Beobachtungen am Horst des Schwarzen Storches (Ciconia nigra L.)

Ohne ZusammenfassungMit freundlicher Genehmigung des Verlages entnommen dem soeben erschienenen Buche: Störche. Erlebnisse mit dem Schwarzen und Weißen Storch. VonHorst Siewert, Berlin 1932. Verlag vonDietrich Reimer. 8°. 208 Seiten, mit 80 Bildertafeln nach Aufnahmen des Verfassers. Leinenband Preis M. 4.80.     

Eolimna martinii n. gen., n. sp. (Bacillariophyceae) aus dem Unter-Oligozän von Sieblos/Rhön im Vergleich mit ähnlichen rezenten Taxa

The laminated sediments of the Lower Oligocene ‘Sieblos-Schichten’ (dysodile and kieselgur-sediments) contain many individuals of a naviculoid diatom species. Formerly this group of diatoms would have been classified without doubt as Navicula (section ‘Minusculae’). After splitting this extremely heterogeneous genus in Navicula sensu stricto and some other homogeneous genera, the pattern of structures of this fossil species does not correspond to any established genus. For that reason this form will be described as the generotype of a new genus Eolimna. Furthermore it became evident that some Recent species (assigned to Navicula) show the same pattern of structures as the new genus Eolimna (generotype: E. martinii) which represents one of the first naviculoid diatoms of limnic origin. The essential criteria of this genus are: comparatively small cells with narrow girdle; simple alveolated rib system; areolae with a hymen in approximately medium position between relatively large sized foramina outside and inside of the valve; a single row of more or less irregular arranged areolae in close position to each other, on one or several of the copulae. The differences to supposed related genera are discussed.     

Induction of callose formation is a sensitive marker for genotypic aluminium sensitivity in maize

The screening of 37 Zea mays L. cultivars in nutrient solution using root elongation (24 h) as a parameter showed large genotypic differences in Al resistance among the genetic material evaluated.Callose concentrations in root tips were closely and positively related to Al-induced inhibition of root elongation. Therefore, Al-induced callose formation in root tips appears to be an excellent indicator of Al injury and can be used as a selection criteria for Al sensitivity. In contrast, aluminium concentrations in root tips were not related to Al-induced inhibition of root elongation, nor to Al-induced callose formation. Callose formation was also induced by short-term A1 treatment in root tip protoplasts, and the response of protoplasts clearly reflected the cultivar-specific response to Al of intact roots. This indicates that in maize, Al sensitivity is expressed on the protoplast level.     

The helper T-cell repertoire of mice expressing class II major histocompatibility complex β chains in the absence of α chains

 Mutant mice generated by disrupting the H2-Aa ^b major histocompatibility complex (Mhc) gene are demonstrated here to express Aβ^b chains in the absence of α chains. These mice possess a CD4⁺ helper T cell (Th) repertoire that uses predominantly the Vβ7 T-cell antigen receptor (Tcr) segment for recognition of any protein antigen presented by the α-free Aβ molecule. As an alloantigen, the Aα-free Aβ molecule is recognized very poorly by T cells from a series of class II disparate mouse strains, indicating that it is grossly different from normal α/β heterodimers. Indeed, molecular modeling suggests a β/β homodimer arrangement with an altered geometry of the Tcr contact area. Interestingly, the mutant mice exhibit normal alloreactivity, without a restricted Vβ usage, toward a series of foreign α/β class II heterodimers, although their T cells developed in the absence of such heterodimers. Thus, the complementarity of Tcr to normal α/β heterodimers, and thereby also alloreactivity, appears to be an ontogeny independent (i. e., germline-encoded) feature. Received: 30 September 1996 / Revised: 18 October 1996     

Progesterone receptor repression by estrogens in rat uterine epithelial cells

Measurements performed using cell lines or animal tissues have shown that the progesterone receptor (PR) can be induced by estrogens. By use of immunohistochemistry we studied the effects of estrogens on the PR levels in the individual cell types of the target organs uterus and breast. In the uteri of rats, ovariectomy induced a decrease in PR immunoreactivity within the myometrium and outer stromal cell layers. In contrast, in the uterine luminal and glandular epithelium and surrounding stromal cell layers the PR immunoreactivity was significantly enhanced. The same picture emerged when intact rats were treated with the pure estrogen receptor antagonist, ZM 182780 (10 mg/kg/d). Treatment of ovariectomized rats with estradiol resulted in high PR levels in the myometrium and stroma cells but low PR immunoreactivity in the epithelial cells. The ER-mediated repression of the PR immunoreactivity was evidently restricted to the uterine epithelium, as we found that in the epithelial cells of the mammary gland and in cells of N-nitrosomethylurea-induced mammary carcinomas the PR expression was induced by estrogens and was blocked by the pure antiestrogen ZM 182780. These results clearly show that in the rat the activated ER induces diverging effects on PR expression in different cell types even within the same organ.     

