Effect of long-term fertilization on bacterial communities in wheat endosphere

Fertilization has been shown to exert a significant influence on soil microorganisms and directly and indirectly influences plant growth and survival in agroecosystems. However, it is unknown whether fertilization affects endophytic microbial communities, which are ubiquitous and intimately associated with plant growth and health. Herein, we investigated endophytic bacterial communities in wheat leaves and roots under different long-term fertilization regimes, including NPK chemical fertilizer and NPK chemical fertilizer combined with wheat straw, pig manure, or cow manure. Endophytic bacterial community composition considerably differed in leaves and roots. Although different fertilization treatments did not affect the endophytic bacterial species richness or phylogenetic diversity in either leaves or roots, the community composition was significantly altered, particularly in roots. The endophytic bacterial co-occurrence network in leaves was more complex and stable than that in roots. Furthermore, many of the keystone species that were identified by their topological positions in the co-occurrence networks of leaves and roots were involved in plant growth and fitness. The total relative abundance of keystone species was the highest in the NPK plus cow manure treatment in both leaves and roots. Overall, our results suggest that different fertilization regimes can strongly affect endophytic bacterial communities, and the combination of NPK fertilizer and cow manure promoted the relative abundance of the key endophytic bacterial microbiota in both leaves and roots, which might be beneficial for plants in agroecosystems.     

Interactional effects of β-glucan, starch, and protein in heated oat slurries on viscosity and in vitro bile acid binding

Three major oat components, β-glucan, starch, and protein, and their interactions were evaluated for the impact on viscosity of heated oat slurries and in vitro bile acid binding. Oat flour from the experimental oat line "N979" (7.45% β-glucan) was mixed with water and heated to make oat slurry. Heated oat slurries were treated with α-amylase, lichenase, and/or proteinase to remove starch, β-glucan, and/or protein. Oat slurries treated with lichenase or lichenase combined with α-amylase and/or proteinase reduced the molecular weight of β-glucan. Heat and enzymatic treatment of oat slurries reduced the peak and final viscosities compared with the control. The control bound the least amount of bile acids (p < 0.05); heating of oat flour improved the binding. Heated oat slurries treated with lichenase or lichenase combined with α-amylase and/or proteinase bound the least amount of bile acid, indicating the contribution of β-glucan to binding. Oat slurries treated with proteinase or proteinase and α-amylase together improved the bile acid binding, indicating the possible contribution of protein to binding. These results illustrate that β-glucan was the major contributor to viscosity and in vitro bile acid binding in heated oat slurries; however, interactions with other components, such as protein and starch, indicate the importance of evaluating oat components as whole system.     

Nematode communities of grazed and ungrazed semi-natural steppe grasslands in Eastern Austria

Soil nematode communities were investigated at eight semi-natural steppe grasslands in the National Park Seewinkel, eastern Austria. Four sites were moderately grazed by horses, cattle and donkeys, four were ungrazed. Nematodes were sampled on four occasions from mineral soil, and their total abundance, diversity of genera, trophic structure and functional guilds were determined. Altogether 58 nematode genera inhabited the grasslands, with Acrobeloides, Anaplectus, Heterocephalobus, Prismatolaimus, Aphelenchoides, Aphelenchus, Tylenchus and Pratylenchus dominating. Mean total abundance at sites was 185–590 individuals per 100 g soil. Diversity indices did not separate communities well, but cluster analysis showed distinct site effects on nematode generic structure. Within feeding groups the relative proportion of bacterial-feeding nematodes was the highest, followed by the fungal- and plant-feeding group. Omnivores and predators occurred in low abundance. The maturity indices and plant parasite indices were characteristic for temperate grasslands, but the abundance of early colonizers (c-p 1 nematodes) was low. A high density of fungal-feeding c-p 2 families (Aphelenchoidae, Aphelenchoididae) resulted in remarkably high channel index values, suggesting that decomposition pathways are driven by fungi. Nematode community indices of all sites pointed towards a structured, non-enriched soil food web. At most sites, grazing showed little or no effect on nematode community parameters, but total abundance was higher at ungrazed areas. Significant differences in the percentage of omnivorous nematodes, the sum of the maturity index, the number of genera and Simpson's index of diversity were found at one long-term grazed pasture, and this site was also separated by multi-dimensional scaling (MDS).     

