Diversity in prokaryotic glycosylation: an archaeal-derived N-linked glycan contains legionaminic acid

VP4, the major structural protein of the haloarchaeal pleomorphic virus, HRPV‐1, is glycosylated. To define the glycan structure attached to this protein, oligosaccharides released by β‐elimination were analysed by mass spectrometry and nuclear magnetic resonance spectroscopy. Such analyses showed that the major VP4‐derived glycan is a pentasaccharide comprising glucose, glucuronic acid, mannose, sulphated glucuronic acid and a terminal 5‐N‐formyl‐legionaminic acid residue. This is the first observation of legionaminic acid, a sialic acid‐like sugar, in an archaeal‐derived glycan structure. The importance of this residue for viral infection was demonstrated upon incubation with N‐acetylneuraminic acid, a similar monosaccharide. Such treatment reduced progeny virus production by half 4 h post infection. LC‐ESI/MS analysis confirmed the presence of pentasaccharide precursors on two different VP4‐derived peptides bearing the N‐glycosylation signal, NTT. The same sites modified by the native host, Halorubrum sp. strain PV6, were also recognized by the Haloferax volcanii N‐glycosylation apparatus, as determined by LC‐ESI/MS of heterologously expressed VP4. Here, however, the N‐linked pentasaccharide was the same as shown to decorate the S‐layer glycoprotein in this species. Hence, N‐glycosylation of the haloarchaeal viral protein, VP4, is host‐specific. These results thus present additional examples of archaeal N‐glycosylation diversity and show the ability of Archaea to modify heterologously expressed proteins.     

CD36 inhibitors reduce postprandial hypertriglyceridemia and protect against diabetic dyslipidemia and atherosclerosis

CD36 is recognized as a lipid and fatty acid receptor and plays an important role in the metabolic syndrome and associated cardiac events. The pleiotropic activity and the multiple molecular associations of this scavenger receptor with membrane associated molecules in different cells and tissues have however questioned its potential as a therapeutic target. The present study shows that it is possible to identify low molecular weight chemicals that can block the CD36 binding and uptake functions. These inhibitors were able to reduce arterial lipid deposition, fatty acid intestinal transit, plasma concentration of triglycerides and glucose, to improve insulin sensitivity, glucose tolerance and to reduce the plasma concentration of HbAc1 in different and independent rodent models. Correlation between the anti-CD36 activity of these inhibitors and the known pathophysiological activity of this scavenger receptor in the development of atherosclerosis and diabetes were observed at pharmacological doses. Thus, CD36 might represent an attractive therapeutic target.     

Expression of p97/VCP and ubiquitin during postnatal development of the degenerating rat retina

In this study, we aimed to investigate the distribution pattern of ubiquitin and p97/VCP in the rat retina during postnatal development. Eyeballs from 1-, 4-, 10-, 36- and 72-week-old rats were examined by immunohistochemistry, and protein colocalization was determined by immunofluorescence microscopy. In the 1-week-old rat retina, p97/VCP was strongly expressed in the neuroblast layer, however no ubiquitin immunoreactivity was observed. p97/VCP immunoreactivity was present in the ganglion cell layer (GCL), inner nuclear layer (INL), outer nuclear layer (ONL), inner segment (IS) of the photoreceptor layer, and retinal pigment epithelium in the 4- and 10-week-old rat retinas. p97/VCP immunoreactivity increased significantly in the 10-week-old rat retinas. Ubiquitin was barely seen in the 4-week-old rat retinas, and ubiquitin expression was weak in the GCL and the IPL of the 10-week-old rat retinas. In the 36- and 72-week-old rats, the presence of ubiquitin was remarkable in the IS, INL, IPL and GCL, however, p97/VCP immunoreactivity was significantly decreased. Colocalization of ubiquitin and p97/VCP was also observed in the INL, IS, GCL and ONL of 36- and 72-week-old rat retinas. Our results indicate that p97/VCP immunoreactivity in the retina significantly decreases after rats reach 10 weeks of age, whereas ubiquitin immunoreactivity increases with aging. These results suggest that an altered expression pattern of p97/VCP and ubiquitin in the developing rat retina may associate with age-related retinal degeneration.     

SPECIES OF THE GENUS PHOBETES F(O)RSTER (HYMENOPTERA, ICHNEUMONIDAE, CTENOPELMATINAE) FROM CHINA WITH AKEY TO SPECIES KNOWN IN CHINA

报道在江西和河南发现的浮姬蜂属Phobetes F(o)rster,1869的种类,其中有2新种:白环浮姬蜂Ph.albiannularis sp.nov.和河南浮姬蜂Ph.henanensis sp.nov.;中国1新纪录种:北海道浮姬蜂Ph.sapporensis( Uchida,1930).指出了新种与近似种的鉴别特征,并附彩色特征图.编制了该属中国已知种的检索表.     

