scholarly journals Genetic architecture influences when and how hybridization contributes to colonization

2019 ◽  
Author(s):  
Bryan Reatini ◽  
Todd J. Vision
Keyword(s):  
Environmental Conditions ◽  
Genetic Architecture ◽  
Genetic Variance ◽  
De Novo ◽  
Dispersal Rate ◽  
Intraspecific Hybridization ◽  
Source Populations ◽  
Second Category ◽  
Do So

AbstractThe role of genetic architecture in adaptation to novel environments has received considerable attention when the source of adaptation variation is de novo mutation. Relatively less is known when the source of adaptive variation is inter- or intraspecific hybridization. We model hybridization between divergent source populations and subsequent colonization of an unoccupied novel environment using individual-based simulations in order to understand the influence of genetic architecture on the timing of colonization and the mode of adaptation. We find that two distinct categories of genetic architecture facilitate rapid colonization but that they do so in qualitatively different ways. For few and/or tightly linked loci, the mode of adaptation is via the recovery of adaptive parental genotypes. With many unlinked loci, the mode of adaptation is via the generation of novel hybrid genotypes. The first category results in the shortest colonization lag phases across the widest range of parameter space, but further adaptation is mutation limited. The second category takes longer and is more sensitive to genetic variance and dispersal rate, but can facilitate adaptation to environmental conditions which exceed the tolerance of parental populations. These findings have implications for understanding the origins of biological invasions and the success of hybrid populations.

ROLE OF THE MESENCHYME IN THE INDUCTION OF THE RAT PROSTATE GLAND BY ANDROGENS IN ORGAN CULTURE

1979 ◽  
Vol 82 (1) ◽  
pp. 171-NP ◽  
Author(s):  
ILSE LASNITZKI ◽  
TAKEO MIZUNO
Keyword(s):  
Organ Culture ◽  
De Novo ◽  
Prostate Gland ◽  
Young Male ◽  
Free Medium ◽  
Foetal Rat ◽  
Rat Prostate ◽  
Do So

SUMMARY Rat prostate glands are induced de novo by androgens in 16·5-day-old male and female urogenital sinuses in vitro as epithelial buds projecting into the surrounding mesenchyme. The role of the mesenchyme in this process has been investigated in various epithelial-mesenchymal recombinations in organ culture. Isolated epithelium did not form buds but required the presence of the mesenchyme to do so. This requirement seemed to be specific; in the presence of testosterone or dihydrotestosterone only urogenital mesenchyme increased cell division in the urogenital epithelium and stimulated prostatic bud formation. In contrast, heterotypic mesenchyme did not affect epithelial mitosis and failed to induce buds while heterotypic epithelia did not respond to urogenital mesenchyme. In recombinants of urogenital mesenchyme pretreated with androgen and untreated urogenital epithelium, grown in androgen-free medium, the majority of explants developed prostatic buds while only a few buds were formed from epithelium pretreated with androgen when it was recombined with untreated mesenchyme. The role of the mesenchyme in the loss of androgen responsiveness of the older female sinuses was examined in heterochronic recombinants. It was found that the old female mesenchyme failed to induce buds in young epithelium while young male or female mesenchymes induced them in the old female epithelium. The results suggest that the urogenital mesenchyme is essential for the initiation of the foetal rat prostate gland and that it may be a target for androgens and complement or mediate their effect on the epithelium.

scholarly journals Latest findings in the genetic architecture of schizophrenia: The contribution of genetic studies among Afrikaners

2014 ◽  
Vol 33 (1) ◽  
Author(s):  
Johannes L. Roos
Keyword(s):  
Genetic Architecture ◽  
De Novo ◽  
Disease Risk ◽  
Association Studies ◽  
Copy Number Variants ◽  
Point Mutations ◽  
Risk Variants ◽  
Genome Wide ◽  
Long Time

A genetic component of schizophrenia has been acknowledged for a long time. The underlying architecture of the genetic risk remains a contentious issue. Early linkage and candidate association studies led to largely inconclusive results. More recently powerful technologies became available. This aspect coupled with samples of sufficient sizes, and genome-wide panels of genetic markers facilitated systematic and agnostic scans throughout the genome for either common or rare disease risk variants of small or large effect size, respectively. Although the former had limited success, the role of rare genetic events, such as copy-number variants (CNVs) or rare point mutations, has become increasingly important in gene discovery for schizophrenia. Recent research done among Afrikaner patients with schizophrenia, building upon earlier findings of de novo recurrent CNVs at the 22q11.2 locus, has highlighted a de novo mutational paradigm as a major component of the genetic architecture of schizophrenia. Recent progress in this regard will be reviewed.

