Showing papers in "Naturwissenschaften in 1978"

The Hypercycle: A principle of natural self-organization Part C: The realistic hypercycle

Abstract: Topologic methods are used to characterize a particular class of self-replicative reaction networks: the hypercycles. The results show that the properties of hypercycles are sufficient for a stable integration of the information contained in several self-replicative units. Among the catalytic networks studied, hypercyclic organization proves to be a necessary prerequisite for maintaining the stability of information and for promoting its further evolution. The techniques used in this paper, though familiar to mathematicians, are introduced in detail in order to make the logical arguments accessible to the nonmathematician.

Remote sensing of the environment

Abstract: A short survey of application areas and selection criteria for the different remote-sensing methods is presented. Microwave sensing is still regarded as one of the more progressive methods and its problem of angular resolution and the principle of synthetic-aperture radar are discussed. Experimental results of microwave probing are presented with examples from agriculture, meteorology, and hydrology.

Phase relations between a circadian rhythm and its zeitgeber within the range of entrainment

Abstract: The regular day-night changes in tissues, physiologic functions, and behavior of organisms are based on endogenous rhythmic processes which under constant conditions continue with periods slightly deviating from 24 h. These 'circadian' rhythms have properties of self-sustained oscillators. Under natural conditions, circadian rhythms are synchronized (entrained) to 24 h by periodic factors in the environment, the so-called 'zeitgebers'. In the laboratory, circadian rhythms can also be entrained to periods other than 24 h within certain limits. Data on the phase relationship between the circadian rhythm and an entraining light-dark cycle for vertebrates, insects, plants, and unicellular organisms are reviewed.

A new pheromone of the silkworm moth Bombyx mori

Abstract: The female silkmoth Bombyx mori L. emits a second pheromone component bombykal (E-10, Z-12-hexade-cadien-1-al) in addition to the well-known sexual attractant bombykol (E-10, Z-12-hexadecadien-1-ol). Bombykal stimulates its own specialized and highly sensitive olfactory cells of the male moth. Surprisingly, the aldehyde inhibits the release of the male's wing-fluttering response to bombykol.

Soil infertility in the Amazonian rain forest

Abstract: Extensive mineral alteration in the older land surfaces of the eastern Amazonian lowland has led to complete impoverishment of the soils in respect of their inorganic nutrient contents Large-scale use of this area for agricultural purposes seems impossible In the western Amazonian lowland, younger land surfaces (Pliocene) have developed along with Pleistocene flood plains The mineral alteration in the soil profiles of this area, which are partly characterized by poor drainage, has resulted in impoverishment of soils to a lesser degree These soils can be used to a limited extent for agricultural purposes, especially at the level of a subsistence economy

Toward drugs derived from cannabis.

Abstract: Recent work aimed at the introduction of natural and synthetic cannabinoids as drugs is reviewed. Delta1-Tetrahydrocannabinol (delta1-THC) is mainly investigated as a potential drug against glaucoma and asthma, and as an antiemetic agent in cancer chemotherapy. Cannabidiol is being tried in the clinic against epilepsy and as a hypnotic. Numerous synthetic cannabinoids are currently being investigated as analgetics and as sedative-relaxants.

Chemical structure and biological activities of lipid A's from various bacterial families.

Abstract: The endotoxic principle of lipopolysaccharides (LPS) is localized in their lipid A component. Biological effects of LPS on, for instance, body temperature, blood pressure, and blood picture, are also induced by free lipid A. In contrast to the great variability of the 0-specific chains, the chemical structure of lipid A is much more constant. It is common for Salmonella and similar for other genera of the Enterobacteriaceae. Recently, a number of lipid A's have been recognized that exhibited distinct structural features compared with Enterobacteriaceae. These lipid A's were found to be also distinct with regard to some of their biological properties.

