Clonal Sectors Reveal That a Specific Meristematic Domain Is Not Utilized in the Maize Mutantnarrow sheath

AbstractThe narrow leaf and shortened stem phenotypes of the maize mutant narrow sheath (ns) are postulated to result from the lack of founder cell initialization in a region of the meristem that gives rise to leaf and stem margins. To test this model, a lineage map of the maize meristem is presented which compares the development of leaf margins in the narrow leaf mutant, narrow sheath (ns), and wild-type sibling plants. X-irradiation of mature seeds produced aneuploid albino sectors in wild-type and ns mutant plants. Of particular interest are sectors occurring in more than one leaf, which reflect a meristematic albino cell lineage. Analyses of these sectors indicated that: (1) a region of the ns meristem does not contribute to the founder cell population of the incipient leaf; (2) the margins of ns mutant leaves are derived from a lateral region of the meristem different from those in wild-type siblings; (3) founder cells in wild-type, juvenile-staged vegetative meristems encircle the meristem to a greater extent than do founder cells in adult-staged meristems; and (4) meristematic leaf founder cells may be subdivided into specific lateral domains, such that the position of a sector on the meristem correlates with a particular cell lineage. These data support our model fornsgene function in a specific domain of the meristem

An Escherichia coli effector protein promotes host mutation via depletion of DNA mismatch repair proteins.

Enteropathogenic Escherichia coli (EPEC) is an attaching and effacing (A/E) human pathogen that causes diarrhea during acute infection, and it can also sustain asymptomatic colonization. A/E E. coli depletes host cell DNA mismatch repair (MMR) proteins in colonic cell lines and has been detected in colorectal cancer (CRC) patients. However, until now, a direct link between infection and host mutagenesis has not been fully demonstrated. Here we show that the EPEC-secreted effector protein EspF is critical for complete EPEC-induced depletion of MMR proteins. The mechanism of EspF activity on MMR protein was posttranscriptional and dependent on EspF mitochondrial targeting. EPEC infection also induced EspF-independent elevation of host reactive oxygen species levels. Moreover, EPEC infection significantly increased spontaneous mutation frequency in host cells, and this effect was dependent on mitochondrially targeted EspF. Taken together, these results support the hypothesis that A/E E. coli can promote colorectal carcinogenesis in humans

Re-conceiving Entrepreneurship for Libraries: Collaboration and the Anatomy of a Conference

For librarians who have worked in the field and have become innovative out of necessity, developing and creating entrepreneurial activities are not unusual. Perhaps recognizing and celebrating those achievements could change common perspectives on the entrepreneurial abilities of librarians. This idea launched the collaborative efforts of two universities to demonstrate this to be so. The libraries at The University of North Carolina at Greensboro and Wake Forest University in Winston-Salem, North Carolina, successfully collaborated on the planning and execution of a conference to celebrate entrepreneurism within the field of librarianship. In doing so, each organization was able to promote its unique talents and give signature to the notion that librarians can be, and in fact are, entrepreneurial. The collaborative value found in this project was derived from our sense of fulfillment of our social responsibility and of celebrating entrepreneurship within the profession. This conference serves as an example of embedded collaboration versus simple logistics, and the conference planning team now looks forward to future endeavors

Autonomy as social independence: reply to Weimer

I defend my pure social account of global autonomy from Steven Weimer’s recent criticisms. In particular, I argue that it does not implicitly rely upon the very kind of nonsocial conception of autonomy that it hopes to replace

Using Acoustic Trajectory Information in Studies of Merger

This study investigates the utility of examining acoustic trajectory information indicative of gliding in the case of mergers or near-mergers. It presents a sociophonetic analysis of conversational speech from one African American Seattle native, who perceives the pin and pen classes as merged. The study finds no difference (“merger”) between the speaker’s pin and pen classes by F1 or F2 at vowel midpoint. However, phonemic vowel distinctions are preserved in Euclidean distance and duration, and the vowel classes are more distinct pre-nasally than in non-pre-nasal contexts. A regression of the researcher’s perception of distance on vowel class corroborates this pattern. Lastly, multidimensional calculation of overlap using SOAM (Wassink 2006) for a small sample of data from 12 Seattle speakers suggests Seattle African Americans differentiate pin from pen somewhat by the amount of glide, while Seattle Whites do not

