Dynamic expression of the LAP family of genes during early development of <Emphasis Type="Italic">Xenopus tropicalis</Emphasis>

The leucine-rich repeats and PDZ (LAP) family of genes are crucial for the maintenance of cell polarity as well as for epithelial homeostasis and tumor suppression in both vertebrates and invertebrates. Four members of this gene family are known: densin, erbin, scribble and lano. Here, we identified the four members of the LAP gene family in Xenopus tropicalis and studied their expression patterns during embryonic development. The Xenopus LAP proteins show a conserved domain structure that is similar to their homologs in other vertebrates. In Xenopus embryos, these genes were detected in animal cap cells at the early gastrula stage. At later stages of development, they were widely expressed in epithelial tissues that are highly polar in nature, including the neural epithelia, optic and otic vesicles, and in the pronephros. These data suggest that the roles of the Xenopus LAP genes in the control of cell polarity and morphogenesis are conserved during early development. Erbin and lano show similar expression patterns in the developing head, suggesting potential functional interactions between the two molecules in vivo.     

Assessing the patterns of linkage disequilibrium in genic regions of the human genome

We used the genotyping data generated by the International HapMap Project to study the patterns of linkage disequilibrium (LD) in human genic regions. LD patterns for 11,998 genes from 11 HapMap populations were identified by analyzing the distribution of haplotype blocks. The genes were prioritized using LD levels. The results showed that there were significant differences in the degree of LD between genes. Genes with high or low LD (the upper and lower quartiles of the LD levels) fell into different Gene Ontology functional categories. The high LD genes clustered preferentially in the metabolic process, macromolecule localization and cell-cycle categories, whereas the low LD genes clustered in the developmental process, ion transport, and immune and regulation system categories. Furthermore, we subdivided the genic region into 3'-UTR, 5'-UTR and CDS (coding region), and compared the different LD patterns in these subregions. We found that the LD patterns in low LD genes had a more interspersed block structure compared with the high LD genes. This was especially true in the CDS and 5'-UTR. The extent of LD was somewhat higher in 5'-UTRs compared with 3'-UTRs for both high and low LD genes. In addition, we assessed the overlap for the intragenic LD regions and found that the LD regions in high LD genes were more consistent among populations. Comprehensive information about the distribution of LD patterns in gene regions in populations may provide insights into the evolutionary history of humans and help in the selection of biomarkers for disease association studies.     

Adaption of seasonal H1N1 influenza virus in mice

The experimental infection of a mouse lung with influenza A virus has proven to be an invaluable model for studying the mechanisms of viral adaptation and virulence. The mouse adaption of human influenza A virus can result in mutations in the HA and other proteins, which is associated with increased virulence in mouse lungs. In this study, a mouse-adapted seasonal H1N1 virus was obtained through serial lung-to-lung passages and had significantly increased virulence and pathogenicity in mice. Genetic analysis indicated that the increased virulence of the mouse-adapted virus was attributed to incremental acquisition of three mutations in the HA protein (T89I, N125T, and D221G). However, the mouse adaption of influenza A virus did not change the specificity and affinity of receptor binding and the pH-dependent membrane fusion of HA, as well as the in vitro replication in MDCK cells. Notably, infection with the mouse adapted virus induced severe lymphopenia and modulated cytokine and chemokine responses in mice. Apparently, mouse adaption of human influenza A virus may change the ability to replicate in mouse lungs, which induces strong immune responses and inflammation in mice. Therefore, our findings may provide new insights into understanding the mechanisms underlying the mouse adaption and pathogenicity of highly virulent influenza viruses.     

