Optimization of fermentation condition for antibiotic production by Xenorhabdus nematophila with response surface methodology.

Aims: To evaluate the influence of environmental parameters on the production of antibiotics (xenocoumacins and nematophin) by Xenorhabdus nematophila and enhance the antibiotic activity.

Methods And Results: Response surface methodology (RSM) was employed to study the effects of five parameters (the initial pH, medium volume in flask, rotary speed, temperature and inoculation volume) on the production of antibiotics in flask cultures by X. nematophila YL001.

[Technique of macroporous resin for tartary buckwheat total flavonoids].

Objective: To investigatre appropriate macroporous resins and the optimal technological parameters of the purification process of tartary buckwheat total flavonoids.

Method: Static and dynamic adsorption-desorption methods were adopted, and evaluated for separating efficiency by macroporous resins absorption rates, desorption rates.

Result: The DM -2 macroporous resin had the best separating efficiency.

Enhanced antibiotic activity of Xenorhabdus nematophila by medium optimization.

Nutrition had highly influence on the antibiotic production by Xenorhabdus nematophila YL001. Glucose and peptone were identified as the best carbon and nitrogen sources that significantly affected antibiotic production using one-factor-at-a-time approach. Response surface methodology was applied to optimize the medium constituents (Glucose, peptone and minerals) for antibiotic production by X.

[Effects of rainfall intensity on rainfall infiltration and redistribution in soil on Loess slope land].

With simulation test, this paper studied the patterns of rainfall infiltration and redistribution in soil on typical Loess slope land, and analyzed the quantitative relations between the infiltration and redistribution and the movement of soil water and mass, with rainfall intensity as the main affecting factor. The results showed that rainfall intensity had significant effects on the rainfall infiltration and water redistribution in soil, and the microcosmic movement of soil water. The larger the rainfall intensity, the deeper the wetting front of rainfall infiltration and redistribution was, and the wetting front of soil water redistribution had a slower increase velocity than that of rainfall infiltration.

Effects of elevated pO3 on carbon cycle between above and belowground organs of trees.

Translocation of carbohydrate from leaves to roots via phloem and reallocation from roots to leaves via xylem regulate the allocation of carbon (C) between above and belowground organs of trees. To quantitatively analyze effects of elevated ozone concentrations pO3 on the internal cycle of C, juvenile beech and spruce were grown in phytotrons and exposed to ambient and elevated pO3 (i.e.

[Genetic diversity of Melampsora larici-populina].

By using ITS - nrDNA-RELP, ITS sequencing, and RAPD molecular marker, this paper studied the genetic diversity of 11 isolates in 5 races of Melampsora larici-populina from different regions. The results indicated that the genetic differentiation of M. larici-populina was correlated to its geographical distribution, which could be grouped into northern and western geographic populations, and the latter could be grouped into high-mountain forest ecologic type (HMF) and western plain ecologic type (WPL).

[Influence of measurement position on calculating pear tree stem sap flow].

By the method of heat pulse, this paper studied the influence of different measurement positions on calculating the stem sap flow velocity and quantity of pear trees. The results showed that at definite depths, the directional variation of the volume fraction of water and wood was lower than the seasonal change of wood physical parameters. The directional and seasonal variation of the volumetric water and wood was 0.

[Rhizodeposition and its role in carbon cycling in plant-soil system].

Rhizodeposition is an important interface process of the exchange between plant and soil, and plays an important role in soil carbon turnover. The rhizodeposition of carbon is also the bridge linking plant, soil" and microorganisms. This paper reviewed the researches on the rhizodeposition in carbon balance and carbon cycling, expounded the mechanisms of carbon rhizodeposition, and discussed the problems in related experiments, the differences of rhizodeposition with plant species, cultivars and growth stages, the relationships between rhizodeposition and soil respiration, and the significance of rhizodeposition in the carbon cycling in plant-soil system.

[Effects of soil moisture on the compensation effect of winter wheat with its partial roots cut off at returning green stage].

