Showing papers in "Naturwissenschaften in 1975"

Amino acid racemization reactions and their geochemical implications

Abstract: The amino acids present in living organisms consist mainly of the L-enantiomers. Over long periods of geological time, amino acids undergo a slow racemization, producing the z~-enantiomers. The amino acids contained in fossil materials show an increasing extent of racemization with age. The kinetics and mechanism of amino acid racemization and the applications of this reaction in geochronology and paleothermometry are discussed.

Ecology and evolution of agonistic behavior in stomatopods

Abstract: Stomatopods are marine crustacea which occupy cavities and burrows on most of the world's tropical reefs and beaches. They are highly aggressive and defend their burrows using a raptorial appendage capable of inflicting lethal blows. Morphologically, the raptorial appendages of stomatopods can be divided into two types, spearing and smashing. Those species possessing the smashing appendage, which is the more potent of the two forms, show heavier telson armor, agonistic repertoires which are more intense and complex, and tend to occupy homesites such as cavities in rock or coral which are scarce as compared to the availability of burrow sites for spearers. Within a group of species from one habitat, the most aggressive is usually the most abundant, suggesting contest competition.

The effect of dibenzoxanthenes on the paralyzing action of zoxazolamine

Abstract: I n Three-month-old male Wistar rats weighing approximately 100 g were fed for a week on a vitamin-rich, synthetic diet [2], which they continued to receive during the experiments. Compounds (I) and (II) were administered by intraperitoneal injection, in solution in maize oil, the controls receiving the solvent only; 24 h later, zoxazolamine (2-amino-5-chlorobenzoxazole) was given intraperitoneally, at dose of 70mg/kg. Total paralysis occurs after 1 or 2 min, and its duration was measured; reduction in the duration of the zoxazolamineinduced paralysis parallels an increase in the level of the hydroxylase which inactivates zoxazolamine [1, 3 5]. It can be observed (Tables 1 and 2) that, as far as compounds (I) are concerned, not only the inducing power shown by (1) and (2) completely disappears with the modification of the nature of R but some of the compounds increase the paralyzing effect of zoxazolamine by retarding its hydroxylation in vivo. This has been manifested by the compounds (4), (6), (9), (10), and (II). In the case of dibenzo[c, h]xanthenes, only the meso-diethyl derivative (16) shows an inhibiting power to some extent. The rest of the compounds proved to be completely inert. These new findings thus confirm our previous conclusions, that the biochemical effect exerted on zoxazolamine hydroxylase synthesis depends essentially on the nature of the substituent in the meso-position. It is thus clear that the most important factor is the overall thickness of the molecule and that there must be an optimum configuration for the compound in order to fix itself properly to the substrate. We have already arrived at the same conclusion with other polycyclic systems [5-7]. It is interesting to note, on the other hand, that some of dibenzoxanthenes are good inhibitors and they differ from inducers only in their molecular geometry. This is a further confirmation of the hypothesis that the inhibitors, to begin with, attack the same cellular targets as the inducers do; but because of the difference

Growth and decay of the Laurentide Ice Sheet and comparisons with Fenno-Scandinavia

Abstract: The history of thought relating to the initiation, growth, and decay of the Laurentide Ice Sheet is traced and the traditional hypothesis of \"highland origin and windward growth\" is re-examined. Extensive field data from Labrador-Ungava and Baffin Island are reviewed in a climatological context. An alternative conceptual model of \"instantaneous glacierization\", based on a late Neoglacial extensive snow cover over much of the eastern Canadian Arctic and Subarctic, is proposed. Comparisons with Fenno-Scandinavia are made in the light of this new model.

Biological cycles for elements in the environment

Abstract: Initially, living systems evolved in the absence of oxygen, and we still have anaerobic bacteria which contain many coordination complexes which catalyze reactions of great importance (e.g., vitamin B12 in methane biosynthesis). Later, molecules of greater design evolved for the purpose of reducing anions such as sulfate and nitrate (e.g., Heme in nitrate reductase). Finally, complexes evolved to deal with molecular oxygen. The initial inorganic matrix of this planet has left its stamp, because metals are involved in every aspect of biosynthesis, biodegradation, and in the assembly of macromolecular structure. If you think that biochemistry is the organic chemistry of living systems, then you are misled; biochemistry is the coordination chemistry of living systems. We can arbitrarily define metals from a biological standpoint as being in three groups: (l) Light metals. These are usually transported as mobile cations, e.g., Na +, K +, etc. (2) Heavy metals. These are metals which function in catalysis in biological systems, e.g., iron, cobalt, copper, molybdenum, etc. (3) Heavy metals and metalloids which are toxic to biological systems, e.g., mercury, platinum, gold, silver, palladium, selenium, tellurium, etc. The uptake of metals by living organisms depends on three important criteria: (1) the availability of the metal, (2) the presence of those ligands which will chelate metals in living systems, and (3) the geometry of the coordination complexes which the metal and ligands allow. In order to be taken up by living organisms, metals must be available and abundant. Fig. 1 presents the

