Absolutes und relatives Wachstum bei Ammonoideen

The following basic growth parameters of the ammonoid shell are analysed: radius of the coiling spiral; whorl width; plane of cross-section; umbilical spiral. The absolute growth of these parameters follows a general growth formula which is based on the probability theory (time-dependent stochastic processes). The in crease of all basic parameters is ruled by analogous formulas which are derived from the general growth formula; the increase of the coiling spiral results in the geometrical figure of a logarithmic spiral, because this is the only one that meets the conditions of the general growth formula. The relative growth can be described as a morphogenetic program that is subdivided in presumably three formally connected subprograms. Each subprogram is defined by specific allometry and integration constants.
Folgende Grundparameter des Wachstums von Ammonoideen-Gehäusen werden analysiert: Radius der äuβeren Spirale, Windungsbreite, Querschnittsfläche, Nabelspirale. Das absolute Wachstum dieser Parameter folgt einer allgemeinen Wachstumsformel, die sich aus der Wahrscheinlichkeitstheorie (zeitabhängige stochastische Prozesse) ergibt. Die Zunahme aller Grundparameter folgt analogen Formeln, die sich aus der allgemeinen Wachstumsformel ableiten lassen; das Anwachsen des äuβeren RadiS führt zur geometrischen Figur einer logarith-mischen Spirale, da nur diese der allgemeinen Wachstumsformel genügt. Das relative Wachstum läβt sich als ein morphogenetisches Wachstumsprogramm beschreiben, das sich in vermutlich drei formal miteinander verknüpfte Unter-programme aufteilt. Jedes Unterprogramm ist durch spezifische Allometrie- und Integrationskonstanten festgelegt.     

Spin Trapping Study in the Lungs and Liver of F344 Rats after Exposure to Ozone

Fischer 344 rats were injected with the spin traps C-phenyl N-tert-butyl nitrone (PBN, 150 mg/kg bw, ip) or 4-pyridine-N-oxide N-tert -butyl nitrone (POBN, 775 mg/kg bw, ip), and exposed to clean air or 2 ppm ozone for two hours. The presence of spin adducts was determined by electron paramagnetic resonance (EPR) spectroscopy of chloroform extracts of lung and liver homogenates. No significant levels of adducts were detected in the lungs of air control animals. Benzoyl N-tert-butyl aminoxyl, attributed to direct reaction of ozone with PBN, and tert-butyl hydroaminoxyl, the scission product of the hydroxyl adduct of PBN, were detected in the lungs of ozone exposed rats. EPR signals for carbon-centred alkoxyl and alkyl adducts were also detected with PBN in the lungs and liver of animals exposed to ozone. With POBN, only carbon-centred alkyl radicals were detected. Senescent, 24 months old rats were found to retain about twice more ¹⁴C-PBN in blood, heart and lungs by comparison to juvenile, 2 months old animals. Accordingly, the EPR signals were generally stronger in the lungs of the senescent rats by comparison to juvenile rats. Together, the observations were consistent with the previously proposed notion that a significant flux of hydrogen peroxide produced from the reaction of ozone with lipids of the extracellular lining, or from activated macrophages in the lungs could be a source of biologically relevant amounts of hydroxyl radical.     

Invertebrate colonization of a new, man-made stream in southern Sweden

SUMMARY.

• 1 The invertebrate colonization of a man-made stream, Flugströmmen, in southern Sweden was monitored for 18 months in 1988 and 1989. Benthic samples were taken on twelve occasions from three sites (upstream, middle and downstream) and community structure was compared with that at ten natural, permanent reference sites nearby.
• 2 The number of species colonizing increased rapidly during the first 3 months. The increase was most rapid upstream but levelled off during the second year at this site, while numbers continued to increase downstream.
• 3 Simuliid species were the earliest colonizers and reached high densities at upstream and middle sites during the first year. Ephemeropteran and plecopteran species also occurred early on, whereas Coleoptera, Odonata and Trichoptera were, on average, slower to colonize. Blackfly densities decreased upstream after the first year and hydropsychids became numerically dominant.
• 4 The colonization order of functional feeding groups was as predicted: filter feeders first, grazers/collectors intermediate, predators and shredders last.
• 5 After a year, the community structure in Flugströmmen closely resembled that in lake-outlet streams situated in the area, although communities at the three sites within the stream were most similar to one another.
• 6 The possible role of competitive and predatory processes in determining the observed successional patterns are discussed.

