Elektronenmikroskopische Untersuchungen am Nucleus praeopticus der Kröte (Bufo vulgaris formosus)

Zusammenfassung Die Feinstruktur der neurosekretorischen Nervenzellen des Nucleus praeopticus magnocellularis der Kröte (Bufo vulgaris formosus) und ihre Umgebung wurde untersucht.Die neurosekretorischen Zellen enthalten drei Arten von osmiophilen Gebilden: die neurosekretorischen Elementargranula, die neurosekretorischen Kügelchen und die Einschlußkörper.Die neurosekretorischen Elementargranula besitzen einen Durchmesser von 1000–3000 Å, durchschnittlich von 1300–1500 Å. Sie entstehen im Golgi-Apparat (Perikaryon) der betreffenden Zellen wie bei den schon beschriebenen anderen Tierarten.Die neurosekretorischen Kügelchen haben einen Durchmesser von 4000 Å bis zu mehreren . Sie kommen zuerst in den Ergastoplasmacisternen des Perikaryons vor und wandern dann innerhalb des Axons caudalwärts ab, ebenso wie die Elementargraunla, verlieren sich aber vor dem Erreichen der Neurohypophyse. Nach Lage und Gestalt entsprechen sie den Kolloidtropfen, die von vielen Lichtmikroskopikern für die neurosekretorischen Zellen niederer Vertebraten beschrieben wurden.Die Einschlußkörper treten vornehmlich im zentralen Bezirk des Perikaryons in Erscheinung. Sie sind so groß wie die Mitochondrien und besitzen verschiedene Innenstrukturen. Auf Grund der Struktur und der histochemischen Reaktion möchten wir diese Einschlußkörper den Lipofuscingranula mit saurer Phosphatase zuordnen.Die neurosekretorischen Nervenzellen schmiegen sich an den die Kapillare umgebenden Perivaskularraum unmittelbar an, innerhalb dessen die Basalmembran unvollkommen ausgebildet ist oder ganz fehlt.Stellenweise dehnt sich ein Abschnitt des Endothels durch den Perivaskularraum hindurch entlang der Außenfläche des Perivaskularraums aus, wobei sich die Endothelzellen der Kapillare und die neurosekretorischen Nervenzellen direkt berühren können. Eine poröse Bauweise des Endothels wurde nicht nachgewiesen. Zwischen den Ependymzellen des III. Ventrikels und den darunterliegenden neurosekretorischen Nervenzellen sind oftmals auffallend große Extrazellularräume zu beobachten, die durch den Spaltraum der benachbarten Ependymzellen mit dem Ventrikellumen kommunizieren. Sie enthalten mikrovilliartige Ausläufer der Ependymzellen und die geschilderten, neurosekretorische Bildungen führenden Axone. Eine Ausstoßung dieser Axone in den Ventrikel wurde nicht festgestellt.Diese Untersuchung wurde zum Teil mit finanzieller Unterstützung durch das Japanische Unterrichtsministerium im Jahre 1963 durchgeführt.Der kurze Inhalt dieser Arbeit wurde unter dem Thema 'Electron microscopic studies on the praeoptic nucleus in the toad am 5. und 6. September 1963 auf dem Kongreß für Endokrinologie in Gunma, Japan, vorgetragen.     

Intraspecific hybridization and its bearing on chromosome evolution inVicia narbonensis (Fabaceae)

Nine accessions ofVicia narbonensis, considered to be the wild progenitor of faba bean (Vicia faba), were investigated to ascertain the nature and extent of intraspecific karyotypic polymorphism. The chromosome complements resolved into four distinct types (A, B, C, D), and the meiotic data of F₁ hybrids (A × B, B × C, A × C) revealed that alteration in chromosome morphology is the result of segmental interchanges. The interchange complexes indicate that the parents differ from each other by 1 to 2 interchanges. It is also evident that karyotype B, and not A as previously reported, is the normal karyotype of the species, and A and C are single homozygotes for unequal interchange. The comparative karyomorphology of the parents and the hybrids, and of two interchange heterozygotes of four chromosomes each in F₁ hybrids of A × C shows that the chromosomes involved in the single interchange homozygotes (A, C) are not common and the breaks in both interchanges occurred in short and long arms of the involved chromosomes. Identification of the interchanged chromosomes in the complements and the frequency of ring and chain quadrivalents in the heterozygotes enabled location of the breakpoints. The present results provide probably the first example indicating that interchange homozygosity (A) is not only firmly established but also has enabled the species to spread further by adapting to a wide range of habitats. — The genetic relationships between A and D are very different. All seven chromosome pairs in D could be distinguished from A, and for that matter, B and C as well. From the meiotic pairing properties it is also amply clear that genome D is well differentiated from A and possibly B, and C, and deserves special status.     

