The peptide growth factor, phytosulfokine, attenuates pattern-triggered immunity

Pattern-triggered immunity (PTI) is triggered by recognition of elicitors called microbe-associated molecular patterns (MAMPs). Although immune responses may provide good protection of plants from pathogen attack, excessive immune responses have negative impacts on plant growth and development. Thus, a good balance between positive and negative effects on the immune signaling network is important for plant fitness. However, little information is known about the molecular mechanisms that are involved in attenuation of PTI. Here, we describe a growth-promoting peptide hormone, phytosulfokine (PSK), as attenuating PTI signaling in Arabidopsis. This research was motivated by the observation that expression of the PSK Receptor 1 (PSKR1) gene was induced by MAMP treatment. Plants homozygous for pskr1 T-DNA insertions showed enhanced defense gene expression and seedling growth inhibition triggered by MAMPs. The pskr1 plants also showed enhanced PTI against the bacterial pathogen Pseudomonas syringae. These results indicate that the PSKR-mediated signaling attenuates immune responses. Tyrosyl protein sulfotransferase (TPST) is an enzyme required for production of the mature sulfated PSK. Like pskr1 mutants, a tpst T-DNA insertion line exhibited enhanced MAMP-triggered seedling growth inhibition, which was suppressed by exogenous application of PSK. Thus, PSK signaling mediated by PSKR1 attenuates PTI but stimulates growth.     

发酵床猪粪腐解菌群筛选

在浙江省安吉县采集了相邻的天然灌木林和板栗林土壤,分析土壤水溶性碳(WSOC)、微生物生物量碳(MBC)、易氧化碳(ROC)、水溶性有机氮(WSON)和微生物生物量氮(MBN),并利用核磁共振方法分析土壤总有机碳的波谱特征,研究天然灌木林改造成板栗林对土壤碳库和氮库的影响.结果表明： 天然灌木林改造成板栗林后,土壤中的碱解氮、有效磷和速效钾显著增加,而WSOC、MBC、ROC、WSON和MBN显著下降.天然灌木林和板栗林土壤有机碳以烷基碳和烷氧碳为主.天然灌木林改造成板栗林后,土壤有机碳中的烷氧碳和羰基碳比例显著下降,而烷基碳和芳香碳比例以及A/O-A值和芳香度均显著增加.天然灌木林改造成板栗林并长期集约经营后,土壤活性碳库和氮库含量均显著下降,而土壤碳库的稳定性显著增加.     

In vitro digestion enhances anti-adhesion effect of tempe and tofu against Escherichia coli

Aims: Enterotoxigenic Escherichia coli is one of the main pathogenic bacteria causing diarrhoea. Earlier studies have shown that tempe—a fungal fermented soya food—has anti‐adhesive activity against E. coli in vitro. Our aims were to challenge the anti‐adhesive activity under gastro‐intestinal conditions and to assess the activity of the nonfermented soya product tofu. Methods and results: In this study, we compared the anti‐adhesive activity of two major soya bean products, tempe and tofu, and their ileum efflux after transit through a dynamic gastrointestinal system simulating digestion in the human stomach and small intestine. The results showed that both tempe and tofu have an anti‐adhesive activity against E. coli in vitro. Tempe and tofu, after digestion through the stomach and small intestine, have even higher anti‐E. coli adhesive activity. Conclusions: In addition to the proven in‐vivo activity of tempe, this confirms the potential antidiarrhoeal effect of both the soya products tempe and tofu. Significance and Impact of the Study: As tofu has a much greater circle of consumers, this finding is relevant for the health of a large part of the world’s population.     

