Epidermal and seed surface characters of plants: systematic applicability and some evolutionary aspects

Based on SEM examinations of about 5000 species of seed plants, this is a survey of their epidermal surface characters with an aim to application in taxonomy. Surface characters may be grouped into four categories: (1) Cellular arrangement or cellular pattern. (2) Shape of cells (the "primary sculpture" of a surface). (3) Relief of outer cell walls (the "secondary sculpture" superimposed on the primary sculpture), caused mainly by cuticular striations and superficially visible wall inclusions and wall thickenings. (4) Epicuticular secretions (the "tertiary sculpture" superimposed on the secondary sculpture), i.e. mainly waxes and related substances.
The systematic applicability is discussed for each of these structural groups. Epidermal characters are only slightly influenced by environmental conditions. Their high structural diversity provides most valuable criteria for the classification between species and family level. There is also some evidence for their systematic applicability above the family level.
The possible evolutionary–ecological significance of surface sculpturing is discussed briefly. There is evidence that these features may be seen primarily under the aspects of reduced ability of plants to contaminate and as temperature control mechanisms of the surfaces.     

The transition of the thick ascending limb of Henle's loop into the distal convoluted tubule in the nephron of the rat kidney

Summary Examination of serial semithin sections of rat kidney cortex and a subsequent electron microscopic study of selected areas revealed that the characteristic epithelium of the cortical part of the thick ascending limb of Henle extends for a varying distance beyond the macula densa. The transition from the relatively thin epithelium of the thick ascending limb at this site to the three -or even four-fold thicker epithelium of the convoluted part of the distal tubule is sharply defined and occurs without the interposition of an intermediate cell type.The position of the macula densa at the end but still clearly within the ascending limb of Henle's loop is functionally interpreted to guarantee the separation of the sensor point macula densa from disturbing influences which might arise from the secretory activity of the subsequent tubular portion.Investigations supported by the Deutsche Forschungsgemeinschaft. The skillful technical assistance of Mrs. Saliha Sabanovic is gratefully acknowledged     

Forschungsschwerpunkte der paläobotanik und palynologie der Universität Wien

An initial accent on the investigation of megafossils by some well-known Austrian paleobotanists (like Ettinghausen, Stur, Unger) changed with time to a higher degree of research on the histology and anatomy of fossil plants, especially of wood and cuticles by the late E. Hofmann. Due to the large quantity of spores and pollen grains in peat, brown coal, salt rocks, phosphorites, clay and shales in Austria, the major topic of investigation at the present time is clearly devoted to palynology. Quaternary, Neogene and Permo-Triassic microfloras occupy the first place in research. Concerning the determination of pollen and morphologic studies of a selection of modern comparison species by all kinds of light and electron microscopy have been initiated to find out whether biospecific determination could be carried out in the Quaternary and Neogene. An example of pollen-morphological features within the genus Pinus is presented.The microflora of Upper Permian and Triassic sediments of the east Alpine salt rocks, their environment and inclusions receive comprehensive microphotographic documentation and will be backed from a stratigraphic point of view by sulphur-isotope investigations, which promise to be of great value in dating the Permo-Triassic boundary.     

Repeated characterization, analysis of variance limitation and discrimination analysis classification of EEG-activity patterns in human sleep]

1. To describe quantitatively and to deliminate nine EEG sleep patterns, mean values and standard deviations of abundances of the frequencies 0.8 ... 1.8 c/sec, 2...3.5 c/sec, 4...13c/sec, 14 to 17 c/sec, 18 to 22 c/sec, and 23 to 40 c/sec as well as of the average amplitudes in selected frequency ranges were calaculated and the distributions represented. 2. All nine EEG activity patterns could be separated by means of univariate and multivariate analyses of variance on the basis of all 28 as well as the 17 indispensable variables. 3. In the course of a stepwise reduction of variables within the framework of a linear discriminant analysis an optimal set of 17 variables was determined for the separation of the patterns, comprising: the percent quantity of the frequencies 0.8 ... 3.5 c/sec, 7 ... 9 c/sec and 18 to 40 c/sec as well as the average amplitudes in the frequency ranges 0.8 to 3.5 c/sec and 7.5 to 40 c/sec. 4. By linear regression analyses it could be shown that the sleep scording system used, can be reflected on an interval scale with the aid of discriminant functions; this can be achieved on the basis of the optimal set of variables as well as of the five most indispensable variables. 5. Finally the degree of the objectivity of the scoring procedures was demonstrated. Advantages and disadvantages of sleep scoring systems were discussed and possibilities of the utilization of results suggested, also in respect to the further development of the automatic recognition of EEG activity patterns.     