Use of microRNA Let-7 to control the replication specificity of oncolytic adenovirus in hepatocellular carcinoma cells

Highly selective therapy for hepatocellular carcinoma (HCC) remains an unmet medical need. In present study, we found that the tumor suppressor microRNA, let-7 was significantly downregulated in a proportion of primary HCC tissues (12 of 33, 36.4%) and HCC cell lines. In line with this finding, we have engineered a chimeric Ad5/11 fiber oncolytic adenovirus, SG7011(let7T), by introducing eight copies of let-7 target sites (let7T) into the 3' untranslated region of E1A, a key gene associated with adenoviral replication. The results showed that the E1A expression (both RNA and protein levels) of the SG7011(let7T) was tightly regulated according to the endogenous expression level of the let-7. As contrasted with the wild-type adenovirus and the control virus, the replication of SG7011(let7T) was distinctly inhibited in normal liver cells lines (i.e. L-02 and WRL-68) expressing high level of let-7 (>300 folds), whereas was almost not impaired in HCC cells (i.e. Hep3B and PLC/PRF/5) with low level of let-7. Consequently, the cytotoxicity of SG7011(let7T) to normal liver cells was successfully decreased while was almost not attenuated in HCC cells in vitro. The antitumor ability of SG7011(let7T)in vivo was maintained in mice with Hep3B xenograft tumor, whereas was greatly decreased against the SMMC-7721 xenograft tumor expressing a high level of let-7 similar with L-02 when compared to the wild-type adenovirus. These results suggested that SG7011(let7T) may be a promising anticancer agent or vector to mediate the expression of therapeutic gene, broadly applicable in the treatment for HCC and other cancers where the let-7 gene is downregulated.     

NF-κB induced the donor liver cold preservation related acute lung injury in rat liver transplantation model

Background

We have observed at our clinical work that acute lung injury (ALI) often occurs in patients transplanted with donor livers persevered for long time. So, we conducted this study to investigate the influence of cold preservation time (CPT) of donor liver on ALI induced by liver transplantation (LT), and further study the role of nuclear factor-κB (NF-κB) in the process.

Methods

Wistar rats were used as donors and recipients to establish orthotopic rat liver transplantation models. Donor livers were preserved at 4°C for different lengths of time. The effect of NF-κB inhibitor, ammonium pyrrolidinedithiocarbamate (PDTC), on ALI was detected. All samples were harvested after 3 h reperfusion. The severity of liver injury was evaluated first. The expressions of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in liver tissue and liver outflow serum were measured respectively. The severity indexes of ALI, the activity of NF-κB and inhibitor-κBα (I-κBα) in lung/liver were measured accordingly.

Results

With the prolonged liver CPT, the liver damage associated indexes and ALI-related indexes all increased significantly. TNF-α and IL-1β in liver outflow serum increased accordingly, and the activity of NF-κB in liver/lung increased correspondingly. All these ALI-associated indexes could be partially reversed by the use of PDTC.

Conclusions

Extended CPT aggravates the damage of donor liver and induces the expressions of TNF-α and IL-1β in liver. These inflammatory factors migrate to lung via liver outflow blood and activate NF-κB in lung, inducing ALI finally. NF-κB may play a critical role in LT-related ALI. Patients with or at risk of ALI may benefit from acute anti-inflammatory treatment with PDTC.     

Lack of association of SULT1A1 R213H polymorphism with colorectal cancer: a meta-analysis

Background

A number of case-control studies were conducted to investigate the association of SULT1A1 R213H polymorphisms with colorectal cancer (CRC) in humans. But the results were not always consistent. We performed a meta-analysis to examine the association between the SULT1A1 R213H polymorphism and CRC.

