ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb11762.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

The surface ofTrachelomonaswas examined readily with SEM at magnifications up to X 20,000 in unfixed or fixed material. Cells were placed directly on specimen holders without washing, air dried, and coated with aluminum or gold. Clones ofT. grandis, T. hispidavar.coronata, andT. oblongavar.punctataand three species from a natural collection showed the following features: the lorica was punctate or solid, and the surface projections, when present, consisted of minute papillae (0.1 μm), larger, often globose papillae (up to 0.8 μm), and spines which tapered to a point or which had parallel sides and ended bluntly; spines appeared hollow or solid. Pringsheim's clone ofT. oblongavar.punctata, which he described as a new spineless variety, possessed short tapering spines and globose papillae. Such observations suggest that a major problem in delimiting species may be in discovering the ornamentation potential of a clone. The discovery of new features of the lorica (e.g., minute papillae and hollow projections), the clarification of shapes of surface features, and, in general, the excellent resolution at 10 times the usable magnification of light microscopy dictate a reexamination of known species with SEM. We suggest that a SEM study of the variation in the lorica surface in clonal material will lead to a recognition of polymorphism and eventually to a clearer understanding of taxonomic entities described from natural collections.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb12337.x

出版商:Wiley    

年代:1975

数据来源: WILEY

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb11763.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

When wheat is germinated in high concentrations of certain auxins, the coleorhiza‐epiblast grows in an excessive and disorganized manner and resembles a callus. Wheat was germinated in 10−3M indoleacetic acid or in water. There was greater net synthesis of DNA, RNA, and protein in the tumor tissue than in control tissue. Control and tumor tissue was fixed for electron microscopy 1, 2, 3, and 4 days after sowing. In contrast to the controls, many more lipoidal bodies appeared in 1‐day‐old, auxin‐treated tissue and thereafter diminished in number. In 2‐ and 3‐day‐old tumor tissue, small membraneous fragments were prominent but disappeared in older tissue. With time, the following changes became progressively more pronounced: cytoplasmic vacuolation, appearance of myelin figures, polyribosome configurations and extensive profiles of rough endoplasmic reticulum, and sloughing of cytoplasmic contents into and accumulation of electron‐dense material in vacuoles. Possible factors in susceptibility of certain tissues to tumor formation are discussed.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb12338.x

出版商:Wiley    

年代:1975

数据来源: WILEY

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb11764.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

Frond members belonging to the monostelic seed fern genusHeterangiumhave been found in Pennsylvanian age coal balls collected in the Illinois Basin. Petioles bear small pinnae below a dichotomy which produced a bipartite frond. Pinnules of theSphenopteris obtusilobatype are borne on secondary pinnae. The anatomy of each pinna order and the pinnules is described.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb12339.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

Root nodules ofAlnus crispa(Ait.) Pursh were shown to possess a symbiotic nitrogen‐fixing organism. The reduction of acetylene to ethylene, as measured by gas chromatography, was used to determine the presence of the nitrogen‐fixing system. Ethylene production was measured at 5.1 μmoles/g excised nodule · hr for both field and greenhouse plants. The nodules were found to consist of short nubs usually clustered in masses up to 4 cm in diam. Microscopic examination of nodules revealed some cortical cells fully packed with spherical endophyte cells. The outer cortex and radiating arms of cells in the inner cortex remained uninfected. Nodules examined during the winter were found to be shrunken, with a random distribution of endophyte cells. Soil nitrogen measurements indicated that nitrogen fixation activity byA. crispadoes not lead to an increase in soil nitrogen above levels in adjacent areas.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb12340.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

Analysis of size‐class distribution in three streamside forest stands in central Illinois shows close agreement of observed data with the negative power curve model of tree size‐class distribution. However, examination of the size‐class distribution of selected species reveals a number of deviations from the model. Most of the deviations from the model can be explained in terms of disease and land use.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb12341.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

Marking procedures were combined with anatomical techniques to establish that inFunaria(1) the apical region does not act as an apical meristem contributing to seta growth, and (2) the subapical region contains an intercalary meristem the derivatives of which account for the elongation of the seta. In sporophytes that are 8 mm long there is a distinctive difference in the pattern of cell division in the apical and subapical regions. Large, undivided endothecial cells exist in the apical region, and a central strand of elongated cells occupies the analogous position in the subapical region. The apical region is earmarked to form the operculum and spore sac and part of the apophysis. There is an ontogenetic continuity between the seta and the lower portion of the apophysis, but the uppermost cells of the subapical region do not contribute to seta formation. Instead, these cells and those at the base of the apical region form a transitional zone between apical and subapical influences, and they account for most of the stomates that develop on the apophysis.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb12342.x

出版商:Wiley    

年代:1975

数据来源: WILEY

摘要:

Ten phenolic compounds were examined for their effect on mung bean (Phaseolus aureusL.) hypocotyl growth and on respiration and coupling parameters of isolated mung bean hypocotyl mitochondria. Three compounds—tannic, gentisic, andp‐coumaric acids—inhibited hypocotyl growth and when incubated with isolated hypocotyl mitochondria released respiratory control, inhibited respiration, and prevented substrate‐supported Ca2+and PO4transport. Vanillic acid also inhibited hypocotyl growth and reduced mitochondrial Ca2+uptake but did not affect respiration or respiratory control of isolated mitochondria. This is the first compound reported to selectively inhibit Ca2+uptake in plant mitochondria. Two other phenolic compounds—α, 3,5‐resorcylic and protocatechuic acids—showed no significant effect on hypocotyl growth and did not affect mitochondrial oxidative phosphorylation either separately or in various combinations. Four phenolic compounds—ferulic, caffeic,p‐hydroxybenzoic, and syringic acids—showed a significant reduction in mung bean hypocotyl growth but did not inhibit any of the mitochondrial processes examined. The results show that phenolic compounds which alter respiration or coupling responses in isolated mitochondria also inhibit hypocotyl growth and may reflect a mechanism of action for these natural growth inhibitors.

ISSN:0002-9122    

DOI:10.1002/j.1537-2197.1975.tb12343.x

出版商:Wiley    

年代:1975

数据来源: WILEY