scholarly journals Genetic architecture of four smoking behaviors using partitioned h2SNP

2020 ◽  
Author(s):  
Luke M. Evans ◽  
Seonkyeong Jang ◽  
Marissa A. Ehringer ◽  
Jacqueline M. Otto ◽  
Scott I. Vrieze ◽  
...  
Keyword(s):  
Smoking Cessation ◽  
Genetic Architecture ◽  
Genetic Variance ◽  
Rare Variants ◽  
Low Frequency ◽  
Smoking Initiation ◽  
Uk Biobank ◽  
Genome Wide ◽  
Smoking Behaviors

AbstractBackground and AimsSmoking is a leading cause of premature death. Although genome-wide association studies have identified many loci that influence smoking behaviors, much of the genetic variance in these traits remains unexplained. We sought to characterize the genetic architecture of four smoking behaviors through SNP-based heritability (h2SNP) analyses.DesignWe applied recently-developed partitioned h2SNP approaches to smoking behavior traits assessed in the UK Biobank.SettingUK Biobank.ParticipantsUK Biobank participants of European ancestry. The number of participants varied depending on the trait, from 54,792 to 323,068.MeasurementsSmoking initiation, age of initiation, cigarettes per day (CPD; count, log-transformed, binned, and dichotomized into heavy versus light), and smoking cessation. Imputed genome-wide SNPs.FindingsWe estimated h2SNP(SE)=0.18(0.01) for smoking initiation and 0.12(0.02) for smoking cessation, which were more than twice the previously reported estimates. Estimated age of initiation h2SNP=0.05(0.01) and binned CPD h2SNP=0.1(0.01) were similar to previous reports. These estimates remained substantially below published twin-based h2 of roughly 50%. CPD encoding strongly influenced estimates, with dichotomized CPD h2SNP=0.28. We found significant contributions of low-frequency variants and variants in low linkage-disequilibrium (LD) with surrounding genomic regions. Functional annotations related to LD, allele frequency, sequence conservation, and selective constraint also contributed significantly to the partitioned heritability. We found no evidence of dominance genetic variance for any trait.Conclusionh2SNP of these four specific smoking behaviors is modest overall. The patterns of partitioned h2SNP for these highly polygenic traits is consistent with negative selection. We found a predominant contribution of common variants, and our results suggest a role of low-frequency or rare variants, poorly tagged by surrounding regions. Deep sequencing of large samples and/or improved imputation will be required to fully assess the role of rare variants.

scholarly journals Evolutionary rates for multivariate traits: the role of selection and genetic variation

2014 ◽  
Vol 369 (1649) ◽  
pp. 20130252 ◽  
Author(s):  
William Pitchers ◽  
Jason B. Wolf ◽  
Tom Tregenza ◽  
John Hunt ◽  
Ian Dworkin
Keyword(s):  
Evolutionary Biology ◽  
Genetic Architecture ◽  
Genetic Variance ◽  
Evolutionary Rates ◽  
Phenotypic Traits ◽  
Sexually Selected Traits ◽  
Rates Of Evolution ◽  
Selected Traits ◽  
Multivariate Traits

A fundamental question in evolutionary biology is the relative importance of selection and genetic architecture in determining evolutionary rates. Adaptive evolution can be described by the multivariate breeders' equation ( ), which predicts evolutionary change for a suite of phenotypic traits ( ) as a product of directional selection acting on them ( β ) and the genetic variance–covariance matrix for those traits ( G ). Despite being empirically challenging to estimate, there are enough published estimates of G and β to allow for synthesis of general patterns across species. We use published estimates to test the hypotheses that there are systematic differences in the rate of evolution among trait types, and that these differences are, in part, due to genetic architecture. We find some evidence that sexually selected traits exhibit faster rates of evolution compared with life-history or morphological traits. This difference does not appear to be related to stronger selection on sexually selected traits. Using numerous proposed approaches to quantifying the shape, size and structure of G , we examine how these parameters relate to one another, and how they vary among taxonomic and trait groupings. Despite considerable variation, they do not explain the observed differences in evolutionary rates.

