The fate of Arabidopsis thaliana homeologous CNSs and their motifs in the Paleohexaploid Brassica rapa.

Following polyploidy, duplicate genes are often deleted, and if they are not, then duplicate regulatory regions are sometimes lost. By what mechanism is this loss and what is the chance that such a loss removes function? To explore these questions, we followed individual Arabidopsis thaliana-A. thaliana conserved noncoding sequences (CNSs) into the Brassica ancestor, through a paleohexaploidy and into Brassica rapa. Thus, a single Brassicaceae CNS has six potential orthologous positions in B. rapa; a single Arabidopsis CNS has three potential homeologous positions. We reasoned that a CNS, if present on a singlet Brassica gene, would be unlikely to lose function compared with a more redundant CNS, and this is the case. Redundant CNSs go nondetectable often. Using this logic, each mechanism of CNS loss was assigned a metric of functionality. By definition, proved deletions do not function as sequence. Our results indicated that CNSs that go nondetectable by base substitution or large insertion are almost certainly still functional (redundancy does not matter much to their detectability frequency), whereas those lost by inferred deletion or indels are approximately 75% likely to be nonfunctional. Overall, an average nondetectable, once-redundant CNS more than 30 bp in length has a 72% chance of being nonfunctional, and that makes sense because 97% of them sort to a molecular mechanism with deletion in its description, but base substitutions do cause loss. Similarly, proved-functional G-boxes go undetectable by deletion 82% of the time. Fractionation mutagenesis is a procedure that uses polyploidy as a mutagenic agent to genetically alter RNA expression profiles, and then to construct testable hypotheses as to the function of the lost regulatory site. We show fractionation mutagenesis to be a deletion machine in the Brassica lineage

Functional interplay between chromatin remodeling complexes RSC, SWI/SNF and ISWI in regulation of yeast heat shock genes

Chromatin remodeling is an essential part of transcription initiation. We show that at heat shock gene promoters functional interactions between individual ATP-dependent chromatin remodeling complexes play critical role in both nucleosome displacement and Pol II recruitment. Using HSP12, HSP82 and SSA4 gene promoters as reporters, we demonstrated that while inactivation of SNF2, a critical ATPase of the SWI/SNF complex, primarily affects the HSP12 promoter, depletion of STH1- a SNF2 homolog from the RSC complex reduces histone displacement and abolishes the Pol II recruitment at all three promoters. From these results, we conclude that redundancy between SWI/SNF and RSC complexes is only partial and likely is affecting different chromatin remodeling steps. While inactivation of other individual ATP-dependent chromatin remodeling complexes negligibly affects reporter promoters, combinatorial inactivation of SNF2 and ISW1 has a synergistic effect by diminishing histone loss during heat induction and eliminating Pol II recruitment. Importantly, it also eliminates preloading of HSF on HSP82 and SSA4 promoters before heat shock and diminishes HSF binding during heat shock. These observations suggest that prior action of chromatin remodeling complexes is necessary for the activator binding

Somatically heritable switches in the DNA modification of Mu transposable elements monitored with a suppressible mutant in maize

Many transposable elements in maize alternate between active and inactive phases associated with the modification of their DNA. Elements in an inactive phase lose their ability to transpose, their ability to excise from reporter alleles and, in some cases, their ability to enhance or suppress mutant phenotypes caused by their insertion. The maize mutant hcf106 is a recessive pale green seedling lethal caused by the insertion of the transposable element Mu1. We show that the hcf106 mutant phenotype is suppressed in lines that have lost Mu activity. That is, homozygous hcf106 seedlings are dark green and viable when transposable elements belonging to the Robertson's Mutator family are modified in their terminal inverted repeats, a diagnostic feature of inactive lines. This property of the mutant phenotype has been used to follow clonal leaf sectors containing modified Mu elements that arise from single somatic cells during plant development. The distribution of these sectors indicates that epigenetic switches involving Mu DNA modification occur progressively as the meristem ages

The Relationship of Macronutrient Intake with Growth in Children with Type 1 Diabetes Mellitus

