Jack of all trades versus master of one: how generalist versus specialist strategies of transposable elements relate to their horizontal transfer between lineages.

Transposable elements (TEs) are obligate genomic parasites, relying on host germline cells to ensure their replication and passage to future generations. While some TEs exhibit high fidelity to their host genome, being passed from parent to offspring through vertical transmission for millions of years, others frequently invade new and distantly related hosts through horizontal transfer. In this review, I highlight how the complexity of interactions between TE and host required for transposition may be an important determinant of horizontal transfer: with TEs with more complex regulatory requirements being less able to invade new host genomes.

P-element invasion fuels molecular adaptation in laboratory populations of Drosophila melanogaster.

Transposable elements (TEs) are mobile genetic parasites that frequently invade new host genomes through horizontal transfer. Invading TEs often exhibit a burst of transposition, followed by reduced transposition rates as repression evolves in the host. We recreated the horizontal transfer of P-element DNA transposons into a Drosophila melanogaster host and followed the expansion of TE copies and evolution of host repression in replicate laboratory populations reared at different temperatures.

Protein-Protein Interactions Shape Genomic Autoimmunity in the Adaptively Evolving Rhino-Deadlock-Cutoff Complex.

The Piwi-interacting RNA (piRNA) pathway is a genomic defense system that controls the movement of transposable elements (TEs) through transcriptional and post-transcriptional silencing. Although TE defense is critical to ensuring germline genome integrity, it is equally critical that the piRNA pathway avoids autoimmunity in the form of silencing host genes. Ongoing cycles of selection for expanded control of invading TEs, followed by selection for increased specificity to reduce impacts on host genes, are proposed to explain the frequent signatures of adaptive evolution among piRNA pathway proteins.

Lyme disease presenting as persistent severe photophobia.

Long-term photophobia in children that has no obvious cause is uncommon and presents a diagnostic dilemma. It may produce significant discomfort and result in social isolation and school absence. We present the case of a 5-year-old boy who presented with chronic photophobia due to interstitial keratitis that was the result of Lyme disease.

Social Media Use Among Young Adults With Connective Tissue Disorders: Cross-Sectional Pilot Study.

Background: Young people with genetic conditions often face challenges coping with their health condition. It can be difficult for them to meet someone with a similar condition, which is important for reinforcement of chronic illness management recommendations. Social media is used by 97% of young people in the United States and may provide those with these disorders a space for emotional expression and support.

Hot Topics in Social Media and Reproductive Health.

Today's generation of adolescents and young adults have been labeled "digital natives" given that they have had access to digital technology since birth. In this review, we address 2 critical areas affecting adolescents' reproductive health and social media. First, we address the current state of the science across several "hot topic" areas of social media use, including body image and privacy concerns.

Adaptive evolution among cytoplasmic piRNA proteins leads to decreased genomic auto-immunity.

In metazoan germlines, the piRNA pathway acts as a genomic immune system, employing small RNA-mediated silencing to defend host DNA from the harmful effects of transposable elements (TEs). Expression of genomic TEs is proposed to initiate self regulation by increasing the production of repressive piRNAs, thereby "adapting" piRNA-mediated control to the most active TE families. Surprisingly, however, piRNA pathway proteins, which execute piRNA biogenesis and enforce silencing of targeted sequences, evolve rapidly and adaptively in animals.

Taming the Turmoil Within: New Insights on the Containment of Transposable Elements.

Transposable elements (TEs) are mobile genetic parasites that can exponentially increase their genomic abundance through self-propagation. Classic theoretical papers highlighted the importance of two potentially escalating forces that oppose TE spread: regulated transposition and purifying selection. Here, we review new insights into mechanisms of TE regulation and purifying selection, which reveal the remarkable foresight of these theoretical models.

Rapid evolution of piRNA-mediated silencing of an invading transposable element was driven by abundant de novo mutations.

The regulation of transposable element (TE) activity by small RNAs is a ubiquitous feature of germlines. However, despite the obvious benefits to the host in terms of ensuring the production of viable gametes and maintaining the integrity of the genomes they carry, it remains controversial whether TE regulation evolves adaptively. We examined the emergence and evolutionary dynamics of repressor alleles after -elements invaded the genome in the mid-twentieth century.

Uninvited guests: how transposable elements take advantage of Drosophila germline stem cells, and how stem cells fight back.

Transposable elements (TEs) are mobile genetic parasites that spread through host genomes by replicating in germline cells. New TE copies that arise in the genomes of germline stem cells (GSCs) are of particular value, because they are potentially transmitted to multiple offspring through the plethora of gametes arising from the same progenitor GSC. However, the fidelity of GSC genomes is also of utmost importance to the host in ensuring the production of abundant and fit offspring.

QTL mapping of natural variation reveals that the developmental regulator bruno reduces tolerance to P-element transposition in the Drosophila female germline.

Transposable elements (TEs) are obligate genetic parasites that propagate in host genomes by replicating in germline nuclei, thereby ensuring transmission to offspring. This selfish replication not only produces deleterious mutations-in extreme cases, TE mobilization induces genotoxic stress that prohibits the production of viable gametes. Host genomes could reduce these fitness effects in two ways: resistance and tolerance.

The Evolution of Small-RNA-Mediated Silencing of an Invading Transposable Element.

