CO-REQUIREMENT FOR CALCIUM AND POTASSIUM IN THE GERMINATION OF SPORES OF THE FERN ONOCLEA SENSIBILIS

Spores of Onoclea sensibilis L. do not germinate on distilled H₂O if they are pretreated for sufficient time with dilute NaClO solution. However, spores will germinate, after NaClO pretreatment, on a simple mineral medium containing the major and trace elements. Complete germination after pretreatment also is obtained on a solution containing only Ca²⁺ and K⁺ as the cations, but neither ion by itself is sufficient. Rb⁺, but not Li⁺ or Na⁺, can replace K⁺. Hypochlorite-treated spores do not require the continuous presence of Ca²⁺ and K⁺ to germinate; exposure during the first 4 hr of culture, with the remainder of the time on distilled H₂O, is sufficient. Extraction of spores with ethylene glycol bis(aminoethyl ether) tetraacetic acid [EGTA] makes their germination dependent on Ca²⁺, as reported by other workers, but it does not produce a co-requirement for K⁺. Colorimetric analysis with arsenazo III confirms that Ca²⁺ is extracted from Onoclea spores by NaClO. Extractable Ca²⁺ amounts to about 78 nmol/mg spore dry wt. Of this amount, 31% is contained in the perispore. The perispore comprises 13% of the total spore dry wt.     

STORAGE PRODUCTS IN SPORES OF ONOCLEA SENSIBILIS L

Lipids and proteins in substantial quantities are present as storage products in spores of Onoclea sensibilis. They fill the sparce spore cytoplasm and ultrastructurally are indistinguishable from reserve materials observed in storage tissue of higher plants. Hydrolysis of both products is correlated with early stages in spore germination.     

DETERMINATION OF RHIZOID ORIENTATION BY LIGHT AND DARKNESS IN GERMINATING SPORES OF ONOCLEA SENSIBILIS

When spores of the fern, Onoclea sensibilis L., are allowed to germinate in darkness, the rhizoid and the protonema are positioned at close to a right angle. If the spores are exposed initially to light and allowed to germinate, the rhizoid and protonema are positioned nearly axially, at opposite ends of the spore. The greater the duration and intensity of the initial illumination, the greater the tendency towards axial arrangement. All colors of light are active to some degree, and the effects are intensity-dependent. The response occurs in a uniform light field and is not dependent on a directional stimulus; the phenomenon reflects the relative arrangement of one part of the gametophyte to another part but not the orientation of growth with respect to an external stimulus. Direct tests show that neither the relative rhizoid orientation nor initial polarity of germination are affected by unilateral white light or polarized red light; the subsequent growth of the protonema, however, is oriented perpendicular to the plane of light polarization. The effects of light in determining the positional relationship between rhizoid and protonema are interpreted in terms of a hypothesis proposing light-induced changes in the structure and mechanical properties of the spore wall.     

NUCLEAR MIGRATION IN GERMINATING SPORES OF ONOCLEA SENSIBILIS: THE PATH AND KINETICS OF MOVEMENT

Nuclear migration was observed in individual germinating spores of Onoclea sensibilis from the onset of movement to the completion of mitosis. About 16 hr after the initiation of germination, the nucleus migrated from its initial position in the center of the spore to the proximal side. It then appeared to migrate along the raphe to one end of the spore where an asymmetric division occurred. The average velocity of migration was measured at 0.256 ± 0.065 μm/min. During migration the nucleus underwent changes in shape. No migrations or movement other than that by the nucleus were observed.     

THE EFFECT OF METHANOL ON SPORE GERMINATION AND RHIZOID DIFFERENTIATION IN ONOCLEA SENSIBILIS

In germinating spores of Onoclea sensibilis, the nucleus migrates to one end prior to an asymmetric cell division that partitions each spore into two daughter cells of unequal size. The larger cell develops into a protonema, whereas the smaller cell immediately differentiates into a rhizoid. When spores were germinated in the presence of methanol, nuclear migration was inhibited and most nuclei moved only to the raphe on the proximal side of the spores. Subsequent cell division partitioned each spore into daughter cells of equal size of which both developed into a protonema and neither into a rhizoid. Spores became sensitive to methanol at a time just prior to or coincident with nuclear migration and the effects of the alcohol were rapidly reversible as long as the spores were removed from methanol prior to the completion of cell division. Exposure to methanol prior to, but not during, nuclear migration or after mitosis had no effect upon rhizoid differentiation. The alcohol disrupted the formation of crosswalls after mitosis and they were often convoluted and irregularly branched. These results are consistent with the interpretation that methanol may disrupt a membrane site that plays an essential role in nuclear movement and rhizoid differentiation.     

