Project description:This research identifies a novel protein required for paramutation at the maize purple plant1 locus. This 'required to maintain repression2' (RMR2) protein represents the founding member of a plant-specific clade of hypothetical proteins. We show that RMR2 is required for transcriptional repression at the Pl1-Rhoades haplotype, for accumulation of 24 nt RNA species, and for maintenance of a 5-methylcytosine pattern distinct from that maintained by RNA polymerase IV. Genetic tests indicate that RMR2 is not required for paramutation occurring at the red1 locus. These results distinguish the paramutation-type mechanisms operating at specific haplotypes. The RMR2 clade of proteins provides a new entry point for understanding the diversity of epigenomic control operating in higher plants.
Project description:Global food production is reliant on the application of finite phosphorus (P) fertilisers. Numerous negative consequences associated with intensive P fertilisation have resulted in a high demand to find alternative sustainable methods that will enhance crop P uptake. Bacteroidetes, primarily from the genus Flavobacterium, have recently been shown to be abundant members of the plant microbiome, but their general ecological role and potential to mobilise P in the rhizosphere remains very poorly characterised. Here, we sought to determine the P mobilisation potential of Flavobacterium strains isolated from the rhizosphere of oilseed rape (Brassica napus L.). In contrast to other abundant rhizosphere bacteria, such as Pseudomonas, all Flavobacterium strains exhibited constitutive phosphatase activity independent of external phosphate (Pi) concentrations. Interestingly, a combination of exoproteomic analysis and molecular microbiology techniques revealed that Flavobacterium have a complex and largely unique repertoire of proteins to mobilise and acquire Pi. This includes the expression of novel, as yet unidentified, phosphatases, and numerous proteins of unknown function. We also discovered that Flavobacterium expresses certain SusCD-like transporters, whose role is typically associated with specialised carbon acquisition, in response to Pi-starvation. Furthermore, the genes encoding these unusual Pi-responsive proteins were enriched in plant-associated Flavobacterium strains suggesting that this machinery represents niche-adaptive strategies for overcoming P scarcity in this genus. We propose that abundant rhizosphere-dwelling Flavobacterium spp. have evolved unique mechanisms for coping with Pi-stress which may provide novel solutions for future sustainable agricultural practices.
Project description:Clinical Flavobacterium columnare ATCC 49512 was grown on Flavobacterium columnare growth medium (FCGM). Bacteria from four colonies at mid-exponential phase were harvested, total proteins were isolated, and identified using 2-DE MALDI TOF/TOF MS and 2-D LC ESI MS/MS analyses. The MS/MS spectra for all peptides were analyzed using sequest algorithm
Project description:Acanthamoeba-infecting Mimiviridae belong to three clades: Mimiviruses (A), Moumouviruses (B) and Megaviruses (C). The uniquely complex mobilome of these giant viruses includes virophages and linear 7 kb-DNA molecules called “transpovirons”. We recently isolated a new virophage (Zamilon vitis) and two new transpovirons (maBtv and mvCtv) respectively associated to B-clade and C-clade Mimiviridae. We used the capacity of the Zamilon virophage to replicate both on B-clade and C-clade host viruses to investigate the three partite interaction network governing the propagation of transpovirons. We notably performed proteomic comparisons of host viruses and virophage particles carrying or cleared of transpovirons in search of proteins involved in this adaptation process. These experiments revealed that transpoviron-encoded proteins are synthetized during the combined Mimiviridae/virophage/transpoviron replication process and are specifically incorporated into the virophage and Mimiviridae virions together with the cognate transpoviron DNA. This is a unique example of intricate commensalism in the viral world, where the Zamilon virophage and the transpoviron depend on their host giant virus to replicate, and the transpoviron depends on the virophage to propagate from one host virus to another.
Project description:Columnaris disease is a prevalent disease in freshwater environments worldwide caused by the ubiquitous aquatic bacterium Flavobacterium species. Adhesion to the external mucosal surfaces of fishes is the initial stage of infection, and the gills specifically have been identified as both a primary target and release site for this pathogen. Previous research has indicated that a predominant US aquaculture product, the hybrid striped bass (Morone chrysops x M. saxatilis), is more susceptible to infection with Flavobacterium columnare (covae) than the maternal white bass (M. chrysops) parental species. Therefore, to further elucidate the differences between these fish we conducted a transcriptomic profiling study examining the differences of gene expression in gill mucosal tissue over time after exposure to F. covae isolate LSU-066-04. Combined with previous work, these data provide a greater understanding of host immune response to a common pathogen in moronids.
Project description:We compare the transcriptome of gnotobiotic Ae. aegypti generated by contaminating axenic (bacteria-free) larvae with bacterial isolates found in natural mosquito breeding sites. We focused on four bacterial isolates (Lysobacter, Flavobacterium, Paenibacillus and Enterobacteriaceae) and found that different gnotobiotic treatments resulted in massive transcriptomic changes throughout the mosquito development.
Project description:Purpose:Salinity is an important environmental factor that affects the physiological activities of fish. Flavobacterium cloumnare is a major aquaculture pathogen infecting various saltwater and freshwater fish. The goals of this study are investigating the mechanism of the immune responses to Flavobacterium cloumnare in grass carp under saline-alkali stress. Methods: Grass carp individuals, averaging 12 cm in body length, were obtained from Duofu fish farm (Wuhan, China) and cultured at recirculating aquaculture system for 2 weeks before the experiment began. For the challenge, all grass carp were randomly divided into three groups, and then cultured at saline-alkali water with the concentration of 0, 3‰ and 6‰. After 30 days, Groups of grass carp were were infected with 2 × 105 CFU/mL Flavobacterium cloumnare G4 strains for 3 h .Gills from each group at 24 hpi, 3dpi and 6dpi were collected. Total RNA of all samples was isolated using TRIzol® Reagent (Invitrogen) according to the manufacturer's introduction. gill per group at 24 hpi and 48 hpi were rinsedRNA integrity was assessed using an Agilent 2100 bioanalyzer (Agilent, USA). Samples with RNA integrity numbers (RINs) ≥ 7.5 were subjected to cDNA library construction using TruseqTM RNA sample prep Kit (Illumina). Results:A total of 27 were processed for transcriptome sequencing, generating 177.79Gb Clean Data. At least 5.73Gb clean data were generated for each sample with minimum 93.70% of clean data achieved quality score of Q30. Clean reads of each sample were mapped to specified reference genome. Mapping ratio ranged from 88.11% to 92.33%. The expression of genes was quantified and differentially expressed genes were identified based on their expression.Criteria for differentially expressed genes was set as Fold Change(FC)≥1.5 and Pvalue<0.05. Fold change(FC) refers to the ratio of gene expression in two samples. These DEGs were further processed for functional annotation and enrichment analysis. Conclusions: Our study represents the immune response of zebrafish against Flavobacterium cloumnare infection in saline-alkali stress conditions, and reveal the discrepant expression pattern of NOD-like pattern recognition receptors in the gills.