A phosphatase enzyme hydrolysing NADP⁺ and NADPH to NAD⁺ and NADH was found to be present in extracts ofChlorella pyrenoidosa

The present paper incorporates a detailed study on the distribution of 5-nucleotidase in the germinating pollen grains ofEschscholtzia califomica. The intense activity of this enzyme has been found in the wall of pollen grains and pollen tubes and small positive granules in the lumen of both in the pollen grains and pollen tubes. The presence of this enzyme in the wall is presumably connected with the permeability and transport process and growth regulation of the pollen tubes.

The nucleic acid fractions in cotyledons of young Chenopodium rubrum plants exposed to continuous light, continuous darkness and short (8 h) day, respectively and labelled with³²P 24 h prior to harvesting were studied by means of chromatography on MAK columns. Some parameters of cotyledon growth (dry weight, cotyledon area, occurrence of mitoses) were also investigated.
The changes in the nucleic acid fractions agreed with the dynamics of cotyledon growth. In continuous light the content of all fractions increased. The radioactivity of DNA and s-RNA did not undergo any great changes and only r-RNA increased. The specific activity of r-RNA increased slightly, that of soluble RNA and DNA was reduced. In continuous darkness the content of all the fractions did not undergo any great changes. The radioactivity as well as the specific activity of all fractions decreased. In short day the content of the nucleic acid fractions did not change conspicuously. Only the specific activity of s-RNA increased in a noticeable way while the radioactivity of r-RNA and the specific activity of DNA decreased and this of r-RNA did not change. The changes in nucleic acid metabolism were partially connected with changes in³²P uptake which depended upon light conditions but they were not merely a consequence of this fact. Obviously, there also exists a more direct relationship between nucleic acid synthesis and growth.

Phosphorus oxytriamide PO(NH₂)₃ was proved chromatographically in the exudate of decapitatedPhaseolus vulgaris plants. This fact verified the presumption that covalent compounds of phosphorus and nitrogen enter roots without previous hydrolysis.

Studying relationships between tobacco mosaic virus reproduction, anthocyanin biosynthesis and phosphorus content in cultivation medium, it was found thatMartin's (1958) finding of an indirect proportion between anthocyanin and virus synthesis is valid even under the complicated conditions of pathological anthocyanin formation induced by phosphorus deficiency. A decrease of anthocyanin biosynthesis with simultaneous stimulation of virus reproduction takes place at temperatures below 20°C. Increased anthocyanin biosynthesis accompanied with the inhibition of virus reproduction occurs at temperatures above 20°C. The obtained results suggest that enzyme systems and substrates participating in considerably increased anthocyanin biosynthesis induced by phosphorus deficiency, differ from those taking part in anthocyanin synthesis induced by virus infection.
The enhanced phosphorus content in the cultivation medium does not influence anthocyanin biosynthesis significantly. Nevertheless, a highly significant inhibition of tobacco mosaic virus reproduction takes place at temperatures above 20°C. This inhibition may be in correlation with some other metabolic systems affected probably by the enhanced phosphorus concentration in the nutrient medium.

The photosynthetic production of dry matter of discs cut out from leaves of cucumber plants severely infected withCorynespora melonis was significantly lower than that of discs from healthy plants. The decrease was found in discs from leaves both infected and symptomless. Expected inhibition agent has not been isolated up to now.

Anthers ofLycium halimifolium were grownin vitro at the following stages of development: tetrads, microspores and binucleate pollen grains. Pollen plantlets were obtained only from anthers inoculated at the stage of microspores. The growth of androgenic embryos was very slow. Mature embryos were formed in about 3% of the inoculated anthers. The largest number of embryos obtained from one anther was 4.

