Department of Biological Sciences

Academic qualification:
BSc (Direct Honours, 1 st Class) NUS, 1984
PhD University of Cambridge, UK, 1987

Founder member of the Institute of Molecular Agrobiology (1994-1996)
Sub-Dean, Faculty of Science, NUS (1996-1998)
Director, Sepcial Programme in Science (1997/98)
Director, Bioscience Centre, NUS (1998-2000)
Deputy Head, Department of Biological Sciences, NUS, (1998-2003)
Core Curriculum, University Scholar Programme, Founding member and Area Coordinator (1999-2000)
Biosensor Focus Interest Group Founding member and leader (1999-2005)
Programme Director, JTC in-house training course 'Introduction to Life Sciences' (2000-2001)
Programme Director, DSO in-house training course 'Crash Course in Life Sciences' (2001)
Scientific Programme Chair for the joint KI-NUS Life Science Symposium 2002
Co-chair for the Singapore Institute of Biology 30 th Anniversary International Conference on Biology in Asia, 2004
Vice Dean, Faculty of Science, NUS (2003 to present)
Chairman, Department Strategic Planing Retreat, 1999-2003)
Chairman, Faculty Strategic Planning Retreat, 2004
Chairman, Non-academics Faculty Review Committee (2003-present)
Chairman, Faculty Safety and Health Management Committee (2003 to present)
Chairman, School Outreach Task Force (2003 to present)
Chairman, Faculty Alumni Relation Task Force (2003 to present)
Chairman, Science Research Programme (2003 to present)
Chairman, Science Mentorship programme (2003 to present)
Chairman, Scientific Review Committee for Singapore Science and Engineering Fair (2007)
Chairman, Faculty Task Force for 'Dinosaurs: A T. rex named Sue and friends' exhibition at the Singapore Science Centre (2006)
Co-chairman, University Task Force for 'Cultures of Creativity: Nobel Museum Centennial Exhibition' at NUS (2006/7)
President, Singapore Institute of Biology (since 2006)
Chairman , Singapore Biology Olympiad (2001-2005)
Vice Chairnan, Meridian Junior College School Advisory Board (since 2005)
Founder and Director, BioNano International Singapore Pte Ltd (since 2003)
Founder of a private Kids Club (since 1996)
Faculty Incident Commander in crisis management (since 2004)

For BL4104 and BL5204, students were challenged to develop biotechnology business plans and to present to audiences that act as venture capitalists. Students learned to make technology into business commodity; to consider marketing plans and financial strategies.

For LSM3233, a special modeling and simulation activity using plasticine clay to enable students to understand the complex process of gastrulation; and a new lab activity making use of the C. elegans round worm embryos were developed. Students were also given mini project to conduct in situ hybridiztion experiments to study gene expression in the zebrafish embryos. Students were also required to write a simulated scientific paper to raise their scientific literacy.

To deal with the large class in LSM3233, group projects using IVLE features to facilitate students independent learning and interaction was implemented.

To demonstrate the complicated process of gastrulation during embryonic development, sleeping bag was used to illustrare how gastrulation inetrnalises structures into the developing embryos.

To help school teachers teach sciences, severay special hands-on activities were designed. For example, 'show me you gut' - a fun activity to learn anatomy of the human digestive system; 'how good are you in water transport using straws'' - a game to illustrate the xylem and vascular system in plants.

Number of graduate students and post-doctoral fellows supervised/being supervised to date:

MSc

PhD

Post-doctoral Fellow

14 conferred

1 ongoing as graduate students not converted yet

8 conferred

2 submitted PhD thesis

1 passed PhD defence

1 writing up thesis

3 ongoing

Developmental Biology-cell differentiation and death; Parkinson's Diseasse; Acute Leukemia
Molecular Diagnostic-molecular sexing; DNA fingerprinting; carbon nanotube labels
Bioengineering-lab-on-chip device development

Current and previous support from ARF/BMRC or other sources within the past 5 years:

Our current investigation started off as a search for potential biomarkers and therapeutic candidates for Parkinson's disease (PD) using the proteomics approach. Several proteins were identified through this exercise and their possible involvements in the aetiology of PD were speculated. Among them, NPM stood out as the candidate for further studies due to its recently discovered interaction with the tumour suppressor p53, as well as its ability to inhibit apoptosis when overexpressed. As PD is characterised by the sudden and massive demise of the dopaminergic brain cells leading to impairment of voluntary motor control, NPM's anti-apoptotic potential lends credence to its candidacy for gene therapy or small-peptide drug delivery aiming at rescuing dopaminergic cells from premature death. However, before this aim can be fulfilled, an in-depth look into the mechanisms underlying cell death inhibition by NPM must be undertaken, in order to determine the specific inhibitory target(s) of NPM within the intricate death signalling network. This will in turn facilitate rationale small-peptide drug designing for PD therapeutics.

Another marker associated with PD is the α-synuclein (α-syn). In our study, human wild type (WT) and mutant α-syn genes were overexpressed using a Tet-on expression system in stably transfected dopaminergic MN9D cells. Their overexpression induced caspase-independent and dopamine-related apoptosis not rescued by general caspase inhibitor Z-VAD-FMK. While apoptosis due to overexpression of WT a-syn was completely abrogated by a specific tyrosine hydroxylase (TH) inhibitor, a-methyl-p-tyrosine (a-MT), the inhibitor only partially rescued apoptosis caused by overexpression of a-syn mutants. In addition, overexpression of mutants enhanced the toxicity of 1-methyl-4-phenylpyridinium (MPP +) and 6-hydroxyldopamine (6-OHDA) to MN9D cells, whereas overexpression of WT protect ed MN9D cells against MPP + toxicity, but not against 6-OHDA. We conclude that WT α-syn is beneficial to dopaminergic neurons but its overexpression in the presence of endogenous dopamine makes it a potential threat to the cells. In contrast, mutant α-syn not only caused the loss of WT protective function but also the gain-of-toxicity which becomes more serious in the presence of dopamine and neurotoxins.

