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Journal of Experimental Botany Aug 2023The word 'fruit' is derived from the latin 'fructus' which itself is said to be derived from 'frui', which means to enjoy. Along those lines, I hope this year's...
The word 'fruit' is derived from the latin 'fructus' which itself is said to be derived from 'frui', which means to enjoy. Along those lines, I hope this year's Flowering Newsletter brings a lot of joy, because fruits and seeds feature in multiple articles.
Topics: Apomixis; Seeds; Fruit
PubMed: 37419454
DOI: 10.1093/jxb/erad258 -
Insects Oct 2023Insects are renowned for their remarkable diversity of reproductive modes. Among these, the largest non-holometabolous order, Hemiptera, stands out with one of the most... (Review)
Review
Insects are renowned for their remarkable diversity of reproductive modes. Among these, the largest non-holometabolous order, Hemiptera, stands out with one of the most diversified arrays of parthenogenesis modes observed among insects. Although there are extensive reviews on reproduction without fertilization in some hemipteran higher taxa, no such analysis has been conducted for the large suborders Fulgoromorpha (planthoppers) and Cicadomorpha (leafhoppers). In both groups, there are species that reproduce by true parthenogenesis, specifically thelytoky, and in Fulgoromorpha, there are species that reproduce by pseudogamy or, more specifically, sperm-dependent parthenogenesis. In this review paper, we give and discuss the only currently known examples of true parthenogenesis in Fulgoromorpha and Cicadomorpha, mainly from the planthopper family Delphacidae and the leafhopper family Cicadellidae. We analyze patterns of distribution, ecology, mating behavior, acoustic communication, and cytogenetic and genetic diversity of parthenoforms and discuss hypotheses about the origin of parthenogenesis in each case. We also highlight examples in which natural populations show a shift in sex ratio toward females and discuss possible causes of this phenomenon, primarily the influence of endosymbiotic bacteria capable of altering the reproductive strategies of the hosts. Our review is mainly based on studies in which the authors have participated.
PubMed: 37887832
DOI: 10.3390/insects14100820 -
Journal of Experimental Botany Aug 2023Endosperm is a key nutritive tissue that supports the developing embryo or seedling, and serves as a major nutritional source for human and livestock feed. In... (Review)
Review
Endosperm is a key nutritive tissue that supports the developing embryo or seedling, and serves as a major nutritional source for human and livestock feed. In sexually-reproducing flowering plants, it generally develops after fertilization. However, autonomous endosperm (AE) formation (i.e. independent of fertilization) is also possible. Recent findings of AE loci/ genes and aberrant imprinting in native apomicts, together with a successful initiation of parthenogenesis in rice and lettuce, have enhanced our understanding of the mechanisms bridging sexual and apomictic seed formation. However, the mechanisms driving AE development are not well understood. This review presents novel aspects related to AE development in sexual and asexual plants underlying stress conditions as the primary trigger for AE. Both application of hormones to unfertilized ovules and mutations that impair epigenetic regulation lead to AE development in sexual Arabidopsis thaliana, which may point to a common pathway for both phenomena. Apomictic-like AE development under experimental conditions can take place due to auxin-dependent gene expression and/or DNA methylation.
Topics: Humans; Endosperm; Epigenesis, Genetic; Asteraceae; Seeds; Reproduction; Arabidopsis
PubMed: 37155961
DOI: 10.1093/jxb/erad168 -
BioRxiv : the Preprint Server For... Dec 2023Bacteria in the genus have evolved numerous strategies to manipulate arthropod sex, including the conversion of would-be male offspring to asexually reproducing...
Bacteria in the genus have evolved numerous strategies to manipulate arthropod sex, including the conversion of would-be male offspring to asexually reproducing females. This so-called "parthenogenesis-induction" phenotype can be found in a number of strains that infect arthropods with haplodiploid sex determination systems, including parasitoid wasps. Despite the discovery of microbe-mediated parthenogenesis more than 30 years ago, the underlying genetic mechanisms have remained elusive. We used a suite of genomic, computational, and molecular tools to identify and characterize two proteins that are uniquely found in parthenogenesis-inducing and have strong signatures of host-associated bacterial effector proteins. These putative parthenogenesis-inducing proteins have structural homology to eukaryotic protein domains including nucleoporins, the key insect sex-determining factor Transformer, and a eukaryotic-like serine-threonine kinase with leucine rich repeats. Furthermore, these proteins significantly impact eukaryotic cell biology in the model, . We suggest these proteins are parthenogenesis-inducing factors and our results indicate this would be made possible by a novel mechanism of bacterial-host interaction.