Direct phosphorus transfer from leaf litter to roots

Abstract: [3-5]. The present communication suggests the presence of one pathway for this reduction in the microsomal system that does not seem to have been reported previously. The more exact nature and magnitude of this process in various tissues need to be studied further. The carcinogenicity of Cr(VI) compounds-particularly less water-soluble ones-has been documented [6]. Cr(VI) has also been reported to be mutagenic in bacterial systems [7, 8]. The biological effect of Cr(VI) thus certainly depends on where it is reducedwhether in extracellular spaces or in the cytoplasm or the nucleus of various organ cells. The importance of Cr(VI) metabolism does not diminish by the fact that Cr(III) compounds, at sufficiently high concentrations, have been found to be mutagenic in the Salmonella system (unpublished data). This work has been supported by ERDA grant E(04-3)-34-PA156 and carried out in the laboratory of Dr. B.N. Ames, University of California, Berkeley, whom I would like to thank for his support and advice.

Representation of complex visual stimuli in the brain.

Abstract: A method was developed to investigate transfer properties of neurons in the visual system using pictures of complex visual stimuli. The picture is moved over the receptive field of a neuron so that it can scan it along programmed lines. The activity of the neuron during the scanning procedure is presented in a two-dimensional dot display on scale with the original picture. By superposition of the stimulus and the transfer pattern, one can find out to which detail of a stimulus the neuron responds. Neurons in the first intracerebral relay of the visual system, the lateral geniculate body, reduce a complex stimulus, such as a photograph of a natural environment, to its contours. Cortical cells only respond to contours either of a limited or of a wider range of orientations (simple and complex cells, respectively). But the course of contours is only described by a continuous representation of these contours in the cortical map of the visual field. This is done by the simple cells, which have small receptive fields and thus a higher resolving power, whereas complex cells with their large receptive fields monitor the approximate location of a moving stimulus. The function of these two classes of neurons is discussed in terms of visual behavior, i.e., for fixation, hold, and binocular vergence movements (simple cells), and for detection of moving objects and motor command signals towards these objects (complex cells). These functions are an important condition for foveal vision which is the basis of perception in primates. An important function of orientation sensitivity of simple cells may be the binocular alignment of contours in binocular fusion and stereoscopic vision.

Remote sensing of the atmosphere by VHF radar experiments

Abstract: Problems in atmospheric dynamics, in particular in micro- and mesoscale processes, which can be solved by radar investigations, are summarized. The method of atmospheric radar experiments is described. Some relevant results obtained with the new SOUSY-VHF-Radar are presented, including observations of a warm-front passage, of layered structures, and of vertical and horizontal velocities in the troposphere. A power profile of radar echoes from heights up to the stratosphere proves that the SOUSY-VHF-Radar in its final operating state will be able to investigate structures and dynamics in the mesosphere too.

Yeast-like microfossils detected in oldest sediments of the earth

Abstract: A microfossil named Ramsaysphaera has been identified in the ca. 3400-million-year-old Swartkoppie chert of South Africa. Ramsaysphaera closely resembles in size, shape and all preserved structural details, asporogenous yeasts which have been subjected to dehydration. A similar microfossil called Isuasphaera was recently detected in cherty layers of the ca. 3800-million-year-old Isua quartzite in. SW-Greenland. With the known data about the early earth, the question arises, when and where life originated and by what principles early evolution was ruled.

Carbonaceous Chondritic Material in the Solar System

Abstract: Carbonaceous chondritic matrix material (CCMM) appears to be an important planet-forming unit in the mid-solar system, from the orbits of Mars to that of Uranus. The type specimen for CCMM is the low-temperature (400-500 K) assemblage of clay minerals, organic polymer, magnetite, and Ni-rich iron sulfides which constitutes the black, fine-grained matrix of primitive carbonaceous chondrites. Solar-system objects which appear to be partly or wholly made of CCMM are the satellites of Mars, most asteroids, interplanetary dust, and, perhaps, comets, satellites of the outer planets and the rings of Uranus. CCMM constituents probably formed by low-temperature reactions of higher-temperature condensates with the ambient solar composition gas, or in the case of the organic polymer, by reactions of gaseous species catalyzed by solids.

