A possible influence of the spindle fibre on crossing-over in Drosophila

The distribution of genes in the second and third chromosomes of Drosophila melanogaster suggests that crossing-over may be influenced by the spindle fibre at least in neighboring regions. The disparity between the genetic and cytological maps of these chromosomes especially in the spindle fibre regions (Dobzhanzky 2,3) is consistent with such a view

Development of eye colors in Drosophila: some properties of the hormones concerned

The substance inducing the production of pigment in the eyes of vermilion brown mutants of Drosophila melanogaster has been shown to be a relatively stable chemical entity possessing true hormone-like activity. A simple method for obtaining hormone solutions has been developed involving extraction of dried wild type Drosophila pupae with ethyl alcohol and water. A logarithmic proportionality has been found to exist between the amount of hormone and the induced eye color. This relationship provides a simple method for the quantitative determination of hormone concentration in given extracts. Larvae and pupae of D. melanogaster contain an intracellular enzyme which inactivates the hormone in the presence of molecular oxygen. The hormone is not oxidized under ordinary conditions with either molecular oxygen or hydrogen peroxide. The hormone has been found to be an amphoteric compound with both acidic and basic groups and with a molecular weight between 400 and 600. The solubility and precipitation reactions of the hormone suggest its amino acid-like nature. However, the instability to heat, acid, and alkali, and its rather restricted occurrence indicate a rather complex specific structure

Development of Eye Colors in Drosophila: Extraction of the Diffusible Substances Concerned

The development of eye color in Drosophila is known to involve special diffusible substances [1,2]. A genetically vermilion (v) eye will develop wild-type eye color if it is supplied with v+ substance by transplantation or by injection of body fluid of wild type flies. Similarly a genetically cinnabar (cn) eye will develop the color characteristic of wild type if it is supplied with cn+ substance. The present paper summarizes preliminary experiments made to learn something of the nature of the two substances just mentioned. During the course of our studies, Ephrussi and Harnly [3] have shown that pupal fluid can be freed of living cells by freezing in liquid air without destroying the v+ and cn+ substances. Khouvine, Ephrussi and Harnly [4] have shown further that these substances can be extracted from Calliphora pupae with 95 per cent alcohol-ether mixtures and with 95 per cent alcohol but not with pure ether. They conclude that these substances are not proteins or enzymes, a conclusion confirmed by our work

A microbiological method for the determination of choline by use of a mutant of Neurospora

Previous communications from this laboratory have described the production of biochemical mutants in the mold Neurospora by means of ultraviolet and x-rays (1, 2). Such mutants are characterized by the inability to carry out specific chemical syntheses which normally occur in the unmutated, or wild type, strain. In each case which has been genetically analyzed the failure of the synthesis has been found to be related to the mutation of a single gene. The strain to be described, known as No. 34486, or cholineless, arose from a culture of wild type Neurospora crassa which had been irradiated with ultraviolet light. It was found to be unable to grow in a medium containing only salts, sugar, and biotin, but it grew normally on the addition of a mixture of water-soluble vitamins. When the components of the mixture were tested singly, it was found that the addition of choline alone permitted normal growth. Up to the present, no completely satisfactory method for the determination of choline in natural products and tissue extracts has been described. Chemical methods, such as precipitation of the reineckate, lack specificity, while the biological method of Fletcher, Best, and Solandt (3) is time-consuming and difficult, and “possesses many dangerous pitfalls for the chemist” (4). The whole subject has been critically reviewed by Best and Lucas (4). It was therefore of interest to determine whether the Neurospora mutant is a suitable test organism in a quantitative assay for choline. The experiments to be described show that this is the case and form the basis of a simple, sensitive, and specific method for the determination of choline in natural products. By this procedure it is possible to determine choline in a concentration of 0.02 mg. per liter; routine analyses can be run on 100 mg. samples of material

Comments on Bernard O. Dodge

Comments on Bernard O. Dodg

In search of organizational virtue in business: agents, goods, practices, institutions and environments

In this paper we argue that MacIntyre’s virtues-goods-practice-institution schema (MacIntyre 1985) provides a conceptual framework within which organizational virtue in general, and virtue in business in particular, can be explored. A heuristic device involving levels of individual agency, mode of institutionalization and environment is used to discuss why some businesses protect practices, develop virtues and encourage the exercise of moral agency in their decision making, while others struggle or fail to do so. In relation to conventional shareholder-owned capitalist business, both the mode of institutionalization and the environment are shown to be largely antithetical to the development of practices. Other businesses may meet the necessary internal conditions for the sustenance of practice-like features but remain dependent upon features within their environments. To illustrate this, we use participant observation to show how one particular organization—Traidcraft plc—meets the relevant conditions

Redefining Self‐Advocacy: A Practice Theory‐Based Approach

The disabled people's movements have successfully influenced public policies and laws. Self‐advocates who are autistic or have an intellectual disability have been working alongside other advocates for recent decades. Practice theory has rarely been used in disability research. This study explores “practice theory” through the analysis of interviews with advocates and self‐advocates within the autism and intellectual disability advocacy movements. This is a qualitative, empirical study based on interviews and focus groups with 43 participants in two countries. The data were collected in 2016–17. Content analysis was used to identify themes. Data indicate that everyday practices of self‐advocates and advocates such as parent advocates and professional advocates largely overlap. There are five major types of practices that are done by nearly all advocates: “informing and being informed,” “using media,” “supporting each other,” “speaking up,” and “bureaucratic duties.” Contrary to several previous studies on self‐advocacy that emphasized “speaking up” as the main activity in advocacy, this study found that most practices of advocates and self‐advocates are “para‐advocacy” practices that may or may not lead directly to “speaking up.” Practices of self‐advocates are often embedded in other everyday activities people do. The line between practices that belong to self‐advocacy and practices outside self‐advocacy may not always be clear even to self‐advocates. Findings also indicate that hierarchies in the disability movement influence strongly the position of self‐advocates