长白山哈泥泥炭地持久孢子库的实验证据

有性繁殖体库对于植物种群的长存具有重要意义,迄今为止,泥炭地尚无苔藓植物长期的持久孢子库的直接实验证据。在长白山哈泥泥炭地,钻取50 cm表层泥炭样品,运用落叶松测年法推算泥炭地地层泥炭藓孢子的埋藏时间,经逐层提取和培养尖叶泥炭藓孢子,研究埋藏时间对孢子萌发率的影响。结果表明,随着埋藏时间的增加,尖叶泥炭藓孢子萌发率呈现对数函数递减的趋势。研究获得泥炭地苔藓植物具有长期的持久孢子库的实验证据,即埋藏112年的尖叶泥炭藓孢子仍具萌发潜力。据推算,泥炭藓孢子最大寿命可达396.4年。     

Analysis of the action of compounds that inhibit the germination of spores of Bacillus species

AIMS: To determine the mechanism of action of inhibitors of the germination of spores of Bacillus species, and where these inhibitors act in the germination process. METHODS AND RESULTS: Spores of various Bacillus species are significant agents of food spoilage and food-borne disease, and inhibition of spore germination is a potential means of reducing such problems. Germination of the following spores was studied: (i) wild-type B. subtilis spores; (ii) B. subtilis spores with a nutrient receptor variant allowing recognition of a novel germinant; (iii) B. subtilis spores with elevated levels of either the variant nutrient receptor or its wild-type allele; (iv) B. subtilis spores lacking all nutrient receptors and (v) wild-type B. megaterium spores. Spores were germinated with a variety of nutrient germinants, Ca2+-dipicolinic acid (DPA) and dodecylamine for B. subtilis spores, and KBr for B. megaterium spores. Compounds tested as inhibitors of germination included alkyl alcohols, a phenol derivative, a fatty acid, ion channel blockers, enzyme inhibitors and several other compounds. Assays used to assess rates of spore germination monitored: (i) the fall in optical density at 600 nm of spore suspensions; (ii) the release of the dormant spore's large depot of DPA; (iii) hydrolysis of the dormant spore's peptidoglycan cortex and (iv) generation of CFU from spores that lacked all nutrient receptors. The results with B. subtilis spores allowed the assignment of inhibitory compounds into two general groups: (i) those that inhibited the action of, or response to, one nutrient receptor and (ii) those that blocked the action of, or response to, several or all of the nutrient receptors. Some of the compounds in groups 1 and 2 also blocked action of at least one cortex lytic enzyme, however, this does not appear to be the primary site of their action in inhibiting spore germination. The inhibitors had rather different effects on germination of B. subtilis spores with nutrients or non-nutrients, consistent with previous work indicating that germination of B. subtilis spores by non-nutrients does not involve the spore's nutrient receptors. In particular, none of the compounds tested inhibited spore germination with dodecylamine, and only three compounds inhibited Ca2+-DPA germination. In contrast, all compounds had very similar effects on the germination of B. megaterium spores with either glucose or KBr. The effects of the inhibitors tested on spores of both Bacillus species were largely reversible. CONCLUSIONS: This work indicates that inhibitors of B. subtilis spore germination fall into two classes: (i) compounds (most alkyl alcohols, N-ethylmaleimide, nifedipine, phenols, potassium sorbate) that inhibit the action of, or response to, primarily one nutrient receptor and (ii) compounds [amiloride, HgCl2, octanoic acid, octanol, phenylmethylsulphonylfluoride (PMSF), quinine, tetracaine, tosyl-l-arginine methyl ester, trifluoperazine] that inhibit the action of, or response to, several nutrient receptors. Action of these inhibitors, is reversible. The similar effects of inhibitors on B. megaterium spore germination by glucose or KBr indicate that inorganic salts likely trigger germination by activating one or more nutrient receptors. The lack of effect of all inhibitors on dodecylamine germination suggests that this compound stimulates germination by creating channels in the spore's inner membrane allowing DPA release. SIGNIFICANCE AND IMPACT OF THE STUDY: This work provides new insight into the steps in spore germination that are inhibited by various chemicals, and the mechanism of action of these inhibitors. The work also provides new insights into the process of spore germination itself.     

