Biologie - Open Access LMU - Teil 01/02

Reaction centers from Rhodobacter sphaeroides have been modified by treatment with sodium borohydride similar to the original procedure [Ditson et al., Biochim. Biophys. Acta 766, 623 (1984)], and investigated spectroscopically and by gel electrophoresis. (1) Low temperature (1.2 K) absorption, fluorescence, absorption- and fluorescence-detected ODMR, and microwave-induced singlet-triplet absorption difference spectra (MIA) suggest that the treatment produces a spectroscopically homogeneous preparation with one of the ‘additional’ bacteriochlorophylls being removed. The modification does not alter the zero field splitting parameters of the primary donor triplet (TP870). (2) From the circular dichroism and Raman resonance spectra in the1500–1800 cm-1 region, the removed pigment is assigned to BchlM, e.g. the "extra" Bchl on the "inactive" M-branch. (3) A strong coupling among all pigment molecules is deduced from the circular dichroism spectra, because pronounced band-shifts and/or intensity changes occur in the spectral components assigned to all pigments. This is supported by distinct differences among the MIA spectra of untreated and modified reaction centers, as well as by Raman resonance. (4) The modification is accompanied by partial proteolytic cleavage of the M-subunit. The preparation is thus spectroscopically homogeneous, but biochemically heterogenous.

Fri, 1 Jan 1988 12:00:00 +0100 http://epub.ub.uni-muenchen.de/2229/ http://epub.ub.uni-muenchen.de/2229/1/2229.pdf Fischer, R.; Siebzehnrübl, S.; Scheer, Hugo Scheer, Hugo und Schneider, S. (Hrsg.) (1988): C-phycocyanin from Mastigocladus laminosus. Chromophore assignment in higher aggregates by cystein modification. Photosynthetic light-harvesting systems, 12. - 16. Oktober 1987 , Deutschland. Biologie

Highly frequency selective photochemistry at cryogenic temperatures is used to gain information on the excited state dynamics of large biomolecular aggregates, the phycobilisomes from the blue–green alga (cyanobacterium) Masticogladus laminosus. In particular, we show that in spite of the well organized structure of these aggregates disorder on a microscopic level dominates the optical spectra. The hole burning reaction in the resonantly excited chromophores is most probably due to a conformational change in the neighborhood of the chromophore. From the widths of the holes energy transfer times between different pigments on the order of 16 ps are determined. These transfer times are independent of the excitation energy. The Journal of Chemical Physics is copyrighted by The American Institute of Physics.

The temperature dependence of spectral holes burnt into a phycocyanin-doped ethylene glycol/water glass is investigated in the temperature range between 1.5 and 15 K. The data are well described by a power law with an exponent of 1.16 ± 0.1. Chromoproteins thus behave very much the same as glasses doped with small impurity molecules.

We present a combined fluorescence and hole-burning study of the biliprotein C-phycocyanin. Sharp zero-phonon holes compare with a broad structureless fluorescence. This finding is rationalized in terms of the special level structure in this pigment, the fast energy-transfer processes and a lack of correlation of the energies of the emissive states.

Fri, 1 Jan 1988 12:00:00 +0100 http://epub.ub.uni-muenchen.de/2236/ http://epub.ub.uni-muenchen.de/2236/1/128.pdf Köhler, W.; Friedrich, J.; Scheer, Hugo Köhler, W.; Friedrich, J. und Scheer, Hugo (1988): Conformational barriers in low-temperature proteins and glasses. In: Physical Reviews, Vol. A37, Nr. 2: pp. 660-662. Biologie

The light-induced radical cation of the primary electron donor P960+• in photosynthetic reaction centers from Rhodopseudomonas viridis has been investigated by ESR, ENDOR and TRIPLE techniques. Both the comparison with the cation radical of monomeric bacteriochlorophyll b (BChl b) and with molecular-orbital calculations performed on P960+• using the results of an X-ray structure analysis, consistently show an asymmetric distribution of the unpaired electron over the two BChl b molecules which constitute P960+•. The possible relevance of this result for the primary electron transfer step in the reaction center is briefly discussed.

