Cytological and cytogenetical studies on brain tumors

Summary Twelve out of 88 cytogenetically examined meningiomas of female patients showed, in addition to the typical loss of a chromosome 22, a loss of 1 or more chromosomes of group C. Among them 8 tumors had less than 8% cells with Barr-body-like particles, whereas in one tumor 12% and in 3 others over 20% Barr bodies were found, which, based on control studies, were classified as sex-chromatin negative, partly positive, and positive, respectively. In one case the loss of an X chromosome was verified by Giemsa banding.In 6 out of 24 meningiomas of male origin, the chromosoma. morphology and association pattern strongly indicated that besides the loss of a chromosome 22, the Y chromosome was also missing. Moreover, the loss of the male sex chromosome could be ascertained in 4 tumors by the conspicuous absence of Y fluorescence in interphase nuclei and in metaphase plates after fluorescence staining.The findings are discussed in connection with the gonosomal loss in other human tumors and in old age.

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Zusammenfassung Unter 88 cytogenetisch untersuchten Meningeomen von Frauen wurden 12 Tumoren gefunden, bei denen außer dem für Meningeome typischen Verlust eines Chromosoms 22 auch ein oder mehrere Chromosomen der C-Gruppe verlorengegangen waren. Bei 8 dieser Tumoren konnte in Gewebekulturpräparaten nur in weniger als 8% der untersuchten Zellen Barr-body-ähnliche Kernstrukturen nachgewiesen werden, bei einem Tumor fanden sich 12% und bei 3 über 20% Barr-bodies. Auf Grund von Vergleichsuntersuchungen wurden 8 Tumoren als geschlechtschromatinnegativ, 1 Tumor als teilweise positiv und die übrigen 3 als eindeutig positiv eingestuft. Bei einem Meningeom konnte das Fehlen eines X-Chromosoms direkt mit der Giemsa-Bandentechnik nachgewiesen werden.Bei 6 von 24 Meningeomen männlicher Herkunft konnte auf Grund der Chromosomenmorphologie und des Assoziationsverhaltens sehr wahrscheinlich gemacht werden, daß außer dem Chromosom 22 auch das Y-Chromosom verlorengegangen war. Bei 4 dieser Tumoren konnte eine Fluorescenzfärbung durchgeführt werden, wobei das Fehlen einer Y-Fluorescenz in Interphasezellen und Metaphaseplatten nachweisbar war.Diese Befunde werden im Zusammenhang mit dem Geschlechtschromosomenverlust bei anderen menschlichen Tumoren und im hohen Lebensalter diskutiert.

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Supported by the Deutsche Forschungsgemeinschaft (SFB 51 E 12).

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Parts of this work are included in the doctoral thesis (M.D.) of H.S. at the University of Munich, Germany.     

Esterase-D polymorphism in Assam by cellulose acetate electrophoresis

Summary With the help of a simplifed and quick method, cellulose acetate electrophoresis, the phenotypes of esterase D were determined in an Assamese population. The gene frequencies of Es D¹ were 0.7263 and 0.2737 for Es D².

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Zusammenfassung In einer Stichprobe aus Assam wurde mit Hilfe einer einfachen und schnellen Methode, der Cellulose-Acetat-Elektrophorese, die Bestimmung der Esterase D-Phänotypen durchgeführt. Die Genfrequenzen wurden für Es D¹ zu 0,.7263 und für Es D² zu 0.2737 bestimmt.

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Supported by the Deutsche Forschungsgemeinschaft, the Stiftung VW and the Fonds der Chemischen Industries.     

Flowering requirements of Scandinavian Festuca pratensis

Flowering requirements of three Scandinavian cultivars of Festuca pratensis Huds, have been studied in controlled environments. At 3 and 6°C, primary induction was independent of photoperiod, while short days (8 h) were more effective than long days (24 h) at higher temperatures. The critical temperature for induction was about 15°C in short days and about 12°C in long days. Saturation of induction required 18–20 weeks of exposure to optimal conditions. At temperatures below 12°C both induction and initiation of inflorescence primordia took place in long days, while a transition to long days was required for inflorescence initiation after primary induction in short days. A minimum of 8 long-day cycles were required for flowering of plants primary induced in short days and saturation of flowering required more than 16 cycles. The critical photoperiod for secondary induction was about 13 h. High temperature (21°C) had some devernalization effect in primary induced plants, suppressing flowering compared with 15°C.     

Growth forms and life-history strategies predict the occurrence of aquatic macrophytes in relation to environmental factors in a shallow peat lake complex

Hydrobiologia - Aquatic ecosystems provide vital services, and macrophytes play a critical role in their functioning. Conceptual models indicate that in shallow lakes, plants with different growth...     

Facultative mutualisms: A double‐edged sword for foundation species in the face of anthropogenic global change

Ecosystems worldwide depend on habitat‐forming foundation species that often facilitate themselves with increasing density and patch size, while also engaging in facultative mutualisms. Anthropogenic global change (e.g., climate change, eutrophication, overharvest, land‐use change), however, is causing rapid declines of foundation species‐structured ecosystems, often typified by sudden collapse. Although disruption of obligate mutualisms involving foundation species is known to precipitate collapse (e.g., coral bleaching), how facultative mutualisms (i.e., context‐dependent, nonbinding reciprocal interactions) affect ecosystem resilience is uncertain. Here, we synthesize recent advancements and combine these with model analyses supported by real‐world examples, to propose that facultative mutualisms may pose a double‐edged sword for foundation species. We suggest that by amplifying self‐facilitative feedbacks by foundation species, facultative mutualisms can increase foundation species’ resistance to stress from anthropogenic impact. Simultaneously, however, mutualism dependency can generate or exacerbate bistability, implying a potential for sudden collapse when the mutualism's buffering capacity is exceeded, while recovery requires conditions to improve beyond the initial collapse point (hysteresis). Thus, our work emphasizes the importance of acknowledging facultative mutualisms for conservation and restoration of foundation species‐structured ecosystems, but highlights the potential risk of relying on mutualisms in the face of global change. We argue that significant caveats remain regarding the determination of these feedbacks, and suggest empirical manipulation across stress gradients as a way forward to identify related nonlinear responses.