阔叶鳞盖蕨和粗毛鳞盖蕨(碗蕨科)配子体发育的研究

以腐殖土为基质,对阔叶鳞盖蕨Microlepia patyphylla（D．Don）J．Sm．和粗毛鳞盖蕨M.strigosa（Thunb．）Presl进行了孢子繁殖;利用光学显微镜观察和记录了它们的孢子萌发和配子体发育过程。结果表明,两者的孢子及配子体性状极为相似：孢子同型,三裂缝,萌发慢;孢子萌发需要光,萌发方式为书带蕨型Vittaria-type;配子体生长慢,发育类型为铁线蕨型Adiantum—type;原叶体心形或其他形状,无毛状体,多数为雌雄异株。性器类型为薄囊蕨型Leptosporangiate-type。它们既具有大量的原始性状,也具有少数进化性状。与阔叶鳞盖蕨相比,粗毛鳞盖蕨的配子体发育特征更为原始。说明粗己鳞盖蕨的系统位置更加低下。首次观察到阔叶鳞盖蕨中细胞自然死亡时的叶绿体聚集现象。粗毛鳞盖蕨原叶体老化时叶绿体呈现规则的、相互镶嵌的多边形的形状以及在正常光照下粗毛鳞盖蕨某些细胞中的部分叶绿体成链珠状排列等现象。     

Localization of fluorescent substances in the cellular slime moldDictyostelium discoideum cells during growth and development

The localization of fluorescent substance was observed microscopically in livingDictyostelium discoideum cells. The fluorescence was localized in the vacuoles of the vegetative cells. The fluorescent vacuoles were not observed in the dead cells. The fluorescent vacuoles in the cytoplasm were lost in starved cells which are able to form an aggregate and to differentiate. The fluorescent vacuoles were not lost but decreased slightly in the cytoplasm of full grown cells and of cells grown in liquid nutrient medium for an extended period of time (stationary phase cells). On a solid substratum, fluorescent vacuoles were also lost from the cells, where the vegetative cells aggregate and form a slug-shaped mass of cells. The whole slug showed homogeneous fluorescence. In a finally constructed fruiting body, the spore mass showed fluorescence. In a spore mass, the fluorescence was not observed in the spores but in the interspore space of the spore mass. It is suggested that vegetative cells secrete fluorescent substance into the inter-cellular space in the mass of cells during development.     

The measurement of Bacillus mycoides spore adhesion using atomic force microscopy,simple counting methods,and a spinning disk technique

An atomic force microscope has been used to study the adhesion of Bacillus mycoides spores to a hydrophilic glass surface and a hydrophobic-coated glass surface. AFM images of spores attached to the hydrophobic-coated mica surface allowed the measurement of spore dimensions in an aqueous environment without desiccation. The spore exosporium was observed to be flexible and to promote the adhesion of the spore by increasing the area of spore contact with the surface. Results from counting procedures using light microscopy matched the density of spores observed on the hydrophobic-coated glass surface with AFM. However, no spores were observed on the hydrophilic glass surface with AFM, a consequence of the weaker adhesion of the spores at this surface. AFM was also used to quantify directly the interactions of B. mycoides spores at the two surfaces in an aqueous environment. The measurements used "spore probes" constructed by immobilizing a single spore at the apex of a tipless AFM cantilever. The data showed that stretching and sequential bond breaking occurred as the spores were retracted from the hydrophilic glass surface. The greatest spore adhesion was measured at the hydrophobic-coated glass surface. An attractive force on the spores was measured as the spores approached the hydrophobic-coated surface. At the hydrophilic glass surface, only repulsive forces were measured during the approach of the spores. The AFM force measurements were in qualitative agreement with the results of a hydrodynamic shear adhesion assay that used a spinning disk technique. Quantitatively, AFM measurements of adhesive force were up to 4 x 10(3) times larger than the estimates made using the spinning disk data. This is a consequence of the different types of forces applied to the spore in the different adhesion assays. AFM has provided some unique insights into the interactions of spores with surfaces. No other instrument can make such direct measurements for single microbiological cells.     

