Reversible Inhibition of Spore Germination by Alcohols

Low levels of alcohols have been found to inhibit the process of spore germination. The extent of germination is dependent upon the concentration of alcohol present in the germinating medium. This inhibition is reversible since removal of the alcohol from the spore environment allows germination to proceed.     

Factors Influencing Spore Germination and Early Gametophyte Development in Anemia mexicana and Anemia phyllitidis

Spores of Anemia mexicana Klotzsch and Anemia phyllitidis (L.) Swartz were tested comparatively to investigate the effects of various treatments on spore germination and early gametophyte development in light and darkness. The optimum pH for induction of spore germination is approximately 6. Both species have a minimum 8 hour light insensitive preinduction phase for spore germination. An additional 8 to 12 hours of light are needed to induce 50% germination in A. phyllitidis while at least 24 hours of light are needed for A. mexicana spores. A. phyllitidis has greater sensitivity to the four gibberellic acids tested (GA₃, GA₄, GA₇, and GA₁₃) than A. mexicana for induction of spore germination in darkness. In both species the greatest response was observed with GA₄ and GA₇. GA₁₃ was clearly the least effective. Gametophytes of each species are 100 times more sensitive to their own antheridiogen than to the antheridiogen of the other species. AMO-1618 (1 millimolar), fenarimol (1 mm), and ancymidol (0.1 mm) had essentially no effect on light-induced germination. The latter two did, however, inhibit gametophyte development.     

Inhibition of Spore Germination in the Cellular Slime Moulds

The phenomenon of auto-inhibition of spore germination has beendemonstrated in the slime moulds Dictyostelium purpureum, strainno. 2; Dictyostelium discoideum, strain no. 1; Dictyosteliummucoroides, strain no. 2; and Polysphondy-Iium violeceum, strainno. 6. A water-soluble substance present in spores was shownto cause this self-inhibition. The substance was isolated fromeach species studied. Evidence as presented indicates that thesame substance occurs in each species of Dictyostelium, butthat it differs from that found in Pv6. An attempt was alsomade to relate this inhibitory substance to the phenomenon of'differential inhibition' in Dp2, Dd, Dm2, and Pu6. An explanationbased on evidence for differential sensitivity to a common inhibitorof spore germination in Dictyostelium and an inhibition in otherthan the spore stage in Pu6 is presented. Apparent differentialproduction of a common inhibitor in Dictyostelium is also reported.     

Ribosomal Ribonucleic Acid Maturation During Bacterial Spore Germination

All the ribosomal ribonucleic acid made during the early stages of germination of spores of Bacillus subtilis is of the "precursor" type, i.e., that type appearing in the incomplete forms of the ribosome. Shortly before the onset of deoxyribonucleic acid synthesis in germination, this precursor ribonucleic acid changed to the mature ribosomal ribonucleic acid characteristic of the 30S and 50S ribosomal subunits.     

Factors Affecting Spore Germination of Volvariella volvacea

Environmental factors affecting basidiospore germination were studied with Volvariella volvacea, the edible straw mushroom which is common in South East Asia. A relatively mild heal shock is necessary for spore germination. The spores give best germination at 40°C although early hyphal growth is better at 35°C the germination of spores is affected by temperature. pH. a presoaking treatment and spore density. Higher pH supports more germination but seems unfavourable for early mycelial growth. Presoaking treatment in phosphate buffer solution or distilled water also stimulates germination markedly.     

Deoxyribonucleic Acid Synthesis and Deoxynucleotide Metabolism During Bacterial Spore Germination

Deoxyribonucleic acid (DNA) synthesis during germination of Bacillus megaterium spores takes place in two stages. In stage I (0-55 min) DNA synthesis is slow and there is no detectable net synthesis, whereas in stage II (from 55 min on) the rate of synthesis is much faster and net DNA synthesis occurs. Deoxyribonucleotide pool sizes match the rates of DNA synthesis in stages I and II. The level of deoxyribonucleotide triphosphates is not correlated with the level of deoxyribonucleotide kinases, but rather with that of ribonucleotide reductase activity.     