The first information concerning the cytogenetic efficiency of thermal neutrons in lentil are presented in this paper. The range of cytologically effective dosages of thermal neutrons in lentil was determined. This determination enables us to compare the efficiency with the mutagenic effect of thermal neutrons and with their effect on the growth and development of plants of M₁ generation. These effects were already evaluated in previous communications.
Thermal neutron irradiation significantly affected all the characters studied. A linear dependence of the effect on the dose of the neutron radiation was found for most of the analyzed characters. From a sample of scored cells, whose nuclei were in the anaphase or early telophase, 9.0 to 72.0% of them had chromosomal bridges and fragments after irradiation with dosages from 3.3×10¹¹ n cm^-2 to 4.5×10¹² n cm^-2. The highest number of rearrangements per one cell reached 2.16 after irradiation with 4.25×10¹² n cm^-2 while the lowest dosage used, 3.3×10¹¹ n cm^-2, induced 0.17 of chromosomal rearrangements per one cell. Irradiation with thermal neutrons is capable of inducing a large number of very complicated chromosome rearragements.

The effects of several growth and trophic substances on bud and root neoformation on leaf fragments ofBegonia rex were studied in precisely defined environmental conditions. IAA, depending on the type of treatment, had different effects. In aseptic cultures, a notable stimulation of bud formation was observed at certain concentrations. However, non aseptic treatments of IAA had no visible effects except at very high concentrations.(10^-3 M) where bud formation was totally inhibited and root formation was favored. NAA, at 10^-6 M and 10^-5 M strongly stimulated root formation and inhibited shoot formation. All the cytokinins used stimulated bud formation and inhibited partially or totally root formation. Gibberellic acid inhibited bud and root formation. Glucose and sucrose clearly stimulated bud and root formation and sucrose, when applied simultaneously with other growth substances, modified the effects of these substances alone. The most favorable environmental conditions were at 24°C in a 24 h photoperiod but other temperatures (17 to 27°C) and photoperiods (9 or 16 h) did not prevent neoformation.

Virus particles (approximately 73 nm in diam.) usually showing an inner capside (45 nm in diam.) and similar to diplornaviruses, esp. reoviruses, were found in some cells of enations inAvena sativa andArrhenatherum elatius leaves infected with the oat sterile dwarf disease (OSDD). (The same virus particles were described by the authors in 1966 in the leafhopper vector.)
Mycoplasma-like microorganisms found in1969 in the OSDD leafhopper vector were absent in OSDD infected plants. Tetracycline did not affect symptom development in plants and did not alter the infectivity of the vector.
Therefore, OSDD is apparently of virus origin; mycoplasmas-like bodies found formerly in the OSDD vector are probably not involved in OSDD etiology.

Studying the influence of the pH of 10% NaCl solutions used for the extraction of RNA and DNA on the yield of both nucleic acids, the maxima of pH were found at which both types of nucleic acids pass into extracts better than at neutral pH and do not remain in residues of the experimental material.The perchloric acid extraction temperature was also studied for obtaining the hydrolysate of nucleic acids from the trichloroacetic acid precipitate of sodium chloride extracts differing by 5 °C within the range of 35 °C to 90 °C and it was found that in this wide range almost the same amount of RNA is extracted by the method used. However, at a lower temperature, some DNA remained in the extracted residue of the trichloroacetic acid precipitate of sodium chloride extracts.

The meioses of four sterile species in the genusAllium which develop bulblets in the inflorescences instead of seeds were compared, namelyAllium sativum, A. cepa var.viviparum, A. carinatum, andA. oleraceum. The most important of them,A. sativum, is an ancient cultivated plant and its vegetative reproduction prevents it from more rapid evolution such as is known in generatively propagated cultivated plants.A. sativum shows fully normal meiosis. After the disintegration of the tetrads, however, the blockade of 1. pm takes place. The cause of the blockade has not yet been cleared up. Removing of bulblets appeared as having no influence on the development of microgones. It is assumed that there may be a viral phenomenon causing a disease of the tapetum without disturbing other functions. InA. cepa var.viviparum there was observed a heavy aberration disturbance in the meiosis, which had already been signalled by the mitosis. On this ground 1. pm does not occur and sterility is fully justified. The aberration disturbance does not seem to spoil the vegetative development but on the contrary to give it a vigorous character.A. carinatum andA. oleraceum are triploid and tetraploid forms; in the meiosis they form various configurations-univalents, bivalents, trivalents, and quadrivalents. The following irregular chromosome distribution results in the coming into existence of variously valuable gametes. 1. pm takes place. There is a theoretical possibility of generative reproduction (after the extirpation of bulblets).

