Induction and repression of mammalian achaete-scute homologue (MASH) gene expression during neuronal differentiation of P19 embryonal carcinoma cells

MASH1 and MASH2, mammalian homologues of the Drosophila neural determination genes achaete-scute, are members of the basic helix-loop-helix (bHLH) family of transcription factors. We show here that murine P19 embryonal carcinoma cells can be used as a model system to study the regulation and function of these genes. MASH1 and MASH2 display complementary patterns of expression during the retinoic-acid-induced neuronal differentiation of P19 cells. MASH1 mRNA is undetectable in undifferentiated P19 cells but is induced to high levels by retinoic acid coincident with neuronal differentiation. In contrast, MASH2 mRNA is expressed in undifferentiated P19 cells and is repressed by retinoic acid treatment. These complementary expression patterns suggest distinct functions for MASH1 and MASH2 in development, despite their sequence homology. In retinoic-acid-treated P19 cells, MASH1 protein expression precedes and then overlaps expression of neuronal markers. However, MASH1 is expressed by a smaller proportion of cells than expresses such markers. MASH1 immunoreactivity is not detected in differentiated cells displaying a neuronal morphology, suggesting that its expression is transient. These features of MASH1 expression are similar to those observed in vivo, and suggest that P19 cells represent a good model system in which to study the regulation of this gene. Forced expression of MASH1 was achieved in undifferentiated P19 cells by transfection of a cDNA expression construct. The transfected cells expressing exogenous MASH1 protein contained E-box-binding activity that could be super-shifted by an anti-MASH1 antibody, but exhibited no detectable phenotypic changes. Thus, unlike myogenic bHLH genes, such as MyoD, which are sufficient to induce muscle differentiation, expression of MASH1 appears insufficient to promote neurogenesis

XASH-3, a novel Xenopus achaete-scute homolog, provides an early marker of planar neural induction and position along the mediolateral axis of the neural plate

We have isolated a novel Xenopus homolog of the Drosophila achaete-scute genes, called XASH-3. XASH-3 expression is neural specific and is detected as early as stage 11 1/2, making it one of the earliest markers of neural induction so far described. Moreover, XASH-3 expression within the neural plate is regionally restricted. Transverse bands of XASH-3 mRNA mark discrete positions along the anteroposterior axis, while longitudinal bands mark a discrete position along the mediolateral axis. This latter site of XASH-3 expression appears to demarcate the prospective sulcus limitans, a boundary zone that later separates the functionally distinct dorsal (alar) and ventral (basal) regions of the spinal cord. In sandwich explants lacking any underlying mesoderm, XASH-3 is expressed in longitudinal stripes located lateral to the midline. This provides the first indication that planar or midline-derived inductive signals are sufficient to establish at least some aspects of positional identity along the mediolateral axis of the neural plate. By contrast, the transverse stripes of XASH-3 expression are not detected, suggesting that this aspect of anteroposterior neural pattern is lost or delayed in the absence of vertically passed signals. The restricted mediolateral expression of XASH-3 suggests that mediolateral patterning of the neural plate is an early event, and that this regionalization can be achieved in the absence of inducing signals derived from underlying mesoderm

Roost Site Selection by Red Knots (Calidris canutus rufa) in Delaware Bay

I monitored the roosting preferences of 53 Red Knots (Calidris canutus rufa) during their northbound migratory stopover in Delaware Bay in 2008 and 2009. The goal was to locate the high tide daytime and nighttime roosts as well as to determine the habitat characteristics that create suitable roost sites. Radio-tracking data were used in collaboration with aerial photos to map and locate high tide roost sites. Habitat surveys were used to determine environmental characteristics that correlated with roost site use. Birds preferred shoreline habitat during the day, but preferred inland habitat at night. Birds’ preference for inland roost sites increased significantly at spring tides. The results of this study can inform local resource managers about the restoration and conservation of roost sites in Delaware Bay for shorebirds.Master of ScienceNatural Resources and EnvironmentUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/78411/1/MS_Thesis-Kathryn Zimmerman-Dec2010.pd

