The effect of sugar nutrition of in vitro pollinated placentae on seed set and dormancy inNicotiana tabacum L.

Summary The substitution of sucrose in the nutrient medium for in vitro pollinated placentae by glucose and fructose favours seed formation and considerably enhances the germination of seeds just attaining maturity. This effect of invert sugar was wholly suppressed in the mixture with two parts of sucrose.     

Ontogenesis of monoamine oxidase in the thyroid gland of rats

Summary During postnatal development, MAO activity in the thyroid gland of male rats increases until day 16, when adult values are reached.     

Specific stimulation of mycobacteria phagocytosis by substances liberated during the cultivation of lymph node cells from tuberculin hypersensitive rabbits with the specific antigen

Zusammenfassung Es wurde festgestellt, dass die Mediatoren der Überempfindlichkeit des verzögerten Types die Fähigkeit besitzen, die Phagocytose der Mykobakterien durch normale Makrophagen zu unterstützen. Die Wirkung hat sich als immunologisch spezifisch bewiesen.     

Demonstration of specific induction of erythrocytes phagocytosis by macrophages from normal,non-sensitized rabbits by a factor released from lymph node cells of immunized rabbits

Zusammenfassung Mit In-vitro-Experimenten wird gezeigt, dass in Anwesenheit von sensibilisierten Kaninchen-Lymphozyten Schaferythrozyten spezifisch an normale Kaninchen-Makrophagen adsorbieren und von diesen dann phagozytiert werden.     

An asteroid breakup 160 Myr ago as the probable source of the K/T impactor

The terrestrial and lunar cratering rate is often assumed to have been nearly constant over the past 3 Gyr. Different lines of evidence, however, suggest that the impact flux from kilometre-sized bodies increased by at least a factor of two over the long-term average during the past approximately 100 Myr. Here we argue that this apparent surge was triggered by the catastrophic disruption of the parent body of the asteroid Baptistina, which we infer was a approximately 170-km-diameter body (carbonaceous-chondrite-like) that broke up 160(-20)+30Myr ago in the inner main asteroid belt. Fragments produced by the collision were slowly delivered by dynamical processes to orbits where they could strike the terrestrial planets. We find that this asteroid shower is the most likely source (>90 per cent probability) of the Chicxulub impactor that produced the Cretaceous/Tertiary (K/T) mass extinction event 65 Myr ago.