Cellular senescence— defined as a process of stable cell-cycle arrest—was first identified as a biological state that marked the end of a cell’s replicative life (Hayflick, 1965). In the investigations that followed, senescence was established as a component of disease states {e.g. DNA damage} (Kuilman et al., 2010), and was correlated with aging-associated disorders (Keyes et al., 2005; Baker ...

The Ras(17N) dominant negative antagonizes endogenous Ras function by forming stable, inactive complexes with Ras guanine nucleotide exchange factors (GEFs; e.g., SOS1). We have used the growth-inhibitory phenotype of Ras(17N) to characterize two aspects of Ras interaction with GEFs. First, we used a nonprenylated version of Ras(17N), designated Ras(17N/186S), which no longer associates with th...

Bu ara?t?rmada, Siyah Alaca ?rk? süt s???rlar?ndan elde edilen sütlerin Somatik Hücre say?lar? (SHS) tespit edilerek, SHS’n?n mevsim ve laktasyon s?ras?na göre de?i?imi ile verimi kalitesine etkisinin ara?t?r?lmas? amaçlanm??t?r. amaçla 30 ba? sa?mal ine?in bir y?l boyunca her ay al?nan sütleri de?erlendirilmi?tir. Al?nan örnekleri 250 ml’lik numune kaplar?na doldurulmu? +4 C so?uk zincir labor...

Introduction The Center for International Meetings on Biology workshop on ‘Exchange Factors’ provided an up-to-date view of how guaninenucleotide-exchange factors (GEFs) affect the biochemical pathways that regulate the Ras superfamily of small GTPases, and how these molecules function as part of an interrelated network of regulatory proteins that mediate the biological responses of Ras-like GT...

The Dictyostelium ras gene (Dd-ras) is expressed at a low level in vegetative cells, is not expressed between the onset of development and aggregation, and is then re-expressed in the multicellular aggregate stages from the distal, now cAMP-responsive, promoter and from two more proximal promoters. Expression of activated Dd-ras (G12----T12) (Reymond et al. 1986) results in an abnormal developm...

INTRODUCTION Rhabdomyosarcoma (RMS) is a pediatric malignancy thought to arise from the aberrant regulation of developmental programs during myogenesis. It is the most common soft-tissue sarcoma of childhood (Wexler and Helman, 1994; Arndt and Crist, 1999). Treatment approaches are often aggressive and multimodal, involving a combination of chemotherapeutic agents and local surgical resection a...

G lioblastoma multiforme (GBM) are the most common and aggressive adult primary brain tumors. Genetic alterations and their consequences in these malignant astrocytomas have been studied extensively and include (i) overexpression of growth factors and their corresponding receptors (fibroblast growth factor, epidermal growth factor, and platelet-derived growth factors), (ii) abnormalities of tra...

discovery that mutations in single genes can modulate aging was not only fascinating but it provided researchers with animal models with which to study aging in cohorts of different aging rates [1-2]. According to the GenAge database [3], at the time of writing, genetic manipulations in 68 genes have been shown to affect lifespan in mice. Among mouse genes in which mutations extend lifespan, a ...

Because phospholipase C (PLC) is activated by G 12/13 and Rho family GTPases, we investigated whether these G proteins contribute to the increased inositol lipid hydrolysis observed in COS-7 cells after activation of certain G protein-coupled receptors. Stimulation of inositol lipid hydrolysis by endogenous lysophosphatidic acid (LPA) or thrombin receptors was markedly enhanced by the expressio...