Imaging of macroscopic objects by NMR Fourier zeugmatography

Abstract: I t has recently become possible [t] to obtain twoor threedimensional images o5 living biological organisms, or of other objects, by means of a new nuclear magnetic resonance technique, called zeugmatography. A set of linear magnetic-field gradients is used to obtain a spatial dispersion of the signals received from various parts of an object. The method is of particular I interest because it could supply a nondestructive technique for cancer detection in living biological systems. This possibility is based on the fact that the water-proton spin relaxation time of cancerous tissue is significantIy longer than tha t of normal tissue [2].

Ein neuer Typ Silylphosphane; (me3Si)3P7, (me3Si)4P14, (me=CH3)

Abstract: einer Glasziehvorrichtung bis zu einem Spitzendurchmesser von < 0,2 pm reproduzierbar hergestellt wird. Die mechanische Festigkeit der Glasspitzen wird durch eine Kombination yon thermischer Behandlung, FluBsgureeinwirkung, Hfirtung durch Ionenaustausch sowie durch Elektronenbeschul3 erh6ht [4]. Auf diese Glasbzw. Quarz-Spitzen wurden mit der Hochfrequenzzerst/iubungsanlage Sputron II (Firma Balzers, Liechtenstein) Edelmetallschichten aufgebracht [5]. Die Haftfestigkeit der Edelmetallschichten wurde durch vorhergehende Glimmentladung und anschliel3endes Aufbringen einer dfinnen Tantal-Zwischenschicht erreicht. Zur elektrischen Isolierung des Elektrodenschaftes wurden, in Weiterentwicklung der f/Jr die Pn-Mikroelektrode entwikkelten Technik [6], Mehrfachschichten hochisolierender Dielektrika abwechselnd aus verschiedenen Oxiden und Nitriden mit der HF-Zerst/iubung aufgebracht. So lassen sich Elektroden mit koaxialer Anordnung der Schichten herstellen. Form und Gr6f3e der akdven Mel3oberfl/iche k6nnen durch Maskieren mit Photolack oder durch Schleifen bestimmt werden. Es entstehen entweder konusf6rmige Spitzen, z.B. mit einem Durchmesser kleiner als 1 ~tm, oder ringf6rmige ElektrodenoberfI~ichen (schriiger Anschliff im Winkel yon 3 0 4 0 °, Fig. 1). Zur Messung des absoluten Sauerstoffdruckes werden zwei gasdurchl/issige Membranen, z.B. aus Polystyrol und Kollodium, aufgebracht. Ftir Wasserstoffdruckmessungen werden die aktiven Edelmetallschichten galvanisch palladiniert [7].

Evolution of sequences within protein superfamilies

Abstract: A protein superfamily, within which the sequences are recognizably related, usually encompasses all structures that diverged less than 400 million years ago and that changed mainly by point mutation. Many superfamilies extend throughout all eukaryotes or throughout a major division of bacteria, while the proteins of some superfamilies occur in all living organisms. All proteins may belong to fewer than 000 distinct superfamilies. To illustrate the new understanding which emerges from such an organization, four important superfamilies are presented: two groups of hormones, the immune-system proteins, and the c-type cytochromes.

The lanthanides as spectroscopic and magnetic resonance probes in biological systems

Abstract: The trivalent lanthanide ions, by virtue of the multitude of their spectroscopic and magnetic properties, are suitable as probes in studies of macromolecular environment, structure, and interactions. The approach is illustrated with examples from optical absorption, fluorescence, circularly polarized luminescence, nuclear magnetic resonance, X-ray diffraction, and other physical techniques. In order to evaluate the significance of the approach, the activation and inhibition of enzymatic reactions by lanthanides is reviewed.

3-chloroindole, principal odorous constituent of the hemichordatePtychodera flava laysanica

Abstract: 50%) free endogenous tryptophan available to the culture because o f decreased activity oftryptophan synthetase, as compared to iow-phosphate culture. Further, when tryptophan was initially supplemented (100 mg/l) to the high-phosphate cultures, they also yielded 100 mg alkaloid per liter. The above results clearly indicate that high concentrations of inorganic phosphorous decrease the synthesis of tryptophan, ultimately inhibiting the synthesis of alkaloids. These observations further support our earlier findings [7J that tryptophan, due to its precursoric nature stimulates alkaloXd synthesis in Aspergittusfumigatus as it does in the clavicep,; species.

