Investigation of sex change, sex differentiation and stress responses in black seabass (Centropristis striata)

Black sea bass (Centropristis striata) have been the focus of research as an aquaculture species for several years due to their high consumer demand and limited seasonable availability. As protogynous hermaphrodites, black sea bass initially develop as females in the wild, and undergo sex reversal between 2 and 6 years of age. Previous studies demonstrated that in captivity, however, a significant number of fish differentiate initially as males, and sex reversal is hastened in females. Full control of reproduction is required for successful commercial culture. Since captive environments pose several sources of stress upon the cultured species, this research investigates stress and effects upon sex differentiation and sex change in black sea bass. The first study measured production of the stress hormone cortisol relative to stocking density, a common source of stress in the culture environment. Black sea bass juveniles were held in high (3.66g fish/L), medium (2.56g fish/L), low (1.4g fish/L) densities, in triplicate for 84 days, after which blood was collected for cortisol radioimmunoassay. Fish in the highest density treatment were found to have significantly (p=0.0003Wilcoxon/Kruskal-Wallis Test) lower plasma cortisol concentrations (0.419ng/ml) than those in the medium (3.243ng/ml) and low-density (3.232ng/m1) groups. Higher cortisol levels may have resulted from fish maintaining and defending territories in the lower density treatments. The second study investigates the process of sex change in adult black sea bass and interactions caused by either an acute physical stressor or exogenously administered cortisol. A preliminary trial measured plasma cortisol at 6 time points (0, 1, 6, 12, 24, 48 hours) after an acute stressor or exogenous application of cortisol through an infused feed. Both trials showed plasma cortisol peaks at 6 hours post feed/stressor. To assess effects upon sex change adult fish in triplicate tanks were fed a cortisol-infused diet (100 mg/kg feed), exposed to an acute stressor (net chasing, 30 seconds), or fed a control diet and not exposed to an acute stressor (control). After 84 days, blood was drawn for cortisol radioimmunoassay and sex was assessed by ovarian biopsy, abdominal massage or gonadal histology. A greater number of females in the cortisol-fed (30%) and chased (28%) treatments underwent sex change compared to those in the control groups (11%), but treatment effects were not significant (p=0.5089 One-Way ANOVA) due to small sample sizes. Although not statistically significant, these results would still be functionally significant in an aquaculture setting. The third study investigated the effect of exogenously administered cortisol upon sex differentiation in juvenile black sea bass. Fish (n=270) were distributed among 9 151L aquaria (30 fish per tank) and fed a cortisol infused diet (control: 0 mg /kg, high: 100 mg /kg, low :10 mg/kg) daily to apparent satiation. After 175, 189 and 217 days in treatment individuals were euthanized and gonads removed for histology to determine sex. Fish which differentiated as female represented 51.85%, 79.19%, and 17.84% of the control, low and high treatments respectively (p=0.0007, One-Way Analysis of Variance, Tukey\u27s Test). Fully differentiated spermatozoa or spermiation was detected in 36.4%, 16.7% and 56.5% of the control, low and high treatments fish, respectively. The low treatment average length (13.64cm) and weight (39.93g) was significantly higher (Length: p=\u3c0.0001, Weight: p=0.0002, One-Way Analysis of Variance, Tukey\u27s Test). The precocious puberty and affected growth and may be linked to previously unperceived stressors in the culture environment. This research will increase our understanding of the physiological processes of black sea bass and help to advance successful commercial propagation

Enantioselective Construction of Acyclic Quaternary Carbon Stereocenters: Palladium-Catalyzed Decarboxylative Allylic Alkylation of Fully-Substituted Amide Enolates

We report a divergent and modular protocol for the preparation of acyclic molecular frameworks containing newly created quaternary carbon stereocenters. Central to this approach is a sequence composed of a (1) regioselective and -retentive preparation of allyloxycarbonyl-trapped fully substituted stereodefined amide enolates and of a (2) enantioselective palladium-catalyzed decarboxylative allylic alkylation reaction using a novel bisphosphine ligand

Probing Trends in Enantioinduction via Substrate Design: Palladium-Catalyzed Decarboxylative Allylic Alkylation of α-Enaminones

Herein, we report the palladium-catalyzed decarboxylative asymmetric allylic alkylation of α-enaminones. In addition to serving as valuable synthetic building blocks, we exploit the α-enaminone scaffold and its derivatives as probes to highlight structural and electronic factors that govern enantioselectivity in this asymmetric alkylation reaction. Utilizing the (S)-t-BuPHOX ligand in a variety of nonpolar solvents, the alkylated products are obtained in up to 99% yield and 99% enantiomeric excess

