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At least 19 recordsLinked to original sources
PubMed1977

Segregation of cytoplasmic incompatibility properties in Culex pipiens fatigans.

Maternally inherited variants, which arose within a laboratory colony of Culex pipiens fatigans, have been studied by rearing cultures from single egg rafts. Segregation, i.e, variation of cytoplasmic incompatibility properties between the male progeny of individual females, was demonstrated. Also, from the daughters of individual females, sub-lines were derived within which all the males showed the same incompatibility or compatibility properties. Among the descendants of tetracycline-treated individuals were lines which superficially simulated these phenomena, but theses lines ultimately reverted to the cytoplasmic compatibility type of the strain which was submitted to the treatment. The types of variation s in cytoplasmic incompatibility properties that have been studied are discussed.

Animals↗
PubMed2026

Wolbachia strain wLhui induces temperature-dependent incomplete cytoplasmic incompatibility in the invasive pest Liriomyza huidobrensis with biocontrol potential.

BACKGROUND: Wolbachia is a maternally inherited endosymbiont that manipulates host reproduction through cytoplasmic incompatibility (CI), offering promising opportunities for biocontrol of agricultural pests. The leaf-miner Liriomyza huidobrensis (Blanchard) is a globally invasive and highly polyphagous pest with a high incidence of Wolbachia infection; however, its reproductive effects remain poorly understood. Here, we investigated the reproductive manipulation induced by the Wolbachia strain wLhui using genomics analyses and crossing assays. RESULTS: wLhui localized primarily to the reproductive tissues of both female and male adults and maintained a 100% infection prevalence across three host generations under both low (15 and 20 °C) and moderate (25 °C) temperatures. Crossing assays showed that wLhui induced incomplete CI, reducing egg hatch by approximately 30% in incompatible crosses. Both CI strength (sh) and wLhui density varied with host rearing temperature. Genome sequencing revealed that wLhui (approximately 1.27 Mb) belongs to supergroup A and harbors two pairs of CI factor genes (cifA and cifB). These Cif proteins are classified as Type I and exhibit substantial phylogenetic and structural divergence. Expression of CifB-pair1 caused growth defects in yeast, suggesting that CifB-pair1 exhibits toxicity. However, no direct interaction between CifA and CifB was detected by yeast two-hybrid assays. CONCLUSIONS: These findings elucidate the role and molecular basis of wLhui-induced reproductive manipulation and highlight its potential for developing Wolbachia-based biocontrol strategies against leaf-miner pests. © 2026 Society of Chemical Industry.

Animals↗
PubMed1976

Partial loss of cytoplasmic incompatibility with age in males of Culex fatigans.

The cytoplasms of Paris and Delhi strains of Culex fatigans have been reported to be bi-directionally incompatible. However, in the present study it is shown that with increasing age males with Paris cytoplasm show an increasing degree of partial compatibility with Delhi females. A male history of previous mating seems a contributory effect in enhancing the degree of partial compatibility. The relevance of partial compatibility to genetic control of C. fatigans is discussed.

Aging↗
PubMed2025

The ecology, evolution, and physiology of Cardinium: a widespread heritable endosymbiont of invertebrates.

Candidatus Cardinium hertigii (Cardinium) are maternally transmitted obligate intracellular bacteria found in a wide range of invertebrate hosts, including arthropods and nematodes. Infection with Cardinium has substantial consequences for host biology, with many strains manipulating host reproduction to favor symbiont transmission by (i) feminizing male hosts, (ii) altering host sex allocation, (iii) inducing parthenogenesis, or (iv) causing cytoplasmic incompatibility. Other Cardinium strains can confer benefits to their host or alter host behavior. Cardinium-modified host phenotypes can result in selective sweeps of cytological elements through host populations and potentially reinforce host speciation. Cardinium has potential for applications in controlling arthropod pest species and arthropod-vectored disease transmission, although much remains to be explored regarding Cardinium physiology and host interactions. In this review, we provide an overview of Cardinium evolution and host distribution. We describe the various host phenotypes associated with Cardinium and how biological and environmental factors influence these symbioses. We also provide an overview of Cardinium metabolism, physiology, and potential mechanisms for interactions with hosts based on recent studies using genomics and transcriptomics. Finally, we discuss new methodologies and directions for Cardinium research, including improving our understanding of Cardinium physiology, response to environmental stress, and potential for controlling arthropod pest populations.

