Scope of research

The Biotechnology Unit undertakes research in the areas of Hevea tissue culture and genetic transformation, molecular markers and genetics, physiology, biochemistry and molecular biology, transcriptomics and latex allergy, with the aim to contribute towards increasing productivity and competitiveness of the Malaysian rubber industry. While the scope of research at the Unit encompasses mainly the basic and strategic biological research activities, a significant portion of the Unit’s research has been structured to address specific needs of the rubber industry.

Senior research staff

Azlina Bahari M.Sc.	abahari@lgm.gov.my
Badrul Ezam Badaruddin B.Sc. (Hons)	ezam@lgm.gov.my
Chow Keng See Ph.D.	kschow@lgm.gov.my
Nurul Hainiza Abdul Razak B. Eng.	hainiza@lgm.gov.my
Nor Azreen Abd Rahman M.Sc.	norazreen@lgm.gov.my
Nor Mayati Che Husin M. Sc. (on study leave)	normayati@lgm.gov.my
Roslinda Sajari Ph.D.	roslinda@lgm.gov.my
Safiah Atan Ph.D.	safiah@lgm.gov.my
Siti Shuhada Shuib B.Sc. (Hons) (on study leave)	shuhada@lgm.gov.my
E. Sunderasan Ph.D.	sunderasan@lgm.gov.my
Siti Arija Mad Arif Ph.D. (Head of Unit)	sitiarija@lgm.gov.my

Major research activities

Tissue Culture and Genetic Transformation

The technique of tissue culture is being harnessed to meet the needs of genetic transformation of Hevea brasiliensis. The main objective of genetic transformation is to enhance crop productivity by improving selected agronomic traits of the rubber tree. Two characteristics of the rubber tree that could benefit from transgenics are in girth increment for timber production and in resistance to diseases, particularly Corynespora leaf disease. Genes of interest are inserted into in vitro cultured anther callus tissue, the process being aided by a bacterium (Agrobacterium). The genetically transformed callus is subsequently regenerated into a complete plantlet though tissue culture.

Genetically transformed rubber tree can also be coaxed to produce commercially valuable proteins in the latex. Genes encoding proteins of commercial value are inserted into rubber trees that then become natural "factories" for the production of the foreign proteins. Examples of such proteins are pharmaceuticals and proteins used in personal care products. Foreign (recombinant) proteins synthesised in the latex in this manner are extracted continually and non-destructively by tapping the tree. Transgenic rubber trees require low maintenance and are environment-friendly as compared with bioreactor systems by which many pharmaceuticals are currently being manufactured. Experimental transgenic rubber trees have successfully produced a bacterial enzyme (GUS), a mouse antibody and human serum albumin.

[Click here] More about the transgenic rubber tree as a living factory for the production of valuable proteins.

Another aspect of genetic transformation under active research concerns the use of endogenous promoters (sequences of genomic DNA that drive gene action) that function in specific tissues of the transgenic rubber tree. One promising candidate promoter for latex vessel-specific expression is the hevein gene promoter. (Hevein is one of the most abundant proteins in latex.) In a recent study, the cDNA of the GUS protein was linked to hevein promoters and used in Hevea genetic transformation. GUS activity was observed in the regenerated rubber plants.

A transgenic rubber plant regenerated via tissue culture.
	Blue colouration of the latex (left) from the transformed plant after reacting with the GUS substrate. Latex from the control untransformed plant remains uncoloured.

Publications

E. SUNDERASAN, and SITI ARIJA M. ARIF. Genetic transformation of rubber tree for the production of pharmaceuticals and improved agronomic traits. Paper presented at Seminar on Application of Transgenic Technology in Agriculture, 13 December 2010, UPM Serdang, Selangor.

YEANG, H.Y., AROKIARAJ, P., JAAFAR, H., ARIF, S.A.M., RAJAMANIKAM, S., CHAN, J.L., SHARIB, J., LEELAVATHY, R., HAMZAH, S. and VAN DER LOGT, C.P.E. (2002) Expression of a functional recombinant antibody fragment in the latex of transgenic Hevea brasiliensis. Journal of Rubber Research, 5(4), 215-25.

AROKIARAJ, P., RUEKER, F, OBERMAYR, E., SHAMSUL BAHRI, A.R., HAFSAH JAAFAR, CARTER, D.C. and YEANG, H.Y. (2002) Expression of human serum albumin in transgenic Hevea brasiliensis. Journal of Rubber Research, 5(3), 157-66.