Expanding Insight into Asymmetric Palladium-Catalyzed Allylic Alkylation of N-Heterocyclic Molecules and Cyclic Ketones

Eeny, meeny, miny … enaminones! Lactams and imides have been shown to consistently provide enantioselectivities substantially higher than other substrate classes previously investigated in the palladium-catalyzed asymmetric decarboxylative allylic alkylation. Several new substrates have been designed to probe the contributions of electronic, steric, and stereoelectronic factors that distinguish the lactam/imide series as superior alkylation substrates (see scheme). These studies culminated in marked improvements on carbocyclic allylic alkylation substrates

An Efficient Protocol for the Palladium-Catalyzed Asymmetric Decarboxylative Allylic Alkylation Using Low Palladium Concentrations and a Palladium(II) Precatalyst

Enantioselective catalytic allylic alkylation for the synthesis of 2-alkyl-2-allylcycloalkanones and 3,3-disubstituted pyrrolidinones, piperidinones and piperazinones has been previously reported by our laboratory. The efficient construction of chiral all-carbon quaternary centers by allylic alkylation was previously achieved with a catalyst derived in situ from zero-valent palladium sources and chiral phosphinooxazoline (PHOX) ligands. We now report an improved reaction protocol with broad applicability among different substrate classes in industry-compatible reaction media using loadings of palladium(II) acetate as low as 0.075 mol% and the readily available chiral PHOX ligands. The novel and highly efficient procedure enables facile scale-up of the reaction in an economical and sustainable fashion

G4 motifs correlate with promoter-proximal transcriptional pausing in human genes

The RNA Pol II transcription complex pauses just downstream of the promoter in a significant fraction of human genes. The local features of genomic structure that contribute to pausing have not been defined. Here, we show that genes that pause are more G-rich within the region flanking the transcription start site (TSS) than RefSeq genes or non-paused genes. We show that enrichment of binding motifs for common transcription factors, such as SP1, may account for G-richness upstream but not downstream of the TSS. We further show that pausing correlates with the presence of a GrIn1 element, an element bearing one or more G4 motifs at the 5′-end of the first intron, on the non-template DNA strand. These results suggest potential roles for dynamic G4 DNA and G4 RNA structures in cis-regulation of pausing, and thus genome-wide regulation of gene expression, in human cells

Quantitative model of R-loop forming structures reveals a novel level of RNA–DNA interactome complexity

R-loop is the structure co-transcriptionally formed between nascent RNA transcript and DNA template, leaving the non-transcribed DNA strand unpaired. This structure can be involved in the hyper-mutation and dsDNA breaks in mammalian immunoglobulin (Ig) genes, oncogenes and neurodegenerative disease related genes. R-loops have not been studied at the genome scale yet. To identify the R-loops, we developed a computational algorithm and mapped R-loop forming sequences (RLFS) onto 66 803 sequences defined by UCSC as ‘known’ genes. We found that ∼59% of these transcribed sequences contain at least one RLFS. We created R-loopDB (http://rloop.bii.a-star.edu.sg/), the database that collects all RLFS identified within over half of the human genes and links to the UCSC Genome Browser for information integration and visualisation across a variety of bioinformatics sources. We found that many oncogenes and tumour suppressors (e.g. Tp53, BRCA1, BRCA2, Kras and Ptprd) and neurodegenerative diseases related genes (e.g. ATM, Park2, Ptprd and GLDC) could be prone to significant R-loop formation. Our findings suggest that R-loops provide a novel level of RNA–DNA interactome complexity, playing key roles in gene expression controls, mutagenesis, recombination process, chromosomal rearrangement, alternative splicing, DNA-editing and epigenetic modifications. RLFSs could be used as a novel source of prospective therapeutic targets

Using a state cancer registry to recruit young breast cancer survivors and high-risk relatives: protocol of a randomized trial testing the efficacy of a targeted versus a tailored intervention to increase breast cancer screening

