Light reversal of a morphine-induced analgesia susceptibility rhythm in mice

Zusammenfassung Durch Tag-Nacht-Umkehr konnte bei Mäusen eine entsprechende Phasenverschiebung beim Muster der Sensibilität für die schmerzstillende Wirkung des Morphins erzielt werden.     

Temperature acclimatization and protein synthesis in the goldfish mucosa

Resumen La síntesis de proteinas en la mucosa del pez dorado aclimatado a 8 °C, aumenta inmediatamente cuando la temperatura del baño aumenta a 25 °C. Un nuevo aumento en la sintesis de proteinas se observa después de 10 h. Estc ùltimo aumento es inhibido por actinomicinan. La reorganizatión en la síntesis de proteinas parece completarse dentro de las 30 h siguientes al aumento de temperatura. A pesar de que se observan variaciones grandes en diferentes peces la evidencia sugiere que al menos parte del fenómeno de aclimatación en la mucosa del pez dorado está relacionado con la síntesis del RNA mensajero.     

Genetic similarity and quality interact in mate choice decisions by female mice

Females express mate preferences for genetically dissimilar males, especially with respect to the major histocompatibility complex, MHC, and for males whose sexually selected signals indicate high genetic quality. The balance of selection pressure on each trait will depend on how females weight these desirable qualities under different conditions, but this has not been tested empirically. Here we show in mice that although MHC dissimilarity and a 'good genes' indicator (investment in scent-marking) both have a role in determining female preference, their relative influence can vary depending on the degree of variability in each trait among available males. Such interactions between condition-dependent and disassortative mate choice criteria suggest a mechanism by which female choice can contribute to maintenance of additive genetic variance in both the MHC and condition-dependent traits, even under consistent directional selection.     

A collimated, high-speed outflow from the dying star V Hydrae

Stars with masses in the range 1-8 solar masses (M(\circ)) live ordinary lives for approximately 10(9)-10(10) years, but die extraordinary deaths. First, during their death throes as asymptotic giant branch (AGB) stars they eject, over 10(4)-10(5) years, half or more of their mass in slowly expanding, spherical winds, and then, in a short (a few 100-1,000 years) and poorly understood phase, they are transformed into aspherical planetary nebula. Recent studies support the idea that high-speed, jet-like flows play a crucial role in this transformation. Evidence for such outflows is indirect, however; this phase is so short that few nearby stars are likely to be caught in the act. Here we report the discovery of a newly launched, high-speed jet-like outflow in the nearby AGB star, V Hydrae. We have detected both proper motions and ongoing evolution in the jet. These results support a model in which the jet is driven by an accretion disk around an unseen, compact companion. We also find a central, dense equatorial disk-like structure which may enable and/or enhance the formation of the accretion disk.     

SAR11 clade dominates ocean surface bacterioplankton communities

The most abundant class of bacterial ribosomal RNA genes detected in seawater DNA by gene cloning belongs to SAR11-an alpha-proteobacterial clade. Other than indications of their prevalence in seawater, little is known about these organisms. Here we report quantitative measurements of the cellular abundance of the SAR11 clade in northwestern Sargasso Sea waters to 3,000 m and in Oregon coastal surface waters. On average, the SAR11 clade accounts for a third of the cells present in surface waters and nearly a fifth of the cells present in the mesopelagic zone. In some regions, members of the SAR11 clade represent as much as 50% of the total surface microbial community and 25% of the subeuphotic microbial community. By extrapolation, we estimate that globally there are 2.4 x 10(28) SAR11 cells in the oceans, half of which are located in the euphotic zone. Although the biogeochemical role of the SAR11 clade remains uncertain, these data support the conclusion that this microbial group is among the most successful organisms on Earth.