Modeling of Fungal and Bacterial Spore Germination under Static and Dynamic Conditions

Isothermal germination curves, sigmoid and nonsigmoid, can be described by a variety of models reminiscent of growth models. Two of these, which are consistent with the percent of germinated spores being initially zero, were selected: one, Weibullian (or “stretched exponential”), for more or less symmetric curves, and the other, introduced by Dantigny''s group, for asymmetric curves (P. Dantigny, S. P.-M. Nanguy, D. Judet-Correia, and M. Bensoussan, Int. J. Food Microbiol. 146:176–181, 2011). These static models were converted into differential rate models to simulate dynamic germination patterns, which passed a test for consistency. In principle, these and similar models, if validated experimentally, could be used to predict dynamic germination from isothermal data. The procedures to generate both isothermal and dynamic germination curves have been automated and posted as freeware on the Internet in the form of interactive Wolfram demonstrations. A fully stochastic model of individual and small groups of spores, developed in parallel, shows that when the germination probability is constant from the start, the germination curve is nonsigmoid. It becomes sigmoid if the probability monotonically rises from zero. If the probability rate function rises and then falls, the germination reaches an asymptotic level determined by the peak''s location and height. As the number of individual spores rises, the germination curve of their assemblies becomes smoother. It also becomes more deterministic and can be described by the empirical phenomenological models.     

Factors Affecting the Rate of Heat-induced Spore Germination in Dictyostelium discoideum

Washed spores of Dictyostelium discoideum, strains NC-4H, NC-4D, and V-12, germinated rapidly after being heat shocked at or near 45.0 C for 30 min. Cultures of the slime molds were grown in association with Escherichia coli B/r as the host bacterium; spores taken from plates of synthetic medium had a higher final germination value than spores from complex medium containing peptone and yeast extract. Young spores germinated more rapidly than older spores. Optimal germination occurred between pH 6.0 and 7.0, and, of the buffers tested, potassium phosphate allowed the most rapid germination. After heat shocking, spores were diluted into fresh oxygenated buffer to provide enough oxygen for completion of germination. Germination occurred most rapidly between incubation temperatures of 22 and 25 C.     

Analysis of the Dynamics of a Bacillus subtilis Spore Germination Protein Complex during Spore Germination and Outgrowth

Germination of Bacillus subtilis spores is normally initiated when nutrients from the environment interact with germinant receptors (GRs) in the spores'' inner membrane (IM), in which most of the lipids are immobile. GRs and another germination protein, GerD, colocalize in the IM of dormant spores in a small focus termed the “germinosome,” and this colocalization or focus formation is dependent upon GerD, which is also essential for rapid GR-dependent spore germination. To determine the fate of the germinosome and germination proteins during spore germination and outgrowth, we employed differential interference microscopy and epifluorescence microscopy to track germinating spores with fluorescent fusions to germination proteins and used Western blot analyses to measure germination protein levels. We found that after initiation of spore germination, the germinosome foci ultimately changed into larger disperse patterns, with ≥75% of spore populations displaying this pattern in spores germinated for 1 h, although >80% of spores germinated for 30 min retained the germinosome foci. Western blot analysis revealed that levels of GR proteins and the SpoVA proteins essential for dipicolinic acid release changed minimally during this period, although GerD levels decreased ∼50% within 15 min in germinated spores. Since the dispersion of the germinosome during germination was slower than the decrease in GerD levels, either germinosome stability is not compromised by ∼2-fold decreases in GerD levels or other factors, such as restoration of rapid IM lipid mobility, are also significant in germinosome dispersion as spore germination proceeds.     

环境因子对中华双扇蕨孢子萌发的影响

为了解珍稀濒危植物中华双扇蕨(Dipteris chinensis)濒危原因,研究了温度和湿度对其孢子萌发的影响.结果表明,中华双扇蕨孢子萌发能力较强,萌发方式为Vittaria型,配子体萌发为Marattia型.中华双扇蕨孢子繁殖不受温度影响,而湿度显著影响孢子繁殖过程,湿润环境中孢子正常萌发,并形成心形配子体,顺利...     

Effects of Anaerobiosis and Respiratory Inhibitors on Blue-Light Inhibition of Spore Germination in Pteris vittata

In a fern, Pteris vittata, inhibition by low-energy blue lightof phytochrome-dependent spore germination was counteractedby anerobiosis and respiratory inhibitors, such as KCN and NaN₃.A 50% inhibition of spore germination in a medium containing0.3 mM NaN₃ required about 8 times longer duration of blue lightirradiation compared with the control. The counteracting effectof NaN₃ continued for about 32 hr after withdrawal of the inhibitor.However, NaN₃ neither induced dark germination nor counteractedthe far-red light inhibition of spore germination. Reducingagents and uncouplers were tested and dithionite and arsenateslightly reversed the blue light inhibition of spore germination. (Received December 17, 1981; Accepted July 8, 1982)     

Infection of Tribolium castaneum with Bacillus thuringiensis: Quantification of Bacterial Replication within Cadavers,Transmission via Cannibalism,and Inhibition of Spore Germination

