Genetic Analysis of the γ-Aminobutyrate Utilization Pathway in Escherichia coli K-12

The control mutation that results in a concomitant severalfold increase in the activities of gamma-aminobutyrate-alpha-ketoglutarate transaminase (GSST, EC 2.6.1.19) and succinic semialdehyde dehydrogenase (SSDH, EC 1.2.1.16), leading to the acquisition of the ability to utilize gamma-aminobutyrate (GABA) as the sole source of nitrogen by Escherichia coli K-12 mutants, was mapped by mating and transduction with P1kc. The locus affected, gabC, is approximately 48% co-transduced with the thyA gene, located at min 55 of the E. coli K-12 chromosome. The structural gene of the first enzyme in the GABA pathway, GSST, was mapped by interrupted mating, using one of the GSST-less mutants, DB742, isolated in this work. The mutated locus, gabT, is situated at about min 73 of the E. coli chromosome, close to the gltC gene. Genetic evidence concerning the sensitivity of the enzymes of the GABA pathway to catabolite repression under different physiological conditions suggests that the two structural genes of the GABA regulon do not constitute one operon.     

Quirks of dye nomenclature. 10. Eosin Y and its close relatives

The long history of eosin Y, eosin B and the methyl and ethyl eosins is recounted as well as their synthesis, the variety of their molecular species and some of the myriad applications of these dyes. Chromatographic techniques are described that reveal the purity or lack of it in commercial samples. Toxicological studies are discussed that suggest that the eosins are virtually non toxic, but efforts to remove them from the environment imply that there may be some risk.     

Can hay harvesting detrimentally affect adult butterfly abundance?

Butterfly transects were carried out in the meadows and tracks of a 1.5 × 1.6 km study area in the Cantabrian section of the Picos de Europa, Spain to examine the impact of hay harvesting on adult butterfly numbers. Overall butterfly numbers significantly decreased between transect counts taken before and after harvesting in cut fields; no such decline was evident in fields without active management (harvesting/grazing) over the same period. Family-level analysis showed hay harvesting to significantly impact on the Satyridae but not other groups. In fields not undergoing active management no Family-level declines were evident, but the Lycaenidae significantly increased in abundance over the same period. Butterfly abundance on tracks surrounding the meadows significantly decreased during the hay harvest period, but this was not reflected in significant decreases in any particular Family group. The results are discussed in relation to the time of harvesting during the day, and socioeconomic changes in extensive pastoral landscapes.