The present studies of the LDH isoenzymes have been made as a part of our studies on the respiration systems of the roots ofVicia faba. All the root zones had 5 LDH isoenzymes and 2 antibands, but there were differences in their relative quantity. Cathodic isoenzymes (LDH₅, LDH₄) prevailed in the meristematic zone, whereas the anodic ones (LDH₁) prevailed in the others. The different enzyme activity in individual zones is probably connected with the transition of the anaerobic metabolism in the meristem to the aerobic one in the differentiating parts of the root.

The character of endogenous growth substances was investigated in developing buds, young fruits and mature walnut leaves. The relatively high content of auxins and gibberellin-like substances was found by means of bioassays in the youngest primordia of vegetative buds. The level of auxins drops in the further course of primordia transformation into the staminate catkins. The development of leaf-buds is characterized by the accumulation of inhibitory activity as revealed by theAvena bioassay, whereas the data obtained from the lettuce bioassay indicate a pronounced stimulation. The onset of terminal bud development is also accompanied by inhibitions and it is only with pistillate flower differentiation that the temporary rise in auxin level is observed. An inhibitory activity was found in these extracts using lettuce bioassay. There is a relatively high auxin level in young fruits, mature leaves and resting buds during the mid-summer period whereas the accumulation of clearcut inhibitions is signalled by the results of lettuce bioassay.
The regulatory role of growth substances in differentiation may be better understood during the second year as many leaf-abnormities appear only with the outgrowing of the bud. Abnormal catkins differ in the number of florets and stamens and some even bear pistillate flowers. Fruit development is liable to deviations in the early stages of differentiation. Abnormal fruits enable us to elucidate many structural peculiarities.

The analysis of diurnal oscillatory movements of tobacco leaves was used in the diagnosis of viral infection of plants. The oscillatory helices circumscribed by a growing leaf of a healthy plant were regular, but some deviations, particularly in the transition points, were recorded.
In order to make clear the cause of these irregularities of trajectory, the course of elongation of leaf petiole and blade in relation to localization and shift of zones of elongation during ontogenesis was analysed. The present analysis is similar to that described by the author's earlier experiments with pea roots. Oscillatory curves circumscribed by petiole, projected on a horizontal plane, were compared with curves circumscribed by the blade tip. The analysis of the leaves of different ages enabled us to study this process in dependence on growth rate. It was confirmed that oscillations are a result of elongation; the extent of oscillations is quantitatively dependent on the growth rate. An analysis of the zones of growth showed that in petiole the active meristems are localized near to its base while in the leaf lamina they move gradually during the ontogenesis from the apical to the basal part of the leaf blade. Active meristems of young rapidly growing leaves are localized approximately in the middle of the blade while those of old leaves were found in close proximity to the base of the lamina. The growth rate of petiole can be expressed in hundreds of mm per hour (4.8×10^-2 mm h^-1); half of this value was recorded for its apical part. The growth rate of leaf blade was found approximately ten times higher (3.2×10^-1 mm h^-1).
The oscillatory movements of growing leaf consists of two integrate components: of oscillations originating in the base of the petiole and of oscillations of leaf blade the centrum of which is localized in the basal third of the blade.
The arrangement of the experiments did not enable us to determine to what extent the phototropic response of leaf blade participates in leaf movements. The movements of leaves of an intact plant are evidently affected by rhythmic stem oscillations. Stem is an integral part of a system which participates in the transfer of information in plants.