Symbiosis↗
PubMedDate not supplied

[Genetic means for control of insect vectors of human diseases (author's transl)].

We divide genetical control methods in two major groups:--mechanisms operating between different species and an example is the attempt of control of A. gambiae in West Africa,--mechanisms operating in a single species with: gamma rays and chemical treatment for sterilisation, cytoplasmic incompatibility (ex.: C. pipiens). Genetical control also suppose the knowledge of biology and ecology of the target insect. This paper does not want to be an exhaustive review of this problem. Its only ambition is to try and expose the possible applications of genetics in the control of vectors.

Africa, Western↗
PubMed2025

Evolutionary Diversification and Functions of the Candidate Male Killing Gene wmk.

Symbiont-mediated male killing (MK) is a mechanism that selectively eliminates male offspring, often by disrupting sex-specific developmental processes. In Drosophila melanogaster, the WO-mediated killing gene wmk from Wolbachia prophage WO transgenically reproduces the MK phenotype, yet how the gene evolves and functions across diverse Wolbachia has not been systematically investigated. We analyzed 32 Wolbachia genomes available in the NCBI database to study wmk homologs across different arthropod hosts, reproductive parasitism functions, and Wolbachia supergroups. First, we report at least five distinct wmk phylogenetic clusters (Types I to V), often organized in multigenic dyads or triads. Second, among MK Wolbachia, there is a significantly higher number of wmk genes and diversity in Lepidoptera strains than in Drosophila strains, which exclusively harbor wmk Types I and III. Third, there are three patterns of wmk sequence and genomic organizational changes in Drosophila MK strains that associate with different evolutionary trajectories underpinning the MK phenotype. Fourth, single and combinatory transgenic expression of Types I and III in D. melanogaster uncovers male-biased lethality associated with Type I; however, dual expression of the Types together elicits a major reduction in offspring number. Fifth, wmk genes have low expression level across D. melanogaster developmental stages relative to the cifA and cifB genes, which could explain why cytoplasmic incompatibility is expressed in this system. These findings establish a complex and phylogenetically informed genetic basis of wmk-induced lethality, highlighting the role of gene copy number and expression, wmk Types, and host background in shaping the phenotype.

Animals↗
PubMed2025

Wolbachia Host Shifts and Widespread Occurrence of Reproductive Manipulation Loci in European Butterflies.

Wolbachia is the most frequent bacterial endosymbiont of arthropods and nematodes. Although it is mostly vertically transmitted, from parent to offspring through the egg cytoplasm, horizontal transfer of Wolbachia is thought to be common over evolutionary timescales. However, the relative frequency of each transmission mechanism has not been studied systematically in closely related species. Additionally, while Wolbachia is generally regarded as a reproductive manipulator, it is unclear how frequently the symbiont induces such effects. In this study, we investigated the presence, phenotypes and phylogenetic relationships among Wolbachia strains in whole genome sequence data for 18 European butterfly sister-species pairs. We find that sister-species share Wolbachia strains more often than random species pairs and that the probability of strain sharing is higher for younger pairs of host species, especially those with greater range overlap. We also find that split times between Wolbachia strains that infect the same sister-species pair generally pre-date host divergence, ruling out co-divergence in favour of horizontal transfer. However, some strains are younger than the mitochondrial split times of their hosts, so introgressive transfer cannot be ruled out in some cases. In addition, all newly assembled Wolbachia genomes contained putative homologues of genes associated with cytoplasmic incompatibility and male killing. This supports the potential for reproductive manipulation in Wolbachia strains infecting European butterflies, which until now was only inferred from mitochondrial diversity patterns. Our results show that horizontal and introgressive transfer of Wolbachia are frequent even between recently speciated host taxa, suggesting the symbiont's turnover rate is higher than had been inferred previously from surveys of distantly related hosts.

