C.K. Yap

Putra University, Malaysia, Putrajaya, Putrajaya, Malaysia

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Publications (174)126.49 Total impact

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    ABSTRACT: Information on the biological responses of polyploid animals towards environmental contaminants is scarce. This study aimed to compare reproductive axis-related gene expressions in the brain, plasma biochemical responses, and the liver and gill histopathological alterations in diploid and triploid full-sibling juvenile African catfish (Clarias gariepinus). Fish were exposed for 96 h to one of the two waterborne phenanthrene (Phe) concentrations [mean measured (SD): 6.2 (2.4) and 76 (4.2) μg/L]. In triploids, exposure to 76 μg/L Phe increased mRNA level of fushi tarazu-factor 1 (ftz-f1). Expression of tryptophan hydroxylase2 (tph2) was also elevated in both ploidies following the exposure to 76 μg/L Phe compared to the solvent control. In triploids, 76 μg/L Phe increased plasma alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) levels compared to the other Phe-exposed group. It also elevated lactate and glucose contents relative to the other groups. In diploids, however, biochemical biomarkers did not change. Phenanthrene exposures elevated glycogen contents and the prevalence of histopathological lesions in the liver and gills of both ploidies. This study showed substantial differences between diploids and triploids on biochemical and molecular biomarker responses, but similar histopathological alterations following acute Phe exposures.
    Full-text · Article · Feb 2016 · Environmental Pollution
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    C K Yap · B H Chua · C H Teh · S G Tan · A Ismail

    Full-text · Dataset · Sep 2015
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    C C Ong · C H Teh · S G Tan · K Yusoff · C K Yap

    Full-text · Dataset · Sep 2015
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    ABSTRACT: Fish tilapia Oreochromis mossambicus were collected from a contaminated Seri Serdang (SS) pond potentially receiving domestic effluents and an uncontaminated pond from Universiti Putra Malaysia (UPM). The fish were dissected into four parts namely gills, muscles, intestines, and liver. All the fish parts were pooled and analyzed for the concentrations of Cd, Cu, Fe, Ni, Pb, and Zn. Generally, the concentrations of all metals were low in the edible muscle in comparison to the other parts of the fish. It was found that the levels of all the heavy metals in the different parts of fish collected from the SS were significantly (P < 0.05) higher than those from UPM, indicating greater metal bioavailabilities in the SS pond. The sediment data also showed a similar pattern with significantly (P < 0.05) higher metal concentrations in SS than in UPM, indicating higher metal contamination in SS. Potential health risk assessments based on provisional tolerable weekly intake (PTWI) and the amount of fish required to reach the PTWI values, estimated daily intake (EDI), and target hazard quotient (THQ) indicated that health risks associated with heavy metal exposure via consumption of the fish's muscles were insignificant to human. Therefore, the consumption of the edible muscles of tilapia from both ponds should pose no toxicological risk of heavy metals since their levels are also below the recommended safety guidelines. While it is advisable to discard the livers, gills, and intestines of the two tilapia fish populations before consumption, there were no potential human health risks of heavy metals to the consumers on the fish muscle part.
    Full-text · Article · Sep 2015 · Environmental Monitoring and Assessment
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    Chee Kong Yap · Wan Hee Cheng
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    ABSTRACT: The beryllium (Be) concentrations were determined in the shells, opercula and soft tissues of the Nerita lineata and in the surface sediments collected from nine geographical sites of Peninsular Malaysian mangrove area in April 2011. The ranges of Be concentrations (μg/kg dry weight) were: <1.00- 4.00 for shells, <1.00-2.00 for opercula and 3.00-41.00 for soft tissues of N. lineata. For sediments, Be ranges were found between 1200 and 3810 μg/kg dry weight. The distribution of Be was found to be: sediment> soft tissues > shells ≥ opercula. The insignificant (p>0.05) relationships of Be between snails and sediments and low bioaccumulation factor (ratio of soft tissues to sediment) (<1.00), could be attributed to the fact that Be contamination being not serious in the Peninsular Malaysian mangrove area. The snail N. lineata as a good biomonitor of Be needs further investigations. Lastly, Peninsular Malaysia mangrove was not contaminated by Be based on the present findings.