Methods and Findings

Data were collected from the following electronic databases: PubMed, Elsevier Science Direct, Excerpta Medica Database, and Chinese Biomedical Literature Database, with the last report up to September 2010. A total of 12 studies including 3,549 cases and 5,610 controls based on the search criteria were involved in this meta-analysis. Overall, no significant association of this polymorphism with CRC was found (H versus R: OR = 1.04, 95%CI = 0.94–1.16, P = 0.46; HR+HH versus RR: OR = 1.01, 95%CI = 0.92–1.11, P = 0.81; HH versus RR+HR: OR = 1.01, 95%CI = 0.74–1.38, P = 0.95; HH versus RR: OR = 1.00, 95%CI = 0.77–1.31, P = 0.98; HR versus RR: OR = 1.01, 95%CI = 0.92–1.11, P = 0.86). In subgroup analysis, we also did not find any significant association in Cauasians (H versus R: OR = 1.02, 95%CI = 0.92–1.15, P = 0.68; HR+HH versus RR: OR = 0.99, 95%CI = 0.91–1.09, P = 0.90; HH versus RR+HR: OR = 1.01, 95%CI = 0.73–1.39, P = 0.97; HH versus RR: OR = 0.99, 95%CI = 0.75–1.31, P = 0.94; HR versus RR: OR = 0.99, 95%CI = 0.90–1.09, P = 0.85). The results were not materially altered after the studies which did not fulfill Hardy-Weinberg equilibrium were excluded (H versus R: OR = 1.06, 95%CI = 0.95–1.19, P = 0.31; HR+HH versus RR: OR = 1.03, 95%CI = 0.93–1.13, P = 0.56; HH versus RR+HR: OR = 1.10, 95%CI = 0.78–1.56, P = 0.57; HH versus RR: OR = 1.09, 95%CI = 0.83–1.44, P = 0.53; HR versus RR: OR = 1.02, 95%CI = 0.92–1.13, P = 0.75).

Conclusion

This meta-analysis demonstrates that there is no association between the SULT1A1 R213H polymorphism and CRC.     

Correlation of N-myc downstream-regulated gene 1 subcellular localization and lymph node metastases of colorectal neoplasms

In colorectal neoplasms, N-myc downstream-regulated gene 1 (NDRG1) is a primarily cytoplasmic protein, but it is also expressed on the cell membrane and in the nucleus. NDRG1 is involved in various stages of tumor development in colorectal cancer, and it is possible that the different subcellular localizations may determine the function of NDRG1 protein. Here, we attempt to clarify the characteristics of NDRG1 protein subcellular localization during the progression of colorectal cancer. We examined NDRG1 expression in 49 colorectal cancer patients in cancerous, non-cancerous, and corresponding lymph node tissues. Cytoplasmic and membrane NDRG1 expression was higher in the lymph nodes with metastases than in those without metastases (P < 0.01). Nuclear NDRG1 expression in colorectal neoplasms was significantly higher than in the normal colorectal mucosa, and yet the normal colorectal mucosa showed no nuclear expression. Furthermore, our results showed higher cytoplasmic NDRG1 expression was better for differentiation, and higher membrane NDRG1 expression resulted in a greater possibility of lymph node metastasis. These data indicate that a certain relationship between the cytoplasmic and membrane expression of NDRG1 in lymph nodes exists with lymph node metastasis. NDRG1 expression may translocate from the membrane of the colorectal cancer cells to the nucleus, where it is involved in lymph node metastasis. Combination analysis of NDRG1 subcellular expression and clinical variables will help predict the incidence of lymph node metastasis.     

Differences in β-strand Populations of Monomeric Aβ40 and Aβ42

Using homonuclear ¹H NOESY spectra, with chemical shifts, ³J_H^N_H^α scalar couplings, residual dipolar couplings, and ¹H-¹⁵N NOEs, we have optimized and validated the conformational ensembles of the amyloid-β 1–40 (Aβ40) and amyloid-β 1–42 (Aβ42) peptides generated by molecular dynamics simulations. We find that both peptides have a diverse set of secondary structure elements including turns, helices, and antiparallel and parallel β-strands. The most significant difference in the structural ensembles of the two peptides is the type of β-hairpins and β-strands they populate. We find that Aβ42 forms a major antiparallel β-hairpin involving the central hydrophobic cluster residues (16–21) with residues 29–36, compatible with known amyloid fibril forming regions, whereas Aβ40 forms an alternative but less populated antiparallel β-hairpin between the central hydrophobic cluster and residues 9–13, that sometimes forms a β-sheet by association with residues 35–37. Furthermore, we show that the two additional C-terminal residues of Aβ42, in particular Ile-41, directly control the differences in the β-strand content found between the Aβ40 and Aβ42 structural ensembles. Integrating the experimental and theoretical evidence accumulated over the last decade, it is now possible to present monomeric structural ensembles of Aβ40 and Aβ42 consistent with available information that produce a plausible molecular basis for why Aβ42 exhibits greater fibrillization rates than Aβ40.     

