Biochemical and cytogenetic studies on the Nucleolus Organizing Regions (NOR) of Man

Summary The hybridization kinetics of DNA with labeled (18s+28s)rRNA from HeLa cells was determined in patients with trisomy 21, healthy probands with normal karyotype and in carriers of a t(DqGq) centric fusion. The results are in, accordance with the saturation values obtained earlier for these probands:Three patients with trisomy 21 showed an increased saturation level. In 2 of these patients the excess of rDNA exceeded the expected value considerably.Three of the investigated translocation carriers t(14q21q) showed significantly reduced saturation values, while results of a fourth proband with a dicentric chromosome t(15q21q) were found to be within the range of normal probands.The heterogeneous results were correlated with the cytogenetic characteristics of the acrocentric chromosomes. It is expected that these differences could be explained on the basis of family analysis.

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Zusammenfassung Hybridisierungskinetiken der DNA mit markierter (18s+28s)rRNA aus HeLa-Zellen wurden ermittelt bei Patienten mit Trisomie 21, gesunden Probanden mit normalem Karyotyp und Trägern einer zentrischen Fusion t(DqGq). Die Ergebnisse bestätigen die bereits früher ermittelten Sättigungswerte von Hybridisierungen bei diesen Probanden:3 Patienten mit Trisomie 21 zeigten erhöhte Sättigungsniveaus. Bei 2 dieser Patienten übersteigt der Überschuß an rDNA den Erwartungswert erheblich.3 der untersuchten Translokationsträger t(14q21q) hatten signifikant erniedrigte Sättigungswerte, während die vierte Probandin mit dem dizentrischen Chromosom t(15q21q) im Normbereich lag.Die unterschiedlichen Befunde werden mit den cytogenetischen Eigenschaften der akrozentrischen Chromosomen in Zusammenhang gebracht. Es wird erwartet, daß diese Unterschiede sich durch Familienuntersuchungen aufklären lassen.

     

Interrelationships of Staphyliniform groups inferred from 18S and 28S rDNA sequences, with special emphasis on Hydrophiloidea (Coleoptera, Staphyliniformia)

The series Staphyliniformia is one of the mega‐diverse groups of Coleoptera, but the relationships among the main families are still poorly understood. In this paper we address the interrelationships of staphyliniform groups, with special emphasis on Hydrophiloidea and Hydraenidae, based on partial sequences of the ribosomal genes 18S rDNA and 28S rDNA. Sequence data were analysed with parsimony and Bayesian posterior probabilities, in an attempt to overcome the likely effect of some branches longer than the 95% cumulative probability of the estimated normal distribution of the path lengths of the species. The inter‐family relationships in the trees obtained with both methods were in general poorly supported, although most of the results based on the sequence data are in good agreement with morphological studies. In none of our analyses a close relationship between Hydraenidae and Hydrophiloidea was supported, contrary to the traditional view but in agreement with recent morphological investigations. Hydraenidae form a clade with Ptiliidae and Scydmaenidae in the tree obtained with Bayesian probabilities, but are placed as basal group of Staphyliniformia (with Silphidae as subordinate group) in the parsimony tree. Based on the analysed data with a limited set of outgroups Scarabaeoidea are nested within Staphyliniformia. However, this needs further support. Hydrophiloidea s.str., Sphaeridiinae, Histeroidea (Histeridae + Sphaeritidae), and all staphylinoid families included are confirmed as monophyletic, with the exception of Hydraenidae in the parsimony tree. Spercheidae are not a basal group within Hydrophiloidea, as has been previously suggested, but included in a polytomy with other Hydrophilidae in the Bayesian analyses, or its sistergroup (with the inclusion of Epimetopidae) in the parsimony tree. Helophorus is placed at the base of Hydrophiloidea in the parsimony tree. The monophyly of Hydrophiloidea s.l. (including the histeroid families) and Staphylinoidea could not be confirmed by the analysed data. Some results, such as a placement of Silphidae as subordinate group of Hydraenidae (parsimony tree), or a sistergroup relationship between Ptiliidae and Scydmaenidae, appear unlikely from a morphological point of view.     

Specific silver staining of experimentally undercondensed chromosome regions

Treatment of human and mouse cell cultures with DNA binding AT-specific compounds and with some base analogues induced distinct undercondensations in several heterochromatic chromosome regions. All those heterochromatic regions undercondensed by AT-specific DNA ligands (distamycin A, DAPI, Hoechst 33258) could be heavily labeled with the silver(Ag)-staining technique; but the heterochromatic regions undercondensed with the cytidine analogue 5-azacytidine were Ag-negative. In metaphase chromosomes from BrdU-treated human cell cultures, the bifilarly substituted chromatids, which show a slight undercondensation, were also Ag-negative. Cytochemical analyses of the Ag-stained undercondensed heterochromatic regions showed that the Ag-stainable material consisted of nonhistone proteins. The mechanism of Ag staining in the undercondensed heterochromatic regions was compared with Ag staining of the nucleolus organizer regions.     

Effect of feeding boxes on the behavior of stereotyping amur tigers (Panthera tigris altaica) in the Zurich Zoo,Zurich, Switzerland

The stereotyped pacing shown by the two Amur tigers in the Zurich Zoo was hypothesized as being caused by permanently frustrated appetitive foraging behavior. Several electrically controlled feeding boxes were installed and access to each box was possible only twice a day for 15 min at semi‐random times. The boxes had to be opened actively by the tigers. Two trials were carried out: one with solitary confinement, and one with paired confinement. During box feeding, the female's stereotyped pacing was significantly reduced from 16% (solitary confinement, conventional feeding) and 7% (paired confinement, conventional feeding) to 1% (solitary confinement) and less than 0.01% (paired confinement) of the daily observed time. The female's sleeping increased significantly in both solitary and paired confinement. The male only showed a significant reduction in stereotyped pacing behavior when kept with the female (conventional feeding: 10%; box feeding: <0.01% of the daily observed time). On days with a box‐feeding regime in paired confinement, the male spent 25% (83 min) of the observed time with active behavior at the feeding boxes. The results support the hypothesis that permanently frustrated appetitive foraging behavior causes stereotyped pacing in adult tigers. Zoo Biol 21:573–584, 2002. © 2002 Wiley‐Liss, Inc.     

Fragility and spiralization anomalies of the chromosomes in three cases, including fraternal twins, with Fanconi's anemia, type Estren-Dameshek

Fraternal twins, offspring of consanguineous parents, developed pancytopenia, the boy at 7, the girl at 12 years of age. A third patient became anemic at 3 years. All three are free of associated malformations. In blood cultures the incidence of chromatid breaks, exchanges, and chromosome-type aberrations was elevated to 24%, 18%, and 28%, respectively. In addition, in a low number of mitotic cells unusual observations, pointing to profound disturbances of chromosome structure, were made. It is suggested that these patients have a genetic defect impairing the normal process of mitotic chromosome condensation and decondensation.     

Mitotic spindle damage induced by 2-chlorobenzylidene malonitrile (CS) in V79 Chinese hamster cells examined by differential staining of the spindle apparatus and chromosomes.

A 3-h exposure of V79 Chinese hamster cells with the sensory irritant 2-chlorobenzylidene malonitrile (CS) caused apolar mitoses in a dose-dependent manner. With a preparation and staining technique that allows for the visualization of the spindle apparatus and the chromosomes it was found that unlike in Colcemid-induced c-metaphases residual spindle fibers or microtubule material were present in the majority of CS-induced c-metaphases. The observation suggests different mechanisms for the induction of the c-mitotic effect by the two spindle poisons.