    Full-text · Article · Jul 2015 · Sains Malaysiana
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    Wan Hee Cheng · Chee Kong Yap
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    ABSTRACT: Samples of mangrove snails Nerita lineata and surface sediments were collected from nine geographical sampling sites in Peninsular Malaysia to determine the concentrations of eight metals. For the soft tissues, the ranges of metal concentrations (μgg(-1)dryweight (dw)) were 3.49-9.02 for As, 0.69-6.25 for Cd, 6.33-25.82 for Cu, 0.71-6.53 for Cr, 221-1285 for Fe, 1.03-50.47 for Pb, and 102.7-130.7 for Zn while Hg as 4.00-64.0μgkg(-1)dw(-1). For sediments, the ranges were 21.81-59.49 for As, 1.11-2.00 for Cd, 5.59-28.71 for Cu, 18.93-62.91 for Cr, 12973-48916 for Fe, 25.36-172.57 for Pb, and 29.35-130.34 for Zn while for Hg as 2.66-312μgkg(-1)dw(-1). To determine the ecological risks on the surface habitat sediments, sediment quality guidelines (SQGs), the geochemical indices, and potential ecological risk index (PERI) were used. Based on the SQGs, all the metals investigated were most unlikely to cause any adverse effects. Based on geoaccumulation index and enrichment factor, the sediments were also not polluted by the studied metals. The PERI values based on As, Cd, Cu, Cr, Hg, Pb and Zn in this study were found as 'low ecological risk'. In order to assess the potential health risks, the estimated daily intakes (EDI) of snails were found to be all lower than the RfD guidelines for all metals, except for Pb in some sites investigated. Furthermore, the calculated target hazard quotients (THQ) were found to be less than 1. However, the calculated total target hazard quotients (TTHQ) from all sites were found to be more than 1 for high level consumers except KPPuteh. Therefore, moderate amount of intake is advisable to avoid human health risks to the consumers. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Full-text · Article · May 2015 · Chemosphere
  • W H Cheng · C K Yap · M P Zakaria
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    ABSTRACT: Sampling for the mangrove snails, Nerita lineata, and surface sediments was carried out from nine geographical sites of Peninsular Malaysia in April 2011. The concentrations of Lithium (Li) were determined in the shells, opercula and soft tissues of N. lineata and in the surface sediments by using ICP-MS. The ranges of Li concentrations (µg/g dry weight) were found to be 0.107-0.283 for shells, 0.021-0.177 for opercula and 0.011-0.634 for total soft tissues of N. lineata. For sediments, Li ranges were found to be between 21.84-146.22 µg/g dry weight). The distribution of Li was found to be: sediment> ST> shell> opercula. The Li sediment data in the present study were comparable with the results of Li contaminated sediments which had been previously reported in the literature and higher than those of continental crust materials and igneous rocks. There was no significant correlation (P>0.05) for the Li levels between the sediments. The snails (shells, opercula and soft tissues) and this indicated that Li is an essential metal for metabolism and thus is being regulated in the body of the snail. INTRODUCTION Lithium (Li) is the lightest of the alkali metals belonging to group 1 of the Periodic Table, along with Na, K, Rb and Cs. Li has been extensively utilized in a wide number of industrial, scientific, and clinical applications (Hu, 2013). In particular, the
    No preview · Article · Feb 2015 · Pertanika Journal of Tropical Agricultural Science
  • Chee Kong Yap

    No preview · Article · Jul 2014 · Chemosphere
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    C.K. Yap · F.B. Edward · S.G. Tan
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    ABSTRACT: Three populations of Polymesoda erosa collected from the west coast of Peninsular Malaysia were analyzed for heavy metals. Their soft tissues were dissected into muscle, foot, mantle, gill and remaining soft tissues (remainder). Overall metal concentrations (μg/g dry weight) in five soft tissues of the three clam populations were Cd (0.25-2.86), Cu (1.80- 21.0), Ni (0.66-30.0), Pb (0.94-7.09), and Zn (79.2-365), and these were Cd (3.64-7.07), Cu (2.37-3.29), Ni (26.2-30.0), Pb (58.8-61.6), and Zn (3.84-8.78) for the shell ranges. Among the three Polymesoda populations, gill was found to have accumulated higher Cu and Zn concentrations compared to other soft tissues, whereas shell was found to have high levels of non-essential Cd, Pb and Ni. Information on heavy metals obtained in this study could serve as baseline data for this particular species since the information is lacking in the literature. The present study has evidently shown that different soft tissues of P. erosa are potential biomonitoring for Cd, Cu, Ni and Zn, whereas the clam shell as a potential biomonitoring material for Pb based on: (1) positive results based on biota-sediment accumulation factors (BSAF) (being macroconcentrators), (2) positive and significant correlations of metals between all five soft tissues (foot, gill, mantle, muscle and remainder) and the sedimentary geochemical fractions and total metal concentrations, and (3) comparisons to two similar burrowing bivalves (Donax faba and Gelonia expansa). Regardless of some metals in edible soft tissues having exceeded the food safety permissible limits, the concentrations of Cd, Cu, Ni and Zn in the soluble fractions (which is more bioavailable to consumers) of all the five edible soft tissues of P. erosa are below all the permissible metal limits. Therefore, these estimations clearly showed that the consumption of P. erosa could pose no toxicological risks to consumers.