A new absolute asymmetric synthesis

Abstract: Der e infache ana ly t i s che Nachwei s ge r inger S pu ren yon S 2i s t ffir F ragen des U m w e l t s c h u t z e s (Wasser u n d L u f t r e inha l t ung ) , der t e chn i schen E i g e n s c h a f t e n der Metal le u n d der Kor ros ion yon groBer B e d e u t u n g . Bet U n t e r s u c h u n g e n fiber die ka tho d ische A b s c h e i d u n g yon Silber a u s cyan i d i s chen E lek t ro ly t en in G e g e n w a r t yon S2--Ionen w u r d e beobach te t , dab s ich bere i t s S2--GehaIte yon < I p p m an t den Verlauf der Po ten t i a l s t r o m d i c h t e k u r v e n auswirken . Mit Hi l fe dieses Ef fek tes is t es mbglich, sehr ger inge S2--Gehal te in w~sser igen L 6 s n n g e n an t e infaehe Weise g e n a u zu b e s t i m m e n . I n Fig. t s ind ffir e inen E l e k t r o l y t e n m i t 80 g Silber/l [NAg (CN)2 ] u n d 200 g f re iem KCN/1 die u n t e r St ickstoff bet R a u m t e m p e r a t u r po t en t i o s t a t i s ch a u f g e n o m m e n e n ~ a t h o d e n p o t e n t i a l s t r o m d i c h t e k u r v e n wiedergegeben. Als K a t h o d e d ien te ein t c m 2 groBes Feins i lberblech . Se tz t m a n d e n E l ek t ro ly t en Na~S bis zu e iner K o n z e n t r a t i o n yon 0,06 p p m S 2zu, so t r i t t bet P o t e n t i a l w e r t e n yon e twa -0 ,6 V (gegenfiber ge sg t t i g t e r Ka lomel -Elek t rode) e in S te i l ans t ieg der S t romd i ch t e bis zu e inem M a x i m u m bet e twa -0 ,8 V u n d 1,6 A / d m ~ ein. Bet h6he ren S p a n n u n g e n f~illt die S t romd i ch t e d a n n wieder auI die W e r t e der S2--Ireien E lek t ro ly t e ab. Bet n e g a t i v e n K a t h o d e n po t en t i a lwe r t en yon fiber -0 ,9 m V ve r l au fen die Po ten t i a l s t r 0 m d i c h t e n k u r v e n ffir das SZ--freie u n d das S2--hal t ige B a d gleich. Die Abh~ng igke i t des S t r o m d i c h t e m a x i m u m s v o m S 2-Geha l t i s t a u s Fig. 1 zn e n t n e h m e n . D a n a c h e rh6hen 1,3 p p m S 2bet e i nem Po ten t i a l y o n -0 ,8 V die S t romd i ch t e gegenf~ber e inem S2--freien E l e k t r o l y t e n u m das e twa t 5fache. Die A u s b i l d u n g des S t r o m d i c h t e m a x i m u m s k a n n u . a . du rch die E l e k t r o l y t z u s a m m e n s e t z u n g beeinflui3t werden . Die Versuche ergaben, dab je nach Ka t hoden f I~che zwischen 2 u n d 0,01 p p m S 2g u t n a c h w e i s b a r stud. Das beobach t e t e Verha l t en der S i lbe rka thode in S2--hal t igen cyan id i schen S i lbere lek t ro ly ten n n d die V e r w e n d u n g zur Bes t i m m u n g yon ge r ingen S2--Mengen b e r u h e n auf der e x t r e m e n Schwer l6s l ichkei t des AgaS u n d der als Folge d a v o n au f t r e t en den R e a k t i o n

Hirnforschung am Navigationssystem der Fliegen

Abstract: Flies control their course and altitude by reference to landmarks. An analysis of their responses has revealed the general features of a network of movement detectors which seems to cover every segment of the visual field. The investigation of the control system has been facilitated by the availability of mutant genes which block specific groups of information channels in the fruitfly, Drosophila. Given the appropriate mutants, it appears feasible to analyze the functional elements of the control system, and to gain an insight into the genetic instructions which determine the thousands of quite specific interconnections in the underlying neuronal network.

Possibilities of using insectistatics and pheromones in pest control.

Abstract: Agents that can decimate insect populations by suppressing growth and reproduction rather than by causing rapid mortality are called insectistatics. Their activity includes interruption of cuticle formation, induction of hormonal imbalance by extrinsic juvenoids or ecdysoids, developmental disturbances due to nutrient antagonists, symbioticides, or accelerators of metabolism. Disruption of mating may be accomplished by pheromone trapping and disorientation or by prevention of sex attraction. The possible contribution of such biotechnical procedures to the control of storage pests is discussed.

Some new toxic compounds in false morels, Gyromitra esculenta.

