A Cold Acclimation Protein with Refolding Activity on Frozen Denatured Enzymes

We found that a cold acclimation protein from an ice-nucleating bacterium, Patoea ananas KUIN-3, has refolding activity on frozen denatured protein. Based on a SDS-PAGE analysis, we confirmed that the cold shock-treated cells of strain KUIN-3 could produce some cold acclimation proteins that inhibit their syntheses by the addition of chloramphenicol during the cold acclimation. Among such proteins, Hsc25 had refolding activity similar to GroELS. Hsc25 was purified to apparent homogeneity by (NH₄)₂SO₄ precipitation and some chromatographies. The purified Hsc25 was composed of 8 subunits of 25,000 each with a molecular mass of 200,000 and had refolding activity against denatured enzymes, which were denatured by heat-treatment at 100°C, cryopreservation at -20°C, or guanidine hydrochloride, in a manner similar to GroELS. The N-terminal sequence of Hsc25 was Met-Arg-Ala-Ser-Thr-Tyr-His-Ala-Ala-Arg-. Furthermore, Hsc25 had a high level of activity at low temperature (12°C). Also, the dissociation constants, KD (M) as the binding specificity for enolase, mutarotase, isocitrate dehydrogenase, and lactate dehydrogenase were 1.82×10^-10, 4.35×10^-9, 8.98×10^-12, and 3.05×10^-11, respectively. The affinity of Hsc25 for frozen danatured enzymes was higher than the affinity for heat denatured enzymes when compared with the affinity of GroEL. These results are the first report on the characterization of a purified chaperon that was induced by cold acclimation.     

一株寒地高效解无机磷细菌的分离鉴定及拮抗作用

【目的】从北方寒地种植的不同农作物根际土壤中分离高效解磷的细菌,为微生物制剂和磷肥的开发提供适于本地区的优良菌种。【方法】通过初筛和复筛从26株解磷菌中筛选获得一株高效解磷细菌,对其进行生理生化和分子生物学鉴定,同时采用钼蓝比色法测定解磷能力。采用平板对峙法测定拮抗植物病原菌能力。【结果】通过筛选后获得的菌株B51-7经鉴定为伯克霍尔德菌属。菌株在发酵液中可溶性磷含量最高达到832.74 mg/L,同时具有很强的广谱抑菌作用,抑菌率最高为89.71%,可以显著促进水稻生长。【结论】菌株B51-7是一株具有生物防治作用的高效解磷细菌,可应用于生物菌肥和生防制剂中。     

Seed reproductive biology of the rare aquatic carnivorous plant Aldrovanda vesiculosa (Droseraceae)

Despite the unprecedented global decline in extant populations of Aldrovanda vesiculosa in the last century, little is known about the reproductive biology of this iconic aquatic carnivorous plant. This study aimed to investigate the role of seed‐based reproduction in the ecology of A. vesiculosa, with particular focus on the interplay between the regulation of seed dormancy by temperature cues and the efficacy of exogenous ethylene gas to act as a germination stimulant, the desiccation capacity and long‐term storage potential of seeds for conservation purposes. Sexual reproduction appears to be extremely limited in both natural and naturalized populations across three continents, with high variability in the success of flowering and seed set between sites and between seasons. Overall, flowering yielded few fertile fruit (6–19% of flowers producing fertile fruit) and seed viability was variable but generally low (29–88%). Fecundity appears to be influenced by seasonal climatic conditions and microhabitat characteristics. Aldrovanda vesiculosa possesses physiologically dormant seeds, with germination stimulated by exposure to ethylene gas (>90% germination) at 25 °C. Seeds appear sensitive to desiccation and sub‐zero temperature storage, with no germination and markedly reduced embryo growth after storage of seeds for >1 month at 15 °C and 15% relative humidity or after short‐term (24 h) storage at ?18 °C. In the absence of significant conservation and restoration initiatives, the continuing decline of dystrophic freshwater wetland habitats globally leaves A. vesiculosa facing extinction. As the successful long‐term storage of seeds appears unfeasible based on the approaches described in this study, other alternatives for germplasm conservation such as cryostorage of vegetative tissues or zygotic embryos must be considered for establishing long‐term ex situ collections of critical germplasm.     

耐低温荧光假单胞菌筛选体系建立及其植物促生作用评价

【目的】以前期研究小麦生境分离细菌为菌株库,从中筛选耐低温菌株,评价其植物促生效果。【方法】通过4°C低温培养筛选耐低温菌株。以产吲哚乙酸、1-氨基环丙烷羧酸(ACC)脱氨酶、嗜铁素以及无机、有机磷溶解能力为评价指标,测定15°C和28°C环境中耐低温菌株的植物促生作用潜力,利用赋分评估系统选定潜力菌株进行温室和田间试验验证其植物促生作用。【结果】筛选到34株耐低温菌株,从中选定的8株植物促生潜力细菌温室试验促生效果和评估分值之间的相关性在0.62以上,菌株1b YB22和3b JN2在28°C环境中对黄瓜的促生效果均在28%以上,二者在15°C环境中对青菜种子根长的促生效果分别为116.76%和46.82%,菌株1b YB22在15°C环境中对青菜的促生效果为25.11%。菌株1b YB22在田间应用对小麦生长同样具有促生作用,增产效果达0.58%。【结论】研究建立的筛选体系从小麦生境分离菌株中获得了耐低温荧光假单胞菌株1b YB22和3b JN2,两株细菌在15°C和28°C均具有植物促生作用,同时可以在田间促进小麦生长。     