Phosphorylation and methylation of proteins during Myxococcus xanthus spore formation

Post-translational modification of proteins was examined during the life cycle of Myxococcus xanthus. A specific pattern of protein phosphorylation was observed in vegetative cells. When spore formation was induced by glycerol, significant changes in the pattern of protein phosphorylation were observed, including the phosphorylation of two membrane proteins. In in vitro experiments, the same membrane proteins were phosphorylated by ATP when the membrane preparation from cells treated with glycerol was used. Changes in the pattern of protein methylation were also observed during spore formation induced by glycerol or fruiting body formation. These results suggest that post-translational protein modification may be required for spore formation or fruiting body formation.     

Patterns of Protein Production in Myxococcus xanthus During Spore Formation Induced by Glycerol, Dimethyl Sulfoxide, and Phenethyl Alcohol

Spore formation of Myxococcus xanthus can occur not only on agar plates during fruiting body formation, but also in a liquid culture by simply adding glycerol, dimethyl sulfoxide, or phenethyl alcohol to the culture. This chemically-induced spore formation occurs synchronously and much faster than that occurring during fruiting body formation. Dramatic changes in patterns of protein synthesis were observed during chemically-induced spore formation, as had previously been observed during fruiting body formation (Inouye et al., Dev. Biol. 68:579-591, 1979). However, the production of protein S, one of the major development-specific proteins during fruiting body formation, was not detected at all, although protein U, another development-specific protein, was produced in a late stage of spore formation as in the case of fruiting body formation. This indicates that the control of the gene expression during chemically-induced spore formation is significantly different from that during fruiting body formation. It was also found that during spore formation, every cell seems to have a potential to form a spore regardless of its age, since smaller cells as well as larger cells separated by sucrose density gradient centrifugation could equally form spores upon the addition of glycerol. Patterns of protein synthesis were almost identical for all the three chemicals. However, the final yield of spores was significantly different depending upon the chemicals used. When phenethyl alcohol was added with glycerol or dimethyl sulfoxide, the final yields were determined by the multiple effect of the two chemicals added. This suggests that although these chemicals are able to induce the gene functions required for spore formation, they may have inhibitory effects on some of the gene functions or the processes of spore formation.     

Sporulation in Bacillus subtilis. Antigenic changes during spore formation

1. Antisera, prepared against extracts of cells and spores of Bacillus subtilis, were used in immunoelectrophoretic studies of the changes occurring in cell extracts during the course of spore formation. 2. At least 15 antigens could be detected in vegetative-cell extracts by the antiserum prepared against cell extracts and at least seven could be demonstrated in spore extracts by the homologous antiserum. 3. Cross-absorption studies showed that two of these antigens were probably completely specific for vegetative-cell extracts and that one was probably completely specific for spore extracts. The remainder were probably present in very small quantities in the heterologous extract. 4. In extracts of cells sporulating in an ;exhaustion medium' those antigens characteristic of the spore began to appear about 1hr. after the end of exponential growth. 5. In cells sporulating in a resuspension medium, spore antigens were detected at 4hr., and by 7hr. a decrease in vegetative-cell antigens was observed. 6. In an asporogenous mutant blocked early in sporulation there was neither an increase in spore antigens nor a decrease in vegetative-cell antigens. 7. In an asporogenous mutant blocked later in sporulation, there was an increase in spore antigens similar to that which occurred in the sporogenous strain.     

Scanning electron microscope observations on the spore of Nosema apis Zander

A simple Epon block fracture technique was used to process spores of Nosema apis for scanning clectron microscope examination. The mature spore was egg-shaped with a pointed anterior pole. The young spore was more elongated. The surface of both stages was smooth. A large number of midgut epithelial cells which harbour N. apis were also observed. The cell surfaces of the epithelial cells were also smooth.     

