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

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

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

The Impact of Health Workers' Strikes on Health Outcomes and Health Service Utilization in Low-and Middle-Income Countries: A Systematic Review

Background The impact of strikes by health workers in low- and middle-income countries (LMIC) is not well described. We systematically reviewed articles on the impact of health workers’ strikes on health outcomes or health service utilization in LMIC. Methods We searched PubMed, SCOPUS, Web of Science, and Google Scholar databases on May 27, 2019. To be included for review, articles met the following criteria: (1) reported on a strike that involved at least one cadre of health worker; (2) reported on a strike in a LMIC; (3) included at least one outcome related to patient or population health or health service utilization; and, (4) included a reference group or time period. There were no date or language restrictions. We modified the Newcastle-Ottawa Tool to appraise study quality. The review is registered with PROSPERO (CRD42019124989). Findings Among 5,123 articles, eleven articles met inclusion criteria. Studies examined 20 strikes in LMIC from 1991 to 2017 (average strike length of 32·9 days), with five studies from Kenya, two each from India and Nigeria, and one each from Malawi and South Africa. The majority of studies reported hospital admissions or inpatient mortality. Generally, health service utilization decreased during strike periods, but changes in patient mortality and other health outcomes varied. Study quality was heterogenous with most studies reporting from a single facility or medical department. Interpretation Compared to high-income settings, our study suggests a more complex picture of the effect of strikes by health workers on health and health service utilization outcomes in LMIC

Area-level incarceration and STI risk among a cohort of justice-involved adolescents and adults

Background: Living in areas of high incarceration is associated with increased risk of STI; however, STI risk with respect to both this area-level exposure and an individual’s involvement with the justice system is not known. Objective: Among individuals before and after arrest or incarceration, assess the association between area-level incarceration rates and risk of chlamydia, gonorrhea, or syphilis. Methods: Retrospective cohort study of individuals living in Marion County (Indianapolis), Indiana who were arrested or in jail, prison, juvenile detention, or juvenile prison between 2005-2008 (N=97,765). Area-level incarceration exposure was defined by the proportion of person-days incarcerated among the total population*365 within a census block group. A 1-year period was assessed before and after a randomly-selected arrest/incarceration per person. Multivariable logistic regression, controlling for age, race, STI history, and year, was performed to assess chlamydia, gonorrhea, or syphilis risk by quartile area-level incarceration exposure, adjusting for individual clustering and stratifying by gender. Results: Area-level incarceration was associated with increased odds of each STI, with a dose response relationship particularly among those with an arrest or jail stay. Women with a history of arrest or jail/prison stay and living in high incarceration areas had higher odds of STI, compared to men with comparable incarceration history and living in similar areas

Effect of Polyethylene Glycol 3350 on the Handling Properties of Low Salt Wheat Dough Formulations

The effect of polyethylene glycol (PEG) 3350 addition (3%, flour wt. basis) on the properties of dough made from two Canadian Western Red Spring wheat cultivars (Triticum aestivum L. ‘Harvest’ and ‘Pembina’) differing in dough mixing requirements and dough-handling properties was investigated in a low salt dough formulation (1% NaCl, flour wt. basis). PEG was added for experimental purposes to alter water mobility to better understand underlining mechanisms, however would not be used in real bread formulations. For cultivar Harvest, but not Pembina, dough stickiness was reduced by the addition of PEG. Dough freezable water content decreased with the addition of PEG for both cultivars. Rheological measurements showed that PEG increased dough stiffness as measured by the complex modulus |G*|. Creep measurements indicated that the relative elastic component (Jel) increased whereas maximum deformation (Jmax) decreased with the addition of PEG for cultivar Harvest only. Dough made with a weaker cultivar (Harvest) with the addition of PEG performed similarly to dough made with a stronger cultivar (Pembina) without PEG. Results indicate that in a low sodium environment, availability of water is critically important for controlling a number of properties that relate closely to dough machinability, especially in a weaker wheat cultivar

Fractionation and subfunctionalization following genome duplications : mechanisms that drive gene content and their consequences

A gene's duplication relaxes selection. Loss of duplicate, low-function DNA (fractionation) sometimes follows, mostly by deletion in plants, but mostly via the pseudogene pathway in fish and other clades with smaller population sizes. Subfunctionalization — the founding term of the Xfunctionalization lexicon — while not the general cause of differences in duplicate gene retention, becomes primary as the number of a gene's cis — regulatory sites increases. Balanced gene drive explains retention for the average gene. Both maintenance-of-balance and subfunctionalization drive gene content nonrandomly, and currently fall outside of our accepted Theory of Evolution. The ‘typical’ mutation encountered by a gene duplicate is not a neutral loss-of-function; dominant mutations (Muller's lexicon; these are not neutral) abound, and confound X functionalization terms like ‘neofunctionalization’. Confusion of words may cause confusion of thought. As with many plants, fish tetraploidies provide a higher throughput surrogate-genetic method to infer function from human and other vertebrate ENCODE-like regulatory sites. ‘Not only have studies on polyploid fractionation led to reconsiderations of fundamental evolutionary theory, but fractionation in polyploids permits higher-throughput comparative genomic experiments using ENCODE-like data yielding the logical precision expected of genetic analyses.’Keywords: The Theory of Evolution, fractionation, Gene Balance Hypothesis, genome dominance, Whole genome duplication, subfunctionalization, dominant mutatio

Test positivity for chlamydia, gonorrhea, and syphilis infection among a cohort of individuals released from jail in Marion County, Indiana

BACKGROUND: Individuals entering jails have high rates of sexually transmitted infections (STI), but there are few data on STI in the postincarceration period. This study aimed to describe rates of chlamydia, gonorrhea, and syphilis infection among individuals released from Marion County (Indianapolis), Indiana jails. METHODS: We conducted a retrospective cohort study of individuals incarcerated in Marion County, Indiana jails from 2003 to 2008 (n = 118,670). We linked county jail and public health data to identify individuals with positive STI test results in the 1 year after release from jail. Rates per 100,000 individuals and Cox proportional hazard analyses were performed for each STI, stratified by demographic, STI, and jail characteristics. RESULTS: We found significantly higher rates of STI in this cohort than in the general population, with rates in the 1 year after release being 2 to 7 times higher for chlamydia, 5 to 24 times higher for gonorrhea, and 19 to 32 times higher for syphilis compared with rates in the general population. Characteristics most associated with increased risk of a positive STI test result among this cohort were younger age for chlamydia and gonorrhea, older age for syphilis, black race for men, being jailed for prostitution for women, history of STI, and history of prior incarceration. CONCLUSIONS: This study found high rates of STIs among a cohort of individuals recently released from jail and identified a number of risk factors. Further study is needed to improve targeted STI testing and treatment among this high-risk population