The organic compound diethylhexyl phthalate (DEHP) represents a high production volume chemical found in cosmetics, personal care products, laundry detergents, and household items. DEHP, along with other phthalates causes endocrine disruption in males. Exposure to endocrine disrupting chemicals has been linked to the development of several adverse health outcomes with apical end points including Non-Alcoholic Fatty Liver Disease (NAFLD). This study examined the adult male zebrafish (Danio rerio) transcriptome after exposure to environmental levels of DEHP and 17α-ethinylestradiol (EE2) using both DNA microarray and RNA-sequencing technologies. Our results show that exposure to DEHP is associated with differentially expressed (DE) transcripts associated with the disruption of metabolic processes in the liver, including perturbation of five biological pathways: ‘FOXA2 and FOXA3 transcription factor networks’, ‘Metabolic pathways’, ‘metabolism of amino acids and derivatives’, ‘metabolism of lipids and lipoproteins’, and ‘fatty acid, triacylglycerol, and ketone body metabolism’. DE transcripts unique to DEHP exposure, not observed with EE2 (i.e. non-estrogenic effects) exhibited a signature related to the regulation of transcription and translation, and ruffle assembly and organization. Collectively our results indicate that exposure to low DEHP levels modulates the expression of liver genes related to fatty acid metabolism and the development of NAFLD.
Forest tree species are increasingly subject to severe mortalities from exotic pests, pathogens, and invasive organisms, accelerated by climate change. Such forest health issues are threatening multiple species and ecosystem sustainability globally. One of the most extreme examples of forest ecosystem disruption is the extirpation of the American chestnut (Castanea dentata) caused by the introduction of chestnut blight and root rot pathogens from Asia. Asian species of chestnut are being employed as donors of disease resistance genes to restore native chestnut species in North America and Europe. To aid in the restoration of threatened chestnut species, we present the assembly of a reference genome for Chinese chestnut (C. mollissima) "Vanuxem," one of the donors of disease resistance for American chestnut restoration. From the de novo assembly of the complete genome (725.2 Mb in 14,110 contigs), over half of the sequences have been anchored to the 12 genetic linkage groups. The anchoring is validated by genetic maps and in situ hybridization to chromosomes. We demonstrate the value of the genome as a platform for research and species restoration, including signatures of selection differentiating American chestnut from Chinese chestnut to identify important candidate genes for disease resistance, comparisons of genome organization with other woody species, and a genome-wide examination of progress in backcross breeding for blight resistance. This reference assembly should prove of great value in the understanding, improvement, and restoration of chestnut species.
Chloroplast DNA is a part of plant non-nuclear genome, and is of particular interest for lineage studies. Moreover, the non-coding regions of cpDNA display higher mutation rates than the conserved coding cpDNA, which has been employed for phylogenetic and population research. We analyzed the cpDNA of 332 gDNA samples from collections of Cornus florida and C. kousa (commercial cultivars, breeding selections, and wild kousa accessions from Asia), using the chlorotyping system developed on North America-native, wild accessions of C. florida. Our results indicated significant differences in chlorotype frequencies between the two species. Cornus florida samples were represented by all major chlorotypes previously described, whereas all C. kousa samples analyzed had only one of the chlorotype patterns shown by C. florida. The chlorotyping analytic panel was then expanded by sequencing the targeted three non-coding cpDNA regions. Results indicated a major difference in the maternally-inherited cpDNA between the two closely related Big-Bracted Cornus species. Chlorotype diversity and differences in the proportion of informative sites in the cpDNA regions of focus emphasized the importance of proper loci choice for cpDNA-based comparative studies between the closely related dogwood species. Phylogenetic analyses of the retrieved sequences for the other species of Cornus provided information on the relative utility of the cpDNA regions studied and helped delineate the groups (Big-Bracted, Cornelian Cherries, Blue/White-Fruited) within the genus. Genealogical relationships based on the cpDNA sequences and the inferred chlorotype networks indicated the need for continued analyses across further non-coding cpDNA regions to improve the phylogenetic resolution of dogwoods.
Forest tree species are increasingly subject to severe mortalities from exotic pests, diseases, and invasive organisms, accelerated by climate change. Forest health issues are threatening multiple species and ecosystem sustainability globally.
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