Enhancement of centelloside production from cultured plants of Centella asiatica by combination of thidiazuron and methyl jasmonate

In order to produce centellosides from whole plant cultures of Centella asiatica (L.) Urban, we evaluated the synergistic effects of thidiazuron (TDZ) and methyl jasmonate (MJ) on whole plant growth and centelloside production. After 4 weeks of treatment with 0.025 mg/L of TDZ coupled with 0.1 mM MJ, the production of madecassoside and asiaticoside from whole plant cultures was estimated to be 2.40- and 2.44-fold, respectively, above that of MJ elicitation alone. When whole plants were treated with a growth regulator and an elicitor, the growth of whole plants, as compared to the controls, did not differ. Additionally, total phytosyterol content in the leaves of whole plants co-treated with MJ and TDZ was 1.08-fold greater than those of MJ alone. These results demonstrate that combined treatments not only stimulate the accumulation of centellosides in the leaves but also inhibit the reduction of phytosterol levels caused by MJ elicitation.     

Responses of soil microbial communities to prescribed burning in two paired vegetation sites in southern China

Prescribed burning is a common site preparation practice for forest plantation in southern China. However, the effects of prescribed burning on soil microbial communities are poorly understood. This study examined changes in microbial community structure, measured by phospholipid fatty acids (PLFAs), after a single prescribed burning in two paired vegetation sites in southern China. The results showed that the total amount of PLFA (totPLFA) was similar under two vegetation types in the wet season but differed among vegetation type in the dry season, and was affected significantly by burning treatment only in the wet season. Bacterial PLFA (bactPLFA) and fungal PLFA (fungPLFA) in burned plots all decreased compared to the unburned plots in both seasons (P = 0.059). Fungi appeared more sensitive to prescribed burning than bacteria. Both G⁺ bacterial PLFA and G⁻ bacterial PLFA were decreased by the burning treatment in both dry and wet seasons. Principal component analysis of PLFAs showed that the burning treatment induced a shift in soil microbial community structure. The variation in soil microbial community structure was correlated significantly to soil organic carbon, total nitrogen, available phosphorus and exchangeable potassium. Our results suggest that prescribed burning results in short-term changes in soil microbial communities but the long-term effects of prescribed burning on soil microbial community remain unknown and merit further investigation.     

Hypoxia induces beta-amyloid in association with death of RGC-5 cells in culture

Beta-amyloid (Aβ) derived from amyloid precursor protein (APP) has been associated with retinal degeneration in Alzheimer’s disease (AD) and glaucoma. This study examined whether hypoxia exposure induces Aβ accumulation in RGC-5 cells. While levels of APP mRNA and protein significantly increased in the cells, elevated abundance of Aβ was also observed in cells and culture medium between 12 or 24 and 48 h after 5% O₂ hypoxia treatment. Additionally, there is a close relationship between induction of APP and Aβ and intracellular accumulation of ROS along with loss of mitochondrial membrane potential followed by the death of RGC-5 cells in culture under hypoxia. These results suggest a possible involvement of APP and Aβ in the death of RGCs challenged by hypoxia.     

Genome-wide linkage scan of a pedigree with familial hypercholesterolemia suggests susceptibility loci on chromosomes 3q25-26 and 21q22

Background

Familial hypercholesterolemia (FH) is a heritable disorder that can increase the risk of premature coronary heart disease. Studies suggest there are substantial genetic heterogeneities for different populations. Here we tried to identify novel susceptibility loci for FH in a Chinese pedigree.

Methodology/Principal Findings

We performed a SNP-based genome-wide linkage scan with the Chinese FH pedigree. Two suggestive linkage loci not previously reported were identified on chromosomes 3q25.1-26.1 (NPL = 9.01, nominal P<0.00001, and simulated occurrence per genome scan = 1.08) and 21q22.3 (NPL = 8.95, nominal P<0.00001, and simulated occurrence per genome scan = 1.26). In the interaction analysis with a trimmed version of the pedigree, we obtained a significantly increased joint LOD score (2.70) compared with that obtained when assuming the two loci uncorrelated, suggesting that more than one locus was involved in this pedigree. Exon screening of two candidate genes ABCG1 and LSS from one of the suggestive region 21q22 didn''t report any causative mutations.

Conclusions/Significances

These results confirm complex etiologies and suggest new genetic casual factors for the FH disorder. Further study of the two candidate regions is advocated.     

