scholarly journals On the mod resc Model and the Evolution of Wolbachia Compatibility Types

Genetics ◽  
2001 ◽  
Vol 159 (4) ◽  
pp. 1415-1422 ◽  
Author(s):  
Sylvain Charlat ◽  
Claire Calmet ◽  
Hervé Merçot
Keyword(s):  
Cytoplasmic Incompatibility ◽  
Natural Populations ◽  
Evolutionary Process ◽  
Embryonic Mortality ◽  
Step Process ◽  
Zygote Development ◽  
Specific Manner

Abstract Cytoplasmic incompatibility (CI) is induced by the endocellular bacterium Wolbachia. It results in an embryonic mortality occurring when infected males mate with uninfected females. The mechanism involved is currently unknown, but the mod resc model allows interpretation of all observations made so far. It postulates the existence of two bacterial functions: modification (mod) and rescue (resc). The mod function acts in the males' germline, before Wolbachia are shed from maturing sperm. If sperm is affected by mod, zygote development will fail unless resc is expressed in the egg. Interestingly, CI is also observed in crosses between infected males and infected females when the two partners bear different Wolbachia strains, demonstrating that mod and resc interact in a specific manner: Two Wolbachia strains are compatible with each other only if they harbor the same compatibility type. Here we focus on the evolutionary process involved in the emergence of new compatibility types from ancestral ones. We argue that new compatibility types are likely to evolve under a wider range of conditions than previously thought, through a two-step process. First, new mod variants can arise by mutation and spread by drift. This is possible because mod is expressed in males and Wolbachia is transmitted by females. Second, once such a mod variant achieves a certain frequency, it can create the conditions for the deterministic invasion of a new resc variant, allowing the invasion of a new mod resc pair. Furthermore, we show that a stable polymorphism might be maintained in natural populations, allowing the long-term existence of “suicidal” Wolbachia strains.

Specific features of long-term domestication of australian crayfish Cherax quadricarinatus in conditions of the western part of Russian Federation

2018 ◽  
Vol 194 ◽  
pp. 188-192
Author(s):  
D. I. Shokasheva
Keyword(s):  
Natural Selection ◽  
Russian Federation ◽  
Natural Populations ◽  
Cherax Quadricarinatus ◽  
Local Environments ◽  
Local Species ◽  
Adaptive Ability

Natural populations of crayfish are in depression in Russia and local species are not cultivated. In this situation, experimental cultivation of allochtonous australian crayfish Cherax quadricarinatus is conducted. This species is distinguished by high reproductive abilities and good consumer properties. It has domesticated in Russia spontaneously and produced 9–10 generations in Astrakhan Region. Certain natural selection in the process of domestication provides adaptive ability of this species to local environments and its capabil­ity to reproduce a viable progeny, so there is no doubts in good prospects of its cultivation in industrial conditions.

Update on the Boundaries of the Curly Birch Range

2020 ◽  
pp. 9-21
Author(s):  
L.V. Vetchinnikova ◽  
◽  
A.F. Titov ◽  
◽  
Keyword(s):  
Population Size ◽  
Natural Populations ◽  
Forest Tree ◽  
Published Data ◽  
Population Approach ◽  
Key Factors ◽  
History Of ◽  
Individual Trees ◽  
Karelian Birch

The article reports on the application of the best known principles for mapping natural populations of curly (Karelian) birch Betula pendula Roth var. carelica (Mercklin) Hämet-Ahti – one of the most appealing representatives of the forest tree flora. Relying on the synthesis and analysis of the published data amassed over nearly 100 years and the data from own full-scale studies done in the past few decades almost throughout the area where curly birch has grown naturally, it is concluded that its range outlined in the middle of the 20th century and since then hardly revised is outdated. The key factors and reasons necessitating its revision are specified. Herewith it is suggested that the range is delineated using the population approach, and the key element will be the critical population size below which the population is no longer viable in the long term. This approach implies that the boundaries of the taxon range depend on the boundaries of local populations (rather than the locations of individual trees or small clumps of trees), the size of which should not be lower than the critical value, which is supposed to be around 100–500 trees for curly birch. A schematic map of the curly birch range delineated using this approach is provided. We specially address the problem of determining the minimum population size to secure genetic diversity maintenance. The advantages of the population approach to delineating the distribution range of curly birch with regard to its biological features are highlighted. The authors argue that it enables a more accurate delineation of the range; shows the natural evolutionary history of the taxon (although it is not yet officially recognized as a species) and its range; can be relatively easily updated (e.g. depending on the scope of reintroduction); should be taken into account when working on the strategy of conservation and other actions designed to maintain and regenerate this unique representative of the forest tree flora.

