Reaktionsmuster verschiedener Mittel-und Zwischenhirnzentren von Rana temporaria L. nach Unterbrechung der Nervenbahnen des Pinealkomplexes

Zusammenfassung Der Einfluß des lichtempfindlichen Pinealkomplexes (Stirnorgan und Epiphysis cerebri) von Rana temporaria auf dorsale diencephale und mesencephale Hirnzentren breitet sich über ein größeres Gebiet aus als man bisher angenommen hat. Nach operativer Unterbrechung des Nervus- und Tractus pinealis wurde mit Punktzählverfahren die Dichte der Zell- und Zellkernvolumina sowie der Kapillaroberfläche im dorsalen Thalamus, mesencephalen (postthalamischen) zentralen Grau, Ganglion habenulae, Tectum opticum, in der Area praetectalis und im Subcommissuralorgan (Sco) bestimmt. Die morphometrischen Meßergebnisse lassen sich wie folgt interpretieren: 1. Der Pinealkomplex wirkt auf das Sco, das zentrale Grau und die Area praetectalis ein (vgl. Paul u. Mitarb., 1971); das Sco wird in erster Linie über das Stirnorgan beeinflußt. 2. Weitere Kerngebiete des Zwischenhirns (Ganglion habenulae und dorsaler Thalamus) gehören funktionell zu dem vom Pinealkomplex kontrollierten System. 3. Die von Kemali und Braitenberg (1970) beschriebene Asymmetrie der Ganglia habenularum zeigt sich auch im funktionellen Zusammenspiel dieser Kerngebiete mit dem Pinealkomplex, dem dorsalen Thalamus und dem dorsalen Abschnitt des zentralen Graus. Die in Stirnorgan und Epiphysis cerebri transformierten Lichtreize werden in Hirnabschnitte weitergeleitet, die olfaktorische und retinale Signalmuster verarbeiten. Über die biologische Bedeutung der nervösen Beziehungen des Stirnorgans zum sekretorischen Sco können noch keine Angaben gemacht werden.

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Study of mesencephalic and diencephalic centers after transection of the centripetal nervous pathways of the pineal complex in Rana temporaria L.

Summary Nervous influences of the pineal complex of the frog, Rana temporaria, exerted upon mesencephalic and diencephalic centers were investigated using morphometric methods after the transection of the nervus or the tractus pinealis. Densities of the cell- and nuclear volumes and of the capillaries were measured by a point-counting method in the dorsal thalamus, the mesencephalic (postthalamic) central gray, the habenular ganglion, the optic tectum, the pretectal area, and the subcommissural organ (sco). The morphometric measurements showed: 1. A functional influence of the pineal complex on the sco, the central gray, and the pretectal area (see Paul et al., 1971); the frontal organ seems to be primarily related to the sco. 2. The habenular ganglia and the dorsal thalamus belong to a system which is controlled by the pineal complex. 3. The morphological asymmetry of the habenular ganglia (Kemali and Braitenberg, 1970) has an influence on the functional interactions between the pineal complex, the dorsal thalamus, and the central gray. The impulses arising in the light-sensitive pineal complex of the frog are conducted to brain regions which are known to integrate olfactory and retinal sensory inputs. The functional significance of the nervous connexion of the frontal organ with the secretory sco is still open to discussion.

Mit Unterstützung durch die Deutsche Forschungsgemeinschaft (Arbeitskreis Prof. Dr. A. Oksche).     

Burkholderia cepacia lipase: A versatile catalyst in synthesis reactions

The lipase from Burkholderia cepacia, formerly known as Pseudomonas cepacia lipase, is a commercial enzyme in both soluble and immobilized forms widely recognized for its thermal resistance and tolerance to a large number of solvents and short‐chain alcohols. The main applications of this lipase are in transesterification reactions and in the synthesis of drugs (because of the properties mentioned above). This review intends to show the features of this enzyme and some of the most relevant aspects of its use in different synthesis reactions. Also, different immobilization techniques together with the effect of various compounds on lipase activity are presented. This lipase shows important advantages over other lipases, especially in reaction media including solvents or reactions involving short‐chain alcohols.     

Haplotyping cryptic Adélie penguin taxa using low-cost,high-resolution melt curves

Distinguishing morphologically cryptic taxa, by definition, requires genetic data such as DNA sequences. However, DNA sequences may not be obtained easily for taxa from remote sites. Here we provide the details of a high-resolution melt-curve-based method using taxon-specific primers that can distinguish two taxa of Adélie penguins, and that will be usable in Antarctica when combined with some of the newly developed field-deployable thermal cyclers. We suggest that the wider adoption of field-deployable polymerase-chain-reaction-based techniques will enable faster assignation of haplotype to individuals in situ, and so allow the targeting of observations and sample collection to specimens relevant to the research question. Targeting individuals will also reduce the need to repeatedly handle animals and reduce the time and travel required to complete field work.     