AROKIARAJ, P., YEANG, H.Y., CHEONG, K.F., SAMSIDAR HAMZAH, JONES, H. AND COOMBER, S. and CHARLWOOD, B.V. (1998) CaMV 35S promoter directs ß-glucuronidase (GUS) expression in the laticiferous system of transgenic Hevea brasiliensis (rubber tree). Plant Cell Reports, 17, 621-5.

AROKIARAJ, P., JONES, H., HAFSAH JAAFAR, COOMBER, S. and CHARLWOOD, B.V. (1996) Agrobacterium-mediated transformation of Hevea anther calli and their regeneration into plantlets. Journal of Natural Rubber Research, 11(2), 77-86.

Molecular Markers and Genetics

Molecular markers serve as useful aids in understanding the Hevea genetics, particularly in genotype selection and can hence facilitate and hasten the progress in breeding. Several molecular marker systems have been attempted in the genotyping H. brasiliensis, such as Restriction Fragment Length Polymorphism (RFLP), Random Amplified Polymorphic DNA (RAPD), DNA Amplified Fragments (DAF) and Amplified Fragment Length Polymorphism (AFLP). Among these, the AFLP system has been successful in producing a number of genetic maps of H. brasiliensis clones RRIM 937, RRIM 600, PB 5/51 and IAN 873. Meanwhile, Quantitative Trait Loci (QTL) map for susceptibility/resistance to the pathogenic fungus Corynespora cassiicola is currently underway. The genetic and QTL maps are being enhanced by the discovery of Single Nucleotide Polymorphisms (SNPs).

Publications

SAFIAH ATAN, SUHAILA DERAPI, LIZAWATI ISMAIL, NOR AINI AB. SHUKOR (2011). Screening of Hevea progenies (PB5/51 x IAN873) with two races of Corynespora cassiicola. Journal of Rubber Research, 14(2), 110-122.

SAFIAH ATAN and NOOR HISHAM HAMID (2003) Differentiating races of Corynespora cassiicola using RAPD and internal transcribed spacer markers. Journal of Rubber Research, 6(1), 58-64.

LEITCH, A.R., LIM,Y.K., LEITCH, I.J., O’NEILL, M., CHYE, M.L. and LOW, F.C.(1998) Molecular cytogenetic studies in rubber Hevea brasiliensis L. (Euphorbiaceae). Genome 41, 464-7.

YEANG, H.Y., SUNDERASAN, E., WICKNESWARI, R., NAPI, D. and ZAMRI, A.S.M. (1998) Genetic relatedness and identities of cultivated Hevea clones determined by isozymes. Journal of Rubber Research, 1(1), 35-47.

LOW, F.C., SAFIAH ATAN, HAFSAH JAAFAR and TAN, H. (1996) Recent advances in the development of molecular markers for Hevea studies. Journal of Natural Rubber Research, 11(1), 32-44.

SAFIAH ATAN, LOW, F.C. and SALEH, N..M. (1996) Construction of a microsatellite-enriched library from Hevea brasiliensis. Journal of Natural Rubber Research, 11(4), 247-55.

Plant Physiology, Biochemistry and Molecular Biology

In Hevea physiology and biochemistry, particular focus is given to mechanisms that control the production of rubber. The molecular, biochemical and cellular aspects of key enzymes regulating rubber biosynthesis are being elucidated. The main focus has been on genes and proteins related to the final steps of rubber biosynthesis and more recently, on pathways of substrate supply for rubber formation. Studies on latex genes and proteins that are induced by ethylene treatment have also been undertaken.

In addition to earlier research on latex Expressed Sequence Tags (ESTs), second generation sequencing and bioinformatics has been adopted for transcriptome analysis of latex, leaf and bark. The generation of these transcriptomes is to enable characterisation of tissue-specific sequences and genome sequence annotation.

Publications

KENG-SEE CHOW, MOHD.-NOOR MAT-ISA, AZLINA BAHARI, AHMAD-KAMAL GHAZALI, HALIMAH ALIAS, ZAINORLINA MOHD.-ZAINUDDIN, CHEE-CHOONG HOH, KIEW-LIAN WAN (2011). Metabolic routes affecting rubber biosynthesis in Hevea brasiliensis latex. Journal of Experimental Botany, doi: 10.1093/jxb/err363.