Wolbachia and Cytoplasmic Incompatibility in the CaliforniaCulex pipiensMosquito Species Complex: Parameter Estimates and Infection Dynamics in Natural Populations

Genetics ◽  
2003 ◽  
Vol 165 (4) ◽  
pp. 2029-2038 ◽  
Author(s):  
Jason L Rasgon ◽  
Thomas W Scott
Keyword(s):  
Species Complex ◽  
Cytoplasmic Incompatibility ◽  
Natural Populations ◽  
Wolbachia Infection ◽  
Field Conditions ◽  
Parameter Estimates ◽  
Infection Prevalence ◽  
Infection Frequency ◽  
Specific Pcr ◽  
Vector Borne

AbstractBefore maternally inherited bacterial symbionts like Wolbachia, which cause cytoplasmic incompatibility (CI; reduced hatch rate) when infected males mate with uninfected females, can be used in a program to control vector-borne diseases it is essential to understand their dynamics of infection in natural arthropod vector populations. Our study had four goals: (1) quantify the number of Wolbachia strains circulating in the California Culex pipiens species complex, (2) investigate Wolbachia infection frequencies and distribution in natural California populations, (3) estimate the parameters that govern Wolbachia spread among Cx. pipiens under laboratory and field conditions, and (4) use these values to estimate equilibrium levels and compare predicted infection prevalence levels to those observed in nature. Strain-specific PCR, wsp gene sequencing, and crossing experiments indicated that a single Wolbachia strain infects Californian Cx. pipiens. Infection frequency was near or at fixation in all populations sampled for 2 years along a >1000-km north-south transect. The combined statewide infection frequency was 99.4%. Incompatible crosses were 100% sterile under laboratory and field conditions. Sterility decreased negligibly with male age in the laboratory. Infection had no significant effect on female fecundity under laboratory or field conditions. Vertical transmission was >99% in the laboratory and ∼98.6% in the field. Using field data, models predicted that Wolbachia will spread to fixation if infection exceeds an unstable equilibrium point above 1.4%. Our estimates accurately predicted infection frequencies in natural populations. If certain technical hurdles can be overcome, our data indicate that Wolbachia can invade vector populations as part of an applied transgenic strategy for vector-borne disease reduction.

scholarly journals Contrasting Patterns of Virus Protection and Functional Incompatibility Genes in Two ConspecificWolbachiaStrains fromDrosophila pandora

2018 ◽  
Vol 85 (5) ◽  
Author(s):  
Angelique K. Asselin ◽  
Simon Villegas-Ospina ◽  
Ary A. Hoffmann ◽  
Jeremy C. Brownlie ◽  
Karyn N. Johnson
Keyword(s):  
Disease Transmission ◽  
Cytoplasmic Incompatibility ◽  
Natural Populations ◽  
Differential Protection ◽  
Content Type ◽  
Infection Dynamics ◽  
Modification Factor ◽  
Control Disease ◽  
Multiple Strains ◽  
High Degree

ABSTRACTWolbachiainfections can present different phenotypes in hosts, including different forms of reproductive manipulation and antiviral protection, which may influence infection dynamics within host populations. In populations ofDrosophila pandoratwo distinctWolbachiastrains coexist, each manipulating host reproduction: strainwPanCI causes cytoplasmic incompatibility (CI), whereas strainwPanMK causes male killing (MK). CI occurs when aWolbachia-infected male mates with a female not infected with a compatible type ofWolbachia, leading to nonviable offspring.wPanMK can rescuewPanCI-induced CI but is unable to induce CI. The antiviral protection phenotypes provided by thewPanCI andwPanMK infections were characterized; the strains showed differential protection phenotypes, whereby cricket paralysis virus (CrPV)-induced mortality was delayed in flies infected withwPanMK but enhanced in flies infected withwPanCI compared to their respectiveWolbachia-cured counterparts. Homologs of thecifAandcifBgenes involved in CI identified inwPanMK andwPanCI showed a high degree of conservation; however, the CifB protein inwPanMK is truncated and is likely nonfunctional. The presence of a likely functional CifA inwPanMK andwPanMK’s ability to rescuewPanCI-induced CI are consistent with the recent confirmation of CifA’s involvement in CI rescue, and the absence of a functional CifB protein further supports its involvement as a CI modification factor. Taken together, these findings indicate thatwPanCI andwPanMK have different relationships with their hosts in terms of their protective and CI phenotypes. It is therefore likely that different factors influence the prevalence and dynamics of these coinfections in naturalDrosophila pandorahosts.IMPORTANCEWolbachiastrains are common endosymbionts in insects, with multiple strains often coexisting in the same species. The coexistence of multiple strains is poorly understood but may rely onWolbachiaorganisms having diverse phenotypic effects on their hosts. AsWolbachiais increasingly being developed as a tool to control disease transmission and suppress pest populations, it is important to understand the ways in which multipleWolbachiastrains persist in natural populations and how these might then be manipulated. We have therefore investigated viral protection and the molecular basis of cytoplasmic incompatibility in two coexistingWolbachiastrains with contrasting effects on host reproduction.

