Der Einflu{beta} verschiedener Lichtqualitaten auf Chlorophyllgehalt und Wachstum von Gewebekulturen aus Crepis capillaris (L.) WALLR.

The influence of different light qualities on chlorophyll contentand growth of tissue cultures from Crepis capillaris (L.) WALLR. Tissue cultures from Crepis capillaris growing on media (M₁; M₂ ; M₂-E) formed chlorophyll and intact chloroplasts onlyin the short wave length region of the visible spectrum (350–550nm). In red light (600–700 nm) as well as in darknessthey lost their chlorophyll after 8–10 weeks. The growth of Crepis-cultures was strongly influenced by lightand the nitrogen of the medium. The highest increase in freshweight (425–485% increase in 3 weeks) was attained inred light or in darkness on M₂ by cultures which had lost theirchlorophyll completely. M₂ contains nitrates, ammonium saltsand amino acids. In contrast, the increase in fresh weight ofgreen cultures growing on M₂ in blue or white light was considerablylower (155–180% increase in 3 weeks). Omission of amino acids, (M₂-E), resulted in the reduction ofthe growth (increase of fresh weight in 3 weeks: 120%) of thechlorophyll-free cells growing in the dark. Green cultures behaveddifferently on M₂-E. In white light they attained an increasein fresh weight of 245%. This suggests that the growth promotingeffect of the amino acids can be replaced by light. Results with cultures growing on M₁, which contains neitherammonium salts nor amino acids, point in the same direction.Green cultures in white or blue light grew better (90–100%increase in fresh weight in 3 weeks) on this "deficient" mediumthan chlorophyll-free tissues in red light or in darkness (20–30%increase in fresh weight in 3 weeks). Some aspects of thesefindings which concern the effect of light on growth are discussed. (Received November 28, 1969; )     

The Capacity of Ovarian Cells of the Postnatal Rat to Reorganize into Histiotypic Structures

Cell-reorganization experiments in vitro were performed with dissociated rat ovaries at different ages of postnatal development, namely newborn, 8–10, 15–22, and 90-day-old. Ovarian cells consistently aggregated into follicularlike structures. Follicular organization in vitro is comparable to the ovarian histology of the respective age. The histogenic properties conserved by ovarian cells are considered to be related with the morphogenetic processes steadily occurring in the ovary.     

Adaptive Use of N2-Dimethyl-Substituted Pterins by Cultures of Crithidia fasciculata1

The compound 6-(L-erythro-1,2′,3′-trihydroxypropyl)pterin, at a concentration of 50 pg/ml (“L-erythro-neopteria”), supports half-maximal growth of Crithidia fasciculata; biopterin at a concentration of 30 pg/ml is shown to yield similar growth. N²-dimethyl-6-(L-erythro-1′,2′,3′-trihydroxypropyl)pterin (A) was inactive even at 100 ng/ml. Synergism was observed with the N²-dimethylamino derivative (A) in the presence of suboptimal biopterin, its activity then being of the order of L-erythro-neopterin. In contrast, the stereoisomeric N²-dimethyl-6-(D-erythro-1′,2′,3′-trihydroxypropyl)pterin (“dimethyl-D-erythro-neopterin”) and its 3′-mono-phosphate only slightly enhanced growth under similar conditions but both threo-isomers had no supplementary activity. Biopterin-induced growth was slowed by 6-(D-erythro1′,2′,3′-trihydroxypropyl)pterin (D-neopterin); the threo-isomers had no such effect. An adaptive demethylation capacity by growing cultures and competition of biopterin uptake by D-neopterin seems likely. The report of the occurrence in Euglena of N₂-dimethyl-6-(L-threo-1′,2′,3′-trihydroxypropyl)pterin and its 3′-mono-phosphate adds further interest to our observations.     

