Evidence of sexual reproduction events in the dagger nematode Xiphinema index in grapevine resistance experiments under controlled conditions

Plant Disease ◽  
2020 ◽  
Author(s):  
Van Chung Nguyen ◽  
Samira Khallouk ◽  
Joël Polidori ◽  
Julia Truch ◽  
Ulysse Portier ◽  
...  
Keyword(s):  
Sexual Reproduction ◽  
Multilocus Genotype ◽  
Equal Proportion ◽  
Grapevine Fanleaf Virus ◽  
Line Frequency ◽  
Xiphinema Index ◽  
Controlled Conditions ◽  
Random Samples ◽  
Over Time ◽  
Durability Of Resistance

The dagger nematode Xiphinema index has a major economic impact due to its transmission of Grapevine fanleaf virus (GFLV) to grapevines. This vector nematode, which was introduced into Western countries from the Middle East together with the domesticated grapevine, mostly reproduces by meiotic parthenogenesis, but microsatellite multilocus genotype (MLG) analysis has revealed the occurrence of rare sexual reproduction events in field conditions. In a previous six-year study under controlled conditions, we evaluated the durability of resistance (R) to X. index in accessions derived from a muscadine R source and reference accessions. In this previous study, we used an equal-proportion mixture of four lines (from Spain, Italy, Greece and Iran) representative of X. index diversity as the inoculum, and we collected random samples in three-, four-, five- and six-year-old vines. Here, we genotyped the individuals from these samples using MLG technique, and we analyzed the changes in line frequency and the occurrence of sexual reproduction events between lines over time. The nematode lines differed in aggressiveness and hybrids between lines were detected at a low, but apparently increasing rate. Hybridization events were recovered in all accessions, regardless of resistance status and propagation type. Finally, our data provide the first evidence of sexual reproduction in the nematode X. index under controlled conditions.

Soft Computing Techniques in Civil Engineering

2010 ◽  
pp. 143-159
Author(s):  
Juan L. Pérez ◽  
Juan R. Rabuñal ◽  
Fernando Martínez Abella
Keyword(s):  
Genetic Programming ◽  
Evolutionary Computation ◽  
Soft Computing ◽  
Civil Engineering ◽  
Structural Concrete ◽  
Controlled Conditions ◽  
Classical Algorithm ◽  
Soft Computing Techniques ◽  
Over Time

Soft computing techniques are applied to a huge quantity of problems spread in several areas of science. In this case, Evolutionary Computation (EC) techniques are applied, in concrete Genetic Programming (GP), to a temporary problem associated to the field of Civil Engineering. The case of study of this technique has been centered in the prediction, over time, of the behavior of the structural concrete in controlled conditions. Given the temporary nature of the case of study, it has been necessary to make several changes to the classical algorithm of GP, among whom it can be emphasized the incorporation of a new operator that gives the GP the ability to be able to solve problems with temporary behavior. The obtained results shown that the proposed method has succeeded in improving the adjustment to the current regulations about creep in the structural concrete.

Soft Computing Techniques in Civil Engineering

2012 ◽  
pp. 1982-1997
Author(s):  
Juan L. Pérez ◽  
Juan Rabuñal ◽  
Fernando Martínez Abella
Keyword(s):  
Genetic Programming ◽  
Evolutionary Computation ◽  
Soft Computing ◽  
Civil Engineering ◽  
Structural Concrete ◽  
Controlled Conditions ◽  
Classical Algorithm ◽  
Soft Computing Techniques ◽  
Over Time

Soft computing techniques are applied to a huge quantity of problems spread in several areas of science. In this case, Evolutionary Computation (EC) techniques are applied, in concrete Genetic Programming (GP), to a temporary problem associated to the field of Civil Engineering. The case of study of this technique has been centered in the prediction, over time, of the behavior of the structural concrete in controlled conditions. Given the temporary nature of the case of study, it has been necessary to make several changes to the classical algorithm of GP, among whom it can be emphasized the incorporation of a new operator that gives the GP the ability to be able to solve problems with temporary behavior. The obtained results shown that the proposed method has succeeded in improving the adjustment to the current regulations about creep in the structural concrete.

scholarly journals The NCAR–FAA Snow Machine: An Artificial Snow-Generation System