Effect of soil properties on the degradation of isoxaflutole and the sorption-desorption of isoxaflutole and its diketonitrile degradate

The transformation of isoxaflutole (ISOX) to its herbicidally active diketonitrile degradate (DKN) was significantly enhanced in the presence of soil and occurred more rapidly in systems containing soil with a greater soil pH. Sorption-desorption of ISOX and DKN in five soils collected within a field revealed both ISOX and DKN were more readily sorbed to soils with greater organic matter, clay content, and lower soil pH. Sorption of ISOX residues occurred within 2 h, and extracts contained similar concentrations of ISOX and DKN at 24 h, suggesting the 24-h sorption coefficients for ISOX-treated systems were actually for mixed ISOX residues. Freundlich sorption coefficients were 3 and 4 times greater for ISOX than for DKN. On the basis of the Freundlich organic carbon sorption constants, ISOX and DKN can be categorized in the very high and high mobility classes, suggesting their potential to leach in the soils needs to be evaluated.     

QUANTITATIVE HEPATOBILIARY SCINTIGRAPHY IN NORMAL CATS AND IN CATS WITH EXPERIMENTAL CHOLANGIOHEPATITIS

Quantitative hepatobiliary scintigraphy using 99mTc-mebrofenin was performed on eight normal cats and on the same cats after induction of experimental cholangiohepatitis by infection with the liver fluke Platynosomum concinnum. Hepatobiliary scintigraphy was performed 3 times at 10 weeks, 4 months and 6 months after infection. In addition, routine biochemical tests, hepatic ultrasound and ultrasound guided hepatic biopsy samples were obtained at the same time points, and the results compared with hepatobiliary scintigraphy. The normal hepatic extraction fraction was determined to be 85%, and the normal hepatic excretion half time (T 1/2) was 14 minutes. There was no significant change in scintigraphic parameters compared to pre-infection values at any time following infection with the liver fluke. No correlation between scintigraphic parameters and histologic scores was found; however, significant correlation was identified between parasite burden and histologic scores 6 months following infection. Despite the presence of severe multifocal histologic abnormalities, minimal clinical, biochemical and scintigraphic derangements were identified using this model of cholangiohepatitis. Based on this study, hepatobiliary scintigraphy appears to be an insensitive test for structural hepatobiliary abnormalities. The role of hepatobiliary scintigraphy in functional hepatobiliary abnormalities of the feline liver has not been determined.     

Systemic coccidioidomycosis in a llama cria native to Missouri

A 3-mo-old male llama was examined because of a 4-wk history of lethargy and ill thrift. Clinical examination revealed subcutaneous masses in the left prescapular and right inguinal regions, mild ataxia, a slight head tilt to the right, and right ear droop. The cria died before clinical workup was complete. At autopsy, there was generalized lymphadenomegaly, a hepatic nodule, a midbrain mass causing rostral compression of the cerebellum, and internal hydrocephalus. Microscopic findings included pyogranulomatous lymphadenitis, meningoencephalitis, hepatitis, and bronchopneumonia. Intralesional fungal spherules, most consistent with Coccidioides spp., were identified in the lymph nodes, lung, and brain. Fungal culture, single-nucleotide variation genotyping real-time PCR, and DNA sequencing confirmed Coccidioides posadasii. The dam of the cria was native to Arizona and had been moved to Missouri ~2.5 y previously. Agar gel immunodiffusion assay of the herd revealed that only the dam was positive for Coccidioides spp.; 6 herdmates were negative. Computed tomography of the dam revealed multiple nodules within the lungs and liver, which were presumed to be an active coccidioidomycosis infection. This case of systemic coccidioidomycosis in a llama native to Missouri was presumably acquired by vertical transmission from the dam.     

Suspended animation in C. elegans requires the spindle checkpoint

In response to environmental signals such as anoxia, many organisms enter a state of suspended animation, an extreme form of quiescence in which microscopically visible movement ceases. We have identified a gene, san-1, that is required for suspended animation in Caenorhabditis elegans embryos. We show that san-1 functions as a spindle checkpoint component in C. elegans. During anoxia-induced suspended animation, embryos lacking functional SAN-1 or a second spindle checkpoint component, MDF-2, failed to arrest the cell cycle, exhibited chromosome missegregation, and showed reduced viability. These data provide a model for how a dynamic biological process is arrested in suspended animation.     

Organization of intracellular reactions with rationally designed RNA assemblies

The rules of nucleic acid base-pairing have been used to construct nanoscale architectures and organize biomolecules, but little has been done to apply this technology in vivo. We designed and assembled multidimensional RNA structures and used them as scaffolds for the spatial organization of bacterial metabolism. Engineered RNA modules were assembled into discrete, one-dimensional, and two-dimensional scaffolds with distinct protein-docking sites and used to control the spatial organization of a hydrogen-producing pathway. We increased hydrogen output as a function of scaffold architecture. Rationally designed RNA assemblies can thus be used to construct functional architectures in vivo.