scholarly journals Experimental evolution of virulence and associated traits in a Drosophila melanogaster – Wolbachia symbiosis

2020 ◽  
Author(s):  
David Monnin ◽  
Natacha Kremer ◽  
Caroline Michaud ◽  
Manon Villa ◽  
Hélène Henri ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
High Temperature ◽  
Evolutionary Theory ◽  
Artificial Selection ◽  
Environmental Conditions ◽  
Experimental Evolution ◽  
Copy Number ◽  
Time Points ◽  
Evolution Of Virulence ◽  
The Mean

AbstractEvolutionary theory predicts that vertically transmitted symbionts are selected for low virulence, as their fitness is directly correlated to that of their host. In contrast with this prediction, the Wolbachia strain wMelPop drastically reduces its Drosophila melanogaster host lifespan at high rearing temperatures. It is generally assumed that this feature is maintained because the D. melanogaster–wMelPop symbiosis is usually not exposed to environmental conditions in which the symbiont is virulent. To test this hypothesis, we submitted wMelPop-infected D. melanogaster lines to 17 generations of experimental evolution at a high temperature, while enforcing late reproduction by artificial selection. The fly survival was measured at different time points, as well as two traits that have been proposed to be causally responsible for wMelPop virulence: its relative density and the mean number of copies of octomom, an 8-genes region of the Wolbachia genome. We hypothesised that these conditions (high temperature and late reproduction) would select for a reduced wMelPop virulence, a reduced wMelPop density, and a reduced octomom copy number. Our results indicate that density, octomom copy number and virulence are correlated to each other. However, contrary to our expectations, we could not detect any reduction in virulence during the course of evolution. We discuss the significance of our results with respect to the evolutionary causes of wMelPop virulence.

scholarly journals Experimental evolution of virulence and associated traits in a Drosophila melanogaster–Wolbachia symbiosis

2021 ◽  
Vol 1 ◽  
pp. 1-None
Author(s):  
David Monnin ◽  
Natacha Kremer ◽  
Caroline Michaud ◽  
Manon Villa ◽  
Hélène Henri ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Experimental Evolution ◽  
Evolution Of Virulence

scholarly journals GENOTYPE AND TIME OF INOCULATION EFFECTS ON DON PER GRAIN AND GRAIN WEIGHT OF WINTER WHEAT UNDER TWO ENVIRONMENTAL CONDITIONS

2017 ◽  
Vol 7 (4) ◽  
pp. 1185-1188
Author(s):  
Victor Chijioke Okereke
Keyword(s):  
High Temperature ◽  
Winter Wheat ◽  
Environmental Conditions ◽  
Grain Weight ◽  
Controlled Environment ◽  
Near Isogenic Lines ◽  
Wild Type ◽  
Subsequent Increase ◽  
Wheat Grains ◽  
The Mean

Experiment was conducted using near isogenic lines of Mercia background in a controlled environment to evaluate the mean effect of timing of inoculation and subsequent increase in temperature on deoxynivalenol (DON) concentration, amount of DON per grain and grain weight. The experiment was completely randomised consisting of three genotypes differing in semi-dwarfing alleles; Mercia 0 {Rht-B1a + Rht-D1a (wild type)}, Mercia 1 (Rht-B1b) and Mercia 2 (Rht-D1b) and four inoculation timings. The experiment was a complete factorial combination with four randomised replicates. Data showed that genotype differed in DON concentration (P<0.001), DON per grain (P=0.006) and mean grain weight (P=0.001) while time of inoculation influenced mean grain weight (P<0.001) and DON Concentration (P<0.001) but not Don per grain (P=0.23). Temperature influenced mean grain weight (P=0.002) with high temperature adversely affecting the size of the wheat grains.

scholarly journals Polygenic mutation in Drosophila melanogaster: the causal relationship of bristle number to fitness.

