3-羟基丙酸高产菌株的筛选及诱变选育

【目的】3-羟基丙酸是一种重要的化学平台化合物,期望得到一株能够高产3-羟基丙酸的菌株。【方法】从土壤及粪便筛选并对得到的菌株进行鉴定和复合诱变。【结果】得到了一株能够利用丙酸发酵生产3-羟基丙酸的酵母Y-11,经生理生化鉴定及18S rDNA序列分析确定其为Candida sp.(假丝酵母)。以Y-11为出发菌株,经紫外-亚硝基胍-60Coγ复合诱变得到了突变性状稳定且可遗传的高产菌株5-13B,其3-羟基丙酸的产量为11.78 g/L,是出发菌株的2.46倍。【结论】对出发菌株和突变株的发酵特性进行了比较,结果表明突变株的3-羟基丙酸产量、对底物丙酸的转化率、产物3-羟基丙酸的积累性能及丙酸的耐受性均优于出发菌株。     

Fusarium solani invader of the eggs of the insectPanstrongylus geniculatus in a vivarium

A strain ofFusarium solani sensu Snyder & Hansen invaded the eggs of the insectPanstrongylus geniculatus in a vivarium. None of the invaded eggs hatched. To establish experimentally the pathogenicity of thisFusarium species against the eggs ofP. geniculatus, the fungus and the eggs were incubated together under different relative humidities and temperatures. At 64% relative humidity and 26 °C, the fungus grew well colonizing and penetrating all of the chorions.Three embryos died and were also colonized byF. solani. Only 4 nymphs hatched and survived to day 20. It is concluded that the isolate ofF. solani was capable of colonizing and invading the chorion of the eggs under certain humidity and temperature conditions and cause the death of the embryos.     

Production of chitinolytic enzymes from a novel species ofAeromonas

A bacterial strain secreting potent chitinolytic activity was isolated from shrimp-pond water by enrichment culture using colloidal crab-shell chitin as the major carbon source. The isolated bacterium, designated asAeromonas sp No. 16 exhibited a rod-like morphology with a polar flagellum. Under optimal culture conditions in 500-ml shaker flasks, it produced a chitinolytic activity of 1.4 U ml^–1. A slightly higher enzymatic activity of 1.5 U ml^–1 was obtained when cultivation was carried out in a 5-liter jar fermentor using a medium containing crystalline chitin as the carbon source. The secretion of the enzyme(s) was stimulated by several organic nitrogenous supplements. Most carbon sources tested (glucose, maltose, N-acetylglucosamine, etc) enhanced cell growth, but they slightly inhibited enzyme secretion. Glucosamine (0.5% w/v) severely inhibited cell growth (16% of the control), but it did not significantly affect enzyme secretion. The production of chitinolytic enzymes was pH sensitive and was enhanced by increasing the concentration of colloidal chitin to 1.5%. The observed chitinolytic activity could be attributed to the presence of -N-acetylglucosaminidase and chitinase. Chitinase was purified by ammonium sulfate fractionation and preparative gel electrophoresis to three major bands on SDS-PAGE. An in-gel enzymatic activity assay indicated that all three bands possessed chitinase activity. Analysis of the enzymatic products indicated that the purified enzyme(s) hydrolyzed colloidal chitin predominantly to N,N-diacetyl-chitobiose and, to a much lesser extent, the mono-, tri, and tetramer of N-acetylglucosamine, suggesting that they are mainly endochitinases.     

青海湖裸鲤寄生舌状绦虫的空间格局研究

舌状绦虫裂头蚴只寄生在体长小于２２０ｍｍ的青海湖裸鲤中,其种群在宿主种群中呈聚集分布。其聚集分布的强度随寄生虫种群平均密度的增加而降低。由于舌状绦虫在宿主体腔生长,产生明显的空间拥挤效应,可能导致宿主死亡或被食鱼鸟类捕食而转移到终末宿主中。在体长小于１２０ｍｍ的宿主中,密度依赖的死亡过程可能是使聚集强度降低的原因;而体长１４０－２００ｍｍ的鱼中,则是非密度依赖的全死过程使聚集强度增加．     

Production of phenolics and the emission of volatile organic compounds by perennial ryegrass (Lolium perenne L.)/Neotyphodium lolii association as a response to infection by Fusarium poae

