幽门螺杆菌黏附素保守区蛋白的免疫原性、安全性和黏附作用的体外评价

探讨幽门螺杆菌（Hp）保守区（AB）蛋白的体外安全性、免疫原性和黏附作用,以确定AB在Hp疫苗研制中的应用价值.ELISA法测定Hp感染者血清中抗AB抗体,四唑盐比色法（MTT）测定T细胞对AB的增殖反应,流式细胞术检测AB致T细胞表达FasL的作用,二苯胺（DPA）法测定AB致T细胞凋亡率,光镜计数法研究AB抗体对Hp与胃癌细胞黏附的影响.ELISA法共检测了55份血清,以快速尿素酶实验(RUT)作为平行对照,两法的评价判断一致性程度的指标卡帕系数为0.76. 同时,低剂量AB即可刺激Hp⁺T细胞的增殖.体外安全性实验表明,AB无明显调节T细胞表达FasL的作用以及无明显致Hp^－T细胞凋亡的作用. AB抗血清能部分阻断Hp与胃癌细胞系的黏附,在光镜下表现为经抗AB兔血清预处理后,每细胞周围黏附的细菌数较免疫前兔血清预处理组显著减少（P＜0.05）.研究表明AB是安全的、具有免疫原性的Hp菌体成分,既可以刺激体液免疫,又能够提高细胞免疫,并且其抗体还可防止Hp与胃上皮细胞的黏附.     

洞庭湖区洪涝灾害成因与防治对策研究

在论述洞庭湖区洪涝灾害概况的基础上,分析了泥沙淤积与围湖垦殖、外洪内涝交织、区域协调机构缺乏与管理体制不统一等洪涝灾害的成因,并提出了调整丘岗地利用结构与重建山区植被、构建避洪耐涝复合高效生态系统、建设分蓄洪区及协调人地、人湖关系等防治对策。     

牛乳腺核基质附着区多重顺式作用序列表明其功能的多样性

高等真核细胞的染色体DNA通过基质结合区(MAR)不时地与核基质特异性结合而组织成一种空间环状结构。为了研究以DNA套环形式附着于核基质上的DNA序列的特性,从处于泌乳期的乳腺组织中克隆了多个MAR DNA序列。体外结合实验表明,这些序列能够同核基质蛋白共结合成不溶性的复合物,这些复合物可较容易的通过离心去除。其中,两个MAR序列中包含有TL、CA—和GA—阻断以及ATTA基序。这两个序列中含有多个复制／转录因子的结合位点、增强子基序、多个完全的和非完全的反向重复序列以及潜在的DNA弯曲核心序列样结构。同一DNA序列中存在不同元件的组合可能说明在控制一系列细胞的发育过程中,它们可能发挥有正的或负的调控元件的功能。     

Application of mitochondrial control region in population genetic studies of the shrimp Penaeus

This study reports a primer set for amplifying a partial fragment of about 610 bp in the fast mutating mitochondrial control region in shrimps of the genus Penaeus (Decapoda: Penaeidae). The utility of this amplified fragment for studying population differentiation and structuring, compared with more conservative mitochondrial genes (16S rRNA and COI), was explored in P. merguiensis populations over a vast geographical range based on sequence and RFLP analyses. The results indicate that the mitochondrial control region provides more informative sites and reveals more haplotypes, making it most useful for evaluating genetic variations within and between populations of Penaeus species.     

Identification and Functional Validation of a 5′ Upstream Regulatory Sequence in the Human Tyrosinase Gene Homologous to the Locus Control Region of the Mouse Tyrosinase Gene

Comparison analysis of the sequences of the mouse and human genomes has proven a powerful approach in identifying functional regulatory elements within the non‐coding regions that are conserved through evolution between homologous mammalian loci. Here, we applied computational analysis to identify regions of homology in the 5′ upstream sequences of the human tyrosinase gene, similar to the locus control region (LCR) of the mouse tyrosinase gene, located at ?15 kb. We detected several stretches of homology within the first 30 kb 5′ tyrosinase gene upstream sequences of both species that include the proximal promoter sequences, the genomic region surrounding the mouse LCR, and further upstream segments. We cloned and sequenced a 5′ upstream regulatory sequence found between ?8 and ?10 kb of the human tyrosinase locus (termed h5′URS) homologous to the mouse LCR sequences, and confirmed the presence of putative binding sites at ?9 kb, homologous to those described in the mouse tyrosinase LCR core. Finally, we functionally validated the presence of a tissue‐specific enhancer in the h5′URS by transient transfection analysis in human and mouse cells, as compared with homologous DNA sequences from the mouse tyrosinase locus. Future experiments in cells and transgenic animals will help us to understand the in vivo relevance of this newly described h5′URS sequence as a potentially important regulatory element for the correct expression of the human tyrosinase gene.     