Sustainability Policy’s Inherent Dilemmas – Exemplified Via Critical Examination of the Las Vegas Metropolitan Sustainability Campaign

In response to a dual problem of critical water scarcity and rapid population growth, leaders of metropolitan Las Vegas implemented a region-wide, internationally marketed sustainability campaign. Preliminary studies found that, while sustainability policy attains its rhetorical goals, solutions initiated not only perpetuate but also purposefully expand the original dual problem to justify continuous water resource acquisitions. To examine this sustainability conundrum constructed by leadership—problem-perpetuation rather than problem-resolution—a critical examination in resource management asked two basic questions: what is being sustained and by what means? Via this inquiry, specific processes by which leaders perpetuate problems can be identified; and, so-informed, new choices capable of resolving human-constructed dilemmas can be applied. Drawing on Las Vegas’ sustainability campaign as example, this paper argues that sustainability policy inherently sustains polity rather than natural or cultural resources and does so by means of policy structure, policy content (and omissions), and policy goals

XATH-1,a Vertebrate Homolog ofDrosophila atonal,Induces Neuronal Differentiation within Ectodermal Progenitors

AbstractXATH-1,a basic/helix-loop-helix transcription factor and a homolog ofDrosophila atonaland mammalianMATH-1,is expressed specifically in the dorsal hindbrain duringXenopusneural development. In order to investigate the role ofXATH-1in the neuronal differentiation process, we have examined the effects ofXATH-1overexpression duringXenopusdevelopment.XATH-1induces the expression of neuronal differentiation markers, such asN-tubulin,within the neural plate as well as within nonneural ectodermal progenitor populations, resulting in the appearance of process-bearing neurons within the epidermis. The related basic/helix-loop-helix genesneurogenin-related-1andneuroDare not induced in response toXATH-1overexpression within the embryo, suggesting thatXATH-1may activate an alternate pathway of neuronal differentiation. In further contrast toneurogenin-related-1andneuroD,high-level expression of general neural markers expressed earlier in development, such asN-CAM,is not induced byXATH-1overexpression. Competent ectodermal progenitors therefore respond to ectopicXATH-1expression by initiating a distinct program of neuronal differentiation

Feasibility and acceptability of a future‐oriented empowerment program to prevent substance use and school dropout among school‐disengaged youth

ObjectiveTo evaluate the feasibility and acceptability of a health promotion program to prevent school dropout and substance use among middle school‐aged youth who display early warning signs of school disengagement.InterventionYouth Empowerment Solutions for Positive Futures (YES‐PF), an intensive, theoretically driven, 5‐week summer enrichment program, aims to prevent school dropout and substance use by promoting youth empowerment, school engagement, and future orientation.Design and SampleUsing a pre–post‐intervention design, we test feasibility and acceptability with 6th and 7th grade students (n = 43) who exhibited early warning signs for school disengagement (e.g., chronic absenteeism) in two school districts.MeasuresProgram evaluation components included: (a) program session forms completed by facilitators; (b) post‐program interviews with facilitators; (c) post‐intervention program evaluation surveys with youth; (d) attendance; and (e) baseline and post‐intervention surveys with youth to assess behavioral and psychosocial outcomes.ResultsFacilitators routinely delivered core component lesson activities. Acceptability and program satisfaction were evidenced in strong program attendance by youth. Youth participants reported higher levels of leadership efficacy (p < .05) and a greater sense of control over their lives and potential problems (p < .01).ConclusionsYES‐PF was feasible and acceptable to school personnel and youth. Program refinement, based on implementation findings, is discussed.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154506/1/phn12706.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154506/2/phn12706_am.pd

Synthesis and Catalytic Activity of (3,4-Diphenylcyclopentadienone)Iron Tricarbonyl Compounds in Transfer Hydrogenations and Dehydrogenations