KMA DARULIZA, KL LAM, KL YANG, JT PRISCILLA, E SUNDERASAN, MT ONG. (2011) Anti-Candida albicans activity and brine shrimp lethality test of Hevea brasiliensis latex B-serum. European Review for Medical and Pharmacological Sciences, 15(10), 1158-1162.

KMA DARULIZA, KL LAM, KL YANG, JT PRISCILLA, E SUNDERASAN, MT ONG. (2011) Specific anti-fungal effect of Hevea brasiliensis latex C-serum on Aspergillus niger. European Review for Medical and Pharmacological Sciences, 15(9), 1027-1033.

AZLINA BAHARI, KENG-SEE CHOW. (2011) Real Time RT-PCR as a Tool for Quantitative Hevea Gene Expression Studies. Journal of Rubber Research, 14(1), 51-64.

NGUYEN ANH NGHIA, JUGAH KADIR, E. SUNDERASAN, MOHD. PUAD ABDULLAH, SUHAIMI NAPIS (2010) Identification and diversity analyses of Corynespora cassiicola isolates using rDNA ITS sequence markers. Journal of Rubber Research, 13(4), 257-264.

MALIK A, FIROZ A, JHA V, E. SUNDERASAN, AHMAD S. (2010) Modeling the three dimensional structures of unbound single-chain variable fragment (scFv) and its hypothetical complex with Corynespora cassiicola toxin, cassiicolin. Journal of Molecular Modelling, 16, 1883–1893.

MOHD-NOOR MAT-ISA, KENG-SEE CHOW, AHMAD-FUAD-HILMI MOHAMAD, MOHD-YUNUS SHAHRUM, CHEE-CHOONG HOH, MOHD-RASDI MOHD-AMIN, KHAIRIL-ANUAR ZAINAL, HOONG-YEET YEANG, KIEW-LIAN WAN (2009). NRESTdb: Access to the Transcriptome of Natural Rubber Latex. Journal Rubb Res, 12(4), 229-238.

M.T. ONG, K.L. YANG, K.L. LAM, G.A. ONG, AND E. SUNDERASAN. (2009) Susceptibility of HeLa (cancer-origin) cells to a sub-fraction of latex B-serum. Journal of Rubb Res, 12(3), 117-124.

E. SUNDERASAN, ABDUL KADIR R, PUJADE-RENAUD V, FREDERIC de LAMOTTE, YEANG HY. AND NATHAN S. (2009) Single-chain variable fragments antibody specific to Corynespora cassiicola toxin, cassiicolin, reduces necrotic lesion formation in Hevea brasiliensis. Journal of General Plant Pathology, 75, 19-26.

NGHIA NA, KADIR J, SUNDERASAN E, ABDULLAH MP., ADAM MALIK, AND NAPIS S. (2008) Morphological and Inter Simple Sequence Repeat (ISSR) markers analyses of Corynespora cassiicola isolates from rubber plantations in Malaysia. Mycopathologia, 166:189-201.

SUNDERASAN, E., LING, S.K., SITI ARIJA MAD ARIF AND YEANG, H.Y. (2007) Deciphering Rubber Particle Destabilisation by Hevea Bark Extract. J Rubb Res 10(2) 89-98.

CHOW, K.S., WAN, K.L., ISA, M.N.M., BAHARI, A., TAN, S.H., HARIKRISHNA, K. AND YEANG, H.Y. (2007) Insights into rubber biosynthesis from transcriptome analysis of Hevea brasiliensis latex. J. Exp. Bot. 58(10): 2429–2440.

KENG-SEE CHOW, FARIDAH YUSOF, SALIMAH MOHD. LIM AND LATIFAH ABDULLAH (2006). An Assessment of Stimulation of Hevea brasiliensis Rubber Biosynthesis by eIF-5A Protein-enriched Bacterial Lysates. Journal of Rubber Research 9(4): 251-259.

AROKIARAJ, P. AND YEANG H.Y. (2006) Yield stimulation of the rubber tree (RRIM 600) with Ethephon does not increase Latex Hev b6 Protein or mRNA. Journal of Rubber Research 9(1), 61-71.

PUJADE-RENAUD, V., SANIER, C., CAMBILLAU, L., PAPPUSAMY, A., JONES, H., RUENGSRI, N., CHRESTIN, H., THARREAU, D., MONTORO, P. AND NARANGAJAVANA, J. (2005) Molecular characterisation of new members of the Hevea brasiliensis hevein multigene family and analysis of their promoter region in rice. Biochimica et Biophysica Acta,1727(3),151-61.

