Mutation induction by thymidine deprivation in Escherichia coli B/r. I. Influence of caffeine.

The addition of caffeine to the plating medium after thymine deprivation of E. coli WP2 uvr+ thyA or WP2 uvrA thyA had no influence on survival. Caffeine, however, reduced the frequency of mutants. The hypothesis is presented that the reduced mutagenesis is due to the sensitivity to caffeine of an inducible error-prone repair mechanism operating during thymine deprivation and after the re-addition of thymine.     

A method for the estimation of amino acid radioactivity in biological samples

A method for quantitative estimation of total radioactivity present in the free amino acid fraction of tissue samples has been described. Samples deproteinized with cold acetone were extracted, in acidic medium, with ethyl (peroxide free); after centrifugation, the aqueous phase was used for amino acid derivatization at 40°C for 15 h with 1-flouro-2,4-dinitrobenzene in bicarbonate-buffered medium. Aliquots of the derivatized samples were acidified and extracted twice again with ethyl ether. The combined organic phases were placed in glass scintilation vials, dried, and used for the determination of its radiactivity, corresponding to the radioactivity present in the free amino acid fraction of the sample. Deproteinized samples of rat blood plasma, as well as hen egg white and yolk were tested after addition of known quantities of ¹⁴C-labelled amino acids or glucose, for validation of the method. No glucose radioactivity was found in any of the extracted samples. All radioactivity added to the samples in the form of ¹⁴C-labelled alanine, glutamic acid, leucine and phenylalanine was quantitatively recovered in the derivatized fraction; only a fraction of arginine radioactivity was recovered.     

Banding patterns of the chromosomes ofCercopithecus neglectus: Comparison withMiopithecus talapoin andErythrocebus patas

The G, Q, and C bands and the location of the nucleolar organizing regions (NORs) of the chromosomes of two male Cercopithecus neglectusare described. The diploid number of the species is 2n =62. Comparison with the karyotypes of Miopithecus talapoin (2n =54), and Erythrocebus patas (2n =54)showed the presence of total banding homeology for only 10 chromosome pairs.     

Babysitting behavior by age/sex classification in squirrel monkeys (Saimiri sciureus)

The aunting behavior in a captive group of 22 squirrel monkeys containing three infants was done in terms of the age/sex classification of those animals involved. The time course of the aunting phenomena and the type and intensity of the interactions between the mothers and the aunts were recorded. Males as well as females were observed to ascertain if the babysitters were sex specific. Observations were gathered before, during, and after a particular threat to any monkey who was carrying an infant. Three categories of protective behavior (protect, retreat, and nothing) were tabulated. The results indicated that most aunting and protection occurred between infant ages 2-1/2-5 weeks when the infants were growing rapidly but not as yet socially self-sufficient. Mothers protected infants the most against juveniles, then subadult males, and least against other adult females. Subadult males were occasionally observed to carry and protect older infants. Aunting behavior was discussed in terms of the selective pressures by which it may have evolved.     

Reactions of 4β,5-epoxy-5β-androstan-3-ones with hydrogen fluoride in pyridine

4β,5-Epoxy-5β-androstane-3,17-dione ($\text{1a}$), 17β-hydroxy-4β,5-epoxy-5β-androstan-3-one ($\text{1b}$) and 17β-acetoxy-4β,5-epoxy-5β-androstan-3-one ($\text{1c}$) were treated with anhydrous hydrogen fluoride in pyridine (70% solution) at 55° and yielded the corresponding 4-en-4-ols e.g. 4-hydroxy-4-androstene-3, 17-dione ($\text{2a}$).As the reaction temperature was lowered each epoxide formed a second product which, at ?75°, was the major component of the reaction mixture and was identified as the 5α-fluoro-4α-ol derivative of the parent enone, e.g. 4α-hydroxy-5-fluoro-5α-androstane-3,17-dione ($\text{3a}$). These fluorohydrins are thermally unstable, losing hydrogen fluoride.The acetates of the fluorohydrins were also prepared, characterized, and shown to be more stable than the parent alcohols.     

The hairpencils of the flour moth Ephestia kuehniella

The hairpencils of the Mediterranean flour moth, Ephestia kuehniella Zeller, are tufts of modified scales between the seventh and eighth abdominal segments of the adult males. The fine structure and development of a hairpencil organule is described. A process of the trichogen cell secretes the modified scale and then withdraws, and the cell invaginates forming a microvillous lumen into which pheromone is probably secreted. This lumen communicates with the outside via rows of pores in the hollow scale. The opening of these pores when the moth emerges from the pupal cuticle may be a result of the drying out of the membrane that covered them. The socket of the hairpencil scale is secreted by a tormogen cell.
The hairpencils of male Lepidoptera differ in position from family to family, but the organules that compose them seem to share a common structure. Epidermal glands and organules are classified in a scheme that takes account of their mode of development.     

An unusual phenotypic expression of Hb-Leiden

After a boy of Mexican-American descent became jaundiced during treatment of a serious urinary tract infection with an oxidant drug, an extensive hematological examination was made. The important finding was the presence of Hb-Leiden to the extent of less than 3% or about a tenth of the usual percentage. Although inclusion bodies are present in the erythrocytes at all times, his hematological parameters have remained normal. The genetic basis for the unusually small amount of Hb-Leiden in the propositus may be due to the Hb-Leiden gene in an anti-Lepore configuration, that is, and Hb-Leiden gene in cis to the normal β and δ genes.     

Genetic and developmental evidence for a repressed genital primordium in Drosophila melanogaster

Agametic, a maternal-effect mutation, causes the absence of germ cells in approximately 40% of the gonads of flies derived from homozygous females. The nature of the deficiency in the eggs produced by these flies was examined. Ultrastructural abnormalities were seen in the polar granules of some eggs shortly after fertilization. Although a normal number of pole cells form, some are abnormal with degenerating polar granules and nuclear bodies and they contain myeloid bodies. The pole cells reach the gonads and at 14 hr of development all the gonads contain germ cells. However, in 40% of the gonads the germ cells become necrotic and disappear. Thus, the source of agametic gonads in the adult is embryonic death of pole cells in some gonads. To test whether this gonadal death is an autonomous deficiency of the mutant pole cells, mosaic pole cell populations were produced by reciprocal pole cell transplantation. In both types of transplants, the mutant pole cells died autonomously. In eight instances gonads containing only donor pole cells were obtained. Since mutant pole cells die when wild-type pole cells normally begin dividing, we suggest that the lesion affects the ability of these mutant pole cells to reenter the cell cycle.