Random environmental variation and inbreeding: effects on pure-strain and hybrid populations of flour beetles (Tribolium)

1986 ◽  
Vol 28 (6) ◽  
pp. 889-898 ◽  
Author(s):  
David Wool ◽  
Orna Bergerson
Keyword(s):  
Environmental Variation ◽  
Single Pair ◽  
Wild Type ◽  
Flour Beetles ◽  
Fitness Trait ◽  
Wild Type Female ◽  
Order Of Magnitude ◽  
Selection For ◽  
Varying Environment ◽  
Type Strains

The effect of inbreeding and of random environmental variation on fitness characters was studied in small populations derived from 10 inbred laboratory strains of Tribolium castaneum (I) and in 18 hybrids (IH) populations, obtained by crossing six mutant to three wild-type strains. Replicate population of each type were held in a constant (C) and a randomly varying (V) environment. Each replicate population was founded by a single pair of adults and one pair of sibs founded each subsequent generation. Thus four groups of inbreeding populations were created: IC, IV, IHC, and IHV. Outbred hybrid populations were held in the varying environment (OV). Several fitness characters were measured. The results confirmed that inbreeding populations exposed to random environmental variation had lower fitness than similar populations in the constant environment populations, as expected (IHC > IHV, IC > IV for each fitness trait). The environmental stress did not result in selection for individuals with higher fitness. In the hybrid populations, consistent and significant differences in fitness between populations having different wild-type (female) ancestors persisted for several generations. No such differences were found among populations grouped by their mutant ancestor. Within each environment, inbreeding had a pronounced effect on fitness. The order of magnitude of the fitness characters was IHC > IC, OV > IHV > IV, parallel to the level of inbreeding. Directional changes in relative (rank) magnitude of fitness characters among populations suggested that their genetic composition was changing temporally.Key words: Tribolium, selection, fitness, inbreedig, population.

scholarly journals Absence of strong heterosis for life span and other life history traits in Caenorhabditis elegans.

Genetics ◽  
1993 ◽  
Vol 134 (2) ◽  
pp. 465-474 ◽  
Author(s):  
T E Johnson ◽  
E W Hutchinson
Keyword(s):  
Life History ◽  
Caenorhabditis Elegans ◽  
Life Span ◽  
Life History Traits ◽  
Environmental Variation ◽  
F1 Hybrids ◽  
Wild Type ◽  
Wild Strains ◽  
And Behavior ◽  
Type Strains

Abstract We have examined crosses between wild-type strains of Caenorhabditis elegans for heterosis effects on life span and other life history traits. Hermaphrodites of all wild strains had similar life expectancies but males of two strains had shorter life spans than hermaphrodites while males of two other strains lived longer than hermaphrodites. F1 hermaphrodite progeny showed no heterosis while some heterosis for longer life span was detected in F1 males. F1 hybrids of crosses between two widely studied wild-type strains, N2 (var. Bristol) and Berg BO (var. Bergerac), were examined for rate of development, hermaphrodite fertility, and behavior; there was no heterosis for these life history traits. Both controlled variation of temperature and uncontrolled environmental variation affected the length of life of all genotypes. Significant G x E effects on life span were observed in comparisons of N2 and Berg BO hermaphrodites, or N2 hermaphrodites and males, or N2 and a Ts mutant strain (DH26). Nevertheless, within an experiment, environmental variation was minimal and life spans were quite replicable.

scholarly journals Use of the alr Gene as a Food-Grade Selection Marker in Lactic Acid Bacteria

2002 ◽  
Vol 68 (11) ◽  
pp. 5663-5670 ◽  
Author(s):  
Peter A. Bron ◽  
Marcos G. Benchimol ◽  
Jolanda Lambert ◽  
Emmanuelle Palumbo ◽  
Marie Deghorain ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Competitive Inhibitor ◽  
Selection Marker ◽  
Wild Type ◽  
Gene Encoding ◽  
Food Grade ◽  
Selection For ◽  
Isogenic Mutants ◽  
Type Strains