Effect of mechanical abrasion on the viability, disruption and germination of spores of Bacillus subtilis

AIMS: To elucidate the factors influencing the sensitivity of Bacillus subtilis spores in killing and disrupting by mechanical abrasion, and the mechanism of stimulation of spore germination by abrasion. METHODS AND RESULTS: Spores of B. subtilis strains were abraded by shaking with glass beads in liquid or the dry state, and spore killing, disruption and germination were determined. Dormant spores were more resistant to killing and disruption by abrasion than were growing cells or germinated spores. However, dormant spores of the wild-type strain with or without most coat proteins removed, spores of strains with mutations causing spore coat defects, spores lacking their large depot of dipicolinic acid (DPA) and spores with defects in the germination process exhibited essentially identical rates of killing and disruption by abrasion. When spores lacking all nutrient germinant receptors were enumerated by plating directly on nutrient medium, abrasion increased the plating efficiency of these spores before killing them. Spores lacking all nutrient receptors and either of the two redundant cortex-lytic enzymes behaved similarly in this regard, but the plating efficiency of spores lacking both cortex-lytic enzymes was not stimulated by abrasion. CONCLUSIONS: Dormant spores are more resistant to killing and disruption by abrasion than are growing cells or germinated spores, and neither the complete coats nor DPA are important in spore resistance to such treatments. Germination is not essential for spore killing by abrasion, although abrasion can trigger spore germination by activation of either of the spore's cortex-lytic enzymes. SIGNIFICANCE AND IMPACT OF THE STUDY: This work provides new insight into the mechanisms of the killing, disruption and germination of spores by abrasion and makes the surprising finding that at least much of the spore coat is not important in spore resistance to abrasion.     

光照和温度对尖叶拟船叶藓孢子萌发及原丝体发育的影响

用组织培养法和光学显微镜技术初步研究了光照和温度对尖叶拟船叶藓孢子萌发及原丝体发育的影响。结果表明：（1）光照是影响孢子萌发的主要环境因子,20℃环境下,24h光照4d的孢子萌发率达83.3％;温度下黑暗培养的孢子30d也不能萌发,转光照后4d的萌发率可达84.6％;（2）温度是影响原丝体发育的主要环境因子,连续光照下,20℃的原丝体生长最快、分枝最多、分化最早,第31天可长达651.64μm;25℃次之,只有379.12μm;而自然光照下5-10℃环境下的孢子萌发率（18d为70.2％）和原丝体生长速度（127.44μm）均最慢;（3）原丝体发育到一定阶段,断裂为单个细胞,单个细胞再萌芽出新原丝体。     

Fine structure of resting spore formation and germination in Entomophthora virulenta

The fine structure during the formation and germination of resting spores of Entomophthora virulenta is described. There were many microbodies in contact with oil droplets, and the microbodies appeared to participate in spore germination. The mature resting spore had an epispore layer with two regions and an endospore layer with five regions. Dictyosomes, numerous vesicles, and lomasomes were produced during the formation of the endospore layer. Prior to spore germination, the single large oil droplet separated into numerous small oil droplets, and the new cell wall was formed beneath the endospore layer which gradually disintegrated possibly by enzymatic actions. The germ tube perforated the epispore layer mainly by mechanical pressure.     