The fluorescence decay time of the biliverdin IX7 chromophore present in biliproteins isolated from Pieris brassicae is determined to be 44 ± 3 ps. This value suggests a cyclic helical chromophore structure. The vibrational frequencies determined by CARS-spectroscopy are compared with those of model compounds. The data confirm that the chromophore in the protein-bound state adopts a cyclic-helical, flexible conformation.

Calculations of excitation transfer rates among the chromophores of C-phycocyanin using the Förster inductive resonance transfer mechanism have been carried out using the new coordinates for the position and orientation of the chromophores (Schirmer, T., Bode, W. and Huber, R. (1987) J. Mol. Biol. 196, 677–695). Several of the rate constants are significantly altered from the results of our calculations using the previously published coordinates (Sauer, K., Scheer, H. and Sauer, P. (1987) Photochem. Photobiol. 46, 427–440). In particular, for the (αβ)3-trimers of Mastigocladus laminosus or for the (αβ)3-trimers or the (αβ)6-hexamers of Agmenellum quadruplicatum, the new calculations predict excited state relaxation components with exponential time constants shorter than 1 ps. In fact, some of the interchromophore interactions are so strong that exciton coupling is probably the relevant mechanism of interaction. The largest exciton energy is calculated to be about 56 cm−1, for the interaction between the adjacent α84 and β84 chromophores of neighboring monomer units within the (αβ)3-trimers or (αβ)6-hexamers. An energy transfer model invoking a combination of pairwise exciton formation followed by slower Förster transfer steps is described.

Fri, 1 Jan 1988 12:00:00 +0100 http://epub.ub.uni-muenchen.de/2279/ http://epub.ub.uni-muenchen.de/2279/1/2279.pdf Scheer, Hugo; Beese, D.; Steiner, R.; Angerhofer, A. Scheer, Hugo; Beese, D.; Steiner, R. und Angerhofer, A. (1988): Reaction centers of purple bacteria with modified chromophores. In: Jacques, Breton (Hrsg.), The Photosynthetic Bacterial Reaction Center : Structure and dynamics. Bd. 1, Plenum Press: New York, pp. 101-111. Biologie

Fri, 1 Jan 1988 12:00:00 +0100 http://epub.ub.uni-muenchen.de/2296/ http://epub.ub.uni-muenchen.de/2296/1/2296.pdf Senge, M.; Struck, A.; Dörnemann, D.; Scheer, Hugo; Senger, H. Senge, M.; Struck, A.; Dörnemann, D.; Scheer, Hugo und Senger, H. (1988): Hydroxylation of chlorinated and unchlorinated chlorophylls in vitro. In: Zeitschrift für Naturforschung C, Vol. 43c: pp. 515-518. Biologie

The Q4 class I gene has been shown to participate in gene conversion events within the mouse major histocompatibility complex. Its complete genomic nucleotide sequence has been determined. The 5' half of Q4 resembles H-2 genes more strongly than other Q genes. Its 3' end, in contrast, is Q-like and contains a translational stop signal in exon 5 which predicts a polypeptide with an incomplete membrane spanning segment. The presence of two inverted B1 repeats suggests that part of the Q4 gene may be mobile within the genome. Gene transfer experiments have shown that the Q4 gene encodes a ß2-microglobulin associated polypeptide of Mr 41 000. A similar protein was found in activated mouse spleen cells. The Q4 polypeptide was found to be secreted both by spleen cells and by transfected fibroblasts and was not detectable on the cell surface. Antibody binding and twodimensional gel electrophoresis indicate that the Q4 molecule is identical to a mouse class I polypeptide, Qb-1, which has been previously described.

Fri, 1 Jan 1988 12:00:00 +0100 http://epub.ub.uni-muenchen.de/3083/ http://epub.ub.uni-muenchen.de/3083/1/040.pdf Ragoussis, Jiannis; Bloemer, Katharina; Weiß, Elisabeth; Ziegler, Andreas Ragoussis, Jiannis; Bloemer, Katharina; Weiß, Elisabeth und Ziegler, Andreas (1988): Localization of the genes for tumor necrosis factor and lymphotoxin between the HLA classI and III regions by field inversion gel electrophoresis. In: Immunogene