Four (3,4-diphenylcyclopentadienone)iron tricarbonyl compounds were synthesized, and their activities in transfer hydrogenations of carbonyl compounds and transfer dehydrogenations of alcohols were explored and compared to those of the well-established [2,5-(SiMe3)2-3,4-(CH2)4(η4-C4C═O)]Fe(CO)3 (3). A new compound, [2,5-bis(3,5-dimethylphenyl)-3,4-diphenylcyclopentadienone]iron tricarbonyl (7), was the most active catalyst in both transfer hydrogenations and dehydrogenations, and compound 3 was the least active catalyst in transfer hydrogenations. Evidence was found for product inhibition of both 3 and 7 in a transfer dehydrogenation reaction, with the activity of 3 being more heavily affected. A monomeric iron hydride derived from 7 was spectroscopically observed during a transfer hydrogenation, and no diiron bridging hydrides were found under reductive or oxidative conditions. Initial results in the transfer hydrogenation of N-benzylideneaniline showed that 3 was a significantly less active catalyst in comparison to the (3,4-diphenylcyclopentadienone)iron tricarbonyl compounds

Expected Limits on the Ocean Acidification Buffering Potential of a Temperate Seagrass Meadow

Ocean acidification threatens many marine organisms, especially marine calcifiers. The only global‐scale solution to ocean acidification remains rapid reduction in CO2 emissions. Nevertheless, interest in localized mitigation strategies has grown rapidly because of the recognized threat ocean acidification imposes on natural communities, including ones important to humans. Protection of seagrass meadows has been considered as a possible approach for localized mitigation of ocean acidification due to their large standing stocks of organic carbon and high productivity. Yet much work remains to constrain the magnitudes and timescales of potential buffering effects from seagrasses. We developed a biogeochemical box model to better understand the potential for a temperate seagrass meadow to locally mitigate the effects of ocean acidification. Then we parameterized the model using data from Tomales Bay, an inlet on the coast of California, USA which supports a major oyster farming industry. We conducted a series of month‐long model simulations to characterize processes that occur during summer and winter. We found that average pH in the seagrass meadows was typically within 0.04 units of the pH of the primary source waters into the meadow, although we did find occasional periods (hours) when seagrass metabolism may modify the pH by up to ±0.2 units. Tidal phasing relative to the diel cycle modulates localized pH buffering within the seagrass meadow such that maximum buffering occurs during periods of the year with midday low tides. Our model results suggest that seagrass metabolism in Tomales Bay would not provide long‐term ocean acidification mitigation. However, we emphasize that our model results may not hold in meadows where assumptions about depth‐averaged net production and seawater residence time within the seagrass meadow differ from our model assumptions. Our modeling approach provides a framework that is easily adaptable to other seagrass meadows in order to evaluate the extent of their individual buffering capacities. Regardless of their ability to buffer ocean acidification, seagrass meadows maintain many critically important ecosystem goods and services that will be increasingly important as humans increasingly affect coastal ecosystems

Ten Years of Experience Training Non-Physician Anesthesia Providers in Haiti.

Surgery is increasingly recognized as an effective means of treating a proportion of the global burden of disease, especially in resource-limited countries. Often non-physicians, such as nurses, provide the majority of anesthesia; however, their training and formal supervision is often of low priority or even non-existent. To increase the number of safe anesthesia providers in Haiti, Médecins Sans Frontières has trained nurse anesthetists (NAs) for over 10 years. This article describes the challenges, outcomes, and future directions of this training program. From 1998 to 2008, 24 students graduated. Nineteen (79%) continue to work as NAs in Haiti and 5 (21%) have emigrated. In 2008, NAs were critical in providing anesthesia during a post-hurricane emergency where they performed 330 procedures. Mortality was 0.3% and not associated with lack of anesthesiologist supervision. The completion rate of this training program was high and the majority of graduates continue to work as nurse anesthetists in Haiti. Successful training requires a setting with a sufficient volume and diversity of operations, appropriate anesthesia equipment, a structured and comprehensive training program, and recognition of the training program by the national ministry of health and relevant professional bodies. Preliminary outcomes support findings elsewhere that NAs can be a safe and effective alternative where anesthesiologists are scarce. Training non-physician anesthetists is a feasible and important way to scale up surgical services resource limited settings