Zur Feinstruktur der Plasmodesmen und Plasmakanäle bei Pollenmutterzellen

Zusammenfassung Bei Tomate (Lycopersicum esculentum) und Kürbis (Cucurbita maxima) wurde der Feinbau der zwischen den Pollenmutterzellen bestehenden Plasmaverbindungen elektronenmikroskopisch untersucht.Neben feinen, den Verhältnissen in meristematischen somatischen Zellen entsprechenden Plasmaverbindungen (Plasmodesmen im engeren Sinne, Durchmesser im geometrischen Mittel 253,3 Å) wurden relativ breite, fast durchweg gröbere Cytoplasmaeinschlüsse (Mitochondrien, Vesikel, Potocytose-Bläschen, Dictyosomen usw.) aufweisende Verbin-dungen (Plasmakanäle, Durchmesser im geometrischen Mittel 0,175 ) festgestellt. Elemente des Endoplasmatischen Reticulums finden sich regelmäßig in den Plasmakanälen. Sie lassen sich jedoch häufig auch in größeren Plasmodesmen nachweisen.Weder über den Zeitpunkt der Entstehung, noch über die Entstehungsweise der Plasmakanäle lassen sich bei unserem Pflanzenmaterial konkrete Angaben machen. Gleiches gilt hinsichtlich des Zeitpunktes und der Art, wie die Plasmakanäle schließlich schwinden.Unbekannt ist auch die Art und Weise, wie die Plasmodesmen in Verbindung mit der Bildung der die Pollenmutterzellen bzw. auch die einzelnen Tetradenzellen umhüllenden dicken Callosemembranen schwinden.Bei der Tomate sind die Plasmakanäle bereits vor Aufgabe der Plasmodesmen vorhanden. Andererseits lassen sie sich in späteren Phasen der Tetradenentwicklung nicht mehr nachweisen.Die Beobachtungen werden in Verbindung mit bereits vorliegenden Angaben in der Literatur, insbesondere im Hinblick auf die Bedeutung der Plasmakanäle und ihre Ähnlichkeit mit Siebporen, diskutiert.

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On the fine structure of plasmodesmata and plasma-channels in pollen mother cells (PMC)

Summary The fine structure of plasmatic connections between PMC has been examined by electron microscopy in tomato (Lycopersicum esculentum) and squash (Cucurbita maxima).In addition to plasmodesmata, of geometrical mean diameter 253.3 Å, which correspond to the plasmodesmata in meristematic somatic cells, there are also to be distinguished plasma-channels of geometrical mean diameter 0.175 , which frequently contain cytoplasmic inclusions, such as mitochondria, vesicles, potocytosevesicles, dictyosomata etc. Generally we found elements of the endoplasmic reticulum in the plasma-channels. These elements are also to be found in larger plasmodesmata.We do not know the time nor the manner in which the plasma-channels of our plants originate and disappear. Also it is unknown how the plasmodesmata disappear when the thick callose-membrane is formed around the PMCs and the tetrad-cells.In the tomato the plasma-channels are present before the plasmodesmata disappear. On the other hand they are absent in later stages of tetrad development.The observations are discussed with regard to the possible function of the plasma-channels and their similarity to sievepores.

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An essential saccharide binding domain for the mAb 2C7 established for Neisseria gonorrhoeae LOS by ES-MS and MSn

A study of bacterial surface oligosaccharides were investigated among different strains of Neisseria gonorrhoeae to correlate structural features essential for binding to the MAb 2C7. This epitope is widely expressed and conserved in gonococcal isolates, characteristics essential to an effective candidate vaccine antigen. Sample lipooligosaccharides (LOS), was prepared by a modification of the hot phenol-water method from which de-O-acetylated LOS and oligosaccharide (OS) components were analyzed by ES-MS-CID-MS and ES-MSnin a triple quadrupole and an ion trap mass spectrometer, respectively. Previously documented natural heterogeneity was apparent from both LOS and OS preparations which was admixed with fragments induced by hydrazine and mild acid treatment. Natural heterogeneity was limited to phosphorylation and antenni extensions to the alpha-chain. Mild acid hydrolysis to release OS also hydrolyzed the beta(1-->6) glycosidic linkage of lipid A. OS structures were determined by collisional and resonance excitation combined with MS and multistep MSn which provided sequence information from both neutral loss, and nonreducing terminal fragments. A comparison of OS structures, with earlier knowledge of MAb binding, enzyme treatment, and partial acid hydrolysis indicates a generic overlapping domain for 2C7 binding. Reoccurring structural features include a Hepalpha(1-->3)Hepbeta(1-->5)KDO trisaccharide core branched on the nonreducing terminus (Hep-2) with an alpha(1-->2) linked GlcNAc (gamma-chain), and an alpha-linked lactose (beta-chain) residue. From the central heptose (Hep-1), a beta(1-->4) linked lactose (alpha-chain), moiety is required although extensions to this residue appear unnecessary.      