Fri, 1 Jan 1988 12:00:00 +0100 http://epub.ub.uni-muenchen.de/3085/ http://epub.ub.uni-muenchen.de/3085/1/3085.pdf Weiß, Elisabeth; Bloemer, Katharina; Doerner, C.; Kuon, W.; Lang, M.; Pohla, Heike; Schattenkirchner, M.; Riethmüller, Gert Weiß, Elisabeth; Bloemer, Katharina; Doerner, C.; Kuon, W.; Lang, M.; Pohla, Heike; Schattenkirchner, M. und Riethmüller, Gert (1988): Molecular biology of the HLA-B27 locus. In: British Journal of Rheumatology, Vol. 27, Nr. 2: pp. 12-18. Biologie

Fri, 1 Jan 1988 12:00:00 +0100 http://epub.ub.uni-muenchen.de/3192/ http://epub.ub.uni-muenchen.de/3192/1/3192.pdf Schuller, Gerd; Radtke-Schuller, Susanne Schuller, Gerd und Radtke-Schuller, Susanne (1988): Midbrain areas as candidates for audio-vocal interface in echolocating bats. In: Nachtigall, P. E. (Hrsg.), Animal Sonar. Processes and performance. Plenum Press: New York u.a., pp. 93-98. Biol

The glyoxylic-acid-induced fluorescence technique was applied to demonstrate patterns of catecholaminergic innervation within the auditory brainstem of echolocating bats and the house mouse. In the cochlear nucleus of the rufous horseshoe bat (Rhinolophus rouxi) and the mustache bat (Pteronotus parnelli), species-specific catecholaminergic innervation patterns are found that contrast with the relatively homogeneous innervation in the rodent. In both bats the subnuclei of the cochlear nucleus receive a differentially dense supply of catecholaminergic fibers, and within the subnuclei, the catecholamine innervation densities can be correlated with the tonotopic frequency representation. The areas devoted to the high-frequency echolocation calls are less densely innervated than those regions which are responsive to lower frequencies. Apart from this common scheme, there are noteworthy distinctions between the two bats which correlate with specialized cytoarchitectural features of the cochlear nucleus. The marginal cell group, located medially to the anteroventral cochlear nucleus of Pteronotus, receives the densest supply of catecholaminergic fibers of all auditory nuclei. This plexus is formed by a morphologically distinct population of catecholaminergic fibers.

A silver impregnation method is described which shows motor and sensory nerves and their endings in formalin-fixed mammalian muscles. The method works with the same reliability on flattened muscle pieces as well as on frozen sections. Large nerve bundles, myelinated and non-myelinated single axons, and terminals impregnated by this method stand out black against a light brown background.

Injection of horseradish peroxidase into the secondary gustatory nucleus of the green sunfish, Lepomis cyanellus, resulted in retrogradely filled neurons bilaterally in the viscerosensory column of the brainstem and in anterograde transport revealing ipsilateral terminal fields in the preglomerular tertiary gustatory nucleus, the nucleus of the torus lateralis and the central and periventricular nucleus of the inferior lobe. Thus, the glomerular nucleus of percomorph teleosts is not a tertiary gustatory center. It is proposed that the term ‘nucleus glomerulosus’ be reserved for the nucleus involved with vision and that the preglomerular subdivision involved in gustation be termed ‘nucleus gustatorius tertius’.

The Edinger-Westphal nucleus in goldfish was identified by retrograde labeling from the ciliary ganglion. In the same animals a few neurons near this nucleus (perinuclear Edinger-Westphal neurons) were labeled by a different retrograde tracer injected into the cerebellum. No double-labeled cells were found. Similar results were obtained in kelp bass, except that in this species no cerebellar-projecting perinuclear neurons were observed. Cerebellar-projecting Edinger-Westphal neurons have previously been described in some mammals, but not in other vertebrates. Therefore the homology of cerebellar-projecting cells of the Edinger-Westphal region in mammals and teleost fishes is doubtful.