scholarly journals The Relative Kicking Frequency of Infants Born Full-term and Preterm During Learning and Short-term and Long-term Memory Periods of the Mobile Paradigm

2005 ◽  
Vol 85 (1) ◽  
pp. 8-18 ◽  
Author(s):  
Jill C Heathcock ◽  
Anjana N Bhat ◽  
Michele A Lobo ◽  
James (Cole) Galloway
Keyword(s):  
Gestational Age ◽  
Short Term Memory ◽  
Full Term ◽  
Long Term Memory ◽  
Early Assessment ◽  
Short Term ◽  
Term Memory ◽  
Lack Of Control ◽  
Specific Manner

Abstract Background and Purpose. Infants born preterm differ in their spontaneous kicking, as well as their learning and memory abilities in the mobile paradigm, compared with infants born full-term. In the mobile paradigm, a supine infant's ankle is tethered to a mobile so that leg kicks cause a proportional amount of mobile movement. The purpose of this study was to investigate the relative kicking frequency of the tethered (right) and nontethered (left) legs in these 2 groups of infants. Subjects. Ten infants born full-term and 10 infants born preterm (<33 weeks gestational age, <2,500 g) and 10 comparison infants participated in the study. Methods. The relative kicking frequencies of the tethered and nontethered legs were analyzed during learning and short-term and long-term memory periods of the mobile paradigm. Results. Infants born full-term showed an increase in the relative kicking frequency of the tethered leg during the learning period and the short-term memory period but not for the long-term memory period. Infants born preterm did not show a change in kicking pattern for learning or memory periods, and consistently kicked both legs in relatively equal amounts. Discussion and Conclusion. Infants born full-term adapted their baseline kicking frequencies in a task-specific manner to move the mobile and then retained this adaptation for the short-term memory period. In contrast, infants born preterm showed no adaptation, suggesting a lack of purposeful leg control. This lack of control may reflect a general decrease in the ability of infants born preterm to use their limb movements to interact with their environment. As such, the mobile paradigm may be clinically useful in the early assessment and intervention of infants born preterm and at risk for future impairment.

scholarly journals Monitoring of fish diseases in the Magadan region

2021 ◽  
Vol 36 ◽  
pp. 07008
Author(s):  
E.A. Vitomskova
Keyword(s):  
Pacific Salmon ◽  
Animal Health ◽  
Natural Populations ◽  
Clinical Signs ◽  
Commercial Fish ◽  
Fish Diseases ◽  
North East ◽  
Comparative Aspect ◽  
Different Seasons

In such a large region as the Far North-East of Russia, there is still no purposeful ichthyopathological study of fish diseases, which has epizootic and epidemiological significance. The material for the study was commercial fish caught in different seasons of 1995-2021. As a result of the research, individuals of natural populations and in aquaculture with clinical signs of infectious and parasitic diseases were found, and cultures of virulent strains of microorganisms were isolated. According to the results of the parasitological study, larvae of nematodes of the family Anisakidae and plerocercoids of cestodes Diphyllobothriidae, which have important epidemiological and epizootic significance, were registered. Based on long-term ichthyopathological studies, a retrospective review of own data was carried out. The analysis of infectious diseases of mature individuals of anadromous Pacific salmon of the genus Oncorhynchus, as well as long-term parasitological monitoring in a comparative aspect of the invasion of commercial fish by helminths dangerous to human and animal health, is presented.

scholarly journals Spatio-temporal ecological and evolutionary dynamics in natural butterfly populations

2017 ◽  
Vol 40 ◽  
pp. 31-36
Author(s):  
Zachariah Gompert ◽  
Lauren Lucas
Keyword(s):  
Evolutionary Dynamics ◽  
Natural Populations ◽  
Distance Sampling ◽  
Spatial And Temporal Variation ◽  
Insect Community ◽  
Long Term Study ◽  
Greater Yellowstone Area ◽  
Genome Wide ◽  
Spatio Temporal

Long term studies of wild populations indicate that natural selection can cause rapid and dramatic changes in traits, with spatial and temporal variation in the strength of selection a critical driver of genetic variation in natural populations. In 2012, we began a long term study of genome-wide molecular evolution in populations of the butterfly Lycaeides ideas in the Greater Yellowstone Area (GYA). We aimed to quantify the role of environment-dependent selection on evolution in these populations. Building on previous work, in 2017 we collected new samples, incorporated distance sampling, and surveyed the insect community at each site. We also defined the habitat boundary at anew, eleventh site. Our preliminary analyses suggest that both genetic drift and selection are important drivers in this system.   Featured photo from Figure 1 in report.

