Optimization of covalent immobilization of pectinase on sodium alginate support

Pectinase was immobilized on a sodium alginate support using glutaraldehyde and retained 66% activity. The optimal pH for activity shifted from 3.0 to 3.5 after immobilization; however, the optimum temperature remained unchanged at 40°C. The immobilized enzyme also had a higher thermal stability and reusability than the free enzyme, and retained 80% of initial activity after 11 batch reactions.     

Diversity of tropical forest landscape types in Hainan Island, China

A novel landscape classification system was proposed in this study based on landscape ecological theory and the differentiation in climate, topography, soil, vegetation and land use mode. Five basic units (zone, tract, province, region and type) and two assistant units (sub and group) were used in this system. The tropical forest landscape in Hainan Island was regarded as a landscape province, belonging to global tropical forest landscape zone, Asiatic (oriental) tropical forest landscape tract and Chinese tropical forest landscape subtract. Based on the grade system of region, sub-region, type-group and type, this landscape province (Hainan Island) is divided into 6 landscape regions (east moist forest landscape, west semi-arid forest landscape, central-south mountainous forest landscape, tropical evergreen needle-leaved forest landscape, tropical bamboo landscape and tropical plantation landscape), 11 tropical forest landscape sub-regions represented by tropical lowland valley rain forest landscape, 26 tropical forest landscape-type groups represented by tropical lowland valley Dipterocarpaceae forest landscape, and 54 forest landscape types (FLT) represented by lowland valley Vatica mangachapoi forest. Generally, this classification system represents the landscape diversity of the tropical forest in Hainan Island. Further studies are needed to better understand the landscape diversity of Hainan Island.     

Oxytocin is expressed by both intrinsic sensory and secretomotor neurons in the enteric nervous system of guinea pig

Single- and double-immunostaining techniques were used systematically to study the distribution pattern and neurochemical density of oxytocin-immunoreactive (-ir) neurons in the digestive tract of the guinea pig. Oxytocin immunoreactivity was distributed widely in the guinea pig gastrointestinal tract; 3%, 13%, 17%, 15%, and 10% of ganglion neurons were immunoreactive for oxytocin in the myenteric plexuses of the gastric corpus, jejunum, ileum, proximal colon, and distal colon, respectively, and 36%, 40%, 52%, and 56% of ganglion neurons were immunoreactive for oxytocin in the submucosal plexuses of the jejunum, ileum, proximal colon, and distal colon, respectively. In the myenteric plexus, oxytocin was expressed exclusively in the intrinsic enteric afferent neurons, as identified by calbindin 28 K. In the submucosal plexuses, oxytocin was expressed in non-cholinergic secretomotor neurons, as identified by vasoactive intestinal polypeptide. Oxytocin-ir nerve fibers in the inner circular muscle layer possibly arose from the myenteric oxytocin-ir neurons, and oxytocin-ir nerve fibers in the mucosa possibly arose from both the myenteric and submucosal oxytocin-ir neurons. Thus, oxytocin in the digestive tract might be involved in gastrointestinal tract motility mainly via the regulation of the inner circular muscle and the balance of the absorption and secretion of water and electrolytes.     

Tumor necrosis factor-alpha enhances inhibitory effects of interleukin-1 beta on Leydig cell steroidogenesis

Human recombinant tumor necrosis factor-alpha (rTNF alpha) alone (up to 1000 units/ml) did not alter either basal or human chorionic gonadotropin (hCG)-induced testosterone formation in primary culture of rat Leydig cells. However, concomitant addition of rTNF alpha with human recombinant interleukin-1 beta (rIL-1 beta) enhanced the inhibitory effects of rIL-1 beta. The rIL-1 beta dose response curve was shifted to the left (IC50 changed from 1 ng/ml to 0.3 ng/ml). Even though rTNF alpha had no effect on testosterone formation, hCG-stimulated cyclic AMP formation was inhibited by rTNF alpha in a dose dependent manner. In the presence of both rTNF alpha and rIL-1 beta, hCG-induced cyclic AMP formation and binding of [125I]-hCG to Leydig cells were further inhibited. Testicular macrophages represent about 20% of the interstitial cells. TNF alpha and IL-1 may be produced locally by interstitial macrophages and have paracrine effects on Leydig cell function.     

Cloning and characterization of an AtNHX2-like Na+/H+ antiporter gene from Ammopiptanthus mongolicus (Leguminosae) and its ectopic expression enhanced drought and salt tolerance in Arabidopsis thaliana

An orthologue of the vacuolar Na⁺/H⁺ antiporter gene, AmNHX2, was isolated from a desert plant, Ammopiptanthus mongolicus, by RACE-PCR. It has a total length of 1,986 bp, with an open reading frame of 1,632 bp, encoding a predicted polypeptide of 543 amino acids. Sequence similarity and exon constituent analysis clearly suggested that AmNHX2 encoded an AtNHX2 (an antiporter from Arabidopsis) like vacuolar Na⁺/H⁺ antiporter. AmNHX2 could be strongly induced by both drought and salt stress. Heterologous expression in the yeast mutant nhx1 indicated that AmNHX2 was the orthologue of ScNHX1, and the complementation effect was almost the same as AtNHX1. Over-expressing AmNHX2 resulted in enhanced tolerances to both drought and salt stresses in transgenic Arabidopsis plants. The transgenic plants accumulated lower Na⁺ content in their leaves, showing healthier root system after salt stress, and retained more water during the drought stress. Our work suggested that AmNHX2 was a salt tolerance determinant in A. mongolicus, but might not be a contributor to the difference in salt sensitivity between A. thaliana and A. mongolicus.     

