Benign familial neonatal convulsions linked to genetic markers on chromosome 20

Recurrent seizures, commonly known as epilepsies, occur in 1.7% of the general population by age 40. The factors that initiate or underlie seizures are not well understood, but trauma, infectious disease and genetics have been implicated. An understanding of the molecular basis of seizures would shed light on the basic mechanisms of neuronal homeostasis and allow new therapeutic strategies to be explored. Here, we report the mapping of an epilepsy gene to a specific chromosomal region, on the basis of cosegregation of two closely-linked DNA markers with a form of epilepsy known as benign familial neonatal convulsions (BFNC2, 12120 in ref. 3). The linked markers confirm the genetic basis and autosomal dominant inheritance of this trait, and localize the gene causing BFNC in this family to the long arm of chromosome 20. This regional placement is the first step towards the isolation of a gene involved in neuronal activity in the human brain.     

Epidemiological parameters of HIV transmission

Epidemiological data on the main determinants of the transmission potential of HIV-1 in specific at risk groups in slowly accumulating, but many uncertainties remain.     

Monosynaptic inhibition of thalamic neurons produced by stimulation of the substantia nigra

Summary Electrical stimulation to the substantia nigra (Pars reticulata) produced a monosynaptic inhibition of the neurons of the ventromedial necleus of the thalamus in anesthetized cats.     

A phage repressor-operator complex at 7 A resolution

The crystal structure of a complex between the DNA-binding domain of phage 434 repressor and a synthetic 434 operator shows that the protein, very similar in conformation to gamma repressor, binds to B-form DNA with the second alpha-helix of a helix-turn-helix motif lying in the major groove.     

Altered cytosol/membrane enzyme redistribution on interleukin-3 activation of protein kinase C

Interleukin-3 (IL-3) is a member of a family of growth and differentiation peptides, collectively referred to as colony-stimulating factors, which regulate haematopoiesis. IL-3 has been highly purified from medium conditioned by WEHI-3B cells, and recently the molecular cloning of complementary DNA for murine IL-3 has been reported. IL-3 seems to stimulate a wide range of colony-forming cells derived from murine bone marrow and has consequently been studied under a variety of names, including burst-promoting activity, mast cell growth factor, P-cell stimulating factor and multi-colony-stimulating factor. Here we present evidence that IL-3-receptor interaction stimulates the rapid and transient redistribution of protein kinase C (PK-C) from cytosol to plasma membrane in FDC-P1 cells. Phorbol myristate acetate (PMA) is shown to have a similar effect in these IL-3-dependent FDC-P1 cells. Our data suggest that IL-3 and phorbol esters share a common feature of transmembrane signalling crucial for growth and differentiation.     

Possible demographic consequences of AIDS in developing countries

Simple mathematical models of the transmission dynamics of HIV that incorporate demographic and epidemiological processes to assess the potential impact of AIDS on human population growth and structure in developing countries suggest that AIDS is capable of changing population growth rates from positive to negative values over timescales of a few decades. The disease is predicted to have little if any impact on the dependency ratio of a population, defined as the number of children below age 15 years and elderly people over 64 years, divided by the number of adults between 15 to 64 years.     

Activation of a transposable element in the germ line but not the soma of Caenorhabditis elegans

The genetic activity of transposable elements is tightly controlled in many species. Transposons that are relatively quiescent under certain circumstances can excise or transpose at greatly increased rates under other circumstances. For example, 'genomic shock' can activate quiescent maize transposons, 'cytotype' and tissue-specific splicing regulate Drosophila P factors, copy number controls Tn5 transposition in bacteria, and developmental timing affects the production of transposon-like intracisternal A-particles in mouse embryos. The Caenorhabditis elegans transposable element Tc1 is subject to both strain-specific and tissue-specific control. Multiple copies of Tc1 are present in the genome of all C. elegans strains collected from nature. However, these elements are genetically active in only certain isolates. For example, in C. elegans variety Bristol transposition and excision of Tc1 are undetectable, but in variety Bergerac transposition and excision are frequent. Moreover, in variety Bergerac, Tc1 is about 1,000-fold more active in somatic cells than in germ cells. We have investigated the genetic basis for the germ/soma regulation of Tc1 activity. We have isolated mutants that exhibit increased frequencies of Tc1 excision in the germ line. The frequencies of Tc1 excision in the soma are unaltered in these mutants. These mutants also exhibit high frequencies of Tc1 germ-line transposition, and this results in a mutator phenotype. Nearly all mutator-induced mutations are caused by insertion of Tc1.