Changes in the hydrophobic characteristics of Clostridium perfringens spores and spore coats by heat

The hydrophobic characteristics of Clostridium perfringens NCTC 8679 spores were demonstrated by adherence to toluene in a toluene-aqueous partition system. Spores and spore coat preparations were hydrophobic. Vegetative cells and spores extracted with a dithiothreitol-sodium dodecyl sulfate treatment known to remove spore coats were not hydrophobic. A heat activation treatment (75 degrees C for 20 min) which promotes more rapid spore germination increased the hydrophobicity of intact spores and decreased that of isolated spore coats. The hydrophobic changes were reversed by washing and stabilized by 0.5% glutaraldehyde. Heat-induced hydrophobic changes were observed in spore coats prepared from spores that were preheated and washed before rupturing in a buffer containing glutaraldehyde. These results suggest the occurrence of a heat-induced change in the spore coat (possibly in the conformation of a macromolecule) which was stable only within the architectural confines of the intact spore.     

Effects of Fumidil B on the spore of Nosema apis and on lipids of the host cell as revealed by freeze-etching

The epithelial cells of the midgut of honey bees, Apis mellifera, infected with Nosema apis showed young and mature spores randomly distributed in the cytoplasm. In these cells, only mitochondria and protein granules were observed. After treating infected bees with Fumidil B, an ultrastructural alteration in the spore membrane, especially in the young spore, was observed. At the same time, lipid granules appeared in the cytoplasm, mostly around the spores. The number of protein granules also increased.     

Sporulation in Bacillus subtilis. Morphological changes

1. When Bacillus subtilis was grown in a medium in which sporulation occurred well-defined morphological changes were seen in thin sections of the cells. 2. Over a period of 7.5hr. beginning 2hr. after the initiation of sporulation the following major stages were observed: axial nuclear-filament formation, spore-septum formation, release of the fore-spore within the cell, development of the cortex around the fore-spore, the laying down of the spore coat and the completion of the corrugated spore coat before release of the spore from the mother cell. 3. The appearance of refractile bodies and 2,6-dipicolinic acid and the development of heat-resistance began between 5 and 6.5hr. after initiation of sporulation. 4. The appearance of 2,6-dipicolinic acid and the onset of refractility appeared to coincide with a diminution of electron density in the spore core and cortex. 5. Heat-resistance was associated with the terminal stage, the completion of the spore coat. 6. The spore coat was composed of an inner and an outer layer, each of which consisted of three or four electron-dense laminae. 7. Serial sections through cells at an early stage of sporulation showed that the membranes of each spore septum were always continuous with the membranes of a mesosome, which was itself in close contact with the bacterial or spore nucleoid. 8. These changes were correlated with biochemical events occurring during sporulation.     

Germination response of spores of the pathogenic bacterium Clostridium perfringens and Clostridium difficile to cultured human epithelial cells

Spores of pathogenic Clostridium perfringens and Clostridium difficile must germinate in the food vehicle and/or host's intestinal tract to cause disease. In this work, we examined the germination response of spores of C. perfringens and C. difficile upon incubation with cultured human epithelial cell lines (Caco-2, HeLa and HT-29). C. perfringens spores of various sources were able to germinate to different extents; while spores of a non-food-borne isolate germinated very well, spores of food-borne and animal isolates germinated poorly in human epithelial cells. In contrast, no detectable spore germination (i.e., loss of spore heat resistance) was observed upon incubation of C. difficile spores with epithelial cells; instead, there was a significant (p?相似文献   

Incorporation of Glycine and Serine into Sporulating Cells of Bacillus subtilis

The changes during growth and sporulation in activities of cells of Bacillus subtilis to incorporate various amino acids were investigated with wild-type strain and its asporogenous mutant. In the case of wild type strain the uptake of valine, phenylalanine, and proline was largest during the logarithmic growth period. The uptake of these amino acids decreased rapidly during the early stationary phase. The uptake of valine and cysteine increased again to some extent just prior to the forespore stage. The uptake of glycine and serine, however, was largest at the forespore stage at which the formation of spore coat took place. From these observed phenomena it was assumed that the remarkable incorporation of glycine and serine into the wild type strain during sporulation was closely related to the formation of spore coat.     