Animals↗
PubMed1977

[The ultrastructure of Langhans cells in pathologic human placentas (author's transl)].

In electron microscopic observations on the villous cytotrophoblast in pathologic human placentas we find, besides a general increase of the amount of Langhans cells, significant ultrastructural differences according to the different diseases in pregnancy. Diabetes mellitus: the most striking observations are small, extremely electron dense mitochondria and a lot of intracellular filaments in a hydropic cytoplasm. Rh-incompatibility: according to the stage of placental damage the Langhans cells show a different structure. In light cases we find hydrolic cells with normal mitochondria as well as swollen ones. The plasmalemm shows a lot of foldings and dentations with the syncytium. In serious cases of rh-incompatibility the Langhans cells cover the trophoblastic basal membrane completely. Their electron density is even higher than that of the syncytium. Characteristic lysosomes appear. In the most serious cases the syncytium is completely destroyed and maximal hydropic Langhans cells cover the villi. EPH-gestosis: the Langhans cells show different phases of differentiation, but no other characteristic criteria. The importance of the Langhans cells for the regeneration of the syncytotrophoblast is discussed. Mitochondria and rough endoplasmic reticulum are obviously not formed in the syncytium but they must be regenerated by taking up Langhans cells by syncytial fusion.

Blood Group Incompatibility↗
PubMed1977

Studies on the development of F1 embryos from inter-strain cross involving DDK mice.

The development of the early mouse embryos was investigated from 36 to 84 h after the presumed time of fertilization. The mean number of cells constituting the embryo from the intra-strain crosses of three strains at 84h of development was as follows: DDK, 22-7; BS, 43-1 and ITES, 62-0. A significance was observed in the cleavage rate of the embryo between DDK and the other two strains. The F1 embryos from the crosses of BS females X DDK males and ITES females X DDK males showed almost the same progress of development as BS and ITES embryos, respectively. Therefore, it is concluded that the early development of the F1 embryos iss, DDK females X BS males, showed conspicuously small cell numbers as compared with their litter-mates that developed to the blastocyst stage. It is inferred that the discrimination is already made during cleavage between the fortunate survivors and the lethal embryos due to the incompatibility between the cytoplasmic factor of DDK eggs and alien spermatozoa.

Animals↗
PubMed1976

Quantitation of turnover and export to the cytoplasm of hnRNA transcribed in the Balbiani rings.

Some quantitative parameters of the intranuclear metabolism and export to the cytoplasm of Balbiani ring 1 and 2 RNA molecules in salivary gland cells of Chironomus tentans have been determined. Growing RNA chains in the Balbiani rings attain uniform labeling with RNA precursors after 20 min of incorporation. The specific activity of 75S RNA released from the Balbiani rings into the nuclear sap increases rapidly and reaches a maximum level between 90 and 180 min of labeling. After 20 min, labeled 75S RNA enters the cytoplasm and accumulates at a linear rate. However, only a small proportion of the RNA produced at the Balbiani ring loci can subsequently be recovered in the nuclear sap (14-17%) or cytoplasm (4-7%) as 75S RNA; presumably the remainder is degraded entirely. Experiments using inhibitors of elongation (actinomycin D) or initiation (5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole) revealed that no significant quanity of the 75S RNA transcribed can be chased into the cytoplasm. Both the kinetics of entry of labeled 75S RNA into the cytoplasm-that is, a constant rate of increase after a brief lag-and chase data are incompatible with a precursor-product relationship between the great majority of nuclear 75S RNA and cytoplasmic 75S RNA with messenger characteristics. The results are discussed in relation to the possibility that a post-transcriptional control mechanism is operating in these cells.

Animals↗
PubMed1979

Post-fusion somatic incompatibility in plasmodia of Physarum polycephalum.