scholarly journals Evolutionary rates for multivariate traits: the role of selection and genetic variation

2014 ◽  
Author(s):  
William Pitchers ◽  
Jason B. Wolf ◽  
Tom Tregenza ◽  
John Hunt ◽  
Ian Dworkin
Keyword(s):  
Evolutionary Biology ◽  
Genetic Architecture ◽  
Genetic Variance ◽  
Evolutionary Rates ◽  
Phenotypic Traits ◽  
Sexually Selected Traits ◽  
Rates Of Evolution ◽  
Selected Traits ◽  
Multivariate Traits

A fundamental question in evolutionary biology is the relative importance of selection and genetic architecture in determining evolutionary rates. Adaptive evolution can be described by the multivariate breeders' equation (Δz = Gβ), which predicts evolutionary change for a suite of phenotypic traits (Δz) as a product of directional selection acting on them (β) and the genetic variance-covariance matrix for those traits (G). Despite being empirically challenging to estimate, there are enough published estimates ofGandβto allow for synthesis of general patterns across species. We use published estimates to test the hypotheses that there are systematic differences in the rate of evolution among trait types, and that these differences are in part due to genetic architecture. We find evidence that sexually selected traits exhibit faster rates of evolution compared to life-history or morphological traits. This difference does not appear to be related to stronger selection on sexually selected traits. Using numerous proposed approaches to quantifying the shape, size and structure ofGwe examine how these parameters relate to one another, and how they vary among taxonomic and trait groupings. Despite considerable variation, they do not explain the observed differences in evolutionary rates.

scholarly journals Both rare and common genetic variants contribute to autism in the Faroe Islands

2018 ◽  
Author(s):  
Claire S Leblond ◽  
Freddy Cliquet ◽  
Coralie Carton ◽  
Guillaume Huguet ◽  
Alexandre Mathieu ◽  
...  
Keyword(s):  
Genetic Architecture ◽  
De Novo ◽  
Copy Number Variants ◽  
Snp Array ◽  
Faroe Islands ◽  
Isolated Populations ◽  
Risk Genes ◽  
Common Genetic Variants ◽  
Rare Gene

AbstractThe number of genes associated with autism is increasing, but few studies have been performed on epidemiological cohorts and in isolated populations. Here, we investigated 357 individuals from the Faroe Islands including 36 individuals with autism, 136 of their relatives and 185 non-autism controls. Data from SNP array and whole exome sequencing revealed that individuals with autism compared to controls had a higher burden of copy-number variants (p < 0.05), higher inbreeding status (p < 0.005) and higher load of homozygous deleterious variants (p < 0.01). Our analysis supports the role of several genes/loci associated with autism (e.g. NRXN1, ADNP, 22q11 deletion) and identified new truncating (e.g. GRIK2, ROBO1, NINL and IMMP2L) or recessive deleterious variants (e.g. KIRELL3 and CNTNAP2) affecting autism-risk genes. It also revealed three genes involved in synaptic plasticity, RIMS4, KALRN and PLA2G4A, carrying de novo deleterious variants in individuals with autism without intellectual disability. In summary, our analysis provides a better understanding of the genetic architecture of autism in isolated populations by highlighting the role of both common and rare gene variants and pointing at new autism-risk genes. It also indicates that more knowledge about how multiple genetic hits affect neuronal function will be necessary to fully understand the genetic architecture of autism.

Posttransplant CMV infection and the role of immunosuppression (Sponsor: Novartis Pharma GmbH, Nürnberg)

2016 ◽  
Vol 04 (01) ◽  
pp. 4-10
Keyword(s):  
Lower Incidence ◽  
Paradigm Shift ◽  
Mtor Inhibitor ◽  
De Novo ◽  
Expert Panel ◽  
Risk Of Infection ◽  
Cmv Infection ◽  
Expert Meeting ◽  
Selection Of

AbstractImmunosuppression permits graft survival after transplantation and consequently a longer and better life. On the other hand, it increases the risk of infection, for instance with cytomegalovirus (CMV). However, the various available immunosuppressive therapies differ in this regard. One of the first clinical trials using de novo everolimus after kidney transplantation [1] already revealed a considerably lower incidence of CMV infection in the everolimus arms than in the mycophenolate mofetil (MMF) arm. This result was repeatedly confirmed in later studies [2–4]. Everolimus is now considered a substance with antiviral properties. This article is based on the expert meeting “Posttransplant CMV infection and the role of immunosuppression”. The expert panel called for a paradigm shift: In a CMV prevention strategy the targeted selection of the immunosuppressive therapy is also a key element. For patients with elevated risk of CMV, mTOR inhibitor-based immunosuppression is advantageous as it is associated with a significantly lower incidence of CMV events.

