Tree species-specific effects on soil microbial residues in an upper Michigan old-growth forest system

Microbial contribution to carbon and nitrogen cycling in forestsoils is important, and may depend on tree species. The amountof amino sugars and their ratios can serve as reliable indicatorsfor bacterial and fungal contribution. We compare forest floormicrobial residues (amino sugars) beneath three canopy-treespecies (Sugar Maple (SM), Acer saccharum Marsh; Basswood (BA),Tilia americana L.; Eastern Hemlock, Tsuga canadensis L.) replicatedin five plots in an upper Michigan old-growth forest. We hypothesizedthat because individual tree species develop a unique microbialcommunity over time, they will accumulate microbial residuesto different degrees. In this study at three tree species sites,the absolute amount of fungal residue (glucosamine (GluN)) wasrelatively constant, while absolute quantities of bacterialresidues (galactosamine (GalN) and muramic acid (MurA)) wereleast in the Hemlock site. Amino sugar ratios revealed thatmicrobial residues were compositionally distinct in the threesites. The lower ratios of GluN to GalN and GluN to MurA inBA and SM sites relative to Hemlock site indicate the lowernet accumulations of GalN and MurA in Hemlock site. In termsof microbial contribution to carbon and nitrogen cycle in forestsoils, we suggest that caution may be needed when using aminosugars as a tool, especially for nitrogen pool assessment, asthe amino sugars are diluted by plant-derived litter. This studyprovides information on the microbial residues in undisturbedforest soils which may assist interpretation of data derivedfrom managed or damaged forests in the future.     

Anti-tumor effect of adenoviral vector-mediated p53 gene transfer on the growth of canine osteosarcoma xenografts in nude mice

We evaluated the anti-tumor effect of adenoviral vector-mediated p53 gene therapy on the growth of canine osteosarcoma xenografts formed in nude mice. Nude mice were subcutaneously transplanted with cells of 2 P53 mutant canine osteosarcoma cell lines, POS and CHOS. The osteosarcoma xenografts were injected with either an adenoviral vector that expresses canine wild-type P53 (AxCA-cp53) or LacZ (AxCA-LacZ). Tumor growth was significantly inhibited in the xenografts injected with AxCA-cp53 in comparison to those injected with AxCA-LacZ or PBS during the observation period of 27 days. An increase of the amount of p21(WAF1/CDKN1A) mRNA, and the number of apoptotic cells was shown in the tumors injected with AxCA-cp53 in comparison to those injected with AxCA-LacZ or PBS. The present study revealed that the adenoviral vector-mediated p53 gene transfer had an anti-tumor effect in canine osteosarcoma xenografts formed in nude mice.     

Asymmetrical allocation of NMDA receptor epsilon2 subunits in hippocampal circuitry

Despite its implications for higher order functions of the brain, little is currently known about the molecular basis of left-right asymmetry of the brain. Here we report that synaptic distribution of N-methyl-D-aspartate (NMDA) receptor GluRepsilon2 (NR2B) subunits in the adult mouse hippocampus is asymmetrical between the left and right and between the apical and basal dendrites of single neurons. These asymmetrical allocations of epsilon2 subunits differentiate the properties of NMDA receptors and synaptic plasticity between the left and right hippocampus. These results provide a molecular basis for the structural and functional asymmetry of the mature brain.     

Estimation of cadmium load on Japanese farmland associated with the application of chemical fertilizers and livestock excreta

It is very important to use ¹⁵N labeled nitrogen gas (¹⁵N₂) in studies on biological nitrogen fixation. For example, ¹⁵N₂ is necessary for direct measurement of the amount of fixed nitrogen, and is useful for studies on the assimilation and transport of fixed nitrogen. However, ¹⁵N₂ is sometimes troublesome to deal with for the following reasons. Decline in the ¹⁵N content of ¹⁵N₂ gas may occur as a result of contamination with atmospheric N₂ during the storage period or application to nitrogen fixing organisms. Also, the ¹⁵N₂ gas provided commercially in a glass bottle or gas cylinder is technically and economically not convenient for experiments employing small amounts of ¹⁵N₂. Moreover, purification of ¹⁵N₂ gas is necessary for biological research, since contamination with the oxidized forms of nitrogen represses biological nitrogen fixation to a certain extent. A simple method for the preparation, purification and storage of ¹⁵N₂ gas for biological nitrogen fixation studies, was therefore devised.     

Regional Variability of the Effects of Land Use Systems on Soil Properties

In order to explore the regional variability of the effects of land use systems on soil properties, Shouyang County in Shanxi Province and Danling County in Sichuan Province of China were selected as the study areas. Field soil samples of the four land use systems （natural forest, forest plantation, shrubland, and cropland） were collected, respectively, from the two areas. The general statistical tools were used to analyze soil data. The results showed that the influence of land use systems on soil properties was significant. In general, soils in slightly human-disturbed land use systems presented a higher fertility level than those in strongly human-disturbed land use systems in both areas. Furthermore, the impacts of the same land use systems on soil properties showed a distinct regional variability, and even in the same land use system, different farming systems and site management measures （such as irrigation, fertilization, and pesticides） could also lead to the regional heterogeneity in soil properties. The regional variability of land use effects on soil properties reveals the regional variability of the effects of human activities on environmental changes, and could explain the complex relationship between humans and the natural environment in certain ways.     