ABSTRACT Both Lactococcus lactis and Lactobacillus plantarum contain a single alr gene, encoding an alanine racemase (EC 5.1.1.1), which catalyzes the interconversion of d-alanine and l-alanine. The alr genes of these lactic acid bacteria were investigated for their application as food-grade selection markers in a heterologous complementation approach. Since isogenic mutants of both species carrying an alr deletion (Δalr) showed auxotrophy for d-alanine, plasmids carrying a heterologous alr were constructed and could be selected, since they complemented d-alanine auxotrophy in the L. plantarum Δalr and L. lactis Δalr strains. Selection was found to be highly stringent, and plasmids were stably maintained over 200 generations of culturing. Moreover, the plasmids carrying the heterologous alr genes could be stably maintained in wild-type strains of L. plantarum and L. lactis by selection for resistance to d-cycloserine, a competitive inhibitor of Alr (600 and 200 μg/ml, respectively). In addition, a plasmid carrying the L. plantarum alr gene under control of the regulated nisA promoter was constructed to demonstrate that d-cycloserine resistance of L. lactis is linearly correlated to the alr expression level. Finally, the L. lactis alr gene controlled by the nisA promoter, together with the nisin-regulatory genes nisRK, were integrated into the chromosome of L. plantarum Δalr. The resulting strain could grow in the absence of d-alanine only when expression of the alr gene was induced with nisin.

scholarly journals Recombinational instability of a chimeric plasmid in Saccharomyces cerevisiae.

1984 ◽  
Vol 4 (1) ◽  
pp. 195-198 ◽  
Author(s):  
M S Whiteway ◽  
A Ahmed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mitotic Recombination ◽  
Wild Type ◽  
Recombination System ◽  
Sequence Homologies ◽  
Selection For ◽  
Derivative Plasmid ◽  
Type Strains ◽  
Chromosomal Recombination ◽  
Site Specific Recombination System

Wild-type strains of Saccharomyces cerevisiae exhibit mitotic recombination between the chimeric plasmid TLC-1 and the endogenous 2mu circle that involves sequence homologies between the two plasmids that are not acted on by the 2mu circle site-specific recombination system. This generalized recombination can be detected because it separates the LEU2 and CAN1 markers of TLC-1 from each other through the formation of a plasmid containing only the S. cerevisiae LEU2 region and the 2mu circle. This derivative plasmid is maintained more stably during vegetative growth than TLC-1, and strains which carry it frequently lose the endogenous 2mu circle. Therefore, TLC-1 can provide a convenient selection for [cir0] cells. Formation of this new plasmid is greatly reduced, but not eliminated, in strains containing the rad52-1 mutation. This indicates that generalized mitotic recombination between plasmid sequences utilizes functions required for chromosomal recombination in S. cerevisiae.

Recombinational instability of a chimeric plasmid in Saccharomyces cerevisiae

1984 ◽  
Vol 4 (1) ◽  
pp. 195-198
Author(s):  
M S Whiteway ◽  
A Ahmed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Mitotic Recombination ◽  
Wild Type ◽  
Recombination System ◽  
Sequence Homologies ◽  
Selection For ◽  
Derivative Plasmid ◽  
Type Strains ◽  
Chromosomal Recombination ◽  
Site Specific Recombination System

Wild-type strains of Saccharomyces cerevisiae exhibit mitotic recombination between the chimeric plasmid TLC-1 and the endogenous 2mu circle that involves sequence homologies between the two plasmids that are not acted on by the 2mu circle site-specific recombination system. This generalized recombination can be detected because it separates the LEU2 and CAN1 markers of TLC-1 from each other through the formation of a plasmid containing only the S. cerevisiae LEU2 region and the 2mu circle. This derivative plasmid is maintained more stably during vegetative growth than TLC-1, and strains which carry it frequently lose the endogenous 2mu circle. Therefore, TLC-1 can provide a convenient selection for [cir0] cells. Formation of this new plasmid is greatly reduced, but not eliminated, in strains containing the rad52-1 mutation. This indicates that generalized mitotic recombination between plasmid sequences utilizes functions required for chromosomal recombination in S. cerevisiae.

scholarly journals Resistance to amino acid analogues in Coprinus: Dominance modifier genes and dominance reversal in dikaryons and diploids

1975 ◽  
Vol 25 (2) ◽  
pp. 95-107 ◽  
Author(s):  
S. Senathirajah ◽  
D. Lewis
Keyword(s):  
Carboxylic Acid ◽  
Single Gene ◽  
Modifier Genes ◽  
Wild Type ◽  
Recessive Resistance ◽  
Amino Acid Analogues ◽  
Resistant Mutants ◽  
Selection For ◽  
Oligomeric Product ◽  
Type Strains

