C K Yap

Putra University, Malaysia, Klang, Selangor, Malaysia

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Publications (93)107.09 Total impact

  • Chee Kong Yap
    Chemosphere 07/2014; · 3.14 Impact Factor
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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.
    Pertanika Journal of Tropical Agricultural Science 02/2014; 37(1):19-38.
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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
    Pertanika Journal of Tropical Agricultural Science 11/2013; 36(4):331-336.
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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.
    Tropical life sciences research. 08/2013; 24(1):55-70.
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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.
    Biochemical Genetics 07/2013; · 0.94 Impact Factor
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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.
    Science of The Total Environment 04/2013; 454-455C:584-597. · 3.16 Impact Factor
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    Dataset: fulltext
    C K Yap, C M Chong, S G Tan
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    ABSTRACT: In this study, the green-lipped mussels Perna viridis were transplanted from a relatively unpolluted site at Kg. Sg Melayu (KSM) to a known polluted site at Kg Pasir Puteh (KPP) and an unpolluted site at Sg. Belungkor (SB). Total soft tissues of mussels were determined for Ag, As, Be, Co, Cr, Cs, Hg, Li, Mn, Se, Sr and V by using an Inductively Coupled Plasma-mass Spectrometer. After transplantation periods (2 and 6 weeks) to KPP, concentrations of As, Co, Cr, Hg, Li, Be, V, Cs, Mn and Sr increased but the concentrations of Ag and Se decreased after transplantation of 2 and 6 weeks. This indicated that KPP is almost confirmed as having the highest bioavailabilities of the above 10 metals than KSM and SB. However, the higher levels of Ag and Se found in the transplanted mussels at KSM should be investigated in future studies. After transplantation periods (2 and 6 weeks) to SB, concentrations of Co, Cr, Hg, Be, V, Cs, Se, Mn and Sr decreased but the concentrations of Ag and Li increased after transplantation of 2 and 6 weeks. This verified that SB is suitable coastal water for depuration of Co, Cr, Hg, Be, V, Cs, Se, Mn and Sr. However, higher levels of Ag and Li at SB than KSM could be attributed to unknown pollution source in the surrounding area which should merit further studies.
    Ecology, Environment and Conservation 01/2013; 19(1):27-31.
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    Journal of Genetics 01/2013; 92(1):e15-8. · 0.88 Impact Factor
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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. ABSTRAK Kajian ini telah dijalankan dengan Centella asiatica secara hidroponik dalam keadaan makmal untuk mengkaji kesan sinergistik dan antagonistik Bioakumulasi Zn ditambah dengan Pb dan perubahan dalam aktiviti antioksidan dalam daun dan akar C. asiatica. Aktiviti antioksidan termasuk superokside dimustase (SOD), katalase (CAT), peroksidase askorbat (APX) dan peroksidase guaiacol (GPX). Rawatan Zn (2 ppm) + Pb (0.4 ppm) dan Zn (4 ppm) + Pb (0.6 ppm) menunjukkan pengumpulan Zn dalam daun sebanyak 14.06 dan 16.84% masing-masing tetapi menurun sebanyak 7.36% dalam pengambilan akar (Zn 4 ppm + Pb 0.6 ppm). Ini menunjukkan bahawa Pb dan Zn bertindak secara sinergistik untuk pengumpulan Zn dalam daun tetapi antogonistik dalam akar. Aktiviti CAT dan SOD dalam daun meningkat apabila Zn ditambah bersama dengan Pb. Dalam akar, CAT, APX dan SOD telah meningkat tetapi GPX telah menurun. Disebabkan sentiviti kepada Zn dengan Pb, SOD dan CAT boleh digunakan sebagai penanda biologi untuk memantau ketoksikan pendedah Pb dan Zn dalam daun dan akar C. asiatica.
    Sains Malaysiana 01/2013; 42(11):1549-1555. · 0.41 Impact Factor
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    ABSTRACT: In this paper, the shells of mussels Perna viridis were determined for Ag, As, Be, Co, Cr, Cs, Hg, Li, Mn, Se, Sr and V, based on transplanted mussels from a known polluted site at Kg Pasir Puteh (KPP) to two relatively unpolluted sites at Kg Sg Melayu (KSM) and Sg Belungkor (SB). It was found that significant (P< 0.05) decreased levels of Ag, Li and Se were found in mussels transplanted to KSM and SB after 2 and 6 weeks. However, significant (P< 0.05) increased levels of As, Mn, Sr and V were found in mussels transplanted to KSM. In comparison between KSM and SB, decreased levels of Ag, As, Li, Mn and Sr in SB were found to be more signficant (P< 0.05) in SB than KSM. Meanwhile there was no signficant (P> 0.05) changes for Cr, Co and Hg levels for both sites after the transplantation periods. When compared to the trace metals in the total soft tissues previously reported by Eugene Ng et al. (2012), only the increased level of As based on the shells was supported by the total soft tissue of mussels. All the differences of increased and decreased levels of trace metals between soft and hard (shells) tissues after the transplantation periods from KPP to KSM and SB, is thus difficult to explain. Further studies are neccesary in the future to understand the differences of metal accumulations between issues and shells of P. viridis.
