Genome-Scale Analysis of Programmed DNA Elimination Sites in Tetrahymena thermophila

Genetically programmed DNA rearrangements can regulate mRNA expression at an individual locus or, for some organisms, on a genome-wide scale. Ciliates rely on a remarkable process of whole-genome remodeling by DNA elimination to differentiate an expressed macronucleus (MAC) from a copy of the germline micronucleus (MIC) in each cycle of sexual reproduction. Here we describe results from the first high-throughput sequencing effort to investigate ciliate genome restructuring, comparing Sanger long-read sequences from a Tetrahymena thermophila MIC genome library to the MAC genome assembly. With almost 25% coverage of the unique-sequence MAC genome by MIC genome sequence reads, we created a resource for positional analysis of MIC-specific DNA removal that pinpoints MAC genome sites of DNA elimination at nucleotide resolution. The widespread distribution of internal eliminated sequences (IES) in promoter regions and introns suggests that MAC genome restructuring is essential not only for what it removes (for example, active transposons) but also for what it creates (for example, splicing-competent introns). Consistent with the heterogeneous boundaries and epigenetically modulated efficiency of individual IES deletions studied to date, we find that IES sites are dramatically under-represented in the ∼25% of the MAC genome encoding exons. As an exception to this general rule, we discovered a previously unknown class of small (<500 bp) IES with precise elimination boundaries that can contribute the 3′ exon of an mRNA expressed during genome restructuring, providing a new mechanism for expanding mRNA complexity in a developmentally regulated manner

Pre-pregnancy predictors of hypertension in pregnancy among Aboriginal and Torres Strait Islander women in north Queensland, Australia; a prospective cohort study

BACKGROUND Compared to other Australian women, Indigenous women are frequently at greater risk for hypertensive disorders of pregnancy. We examined pre-pregnancy factors that may predict hypertension in pregnancy in a cohort of Aboriginal and Torres Strait Islander women in north Queensland. METHODS Data on a cohort of 1009 Indigenous women of childbearing age (15–44 years) who participated in a 1998–2000 health screening program in north Queensland were combined with 1998–2008 Queensland hospitalisations data using probabilistic data linkage. Data on the women in the cohort who were hospitalised for birth (n = 220) were further combined with Queensland perinatal data which identified those diagnosed with hypertension in pregnancy. RESULTS Of 220 women who gave birth, 22 had hypertension in the pregnancy after their health check. The mean age of women with and without hypertension was similar (23.7 years and 23.9 years respectively) however Aboriginal women were more affected compared to Torres Strait Islanders. Pre-pregnancy adiposity and elevated blood pressure at the health screening program were predictors of a pregnancy affected by hypertension. After adjusting for age and ethnicity, each 1 cm increase in waist circumference showed a 4% increased risk for hypertension in pregnancy (PR 1.04; 95% CI; 1.02-1.06); each 1 point increase in BMI showed a 9% adjusted increase in risk (1.09; 1.04-1.14). For each 1 mmHg increase in baseline systolic blood pressure there was an age and ethnicity adjusted 6% increase in risk and each 1 mmHg increase in diastolic blood pressure showed a 7% increase in risk (1.06; 1.03-1.09 and 1.07; 1.03-1.11 respectively). Among those free of diabetes at baseline, the presence of the metabolic syndrome (International Diabetes Federation criteria) predicted over a three-fold increase in age-ethnicity-adjusted risk (3.5; 1.50-8.17). CONCLUSIONS Pre-pregnancy adiposity and features of the metabolic syndrome among these young Aboriginal and Torres Strait Islander women track strongly to increased risk of hypertension in pregnancy with associated risks to the health of babies.Sandra K Campbell, John Lynch, Adrian Esterman and Robyn McDermot

Relation of exaggerated cytokine responses of CF airway epithelial cells to PAO1 adherence

In many model systems, cystic fibrosis (CF) phenotype airway epithelial cells in culture respond to P. aeruginosa with greater interleukin (IL)-8 and IL-6 secretion than matched controls. In order to test whether this excess inflammatory response results from the reported increased adherence of P. aeruginosa to the CF cells, we compared the inflammatory response of matched pairs of CF and non CF airway epithelial cell lines to the binding of GFP-PAO1, a strain of pseudomonas labeled with green fluorescent protein. There was no clear relation between GFP-PAO1 binding and cytokine production in response to PAO1. Treatment with exogenous aGM1 resulted in greater GFP-PAO1 binding to the normal phenotype compared to CF phenotype cells, but cytokine production remained greater from the CF cell lines. When cells were treated with neuraminidase, PAO1 adherence was equalized between CF and nonCF phenotype cell lines, but IL-8 production in response to inflammatory stimuli was still greater in CF phenotype cells. The polarized cell lines 16HBEo-Sense (normal phenotype) and Antisense (CF phenotype) cells were used to test the effect of disrupting tight junctions, which allows access of PAO1 to basolateral binding sites in both cell lines. IL-8 production increased from CF, but not normal, cells. These data indicate that increased bacterial binding to CF phenotype cells cannot by itself account for excess cytokine production in CF airway epithelial cells, encourage investigation of alternative hypotheses, and signal caution for therapeutic strategies proposed for CF that include disruption of tight junctions in the face of pseudomonas infection

Parental experiences of supporting children with clinically significant post-traumatic distress: a qualitative study of families accessing psychological services

