[Epigenetics and the improvement of crop plants].

Epigenetics is a term that refers to the changes in gene expression that are heritable and induced by DNA methylation, histones post-translational modifications, or sncRNA, not resulting from the DNA sequence rearrangements. Epigenetic modifications influence gene expression, and thus, the plasticity of plants' development and phenotype in response to external and internal factors. Until recently, the only known epigenetic modification of the DNA in eukaryotic organisms was 5-methylcytosine.

Epigenetic Changes Occurring in Plant Inbreeding.

Inbreeding is the crossing of closely related individuals in nature or a plantation or self-pollinating plants, which produces plants with high homozygosity. This process can reduce genetic diversity in the offspring and decrease heterozygosity, whereas inbred depression (ID) can often reduce viability. Inbred depression is common in plants and animals and has played a significant role in evolution.

Global DNA 5-hydroxymethylcytosine level and its chromosomal distribution in four rye species.

The rye genome has a large size with a high level of cytosine methylation, which makes it particularly convenient for studying the occurrence of potential cytosine demethylation intermediates. Levels of global 5-hydroxymethylcytosine (5hmC) were analysed by enzyme-linked immunosorbent assay (ELISA) and mass spectrometry in four rye species: Secale cereale, Secale strictum, Secale sylvestre, and Secale vavilovii. The amount of 5hmC showed interspecific variation, and was also variable among organs, i.

Androgens increase excitatory neurogenic potential in human brain organoids.

The biological basis of male-female brain differences has been difficult to elucidate in humans. The most notable morphological difference is size, with male individuals having on average a larger brain than female individuals, but a mechanistic understanding of how this difference arises remains unknown. Here we use brain organoids to show that although sex chromosomal complement has no observable effect on neurogenesis, sex steroids-namely androgens-lead to increased proliferation of cortical progenitors and an increased neurogenic pool.

The distribution pattern of 5-methylcytosine in rye (Secale L.) chromosomes.

The rye (Secale L.) genome is large, and it contains many classes of repetitive sequences. Secale species differ in terms of genome size, heterochromatin content, and global methylation level; however, the organization of individual types of sequences in chromosomes is relatively similar.

The epigenetic regulation of centromeres and telomeres in plants and animals.

The centromere is a chromosomal region where the kinetochore is formed, which is the attachment point of spindle fibers. Thus, it is responsible for the correct chromosome segregation during cell division. Telomeres protect chromosome ends against enzymatic degradation and fusions, and localize chromosomes in the cell nucleus.

Chromosome numbers of Carex (Cyperaceae) and their taxonomic implications.

Counting chromosomes is the first step towards a better understanding of the karyotype evolution and the role of chromosome evolution in species diversification within Carex; however, the chromosome count is not known yet for numerous sedges. In this paper chromosome counts were performed for 23 Carex taxa from Armenia, Austria, the Czech Republic, and Poland. Chromosome numbers were determined for the first time in three species (Carex cilicica, 2n = 54; C.

The genetics of egg retention and fertilization success in Drosophila: One step closer to understanding the transition from facultative to obligate viviparity.

Oviparous, facultative egg retention enables Drosophila females to withhold fertilized eggs in their reproductive tracts until circumstances favor oviposition. The propensity to retain fertilized eggs varies greatly between species, and is correlated with other reproductive traits, such as egg size and ovariole number. While previous studies have described the phenomenon, no study to date has characterized within-species variation or the genetic basis of the trait.

Reorganization of wheat and rye genomes in octoploid triticale (× Triticosecale).

The analysis of early generations of triticale showed numerous rearrangements of the genome. Complexed transformation included loss of chromosomes, t-heterochromatin content changes and the emergence of retrotransposons in new locations. This study investigated certain aspects of genomic transformations in the early generations (F5 and F8) of the primary octoploid triticale derived from the cross of hexaploid wheat with the diploid rye.

The DNA methylation level against the background of the genome size and t-heterochromatin content in some species of the genus .

Methylation of cytosine in DNA is one of the most important epigenetic modifications in eukaryotes and plays a crucial role in the regulation of gene activity and the maintenance of genomic integrity. DNA methylation and other epigenetic mechanisms affect the development, differentiation or the response of plants to biotic and abiotic stress. This study compared the level of methylation of cytosines on a global (ELISA) and genomic scale (MSAP) between the species of the genus .

Effects of larval crowding on quantitative variation for development time and viability in .

Competition between individuals belonging to the same species is a universal feature of natural populations and is the process underpinning organismal adaptation. Despite its importance, still comparatively little is known about the genetic variation responsible for competitive traits. Here, we measured the phenotypic variation and quantitative genetics parameters for two fitness-related traits-egg-to-adult viability and development time-across a panel of strains under varying larval densities.

Molecular phylogenetics, seed morphometrics, chromosome number evolution and systematics of European L. (Elatinaceae) species.

The genus contains 25 species, all of which are small, herbaceous annuals distributed in ephemeral waters on both hemispheres. However, due to a high degree of morphological variability (as a consequence of their amphibious life-style), the taxonomy of this genus remains controversial. Thus, to fill this gap in knowledge, we present a detailed molecular phylogenetic study of this genus based on nuclear (rITS) and plastid (, , ) sequences using 27 samples from 13 species.

A novel method for quantifying the rate of embryogenesis uncovers considerable genetic variation for the duration of embryonic development in Drosophila melanogaster.