A Re-Appraisal of the Role of Blood Coagulation and Platelets in the Generalized Shwartzman Phenomenon

1966 ◽  
Vol 15 (03/04) ◽  
pp. 519-538 ◽  
Author(s):  
J Levin ◽  
E Beck
Keyword(s):  
Blood Coagulation ◽  
The State ◽  
Coagulation System ◽  
Renal Lesions ◽  
Intravascular Coagulation ◽  
Renal Glomeruli ◽  
Coagulation Mechanism ◽  
Shwartzman Phenomenon ◽  
Do So

SummaryThe role of intravascular coagulation in the production of the generalized Shwartzman phenomenon has been evaluated. The administration of endotoxin to animals prepared with Thorotrast results in activation of the coagulation mechanism with the resultant deposition of fibrinoid material in the renal glomeruli. Anticoagulation prevents alterations in the state of the coagulation system and inhibits development of the renal lesions. Platelets are not primarily involved. Platelet antiserum produces similar lesions in animals prepared with Thorotrast, but appears to do so in a manner which does not significantly involve intravascular coagulation.The production of adrenal cortical hemorrhage, comparable to that seen in the Waterhouse-Friderichsen syndrome, following the administration of endotoxin to animals that had previously received ACTH does not require intravascular coagulation and may not be a manifestation of the generalized Shwartzman phenomenon.

‘Wheels have been set in motion’: Geocentrism and Relativity in Tom Stoppard’s Rosencrantz and Guildenstern Are Dead

2018 ◽  
Author(s):  
Liliane Campos
Keyword(s):  
20Th Century ◽  
Film Adaptation ◽  
Frames Of Reference ◽  
Quantum Uncertainty ◽  
Galilean Relativity ◽  
Modern Physics ◽  
20Th Century Physics ◽  
Time Specific ◽  
Do So

By decentring our reading of Hamlet, Stoppard’s tragicomedy questions the legitimacy of centres and of stable frames of reference. So Liliane Campos examines how Stoppard plays with the physical and cosmological models he finds in Hamlet, particularly those of the wheel and the compass, and gives a new scientific depth to the fear that time is ‘out of joint’. In both his play and his own film adaptation, Stoppard’s rewriting gives a 20th-century twist to these metaphors, through references to relativity, indeterminacy, and the role of the observer. When they refer to the uncontrollable wheels of their fate, his characters no longer describe the destruction of order, but uncertainty about which order is at work, whether heliocentric or geocentric, random or tragic. When they express their loss of bearings, they do so through the thought experiments of modern physics, from Galilean relativity to quantum uncertainty, drawing our attention to shifting frames of reference. Much like Schrödinger’s cat, Stoppard’s Rosencrantz and Guildenstern are both dead and alive. As we observe their predicament, Campos argues, we are placed in the paradoxical position of the observer in 20th-century physics, and constantly reminded that our time-specific relation to the canon inevitably determines our interpretation.

Helping when desire is low: The role of Expectancy in helping

2020 ◽  
Author(s):  
Małgorzata Kossowska
Keyword(s):  
Experimental Studies ◽  
Helping Behavior ◽  
Perceived Effectiveness ◽  
Do So

One might assume that the desire to help (here described as Want) is the essential driver of helping declarations and/or behaviors. However, even if desire to help is low, helping behavior may still occur if the expectancy regarding the perceived effectiveness of helping is high. We tested these predictions in a set of three experimental studies. In all three, we measured the desire to help (Want) and the Expectancy that the aid would be impactful for the victim; in addition, we manipulated Expectancy in Study 3. In Studies 1 and 3, we measured the participants’ declaration to help while in Study 2, their helping behavior was examined. In all three studies, we used variations of the same story about a victim. The results supported our hypothesis. Thus, the studies help to tease apart the determinants of helping behavior under conditions of lowered desire to do so, an issue of great importance in public policymaking.

Sign in / Sign up

Export Citation Format

Share Document