Studies on the mechanism of the osmoresistance of spores of Bacillus subtilis

AIMS: To determine the reason that spores of Bacillus species, in particular Bacillus subtilis, are able to form colonies with high efficiency on media with very high salt concentrations. METHODS AND RESULTS: Spores of various Bacillus species have a significantly higher plating efficiency on media with high salt concentration (termed osmoresistance) than do log or stationary phase cells. This spore osmoresistance is higher on richer media. Bacillus subtilis spores lacking various small, acid-soluble spore proteins (SASP) were generally significantly less osmoresistant than were wild-type spores, as shown previously (Ruzal et al. 1994). Other results included: (a) spore osmoresistance varied significantly between species; (b) the osmoresistance of spores lacking SASP was not restored well by amino acid osmolytes added to plating media, but was completely restored by glucose; (c) the osmoresistance of spores lacking SASP was restored upon brief germination in the absence of salt in a process that did not require protein synthesis; (d) significant amounts of amino acids generated by SASP degradation were retained within spores upon germination in a medium with high but not low salt; (e) slowing but not abolishing SASP degradation by loss of the SASP-specific germination protease (GPR) did not affect spore osmoresistance; (f) sporulation at higher temperatures produced less osmoresistant spores; and (g) spore osmoresistance was not decreased markedly by the absence of the stress sigma factor for RNA polymerase, sigmaB. CONCLUSIONS: Spore osmoresistance appears as a result of three major factors: (1) specific characteristics of spores and cells of individual species; (2) the precise sporulation conditions that produce the spores; and (3) sufficient energy generation by the germinating and outgrowing spore to allow the spore to adapt to conditions of high osmotic strength; the substrates for this energy generation can come from either the endogenous generation of amino acids by SASP degradation or from the spore's environment, in the form of a readily taken up and metabolized energy source such as glucose. SIGNFICANCE AND IMPACT OF STUDY: These results provide information on the mechanisms of spore osmoresistance, a spore property that can be of major applied significance given the use of high osmotic strength with or without high salt as a means of food preservation.     

Longevity and germination of Edhazardia aedis (Microspora: Amblyosporidae) spores

Edhazardia aedis is a polymorphic microsporidium of mosquitoes that is both horizontally and vertically transmitted to its host. Because it is being developed for biological control of mosquitoes, detailed knowledge is needed regarding the longevity and germation of its fragile, mosquito‐infectious spore. Spores responsible for horizontal transmission were extracted from 7–10‐day‐old larvae (reared from infected Aedes aegypti eggs) and purified by Ludox density gradient centrifugation. Mature spores were variable in specific gravity, being found throughout the 20 and 60% zone in Ludox gradients. The optimal environment for spore germination was dilute KCl at pH 10.0–11.0; ammonia inhibited germination. Osmotic inhibition was almost complete in both sucrose and polyethylene glycol at concentrations equivalent to 40 atm. The spores retained their viability for a maximum of 21 days at 23±2°C, whereas when held at 5±2°C, their viability was completely lost within two days post‐harvest. Potential for germination decreased along with infectivity, providing a simple assay for spore viability.     

甘蓝根肿病菌的生物学特性研究*

对甘蓝根肿病菌生物学特性研究表明,该菌休眠孢子萌发的最适温度24℃,最适pH值6.0～6.7,致死温度45℃,肿根腐烂处理可以显著提高萌发率,光对休眠孢子萌发有明显抑制作用。该菌休眠孢子在感病寄主的根分泌物溶液中萌发率最高,达75%。耐病甘蓝品种及番茄的根分泌物均能刺激休眠孢子萌发。通过电镜观察,根肿病菌休眠孢子为近球形,孢壁有乳状突起,直径2.1～3.1mm(平均直径2.5mm)。游动孢子为近球形或椭圆形,大小为1.6～3.6mm,同侧着生不等长尾鞭式双鞭毛。     

Spore coat is altered in modB glycosylation mutants of Dictyostelium discoideum.

The modB mutation eliminates specific carbohydrate epitopes from glycoproteins which are expressed primarily in prespore and spore cells of differentiating Dictyostelium discoideum. Spores formed by the mutant show several phenotypes. Whereas mutant spores germinate efficiently after heat activation, they germinate poorly after urea activation. Following germination, at least one glycosylation-defective glycoprotein is cleaved, and the larger fragment is released in soluble form from the spore coat. However, an earlier difference in the spore coat can be traced back to the nongerminated spore coat, as detected by the elutability of protein from intact spores by chemical extraction. An altered character of the pregermination spore coat is also suggested by increased labeling by a fluorescent lectin which binds to its interior. The findings are consistent with a change in the character of certain molecular contacts leading to altered characteristics of the mutant spore coat, which are specific because they are distinctive from changes observed in another glycosylation mutant which affects a different epitope.     

