Pilot-scale production of l-phenylalanine from d-glucose

Effects of inoculum size and total sugar content on both l-phenylalanine productivity and titre have been investigated using a tyrosine auxotrophic regulatory mutant of Escherichia coli. Fermentations were carried out in a 500 litre pilot fermenter with intermittent feeding of d-glucose plus phosphate. It was found that the productivity was not greatly affected by inoculum size. However, the l-phenylalanine titre was significantly affected by total sugar content. Relatively high productivities of up to 0.35–0.40 g l-phenylalanine l^?1 h^?1 have been achieved at l-phenylalanine titres of 14–15 g l^?1.     

草鱼出血病病毒多肽的免疫原性

采用中和试验比较了草鱼出血病病毒ＧＣＨＶ８７３的１１个多肽的免疫原性,确定了主要中和抗原。纯化的单个病毒多肽免疫家兔获得抗血清,多太ＶＰ１、ＶＰ５、ＶＰ６和ＶＰ９的抗血清具有中和效价,而ＶＰ２、ＶＰ３、ＶＰ４、ＶＰ８、ＶＰ１０和ＶＰ１１则不能诱生中和抗体。其中ＶＰ５的抗血清中和效价最高,因此,ＶＰ６极可能是病毒多肽中的主要中和抗原。     

Identification of the culturable and nonculturable bacterial population in ground water of a municipal water supply in Germany

AIMS: The identification of the culturable and nonculturable bacterial population in ground water of a municipal water supply in Mainz (Germany) during the year 2002. METHODS AND RESULTS: Total counts varied between 3.5 x 103 and 2.2 x 104 cells ml-1, viable counts were approximately between 8.1 x 102 and 3.3 x 103 cells ml-1. After cultivation on different nutrient media (R2A, DEV, PCA, Endo, Standard) <1% appeared to be culturable on the media used. After denaturating gradient gel electrophoreses, up to 24 different bacterial species were detected in the ground water. With the aid of 16S rDNA isolation, amplification and sequencing, the isolated organisms and clones could be identified. CONCLUSIONS: The isolated and cultured organisms mainly belonged to the Proteobacteria (alpha, beta and gamma), Flavobacteria or Actinobacteria. However, most of the noncultured micro-organisms were beta-Proteobacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study in which the identification of all culturable and nonculturable bacteria in a ground water has been attempted.     

应用Vero细胞检定法和家兔皮内中和法检测吸附白喉类毒素的效价

Ｖｅｒｏ细胞法测定ＤＴＰ疫苗中白喉类毒素的效价与家兔皮内中和法（简称ＮＴ法）所得结果两法之间有一种平行关系,并且有很好的相关性,ｒ＝０．９３。但Ｖｅｒｏ细胞法测得平均值低于ＮＴ法,二者之间的平均比率为０．２８７,Ｓ＝０．０８９。本试验结果与１９９５部颁规程ＮＴ法０．２５ＩＵ／ｍｌ相比,确定了Ｖｅｒｏ细胞法以０．０７ＩＵ／ｍｌ作为检定吸附ＤＴＰ效价的最低要求。     

2个玉米抗矮花叶病分子标记的有效性评价

玉米矮花叶病是玉米重要的病毒病害,培育抗病品种是防治该病最经济有效的方法,将常规育种方法与分子育种技术相结合可以大大提高抗病育种的效率。本研究利用前期研究开发的2个分子标记Indel186-9和SCAR112,检测100份常用玉米自交系的标记基因型,结合100份玉米自交系抗性表型鉴定结果进行2个分子标记辅助选择的有效性分析。结果表明,目前种质资源中高抗病材料较少,亟待进行抗病改良。本试验所用的自交系包括不同血缘,抗源主要来源于PB和四平头种质。Indel186-9标记和SCAR112标记的选择符合率均达到80%,同时使用两者选择符合率达到91.67%,其中抗病选择符合率达到100%。Indel186-9和SCAR112标记分别可以使抗病级别从平均7.26级提高到平均2.4级,平均7.63级提高到平均4.27级。试验证明2个标记均可用于对玉米抗矮花叶病材料的选择,正确组合使用可提高对玉米抗矮花叶病材料的选择效率。     

Haemolymph-ecdysteroid peaks occur in headless larvae of Calpodes ethlius

During the last-larval stadium of Calpodes ethlius, there is a critical period after which neck ligation no longer prevents pupation. Radioimmunoassay of haemolymph from larvae ligatured after this critical period shows that the ecdysteroid titre remains lower than normal for 3 days then rises to a prepupal peak, falls to a low level, and rises rapidly again close to the time of pupation. Hormone peaks resembling those found in normal larvae are, therefore, produced in the absence of the head. The slowly rising hormone titre seen in normal larvae prior to the prepupal peak is abolished by neck ligation, indicating that this phase of the titre retains dependence on the head after the critical period. This difference may account for the lack of intermoult wax and endocuticle secretion in neck-ligated larvae. It is concluded that peaks of haemolymph ecdysteroids can be generated at appropriate developmental stages in the absence of the head, whereas the slowly rising phase of haemolymph ecdysteroids cannot.     

