A systematic study of chiral homoprolinols and their derivatives in the catalysis of enantioselective addition of diethylzinc to aldehydes

Homoprolinol analogs, a class of optically active γ‐amino alcohols, were examined systematically in the enantioselective addition reactions of diethylzinc to aldehydes. By comparison of the results catalyzed by these γ‐amino alcohols with those by the β‐amino alcohols based on pyrrolidine architecture reported in the literature references, we have observed that the γ‐amino alcohols are superior to the corresponding β‐amino alcohols when the nitrogen and the oxygen are unsubstituted. Among the homoprolinols we tested, 2b gave the best results (45–88% yields, 44–81% ee) in the addition reactions. To the best of our knowledge, 2b has been noticed as one of the most efficient γ‐amino alcohol catalysts based on pyrrolidine framework. Chirality, 2011. © 2011 Wiley‐Liss, Inc.     

Spindle assembly checkpoint signalling is uncoupled from chromosomal position in mouse oocytes

The spindle assembly checkpoint (SAC) averts aneuploidy by coordinating proper bipolar chromosomal attachment with anaphase-promoting complex/cyclosome (APC/C)-mediated securin and cyclin B1 destruction required for anaphase onset. The generation of a Mad2-based signal at kinetochores is central to current models of SAC-based APC/C inhibition. During mitosis, kinetochores of polar-displaced chromosomes, which are at greatest risk of mis-segregating, recruit the highest levels of Mad2, thereby ensuring that SAC activation is proportionate to aneuploidy risk. Paradoxically, although an SAC operates in mammalian oocytes, meiosis I (MI) is notoriously error prone and polar-displaced chromosomes do not prevent anaphase onset. Here we find that Mad2 is not preferentially recruited to the kinetochores of polar chromosomes of wild-type mouse oocytes, in which polar chromosomes are rare, or of oocytes depleted of the kinesin-7 motor CENP-E, in which polar chromosomes are more abundant. Furthermore, in CENP-E-depleted oocytes, although polar chromosomal displacement intensified during MI and the capacity to form stable end-on attachments was severely compromised, all kinetochores nevertheless became devoid of Mad2. Thus, it is possible that the ability of the SAC to robustly discriminate chromosomal position might be compromised by the propensity of oocyte kinetochores to become saturated with unproductive attachments, thereby predisposing to aneuploidy. Our data also reveal novel functions for CENP-E in oocytes: first, CENP-E stabilises BubR1, thereby impacting MI progression; and second, CENP-E mediates bi-orientation by promoting kinetochore reorientation and preventing chromosomal drift towards the poles.     

IL-22 and non-ELR-CXC chemokine expression in chronic hepatitis B virus-infected liver

Hepatitis B virus infection is still a major global health problem, despite decades of research. Interleukin (IL)-22 induces acute phase reactants and chemokines, favors anti-microbial defence and protects tissues from damage. IL-22 is important in chronic skin inflammation, but its role in chronic hepatitis B (CHB) is unclear. This study explores the association between intra-hepatic IL-22 expression, its relevant associated cytokines and the severity of liver inflammation/fibrosis in CHB patients. IL-22, IL-17, IL-10, IL-6, non-ELR-CXC chemokines (CXCL-9, CXCL-10, CXCL-11), fibroblast growth factors and Kupffer cell (KC) numbers were measured in patients with CHB (n=65), acute hepatitis B (AHB; n=4), chronic hepatitis C (CHC; n=14) and non-viral hepatitis (n=23), using immunohistochemistry. Expression of IL-22, IL-17, IL-10, IL-6, non-ELR-CXC chemokines and number of KCs in liver tissues were substantially higher in AHB patients than others. In CHB patients, the expression of IL-22, IL-6, CXCL-9 and CXCL-10 were significantly higher with alanine aminotransferase (ALT) levels ≤ twice the upper limit of normal (ULN), compared with those with ALT levels >twice the ULN, whereas IL-10 and IL-17 showed a reverse pattern. IL-22 was inversely (P<0.01), but IL-17 was positively (P<0.05), correlated with the histological activity index) in these patients, and a significant negative correlation between the fibrosis stage and IL-22 or non-ELR-CXC chemokines was observed. Furthermore, immunofluorescent labeling demonstrated a close spatial association of IL-22, CXCL-9, -10 or -11 in the CHB liver. We speculate that IL-22 and non-ELR-CXC chemokines synergistically may provide protection in liver inflammation/fibrosis during CHB infection.     

Stages and duration of the cycle of the seminiferous epithelium in oncilla (Leopardus tigrinus, Schreber, 1775)

Six adult Leopardus tigrinus (oncilla) were studied to characterize stages of the seminiferous epithelium cycle and its relative frequency and duration, as well as morphometric parameters of the testes. Testicular fragments were obtained (incisional biopsy), embedded (glycol methacrylate), and histologic sections examined with light microscopy. The cycle of the seminiferous epithelium was categorized into eight stages (based on the tubular morphology method). The duration of one seminiferous epithelium cycle was 9.19 d, and approximately 41.37 d were required for development of sperm from spermatogonia. On average, diameter of the seminiferous tubules was 228.29 μm, epithelium height was 78.86 μm, and there were 16.99 m of testicular tubules per gram of testis. Body weight averaged 2.589 kg, of which 0.06 and 0.04% were attributed to the testis and seminiferous tubules, respectively. In conclusion, there were eight distinct stages in the seminiferous epithelium, the length of the seminiferous epithelium cycle was close to that in domestic cats and cougars, and testicular and somatic indexes were similar to those of other carnivores of similar size.     

