Browsing by Author "Lin, Hui-Jen"

Now showing 1 - 4 of 4

A Novel Metallo-beta-Lactamase Involved in the Ampicillin Resistance of Streptococcus pneumoniae ATCC 49136 Strain
(2016-05-23)
Chang, Chia-Yu
;
Lin, Hui-Jen
;
Li, Bor-Ran
;
Li, Yaw-Kuen
;
分子醫學與生物工程研究所
Streptococcus pneumoniae, a penicillin-sensitive bacterium, is recognized as a major cause of pneumonia and is treated clinically with penicillin-based antibiotics. The rapid increase in resistance to penicillin and other antibiotics affects 450 million people globally and results in 4 million deaths every year. To unveil the mechanism of resistance of S. pneumoniae is thus an important issue to treat streptococcal disease that might consequently save millions of lives around the world. In this work, we isolated a streptococci-conserved L-ascorbate 6-phosphate lactonase, from S. pneumoniae ATCC 49136. This protein reveals a metallo-beta-lactamase activity in vitro, which is able to deactivate an ampicillin-based antibiotic by hydrolyzing the amide bond of the beta-lactam ring. The Michaelis parameter (K-m) = 25 mu M and turnover number (k(cat)) = 2 s(-1) were obtained when nitrocefin was utilized as an optically measurable substrate. Through confocal images and western blot analyses with a specific antibody, the indigenous protein was recognized in S. pneumoniae ATCC 49136. The protein-overexpressed S. pneumonia exhibits a high ampicillin-tolerance ability in vivo. In contrast, the protein-knockout S. pneumonia reveals the ampicillin-sensitive feature relative to the wild type strain. Based on these results, we propose that this protein is a membrane-associated metallo-beta-lactamase (MBL) involved in the antibiotic-resistant property of S. pneumoniae.
Fluorescent tracer of dopamine enables selective labelling and interrogation of dopaminergic amacrine cells in the retina of living zebrafish
(2016-01-01)
Lin, Hui-Jen
;
Hong, Zhen-Yi
;
Li, Yaw-Kuen
;
Liau, Ian
;
生物科技學系
The retinal dopaminergic amacrine cell plays multiple roles in vision; it optimizes the encoding of visual stimuli, serves as an output of the circadian rhythm, and influences trophic processes. Specific identification of such cells in vivo remains challenging. A fluorescent tracer that mimics natural dopamine would help elucidate the distribution and the functional roles of dopaminergic neurons. Here we report a fluorescent tracer of dopamine for the selective labeling and study of retinal dopaminergic amacrine cells in vivo. This tracer has low toxicity and effective selectivity, and enables fluorescent determination of the evoked release of dopamine and the femtosecond laser ablation of single dopaminergic amacrine cells in living zebrafish. Our approach is readily adaptable by other research groups, and is expected to accelerate biomedical research in domains related to the pathophysiology of retinal dopaminergic amacrine cells.
Interplay between Structure and Fluidity of Model Lipid Membranes under Oxidative Attack
(2010-12-02)
Tai, Wan-Yu
;
Yang, Yi-Cyun
;
Lin, Hui-Jen
;
Huang, Chin-Ping
;
Cheng, Yi-Lin
A proper regula:ion of membrane fluidity is critical for cellular activities such as communication between cells, mitosis, an :I endocytosis. Unsaturated lipids, a main component of biological membranes, are particularly susceptible to oxidative attack of reactive oxygen species. The oxidation of lipids can produce structural derangement of membranes and eventually alter the membrane fluidity. We have applied fluorescence correlation spectroscopy (FCS) and Raman spectroscopy to investigate the fluidity and structure of model membranes subject to oxidative attack. Hydrogen peroxide has little effect on the lateral fluidity of membranes. whereas hydroxyl radical causes a significantly increased fluidity. The latter is rationalized with the cleavage of the acyl chains of lipids caused by hydroxyl radical; this interpretation is founded on the diminished intensities of lines in Raman spectra associated with -CH(2) and C = C moieties in lipids and supported by mass-spectral measurements. The same approach provides a mechanistic account of the inhibitory capability of vitamins C and E against ate increased membrane fluidity resulting from an oxidative attack. Membranes with much cholesterol exhibit a novel resistance against altered membrane fluidity induced with oxidative attack; this finding has biological implications. Our approach combining FCS and Raman measurements reveals the interplay between the structure and fluidity of membranes and provides insight into the pathophysiology of cellular oxidative injury.
Toward live-cell imaging of dopamine neurotransmission with fluorescent neurotransmitter analogues
(2015-01-01)
Lin, Hui-Jen
;
Lu, Hsueh-Han
;
Liu, Kuan-Miao
;
Chau, Chi-Min
;
Hsieh, You-Zung
We report a novel \'fluorescent dopamine\' that possesses essential features of natural dopamine. Our method is simple and is readily extended to monoamine neurotransmitters such as L-norepinephrine, serotonin and GABA, providing a more practical approach. Because of its compatibility with sensitive fluorescent measurements, we envisage that our approach will have a broad range of applications in neural research.