New Antagonistic Strains of Non‐Pathogenic Agrobacterium vitis to Control Grapevine Crown Gall

Graft unions of nursery stock of grapevine (Vitis vinifera L.) collected in Japan yielded non‐pathogenic strains of Agrobacterium. On the basis of classic diagnostic tests, a sequence analysis and a previously reported multiplex PCR method, the non‐pathogenic strains ARK‐1, ARK‐2 and ARK‐3 were identified as Agrobacterium vitis. Stems of grapevine seedlings were inoculated with both a cell suspension of seven mixed strains of A. vitis (Ti) as a pathogen and one of a new strain or A. vitis strain VAR03‐1, one of the biological control agents against crown gall previously reported, as competitors to assay the suppression of tumour formation caused by the pathogen. In a test with a 1:1 cell ratio of pathogen/nonpathogen, strains ARK‐1, ARK‐2 and ARK‐3 reduced the tumour incidence.. In particular, strain ARK‐1 was strongest at inhibiting tumour formation in this study. Strain ARK‐1 established populations on roots of grapevine tree rootstock and persisted on roots for a year. ARK‐1, ARK‐2 and ARK‐3 did not produce a halo of inhibition against A. vitis (Ti) strain on YMA medium. Moreover, strain ARK‐1 did not reduce tumour incidence on the stems of grapevine when ARK‐1 was dead or only culture filtrate was used. This result indicates the possibility that these new strains inhibit grapevine crown gall in planta by a different mechanism other than VAR03‐1. In particular, one of the new strains, named ARK‐1, was most effective in inhibiting tumour formation on grapevine and appears to be a promising new agent to control grapevine crown gall.     

微生物方法降解刺参养殖池塘中氨态氮的研究进展

随着刺参养殖业的迅速发展,刺参池塘养殖暴露出诸多问题,如水体氨态氮含量高、病害严重、单位产量下降等.传统药物弊端较多,微生物方法成为降解水体中氨态氮含量和预防病害发生的新的有效途径.综合阐述了刺参池塘养殖过程中氨态氮对刺参的危害和微生物降解氨态氮的利弊,并介绍了水体中氨态氮高效降解菌株的筛选以及现有微生态制剂存在的问题,对微生物方法降解刺参养殖池塘氨态氮的前景进行了展望.     

Detection of IgG and IgM in Sera from Canines with Blastomycosis using Eight Blastomyces dermatitidis Yeast Phase Lysate Antigens

The objective of this study was to compare the efficacy of eight Blastomyces dermatitidis yeast phase lysate antigens (T-58: dog, Tennessee; T-27: polar bear, Tennessee; ERC-2: dog, Wisconsin; B5894: human, Minnesota; SOIL: soil, Canada; B5896: human, Minnesota; 48089: human, Zaire; 48938: bat, India) in the detection of the immunoglobulins IgG and IgM in serum specimens from canines with blastomycosis. An indirect enzyme-linked immunosorbent assay (ELISA, peroxidase system) was used to analyze sera collected during four different intervals post-infection. The yeast lysate antigen 48938 was a reactive antigen for the detection of both IgG (mean absorbance value range: 1.198–2.934) and IgM (mean absorbance value range: 0.505–0.845). For the same sera, antigen T-27 was also effective in the detection of IgG (mean absorbance value range: 0.904–3.356) and antigen 48089 was useful for the detection of IgM (mean absorbance value range: 0.377–0.554). The yeast lysate antigen B5894 proved to be a poor antigen for the detection of both IgG and IgM (mean absorbance value ranges: 0.310–0.744 for IgG, 0.025–0.069 for IgM). Inherent variations in yeast lysate antigens such as these may be utilized to develop improved immunoassay procedures for the specific detection of IgG or IgM in cases of blastomycosis.     

The community composition of root-associated bacteria of the tomato plant

The objective of this study was to characterize the bacterial community composition in the bulk soil, rhizosphere soil and root tissue of the tomato plant (Lycopersicum esculentum Mill). 16S ribosomal DNA (rDNA) from the bacterial community was amplified using PCR, and sequence analysis of 16S rDNA clones was subsequently used for bacterial identification and phylogenetic classification. Phylogenetic analysis of clones (total of 68) from the bulk soil, rhizosphere and root tissues showed that about 50% of the bacteria belonged to the α-, β-, γ-, and δ-Proteobacteria or Cytophaga–Flavobacterium–Bacteroides (CFB) phyla, with only one high G+C clone identified. A number of diverse bacteria were identified within Proteobacteria, while 87% of the bacteria belonged to the genus Flavobacterium within the CFB phylum, which is a unique finding for tomato plants. Our results will be of interest to those wanting to identify bacteria that can promote plant growth or resistance to diseases.     