Local and Temporal Pattern of Con A-Binding Site Aggregation During Conjugation in Euplotes vannus (Ciliophora,Hypotrichida)1

ABSTRACT. Conjugating cells of Euplotes vannus (syngens Naples and Barcarès) were investigated for Con A-binding sites by means of fluorescence microscopy. Cells fixed with 0.4% paraformaldehyde and incubated with 15 μg/ml FITC-Con A showed a distinct region of strong fluorescence, the size, shape and localization of which characteristically changed during the course of conjugation, first appearing at courtship stage (cells contact without forming pairs) and vanishing soon after the migration pronuclei have been exchanged, but before cells have separated. Con A binding and conjugation were blocked by cyclohexamide and α-galactosidase. Con A-binding was also inhibited by α-mannosidase, α-glucosidase and β-galactosidase without affecting conjugation except a delay of pair formation. The results suggest an involvement of newly formed or translocated glycoconjugates in cell pairing during conjugation.     

Selection of a suitable cladoceran species for toxicity testing in turbid waters

Abstract Two Australian cladocerans, Moina australiensis Sars and a species of Ceriodaphnia, were evaluated as possible biological indicator organisms to assess the toxicity of irrigation supply and drainage water of the Murrumbidgee and Coleambally Irrigation Areas. M. australiensis, being large (～2000 μm) and orange, was initially chosen to overcome visibility problems in highly turbid Australian inland waters. However, the organism responded erratically in culture. Mortality was high and neonate production was unpredictable when cultured under recommended United States Environmental Protection Agency protocols. Attempts to improve culture performance by optimizing food (quality and quantity), water (control source, hardness, volume) and temperature were only marginally successful. Similar difficulties were not evident when Ceriodaphnia sp. was used as the test organism. Although Ceriodaphnia sp. is small (～1000 μm), grey and more difficult to see in turbid water its responses were more predictable and reliable than those of M. australiensis. Results of initial trials comparing the two organisms suggest that Ceriodaphnia sp. was a better test organism and more suited to local requirements.     

Estimation of growth parameters in salt-stressed maize: comparison of the pressure-block and applied-tension techniques

A custom-built pressure block was used to estimate the effective turgor (turgor pressure minus the yield threshold) and the cell wall extensibility of the growing zone of the third leaves of 8-d-old maize (Zea mays L.) seedlings. In response to cell wall loosening, pressure in the chamber increased rapidly and reached a maximum after approximately 60 min. Plants treated with 80 mol m^?3 NaCl for 4 h were compared to control plants. Pressure-block analysis revealed that salinity reduced effective turgor, but had no effect on cell wall extensibility. These results are qualitatively and quantitatively similar to those obtained with an applied-tension technique used previously in our laboratory. This study indicates that the pressure-block and applied-tension techniques, which use very different methodologies, estimate similar growth parameters.     

Ammonium Nutrition Enhances Chlorophyll and Glaucousness in Kohlrabi

Kohlrabi (Brassica oleracea var.gongylodes) plants were grownin the greenhouse under autumn conditions and fertilized eitherwith pellets containing nitrogen as 40% ammonium sulphate and60% urea or with nutrient solution containing nitrogen predominantlyas nitrate. Plants given nitrogen as ammonium ions developedglaucous leaves compared to those supplied with nitrate whichformed glossy leaves. Ammonium-induced glaucousness was theresult of a two-fold increase in the amount of epicuticularwax and a markedly altered fine structure. Leaves from ammoniumfertilized kohlrabi plants also showed a 21% increase in chlorophyllcontent together with a reduction in the chlorophyll a:b ratioand decreased ground state fluorescence compared to plants suppliedwith nitrate. Photosynthesis and stomatal transpiration wereunaffected by the form of supplied nitrogen. Brassica oleracea ; chlorophyll; chlorophyll fluorescence; epicuticular wax; glaucousness; photosynthesis; transpiration     

Kinetics of Maize Leaf Elongation: II. RESPONSES OF A NA-EXCLUDING CULTIVAR AND A NA-INCLUDING CULTIVAR TO VARYING NA/CA SALINITIES

