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Notes: Zusammenfassung Elektronenmikroskopische Untersuchungen an bioptisch gewonnenen Partikeln der Korpusschleimhaut lassen einen Funktionscyclus vor allem an den Hauptzellen erkennen. Nach Stimulation der Magensekretion mit Pentagastrin kommt es zur Häufung von Lysosomen und ihrer Ausstoßung in das Lumen sowie zu einem Verlust des endoplasmatischen Reticulums. Dieser Sekretionsphase folgt eine Regenerationsphase mit Wiederaufbau des endoplasmatischen Reticulums. Nach 5 1/2 Std ist der Zustand der sekretorischen Ruhephase wieder erreicht. Die ultrastrukturellen Veränderungen der Magenschleimhaut in der Sekretionsphase ähneln dem nach Betazol-Injektion beschriebenen Bild, sind jedoch schwächer ausgeprägt. Die Festlegung des zeitlichen Ablaufs der Ultrastrukturveränderungen ist für weitere Untersuchungen über die Wirkung entzündungshemmender Pharmaka und auch für Funktionsstudien bei der Gastritis bedeutsam.

Notes: [Auszug] During the division of a ciliate, two main categories of micro-tubule arrays can be distinguished: cytoplasmic and nucleoplas-mic. Nuclear envelopes remain intact and large numbers of aligned nucleoplasmic microtubules are associated with the marked elongation of dividing nuclei (Fig. l)12'13. ...

Notes: [Auszug] We used the model system for exposing lung explants to puffs of fresh smoke in standardized conditions2. Lung explants were prepared and exposed to cigarettes made from marijuana or Kentucky Standard tobacco as previously described1. Normal lung tissue was obtained not only from older patients ...

Notes: Abstract  A microbial peptide amidase was found in a limited screening and purified about 500-fold from Stenotrophomonas maltophilia. The native enzyme has a molecular mass of 38 kDa (gel filtration). The sequence of the first 16 amino acids was determined by Edman degradation. The isoelectric point was found to be around 5.8. The peptide amidase exhibited a pH optimum of 6.0 and a temperature optimum of about 39–45°C. The enzyme is stable in 50 mM TRIS/HCl, pH 7.5, at 30°C, and the residual activity was found to be above 90% after 1 week of incubation. The biocatalyst is not inhibited by potential inhibitors like Hg2+, EDTA, D-cycloserine or dithiothreitol and only weakly influenced by inhibitors of serine proteases. The peptide amidase deamidates selectively C-terminal amide groups in peptide amides without hydrolysing internal peptide bonds or amide functions in the side-chain of glutamine or asparagine. Unprotected amino acid amides are not hydrolysed. The enzyme is stereoselective with regard to L-enantiomers in the C-terminal position.

Notes: Abstract A microbial peptide amidase was found in a limited screening and purified about 500-fold from Stenotrophomonas maltophilia. The native enzyme has a molecular mass of 38 kDa (gel filtration). The sequence of the first 16 amino acids was determined by Edman degradation. The isoelectric point was found to be around 5.8. The peptide amidase exhibited a pH optimum of 6.0 and a temperature optimum of about 39–45°C. The enzyme is stable in 50 mM TRIS/HCl, pH 7.5, at 30°C, and the residual activity was found to be above 90% after 1 week of incubation. The biocatalyst is not inhibited by potential inhibitors like Hg2+, EDTA, d-cycloserine or dithiothreitol and only weakly influenced by inhibitors of serine proteases. The peptide amidase deamidates selectively C-terminal amide groups in peptide amides without hydrolysing internal peptide bonds or amide functions in the side-chain of glutamine or asparagine. Unprotected amino acid amides are not hydrolysed. The enzyme is stereoselective with regard to l-enantiomers in the C-terminal position.

Notes: Abstract To elucidate the possible mechanism of disturbances in chromosome segregation leading to the increase in aneuploidy in oocytes of aged females we examined the meiotic spindles of CBA/Ca mice. Employing immunofluorescence with an anti-tubulin antibody, and human scleroderma serum, as well as 4′-6-diamidino-2-phenylindole (DAPI) staining of chromosomes the microtubular cytoskeleton could be visualized, and the behaviour of chromosomes and centromeres of oocytes spontaneously maturing in vitro could be studied. The morphology of spindles during the first meiotic division was not conspiciously different in oocytes from young and aged mice as far as the cytoskeletal elements were concerned. Neither multipolar spindles nor pronounced cytoplasmic asters appeared in oocytes of mice approaching the end of their reproductive life (9 months and older). Oocytes of aged females also did not exhibit any sign of premature separation of parental chromosomes at prophase, obvious malorientations of bivalents, or significant lagging of chromosomes during ana and telophase. Metaphase I with all bivalents aligned at the spindle equator appeared to be a relatively brief stage in oocyte development compared with pro-and prometaphase. Therefore, already slight disturbances occuring in the timing of the developmental programme which leads to a premature anaphase transition may be responsible for the high incidence of chromosomally unbalanced gametes in aged females, rather than non-separation and lagging of chromosomes during late ana-and telophase. In a second set of experiments we compared the metaphase II spindles of spontaneously ovulated oocytes obtained from animals at different ages. Previous studies have shown that spindle length and chromosome alignment may be altered in cells predisposed to aneuploidy. To distinguish between the significance of the chronological age of the female and the physiological age of the ovaries (as indicated by the total number of oocytes remaining) we examined the spindle apparatus in young (3–4 months old) and aged (9 months and older) mice as well as CBA females which had been unilaterally ovariectomized (uni-ovx) early in adult life and were approaching the end of their reproductive life at 6–7 months of age. Measurements of the pole-to-pole distance implied that spindle length may be related to maternal age. In oocytes of aged (9 month), uni-ovx (6 month) as well as 6-month-old sham-operated controls the metaphase II spindle was significantly shorter than in oocytes of young mice. By contrast, chromosome disorder and displacement was most pronounced in the aged and uni-ovx mice whilst most oocytes from young mice and moderately aged shamtreated controls exhibited a more regular alignment of chromosomes. These results, which are consistent with recent findings in CBA mice of an increased rate of aneuploidy in females approaching the end of their reproductive life, are discussed with respect to the hypothesis that the aetiology of aneuploidy rests on the critical timing of different events in oocyte development.

