Immigrants and Native Workers: An Analysis of the Long Run Impact of Immigrants on Native Workers

In this study I examine how new labor market entrants affect employment, poverty, and income and how this varies for different subcategories of the population within Combined Statistical Areas (CSAs) and metropolitan and micropolitan statistical areas not within a CSA. These subcategories are sorted by nativity and education level and I specifically look at how foreign born workers impact native workers. The effect can be measured by looking at the changes in population for high-skilled/low-skilled natives and migrants and comparing this to the changes in the number of persons employed, unemployed, in poverty, out of poverty, etc. The time period for the population change is adjusted relative to the time period for the employment change to look at the short run and long run effects of immigration. I use the initial population size for each subgroup as a control. My data source is the American Community Survey from the United States Census Bureau. I find that most of the effect that immigrants have on native workers is negative, however these effects are very minimal for an increase in the low-skilled immigrant population. An increase in the high-skilled immigrant population has a larger negative effect on native workers than an increase in the low-skilled immigrant population. An increase in the native population has the greatest negative impact on native workers

Phylogenomics of Xanthomonas field strains infecting pepper and tomato reveals diversity in effector repertoires and identifies determinants of host specificity

Citation: Schwartz, A. R., Potnist, N., Milsina, S., Wilson, M., Patane, J., Martins, J., . . . Staskawicz, B. J. (2015). Phylogenomics of Xanthomonas field strains infecting pepper and tomato reveals diversity in effector repertoires and identifies determinants of host specificity. Frontiers in Microbiology, 6, 17. https://doi.org/10.3389/fmicb.2015.00535Bacterial spot disease of pepper and tomato is caused by four distinct Xanthomonas species and is a severely limiting factor on fruit yield in these crops. The genetic diversity and the type Ill effector repertoires of a large sampling of field strains for this disease have yet to be explored on a genomic scale, limiting our understanding of pathogen evolution in an agricultural setting. Genomes of 67 Xanthomonas euvesicatoria (Xe), Xanthomonas perforans (Xp), and Xanthomonas gardneri (Kg) strains isolated from diseased pepper and tomato fields in the southeastern and midwestern United States were sequenced in order to determine the genetic diversity in field strains. Type Ill effector repertoires were computationally predicted for each strain, and multiple methods of constructing phylogenies were employed to understand better the genetic relationship of strains in the collection. A division in the Xp population was detected based on core genome phylogeny, supporting a model whereby the host-range expansion of Xp field strains on pepper is due, in part, to a loss of the effector AvrBsT. Xp-host compatibility was further studied with the observation that a double deletion of AvrBsT and XopQ allows a host range expansion for Nicotiana benthamiana. Extensive sampling of field strains and an improved understanding of effector content will aid in efforts to design disease resistance strategies targeted against highly conserved core effectors.Additional Authors: Goss, E.;Bart, R. S.;Setubal, J. C.;Jones, J. B.;Staskawicz, B. J

Elementos traço e parasitismo em tilápia do nilo cultivada no sul do Brasil

This study evaluated the trace elements and parasitological indices in Nile tilapia examined from two different facilities, named as swine-consorted, using pig manure, and monoculture. For trace element analysis, the fish muscle tissue was collected individually in each facility. Each portion was weighed, dried in a stove at 60°C for 48 h and analyzed by Energy Dispersive X-ray Fluorescence Spectrometry (EDXRF). Parasitological analysis followed the routine method for parasites collection, quantification and identification. The predominant element was zinc (Zn) followed by iron (Fe) and arsenic (As) in fish from both facilities. Fish from swine-consorted system had greater values of abundance and mean intensity of trichodinids and fish from monoculture showed higher abundance and mean intensity of monogeneans. Nevertheless, no signs of damage to fish production was observed. The contents of the elements Zn, Fe, As, cooper (Cu) and mercury (Hg) were above of the maximum permitted limits recommended by the Brazilian legislation. © 2016, Instytut Technologii Drewna. All rights reserved

Prospects for plant defence activators and biocontrol in IPM - Concepts and lessons learnt so far

There is an urgent need to develop new interventions to manage pests because evolution of pesticide resistance and changes in legislation are limiting conventional control options for farmers. We investigated β-aminobutyric acid (BABA), jasmonic acid (JA) and fructose as possible plant defence activators against grey mould disease, . Botrytis cinerea, and root knot nematode, . Meloidogyne incognita. We also tested . Trichogramma achaeae parasitoid wasps and an antifeedant plant extract for biocontrol of the invasive tomato leafminer, . Tuta absoluta. BABA and JA enhanced resistance of tomato plants to . B. cinerea but neither treatment provided complete protection and the efficacy of treatment varied over time with BABA being more durable than JA. Efficacy was partly dependent on tomato cultivar, with some cultivars responding better to BABA treatment than others. Furthermore, treatment of tomato with BABA, JA and fructose led to partial suppression of . M. incognita egg mass development. Biocontrol agent, . T. achaeae, performance against . T. absoluta could be enhanced by adjusting the rearing conditions. Both attack rate and longevity were improved by rearing the parasitoids on . T. absoluta rather than on other insects. Finally, . Ajuga chamaepitys extract was shown to have significant antifeedant activity against . T. absoluta. Our findings suggest that there are potential new solutions for protection of crops but they are more complicated to deploy, more variable and require more biological knowledge than conventional pesticides. In isolation, they may not provide the same level of protection as pesticides but are likely to be more potent when deployed in combination in IPM strategies

