THE ACTION OF CORTICOTROPIN (ACTH) ON NUCLEIC ACIDS AND SUBCELLULAR ELEMENTS OF THE ADRENAL CORTEX

It was shown experimentally that ACTH causes an increase of cytoplasmic RNA and subcellular granules of the adrenal cortex shortly after administration. This effect was found to be concentrated primarily on the basophilic cytoplasmic granules and to be largely independent of cell division. The increase of nuclear RNA, DNA, and nuclear mass followed that of the cytoplasm. The observations indicate also that the mass increase of mitochondrial and chromidial systems is closely related to the increase in cytoplasmic, largely chromidial RNA.     

Evaluation of secondary nitroalkanes, their nitronates, primary nitroalkanes, nitrocarbinols, and other aliphatic nitro compounds in the Ames Salmonella assay.

The secondary nitroalkanes 2-nitropropane, 2-nitrobutane, 3-nitropentane and nitrocyclopentane, as well as their anionic forms (nitronates); the primary nitroalkanes 1-nitropropane, 1-nitrobutane, and 1-nitropentane and their respective nitronates; the nitrocarbinols 2-nitro-1-propanol, 2-nitro-1-butanol, 3-nitro-2-butanol, and 3-nitro-2-pentanol and their respective nitronates; 2-methyl-2-nitropropane, and 2-nitroso-2-nitropropane were tested in the Ames Salmonella assay using strains TA98, TA100 and TA102. Nitronates of the secondary nitroalkanes 2-nitropropane, 2-nitrobutane, 3-nitropentane, and nitrocyclopentane were significantly mutagenic in Salmonella strains TA100 and TA102 at 10-80 mumoles/plate, but the parent compounds were mutagenic at only a single dose level or were not mutagenic at all in the same dose range. The primary nitroalkanes and the nitrocarbinols were not mutagenic, or only marginally so, at the concentrations tested. The nitronates of the primary nitroalkanes and the nitrocarbinols reprotonated too rapidly under the conditions of the assay for adequate evaluation of mutagenicity. 2-Methyl-2-nitropropane was not mutagenic in strains TA100 and TA102; 2-nitroso-2-nitropropane was also not mutagenic in strains TA100 and TA102, but induced an equivocal mutagenic response in TA98. The positive Salmonella mutation data for the nitronates of the secondary nitroalkanes studied correlate very well with the very slow rate of reprotonation of secondary nitroalkane nitronates at pH 7.7 (Conaway et al. (1991) Cancer Res., 51, 3143), and provide further evidence that nitronates of secondary nitroalkanes, rather than the neutral parent forms with which they may be in equilibrium, are the more proximate mutagenic species.     

Two new myrmecophytic associations from the Malay Peninsula: Ants of the genusCladomyrma (Formicidae,Camponotinae) as partners ofSaraca thaipingensis (Caesalpiniaceae) andCrypteronia griffithii (Crypteroniaceae)

Summary In Peninsular Malaysia the treesSaraca thaipingensis (Caesalpiniaceae) andCrypteronia griffithii (Crypteroniaceae) are inhabited by ants. In the vicinity of Gombak, near Kuala Lumpur, the hollow internodes of youngSaraca thaipingensis plants are colonized mainly by twoCladomyrma species. In larger trees aCrematogaster sp. is also found.Crypteronia griffithii is inhabited by a third species ofCladomyrma. None of these species is conspecific with any of the threeCladomyrma taxa so far described. The colonies are founded by single mated queens, which have a conspicuous, sphecid wasp-like behaviour when searching for host plants and nest sites. They chew holes into the plant internodes and hollow them out to provide nest sites. Coccids and pseudococcids are cultivated within the internodes. The homopterans are not carried by queens on their nuptial flights. They apparently find their way by themselves into the cavities or are perhaps carried there by the worker ants. TheCladomyrma ants onCrypteronia are not aggressive, in contrast to those onSaraca thaipingensis.The relationship ofCrypteronia with ants seems to be obligatory, whereasSaraca was only partly colonized byCladomyrma. The interaction ofSaraca withCrematogaster sp. is loose and facultative, since theCrematogaster sp. also lives on other three species. Our studies have now revealed fourCladomyrma spp. which are regularly associated with plants. The genus therefore seems to have an entirely myrmecophytic way of life.     

Pseudomonas aeruginosa diaminopimelate decarboxylase: evolutionary relationship with other amino acid decarboxylases

The lysA gene encodes meso-diaminopimelate (DAP) decarboxylase (E.C.4.1.1.20), the last enzyme of the lysine biosynthetic pathway in bacteria. We have determined the nucleotide sequence of the lysA gene from Pseudomonas aeruginosa. Comparison of the deduced amino acid sequence of the lysA gene product revealed extensive similarity with the sequences of the functionally equivalent enzymes from Escherichia coli and Corynebacterium glutamicum. Even though both P. aeruginosa and E. coli are Gram-negative bacteria, sequence comparisons indicate a greater similarity between enzymes of P. aeruginosa and the Gram- positive bacterium C. glutamicum than between those of P. aeruginosa and E. coli enzymes. Comparison of DAP decarboxylase with protein sequences present in data bases revealed that bacterial DAP decarboxylases are homologous to mouse (Mus musculus) ornithine decarboxylase (E.C.4.1.1.17), the key enzyme in polyamine biosynthesis in mammals. On the other hand, no similarity was detected between DAP decarboxylases and other bacterial amino acid decarboxylases.