Language,Reading, and Math Learning Profiles in an Epidemiological Sample of School Age Children

Dyscalculia, dyslexia, and specific language impairment (SLI) are relatively specific developmental learning disabilities in math, reading, and oral language, respectively, that occur in the context of average intellectual capacity and adequate environmental opportunities. Past research has been dominated by studies focused on single impairments despite the widespread recognition that overlapping and comorbid deficits are common. The present study took an epidemiological approach to study the learning profiles of a large school age sample in language, reading, and math. Both general learning profiles reflecting good or poor performance across measures and specific learning profiles involving either weak language, weak reading, weak math, or weak math and reading were observed. These latter four profiles characterized 70% of children with some evidence of a learning disability. Low scores in phonological short-term memory characterized clusters with a language-based weakness whereas low or variable phonological awareness was associated with the reading (but not language-based) weaknesses. The low math only group did not show these phonological deficits. These findings may suggest different etiologies for language-based deficits in language, reading, and math, reading-related impairments in reading and math, and isolated math disabilities.     

Diaminopimelic acid uptake by Bacillus megaterium: influence of growth conditions and other amino acids

Diaminopimelic acid (DAP) uptake was studied in Bacillus megaterium. The K _m and V _max were determined for bacteria grown with or without DAP. The uptake of DAP was shown to be constitutive and unaffected by the presence of other amino acids (including cystine). The concentration of DAP and lysine in the amino acid pool was examined and a procedure for pulse-labelling cell walls developed.     

The glycerol teichoic acid from walls of Staphylococcus epidermidis I2

1. Walls of Staphylococcus epidermidis I2 contain 30% (w/w) of a glycerol teichoic acid containing phosphate, d-alanine and d-glucose in the molecular proportions 1:0.25:0.50. 2. The teichoic acid was isolated by extraction with trichloroacetic acid and with dilute aqueous NN-dimethylhydrazine at pH7, and was shown to be a (1-->3)-linked poly(glycerol phosphate) containing beta-d-glucopyranosyl and d-alanyl ester substituents. 3. 2-O-beta-d-Glucopyranosylglycerol was isolated and characterized as its crystalline hexa-O-acetate. 4. Unlike that of certain other bacteria, the peptidoglycan component of the wall is not solubilized by NN-dimethylhydrazine. 5. The membrane teichoic acid is also a (1-->3)-linked poly(glycerol phosphate) but contains a smaller proportion of glucosyl substituents.