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Cell Host & Microbe Jun 2021The most widespread intracellular bacteria in the animal kingdom are maternally inherited endosymbionts of the genus Wolbachia. Their prevalence in arthropods and... (Review)
Review
The most widespread intracellular bacteria in the animal kingdom are maternally inherited endosymbionts of the genus Wolbachia. Their prevalence in arthropods and nematodes worldwide and stunning arsenal of parasitic and mutualistic adaptations make these bacteria a biological archetype for basic studies of symbiosis and applied outcomes for curbing human and agricultural diseases. Here, we conduct a summative, centennial analysis of living in the Wolbachia world. We synthesize literature on Wolbachia's host range, phylogenetic diversity, genomics, cell biology, and applications to filarial, arboviral, and agricultural diseases. We also review the mobilome of Wolbachia including phage WO and its essentiality to hallmark reproductive phenotypes in arthropods. Finally, the Wolbachia system is an exemplar for discovery-based science education using biodiversity, biotechnology, and bioinformatics lessons. As we approach a century of Wolbachia research, the interdisciplinary science of this symbiosis stands as a model for consolidating and teaching the integrative rules of endosymbiotic life.
Topics: Animals; Bacteriophages; Biological Evolution; Feminization; Host Microbial Interactions; Host Specificity; Humans; Male; Phenotype; Phylogeny; Preventive Medicine; Symbiosis; Wolbachia
PubMed: 33945798
DOI: 10.1016/j.chom.2021.03.006 -
Plants (Basel, Switzerland) May 2021Angiosperm plants reproduce both sexually and asexually (by apomixis). In apomictic plants, the embryo and endosperm develop without fertilization. Modern maize seems to...
Angiosperm plants reproduce both sexually and asexually (by apomixis). In apomictic plants, the embryo and endosperm develop without fertilization. Modern maize seems to have a broken apomixis-triggering mechanism, which still works in and in -maize hybrids. For the first time, maize lines characterized by pronounced and inheritable high-frequency maternal parthenogenesis were generated 40 years ago, but there are no data on gene expression in parthenogenic maize proembryos. Here we examined for the first time gene expression in parthenogenic proembryos isolated from unpollinated embryo sacs (ESs) of a parthenogenic maize line (AT-4). The DNA-methylation genes (, ) and the genes coding for the chromatin-modifying enzymes (, , ) were expressed much higher in parthenogenic proembryos than in unpollinated ESs. The expression of the fertilization-independent endosperm () genes was found for the first time in parthenogenic proembryos and unpollinated ESs. In parthenogenic proembryos, the gene was expressed up to two times higher than it was expressed in unpollinated ESs.
PubMed: 34066123
DOI: 10.3390/plants10050964 -
The American Naturalist Aug 2022AbstractDetermining how and how often asexual lineages emerge within sexual species is central to our understanding of sex-asex transitions and the long-term maintenance...
AbstractDetermining how and how often asexual lineages emerge within sexual species is central to our understanding of sex-asex transitions and the long-term maintenance of sex. Asexuality can arise "by transmission" from an existing asexual lineage to a new one through different types of crosses. The occurrence of these crosses, cryptic sex, variations in ploidy, and recombination within asexuals greatly complicates the study of sex-asex transitions, as they preclude the use of standard phylogenetic methods and genetic distance metrics. In this study we show how to overcome these challenges by developing new approaches to investigate the origin of the various asexual lineages of the brine shrimp . We use a large sample of asexuals, including all known polyploids, and their sexual relatives. We combine flow cytometry with mitochondrial and nuclear DNA data. We develop new genetic distance measures and methods to compare various scenarios describing the origin of the different lineages. We find that all diploid and polyploid likely arose within the past 80,000 years through successive and nested hybridization events that involved backcrosses with different sexual species. All have the same common ancestor and therefore likely carry the same asexuality gene(s) and reproduce by automixis. These findings radically change our view of sex-asex transitions in this group and show the importance of considering scenarios of asexuality by transmission. The methods developed are applicable to many other asexual taxa.