Genetics ◽  
1995 ◽  
Vol 139 (2) ◽  
pp. 861-872 ◽  
Author(s):  
S V Nuzhdin ◽  
J D Fry ◽  
T F Mackay
Keyword(s):  
Drosophila Melanogaster ◽  
Artificial Selection ◽  
Random Mating ◽  
Direct Selection ◽  
Stabilizing Selection ◽  
Fitness Effects ◽  
Bristle Number ◽  
Mean Fitness ◽  
The Mean ◽  
Average Fitness

Abstract The association between sternopleural and abdominal bristle number and fitness in Drosophila melanogaster was determined for sublines of an initially highly inbred strain that were maintained by divergent artificial selection for 150 generations or by random mating for 180 generations. Replicate selection lines had more extreme bristle numbers than those that were maintained without artificial selection at the same census size for approximately the same number of generations. The average fitness, estimated by a single generation of competition against a compound autosome strain, was 0.17 for lines selected for high and low abdominal bristle numbers and 0.19 for lines selected for high and low sternopleural bristle number. The average fitness of unselected lines, 0.46, was significantly higher than that of the selection lines. The fitnesses and the relationships of bristle number to fitness in progeny of all possible crosses of high x high (H x H), high x low (H x L) and low x low (L x L) selection lines were examined to determine whether the observed intermediate optima were caused by direct stabilizing selection on bristle number or by apparent stabilizing selection mediated through deleterious pleiotropic fitness effects of mutations affecting bristle number. Although bristle number was nearly additive for progeny of H x H, H x L and L x L crosses among sternopleural bristle selection lines, their mean fitnesses were not significantly different from each other, or from the mean fitness of the unselected lines, suggesting partly or completely recessive pleiotropic fitness effects cause apparent stabilizing selection. The average fitness of the progeny of H x H abdominal bristle selection lines was not significantly different from the fitness of unselected lines, but the mean fitness of the progeny of L x L crosses was not significantly different from that of the pure low lines. This is consistent with direct selection against low but not high abdominal bristle number, but the interpretation is confounded by variation in average degree of dominance for fitness (on average recessive in the high abdominal bristle selection lines and additive in the low abdominal bristle selection lines). Neither direct stabilizing selection nor pleiotropy, therefore, can account for all the observations.

COLONY OF THE FUNGUS Aspergillus oryzae AND SELF-AFFINE FRACTAL GEOMETRY OF GROWTH FRONTS

Fractals ◽  
1993 ◽  
Vol 01 (01) ◽  
pp. 11-19 ◽  
Author(s):  
SHU MATSUURA ◽  
SASUKE MIYAZIMA
Keyword(s):  
Aspergillus Oryzae ◽  
Environmental Conditions ◽  
Fractal Geometry ◽  
Nutrient Concentration ◽  
Incubation Temperature ◽  
Characteristic Exponent ◽  
Growth Front ◽  
Favorable Condition ◽  
The Self ◽  
The Mean

A variety of colony shapes of the fungus Aspergillus oryzae under varying environmental conditions such as the nutrient concentration, medium stiffness and incubation temperature are obtained, ranging from a homogeneous Eden-like to a ramified DLA-like pattern. The roughness σ(l, h) of the growth front of the band-shaped colony, where h is the mean front height within l of the horizontal range, satisfies the self-affine fractal relation under favorable environmental conditions. In the most favorable condition of our experiments, its characteristic exponent is found to be a little larger than that of the 2-dimensional Eden model.

Thermal adaptation of acetic acid bacteria for practical high-temperature vinegar fermentation

2021 ◽  
Vol 85 (5) ◽  
pp. 1243-1251
Author(s):  
Nami Matsumoto ◽  
Naoki Osumi ◽  
Minenosuke Matsutani ◽  
Theerisara Phathanathavorn ◽  
Naoya Kataoka ◽  
...  
Keyword(s):  
Acetic Acid ◽  
High Temperature ◽  
Experimental Evolution ◽  
Culture Medium ◽  
Thermal Adaptation ◽  
Acetic Acid Bacteria ◽  
Acid Fermentation ◽  
Acetic Acid Production ◽  
Fermentation System ◽  
Fermentor Culture

ABSTRACT Thermotolerant microorganisms are useful for high-temperature fermentation. Several thermally adapted strains were previously obtained from Acetobacter pasteurianus in a nutrient-rich culture medium, while these adapted strains could not grow well at high temperature in the nutrient-poor practical culture medium, “rice moromi.” In this study, A. pasteurianus K-1034 originally capable of performing acetic acid fermentation in rice moromi was thermally adapted by experimental evolution using a “pseudo” rice moromi culture. The adapted strains thus obtained were confirmed to grow well in such the nutrient-poor media in flask or jar-fermentor culture up to 40 or 39 °C; the mutation sites of the strains were also determined. The high-temperature fermentation ability was also shown to be comparable with a low-nutrient adapted strain previously obtained. Using the practical fermentation system, “Acetofermenter,” acetic acid production was compared in the moromi culture; the results showed that the adapted strains efficiently perform practical vinegar production under high-temperature conditions.

