The isolation and structure of 13,18-dehydroglaucarubinone,a new antineoplastic quassinoid fromSimarouba amara

Summary An investigation of the Guyana plantSimarouba amara Aubl. (Simaroubaceae) for antineoplastic quassinoids led to isolation and structural determination of the new quassinoids 2-acetylglaucarubine (1a) and 13,18-dehydroglaucarubinone (2). The previously known 2-acetylglaucarubinone (3a) and glaucarubinone (3b) were also obtained. The new quassinoid2 was found significantly to inhibit growth of the murine lymphocytic leukemia P388.Antineoplastic agents 59. For part 58 refer to M. T. Edgar, G.R. Pettit and T.H. Smith, J. org. Chem., in preparation.Acknowledgments. We wish to thank Mr B. Septe for providing the¹³C-NMR-data. Dr Jean H. Schmidt and Miss Linda M. Lange for assistance with biological studies.—G.R. Pettit is grateful to the National Cancer Institute (performed pursuant to contract No. N01-67048 with the Division of Cancer Treatment, NCI, National Institutes of Health, Dept. of Health, Education and Welfare), Public Health Services Research grant No. CA 16049-03 from the National Cancer Institute, the Fannie E. Rippel Foundation, Talley Industries, and the Phoenix Coca-Cola Bottling Co., for partial support of this investigation.     

The Lkb1 metabolic sensor maintains haematopoietic stem cell survival

Haematopoietic stem cells (HSCs) can convert between growth states that have marked differences in bioenergetic needs. Although often quiescent in adults, these cells become proliferative upon physiological demand. Balancing HSC energetics in response to nutrient availability and growth state is poorly understood, yet essential for the dynamism of the haematopoietic system. Here we show that the Lkb1 tumour suppressor is critical for the maintenance of energy homeostasis in haematopoietic cells. Lkb1 inactivation in adult mice causes loss of HSC quiescence followed by rapid depletion of all haematopoietic subpopulations. Lkb1-deficient bone marrow cells exhibit mitochondrial defects, alterations in lipid and nucleotide metabolism, and depletion of cellular ATP. The haematopoietic effects are largely independent of Lkb1 regulation of AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) signalling. Instead, these data define a central role for Lkb1 in restricting HSC entry into cell cycle and in broadly maintaining energy homeostasis in haematopoietic cells through a novel metabolic checkpoint.     

Calmodulin interacts with MLO protein to regulate defence against mildew in barley

In plants, defence against specific isolates of a pathogen can be triggered by the presence of a corresponding race-specific resistance gene, whereas resistance of a more broad-spectrum nature can result from recessive, presumably loss-of-regulatory-function, mutations. An example of the latter are mlo mutations in barley, which have been successful in agriculture for the control of powdery mildew fungus (Blumeria graminis f. sp. hordei; Bgh). MLO protein resides in the plasma membrane, has seven transmembrane domains, and is the prototype of a sequence-diversified family unique to plants, reminiscent of the seven-transmembrane receptors in fungi and animals. In animals, these are known as G-protein-coupled receptors and exist in three main families, lacking sequence similarity, that are thought to be an example of molecular convergence. MLO seems to function independently of heterotrimeric G proteins. We have identified a domain in MLO that mediates a Ca2+-dependent interaction with calmodulin in vitro. Loss of calmodulin binding halves the ability of MLO to negatively regulate defence against powdery mildew in vivo. We propose a sensor role for MLO in the modulation of defence reactions.     

The effects of nerve growth factor antiserum on ambystoma

Résumé Des injections d'un sérum spécifique contre le facteur de croissance nerveuse (anti-NGF) provoquent une réduction de la taille des ganglions rachidiens de la salamandreAmbystoma par suite de la réduction de la masse cellulaire du ganglion. Il y a aussi un plus grand nombre de «petites» cellules (d'un diamètre nucléaire de moins de 6,25 ) dans les ganglions des animaux utilisés.

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I should like to express my thanks to Dr.Isaac Schenkein for supplying the antiserum preparation, and to Mr.Edward Kalmar for technical assistance. This research was supported by a grant from the Rutgers University Research Council.     

