gel electrophoresis and were then subjected to DNA Sequencing and in silico analysis. The obtained sequences were compared with the sequences available in the GeneBank. BLAST search for both the trnR-N and trnL-F regions confirmed that all the 15 samples belong to Mangifera indica with a 99% sequence identity. In addition, the trnL-F sequences were 99% identical to a number of specific mango cultivars such as, Tommy and Arunika. However, the trnR-N sequences were less informative as it gave hits to only two mango accessions (e.g. Mangifera indica voucher PDBK 2014-0249). It is postulated that the plastid trnR-N may be a potential candidate region for the development of the Harumanis genetic signature. The results may be used to complement other molecular data for the development of a genetic barcode for Harumanis.
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