Salinity causes physiological and morphological changes in plantsand calcium can mitigate many of these effects. In this study,the effects of salinity (75 mol m^–3 NaCl) with or withoutsupplemental Ca (10 mol m^–3) on the kinetics of maize(Zea mays L.) leaf elongation were examined using Linear VariableDifferential Transformers (LVDTs). Short-term growth responsesof two cultivars (Dekalb hybrid XL75 and Pioneer hybrid 3906)differing in salt tolerance were compared. Salinity caused animmediate reduction in the leaf elongation rate (LER). Within2 h, elongation rates had increased and reached new steady rates.Significant differences between salinity treatments with highand low Ca could be detected within the first 2 h after impositionof salinity for Dekalb hybrid XL75, but not for Pioneer hybrid3906. After 24 h, distinct differences for both cultivars weredetected. Dekalb hybrid XL75, a Na-includer, was more salt-sensitiveand responsive to supplemental Ca (10 mol m^–3) than Pioneerhybrid 3906, a Na-excluder. Turgor was not reduced 24 h aftersalinization because there was complete osmotic adjustment inthe elongation zone of the leaves. Analysis of the growth parameterslimiting LER indicated that the yield threshold (Y) was increasedfor salt-stressed plants. In addition, both the cell wall extensibilityand hydraulic conductance were reduced 24 h after salinization.Supplemental Ca increased LER of salt-stressed plants by increasinghydraulic conductance. The differences in LER of the two cultivarsunder saline conditions was attributed to differences in theincrease of Y caused by salinity. Key words: Calcium, growth, salinity, sodium, Zea mays L.     

Population systematics of Russell's viper: a multivariate study

A multivariate analysis of the population systematics of Russell's viper, based on scalation and colour pattern characters, reveals that the populations of this viper constitute two well-defined taxa: a western form, comprising all populations from the Indian subcontinent, and an eastern form, comprising all populations from east of the Bay of Bengal. The two forms could be considered either as subspecies of one species, or as two separate species, depending on the species concept used. Within the western form, there is no clear pattern of geographic variation. Within the eastern form, the populations from the Lesser Sunda Islands are clearly divergent from the populations of mainland Asia and Java. The conventionally recognized subspecies of Vipera russelli fail to portray this pattern of geographic variation. There is no clear relationship between the pattern of geographic variation in morphology and the pattern of geographic variation in the clinical effects of the venom in human bite victims: some populations with considerable differences in venom effects are equally distinct morphologically, whereas other populations with equally strong venom differences are morphologically very similar. The distribution of Russell's viper can be attributed to Pleistocene changes in climate and sea level, coupled with the viper's ecological requirements, which appear to include a seasonally dry climate.     

Miniaturization in plethodontid salamanders (Gaudata: Plethodontidae) and its consequences for the brain and visual system

In seven species of plethodontid salamanders (Desmognathus ochrophaeus, Eurycea bislineata, Plethodon cinereus, Batrachoseps attenuatus, Hydromantes italicus, Thorius narisovalis and Bolitoglossa subpalmata), absolute and relative volumes of the eye, the brain, major regions of the brain, and regions containing the major visual and visuomotor centres (i.e. thalamus, praetectum, tectum and tegmentum mesencephali), and the density and number of neurons in these regions were determined. The seven species range from moderately large to extremely small in body size and from the smallest to the largest genome sizes found in terrestrial salamanders. The following processes were observed in miniaturized salamanders with intermediate to large genome and cell sizes (Batrachoseps, Thorius) as compared to small and medium-sized salamanders with small genome and cell sizes: (1) increase in the relative size of the brain, from 3.9 to 12.4% of head volume; (2) reduction in relative size of the ventricles from 10.9 to 5.8% of brain volume; (3) increase in relative volume of those brain regions containing the major visual and visuomotor centres from 29.2 to 37% of brain volume; (4) increase in volume of grey matter relative to white matter, from 33.2 to 44.4% of midbrain volume; (5) increase in volume of tectal relative to tegmental grey matter, from 54.8 to 76.8% of total midbrain volume; (6) increase in neuron packing density in the regions containing the visual centres, from 16 to 31.5%. Because of these compensatory processes, Thorius, the smallest species with a head 1/27 and a brain 1/9 the size of that of the largest one, Hydromantes, has 1/3 as many central visual neurons (58 000 vs. 187 000). Some of these processes found in miniaturized salamanders, such as increase in tectal cell density, also occur in large salamanders with very large genome and cell sizes, viz. in Bolitoglossa (25%) and Hydromantes (29%). Thus, increase in genome size and cell size seem to pose functional problems similar to miniaturization; both cases involve an increase in cell size relative to overall organismal structure.