    Full-text · Article · Feb 2014 · Pertanika Journal of Tropical Agricultural Science
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    Full-text · Dataset · Jan 2014
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    C K Yap · W H Cheng · S.G. Tan
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    ABSTRACT: The concentrations of Cd and Zn were determined in Nerita lineata snails and sediments collected from Johore and Klang between May 2010 and April 2011. This study found variations of heavy metal accumulations in the shells, opercula and soft tissues. The mean concentrations (μg/g dry weight) of Cd and Zn were 5.42 and 8.11 for shells; 5.60 and 14.26 for opercula; 3.08 and 110.90 for soft tissues, respectively. The mean concentrations (μg/g dry weight) of Cd and Zn for surface sediments were 1.76 and 88.78, respectively. Generally the results of this study were comparable with those of previous reports on the same species
    Full-text · Article · Dec 2013 · Journal of Sustainability Science and Management
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    C K Yap · G H Ong · S.G. Tan · Maziah · Hamzah · M.S.
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    ABSTRACT: Increase of Uranium (U) in the environment has risen the public concern, especially in medicinal plants. Therefore the aim of this study was to determine the potential of Centella asiatica (L.) Urban as a good bio indicator of U pollution based on the correlation of U levels between plant and soil and experimental transplantation study. The U in soils and C. asiatica was determined by Neutron Activation Analysis (NAA). TheU levels in soils from 12 sampling sites ranged from 1.97μg/g to 10.71μg/g dw. The Enrichment factor ranged from 0.79 to 18.25 and the Igeo values ranged from -1.04 to 2.07. For all sampling sites, the roots (0.98-5.60μg/g dw) showed the highest U accumulation followed by leaves (0.41-1.91μg/g dw) and stems (0.28-1.28μg/g dw). The correlation analysis based on U concentrations between the three parts of the plant and soils were found to be significant (P< 0.05) withstems-soils, R= 0.846; leaves-soils, R= 0.775; roots-soils, R= 0.786. Based on the transplantation study under field and laboratory conditions, U concentrations in the leaves, stems and roots of C. asiatica were significantly higher (P< 0.05) after three weeks of exposure in polluted soils. After three weeks of back transplantation to clean soils, the U levels in the three parts were still higher than the initial U levels even though elimination of U occurred. Based on correlation study from sampling sites and transplantation study, the results suggested that the leaves, stems and roots of C. asiatica are good bio indicators of U pollution in soil
    Full-text · Article · Dec 2013 · Journal of Sustainability Science and Management
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    G H Ong · C K Yap · M Maziah · S G Tan
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    ABSTRACT: This study was carried out by using Centella asiatica grown using a hydroponic system under laboratory conditions to study synergistic and antagonistic effects of Zn bioaccumulation with added Pb and the changes in antioxidant activities in leaves and roots of C. asiatica. The antioxidant activities included superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and guaiacol peroxidase (GPX). The treatments Zn (2 ppm) + Pb (0.4 ppm) and Zn (4 ppm) + Pb (0.6 ppm) increased the accumulation of Zn in leaves by 14.06 and 16.84%, respectively, but decreased by 7.36% uptake in roots (Zn 4 ppm + Pb 0.6 ppm). This showed that Pb and Zn acted synergistically to Zn accumulation in leaves but antagonistically in roots. CAT and SOD activities in leaves were increased when Zn was added together with Pb. In roots, CAT, APX and SOD activities were increased but GPX was decreased. Owing to their sensitivities to Zn with Pb, SOD and CAT could be used as biomarkers to monitor the toxicity of Pb and Zn exposure in the leaves and roots of C. asiatica.