A study was made concerning the effect of the analogues of nucleic acid components upon the seed set inPapaver somniferum L. For the experiments flowers one day after anthesis were used, as the pollination taking place at this flower age had previously been found to be most efficient for the seed set. The solutions of analogues in a 10 per cent sucrose were applied by injecting them into the ovaries three hours prior to pollination. Damage to the ovary by the injection reduces the seed set by about two thirds.
In comparison with control flowers, into which only a sucrose solution was injected, 5-bromouracil at a concentration of 5.2×10^-4 M increases the seed set by about 70 per cent. Uracil brings about the same degree of promotion. The same concentration of 5-bromodeoxyuridine has no significant effect on the seed set. When applied simultaneously with uracil it suppresses its stimulating effect completely. The equimolar mixture of uracil and bromouracil did not cause any significant increase in the number of seeds in the capsules, either.

In barley embryos, treated with N-methyl (¹⁴C)-N-nitrosourea, the alkylation of nucleic acids was much higher than that of proteins and lipids. At a concentration inhibiting the growth of M₁ seedlings to 50%, 0.27% of DNA-guanine was methylated to N-7-methylguanine. In barley DNA, alkylatedin vitro, the presence of 3-methyladenine and 0-6-methylguanine was chromatographically detected.

Auxins (NAA, IAA) inhibited the seed germination of lettuce cv. Cabbage. The auxin-indueed inhibition of seed germination could be overcome if 2-chlorethanephosphonic acid (CEPA, ethrel) or kinetin was added simultaneously. Thus ethylene can also modulate the action of endogenous inhibitors in seed germination.

By comparing maize plants cultivated in standing nutrient solution with those from solutions flowing at different flow rates it has been established that absorption of nitrogen, potassium and especially of phosphorus was increased owing to the flow. There was likewise a relative rise in the distribution of nutrients to the overground parts of the plants. The content expressed per unit dry matter was increased only in the case of phosphorus; with nitrogen and potassium it was slightly lower than in the standing solution. Increasing amounts of iron were required under the conditions of flowing nutrient solutions to prevent chlorosis of the plants. The production of dry matter,NAR andRGR was also increased because of the flow. The flow considerably changed the habitus of the primary roots of the maize plants. The roots were longer, thinner and on the whole they contained relatively less dry matter (RWR). The lengthening of the roots is explained as a response to stimulation by the solution flow-the rheotropism.

Growth measurements on individual polycormones ofScirpus lacustris L. cultivated in hydroponic sand cultures from single rhizome cuttings enabled us to analyse the process of offshoot formation. The time interval in the growth of individual subsequent shoots of one polycormone (plastochron), the final length of the shoot and the number of shoots formed during the growth period are suitable parameters for describing the rhythm of offshoot formation. The interdependence of these parameters and the effect of cutting or shading of individual shoots characterize the translocation of assimilates produced by individual shoots, and their use for the growth of subsequent shoots.

The author compares the activity of ¶-fluorophenylalanine and the effect of a medium without nitrogen on the morphogenesis of hyphae of Achlya ambisexualis ♀. A hyperramification often corresponds to a mode of prelethal development and is observed in the same conditions as an asexual multiplication.

The metabolism of¹⁴C-anthranilic acid (¹⁴C-AA) in kohlrabi (Brassica oleracea L. var.gongylodes L.) and the effect of radiation gamma⁶⁰Co on this metabolism was investigated. In hypocotylar segmnents of seven days old etiolated seedlings¹⁴C-AA was metabolised par, tially to its detoxication product¹⁴C-β-glucoside of AA. Simultaneously L-tryptophan was also formed, which in these plants is a precursor of indolic glucosinolates glucobrassicin and neoglucobrassicin.
The metabolism of¹⁴C-AA was followed for 97 h. Radiation, applied both to seeds and to seven days old plants did not affect the metabolism of¹⁴C-AA substantially. The intermediary reaction AA → L-tryptophan in the biosynthesis of L-tryptophan is not a radiosensitive part of the synthesis of this amino acid. A not too high radiation sensitivity (max. 45%) was observed in the metabolic pathway leading from L-tryptophan to glucobrassicin.

