Exploring the Importance of Mentoring for New Scholars: A Social Exchange Perspective

This exploratory study examines the importance of mentor/mentee relationships on faculty development by measuring how social exchange between new faculty members (mentees) in information systems and their former dissertation chairs (mentors) relate to how quickly the new faculty members completed their doctoral program and the number of peer reviewed publications they produced in their first six years of academic employment. In addition, this study measures how gender and ethnicity relate to the strength of the social exchange between mentors and mentees. The results show a statistically significant relationship between social ties and the number of publications new faculty obtain in their early years of academic employment. The results also indicate that mixed gender pairs have higher social exchange in this context. This study has implications for shaping doctoral education by providing insight into the importance of social ties on the development and productivity of new faculty

An Empirically Based Calculation of the Extragalactic Infrared Background

Using the excellent observed correlations among various infrared wavebands with 12 and 60 micron luminosities, we calculate the 2-300 micron spectra of galaxies as a function of luminosity. We then use 12 micron and 60 micron galaxy luminosity functions derived from IRAS data, together with recent data on the redshift evolution of galaxy emissivity, to derive a new, empirically based IR background spectrum from stellar and dust emission in galaxies. Our best estimate for the IR background is of order 2-3 nW/m^2/sr with a peak around 200 microns reaching 6-8 nW/m^2/sr. Our empirically derived background spectrum is fairly flat in the mid-IR, as opposed to spectra based on modeling with discrete temperatures which exhibit a "valley" in the mid-IR. We also derive a conservative lower limit to the IR background which is more than a factor of 2 lower than our derived flux.Comment: 14 pages AASTeX, 2 .ps figures, the Astrophysical Journal, in pres

Exploring The Effects Of Social Exchange Relationships On The Scholarly Productivity Of New Faculty Members In Accounting

This paper explores how social relationships between new accounting faculty members and their former dissertation chairs can influence the publishing productivity of the new faculty members in their early academic careers. The focus on social relationships offers a unique approach to studying the effectiveness doctoral education. Our findings show that strong social exchange between new faculty members and their former chairs can have a significant impact on new faculty members’ scholarly productivity and provide some reasons for those effects. We also find differences in relationships between mixed and same gender pairs and examine reasons for those differences

Chromatin profiling of Drosophila CNS subpopulations identifies active transcriptional enhancers

One of the key issues in studying transcriptional regulation during development is how to employ genome-wide assays that reveals sites of open chromatin and transcription factor binding to efficiently identify biologically relevant genes and enhancers. Analysis of Drosophila CNS midline cell development provides a useful system for studying transcriptional regulation at the genomic level due to a large, well-characterized set of midline-expressed genes and in vivo validated enhancers. In this study, FAIRE-seq on FACS-purified midline cells was performed and the midline FAIRE data were compared with whole-embryo FAIRE data. We find that regions of the genome with a strong midline FAIRE peak and weak whole-embryo FAIRE peak overlap with known midline enhancers and provide a useful predictive tool for enhancer identification. In a complementary analysis, we compared a large dataset of fragments that drive midline expression in vivo with the FAIRE data. Midline enhancer fragments with a midline FAIRE peak tend to be near midline-expressed genes, whereas midline enhancers without a midline FAIRE peak were often distant from midline-expressed genes and unlikely to drive midline transcription in vivo

Twine: display and analysis of cis-regulatory modules

Summary: Many algorithms analyze enhancers for overrepresentation of known and novel motifs, with the goal of identifying binding sites for direct regulators of gene expression. Twine is a Java GUI with multiple graphical representations (‘Views’) of enhancer alignments that displays motifs, as IUPAC consensus sequences or position frequency matrices, in the context of phylogenetic conservation to facilitate cis-regulatory element discovery. Thresholds of phylogenetic conservation and motif stringency can be altered dynamically to facilitate detailed analysis of enhancer architecture. Views can be exported to vector graphics programs to generate high-quality figures for publication. Twine can be extended via Java plugins to manipulate alignments and analyze sequences

Drosophila melanogaster Zelda and Single-minded collaborate to regulate an evolutionarily dynamic CNS midline cell enhancer

The Drosophila Zelda transcription factor plays an important role in regulating transcription at the embryonic maternal-to-zygotic transition. However, expression of zelda continues throughout embryogenesis in cells including the developing CNS and trachea, but little is known about its post-blastoderm functions. In this paper, it is shown that zelda directly controls CNS midline and tracheal expression of the link (CG13333) gene, as well as link blastoderm expression. The link gene contains a 5’ enhancer with multiple Zelda TAGteam binding sites that in vivo mutational studies show are required for link transcription. The link enhancer also has a binding site for the Single-minded: Tango and Trachealess:Tango bHLH-PAS proteins that also influences link midline and tracheal expression. These results provide an example of how a transcription factor (Single-minded or Trachealess) can interact with distinct co-regulatory proteins (Zelda or Sox/POU-homeodomain proteins) to control a similar pattern of expression of different target genes in a mechanistically different manner. While zelda and single-minded midline expression is well-conserved in Drosophila, midline expression of link is not well-conserved. Phylogenetic analysis of link expression suggests that ~60 million years ago, midline expression was nearly or completely absent, and first appeared in the melanogaster group (including D. melanogaster, D. yakuba, and D. erecta) >13 million years ago. The differences in expression are due, in part, to sequence polymorphisms in the link enhancer and likely due to altered binding of multiple transcription factors. Less than 6 million years ago, a second change occurred that resulted in high levels of expression in D. melanogaster. This change may be due to alterations in a putative Zelda binding site. Within the CNS, the zelda gene is alternatively spliced beginning at mid-embryogenesis into transcripts that encode a Zelda isoform missing three zinc fingers from the DNA binding domain. This may result in a protein with altered, possibly non-functional, DNA-binding properties. In summary, Zelda collaborates with bHLH-PAS proteins to directly regulate midline and tracheal expression of an evolutionary dynamic enhancer in the post-blastoderm embryo

