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.     

Neuronal and Extraneuronal Effects of Intracisternally Administered 6-Hydroxydopamine on the Developing Rat Brain

Abstract: Intracisternal administration of 100 μg 6-OHDA to newborn rats causes permanent defects, not only of the monoaminergic neuron system, but also of extraneuronal tissue elements. The long noradrenergic fibre tracts are irreversibly destroyed, while the short projections recover and regenerate after a transient period of injury. In the major noradrenergic cell group, the locus coeruleus, most of the cells in the caudal and middle parts degenerate, while a small dorsorostral group survives and forms the source of the regenerating fibres. Dopaminergic and serotonergic fibre tracts are also affected. The 6-OHDA treatment also damages granule and dial cells of the cerebellar cortex as well as the mesenchymal cells of the pial coverings of the cerebellum, leading to primitive foliation, absence of fissuration, and defective migration of granule cells and resulting in a marked reduction of cerebellar size, area, and granule cell number.     

Phenylacetic acid in an anaerobic swine manure digester

Summary The presence of phenylacetic acid (PAA) in an anaerobic swine manure digester was determined by gas chromatography of the butyl ester and confirmed by mass spectroscopy. PAA concentration increased during start-up of a digester and with low carbon, high nitrogen loading. Unlike acetate, propionate and butyrate, the concentration of PAA varied little through the day in a stable digester loaded once per day. The laboratory scale digester was loaded at 4 g of swine manure solids/liter digester volume per day. The retention time and temperature were 15 days and 37°C. PAA is a microbial intermediate which is produced by one group of anaerobic bacteria and converted to methane by other members of the bacterial community in the digester. As such, it may be a useful indicator of the relative metabolic activity of the bacterial groups and thus of the overall stability of the anaerobic process.     

MAJOR CLADES OF THE ANGIOSPERMS

Abstract— Our knowledge of fundamental angiosperm interrelationships is still very incomplete. The absence of a narrowly circumscribed gymnosperm outgroup, ideally the sister group, makes character evaluation, necessary for a cladistic analysis, difficult. According to current views the superorder Magnoliiflorae with a number of other groups, for example the monocotyledons, may represent a complex of families near the base of the angiosperms. Interrelationships of groups within the monocotyledons are much better understood than those between groups within the dicotyledons. A cladogram of monocotyledon orders based on earlier work by R. Dahlgren, H. T. Clifford, and F. N. Rasmussen is presented. A data matrix for a sample of the angiosperms with 61 characters for 49 taxa, mostly magnoliifloran and related families, is presented. The characters are polarized mainly according to the current view that the primitive angiosperm morphotype is a woody dicotyledon with strobiloid flowers. As an alternative the matrix is adjusted following W. C. Burger's conjecture that the primitive angiosperm was a herbaceous monocotyledon with trimerous flowers. Both matrices were run in a computerized parsimony analysis, resulting in numerous equally parsimonious solutions. This result is illustrative of the great homoplasy in the available character information, and also of how little actually is known about fundamental angiosperm interrelationships or phylogeny.     

Assignment of orthologous relationships among mammalian alpha-globin genes by examining flanking regions reveals a rapid rate of evolution

In order to study the relationships among mammalian alpha-globin genes, we have determined the sequence of the 3' flanking region of the human alpha 1 globin gene and have made pairwise comparisons between sequenced alpha-globin genes. The flanking regions were examined in detail because sequence matches in these regions could be interpreted with the least complication from the gene duplications and conversions that have occurred frequently in mammalian alpha-like globin gene clusters. We found good matches between the flanking regions of human alpha 1 and rabbit alpha 1, human psi alpha 1 and goat I alpha, human alpha 2 and goat II alpha, and horse alpha 1 and goat II alpha. These matches were used to align the alpha-globin genes in gene clusters from different mammals. This alignment shows that genes at equivalent positions in the gene clusters of different mammals can be functional or nonfunctional, depending on whether they corrected against a functional alpha-globin gene in recent evolutionary history. The number of alpha-globin genes (including pseudogenes) appears to differ among species, although highly divergent pseudogenes may not have been detected in all species examined. Although matching sequences could be found in interspecies comparisons of the flanking regions of alpha- globin genes, these matches are not as extensive as those found in the flanking regions of mammalian beta-like globin genes. This observation suggests that the noncoding sequences in the mammalian alpha-globin gene clusters are evolving at a faster rate than those in the beta-like globin gene clusters. The proposed faster rate of evolution fits with the poor conservation of the genetic linkage map around alpha-globin gene clusters when compared to that of the beta-like globin gene clusters. Analysis of the 3' flanking regions of alpha-globin genes has revealed a conserved sequence approximately 100-150 bp 3' to the polyadenylation site; this sequence may be involved in the expression or regulation of alpha-globin genes.      

