Huntington's disease: two families with differing clinical features show linkage to the G8 probe

To test the hypothesis that interfamily variability in Huntington's Disease (HD) is due to mutation at different loci, linkage analysis was undertaken in two large HD kindreds that differed in ethnicity, age-at-onset, and neurologic and psychiatric features. Both families showed linkage of the HD locus to the G8 probe. Several recombinants were documented in each family, and the best estimate of the recombination fraction for the two families was 6 percent with a 95 percent confidence interval of 0 to 12 percent. Although the data support the existence of a single HD locus, use of the G8 probe for presymptomatic testing in these kindreds would have resulted in a 12 percent error rate in genotype assignment at the HD locus.     

Multimodal signals: enhancement and constraint of song motor patterns by visual display

Many birds perform visual signals during their learned songs, but little is known about the interrelationship between visual and vocal displays. We show here that male brown-headed cowbirds (Molothrus ater) synchronize the most elaborate wing movements of their display with atypically long silent periods in their song, potentially avoiding adverse biomechanical effects on sound production. Furthermore, expiratory effort for song is significantly reduced when cowbirds perform their wing display. These results show a close integration between vocal and visual displays and suggest that constraints and synergistic interactions between the motor patterns of multimodal signals influence the evolution of birdsong.     

Temperaturansprüche mikroskopischer Bodenpilze aus klimatisch und geographisch verschiedenen Standorten

Temperature demands of microscopic soil fungi from different climatic and geographical sites. . 154 strains of microscopic soil fungi were isolated at 25°C from soils deriving from tropical to alpine climatic zones of the world (SW-Africa, Argentine, Nepal, Canary Islands and W-Germany). Determining their saccharolytic, amylolytic and proteolytic activities on saccharose-, starch- or gelatine-containing agar plates at 5 °C, 15 °C, 25 °C, 35 °C and 43 °C, the activity range as well as the optimal temperature were obtained. The following results were obtained: 1) A clear correlation between the temperature requirements of the fungal flora and the climatic conditions of the site of isolation was observed. 2) The fungal flora of a certain climatic zone was composed of strains of ubiquitously distributed species. Their great adaptability enables them to accomodate themselves to the temperature conditions of each site. 3) A smaller percentage of species was characterised by a small range of temperature variability and therefore depending on a certain climatic zone. Some of these were strict pschychrophilic species, characteristic for alpine and subalpine regions, but others behaved as strict mesophiles observed only in warm regions. 4) Finally from each site of isolation there also could be isolated a certain amount of fungi, whose ecological demands did not or only for a very short time coincide with the bioclimatic conditions of the particular site. Generally, these isolates are able to form resistant spores enabling them to survive unfavourable climatic conditions. .     

Oxygen profiles and methane turnover in a flooded rice microcosm

Summary Dissolved O₂ was depleted within the top 3.5-mm surface layer of flooded rice soil microcosms without plants. In planted microcosms, however, O₂ was detectable down to at least 40 mm in depth. O₂ concentrations in the uppermost soil layers of microcosms with rice plants were higher in the light than in the dark, indicating O₂ production by photosynthesis. The CH₄ emission rates were nearly identical for illuminated and for darkened microcosms, demonstrating that the photosynthetically produced O₂ did not increase CH₄ oxidation in the rhizosphere. In contrast, CH₄ emission rates increased when the microcosms were incubated under an N₂ atmosphere, indicating that transport of O₂ from the atmosphere into the rhizosphere was important for CH₄ oxidation. CH₄ emission under air accounted for only 10%–20% of the cumulative CH₄ production determined in cores taken from the microcosms. Apparently, 80%–90% of the CH₄ produced was oxidized in the rhizosphere and thus was not emitted.