Contributions to the productivity of the littoral region of pools and ponds

Summary During a quantitative study of the littoral zooplankton of a backwater, temperature as well as some chemical conditions have been measured at monthly intervals throughout two years. All three stations with different types of vegetation showed during the daytime steadily higher temperatures near the surface than did the openwater station. pH, oxygen and alkalinity showed a clear dependence on the photosynthetic and respiratory activity of plants. At the station with a concentration of leaves of Nuphar, Hydrocharis, Myriophyllum, and Ceratophyllum near the surface, a remarkable vertical stratification of temperature and chemical factors were observed.Crustacea exceeded numerically the Rotatoria, the mean ratios for the warm seasons ranging from 1.9 to 4.8 : 1, at stations with emergent vegetation, and from 5.0 to 13.0, at stations with submerged vegetation. A spring (May) maximum of the littoral species, mainly Chydorus, was followed by an increase of tycholimnetic Cladocera during June–September; this was followed by a fall maximum of littoral Cyclopidae. In the case of the lower spring maximum of littoral species in 1954, a more abundant development of pelagic Rotatoria and of Ceriodaphnia was observed. The littoral and tycholimnetic or pelagic species seem to substitute for one another. Two types of life-cycles may be distinguished: The littoral species have mostly a well defined spring maximum and a less defined fall maximum, the tycholimnetic species, a summer maximum. At the station with submerged vegetation, Crustacea as well as Rotatoria were more concentrated near the surface than below it, the concentrations observed being five-fold for Crustacea, and two-fold for Rotatoria. Two phases may be distinguished, the pelagic, lasting from November until June, and the littoral, lasting from late June until October.The Labíko backwater had nearly ten times the concentration of littoral zooplankton, as the tarns observed by Smyly; this may be attributed to the generally greater productivity and denser vegetation of the former. The standing crop of the littoral zooplankton, expressed in organic nitrogen, reached 1 to 1.5 mg/l and 2 to 5 mg/dm². In comparison with the free-water region, the littoral zooplankton of the backwater was more concentrated per unit of volume, but had a lower standing crop per unit of surface area.

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Zusammenfassung Das litorale Zooplankton des Altwassers Labíko wurde in monatlichen Abständen studiert und Temperaturmessungen und chemische Analysen ausgeführt. Alle drei untersuchten Stationen mit verschiedener Vegetation zeigten während des Tages eine erhöhte Temperatur in Vergleich mit der pelagialen Region. pH, Sauerstoff and SBV zeigten eine deutliche Abhängigkeit von der photosynthetischen und respiratorischen Aktivität der Pflanzen. Auf der Station mit der Oberflächenanhäufung der Blätter von Nuphar, Hydrocharis, Myriophyllum und Ceratophyllum erschien eine markante vertikale Stratifikation der Temperatur und der chemischen Faktoren.Crustaceen überschritten die Rotatorien im numerischen Durchschnittsverhältnis (für die warmen Perioden) 1.9 bis 4.8 mal auf den Stationen mit der emergenten Vegetation and 5.0 bis 13.0 mal auf den Stationen mit submerser Vegetation. Einem Frühlingsmaximum der Litoralformen (hauptsächlich Chydorus) folgte eine erhöhte Zahl der tycholimnetischen Cladoceren im Juni–September nach. Dieses wurde durch das Herbstmaximum der litoralen Cyclopidae ausgelöst. In dem Falle eines niedrigen Frühlingsmaximum der Litoralformen im Jahre 1954 fand ein Aufsteig der pelagialen Rotatorien and Ceriodaphnien statt, was eine Substitution der litoralen and tycholimnetischen oder pelagialen Formen andeutet. Man kann zwei Typen von Lebenszyklen unterscheiden: Litorale Arten haben meistens ein gut ausgeprägtes Frühjahrsmaximum und ein weniger deutliches Herbstmaximum, während die tycholimnetischen Arten ein Sommermaximum aufweisen. Auf der Station mit submerser Vegetation sind Crustaceen sowie Rotatorien in der Oberflächenschicht viel mehr konzentriert als unter derselben (fünfmal, bezw. zweimal im Durchschnitt). Hier kann mit zwei Phasen gerechnet werden, einer pelagialen zwischen November und Anfang Juni and einer litoralen zwischen Ende Juni and Oktober.Das Altwasser Labíko hat ungefähr zehnmal höhere Konzentrationen des litoralen Zooplanktons als die von Smyly beobachteten Teiche, was der allgemein höheren Produktion und dichteren Vegetation des Altwassers zugerechnet werden kann. Die im Stickstoff ausgedrückte Biomasse des litoralen Zooplanktons erreicht 1.0–1.5 mg/l und 2–5 mg/dm₂. Im Vergleich zu der Freiwasserregion, ist das litorale Zooplankton des Altwassers mehr konzentriert, hat aber eine niedrigere Biomasse per Flächeneinheit.