GIBBERELLIC ACID-INDUCED GERMINATION OF SPORES OF ANEMIA PHYLLITIDIS: NUCLEIC ACID AND PROTEIN SYNTHESIS DURING GERMINATION

The distribution and synthesis of nucleic acids and proteins during gibberellic acid-induced germination of spores of Anemia phyllitidis were studied in order to relate biochemical activity with morphogenetic aspects of germination. Germination is accompanied by the hydrolysis of storage protein granules and the localized appearance of cytoplasmic RNA, protein, and insoluble carbohydrates in a small area adjoining the spore wall and surrounding the nucleus. The protoplast of the spore enlarges in this region, the spore wall breaks and a protonemal cell is formed which contains many chloroplasts. A second division in the spore at right angles to the first yields a rhizoid cell. Autoradiography of ³H-thymidine incorporation has shown that DNA is synthesized both in the nucleus and in the immediately surrounding cytoplasm of the germinating spore until some time after the first division, although a strictly nuclear DNA synthesis is observed later. Synthesis of RNA and proteins is limited to the presumptive regions of the germinating spore which become the protonema and rhizoid, shifting to specific sites in these cells as germination proceeds. The nucleus of the spore continues to be biosynthetically active long after it ceases to divide.     

Presence of proteins derived from the vegetative cell membrane in the dormant spore coat of Bacillus subtilis

To confirm the presence of the outer spore membrane in dormant spore coats of Bacillus subtilis, the proteins from vegetative cell membrane and dormant spore coat fractions were compared by immunoblot assay with antibodies prepared against both preparations. The spore coat fraction contained at least 11 proteins antigenically identical to those in the vegetative cell membranes. Further, the cytochemical localization of the proteins derived from vegetative cell membrane in dormant spores was examined by an immunoelectron microscopy method with a colloidal gold-immunoglobulin G complex. The colloidal gold particles were observed in the coat region and around the core region of dormant spore. These results have provided evidence that some proteins from vegetative cell membrane remain in the dormant spore coat region of B. subtilis, although it is not clear whether the outer membrane persists as an intact functional entity or not.     

Gymnodinium helveticum Penard F. Achroum Skuja a case of phagotrophy

Gymnodinium helveticum f. achroum in Blelham Tarn was occasionally noted to exhibit phagotrophy. Various algae were observed inside Gymnodinium cells. The seeding of an experimental enclosure with dead Lycopodium spores resulted in some of the Gymnodinium cells containing a spore.

From the results, it is suggested that this dinoflagellate exhibits non-selective and non-predatory phagotrophy.     

苏铁蕨配子体发育的研究

用无机培养基培养苏铁蕨(Brainea insignis (Hook.)J.Sm.)的孢子,显微镜下观察记录其孢子萌发及配子体形态发育过程.结果表明:孢子褐色,单裂缝,具周壁,稍褶皱.接种3 d左右孢子萌发,萌发类型为书带蕨型(VittariaType),原叶体发育类型为槲蕨型(Drynaria Type).接种15 d左右发育为片状体.接种25 d左右发育为成熟原叶体,呈心形,其翼面和翼缘均分布有毛状体.精子器由3细胞构成,成熟颈卵器颈部由4列细胞组成,4～5层细胞高.     

Brefeldin A affects adhesion of zoospores of the green alga Enteromorpha.

Primary adhesion of zoospores of the green macroalga Enteromorpha to substrata involves a massive release of adhesive glycoproteins from Golgi-derived, membrane-bounded vesicles in the anterior region of the spore, followed by rapid curing. This process is sensitive to low concentrations (5-10 microg x ml(-1)) of the secretion-inhibiting antibiotic, brefeldin A (BFA). The proportion of cells that settled in BFA was reduced by approximately 50%, but the effect was fully reversed by washing in seawater to remove the BFA. Ultrastructural observations showed that BFA caused the breakdown of Golgi stacks in the majority of cells examined. When settled cells were subjected to shear stress, a greater proportion of those settled in the presence of BFA were detached, compared with controls, indicating reduced adhesion strength in the presence of the antibiotic. The most likely reason for this is that strong adhesion to substrata either requires the synthesis of extra adhesive materials beyond those present in the swimming spore, or the secretion of an additional component required for adhesive curing. The novel use of atomic force microscopy in force modulation mode demonstrated that the adhesive secreted by most spores in the presence of BFA did not undergo the rapid curing process typical of control spores. However, some variation between zoospores was observed, with some cells showing no ultrastructural changes and normal adhesive curing. These results are discussed in relation to variations observed in the propensity and competence of spores to settle, which may be reflected in differential requirements for de novo synthesis and secretion of materials needed for full adhesion.     