Reproduction within a host and transmission to the next host are crucial for the virulence and fitness of pathogens. Nevertheless, basic knowledge about such parameters is often missing from the literature, even for well-studied bacteria, such as Bacillus thuringiensis, an endospore-forming insect pathogen, which infects its hosts via the oral route. To characterize bacterial replication success, we made use of an experimental oral infection system for the red flour beetle Tribolium castaneum and developed a flow cytometric assay for the quantification of both spore ingestion by the individual beetle larvae and the resulting spore load after bacterial replication and resporulation within cadavers. On average, spore numbers increased 460-fold, showing that Bacillus thuringiensis grows and replicates successfully in insect cadavers. By inoculating cadaver-derived spores and spores from bacterial stock cultures into nutrient medium, we next investigated outgrowth characteristics of vegetative cells and found that cadaver-derived bacteria showed reduced growth compared to bacteria from the stock cultures. Interestingly, this reduced growth was a consequence of inhibited spore germination, probably originating from the host and resulting in reduced host mortality in subsequent infections by cadaver-derived spores. Nevertheless, we further showed that Bacillus thuringiensis transmission was possible via larval cannibalism when no other food was offered. These results contribute to our understanding of the ecology of Bacillus thuringiensis as an insect pathogen.     

东北刺人参种子萌发影响因子的研究

东北刺人参(Oplopanax elatus Nakai)种子透水性良好,休眠后萌发不受其影响.种皮和胚乳的水提取物中存在萌发抑制物质,胚乳中提取物对白菜种子萌发的抑制效果比种皮更明显.种子自然脱落时胚尚未分化完全,处于心形胚阶段.种子需要先温暖层积以完成胚的分化与生长,然后转入低温层积完成生理后熟.同批种子胚的发育不完全同步,变温层积处理7个月有极少数种子萌发,连续变温层积处理17个月大部分种子萌发.不同年份受气候条件影响,种子产量和发芽率差异较大.种子耐贮性较强,贮藏2年的种子生活力变化不大,仍具有较高的萌发潜力.     

东北刺人参种子萌发影响因子的研究

东北刺人参(Oplopanax elatus Nakai)种子透水性良好,休眠后萌发不受其影响。种皮和胚乳的水提取物中存在萌发抑制物质,胚乳中提取物对白菜种子萌发的抑制效果比种皮更明显。种子自然脱落时胚尚未分化完全,处于心形胚阶段。种子需要先温暖层积以完成胚的分化与生长,然后转入低温层积完成生理后熟。同批种子胚的发育不完全同步,变温层积处理7个月有极少数种子萌发,连续变温层积处理17个月大部分种子萌发。不同年份受气候条件影响,种子产量和发芽率差异较大。种子耐贮性较强,贮藏2年的种子生活力变化不大,仍具有较高的萌发潜力。     

Studies on the Bacterial Spore Coat

Properties of alkali-soluble components from the spore coat of Bacillus megaterium were examined by physicochemical methods. They were composed of acidic polypeptides of various molecular weights with small amounts of phosphorus and sugar. They were allowed to dissociate to unit components by incubation with SDS. The major component was partially purified by gel filtration, and shown to have a mean molecular weight of about 11,000.     

Action Spectrum between 250 and 800 Nanometers for the Photoinduced Inhibition of Spore Germination in Pteris vittata

An action spectrum between 250 and 800 nm for the inhibitionof red-light-induced germination of spores in the fern Pterisvittata was determined on the Okazaki Large Spectrograph. Theresultant spectrum showed prominent peaks of effectiveness atabout 370, 440 and 730 nm and a minor peak in the neighborhoodof 260 nm. Next, a brief red light irradiation was given immediatelyafter the monochromatic irradiation to cancel the inhibitoryeffect caused by simultaneously formed P_R. This resulted ina complete disappearance of the peak at 730 nm and considerabledecrease of other peaks in the shorter wavelength region exceptat 260 nm. Further correction of the latter spectrum by consideringthe transmission spectrum of a spore coat revealed that 260nm light acted more effectively than lights of 370 and 440 nm.The inhibitory effect of UV light on spore germination was nullifiedby subsequent irradiation with red light for 24 h or darknessfor 48 h followed by a brief red irradiation, indicating thatthe inhibitory action of UV light was ascribable to a blue-ultraviolet light-absorbing pigment. ⁴Present address (KT) and permanent address (MF): Botany Department,Faculty of Science, University of Tokyo, Hongo, Tokyo 113, Japan. (Received July 30, 1983; Accepted November 21, 1983)     

Gamma-Ray-Induced Spore Germination of Dictyostelium discoideum

⁶⁰Co gamma rays can induce germination of the spores of the cellular slime mold, Dictyostelium discoideum, in the absence of heat shock, amino acids, or bacteria food source. About 65% amoebae emergence occurs by 13 hr after a dose of 180 krad.