Human genetic history in East Asia is poorly understood. To clarify population relationships, we obtained genome wide data from 26 ancient individuals from northern and southern East Asia spanning ...9,500-300 years ago. Genetic differentiation was higher in the past than the present, reflecting a major episode of admixture involving northern East Asian ancestry spreading across southern East Asia after the Neolithic, transforming the genetic ancestry of southern China. Mainland southern East Asian and Taiwan Strait island samples from the Neolithic show clear connections with modern and ancient samples with Austronesian-related ancestry, supporting a southern China origin for proto-Austronesians. Connections among Neolithic coastal groups from Siberia and Japan to Vietnam indicate that migration and gene flow played an important role in the prehistory of coastal Asia.
碩士
國立臺北教育大學
自然科學教育學系碩士班
99
The purpose of this study is to probe how science teachers promote profe-
ssional knowledge in instructing primary science fair, and how “case-method teaching” assists ...university professors to implement their curriculums.
To understand the real scene of teacher education, researcher collected class
videos, worksheets, professors’ curriculum materials, and science fair schemes
designed by science teachers. Besides, researcher interviewed professors as
well. Cross reference different data and triangulate them to ensure the validity.
First, interview two professors to understand their philosophy and course
design. Besides, by analyzing science fair schemes designed by empowerment
class of instructing primary science fair, researcher found that most science
teachers failed to understand the theatrical base of their scheme subjects. Along
with flawed experimental operation, poorly controlled variables, or verification
of known facts.
Second, with the benefit of “participant observation",
Retroviruses are single-stranded, positive-sense RNA viruses that cause many diseases in a variety of species. During the replication cycle, the retroviral genome generates three species of viral RNA ...(vRNA): the first is an unspliced vRNA that serves as the template for the translation of the Gag and Gag-Pol proteins, the second is an unspliced vRNA that is packaged into newly formed virions, and the third is a spliced vRNA that serves as the template for translation of Env and other viral proteins. Studies in our laboratory of the avian oncoretrovirus Rous sarcoma virus (RSV) demonstrated that the Gag transiently traffics through the nucleus, and this step is linked to efficient packaging of the genome into virions.Retroviruses are unique in that they package their genomes into newly formed virions as a non-covalently linked genome dimer. Disruption of genome dimer formation in any manner reduces the infectivity of any newly formed virions, which has motivated researchers to further characterize this step in the retrovirus replication cycle. Genome dimerization has been characterized to involve two cis-acting sequences in the 5’ UTR of the genome. The first is a dimer linkage sequence (DLS), a sequence initially identified in RSV via electron microscopy images of genome dimers isolated from virions demonstrating a physical linkage between two strands of viral RNA. The second is a dimer initiation site (DIS), a sequence identified during deletion analysis experiments of the 5’ UTR of retroviruses. The DIS has been characterized to be a stem-loop containing a palindromic sequence across the top of the stem-loop allowing for intermolecular interactions.In this study, we sought to answer questions about genome dimerization in RSV using a combination of single molecule microscopy techniques including RNA stem loops and fluorescent-tagged coat proteins and RNA FISH. These techniques allowed us to observe single molecules of RNA in the context of a whole cell. We determined the subcellular location of RSV genome dimerization, the composition of genome dimers in cells and in virions, and whether Gag played a role in genome dimerization. Additionally, we used microscopy techniques to visualize genome splicing in RSV. Live-cell imaging techniques were used to observe genome dimerization and genome splicing in real-time and measure the kinetics of these processes.Taken together, we propose a model in which a threshold of nuclear Gag is functional in facilitating genome dimerization and possibly genome splicing. The expression of additional nuclear-trapped Gag in trans does not increase the number of genome dimers formed in the cell. We propose that nuclear Gag serves to regulate efficient dimerization and packaging of genomes. Further study of these functions in RSV, and in other retroviruses, will increase our understanding of the role of nuclear Gag in retrovirus replication and infectivity.
Alzheimer's disease (AD) is the most common form of neurodegenerative disorder affecting the elderly, presenting symptoms such as memory impairment and dementia. AD is pathologically characterized by ...the development of extracellular senile plaques and intracellular neurofibrillary tangles (NFT). The plaques are composed of amyloid-β peptide (Aβ) and the NFTs are composed of a hyperphosphorylated form of the tau protein. Aβ is formed by sequential proteolytic processing of the amyloid precursor protein (APP) by β-, and γ-secretase. Accordingly, alterations in APP processing result in increased Aβ generation. The low-density lipoprotein receptor-related protein (LRP) is a large endocytic protein involved in diverse biological functions. It has been hypothesized that LRP plays a dual role in AD, playing a role in both the clearance and the production of Aβ. Previous studies have shown that the cytoplasmic tail alone is able to promote Aβ generation and promote APP processing. This study seeks to determine the area of the cytoplasmic tail responsible for pro-amyloidogenic activity and how it occurs. Our findings indicate that the last 37 amino acids of the tail, containing a dileucine motif, are sufficient. Additionally, LRP facilitates the generation of Aβ by trafficking APP and BACE1 to the lipid raft domains. This function of LRP may be altered due to the presence of a Kunitz protease inhibitor (KPI) domain on APP. The results of our study have therapeutic potential to reduce β-amyloid by understanding the function of LRP in the amyloidogenic processing of APP.