A novel cyanophage with a cyanobacterial nonbleaching protein A gene in the genome

A cyanophage, PaV-LD, has been isolated from harmful filamentous cyanobacterium Planktothrix agardhii in Lake Donghu, a shallow freshwater lake in China. Here, we present the cyanophage's genomic organization and major structural proteins. The genome is a 95,299-bp-long, linear double-stranded DNA and contains 142 potential genes. BLAST searches revealed 29 proteins of known function in cyanophages, cyanobacteria, or bacteria. Thirteen major structural proteins ranging in size from 27 kDa to 172 kDa were identified by SDS-PAGE and mass-spectrometric analysis. The genome lacks major genes that are necessary to the tail structure, and the tailless PaV-LD has been confirmed by an electron microscopy comparison with other tail cyanophages and phages. Phylogenetic analysis of the major capsid proteins also reveals an independent branch of PaV-LD that is quite different from other known tail cyanophages and phages. Moreover, the unique genome carries a nonbleaching protein A (NblA) gene (open reading frame [ORF] 022L), which is present in all phycobilisome-containing organisms and mediates phycobilisome degradation. Western blot detection confirmed that 022L was expressed after PaV-LD infection in the host filamentous cyanobacterium. In addition, its appearance was companied by a significant decline of phycocyanobilin content and a color change of the cyanobacterial cells from blue-green to yellow-green. The biological function of PaV-LD nblA was further confirmed by expression in a model cyanobacterium via an integration platform, by spectroscopic analysis and electron microscopy observation. The data indicate that PaV-LD is an exceptional cyanophage of filamentous cyanobacteria, and this novel cyanophage will also provide us with a new vision of the cyanophage-host interactions.     

Proteomic Analysis of Osmotic Stress-Responsive Proteins in Sugarcane Leaves

Osmotic stress-related proteins in sugarcane were identified using proteomics approach based on two-dimensional polyacrylamide gel electrophoresis (2-DE) and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS). Sugarcane settlings were subjected to osmotic stress in the nutrient solution containing 10% (w/v) PEG 6000 for 14 h. Total proteins were extracted from leaves, and separated by 2-DE. Four typical spots exhibited significant changes in PEG treatment compared to control, which were identified using MALDI-TOF-MS successfully. The drought inducible 22 kDa protein and Rubisco small subunit were up-regulated while isoflavone reductase-like (IRLs, related to antioxidant defense system) protein and delta chain of ATP synthase were down-regulated by the osmotic stress. Analysis of the results showed that the most differential proteins under osmotic stress were acidic, unstable and transmembrane proteins, enriched with hydrophobic amino acids such as leucine and alanine which are extremely important for structural stabilization of proteins by hydrophobic interaction. However, the drought inducible 22 kDa protein was a hydrophile and non-transmembrane protein enriched with glutamic acid. These results provide new insight into the part of regulatory mechanism of adaptations to osmotic stress through differential expression of specific proteins and implicate several previously unrecognized proteins to osmotic stress.     

入侵植物刺苍耳在新疆的分布及其群落特征

刺苍耳是原产于南美洲的菊科植物,2009年首次在新疆的伊宁县发现。于2010～2011年对新疆南北疆近40个县(市)中刺苍耳可能出现的区域进行调查,并采用样方法,对不同生境中刺苍耳分布相对集中的23个样地所有物种的多度、频度和重要值进行了观测和分析,以明确刺苍耳在新疆的分布区及其群落特征,为有效防治其扩散提供依据。结果显示:(1)刺苍耳分布于新疆的昌吉市、伊宁市、伊宁县、巩留县、特克斯县、新源县、察布查尔县、霍城县和尼勒克县,分布区海拔597～1 834m,生境类型包括荒漠草原和绿洲。(2)刺苍耳在荒漠草原和绿洲生境中的相对多度均处于首位,且在绿洲中达到最大值,为入侵区域最重要的物种;刺苍耳在2种生境中的相对盖度均为第一,且绿洲(46.83%)大于荒漠草原(43.00%)。(3)刺苍耳在2种生境中的综合适应力均最强,在绿洲中尤为突出,是其最易入侵的区域。研究表明,刺苍耳在新疆荒漠草原生境中尚处于局部危害阶段,但在绿洲中已处于蔓延期。     

柑桔BES SSR标记开发及连锁图延伸和加密

为了系统性地开发和拓展柑桔SSR标记,通过对公布的柑桔BAC文库末端序列(BAC-End sequence,BES)进行SSR分析,选择1500个SSR位点设计合成并检测323对引物。结果表明:(1)从总长度为28.1 Mb的46 339条序列中共检测出22 403个SSR位点,约每2条序列就会出现一个SSR位点,发生频率为48%,相当于平均1.25kb的序列中就会出现1个SSR,频率约为柑桔EST的2倍,且不同核心重复序列的SSR发生特点与EST也不同。(2)所合成的323对引物中,有效扩增316对,扩增率约98%,173对表现多态性,总多态性比率约55%,多态性引物中单核苷酸重复类型15对,双核苷酸重复类型100对,三核苷酸及以上重复类型58对,表明柑桔BES中具有较为丰富的多态性SSR标记。(3)结合已发表的遗传作图数据,对总计349个多态性位点进行遗传连锁分析,获得的新遗传连锁图谱共含有9个连锁群、334个SSR标记、总长844.2cM、平均图距2.53cM,延长和加密了先前的图谱。该研究开发的新SSR标记为开展柑桔遗传鉴定分析和遗传图谱构建提供了新的标记来源,加密的遗传图谱为柑桔的基因定位、图位克隆和标记辅助育种等奠定了基础,SSR分析结果也为其他物种SSR标记的开发提供了参考。