SUMMARYWild-type strains of Coprinus lagopus are sensitive to para-fluoro-phenylalanine and ethionine. Resistant mutants to these two analogues are known but all these mutants are recessive in a heterozygous dikaryon except for F7 (pfpr-3) which is semi-dominant. Resistance to two other analogues, however – canavanine sulphate and azetidine-2-carboxylic acid – were found to be wild-type features. One strain of C. lagopus sensitive to canavanine was identified. Selection for canavanine resistance in monokaryons always yielded only dominant resistance, while selection for para-fluorophenylalanine resistance in monokaryons gave only recessive resistance. Canavanine-resistant mutants were due to a single gene mutation which, like the wild-type resistance, were dominant in heterozygous dikaryons. The wild-type resistance was also dominant in a diploid but the mutant resistance was recessive. Selection for resistance to para-fluorophenylalanine in auxotrophically balanced dikaryons resulted in the identification of two new loci (pfpr-10 and pfpr-ll), and two specific dominance modifiers (mod+-10 and mod+-ll). In the absence of the specific modifier, pfpr-10 and pfpr-ll were recessive while, in the presence of even one dose of the specific modifier, resistance was dominant in the dikaryon. The pfpr-10 and pfpr-ll even in the presence of two doses of modifier were fully recessive in the diploid. The action of the modifier genes and the reversal of dominance in dikaryon and diploid is discussed in terms of negative complementation in an oligomeric product of the pfpr gene and localized translation of the relevant mRNA in the cell with the modifier acting as a reinforcer of localization.

129 Genomic Relationship Between PRRSV Wild-type Infection and PRRSV Vaccination for Antibody Response and Reproductive Performance

2021 ◽  
Vol 99 (Supplement_1) ◽  
pp. 18-18
Author(s):  
Leticia P Sanglard ◽  
Felipe Hickmann ◽  
Yijian Huang ◽  
Kent A Gray ◽  
Daniel Linhares ◽  
...  
Keyword(s):  
Antibody Response ◽  
Reproductive Performance ◽  
Genetic Correlations ◽  
Clinical Signs ◽  
Respiratory Syndrome Virus ◽  
Wild Type ◽  
Large White ◽  
Selection For ◽  
Indicator Trait ◽  
Type Infection

Abstract Immunoglobulin G antibody response, measured as sample-to-positive (S/P) ratio, to Porcine Reproductive and Respiratory Syndrome virus (PRRSV) has been proposed as an indicator trait for improved reproductive performance in PRRSV-infected purebred sows and PRRSV-vaccinated crossbred gilts. In this study, we investigated the genetic correlations (rg) of S/P ratio following a PRRSV outbreak and PRRSV-vaccination with performance in non-exposed and PRRSV-exposed sows. PRRSV outbreak phase was defined based on previously described methodologies after the detection of typical clinical signs of PRRSV infection. 541 Landrace sows had S/P ratio measured at ~54 days after the beginning of the PRRSV outbreak (S/Poutbreak), and 906 Landrace x Large White naïve F1 gilts had S/P ratio measured at ~50 days after vaccination with a commercial modified live PRRSV vaccine (S/PVx). 711 and 428 Landrace sows had reproductive performance recorded before and during the PRRSV outbreak, respectively. 811 vaccinated F1 animals had farrowing performance for up to 3 parities. All animals were genotyped for ~28K SNPs. The estimate of rg of S/Poutbreakwith S/PVx was high (rg±SE = 0.72±0.18). Estimates of rg of S/Poutbreak with reproductive performance in F1 sows were low to moderate, ranging from 0.05±0.23 (number stillborn) to 0.30±0.20 (total number born). Estimates of rg of S/PVxwith reproductive performance in non-infected purebred sows were moderate and favorable with number born alive (0.50±0.23), but low (0 to -0.11±0.23) with litter mortality traits. Estimates of rg of S/PVx were moderate and negative (-0.47±0.18) with the number of mummies in PRRSV-infected purebred sows and low with other traits (-0.29±0.18 for total number born to 0.05±0.18 for number stillborn). These results indicate that selection for antibody response following a PRRSV outbreak collected in purebred sows and to PRRSV vaccination collected in commercial crossbred gilts may increase litter size of non-infected and PRRSV-exposed purebred and commercial crossbred sows.

scholarly journals Identification ofvib-1, a Locus Involved in Vegetative Incompatibility Mediated byhet-cinNeurospora crassa

Genetics ◽  
2002 ◽  
Vol 162 (1) ◽  
pp. 89-101 ◽  
Author(s):  
Qijun Xiang ◽  
N Louise Glass
Keyword(s):  
Acid Phosphatase ◽  
Recognition System ◽  
Deletion Mutants ◽  
Wild Type ◽  
Vegetative Incompatibility ◽  
Death Rates ◽  
Self Recognition ◽  
Allelic Differences ◽  
Native Gel ◽  
Type Strains