Thesis (M.S.)--University of California, San Diego, 2008.
Title from first page of PDF file (viewed July 30, 2008). Available via ProQuest Digital Dissertations. Includes bibliographical references ...(p. 42-46).
Between Middle Chinese and the 1963-85 system of Peking Mandarin, about 454 characters have been flowing into or towards the Yin-Ping category and 77 out of the category, forming a ratio of 85.5% to ...14.5%. A decided majority of the out-flowing characters can readily be attributed to an analogy of certain high-frequency characters that bear obvious graphic similarities. On the other hand, there seems to be a tendency for high-frequency colloquial forms to change to Yin-Ping. Five types of evidence are submitted to substantiate this claim. They are found in 1) reduplicates, 2) onomatopoetic forms, 3) monosyllabic verbs, 4) colloquial (as opposed to literary) vocabulary of a character, 5) colloquial (as opposed to literary) reading(s) of a character. A total of 156 examples are cited here.
The Gram-negative anaerobe Fusobacterium nucleatum is a major producer of hydrogen sulfide (H2S), a volatile sulfur compound that causes halitosis. Here, we dissected the genetic determinants of H2S ...production and its role in bacterial fitness and virulence in this important member of the oral microbiome. F. nucleatum possesses four enzymes, CysK1, CysK2, Hly, and MegL, that presumably metabolize l-cysteine to H2S, and CysK1 was previously shown to account for most H2S production in vitro, based on correlations of enzymatic activities with gene expression at mid-log phase. Our molecular studies showed that cysK1 and megL were highly expressed at the late exponential growth phase, concomitant with high-level H2S production, while the expression levels of the other genes remained substantially lower during all growth phases. Although the genetic deletion of cysK1 without supplementation with a CysK1-catalyzed product, lanthionine, caused cell death, the conditional ΔcysK1 mutant and a mutant lacking hly were highly proficient in H2S production. In contrast, a mutant devoid of megL showed drastically reduced H2S production, and a cysK2 mutant showed only minor deficiencies. Intriguingly, the exposure of these mutants to various antibiotics revealed that only the megL mutant displayed altered susceptibility compared to the parental strain: partial sensitivity to nalidixic acid and resistance to kanamycin. Most significantly, the megL mutant was attenuated in virulence in a mouse model of preterm birth, with considerable defects in the spread to amniotic fluid and the colonization of the placenta and fetus. Evidently, the l-methionine γ-lyase MegL is a major H2S-producing enzyme in fusobacterial cells that significantly contributes to fusobacterial virulence and antibiotic susceptibility. IMPORTANCE Fusobacterium nucleatum is a key commensal anaerobe of the human oral cavity that plays a significant role in oral biofilm development and contributes to additional pathologies at extraoral sites, such as promoting preterm birth and colorectal cancer. Although F. nucleatum is known as a major producer of hydrogen sulfide (H2S), its genetic determinants and physiological functions are not well understood. By a combination of bacterial genetics, biochemical methods, and in vivo models of infection, here, we demonstrate that the l-methionine γ-lyase MegL not only is a major H2S-producing enzyme of F. nucleatum but also significantly contributes to the antibiotic susceptibility and virulence of this organism.
GV1001, an anticancer vaccine, exhibits other biological functions, including anti-inflammatory and antioxidant activity. It also suppresses the development of ligature-induced periodontitis in mice. ...Porphyromonas gingivalis (Pg), a major human oral bacterium implicated in the development of periodontitis, is associated with various systemic disorders, such as atherosclerosis and Alzheimer’s disease (AD). This study aimed to explore the protective effects of GV1001 against Pg-induced periodontal disease, atherosclerosis, and AD-like conditions in Apolipoprotein (ApoE)-deficient mice. GV1001 effectively mitigated the development of Pg-induced periodontal disease, atherosclerosis, and AD-like conditions by counteracting Pg-induced local and systemic inflammation, partly by inhibiting the accumulation of Pg DNA aggregates, Pg lipopolysaccharides (LPS), and gingipains in the gingival tissue, arterial wall, and brain. GV1001 attenuated the development of atherosclerosis by inhibiting vascular inflammation, lipid deposition in the arterial wall, endothelial to mesenchymal cell transition (EndMT), the expression of Cluster of Differentiation 47 (CD47) from arterial smooth muscle cells, and the formation of foam cells in mice with Pg-induced periodontal disease. GV1001 also suppressed the accumulation of AD biomarkers in the brains of mice with periodontal disease. Overall, these findings suggest that GV1001 holds promise as a preventive agent in the development of atherosclerosis and AD-like conditions associated with periodontal disease.