藓类植物孢子生活力的快速检测方法初探

通过对温度和光照条件的实验探索,筛选出金发藓（Polytrichum commune）和细叶小羽藓（Haplocladium microphyllum）2种藓类孢子萌发的最适条件。采用碘-碘化钾染色法、TTC染色法、红墨水染色法、亚甲基蓝染色法对6种藓类植物孢子的生活力进行测定,并将测得的生活力结果与孢子萌发率进行了比较分析。结果表明,亚甲基蓝染色法测定的藓类植物孢子平均生活力百分率与孢子平均萌发率最为接近,且染色效果明显,可用于苔藓植物孢子生活力的快速测定。亚甲基蓝染色法测得的孢子生活力（x）与其离体萌发率（y）的相关性达到极显著水平（r=0.976）,其回归方程为y=-8.547+1.069x(P<0.01),可通过孢子生活力方便预测萌发率。     

Spatial patterns of litter decomposition in the littoral zone of boreal lakes

1. We studied the patterns of litter decomposition in lake littoral habitats and investigated whether decay rates, as an integrating proxy for environmental conditions in the sediment, would co‐vary with net carbon dioxide (CO₂) exchange and methane (CH₄) efflux. These gas fluxes are known to be sensitive to environmental conditions. Losses in the mass of cellulose, root, rhizome and moss litter were measured during 2 years in boreal littoral wetlands in Finland and compared with published data on concurrently measured gas fluxes. Four study sites covered a range of sediment types and hydrological conditions. 2. Decomposition was not linearly related to the duration of flooding but depended on sediment type. Readily decomposable litter fractions, such as cellulose and rhizome litter, lost mass at a faster rate in marshes with a longer period of flooding but wide water level fluctuations that hinder establishment of a Sphagnum cover, than in peat‐forming fens. In marshes, the mean first‐year mass losses were 83–99% and 19–62% for cellulose and rhizomes, respectively. In fens, the respective losses were 40–53% and 33%. In the first year, the loss in the mass of the more recalcitrant root litter did not differ between sites (mean 19–30%) and moss litter lost no mass. 3. The estimated first‐year carbon loss from belowground litter was about 0.1–0.3 times ecosystem respiration and roughly similar to net carbon gas (CO₂, CH₄) efflux, suggesting that vascular plants and recent plant residues contribute substantially to ecosystem release of carbon gases. On the other hand, at least 40% of the mass of the belowground litter remained on a littoral site after the first 2 years of decomposition. Slow decomposition may indicate the accumulation of organic‐rich sediments. The accumulated carbon could explain the excess CO₂ release found in most littoral sites. In continuously inundated sites decomposition rates were similar to those in periodically flooded sites, but ecosystem‐atmosphere CO₂ exchange fell to close to zero. This discrepancy implies that the released CO₂ is dissolved in water and may be exported into the pelagic zone of the lake.     

近40年来辽宁地区气候干湿界线年代际波动及其成因

应用1961～2004年辽宁省内52个气象站的温度、降水、湿度、风和日照等气候资料,采用改进的Penman模型计算了辽宁地区近40年的潜在蒸发量,讨论了其时空代表性及分布特征;以干燥度指数为干湿气候区的划分标准,通过对该地区近40年干湿气候界线波动状况的对比,在10年际尺度上详细分析了其干湿气候界线波动及变化规律.结果表明,20世纪60年代以来,辽宁省干湿气候界线波动显著,呈现出整体移动的特征,但半湿润与湿润、半干旱与半湿润两条界线并未表现出同进、同退的年际变化特征.20世纪90年代辽宁省干湿气候存在一次突变,半湿润与湿润界限明显东移,半干旱与半湿润界线明显西移,半干旱和湿润区面积都显著缩小,半湿润区面积显著扩大.辽宁西部的气候干湿状况主要由西太平洋副热带高压和东南季风控制,辽宁东部的气候干湿状况除受西太平洋副热带高压和东南季风的影响外,还应考虑到地形降水的作用.     