Background: Embryogenesis is a highly conserved, canalized process, and variation in the duration of embryogenesis (DOE), i.e., time from egg lay to hatching, has a potentially profound effect on the outcome of within- and between-species competition.

Comment on "Cortical folding scales universally with surface area and thickness, not number of neurons".

Mota and Herculano-Houzel (Reports, 3 July 2015, p. 74) assign power functions to neuroanatomical data and present a model to account for evolutionary patterns of cortical folding in the mammalian brain. We detail how the model assumptions are in conflict with experimental and observational work and show that the model itself does not accurately fit the data.

How did viviparity originate and evolve? Of conflict, co-option, and cryptic choice.

I propose that the underlying adaptation enabling the reproductive strategy of birthing live young (viviparity) is retraction of the site of fertilization within the female reproductive tract, and that this evolved as a means of postcopulatory sexual selection. There are three conspicuous aspects associated with viviparity: (i) internal development is a complex trait often accompanied by a suite of secondary adaptations, yet it is unclear how the intermediate state of this trait - egg retention - could have evolved; (ii) viviparity often results in a reduction in fecundity; (iii) viviparity has evolved independently many times across a diverse array of animal groups. Focusing on the Diptera (true flies), I provide explanations for these observations.

Systematic imaging reveals features and changing localization of mRNAs in Drosophila development.

mRNA localization is critical for eukaryotic cells and affects numerous transcripts, yet how cells regulate distribution of many mRNAs to their subcellular destinations is still unknown. We combined transcriptomics and systematic imaging to determine the tissue-specific expression and subcellular distribution of 5862 mRNAs during Drosophila oogenesis. mRNA localization is widespread in the ovary and detectable in all of its cell types-the somatic epithelial, the nurse cells, and the oocyte.

An adaptive threshold in mammalian neocortical evolution.

Expansion of the neocortex is a hallmark of human evolution. However, determining which adaptive mechanisms facilitated its expansion remains an open question. Here we show, using the gyrencephaly index (GI) and other physiological and life-history data for 102 mammalian species, that gyrencephaly is an ancestral mammalian trait.

Introns and gene expression: cellular constraints, transcriptional regulation, and evolutionary consequences.

A gene's "expression profile" denotes the number of transcripts present relative to all other transcripts. The overall rate of transcript production is determined by transcription and RNA processing rates. While the speed of elongating RNA polymerase II has been characterized for many different genes and organisms, gene-architectural features - primarily the number and length of exons and introns - have recently emerged as important regulatory players.

Towards an ecological understanding of morphological evolution.

The roots of modern evo-devo can be traced back to the comparative anatomy of the 19th century. Inheriting from this tradition, the field has maintained a mechanistic approach to understanding the origins of distinct animal morphologies. While this focus has produced a valuable body of work, we argue here that a fuller understanding of why species diverge morphologically must be centered on the selective forces driving divergence, and these forces ultimately reside in the ecological context in which organisms live and reproduce.

The earliest transcribed zygotic genes are short, newly evolved, and different across species.

The transition from maternal to zygotic control is fundamental to the life cycle of all multicellular organisms. It is widely believed that genomes are transcriptionally inactive from fertilization until zygotic genome activation (ZGA). Thus, the earliest genes expressed probably support the rapid cell divisions that precede morphogenesis and, if so, might be evolutionarily conserved.

Neocortical development as an evolutionary platform for intragenomic conflict.

Embryonic development in mammals has evolved a platform for genomic conflict between mothers and embryos and, by extension, between maternal and paternal genomes. The evolutionary interests of the mother and embryo may be maximized through the promotion of sex-chromosome genes and imprinted alleles, resulting in the rapid evolution of postzygotic phenotypes preferential to either the maternal or paternal genome. In eutherian mammals, extraordinary in utero maternal investment in the brain, and neocortex especially, suggests that convergent evolution of an expanded mammalian neocortex along divergent lineages may be explained, in part, by parent-of-origin-linked gene expression arising from parent-offspring conflict.

An excess of gene expression divergence on the X chromosome in Drosophila embryos: implications for the faster-X hypothesis.

The X chromosome is present as a single copy in the heterogametic sex, and this hemizygosity is expected to drive unusual patterns of evolution on the X relative to the autosomes. For example, the hemizgosity of the X may lead to a lower chromosomal effective population size compared to the autosomes, suggesting that the X might be more strongly affected by genetic drift. However, the X may also experience stronger positive selection than the autosomes, because recessive beneficial mutations will be more visible to selection on the X where they will spend less time being masked by the dominant, less beneficial allele--a proposal known as the faster-X hypothesis.

Evidence of community structure in biomedical research grant collaborations.

Recent studies have clearly demonstrated a shift towards collaborative research and team science approaches across a spectrum of disciplines. Such collaborative efforts have also been acknowledged and nurtured by popular extramurally funded programs including the Clinical Translational Science Award (CTSA) conferred by the National Institutes of Health. Since its inception, the number of CTSA awardees has steadily increased to 60 institutes across 30 states.

The evolution of early animal embryos: conservation or divergence?

There is a remarkable similarity in the appearance of groups of animal species during periods of their embryonic development. This classic observation has long been viewed as an emphatic realization of the principle of common descent. Despite the importance of embryonic conservation as a unifying concept, models seeking to predict and explain different patterns of conservation have remained in contention.