Expression of ribosomal protein genes in Escherichia coli

Streptomycin or spectinomycin treatment of an E. coli strain, carrying the strR and spcR alleles on the chromosome and the wild-type (sensitive) alleles on the episome, selects for inactivation of the relevant sensitive allele. After Mu induced mutagenesis, in the absence of selection against extended deletions upon the episome, a large proportion of stro mutants are also spco, and vice versa. However, when markers flanking the strA and spcA gene cluster are simultaneously selected, effectively eliminating long deletions, the majority of stro mutants continue to express the spcs allele, and vice versa. Insofar as inactivation after Mu treatment is due to prophage insertion within or proximal to the genes in question, this result indicates that the genes strA and spcA are not parts of a single operon. In virtue of the high frequency of extended deletions observed in the absence of suitable counter-selection, we must place a word of caution upon the use of phage Mu-1 as a means of isolating polar mutations and defining transcriptional units.

[Pneumocystis carinii pneumonia after kidney transplantation. Early diagnosis by distal bronchial brushing]

Distal bronchial brushing is one of the methods used in the in vivo indentification of Pneumocystis carinii, a parasite associated with severe pneumonia, the development of which is induced by immuno-depression, particularly after renal transplantation. In three patients the pathogenic agent was demonstrated in alveolar material obtained in this way. The technique is simple and risk-free. It may be used early and repeatedly.

[Circulatory survival of irreversible comas]

On the basis of a series of 53 cases of irreversible coma maintained in circulatory survival with the aim of removing the kidneys, the authors discuss the mode of treatment, with particular reference to the intravenous fluids used and the use of medications influencing the circulation. Fluid and electrolytes given must be adjusted hourly to ensure the exact replacement of urinary losses. Isoprotenerol is the only medication usually necessary. In the event of circulatory insufficiency, which is difficult to foresee and hence prevent, immediate volume expansion in a short a time as possible and isoprotenerol most frequently correct the situation (14 out of 17 cases). Thus effective circulation may be maintained until the kidneys are removed (48 out of 53 cases). 92 p.cent of the grafted kidneys functioned from the first day onwards.

Colouring Matters of Australian Plants. XVIII. Constituents of Anigozanthos rufus

Four new phenylphenalenone pigments have been isolated from Anigozanthos rufus Labill. and their structures have been determined. The known compound 2-phenylnaphthalic anhydride was also isolated from the plant. The synthesis of one of the new pigments, and of some related compounds, is described.

Effects of protein and energy intakes on the wool growth of Merino wethers

The results of an experiment are presented which show that the supply of both protein and energy to the small intestine of adult sheep affects the rate of wool growth, and that the direction and magnitude of the response to energy absorption is dependent upon the particular level of protein given. Thirty fine-wool Merino wethers received their entire diets, which consisted of reconstituted spray-dried cow's milk, sodium caseinate, glucose, butterfat, and micronutrients, by direct abomasal infusion in an experiment consisting of two parts. In part I the effect of protein intake (20,40, 60, 80, or 100 g/day) at constant energy intake (5.02 MJ/day) was investigated, while in part II the effect of energy intake (3.01, 4.02, 5.02,7.53, or 10.04 MJ/day) at three levels of protein intake (20, 60, or 100 g/day) was studied. A nitrogen balance trial was conducted with selected animals during 7 days near the end of each part of the experiment. In part I, as the daily intake of protein was increased from 20 to 80 g, the wool growth rate increased almost linearly from 2.3 to 9.0 g/sheep/day. With a further rise in protein intake to 100 g/day the mean value fell to 8 .O g/sheep/day. The overall trend in wool growth with increasing protein intake was significantly quadratic. In part II, for sheep receiving 100 g protein/day, an increase in energy intake from 3.01 to 10.04 MJ/day caused a highly significant, linear rise in wool growth rate of 52 %. For animals receiving 60 g protein/day, wool growth rate tended to increase at first and then fell again as energy intake was raised from 3.01 to 10.04 MJ/day, but the differences were not significant. When sheep were given only 20 g protein/day, an increase in energy intake from 3.01 to 10.04 MJ/day resulted in a decline in wool growth rate of 45 %. The results suggest that there is an optimum ratio of protein to energy absorption required for maximum wool growth in sheep. If protein is limiting, an increase in protein absorption stimulates wool growth, but an increase in energy absorption reduces it. Conversely, if protein is in excess an increase in protein absorption reduces wool growth, but it is stimulated by an increase in energy absorption. The practical significance of the results is discussed.

Biosynthesis of N-(alpha-hydroxyethyl) lysergamide, a metabolite of Claviceps paspali Stevens and Hall

1. The biosynthetic origin of the amide substituent of N-(alpha-hydroxyethyl)lysergamide has been studied. 2. [1-(14)C]Acetate, [(14)C]formate, [2-(14)C]mevalonic acid lactone, [2-(14)C]indole, dl-[3-(14)C]tryptophan, dl-[3-(14)C]serine, dl-[2-(14)C]alanine and [2-(14)C]pyruvate were efficiently incorporated into the alkaloid, but not dl-[1-(14)C]alanine or [1-(14)C]pyruvate. 3. Only the dl-[2-(14)C]alanine- and [2-(14)C]pyruvate-derived alkaloid contained appreciable radioactivity in the amide substituent. 4. l-[(15)N]Alanine-derived alkaloid was shown to be specifically labelled in the amide nitrogen. However, l-[(14)C,(15)N]alanine was found to be incorporated into the methylcarbinolamide substituent with an appreciable increase in the (15)N/(14)C ratio, suggesting that alanine is not the direct precursor of this moiety.