Fri, 1 Jan 1988 12:00:00 +0100 http://epub.ub.uni-muenchen.de/3304/ http://epub.ub.uni-muenchen.de/3304/1/3304.pdf Northcutt, R. G.; Wullimann, Mario F. Northcutt, R. G. und Wullimann, Mario F. (1988): The visual system in teleost fishes. morphological patterns and trends. In: Atema, J.; Fay, R. R.; Popper, A. N. und Tavolga, W. N. (Hrsg.), Sensory Biology of Aquatic Animals. Springer: New York u.a., pp. 515-552. Biologie

A guanosine 5-triphosphate (GTP)-dependent protein kinase was detected in preparations of outer chloroplast envelope membranes of pea (Pisum sativum L.) chloroplasts. The protein-kinase activity was capable of phosphorylating several envelope-membrane proteins. The major phosphorylated products were 23- and 32.5-kilo-dalton proteins of the outer envelope membrane. Several other envelope proteins were labeled to a lesser extent. Following acid hydrolysis of the labeled proteins, most of the label was detected as phosphoserine with only minor amounts detected as phosphothreonine. Several criteria were used to distinguish the GTP-dependent protein kinase from an ATP-dependent kinase also present in the outer envelope membrane. The ATP-dependent kinase phosphorylated a very different set of envelope-membrane proteins. Heparin inhibited the GTP-dependent kinase but had little effect upon the ATP-dependent enzyme. The GTP-dependent enzyme accepted phosvitin as an external protein substrate whereas the ATP-dependent enzyme did not. The outer membrane of the chloroplast envelope also contained a phosphotransferase capable of transferring labeled phosphate from [-32P]GTP to ADP to yield (-32P]ATP. Consequently, addition of ADP to a GTP-dependent protein-kinase assay resulted in a switch in the pattern of labeled products from that seen with GTP to that typically seen with ATP.

Fri, 1 Jan 1988 12:00:00 +0100 http://epub.ub.uni-muenchen.de/3505/ http://epub.ub.uni-muenchen.de/3505/1/3505.pdf Soll, Jürgen; Fischer, Irene Soll, Jürgen und Fischer, Irene (1988): Analysis of chloroplast envelope membranes using photoaffinity label. In: Journal of Plant Physiology, Vol. 132: pp. 631-635. Biologie

An ATP-dependent protein kinase was partially purified from isolated outer envelope membranes of pea (Pisum sativum L., Progress No. 9) chloroplasts. The purified kinase had a molecular weight of 70 kilodaltons, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. It was of the cyclic nucleotide and Ca2+, calmodulin-independent type. The purification involved the detergent solubilization of purified outer envelopes by 0.5% cholate and 1% octylglycoside, followed by centrifugation on a linear 6 to 25% sucrose gradient. Active enzyme fractions were further purified by affinity chromatography on histone III-S Sepharose 4B and ion exchange chromatography on diethylaminoethyl cellulose. The protein kinase eluted at 100 millimolar and 50 millimolar NaCl, respectively. The protein kinase was essentially pure as judged by Western blot analysis. The enzyme has a KM of 450 micromolar for ATP and a Vmax of 25 picomoles of 32P incorporated into histone III-S per minute per microgram. Inhibition by ADP is competitive (Ki 150 micromolar).

The identification and localization of a marker protein for the intermembrane space between the outer and inner chloroplast envelopes is described. This 64-kDa protein is very rapidly labeled by [γ-32P]ATP at very low (30 nM) ATP concentrations and the phosphoryl group exhibits a high turnover rate. It was possible to establish the presence of the 64-kDa protein in this plastid compartment by using different chloroplast envelope separation and isolation techniques. In addition comparison of labeling kinetics by intact and hypotonically lysed pea chloroplasts support the localization of the 64-kDa protein in the intermembrane space. The 64-kDa protein was present and could be labeled in mixed envelope membranes isolated from hypotonically lysed plastids. Mixed envelope membranes incorporated high amounts of 32P from [γ-32P]ATP into the 64-kDa protein, whereas separated outer and inner envelope membranes did not show significant phosphorylation of this protein. Water/Triton X-114 phase partitioning demonstrated that the 64-kDa protein is a hydrophilic polypeptide. These findings suggest that the 64-kDa protein is a soluble protein trapped in the space between the inner and outer envelope membranes. After sonication of mixed envelope membranes, the 64-kDa protein was no longer present in the membrane fraction, but could be found in the supernatant after a 110000 × g centrifugation.

