Identification of natural recombinants derived from PCV2a and PCV2b.

Porcine circovirus type 2 (PCV2) is considered to be the main pathogen in PC-associated diseases, and significantly affects the global pig-producing industry. PCV2 continuously evolves by point mutations and genome recombinations. In the present study, we aimed to further identify recombinant PCV2 strains. We used polymerase chain reaction to detect PCV2 in the carcasses of pigs with suspected infections from different regions of Guangdong Province in China. DNA was extracted from samples with confirmed infection and full- genome amplification, sequencing, phylogenetic tree construction, gene recombination detection, and sequence alignment were performed in gene recombination analysis. Our results show that recombination occurred between the strains SHC (DQ104421) and ZhuJi2003 (AY579893). The recombination resulted in three recombinants: GD003 (KM503044), GD005 (KM487708), and GD008 (KM487709). Further analyses revealed that these novel recombinants appeared to result from recombination between the PCV2a and PCV2b strains, with crossover regions located in ORF2. This study was a comprehensive analysis that used several different methods, which demonstrated that a cluster of PCV2 strains resulted from the same type of inter-genotypic recombination pattern, with a breakpoint in the structural protein coding region. The results of our study provide both information on the recombination mechanism and disease pathogenesis and useful data for the prevention of PCV2 in the swine industry.

Association between the -77T>C polymorphism in the DNA repair gene XRCC1 and lung cancer risk.

Numerous studies have evaluated the association between the X-ray repair cross-complementing group 1 (XRCC1) DNA repair gene polymorphism -77T>C and lung cancer risk. However, this association is controversial. We used PubMed and Embase to identify 5 case-control studies, which included 2488 lung cancer cases and 2576 controls, for inclusion in a comprehensive meta-analysis in order to assess this association. Two independent reviewers extracted data from the studies, and ORs with 95%CIs were calculated. When all studies were pooled, we found a significant association between the -77T>C polymorphism and lung cancer risk (TT vs CC: OR = 0.52, 95%CI = 0.34-0.80, P = 0.49; TT vs CT: OR = 0.71, 95%CI = 0.62-0.81, P = 0.69; dominant model: OR = 1.45, 95%CI = 1.27-1.66, P = 0.64; recessive model: OR = 0.54, 95%CI = 0.36-0.82, P = 0.24). In a subgroup analysis of nationalities, the -77T>C polymorphism was significantly associated with lung cancer risk in Asian patients. In conclusion, the XRCC1 -77T>C polymorphism might be related to increased risk of lung cancer in Asians. Future studies are needed for conclusive evidence about this association.

Identification of 18 genes encoding necrosis-inducing proteins from the plant pathogen Phytophthora capsici (Pythiaceae: Oomycetes).

Phytophthora capsici is an aggressive plant pathogen that affects solanaceous and cucurbitaceous hosts. Necrosis-inducing Phytophthora proteins (NPPs) are a group of secreted toxins found particularly in oomycetes. Several NPPs from Phytophthora species trigger plant cell death and activate host defense gene expression. We isolated 18 P. capsici NPP genes, of which 12 were active during hypha growth from a Phytophthora stain isolated from pepper (Capsicum annuum) plants in China. The 18 predicted proteins had a sequence homology of 46.26%. The 18 Pcnpp sequences had a conserved GHRHDWE motif and fell into two groups. Eleven sequences in group 1 had two conserved cysteine residues, whereas the other seven sequences in group 2 lacked these two cysteine residues. A phylogenetic tree was constructed on the basis of the alignment of the predicted protein sequences of 52 selected NPP genes from oomycetes, fungi and bacteria from Genbank. The tree did not rigorously follow the taxonomic classification of the species; all the NPPs from oomycetes formed their own clusters, while fungal sequences were grouped into two separate clades, indicating that based on NPPs, we can separate oomycetes from fungi and bacteria, and that expansion of the NPP family was a feature of Phytophthora evolution.

Cigarette smoke enhances {beta}-defensin 2 expression in rat airways via nuclear factor-{kappa}B activation.

ß-defensin 2 (BD-2), an antimicrobial peptide, participates in airway defence. Cigarette smoke (CS) is a major risk factor for the development of chronic obstructive pulmonary disease. This study mainly aims to investigate the effect of CS on rat BD-2 (rBD-2) expression in rat airways. Rats were exposed to CS and treated with caffeic acid phenethyl ester (CAPE), a nuclear factor (NF)-κB inhibitor, or astragaloside IV (AS-IV), an active ingredient of Astragalus mongholicus. Besides the analysis of bronchoalveolar lavage fluid (BALF) and histological changes after CS exposure, rBD-2 expression was investigated with immunohistochemistry, reverse transcription PCR and ELISA. Total glutathione and nitric oxide (NO) levels in rat lungs were also detected. CS exposure markedly increased rBD-2 immunoreactivity, as well as rBD-2 mRNA and protein levels in rat airways, which were inhibited by CAPE treatment. Moreover, associated airway inflammation induced by CS was demonstrated by histological changes, increased cell counts and pro-inflammatory cytokines in BALF, and NF-κB activation and high levels of total glutathione and NO, which were all reversed by AS-IV in a dose-dependent fashion. In conclusion, CS exposure induces rBD-2 expression in rat airways via a NF-κB-dependent pathway, and AS-IV attenuates CS-induced airway inflammation due to its anti-inflammatory and antioxidant properties, at least partly through NF-κB inactivation.

N-type calcium channels and their regulation by GABAB receptors in axons of neonatal rat optic nerve.

Axons of neonatal rat optic nerves exhibit fast calcium transients in response to brief action potential stimulation. In response to one to four closely spaced action potentials, evoked calcium transients showed a fast-rising phase followed by a decay with a time constant of approximately 2-3 sec. By selective staining of axons or glial cells with calcium dyes, it was shown that the evoked calcium transient originated from axons. The calcium transient was caused by influx because it was eliminated when bath calcium was removed. Pharmacological profile studies with calcium channel subtype-specific peptides suggested that 58% of the evoked calcium influx was accounted for by N-type calcium channels, whereas L- and P/Q-type calcium channels had little, if any, contribution. The identity of the residual calcium influx remains unclear. GABA application caused a dramatic reduction of the amplitude of the action potential and the associated calcium influx. When GABAA receptors were blocked by bicuculline, the inhibitory effect of GABA on the action potential was eliminated, whereas that on the calcium influx was not, indicating involvement of GABAB receptors. Indeed, the calcium influx was inhibited by the GABAB receptor agonist baclofen. This baclofen effect was occluded by a previous block of N-type calcium channels and was unaffected by the broad-spectrum K+ channel blocker 4-AP. We conclude that neonatal rat optic nerve axons express N-type calcium channels, which are subjected to regulation by G-protein-coupled GABAB receptors. We suggest that receptor-mediated inhibition of axonal calcium channels plays a protective role in neonatal anoxic and/or ischemic injury.