    Full-text · Article · Nov 2013 · Sains Malaysiana
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    G.H. Ong · C.K.Yap · M. Marziah · S.G. Tan
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    ABSTRACT: Antioxidative enzymes have been claimed as being beneficial for enhancing fitness and for preventing disorders in plants due to the production of reactive oxygen species (ROS) caused by heavy metal stresses. Centella asiatica plants and soil sediments from nine sampling sites were collected between May and June of 2010. They were tested for their Cd, Cu, Fe, Ni, Pb and Zn contents. The plants were also analyzed for the activities of antioxidative enzymes namely superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and guaiacol peroxidase (GPX). This study revealed positive and significant (P<0.05) correlations between plants (leaves and roots) and soils for Cd, Zn, Ni and Fe content. It also showed that the significant correlations between Cd, Fe and Pb accumulations did not seem to be a factor for the increase in antioxidative enzyme activities due to their low concentrations in the plant; but the accumulated Cu, Zn and Ni levels were significantly (P<0.05) correlated with increases in antioxidative activities
    Full-text · Article · Nov 2013 · Pertanika Journal of Tropical Agricultural Science
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    Utama · C K Yap · W H Cheng · C C Ong · S G Tan
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    ABSTRACT: A total of 19 polymorphic microsatellite loci were used to analyze the levels of genetic variations for six geographical populations of green-lipped Perna viridis collected from the coastal waters of Peninsular Malaysia. In addition, the total soft tissues of all mussel populations were determined for heavy metals (Cd, Cu, Pb and Zn). F ST values revealed that all the six populations of P. viridis in Peninsular Malaysia were categorized as showing 'moderate genetic differentiation' according to the classification of Wright (1978). Cluster analysis revealed that three populations which were located in the western part of the Johor Causeway were clustered differently from the other three populations located in the eastern part. Hierarchical F-statistics and cluster analysis indicated that the Johor Causeway which blocked the free flow of the pelagic larvae swimmers of P. viridis and a distinct effect of heavy metal contamination on the Kg. Pasir Puteh population, were the two main causal agents for the genetic differentiation of the P. viridis populations investigated in this study. ABSTRAK Sejumlah 19 lokus mikrosatelit yang berpolimorfik telah digunakan untuk menganalisis tahap variasi genetik bagi enam populasi geografi kupang Perna viridis yang disampel dari persisiran pantai Semenanjung Malaysia. Keseluruhan tisu lembut daripada kesemua populasi juga ditentukan untuk logam berat (Cd, Cu, Pb dan Zn). Nilai F ST menunjukkan kesemua enam populasi P. viridis di Semenanjung Malaysia dikategorikan sebagai 'perbezaan genetik yang sederhana' mengikut klasifikasi Wright (1978). Analisis kluster menunjukkan bahawa tiga populasi yang berada di bahagian barat Tambak Johor telah diklusterkan berasingan daripada tiga lagi populasi yang berada di bahagian timur. F-statistik
    Full-text · Article · Nov 2013 · Sains Malaysiana
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    ABSTRACT: In this study, Centella asiatica and surface soils were collected from 12 sampling sites in Peninsular Malaysia, and the barium (Ba) concentrations were determined. The Ba concentration [μg/g dry weight (dw)] was 63.72 to 382.01 μg/g in soils while in C. asiatica, Ba concentrations ranged from 5.05 to 21.88 μg/g for roots, 3.31 to 11.22 μg/g for leaves and 2.37 to 6.14 μg/g for stems. In C. asiatica, Ba accumulation was found to be the highest in roots followed by leaves and stems. The correlation coefficients (r) of Ba between plants and soils were found to be significantly positively correlated, with the highest correlation being between roots-soils (r=0.922, p<005), followed by leaves-soils (r=0.890, p<005) and stems-soils (r=0.848, p<005). This indicates that these three parts of C. asiatica are good biomonitors of Ba pollution. For the transplantation study, four sites were selected as unpolluted [(Universiti Putra Malaysia (UPM)], semi-polluted (Seri Kembangan and Balakong) and polluted sites (Juru). Based on the transplantation study under experimental field and laboratory conditions, Ba concentrations in C. asiatica were significantly (p<0.05) higher after three weeks of exposure at Seri Kembangan, Balakong and Juru. Thus, these experimental findings confirm that the leaves, stems and roots of C. asiatica can reflect the Ba levels in the soils where this plant is found. Three weeks after back transplantation to clean soils, the Ba levels in C. asiatica were still higher than the initial Ba level even though Ba elimination occurred. In conclusion, the leaves, stems and roots of C. asiatica are good biomonitors of Ba pollution.