Fri, 1 Jan 1988 12:00:00 +0100 http://epub.ub.uni-muenchen.de/5058/ http://epub.ub.uni-muenchen.de/5058/1/5058.pdf Gabriel, Wilfried Gabriel, Wilfried (1988): Quantitative genetic models for partheonogenetic species. In: Jong, Gerdina de (Hrsg.), Population genetics and evolution. Springer: Heidelberg, pp. 73-82. Biologie

Fri, 1 Jan 1988 12:00:00 +0100 http://epub.ub.uni-muenchen.de/5059/ http://epub.ub.uni-muenchen.de/5059/1/013.pdf Gabriel, Wilfried; Wagner, G. P. Gabriel, Wilfried und Wagner, G. P. (1988): Parthenogenetic populations can remain stable in spite of high mutation rate and random drift. In: Naturwissenschaften, Vol. 75, Nr. 4: pp. 204-205.

Fri, 1 Jan 1988 12:00:00 +0100 http://epub.ub.uni-muenchen.de/5060/ http://epub.ub.uni-muenchen.de/5060/1/5060.pdf Gabriel, Wilfried; Thomas, Bernhard Gabriel, Wilfried und Thomas, Bernhard (1988): The influence of food availability, predation risk, and metabolic costs on the evolutionary stability of diel vertical migration in zooplankton. In: Verhandlungen / International Association of Theoretical and Applied Limnology

Fri, 1 Jan 1988 12:00:00 +0100 http://epub.ub.uni-muenchen.de/5061/ http://epub.ub.uni-muenchen.de/5061/1/5061.pdf Gabriel, Wilfried; Thomas, Bernhard Gabriel, Wilfried und Thomas, Bernhard (1988): Vertical migration of zooplankton as an evolutionary stable strategy. In: American Naturalist, Vol. 132, Nr. 2: pp. 199-216. Biologie

Fri, 1 Jan 1988 12:00:00 +0100 http://epub.ub.uni-muenchen.de/5062/ http://epub.ub.uni-muenchen.de/5062/1/5062.pdf Gabriel, Wilfried; Thomas, Bernhard Gabriel, Wilfried und Thomas, Bernhard (1988): Ultimate causes of vertical migration in zooplankton. An evaluation by evolutionary game theory. In: Wolff, Wilfried (Hrsg.), Ecodynamics. Contributions to theoretical ecology. Springer: Berlin u.a., pp. 127-134. Biologie

Excitation energy transfer in C-phycocyanin is modeled using the Forster inductive resonance mechanism. Detailed calculations are carried out using coordinates and orientations of the chromophores derived from X-ray crystallographic studies of C-phycocyanin from two different species (Schirmer et al, J. Mol. Biol. 184, 257–277 (1985) and ibid., 188, 651-677 (1986)). Spectral overlap integrals are estimated from absorption and fluorescence spectra of C-phycocyanin of Mastigocladus laminosus and its separated subunits. Calculations are carried out for the β-subunit, αβ-monomer, (αβ)3-trimer and (αβ)0-hexamer species with the following chromophore assignments: β155 = 's’(sensitizer), β84 =‘f (fluorescer) and α84 =‘m’(intermediate):]:. The calculations show that excitation transfer relaxation occurs to 3=98% within 200 ps in nearly every case; however, the rates increase as much as 10-fold for the higher aggregates. Comparison with experimental data on fluorescence decay and depolarization kinetics from the literature shows qualitative agreement with these calculations. We conclude that Forster transfer is sufficient to account for all of the observed fluorescence properties of C-phycocyanin in aggregation states up to the hexamer and in the absence of linker polypeptides.

Thu, 1 Jan 1987 12:00:00 +0100 http://epub.ub.uni-muenchen.de/2181/ http://epub.ub.uni-muenchen.de/2181/1/2181.pdf Robert, B.; Steiner, R.; Zhou, Q.; Scheer, Hugo; Lutz, M. Biggins, J. (Hrsg.) (1987): Structures of antenna complexes and reaction centers from bacteriochlorophyll b-containing bacteria. Resonance Raman studies. International Congress on Photosynthesis , 10. - 15. August 1986, Providence, USA.