The larval ring gland ofDrosophila melanogaster: A comparison of Ebony and Oregon strains by use of a qualitative protein stain

Résumé Le contenu protéique des cellules glandulaires circulaires des larves de 2 races deDrosophila melanogaster est examiné en détail. Les résultats de cette étude montrent que la production et l'activité hormonale de ces 2 races diffère.     

Identification of chicken lysozyme <Emphasis Type="Italic">g</Emphasis>2 and its expression in the intestine

Lysozyme is an important component of the innate immune system, protecting the gastrointestinal tract from infection. The aim of the present study was to determine if lysozyme is expressed in the chicken (Gallus gallus) intestine and to characterise the molecular forms expressed. Immunohistochemical staining localised lysozyme to epithelial cells of the villous epithelium along the length of the small intestine. There was no evidence for lysozyme expression in crypt epithelium and no evidence for Paneth cells. Immunoblots of chicken intestinal protein revealed three proteins: a 14-kDa band consistent with lysozyme c, and two additional bands of approximately 21 and 23 kDa, the latter consistent with lysozyme g. RT-PCR analyses confirmed that lysozyme c mRNA is expressed in 4-day, but not older chicken intestine and lysozyme g in 4- to 35-day chicken intestine. A novel chicken lysozyme g2 gene was identified by in silico analyses and mRNA for this lysozyme g2 was identified in the intestine from chickens of all ages. Chicken lysozyme g2 shows similarity with fish lysozyme g, including the absence of a signal peptide and cysteines involved in disulphide bond formation of the mammalian and bird lysozyme g proteins. Analyses using SecretomeP predict that chicken lysozyme g2 may be secreted by the non-classical secretory pathway. We conclude that lysozyme is expressed in the chicken small intestine by villous enterocytes. Lysozyme c, lysozyme g and g2 may fulfil complimentary roles in protecting the intestine.Received 4 August 2004; received after revision 1 September 2004; accepted 7 September 2004     

Fracture surface energy of the Punchbowl fault, San Andreas system

Fracture energy is a form of latent heat required to create an earthquake rupture surface and is related to parameters governing rupture propagation and processes of slip weakening. Fracture energy has been estimated from seismological and experimental rock deformation data, yet its magnitude, mechanisms of rupture surface formation and processes leading to slip weakening are not well defined. Here we quantify structural observations of the Punchbowl fault, a large-displacement exhumed fault in the San Andreas fault system, and show that the energy required to create the fracture surface area in the fault is about 300 times greater than seismological estimates would predict for a single large earthquake. If fracture energy is attributed entirely to the production of fracture surfaces, then all of the fracture surface area in the Punchbowl fault could have been produced by earthquake displacements totalling <1 km. But this would only account for a small fraction of the total energy budget, and therefore additional processes probably contributed to slip weakening during earthquake rupture.     

A splicing mutation affecting expression of ataxia-telangiectasia and Rad3-related protein (ATR) results in Seckel syndrome

Seckel syndrome (OMIM 210600) is an autosomal recessive disorder characterized by intrauterine growth retardation, dwarfism, microcephaly and mental retardation. Clinically, Seckel syndrome shares features in common with disorders involving impaired DNA-damage responses, such as Nijmegen breakage syndrome (OMIM 251260) and LIG4 syndrome (OMIM 606593). We previously mapped a locus associated with Seckel syndrome to chromosome 3q22.1-q24 in two consanguineous Pakistani families. Further marker analysis in the families, including a recently born unaffected child with a recombination in the critical region, narrowed the region to an interval of 5 Mbp between markers D3S1316 and D3S1557 (145.29 Mbp and 150.37 Mbp). The gene encoding ataxia-telangiectasia and Rad3-related protein (ATR) maps to this region. A fibroblast cell line derived from an affected individual displays a defective DNA damage response caused by impaired ATR function. We identified a synonymous mutation in affected individuals that alters ATR splicing. The mutation confers a phenotype including marked microcephaly (head circumference 12 s.d. below the mean) and dwarfism (5 s.d. below the mean). Our analysis shows that UV-induced ATR activation can occur in non-replicating cells following processing by nucleotide excision repair.