Isolation and characterization of the positive regulatory gene ADR1 from Saccharomyces cerevisiae.

The DNA segments containing the ADR1 gene and a mutant allele, ADR1-5c, have been isolated by complementation of function in Saccharomyces cerevisiae. The ADR1 gene is required for synthesis of the glucose-repressible alcohol dehydrogenase (ADHII) when S. cerevisiae cells are grown on a nonfermentable carbon source, whereas the ADR1-5c allele allows ADHII synthesis even during glucose repression. A plasmid pool consisting of yeast DNA fragments isolated from a strain carrying the ADR1-5c allele was used to transform a strain containing the adr1-1 allele, which prevents ADHII depression. Transformants were isolated which expressed ADHII during glucose repression. A plasmid isolated from one of these transformants was shown to carry the ADR1-5c allele by its ability to integrate at the chromosomal adr1-1 locus. The wild-type ADR1 gene was isolated by colony hybridization, using the cloned ADR1-5c gene as a probe. The ADR1-5c and ADR1 DNA segments were indistinguishable by restriction site mapping. A partial ADR1 phenotype could be conferred by a 1.9-kilobase region, but DNA outside of this region appeared to be necessary for normal activation of ADHII by the ADR1 gene.     

Varicose Veins,Deep Vein Thrombosis,and Haemorrhoids: Epidemiology and Suggested Aetiology

Current concepts on the aetiology of varicose veins, deep vein thrombosis, and haemorrhoids have been examined and, in the light of epidemiological evidence, found wanting.It is suggested that the fundamental cause of these disorders is faecal arrest which is the result of a low-residue diet.     

Further observations on the fine structure and development of the infracerebral complex (“infracerebral gland”) of Nereis limnicola (Annelida,Polychaeta)

Cell and Tissue Research - The infracerebral complex consists of: (a) two types of ependymoid infracerebral cells located on the ventral surface of the brain, adjacent to a coelomic sinus and blood...     

Nitrification and nitrate uptake: Leaching balance in a declined forest ecosystem in eastern France

Nitrate uptake and leaching were measured during one year in a declined fir forest on the Vosges highlands (eastern France), in order to investigate whether excess nitrification could be responsible for a deleterious acidification of the ecosystem. Nitrate uptake by the vegetation was active mainly from spring to early fall, and then reached about 66 kg N ha^-1. No significant leaching loss occurred during the growth period of the vegetation. Significant nitrate leaching occurred in winter (about 17 kg N ha^-1). During fall and winter the nitrification rate was of the same magnitude as values reported for other ecosystems, and, thus, was not considered to be abnormaly strong. No abnormal temporal discoupling of nitrate production and nitrate uptake occurred in the ecosystem, and forest decline must therefore have some other cause.     

Transgenic Analysis of a PotentialHoxd-11Limb Regulatory Element Present in Tetrapods and Fish

Genes of theHoxDcomplex related to theDrosophila Abd-Bgene are involved in the morphogenesis of vertebrate paired appendages.Hoxd-11,for instance, is necessary in combination with otherHoxgenes for the proper development of different parts of the tetrapod limbs. Sequence comparisons between the mouse, chicken, and zebrafishHoxd-11loci have revealed the conservation of several blocks of DNA sequence which may be of importance for the regulation ofHoxd-11expression. We have used transgenic mice to show that one of these conserved elements specifically drives expression in a proximal-posterior part of developing forelimbs. Production of mice transgenic for a full fishHoxd-11construct as well as for mouse–fishHoxd-11chimeric constructs shows that the fish counterpart of this sequence is able to elicit expression in mouse forelimbs as well, though in a slightly different domain. However, this fish element requires the presence of the mouse promoter and does not work in its own context. These results are discussed in light of both the control ofHoxdgene expression during limb development and the use of a comparative interspecies approach to understand the regulation of genes involved in vertebrate development.