scholarly journals Enhanced Outcrossing, Directional Selection and Transgressive Segregation Drive Evolution of Novel Phenotypes in Hybrid Swarms of the Dutch Elm Disease Pathogen Ophiostoma novo-ulmi

2021 ◽  
Vol 7 (6) ◽  
pp. 452
Author(s):  
Clive Brasier ◽  
Selma Franceschini ◽  
Jack Forster ◽  
Susan Kirk
Keyword(s):  
Growth Rate ◽  
Transgressive Segregation ◽  
Directional Selection ◽  
Dutch Elm Disease ◽  
The Novel ◽  
Hybrid Fitness ◽  
Hybrid Swarms ◽  
Popula Tions ◽  
Extreme Phenotypes ◽  
Type Frequency

In the 1970s, clones of the two subspecies of Ophiostoma novo-ulmi, subsp. americana (SSAM) and subsp. novo-ulmi (SSNU) began to overlap in Europe, resulting in hybrid swarms. By 1983–1986, hybrids with high, SSAM-like growth and pathogenic fitness comprised ~75% of popula-tions at Limburg, Netherlands and Orvieto, Italy. We resampled these populations in 2008 to examine trends in hybrid fitness traits. Since preliminary sampling in 1979–1980, MAT-1 locus frequency had increased from ~0% to ~32% at Orvieto and 5% to ~43% at Limburg, and vegeta-tive incompatibility type frequency had changed from near clonal to extremely diverse at both sites. This represents an enormous increase in outcrossing and recombination potential, due in part to selective acquisition (under virus pressure) of MAT-1 and vic loci from the resident O. ulmi and in part to SSAM × SSNU hybridisation. Overt virus infection in the 2008 samples was low (~4%), diagnostic SSAM and SSNU cu and col1 loci were recombinant, and no isolates exhib-ited a parental SSAM or SSNU colony pattern. At both sites, mean growth rate and mean patho-genicity to 3–5 m clonal elm were high SSAM-like, indicating sustained directional selection for these characters, though at Orvieto growth rate was slower. The once frequent SSNU-specific up-mut colony dimorphism was largely eliminated at both sites. Perithecia formed by Limburg isolates were mainly an extreme, long-necked SSNU-like form, consistent with transgressive segregation resulting from mismatch of SSAM and SSNU developmental loci. Orvieto isolates produced more parental-like perithecia, suggesting the extreme phenotypes may have been se-lected against. The novel phenotypes in the swarms are remodelling O. novo-ulmi in Europe. Locally adapted genotypes may emerge.

scholarly journals The genetic architecture necessary for transgressive segregation is common in both natural and domesticated populations

2003 ◽  
Vol 358 (1434) ◽  
pp. 1141-1147 ◽  
Author(s):  
Loren H. Rieseberg ◽  
Alex Widmer ◽  
A. Michele Arntz ◽  
Burke Burke
Keyword(s):  
Adaptive Evolution ◽  
Genetic Architecture ◽  
Transgressive Segregation ◽  
Species Level ◽  
General Mechanism ◽  
Interspecific Crosses ◽  
Genetic Studies ◽  
Extreme Phenotypes ◽  
Parental Lines ◽  
Parental Differences

Segregating hybrids often exhibit phenotypes that are extreme or novel relative to the parental lines. This phenomenon is referred to as transgressive segregation, and it provides a mechanism by which hybridization might contribute to adaptive evolution. Genetic studies indicate that transgressive segregation typically results from recombination between parental taxa that possess quantitative trait loci (QTLs) with antagonistic effects (i.e. QTLs with effects that are in the opposite direction to parental differences for those traits). To assess whether this genetic architecture is common, we tabulated the direction of allelic effects for 3252 QTLs from 749 traits and 96 studies. Most traits (63.6%) had at least one antagonistic QTL, indicating that the genetic substrate for transgressive segregation is common. Plants had significantly more antagonistic QTLs than animals, which agrees with previous reports that transgressive segregation is more common in plants than in animals. Likewise, antagonistic QTLs were more frequent in intra– than in interspecific crosses and in morphological than in physiological traits. These results indicate that transgressive segregation provides a general mechanism for the production of extreme phenotypes at both above and below the species level and testify to the possible creative part of hybridization in adaptive evolution and speciation.