YEANG, H.Y. (2005) The kinetics of latex flow from the rubber tree in relation to latex vessel plugging and turgor pressure. Journal of Rubber Research, 8(3), 160-81

KO, J.H., CHOW, K.S. and HAN, K.H. (2003) Transcriptome analysis reveals novel features of the molecular events occurring in the laticifers of Hevea brasiliensis (para rubber tree). Plant Molecular Biology, 53(4), 479-92.

K.-S. CHOW, SALIMAH M. LIM and K.-H. HAN (2003) Characterisation of a family of eIF-5A cDNAs from Hevea brasiliensis. Journal of Rubber Research, 6(2), 107-120.

SUNDERASAN, E., WARD, M.A. and YEANG, H.Y. (2002) Isolation and characterisation of latex cyanogenic glucosidase. Journal of Rubber Research, 5(4), 244-52.

SIVAKUMARAN, S., GHANDIMATHI, H., ZAINAB HAMZAH, FARIDAH YUSOF, SAMSIDAR HAMZAH and YEANG, H.Y. (2002) Physiological and nutritional aspects in relation to the spontaneous development of tapping panel dryness in clone PB 260. Journal of Rubber Research, 5(3), 135-56.

BOKMA, E., SPIERING, M., CHOW, K.S., MULDER, P.M.F., SUBROTO, T. and BEINTEMA, J.J. (2001). Determination of cDNA and genomic DNA sequences of hevamine, a chitinase from the rubber tree Hevea brasiliensis. Plant Physiology and Biochemistry, 39, 367-76.

YUSOF, F., CHOW, K.S., WARD, M. and WALKER, J.M. (2000) A stimulator protein of rubber biosynthesis from Hevea brasiliensis latex, Journal of Rubber Research, 3(4), 193-210.

LUO, S., XIAO, X., HAMZAH, S. and YEANG, H.Y. (2000) Hev b3 in latex from TPD rubber trees. Chinese Journal of Tropical Crops, 21(2), 7-11.

SAMSIDAR HAMZAH, XIAO, X., LUO, S., CHAN, J.L. and YEANG, H.Y. (2000) Protein marker for tapping panel dryness identified as the small rubber particle protein (Hev b 3). Journal of Rubber Research, 3(1), 42-52.

HAN K.H., SHIN D.H., YANG J., KIM I.J., OH S.K. and CHOW K.S. (2000) Genes expressed in latex of Hevea brasiliensis. Tree Physiology, 20, 503-510.

SHIN, D.H., YANG, J., CHOW, K.S. and HAN, K.H. (1999) A Hevea brasiliensis homolog of DnaJ (HvDnaJ) is expressed abudantly in latex and induced by ethylene (Accession No. AF085275) (PGR99-004). Plant Physiology 119, 363.

CHOW, K.S. (1999) Cloning of a thioredoxin h cDNA from Hevea brasiliensis (Accession No. AFF133127) (PGR99-059). Plant Physiology 120:339.

OH, S.K., KANG, H., SHIN, D.H., YANG, J., CHOW, K.S., YEANG, H.Y., WAGNER, B., BREITENEDER, H. and HAN, K.H. (1999) Isolation, characterisation and functional analysis of a novel cDNA clone encoding a small rubber particle protein from Hevea brasiliensis. Journal of Biological Chemistry 274(24):17132-8.

FARIDAH YUSOF, AUDLEY, B.G., ISMAIL, F. and WALKER, J.M. (1998) A rapid assay for the incorporation of isopentenyl diphosphate in rubber biosynthesis. Journal of Rubber Research, 1(1), 48-66.

FARIDAH YUSOF, WARD, M.A. and WALKER, J.M. (1998) Purification and characterisation of an inhibitor of rubber biosynthesis from C-serum of Hevea brasiliensis latex, Journal of Rubber Research, 1(2), 95-110.

SHAMSUL BAHRI, A.R. and SAMSIDAR HAMZAH (1996) Immunocytochemical localisation of rubber membrane protein in Hevea latex. Journal of Natural Rubber Research, 11(2), 88-95.

YEANG, H.Y. and OTHMAN HASHIM (1996) Destabilisation of lutoids in Hevea brasiliensis latex during early and late flow. Journal of Natural Rubber Research, 11(1), 45-58.