Thu, 1 Jan 1987 12:00:00 +0100 http://epub.ub.uni-muenchen.de/2182/ http://epub.ub.uni-muenchen.de/2182/1/2182.pdf Sauer, K.; Scheer, Hugo Biggins, J. (Hrsg.) (1987): Fluorescence decay and depolarization kinetics calculated using Förster inductive resonance and the molecular coordinates for C-Phycocyanin. International Congress on Photosynthesis , 10. - 15. August 1986, Providence

Thu, 1 Jan 1987 12:00:00 +0100 http://epub.ub.uni-muenchen.de/2222/ http://epub.ub.uni-muenchen.de/2222/1/2222.pdf Scheer, Hugo Biggins, J. (Hrsg.) (1987): Photochemistry and photophysics of C-phycocyanin. VIIth International Congress on Photosynthesis, 10. - 15. August 1986, Providence, Rhode Island, USA. Biologie

Thu, 1 Jan 1987 12:00:00 +0100 http://epub.ub.uni-muenchen.de/2227/ http://epub.ub.uni-muenchen.de/2227/1/2227.pdf Siebzehnrübl, S.; Fischer, R.; Scheer, Hugo Siebzehnrübl, S.; Fischer, R. und Scheer, Hugo (1987): Chromophore assignment in C-phycocyanin from Mastigocladus laminosus. In: Zeitschrift für Naturforschung C, Vol. 42c: pp. 258-262. Biologie

Thu, 1 Jan 1987 12:00:00 +0100 http://epub.ub.uni-muenchen.de/2228/ http://epub.ub.uni-muenchen.de/2228/1/2228.pdf Fischer, R.; Madubunyi, I.; Scheer, Hugo Fischer, R.; Madubunyi, I. und Scheer, Hugo (1987): Stereochemistry of Two Hydroxybiflavanonols from Garcinia cola Nuts. In: Zeitschrift für Naturforschung C, Vol. 42c: pp. 855-857. Biologie

A new method is presented for the fast preparative separation of the light-harvesting photosynthetic pigment C-phycocanin into its and subunits, which is based on isoelectric focusing in layers of granutaled gels containing 7 M urea. The method has been successful in cases where other separation procedures failed. The recovery of the separated chains of the light -sensitive biliprotein amounts to 70 � 10 % when the separation is carried out under light exclusion and in an argon atmosphere. A simple and inexpensive setup for work under an atmosphere of protective gas is described.

Thu, 1 Jan 1987 12:00:00 +0100 http://epub.ub.uni-muenchen.de/3086/ http://epub.ub.uni-muenchen.de/3086/1/weiss_elisabeth_3086.pdf Schwaeble, Wilhelm; Zwirner, Jörg; Schulz, T. F.; Linke, Reinhold P.; Dierich, Manfred P.; Weiß, Elisabeth Schwaeble, Wilhelm; Zwirner, Jörg; Schulz, T. F.; Linke, Reinhold P.; Dierich, Manfred P. und Weiß, Elisabeth (1987): Human complement factor H. expression of an additional truncated gene product of 43 kDa in human liver. In: European Journal of Immunology, Vol. 17: pp. 1485-1489. Biologie 0

The peculiar tropism of the human immunodeficiency virus (HIV) for T helper lymphocytes can be explained by a specific interaction between the virus and the CD4 molecule on these cells (1, 2). The tropism for T lymphocytes, however, can hardly account for the early brain infection observed in some AIDS (acquired immune deficiency syndrome) patients (3, 4). Since CD4 is also expressed on virus-susceptible non-T cell lines we wondered whether an additional expression site of CD4 could be demonstrated in neural tissue (5). To this end, CD4 expression in brain was analyzed with several different anti-CD4 mAbs, and using a CD4-specific cDNA probe in Northern blot analyses . CD4' cells and CD4-specific mRNA were found in the cerebellum, thalamus, and pons. The reactive cells could be identified as neurons as well as glial cells.