Topics: Animals; Artemia; Parthenogenesis; Phylogeny; Polyploidy; Reproduction, Asexual
PubMed: 35905400
DOI: 10.1086/720268 -
Journal of Equine Veterinary Science Apr 2021As standard in vitro fertilization is not a viable technique in horses yet, many different techniques have been used to create equine embryos for research purposes. One... (Review)
Review
As standard in vitro fertilization is not a viable technique in horses yet, many different techniques have been used to create equine embryos for research purposes. One such method is parthenogenesis in which an oocyte is induced to mature into an embryo-like state without the introduction of a spermatozoon, and thus they are not considered true embryos. Another method is somatic cell nuclear transfer (SCNT), in which a somatic cell nucleus from an extant horse is inserted into an enucleated oocyte, creating a genetic clone of the donor horse. Due to limited availability of equine oocytes in the United States, researchers have investigated the potential for combining equine somatic cell nuclei with oocytes from other species to make embryos for research purposes, which has not been successful to date. There has also been a rising interest in producing transgenic animals using sperm exposed to exogenous DNA. The successful creation of transgenic equine blastocysts shows the promise of sperm mediated gene transfer (SMGT), but this method is not ideal for other applications, like gene therapy, because it cannot be used to induce targeted mutations. That is why technologies like CRISPR/Cas9 are vital. In this review, we argue that parthenogenesis, SCNT, and interspecies SCNT can be considered genetic manipulation strategies as they create embryos that are genetically identical to their parent cell. Here, we describe how these methods are performed and their applications and we also describe the few methods that have been used to directly modify equine embryos: SMGT and CRISPR/Cas9.
Topics: Animals; Blastocyst; Embryo, Mammalian; Horses; Male; Nuclear Transfer Techniques; Oocytes; Parthenogenesis
PubMed: 33781418
DOI: 10.1016/j.jevs.2021.103394 -
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 -
Genes Aug 2020In the past decades, the grasses of the genus have emerged as a versatile model allowing evolutionary, genetic, molecular, and developmental studies on apomixis as well... (Review)
Review
In the past decades, the grasses of the genus have emerged as a versatile model allowing evolutionary, genetic, molecular, and developmental studies on apomixis as well as successful breeding applications. The rise of such an archetypal system progressed through integrative phases, which were essential to draw conclusions based on solid standards. Here, we review the steps adopted in to establish the current body of knowledge on apomixis and provide model breeding programs for other agronomically important apomictic crops. In particular, we discuss the need for previous detailed cytoembryological and cytogenetic germplasm characterization; the establishment of sexual and apomictic materials of identical ploidy level; the development of segregating populations useful for inheritance analysis, positional mapping, and epigenetic control studies; the development of omics data resources; the identification of key molecular pathways via comparative gene expression studies; the accurate molecular characterization of genomic loci governing apomixis; the in-depth functional analysis of selected candidate genes in apomictic and model species; the successful building of a sexual/apomictic combined breeding scheme.