FARIDAH YUSOF, M.A. SITI ARIJA, GHANDIMATHI, H., ZAINAB HAMZAH, SIVAKUMARAN, S. and YEANG, H.Y. (1995) Changes in some physiological latex parameters in relation to the onset of induced tapping panel dryness. Journal of Natural Rubber Research, 10(3), 182-98.

YEANG, H.Y., YIP, E. and SAMSIDAR HAMZAH (1995) Characterisation of Zone 1 and Zone 2 rubber particles in Hevea brasiliensis latex. Journal of Natural Rubber Research, 10(2), 108-23.

Latex Allergy

Natural rubber latex is used in the manufacture of a wide range of latex goods, the most important being products related to healthcare such as examination gloves. In the recent past, many reports implicated certain proteins found on gloves and other surgical aids made from latex can induce allergenicty in sensitised persons. The problem of latex allergy is therefore of direct concern both to the manufacturers and consumers of latex goods.

To resolve the problem of latex allergy, effort has been made to quantitate the very low concentrations of residual proteins in latex goods and to understand the nature and behaviour of such proteins. In addition, a number of major allergens have been isolated, purified, their corresponding antibody obtained, and the encoding genes (cDNA) cloned. Currently efforts are undertaken to develop diagnostic kit that could serve as a valuable tool in the quality control of manufactured latex gloves.

The Latex Allergens

There are 13 recognised latex allergens (proteins that cause allergy) named Hev b 1 to Hev b 13 according to the nomenclature of the International Union of Immunological Societies and the World Health Organisation. Find out more about the latex allergens...

•	Which latex allergens are most commonly responsible for sensitisation to natural rubber latex?
•	Do diagnostic reagents used in skin prick test contain all the main latex allergens?
•	Which is the most potent latex allergen?
	3D model structure of Hev b 4, a glycosylated latex allergen

Publications

A. MALIK, SITI ARIJA M. ARIF, S. AHMAD AND E. SUNDERASAN. (2008) A molecular and in silico characterisation of Hev b 4, a glycosylated latex allergen. Int. J. Biol. Macromolecules. 42(2) 185-190.

Yeang H.Y., S.A.M. Arif, Loke Y.H., Chew N.P. and Mohsin S.M. (2007) Electrophoretic Characterisation of Hevein. J. Rubb. Res. Vol 10(4), 2007, p. 235-244.

M. RAULF-HEIMSOTH, HP RIHS, P. ROZYNEK, R. CREMER, A. GASPAR, G. PIRES, H.Y. YEANG, S.A.M. ARIF, R.G. HAMILTON, I. SANDER, M. LUNDBERG, T. BRÜNING (2007) Quantitative analysis of IgE reactivity profiles in patients allergic or sensitized to natural rubber latex (Hevea brasiliensis). Clin Exp Allergy; 37 (11); 1657-67.

SMITH AM, AMIN HS, BIAGINI RE, HAMILTON RG, ARIF SA, YEANG HY AND BERNSTEIN DI (2007) Percutaneous reactivity to natural rubber latex proteins persists in health-care workers following avoidance of natural rubber latex. Clin Exp Allergy; 37 (9); 1349-56.

S. WAGNER, M. BUBLIN, C. HAFNER, T. KOPP, D. ALLWARDT, U. SEIFERT, S.A. ARIF, O. SCHEINER AND H. BREITENEDER (2007). Generation of Allergen-Enriched Protein Fractions of Hevea brasiliensis Latex for in vitro and in vivo Diagnosis Int Arch Allergy Immunol 2007 , 143 : 246–254

YEANG, H.Y., HAMILTON, R.G., BERNSTEIN, D.I., ARIF, S.A.M., CHOW, K.S., LOKE, Y.H., RAULF HEIMSOTH, M., WAGNER, S., BREITENEDER, H., BIAGINI, R.E. (2006) Allergen concentration in natural rubber latex. Clinical and Experimental Allergy 36, 1078-1086.

ARIF, S.A.M., HAMILTON R.G. AND YEANG, H.Y. (2006) IgE antibody binding to the carbohydrate moiety of Hev b 13, Journal of Rubber Research 9(1) , 40-49.