scholarly journals Ploidy frequencies in plants with ploidy heterogeneity: fitting a general gametic model to empirical population data

2013 ◽  
Vol 280 (1751) ◽  
pp. 20122387 ◽  
Author(s):  
Jan Suda ◽  
Tomáš Herben
Keyword(s):  
Natural Populations ◽  
Evolutionary Process ◽  
Optimization Procedure ◽  
Population Data ◽  
Unreduced Gametes ◽  
Unreduced Gamete ◽  
Model Parameters ◽  
Main Mode ◽  
Ploidy Levels ◽  
Polyploid Formation

Genome duplication (polyploidy) is a recurrent evolutionary process in plants, often conferring instant reproductive isolation and thus potentially leading to speciation. Outcome of the process is often seen in the field as different cytotypes co-occur in many plant populations. Failure of meiotic reduction during gametogenesis is widely acknowledged to be the main mode of polyploid formation. To get insight into its role in the dynamics of polyploidy generation under natural conditions, and coexistence of several ploidy levels, we developed a general gametic model for diploid–polyploid systems. This model predicts equilibrium ploidy frequencies as functions of several parameters, namely the unreduced gamete proportions and fertilities of higher ploidy plants. We used data on field ploidy frequencies for 39 presumably autopolyploid plant species/populations to infer numerical values of the model parameters (either analytically or using an optimization procedure). With the exception of a few species, the model fit was very high. The estimated proportions of unreduced gametes (median of 0.0089) matched published estimates well. Our results imply that conditions for cytotype coexistence in natural populations are likely to be less restrictive than previously assumed. In addition, rather simple models show sufficiently rich behaviour to explain the prevalence of polyploids among flowering plants.

scholarly journals Reelin deficiency contributes to long-term behavioral abnormalities induced by chronic adolescent exposure to Δ9-tetrahydrocannabinol in mice

2020 ◽  
Author(s):  
Attilio Iemolo ◽  
Aisha Nur ◽  
Patricia Montilla-Perez ◽  
Victoria B Risbrough ◽  
Francesca Telese
Keyword(s):  
Psychiatric Disorders ◽  
Emotional Reactivity ◽  
Lateral Septum ◽  
Early Gene ◽  
Novelty Seeking ◽  
Behavioral Abnormalities ◽  
Specific Manner ◽  
The Brain ◽  
Adolescent Exposure

AbstractHeavy and frequent use of cannabis during adolescence increases the risk of developing psychiatric disorders. However, the neurobiological mechanisms underlying this vulnerability remain largely unknown. Here, we explore whether adolescent vulnerability to long-term behavioral effects of cannabis is modulated by Reelin, a gene implicated in the development of the brain and of psychiatric disorders. To this aim, heterozygous Reeler (HR) mice, that express reduced level of Reelin, were chronically exposed during adolescence to high doses (10mg/kg) of Δ9-tetrahydrocannabinol (THC), a major psychoactive component of cannabis. Mice were tested in early adulthood with multiple behavioral assays, including working memory, social interaction, locomotor activity, anxiety-like responses, stress reactivity, and pre-pulse inhibition. Compared to wild-type (WT), HR mice treated with THC showed impaired social behaviors, elevated disinhibitory phenotypes and increased responsiveness to aversive situations, in a sex-specific manner. Independent of THC exposure, HR mice also spent more time exploring unfamiliar objects, indicating that Reelin modulates novelty seeking behavior. To identify the neuronal ensemble underlying this elevated novelty seeking in HR mice, we mapped the regional brain expression of the immediate early gene, Fos, in mice exposed to novel objects. HR mice exhibited reduced neuronal activation in the lateral septum, a subcortical brain structure implicated in emotions, cognition and reward processes. Overall, these findings show that (1) Reelin deficiency influences behavioral abnormalities caused by heavy consumption of THC during adolescence, and (2) that Reelin plays a role in the neurobiological mechanisms underlying disinhibitory behaviors, such as novelty seeking.Significant StatementThe link between cannabis abuse and the development psychiatric disorders, especially in adolescents, makes understanding the neurobiological mechanisms underlying cannabis effects on the brain a significant biomedical problem. Reelin is a key signaling molecule in the development of the adolescent brain and of psychiatric disorders, but its role in modulating the behavioral changes induced by cannabis remain unknown. Here, we report an interaction between Reelin deficiency and chronic adolescent exposure to THC, a major psychoactive component of cannabis. This interaction led to cognitive deficits, disinhibitory behaviors and altered emotional reactivity in mice, in a sex-specific manner. These experiments are the first to establish a link between Reelin signaling and the endocannabinoid system targeted by THC.

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