Showing papers in "Naturwissenschaften in 1972"

Formation and diagenesis of inorganic Ca−Mg carbonates in the lacustrine environment

Abstract: Lacustrine formation of primary carbonate minerals (calcite, high-Mg calcite, aragonite, hydrous Mg carbonates) and of secondary carbonates (dolomite, huntite and magnesite), as determined from 25 lakes with differing hydrochemistry and salinity, is dependent on the Mg/Ca ratio of the lake or pore water, respectively. Secondary carbonates are found only in lake sediments with high-Mg calcite and a Mg/Ca ratio of more than seven. The only difference between non-marine (including speleothems) and marine carbonates is the absence of calcite in the marine environment.

The growth of large diamond crystals

Abstract: Large diamond crystals up to 6 mm in average diameter may be grown at high pressures (55–60 kbar) and temperatures (1400–1500 °C) by causing diamond to dissolve in a molten catalyst metal (Fe, Ni, Co, etc.) in a hot region and deposit upon a seed crystal in a slightly cooler region. Several days are required to produce a high quality single crystal. The process can be controlled to produce different kinds of diamonds whose properties have been studied.

Cytochalasin stops tip growth in plants

Abstract: Th ioha rns to f f w i rk t bei v ie len S a m e n k e i m u n g s f 6 r d e r n d [1]. Bei pos i t iv pho tob l a s t i s chen S amen k a n n er oft das L i ch t erse tzen, so dab S a m e n anch i m D u n k e l n ke i men [2]. Bei den n e g a t i v pho tob l a s t i s chen S a m e n yon Phacelia h e m m t Thioha rns to f f die K e i m u n g i m D u n k e l n s chwach u n d verst&rkt die 1 4 e i m n n g s h e m m u n g du rch L ich t [3]. Hier wird yon einer f6 rde rnden W i r k u n g auf die L i c h t k e i m u n g der nega t iv pho to b las t i schen [4] S a m e n von Zygophyllum coccineum L. ber ichter . Die S a m e n w u r d e n in W a d i Hof in der &gypt isch-arabischen Wi i s te im Sep tember 1970 ge sammel t . Zur K e i m u n g k a m e n sie bei 25 ~ in Pe t r i scha len (50 S a m e n pro Schale) auf eine Lage Fi l terpapier , die m i t 5 ml dest. W a s s e r oder der T h i o h a r n s t o f f L 6 s u n g getr&nkt war. Be l ich te t wurde mi t We ig l i ch t in e inem L i c h t s c h r a n k ( K I ( B 600L der Fa. Heraeus , H a n a u ; Leuch ts to f f rShren , Licht intensi t~i t in H6he d e r Schalen ca. 2 0 0 0 L u x ) . Jeder Ansa t z wurde 6fach durchgef t ih r t u n d die Ergebnisse gemi t te l t . Der P rozen t s a t z der geke imten S a m e n wurde fiber 7 Tage in 24s t f ind igem A b s t a n d festgestel l t , wobei als geke imt S a m e n gal ten, deren Ke imwurze l eben s i ch tba r geworden war. A m E n d e des Versuchs w u r d e die L~nge des H y p o c o t y l s und der Wurze l ermi t t e l t .

Schwermetalle in Sedimenten von Donau, Rhein, Ems, Weser und Elbe im Bereich der Bundesrepublik Deutschland