Bootstrapping the Energy Flow in the Beginning of Life

This paper suggests that the energy flow on which all living structures depend only started up slowly, the low-energy, initial phase starting up a second, slightly more energetic phase, and so on. In this way, the build up of the energy flow follows a bootstrapping process similar to that found in the development of computers, the first generation making possible the calculations necessary for constructing the second one, etc. In the biogenetic upstart of an energy flow, non-metals in the lower periods of the Periodic Table of Elements would have constituted the most primitive systems, their operation being enhanced and later supplanted by elements in the higher periods that demand more energy. This bootstrapping process would put the development of the metabolisms based on the second period elements carbon, nitrogen and oxygen at the end of the evolutionary process rather than at, or even before, the biogenetic event.     

Structural heterogeneity in waxy-rice starch

Alpha-amylase of B. amyloliquefaciens was used for the structural characterization of the amylopectin from waxy-rice starch. Fractions of -dextrins with a degree of polymerization (d.p.) <5000 were isolated from amylopectin hydrolysates after 1 and 3 h. φ,β-Limit dextrins were prepared by successive phosphorolysis and beta-amylolysis of the fractions and these were analysed by a second alpha-amylolysis. Based on the hydrolysis pattern, the limit dextrins were divided into two major groups, A and B, which possessed units of clusters of d.p. 100–200 and 90–130, respectively. An extensive alpha-amylolysis resulted in characteristic distributions of dextrins with d.p. <80 which represented branched building blocks. Type A dextrins possessed more larger building blocks with d.p. 40, but less intermediate and small blocks, than type B. The φ,β-limit dextrin of the original amylopectin had a distinct distribution enriched in small building blocks. A model is proposed in which the two types of dextrins originate from regular and less regular structural domains of the amylopectin fraction within the starch granules.     

Kinetic Mechanisms of Biological Regulation in Photosynthetic Organisms

Principles of regulation on different levels of photosynthetic apparatus are discussed. Mathematical models of isolated photosynthetic reaction centers and general system of energy transduction in chloroplast are developed. A general approach to model these complex metabolic systems is suggested. Regulatory mechanisms in plant cell are correlated with the different patterns of fluorescence induction curve at different internal physiological states of the cells and external (environmental) conditions. Light regulation inside photosynthetic reaction centers, diffusion processes in thylakoid membrane, generation of transmembrane electrochemical potential, coupling with processes of CO₂ fixation in Calvin Cycle are considered as stages of control of energy transformation in chloroplasts in their connection with kinetic patterns of fluorescence induction curves and other spectrophotometric data.     

Drones,automatic counting tools,and artificial neural networks in wildlife population censusing

1. The use of a drone to count the flock sizes of 33 species of waterbirds during the breeding and non‐breeding periods was investigated.
2. In 96% of 343 cases, drone counting was successful. 18.8% of non‐breeding birds and 3.6% of breeding birds exhibited adverse reactions: the former birds were flushed, whereas the latter attempted to attack the drone.
3. The automatic counting of birds was best done with ImageJ/Fiji microbiology software – the average counting rate was 100 birds in 64 s.
4. Machine learning using neural network algorithms proved to be an effective and quick way of counting birds – 100 birds in 7 s. However, the preparation of images and machine learning time is time‐consuming, so this method is recommended only for large data sets and large bird assemblages.
5. The responsible study of wildlife using a drone should only be carried out by persons experienced in the biology and behavior of the target animals.

     

An HPLC‐ESMS study on the solid‐phase assembly of C‐terminal proline peptides

DKP formation is a serious side reaction during the solid‐phase synthesis of peptide acids containing either Pro or Gly at the C‐terminus. This side reaction not only leads to a lower overall yield, but also to the presence in the reaction crude of several deletion peptides lacking the first amino acids. For the preparation of protected peptides using the Fmoc/tBu strategy, the use of a ClTrt‐Cl‐resin with a limited incorporation of the C‐terminal amino acid is the method of choice. The use of resins with higher loading levels leads to more impure peptide crudes. The use of HPLC‐ESMS is a useful method for analysing complex samples, such as those formed when C‐terminal Pro peptides are prepared by non‐optimized solid‐phase strategies. Copyright © 1999 European Peptide Society and John Wiley & Sons, Ltd.