Whole-Genome Effects of Ethyl Methanesulfonate-Induced Mutation on Nine Quantitative Traits in Outbred Drosophila melanogaster

Genetics ◽  
2001 ◽  
Vol 157 (3) ◽  
pp. 1257-1265 ◽  
Author(s):  
Hsiao-Pei Yang ◽  
Ana Y Tanikawa ◽  
Wayne A Van Voorhies ◽  
Joana C Silva ◽  
Alexey S Kondrashov
Keyword(s):  
Drosophila Melanogaster ◽  
Quantitative Traits ◽  
Spontaneous Mutation ◽  
Developmental Time ◽  
Ethyl Methanesulfonate ◽  
Induced Mutations ◽  
Mean Values ◽  
Eye Color ◽  
Recessive Mutations ◽  
The Mean

Abstract We induced mutations in Drosophila melanogaster males by treating them with 21.2 mm ethyl methanesulfonate (EMS). Nine quantitative traits (developmental time, viability, fecundity, longevity, metabolic rate, motility, body weight, and abdominal and sternopleural bristle numbers) were measured in outbred heterozygous F3 (viability) or F2 (all other traits) offspring from the treated males. The mean values of the first four traits, which are all directly related to the life history, were substantially affected by EMS mutagenesis: the developmental time increased while viability, fecundity, and longevity declined. In contrast, the mean values of the other five traits were not significantly affected. Rates of recessive X-linked lethals and of recessive mutations at several loci affecting eye color imply that our EMS treatment was equivalent to ∼100 generations of spontaneous mutation. If so, our data imply that one generation of spontaneous mutation increases the developmental time by 0.09% at 20° and by 0.04% at 25°, and reduces viability under harsh conditions, fecundity, and longevity by 1.35, 0.21, and 0.08%, respectively. Comparison of flies with none, one, and two grandfathers (or greatgrandfathers, in the case of viability) treated with EMS did not reveal any significant epistasis among the induced mutations.

scholarly journals GENETIC LOAD IN NATURAL POPULATIONS: IS IT COMPATIBLE WITH THE HYPOTHESIS THAT MANY POLYMORPHISMS ARE MAINTAINED BY NATURAL SELECTION?

Genetics ◽  
1974 ◽  
Vol 77 (3) ◽  
pp. 569-589
Author(s):  
Martin L Tracey ◽  
Francisco J Ayala
Keyword(s):  
Drosophila Melanogaster ◽  
Natural Selection ◽  
Natural Population ◽  
Natural Populations ◽  
Genetic Load ◽  
Structural Genes ◽  
Invertebrate Species ◽  
Average Proportion ◽  
Mean Fitness ◽  
The Mean

ABSTRACT Recent studies of genetically controlled enzyme variation lead to an estimation that at least 30 to 60% of the structural genes are polymorphic in natural populations of many vertebrate and invertebrate species. Some authors have argued that a substantial proportion of these polymorphisms cannot be maintained by natural selection because this would result in an unbearable genetic load. If many polymorphisms are maintained by heterotic natural selection, individuals with much greater than average proportion of homozygous loci should have very low fitness. We have measured in Drosophila melanogaster the fitness of flies homozygous for a complete chromosome relative to normal wild flies. A total of 37 chromosomes from a natural population have been tested using 92 experimental populations. The mean fitness of homozygous flies is 0.12 for second chromosomes, and 0.13 for third chromosomes. These estimates are compatible with the hypothesis that many (more than one thousand) loci are maintained by heterotic selection in natural populations of D. melanogaster.

scholarly journals Perioperative Microbial Contamination From Patients on Contact Precaution in Operating Room Environment

2020 ◽  
Vol 41 (S1) ◽  
pp. s348-s349
Author(s):  
Hajime Kanamori ◽  
William Rutala ◽  
Maria Gergen ◽  
David Jay Weber
Keyword(s):  
Small Computer ◽  
Contact Precaution ◽  
Time Points ◽  
Contact Precautions ◽  
Surgery Patient ◽  
Patient Arrival ◽  
The Mean ◽  
Healthcare Associated ◽  
Cleaning And Disinfection ◽  
The Impact