For three consecutive years the content of natural stimulators and inhibitors was observed in leaves and shoots of peach trees. Research was directed to the question of development of flower buds.
The substances under study were isolated from the acidic fraction of ether extracts by means of paper chromatography and their concentration was determined by biological test. The activities of substances which either stimulate or inhibit the growth of oat coleoptiles, were added up. The curve expressing the content of stimulators in shoots in relation to the fresh weight showed its maximum in the period of full growth of shoots (15 June-15 July according to the fluctuating vegetative conditions) and it showed a decreasing tendency at the end of the season. The decline of the curve showing the content of inhibitors is of similar direction but less steep. The trend of substances under study is the same in leaves as in shoots, but their quantity is lower. Stimulation and inhibition effects in individual sampling intervals were added up to make a common curve which seems to express the combined action of stimulators and inhibitors in the plant, which determines its growth pattern.

Der Verlauf von Brdička's serologischer Reaktion bildete ein Beschädigungskriterium der VersuchspflanzeSinapis alba L., die durch folgende Herbizidstoffe behandelt wurde: 2,4-D; 2,45-T; MCPA; Atrazin; Aminotriazol; 4-Phenäthylpyridin in den Konzentrationen 10^-3M, 10^-4M und 10^-5M. Während der polarographischen Bestimmung bewirkten die pathologischen Veränderungen der Pflanze verschiedene Höhen der katalytischen Eiweissdoppelstufen. Bei der oszillopolarographischen Bewertung kam es mit steigender Beschädingung zur Ausgleichung der Einschnitte der Kurvenabhängigkeit dE/dt=f(E). Die benützten Methoden zeigten grösste Veränderungen bei den Derivaten der Phenoxyessigsäure-was den stärksten Beschädigungen der Versuchspflanze entsprach.

Tomato and pear fruit underwent shifts in respiratory metabolism (CO₂ evolution) when ripened at reduced relative humidity (15 to 25% R.H.). A bimodal respiratory spectrum was observed with fruit ripened at low relative humidity; concomitantly, a number of the ripening indices were observed to quantitatively (mainly intensification) and perhaps qualitatively differ from fruit ripened at 80 to 90% R.H. The results suggest that the additional climacteric respiratory burst is coupled to metabolic changes associated with ripening and illustrate the dramatic influence water vapor deficit can have on physiological processes such as ripening.

The structure of the maize root enables one to determine the experimental specific conductivity of conducting and non-conducting tissues for the longitudinal water transfer. Using the method of Farmer and Berger in Huber and Schmidt's modification, successive differences in orders of magnitude were revealed among the experimental specific conductivities of the tissues of pith, cortex, and those of the area with concentrated xylem. The highest values of specific conductivity (cm³ cm^-2 h^-1 at 400 mbar per 5 mm distance, at 20° C) were determined in the area with concentrated xylem (mean value 10 018 cm³ cm^-2 h^-1); in the cortex area values by one order of magnitude lower were obtained (mean value 1 206 cm³ cm^-2 h^-1); in the pith area by two orders of magnitude lower (mean value 167 cm³ cm^-2 h^-1). The tissues of the area with concentrated xylem participated in the experimental root conductivity by 72 per cent, cortex tissues by 27 and pith tissues by one per cent. In this paper the individual tissues of maize root are characterized in detail from the anatomical viewpoint and the possible causes of the differences are discussed.

Pricking one of the cotyledons of aBidens pilosus L. (var.radiatus) seedling decapitated just above the cotyledons four times in succession induces after one minute the dominance of buds on the unaffected side.

Experimental Study of changes in water content during dehydration and rehydration of the Fern: Notochlaena vellea R. Br.-This study takes place after studies made on otherPolypodiaceenFerns. We have shown that, in these ferns, the survival duration was longer for the subterranean organs than for aerial ones. The problem was to show that this difference is due to a lower dehydration of the subterranean tissues. As far as we looked at the total water deficiency, we did not find any significant difference between the leaves and the meristematic parts of the subterranean organs: the main difference is the rate of rehydration which is higher in subterranean parts.