缩球囊霉孢子萌发及细胞核在孢子和芽管中分布的研究*

本文研究了从本校分离的丛枝菌根真菌缩球囊霉Glomus constrictum的孢子萌发和萌发孢子的细胞核DAPI(46-diamidino-2-phenylindol)染色。结果显示,G. constrictum孢子直径为179.5-198.7μm ,顶生于产孢菌丝上。经表面消毒处理后,孢子在水琼脂平板上7天开始萌发。DAPI染色后,经稀释荧光计数,单个孢子细胞核数目约为5300,在孢子中无序分布, 细胞核直径约为9.9-11.2μm 。孢子萌发过程中,细胞核总数无明显变化,只是部分细胞核从孢子流向了萌发伸长的菌丝。     

球囊霉属几种AM真菌孢子表面消毒与萌发的研究

通过对球囊霉属几种AM真菌进行孢子表面消毒与萌发研究,结果表明,采用差别灭菌法即先用含2%氯胺T、0.02%链霉素和0.01%庆大霉素的溶液孢子表面消毒10min,然后在25～27℃下培养3天,再用含2%氯胺T、0.02%链霉素和0.01%庆大霉素的溶液孢子表面消毒10min,其消毒效果最好,孢子萌发率较高,污染率较低.同时发现土壤、草炭和寄主植物根的分泌物对孢子萌发有促进作用.培养基pH值的变化对孢子萌发也有一定的影响.AM真菌孢子用改良Sandwich法进行萌发,其萌发率最高.     

球囊霉属几种AM真菌孢子表面消毒与萌发的研究*

通过对球囊霉属几种AM真菌进行孢子表面消毒与萌发研究,结果表明,采用“差别灭菌法”即先用含2%氯胺T、0.02%链霉素和0.01%庆大霉素的溶液孢子表面消毒10min,然后在25~27℃下培养3天,再用含2%氯胺T、0.02%链霉素和0.01%庆大霉素的溶液孢子表面消毒10min,其消毒效果最好,孢子萌发率较高,污染率较低。同时发现土壤、草炭和寄主植物根的分泌物对孢子萌发有促进作用。培养基pH值的变化对孢子萌发也有一定的影响。AM真菌孢子用“改良Sandwich法”进行萌发,其萌发率最高。     

REVERSIBLE ACTIVATION FOR GERMINATION AND SUBSEQUENT CHANGES IN BACTERIAL SPORES

Lee, W. H. (University of Illinois, Urbana) and Z. John Ordal. Reversible activation for germination and subsequent changes in bacterial spores. J. Bacteriol. 85:207-217. 1963.-It was possible to isolate refractile spores of Bacillus megaterium, from a calcium dipicolinate germination solution, that were activated and would germinate spontaneously in distilled water. Some of the characteristics of the initial phases of bacterial spore germination were determined by studying these unstable activated spores. Activated spores of B. megaterium were resistant to stains and possessed a heat resistance intermediate between that of dormant and of germinated spores. The spontaneous germination of activated spores was inhibited by copper, iron, silver, or mercury salts, saturated o-phenanthroline, or solutions having a low pH value, but not by many common inhibitors. These inhibitions could be partially or completely reversed by the addition of sodium dipicolinate. The activated spores could be deactivated and made similar to dormant spores by treatment with acid. Analyses of the exudates from the variously treated spore suspensions revealed that whatever inhibited the germination of activated spores also inhibited the release of spore material. The composition of the germination exudates was different than that of extracts of dormant spores. Although heavy suspensions of activated spores gradually became swollen and dark when suspended in solutions of o-phenanthroline or at pH 4, the materials released resembled those found in extracts of dormant spores rather than those of normal germination exudates.     

NUCLEAR MIGRATION AND ASYMMETRIC CELL DIVISION IN ONOCLEA SENSIBILIS SPORES: AN ULTRASTRUCTURAL AND CYTOCHEMICAL STUDY

A method of preparation for electron microscopy of fern spores in early stages of germination is presented. The cytochemistry and fine structure of Onoclea spores during the early stages of germination are described. The cytoplasm of the hydrated spore is filled with lipid droplets, protein granules and chloroplasts. During the early stages of development ribosomes and mitochondria increase in the area surrounding the central nucleus, and a new peripheral wall forms around the protoplast. Microtubules and large, branching mitochondria are associated with the nucleus during migration from its original central position in the spore to the proximal face and then to one end of the spore. There is no morphological polarization of cytoplasmic organelles of the spore before migration of the nucleus.     

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.     

THE GERMINATION AND ENZYMIC ACTIVITIES OF BACILLUS SPORES AT LOW TEMPERATURES

SUMMARY: Well washed spore preparations of Bacillus cereus and B. subtilis were suspended in various nutrient broths, soil extracts, autoclaved soil of various moisture contents, and in two inorganic solutions, phosphate buffer, pH 7·2 and Ringer's solution. These were incubated at 8°, 5°, 1° and 0° for periods up to 270 days. Periodic total and spore counts on plates indicated a progressive decrease in each, associated with germination taking place in all conditions except in the two inorganic media. Enzymic tests indicated secretion and activity of nitratase and gelatinase and, with spores of B. pasteurii , urease, as a result of germination. B. subtilis germinated to a greater extent than B. cereus in each of the nutrient media. Germination of both organisms at 5° was also observed in L - and D -alanine: in the latter it was probably the result of racemization to the L -form.     

钾对小麦旗叶蔗糖和籽粒淀粉积累的影响

 利用冬小麦品种‘鲁麦22’(Triticum aestivum cv. `Lumai 22’)在大田条件下研究了钾素对小麦旗叶蔗糖和籽粒淀粉积累及其有关酶活性的影响。结果表明,钾素有利于提高旗叶光合速率,增强开花后旗叶磷酸蔗糖合成酶活性,提高旗叶中蔗糖的含量;从而提高了灌浆期间籽粒中蔗糖的供应,增强了籽粒中蔗糖合成酶和腺苷二磷酸葡萄糖焦磷酸化酶的活性,加速了淀粉积累速率,提高了粒重和产量。