Membranous Glomerulonephropathy in a Hatano Low-avoidance Rat

Membranous glomerulonephropathy can be experimentally induced in rats, but spontaneous cases have been rarely reported. In this report, we present a typical case of spontaneous membranous glomerulonephropathy in a rat. A male Hatano low-avoidance (LAA) strain rat had a tumor mass on the right auricle, and was sacrificed at 41 weeks of age. Urinary screening by reagent strips revealed intense proteinuria. Histological tests revealed frequent presence of irregularly sized eosinophilic hyaline materials on the capillary wall and in the mesangium of renal glomeruli. Immunofluorescence revealed granular deposits of IgG, IgM, and C3 in the glomeruli. Subepithelial dense deposits were observed by electron microscopy accompanied by podocyte foot process effacement and occasional irregular thickening of the glomerular basement membrane. The rat also developed chronic lymphocytic pancreatitis, and the tumor mass on the right auricle was diagnosed as a fibrosarcoma. Screening tests for antibodies against major infectious agents and antinuclear antibody were negative. Western blot and indirect immunofluorescence analyses suggested the presence of an autoantibody against the pancreatic component. The glomerulopathy was considered an early stage of membranous glomerulonephropathy.     

Analyzing soil-available phosphorus by the Mehlich-3 extraction method to recommend a phosphorus fertilizer application rate for maize production in northern Mozambique

ABSTRACT

The available phosphorus (P) in soil is a major limiting factor for maize productivity in the Nacala corridor, Mozambique. In this study, soils were collected from three representative sites, Ribaue, Nampula, and Nacala, in the area, and each was used for maize pot experiment with five P fertilizer levels. The soil-available P content was determined by the Mehlich-3 method at 30 days after P fertilization. The shoot biomass and P concentration at the tasseling stage increased as the P fertilizer level increased and were significantly expressed as a function of soil-available P. Based on the function, the available P that attains 90% of the maximum shoot biomass was estimated as 79 mg P₂O₅ kg^?1. Consequently, the results in this study suggest a recommendation of 32–74 kg P₂O₅ ha^?1 fertilizer for maize production in the Nacala corridor although a field evaluation and economical evaluation are necessary.     

Root response to aerobic conditions in rice,estimated by Comair root length scanner and scanner-based image analysis

Precise evaluation of root system architecture is important for understanding how rice plants are adapted to non-puddled and non-flooded conditions in aerobic culture. The objective of this study was to compare estimates of root length by the Comair root length scanner and a flat bed scanner and image analysis software in rice grown in aerobic, near-saturated and flooded fields. Fine roots (diameter < 0.2 mm) accounted for >80% of root length in all hydrological conditions. The Comair root length scanner detected fewer fine roots than the software; root length estimated by the Comair scanner was between that of roots wider than 0.1 mm and roots wider than 0.2 mm estimated by image analysis software. Importantly, total root length under aerobic and near-saturated conditions was 10–30% of that under flooding by image analysis software, but not by the Comair scanner. Digital image analysis detected genotypic differences in fine root development in the subsurface layer in aerobic culture that the Comair root length scanner would have missed. Although root length measurement by image analysis software is still under development, this new tool will facilitate the phenotyping of root system architecture and shed light on the roles of fine roots in water-saving rice cultivation.     

Characterizing Spatial Patterns of Phenology in Cropland of China Based on Remotely Sensed Data

This study used time-series of global inventory modeling and mapping studies （GIMMS） normalized difference vegetation index （NDVI） datasets at a spatial resolution of 8 km and 15-d interval to investigate the spatial patterns of cropland phenology in China. A smoothing algorithm based on an asymmetric Gaussian function was first performed on NDVI dataset to minimize the effects of anomalous values caused by atmospheric haze and cloud contamination. Subsequent processing for identifying cropping systems and extracting phenological parameters, the starting date of growing season （SGS） and the ending date of growing season （EGS） was based on the smoothed NVDI time-series data. The results showed that the cropping systems in China became complex as moving from north to south of China. Under these cropping systems, the SGS and EGS for the first growing season varied largely over space, and those regions with multiple cropping systems generally presented a significant advanced SGS and EGS than the regions with single cropping patterns. On the contrary, the phenological events of the second growing season including both the SGS and EGS showed little difference between regions. The spatial patterns of cropping systems and phenology in Chinese cropland were highly related to the geophysical environmental factors. Several anthropogenic factors, such as crop variety, cultivation levels, irrigation, and fertilizers, could profoundly influence crop phenological status. How to discriminate the impacts of biophysical forces and anthropogenic drivers on phenological events of cultivation remains a great challenge for further studies.