scholarly journals “Lessons from Rare Forms of Osteoarthritis”

2021 ◽  
Vol 109 (3) ◽  
pp. 291-302 ◽  
Author(s):  
Rebecca F. Shepherd ◽  
Jemma G. Kerns ◽  
Lakshminarayan R. Ranganath ◽  
James A. Gallagher ◽  
Adam M. Taylor
Keyword(s):  
Treatment Strategies ◽  
First Century ◽  
Therapeutic Interventions ◽  
Coxa Vara ◽  
Common Disease ◽  
The Novel ◽  
Mendelian Disorders ◽  
Extreme Phenotypes ◽  
Different Types ◽  
Developed World

Abstract Osteoarthritis (OA) is one of the most prevalent conditions in the world, particularly in the developed world with a significant increase in cases and their predicted impact as we move through the twenty-first century and this will be exacerbated by the covid pandemic. The degeneration of cartilage and bone as part of this condition is becoming better understood but there are still significant challenges in painting a complete picture to recognise all aspects of the condition and what treatment(s) are most appropriate in individual causes. OA encompasses many different types and this causes some of the challenges in fully understanding the condition. There have been examples through history where much has been learnt about common disease(s) from the study of rare or extreme phenotypes, particularly where Mendelian disorders are involved. The often early onset of symptoms combined with the rapid and aggressive pathogenesis of these diseases and their predictable outcomes give an often-under-explored resource. It is these “rarer forms of disease” that William Harvey referred to that offer novel insights into more common conditions through their more extreme presentations. In the case of OA, GWAS analyses demonstrate the multiple genes that are implicated in OA in the general population. In some of these rarer forms, single defective genes are responsible. The extreme phenotypes seen in conditions such as Camptodactyly Arthropathy-Coxa Vara-pericarditis Syndrome, Chondrodysplasias and Alkaptonuria all present potential opportunities for greater understanding of disease pathogenesis, novel therapeutic interventions and diagnostic imaging. This review examines some of the rarer presenting forms of OA and linked conditions, some of the novel discoveries made whilst studying them, and findings on imaging and treatment strategies.

Phaeotheca dimorphospora sp.nov.: description et caractéristiques culturales

1994 ◽  
Vol 72 (6) ◽  
pp. 808-817 ◽  
Author(s):  
Pierre DesRochers ◽  
G. B. Ouellette
Keyword(s):  
Growth Rate ◽  
Growth Temperature ◽  
Type Species ◽  
Optimal Growth ◽  
Outer Wall ◽  
Dutch Elm Disease ◽  
Optimal Growth Temperature ◽  
Ophiostoma Ulmi ◽  
Mother Cells

An unknown fungus isolated from an elm branch and inhibitory against Ophiostoma ulmi in vitro is described as Phaeotheca dimorphospora sp.nov. This dematiaceous deuteromycete propagates by endoconidia released after exfoliation of chlamydospore outer wall, as in mother cells of the type species Phaeotheca fissurella. However, P. dimorphospora differs from the type species by producing hyaline secondary ameroconidia between the endoconidial masses. Other ameroconidia, similar to the secondary ameroconidia, are produced through the chlamydospore outer wall. The optimal growth temperature of P. dimorphospora is 23 °C, whereas it is 15.5 °C for the type species. On media containing a high dextrose concentration (30 g ∙ L−1), colonies of P. dimorphospora are gray and crustose and grow slowly, at least initially. Conversely, on media with a low dextrose concentration (5 or 10 g ∙ L−1) colonies have a faster growth rate and appear whitish or ivory and fluffy. Key words: Phaeotheca dimorphospora, diagnosis, inhibition, Ophiostoma ulmi, Dutch elm disease.

scholarly journals Can cryptocurrencies be a safe haven during the novel COVID-19 pandemic? Evidence from the Tunisian Stock Market

