No abstract

Genetic studies have previously demonstrated that the RED1 gene of Saccharomyces cerevisiae is required for chromosome segregation at the first meiotic division. Northern blot hybridization analysis indicates that the RED1 gene produces two transcripts of 2.75 and 3.2 kilobases. The major 2.75 kb transcript is not present in mitotic cells and is meiotically induced to accumulate maximally just prior to the meiosis I division. The DNA sequence of the RED1 gene was determined and used to predict the amino acid sequence of the encoded gene product. The RED1 protein is 827 amino acids in length and has a molecular weight of 95.5 kilodaltons. There is no significant homology between the RED1 amino acid sequence and other known protein sequences, including those encoded by genes essential for meiosis.

Horizontal standard lamps calibrate the spectral irradiance responsivity of spectroradiometers that measure solar ultraviolet irradiance. A field calibration unit and power supply developed to meet the requirements for using these standards in the field are described and their operation and associated uncertainties are detailed. Results from assessments obtained at two field instrument intercomparisons indicate that the horizontal standard, field calibration unit, and power supply operate within the design tolerances, making them suitable for performing routine calibrations in the field on most ultraviolet spectroradiometers.

A log-linear analysis has been applied to the survival probabilities of the genes of the founders of Tristan da Cunha. This analysis enables a large set of probabilities to be viewed as a single function, and the features of this function to be analysed. Features of the structure of the ancestral genealogy are thereby illuminated, and the dependence and interactions between founders with regard to the descent of their genes to the current population may be quantified.

Methods for inferring the mode of inheritance of a trait from familial data are becoming widely used. It is therefore important to assess alternative procedures for the collection of the relevant data. Cannings and Thompson (1977, Clinical Genetics 12, 208-212) and Thompson and Cannings (1979. In Genetic Analysis of Common Diseases, 363-382, New York: Liss) have advocated sequential schemes on the grounds that these admit simple methods for the correction of the likelihood function for ascertainment bias. Here it is shown that sequential procedures may also greatly increase efficiency, as measured by (statistical) information gained per individual sampled. Although attention is restricted to sampling sibships, and to a simple genetic model, the measures introduced are more widely applicable. A practical procedure for the construction of schemes, via a relationship between expected log likelihood and entropy, is also presented. This too is more widely applicable. A numerical example demonstrates the gains which can be achieved in practice, relative to alternative hypotheses which have been considered in several medical-genetic studies.