PubMed: 38076953
DOI: 10.1101/2023.12.01.569668 -
Genome Biology and Evolution Jul 2023Cyclical parthenogenesis, where females can engage in sexual or asexual reproduction depending on environmental conditions, represents a novel reproductive phenotype...
Cyclical parthenogenesis, where females can engage in sexual or asexual reproduction depending on environmental conditions, represents a novel reproductive phenotype that emerged during eukaryotic evolution. The fact that environmental conditions can trigger cyclical parthenogens to engage in distinct reproductive modes strongly suggests that gene expression plays a key role in the origin of cyclical parthenogenesis. However, the genetic basis underlying cyclical parthenogenesis remains understudied. In this study, we characterize the female transcriptomic signature of sexual versus asexual reproduction in the cyclically parthenogenetic microcrustacean Daphnia pulex and Daphnia pulicaria. Our analyses of differentially expressed genes (DEGs), pathway enrichment, and gene ontology (GO) term enrichment clearly show that compared with sexual reproduction, the asexual reproductive stage is characterized by both the underregulation of meiosis and cell cycle genes and the upregulation of metabolic genes. The consensus set of DEGs that this study identifies within the meiotic, cell cycle, and metabolic pathways serves as candidate genes for future studies investigating how the two reproductive cycles in cyclical parthenogenesis are mediated at a molecular level. Furthermore, our analyses identify some cases of divergent expression among gene family members (e.g., doublesex and NOTCH2) associated with asexual or sexual reproductive stage, suggesting potential functional divergence among gene family members.
Topics: Parthenogenesis; Transcriptome; Reproduction, Asexual; Male; Female; Animals; Daphnia; Gene Expression Profiling
PubMed: 37392457
DOI: 10.1093/gbe/evad122 -
STAR Protocols Dec 2023Most species of sexually reproducing Drosophila are capable of some degree of facultative parthenogenesis, which involves the initiation of development in an...
Most species of sexually reproducing Drosophila are capable of some degree of facultative parthenogenesis, which involves the initiation of development in an unfertilized egg. Here, we present an optimized protocol to screen facultative parthenogenesis in Drosophila. We describe steps for the collection and maintenance of virgin flies. We then detail offspring screening for the analysis of parthenogenesis. This protocol can be applied to different Drosophila strains and can be adapted for the analysis of parthenogenesis in other animals. For complete details on the use and execution of this protocol, please refer to Sperling et al..
Topics: Animals; Drosophila; Parthenogenesis
PubMed: 37740913
DOI: 10.1016/j.xpro.2023.102585 -
Comparative Cytogenetics 2023An account is given of my development of techniques to obtain well-spread Giemsa-stained banded chromosome preparations. Apparent G-banding could be obtained following...
An account is given of my development of techniques to obtain well-spread Giemsa-stained banded chromosome preparations. Apparent G-banding could be obtained following very slight trypsin treatment of freshly prepared slides, but this banding was very fine (close-grained) and possibly not a reflection of chromosome structure. However, treatment of developing embryos with 5-fluorouridine produced a similar chromomere banding, which is therefore regarded as genuine. Steady accumulation of Fabricius, 1775 karyotypes has resulted in the production of an Atlas covering 62 of the 170 species known to occur in the Palaearctic. Chromosome polymorphisms involving pericentric inversions and addition of extra C-banding regions have been found, as well as small B-chromosomes in a few species. In general, karyotypes have proved very useful in establishing the limits of individual species. Parthenogenesis involving triploidy has been found in two species. Karyotypes of experimentally produced hybrids have revealed irregularities in chromosome condensation.
PubMed: 38284104
DOI: 10.3897/compcytogen.17.112831 -
Current Biology : CB Sep 2023Facultative parthenogenesis enables sexually reproducing organisms to switch between sexual and asexual parthenogenetic reproduction. To gain insights into this...