KOLARICH, D, ALTMANN, F. AND SUNDERASAN, E. (2006) Structural analysis of the glycoprotein allergen Hev b 4 from natural rubber latex by mass spectrometry. Biochimica et Biophysica Acta , 1760(4), 715-20.

SUNDERASAN, E., BAHARI, A., ARIF, S.A.M., ZAINAL, Z., HAMILTON, R.G., and YEANG, H.Y. (2005) Molecular cloning and immunoglobulin E reactivity of a natural rubber latex lecithinase homologue, the major allergenic component of Hev b 4. Clinical and Experimental Allergy , 35, 1490-5.

KURUP, V.P., SUSSMAN, G.L., YEANG, H.Y., ELMS, N., BREITENEDER, H., ARIF, S.A.M., KELLY, K., BANSAL, N.K. and FINK, J.N. (2005) Specific IgE response to purified and recombinant allergens in latex allergy. Clin Mol Allergy , 3, 11.

JOHAR, A., LIM, D., ARIF, S.A.M., HAWARDEN, D., DU TOIT, G., WEINBERG, E.G., MOTALA, C., FIEGGEN, G., YEANG, H.Y. and POTTER, P.C. (2005) Low prevalence of latex sensitivity in South African spina bifida children in Cape Town. Pediatric Allergy and Immunology,16(2), 165-70.

YEANG, H.-Y. and CHOW, K.-S. (2004) DNA cloning of Hev b 2 (Hevea latex ß-1,3-glucanase) and IgE reactivity of the recombinant protein. Journal of Rubber Research 2004 7(3) :180-7.

YEANG, H.-Y., ARIF, S.A.M., RAULF-HEIMSOTH, M., LOKE, Y.-H., SANDER, I., SULONG, S.H., LAU, C.-H., and HAMILTON, R.G. (2004) Hev b 5 and Hev b 13 as allergen markers to estimate the allergenic potency of latex gloves. Journal of Allergy and Clinical Immunology , 114(3) , 593-8.

ARIF, S.A.M., HAMILTON, R.G., YUSOF, F., CHEW, N.-P., LOKE, Y.-H., NIMKAR, S., BEINTEMA, J.J. and YEANG, H.Y. (2004) Isolation and characterisation of the Early Nodule Specific Protein homologue (Hev b 13), an allergenic lipolytic esterase from Hevea brasiliensis latex. Journal of Biological Chemistry, 279(23) :23933-41.

YEANG, H.Y. (2004) Natural rubber latex allergens: new developments, Current Opinion in Allergy & Clinical Immunology , 4(2) , 99-104.

BERNSTEIN, D.I., BIAGINI, R.E., KARNANI, R., HAMILTON, R , MURPHY, K., BERNSTEIN, C., ARIF, S. A.., BRENDTS, B. and YEANG, H.Y. (2003) In vitro sensitization to purified Hevea brasiliensis proteins in health-care workers sensitized to natural rubber latex. Journal of Allergy and Clinical Immunology , 111(3) , 610-6.

YEANG, H.Y., LAU, C.H., SITI ARIJA M. ARIF, LOKE, Y.H., CHAN, J.L., SAMSIDAR HAMZAH and HAMILTON, R.G. (2002) Hev b 1, Hev b 2 and Hev b 3 Contents in Natural Rubber Latex and Powdered Latex Gloves. Journal of Rubber Research , 5(3), 167-78.

YEANG, H.Y., ARIF, S.A.M., YUSOF, F. and SUNDERASAN, E. (2002) The allergenic proteins of natural rubber latex. Methods. 27(1) , 32-45.

IKRAM, A., BAHRI, A.R.S., FAUZI, M.S. and NAPI, N. (2001) Effects of added nitrogen and phosphorus on the biodegradation of NR gloves in soil. Journal of Rubber Research , 4 , 102-17.

YEANG, H.Y., CHOW, K.S., YUSOF, F., ARIF, S.A.M., CHEW, N.P. and LOKE, Y.H. (2000) Appraisal of latex glove proteins in the induction of sensitivity to multiple latex allergens. Journal of Investigational Allergology & Clinical Immunology , 10(4) , 215-22.

YEANG, H.Y. (2000) Prevalence of latex allergy may be vastly over-estimated when determined by in vitro assays. Annals of Allergy , Asthma & Immunology , 84 , 628-32.