Simulated in situ growth rates of pelagic marine bacteria

Abstract: crospores in the lightest fractions divided and 2% gave rise to plants (Fig. 1 a, II, c). This represents a 40-fold enrichment of plantlet-forming microspores over the controls. Similar results have been obtained on six separate occasions. Although the relative sequence of the fractions was always the same, a variation in microspore buoyant density of + 7 mg/cm 3 occurred from experiment to experiment. Finer gradation in the gradient phases (ca., 3 mg/ cm 3) led to 13% of the microspores undergoing divisions. If in addition to narrower steps the period of anther culture is extended to seven days, then the frequency was further increased to 30% (Fig. 1 d). The microspores with division potential clearly corresponded to those that stain only lightly with acetocarmine as reported previously [1]. Although very high proportions of microspores in some experiments divided, many later aborted; this problem is also observed in anther culture [1]. It is not known whether this abortion is genetically determined or whether it results from competition for compounds essential to further development. We are now for the first time in a position to attempt to maximize further development of microspores by physiological manipulation of embryogenically enriched populations. The techniques reported here may be of great value for workers wishing to understand more of the biology of embryogenesis in higher plants and should prove to be of widespread application even in species where the yield of embryologically competent microspores is much lower than in N. tabacum.

Stimulation of embryogenesis in Citrus tissue culture by galactose

Abstract: Cyclotella cells possess a number of defined chitin-synthesizing apparatus consisting each of the pore in the silica valve and the underlying specialized structures of the plasma membrane. Fibril synthesis is coupled with the existence of this particle-bearing region of the plasma membrane (these structures are absent under inhibitory culture conditions with no fibril synthesis). Chitin synthesis in CyclotelIa obviously is not an exocytotic process with an involvement of vesicular structures, but a transmembrane event. It is not yet clear whether the observed particles are identical with the chitin-synthesizing granules described [3, 4], or serve to fix the chitin synthetases in this position of the plasma membrane, and maintain the conical invagination against the osmotic pressure.

Metabolic coupling between the alga Oscillatoria redekei and accompanying bacteria

Abstract: Quelle dieses Pheromons ausscheidet. Bei dem Pheromon handelt es sich oftenbar um ein ,,mating stimulant\", das bei Anwesenheit artfremder Weibchen interspezifische Kopulationen ausschliegt. Nach den bisherigen Ergebnissen scheint das Pheromon von den fiberall vorhandenen Hautdriisen oder von Epidermiszellen auf oder in die Cuticula abgegeben zu wetden (~ihnliche Sexuallockstoffe sind aus der Cuticula yon Musciden isoliert worden [2]). Allerdings ist nicht auszuschliel3en, dab das Pheromon beim Putzen auf der K6rperoberfl~che verteilt wird.

Cercaricidal activity of some essential oils of plants from Brazil.

Abstract: Extended screening tests on the cercaricidal activity of various plants from northeast Brazil have shown that the extracts of the leaves and fruits of Piper marginatum, Protium heptaphyllum, and Capsicum annuum show a remarkable effect on the cercaria of Schistosoma mansoni. In the case of the oils of Piper marginatum and Capsicum annuum, 90--96% of the cercaria of Schistosoma mansoni were killed within 15 min. According to the NMR spectra, the active principles of the extracts seem to be water-soluble unsaturated compounds from the oils or their hydrolysis products. Natural substances provide an attractive alternative for preventive actions against schistosomiasis, as the perturbation of the ecological equilibrium of natural waters can be avoided in this manner.

Wind stimuli control vestibular and optokinetic reflexes in the pigeon

Abstract: I , ' ' ' i . . . . i . . . . h . . . . i . . . . ~ ' 0 5. 10. 15. .20. 25.Day Fig. l. The time course of changes in time lag between the two subalar muscles in Omocestus viridulus after bilateral autotomy of the hind-femora. Each point represents 400-600 cycles of subalar activations from the first sequence of one courtship. Vertical bars indicate the standard deviation. The inserts show myograms from the left and right subalar muscle (L, R) before and after bilateral autotomy. Traces of corresponding leg movements are included in the first records

Folding and association of oligomeric enzymes.

