Pythium vexans causing patch canker of rubber trees on Hainan Island,China

This is the first report of patch canker disease of rubber trees (clone RRIM600) in China. It is characterized by discrete irregular patches of rotted, discolored bark and wood, accompanied by a decrease in latex flow. A total of seven isolates of Pythium vexans were obtained from the diseased bark of the trunks and roots of rubber trees. Inoculating these isolates into healthy, mature rubber trees resulted in symptoms similar to patch canker and the same fungal species was re-isolated from the diseased tissues. This is also the first record of Py. vexans in Hainan.     

Headloop suppression PCR and its application to selective amplification of methylated DNA sequences

Selective amplification in PCR is principally determined by the sequence of the primers and the temperature of the annealing step. We have developed a new PCR technique for distinguishing related sequences in which additional selectivity is dependent on sequences within the amplicon. A 5′ extension is included in one (or both) primer(s) that corresponds to sequences within one of the related amplicons. After copying and incorporation into the PCR product this sequence is then able to loop back, anneal to the internal sequences and prime to form a hairpin structure—this structure is then refractory to further amplification. Thus, amplification of sequences containing a perfect match to the 5′ extension is suppressed while amplification of sequences containing mismatches or lacking the sequence is unaffected. We have applied Headloop PCR to DNA that had been bisulphite-treated for the selective amplification of methylated sequences of the human GSTP1 gene in the presence of up to a 10⁵-fold excess of unmethylated sequences. Headloop PCR has a potential for clinical application in the detection of differently methylated DNAs following bisulphite treatment as well as for selective amplification of sequence variants or mutants in the presence of an excess of closely related DNA sequences.     

Genomic blueprint of Hahella chejuensis, a marine microbe producing an algicidal agent

Harmful algal blooms, caused by rapid growth and accumulation of certain microalgae in the ocean, pose considerable impacts on marine environments, aquatic industries and even public health. Here, we present the 7.2-megabase genome of the marine bacterium Hahella chejuensis including genes responsible for the biosynthesis of a pigment which has the lytic activity against a red-tide dinoflagellate. H.chejuensis is the first sequenced species in the Oceanospiralles clade, and sequence analysis revealed its distant relationship to the Pseudomonas group. The genome was well equipped with genes for basic metabolic capabilities and contained a large number of genes involved in regulation or transport as well as with characteristics as a marine heterotroph. Sequence analysis also revealed a multitude of genes of functional equivalence or of possible foreign origin. Functions encoded in the genomic islands include biosynthesis of exopolysacchrides, toxins, polyketides or non-ribosomal peptides, iron utilization, motility, type III protein secretion and pigmentation. Molecular structure of the algicidal pigment, which was determined through LC-ESI-MS/MS and NMR analyses, indicated that it is prodigiosin. In conclusion, our work provides new insights into mitigating algal blooms in addition to genetic make-up, physiology, biotic interactions and biological roles in the community of a marine bacterium.     

Polymorphisms of complement receptor 1 and interleukin-10 genes and systemic lupus erythematosus: a meta-analysis

A number of studies have tested the association of the complement receptor 1 (CR1) and Interleukin-10 (IL10) polymorphisms with systemic lupus erythematosus (SLE), but reported conflicting results. The aim of the study is to explore whether the CR1 and IL10 genes are associated with SLE susceptibility. We surveyed studies on the CR1 and IL10 polymorphisms and SLE using comprehensive Medline search and review of the references. A meta-analysis was conducted in a fixed effects model or random effects model based on between-study heterogeneity. Eighteen comparisons from 13 studies were included in the CR1 meta-analysis and a total of 16 separate comparisons were used for the IL10 meta-analysis. The CR1 meta-analysis showed no significant association of the CR1 functional polymorphisms with SLE. In contrast, the S structural variant of the CR1 showed a significant association (OR=1.544, 95% CI, 1.217–1.959, P<0.001). Stratification by ethnicity indicated that the CR1 S variant was associated with SLE in Caucasians (OR=1.667, 95% CI, 1.193–2.357, P=0.003). The IL10 meta-analysis showed a significant association between SLE and the G11 allele of IL10.G (OR=1.279, 95% CI; 1.027–1.593, P=0.028) in whole populations, and IL10 promoter −1082G allele was associated with SLE in Asians (OR=1.358, 95% CI; 1.015–1.816, P=0.039). In conclusion, the CR1 meta-analysis revealed the association of the S structural variant of the CR1 with SLE and the IL10 meta-analysis showed the association of IL10.G11 allele and SLE in whole populations and the association between promoter -A1082G polymorphism and SLE in Asians.     

Encapsulating live cells with water-soluble chitosan in physiological conditions

A new class of microcapsules was prepared under physiological conditions by polyelectrolyte complexation between two oppositely-charged, water-soluble polymers. The microcapsules consisted of an inner core of half N-acetylated chitosan and an outer shell of methacrylic acid (MAA) (20.4%)-hydroxyethyl methacrylate (HEMA) (27.4%)-methyl methacrylate (MMA) (52.2%) (MAA-HEMA-MMA) terpolymer. Both 400 and 150 kDa half N-acetylated chitosans maintained good water solubility and supplied enough protonated amino groups to coacervate with terpolymer at pH 7.0-7.4, in contrast to other chitosan-based microcapsules which must be prepared at pH <6.5. The viscosity of half N-acetylated chitosan solutions between 80 and 3000 cPas allowed the formation of microcapsules with spherical shape. Molar mass, pH and concentration of half N-acetylated chitosan, and reaction time, influenced the morphology, thickness and porosity of the microcapsules. Microcapsules formed with high concentration of half N-acetylated chitosan exhibited improved mechanical stability, whereas microcapsules formed with low concentration of half N-acetylated chitosan exhibited good permeability. This 3D microenvironment has been configured to cultivate sensitive anchorage-dependent cells such as hepatocytes to maintain high level of functions.     

The G protein-coupled receptor kinase-2 is a TGFbeta-inducible antagonist of TGFbeta signal transduction

Signaling from the activin/transforming growth factor beta (TGFbeta) family of cytokines is a tightly regulated process. Disregulation of TGFbeta signaling is often the underlying basis for various cancers, tumor metastasis, inflammatory and autoimmune diseases. In this study, we identify the protein G-coupled receptor kinase 2 (GRK2), a kinase involved in the desensitization of G protein-coupled receptors (GPCR), as a downstream target and regulator of the TGFbeta-signaling cascade. TGFbeta-induced expression of GRK2 acts in a negative feedback loop to control TGFbeta biological responses. Upon TGFbeta stimulation, GRK2 associates with the receptor-regulated Smads (R-Smads) through their MH1 and MH2 domains and phosphorylates their linker region. GRK2 phosphorylation of the R-Smads inhibits their carboxyl-terminal, activating phosphorylation by the type I receptor kinase, thus preventing nuclear translocation of the Smad complex, leading to the inhibition of TGFbeta-mediated target gene expression, cell growth inhibition and apoptosis. Furthermore, we demonstrate that GRK2 antagonizes TGFbeta-induced target gene expression and apoptosis ex vivo in primary hepatocytes, establishing a new role for GRK2 in modulating single-transmembrane serine/threonine kinase receptor-mediated signal transduction.