Transposable elements (TEs) are genomic parasites that impose fitness costs on their hosts by producing deleterious mutations and disrupting gametogenesis. Host genomes avoid these costs by regulating TE activity, particularly in germline cells where new insertions are heritable and TEs are exceptionally active. However, the capacity of different TE-associated fitness costs to select for repression in the host, and the role of selection in the evolution of TE regulation more generally remain controversial.

Recruitment of Participants and Delivery of Online Mental Health Resources for Depressed Individuals Using Tumblr: Pilot Randomized Control Trial.

Background: Adolescents and young adults frequently post depression symptom references on social media; previous studies show positive associations between depression posts and self-reported depression symptoms. Depression is common among young people and this population often experiences many barriers to mental health care. Thus, social media may be a new resource to identify, recruit, and intervene with young people at risk for depression.

p53 is required for female germline stem cell maintenance in P-element hybrid dysgenesis.

Hybrid dysgenesis is a sterility syndrome resulting from the mobilization of certain transposable elements in the Drosophila germline. Particularly extreme is the hybrid dysgenesis syndrome caused by P-element DNA transposons, in which dysgenic female ovaries often contain few or no germline cells. Those offspring that are produced from dysgenic germlines exhibit high rates of de novo mutation and recombination, implicating transposition-associated DNA damage as the cause of germline loss.

Retrotransposons: Stowaways in the Primordial Germline.

In order to succeed, retrotransposon transcripts must identify the subset of nuclei that will be transmitted to offspring. A new study reveals that the primordial germline is a hideout for retrotransposon transcripts, providing early access to future gametes.

Targeted identification of TE insertions in a genome through hemi-specific PCR.

Background: Transposable elements (TEs) are major components of eukaryotic genomes and drivers of genome evolution, producing intraspecific polymorphism and interspecific differences through mobilization and non-homologous recombination. TE insertion sites are often highly variable within species, creating a need for targeted genome re-sequencing (TGS) methods to identify TE insertion sites.

Methods: We present a hemi-specific PCR approach for TGS of -elements in genomes on the Illumina platform.

Paternal Induction of Hybrid Dysgenesis in Is Weakly Correlated with Both -Element and Element Dosage.

Transposable elements (TEs) are virtually ubiquitous components of genomes, yet they often impose significant fitness consequences on their hosts. In addition to producing specific deleterious mutations by insertional inactivation, TEs also impose general fitness costs by inducing DNA damage and participating in ectopic recombination. These latter fitness costs are often assumed to be dosage-dependent, with stronger effects occurring in the presence of higher TE copy numbers.

Reexamining the P-Element Invasion of Drosophila melanogaster Through the Lens of piRNA Silencing.

Transposable elements (TEs) are both important drivers of genome evolution and genetic parasites with potentially dramatic consequences for host fitness. The recent explosion of research on regulatory RNAs reveals that small RNA-mediated silencing is a conserved genetic mechanism through which hosts repress TE activity. The invasion of the Drosophila melanogaster genome by P elements, which happened on a historical timescale, represents an incomparable opportunity to understand how small RNA-mediated silencing of TEs evolves.

Marfan syndrome patient experiences as ascertained through postings on social media sites.

Marfan syndrome (MS) is a connective tissue disorder that affects thousands of adolescents [Population Reference Bureau, 2013]. Some adolescent patients with MS may use social media to express their experiences and emotions, but little is known about what patients choose to share online. To investigate social media content related to Marfan syndrome we used search terms "Marfan syndrome" and "Marfans" on six different social media sites.

Young adult females' views regarding online privacy protection at two time points.

Purpose: Risks associated with adolescent Internet use include exposure to inappropriate information and privacy violations. Privacy expectations and policies have changed over time. Recent Facebook security setting changes heighten these risks.

Analysis of piRNA-mediated silencing of active TEs in Drosophila melanogaster suggests limits on the evolution of host genome defense.

The Piwi-interacting RNA (piRNA) pathway defends animal genomes against the harmful consequences of transposable element (TE) infection by imposing small-RNA-mediated silencing. Because silencing is targeted by TE-derived piRNAs, piRNA production is posited to be central to the evolution of genome defense. We harnessed genomic data sets from Drosophila melanogaster, including genome-wide measures of piRNA, mRNA, and genomic abundance, along with estimates of age structure and risk of ectopic recombination, to address fundamental questions about the functional and evolutionary relationships between TE families and their regulatory piRNAs.

Drosophila interspecific hybrids phenocopy piRNA-pathway mutants.

The Piwi-interacting RNA (piRNA) pathway defends the germline of animals from the deleterious activity of selfish transposable elements (TEs) through small-RNA mediated silencing. Adaptation to novel invasive TEs is proposed to occur by incorporating their sequences into the piRNA pool that females produce and deposit into their eggs, which then propagates immunity against specific TEs to future generations. In support of this model, the F1 offspring of crosses between strains of the same Drosophila species sometimes suffer from germline derepression of paternally inherited TE families, caused by a failure of the maternal strain to produce the piRNAs necessary for their regulation.

Postmating transcriptional changes in reproductive tracts of con- and heterospecifically mated Drosophila mojavensis females.

In internally fertilizing organisms, mating involves a series of highly coordinated molecular interactions between the sexes that occur within the female reproductive tract. In species where females mate multiply, traits involved in postcopulatory interactions are expected to evolve rapidly, potentially leading to postmating-prezygotic (PMPZ) reproductive isolation between diverging populations. Here, we investigate the postmating transcriptional response of the lower reproductive tract of Drosophila mojavensis females following copulation with either conspecific or heterospecific (Drosophila arizonae) males at three time points postmating.