Abstract: Horsechestnut anthers were isolated from flower buds in various stages of development and cultivated in the presence of auxin and kinetin. The anthers showed the capacity for androgenesis and evidence is presented that the plantlets developed from single microspores. Haploid karyotypes were observed in the root menstem cells in three plantlets.

Abstract: The products of first microspore mitosis were studied in anthers of Hordeum vulgare. These anthers were obtained either directly from plants at the binucleate stage or from tillers which had been estimated visually as containing pollen at the mid-uninucleate stage and then pretreated by being clipped off at ground level and allowed to stand in water for 2 d. In microspores from the latter plants ten-fold increases in the failure of nuclear differentiation, alteration of the axis of division, or both were observed. High frequencies of further microspore response in individual anthers were subsequently induced through culture of the spikes from the pretreated tillers in agitated liquid medium. A five to ten-fold increase in the percentage of anthers producing macroscopic callus was observed in these spikes when compared with the controls. It is suggested that nucleo-cytoplasmic disturbances in the microspores, brought about through the pretreatment period, stimulated the further divisions which eventually resulted in microspore callus formation. Microspore calluses were produced most often following an equal first division, although when mitosis resulted in differentiated nuclei further divisions of the vegetative nucleus also resulted in callus production. Haploid, diploid, polyploid, and mixaploid microspore calluses were produced but no evidence was obtained to link haploid production with any particular developmental pathway. Macroscopic calluses which emerged from the cultured anthers were probably mixtures of cell populations derived from several or many different gametic genotypes.

Abstract: des Rfickenmarks, den Nerven, die den Herzschmerz melden, eng anliegen und infolge mangelhafter Isolierung miterregt werden. Das fihnelt dem ,,(Jbersprechen\" in Nachrichtenleitungen. Um die Richtigkeit dieser Vermutung zu prfifen, wurden durch elektrische Str6me Schmerzen an den genannten Armstellen erregt; der erwartete scheinbare Herzschmerz konnte jedoch nicht deutlich wahrgenommen werden. Diesem fast negativen Ergebnis ffigte sich aber ein positives an. Als der Patient zuffillig bei Vorbereitung der Versuche einen Angina pectorisAnfall aus anderer Ursache erlitt, bewirkte die Stromreizung am Arm das sekundenschnelle Aufh6ren der Herzschmerzen. Dieser Vorgang war reproduzierbar, als es gelungen war, optimale Stellen ftir den Ansatz der Elektroden zu finden. Gedeutet wird diese Erscheinung als Energieentzug im Bereich einer Engstelle des Nervenbtindels. Die ,,Armnerven\" verbrauchen bei starker Reizung dort die Energie infolge Diffusion der Elektrolyte auch aus ihrer Umgebung, hier aus dem Bereich der den Herzschmerz meldenden Nervenleitung. Das Verfahren kann nicht als echte Therapie gelten. Der Verfasser wendet sich mit dieser als Anregung gedachten Mitteilung mehr an Biophysiker und Biologen als an Mediziner.

Abstract: Our objective was to determine the average numbers of pollen grains from fertile plants (Ms 1) and the average numbers of coenocytic microspores from genetic male sterile plants (ms 1 ms 1) in soybeans, Glycine max L. Merr. Comparisons were made between the average numbers of pollen grains and the average numbers of coenocytic microspores with respect to environment where plants were grown and to stamen position in the flower. Five male sterile lines were used. They included the North Carolina ms 1 mutant, the cultivar Hark with the ms 1 gene, and mutants identified as the Urbana, Tonica, and Ames male steriles. Three environments used were the Agronomy Farm, University of Georgia, Athens, Georgia; the Agronomy and Agricultural Engineering Research Center, Iowa State University, Ames, Iowa; and the Agronomy Greenhouse, Iowa State University, Ames, Iowa. Pollen production from fertile plants varied from 374 to 760 pollen grains per anther among genetic lines and environments. This variation may be an important consideration in selecting a male parent to use as a pollinator for hybrid seed production. Among fertile plants, the average numbers of pollen grains per anther of the separate stamen and and of the lower whorl of stamens were significantly different only in greenhouse-grown plants. Among male sterile plants, the average numbers of coenocytic microspores per anther of the separate stamen and of the lower whorl of stamens were significantly different in three genotype x environment combinations. These three exceptions did not conform to any genetic or environmental pattern. Deviations from the expected ratio of 4 pollen grains from fertile plants: 1 coenocytic microspore from sterile plants were attributed to initial differences in the average number of microspore mother cells between the two genotypes.

Abstract: Lepidodendracean fructifications with well-preserved megagametophytes are described from Pennsylvanian petrifactions of eastern Kentucky. One cone is megasporangiate with one functional alate spore in each sporangium; the other cone is bisporangiate with spinose megaspores and papillate microspores. Both strobili have megaspores that contain prothallia with rhizoids and well-developed archegonia. Ontogenetic stages of megagametophytic development in these cones are comparable to stages that occur in extant heterosporous lycopods. This study provides further evidence of a close phylogenetic relationship between the lepidodendrids and the extant genus Isoetes.

Abstract: When a monosomic plant of a diploid species undergoes meiosis, two haploid and two nullisomic cells are produced. Zea mays L. microspore quartet cells nullisomic for chromosome number 1, 2, 4, 6, 7...

Abstract: [in Japanese]

Abstract: Binucleate microspores were induced in Tradescantia paludosa with heat shocks. Nuclear and cell volumes were determined from early G1 to G2. Volumes of sister nuceli, present in a single cell, were rarely the same. It is suggested that, at least in part, nuclear volume is controlled by factors that are 1) present in nuclei, 2) not distributed equally at anaphase, and 3) not rapidly exchanged.

Abstract: The cause of male sterility in 3 soybean lines, TGM 103-1, N-69-2774 and TGM 242-4 was studied. In TGM 103-1, which was both male and female sterile, two different abnormalities were associated with sterility. Precocious movement of a few chromosomes at the metaphase I stage resulted into the production of non-functional pollen while cells which underwent apparent normal meiotic division had disintergration of the tapetal cell wall immediately after the free microspore stage leading to the starvation and subsequent death of the developing microspores. In lines N-69-2774 and TGM 242-4, both of which were partially sterile, male sterility resulted from a failure of cytokinesis after the telophase II stage. Meiosis proceeded normally but the 4 microspores after telophase II failed to separate into pollen grains and degenerated thereafter.

Abstract: Several experiments have been performed in order to induce cell proliferation and plant differentiation from pollen grains by anther culture in barley. Some modifications of the culture media, pretreatments and transfer of the anthers increased notably the frequency of cell division, but the low proportion of normal green plantlets differentiating from microspores and calluses remains the major obstacle preventing the practical use of anther culture in barley breeding.