SUMMARY The relations between the quantity of red eye pigment and related pteridine compounds of Drosophila melanogaster have been studied in a variety of genotypes, which include strains selected for high or low pigment content, various derivatives of these lines and also lines in which one or other of the major autosome pairs were represented by homozygous chromosome pairs, derived by random sampling from the base population and also inbred lines. The quantity of red pigment was defined by the optical density when whole heads were extracted in a suitable solvent, while the pteridines were separated by chromatography and their amounts estimated by means of their characteristic fluorescence. The evidence from selection, inbreeding and chromosome sampling from the base population demonstrated the presence of substantial genetic variation for pigment content and amounts of related pteridines. The genetic and biochemical properties of the selected lines differed according to the direction of selection. High lines remained heterozygous after many generations of selection and displayed dominance and epistasis in favour of higher pigment content in crosses to the unselected stock. Selection for low pigment content led to fixation of recessive effects, attributable to particular chromosomes. The dominance-recessive relationship in red pigment differences was also applicable to the associated pteridines. The metabolic pattern in all lines with reduced pigment content is compatible with the assumption of reduced enzyme activity at particular steps of the pathway leading to the drosopterins (red eye pigments). The two steps accessible to study are subject to genetic variation in the base population, while inbreeding or selection for low pigment content leads to genetically fixed alterations at one or other of these steps. The genetic analysis was consistent with the biochemical evidence. Increase in pigment content above the normal level, either by selection or chance fixation, is accompanied by correlated increase in all the precursors. Several alternatives are possible but it is suggested that this may be due to an increase in early precursors, before the stages which have been altered in the low pigment lines. Attention is drawn to the similarity in genetic behaviour between pigment content and body size. Particular emphasis is laid on the value of selection as a means of creating biochemical differences which offer a basis for relating biochemical function and genetic behaviour.
The importance of atherosclerosis in public health has generated a vast literature relating to epidemiology of the disease, clinical descriptions of symptoms and records of variation of serum concentration of cholesterol, triglyceride or lipo-protein fractions in normal or affected persons. Such evidence has led to a number of hypotheses as to the origins of the disease, and although rival theories may be espoused with fervour or may fluctuate in popularity, a familial predisposition to coronary disease is a recurring theme. In this brief review, which does not aim to be exhaustive and is not concerned with hypertension, we shall focus attention on the more important aspects and attempt to set the conflicting evidence in perspective.
The following is the record of a case of ruptured uterus which required 3 laparotomies and transfusion of 11 pints of blood in the course of 15 hours. Case ReportThe patient, a 4-gravida aged 24, was 40 weeks pregnant
A bacteriological survey of 101 patients with acute haematogenous osteomyelitis and of 45 patients with acute septic arthritis has been performed. In the osteomyelitis survey, the organism most frequently detected was Staphylococcus aureus (75% of cases). In 10% of cases streptococci were found. Staph. aureus was also the most frequently grown organism in cases of acute septic arthritis (48·5% of cases), but Haemophilus influenzae accounted for 34% of positive cultures. On the basis of the survey, a combination of methicillin or cloxacillin and penicillin is recommended for acute haematogenous osteomyelitis and methicillin or cloxacillin and ampicillin for acute septic arthritis. The best choice of antibiotics is vitally important since treatment has to commence before the results of culture are known. Repeated evaluation of trends In the pattern of organisms causing these diseases Is strongly recommended.
Genetic Manipulation in Crops: Proceedings of the International Symposium held in Beijing, October 1984. Natural Resources and the Environment Series Volume 22. London: Cassell. 1988. 446 pages, £25.00 ISBN 1 85148 022 6 - Volume 53 Issue 1