Structural and functional analysis of the single-strand origin of replication from the lactococcal plasmid pWV01

The single-strand origin (SSO) of the rolling-circle (RC), broad-host-range lactococcal plasmid pWVO1 was functionally characterized. The activity of this SSO in the conversion of single-stranded DNA to double-stranded DNA was tested both in vivo and in vitro. In addition, the effect of this SSO on plasmid maintenance was determined. The functional pWVO1 SSO comprises a 250 by region, containing two inverted repeats (IRs). The activity of each IR was tested, separately and in combination, in a plasmid derivative that was otherwise completely devoid of structures that might function as SSO. One of the IRs (IR 1) showed some homology with other previously described SSOs of the SSO_A type, as well as with the conversion signal of the Escherichia coli phage X174. This IR was shown to have a partial, RNA polymerise-independent activity in complementary strand synthesis, both in vivo and in vitro. The second IR, which had no activity of its own, was required for full SSO activity, both in vivo and in vitro. The conversion of single-stranded DNA to the double-stranded form by the complete SSO was only partly sensitive to inhibition by rifampicin, indicating the existence of an RNA polymerase-independent pathway for this event. The results suggest that the pWVO1 SSO can be activated by two different routes: an RNA polymerise-dependent one (requiring the entire SSO), and an RNA polymerase-independent one (requiring only IR I).     

Intratumoral expression of IL-17 and its prognostic role in gastric adenocarcinoma patients

In this study, we characterized the intratumoral expression of IL-17 and CD8(+) TILs in gastric adenocarcinoma patients after resection and determined the correlation between the survival probability of gastric adenocarcinoma patients and the expression of IL-17 in tumor. Expression of IL-17 and CD8 was assessed by immunohistochemistry, and the prognostic effects of intratumoral IL-17 expression and CD8(+) TILs were evaluated by Cox regression and Kaplan-Meier analysis. Immunohistochemical detection revealed the presence of IL-17 and CD8(+) cells in gastric adenocarcinoma tissue samples (90.6%, 174 out of 192 patients and 96.9%, 186 out of 192 patients, respectively). We have also found that intratumoral IL-17 expression was significantly correlated with age (p=0.004) and that the number of CD8(+)TILs was significantly correlated with UICC staging (p=0.012) and the depth of tumor invasion (p=0.022). The five-year overall survival probability among patients intratumorally expressing higher levels of IL-17 was significantly better than those expressing lower levels of IL-17 (p=0.036). Multivariate Cox proportional hazard analyses revealed that intratumoral IL-17 expression (HR: 0.521; 95% CI: 0.329-0.823; p=0.005) was an independent factor affecting the five-year overall survival probability. We conclude that low levels of intratumoral IL-17 expression may indicate poor prognosis in gastric adenocarcinoma patients.     

激素对亚洲玉米螟幼虫滞育的影响

激素对亚洲玉米螟幼虫滞育的影响＊赵章武＊＊曹梅讯（中国科学院上海昆虫研究所上海２０００２５）亚洲玉米螟Ｏｓｔｒｉｎｉａｆｕｒｎａｃａｌｉｓ是我国乃至亚洲地区的重要农业害虫之一。它具有兼性滞育的特点,年发生１～７代,以末龄老熟滞育幼虫越冬。来年春天终止...     

Cellular Uptake and Antitumor Activity of DOX-hyd-PEG-FA Nanoparticles

A PEG-based, folate mediated, active tumor targeting drug delivery system using DOX-hyd-PEG-FA nanoparticles (NPs) were prepared. DOX-hyd-PEG-FA NPs showed a significantly faster DOX release in pH 5.0 medium than in pH 7.4 medium. Compared with DOX-hyd-PEG NPs, DOX-hyd-PEG-FA NPs increased the intracellular accumulation of DOX and showed a DOX translocation from lysosomes to nucleus. The cytotoxicity of DOX-hyd-PEG-FA NPs on KB cells was much higher than that of free DOX, DOX-ami-PEG-FA NPs and DOX-hyd-PEG NPs. The cytotoxicity of DOX-hyd-PEG-FA NPs on KB cells was attenuated in the presence of exogenous folic acid. The IC₅₀ of DOX-hyd-PEG-FA NPs and DOX-hyd-PEG NPs on A549 cells showed no significant difference. After DOX-hyd-PEG-FA NPs were intravenously administered, the amount of DOX distributed in tumor tissue was significantly increased, while the amount of DOX distributed in heart was greatly decreased as compared with free DOX. Compared with free DOX, NPs yielded improved survival rate, prolonged life span, delayed tumor growth and reduced the cardiotoxicity in tumor bearing mice model. These results indicated that the acid sensitivity, passive and active tumor targeting abilities were likely to act synergistically to enhance the drug delivery efficiency of DOX-hyd-PEG-FA NPs. Therefore, DOX-hyd-PEG-FA NPs are a promising drug delivery system for targeted cancer therapy.     

Diversity of endophytic bacteria within nodules of the Sphaerophysa salsula in different regions of Loess Plateau in China

A total of 115 endophytic bacteria were isolated from root nodules of the wild legume Sphaerophysa salsula grown in two ecological regions of Loess Plateau in China. The genetic diversity and phylogeny of the strains were revealed by restriction fragment length polymorphism and sequencing of 16S rRNA gene and enterobacterial repetitive intergenic consensus-PCR. Their symbiotic capacity was checked by nodulation tests and analysis of nifH gene sequence. This is the first systematic study on endophytic bacteria associated with S. salsula root nodules. Fifty of the strains found were symbiotic bacteria belonging to eight putative species in the genera Mesorhizobium, Rhizobium and Sinorhizobium, harboring similar nifH genes; Mesorhizobium gobiense was the main group and 65 strains were nonsymbiotic bacteria related to 17 species in the genera Paracoccus, Sphingomonas, Inquilinus, Pseudomonas, Serratia, Mycobacterium, Nocardia, Streptomyces, Paenibacillus, Brevibacillus, Staphylococcus, Lysinibacillus and Bacillus, which were universally coexistent with symbiotic bacteria in the nodules. Differing from other similar studies, the present study is the first time that symbiotic and nonsymbiotic bacteria have been simultaneously isolated from the same root nodules, offering the possibility to accurately reveal the correlation between these two kinds of bacteria. These results provide valuable information about the interactions among the symbiotic bacteria, nonsymbiotic bacteria and their habitats.