Two glucocorticoid response elements (GREs) located 2.5 kb upstream of the transcription initiation site of the tyrosine aminotransferase gene were identified by gene transfer experiments and shown to bind to purified glucocorticoid receptor. Although the proximal GRE has no inherent capacity by itself to stimulate transcription, when present in conjunction with the distal GRE, this element synergistically enhances glucocorticoid induction of gene expression. Cooperativity of the two GREs is maintained when they are transposed upstream of a heterologous promoter. An oligonucleotide of 22 bp representing the distal GRE is sufficient to confer glucocorticoid inducibility. As evidenced by the mapping of DNAase I hypersensitive sites, local alterations in the structure of chromatin at the GREs take place as a consequence of hormonal treatment.

Thu, 1 Jan 1987 12:00:00 +0100 http://epub.ub.uni-muenchen.de/3300/ http://epub.ub.uni-muenchen.de/3300/1/3300.pdf Wullimann, Mario F. Kullander, Sven O. (Hrsg.) (1987): The hypothalamic, ventricular channel-system and its phylogenetic distribution among fishes. V Congress of European Ichthyologists , 1985, Stockholm.

We investigated whether all stem cells of Hydra can differentiate both somatic cells and gametes or if a separate germ line exists in these phylogenetically old organisms. The differentiation potential of single stem cells was analyzed by applying a statistical cloning procedure. All stem cell clones were found to differentiate somatic cells. No clone was found to contain stem cells which do not differentiate. Most of the clones could be induced to form gametes. No clone was found that produced gametes only. The results indicate that stem cells are multipotent in the sense that individual stem cells can differentiate into somatic cells as well as germ line cells.

Thu, 1 Jan 1987 12:00:00 +0100 http://epub.ub.uni-muenchen.de/3387/ http://epub.ub.uni-muenchen.de/3387/1/3387.pdf David, Charles N.; Bosch, Thomas C. G.; Hobmayer, Engelbert; Holstein, Thomas W.; Schmidt, Tobias David, Charles N.; Bosch, Thomas C. G.; Hobmayer, Engelbert; Holstein, Thomas W. und Schmidt, Tobias (1987): Interstitial stem cells in Hydra. In: Loomis, W. F. (Hrsg.), Genetic Regulation of Development. Liss: New York, pp. 389-408. Biologie

Thu, 1 Jan 1987 12:00:00 +0100 http://epub.ub.uni-muenchen.de/3512/ http://epub.ub.uni-muenchen.de/3512/1/3512.pdf Schindler, C.; Hracky, R.; Soll, Jürgen Schindler, C.; Hracky, R. und Soll, Jürgen (1987): Protein transport in chloroplasts. ATP is prerequisit. In: Zeitschrift für Naturforschung C, Vol. 42c: pp. 103-108. Biologie

Thu, 1 Jan 1987 12:00:00 +0100 http://epub.ub.uni-muenchen.de/3596/ http://epub.ub.uni-muenchen.de/3596/1/3596.pdf Schulze-Siebert, D.; Homeyer, U.; Soll, Jürgen; Schultz, Gernot Stumpf, Paul K. (Hrsg.) (1987): Synthesis of Plastoquinone-9, α-Tocopherol and Phylloquinone (Vitamine K1) and its integration in chloroplast carbon metabolism of higher plants. 17. Internat. Symposium on Plant Lipids, Univ. of California, Davis, July 27 - August 1,

Thu, 1 Jan 1987 12:00:00 +0100 http://epub.ub.uni-muenchen.de/5036/ http://epub.ub.uni-muenchen.de/5036/1/5036.pdf Lynch, Michael; Gabriel, Wilfried Lynch, Michael und Gabriel, Wilfried (1987): Environmental tolerance. In: American Naturalist, Vol. 129: pp. 283-303. Biologie 0

Thu, 1 Jan 1987 12:00:00 +0100 http://epub.ub.uni-muenchen.de/5037/ http://epub.ub.uni-muenchen.de/5037/1/5037.pdf Gabriel, Wilfried Möller, Dietmar P. F. (Hrsg.) (1987): The use of computer simulation to evaluate the testability of a new fitness concept. 2. Erwin-Riesch-Arbeitstagung , Februar 1986, Münster-Ebernburg.

