摘要:

SUMMARYThe carpospores ofScinaia complanatagrow into a filamentous tetrasporophytic phase, which is capable of self‐reproduction. The tetraspores grow into a morphologically recognizable filamentous gametophytic stage, which is also capable of self‐reproduction, and which can give rise to adultScinaiathalli. Growth and reproduction of the tetrasporophyte and the gametophytic filamentous stage, as well as the development of adultScinaiathalli, are furthered by 17 °C long day conditions, which roughly correspond to summer conditions in the Mediterra

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00671.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYThe ultrastructural changes of the embryo sac ofPetuniaduring and after fertilization are described. The pollen tube enters the embryo sac by growing through the filiform apparatus and discharges its content into one of the synergids (penetrated synergid). The volume of the penetrated synergid increases and the cell bursts at its chalazal pole. The synergid and discharged pollen tube cytoplasm merge and subsequently degenerate. The degeneration is marked by the darkening of the cytoplasm and the disappearance of organelles. A complex rough endoplasmic reticulum and numerous small spheres remain discernible longest. Two degenerating nuclei are present in the penetrated synergid.The ultrastructure of the zygote changes slightly during its early development. 50 hrs after pollination (10–15 hrs after fertilization) the nucleus does not contain chromatin clumps any more and is surrounded by a shell of plastids.The primary endosperm cell shows a number of marked changes after the formation of its nucleus. The ribosomes become aggregated into large polysomes and the plasma matrix becomes homogeneously electron‐dense. Both the mitochondria and dictyosomes change in ultrastructure and shape. Plastids, without starch, appear as the endoplasmic reticulum becomes very extensive. This ultrastructural differentiation indicates a changing metabolic activ

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00672.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYCombinations of extracts from pollen and styles of Petunia hybrida caused an increase of the deamination by glutamate dehydrogenase (GDH). However, neither the combination of 54‐fold purified style GDH and pollen extract, nor the combination of partly purified pollen GDH and style extract resulted in an activation of the deamination by GDH. It appeared that the increase of the GDH deamination found after combining pollen and style extract was caused by activation of a dehydrogenase which interferes with the GDH deamination assay. Although this dehydrogenase was found to be present in both pollen and styles, it was only active in the styles since it needed an aromatic amine or phenol for its catalytical action which was found in the styles, but not in the polle

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00673.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYA study of the variation in the number of fertile stamens in flowers ofSpergularia marinarevealed that this number fluctuates between 0 and 10 but is usually 2 to 5. A statistical analysis showed that reduction did not take place at random, because certain stamens tend to disappear more often than other ones, the progressive reduction also proceeding according to certain rules. Although the causal explanation for these phenomana can only be a tentative one for the time being, the statistical data are put on record in order to draw the attention to the occurrence of such singular processes.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00674.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYSeasonal fluctuations of dry matter, water soluble carbohydrates and total nitrogen content were traced in underground storage organs ofCirsium arvenseandTussilago farfara. Samples from experimentally planted monocultures of the two species were analysed.Both species showed identical fluctuations in dry matter and carbohydrate contents. A gradual decrease in autumn and winter, succeeded by a rapid decline in spring, after a distinct minimum in April‐May was followed by a steep rise towards a maximum in late summer. Fluctuations seem bo be affected by weather conditions during the growing season.The nitrogen content decreased gradually from early spring until the middle of the summer and then increased similarly until the start of the cycl

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00675.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYChanges in activity of some mitochondrial enzymes from cotyledons of peas have been followed during germination. During the first day the activity of the succinate and malate oxidase system increased whereas succinate and malate dehydrogenase activity hardly changed. Oxidase and dehydrogenase activity both increased during the subsequent two days. The respiratory control of mitochondrial fractions from mature, air‐dry cotyledons was very low but increased rapidly during the first day of germination. Mitochondrial activity decreased during the later phases of germination. It is suggested that the increase of the respiratory capacity of the mitochondria during the first day is effected by an increase of the capacity of the electron transfer chai

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00676.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYThe isolation and subculturing of callus tissues from three coffee species is described. In callus tissues of one species, i.e.Coffea canephoraPierre ex Froehner (‘Robusta’ coffee), embryoid and plantlet formation was obser

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00677.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYBranches ofChenopodium album, including leaves and young inflorescences, were put into a solution of15N‐L‐proline in order to absorb the latter with the transpiration stream. After 48 hrs of exposure a number of nitrogen fractions were separated.15N was found in free and bound amino acids, especially in arginine, alanine, glutamic and aspartic acid as well as in amino‐lipids and chlorophyll fraction. Proline is considered to be an important source of nit

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00678.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYFlat forms ofLemna gibbabecame gibbous in the presence of EDDHA. The degree of the gibbosity varied with the concentration of the chelate. The maximum convexity was observed at 10 and 20 ppm. This clearly suggested that both flat and gibbous forms belong to the same taxon and merely represent the morphological modifications under different nutritional conditions.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00679.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYAn as yet unidentified glucose‐complex is formed in the cells of 5 mm stem segments cut from the third internode at 1 mm from the tip of etiolated pea seedlings. In segments growing in solutions containing 10 μg/ml IAA and various concentrations of glucose the quantities of the unknown glucose‐complex and cellulose are proportional.Increasing the IAA concentration at a constant glucose concentration of 0.1% causes an increase in the glucose‐complex and in the synthesis of cellulose up to a concentration of 10 μg/ml. At IAA concentrations higher than 50 μg/ml cellulose synthesis decreases to the value obtained when no IAA is present, whereas the amount of the glucose‐complex is increased.Galactose inhibits cellulose synthesis by way of interfering with the glucose absorption.In low concentrations of glucosecobalt chloride promotes sugar absorption, the formation of the glucose‐complex, and cellulose synthesis. In high sugar concentrations it does not affect these processes.The results obtained indicate a close relationship between cellulose synthesis and the formation of the glucose‐complex. It is suggested that the latter is an intermediate in the synthesi

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00680.x

年代:1970

数据来源: WILEY