Susceptibility of Selected Potato Varieties to Zebra Chip Potato Disease

Zebra chip (ZC), an emerging and serious disease of potato has caused millions of dollars in losses to the potato industry in the United States, Mexico, Central America, and New Zealand. The disease has recently been associated with a previously undescribed species of liberibacter tentatively named “Candidatus Liberibacter solanacearum” transmitted to potato by the potato psyllid, Bactericera cockerelli (Šulc). At present, applications of insecticides targeted against the potato psyllid are the only means to manage ZC. Given the low psyllid density and short inoculation access period required to induce the disease, insecticides may not act fast enough to prevent transmission of liberibacter to potato by the psyllid and development of ZC. Identification and development of ZC-resistant or tolerant varieties may offer the most efficient and sustainable way to manage this potato disease. Susceptibility of selected potato varieties to ZC was evaluated under controlled field cage conditions in 2009 and 2010 in WA by inoculating potato plants with “Ca. L. solanacearum” using infective potato psyllids and monitoring them for ZC symptom development. All potato varieties evaluated in both years of the study were determined to be very susceptible to the disease, with almost 100% of the inoculated plants developing severe ZC foliar and tuber symptoms. Potato yield in all tested varieties was significantly affected by ZC, with yield losses ranging from 49.9% to 87. 2%. Information from this research suggests that there is an urgent need to develop new potato varieties that are resistant or tolerant to this damaging potato disease

Diverse modes of Drosophila tracheal fusion cell transcriptional regulation

Drosophila tracheal fusion cells play multiple important roles in guiding and facilitating tracheal branch fusion. Mechanistic understanding of how fusion cells function during development requires deciphering their transcriptional circuitry. In this paper, three genes with distinct patterns of fusion cell expression were dissected by transgenic analysis to identify the cis regulatory modules that mediate their transcription. Bioinformatic analysis involving phylogenetic comparisons coupled with mutational experiments were employed. The dysfusion bHLH-PAS gene was shown to have two fusion cell cis-regulatory modules; one driving initial expression and another autoregulatory module to enhance later transcription. Mutational dissection of the early module identified at least four distinct inputs, and included putative binding sites for ETS and POU homeodomain proteins. The ETS transcription factor Pointed mediates the transcriptional output of the branchless/breathless signaling pathway, suggesting that this pathway directly controls dysfusion expression. Fusion cell cis-regulatory modules of CG13196 and CG15252 require two Dysfusion:Tango binding sites, but additional sequences modulate the breadth of activation in different fusion cell classes. These results begin to decode the regulatory circuitry that guides transcriptional activation of genes required for fusion cell morphogenesis

Time-lapse imaging reveals stereotypical patterns of Drosophila midline glial migration

The Drosophila CNS midline glia (MG) are multifunctional cells that ensheath and provide trophic support to commissural axons, and direct embryonic development by employing a variety of signaling molecules. These glia consist of two functionally distinct populations: the anterior MG (AMG) and posterior MG (PMG). Only the AMG ensheath axon commissures, whereas the function of the non-ensheathing PMG is unknown. The Drosophila MG have proven to be an excellent system for studying glial proliferation, cell fate, apoptosis, and axon-glial interactions. However, insight into how AMG migrate and acquire their specific positions within the axon-glial scaffold has been lacking. In this paper, we use time-lapse imaging, single-cell analysis, and embryo staining to comprehensively describe the proliferation, migration, and apoptosis of the Drosophila MG. We identified 3 groups of MG that differed in the trajectories of their initial inward migration: AMG that migrate inward and to the anterior before undergoing apoptosis, AMG that migrate inward and to the posterior to ensheath commissural axons, and PMG that migrate inward and to the anterior to contact the commissural axons before undergoing apoptosis. In a second phase of their migration, the surviving AMG stereotypically migrated posteriorly to specific positions surrounding the commissures, and their final position was correlated with their location prior to migration. Most noteworthy are AMG that migrated between the commissures from a ventral to a dorsal position. Single-cell analysis indicated that individual AMG possessed wide-ranging and elaborate membrane extensions that partially ensheathed both commissures. These results provide a strong foundation for future genetic experiments to identify mutants affecting MG development, particularly in guidance cues that may direct migration. Drosophila MG are homologous in structure and function to the glial-like cells that populate the vertebrate CNS floorplate, and study of Drosophila MG will provide useful insights into floorplate development and function