Abstract Background The Michigan Prevention Research Center, the University of Michigan Schools of Nursing, Public Health, and Medicine, and the Michigan Department of Community Health propose a multidisciplinary academic-clinical practice three-year project to increase breast cancer screening among young breast cancer survivors and their cancer-free female relatives at greatest risk for breast cancer. Methods/design The study has three specific aims: 1) Identify and survey 3,000 young breast cancer survivors (diagnosed at 20–45 years old) regarding their breast cancer screening utilization. 2) Identify and survey survivors’ high-risk relatives regarding their breast cancer screening utilization. 3) Test two versions (Targeted vs. Enhanced Tailored) of an intervention to increase breast cancer screening among survivors and relatives. Following approval by human subjects review boards, 3,000 young breast cancer survivors will be identified through the Michigan Cancer Registry and mailed an invitation letter and a baseline survey. The baseline survey will obtain information on the survivors’: a) current breast cancer screening status and use of genetic counseling; b) perceived barriers and facilitators to screening; c) family health history. Based on the family history information provided by survivors, we will identify up to two high-risk relatives per survivor. Young breast cancer survivors will be mailed consent forms and baseline surveys to distribute to their selected high-risk relatives. Relatives’ baseline survey will obtain information on their: a) current breast cancer screening status and use of genetic counseling; and b) perceived barriers and facilitators to screening. Young breast cancer survivors and high-risk relatives will be randomized as a family unit to receive two versions of an intervention aiming to increase breast cancer screening and use of cancer genetic services. A follow-up survey will be mailed 9 months after the intervention to survivors and high-risk relatives to evaluate the efficacy of each intervention version on: a) use of breast cancer screening and genetic counseling; b) perceived barriers and facilitators to screening; c) self-efficacy in utilizing cancer genetic and screening services; d) family support related to screening; e) knowledge of breast cancer genetics; and f) satisfaction with the intervention. Discussion The study will enhance efforts of the state of Michigan surrounding cancer prevention, control, and public health genomics. Trial registration NCT01612338http://deepblue.lib.umich.edu/bitstream/2027.42/112835/1/12885_2012_Article_3739.pd

Exon deletions and intragenic insertions are not rare in ataxia with oculomotor apraxia 2

<p>Abstract</p> <p>Background</p> <p>The autosomal recessively inherited ataxia with oculomotor apraxia 2 (AOA2) is a neurodegenerative disorder characterized by juvenile or adolescent age of onset, gait ataxia, cerebellar atrophy, axonal sensorimotor neuropathy, oculomotor apraxia, and elevated serum AFP levels. AOA2 is caused by mutations within the senataxin gene (<it>SETX</it>). The majority of known mutations are nonsense, missense, and splice site mutations, as well as small deletions and insertions.</p> <p>Methods</p> <p>To detect mutations in patients showing a clinical phenotype consistent with AOA2, the coding region including splice sites of the <it>SETX </it>gene was sequenced and dosage analyses for all exons were performed on genomic DNA. The sequence of cDNA fragments of alternative transcripts isolated after RT-PCR was determined.</p> <p>Results</p> <p>Sequence analyses of the <it>SETX </it>gene in four patients revealed a heterozygous nonsense mutation or a 4 bp deletion in three cases. In another patient, PCR amplification of exon 11 to 15 dropped out. Dosage analyses and breakpoint localisation yielded a 1.3 kb LINE1 insertion in exon 12 (patient P1) and a 6.1 kb deletion between intron 11 and intron 14 (patient P2) in addition to the heterozygous nonsense mutation R1606X. Patient P3 was compound heterozygous for a 4 bp deletion in exon 10 and a 20.7 kb deletion between intron 10 and 15. This deletion was present in a homozygous state in patient P4.</p> <p>Conclusion</p> <p>Our findings indicate that gross mutations seem to be a frequent cause of AOA2 and reveal the importance of additional copy number analysis for routine diagnostics.</p

Common variation near IRF6 is associated with IFN-β-induced liver injury in multiple sclerosis

Multiple sclerosis (MS) is a disease of the central nervous system treated with disease-modifying therapies, including the biologic, interferon-β (IFN-β). Up to 60% of IFN-β-exposed MS patients develop abnormal biochemical liver test results1,2, and 1 in 50 experiences drug-induced liver injury3. Since genomic variation contributes to other forms of drug-induced liver injury4,5, we aimed to identify biomarkers of IFN-β-induced liver injury using a two-stage genome-wide association study. The rs2205986 variant, previously linked to differential expression of IRF6, surpassed genome-wide significance in the combined two-stage analysis (P = 2.3 × 10-8, odds ratio = 8.3, 95% confidence interval = 3.6-19.2). Analysis of an independent cohort of IFN-β-treated MS patients identified via electronic medical records showed that rs2205986 was also associated with increased peak levels of aspartate aminotransferase (P = 7.6 × 10-5) and alkaline phosphatase (P = 4.9 × 10-4). We show that these findings may be applicable to predicting IFN-β-induced liver injury, offering insight into its safer use