Effects of yogurt and bifidobacteria supplementation on the colonic microbiota in lactose-intolerant subjects

Aims: Colonic metabolism of lactose may play a role in lactose intolerance. We investigated whether a 2‐week supplementation of Bifidobacterium longum (in capsules) and a yogurt enriched with Bifidobacterium animalis could modify the composition and metabolic activities of the colonic microbiota in 11 Chinese lactose‐intolerant subjects. Methods and Results: The numbers of total cells, total bacteria and the Eubacterium rectale/Clostridium coccoides group in faeces as measured with fluorescent in situ hybridization and the faecal β‐galactosidase activity increased significantly during supplementation. The number of Bifidobacterium showed a tendency to increase during and after supplementation. With PCR‐denaturing gradient gel electrophoresis, in subjects in which B. animalis and B. longum were not detected before supplementation, both strains were present in faeces during supplementation, but disappeared after supplementation. The degree of lactose digestion in the small intestine and the oro‐caecal transit time were not different before and after supplementation, whereas symptom scores after lactose challenge decreased after supplementation. Conclusions: The results suggest that supplementation modifies the amount and metabolic activities of the colonic microbiota and alleviates symptoms in lactose‐intolerant subjects. The changes in the colonic microbiota might be among the factors modified by the supplementation which lead to the alleviation of lactose intolerance. Significance and Impact of the Study: This study provides evidence for the possibility of managing lactose intolerance with dietary lactose (yogurt) and probiotics via modulating the colonic microbiota.     

Discovery and development of a synthetic peptide derived from lactoferrin for clinical use

There is an urgent need to develop new antimicrobial drugs especially for combating the rise of infections caused by multi-resistant pathogens such as MRSA and VRSA. The problem of antibiotic resistant micro-organisms is expected to increase disproportionally and controlling of infections is becoming difficult because of the rapid spread of those micro-organisms. Primary therapy with classical antibiotics is becoming more ineffective. Combinational therapy of antibiotics with antimicrobial peptides (AMP's) has been suggested as an alternative approach to improve treatment outcome. Their unique mechanism of action and safety profile makes AMP's appealing candidates for simultaneous or sequential use in different cases of infections. In this review, for antimicrobial treatment the application of synthetic antimicrobial peptide hLF(1-11), derived from the first 11 amino acids of human lactoferrin is evaluated in both pre-clinical and clinical settings. Present information indicates that this derivate from lactoferrin is well tolerated in pre-clinical tests and clinical trials and thus hLF(1-11) is an interesting candidate for further exploration in various clinical indications of obscure infections, including meningitis. Another approach of using AMP's is their use in prevention of infections e.g. as coating for dental or bone implants or in biosensing applications or useful as infection specific radiopharmaceutical.     

Reconstitution of the gastrointestinal microflora of lactobacillus-free mice.

A colony of mice that do not harbor lactobacilli in their digestive tracts but whose intestinal microflora is otherwise functionally similar to that of conventional animals was derived. Methods used to reconstitute the intestinal microflora of the mice included inoculation of the animals with cultures of specific microbes, noncultivable microbes attached to epithelial cells, and cecal contents from conventional mice treated with chloramphenicol. Twenty-six microflora-associated characteristics were monitored by using relatively simple tests to determine the microflora status of the mice.     

Glycoprotein H of herpes simplex virus type 1 requires glycoprotein L for transport to the surfaces of insect cells.

In mammalian cells, formation of heterooligomers consisting of the glycoproteins H and L (gH and gL) of herpes simplex virus type 1 is essential for the cell-to-cell spread of virions and for the penetration of virions into cells. We examined whether formation of gH1/gL1 heterooligomers and cell surface expression of the complex occurs in insect cells. Three recombinant baculoviruses, expressing gL1, gH1, and truncated gH1 (gH1t), which lacks the transmembrane region, were constructed. It was shown that recombinant gH1/gL1 and gH1t/gL1 heterooligomers were produced in insect cells. As in mammalian cells, gH1 and gH1t were not detected on the surfaces of insect cells in the absence of gL1. When coexpressed with gL1, recombinant gH1 was displayed on the surfaces of insect cells. Coexpression of gH1t and gL1 resulted in secretion of the gH1t/gL1 complex into the cell culture medium, indicating that gH1t is also transported to the surfaces of insect cells. Our results indicate that the process of folding and intracellular transport of gH1 and gL1 is comparable in insect cells and mammalian cells and that the baculovirus expression system can be used to examine the complex formation and the intracellular transport of gH1 and gL1. The availability of secreted gH1t/gL1 complex offers the opportunity to further investigate the immunological properties of this complex.     

The 'normalization' of germ-free guineapigs with host-specific caecal microflora

Hysterectomy-derived germ-free guineapigs were given colonization-resistant caecal flora from mice (mCRF) or microflora obtained from the caecum of an antibiotic-decontaminated conventional guineapig (gpCRF) and compared with guineapigs raised conventionally with the sow. Body weight and the following intestinal parameters were determined for the groups: colonization resistance (CR) to Escherichia coli, relative caecal weight (RCW), beta-aspartylglycine (faeces), volatile fatty acids (caecum) and bile acids (faeces). mCRF guineapigs showed values quite different from control animals for CR and RCW, indicating the unsuitability of mouse CRF for normalizing guineapigs. In gpCRF guineapigs CR and RCW values were comparable with controls, indicating the suitability of the guineapig flora for normalizing guineapigs. mCRF guineapigs housed with gpCRF guineapigs, showed an improvement in CR and RCW, yielding values found in control animals.