The aim of this study was to investigate the experiences of parents in providing support to their child following trauma exposure in cases where children are experiencing clinically significant levels of post-traumatic distress. Qualitative interviews were conducted with parents whose child was exposed to a trauma and referred for psychological treatment. Parents reported considerable anxiety in coping with their child’s post-traumatic distress. Avoidance of trauma-related discussions was encouraged due to concerns that non-avoidant approaches may worsen children’s post-trauma difficulties. Nonetheless, parents were often sensitive to their child’s distress and offered reassurance and other forms of support. Many barriers existed to accessing psychological treatment, and perceptions of inadequate guidance from therapists on supporting child adjustment contributed to parental distress. The results illustrate the strategies used by parents in supporting their child post-trauma and may assist mental health professionals in providing acceptable guidance to parents following child trauma

Premating Reproductive Barriers between Hybridising Cricket Species Differing in Their Degree of Polyandry

Understanding speciation hinges on understanding how reproductive barriers arise between incompletely isolated populations. Despite their crucial role in speciation, prezygotic barriers are relatively poorly understood and hard to predict. We use two closely related cricket species, Gryllus bimaculatus and G. campestris, to experimentally investigate premating barriers during three sequential mate choice steps. Furthermore, we experimentally show a significant difference in polyandry levels between the two species and subsequently test the hypothesis that females of the more polyandrous species, G. bimaculatus, will be less discriminating against heterospecific males and hence hybridise more readily. During close-range mating behaviour experiments, males showed relatively weak species discrimination but females discriminated very strongly. In line with our predictions, this discrimination is asymmetric, with the more polyandrous G. bimaculatus mating heterospecifically and G. campestris females never mating heterospecifically. Our study shows clear differences in the strength of reproductive isolation during the mate choice process depending on sex and species, which may have important consequences for the evolution of reproductive barriers

Factors contributing to posttraumatic growth and its buffering effect in adult chidren of cancer patients undergoing treatment

This study examined relationships among demographic, clinical, and psychosocial variables in adult children of cancer patients. Two hundred and fourteen participants completed measures of posttraumatic growth (PTG), distress, posttraumatic stress disorder (PTSD) symptoms, social support, and family functioning. Significant gender differences in all PTG dimensions were found, as well as associations among PTG, gender, parental dependency, distress, PTSD, and family functioning. Social support was not a mediator in the relationship between gender and PTG. Gender, education, disease duration, dependency, distress, and family flexibility predicted PTG. Finally, PTG had amoderating effect in the relationship between distress and PTSD/social support. These results may guide psychosocial interventions in this population.Fundação para a Ciência e Tecnologia (FCT

Macronuclear Genome Sequence of the Ciliate Tetrahymena thermophila, a Model Eukaryote

The ciliate Tetrahymena thermophila is a model organism for molecular and cellular biology. Like other ciliates, this species has separate germline and soma functions that are embodied by distinct nuclei within a single cell. The germline-like micronucleus (MIC) has its genome held in reserve for sexual reproduction. The soma-like macronucleus (MAC), which possesses a genome processed from that of the MIC, is the center of gene expression and does not directly contribute DNA to sexual progeny. We report here the shotgun sequencing, assembly, and analysis of the MAC genome of T. thermophila, which is approximately 104 Mb in length and composed of approximately 225 chromosomes. Overall, the gene set is robust, with more than 27,000 predicted protein-coding genes, 15,000 of which have strong matches to genes in other organisms. The functional diversity encoded by these genes is substantial and reflects the complexity of processes required for a free-living, predatory, single-celled organism. This is highlighted by the abundance of lineage-specific duplications of genes with predicted roles in sensing and responding to environmental conditions (e.g., kinases), using diverse resources (e.g., proteases and transporters), and generating structural complexity (e.g., kinesins and dyneins). In contrast to the other lineages of alveolates (apicomplexans and dinoflagellates), no compelling evidence could be found for plastid-derived genes in the genome. UGA, the only T. thermophila stop codon, is used in some genes to encode selenocysteine, thus making this organism the first known with the potential to translate all 64 codons in nuclear genes into amino acids. We present genomic evidence supporting the hypothesis that the excision of DNA from the MIC to generate the MAC specifically targets foreign DNA as a form of genome self-defense. The combination of the genome sequence, the functional diversity encoded therein, and the presence of some pathways missing from other model organisms makes T. thermophila an ideal model for functional genomic studies to address biological, biomedical, and biotechnological questions of fundamental importance

Caenorhabditis briggsae Recombinant Inbred Line Genotypes Reveal Inter-Strain Incompatibility and the Evolution of Recombination

The nematode Caenorhabditis briggsae is an emerging model organism that allows evolutionary comparisons with C. elegans and exploration of its own unique biological attributes. To produce a high-resolution C. briggsae recombination map, recombinant inbred lines were generated from reciprocal crosses between two strains and genotyped at over 1,000 loci. A second set of recombinant inbred lines involving a third strain was also genotyped at lower resolution. The resulting recombination maps exhibit discrete domains of high and low recombination, as in C. elegans, indicating these are a general feature of Caenorhabditis species. The proportion of a chromosome's physical size occupied by the central, low-recombination domain is highly correlated between species. However, the C. briggsae intra-species comparison reveals striking variation in the distribution of recombination between domains. Hybrid lines made with the more divergent pair of strains also exhibit pervasive marker transmission ratio distortion, evidence of selection acting on hybrid genotypes. The strongest effect, on chromosome III, is explained by a developmental delay phenotype exhibited by some hybrid F2 animals. In addition, on chromosomes IV and V, cross direction-specific biases towards one parental genotype suggest the existence of cytonuclear epistatic interactions. These interactions are discussed in relation to surprising mitochondrial genome polymorphism in C. briggsae, evidence that the two strains diverged in allopatry, the potential for local adaptation, and the evolution of Dobzhansky-Muller incompatibilities. The genetic and genomic resources resulting from this work will support future efforts to understand inter-strain divergence as well as facilitate studies of gene function, natural variation, and the evolution of recombination in Caenorhabditis nematodes