Stetteria hydrogenophila, gen. nov. and sp. nov., a novel mixotrophic sulfur-dependent crenarchaeote isolated from Milos, Greece

A new hyperthermophilic, strictly anaerobic crenarchaeote, Stetteria hydrogenophila DSM11227 representing a new genus within the family of Desulfurococcaceae, was isolated from the sediment of a marine hydrothermal system at Paleohori Bay in Milos, Greece. Cells are gram-negative irregular and disc-shaped cocci, 0.5–1.5 μm in diameter, which are flagellate and can form cytoplasmatic protrusions up to 2 μm in length. The strain grew optimally at 95°C at pH 6.0 and at a NaCl concentration of 3%. The organism grew mixotrophically on peptide substrates. It required elemental sulfur as an external electron acceptor, and in addition, its growth was completely dependent on the presence of molecular hydrogen. Sulfur could be replaced by thiosulfate. H₂S, CO₂, acetate, and ethanol were identified as products of metabolism. The G + C content of DNA was 65 mol%. Analysis of its phylogenetic position by sequence analysis of 16S rRNA placed this organism in the family of Desulfurococcaceae. The dependence of this organism on both hydrogen and sulfur during growth on peptide substrates distinguishes Stetteria from all previously described species of Crenarchaeota. Received: September 4, 1996 / Accepted: November 12, 1996     

Combined immunophenotyping and FISH with sex chromosome-specific DNA probes for the detection of chimerism in epidermal Langerhans cells after sex-mismatched bone marrow transplantation

 Langerhans cells (LC) of the skin represent bone marrow-derived dendritic antigen-presenting cells and are therefore important in pathophysiological processes such as rejection, graft-versus-host disease, and graft-versus-leukemia-reaction after bone marrow transplantation (BMT). For understanding of these diseases, the evaluation of the chimeric status of LC following BMT is of great interest. To analyze the sex chromosome constitution of LC in the skin, we established a modified and refined technique of combined immunophenotyping and fluorescence in situ hybridization (FISH) and investigated frozen sections of skin biopsies from nine patients after allogeneic sex-mismatched BMT and of two healthy donors for control. LC were specifically labeled using a fluorescent CD1a antibody and hybridized simultaneously with X and Y chromosome-specific DNA probes. The results of this practical application on nine leukemia patients show the appearance of donor-type LC and the persistence of host-type LC at various times (36 up to 1395 days) after sex-mismatched BMT. Complete chimerism of LC could not be detected in any case. The frequency of recipient-specific LC ranged from 7% to 92% and showed no correlation with time postgrafting. We conclude from our results of 1461 analyzed LC that combined immunophenotyping and interphase cytogenetic analysis by FISH is the method of choice for the assessment of chimerism in a particular cell type after sex-mismatched BMT. Its practical application on other tissues affected by BMT-related pathophysiological processes reveals further knowledge of the time-dependent course of chimeric patterns after BMT. Accepted: 18 July 1996     

The mitochondrial protein import motor: dissociation of mitochondrial hsp70 from its membrane anchor requires ATP binding rather than ATP hydrolysis.

During protein import into mitochondria, matrix-localized mitochondrial hsp70 (mhsp70) interacts with the inner membrane protein Tim44 to pull a precursor across the inner membrane. We have proposed that the Tim44-mhsp70 complex functions as an ATP-dependent "translocation motor" that exerts an inward force on the precursor chain. To clarify the role of ATP in mhsp70-driven translocation, we tested the effect of the purified ATP analogues AMP-PNP and ATP gamma S on the Tim44-mhsp70 interaction. Both analogues mimicked ATP by causing dissociation of mhsp70 from Tim44. ADP did not disrupt the Tim44-mhsp70 complex, but did block the ATP-induced dissociation of this complex. In the presence of ADP, mhsp70 can bind simultaneously to Tim44 and to a peptide substrate. These data are consistent with a model in which mhsp70 first hydrolyzes ATP, then associates tightly with Tim44 and a precursor protein, and finally undergoes a conformational change to drive translocation.