High-resolution autoradiography has been used to establish that during the incompatibility reaction that follows fusion between plasmodia of a 'killer' and a 'sensitive' strain of the myxomycete Physarum polycephalum, the nuclei of the sensitive strain are selectively damaged, enclosed in vacuoles and eliminated from the cytoplasm. This damage is visible as increased chromatin condensation and nucleolar segregation. Nuclear envelopes of both strains show blebbing, and there is an increase in the size and frequency of cytoplasmic vesicles of endoplasmic reticulum. Multiple nuclear fusions are seen between all combinations of genetically like and unlike types of nuclei throughout the course of the incompatibility reaction. After the reaction, mean nuclear diameters increase over 2-3 days to give nuclei an order of magnitude greater in volume than the controls; the population size range returns to normal in 4-5 days. Fusions between incompatible plasmodia carried out when the killer strain is at or very near to mitosis do not produce an immediate incompatibility reaction, but give plasmodia that are neutral and act as neither killers nor sensitives; these heterokaryons convert to killer phenotypes after a few days.

Cell Nucleolus↗
PubMed1977

Informational molecules in amoebae: an attempt to follow injected fractions using autoradiography.

Cytoplasmic fractions from Amoeba discoides contain informational molecules which, when injected into A. proteus, may influence the characters of resulting clones. An attempt was made to follow and locate these molecules by autoradiography. Using either 3H-uridine or 3H-leucine, radioactive fractions of A. discoides were microinjected into A. proteus and cells examined at varying times after injection. A. discoides were injected with the same preparations to serve as controls. Grain counts were compared for equivalent areas of nucleus and cytoplasm, and results expressed in terms of the ratio between nucleus and cytoplasm. When the light microsomal or the supernatant fractions were injected, the level of labelled molecules was higher in the nucleus than the cytoplasm in over 50% of the cells examined after 6 h, except for those cells injected with 3H-leucine-labelled supernatant material when only 15% cells showed a nuclear/cytoplasmic grain count greater than 1.1. After some purification by sucrose density gradient centrifugation, 'information-containing' peaks '13' from the light microsomal fraction, and '16' from the supernatant fraction were injected. A different pattern of results was obtained. The problems of interpreting these results in the light of known migratory molecules and strain incompatibility are discussed.

Amoeba↗
PubMed2025

Genetic interactions and natural variation underlying S-RNase-independent unilateral incompatibility in Solanum.

Pistils of self-incompatible (SI) species/populations typically reject pollen of related self-compatible (SC) species/populations, but not vice versa, a pattern known as unilateral incompatibility (UI). UI is complex and includes both S-RNase-dependent and S-RNase-independent mechanisms. Pistils of Solanum pennellii LA0716 (SC, no S-RNase) reject pollen of cultivated tomato, Solanum lycopersicum (SC); UI in this system involves the expression of ornithine decarboxylase2 (ODC2) and HT-A/-B genes in the pistil, and farnesyl pyrophosphate synthase2 (FPS2), ui6.2, and ui12.2 in pollen. We show that IL12-3 (HT-A/-B) × IL3-3 (ODC2) double introgression lines reject S. lycopersicum pollen, while odc2 or ht-a mutants do not, demonstrating that ODC2 and HT-A are required for UI. Transmission ratio distortion in favor of pennellii alleles was observed in interspecific F2 S. lycopersicum × S. pennellii near ui6.2 and ui12.2, and in F2 IL12-3 × IL3-3 near ui12.2. Equivalent populations made with odc2 mutants segregate in Mendelian ratios, while ht-a mutants have little effect, indicating ui6.2 and ui12.2 interact primarily with ODC2. Pollen from fps2 mutants in S. pennellii LA0716 are incompatible on pistils of all tested S. pennellii and some Solanum habrochaites accessions, but compatible with all other tomato clade species, suggesting ODC2-dependent UI evolved in a common ancestor to S. pennellii and S. habrochaites. Within S. habrochaites, fps2 pollen rejection was observed mainly in SI or mixed mating populations, suggesting an association with outcrossing. Triple mutants of S. pennellii and S. habrochaites lacking functional ODC2, HT-A/-B, and S-RNase are cross-compatible as female parents with S. lycopersicum, allowing transfer of their cytoplasmic genomes into cultivated tomato.

Solanum↗