Significance
Fusobacterium nucleatum
interacts with many oral microbes and has the ability to spread to the placenta and amniotic fluid, promoting preterm birth. Yet, the molecular mechanisms ...underlying polymicrobial interactions, termed coaggregation, by Fusobacteria are poorly understood. Here, we revealed that the two-component signal transduction system CarRS regulates expression of genes encoding lysine utilization factors (e.g., KamA) and the coaggregation factor RadD. Extracellular lysine blocks RadD-mediated coaggregation by binding to RadD. Significantly, mutants lacking KamA or CarR (which up-regulates RadD) are attenuated in virulence in a preterm birth model, while mutants devoid of RadD or CarS (which down-regulates RadD) exhibit increased virulence. Our findings unveiled a molecular linkage between coaggregation and lysine metabolism via CarRS-mediated gene regulation that modulates bacterial virulence.
A gram-negative colonizer of the oral cavity,
Fusobacterium nucleatum
not only interacts with many pathogens in the oral microbiome but also has the ability to spread to extraoral sites including placenta and amniotic fluid, promoting preterm birth. To date, however, the molecular mechanism of interspecies interactions—termed coaggregation—by
F. nucleatum
and how coaggregation affects bacterial virulence remain poorly defined. Here, we employed genome-wide transposon mutagenesis to uncover fusobacterial coaggregation factors, revealing the intertwined function of a two-component signal transduction system (TCS), named CarRS, and a lysine metabolic pathway in regulating the critical coaggregation factor RadD. Transcriptome analysis shows that CarR modulates a large regulon including
radD
and lysine metabolic genes, such as
kamA
and
kamD
, the expression of which are highly up-regulated in the Δ
carR
mutant. Significantly, the native culture medium of Δ
kamA
or Δ
kamD
mutants builds up abundant amounts of free lysine, which blocks fusobacterial coaggregation with streptococci. Our demonstration that lysine-conjugated beads trap RadD from the membrane lysates suggests that lysine utilizes RadD as its receptor to act as a metabolic inhibitor of coaggregation. Lastly, using a mouse model of preterm birth, we show that fusobacterial virulence is significantly attenuated with the Δ
kamA
and Δ
carR
mutants, in contrast to the enhanced virulence phenotype observed upon diminishing RadD (Δ
radD
or Δ
carS
mutant). Evidently,
F. nucleatum
employs the TCS CarRS and environmental lysine to modulate RadD-mediated interspecies interaction, virulence, and nutrient acquisition to thrive in the adverse environment of oral biofilms and extraoral sites.
Fusobacterium nucleatum, an anaerobic Gram-negative bacterium frequently found in the human oral cavity and some extra-oral sites, is implicated in several important diseases: periodontitis, adverse ...pregnancy outcomes, and colorectal cancer. To date, how this obligate anaerobe copes with oxidative stress and host immunity within multiple human tissues remains unknown. Here, we uncovered a critical role in this process of a multigene locus encoding a single, fused methionine sulfoxide reductase (MsrAB), a two-component signal transduction system (ModRS), and thioredoxin (Trx)- and cytochrome
(CcdA)-like proteins, which are induced when fusobacterial cells are exposed to hydrogen peroxide. Comparative transcriptome analysis revealed that the response regulator ModR regulates a large regulon that includes
,
, and many metabolic genes. Significantly, specific mutants of the
locus, including
, are sensitive to reactive oxygen species and defective in adherence/invasion of colorectal epithelial cells. Strikingly, the
mutant is also defective in survival in macrophages, and it is severely attenuated in virulence in a mouse model of preterm birth, consistent with its failure to spread to the amniotic fluid and colonize the placenta. Clearly, the MsrAB system regulated by the two-component system ModRS represents a major oxidative stress defense pathway that protects fusobacteria against oxidative damage in immune cells and confers virulence by enabling attachment and invasion of multiple target tissues.
F. nucleatum colonizes various human tissues, including oral cavity, placenta, and colon. How this obligate anaerobe withstands oxidative stress in host immune cells has not been described. We report here that F. nucleatum possesses a five-gene locus encoding a fused methionine sulfoxide reductase (MsrAB), a two-component signal transduction system (ModRS), and thioredoxin- and cytochrome
-like proteins. Regulated by ModRS, MsrAB is essential for resistance to reactive oxygen species, adherence/invasion of colorectal epithelial cells, and survival in macrophage. Unable to colonize placenta and spread to amniotic fluid, the
mutant failed to induce preterm birth in a murine model.
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