Novel developmental specificity in the nervous system of transgenic animals expressing growth hormone fusion genes

The development of methods for introducing foreign genes into the germ line of mice provides an approach for studying mechanisms underlying inducible and developmental gene regulation. Transgenic animals expressing foreign genes have thus been used to test models of the role played by specific DNA sequences in determining cell-specific expression. Results from these experiments suggest that tissue-specific expression is the consequence of a cis-acting regulatory sequence. However, these results do not exclude the possibility that cell-specific expression of some genes might be 'coded' by combinations of regulatory elements. We have previously described the production of transgenic mice from eggs microinjected with metallothionein-I/growth hormone (MGH) fusion genes, and now demonstrate that the juxtaposition of sequences from two different genes can be deciphered by cells to generate novel tissue specificities. Although expression of the endogenous metallothionein and growth hormone genes has not been detected in neuronal cells, transgenic mice clearly express an MGH fusion gene in a restricted subset of neurones. These results suggest a model in which tissue-specific patterns of expression of certain genes are determined by combinations of cis-acting regulatory sequences.     

Nutrient relationships between Orobanche fasciculata Nutt. and its host Artemisia pygmaea Gray in the Uinta Basin of Utah, USA

Patterns of mineral nutrient uptake and distribution within the roots, stems, and leaves of Artemisia pygmaea and in the vascular parasite Orobanche fasciculata were investigated. All nutrients studied were magnified over concentrations found in the soil into the host and parasite. Nitrogen, phosphorus, potassium, and zinc were magnified along the flow gradient of soil-roots-stems-leaves of the host. All others increased in the roots and then decreased in the stems and leaves. Orobanche fasciculata concentrated phosphorus, potassium, and sodium over soil and root concentrations while excluding to some degree all others.     

Essay Review: The Historicity of Sound and Hearing

This paper investigates the extent of overseas migration by British chemists over the period 1887–1971. Notwithstanding the ‘brain drain’ alarms of the 1960s, overseas employment was characteristic of some 19% of British chemists’ careers throughout our period, though its nature changed considerably. Our study examines the overseas employment histories of four cohorts of members of the [Royal] Institute of Chemistry in the ‘Chemists’ Database’ at the Open University. Those employed abroad were not only highly qualified but also both geographically mobile and occupationally versatile. Over the period, the pattern of chemists’ migration was broadly similar to that of British migration trends more generally. Except in the interwar years, chemists’ rate of migration was relatively constant. However, the length of time they spent abroad declined markedly over the period: long-term migration became less characteristic than short-term overseas employment for purposes of career development. From the late nineteenth century, British chemists staffed the Empire, but also found employment in the expanding US economy. After 1945, chemists’ destinations shifted more markedly towards North America, including Canada, and later also to Europe. Our work thus provides a new perspective on the dynamics of scientists’ migration and contributes to studies on the brain drain.     

Towards a resolution of the lek paradox

Genetic benefits in the shape of 'good genes' have been invoked to explain costly female choice in the absence of direct fitness benefits. Little genetic variance in fitness traits is expected, however, because directional selection tends to drive beneficial alleles to fixation. There seems to be little potential, therefore, for female choice to result in genetic benefits, giving rise to the 'lek paradox'. Nevertheless, evidence shows that genetic variance persists despite directional selection and genetic benefits of female choice are frequently reported. A theoretical solution to the lek paradox has been proposed on the basis of two assumptions: that traits are condition-dependent, and that condition shows high genetic variance. The observed genetic variability in sexual traits will be accounted for, because a proportion of the genetic variance in condition will be captured and expressed in the trait. Here we report results from experiments showing that male courtship rate in the dung beetle Onthophagus taurus is a condition-dependent trait that is preferred by females. More importantly, male condition has high genetic variance and is genetically correlated with courtship rate. Our results thereby represent a significant step towards a resolution of the lek paradox.     

Failure of actinomycin D to inhibit appearance of clotting activity by vitamin K in vitro

Zusammenfassung Lebergewebeschnitte mit Cumarin antikoagulentienvorbehandelter Ratten zeigen den Faktor VII im Medium nur beim Zusatz von Vitamin K. Die Vitamin-K-Wirkung wird bei gleichzeitigem Zusatz von Aktinomycin D nicht beeinflusst. Diese Beobachtung stimmt nicht überein mit der Hypothese, dass Vitamin K durch Beförderung der Auslösung der für die Synthese des Faktors VII spezifischen t-RNA eine Wirkung ausübt.