The toxic mechanism of synuclein has also been studied in transient transfection cell models. MN9D and N2A cells were transfected with GFP protein and wild type, A30P and A53T mutant synuclein. We found that the A30P and A53T mutant synuclein could be toxic to MN9D and N2A cells, especially the A53T mutation. The toxicity of A53T and A30P synuclein to MN9D cells could be alleviated by TH inhibitor a-MT and toxicity to N2A cells could be aggravated by exogenous dopamine suggesting the dopamine related toxicity of mutant synuclein. Furthermore in the transient transfection MN9D and N2A cells, we also found that toxicity of synuclein was not caspase dependent. These results conform to our previous observations in stable transfected MN9D cells.

One of the key chemicals involved in the study of PD is the nature of dopamine in the mid brain neurons that lead to neurodgeneration. We have developed a novel HPLC method to analyse dopamine and its derivatives and we found that aminochrome (AM), one of the DA-quinones, is responsible for DA- induced irreversible proteasome inactivation leading to vulnerability of DA neurons and even cell demise. AM could covalently conjugate with the sulfhydryl groups of proteins or enzymes and lead to permanent irreversible inactivation. Furthermore, DA-quinones contribute more significantly to PD pathogenesis, compared with ROS such as H2O2. We aim to further study the toxic mechanism of DA-derived DA quinones related to PD. We conjecture that in DA neurons the accumulation of agents (such as iron) responsible for acceleration of DA oxidation and DA quinones production could act as triggering factors for PD onset. We intent to identify the interactions between DA quinones and some detoxification agents that have relevance to PD onset and development.

Another direction developed from our discovery of NPM and its involvement in apoptosis of neurons upon challenge with neurotoxin to emulate what might happen in the midbrain of PD brain. We believe we are the first to show its upregulation during early insult of the dopaminergic neurons using MN9D cells as a model. The novel function of NPM as an inhibitor of caspases has not been reported in literature. We are now doing domain studies to see which part of NPM interacts with caspses.

I strongly believe in trans-domain and cross-disciplinary research. The following are some examples:

This is an ongoing research with a multidisciolinary collaboration. In this project a novel carbon nanotube (CNT) derived label capable of dramatic signal amplification of nucleic acid detection and direct visual detection of target hybridization was developed. Highly sensitive colorimetric detection of human acute lymphocytic leukemia (ALL) related oncogene sequences amplified by the novel CNT-based label was demonstrated. AFM images confirmed that a monolayer of horseradish peroxidase and detection probe molecules were immobilized along the carboxylated CNT carrier. The resulting CNT labels significantly enhanced the nucleic acids assay sensitivity by at least 1000 times compared to that of conventional labels sed in enzyme-linked oligosorbent assay (ELOSA). An excellent detection limit of 1 ´ 10-12 M and a 5-order wide dynamic range of target concentration were achieved. Hybridizations using these labels were coupled to a concentration-dependent formation of visible dark aggregates. Targets can thus be detected simply with visual inspection, eliminating the need for expensive and sophisticated detection systems. The approach holds promise for ultrasensitive and low cost visual inspection and colorimetric nucleic acids detection in point-of-care and early disease diagnostic application.

The aim of the project was to design, fabricate, and demonstrate a system for the extraction of DNA from human body fluids based on micro components. Specifically, the project aimed to demonstrate DNA extraction from human blood.The deliverable for this project was a portable, miniature module for DNA extraction and purification based on microfluidics and micromachining techniques. So far three technology disclosures have been filed for patent.

The aim of this project was to design and develop a microPCR as a 'lab-on-chip' device. The device will be able to run PCR in very short time and with multiplexing feature. It was also meant to be a module system that can be integrated to the DNA extractor and a signal detector so as to make the micro-total analysis system feasible. Three USA patents have been granted for the invention. This project was nominated for NSTA award 2001

(IV) The above projects on DNA micro-extraction and micro PCR under the Biosensor Focused Interest Group were extended to a new project on ' BioMEMS nucleic acid diagnostic system' from 2003-2005, and we managed to develop a RNA extraction chip. Several patents have been filed from this work and this project was nominated for the NSTA award 2006.

(V) Tissue Engineering of an Autogenous Periodontal Transplant for the Regeneration of the Periodontium (2001 to 2006)

Regeneration by autogenous cell transplantation is one of the most promising tissue engineering technics as it has the potential to provide the ideal autogenic construct. This project aims to develop a cell culture system which allows the tissue engineering of a 3-D scaffold / periodontal fibroblast / osteoblast construct based on the PCL scaffolds developed earlier for tissue engineering bone and cartilage. Human periodontal ligament fibroblast and osteoblasts are to be obtained and seeded onto a three-dimensional scaffold. The bioresorbable template provides the necessary support for cellular proliferation, differentiation and production of extracellular matrix, facilitating the assimilation in-vivo, eventually defining the overall configuration of the new periodontium with new attachment on the previously denuded root surfaces. The project has won the graduate students several awards in conferences.