     

Inhibition of photosynthetic electron transport and formation of inactive chlorophyll in winter stressed Pinus silvestris

Kinetics of fluorescence at room temperature, electron transport and photooxidation of P700 and cytochrome f have been studied in chloroplasts isolated from active and winter stressed Pinus silvestris. The winter stress induced block in the electron transport chain between the two photosystems is close to the site of plastoquinone, since winter stress and DCMU caused the same type of inhibition of the reoxidation of the primary electron acceptor Q of photosystem II. No winter inhibition of the electron transport between cytochrome f and P700 was observed. Time course studies of P700 photooxidation in chloroplasts of active and winter stressed pine have shown that the photosynthetic unit size must be about equal in the two types of chloroplasts. An apparent increase of the photosynthetic unit size was induced by winter stress, as revealed by the high chlorophyll/P700 ratio of winter stressed pine. The phenomenon is explained by the formation of photosynthetically inactive chlorophyll. Low-temperature fluorescence emission spectra were recorded when either chlorophyll a (433 nm) or chlorophyll b (477 nm) were preferentially excited. Winter stress induced the formation of a chlorophyll a fraction emitting at 673 nm. This chlorophyll is most likely derived from the chlorophyll a antennae of the two photosystems, and it probably contributes to the photosynthetically inactive pool of chlorophyll in winter stressed pine. The light harvesting chlorophyll a/b complex is relatively resistant to winter stress.     

Phycochromes b and d: their occurrence in some phycoerythrocyanin-containing blue-green algae (cyanobacteria)

Abstract
Phycochromes b and d, two types of photoreversibly photochromic pigments previously extracted from the blue-green alga Tolypothrix distorta , which contains phycoerythrocyanin, have now been found in three Anabaena strains also containing phycoerythrocyanin. Tests for the presence of phycochromes b and d in a number of blue-green algae lacking phycoerythrocyanin have been negative. The possibility that phycochrome b-type absorbance changes are due to changes in the α-subunit of phycoerythrocyanin is discussed.     

Some effects of humidity on the light reaction of photosynthesis in the lichens Cladonia impexa and Collema flaccidium

Luminescence and fluorescence were measured at different relative humidities in the lichen Cladonia impexa Harm. Both parameters showed a constant value at relative humidities lower than 80%: thereafter they increased. Low relative humidity was found to decrease energy transfer from chlorophyll b to chlorophyll a. inhibit electron transport, lower electron holding capacity on the reduced side of photosystem two and impair far-red-induced afterglow, reflecting photophosphorylation. In Collema flaccidium Ach. Ach. energy transfer from the accessory pigments phycocyanin and phycoerythrin to chlorophyll a was only possible at high relative humidity. The results are interpreted as due to conformational changes caused by changed water content in the lichen.     

Measles Virus-Specific IgG in Cerebrospinal Fluid in Multiple Sclerosis

The prevalence of measles virus-specific IgG in cerebrospinal fluid (C.S.F.) of patients with multiple sclerosis (M.S.) has been compared with that in fluids from patients with other neurological diseases and from normal control subjects. The prevalence in the three groups was 58·1%, 24·1%, and 0% respectively. Fivefold concentration of the specimens increased the prevalence in the first two groups to 80·6% and 34·5% respectively, while measles IgG was not detected in any fluids of the normal control group, even after concentration.     

Decarboxylation and Transport of Auxin in Segments of Sunflower and Cabbage Roots. II. A Chromatographic Study Using IAA-1-14C and IAA-5-3H

The polar movement of IAA has been examined in 5-mm root segments of Brassica oleracea and Helianthus annum. The movement was studied partly with IAA-1-¹⁴C and partly with IAA-5-³H. In both plants a slight acropetal flux of ¹⁴C and IAA-³H was found through the segments. The recovered radioactivity in the agar receiver blocks and in the receiver end of the segments increased as a function of time. A large portion of the applied IAA was converted on the cut surfaces and in the tissues of the segments. Chromatographic analysis indicated different destruction products when estimated by scintillation counting and by spraying with in-dole reagent (DMCA). Chromatograms run in isopropanol: ammonia: water, 8:1:1, yielded three different substances, one spot near the starting line and one near the front, neither of which has been identified. Finally there was a spot with R_f 0.4–0.6, probably representing IAA.     

1:1 Distribution between Induced Mutants and Phenocopies

BY ultraviolet irradiation of germiings of the multicellular alga Ulva mutabilis Føyn, it is possible to obtain chimaeric plants which consist of two morphologically different parts of different genetic constitution, one part wild type and the other mutant^{1, 2}. Other plants found have been identical in appearance to the chimaeras, though the morphologically different parts were both genetically wild type. They should be considered phenocopies of the genetic chimaeras. Surprisingly, the genetical chimaeras and their phenocopies were found in equal numbers. This observation and the previous one that only complete mutations are found after ultraviolet irradiation of Ulva cells¹, can be explained if only one of the two strands in the DNA molecule is genetically conserved.     

The State of Protochlorophyll and Chlorophyll in Corn Roots

The protochlorophyll(ide) present in primary roots of dark-grown corn (Zea mays) seedlings has an in vivo absorption maximum at 634 nm. Red light converts the pigment to chlorophyll(ide) a with an absorption maximum at 675 nm.