Background: The contaminated healthcare environment, including operating rooms (ORs), can serve as an important role in transmission of healthcare-associated pathogens. Studies are very limited regarding the level of contamination of ORs during the surgery of a patient on contact precautions and the risk to the next surgery patient after standard room cleaning and disinfection. Objective: Here, we investigated the microbial burden on the OR environment when patients on contact precautions receive surgery, and we assessed the impact of cleaning and disinfection on the contamination of OR environmental sites. Methods: This investigation was conducted in the ORs of an academic facility during an 8-month period. It involved 10 patients on contact precautions for multidrug-resistant pathogens, including methicillin-resistant Staphylococcus aureus (MRSA; n = 7); carbapenem-resistant Enterobacteriaceae (CRE) plus MRSA (n = 2); and vancomycin-resistant Enterococcus (VRE) plus MRSA (n = 1), who underwent surgery. Environmental sampling was performed at the following time points: (1) immediately before the surgical patient’s arrival in the OR, (2) after surgery but before the OR cleaning and disinfection, and (3) after the OR cleaning and disinfection. In total, 1,520 environmental samples collected from 15 OR sites for 10 surgical patients at 3 time points were analyzed. Relatedness among environmental MRSA isolates was determined by pulsed-field gel electrophoresis. Results: Overall, the mean CFUs of aerobes per Rodac plate (CFU/25 cm2) were 10.1 before patient arrival, 14.7 before cleaning and disinfection, and 6.3 after cleaning and disinfection (P < .0001, after cleaning and disinfection vs before cleaning and disinfection). Moreover, 7 environmental sites (46.7%) after cleaning and disinfection, including bed, arm rest, pyxis counter, floor (near, door side), floor (far, by door), steel counter (small, near bed), and small computer desk, had significantly lower mean counts of aerobes than before patient arrival or before cleaning and disinfection (Fig. 1). The mean CFUs of MRSA per Rodac plate (CFU/25 cm2) were 0.04 before patient arrival, 0.66 before cleaning and disinfection, and 0.08 after cleaning and disinfection (P = .0006, after cleaning and disinfection vs before cleaning and disinfection). Of environmental sites where MRSA was identified, 87.2% were on floors (41 of 47) and 19.1% were after cleaning and disinfection (9 of 47, 8 from floors and 1 from pyxis touchscreen). The A2/B2 MRSA strain was identified on different environmental sites (eg, floor, computer desk, counter) in various rooms (eg, OR2, OR10, and OR16), even after cleaning and disinfection (Fig. 2). Conclusions: Our study has demonstrated that the OR environment was contaminated with aerobic bacteria and MRSA after surgery and that MRSA persisted in the environment even after cleaning and disinfection. Enhanced environmental cleaning in the perioperative environment used for patients on isolation is necessary to prevent transmission of healthcare-associated pathogens in ORs.Funding: NoneDisclosures: Drs. Rutala and Weber are consultants to PDI (Professional Disposable International)

Étude du développement hétéroblastique chez quelques espèces du genre Medicago

1983 ◽  
Vol 61 (8) ◽  
pp. 2212-2223 ◽  
Author(s):  
Catherine Damerval
Keyword(s):  
Environmental Conditions ◽  
Mean Value ◽  
Annual Species ◽  
The Mean ◽  
Shape Changes

Seven foliar types were defined for the first leaf in the heteroblastic development of seven annual species of Medicago L. Among the species, M. aculeata and M. murex have a typical foliar form. There is no relation between the first leaf and the succeeding trifoliolate one. The shape changes of the middle foliole of the trifoliolate leaves during the development allowed to establish a foliar sequence whose mean length was used to suggest an evolutive hierarchy among the taxa. Five quantitative variables were analysed on the first and on the sixth leaf for stability according to environmental conditions; the two stable variables (L/l and L/Pl) have a best discriminant value for the first leaf than for the sixth one. However, intraspecific heterogeneity is high in both cases. A relation between the flowering precocity and the mean value of one of the sixth leaf's variables (that is, the ratio of the length to the width of the foliole limb) was demonstrated in four species only. The heteroblastic development not only allows to establish a relation between foliar stage and physiologic age, but it itself constitutes a very good taxonomic and systematic criterium; it allowed to identify the seven species studied.

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