2018 ◽  
Vol 35 (11) ◽  
pp. 2159-2168
Author(s):  
Scott D. Landolt ◽  
Roy M. Rasmussen ◽  
Alan J. Hills ◽  
Warren Underwood ◽  
Charles A. Knight ◽  
...  
Keyword(s):  
Mass Balance ◽  
Size Distribution ◽  
Liquid Water ◽  
Generation System ◽  
Fall Velocity ◽  
Atmospheric Research ◽  
Controlled Conditions ◽  
Precipitation Gauge ◽  
Cold Chamber ◽  
Over Time

AbstractThe National Center for Atmospheric Research (NCAR) developed an artificial snow-generation system designed to operate in a laboratory cold chamber for testing aircraft anti-icing fluids under controlled conditions. Flakes of ice are produced by shaving an ice cylinder with a rotating carbide bit; the resulting artificial snow is dispersed by turbulent airflows and falls approximately 2.5 m to the bottom of the device. The resulting fine ice shavings mimic snow in size, distribution, fall velocity, density, and liquid water equivalent (LWE) snowfall rate. The LWE snowfall rate can be controlled using either a mass balance or a precipitation gauge, which measures the snowfall accumulation over time, from which the computer derives the LWE rate. LWE snowfall rates are calculated every 6 s, and the rate the ice cylinder is fed into the carbide bit is continually adjusted to ensure that the LWE snowfall rate matches a user-selected value. The system has been used to generate LWE snowfall rates ranging from 0 to 10 mm h−1 at temperatures from −2 to −30°C and densities of approximately 0.1–0.5 g cm−3. Comparisons of the snow-machine fluid tests with the outdoor fluid tests have shown that the snow machine can mimic natural outdoor rates under a broad range of conditions.

Employing Simulated Data to Illustrate an Important Cause of the ‘Steepling’ Effect in Breath Alcohol Analysis

1994 ◽  
Vol 34 (4) ◽  
pp. 321-323 ◽  
Author(s):  
Rod G. Gullberg
Keyword(s):  
Kinetic Model ◽  
Data Collection ◽  
Nonlinear Regression ◽  
Kinetic Modelling ◽  
Analytical Data ◽  
Simulated Data ◽  
Breath Alcohol ◽  
Random Samples ◽  
The Mean ◽  
Over Time

The ‘steepling’ effect (large excursions in analytical data over time) is a debated issue in forensic breath alcohol analysis with various explanations being postulated. Simulated breath alcohol data was generated according to a hypothetical kinetic model where single random samples as well as means of duplicate random samples were plotted with respect to time at 0.2 hour intervals. In addition, the simulated data was compared when both two or more digit treatment was employed. Results showed the occurrence of significant noise or ‘steepling’ when single, two-digit breath alcohol samples were employed as compared to a four-digit mean computed from three-digit duplicates. The magnitude of variability was quantified by means of nonlinear regression resulting in the residual sum of squares (RSS) = 0.00202 for the single analysis and RSS = 0.00053 for the mean of duplicates. The method of data collection and treatment appears to contribute significantly to the ‘steepling’ phenomenon. Intuitively, replicate analyses reduce variability and allow for more accurate kinetic modelling employing breath alcohol analysis.

scholarly journals Ant queens adjust egg fertilization to benefit from both sexual and asexual reproduction

2011 ◽  
Vol 7 (4) ◽  
pp. 571-573 ◽  
Author(s):  
S. Aron ◽  
I. Timmermans ◽  
M. Pearcy
Keyword(s):  
Sexual Reproduction ◽  
Asexual Reproduction ◽  
Evolutionary Biology ◽  
Transmission Rate ◽  
Early Spring ◽  
Mating Period ◽  
Cataglyphis Cursor ◽  
Sexual And Asexual Reproduction ◽  
Over Time

An enduring problem in evolutionary biology is the near ubiquity of sexual reproduction despite the inherent cost of transmitting only half the parent's genes to progeny. Queens of some ant species circumvent this cost by using selectively both sexual reproduction and parthenogenesis: workers arise from fertilized eggs, while new queens are produced by parthenogenesis. We show that queens of the ant Cataglyphis cursor maximize the transmission rate of their genes by regulating the proportion of fertilized and parthenogenetic eggs laid over time. Parthenogenetic offspring are produced in early spring, when workers raise the brood into sexuals. After the mating period, queens lay mostly fertilized eggs that will be reared as the non-reproductive caste.