Satellite-marked waterfowl reveal migratory connection between H5N1 outbreak areas in China and Mongolia

The role of wild birds in the spread of highly pathogenic avian influenza H5N1 has been greatly debated and remains an unresolved question. However, analyses to determine involvement of wild birds have been hindered by the lack of basic information on their movements in central Asia. Thus, we initiated a programme to document migrations of waterfowl in Asian flyways to inform hypotheses of H5N1 transmission. As part of this work, we studied migration of waterfowl from Qinghai Lake, China, site of the 2005 H5N1 outbreak in wild birds. We examined the null hypothesis that no direct migratory connection existed between Qinghai Lake and H5N1 outbreak areas in central Mongolia, as suggested by some H5N1 phylogeny studies. We captured individuals in 2007 from two of the species that died in the Qinghai Lake outbreaks and marked them with GPS satellite transmitters: Bar-headed Geese Anser indicus ( n  =   14) and Ruddy Shelduck Tadorna ferruginea ( n  =   11). Three of 25 marked birds (one Goose and two Shelducks) migrated to breeding grounds near H5N1 outbreak areas in Mongolia. Our results describe a previously unknown migratory link between the two regions and offer new critical information on migratory movements in the region.     

In pursuit of virtual lead optimization: pruning ensembles of receptor structures for increased efficiency and accuracy during docking

Representing receptors as ensembles of protein conformations during docking is a powerful method to approximate protein flexibility and increase the accuracy of the resulting ranked list of compounds. Unfortunately, docking compounds against a large number of ensemble members can increase computational cost and time investment. In this article, we present an efficient method to evaluate and select the most contributive ensemble members prior to docking for targets with a conserved core of residues that bind a ligand moiety. We observed that ensemble members that preserve the geometry of the active site core are most likely to place ligands in the active site with a conserved orientation, generally rank ligands correctly and increase interactions with the receptor. A relative distance approach is used to quantify the preservation of the three-dimensional interatomic distances of the conserved ligand-binding atoms and prune large ensembles quickly. In this study, we investigate dihydrofolate reductase as an example of a protein with a conserved core; however, this method for accurately selecting relevant ensemble members a priori can be applied to any system with a conserved ligand-binding core, including HIV-1 protease, kinases, and acetylcholinesterase. Representing a drug target as a pruned ensemble during in silico screening should increase the accuracy and efficiency of high-throughput analyses of lead analogs.     

A role for plant microtubules in the formation of transmission-specific inclusion bodies of Cauliflower mosaic virus

Interactions between microtubules and viruses play important roles in viral infection. The best-characterized examples involve transport of animal viruses by microtubules to the nucleus or other intracellular destinations. In plant viruses, most work to date has focused on interaction between viral movement proteins and the cytoskeleton, which is thought to be involved in viral cell-to-cell spread. We show here, in Cauliflower mosaic virus (CaMV)-infected plant cells, that viral electron-lucent inclusion bodies (ELIBs), whose only known function is vector transmission, require intact microtubules for their efficient formation. The kinetics of the formation of CaMV-related inclusion bodies in transfected protoplasts showed that ELIBs represent newly emerging structures, appearing at late stages of the intracellular viral life cycle. Viral proteins P2 and P3 are first produced in multiple electron-dense inclusion bodies, and are later specifically exported to transiently co-localize with microtubules, before concentrating in a single, massive ELIB in each infected cell. Treatments with cytoskeleton-affecting drugs suggested that P2 and P3 might be actively transported on microtubules, by as yet unknown motors. In addition to providing information on the intracellular life cycle of CaMV, our results show that specific interactions between host cell and virus may be dedicated to a later role in vector transmission. More generally, they indicate a new unexpected function for plant cell microtubules in the virus life cycle, demonstrating that microtubules act not only on immediate intracellular or intra-host phenomena, but also on processes ultimately controlling inter-host transmission.