Abstract: Uber den Verbleib umweltgef~hrdender Schwermetalle liegen bislang keine Daten vor. Als sicher gilt lediglich, daB der grSBte Teil der Schwermetalle aus dem industriellen, landwirtschaftlichen und h~uslichen Bereich in fester, kolloidaler oder gelSster Form tiber die FlieBgew~tsser in die Weltmeere gelangt und dort angereichert wird, Blei z.B. bereits um den Faktor 5 0 [1 ]. Die Messung der Schwermetallgehalte in den Flul~w~tssern ergibt vielfach ein unklares Bild fiber das AusmaB der Verunreinigung, da Anderungen in der Wasserffihrung, unterschiedliche Betonung einzelner Liefergebiete oder kurzfristige lokale Emissionen tempor~ire Schwankungen in der Schadstofftihrung yon mehreren GrSBenordnungen verursachen kSnnen. Bei der Untersuchung des Schwebgutes, dessen mineralische und organische Komponenten eine hohe Sorptions-F~higkeit ffir Schwermetall-Ionen besitzen, ergeben sich nahezu dieselben Variationsbreiten [2]. Erst l~ngerfristige Messungen fiber mehrere Jahreszyklen hinweg, wie sie z.Z. von verschiedenen Arbeitsgruppen im Schwerpunktprogramm ,,Schadstoffe im Wasser\" der Deutschen Forschungsgemeinschaft durchgeffihrt werden, kSnnen zu verl~tBlichen Anssagen ffihren. Bis zum Vorliegen entsprechender Daten erscheinen uns die tonigen Sedimente der Flfisse als geeigneter Gradmesser ftir eine Erkennung der Belastung eines FlieBgew~tssers mit Schwermetallen. Da Sedimente aus vielen Schichten aufgebaut sind, deren jede einzelne einer bestimmten Schwebgutffihrung im flieBenden Wasser entspricht, liefern sie indirekt einen Mittelwert ffir die Schwermetallbelastung des Schwebgutes fiber einen l~ngeren Zeitraum. In der vorliegenden Studie fiber die Belastung yon FluB-Sedimenten mit SchwermetaUen wird eine Stoffgruppe untersucht, deren unmittelbare oder chronische Gefahr ffir den Menschen durch eine Reihe von schwerwiegenden Unfiillen in jfingster Zeit dokumentiert wird [3--5]. Obwohl vielfach noch keine genauen Vorstellungen fiber die toxischen Grenzwerte der einzelnen Schwermetalle bestehen und auch noch weitgehend unbekannt ist, unter welchen Bedingungen die in oder an die Sedimente gebundenen Schwermetalle mobilisiert werden kSnnen und dann evtl. eine Gef~thrdung des aus der Uferfiltration gewonnenen Trinkwassers darstellen, schien nach den Ergebnissen frfiherer Beobachtungen am Rhein [6--8] eine generelle Bestandsanfnahme der Schwermetallverteilung in den wichtigsten Flfissen der BRD erforderlich. Um vergleichbare Daten zu erhalten, wurde jeweils die Tonfraktion (Anteil kleiner 2 ~m) von Schlammproben atomabsorptionsspektroskopisch auf ihre Gehalte an Quecksilber, Cadium, Zink, Blei, Kupfer, Chrom, Nickel und Kobalt untersucht, die w~thrend des extremen Niedrigwassers im Winter 1971172 aus dem normalerweise fiberfluteten Uferbereich der Flfisse Rhein, Ems, Weser, Elbe und Donau sowie deren wichtigsten Nebenflfissen gewonnen worden waren. Die Ergebnisse der Einzelmessungen ffir Hg, Cd, Zn, Pb, Cu und Cr sind in Fig. t graphisch dargestellt. Tabelle I enth~ilt die Minimal-, Mittelund Maximalwerte s~tmtlicher untersnchten Schwermetalle ffir die einzelnen Flfisse sowie zum Vergleich die Durchschnittsgehalte dieser Elemente in tonigen Sedimentgesteinen [9], die als geochemische Bezugsbasis gelten kSnnen. Die Addition der Mittelwerte aller 8 untersuchten Elemente ergibt ffir jeden FluB mehr als 1000 ppm (0,1%), bei Elbe und Weser werden 2000 ppm (0,2 %) fiberschritten. Der Gehalt an Zink ist bei jedem FluB hSher als alle anderen 7 Elemente zusammengenommen. Ordnet man die in Tabelle t aufgeffihrten Flfisse und Nebenflfisse nach dem Gehalt an einem bestimmten Schwermetall (Mittelwert), so ergibt sich die in Tabelle 2 angeffihrte Reihenfolge.

The presence of was esters in marine planktonic copepods

Abstract: Many of the common calanoid copepods in the sea contain large amounts of an unusual lipid, the wax esters (fatty acids esterified to long chain alcohols). They serve as reserve energy stores which are used during long periods of starvation, e.g. "over-wintering", and for production of eggs. Upper-water copepods have wax esters high in unsaturation, reflecting the high unsaturation of the fat ty acids of their phytoplankton diet, while deep-water copepods have more saturated wax esters.

Struktur und Wirkung der Amatoxine

Abstract: The amatoxins, mainly 0cand fl-amanitine, are the essential lethal poisons of the toadstool Amanita phalloides. Structurally they are cyclic octapeptides whose ring is divided and held in compact shape by a sulfoxide bridge. Chemical changes in the molecule, like scission of one of the rings or alterations at the y=hydroxylated isoleucine side chain, may reduce or even eliminate toxicity. The toxic action can be attributed to a biological property of the toxins operating at molecular level: extremely strong inhibition of one of the eucaryotic RNA polymerases (form II resp. B). Bisnor-deoxy-amanineamide, a synthetic compound having the features of the highly toxic natural products in simplified form, inhibits RNA synthesis by 90% at a concentration of 40 ~tg/ml. I t is t03 times less active than the natural amatoxins and therefore nontoxic.

The behavioural role of the mammalian skin glands.