Abstract: The spontaneous structure formation of oligomeric enzymes consists of the consecutive ‘folding’ and association of the constituent polypeptide chains. Whether catalytic function is an intrinsic property of the folded monomers may be determined using kinetic reconstitution experiments. It is shown that full activity requires association; the correct assembly of subunits depends on their proper folding. The native structure is determined as the kinetically accessible state of lowest free energy.

A novel cell-fusion method of protoplasts by polyvinyl alcohol

Abstract: Hornissen (Vespa crabro L.) stellen ihre Nesttemperatur auf einen nahezu konstanten Sollwert ein. Das zugrunde liegende Verhalten ist das W~irmen der verdeckelten Brutzellen (Puppen) [1]. Die Analyse des W~irmungsverhaltens zeigt, dab die Ausl6set ftir dieses Verhalten aus zwei Hauptkomponenten bestehen. So 'wird bei den Imagines nur dann W/irmungsverhalten ausgel6st, wenn auger dem Druck der Puppe auf die Zellwand gleichzeitig chemische Reize vorhanden sind [2]. Im Biotest wurden jungen Hornissen (Innendiensttieren) Brutzellen geboten, die neben einem Stein, der dem Gewicht (350-400 mg) einer Hornissenpuppe entsprach, Substanzen aus Puppen bzw. frischen Brutzellen enthielten. Uber Thermoelemente wurde die Temperatur wghrend des Versuchs gemessen und registriert, so dab zweifelsfrei entschieden werden konnte, welche der gebotenen Zellen WS.rmungsverhalten ausl6ste. Arbeiterinnenpuppen, K6niginnenpuppen und frische Brutzellen wurden 2 4 h i m Soxhlet-Apparat mit Di/ithyl/ither extrahiert. Dieser Extrakt wurde auf die Zellwand aufgetragen und erwies sich im Biotest als reizwirksam. Die anschlieBende diinnschichtchromatographische Auftrennung (Kieselgel 60 F254) wurde auf Fertigplatten mit einer Schichtdicke von 0,25 bzw. 0,5 mm durchgeffihrt. Als Laufmittel diente eine Mischung aus n-Hexan und Chloroform (1:4). Unter Standardbedingungen [3] wurde dann eine aktive Fraktion mit einem RfWert yon 0,67 gefunden, die gaschromatographisch und massenspektrometrisch analysiert wurde. Der Gaschromatograph (S/iule 3% O V 1, Sfiulentemperatur 250 ~ war direkt mit einem Massenspektrometer gekoppelt, wobei die Massenspektren durch einen Prozel3rechner registriert wurden. Die Auswertung der Massenspektren ergab, dab die biologisch akrive Fraktion ein Gemisch aus ges/ittigten und unges/ittigten Kohlenwasserstoffen mit 23-31 Kohlenstoffatomen ist. Die als Hauptkomponente auftretende Verbindung besitzt das Molekulargewicht 350 und die Summenformel C25Hs0 (durch hochaufl6sende Massenspektrometrie erhalten). Das massenspektrometrische Fragmentierungsverhalten dieser Verbindung sowie ihre F/ihigkeit, eine alkalische Permanganat-L6sung zu entffirben, zeigen eindeutig das Vorliegen yon Pentacosen an. Die Lage der Doppelbindung im Pentacosen wurde chemisch-massenspektrometrisch ermittelt, indem die Doppelbin'dung zunfichst mit OsO4 oxydiert und das entstandene Diol in das entsprechende Acetonid iibergeftihrt wurde [4]. Aufgrund der massenspektrometrischen Fragmentierung der Acetonid-Funktion konnte die Doppelbindung im Pentacosen der Position 9 zugeordnet werden. Die Synthese des 9-Pentacosens gelang durch eine Wittig-Reaktion, ausgehend vom Cetyl-triphenyl-phosphoniumbr omid und Nonanal unter Verwendung von Butyllithium als Base [5]. Das entstandene 9Pentacosen wurde durch prfiparative Gaschromatographic gereinigt und massenspektrometrisch identifiziert. Im IR-Spektrum des synthetisierten 9-Pentacosens treten zwei Banden ffir transund cis-Isomere auf, dagegen enthfilt das IR-Spektrum der Substanz biologischen Ursprungs nur eine Bande ffir das cis-9-Pentacosen. Die mit der synthetisierten Verbindung durchgeffihrten biologischen Tests verliefen positiv. Folglich ist cis-9-Pentacosen ein Ausl6ser ffir das W~irmen der Brutzellen bei Hornissen.