KURUP,V.P., YEANG, H.Y., SUSSMAN, G.L., BANSAL, N.K, BEEZHOLD, D.H., KELLY, K.J., HOFFMAN, D.R., WILLIAMS, B. and FINK, J.N. (2000) Detection of IgE in the sera of patients using purified latex allergens. Clinical and Experimental Allergy , 30(3) , 359-69.

JOHNSON, B.D., KURUP, V.P., SUSMAN, G.L., ARIF, S.A.M., KELLY, K.J., BEEZHOLD, D.H. and FINK, J.N. (1999) Purified and remcombinant latex proteins stimulate peripheral blood lymphocytes of latex allergic patients. International Archives of Allergy and Immunology , 120 , 270-9.

WAGNER, B., KREBITZ, M., BUCK, D., NIGGEMANN, B., YEANG, H. Y., HAN, K.H., SCHEINER, O., and BREITENEDER, H. (1999). Cloning, expression and characterisation of recombinant Hev b 3, a Hevea brasiliensis protein associated with latex allergy in spina bifida patients. Journal of Allergy and Clinical Immunology. 104(5) , 1084-92.

SOWKA, S., HAFNER, C., RADAUER, C., FOCKE, M., BREHLER, R., ASTWOOD, J. D., ARIF, S. A., KANANI, A., SUSSMAN, G. L., SCHEINER, O., BEEZHOLD, D. H., and BREITENEDER, H. (1999). Molecular and immunological characterisation of new isoforms of the Hevea brasiliensis latex allergen Hev b 7: Evidence of no cross-reactivity between Hev b 7 isoforms and potato patatin and proteins from avocado and banana. Journal of Allergy and Clinical Immunology , 104 , 1302-10.

AIRENNE, K.J., LAITINEN, O.H., ALENIUS, H., MIKKOLA, J., KALKKINEN, N., ARIF, S.A., YEANG, H.Y., PALOSUO, T. and KULOMAA, M.S. (1999) Avidin is a promising tag for fusion proteins produced in baculovirus-infected insect cells. Protein Expression and Purification , 17(1) ,139-45.

YEANG, H.Y., FARIDAH YUSOF and LATIFAH ABDULLAH (1998) Protein purification for the Lowry assay: Acid precipitation of proteins in the presence of SDS and other biological detergents, Analytical Biochemistry , 265 , 381-384.

YEANG, H.Y., WARD, M.A., ZAMRI, A.S.M., DENNIS, M.S. and LIGHT, D.R. (1998) Sequence similarity of Hev b 3 with two previously reported 27 and 23 kDa latex allergens detected by spina bifida patients. Allergy 53(5) , 513-9.

SOWKA, S. WAGNER, S., KREBITZ, M., SITI ARIJA MAD ARIF, FARIDAH YUSOF, KINACIYAN, T., BREHLER, R., SCHEINER, O. and BREITENEDER, H. (1998) cDNA cloning of the 43-kDa latex allergen Hev b 7 with sequence similarity to patatin and its expression in the yeast Pichia pastoris . European Journal of Biochemistry , 255 , 213-9.

YEANG, H.Y., CHEONG, K.F., SUNDERASAN, E., SAMSIDAR HAMZAH, CHEW, N.P., SHARIFAH HAMID, HAMILTON, R.G. and CARDOSA, M.J. (1996) The 14.6kd rubber elongation factor ( Hev b 1) and 24 kd ( Hev b 3 rubber particle proteins are recognised by IgE from patients with spina bifida and latex allergy. Journal of Allergy and Clinical Immunology , 98(3) , 628-39.

SUNDERASAN, E., SAMSIDAR HAMZAH, SHARIFAH HAMID, WARD, M.A., YEANG, H.Y. and CARDOSA, M.J. (1995) Latex B-serum -1,3-glucanase ( Hev b II) and a component of the microhelix ( Hev b IV) are major latex allergens. Journal of Natural Rubber Research , 10(2) , 82-99.

YEANG, H.Y., SUNDERASAN, E. and HAFSAH MOHD. GHAZALY (1995) Latex allergy studies: Extraction of natural rubber latex proteins with reference to film thickness, latex d.r.c. and protein migration behaviour. Journal of Natural Rubber Research , 10(1) , 46.

YEANG, H.Y., FARIDAH YUSOF and LATIFAH ABDULLAH (1995) Precipitation of Hevea brasiliensis proteins with trichloroacetic acid and phosphotungstic acid in preparation for the Lowry protein assay. Analytical Biochemistry , 226 , 35-43.