    Asian Journal of Microbiology, Biotechnology and Environmental Sciences 01/2013; 15(2013):5-8.
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    ABSTRACT: The concentrations of Cu, Fe and Pb were determined in Nerita lineata snails and sediments collected from Selangor, Negeri Sembilan and Johore between May 2010 and April 2011. This study showed variations of heavy metal accumulations in shells, opercula and soft tissues. The mean concentrations (µg/g dry weight) of Cu, Fe and Pb were 5.00, 29.97 and 50.07 for shells; 5.28, 19.50 and 49.34 for opercula; 14.94, 539.25 and 18.83 for soft tissues, respectively. The mean total (µg/ g dry weight) concentrations of Cu, Fe and Pb in the surface sediments were 19.72, 25956.14 and 46.99, respectively. Generally the results of this study were comparable with previous reports on the same species. The Pb levels of the snail samples were found to correlate well with the Pb levels in the sediments which confirmed the snail as a good biomonitor for Pb.
    Pollution Research 01/2013; 32(2):211-216.
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    ABSTRACT: Here, we described a molecular sexing method for the painted storks using dried blood on FTA cards (Whatman), P2/P8 sex-linked microsatellite primers designed by Griffiths et al. (1998), horizontal PAGE system (Yee et al. 2010) and quick silver staining protocol (Byun et al. 2009).
    Journal of Genetics 01/2013; 92(1):e15-e18. · 0.88 Impact Factor
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    ABSTRACT: The Straits of Johore is a hotspot area of metal pollution in the southern part of Peninsular Malaysia. In this study, green-lipped mussels Perna viridis were collected from three sites from the Straits of Johore in April 2011. The mussel tissues were dissected into eight parts including byssus, crystalline style, foot, gill, gonad, mantle, muscle and remainder. The total shells and all the dissected eight parts were determined for nine trace metal concentrations (Ag, As, Co, Cr, Cs, Hg, Mn, Se and Sr) by using an Inductively Coupled Plasma-Mass Spectrometer, because these nine trace metals are rarely reported in the literature from Malaysia. Based on the present data, Sr and Mn have a very different accumulation pattern in mussels when compared with other trace metals. It is also found that the byssus is highly accumulative of Co and Cr, while the shell is also highly accumulative of for Sr. When compared to the metal levels reported in the literature, the present data are considered low. Further studies are needed to confirm why Gelang Patah population had the highest levels of Ag, As, Cs, Mn and Se when compared to Senibong and Pantai Lido, based on some mussel parts. The present data in the different tissues of P. viridis are important for future reference. KEY WORDS : Trace metals, Perna viridis, The Straits of Johore. *Corresponding
    Pollution Research 01/2013; 32(1):9-19.
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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
    Sains Malaysiana 01/2013; 42(11):1557-1564. · 0.41 Impact Factor
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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
    Journal of Sustainability Science and Management 01/2013; 8(2):35-43.
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    Chee Kong Yap, Noorhaidah Arifin, Soo, Guan Tan
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    ABSTRACT: In this paper, the relationships of Cu concentrations between the snail's different soft tissues and surface sediments were evaluated by using multivariate analysis, namely cluster analysis, correlation analysis and stepwise multiple linear regression analysis. Three findings can be highlighted based on the present study. First, different concentrations of Cu were found in the different soft tissues, indicating different mechanisms of sequestration and regulations of Cu in these different tissues. By comparing the Cu concentrations in similar tissues, spatial variations of Cu were found in the different sampling sites although there was no consistent pattern of Cu in these sampling sites. Second, the digestive caecum was a better biomonitoring organ for Cu contamination. Third, higher Cu contamination might not necessarily result in higher Cu bioavailability to T. telescopium based on the cluster analysis. In general, all the different soft tissues could be used as biomonitoring tissues of Cu bioavailabilities and contamination in Malaysian intertidal mudflats provided they were statistically analyzed by using a multivariate approach. To our knowledge, this is the most comprehensive study of Cu accumulation in the different soft tissues of T. telescopium from tropical intertidal area in relation to sediment data.
    International Journal of Chemistry. 01/2013; 5(1):8-20.
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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
    Journal of Sustainability Science and Management 01/2013; 8(2):71-75.
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