Microstructural differences in white matter tracts across middle to late adulthood : a diffusion MRI study on 7167 UK Biobank participants

Acknowledgements This research was approved by the UK Biobank (application number: 24089) and was supported by the Roland Sutton Academic Trust (grant number: 0039/R/16) and Taiwan National Health Research Institute (NHRI-EX109-10928NI). We acknowledge the valuable contributions of members of the UK Biobank Imaging Working Group and the UK Biobank coordinating center. The UK Biobank (including the imaging enhancement) was supported by the UK Medical Research Council and the Wellcome Trust. The authors are grateful for the provision of simultaneous multislice (multiband) pulse sequence and reconstruction algorithms by the Center for Magnetic Resonance Research, University of Minnesota. Finally, the authors are extremely grateful to all UK Biobank study participants, who have generously donated their time to make this resource possible. This article was edited by Wallace Academic Editing.Peer reviewedPostprin

Precipitation controls on nutrient budgets in subtropical and tropical forests and the implications under changing climate

Biological, geological and hydrological drivers collectively control forest biogeochemical cycling. However, based on a close examination of recent literature, we argue that the role of hydrological control particularly precipitation on nutrient budgets is significantly underestimated in subtropical and tropical forests, hindering our predictions of future forest nutrient status under a changing climate in these systems. To test this hypothesis, we analyzed two decades of monthly nutrient input and output data in precipitation and streamwater from a subtropical forested watershed in Taiwan, one of the few sites that has long-term nutrient input-output data in the tropics and subtropics. The results showed that monthly input and output of all ions and budgets (output – input) of most ions were positively correlated with precipitation quantity and there was a surprisingly greater net ion export during the wet growing season, indicating strong precipitation control on the nutrient budget. The strong precipitation control is also supported by the divergence of acidic precipitation and near neutral acidity of streamwater, with the former being independent from precipitation quantity but the latter being positively related to precipitation quantity. An additional synthesis of annual precipitation quantity and nutrient budgets of 32 forests across the globe showed a strong correlation between precipitation quantity and nutrient output-input budget, indicating that strong precipitation control is ubiquitous at the global scale and is particularly important in the humid tropical and subtropical forests. Our results imply that climate change could directly affect ecosystem nutrient cycling in the tropics through changes in precipitation pattern and amount

Monsoon hydrography and productivity changes in the East China Sea during the past 100,000 years : Okinawa Trough evidence (MD012404)

Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 24 (2009): PA3208, doi:10.1029/2007PA001577.We analyzed the high-resolution foraminifer isotope records, total organic carbon (TOC), and opal content from an Okinawa Trough core MD012404 in order to estimate the monsoon hydrography and productivity changes in the East China Sea (ECS) of the tropical western Pacific over the past 100,000 years. The variability shown in the records on orbital time scales indicates that high TOC intervals coincide with the increases of boreal May–September insolation driven by precession cycles (∼21 ka), implying a strong connection to the variations in monsoons. We also observed possibly nearly synchronous, millennial-scale changes of the ECS surface hydrography (mainly driven by salinity changes but also by temperature effects) and productivity coincident with monsoon events in the Hulu/Dongge stalagmite isotope records. We found that increased freshening and high productivity correlate with high monsoon intensity in interstadials. This study suggests that the millennial-scale changes in monsoon hydrography and productivity in the ECS are remarkable and persistent features over the past 100,000 years.Y.Y.’s work was partly supported by Global Environmental Research Fund (RF-081) and JSPS Kakenhi (21674003)

Comparison of Human and Soil Candida tropicalis Isolates with Reduced Susceptibility to Fluconazole

Infections caused by treatment-resistant non-albicans Candida species, such as C. tropicalis, has increased, which is an emerging challenge in the management of fungal infections. Genetically related diploid sequence type (DST) strains of C. tropicalis exhibiting reduced susceptibility to fluconazole circulated widely in Taiwan. To identify the potential source of these wildly distributed DST strains, we investigated the possibility of the presence in soil of such C. tropicalis strains by pulsed field gel electrophoresis (PFGE) and DST typing methods. A total of 56 C. tropicalis isolates were recovered from 26 out of 477 soil samples. Among the 18 isolates with reduced susceptibility to fluconazole, 9 belonged to DST149 and 3 belonged to DST140. Both DSTs have been recovered from our previous studies on clinical isolates from the Taiwan Surveillance of Antimicrobial Resistance of Yeasts (TSARY) program. Furthermore, these isolates were more resistant to agricultural azoles. We have found genetically related C. tropicalis exhibiting reduced susceptibility to fluconazole from the human hosts and environmental samples. Therefore, to prevent patients from acquiring C. tropicalis with reduced susceptibility to azoles, prudent use of azoles in both clinical and agricultural settings is advocated