桉树枝瘿姬小蜂虫瘿解剖特征与寄主叶片生理指标的变化

采用人工接蜂、桉树组织石蜡切片和生化组分测定等方法研究了桉树受桉树枝瘿姬小蜂诱导后的生理生化响应机制.结果表明:DH201-2叶柄角质层厚度和油囊数量均较GL-UG9的厚、多,且差异均达到极显著水平(P角质层厚度=0.00001 ＜0.01,P油囊数量=0.00209＜0.01),但是GL-UG9叶柄表皮细胞厚度和维管束数量均较DH201-2厚、多,差异分别达到显著水平(P=0.015215＜0.05)和极显著水平(P=0.002375＜0.01),DH201-2茎皮层薄壁细胞厚度、油囊直径、维管束数量较GL-UG9厚、多,差异分别为显著(P皮层薄壁细胞厚度=0.04071 ＜0.05)、极显著(P油囊直径=000016＜0.05)、极显著(P维管束数量=0.00000＜0.01).而GLUG9茎角质层和表皮细胞厚度均较DH201-2厚,差异达到了极显著水平(P角质层厚度=0.00167,P表皮细胞厚度=0.00000＜0.01);桉树枝瘿姬小蜂虫瘿为组织瘿,由内到外可以分为:营养组织层、薄/厚壁组织层、维管束层、皮层、表皮等结构;接种桉树枝瘿姬小蜂成虫后,桉树叶片可溶性总糖、游离氨基酸、叶绿素含量均升高,差异达到了极显著水平(P＜0.01),但是蛋白质、pH值、类黄酮、总酚的变化没有达到显著水平(P＞0.05);吲哚乙酸氧化酶、过氧化物、过氧化氢酶活力均有不同程度的升高.研究显示桉树枝瘿姬小蜂入侵诱导了桉树一系列的生理生化变化,实验结果为抗桉树枝瘿姬小蜂桉树无性系的选育技术体系构建提供了理论基础.     

滇池外海蓝藻水华爆发反演及规律探讨

气象条件和营养盐浓度一直被认为是导致蓝藻水华爆发的两个重要因素。通过滇池外海Chla浓度时空分异性分析,得出晖湾中测点最易爆发蓝藻水华且爆发时间集中在每年6—9月。同时,采用基于缺失数据多重插补的EMB算法将气象条件和蓝藻水华爆发的不完全数据集进行反演,建立了滇池外海2004—2008年4—10月完整的气象、营养盐及蓝藻爆发的基础数据集,解决了表观蓝藻水华爆发研究中观测数据缺失的问题。据此,探讨了滇池外海晖湾中测点Chla、TN和TP与蓝藻水华爆发关系,进而提出了控制滇池外海蓝藻水华的一种新思路。     

植物种群自疏过程中构件生物量与密度的关系

不论是在对植物种群自疏规律还是在对能量守衡法则的研究中,个体大小(M)大多针对植物地上部分生物量,地下部分和构件生物量及其动态十分重要又多被忽视。以1年生植物荞麦为材料研究了自疏种群地下部分生物量、包括地下部分的个体总生物量以及各构件生物量与密度的关系。结果表明:平均地上生物量和个体总生物量与密度的异速关系指数(γabove-ground和γindividual)分别为-1.293和-1.253,与-4/3无显著性差异(P>0.05),为-4/3自疏法则提供了有力证据;平均根生物量-密度异速指数γroot(-1.128)与-1无显著性差异(P>0.05),与最终产量恒定法则一致;平均茎生物量-密度异速指数γstem(-1.263)接近-4/3(P>0.05),平均叶生物量-密度异速指数γleaf(-1.524)接近-3/2(P>0.05),分别符合-4/3自疏法则与-3/2自疏法则;而繁殖生物量与密度的异速关系指数γreproductive(-2.005)显著小于-3/2、-4/3或-1(P<0.001)。因此,不存在一个对植物不同构件普适的生物量-密度之间的关系。光合产物在地上和地下构件的生物量分配格局以及构件生物量与地上生物量之间特异的异速生长关系导致不同构件具有不同的自疏指数。无论对于地上生物量还是个体总生物量,荞麦种群能量均守衡,而对于地下生物量,荞麦种群能量不守衡。