AbstractA non-self-recognition system called vegetative incompatibility is ubiquitous in filamentous fungi and is genetically regulated by het loci. Different fungal individuals are unable to form viable heterokaryons if they differ in allelic specificity at a het locus. To identify components of vegetative incompatibility mediated by allelic differences at the het-c locus of Neurospora crassa, we isolated mutants that suppressed phenotypic aspects of het-c vegetative incompatibility. Three deletion mutants were identified; the deletions overlapped each other in an ORF named vib-1 (vegetative incompatibility blocked). Mutations in vib-1 fully relieved growth inhibition and repression of conidiation conferred by het-c vegetative incompatibility and significantly reduced hyphal compartmentation and death rates. The vib-1 mutants displayed a profuse conidiation pattern, suggesting that VIB-1 is a regulator of conidiation. VIB-1 shares a region of similarity to PHOG, a possible phosphate nonrepressible acid phosphatase in Aspergillus nidulans. Native gel analysis of wild-type strains and vib-1 mutants indicated that vib-1 is not the structural gene for nonrepressible acid phosphatase, but rather may regulate nonrepressible acid phosphatase activity.

scholarly journals HET-E and HET-D Belong to a New Subfamily of WD40 Proteins Involved in Vegetative Incompatibility Specificity in the Fungus Podospora anserina

Genetics ◽  
2002 ◽  
Vol 161 (1) ◽  
pp. 71-81
Author(s):  
Eric Espagne ◽  
Pascale Balhadère ◽  
Marie-Louise Penin ◽  
Christian Barreau ◽  
Béatrice Turcq
Keyword(s):  
Genetic Difference ◽  
Podospora Anserina ◽  
Wild Type ◽  
Incompatible Interaction ◽  
Vegetative Incompatibility ◽  
Repeat Domain ◽  
Upper Face ◽  
E1a Gene ◽  
Type Strains ◽  
Wd40 Repeats

Abstract Vegetative incompatibility, which is very common in filamentous fungi, prevents a viable heterokaryotic cell from being formed by the fusion of filaments from two different wild-type strains. Such incompatibility is always the consequence of at least one genetic difference in specific genes (het genes). In Podospora anserina, alleles of the het-e and het-d loci control heterokaryon viability through genetic interactions with alleles of the unlinked het-c locus. The het-d2Y gene was isolated and shown to have strong similarity with the previously described het-e1A gene. Like the HET-E protein, the HET-D putative protein displayed a GTP-binding domain and seemed to require a minimal number of 11 WD40 repeats to be active in incompatibility. Apart from incompatibility specificity, no other function could be identified by disrupting the het-d gene. Sequence comparison of different het-e alleles suggested that het-e specificity is determined by the sequence of the WD40 repeat domain. In particular, the amino acids present on the upper face of the predicted β-propeller structure defined by this domain may confer the incompatible interaction specificity.

scholarly journals Isolation of a gene required for programmed initiation of development by Aspergillus nidulans.

1992 ◽  
Vol 12 (9) ◽  
pp. 3827-3833 ◽  
Author(s):  
T H Adams ◽  
W A Hide ◽  
L N Yager ◽  
B N Lee
Keyword(s):  
Life Cycle ◽  
Aspergillus Nidulans ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Nutrient Deprivation ◽  
Deletion Mutants ◽  
Wild Type ◽  
Microbial Development ◽  
Type Strains ◽  
Posttranscriptional Level

In contrast to many other cases in microbial development, Aspergillus nidulans conidiophore production initiates primarily as a programmed part of the life cycle rather than as a response to nutrient deprivation. Mutations in the acoD locus result in "fluffy" colonies that appear to grow faster than the wild type and proliferate as undifferentiated masses of vegetative cells. We show that unlike wild-type strains, acoD deletion mutants are unable to make conidiophores under optimal growth conditions but can be induced to conidiate when growth is nutritionally limited. The requirement for acoD in conidiophore development occurs prior to activation of brlA, a primary regulator of development. The acoD transcript is present both in vegetative hyphae prior to developmental induction and in developing cultures. However, the effects of acoD mutations are detectable only after developmental induction. We propose that acoD activity is primarily controlled at the posttranscriptional level and that it is required to direct developmentally specific changes that bring about growth inhibition and activation of brlA expression to result in conidiophore development.

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