Modulating the affinity and the selectivity of engineered calmodulin EF-Hand peptides for lanthanides

A set of engineered peptides (33 amino acids long) corresponding to the helix-turn-helix (EF-Hand) motif of the metal-binding site I of the protein calmodulin from paramecium tetraurelia have been synthesized. A disulfide bridge has been introduced in the native sequence in order to stabilize a native-like conformation. The calcium-binding carboxylate residues in positions 20, 22, 24, and 31 were mutated into other amino acids and the influence of such mutations on the binding affinity of the peptides for calcium and lanthanides have been studied. It was shown that the binding affinity for terbium ions can be modulated with dissociation constants ranging from 40 nmolar to 40 mmolar. The study of the influence of the mutations on the terbium affinity showed that the residue in position 24 played a key role on the capability of the peptides to bind lanthanides and that the affinity could be enhanced by mutations on non-coordinating positions. Such peptides with high affinity for lanthanides may facilitate the development of new highly sensitive biosensors to monitor the metal pollution in the environment.     

2007年北京地区儿童手足口病病原的初步筛查

2007年4～6月儿童手足口病流行期间,对北京地区51例皮损症状典型、伴/不伴发热、无重症合并症的手足口病患儿采样,建立RT-PCR方法,以5'非编码区(5'UTR)肠道病毒通用引物、CA16和EV71 VP1区特异性引物直接对82份临床标本进行了初步筛查,肠道病毒阳性率达70.6%。检测病例中CA16阳性25例(25/51)、EV71阳性4例(4/51)、非CA16和EV71的肠道病毒阳性病例7例(7/51),三者比例约为6:1:2。2007年北京地区儿童轻症手足口病主要病原包括CA16和EV71,同时还存在一定比例其它肠道病毒。部分EV71毒株经测序验证及系统进化分析显示为C4基因亚型。     

A Tlx2‐Cre mouse line uncovers essential roles for hand1 in extraembryonic and lateral mesoderm

Hand1 regulates development of numerous tissues within the embryo, extraembryonic mesoderm, and trophectoderm. Systemic loss of Hand1 results in early embryonic lethality but the cause has remained unknown. To determine if Hand1 expression in extraembryonic mesoderm is essential for embryonic survival, Hand1 was conditionally deleted using the HoxB6‐Cre mouse line that expresses Cre in extraembryonic and lateral mesoderm. Deletion of Hand1 using HoxB6‐Cre resulted in embryonic lethality identical to systemic knockout. To determine if lethality is due to Hand1 function in extraembryonic mesoderm or lateral mesoderm, we generated a Tlx2‐Cre mouse line expressing Cre in lateral mesoderm but not extraembryonic tissues. Deletion of Hand1 using the Tlx2‐Cre line results in embryonic survival with embryos exhibiting herniated gut and thin enteric smooth muscle. Our results show that Hand1 regulates development of lateral mesoderm derivatives and its loss in extraembryonic mesoderm is the primary cause of lethality in Hand1‐null embryos. genesis 48:479–484, 2010. © 2010 Wiley‐Liss, Inc.     

野生植物蒲公英营养成分的研究

对野生植物蒲公英的营养成分进行了分析,结果表明,蒲公英中含有多种营养成分,丰富的矿质元素和维生素及其β-胡萝卜素。蒲公英中至少含有17种氨基酸。蒲公英营养成分分析旨在为开发利用植物资源提供科学依据。     

茭白冬芽的发育及抗寒性的形态学研究

节间横向维管组织是冬芽发育过程中所形成的特殊越冬维管结构,它们约起源于冬芽苗端倒数第五节间,其原始细胞由紧贴周缘维管束环外侧的一层薄壁细胞壁反分化而成。节间横向维管组织具有发达的木质部,但不呈V形,它们对加强冬芽发育时期及来年春天萌发期的水份和无机盐的运输起重要作用。冬芽发育过程中,其生长锥及幼叶的细胞发生了一系列细胞学变化,可归纳如下:①细胞分裂活动逐渐减弱,最终停止;②核仁周围的亮环越来越小,直至基本消失;③细胞所积累的淀粉颗粒逐渐增多增大;④在休眠期,细胞普遍产生质壁分离现象。这些细胞学变化可作为确定茭白冬芽抗寒性的有力依据。     

Hand preference and tool use in wild chimpanzees

The hand preference of chimpanzees in their natural habitat was studied at Bossou, Republic of Guinea, West Africa. The quantitative difference in left/right hand use was small in food picking and carrying. In contrast, the chimpanzees employed either the right or left hand in nutcracking behavior using a pair of stones. All adults and many adolescents and juveniles utilized one hand exclusively for holding a hammer stone. Left hand preference was more prevalent among adults. However, when adolescents and juveniles were included, there was no significant bias in the ratio of left/right handers. Nut-cracking behavior requires long-term learning of the fine manipulation of stones and nuts by both hands. Each hand has a separate role, and the hands work together in nut cracking. The differential and complementary use of both hands may be a prime factor promoting exclusive hand preference in chimpanzees comparable to that of humans.     

The use of hand morphology in the taxonomy of galagos

Measurements of volar (hand) pad area were made for 244 specimens, representing 12 species and 4 genera of galagos (sub-family Galaginae). When corrected for body weight, statistically significant differences were identified, at both the genus and species levels in the areas of the volar pads. Most informative, in terms of taxonomic differences, were measurements of two of the five pads; interdigjtal pad number 4 and thenar pad number 5. Closely related species were distinguishable on the basis of these measurements. The thick-tailed galago (Otolemur crassicaudatus) was separate from Garnett's galago (O. garnettii) and the specific status of the silver greater galago (O. argentatus) was supported. Likewise, the two needle-clawed galagos (Euoticus elegantulus andE. pallidus), recently separated on mitochodrial DNA grounds, were found to differ significantly in their volar pad morphology. These studies show that comparative studies of volar hand pad morphology provide a novel approach to the re-assessment of galago taxonomy, and may be applicable also in taxonomic studies of other prosimian groups.