Evolution of neo-sex chromosomes in Drosophila albomicans

紅果蠅 (Drosophila albomicans) 具有一對新的性染色體 (3-X 與 3-Y)，使得其性染色體佔了整個基因組的 60%，而與此對新性染色體 3 號臂同源的仍為其同胞種-輝顏果蠅 (D. nasuta) 的 3 號體染色體。一般而言，Y 染色體多異染色質化且僅含少數具有活性的基因，但由於紅果蠅具有此癒合的新性染色體，尚處於染色體分化初期，這些同源序列是研究性性染色體與體染色體差別的好材料，本論文依此特性，探討諸如 Y 染色體上對雄性有利的性別拮抗因子的堆積、Y 染色體的退化以及性染色體分化的時間。由限制性雜合消去法 (SSH) 所獲得的紅果蠅雄性特殊表現基因的分析結果，並未顯示在新性染色體臂上的比例較高，但如預期地性染色體上的基因承受較大的選汰壓，並雄性特殊表現基因的演化速率較一般基因為快。並由紅果蠅性染色體上的二十五個對偶基因，其 X 與 Y 序列差異推測新性染色體臂分化的時間約七萬年。雖未發現紅果蠅新 Y 染色體有明顯的退化，但發現雲南族群的 Amyrel 基因有一個多態存在的退化因子，它的表現序列具有一個 206 bp 的缺失而且該序列的轉譯過早終止。表示 Y 染色體在演化初期雖未有顯著的退化現象，但族群中已出現退化因子。Drosophila albomicans has a pair of neo-sex chromosomes which composed 60% of the genome (i.e., fused 3-X and 3-Y) and the homologous 3rd chromosome is still an autosome of its sibling species D. nasuta. Generally speaking, the Y chromosome contains only a small number of genes and its major components are heterochromatin. Because of the fusion events between the autosome and sex chromosomes, D. albomicans became a promising material to study the early stage of sex chromosomes. Homologous sequences on the 3rd chromosome can be used to study sex chromosome differentiation after the cessation of recombination, such as the accumulation of sexual antagonistic alleles favoring males, Y chromosome degeneration and the neo-sex chromosome divergence time of D. albomicans. The SSH cDNA library of males did not show a significant higher proportion of male specifically expressed genes located on this neo-sex chromosome arms, but their evolution rate is higher as expected. Also as expected, genes on the sex chromosome were shown to be under higher selection pressure, and found the evolution rate is higher of the male-specific expression genes than other ones. The divergence time of the neo-sex chromosomes is about 70,000 years according to the 25 alleles of X and Y homologous sequences. There’s no significant degeneration found on the neo-Y chromosome, however, an allele of the gene Amyrel on the Y chromosome with a 206 bp deletion and a premature stop codon was found polymorphically existed in the Yunnan population. It shows there’s no obvious degeneration of Y chromosome at this early stage; nevertheless, a degenerate allele polymorphically existed.目錄頁數辭……………………………………………………………… i文摘要………………………………………………………… iii文摘要………………………………………………………… iv言……………………………………………………………… 11) 穆勒氏棘輪 (Muller’s ratchet)……………………… 32) 搭便車效性 (hitchhiking effect) …………………… 33) 染色體的不需適應性 (non-adaptive Y) ……………… 4蠅性染色體的癒合與退化…………………………………… 4果蠅的性染色體演化………………………………………… 6料與方法……………………………………………………… 12蠅之品系、維持與雜交實驗………………………………… 12DNA libraries 之建立……………………………………… 13SH libraries 之建立……………………………………… 15enomic DNA 之萃取………………………………………… 17合酶連鎖反應與定序……………………………………… 17列分析……………………………………………………… 18列資料整理………………………………………………… 22緣關係樹之建立…………………………………………… 25果……………………………………………………………… 27果蠅與輝顏果蠅 ESTs 之分析……………………………… 27果蠅新性連基因與輝顏果蠅同源基因之分析……………… 28緣關係樹與地理分布之關係………………………………… 40歧時間………………………………………………………… 47論……………………………………………………………… 49別拮抗因子之累積…………………………………………… 49 Y 染色體之退化……………………………………………… 50染色體之分歧時間…………………………………………… 51考文獻………………………………………………………… 53錄……………………………………………………………… 6

Stable isotope record of planktonic foraminifera from sediment core MD96-2085

A high-resolution (~4-5cm/kyr) giant piston core record (MD962085) retrieved during an IMAGES II-NAUSICAA cruise from the continental slope of the southeast Atlantic Ocean reveals striking variations in planktonic foraminifer faunal abundances and sea-surface temperatures (SST) during the past 600 000 yr. The location and high-quality sedimentary record of the core provide a good opportunity to assess the variability of the Benguela Current system and associated important features of the ocean-climate system in the southeast Atlantic. The planktonic foraminifer faunal abundances of the core are dominated by three assemblages: (1) Neogloboquadrina pachyderma (right coiling) + Neogloboquadrina dutertrei, (2) Globigerina bulloides, and (3) Globorotalia inflata. The assemblage of N. pachyderma (right coiling) + N. dutertrei shows distinctive abundance changes which are nearly in-phase with glacial-interglacial variations. The high abundances of this assemblage are associated with major glacial conditions, possibly representing low SST/high nutrient level conditions in the southwestern Africa margin. In contrast, the G. bulloides and G. inflata assemblages show greater high-frequency abundance change patterns, which are not parallel to the glacial-interglacial changes. These patterns may indicate rapid oceanic frontal movements from the south, and a rapid change in the intensity of the Benguela upwelling system from the east. A single episode of maximum abundances of a polar water species N. pachyderma (left coiling) occurred in the beginning of stage 9 (~340-330 kyr). The event of the maximum occurrence of this species shown in this record may indicate instability in the Benguela coastal upwelling, or the Antarctic polar front zone position. A winter season SST estimate using transfer function techniques for this record shows primarily glacial-interglacial variations. The SST is maximal during the transitions from the major glacial to interglacial stages (Terminations I, II, IV, V), and is associated with the abundance maxima of a warm water species indicator Globigerinoides ruber. Cross-spectral analyses of the SST record and the SPECMAP stack reveal statistically significant concentrations of variance and coherencies in three major orbital frequency bands. The SST precedes changes in the global ice volume in all orbital frequency bands, indicating a dominant southern Hemispheric climate effect over the Benguela Current region in the southeast Atlantic