Conservation units based on mitochondrial and nuclear DNA variation among European bullhead populations (Cottus gobio L., 1758) from Flanders, Belgium

In this study, we aimed to delineateevolutionarily significant units (ESUs) andmanagement units (MUs) for the Europeanbullhead in Flanders (Belgium). Therefore, wedetermined the genetic interrelationshipsbetween 11 bullhead populations, using lengthvariation at 7 polymorphic microsatellite lociand sequence variation in the d-loop of themitochondrial DNA (mtDNA). Despite therelatively small geographical scale of ourstudy, the analysis of the d-loop sequencesshows that the Flemish bullhead populationscontain 3 haplotype groups, which can beassigned to 3 previously described EuropeanmtDNA clades. Because of the importantdifferences between these clades, they may bedefined as evolutionarily significant units,which should be managed separately. Analysis ofmicrosatellite data reveals very high degreesof isolation between populations, with theexception of 3 pairwise comparisons whichinvolved adjacent populations. Our data suggestthat the 3 haplotype groups probably qualify asESUs, as they show phylogeographicdifferentiation for mtDNA variants as well assignificant divergence of allele frequencies atnuclear loci. However, one of these units,limited to a single population, may be ofCentral European origin. All populations of theScheldt basin meet the criteria for MUrecognition, since significantly differentmicrosatellite allele frequencies as well asprivate alleles are found. In contrast, geneticdifferentiation among the 3 populations of theMeuse basin is very low.     

Lack of mtDNA control region variation in Hainan Eld's deer: Consequence of a recent population bottleneck?

We find no genetic variation at 550bp ofmtDNA control region among 55 Hainan Eld's deerin an island population that has sufferedrecent population contractions. Congenericspecies show high levels of variation at thislocus. We use a simulation approach to test thelikelihood of various bottleneck scenarios, andshow, in the context of what is known about therecent demographic history of this population,that there are credible scenarios for abottleneck driven by hunting pressure in the1960s that could account for the lack ofvariation at this locus.     

Quantitative correlation between mRNA secondary structure around the region downstream of the initiation codon and translational efficiency in Escherichia coli

Translational efficiency in Escherichia coli is known to be strongly influenced by the secondary structure around the ribosome‐binding site and the initiation codon in the translational‐initiation region of the mRNA. Several quantitative studies have reported that translational efficiency is attributable to effects on ribosome accessibility predominantly caused by the secondary structure surrounding the ribosome‐binding site. However, the influence of mRNA secondary structure around regions downstream of the initiation codon on translational efficiency after ribosome‐binding step has not been quantitatively studied. Here, we quantitatively analyzed the relationship between secondary structure of mRNA surrounding the region downstream of the initiation codon, referred to as the downstream region (DR), and protein expression levels. Modified hairpin structures containing the initiation codon were constructed by site‐directed mutagenesis, and their effects on expression were analyzed in vivo. The minimal folding free energy (ΔG) of a local hairpin structure was found to be linearly correlated with the relative expression level over a range of fourfold change. These results demonstrate that expression level can be quantitatively controlled by changing the stability of the secondary structure surrounding the DR. Biotechnol. Bioeng. 2009; 104: 611–616 © 2009 Wiley Periodicals, Inc.     

miR-17 family miRNAs are expressed during early mammalian development and regulate stem cell differentiation

MicroRNAs are small non-coding RNAs that regulate protein expression by binding 3′UTRs of target mRNAs, thereby inhibiting translation. Similar to siRNAs, miRNAs are cleaved by Dicer. Mouse and ES cell Dicer mutants demonstrate that microRNAs are necessary for embryonic development and cellular differentiation. However, technical obstacles and the relative infancy of this field have resulted in few data on the functional significance of individual microRNAs. We present evidence that miR-17 family members, miR-17-5p, miR-20a, miR-93, and miR-106a, are differentially expressed in developing mouse embryos and function to control differentiation of stem cells. Specifically, miR-93 localizes to differentiating primitive endoderm and trophectoderm of the blastocyst. We also observe high miR-93 and miR-17-5p expression within the mesoderm of gastrulating embryos. Using an ES cell model system, we demonstrate that modulation of these miRNAs delays or enhances differentiation into the germ layers. Additionally, we demonstrate that these miRNAs regulate STAT3 mRNA in vitro. We suggest that STAT3, a known ES cell regulator, is one target mRNA responsible for the effects of these miRNAs on cellular differentiation.     

Analyses of non-leucine-rich repeat (non-LRR) regions intervening between LRRs in proteins

Background

Many proteins have LRR (leucine-rich repeat) units interrupted by non-LRRs which we call IR (non-LRR island region).

Methods

We identified proteins containing LRR@IRs (LRRs having IR) by using a new method and then analyzed their natures and distributions.

Results

LRR@IR proteins were found in over two hundred proteins from prokaryotes and from eukaryotes. These are divided into twenty-one different protein families. The IRs occur one to four times in LRR regions and range in length from 5 to 11,265 residues. The IR lengths in Fungi adenylate cyclases (acys) range from 5 to 116 residues; there are 22 LRR repeats. The IRs in Leishmania proteophosphoglycans (ppgs) vary from 105 to 11,265 residues. These results indicate that the IRs evolved rapidly. A group of LRR@IR proteins—LRRC17, chondroadherin-like protein, ppgs, and four Pseudomonas proteins—have a super motif consisting of an LRR block and its adjacent LRR@IR region. This indicates that the entire super motif experienced duplication. The sequence analysis of IRs offers functional similarity in some LRR@IR protein families.

General significance

This study suggests that various IRs and super motifs provide a great variety of structures and functions for LRRs.