The B.T.O. in the Seventies

Since the cessation of grazing and the reduction of Rabbit activity the chalk downland at the eastern end of the Chiltern Hills has been invaded by scrub, mainly hawthorn, which has attracted a uniquely diverse breeding bird community. Census studies show how different species are adapting to the various phases of the secondary succession towards woodland climax, and some broad lines of management are indicated.     

The Mechanism of the Gram Reaction. II. The Function of Iodine in the Gram Stain

Fifty-five reagents were studied as to their ability to replace iodine in the Gram stain. None gave results as good as iodine. Eight gave usable Gram preparations, and forty-seven gave negative results. Omission of the counterstain resulted in increasing to thirty-three the number of reagents giving differentiation, but this, was not considered a true Gram differentiation. Many oxidizing agents were shown not to be substitutes for iodine; therefore the function of iodine must be more than to serve as an oxidizing agent. Many reagents which formed precipitates with the dye could not replace iodine; therefore factors other than precipitate formation must be involved. However, all agents which were good substitutes for iodine were both good oxidizing and dye precipitating agents. Experiments involving the study of cell membrane permeability showed that Gram-positive cells were less permeable to iodine in alcoholic solution than Gram-negative cells. This difference could not be demonstrated for iodine in aqueous solution. It was concluded that iodine served to form a dye-iodine precipitate (or complex) in the cell. Since Gram-positive cells were less permeable to iodine in alcohol than Gram-negative cells, this resulted in a slower dissolving out of this complex from Gram-positive cells during de-colorization and hence a slower decolorization time. The relative solubilities of dye precipitates in alcohol and in aqueous safranin solution were also indicated as an important factor influencing decolorization. Dyes which formed highly soluble precipitates with iodine could not be used in the Gram stain. It is not proposed that the mechanism of the Gram stain is entirely one of membrane permeability; chemical factors are undoubtedly important and will be discussed in a later paper. However, it is proposed that the chemical and physical factors are closely interrelated in the Gram stain mechanism.     

The biogenesis of the anthocyanins. III. The role of sugars in anthocyanin formation

Anthocyanin formation in growing cultures of Spirodela is promoted by sucrose but not by glucose; conversely, growth is promoted by glucose but not by sucrose. Fructose is intermediate in both respects.In non-growing cultures, however, all three sugars are equally effective in promoting anthocyanin formation.A number of treatments which increase or decrease the anthocyanin content have parallel effects on the reducing sugar content. A plot of anthocyanin content against reducing sugar content shows a smooth relationship. Variations in the sucrose content are smaller and show no parallelism with pigmentation.It is deduced that anthocyanin may be formed independently from any of the three sugars, but that glucose is preferentially consumed for growth.Phosphate apparently does not participate in the formation of anthocyanin, and if the process does take place directly from sugars it probably does not proceed via the usual glycolytic pathway, since none of a number of glycolytic intermediates gives rise to any anthocyanin.There is some evidence for a participation of meso-inositol in the biogenesis of anthocyanin. The effects of quinic and shikimic acids appear too small for them to be considered as intermediates. Phosphate appears to be no more required with inositol than with the sugars.     

The genetics of esterases in Drosophila. VIII. The gene regulating the activity of JH-esterase in D. virilis

The content of JH-esterase was assayed by radial immunodiffusion in Drosophila virilis pupae under normal conditions and under the effects of extreme factors. It was found that JH-esterase content is the same (not different from the control) in pupae showing a high activity of the enzyme and in those not showing it. These data are evidence for a gene controlling JH-esterase activity. It was also shown that a regulatory factor converts inactive into active JH-esterase when homogenates of pupae, with active and inactive forms, were mixed and incubated together. It was demonstrated that the source of the activating factor is the larval brain. Sublines 147-R and 147-I were produced by introducing the second chromosome pair of stocks 103 and 101, which are heat resistant, into the genome of individuals of stock 147, which is heat sensitive. Sublines 160-III, 160-IV, 160-V, and 160-VI were produced by introducing the third, fourth, fifth, and sixth chromosome pairs of stock 147 into the genome of stock 160S, which is heat-resistant. The results of analysis of JH-esterase activity and the viability of individuals of these sublines at high temperatures indicated that the gene regulating the activity of JH-esterase is located in the sixth chromosome of D. virilis.     

Computers in the surgery. The patient's view.

A postal survey sent to 350 patients from two rural practices confirmed that an appreciable minority of patients (17%) were opposed to doctors using computers. The questionnaire distributed had been carefully designed to identify their opposition more specifically. Most of the general concern was accounted for by the 91 patients (31%) who feared that confidentiality of information would be reduced. The sensitive nature of medical information alerts patients to the possibility of diminished security of records and obliges practices considering acquiring a computer to ensure that these fears are not realised. Smaller proportions of patients were found to oppose computers on other grounds--namely, impersonality, economy, and general anxiety.