市售酸奶中乳酸菌的鉴定与耐药性

[目的]检测市售酸奶中乳酸菌的种类及其耐药情况.[方法]收集10种来自5个不同厂家的酸奶,通过细菌基因组重复基因外回文序列-PCR (repetitive extragenic palindromic-PCR,rep-PCR)结合16S rRNA同源性分析的方法对分离的乳酸菌进行基因分型和菌种鉴定.利用药敏纸片扩散法(K-B法)对分离的乳酸菌进行针对7种抗生素的药敏实验,用PCR特异性扩增结合测序的方法检测每个样品中不同基因型菌株的耐药基因(包括红霉素耐药基因erm A、erm B和四环素耐药基因tetM、tetK、tet S、tetQ、tetO、tetL、tetW).[结果]10种市售酸奶中分离到100株乳酸菌.其中,德氏乳杆菌保加利亚亚种(Lactobacillus delbrueckii ssp.bulgaricus)23株,干酪乳杆菌(Lactobacillus casei)26株,嗜热链球菌(Streptococcus thermophilus)30株,嗜酸乳杆菌(Lactobacillus acidophilus)5株,植物乳杆菌(Lactobacillus plantarum)6株,副干酪乳杆菌(Lactobacillus paracasei)10株.药敏实验发现所有100株乳酸菌均对链霉素和庆大霉素耐药,42株对万古霉素耐药,没有菌株对头孢氨苄,四环素,红霉素以及土霉素耐药.在28株经过16S rRNA测序的乳酸菌中检测到5种不同的耐药基因,在8株乳酸菌中检测到erm B基因,4株检测到tetK基因,2株菌检测到tetL基因,4株菌检测到tet M基因,2株菌检测到tet O基因,没有检测到erm A,tet S,tet Q,tet W基因.28株乳酸菌中有15株(53.57%)检测到耐药基因,其中有4株L delbrueckii ssp.bulgaricus检测到2-3种不同的耐药基因.[结论]本研究在市售酸奶中除了检测到商品标签上标注的L.delbrueckii ssp.bulgaricus和S.thermophilus以外,还检测到商标上没有标注的乳酸菌;作为常用发酵剂的德氏乳杆菌保加利亚亚种和嗜热链球菌更容易检测到耐药基因;分离得到的乳酸菌均对红霉素和四环素敏感却检测到相应的耐药基因,再一次证明了没有耐药表型的菌株也可能携带耐药基因.     

The higher expression and distribution of 9-cis-epoxycarotenoid dioxygenase1 (AhNCED1) from Arachis hyopgaea L. contribute to tolerance to water stress in a drought-tolerant cultivar

The 9-cis-epoxycarotenoid dioxygenase (NCED) is thought to be the rate-limiting enzyme in the abscisic acid (ABA) biosynthetic pathway. In this study, transient expression of AhNCED1 and ABA distribution were detected in the vascular cambium of a drought-tolerant peanut cultivar (Yueyou 7) under a water stress treatment. It caused increases in ABA content in this region. The synthesis of ABA and AhNCED1 in the leaves of Yueyou 7 took place more quickly than in the control cultivar (Shanyou 523). Furthermore, AhNCED1 mRNA and proteins were induced in Yueyou 7 than in Shanyou 523, coinciding with greater ABA accumulation. During the seedling, blooming, and fruiting stages, AhNCED1 protein expression was higher in Yueyou 7 than in Shanyou 523, and it was induced more quickly when the plants were under water stress. These data suggest that the drought-tolerant cultivar can synthesize and distribute ABA more rapidly than does the control cultivar because of a high level of AhNCED1 expression, which then modulates physiological responses under water stress conditions.