Thu, 1 Jan 1987 12:00:00 +0100 http://epub.ub.uni-muenchen.de/5040/ http://epub.ub.uni-muenchen.de/5040/1/5040.pdf Lynch, Michael; Gabriel, Wilfried Lynch, Michael und Gabriel, Wilfried (1987): Evolution of the breadth of biochemical adaptation. In: Calow, Peter (Hrsg.), Evolutionary physiological ecology. Cambridge Univ. Pr.: Cambridge u.a., pp. 67-83. Biologie

I. Birth and death rates of natural cladoceran populations cannot be measured directly. Estimates of these population parameters must be calculated using methods that make assumptions about the form of population growth. These methods generally assume that the population has a stable age distribution. 2. To assess the effect of variable age distributions, we tested six egg ratio methods for estimating birth and death rates with data from thirty-seven laboratory populations of Daphnia pulicaria. The populations were grown under constant conditions, but the initial age distributions and egg ratios of the populations varied. Actual death rates were virtually zero, so the difference between the estimated and actual death rates measured the error in both birth and death rate estimates. 3. The results demonstrate that unstable population structures may produce large errors in the birth and death rates estimated by any of these methods. Among the methods tested, Taylor and Slatkin's formula and Paloheimo's formula were most reliable for the experimental data. 4. Further analyses of three of the methods were made using computer simulations of growth of age-structured populations with initially unstable age distributions. These analyses show that the time interval between sampling strongly influences the reliability of birth and death rate estimates. At a sampling interval of 2.5 days (equal to the duration of the egg stage), Paloheimo's formula was most accurate. At longer intervals (7.5–10 days), Taylor and Slatkin's formula which includes information on population structure was most accurate.

1. Horseradish peroxidase was applied by iontophoretic injections to physiologically identified regions of the laryngeal motor nucleus, the nucleus ambiguus in the CF/FM batRhinolophus rouxi. 2. The connections of the nucleus ambiguus were analysed with regards to their possible functional significance in the vocal control system, in the respiration control system, and in mediating information from the central auditory system. 3. The nucleus ambiguus is reciprocally interconnected with nuclei involved in the generation of the vocal motor pattern, i.e., the homonomous contralateral nucleus and the area of the lateral reticular formation. Similarly, reciprocal connections are found with the nuclei controlling the rhythm of respiration, i.e., medial parts of the medulla oblongata and the parabrachial nuclei. 4. Afferents to the nucleus ambiguus derive from nuclei of the descending vocalization system (periaqueductal gray and cuneiform nuclei) and from motor control centers (red nucleus and frontal cortex). 5. Afferents to the nucleus ambiguus, possibly mediating auditory influence to the motor control of vocalization, come from the superior colliculus and from the pontine nuclei. The efferents from the pontine nuclei are restricted to rostral parts of the nucleus ambiguus, which hosts the motoneurons of the cricothyroid muscle controlling the call frequency.

The proliferative capacity of gland cells in Hydra attenuata was investigated. The results indicate that both gland cell proliferation and interstitial cell differentiation to gland cells contribute to the maintenance of the whole population. On the basis of [3H]thymidine incorporation and nuclear DNA measurements, gland cells consist of at least three different populations. One population consists of rapidly proliferating cells with a cell cycle of about 72 h. These cells are distributed throughout the body column. In the lower gastric region there is a population of non-cycling cells in G2 while in the upper gastric region there is a population of noncycling cells in G1. About half the G1 population becomes a new antigen, SEC 1, which is typical of mucus cells.

Two signals, the head activator and an injury stimulus, control differentiation of nerve cells from uncommitted stem cells in hydra [Th. Holstein, H. C. Schaller, and C. N. David, (1986) Dev. Biol. 115, 9–17]. The time of action of these signals in the precursor cell cycle was determined. Methanol extracts of hydra containing 10−13 M head activator cause nerve cell commitment in S phase of the precursor cell cycle. Committed precursors complete the cell cycle, divide, and arrest in G1. Injury relieves the G1 block and precursors differentiate nerve cells. Under these conditions the time from commitment to nerve differentiation is 12 hr, the time from the end of S phase to nerve differentiation is 9 hr, and the time from the G1 block to nerve differentiation is 4 hr. Committed precursors blocked in G1 are unstable, decaying with a half-life of 12 hr if not stimulated to differentiate by an injury stimulus.