Abstract: The common occurrence of skin glands, their specialization and responsiveness to physiological variations leave no doubt as to their behavioural importance in mammals and man. The study of their function is, however, hindered by the highly complex behaviour of mammals and the fact that skin glands are not indispensable.

Toxic Proteins Inhibiting Protein Synthesis

Abstract: Proteins which destroy various organisms are widely distributed in nature. Some of these proteins exert their toxic effect by inhibiting protein synthesis in a specific manner. Thus, Colicin E 3 kills susceptible bacteria by inhibiting ribosome function. It does this by splitting off a small fragment from the t6S ribosomal RNA thus inactivating the 30S ribosomal subunit. Diphtheria toxin inhibits protein synthesis in eukaryotes by inactivating peptidyl-transferase II; this enzyme is necessary for the elongation of peptide chains on the ribosomes. Two toxic proteins from plants, abrin and ricin, also apparently interfere with some process necessary for the elongation of already initiated peptide chains. The possible physiological significance of the toxic proteins is discussed. There are in bacteria, as well as in plants and animals, proteins which have a highly toxic effect upon other organisms. Very small amounts of these toxic proteins, often termed "toxins" or "protein toxins", exert a pronounced effect and the lethal dose is often a few ~zg per kg body weight, or even less. Some cells and organs are highly sensitive to the action of a particular toxic protein, whereas others are virtually unaffected. Although their mechanism of action at the molecular level is largely unknown, it has recently become clear that some toxic proteins act by inhibiting protein synthesis.

Isogenic transplantation of ethylnitrosourea-induced tumors of the central and peripheral nervous system in two different inbred rat strains.

Abstract: The selective production of neurogenic tumors in rats by the resorptive carcinogens methyland ethylnitrosourea has become well established in experimental neurooncology [1]. Neurogenic transplantation tumors in inbred animals are useful for the investigation of a number of problems, e.g. histocompatibility or tumor-specific transplantation antigens. Previous isotransplantation experiments proved successful population with various degrees of differentiation and anaplasia. For isogenic transplantation, tumor tissue is inoculated subcutaneously either as minced tumorbrei or as small pieces (25--250 mg tissue/injection) into male and female rats of different age groups. Table t summarizes the percentage of acceptance of transplanted tumor samples and the rate of tumor growth in t h e two rat strains. CNS tumors have a lower rate of acceptance in the first passage than PNS tumors. The rate increases to about t00% after the second passage. Transplanted primary brain tumors are accepted more readily when injected into recipient hosts younger than one month, but age-dependent differences are less marked for PNS tumors. The mean growth rate for accepted CNS tumors in the first passage is generally slower than that for PNS tumors. Transplanted CNS tumors undergo marked sarcomatous changes, usually after the first passage, while the PNS tumors maintain their primary morphological characteristics for several passages. This study has shown that transplantable tumors of the central and peripheral nervous system can be established in inbred rat strains. The changes in morphology and growth behaviour of primary and transplanted tumors will be described in detail.

Pupal coloration in Papilio machaon in response to the wavelength of light.

Abstract: 59. Jg., He]l 6, 1972 Kurze Originalmitteilungen 219 All groups showed a significant increase (Fig. 1) in testis size compared with the winter controIs (p < 0.00t, U test). Testis development was most advanced in the two long-day groups that did not receive melatonin; each of these groups differs significantly from all other groups (p < 0.0t or < 0.00t). In the long-day animals which received melatonin, testis develop- ment corresponded with that of the three short-day groups (no significant differences). Spermatogenic activity, deter- mined by the number of motile spermatozoa in smears from the cauda epididymidis, corresponded well with testis size. Good correspondence between testis size and histological stage has previously been reported in the golden hamster [7]. These data show that a long photoperiod accelerates testicular recrudescense in the dwarf hamster; that melatonin inhibits the influence of the long photoperiod; but that melatonin does not completely suppress testicular development. The experi- ments also suggest that seasonal breeders are better suited for studies of pineal function than the laboratory rat. Thanks are due to Dr. J. Figala, Budejovice, for introducing the hamsters to our laboratory. Received March 9, 1972 [1] Wurtman, R. J., Axelrod, J., Kelly, D. E.: The pineal. New York: Academic Press 1968. -- [2] Reiter, R. J., Era- schini, F. : Neuroendocrinol. 5, 219 (1969).- [3] Reiter, R. J., Sorrentino, S. : Am. Zoologist 10, 247 (1970). -- [4] Rust, C. C., Meyer, R. I<.: Science 16S, 921 (t969). -- [5] Herbert, J., in: The pineal gland (G. E. "vV. Wolstenholme and J. Knight, eds.), p. 303. Edinburgh: Churchill Livingstone 1971.- [6] Hoff- mann, K.: in prep. -- [7] Gaston, S., Menaker, M.: Science 158, 925 (t967).