A protocol for the combined biochemical and serological identification of the Ames mutagen tester strains as Salmonella typhimurium

Previously published reports have noted biochemical reactions atypical of Salmonella among the Ames tester strains of Salmonella typhimurium, and an inability to assign the strains to a specific Salmonella O (heat-stable cell wall) antigen group. We studied the biochemistry and serology of strains TA97, 98, 100, 102, 104, 1535, 1537, and 1538 in an attempt to develop a protocol to correctly speciate the strains. Biochemical reactions of all eight strains using standard media supplemented with histidine and biotin were consistent with those of the genus Salmonella. Strains TA100, 104, and 1535 were assigned to Salmonella O groups using bacteria treated with hot ethanol (White schema). H (flagellar) antigen assignments were performed successfully with seven of the eight strains. Two H antigen assignments required the use of the Craigie tube test for selection of motile revertants. Combining our biochemical and serological results obtained by this protocol, we were able to correctly speciate TA100, 104, and 1535 as Salmonella typhimurium. Our results demonstrate that representatives of the tester strains can be correctly speciated provided that procedures are followed that allow for the unusual nutrient requirements, the deep rough cell wall mutation, and the variably deficient motility of these organisms.

Multimer resolution systems of ColE1 and ColK: localisation of the crossover site

We have identified and characterised a stability function encoded by the high copy plasmid ColK. The function is analogous to ColE1 cer and maximises stability by maintaining plasmids in the monomeric state. In vivo recombination between cer and ckr (which share more than 90% homology at the DNA sequence level) produced a functional hybrid. Sequence analysis of hybrids indicates that recombination involving cer and ckr is site-specific and occurs within a 35 bp region of DNA which contains palindromic symmetry.

Gender roles as developmental pathways

Male and female gender roles are discussed as developmental pathways in terms of four related descriptive dimensions: the first three, rigidity, complexity and consistency, are all concerned with processes operating at particular stages of development; the fourth, continuity, is concerned with the overall developmental pathway. The limited evidence available indicates the following: there is a more rigid male role in childhood, but the evidence for adults is less clear; there is some evidence of greater complexity and inconsistency in the male role during childhood; developmentally, the female role becomes less flexible at adolescence whereas the male role becomes more flexible and varied; the female role shows more change across the adult life-span, particularly at the birth of the first child. The wider societal and historical implications of these conclusions, and their relation to role-related difficulties, are discussed.

The long-term effect of lithium carbonate on tardive dyskinesia

Lithium carbonate has been used in the treatment of tardive dyskinesia (TD) with conflicting results. In this study, six patients with a diagnosis of manic depressive illness were followed in the Affective Disorders Clinic of Douglas Hospital for one year. None of the patients showed improvement of their TD in this study. Possible reasons for this lack of response are discussed.

Sex differences in the aggressive behaviour of schoolchildren

An observational study was carried out to investigate whether sex differences in aggression, found in pre-school children in free-play situations, would also be found at older ages in the classroom. Equal numbers of boys and girls, aged 6 and 11 years, were observed individually in their school classrooms for eight 5 min periods, carried out over several weeks. At 11 years of age, boys showed more physical aggression than girls, a finding which resulted from a few boys showing higher scores than the remaining boys and the girls; girls showed more verbal aggression. These sex differences were not found at 6 years of age. At both ages, there was a higher proportion of same-sex than opposite-sex encounters. These results are discussed in terms of the generality of sex differences in aggression, the possibility of a sex difference in the form of aggressive acts, and the sex of the recipient of aggression.

Hyperpigmentation of pernicious anemia in blacks. Report of three cases

We investigated three black women who had anemia and skin hyperpigmentation. They were found to have pernicious anemia (PA) and normal adrenal functions. To our knowledge, this is the first report of skin hyperpigmentation of PA in black patients. This report reemphasizes the similarities in clinical features of PA and Addison's disease.

Testosterone and persistence in mice

In view of previous studies showing that testosterone increases persistence of food searching in chicks, a single factorially-designed experiment was carried out to investigate whether a similar phenomenon occurs in male mice. Using a runway test, it was found that testosterone, injected into castrated mice, did increase persistence. It was also shown that intact males resembled more the testosterone-injected than control-injected castrates, and that females resembled neither intact males nor either group of castrates. A larger number of training trials was found to affect feeding latencies in a similar way to testosterone. Comparison of two strains differing in emotional reactivity (BALB/c and Porton) showed differences consistent with their reactivity levels.

Sex differences in the emotional behaviour of laboratory mice

Three laboratory strains of mice (C57, BALB/c, Porton) were tested in an open field using a number of measures taken during the initial 2 min of testing and after a loud bell had sounded. The mice were tested either in a clean field or in one containing an odour of a same-sex conspecific. Over all three strains, several measures indicated that females showed high leveles of 'emotional' or 'fear' responses than did males. This sex difference was found in C57 and BALB/c strains but not in the Portons; it could not be attributed to activity or response-specific sex differences. Conspecific odours did not influence the direction of the main findings.

The effect of high and low doses of cycloheximide on nucleolar ribonucleic acid synthesis

In resting rat liver a dose of cycloheximide (1 mg. per kg.) inhibits leucine incorporation by 80 per cent whereas doses above 15 mg. per kg. inhibit it more than 90 per cent, when tested at 90 minutes following intraperitoneal injection. Initial stimulation of incorporation of orotate into total cellular, nuclear, and nucleolar fractions was seen at all doses tested. After 3 hours, however, marked suppression of incorporation particularly into nucleolar RNA was seen at 5 mg. per kg. and above while 1 mg. per kg. continued to stimulate. At 5 hours there was continued marked inhibition of RNA synthesis by 30 mg. per kg. and slight depression of RNA synthesis even by 1 mg. per kg. Preliminary ultrastructural studies failed to show objective nucleolar alterations even after 5 hours of cycloheximide treatment at a dose of 30 mg. per kg. No direct effect of several concentrations of cycloheximide on RNA synthesis was seen in an in vitro nucleolar system.

Open-field behaviour of oestrous and dioestrous rats: evidence against an 'emotionality' interpretation

Oestrous and dioestrous rats were observed during the initial 2 min of open-field exposure, and after a loud bell had sounded. Although defecation and ambulation showed characteristic difference between the two phases (less defecation and more ambulation at oestrus), other measures associated with emotional behaviour (latency to move from the wall, flight, and freezing to the bell) showed no differences. These findings supported Drewett's suggestion that open-field defecation and ambulation change with oestrous phase because of general metabolic changes and not as a result of 'emotionality' changes.

An electromagnetic catheter flow meter for determination of blood flow in major arteries

Images