Immunological Homology Between Crystal and Spore Protein of Bacillus thuringiensis

Spore suspensions containing about 0.3% crystals and crystal suspensions containing about 0.1% spores were obtained from cultures of Bacillus thuringiensis by extraction with a two-phase system. Both preparations were tested for the presence of contaminating material from vegetative cells and were judged to be clean. Solutions of spore protein were obtained by extracting broken spores with phosphate buffer followed by extraction with either alkali- or urea-mercaptoethanol. The alkali spore or urea spore extracts had the same isoelectric point as crystal protein solubilized with these reagents. An antiserum prepared against alkali crystal solution precipitated alkali or urea spore extracts and crystal solutions but not phosphate spore extracts or extracts of whole cells. Lines of identity between spore and crystal precipitates were observed by using the Ouchterlony double-diffusion technique. Absorption of the antiserum with an excess of urea spore extract caused a disappearance of the precipitin bands originating from the spore protein and the homologous bands from the crystal protein. The results suggest that the crystal and endospore contain one or more common proteins.     

Light and electron microscopic observations of Leptotheca koreana n. sp. (Myxosporea) in the kidney of cultured rockfish Sebastes schlegeli.

The structure and sporogenesis of Leptotheca koreana n. sp. from cultured rockfish Sebastes schlegeli from South Korea were studied by light and transmission electron microscopy. Broadly oval spores and disporous pseudoplasmodia were observed in the lumen of renal tubules. Spores were 8.59 +/- 1.25 microm in length, 13.42 +/- 1.0 microm in width in sutural view and 8.13 +/- 0.52 pm in thickness in the plane perpendicular to the suture. The width of each valve was always smaller than spore length. Two spherical polar capsules were equal in size (3.86 +/- 0.45 microm in diameter) containing a polar filament with 6 to 7 turns, opening at the anterior end of the spore. Two uninucleate sporoplasms filled the spore cavity. The asynchronous division of secondary and tertiary cells and asynchronous development in spore formation of the present Leptotheca koreana resembled the disporous sphaerosporids. Cytoplasmic projections of pseudoplamodia were considered to be rhizoids, as they seem to strengthen the attachment to the epithelial cells of the renal tubules. The capsulogenic cells in early sporoblast had large amounts of rough endoplasmic reticulum but had a few Golgi apparatus.     

Monterey Bay Phytoplankton. II. Resting Spore Cycles in Coastal Diatom Populations

The purpose of this study is to examine the role of "restingspores" in natural population cycles of temperature, neriticdiatoms. Resting spores are a conspicuous element of centricdiatom populations in most neritic and some deep-water environmentsof the world oceans. Until recently the spores have been accepted,almost axiomatically, as surviving as a seasonal benthic stagewhich reinoculate the water column at the onset of favorablegrowth conditions. Data to support this hypothesis, however,is limited and contradictory. In my study, I am examining theoccurrence of resting spores in relation to vegetative cellcycles and oceanographic conditions in Monterey Bay, California,a nearshore upwelling-dominated system. I have utilized samplesfrom the water column, from settling-tubes, and from sedimentcores to document the cycles. Resting spore cycles were observed for many neritic species,and spore cycles for abundant species were considered in detail.Resting spore formation was associated with low nitrate concentrationsin surface waters. After spore formation in the water columnspores were found in settling-tubes and in sediment samples.Spore formation was a frequent event and spores were often presentin the water column and in the sediments. Observations of spore cycles in the present study were consistentwith the prevailing idea that resting spores function as benthicresting stages in coastal populations. The pelagic retentionand/or dispersal in coastal circulation cells, however, alsoappeared to be highly likely. The study has demonstrated thepotential for resting spores to function as survival stagesin Monterey Bay and in other regions with similar hydrographicconditions. The present evidence regarding the role of restingspores suggests that resting spores may have a wide range offunctions, and a more inclusive (or alternate) resting sporehypothesis is suggested.