Enhanced Botrytis cinerea resistance of Arabidopsis plants grown in compost may be explained by increased expression of defense-related genes, as revealed by microarray analysis

Composts are the products obtained after the aerobic degradation of different types of organic matter waste and can be used as substrates or substrate/soil amendments for plant cultivation. There is a small but increasing number of reports that suggest that foliar diseases may be reduced when using compost, rather than standard substrates, as growing medium. The purpose of this study was to examine the gene expression alteration produced by the compost to gain knowledge of the mechanisms involved in compost-induced systemic resistance. A compost from olive marc and olive tree leaves was able to induce resistance against Botrytis cinerea in Arabidopsis, unlike the standard substrate, perlite. Microarray analyses revealed that 178 genes were differently expressed, with a fold change cut-off of 1, of which 155 were up-regulated and 23 were down-regulated in compost-grown, as against perlite-grown plants. A functional enrichment study of up-regulated genes revealed that 38 Gene Ontology terms were significantly enriched. Response to stress, biotic stimulus, other organism, bacterium, fungus, chemical and abiotic stimulus, SA and ABA stimulus, oxidative stress, water, temperature and cold were significantly enriched, as were immune and defense responses, systemic acquired resistance, secondary metabolic process and oxireductase activity. Interestingly, PR1 expression, which was equally enhanced by growing the plants in compost and by B. cinerea inoculation, was further boosted in compost-grown pathogen-inoculated plants. Compost triggered a plant response that shares similarities with both systemic acquired resistance and ABA-dependent/independent abiotic stress responses

Multiple Recombination Events Drive the Current Genetic Structure of Xanthomonas perforans in Florida

Prior to the identification of Xanthomonas perforans associated with bacterial spot of tomato in 1991, X. euvesicatoria was the only known species in Florida. Currently, X. perforans is the Xanthomonas sp. associated with tomato in Florida. Changes in pathogenic race and sequence alleles over time signify shifts in the dominant X. perforans genotype in Florida. We previously reported recombination of X. perforans strains with closely related Xanthomonas species as a potential driving factor for X. perforans evolution. However, the extent of recombination across the X. perforans genomes was unknown. We used a core genome multilocus sequence analysis approach to identify conserved genes and evaluated recombination-associated evolution of these genes in X. perforans. A total of 1,356 genes were determined to be “core” genes conserved among the 58 X. perforans genomes used in the study. Our approach identified three genetic groups of X. perforans in Florida based on the principal component analysis (PCA) using core genes. Nucleotide variation in 241 genes defined these groups, that are referred as Phylogenetic-group Defining (PgD) genes. Furthermore, alleles of many of these PgD genes showed 100% sequence identity with X. euvesicatoria, suggesting that variation likely has been introduced by recombination at multiple locations throughout the bacterial chromosome. Site-specific recombinase genes along with plasmid mobilization and phage associated genes were observed at different frequencies in the three phylogenetic groups and were associated with clusters of recombinant genes. Our analysis of core genes revealed the extent, source, and mechanisms of recombination events that shaped the current population and genomic structure of X. perforans in Florida

Mycorrhizal fungi as mediators of defence against insect pests in agricultural systems

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74655/1/j.1461-9563.2009.00445.x.pd

A Glutamic Acid-Rich Protein Identified in Verticillium dahliae from an Insertional Mutagenesis Affects Microsclerotial Formation and Pathogenicity

Verticillium dahliae Kleb. is a phytopathogenic fungus that causes wilt disease in a wide range of crops, including cotton. The life cycle of V. dahliae includes three vegetative phases: parasitic, saprophytic and dormant. The dormant microsclerotia are the primary infectious propagules, which germinate when they are stimulated by root exudates. In this study, we report the first application of Agrobacterium tumefaciens-mediated transformation (ATMT) for construction of insertional mutants from a virulent defoliating isolate of V. dahliae (V592). Changes in morphology, especially a lack of melanized microsclerotia or pigmentation traits, were observed in mutants. Together with the established laboratory unimpaired root dip-inoculation approach, we found insertional mutants to be affected in their pathogenicities in cotton. One of the genes tagged in a pathogenicity mutant encoded a glutamic acid-rich protein (VdGARP1), which shared no significant similarity to any known annotated gene. The vdgarp1 mutant showed vigorous mycelium growth with a significant delay in melanized microsclerotial formation. The expression of VdGARP1 in the wild type V529 was organ-specific and differentially regulated by different stress agencies and conditions, in addition to being stimulated by cotton root extract in liquid culture medium. Under extreme infertile nutrient conditions, VdGARP1 was not necessary for melanized microsclerotial formation. Taken together, our data suggest that VdGARP1 plays an important role in sensing infertile nutrient conditions in infected cells to promote a transfer from saprophytic to dormant microsclerotia for long-term survival. Overall, our findings indicate that insertional mutagenesis by ATMT is a valuable tool for the genome-wide analysis of gene function and identification of pathogenicity genes in this important cotton pathogen