Page 20 - Undergraduate Research Opportunities Program Proceedings 2017-18

School of Science
Division of Life Science

The 3xTg mouse strain was constructed by researchers to serve as a potential model for studying Alzheimer’s Disease
(AD). However, despite the genetic modification, only mild memory dysfunction and anxiety are shown by 3xTg mice and
there is no evidence of significant neurodegeneration. This is insufficient to mimic all of the human AD symptoms. To
investigate whether neurodegeneration occurs in 3xTg mice, our team took the quantitative approach of counting the
cell number of both the cortex and the hippocampus, and then made comparisons with wild type mice. The results
indicated that neurodegeneration occurred, but only in left hippocampus and right cortex.

Supervisor: HERRUP Karl / LIFS Co-Supervisor: HUNG Siu Chun / LIFS
Student: WANG Ximeng / BCB Course: UROP1100, Fall
UROP2100, Spring
ZHANG Yue / BIBU UROP1100, Fall
UROP2100, Spring

One of the critical question in neurobiology is whether cell lineage plays a major role in mammalian brain cell number
control. It is postulated that, one individual has a certain number of progenitor cells, of which each later will undergo
certain times of cell division and differentiate into all types of cells in the brain. This hypothesis can be applied to a
particular region in the brain, that is to say, the cerebellum. During the counting of cerebellar cells excluding the Purkinje
cells, it was found that clumps were responsible for large variations among different aliquots from the same sample.
Therefore, the focus shifted from improving counting techniques, which was the goal of last semester’s UROP, to solving
the clump issue. There are mainly two ways to deal with clumps. One way is to separate clumps into scattered nuclei,
the other is to estimate both the number of nuclei in one clump and the number of clumps in one cell suspension.

Modeling Mammalian Vesicle Dynamics in Yeast

Supervisor: HERRUP Karl / LIFS Co-Supervisor: BANFIELD David Karl / LIFS
Student: CHANG Yau Ming / BICH Course: UROP1100, Summer

ATM and ATR, proteins that are involved in numerous neurodegenerative diseases, were found to have cytoplasmic
functions in mammalsi and recent papers revealed their colocalization with endocytic proteins ii .To efficiently dissect its
role, we generated yeast mutants deficient in their homologues (TEL1 and MEC1, respectively) and conducted an
endocytic FM4-64 dye assay. We discovered that MEC1/TEL1 deficient mutants reached vacuolar staining faster than
wild types. In addition, a preliminary mammalian ATM/ATR inhibitor tests was conducted to test for their effectiveness
in yeast.

Biochemical Characterization of Histone Variants and Post-translationally Modified Nucleosomes

Supervisor: ISHIBASHI Toyotaka / LIFS
Student: CHEUNG Yat Hin Boris / BIBU Course: UROP1100, Fall
UROP2100, Spring

Nucleosome is the fundamental unit of the chromatin structure and is a major component in the process of chromatin
condensation and relaxation. The human genome consists of approximately 30 million nucleosomes, however, details
for nucleosome-nucleosome interaction remains unclear and defining the interaction will lead to insights to global gene
expression patterns. This project focuses on quantifying the inter-nucleosomal interactions among three nucleosomes.
We have constructed three identical repeated nucleosomal positioning sequence and successfully loaded tri-
nucleosomes. This study helps to quantify the inter-nucleosomal interactions.

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