Skeletal muscle cells lacking the retinoblastoma protein display defects in muscle gene expression and accumulate in S and G2 phases of the cell cycle.

Viral oncoproteins that inactivate the retinoblastoma tumor suppressor protein (pRb) family both block skeletal muscle differentiation and promote cell cycle progression. To clarify the dependence of terminal differentiation on the presence of the different pRb-related proteins, we have studied myogenesis using isogenic primary fibroblasts derived from mouse embryos individually deficient for pRb, p107, or p130. When ectopically expressed in fibroblasts lacking pRb, MyoD induces an aberrant skeletal muscle differentiation program characterized by normal expression of early differentiation markers such as myogenin and p21, but attenuated expression of late differentiation markers such as myosin heavy chain (MHC). Similar defects in MHC expression were not observed in cells lacking either p107 or p130, indicating that the defect is specific to the loss of pRb. In contrast to wild-type, p107-deficient, or p130-deficient differentiated myocytes that are permanently withdrawn from the cell cycle, differentiated myocytes lacking pRb accumulate in S and G2 phases and express extremely high levels of cyclins A and B, cyclin-dependent kinase (Cdk2), and Cdc2, but fail to readily proceed to mitosis. Administration of caffeine, an agent that removes inhibitory phosphorylations on inactive Cdc2/cyclin B complexes, specifically induced mitotic catastrophe in pRb-deficient myocytes, consistent with the observation that the majority of pRb-deficient myocytes arrest in S and G2. Together, these findings indicate that pRb is required for the expression of late skeletal muscle differentiation markers and for the inhibition of DNA synthesis, but that a pRb-independent mechanism restricts entry of differentiated myocytes into mitosis

Development Of A BioWin-Based Model Of A Small Lagoon Wastewater Treatment System

An aerated lagoon wastewater treatment facility (WWTF) was modeled using BioWin wastewater treatment simulation software. Comprehensive model sensitivity analysis and wastewater characterization throughout the treatment train were performed for model calibration. Two separate calibrated models were necessary to accommodate the large seasonal variations in flow and loading experienced at the WWTF. Dynamic models using variable volume modeling elements to represent the WWTF’s two lagoons were most effective for predicting lagoon performance. The calibrated models were generally able to accurately predict trends in nitrogen, phosphorus, chemical oxygen demand levels and speciation throughout the treatment train and in the effluent. Both models struggled to accurately predict accumulation and removal of solids in the system due to the complex solids removal processes which occur in lagoons. Sludge impacts were assumed to be negligible in modeling, and the lagoons were modeled as completely mixed reactors. Both assumptions were verified via comprehensive lagoon profiling

\u27And I am a Material Girl\u27: How Aesthetics and Material Culture Fashion Femininity in Edith Wharton\u27s The Age of Innocence, from Text to Film

This thesis explores the role of aesthetics and material culture in Edith Wharton’s 1920 novel The Age of Innocence and in Martin Scorsese’s 1993 film adaptation. In Wharton’s Old New York, material opulence is arguably the most essential aspect of culture. Newland Archer is the primary authority on fashion and taste within the narrative, and is thus charged with enforcing standards of socially constructed Victorian femininity with regard to his two romantic interests, May Welland and Ellen Olenska. Scorsese’s film uses mise-en-scène to echo the detail rich design aesthetic found in Wharton’s prose; however, the film’s abandonment of Newland’s distinctly masculine perspective in favor of a female narrator restructures the power dynamics found in Wharton’s narrative. Both the novel and film highlight society’s fetishizing of material culture, a systematic obsession rooted in the oppressive qualities of the Victorian social climate. For both the novel and the film, material opulence is powerful within society because it is the only form of self-expression and individual agency that the characters have access to given the standards of repression, especially for women. Materials can only represent identity and experience and are therefore meaningless. Wharton and Scorsese use their works to criticize the tyranny of materialism during the Victorian period

Managerial Roles and Entrepreneurship in Non-Profit Urban Arts Agencies in Virginia

The future of the arts in Virginia depends on knowing how arts agencies are functioning and surviving at a time of resource decline. What roles do managers play in administering agencies? What business and management skills do managers use to maintain an agency and to relate to the community? How do managers handle cutbacks? Does entrepreneurship create more viable arts agencies? Bivariate data analysis separated managers into four role groups: entrepreneur, administrator, artist, and caretaker, according to their perceived degree of programmatic creativity and documented access to organizational resources. Managerial role types were compared with management behaviors to discern significant differences. Data revealed that the entrepreneur is mostly found in visual arts agencies, is highly creative and attentive to business matters, and tends to work alone. The administrator is generally found in large music and theatrical agencies, manages a highly complex organization with a large staff, budget, and board; this type does not emphasize creativity. The artist, predictably the most highly creative, lacks sufficient managerial skills to maintain a stable organization, and is largely located in smaller music, theatre or dance agencies. The caretaker, found in every type of agency, lacks creative purpose and resources, and is in constant peril of merger or termination. All role types employ the same basic cutback strategies, but vary in their positive attempts to increase revenues and audiences according to role type and agency type. In light of external pressures, the entrepreneur is not distinguished from other role types in demonstrating greater agency viability

Foxp1 and lhx1 coordinate motor neuron migration with axon trajectory choice by gating Reelin signalling.