Relationships among pheromone titre,calling and age in the omnivorous leafroller moth (Platynota stultana)

Temperature modified the expression of female calling in Platynota stultana. Absolute temperature levels and not necessarily a decrease in temperature appear to modulate the timing of calling by delimiting a specific time interval for calling at each temperature. Calling began earlier in the photoperiod at lower temperatures than at higher temperatures. As females aged they initiated calling at an earlier time. Pheromone production (at 24°C) was rhythmical with maximal titre being reached near to the onset of the calling period at 14°C and about 5 hr prior to the onset of calling at 24°C. Females thus appear to be capable of emitting pheromone at an appropriate rate any time during calling intervals delimited by temperatures between 14 and 24°C. Pheromone titre appears to reflect a time-dependent readiness to respond to a decrease in temperature.     

携带反义凝血酶受体和p21双基因共表达腺病毒伴随病毒载体的构建与包装

为探讨双基因共表达对再狭窄的防治作用,分别构建了含反义凝血酶受体(ATR)或/和p21单、双基因及报告基因绿色荧光蛋白(GFP)的腺病毒伴随病毒(AAV)载体.上述载体经脂质体介导转染BHK-21细胞, G418筛选获得整合有外源基因的细胞株.克隆形成过程中显示单、双基因转染后细胞增殖受到了不同程度的抑制,克隆形成速度减慢,细胞形态改变,且双基因的作用明显大于单基因.以绿色荧光出现说明报告基因得到表达后,又以DNA印迹证实ATR和p21单、双基因已整合于细胞基因组中,并维持了凝血酶受体(TR)基因的反义位置.半定量RT-PCR证实TR基因表达降低,p21基因表达升高,ATR和p21(AP)双基因得到了共表达.以具有可提供复制和包装功能的重组单纯疱疹病毒rHSV-rc/ΔU12分别感染载有不同基因的BHK细胞株,包装产生重组AAV(rAAV)病毒, 并经点杂交法测定其滴度(每毫升病毒液中所含病毒颗粒数).rAAV/AP中ATR与p21的病毒颗粒数分别为1.02×10¹³/ml和1.08×10¹³/ml, 单基因rAAV/ATR的滴度为6.54×10¹²/ml,rAAV/P21为1.06×10¹³/ml,为进一步的体内外实验奠定了物质基础.     

Prospecting the utility of a PMI/mannose selection system for the recovery of transgenic sugarcane (<Emphasis Type="Italic">Saccharum</Emphasis> spp. hybrid) plants

For the first time, the phosphomannose isomerase (PMI, EC 5.3.1.8)/mannose-based “positive” selection system has been used to obtain genetically engineered sugarcane (Saccharum spp. hybrid var. CP72-2086) plants. Transgenic lines of sugarcane were obtained following biolistic transformation of embryogenic callus with an untranslatable sugarcane mosaic virus (SCMV) strain E coat protein (CP) gene and the Escherichia coli PMI gene manA, as the selectable marker gene. Postbombardment, transgenic callus was selectively proliferated on modified MS medium containing 13.6 μM 2,4-D, 20 g l⁻¹ sucrose and 3 g l⁻¹ mannose. Plant regeneration was obtained on MS basal medium with 2.5 μM TDZ under similar selection conditions, and the regenerants rooted on MS basal medium with 19.7 μM IBA, 20 g l⁻¹ sucrose, and 1.5 g l⁻¹ mannose. An increase in mannose concentration from permissive (1.5 g l⁻¹) to selective (3 g l⁻¹) conditions after 3 weeks improved the overall transformation efficiency by reducing the number of selection escapes. Thirty-four vigorously growing putative transgenic plants were successfully transplanted into the greenhouse. PCR and Southern blot analyses showed that 19 plants were manA-positive and 15 plants were CP-positive, while 13 independent transgenics contained both transgenes. Expression of manA in the transgenic plants was evaluated using a chlorophenol red assay and enzymatic analysis.     

Subterranean clover mottle sobemovirus: its host range, resistance in subterranean clover and transmission through seed and by grazing animals

Subterranean clover mottle sobemovirus (SCMV) was transmitted by manual inoculation of sap to 27 cultivars belonging to three sub-species of subterranean clover. The virus readily infected systemically all inoculated plants of five susceptible cultivars of ssp. subterraneum. Ten others showed partial resistance as not all infected plants developed systemic infection; cold winter conditions further delayed or prevented systemic movement in four of them. Two cultivars of spp. brachycalycinum and four of spp. yanninicum failed to develop systemic infection following inoculation and were considered highly resistant. Resistance to SCMV in three of the spp. yanninicum was further confirmed by the failure to establish detectable primary infections in most of the inoculated leaves. Moreover, when the four ssp. yanninicum cultivars were graft-inoculated with SCMV, systemic infection eventually developed in them but the virus concentration was low. SCMV was also transmitted by manual inoculation of sap to a further 23 species of Trifolium, Medicago or Pisum. Three species were non-hosts, five were infected only in inoculated leaves and 18 others developed systemic infection in some or all plants. SCMV reached very high concentrations and was stable in subterranean clover sap. It was transmitted experimentally between subterranean clover plants by brushing infected leaves against healthy ones and in swards was readily transmitted by the trampling and grazing of sheep, but only poorly by mowing. Seed transmission of SCMV to seedlings of five cultivars of subterranean clover was low (0–0.12%). SCMV was not transmitted by Myzus persicae.