The study with pot experiment showed that after cutting partial roots at returning green stage, the growth of winter wheat was restrained at early growth stage, and the leaf area was decreased significantly from returning green to jointing stage but restored to the level of the control at flowering stage. Under high soil moisture condition, root cutting increased the values of chlorophyll fluorescence parameters ETR, phiPS II , qp and qn, at jointing stage significantly. The accumulated dry matter weight per stem after anthesis was significantly higher in root-cut wheat (0.

[Diurnal dynamics of photosynthetic and transpiration rates of alfalfa under dry farming and their relationships with environmental factors].

In this paper, the diurnal dynamics of photosynthetic rate (Pn) and transpiration rate ( Tr) of four years planted alfalfa under dry farming, as well as those of photosynthetic active radiation (PAR) , CO2 concentration in field ( Ca ) , relative humidity (RH) and air temperature ( Ta) were measured, and the relationships between the diurnal dynamics of Pn, Tr and climatic factors were analyzed by correlation coefficient, path coefficient, and decision coefficient analyses. The results showed that T. had the greatest effect on the diurnal dynamics of Pn , while RH, PAR and C, affected P,, mainly through their acting on Ta PAR had the greatest effect on the diurnal changes of Tr, and RH, Ta and Ca affected Tr indirectly by acting on PAR.

Analysis of the genetic diversity and the phylogenetic evolution of Chinese sheep based on Cyt b gene sequences.

The complete sequences of Cyt b gene from 20 individuals belonging to eight Chinese indigenous sheep breeds and one foreign breed were studied. The results showed that the hapolotype diversity of Chinese sheep breeds was 97.1%.

Immortalization of bovine germ line stem cells by c-myc and hTERT.

The limited life span of bovine germ line stem cells in vitro is one of the obstacles to spermatogenesis analysis, genetic manipulation and generating transgenic animal. The aim of this study is to establish immortalized bovine germ line stem cells by c-myc or hTERT. We constructed pEMY and pETE expression vectors and transfected germ line cells from 5-month-old bovine.

[Rhythmic beating cardiomyocytes derived from human embryonic germ (EG) cells in vitro].

Unlabelled: Embryonic germ (EG) cells are pluripotent cells derived from primordial germ cells (PGCs) of gonads, gonadal ridges and mesenteries, analogies of fetuses,with the ability to undergo both highly self-renewal and multiple differentiation. These cells in vitro can differentiate into derivatives of all three embryonic germ layers when transferred to an in vitro environment and have the ability to form any fully differentiated cells of the body. The aim of this study is to investigate the potentiality of human EG cells differentiation into cardiomyocytes.

[Effects of CaCOC addition under Zn supply on wheat seedlings growth and Zn uptake].

High concentration calcium carbonate in calcareous soils usually limits plant Zn uptake. In this paper, a solution culture experiment was conducted to study the effects of CaCO3 addition with or no Zn supply on the growth and Zn uptake of three genotypes winter wheat seedlings. The results showed that Zn supply or CaCO3 addition had no significant effects on seedlings biomass and root/canopy ratio, and there was no significant difference among the three genotypes.

[Cold hardiness of Pinus ponderosa, P. banksian and P. tabulaeformis].

By the method of artificial freezing, this paper made a comparative study on the cold hardiness of Pinus ponderosa, P. banksiana and P. tabulaeformis, with their inherent mechanisms approached.

[Predation of Orius minutus on Odontothrips loti].

In this paper, a laboratory study was made on the predation of Orius minutus on the 3rd to approximately 4th instar nymphs of Odontothrips loti, and the intraspecific interference within O. minutus. The results showed that the functional responses of adult O.

[UV-induced DNA mutation of peach aphid].

By using PCR technique and microsatellite marks, this paper studied the DNA polymorphism of peach aphid (Myzus persicae) under UV-radiation. The fragments of three primers were amplified, and the gene diversity and the rate of loci polymorphisms of their genomic DNA, which could reflect the damage degree of DNA after UV-radiation, were measured. The results revealed that after treated with different radiation intensity (15, 30, 45 W) and duration (2, 4, 6 h) , the UV-induced DNA mutations were genetic and could be delivered to F2 generation.