Topics: Apomixis; Gene Expression Regulation, Developmental; Gene Expression Regulation, Plant; Models, Biological; Paspalum; Plant Breeding; Plant Proteins; Seeds
PubMed: 32839398
DOI: 10.3390/genes11090974 -
Genes Jul 2020Many species of arthropods carry maternally inherited bacterial endosymbionts that can influence host sexual reproduction to benefit the bacterium. The most well-known... (Review)
Review
Many species of arthropods carry maternally inherited bacterial endosymbionts that can influence host sexual reproduction to benefit the bacterium. The most well-known of such reproductive parasites is . are obligate intracellular α-proteobacteria found in nearly half of all arthropod species. This success has been attributed in part to their ability to manipulate host reproduction to favor infected females. Cytoplasmic incompatibility (CI), a phenomenon wherein infection renders males sterile when they mate with uninfected females, but not infected females (the rescue mating), appears to be the most common. CI provides a reproductive advantage to infected females in the presence of a threshold level of infected males. The molecular mechanisms of CI and other reproductive manipulations, such as male killing, parthenogenesis, and feminization, have remained mysterious for many decades. It had been proposed by Werren more than two decades ago that CI is caused by a -mediated sperm modification and that rescue is achieved by a -encoded rescue factor in the infected egg. In the past few years, new research has highlighted a set of syntenic gene pairs encoding CI-inducing factors (Cifs) as the key players for the induction of CI and its rescue. Within each Cif pair, the protein encoded by the upstream gene is denoted A and the downstream gene B. To date, two types of Cifs have been characterized based on the enzymatic activity identified in the B protein of each protein pair; one type encodes a deubiquitylase (thus named CI-inducing deubiquitylase or ), and a second type encodes a nuclease (named CI-inducing nuclease or ). The CidA and CinA proteins bind tightly and specifically to their respective CidB and CinB partners. In transgenic , the expression of either the Cid or Cin protein pair in the male germline induces CI and the expression of the cognate A protein in females is sufficient for rescue. With the identity of the CI induction and rescue factors now known, research in the field has turned to directed studies on the molecular mechanisms of CI, which we review here.
Topics: Animals; Cytoplasm; Drosophila melanogaster; Symbiosis; Wolbachia
PubMed: 32722516
DOI: 10.3390/genes11080852 -
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 -
Scientific Reports May 2021Non-lethal methods for semen collection from elasmobranchs to better understand species reproduction has accompanied the development of artificial insemination....
Non-lethal methods for semen collection from elasmobranchs to better understand species reproduction has accompanied the development of artificial insemination. Ejaculates (n = 82) collected from whitespotted bamboo sharks Chiloscyllium plagiosum (n = 19) were assessed and cold-stored raw or extended at 4 °C. Females (n = 20) were inseminated with fresh or 24-48 h cold-stored raw or extended semen and paternity of offspring determined with microsatellite markers. Insemination of females with fresh semen (n = 10) resulted in 80 hatchlings and 27.6% fertility. Insemination of females with semen cold-stored 24 h (n = 4) and 48 h (n = 1) semen resulted in 17 hatchlings and fertilization rates of 28.1% and 7.1% respectively. Two females inseminated with fresh or cold-stored semen laid eggs that hatched from fertilization and parthenogenesis within the same clutch. Parthenogenesis rate for inseminated females was 0.71%. Results demonstrate artificial insemination with cold-stored semen can provide a strategy for transport of male genetics nationally and internationally, precluding the need to transport sharks. Production of parthenotes in the same clutch as sexually fertilized eggs highlights the prevalence of parthenogenesis in whitespotted bamboo sharks and poses important considerations for population management.
Topics: Animals; Ejaculation; Female; Fertility; Insemination, Artificial; Male; Microsatellite Repeats; Oviposition; Parthenogenesis; Paternity; Semen Analysis; Semen Preservation; Sharks; Sperm Motility; Spermatozoa; Zygote
PubMed: 33980873
DOI: 10.1038/s41598-021-88568-y -
EvoDevo Aug 2022Water fleas of the genus Daphnia have been a model system for hundreds of years and is among the best studied ecological model organisms to date. Daphnia are planktonic... (Review)
Review
Water fleas of the genus Daphnia have been a model system for hundreds of years and is among the best studied ecological model organisms to date. Daphnia are planktonic crustaceans with a cyclic parthenogenetic life-cycle. They have a nearly worldwide distribution, inhabiting standing fresh- and brackish water bodies, from small temporary pools to large lakes. Their predominantly asexual reproduction allows for the study of phenotypes excluding genetic variation, enabling us to separate genetic from non-genetic effects. Daphnia are often used in studies related to ecotoxicology, predator-induced defence, host-parasite interactions, phenotypic plasticity and, increasingly, in evolutionary genomics. The most commonly studied species are Daphnia magna and D. pulex, for which a rapidly increasing number of genetic and genomic tools are available. Here, I review current research topics, where the Daphnia model system plays a critical role.
PubMed: 35941607
DOI: 10.1186/s13227-022-00199-0