Notes: Abstract Exposure of Nyctotherus ovalis to low temperatures or vinblastine caused similar reactions of “classes” of microtubules (mt) present in the mitotic micronucleus of this ciliate towards both treatments. However, differences of sensitivity between certain “classes” of mt at individual mitotic stages exist. Unlike the kinetochore mt (kmt) of most other eukaryotic cells, kmt in Nyctotherus completely disassemble after incubation at 6–8 ° C (60 min) and most disappear after prolonged exposure to vinblastine (10−5 M, 16 h). The depolymerization of kmt causes the collapse of the spindle and a dislocation of chromosomes at metaphase, yet the reduced number of kmt after vinblastine-treatment still allows an alignment of composite complexes at the spindle equator. The data suggest that three individual sets of mt exist in the interpolar spindle region during ana- and telophase: 1) interpolar mt (int mt), which are assembled during anaphase, are cold- and vinblastine sensitive; 2) manchette mt (ma mt), which are first observed underneath the nuclear envelope during mid-anaphase, are cold-stable and insensitive to vinblastine treatment (10−5 M); after prolonged treatment (16 h) they form spiral structures; 3) stembody mt (st mt), comprising the interpolar region of the nucleus during telophase, are cold- and vinblastine insensitive. Paracrystalline structures resembling a stembody are formed in telophase-like division stages after prolonged vinblastine exposure (16 h, 10−5 M). Since kmt and int mt possess the same sensitivity under depolymerizing conditions, they probably have a similar composition. Thus the idea that the int mt in this organism arise by elongation of kmt is supported. However, st mt apparently do not originate from an extension of preexistent int mt, but appear to represent a new set of stable mt. This is emphasized not only by their greater stability compared to the int mt but also by the distribution of cold-stable mt in late anaphase micronuclei. The ma mt may be an intermediary step in formation of st mt since their stability resembles that of the st mt. A comparison of the substructure of vinblastine-induced paracrystals in Nyctotherus with those observed in in vitro systems with known composition suggests that a turnover of MAPs may be responsible for the different stability of mt and thus could specify and regulate mt sensitivity and function. Another organelle, possibly involved in conferring stability to mt, is the nuclear membrane. The assumption that the nuclear envelope possesses an intrinsic property to nucleate mt and thus aid in the alignment of mt is supported.

Notes: Abstract Alterations in the organization of the microtubular cytoskeleton and chromosome alignment were examined by tubulin immunofluorescence and DAPI staining during in vivo ageing of naturally ovulated, metaphase-arrested oocytes of CBA/Ca mice in the fallopian tubes. In oocytes isolated from young mice on the day of oestrus, a few hours after ovulation, when they are still tightly surrounded by cumulus, the anti-tubulin fluorescence is almost exclusively restricted to the metaphase spindle. Only some faintly staining foci are observed in the cytoplasm, which presumably represent cytoplasmic MTOC not involved in spindle formation. The spindle is usually barrel-shaped or slightly pointed at its poles and does not possess astral fibres. In oocytes aged for more than 12 h in the fallopian tubes cytoplasmic asters develop, while microtubules seem to become gradually lost from the spindle, preferentially in its central area near the chromosomes. Astral fibres are observed radiating out from the polar centrosomes into the cytoplasm. In oocytes free of cumulus, and consequently more than 24 h post-ovulation, a pronounced shrinking of the spindle is observed. The mean pole-to-pole distance becomes significantly reduced in postovulatory aged cells. At the same time astral microtubules in the cytoplasm appear to become gradually depolymerized. Age-dependent alterations in the microtubular cytoskeleton do not seem to result from a changed pattern of the post-translational detyrosylation of α-tubulin in certain sets of microtubules. In freshly ovulated oocytes chromosomes in most spindles are well ordered and precisely arranged at the equatorial plane. In 11% of the cells only, there was dislocation of one or several of the chromosomes from the spindle equator. By contrast, 61.4% of bipolar spindles of postovulatory aged oocytes have chromosomes displaced from the centre of the spindle towards one of the spindle poles. The implications of the observed alterations in the microtubular cytoskeleton, shrinking of the spindle and increased disorder of chromosome alignment are discussed with regard to predisposition to aneuploidy and reduction of developmental potential of postovulatory aged oocytes.