镜鲤体长性状的QTL定位分析

以镜鲤良种后代为祖父母本所培育的杂交F2群体的68个个体为材料,利用553个分子标记(217个SSR和336个SNP标记)对其进行基因型检测,运用JoinMap4.0软件包对遗传连锁图谱进行构建。利用MapQTL5.0区间作图法(Interval mapping)进行QTL检测,通过置换实验(1 000次重复)确定连锁群显著性水平阈值。在对体长的区间定位中共检测到12个与体长性状相关的QTLs区间,分布在BL-1-1(SNP0137-SNP1481)、BL-4-1(SNP0092-HLJ797)、BL-5-1(SNP1268-HLJ423)、BL-7-1(HLJ870-SNP0702)、BL-12-1(SNP0922-HLJ639)、BL-16-1(HLJE351-SNP0674)、BL-25-1(SNP0394-SNP0862)、BL-35-1(HLJ668-SNP0832)、BL-43-1(SNP0389-SNP1425)、BL-47-1(HLJ057-HLJ1113)、BL-47-2(HLJ1439-HLJ1418)等11个连锁群上,解释表型变异范围是13.8%~64.9%,其中贡献率大于20%的主效QTLs有8个,是体长性状的主效QTLs区间。     

Novel Inhibitors of Staphylococcus aureus Virulence Gene Expression and Biofilm Formation

Staphylococcus aureus is a major human pathogen and one of the more prominent pathogens causing biofilm related infections in clinic. Antibiotic resistance in S. aureus such as methicillin resistance is approaching an epidemic level. Antibiotic resistance is widespread among major human pathogens and poses a serious problem for public health. Conventional antibiotics are either bacteriostatic or bacteriocidal, leading to strong selection for antibiotic resistant pathogens. An alternative approach of inhibiting pathogen virulence without inhibiting bacterial growth may minimize the selection pressure for resistance. In previous studies, we identified a chemical series of low molecular weight compounds capable of inhibiting group A streptococcus virulence following this alternative anti-microbial approach. In the current study, we demonstrated that two analogs of this class of novel anti-virulence compounds also inhibited virulence gene expression of S. aureus and exhibited an inhibitory effect on S. aureus biofilm formation. This class of anti-virulence compounds could be a starting point for development of novel anti-microbial agents against S. aureus.     

Parapapillary Atrophy: Histological Gamma Zone and Delta Zone

Background

To examine histomorphometrically the parapapillary region in human eyes.

Methodology/Principal Findings

The histomorphometric study included 65 human globes (axial length:21–37 mm). On anterior-posterior histological sections, we measured the distance Bruch''s membrane end (BME)-optic nerve margin (“Gamma zone”), BME-retinal pigment epithelium (RPE) (“Beta zone”), BME-beginning of non-occluded choriocapillaris, and BME-beginning of photoreceptor layer. “Delta zone” was defined as part of gamma zone in which blood vessels of at least 50 µm diameter were not present over a length of >300 µm. Beta zone (mean length:0.35±0.52 mm) was significantly (P = 0.01) larger in the glaucoma group than in the non-glaucomatous group. It was not significantly (P = 0.28) associated with axial length. Beta zone was significantly (P = 0.004) larger than the region with occluded choriocapillaris. Gamma zone (mean length:0.63±1.25 mm) was associated with axial length (P<0.001;r² = 0.73) with an increase starting at an axial length of 26.5 mm. It was not significantly (P = 0.24) associated with glaucomatous optic neuropathy. Delta zone (present only in eyes with axial length of ≥27 mm) was associated with axial length (P = 0.001) and scleral flange length (P<0.001) but not with glaucoma (P = 0.73).

Conclusions/Significance

Parapapillary gamma zone (peripapillary sclera without overlying choroid, Bruch''s membrane and deep retinal layers) was related with axial globe elongation and was independent of glaucoma. Delta zone (no blood vessels >50 µm diameter within gamma zone) was present only in highly axially elongated globes and was not related with glaucoma. Beta zone (Bruch''s membrane without RPE) was correlated with glaucoma but not with globe elongation. Since the region with occluded choriocapillaris was smaller than beta zone, complete loss of RPE may have occurred before complete choriocapillaris closure.     

Genome Sequence of Clostridium tunisiense TJ,Isolated from Drain Sediment from a Pesticide Factory

Clostridium tunisiense is a Gram-positive, obligate anaerobe that was first isolated in an anaerobic evironment under eutrophication. Here we report the first genome sequence of the Clostridium tunisiense TJ isolated from drain sediment of a pesticide factory in Tianjin, China. The genome is of great importance for both basic and application research.     

Co-expression of Dsb proteins enables soluble expression of a single-chain variable fragment (scFv) against human type 1 insulin-like growth factor receptor (IGF-1R) in E. coli

Type 1 insulin-like growth factor receptor (IGF-1R) is a promising therapeutic target for cancer treatment. A single-chain variable fragment (scFv) against human IGF-1R forms inclusion body when expressed in periplasmic space of E. coli routinely. Here, we described that co-expression of appropriate disulfide bonds (Dsb) proteins known to catalyze the formation and isomerization of Dsb can markedly recover the soluble expression of target scFv in E. coli. A 50 % recovery in solubility of the scFv was observed upon co-expression of DsbC alone, and a maximum solubility (80 %) was obtained when DsbA and DsbC were co-expressed in combination. Furthermore, the soluble scFv present full antigen-binding activity with IGF-1R, suggesting its correct folding. This study also suggested that the selection of Dsb proteins should be tested case-by-case if the approach of co-expression of Dsb system is adopted to address the problem of insoluble expression of proteins carrying Dsb.