Spore germination of Frankia strains isolated from Colletia hystrix and Retanilla ephedra (Rhamnaceae)

Two Frankia strains, ChI1 from Colletia hystrix and ReI6 from Retanilla ephedra, were assayed to determine the germinability of their spores and the stages of the life cycle in different media. In BAP medium, both strains showed approximately 18% spore germination. However, in BAP medium lacking micronutrients and FeEDTA, strain ChI1 spores exhibited approximately 53% germination and strain ReI6 spores about 42%. The survey also showed that the spores were not heat-resistant, the ReI6 spores being more sensitive than ChI1 spores. Both strains exhibited a small increase in their percentage of germination with a 15-pulse ultrasonic treatment.     

Sur la culture des spores et le développement du thalle de Botryocladia chiajeana (Menegh.) Kylin (Rhodyméniales,Rhodyméniacées)

Abstract

On the culture of spores and the development of the thallus of Botryocladia chiajeana (Menegh.) Kylin (Rhodymeniales, Rhodymeniaceae). - The complete development of Botryocladia chiajeana has been studied in culture. Spore germination and sporeling development is of the discalis mediatus type described by Inoh (1947). The hollow vesiculous branches filled with a mucilage derive from the spacing of the erect filaments which form the stipe. The authors compare this development of the thallus with that described for other Rhodymeniales.     

芽胞抗力快速弱化技术研究

以L-丙氨酸缓冲液为发芽剂,结合芬顿反应原理,观察发芽-氧化损伤效应对芽胞的杀灭效果,以期为新型炭疽疫源地净化方法的深入研究奠定基础。以腊样芽胞为试验菌,采用透射电镜、激光扫描共聚焦显微镜、活菌计数等方法观察芽胞发芽过程的超微结构、核酸含量变化,以及在芬顿反应的联合作用下发芽体的活性变化。在20~30 min的发芽过程中,芽胞核心密度降低,核心与皮质、皮质与外壁之间界限模糊,芽胞外壁和芽胞衣有破裂,通透性增加,进一步有皮质消失、细胞核与细胞质融合、细胞膜基本形成的现象;发芽体荧光强度不断增加,显示菌体中核酸的活性和含量不断增加;发芽体对化学因子的抗力明显下降,H2O2浓度为0.20 mol/L的Fenton反应系统作用60 min时,发芽体灭活可达到3.016个对数级。诱导发芽和反应的联合处理程序可显著提高芽胞的灭活水平。     

Dictyostelium development-socializing through cAMP

Starving Dictyostelium amoebae use cAMP as a chemoattractant to gather into aggregates, as a hormone-like signal to induce cell differentiation, and as an intracellular messenger to control stalk- and spore cell maturation and germination of spores. In this chapter we describe the respective roles of the three adenylyl cyclases ACA, ACB and ACG in controlling cAMP signaling during development and we discuss how cAMP signals are processed by the cells to trigger the large repertoire of gene regulatory events that is under control of this signal molecule.     

Interactions between a salt marsh native perennial (Salicornia virginica) and an exotic annual (Polypogon monspeliensis) under varied salinity and hydroperiod

An exotic grass invades salt marshes of southern California in very wet years and where there are sewage spills or urban runoff. A series of growth-chamber, mesocosm, and greenhouse experiments explored whether soil salinity and/or waterlogging could explain invasion patterns. In all experiments, salinity significantly affected the growth and distribution of Polypogon monspeliensis (rabbit-foot grass, an exotic annual grass) and Salicornia virginica (pickleweed, a native perennial succulent). High salinities caused a greater reduction in seed germination rates for P. monspeliensis than for S. virginica, indicating that high salinity limits establishment and the spread of this exotic grass. At Tijuana Estuary, fresh water inputs to tidal mesocosms lowered soil salinities, increased cover of P. monspeliensis, and decreased cover of S. virginica. Polypogon monspeliensis outcompeted S. virginica under all salinity and hydrology treatments in the greenhouse experiment. Seasonally-low soil salinities caused by winter runoff and anthropogenic fresh water inputs are the likely factors controlling annual variations in the distribution of P. monspeliensis in southern California salt marshes. Our understanding of the causes of invasion is readily applicable to management: local invasions may be reversed by adding salt, and larger scale problems could be avoided by reinstating more natural hydrologic regimes.