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<jats:p>General and specific cognitive abilities were studied in intact Swedish same-sex twin pairs 80 or more years old for whom neither twin had major cognitive, sensory, or motor impairment. Resemblance for 110 identical twin pairs significantly exceeded resemblance for 130 fraternal same-sex twin pairs for all abilities. Maximum-likelihood model-fitting estimates of heritability were 62 percent for general cognitive ability, 55 percent for verbal ability, 32 percent for spatial ability, 62 percent for speed of processing, and 52 percent for memory. There was also evidence for the significant influence of idiosyncratic experience as the environmental component that most determines individual differences in cognitive abilities late in life.</jats:p>

<jats:p> Self-incompatibility in <jats:italic>Brassica</jats:italic> refers to the rejection of self-related pollen and is mediated by a receptor protein kinase localized to the plasma membrane of the stigma epidermis in the flower. The recessive mutation <jats:italic>mod</jats:italic> eliminates self-incompatibility in the stigma. In <jats:italic>mod</jats:italic> mutants, self-compatibility was shown to be associated with the absence of transcripts encoded by an aquaporin-related gene. This observation suggests that a water channel is required for the self-incompatibility response of <jats:italic>Brassica</jats:italic> , which is consistent with the concept that regulation of water transfer from the stigma to pollen is a checkpoint in the early events of pollination in the crucifer family. </jats:p>

<jats:p> Aluminum when in soluble form, as found in acidic soils that comprise about 40 percent of the world’s arable land, is toxic to many crops. Organic acid excretion has been correlated with aluminum tolerance in higher plants. Overproduction of citrate was shown to result in aluminum tolerance in transgenic tobacco ( <jats:italic>Nicotiana tabacum)</jats:italic> and papaya ( <jats:italic>Carica papaya</jats:italic> ) plants. </jats:p>

<jats:p> Tetrachloroethene is a prominent groundwater pollutant that can be reductively dechlorinated by mixed anaerobic microbial populations to the nontoxic product ethene. Strain 195, a coccoid bacterium that dechlorinates tetrachloroethene to ethene, was isolated and characterized. Growth of strain 195 with H <jats:sub>2</jats:sub> and tetrachloroethene as the electron donor and acceptor pair required extracts from mixed microbial cultures. Growth of strain 195 was resistant to ampicillin and vancomycin; its cell wall did not react with a peptidoglycan-specific lectin and its ultrastructure resembled S-layers of Archaea. Analysis of the 16 <jats:italic>S</jats:italic> ribosomal DNA sequence of strain 195 indicated that it is a eubacterium without close affiliation to any known groups. </jats:p>

<jats:p>Apoptosis of Jurkat T cells induced the caspase-mediated proteolytic cleavage of p21-activated kinase 2 (PAK2). Cleavage occurred between the amino-terminal regulatory domain and the carboxyl-terminal catalytic domain, which generated a constitutively active PAK2 fragment. Stable Jurkat cell lines that expressed a dominant-negative PAK mutant were resistant to the Fas-induced formation of apoptotic bodies, but had an enhanced externalization of phosphatidylserine at the cell surface. Thus, proteolytic activation of PAK2 represents a guanosine triphosphatase–independent mechanism of PAK regulation that allows PAK2 to regulate morphological changes that are seen in apoptotic cells.</jats:p>