The effect of centrifugal accelerations on the polarity of statocytes and on the graviperception of cress roots

The structural polarity of statocytes of Lepidium sativum L. is converted to a physical stratification by a root-tip-directed centrifugal acceleration. Sedimentation of amyloplasts and nucleus to the centrifugal (distal) cell pole and the lateral displacement of the distal endoplasmic reticulum (ER) complex occur after centrifugation for 20 min at an acceleration of 50 g. With higher doses (20 min, 100-2,000 g), smaller organelles become increasingly displaced. From the centrifugal to the centripetal cell pole, the following stratification is observed: 1) amyloplasts with mitochondria; 2) nucleus with mitochondria and a few dictyosomes, as well as laterally located ER; 3) dictyosomes with a few mitochondria; 4) vacuoles; and 5) lipid droplets. Within the first 7.5 min, after the roots have been returned to 1 g, the original arrangement of the amyloplasts sedimented on the underlying ER complex is reestablished in 66% of the statocytes. When roots previously centrifuged in an apical direction are exposed in a horizontal position to 1 g, the latent period of the graviresponse is increased by 7.5 min relative to the non-centrifuged controls. The kinetics of the response are identical to the controls. Roots centrifuged first in an apical direction and then for 2 h in a lateral direction (1,000 g) have statocytes with a physical stratification perpendicular to the root axis. A gravitropic curvature does not take place during the lateral centrifugation. These results support the hypothesis that the distal ER complex is necessary and sufficient for graviperception.     

Oscillations of cAMP with the cardiac cycle

Oscillations of cAMP with the cardiac cycle were demonstrated in the rat heart using a stimulator-triggered rapid freeze-clamp to decrease the temperature of the heart from 37 degrees C to -80 degrees C in 5 msec (20,000 degrees/sec) at a predetermined phase of the cardiac cycle. The nucleotide, cAMP, oscillated 60% with the cardiac cycle during normal working conditions, the higher cAMP value occurring during systole.     

Shuttle-like movements of Golgi vesicles in the tip of growingChara rhizoids

Summary In tip-growingChara rhizoids, the in-vivo saltatory movements of Golgi vesicles were recorded. The movements in radial direction back and forth between the ER aggregate and the plasma membrane occurred three times more often than movements passing the ER aggregate tangentially. The mean velocity of the class of Golgi vesicles observed (0.4–1 m in diameter) was approx. 0.3 m/s. Higher speed of 1–1.5 m/s occurred only in radial directions. Possibly, the ER aggregate is involved in guidance of the Golgi vesicles.Abbreviations DIC differential interference contrast - ER endoplasmic reticulum - OsFeCN osmium tetroxide-potassium ferricyanide Dedicated to the memory of Professor O. Kiermayer     

P48-Triggered transmembrane signaling transduction of human monocytes:mobilization of calcium ion and activation of protein kinase C(PKC)

INTRODUCTI0NThedifferentiati0nofcelIsalongthemonocyte-macr0phagepathwayandthesig-nalsinvo1vedinthesecel1sacquiringtheabilitytokilltum0rcellsarenotfllllyundersto0d.Wehavebeenstudingamoleculewhichappearst0beanimportantmemberofthecytokinenetworkinvo1vedintheregulati0nmonocyteactivation.ThiscytokinetermedP48wasisolatedfr0mthehllmannullcellleukemiacell1ineReh.IthasbeenpurifiedtohomogeneityandfOundtobedistinctfrominterferongamma,col0nystimulatingfactors(CSFs)andTNFalphaalldbeta[1,2].Func-ti…