    Full-text · Article · Aug 2013
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    ABSTRACT: Suspicious hybrids of painted storks and milky storks were found in a Malaysian zoo. Blood of these birds was sampled on FTA cards for DNA fingerprinting. Of 44 optimized primers, 6 produced diagnostic markers that could identify hybrids. The markers were based on simple, direct PCR-generated multilocus banding patterns that provided two sets of genetic data, one for each of the two stork species and another for the hybrids. It also revealed that large DNA fragments (3,000 bp) could be amplified from blood collected on FTA cards. When the results of each individual bird's DNA fingerprint were compared with plumage characters, the hybrids were found to express a range of intermediate phenotypic traits of the pure breeds with no dominant plumage characteristic from either parental species.
    Full-text · Article · Jul 2013 · Biochemical Genetics
  • C.K. Yap · W.H. Cheng
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    ABSTRACT: This study focused on the distributions of Cd, Cu, Fe, Ni, Pb and Zn in the various tissues (shell, operculum, muscle, digestive cecum, foot, cephalic tentacles, mantle, radular and remainder) of the mangrove snail Nerita lineata collected from Sungai Janggut, Selangor. Copper and Zn levels in all soft tissues were found to exceed those in the sediment, indicating bioaccumulation of these metals. Fe levels in all soft tissues of the snails were found to be lower than those in the sediment even though Fe is the most abundant metal among the six metals investigated. Cd and Pb levels in soft tissues were also found to be lower than those in the sediment but opposite trends were observed for Cd and Pb levels in the shells. Ni, Cd and Pb levels in the shells were significantly (p< 0.05) higher than those in the soft tissues and sediment. However, digestive cecum and remainder showed higher Ni level as compared with sediment. The biota sediments accumulation factor (BSAF) has identified that the shell and operculum were macroconcentrators for Cd, Ni and Pb while all the soft tissues of N. lineata were macroconcentrators for Cu (except for muscle) and Zn. The findings indicated that the differences in metal distribution could be attributed to the differences in tissue physiology and metal handling, storage and detoxification strategies.
    No preview · Article · May 2013 · Sains Malaysiana
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    Full-text · Article · Apr 2013 · Journal of Genetics
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    ABSTRACT: The spatial distribution of 19 polycyclic aromatic hydrocarbons (tPAHs) was quantified in aquacultures located in intertidal mudflats of the west coast of Peninsular Malaysia in order to investigate bioaccumulation of PAH in blood cockles, Anadara granosa (A. granosa). Fifty-four samples from environmental matrices and A. granosa were collected. The sampling locations were representative of a remote area as well as PAH-polluted areas. The relationship of increased background levels of PAH to anthropogenic PAH sources in the environment and their effects on bioaccumulation levels of A. granosa are investigated in this study. The levels of PAH in the most polluted station were found to be up to ten-fold higher than in remote areas in blood cockle. These high concentrations of PAHs reflected background contamination, which originates from distant airborne and waterborne transportation of contaminated particles. The fraction and source identification of PAHs, based on fate and transport considerations, showed a mix of petrogenic and pyrogenic sources. The relative biota-sediment accumulation factors (RBSAF), relative bioaccumulation factors from filtered water (RBAFw), and from suspended particulate matter (SPM) (RBAFSP) showed higher bioaccumulations of the lower molecular weight of PAHs (LMWs) in all stations, except Kuala Juru, which showed higher bioaccumulation of the higher molecular weight of PAHs (HMWs). Calculations of bioaccumulation factors showed that blood cockle can accumulate PAHs from sediment as well as water samples, based on the physico-chemical characteristics of habitat and behaviour of blood cockles. Correlations among concentrations of PAHs in water, SPM, sediment and A. granosa at the same sites were also found. Identification of PAH levels in different matrices showed that A. granosa can be used as a good biomonitor for LMW of PAHs and tPAHs in mudflats. Considering the toxicity and carcinogenicity of PAHs, the bioaccumulation by blood cockles are a potential hazard for both blood cockles and their consumers.
    No preview · Article · Apr 2013 · Science of The Total Environment