Transition of basic protein during spermatogenesis of <Emphasis Type="Italic">Fenneropenaeus chinensis</Emphasis> (Osbeck, 1765)

According to the ultrastructural characteristic observation of the developing male germ cells, spermatogenesis of the crustacean shrimp, Fenneropenaeus chinensis, is classified into spermatogonia, primary spermatocytes, secondary spermatocyte, four stages of spermatids, and mature sperm. The basic protein transition during its spermatogenesis is studied by transmission electron microscopy of ammoniacal silver reaction and immunoelectron microscopical distribution of acetylated histone H4. The results show that basic protein synthesized in cytoplasm of spermatogonia is transferred into the nucleus with deposition on new duplicated DNA. In the spermatocyte stage, some nuclear basic protein combined with RNP is transferred into the cytoplasm and is involved in forming the cytoplasmic vesicle clumps. In the early spermatid, most of the basic protein synthesized in the new spermatid cytoplasm is transferred into the nucleus, and the chromatin condensed gradually, and the rest is shifted into the pre-acrosomal vacuole. In the middle spermatid, the nuclear basic protein linked with DNA is acetylated and transferred into the proacrosomal vacuole and assembled into the acrosomal blastema. At the late spermatid, almost all of the basic protein in the nucleus has been removed into the acrosome. During the stage from late spermatid to mature sperm, some de novo basic proteins synthesized in the cytoplasm belt transfer into the nucleus without a membrane and almost all deposit in the periphery to form a supercoating. The remnant histone H4 accompanied by chromatin fibers is acetylated in the center of the nucleus, leading to relaxed DNA and activated genes making the nucleus non-condensed.     

Mapping and validation of a new QTL for adult-plant resistance to powdery mildew in Chinese elite bread wheat line Zhou8425B

Key message

Four QTLs for adult-plant resistance to powdery mildew were mapped in the Zhou8425B/Chinese Spring population, and a new QTL on chromosome 3B was validated in 103 wheat cultivars derived from Zhou8425B.

Abstract

Zhou8425B is an elite wheat (Triticum aestivum L.) line widely used as a parent in Chinese wheat breeding programs. Identification of genes for adult-plant resistance (APR) to powdery mildew in Zhou8425B is of high importance for continued controlling the disease. In the current study, the high-density Illumina iSelect 90K single-nucleotide polymorphism (SNP) array was used to map quantitative trait loci (QTL) for APR to powdery mildew in 244 recombinant inbred lines derived from the cross Zhou8425B/Chinese Spring. Inclusive composite interval mapping identified QTL on chromosomes 1B, 3B, 4B, and 7D, designated as QPm.caas-1BL.1, QPm.caas-3BS, QPm.caas-4BL.2, and QPm.caas-7DS, respectively. Resistance alleles at the QPm.caas-1BL.1, QPm.caas-3BS, and QPm.caas-4BL.2 loci were contributed by Zhou8425B, whereas that at QPm.caas-7DS was from Chinese Spring. QPm.caas-3BS, likely to be a new APR gene for powdery mildew resistance, was detected in all four environments. One SNP marker closely linked to QPm.caas-3BS was transferred into a semi-thermal asymmetric reverse PCR (STARP) marker and tested on 103 commercial wheat cultivars derived from Zhou8425B. Cultivars with the resistance allele at the QPm.caas-3BS locus had averaged maximum disease severity reduced by 5.3%. This STARP marker can be used for marker-assisted selection in improvement of the level of powdery mildew resistance in wheat breeding.

     

N-Terminal Myristoylated VP5 is Required for Penetrating Cell Membrane and Promoting Infectivity in Aquareoviruses

正Dear Editor,Myristoylation is a naturally occurring post-translational modification for targeting cytoplasmic proteins to intracellular membranes.Unlike enveloped animal viruses,which enter host cells by membrane fusion,nonenveloped animal viruses must disrupt the cell membrane to initiate infection.Some animal viruses and several nonenveloped viruses such     

Landscape correlates of forest plant invasions: A high‐resolution analysis across the eastern United States

Aim

Invasive species occurrence is often related to the anthropogenic context of a given area. Quantifying the effects of roads is of particular interest as roads are a major vector for invasion. Our objective was to further quantify the effects of roads on forest plant invasion through a macroscale, high‐resolution investigation to assist effective invasion control and mitigation.

Location

Eastern United States.

Methods

Using invasive plant data from 23,039 forest inventory plots in 13 ecological provinces, we employed logistic regression to relate the odds of invasion to distance from a road, with adjustments for broadscale differences attributable to ecological provinces, and local scale differences in productivity, forest fragmentation and land use.

Results

The overall proportion (P) of invaded plots was 0.58 (0.65 for plots within 50 m of a road), and the highest odds (P/1 ? P) of invasion were found in relatively more productive, fragmented forest in landscapes with more than 10% agriculture or developed land cover. Wald chi‐square statistics indicated the best predictor of the odds of invasion was ecological province, followed by land use, productivity, forest fragmentation and distance from a road. Depending on the province, the adjusted odds of invasion decreased by up to 23% (typically 4%–10%) per 100 m distance from a road. The adjusted probability of invasion approached zero in only three provinces, for the least productive, least fragmented forest that was at least 2,000 m from a road in landscapes with less than 10% agricultural or developed land cover.

Main conclusions

In the eastern United States, the existence of a nearby road is less important than the landscape context associated with the road. A purely road‐mediated effect has little practical meaning because anthropogenic activities and roads are pervasive and confounded.