Methylation of tin by estuarine microorganisms

Mixed inoculums of microorganisms from Chesapeake Bay sediments transformed inorganic tin (SnCl(4) . 5H(2)O) to organotin compounds. Dimethyltin and trimethyltin species were identified as products by gas chromatography-mass spectrometry. Methylated tin species were not observed in sterile controls or in poisoned controls. Thus, estuarine microorganisms have the potential for transforming tin to toxic organotins and for mobilizing tin in the ecosystem.     

Spray aiming in bombardier beetles: jet deflection by the coanda effect

Bombardier beetles of the carabid subfamily Paussinae have a pair of flanges, diagnostic for the group, that project outward from the sides of the body. Behind each flange is a gland opening, from which the beetles discharge a hot, quinone-containing secretion when disturbed. The flanges are curved and grooved and serve as launching guides for anteriorly aimed ejections of secretion. Jets of fluid, on emergence from the gland openings, follow the curvature of the flanges and are thereby bent sharply in their trajectory and directed forward. The phenomenon is illustrative of the Coanda effect, widely applicable in engineering and responsible for the familiar tendency of liquids to curve around spouts and down the front of containers when being poured.     

Silicon-mediated organic synthesis

Organic chemists have used the chemical properties of tetracovalent silicon in a remarkable variety of new synthetic transformations. In carbon-functional silanes, exceptional stabilization is provided to a carbocation center in the beta position when the carbon-silicon bond lies in plane. This phenomenon directs electrophilic attack to the silicon-substituted carbon in aryl-, vinyl-, and alkynylsilanes and to carbon-3 in allylsilanes. For different reasons, silicon also stabilizes a carbon-metal bond in the alpha position. Consequently, access to many silicon-containing organometallics is readily available. The exceptional strength of silicon-oxygen and silicon-fluorine bonds is yet another factor that controls the chemical reactivity of silicon reagents. In recent developments, preparative chemists have taken advantage of these properties in imaginative and useful ways.     

Decay of female sexual behavior under parthenogenesis

A laboratory strain of Drosophila mercatorum has existed for 20 years without males and therefore without natural selection operating to maintain the genetic basis of female mating behavior. The females of this strain have recently experienced a genetic impairment of mating capacity. This observation exemplifies the mode of evolution of vestigial characters and supports Muller's theory that random mutation will tend to destroy the genetic basis of a character from which selection has been removed.     

Conservation and duplication of isozymes in plants

Many enzymes in plants have isozymes because the same catalytic reaction is often present in several subcellular compartments, most frequently the plastids and the cytosol. The number and subcellular locations of the isozymes appear to be highly conserved in plant evolution. However, gene duplication in diploid species and the addition of genomes in polyploid species have increased the number of isozymes.