2020 ◽  
Vol 3 (1) ◽  
pp. 14-31
Author(s):  
Ahmed Jeribi ◽  
Yasmin Snene Manzli
Keyword(s):  
Growth Rate ◽  
Stock Market ◽  
Portfolio Diversification ◽  
The Novel ◽  
Safe Haven ◽  
Market Returns ◽  
Stock Market Returns ◽  
Ols Regression ◽  
Hedging Strategies ◽  
The Us

In this paper, we discuss the behavior of stock market returns in Tunisia during the COVID-19 outbreak. Using the OLS regression, we find that Bitcoin act as a hedge and Ethereum as a diversifier for Tunisia’s stock market before the COVID-19 outbreak; however, Bitcoin and Ethereum cannot generate benefits from portfolio diversification and hedging strategies for financial investors during the COVID-19. Moreover, Dash, Monero, and Ripple act as hedges before the COVID-19 outbreak and as diversifiers during this pandemic. Our results reveal that gold acts as a hedge and diversifier before the pandemic, but it's neither hedge nor a haven during the COVID-19 pandemic. Besides, the results indicated that the expected volatility of the US stock market has an impact on the Tunisian stock market. Finally, our results indicate that the growth rate of the COVID-19 confirmed cases and deaths harms Tunisia's stock market.

scholarly journals Changing Clusters of Indian States with respect to number of Cases of COVID-19 using incrementalKMN Method

2020 ◽  
Author(s):  
Rabinder Kumar Prasad ◽  
Rosy Sarmah ◽  
Subrata Chakraborty
Keyword(s):  
Growth Rate ◽  
High Risk ◽  
Doubling Time ◽  
The Other ◽  
Risk Category ◽  
The Novel ◽  
Indian States ◽  
High Risk Category ◽  
First Case ◽  
Novel Coronavirus

Abstract The novel Coronavirus (COVID-19) incidence in India is currently experiencing exponential rise with apparent spatial variation in growth rate and doubling time. We classify the states into five clusters with low to high-risk category and identify how the different states moved from one cluster to the other since the onset of the first case on $30^{th}$ January 2020 till the end of $15^{th}$ September 2020. We cluster the Indian states into $5$ groups using incrementalKMN clustering \cite{b1}. We observed and comment on the changing scenario of the formation of the clusters starting from before lockdown, through lockdown and the various unlock phases.

scholarly journals Effect of Elm Selection, Explant Source and Medium Composition on Growth of Ophiostoma ulmi on Callus Cultures

1992 ◽  
Vol 10 (1) ◽  
pp. 59-62
Author(s):  
Subhash C. Domir ◽  
Lawrence R. Schreiber ◽  
Jann M. Ichida ◽  
Steven M. Eshita
Keyword(s):  
Growth Rate ◽  
High Performance ◽  
Callus Tissue ◽  
Fungal Growth ◽  
Callus Cultures ◽  
Medium Composition ◽  
Dutch Elm Disease ◽  
Ophiostoma Ulmi ◽  
American Elm ◽  
Explant Source

Abstract We examined the effects of elm selection, explant source and media composition on growth of the Dutch elm disease (DED) fungus Ophiostoma ulmi on callus cultures. Calluses were generated from leaf and stem tissue of an American elm (Ulmus Americana L.) seedling (A), susceptible to the disease; an American elm selection 8630, resistant to the disease; and a Siberian elm (U. pumila L.) seedling, also resistant to DED. Calluses were generated on modified Murashige-Skoog (MMS) medium, either with (MMSC) or without coconut milk. Explant source did not affect the fungal growth rate on the callus. Rate of O. ulmi growth on American elm A callus was similar on both media; on Siberian and 8630, fungal growth rate was more rapid on callus cultured on MMS than on MMSC. However, in the absence of callus tissue, O. ulmi growth on MMSC medium was more than five times as rapid as it was on MMS. We observed significant interactions between explant source and selection, and between medium and selection. Fungal growth was always more rapid on American A, and American 8630 then on Siberian. Scanning electron microscopy revealed heavy fungal sporulation on American A, slight on Siberian and none on American 8630. High performance liquid chromatography analysis showed that the secondary metabolic profiles were distinguishable for callus tissue versus explant tissue, but were similar for calli generated from different explant sources.