Isolation of human retinal genes: recoverin cDNA and gene.

A human retina cDNA library enriched for retina-specific clones was prepared by subtraction with a non-retina population of cDNA in combination with polymerase chain reaction (PCR) amplifications. A highly retina-specific cDNA clone (1190 bp) was obtained through this library encoding a 200 amino acid protein with three calcium binding sites and 87% homology to the bovine photoreceptor protein, recoverin, which has been shown to mediate the recovery of the dark current after photoactivation, and 58% homology to the calcium-binding chick cone protein, visinin. Analysis of the gene indicated a 9-10 kb single-copy gene with at least three exons and two introns. The three exons contained the entire coding sequence, and all of the calcium-binding EF-hand regions were in putative exon 1. The recoverin gene was mapped to human chromosome 17 by hybridization to a panel of human-rodent hybrid DNAs.     

Characterization of human thyrotropin receptor-related peptide-like immunoreactivity in peripheral blood of Graves' disease.

An antiserum raised against an alignment of amino acid-(32-56), termed TSHRP-1, in the extracellular domain of human thyrotropin (TSH) receptor was used to identify the TSH receptor-like substance in plasma of Graves' disease. The dilution curve of plasma TSHRP-1-like immunoreactivity was observed in a manner parallel to the standard synthetic peptide curve in radioimmunoassay, and its molecular weight estimated approximately 60 kDa. The amounts of TSHRP-1-like immunoreactivity were significantly higher in Graves' plasma than those in plasma of normal and hypothyroid patients due to Hashimoto's thyroiditis. The present results indicate that human peripheral blood possesses a soluble form of the extracellular domain of TSH receptor which may contribute to the pathophysiology of Graves' disease.     

Effect of penicillin G on the electroporation of Rhodococcus rhodochrous CF222

M. SUNAIRI, N. IWABUCHI, K. MURAKAMI, F. WATANABE, Y. OGAWA, H. MUROOKA AND M. NAKAJIMA. 1996. Suitable conditions for the introduction of bacteriophage DNA into cells of Rhodococcus rhodochrous CF222 by electroporation were established, and penicillin G was found to enhance the transfection frequency. When conditions optimal for the parental strain were applied to its colony-morphological mutants, different transfection frequencies were observed. Penicillin G enhanced the transfection frequency of smooth and mucoidal mutants but not of rough mutants.     

Induction and Repair of Damage to DNA in Cucumber Cotyledons Irradiated with UV-B

Photoinduced lesions in DNA, namely, cyclobutane pyrimidinedimers (CPDs) and pyrimidine-(6-4)-pyrimidone photoproducts[(6-4)photoproducts], in cucumber cotyledons that had been irradiatedwith naturally occurring levels of UV-B (290–320 nm) werequantitated by enzyme-linked immunosorbent assays with monoclonalantibodies specific to each type of photolesion. Induction ofthese photolesions was dependent on temperature and their extentwas reduced by simultaneous irradiation with white light. Thedark repair of both types of photolesion was undetectable. Light-dependentremoval of (6-4)photoproducts was very slow, with 50% removalin 4 h. By contrast, 50% of initial CPDs were removed within15 min. Both photorepair processes were dependent on the intensityof white light and were sensitive to temperature. These resultsindicate that high photolyase activity is present in cucumbercotyledons and that repair activities in cucumber cotyledonsare different from those reported in Arabidopsis, in which (6-4)photoproductsare photorepaired more rapidly than CPDs. (Received October 13, 1995; Accepted December 28, 1995)