Bcr encodes a GTPase-activating protein for p21rac

More than thirty small guanine nucleotide-binding proteins related to the ras-encoded oncoprotein, termed Ras or p21ras, are known. They regulate many fundamental processes in all eukaryotic cells, such as growth, vesicle traffic and cytoskeletal organization. GTPase-activating proteins (GAPs) accelerate the intrinsic rate of GTP hydrolysis of Ras-related proteins, leading to down-regulation of the active GTP-bound form. For p21ras, two GAP proteins are known, rasGAP and the neurofibromatosis (NF1) gene product. There is evidence that rasGAP may also be a target protein for regulation by Ras and be involved in downstream signalling. We have purified a GAP protein for p21rho, which is involved in the regulation of the actin cytoskeleton. Partial sequencing of rhoGAP reveals significant homology with the product of the bcr (breakpoint cluster region) gene, the translocation breakpoint in Philadelphia chromosome-positive chronic myeloid leukaemias. We show here that the carboxy-terminal domains of the bcr-encoded protein (Bcr) and of a Bcr-related protein, n-chimaerin, are both GAP proteins for the Ras-related GTP-binding protein, p21rac. This result suggest that Bcr could be a target for regulation by Rac and has important new implications for the role of bcr translocations in leukaemia.     

(E,E)-10,12-Hexadecadienal: A component of the female sex pheromone of the spiny bollworm,Earias insulana (Boisd.) (Lepidoptera: Noctuidae)

Summary (E,E)-10,12-Hexadecadienal has been identified as a component of the sex pheromone of the female spiny bollworm moth,Earias insulana, by gas-chromatographic, electroantennographic and microchemical studies of abdominal tip extracts and entrained volatiles from female moths.This work was carried out under Ministry of Agriculture, Fisheries and Food licence HH 11599/139, issued under the Destructive Pests and Diseases of Plants Order 1965.     

X rays may be twice as potent as gamma rays for malignant transformation at low doses

The introduction in the 1950s of 60Co teletherapy units and megavoltage X-ray accelerators for radiotherapy prompted several studies which showed that the relative biological effectiveness (RBE) of orthovoltage X rays, compared with 60Co gamma rays, was approximately 1.1-1.2 (refs 1, 2). Subsequently, radiation therapists confirmed that the effect of established treatment protocols using orthovoltage X rays could be duplicated with the higher energy radiation by increasing the dose by approximately 10%, when radiation doses are of the order of tens of grays (or thousands of rads). The dependence of biological effectiveness on photon energy led to recommendations in which the quality factor, Q, which is an RBE for radiation protection purposes, was set at unity for X and gamma rays as well as for electrons or other directly ionizing particles having a linear energy transfer (LET) of less than 3.5 ke V microns-1. Over the past decade, however, several studies have shown differences in RBE between various low-LET radiations having LET values within the range designated for standard radiation. Underbrink et al. found an RBE for orthovoltage X rays relative to 60Co gamma rays of approximately 2 at 0.04 Gy, for induction of pink mutations in the stamen hairs of Tradescantia. Schmidt et al. scored chromosome aberrations in human lymphocytes, and at 0.25 Gy found the RBE of 200-k Vp X rays relative to 3-MeV electrons to be also approximately 2. Here we have compared 60Co gamma rays and orthovoltage X rays over the dose range 0.03-1.5 Gy using malignant transformation in mammalian cells in vitro as an end point. Our findings indicate that whereas the transformation incidence seems similar for X and gamma rays at high doses, the malignant potential of X rays is about twice that of gamma rays at 0.03 Gy.     

Regional brain [Met]-enkephalin in alcohol-preferring and non-alcohol-preferring inbred strains of mice

Scrutiny of the data from these studies reveals that the C58/J alcohol-preferring mice have significantly lower baseline methionine-enkephalin levels in both the corpus striatum and hypothalamus compared to C3H/CHRGL/2 non-alcohol-preferring mice. In other brain regions in these two strains, specifically, pituitary, amygdala, midbrain, and hippocampus, analysis of methionine-enkephalin levels did not show any significant differences. This suggests that the hypothalamus may indeed be a specific locus involved in the regulation of alcohol intake, via the molecular interaction between neuroamines, opioid peptides, as they are influenced by genetics and environment.     

Macromolecular hypertension: Hypertensive cardiovascular disease from subcutaneously administered polyvinyl alcohol

Zusammenfassung Nach subkutaner Injektion von Polyvinylalkohollösung entwickeln Ratten innerhalb eines Monats arteriellen Hochdruck. Gleichzeitig beobachtet man Vergrösserung von Leber, Milz, Herz und Nieren, sowie Thymusatrophie, jedoch keine Nebennierenvergrösserung. Es wird daher vermutet, dass diese Hypertonie, ähnlich der durch Methylcellulose hervorgerufenen, eine Folge von gestörter intraglomerulärer Durchblutung ist.

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This study was supported by grants H 2703 and H 4327 from the United States Public Health Service.