Simultaneous genetic transformation and genome editing of mixed lines in soybean () and maize ().

Unlabelled: Robust genome editing technologies are becoming part of the crop breeding toolbox. Currently, genome editing is usually conducted either at a single locus, or multiple loci, in a variety at one time. Massively parallel genomics platforms, multifaceted genome editing capabilities, and flexible transformation systems enable targeted variation at nearly any locus, across the spectrum of genotypes within a species.

Tuning of meristem maturation rate increases yield in multiple cultivars.

Breeding programs aim to improve crop yield and environmental stability for enhanced food security. The principal methodology in breeding for stable yield gain relies on the indirect selection of beneficial genetics by yield evaluation across diverse environmental conditions. This methodology requires substantial resources while delivering a slow pace of yield gain and environmental adaptation.

Functional diversification of maize RNA polymerase IV and V subtypes via alternative catalytic subunits.

Unlike nuclear multisubunit RNA polymerases I, II, and III, whose subunit compositions are conserved throughout eukaryotes, plant RNA polymerases IV and V are nonessential, Pol II-related enzymes whose subunit compositions are still evolving. Whereas Arabidopsis Pols IV and V differ from Pol II in four or five of their 12 subunits, respectively, and differ from one another in three subunits, proteomic analyses show that maize Pols IV and V differ from Pol II in six subunits but differ from each other only in their largest subunits. Use of alternative catalytic second subunits, which are nonredundant for development and paramutation, yields at least two subtypes of Pol IV and three subtypes of Pol V in maize.

Safety assessment of food and feed from biotechnology-derived crops employing RNA-mediated gene regulation to achieve desired traits: a scientific review.

Gene expression can be modulated in plants to produce desired traits through agricultural biotechnology. Currently, biotechnology-derived crops are compared to their conventional counterparts, with safety assessments conducted on the genetic modification and the intended and unintended differences. This review proposes that this comparative safety assessment paradigm is appropriate for plants modified to express mediators of RNA-mediated gene regulation, including RNA interference (RNAi), a gene suppression mechanism that naturally occurs in plants and animals.

Multiple SET methyltransferases are required to maintain normal heterochromatin domains in the genome of Drosophila melanogaster.

Methylation of histone H3 lysine 9 (H3K9) is a key feature of silent chromatin and plays an important role in stabilizing the interaction of heterochromatin protein 1 (HP1) with chromatin. Genomes of metazoans such as the fruit fly Drosophila melanogaster generally encode three types of H3K9-specific SET domain methyltransferases that contribute to chromatin homeostasis during the life cycle of the organism. SU(VAR)3-9, dG9a, and dSETDB1 all function in the generation of wild-type H3K9 methylation levels in the Drosophila genome.

In vitro specificities of Arabidopsis co-activator histone acetyltransferases: implications for histone hyperacetylation in gene activation.

In genetic hybrids displaying nucleolar dominance, acetylation of lysines 5, 8, 12 and 16 of histone H4 (H4K5, H4K8, H4K12, H4K16) and acetylation of histone H3 on lysines 9 and 14 (H3K9, H3K14) occurs at the promoters of active ribosomal RNA (rRNA) genes, whereas silenced rRNA genes are deacetylated. Likewise, histone hyperacetylation correlates with the active state of transgenes and of endogenous plant genes involved in physiological processes, including cold tolerance, light-responsiveness and flowering. To investigate histone hyperacetylation dynamics we used sodium butyrate, a histone deacetylase inhibitor known to switch silent rRNA genes on, in order to enrich the pool of acetylated histones.

Drosophila PIWI associates with chromatin and interacts directly with HP1a.

The interface between cellular systems involving small noncoding RNAs and epigenetic change remains largely unexplored in metazoans. RNA-induced silencing systems have the potential to target particular regions of the genome for epigenetic change by locating specific sequences and recruiting chromatin modifiers. Noting that several genes encoding RNA silencing components have been implicated in epigenetic regulation in Drosophila, we sought a direct link between the RNA silencing system and heterochromatin components.

The contradictory definitions of heterochromatin: transcription and silencing.

Eukaryotic genomes are packaged in two general varieties of chromatin: gene-rich euchromatin and gene-poor heterochromatin. Each type of chromatin has been defined by the presence of distinct chromosomal proteins and posttranslational histone modifications. This review addresses recent findings that appear to blur the definitions of euchromatin and heterochromatin by pointing to the presence of typically heterochromatic modifications (including H3K9me) in euchromatin and typically euchromatic enzymes (including RNA polymerases) in heterochromatin.

Cloning and expression of type III collagen in normal and injured tendons of horses.

Objective: To clone the 5' end of type III collagen and describe its pattern of mRNA and protein expression in normal and healing tendons in horses.

Animals: 14 healthy adult horses.

Procedure: The tensile region of collagenase-injured superficial digital flexor tendons was harvested at intervals from 1 to 24 weeks after injury.

Specific contributions of histone tails and their acetylation to the mechanical stability of nucleosomes.

The distinct contributions of histone tails and their acetylation to nucleosomal stability were examined by mechanical disruption of individual nucleosomes in a single chromatin fiber using an optical trap. Enzymatic removal of H2A/H2B tails primarily decreased the strength of histone-DNA interactions located approximately +/-36bp from the dyad axis of symmetry (off-dyad strong interactions), whereas removal of the H3/H4 tails played a greater role in regulating the total amount of DNA bound. Similarly, nucleosomes composed of histones acetylated to different degrees by the histone acetyltransferase p300 exhibited significant decreases in the off-dyad strong interactions and the total amount of DNA bound.

Parathyroid hormone-related peptide and indian hedgehog expression patterns in naturally acquired equine osteochondrosis.

Early changes in parathyroid hormone-related peptide (PTH-rP) and Indian hedgehog (Ihh) expression were examined in equine articular osteochondrosis (OC) as a model of a naturally acquired dyschondroplasia. Cartilage was harvested from OC-affected femoropatellar or scapulohumeral joints from immature horses and normal control horses of similar age. PTH-rP expression levels were assessed by semi-quantitative PCR, in situ hybridization, and immunohistochemistry.

Mechanical disruption of individual nucleosomes reveals a reversible multistage release of DNA.

The dynamic structure of individual nucleosomes was examined by stretching nucleosomal arrays with a feedback-enhanced optical trap. Forced disassembly of each nucleosome occurred in three stages. Analysis of the data using a simple worm-like chain model yields 76 bp of DNA released from the histone core at low stretching force.