The messinian salinity crisis

Abstract: Two major discoveries made by the deepsea drilling during the last decade were the discovery of the Late Miocene desiccation of the Mediterranean Sea and of the Late Miocene glacial advance of the Antarctic. The coincidence in timing suggests a causal connection between the two. The desiccation of the Mediterranean may have been the catalytic event which led to a momentous expansion of the Antarctic ice cap. Or conversely, a world-wide lowering of the sea level as a consequence of Antarctic glaciation rriay have closed off a shallow connection between the Atlantic and the Mediterranean and resulted in the isolation and eventual desiccation of the latter. A paper by Adams et al. [1] presented evidence to support a contention that there was indeed a eustatic drop of sea level during the late miocene time, and that this world-wide change was the cause of the Messinian salinity crisis. Stratigraphical data from widely separated regions of Australia, of Fiji, of Marshall Islands, of North and South Florida, and of Spain have been evaluated; they all show a stratigraphic hiatus including the Messinian timespan. My associates and I have discussed various, far-reaching geomorphic, climatic, zoogeographic, and paleobotanical changes of the circum-Mediterranean world, when the water levels within the Mediterranean basins were drastically lowered. An appreciable eustatic lowering of sea level would have world-wide consequences and leave an impressive geological record behind. Perhaps the record is indeed so extraordinary that one Japanese geologist was moved to write a book and spinned a yawn of a 2000-m eustatic sealevel change since the Late Miocene [2]. While I do not for one minute believe in that tall figure, it may nevertheless be worthwhile that we take a closer look at some of his strange tales. Since the precise dating of the numerous events of the Late Miocene is fraught with difficulties, we may never be able to decide if the Messinian Antarctic glaciation was the cause or the consequence of the Mediterranean desiccation. It seems satisfying that the isolation of the Mediterranean could be explained by a slight drop of sea level, so that we need not postulate an orogenic uplift of the Betic Portal at a rate exceeding the erosive power of invading Atlantic waters. On the other hand, we must then look for another cause to explain the explosive expansion of Antarctic ice cap; we could not relate the glaciation which caused the eustatic change to the extraction of 6% of the dissolved salt in the world, or to an increased albedo effect when an appreciable portion of a darkblue sea was replaced by a white salt desert. Of course, the workings of nature is commonly more sophisticated than we normally dare to assume. Cause and effect were perhaps interacting in such a way that the final resonance was the two Messinian catastrophes: the Antarctic glacial advance and the Mediterranean desiccation. K.J. Hsti Swiss Federal Institute of Technology, Zurich

Social synchronization of the activity rhythm in a cave-dwelling insectivorous bat

Abstract: can be the determining factor specific to the species tested and differences in these structural orders may specify the adult tissue pattern in other species too. A comparable situation exists in the aggregation stage of slime mold [7], where the cells are spread out in two dimensions and the original center of the aggregate becomes the anterior tip of the slug, retaining its dominant role later. The segregation of specialized cells at two poles of the aggregate and directed development based on this pattern also has phylogenetic significance. The origination of sponges has been ascribed to the symbiosis of flagellate and ameboid cells [8]. One can visualize how in an aggregate with such an assembly of cells the functional order would be initiated by designing the pattern with specific localization of different cell types.