Mikromorphologie und Orientierungsmuster epicuticularer Wachs-Kristalloide: Ein neues systematisches Merkmal bei Monokotylen

Based on SEM examinations of some 1600 species of monocotyledons out of 61 families the characteristics of their epicuticular waxes are described in this preliminary paper and illustrated by 20 SEM micrographs. Four basic types of waxes are recognized. Two of them occur throughout the monocotyledonous and dicotyledonous orders of angiosperms; two others are of high systematic significance and restricted to particular orders of the monocotyledons: The “Convallaria-Type” is characterized by fine wax platelets with parallel orientation, forming a pattern around the stomata reminiscent of electromagnetic field lines. This type is restricted to the three liliiflorous ordersAsparagales, Liliales, andBurmanniales. The “Strelitzia-Type” is characterized by massive compound wax rodlets; it is restricted to the superordersAreciflorae, Commeliniflorae, Zingiberiflorae, plus the two liliiflorous ordersBromeliales andVelloziales. The data are compared with the classifications ofDahlgren & Clifford (1982); they tentatively indicate the exclusion ofBromeliales, Velloziales, andTyphales from theLiliiflorae.     

Purification and properties of glutamine synthetase from the plant cytosol fraction of lupin nodules

Glutamine synthetase from the plant cytosol fraction of lupin nodules was purified 89-fold to apparent homogeneity. The enzyme molecule is composed of eight subunits of M_r 44,700 ± 10%. Kinetic analysis indicates that the reaction mechanism is sequential and there is some evidence that Mg-ATP is the first substrate to bind to the enzyme. Michaelis constants for each substrate using the ammonium-dependent biosynthetic reaction are as follows: ATP, 0.24 mm; l-glutamate, 4.0–4.2 mm; ammonium, 0.16 mm. Using an hydroxamate-forming biosynthetic reaction the K_m ATP is 1.1 mm but the K_m for l-glutamate is not altered. The effect of pH on the K_m for ammonium indicates that NH₃ rather than NH₄⁺ may be the true substrate. At 10 mm Mg²⁺, the pH optimum of the enzyme is between 7.5 and 8, but increasing Mg²⁺ concentrations produce progressively more acidic optima while lower Mg²⁺ concentrations raise the pH optimum. The rate-response curve for Mg²⁺ is sigmoidal becoming bell-shaped in alkaline conditions. The enzyme is inhibited by l-Asp (K_i, 1.4 mm) and less markedly by l-Gln and l-Asn. Inhibition by ADP and AMP is strong, both nucleotides exhibiting K_i values around 0.3 mM. Investigations of the probable physiological conditions within the nodule plant cytosol indicate that in situ glutamine synthetase has an activity greater than that required to support the efflux of amino acid nitrogen from the nodule. A possible role for glutamine synthetase in the control of nodule ammonium assimilation is suggested.     

Einfluß der Konzentration der Zuckerlösung auf den Gesang und das Balzverhalten des Gelbbauchnektarvogels (Nectarinia venusta)*

Different concentrations of a sucrose solution vary the courtship song and behaviour of the male yellow-bellied sunbird Nectarinia venusta- the duration of subsong, total singing duration, and the absolute number of full song phrases. With high concentrations the sunbird sings more full song phrases but less subsong during the courtship season than otherwise. The various effects are described.