Grasses very often form symbiotic associations with Neotyphodium/Epichloë endophytic fungi. These endophytes often allow the host grass to be protected from different pathogens. However, there is little known about the mechanisms of such endophyte influence on the host. Thus, the purpose of this research was to examine the effect of the N. lolii endophyte on the total production of phenolic compounds, VOCs emission and the resistance of three perennial ryegrass genotypes infected by pathogenic Fusarium poae. Analyses of total phenolics content were performed in control (not inoculated) and inoculated plants after 1, 2, 3, 4, 5, and 6 days (DAI) and for VOCs after 0, 3, 6 and 12 DAI. The presence of endophytes significantly reduced the disease index in two of the three genotypes relative to that in E−. Plants infected by N. lolii exhibited higher production of phenolics relative to the E− plants. The highest amounts of phenolics were observed on the second and sixth DAI. Genotype Nl22 showed the strongest effect of the endophyte on the production of phenolics, which increased by over 61%. Both the endophyte infected and non-infected plants emitted most abundantly two GLVs ((Z)-3-hexenal, (Z)-3-hexen-1-yl acetate), three terpenes (linalool, (Z)-ocimene, β-caryophyllene) and three shikimic acid pathway derivatives (benzyl acetate, indole, and methyl salicylate). The endophyte presence and the intervals of VOCs detection were a highly significant source of variation for all emitted volatiles (P < 0.001). The genotype of the perennial ryegrass significantly affected only the emission of methyl salicylate (P < 0.05) and β-caryophyllene (P < 0.05). Most of the VOCs ((Z)-3-hexen-1-yl acetate, (Z)-3-hexenal, linalool and methyl salicylate) reached their highest levels of emission on the sixth DAI, when averaged over genotypes and endophyte status. The results highlight the role of Neotyphodium spp. in the mediation of quadro-trophic interactions among plants, symbiotic endophytes, invertebrate herbivores and plant pathogenic fungi. Our results also confirm the fact that symbiotic plants can activate a defense reaction faster than non-symbiotic plants after a pathogen attack. Thus, N. lolii can be involved in the defense of perennial ryegrass against pathogens and potentially could be central to the host plants’ protection.     

Allelopathic effect of actinobacterial isolates against selected weeds

The taxonomic characteristics of weeds such as morphology of shoot, leaves, flowers, stem, fruits and seeds were recorded as Gynandropsis pentaphylla, DC, Amarantus spinosus Linn, Cyperus rotundus, Amarantus viridis Linn, Cassia occidentalis, Linn and Echinochilora orygicola. Totally 20 actinobacteria isolates were screened for herbicidal activity against the weed. Among the 20 isolates, only four actinobacterial isolates KA1-3, KA1-4, KA1-7 and KA23A showed significant herbicidal activity against C. rotundus. The herbicidal effect of actinobacterial culture filtrates on germination and seedling growth of C. rotundus was tested. The shoot and root growth of C. rotundus was severely affected when compared to control. The potent actinobacterial isolates KA1-4 and KA1-7 were characterised based on their morphological and molecular phylogenetic property and were identified as Streptomyces sp. The present study concludes that actinobacterial isolates will be used as bioherbicide against C. rotundus. Further studies are required to confirm the activity of actinobacterial isolates against C. rotundus under field conditions.     

The Purification of Amyloid Fibril Proteins

Amyloid fibril concentrates have been fractionated and shown to have homogeneous fragments of the variable region of immunoglobulin proteins as their major protein constituent. Amyloid fibril protein purification was performed on ten amyloid preparations by sequential gel filtration on Sepharose 4 B and Sephadex G-100 columns equilibrated with 5 M guanidine-HCl in 1 N acetic acid.     

岷江百合类萌发素蛋白基因LrGLP2的克隆及表达特性分析

类萌发素蛋白是植物中普遍存在的一类可溶性糖蛋白,在植物抗逆胁迫中起着重要作用。依据岷江百合编码GLP的EST序列设计引物,采用快速扩增cDNA末端技术,从岷江百合犯ilium regale Wilson）克隆得到一个新的GLＰt基因的全长eDNA序列,命名为LrGLP2。LrGLP2全长cDNA为921bp,含有654bp的开放阅读框,49bp5’非编码区以及218bp3’UTR,编码217个氨基酸的蛋白质。LrGLP2编码蛋白质与已知植物GLPs家族成员间的同源性和聚类分析表明LrGLP2与来源于水稻（Oryza sativa）、节节麦似egilopstauschii）、葡萄（Vitis vinifera）中的GLPs具有较高的相似性。qRT-PCR分析显示,LrGLP2在岷江百合正常生长发育的根中有一定量的表达,而在茎和叶中几乎检测不到表达量。水杨酸、茉莉酸以及H202处理均不同程度抑制LrGLP2的转录水平,但乙烯处理能明显诱导LrGLP2的表达。此外,岷江百合接种尖孢镰刀菌（Fusari—umoxysporumfsp．tiliO后,LrGLP2在接种后2h表达迅速上调,12h表达量急剧上升,至24h表达量达到最大值,之后表达量下降,可见￡rGLP2参与岷江百合对尖孢镰刀菌的防卫反应。     

A new genus and species of Coenosiini from Costa Rica (Diptera,Muscidae, Coenosiinae)

Palpilongus gen. n. is herein described for one species – Palpilongus bifurcus sp. n., from Costa Rica, based on male and females. The striking morphological characters of the species – palpus very long, about as long as prementum; upper calypter truncate and very short and setae of male sternite 5 bifurcated, confirm that this new species is also a new genus in the tribe Coenosiini. Male and female terminalia were dissected and illustrated.     

A New Species of Kudoa (Myxosporidea: Chloromyxidae) from the Spot,Leiostomus xanthurus Lacépède,in Clear Lake,Texas*

SYNOPSIS. Kudoa branchiata sp. n. (Myxosporidea: Chloromyxidae) is described from the gills of the marine sciaenid fish, Leiostomus xanthurus Lacépède, from Clear Lake, Texas. Twelve of the 429 hosts examined from 10 September 1970 to 28 April 1971, were infected. Eight of the 12 infected fish were collected in February and March 1971—a period during which only 13% of the total host sample was taken. The mean total length of infected hosts was 149 mm, with a range of 112–185 mm. The mean number of myxosporidean cysts per infected host was 3.5, with a range of 1–11.