scholarly journals The specific transmission of Grapevine fanleaf virus by its nematode vector Xiphinema index is solely determined by the viral coat protein

Virology ◽  
2004 ◽  
Vol 320 (1) ◽  
pp. 12-22 ◽  
Author(s):  
Peggy Andret-Link ◽  
Corinne Schmitt-Keichinger ◽  
Gérard Demangeat ◽  
Véronique Komar ◽  
Marc Fuchs
Keyword(s):  
Coat Protein ◽  
Grapevine Fanleaf Virus ◽  
Viral Coat Protein ◽  
Xiphinema Index ◽  
Viral Coat

scholarly journals Asexual freshwater snails make poor mate choice decisions

2021 ◽  
Author(s):  
Sydney Stork ◽  
Joseph Jalinsky ◽  
Maurine Neiman
Keyword(s):  
New Zealand ◽  
Mate Choice ◽  
Sexual Reproduction ◽  
Asexual Reproduction ◽  
Freshwater Snail ◽  
Freshwater Snails ◽  
Choice Assay ◽  
Mating Choice ◽  
Related Trait ◽  
Over Time

Once-useful traits that no longer contribute to fitness tend to decay over time. We address whether the expression of mating-related traits that increase the fitness of sexually reproducing individuals but are likely less useful or even costly to asexual counterparts seems to exhibit decay in the latter. Potamopyrgus antipodarum is a New Zealand freshwater snail characterized by repeated transitions from sexual to asexual reproduction. The frequent coexistence of sexual and asexual lineages makes P. antipodarum an excellent model for the study of mating-related trait loss. We used a mating choice assay including sexual and asexual P. antipodarum females and conspecific (presumed better choice) vs. heterospecific (presumed worse choice) males to evaluate the loss of behavioural traits related to sexual reproduction. We found that sexual females engaged in mating behaviours with conspecific mating partners more frequently and for a greater duration than with heterospecific mating partners, while asexual females seemed to lack the ability to make a choice. These results suggest that selection acting to maintain mate choice in asexual P. antipodarum is weak or ineffective relative to sexual females and that asexual reproduction likely contributes to the evolutionary decay of behavioural traits in this system.

scholarly journals Survival of Xiphinema index in Vineyard Soil and Retention of Grapevine fanleaf virus Over Extended Time in the Absence of Host Plants

2005 ◽  
Vol 95 (10) ◽  
pp. 1151-1156 ◽  
Author(s):  
Gérard Demangeat ◽  
Roger Voisin ◽  
Jean-Claude Minot ◽  
Nathalie Bosselut ◽  
Marc Fuchs ◽  
...  
Keyword(s):  
Host Plants ◽  
Control Strategies ◽  
Limited Information ◽  
Grapevine Fanleaf Virus ◽  
Term Survival ◽  
Adverse Conditions ◽  
Xiphinema Index ◽  
Vineyard Soil ◽  
Viral Genomic Rna

Grapevine fanleaf virus (GFLV) is transmitted specifically from grapevine to grapevine by the ectoparasitic root-feeding nematode Xiphinema index. Limited information is available on the survival of X. index in vineyard soil and on the retention of GFLV by X. index over extended periods of time. We addressed these two issues by quantifying the numbers of living X. index recovered from soil samples that were collected in three naturally GFLV-infected vineyards in France and subsequently stored at 7 or 20°C in the absence of host plants. Our data indicated a two- to eightfold decrease in X. index numbers but the recovery of 8 to 10 living fourth-stage juveniles (J4) and adults per kilogram of soil after 4 years of storage regardless of temperature. In addition, GFLV was detected readily in all groups of 20 isolated X. index adults and J4 (except for J4 that were kept 4 years at 20°C) by reverse transcription-polymerase chain reaction using total nematode RNAs and a primer set located in conserved regions at the 3′ end of viral genomic RNA 2. Our findings on the long-term survival of viruliferous X. index under adverse conditions emphasize the need for new control strategies against GFLV.

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