     

Effect of lowered incubation temperatures on nucleic acid and protein synthesis by a mesophilic and a psychrophilic bacterium

The authors studied changes in the synthesis of nucleic acids (RNA, DNA) and protein by a mesophilic strain ofEscherichia coli B and a psychrophilic strain ofPseudomonas fluorescens at a low incubation temperature giving tenfold prolongation of the generation time. It was found that lowering the incubation temperature was followed by an increase in the intracellular nucleic acid content during the lag phase and the phase of accelerated growth, in which maximum nucleic acid (NA) values were reached. As a result, the total NA level in the cell also remained relatively high during further proliferation, when the increase in NA (particularly RNA) slows down at low incubation temperatures. Proteosynthesis, however, fell in the mesophilic culture. The smaller effect of a lowered temperature on DNA biosynthesis was manifested specifically in the lag phase ofEscherichia coli, in which disproportion developed between the amount of DNA (which was synthesized at a relatively higher rate) and RNA; this was afterwards equalized by a temporary break in DNA production. Pronounced differences in the given types of biosynthesis were found only in the mesophilic culture, while at suboptimal temperatures the metabolism of the psychrophilic strain slowed down but no marked changes occurred.     

Preparation of anti-inhibitor serum and its effect on the multiplication of influenza virus

Antiserum был подготовлен противингибитор вируса haemagglutination (IVH)одна из эмбриона chorioallantoic мембр анныепутем иммун изации морских св инокЭто анти-инги битора в сыворотке заблокирован ингибирование IVH из chorioallantoicмембран в haemagglutination испытанияно ника кого влияния на ре цепторы эритроци товСыворотке кро] ви не влияет рост chorioallantoic мембраны клет ок инет нейтрализ овать воздействи е на вирус гриппа Она снизилась спо собность chorioallantoic мембр ан для adsorb вируса гри ппа, а также степен ь размножения вир усав такого рода тканиАвторы хоте ли бы поблагодари ть г-н Г. Ruttkay-Ne -палубе и для проведения эле ктрофореза меру ния.     

Morphology and function of the Golgi apparatus

The polymorphism of the dictyosomes in the root meristeme ofFagopyrum is connected with their various functions in secretory processes and cell differentiation. The dictyosomes containing vesicular dilatations of the cisternae, which in this object occur more frequently than in others, probably participate in a similar way as the Golgi apparatus of the animal cell in the formation of lysozomes, in the formation of elements belonging to the group of dense bodies analogical lysozomes. These bodies are present in large numbers in the cytoplasm of cells, containing dictyosomes with vesicular dilatations. The other forms of the dictyosomes reveal indications of their participation in the production of the carbohydrate material of the cell walls, like most dictyosomes of other plant objects. However, no fusion of the Golgi vesicles with the plasmalemma was observed. According to their morphological appearance the typical forms of dictyosomes were classified on the basis of their relationship to secretory processes. Simultaneously the morphology and function of the Golgi apparatus was compared in the animal and plant cell. Several morphological varieties of the dictyosomes of plant cells, observed after the action of pathogenic factors and the effect of the fixation procedures, were also noticed in small quantities in the cells of the investigated objects.     

Stand microclimate and physiological activity of tree leaves in an oak-hornbeam forest

Summary In an uneven-aged, multi-species oak-hornbeam forest at Báb, SW Slovakia (former IBP Forest Research Site), a series of micrometeorological and ecophysiological measurements started in 1985. The aims of the work are to improve understanding of physiological processes (photosynthesis, respiration, and transpiration) of adult trees and stand microclimate, to collect data for simulation of the canopy (stand) photosynthesis and for ecological synthesis of the functioning of the forest ecosystem. In this paper, photosynthetically active radiation (PAR), air temperature (AT) and relative humidity (RH), wind speed (WS), and CO₂ concentration ([CO₂]) in and above the forest are characterized for the fully leaved season, using diurnal courses, vertical profiles and isodiagrams (isopleths). Approximately 50% of incident PAR was absorbed by the upper 4–5 m layer of leaves and only approximately 5% or less penetrated to the forest floor. Vertical gradients of AT and RH were generally low, but large differences in diurnal ranges of AT and RH were observed between vertical levels. The upper leaf canopy greatly reduced WS, and at a height of about 14 m above the ground it was close to zero. The highest diurnal [CO₂] maximum and variations occurred at 1 m above the ground, and the lowest above the forest. In good light conditions in the forest, the entire leaf canopy (overstorey and understorey canopy) is a large sink of CO₂. At night the forest stand is a source of CO₂, the largest internal source being the soil and forest floor.