Abstract: 50%) free endogenous tryptophan available to the culture because o f decreased activity oftryptophan synthetase, as compared to iow-phosphate culture. Further, when tryptophan was initially supplemented (100 mg/l) to the high-phosphate cultures, they also yielded 100 mg alkaloid per liter. The above results clearly indicate that high concentrations of inorganic phosphorous decrease the synthesis of tryptophan, ultimately inhibiting the synthesis of alkaloids. These observations further support our earlier findings [7J that tryptophan, due to its precursoric nature stimulates alkaloXd synthesis in Aspergittusfumigatus as it does in the clavicep,; species.

Age-trend in carbon isotopic composition in Paleozoic sediments

Abstract: Average 6 ~3C values of organic carbon in marine Paleozoic sediments of the Rheinisches Schiefergebirge in northwest Germany and adjacent areas were determined. They exhibit a trend towards heavier isotope values during Middle Devonian through Carboniferous. This age-trend in isotope values is interpreted as a result of increasing photosynthetic activity. It was probably caused either by the massive emergence of land plants during Devonian time and/or by increasing water temperatures of Devonian oceans.

Autonomous circadian rhythms in man. Singly versus collectively isolated subjects.

Abstract: Autonomous circadian rhythms in man have been investigated not only with subjects singly isolated from environmental time cues, but also with groups of subjects collectively isolated. This paper deals with a comparison of both types of experiments. First, the courses of the group experiments are similar to those of the single experiments. In all of 10 group experiments with two subjects each, the subjects living together were mutually synchronized with regard to their circadian rhythms. In most group experiments, the rhythms were internally synchronized (Fig. 1, left). I n some of the group experiments, internal desynchronization occurred spontaneously, as it did in single experiments; i.e. different rhythms within each subject ran with different periods in a steady state (Fig. 1, right). Remarkably, in group experiments not only the activity rhythms of different subjects within the group were mutually synchronized, but also the vegetative rhythms which run with another period (e.g. rectal temperature rhythms). This result is supported by the sequence of the temporal positions of rectal temperature extreme values originating from two subjects and alternating from day to day; sections with separate rhythms are, however, too short to yield conclusive results. The result mentioned means that mutual social contacts among subjects act as mutual Zeitgebers, independent of each other with regard to the different rhythms. With the occurrence of internal desynchronization, the periods of the different rhythms presented change into opposite directions. The ratio of these period alterations is 1:12 (cf. Fig. 1, right), which is in accordance with a multi-oscillator model derived from single experiments [1]. Second, there are slight but significant differences between single and group experiments with respect to the periods.

Structure and function of the endoplasmic reticulum

Abstract: After a general review of enzyme topology and the molecular architecture of endoplasmic reticulum the latest research results are discussed. Microsomal enzymes do not occur in specialized regions of the endoplasmic reticulum but are uniformly distributed over the entire membrane system. Functionally associated enzymes are also located in the direct vicinity of the membrane. It has been shown that the catalytic activity of integral enzyme proteins depends on phospholipid and membrane structure. These membrane-bound lipoproteid complexes exert specific effects as vectorial enzyme catalysts. The endoplasmic reticulum is active is active in the intracellular transport of metabolites.

[Living-polymerization and enzymatic synthesis of polysaccharides].

Abstract: The kinetics of anionic polymerization are shown to be largely analogous to those of enzymic polycondensation )amylose synthesis). The two systems are compared as regards their capacity to synthesize linear and branched polymers of well-defined size and shape.

Effect of toxins of sea anemones on neuromuscular transmission.

Abstract: In various mold cultures two fluorescent spots with Rf-values, similar to those of aflatoxin B2 and G1 were observed, but UV-absorption spectra showed that these two substances differed from aflatoxin B2 and G~. By adding ~4C-marked aflatoxin B~ to cultures of A. niger it was proved that these unknown substances originated directly from aflatoxiu B1. Both blue fluorescing compounds have been accumulated and characterized by UV-, fluorescence, and mass spectrometry. The molecular peaks of both fluorescing products were 314 m/ e. A characteristic peak at 296 m/e results from loss of one water molecule. The highest maximum of the UV-spectrum was shifted from 362 nm (aflatoxin Bt) to 328 nm. These facts

Temperature regulation in the slow loris.

Abstract: Fig. I. (a) View of a tumorous subculture of C. capgllar'is with unstable, variable karyotypes (strain TA). (b) (g) Metaphase plates of six established clones from tumorous strains; in each case the abnormal karyotype was present in all dividing cells of the relevant subculture. The tissues were pretreated for 3 h in liquid nutrient medium containing 0.1% colchicine, fixed in ethanol/acetic acid (3:1) and stained with acetic orcein. (b), (c) Strain TH, (d) strain Th, (e) strain TD, (f) strain TG, (g) strain TA