长期冷藏对越冬代异色瓢虫繁殖及子代生长发育和捕食能力的影响

异色瓢虫被认为是一种重要的捕食性天敌,常被用来防治蚜虫、介壳虫、叶螨等害虫。为了更好地开发利用东北地区丰富的越冬代异色瓢虫自然资源,本研究调查了低温冷藏(3℃冷藏0,30,60,90,120,150 d)对吉林采集的越冬代异色瓢虫繁殖及其子代生长发育和捕食能力的影响。研究结果表明,经历90 d冷藏的瓢虫产卵量最大,明显高于冷藏60 d个体的产卵量,与冷藏120 d、150 d及未经冷藏个体的产卵量不存在明显差异;经历不同冷藏期的瓢虫与室内人工饲养种群子代具有相似发育历期(约16.0 d);而且长期冷藏也未对瓢虫子代幼期的捕食能力产生负面影响,冷藏150 d瓢虫的子代在整个幼虫阶段能捕食662.8头蚜虫,与未冷藏个体和人工饲养种群个体不存在明显差异。本研究为开发利用东北地区越冬代异色瓢虫自然资源的生物防治作用提供了理论依据。     

南海冷泉区深海沉积物中细菌的分离培养及多样性分析

为了认识南海深海冷泉区沉积物中可培养微生物的多样性,本文以冷泉区与非冷泉区两个站点的深海沉积物为样品,通过两种培养基(R2A海水培养基和2216E培养基)直接涂布或富集后平板分离纯化,从9个样品中共得到395株菌株,并通过16SrRNA基因鉴定,分属10个属。发现产芽胞细菌分布最广、丰度最大,包括3个属、15个种。其中芽胞杆菌(Bacillus)无论是在数量还是在种类上都分布最多。并且,随着水深和沉积物深度的增加,分离到的可培养微生物丰富度降低。本研究表明,即使在冷泉区,南海深海沉积物中产芽胞细菌也比较丰富。     

氨基酸的冷电弧-光催化-吸附脱色工艺优化

将TiO2光催化剂负载于活性炭,然后将活性炭装填于冷电弧-光催化-吸附集成反应器中,用该反应器对豆粕氨基酸进行脱色。以豆粕氨基酸的脱色率和氨基酸保留率为指标,探讨处理电压、处理时间、溶液pH和活性炭填充量4个因素对脱色效果的影响。在单因素试验的基础上,利用二次回归正交旋转组合设计建立回归模型方程确定最佳工艺条件,并对方程进行回归分析和系数检验。结果表明:回归方程在#=0.01水平上高度显著。各因素对脱色效果的影响程度大小依次为:溶液pH>活性炭填充量>处理时间>处理电压。最佳脱色条件为处理电压20kV、处理时间11min、溶液pH 3.6和活性炭填充量63g,此条件下氨基酸溶液脱色率为94.8%,保留率为83.1%。     

利用低温水浴鉴定水稻苗期耐寒性

高效准确鉴定苗期耐寒性是水稻(Oryza sativa)耐寒研究的前提。基于流动水浴温度均一这一特性, 建立了一种恒温水浴鉴定水稻幼苗耐寒性方法。该方法中环境温度设定为20°C, 水浴温度设定为4°C。根据对2个水稻亚种不同材料的处理结果, 总结出几种常见品种的低温处理时间与存活率参考值, 并对操作过程中的一些注意事项进行了说明。     

Preliminary analysis of geographical distribution based on cold hardiness for Evergestis extimalis (Scopoli) (Lepidoptera: Pyralidae) on Qinghai–Tibet Plateau

Evergestis extimalis  (Scopoli) is a pest insect present in spring rape fields of the Qinghai–Tibet plateau. A survey of its distribution and analysis of its physiological and biochemical variances of its overwintering larvae were conducted in this study. Prior to 2006, Evergestis extimalis Scopli appeared only sporadically at the east agricultural district of Qinghai Province at 2,100 m elevation; after 2006, there have been frequent outbreaks at 2,200 m or so height. The insect's distribution has extended continuously toward higher altitudes yearly, and the scope of its damage reached 2,800 m height in 2010. These changes indicate that the cold hardiness of E. extimalis is on the rise. Physiological and biochemical analyses were performed for the insect's overwintering larvae from November 2011 to March 2012. The supercooling point (SCP) and freezing point (FP) ranged from ?6.85°C to ?12.49°C and from ?6.23°C to ?8.17°C, respectively, and both were at their respective lowest points in January 2012; the lowest points of water and fat contents (which did not vary to any extreme degree throughout the test period) were also observed in January 2012. Glycogen content varied from 2.42 mg/g to 4.56 mg/g. Protein content increased gradually at the first two months and reached its peak in January 2012 before dropping slightly. The activity of protective enzymes POD, CAT, and SOD varied with changes in environmental temperature, and each was at its lowest point in January 2012. With the exception of protein and glycerol content, other physiological and biochemical variances were generally parallel with environmental temperature, strongly indicating that E. extimalis has indeed developed cold hardiness.