Field-focusing nuclear magnetic resonance (FONAR)

Abstract: A technique, field-focusing NMR (FONAR), is described for doing NMR scans in large samples. The method utilizes a shaped D.C. magnetic field that confines the NMR-signal-producing region of the sample to a small volume called the resonance aperture. The aperture contains the required values of the H o field to fully bracket the band of the r.f. pulse. The magnet system and r.f. pick-up coil that achieved the first human NMR scan is discussed.

The mutagenicity of hexavalent chromium is decreased by microsomal metabolism.

Abstract: Es liegen oktaedrische PtI~-Baugruppen vor, die entsprechend der Bauformel ~[PtI~IgI~/2 ] fiber zwei Spitzen zu unendlichen Ket ten verknfipft sind. Diese Ket ten werden fiber siebenfach koordinier te Alkal ikat ionen (trigonales MI6-Prisma mit zusfitzlichem I vor einer Seitenflfiche) verknfipft. Die Pt-I-Abstfinde zu den endstfindigen I s und I~, die das Pt in F o r m eines nahezu unverzerr ten Quadrates umgeben, entsprechen mit etwa 265 p m der Summe der kovalenten Radien von Pt(IV) und Iod und den von den verschiedenen PtI4-Modif ikationen bekannten Werten [1 3]. Das die Verknfipfung bewirkende Iv besetzt statistisch eine 8-zS.hlige Lage mit ha lbem Gewicht. Es ist um ca. 25 pm aus der Lage auf einer Spiegelebene im Schwerpunkt zwischen den beiden P t -Atomen (Pt-PtAbs tand 593 pm) in Richtung auf ein PtA t o m verschoben. Die unsymmetrische IBr/icke (Pt-I: ~ 270 und ~ 320 pm) ffihrt dazu, dab innerhalb einer Kette PtI6-Oktaeder und PtI4-Quadrate alternieren. Bei den hier erstmals beschriebenen Verb indungen des Typs M2PtIs handel t es sich um eine neue Gruppe von Vertretern der in der letzten Zeit wegen ihrer interessanten physikalischen Eigenschaften besonders intensiv untersuchten Platinverbindungen mit gemischter Valenz und der allgemeinen Zusammensetzung PtX3.2L, wobei bier an Stelle des sonst fiblichen Amins die Lewisbase L = I tritt.

Leaf arrangement: Geometry, morphogenesis, and classification

Abstract: The striking universality of the occurrence of Fibonacci numbers in phyllotaxis is analyzed. Geometric investigation shows that Fibonacci patterns are intimately related to the golden divergence angle along the genetic spiral. A simple argument is presented to make this angle plausible by considering inhibitory action in primary pattern formation. The various types of leaf arrangement are related to the spatial and temporal range of the inhibitory influences.

Principle and technique of field-desorption mass spectrometry

Abstract: The principle and technique of field-desorption mass spectrometry is described briefly. As is demonstrated for some corrin derivatives and vitamin B12 as examples, the method of field desorption extends the range of mass-spectrometric analysis considerably. The molecular weights of substances that are not amenable to conventional mass-spectrometric techniques can be determined. Recent results show that the most important application of field-desorption mass spectrometry will be in the field of biochemical, medical, and environmental analysis.

Biochemical and ecological similarities in marsh plants and diving animals

Abstract: Higher plants which can survive flooding have certain ecological and biochemical similarities with diving reptiles, birds, and mammals. The ecological similarities arise from the fact that these wet-land plants and diving animals are all terrestrial organisms which have re-entered the aquatic habitat as a retreat or ecological refuge free from interference by dry-land species. To survive in the wet-land or aquatic habitat species of terrestrial origin have to restrict their metabolic rate in the absence of oxygen and exploit a wide range of metabolic products to aid proton disposal and avoid the dangers of cell toxicity due to the accumulation of an excessive oxygen debt. In some plants metabolic adaptation to anoxia (low oxygen supply) resembles that found in animal parasites. It is a striking example of metabolic co-evolution that the retreat of so many terrestrial species of both plants and animals back to the low-oxygen habitat has been made possible by the exploitation of similar biochemical control mechanisms and pathways.