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. Genes encoding for
proteins that confer particular traits to the rubber tree 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.
An important objective of genetic transformation is the enhancement of crop productivity
by improving selected agronomic traits of the rubber tree. Two characteristics of
the rubber tree that could benefit from transgenesis are in girth increment for
timber production and in resistance to diseases, particularly Corynespora
leaf disease.
A second role for the transgenic rubber tree lies in the production of 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 protein. 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 at the Rubber Research
Institute of Malaysia have successfully produced a bacterial enzyme (GUS), a mouse
antibody and human serum albumin.
An aspect of genetic transformation under active research concerns
the use of endogenous Hevea gene promoters (sequences of DNA which 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 study,
the DNA of the gus protein was linked to hevein promoters and used in Hevea
genetic transformation. GUS expression was observed in the embryoids that were obtained.
The transgenic rubber plant.
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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
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 genetics
of Hevea brasiliensis. They can play a useful role in genotype
selection and can hence facilitate and hasten the progress in Hevea breeding.
DNA probes and markers are being used for genetic and physical
mapping, fingerprinting and detection of somaclonal variation. Currently, emphasis
is directed towards the use of Amplified Fragment Length Polymorphism (AFLP) for
mapping quantitative trait loci (QTLs), genetic linkage map construction and genotyping
rubber cultivars with promising traits/characters for latex-timber production.
Publications
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 studying Hevea biochemistry and its regulation at the whole tree and cellular levels, particular focus is given to the mechanisms that control the production of rubber. The molecular, biochemical and cellular aspects of key enzymes regulating rubber biosynthesis are being elucidated. Much of the recent work was centred on the role of proteinaceous stimulators and inhibitors in influencing the rate of rubber biosynthesis. Studies are also undertaken on the isolation, expression and characterisation of ethylene signaling pathway genes. Such genes could be important in the physiological regulation of latex flow when the rubber tree is tapped.
Another research topic receiving attention is in the area of Expressed Sequence Tags (ESTs). Short sequences of DNA isolated from the latex give a broad representation of the genes that are expressed in the latex. Genes of interest in future research could be isolated using these tags as guide gene sequences. The catalogue of genes would hence be valuable in studies on gene function and genetic regulation of Hevea physiology and biochemistry. As an example, a gene sequence coding for the enzyme of the first step of the purported alternative rubber biosynthesis pathway was identified from the MRB latex EST collection and a study on this gene is ongoing.
Publications
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.
Reproductive biology
The continuing improvement in the productivity of the rubber
tree, both in terms of latex as well as timber, owes much to its breeding and selection.
In Hevea breeding, artificial (hand) pollination plays a pivotal role in
generating new and improved cultivars. Nevertheless, problems of poor fruit-set
and non-synchronisation of flowering among different cultivars are important constraints
in breeding research. Investigations into the reproductive biology of the rubber
tree are aimed at alleviating some of these problems.
Fluorescence micrograph of a Hevea pollen tube (t) penetrating an ovule (o).
Publications
HAMZAH S., CHAN, J.L. and YEANG, H.Y. (2002) Pollen tube growth
and fruit-set success in Hevea brasiliensis hand-pollination influenced
by the choice of clone and female flower.
Euphytica,
123,
1-8.
YEANG, H.Y. and CHEVALLIER, M.H. (1999) Range of Hevea
brasiliensis pollen dispersal estimated by esterase isozyme markers. Annals
of Botany, 84, 681-4.
SAMSIDAR HAMZAH, CHAN, J.L. and YEANG, H.Y. (1999) Hevea
brasiliensis seedlings from hand-pollination using cryo-stored pollen validated
by isozymes. Journal of Rubber Research, 2(1), 62-8.
SAMSIDAR HAMZAH and CHAN, J.L. (1996) Pollen storage of Hevea.
Journal of Natural Rubber Research, 11(2), 115-24.
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 recent years, there have been many reports that certain proteins
found on gloves and other surgical aids made from latex can cause an allergy 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 proteins residual in latex goods and
to understand the nature and behaviour of such residual proteins. There is ongoing
research to isolate, purify and identify the specific allergenic proteins and to
clone the genes (cDNA) that encode them. Once the allergens are pinpointed, it would
be possible to develop diagnostics for latex allergy, immunotherapy to relieve the
effects of latex allergy and immunoassays to control the quality of manufactured
latex gloves.
Two-dimensional immunoelectrophoresis of latex glove proteins reacted with rabbit antiserum against the same proteins.
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...
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.
Misc Publications
HAMZAH S., CHAN, J.L. and YEANG, H.Y. (2002) Pollen tube growth and fruit-set success in Hevea brasiliensis hand-pollination influenced by the choice of clone and female flower. Euphytica, 123, 1-8.
YEANG, H.Y. and CHEVALLIER, M.H. (1999) Range of Hevea brasiliensis pollen dispersal estimated by esterase isozyme markers. Annals of Botany, 84, 681-4.
SAMSIDAR HAMZAH, CHAN, J.L. and YEANG, H.Y. (1999) Hevea brasiliensis seedlings from hand-pollination using cryo-stored pollen validated by isozymes. Journal of Rubber Research, 2(1), 62-8.
SAMSIDAR HAMZAH and CHAN, J.L. (1996) Pollen storage of Hevea. Journal of Natural Rubber Research, 11(2), 115-24.