Child growth, a sensitive metric of overall health, results from the intricate interplay of nature and nurture. While the importance of nutrition in child growth is well established, growth trajectories exhibit substantial individual variability, influenced by sex and age, and often characterized by nonlinear patterns. Inadequate nutrition or disease can hinder growth, with potential for recovery upon proper nutrition or acute disease resolution. However, chronic disease or persistent malnutrition may lead to permanent growth perturbation. Notably, before the advent of insulin, chronic stunting and wasting were hallmarks of Type 1 diabetes mellitus (T1DM), though the specific impacts under modern standard of care remain incompletely understood. The three primary macronutrients—protein, carbohydrate, and fat—contribute to growth by supplying calories for total energy. Among healthy children, the roles of each macronutrient in physical growth are well-defined. Dietary protein uniquely supports linear and somatic growth through its dual energy-yielding and nitrogen-obtaining properties. Fatty acids from dietary fat are essential for neurological growth and development. Conversely, any direct role of dietary carbohydrate in growth beyond energy provision is minimal. Whether these macronutrient roles are altered in the presence of T1DM remains unclear. Additionally, recommendations for macronutrient distribution in children, as defined by the Acceptable Macronutrient Distribution Range (AMDR), were primarily extrapolated from adults and not tailored for diseased populations. This dissertation first provides context by examining the relationship between macronutrient intake and height growth in healthy children. Subsequent chapters explore growth and nutrition in children with T1DM undergoing standard insulin therapy. Longitudinal descriptive analyses, utilizing nonlinear mixed effects modeling, revealed that these children may experience earlier puberty onset and achieve taller final adult heights compared to their non-T1DM peers. Nutritional Geometry (NG) was applied to uncover disease-, sex-, and age-specific relationships between macronutrient distribution and physical height growth. Findings suggest a significant positive main effect association between fat intake and maximal height in boys, but not girls. However, no relationships with z-height were observed in boys or girls, suggesting macronutrient distribution is unrelated to normal growth in this population. The findings underscore NG\u27s potential to inform disease-specific AMDR recommendations for optimal child growth

Origin and evolution of the octoploid strawberry genome.

Cultivated strawberry emerged from the hybridization of two wild octoploid species, both descendants from the merger of four diploid progenitor species into a single nucleus more than 1 million years ago. Here we report a near-complete chromosome-scale assembly for cultivated octoploid strawberry (Fragaria × ananassa) and uncovered the origin and evolutionary processes that shaped this complex allopolyploid. We identified the extant relatives of each diploid progenitor species and provide support for the North American origin of octoploid strawberry. We examined the dynamics among the four subgenomes in octoploid strawberry and uncovered the presence of a single dominant subgenome with significantly greater gene content, gene expression abundance, and biased exchanges between homoeologous chromosomes, as compared with the other subgenomes. Pathway analysis showed that certain metabolomic and disease-resistance traits are largely controlled by the dominant subgenome. These findings and the reference genome should serve as a powerful platform for future evolutionary studies and enable molecular breeding in strawberry

Genes Identified by Visible Mutant Phenotypes Show Increased Bias toward One of Two Subgenomes of Maize

Not all genes are created equal. Despite being supported by sequence conservation and expression data, knockout homozygotes of many genes show no visible effects, at least under laboratory conditions. We have identified a set of maize (Zea mays L.) genes which have been the subject of a disproportionate share of publications recorded at MaizeGDB. We manually anchored these “classical” maize genes to gene models in the B73 reference genome, and identified syntenic orthologs in other grass genomes. In addition to proofing the most recent version 2 maize gene models, we show that a subset of these genes, those that were identified by morphological phenotype prior to cloning, are retained at syntenic locations throughout the grasses at much higher levels than the average expressed maize gene, and are preferentially found on the maize1 subgenome even with a duplicate copy is still retained on the opposite subgenome. Maize1 is the subgenome that experienced less gene loss following the whole genome duplication in maize lineage 5–12 million years ago and genes located on this subgenome tend to be expressed at higher levels in modern maize. Links to the web based software that supported our syntenic analyses in the grasses should empower further research and support teaching involving the history of maize genetic research. Our findings exemplify the concept of “grasses as a single genetic system,” where what is learned in one grass may be applied to another