Three loci related to the src oncogene and tyrosine-specific protein kinase activity in Drosophila

Rous sarcoma virus (RSV) is an acutely oncogenic avian retrovirus which induces sarcomas in animals and transforms fibroblasts in cell culture. Genetic analysis indicates that the viral src gene (v-src) mediates neoplastic transformation. The product of v-src is a 60,000 molecular weight (MW) phosphoprotein (pp60v-src) possessing the enzymatic activity of a tyrosine-specific protein kinase. The viral src gene is derived from a cellular gene (c-src) which also encodes a 60,000 MW phosphoprotein (pp60c-src) with tyrosine-specific protein kinase activity. Both birds and mammals are known to possess c-src. Shilo and Weinberg have reported that the genome of the fruit fly, Drosophila melanogaster, contains nucleotide sequences that are homologous to v-src. We report here the molecular cloning and chromosomal mapping of three loci from the Drosophila genome that contain such sequences. We also show that Drosophila contain both phosphotyrosine and a tyrosine-specific protein kinase activity immunoprecipitated by antisera directed against pp60v-src. It should now be possible to identify the precise locus that encodes a src-specific protein kinase in Drosophila, and to explore the role of c-src in the growth and development of D. melanogaster.     

Deficiency of Mbd2 suppresses intestinal tumorigenesis

Gene silencing through de novo methylation of CpG island promoters contributes to cancer. We find that Mbd2, which recruits co-repressor complexes to methylated DNA, is essential for efficient tumorigenesis in the mouse intestine. As Mbd2-deficient mice are viable and fertile, their resistance to intestinal cancer may be of therapeutic relevance.     

Localization to Xq27 of a susceptibility gene for testicular germ-cell tumours

Testicular germ-cell tumours (TGCT) affect 1 in 500 men and are the most common cancer in males aged 15-40 in Western European populations. The incidence of TGCT has risen dramatically over the last century. Known risk factors for TGCT include a history of undescended testis (UDT), testicular dysgenesis, infertility, previously diagnosed TGCT (ref. 7) and a family history of the disease. Brothers of men with TGCT have an 8-10-fold risk of developing TGCT (refs 8,9), whereas the relative risk to fathers and sons is fourfold (ref. 9). This familial relative risk is much higher than that for most other types of cancer. We have collected samples from 134 families with two or more cases of TGCT, 87 of which are affected sibpairs. A genome-wide linkage search yielded a heterogeneity lod (hlod) score of 2.01 on chromosome Xq27 using all families compatible with X inheritance. We obtained a hlod score of 4.7 from families with at least one bilateral case, corresponding to a genome-wide significance level of P=0.034. The proportion of families with UDT linked to this locus was 73% compared with 26% of families without UDT (P=0.03). Our results provide evidence for a TGCT susceptibility gene on chromosome Xq27 that may also predispose to UDT.     

A chemical switch for inhibitor-sensitive alleles of any protein kinase

Protein kinases have proved to be largely resistant to the design of highly specific inhibitors, even with the aid of combinatorial chemistry. The lack of these reagents has complicated efforts to assign specific signalling roles to individual kinases. Here we describe a chemical genetic strategy for sensitizing protein kinases to cell-permeable molecules that do not inhibit wild-type kinases. From two inhibitor scaffolds, we have identified potent and selective inhibitors for sensitized kinases from five distinct subfamilies. Tyrosine and serine/threonine kinases are equally amenable to this approach. We have analysed a budding yeast strain carrying an inhibitor-sensitive form of the cyclin-dependent kinase Cdc28 (CDK1) in place of the wild-type protein. Specific inhibition of Cdc28 in vivo caused a pre-mitotic cell-cycle arrest that is distinct from the G1 arrest typically observed in temperature-sensitive cdc28 mutants. The mutation that confers inhibitor-sensitivity is easily identifiable from primary sequence alignments. Thus, this approach can be used to systematically generate conditional alleles of protein kinases, allowing for rapid functional characterization of members of this important gene family.     

Deficiency or inhibition of oxygen sensor Phd1 induces hypoxia tolerance by reprogramming basal metabolism

HIF prolyl hydroxylases (PHD1-3) are oxygen sensors that regulate the stability of the hypoxia-inducible factors (HIFs) in an oxygen-dependent manner. Here, we show that loss of Phd1 lowers oxygen consumption in skeletal muscle by reprogramming glucose metabolism from oxidative to more anaerobic ATP production through activation of a Pparalpha pathway. This metabolic adaptation to oxygen conservation impairs oxidative muscle performance in healthy conditions, but it provides acute protection of myofibers against lethal ischemia. Hypoxia tolerance is not due to HIF-dependent angiogenesis, erythropoiesis or vasodilation, but rather to reduced generation of oxidative stress, which allows Phd1-deficient myofibers to preserve mitochondrial respiration. Hypoxia tolerance relies primarily on Hif-2alpha and was not observed in heterozygous Phd2-deficient or homozygous Phd3-deficient mice. Of medical importance, conditional knockdown of Phd1 also rapidly induces hypoxia tolerance. These findings delineate a new role of Phd1 in hypoxia tolerance and offer new treatment perspectives for disorders characterized by oxidative stress.     

Effects of Enzymatic Treatments with a Protease and a Total Crude Cellulase on the Handle and Prickle of a Viscose/Wool Blend Furnishing Fabric

Carefully controlled treatments with a protease and acellulase were used to improve the softness and reducethe subjectively perceived prickle of a coarse wool andviscose blend fabric. The activity towards wool of a non-specific endoprotease (Novolan L) was shown to bemuch greater in buffer containing a reducing agent (so-dium sulphite). The balance between protease and sodi-um sulphite concentrations was studied in order to reducethe amount of enzyme required.     

Cyclic nucleotide levels in the perfused rat heart subjected to hypoxia.

Isolated rat hearts were subjected to hypoxic perfusion on a recirculating Langendorff apparatus. Following a 30-min-period of aerobic stabilization the hearts were perfused for 30 min with media equilibrated with 84% N2, 12%O2 and 4% CO2. At the end of the hypoxic period myocardial concentrations of cyclic AMP and cyclic GMP were determined by radioimmunoassay. Exposure to hypoxia resulted in a significant increase in cyclic AMP (p less than 0.01) and a decrease in cyclic GMP (p less than 0.05) as compared to hearts perfused for 60 min with media gassed with 96% O2. 4% CO2.     

Whence chemistry?

Along with exploring some of the necessary conditions for the chemistry of our world given what we know about quantum mechanics, I will also discuss a different reductionist challenge than is usually considered in debates on the relationship of chemistry to physics. Contrary to popular belief, classical physics does not have a reductive relationship to quantum mechanics and some of the reasons why reduction fails between classical and quantum physics are the same as for why reduction fails between chemistry and quantum physics. However, a neoreductionist can accept that classical physics has some amount of autonomy from quantum mechanics, but still try to maintain that classical+quantum physics taken as a whole reduces chemistry to physics. I will explore some of the obstacles lying in the neoreductionist's path with respect to quantum chemistry and thereby hope to shed more light on the conditions necessary for the chemistry of our world.