Facultative parthenogenesis enables sexually reproducing organisms to switch between sexual and asexual parthenogenetic reproduction. To gain insights into this phenomenon, we sequenced the genomes of sexually reproducing and parthenogenetic strains of Drosophila mercatorum and identified differences in the gene expression in their eggs. We then tested whether manipulating the expression of candidate gene homologs identified in Drosophila mercatorum could lead to facultative parthenogenesis in the non-parthenogenetic species Drosophila melanogaster. This identified a polygenic system whereby increased expression of the mitotic protein kinase polo and decreased expression of a desaturase, Desat2, caused facultative parthenogenesis in the non-parthenogenetic species that was enhanced by increased expression of Myc. The genetically induced parthenogenetic Drosophila melanogaster eggs exhibit de novo centrosome formation, fusion of the meiotic products, and the onset of development to generate predominantly triploid offspring. Thus, we demonstrate a genetic basis for sporadic facultative parthenogenesis in an animal.
Topics: Animals; Drosophila; Drosophila melanogaster; Parthenogenesis; Centrosome
PubMed: 37516115
DOI: 10.1016/j.cub.2023.07.006 -
International Journal of Molecular... Jul 2023The increasing frequency of general and particularly male cancer coupled with the reduction in male fertility seen worldwide motivated us to seek a potential... (Review)
Review
The increasing frequency of general and particularly male cancer coupled with the reduction in male fertility seen worldwide motivated us to seek a potential evolutionary link between these two phenomena, concerning the reproductive transcriptional modules observed in cancer and the expression of cancer-testis antigens (CTA). The phylostratigraphy analysis of the human genome allowed us to link the early evolutionary origin of cancer via the reproductive life cycles of the unicellulars and early multicellulars, potentially driving soma-germ transition, female meiosis, and the parthenogenesis of polyploid giant cancer cells (PGCCs), with the expansion of the CTA multi-families, very late during their evolution. CTA adaptation was aided by retrovirus domestication in the unstable genomes of mammals, for protecting male fertility in stress conditions, particularly that of humans, as compensation for the energy consumption of a large complex brain which also exploited retrotransposition. We found that the early and late evolutionary branches of human cancer are united by the immunity-proto-placental network, which evolved in the Cambrian and shares stress regulators with the finely-tuned sex determination system. We further propose that social stress and endocrine disruption caused by environmental pollution with organic materials, which alter sex determination in male foetuses and further spermatogenesis in adults, bias the development of PGCC-parthenogenetic cancer by default.
Topics: Pregnancy; Animals; Humans; Male; Female; Testis; Placenta; Spermatogenesis; Reproduction; Neoplasms; Mammals; Polyploidy; Fertility
PubMed: 37511419
DOI: 10.3390/ijms241411660 -
Annual Review of Microbiology Sep 2023Among endosymbiotic bacteria living within eukaryotic cells, is exceptionally widespread, particularly in arthropods. Inherited through the female germline, it has... (Review)
Review
Among endosymbiotic bacteria living within eukaryotic cells, is exceptionally widespread, particularly in arthropods. Inherited through the female germline, it has evolved ways to increase the fraction of bacterially infected offspring by inducing parthenogenesis, feminization, male killing, or, most commonly, cytoplasmic incompatibility (CI). In CI, infection of males causes embryonic lethality unless they mate with similarly infected females, creating a relative reproductive advantage for infected females. A set of related bicistronic operons encodes the CI-inducing factors. The downstream gene encodes a deubiquitylase or nuclease and is responsible for CI induction by males, while the upstream product when expressed in females binds its sperm-introduced cognate partner and rescues viability. Both toxin-antidote and host-modification mechanisms have been proposed to explain CI. Interestingly, male killing by either or endosymbionts involves deubiquitylases as well. Interference with the host ubiquitin system may therefore be a common theme among endosymbiont-mediated reproductive alterations.
Topics: Female; Male; Humans; Wolbachia; Semen; Reproduction; Cytoplasm; Molecular Biology; Symbiosis
PubMed: 37285552
DOI: 10.1146/annurev-micro-041020-024616