HEDIS Measures and Managed Care Enrollment

This article examines the relationship between 1996 health plan enrollment and both HEDIS-based plan performance ratings and individual HEDIS measures. Data were obtained from a large firm that collected, aggregated, and disseminated plan performance ratings to its employees. Plan market share regressions are estimated controlling for out-of-pocket price and model type in addition to the plan ratings and HEDIS measures. The results suggest that employees did not respond strongly to the provided ratings. There are several potential explanations for the lack of response, including difficulty understanding the ratings and never having seen them. In addition, employees may base their plan choices on information that is obtained from their own past experience, friends, family, and colleagues. The pattern of results suggests that such information is important. Counterintuitive signs most likely reflect an inverse correlation between some HEDIS ratings (or measures) and attributes employees observe informally.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68992/2/10.1177_107755879905600204.pd

Genome-Wide Association Study for Maize Leaf Cuticular Conductance Identifies Candidate Genes Involved in the Regulation of Cuticle Development.

The cuticle, a hydrophobic layer of cutin and waxes synthesized by plant epidermal cells, is the major barrier to water loss when stomata are closed at night and under water-limited conditions. Elucidating the genetic architecture of natural variation for leaf cuticular conductance (g c) is important for identifying genes relevant to improving crop productivity in drought-prone environments. To this end, we conducted a genome-wide association study of g c of adult leaves in a maize inbred association panel that was evaluated in four environments (Maricopa, AZ, and San Diego, CA, in 2016 and 2017). Five genomic regions significantly associated with g c were resolved to seven plausible candidate genes (ISTL1, two SEC14 homologs, cyclase-associated protein, a CER7 homolog, GDSL lipase, and β-D-XYLOSIDASE 4). These candidates are potentially involved in cuticle biosynthesis, trafficking and deposition of cuticle lipids, cutin polymerization, and cell wall modification. Laser microdissection RNA sequencing revealed that all these candidate genes, with the exception of the CER7 homolog, were expressed in the zone of the expanding adult maize leaf where cuticle maturation occurs. With direct application to genetic improvement, moderately high average predictive abilities were observed for whole-genome prediction of g c in locations (0.46 and 0.45) and across all environments (0.52). The findings of this study provide novel insights into the genetic control of g c and have the potential to help breeders more effectively develop drought-tolerant maize for target environments

Discolored1 (DSC1) is an ADP-Ribosylation Factor-GTPase Activating Protein Required to Maintain Differentiation of Maize Kernel Structures

The embryo and endosperm are the products of double fertilization and comprise the clonally distinct products of angiosperm seed development. Recessive mutations in the maize gene discolored1 (dsc1) condition inviable seed that are defective in both embryo and endosperm development. Here, detailed phenotypic analyses illustrate that discolored mutant kernels are able to establish, but fail to maintain, differentiated embryo, and endosperm structures. Development of the discolored mutant embryo and endosperm is normal albeit delayed, prior to the abortion and subsequent degeneration of all differentiated kernel structures. Using a genomic fragment that was previously isolated by transposon tagging, the full length dsc1 transcript is identified and shown to encode an ADP-ribosylation factor-GTPase activating protein (ARF-GAP) that co-localizes with the trans-Golgi network/early endosomes and the plasma membrane during transient expression assays in N. benthamiana leaves. DSC1 function during endomembrane trafficking and the maintenance of maize kernel differentiation is discussed

Distribution and Environmental Tolerances of Aquatic Macroinvertebrate Families in the Agricultural Zone of Southwestern Australia

The agricultural zone of southwestern Australia is an extensively modified landscape. Ninety percent of the perennial native vegetation has been cleared and replaced by annual cereal crops and pasture. Consequently, groundwater has risen and much of the region is affected by dryland salinity. River geomorphology and water quality have been severely impacted by land clearing, anthropogenic patterns of land use, and secondary salinization. The objectives of this study were to determine patterns of distribution of aquatic macroinvertebrates in the region, and to identify environmental variables influencing these patterns. Aquatic macroinvertebrates were sampled at 176 river sites during spring 1997 and a range of environmental data were collected at each site. Eighty-one families were collected, with the fauna being dominated by insects. At the family level, macroinvertebrate communities were homogeneous and depauperate, and consisted of families that tolerated a broad range of environmental conditions. The fauna was particularly resilient to high salinities, with some families tolerating salinities orders of magnitude greater than previously reported for lotic waters. The most significant environmental factors influencing the distribution of aquatic invertebrates were rainfall, salinity, land use, and instream habitat