Topographic neuronal maps arise as a consequence of axon trajectory choice correlated with the localisation of neuronal soma, but the identity of the pathways coordinating these processes is unknown. We addressed this question in the context of the myotopic map formed by limb muscles innervated by spinal lateral motor column (LMC) motor axons where the Eph receptor signals specifying growth cone trajectory are restricted by Foxp1 and Lhx1 transcription factors. We show that the localisation of LMC neuron cell bodies can be dissociated from axon trajectory choice by either the loss or gain of function of the Reelin signalling pathway. The response of LMC motor neurons to Reelin is gated by Foxp1- and Lhx1-mediated regulation of expression of the critical Reelin signalling intermediate Dab1. Together, these observations point to identical transcription factors that control motor axon guidance and soma migration and reveal the molecular hierarchy of myotopic organisation

Cholesterol activates the G-protein coupled receptor Smoothened to promote Hedgehog signaling

Cholesterol is necessary for the function of many G-protein coupled receptors (GPCRs). We find that cholesterol is not just necessary but also sufficient to activate signaling by the Hedgehog (Hh) pathway, a prominent cell-cell communication system in development. Cholesterol influences Hh signaling by directly activating Smoothened (SMO), an orphan GPCR that transmits the Hh signal across the membrane in all animals. Unlike most GPCRs, which are regulated by cholesterol through their heptahelical transmembrane domains, SMO is activated by cholesterol through its extracellular cysteine-rich domain (CRD). Residues shown to mediate cholesterol binding to the CRD in a recent structural analysis also dictate SMO activation, both in response to cholesterol and to native Hh ligands. Our results show that cholesterol can initiate signaling from the cell surface by engaging the extracellular domain of a GPCR and suggest that SMO activity may be regulated by local changes in cholesterol abundance or accessibility

IPMK and ??-catenin mediate PLC-??1-dependent signaling in myogenic differentiation

In previous studies, we have reported that phospholipase C (PLC)-??1 plays a crucial role in myogenic differentiation and we determined the importance of its catalytic activity for the initiation of this process. Here we define the effectors that take part to its signaling pathway. We show that the Inositol Polyphosphate Multikinase (IPMK) is able to promote myogenic differentiation since its overexpression determines the up-regulation of several myogenic markers. Moreover, we demonstrate that IPMK activates the same cyclin D3 promoter region targeted by PLC-??1 and that IPMKinduced promoter activation relies upon c-jun binding to the promoter, as we have shown previously for PLC-??1. Furthermore, our data shows that IPMK overexpression causes an increase in ??-catenin translocation and accumulation to the nuclei of differentiating myoblasts resulting in higher MyoD activation. Finally, we describe that PLC-??1 overexpression determines too an increase in ??-catenin translocation and that PLC-??1, IPMK and ??-catenin are mediators of the same signaling pathway since their overexpression results in cyclin D3 and myosin heavy chain (MYH) induction.ope

Establishment of Motor Neuron-V3 Interneuron Progenitor Domain Boundary in Ventral Spinal Cord Requires Groucho-Mediated Transcriptional Corepression

Background: Dorsoventral patterning of the developing spinal cord is important for the correct generation of spinal neuronal types. This process relies in part on cross-repressive interactions between specific transcription factors whose expression is regulated by Sonic hedgehog. Groucho/transducin-like Enhancer of split (TLE) proteins are transcriptional corepressors suggested to be recruited by at least certain Sonic hedgehog-controlled transcription factors to mediate the formation of spatially distinct progenitor domains within the ventral spinal cord. The aim of this study was to characterize the involvement of TLE in mechanisms regulating the establishment of the boundary between the most ventral spinal cord progenitor domains, termed pMN and p3. Because the pMN domain gives rise to somatic motor neurons while the p3 domain generates V3 interneurons, we also examined the involvement of TLE in the acquisition of these neuronal fates. Methodology and Principal Findings: A combination of in vivo loss- and gain-of-function studies in the developing chick spinal cord was performed to characterize the role of TLE in ventral progenitor domain formation. It is shown here that TLE overexpression causes increased numbers of p3 progenitors and promotes the V3 interneuron fate while suppressing the motor neuron fate. Conversely, dominant-inhibition of TLE increases the numbers of pMN progenitors and postmitotic motor neurons. Conclusion: Based on these results, we propose that TLE is important to promote the formation of the p3 domain an

Interpretation of the sonic hedgehog morphogen gradient by a temporal adaptation mechanism

Morphogens act in developing tissues to control the spatial arrangement of cellular differentiation(1,2). The activity of a morphogen has generally been viewed as a concentration-dependent response to a diffusible signal, but the duration of morphogen signalling can also affect cellular responses(3). One such example is the morphogen sonic hedgehog (SHH). In the vertebrate central nervous system and limbs, the pattern of cellular differentiation is controlled by both the amount and the time of SHH exposure(4-7). How these two parameters are interpreted at a cellular level has been unclear. Here we provide evidence that changing the concentration or duration of SHH has an equivalent effect on intracellular signalling. Chick neural cells convert different concentrations of SHH into time-limited periods of signal transduction, such that signal duration is proportional to SHH concentration. This depends on the gradual desensitization of cells to ongoing SHH exposure, mediated by the SHH-dependent upregulation of patched 1 (PTC1), a ligand-binding inhibitor of SHH signalling(8). Thus, in addition to its role in shaping the SHH gradient(8-10), PTC1 participates cell autonomously in gradient sensing. Together, the data reveal a novel strategy for morphogen interpretation, in which the temporal adaptation of cells to a morphogen integrates the concentration and duration of a signal to control differential gene expression.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62511/1/nature06347.pd