[The degree of inbreeding in 10 Chinese indigenous pig breeds].

The population inbreeding coefficients of 10 indigenous pig breeds were estimated by microsatellite markers. Results showed that: the inbreeding coefficient of Guizhou miniature pig was the highest (0.1992), and that of Hanzhong black pig the lowest (0.

[Physiological-ecological effects of Populus davidiana--Quercus liaotungensis mixed forest in Ziwuling forest area].

This paper studied the soil physical- properties under Populus davidiana, Quercus liaotungensis, and Populus davidiana--Quercus liaotungensis mixed forest in the Ziwuling forest area of Loess Plateau, and the leaf photosysthetic characteristics of these three types of forests. The results showed that soil moisture content in 0 - 300 cm layer was the highest under P. davidiana forest, and obviously increased below 200 cm in depth under P.

Metschnikowia sinensis sp. nov., Metschnikowia zizyphicola sp. nov. and Metschnikowia shanxiensis sp. nov., novel yeast species from jujube fruit.

Eight yeast strains were isolated from jujube fruit surfaces collected in Shanxi and Shandong Provinces, China. All eight strains produced needle-shaped ascospores under suitable conditions. Three separate groups, representing three novel species in the genus Metschnikowia, were recognized by sequence comparisons of the 26S rDNA D1/D2 domain and internal transcribed spacer (ITS) region.

[Soil carbon cycle of Pinus tabulaeformis forest in Huoditang forest region of Qinling Mountains].

With soil carbon cycle compartment model,this paper studied the carbon storage and flux of each carbon compartment of soil under Pinus tabulaeformis, a main forest type in the Huoditang forest region of Qinling Mountain. The results showed that the storage of soil organic carbon was 146.071 t x hm(-2), with 130.

[Spatial distribution pattern of Pontania dolichura larvae and sampling technique].

In this paper, the spatial distribution pattern of Pontania dolichura larvae was analyzed with Taylor's power law, Iwao's distribution function, and six aggregation indexes. The results showed that the spatial distribution pattern of P. dolichura larvae was of aggregated, and the basic component of the distribution was individual colony, with the aggregation intensity increased with density.

[Profit and loss of nutrients in crop-fruit ecosystems].

The analysis on the balance of nutrient's profit and loss in crop-fruit ecosystems of three villges in middle-south Loess Plateau showed that fertilization was the main input of nutrients, of which, chemical fertilizer occupied a larger proportion, while organic manure was relatively insufficient. The quantity of N, P and K spent in interior circulation was far less than that exported from the ecosystem. The ratio of nutrient's output and input in three test villages was differed, but all at a low level.

[Leaf structure and some physiologic characteristics of low temperature wheat germplasm].

Through a long-term observation on wheat canopy temperature, it was found that in the nature, there existed low temperature wheat germplasm (LTWG) with constant low canopy temperature, and high temperature wheat germplasm (HTWG) with constant high canopy temperature. The study on the leaf structure and some physiologic characteristics of LTWG during its blooming and milk-filling stages showed that the canopy temperature of LTWG was 1 to approximately 4 degrees C lower than that of HTWG. The mesophyll cells of LTWG functional leaves were smaller, more compact in cell arrangement, and 1 to approximately 2 cell layers more than those of HTWG's.

[Effects of salicylic acid on chlorophyll fluorescence and xanthophyll cycle in cucumber leaves under high temperature and strong light].

In this study, cucumber leaves were under high temperature and strong light stress after two days of spraying with 50 to approximately 400 micromol x L(-1) salicylic acid (SA) solution. The measurements showed that SA pretreatment could inhibit the decrease of intrinsic photochemical efficiency (Fv/ /Fm), quantum yield of PSII(phiPSII), maximum fluorescence value (Fm), and photochemical quenching (qP) by 16.1% to approximately 30.