scholarly journals Lessons from mainland China’s epidemic experience about the growth rules of infected and recovered cases of COVID-19 worldwide

2020 ◽  
Author(s):  
Chuanliang Han ◽  
Yimeng Liu ◽  
Jiting Tang ◽  
Yuyao Zhu ◽  
Carlo Jaeger ◽  
...  
Keyword(s):  
Growth Rate ◽  
Strong Evidence ◽  
Logistic Model ◽  
Mainland China ◽  
Linear Connection ◽  
Control Measures ◽  
Logistic Growth ◽  
Strong Positive Correlation ◽  
The Novel ◽  
Novel Coronavirus

AbstractThe novel coronavirus disease (COVID-19) that emerged at the end of 2019 has been controlled in mainland China so far, while it is still spreading globally. When the pandemic will end is a question of great concern. A logistic model depicting the growth rules of infected and recovered cases in mainland China may shed some light on this question. We extended this model to 31 countries outside China experiencing serious COVID-2019 outbreaks. The model well explained the data in our study (R2 ≥ 0.95). For infected cases, the semi-saturation period (SSP) ranges from 63 to 170 days (March 3 to June 18). The logistic growth rate of infected cases is positively correlated with that of recovered cases, and the same holds for the SSP. According to the linear connection between the growth rules for infected and recovered cases identified from the Chinese data, we predicted that the SSP of the recovered cases outside China ranges from 82 to 196 days (March 22 to July 8). More importantly, we found a strong positive correlation between the SSP of infected cases and the timing of government’s response, providing strong evidence for the effectiveness of rapid epidemic control measures in various countries.

scholarly journals ‘Fiorente’ and ‘Arno’ Elm Trees

HortScience ◽  
2007 ◽  
Vol 42 (3) ◽  
pp. 712-714 ◽  
Author(s):  
Alberto Santini ◽  
Alberto Fagnani ◽  
Fabio Ferrini ◽  
Luisa Ghelardini ◽  
Lorenzo Mittempergher
Keyword(s):  
Growth Rate ◽  
20Th Century ◽  
Genetic Improvement ◽  
Mediterranean Climate ◽  
Breeding Program ◽  
Dutch Elm Disease ◽  
Asian Species ◽  
Improvement Programs ◽  
The Mediterranean

Dutch elm disease (DED) has spread through Europe since the beginning of the 20th century. Several independent genetic improvement programs for breeding DED-resistant elms have been established in Europe. The Italian elm breeding program began in the late 1970s with the goal of hybridizing susceptible European elms with resistant Asian species to select DED-resistant clones suited to the Mediterranean climate. Ulmus ‘Fiorente’ and ‘Arno’ are two new releases selected for DED resistance, superior growth rate, attractive foliage, and upright habit.

scholarly journals SARS-CoV-2 Variant Under Investigation 202012/01 has more than twofold replicative advantage

2021 ◽  
Author(s):  
Frederic Grabowski ◽  
Grzegorz Preibisch ◽  
Marek Kochańczyk ◽  
Tomasz Lipniacki
Keyword(s):  
Growth Rate ◽  
Exponential Growth ◽  
The Novel ◽  
Serial Interval

AbstractThe novel SARS-CoV-2 Variant Under Investigation VUI-202012/01 (also known as B.1.1.7), first collected on September 20, 2020, in Kent, is a rapidly growing lineage that in the first half of December 2020 constitutes more than 1/3 of all SARS-CoV-2 genomes sequenced in England. Based on GISAID data we have shown nearly exponential growth of the VUI-202012/01 to non-VUI-202012/01 genomes ratio in the five-week period since October 19 till November 22, 2020, with weekly growth rate of 2.31 [95% CI: 2.08–2.57]. Assuming the serial interval of 6.73 days we estimated the replicative advantage of VUI-202012/01 lineage as 2.316.73/7 = 2.24 [95% CI: 2.03–2.48]. Such significant replicative advantage and the fact that London serves as major international transportation hub suggest that the VUI-202012/01 strain will likely become globally dominant, hindering containment of the COVID-19 epidemics prior to massive vaccinations.

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