Versuch einer Kausalanalyse der geotropischen Reaktionskette im Chara-Rhizoid

Summary In the initial phase of the geotropical reaction of the Chara rhizoid the growth difference postulated by Sievers (1967c) between the physically upper, slightly subapical flank and the lower one is demonstrated. In horizontal exposure the growth of the extreme cell apex is continued, while the growth of the lower flank is inhibited and that of the upper one is promoted. In the end phase the cell apex shows a damped oscillation until it finally reaches the vertical growth direction. The statoliths follow the oscillating growth of the cell tip from one flank to the opposite one until they are statistically equally redistributed in their normal position.—In vertical exposure under reduced turgor pressure the statoliths fall down into the extreme cell apex, where they inhibit the growth of this part of the cell wall, while the subapical wall grows transversally.—It is concluded that the statoliths inhibit the growth of the cell wall area which they cover.—The physical phase of the reaction chain, the susception, is the gravity-induced downward displacement of the statoliths. The physiological phase starts with the diversion of the acropetal transport of the Golgi vesicles to the upper part of the cell, which is caused by the block of statoliths (perception). The greater rate of vesicle incorporation into the upper flank in comparison to the lower one causes the subapical growth difference which results in the curvature (reaction).—In the case of the Chara rhizoid Golgi- and statolith-apparatus function as a self-regulating cellular system.

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Herrn Prof. Dr. Dr. h. c. Kurt Mothes zum 70. Geburtstag.     

The isolation and genetic analysis of aCaenorhabditis elegants translocation (szT1) strain bearing an X-chromosome balancer

A single X-chromosome balancer-bearingCelegans ♂+, as a founder of a strain (AF1), was isolated directly from Fl progeny of irradiated+dpy-8unc-3/lon-2++ hermaphrodites on the basis of the absence of recombinant F2 categories. The balancer chromosome (Bal-X-1) suppresses recombination over a two-thirds section of the X chromosome (between genesdpy-8 andlet-2) and is associated with a reciprocal translocation between linkage groups (LG) X and I. Animals homozygous for the translocation (szT1(X:1)) are nonviable. Hermaphrodites heterozygous for the translocation segregate male selfprogeny at a frequency of 0.08-0.12.Bal-X-l carries the marker mutationlon-2(e678) and can be detected cytologically. This balancer chromosome proved useful for rnaimaininga number of X-linked lethal mutations and deficiencies inC. elegans.     

Catecholamine im Hypothalamus vom Goldfisch (Carassius auratus)

Zusammenfassung Mit der fluoreszenzmikroskopischen Methode zur Lokalisation von Catechol- und Tryptaminen wurden im Hypothalamus von Carassius auratus zwei bisher unbekannte catecholaminhaltige Kerngebiete gefunden. Sie liegen in der Pars posterior des Lobus medius hypothalami und werden Nucleus recessus posterioris und Nucleus recessus lateralis genannt. Aus diesen Kerngebieten gehen vier markarme Bahnen hervor, die ungekreuzt verlaufen und innerhalb des Hypothalamus endigen. Verschiedene pharmakologische und histochemische Befunde legen die Vermutung nahe, daß die fluoreszierende Substanz im Hypothalamus Noradrenalin ist. Eine Abgabe von biogenen Aminen in den Liquor cerebrospinalis wird für möglich gehalten.

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Summary The hypothalamus of Carassius auratus was investigated by means of the method for fluorescence-microscopical detection of catechol- and tryptamines. The hypothalamus was found to contain two hitherto unknown nuclei with specific catecholamine-fluorescence. They are situated in the pars posterior of the lobus medius hypothalami and are termed nucleus recesaus lateralis and nucleus recessus posterions. The unmyelinated axons of these nuclei give rise to four different tracts which run uncrossed in the frontal direction and terminate within the hypothalamus. Their course is described in detail. According to the results of histochemical and pharmacological tests it is assumed that the fluorescent substance in the hypothalamus is noradrenaline. The two nuclei are bordering the ventricular wall and are thought to secrete catecholamines into the cerebrospinal fluid.

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Mit dankenswerter Unterstützung durch eine Sachbeihilfe der Joachim-Jungius-Gesellschaft zur Förderung der Wissenschaften, Hamburg.     

Dynamics of the immune system response in cerebrospinal fluid and blood of SIVmac-infected rhesus monkeys

Paired sera and CSF samples were collected from SIV_mac-infected macaques. Animals infected with SIV_mac251 maintained low gag and high env-specific antibody levels in plasma. Increasing env-specific antibody titers in CSF were associated in one animal with strong intrathecal synthesis. SIV_mac239-infected monkeys revealed high antibody titers of gag and env-specificity, in one animal accompanied by weak intrathecal synthesis of virus-specific antibodies. In all animals, the CD4/CD8 ratio in CSF decreased faster compared to blood.     

The IleL229 → Met mutation impairs the quinone binding to the QB-pocket in reaction centers of Rhodobacter sphaeroides

A spontaneous mutant (R/89) of photosynthetic purple bacterium Rhodobacter sphaeroides R-26 was selected for resistance to 200 M atrazin. It showed increased resistance to interquinone electron transfer inhibitors of o-phenanthroline (resistance factor, RF=20) in UQ_o reconstituted isolated reaction centers and terbutryne in reaction centers (RF=55) and in chromatophores (RF=85). The amino acid sequence of the Q_B binding protein of the photosynthetic reaction center (the L subunit) was determined by sequencing the corresponding pufL gene and a single mutation was found (Ile^L229 Met). The changed amino acid of the mutant strain is in van der Waals contact with the secondary quinone Q_B. The binding and redox properties of Q_B in the mutant were characterized by kinetic (charge recombination) and multiple turnover (cytochrome oxidation and semiquinone oscillation) assays of the reaction center. The free energy for stabilization of Q_AQ_B ^– with respect to Q_A ^–Q_B was G_AB=–60 meV and 0 meV in reaction centers and G_AB=–85 meV and –46 meV in chromatophores of R-26 and R/89 strains at pH 8, respectively. The dissociation constants of the quinone UQ_o and semiquinone UQ_o ^– in reaction centers from R-26 and R/89 showed significant and different pH dependence. The observed changes in binding and redox properties of quinones are interpreted in terms of differential effects (electrostatics and mesomerism) of mutation on the oxidized and reduced states of Q_B.Abbreviations BChl bacteriochlorophyll - Ile isoleucine - Met methionin - P primary donor - Q_A primary quinone acceptor - Q_B secondary quinone acceptor - RC reaction center protein - UQ_o 2,3-dimethoxy-5-methyl benzoquinone - UQ₁₀ ubiquinone 50 This work is dedicated to the memory of Randall Ross Stein (1954–1994) and is, in a small way, a testament to the impact which Randy's ideas have had on the development of the field of competitive herbicide binding.     

Theoretical studies on animal orientation. I. Methodological appraisal of classifications

Research on animal orientation shows a persistent lack of integration. Theories entertained in different “schools” are couched in incommensurable terms. The underlying definitions mostly do not satisfy elementary canons of methodology, and this results in a confusion of empirical and conceptual problems. Application of basic methodology shows that current classifications of orientation patterns are logically incomplete.Moreover, allegedly distinct kinds of orientation wrongly show logical dependencies resulting from poor definitions. Reference to physiological mechanisms, beyond stimuli and responses, must be omitted from definitions for orientation patterns. Likewise, orientation must not be made functional (adaptive) by definition. Vagueness is to some extent unavoidable in general theories.