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WormBook : the Online Review of C.... Sep 2017The nematode Caenorhabditis elegans is now a major model organism in biology. The choice of Sydney Brenner to adopt this species in the mid-1960s and the success of his... (Review)
Review
The nematode Caenorhabditis elegans is now a major model organism in biology. The choice of Sydney Brenner to adopt this species in the mid-1960s and the success of his team in raising it to a model organism status have been told (http://www.wormbook.org/toc_wormhistory.html; Brenner, 2001; Ankeny, 2001). Here we review the pre-Brenner history of the use of free-living nematodes as models for general questions in biology. We focus on the period that started in 1899 with the first publication of Emile Maupas mentioning Rhabditis elegans and ended in 1974 with the first publications by Brenner. A common thread in this period, aided by the variety in modes of reproduction of different nematode species, is found in studies of meiosis, fertilization, heredity, and sex determination. Maupas in his 1900 opus on reproduction had already chosen C. elegans as the species of reference. Hikokura Honda determined its hermaphrodite chromosomal content in 1925. C. elegans was again isolated and chosen as a main subject by Victor Nigon in the 1940-50s. Nigon mastered crosses between C. elegans hermaphrodites and males, described the meiotic behavior of chromosomes in XX hermaphrodites and X0 males and, using tetraploids, correctly inferred that sex was determined by X chromosome to autosome dosage. With Ellsworth Dougherty, Nigon isolated and studied a C. briggsae body size mutant and a C. elegans slow growth mutant. Dougherty and his team devoted most of their work to finding a defined culture medium to screen for physiological mutants, focusing on C. briggsae. With Helene Fatt, Dougherty also performed the first genetic study of natural variation in C. elegans, concerning the difference in heat resistance of the Bergerac and Bristol strains. Jean Brun, a student of Nigon, performed a long and remarkable experiment in acclimatization of C. elegans Bergerac to higher temperatures, the significance of which remains to be clarified.
Topics: Adaptation, Physiological; Aging; Animals; Biomedical Research; Caenorhabditis elegans; Fertility; Hermaphroditic Organisms; History, 19th Century; History, 20th Century; Meiosis; Models, Animal; Parthenogenesis; Sex Determination Analysis; Temperature
PubMed: 28326696
DOI: 10.1895/wormbook.1.181.1 -
Current Biology : CB Apr 2023Wang and Underwood introduce apomixis in plants.
Wang and Underwood introduce apomixis in plants.
Topics: Apomixis; Plants; Seeds
PubMed: 37098328
DOI: 10.1016/j.cub.2023.01.051 -
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 -
Ecology and Evolution Jul 2022Sex is evolutionarily more costly than parthenogenesis, evolutionary ecologists therefore wonder why sex is much more frequent than parthenogenesis in the majority of...
Sex is evolutionarily more costly than parthenogenesis, evolutionary ecologists therefore wonder why sex is much more frequent than parthenogenesis in the majority of animal lineages. Intriguingly, parthenogenetic individuals and species are as common as or even more common than sexuals in some major and putative ancient animal lineages such as oribatid mites and rotifers. Here, we analyzed oribatid mites (Acari: Oribatida) as a model group because these mites are ancient (early Paleozoic), widely distributed around the globe, and include a high number of parthenogenetic species, which often co-exist with sexual oribatid mite species. There is evidence that the reproductive mode is phylogenetically conserved in oribatid mites, which makes them an ideal model to test hypotheses on the relationship between reproductive mode and species' ecological strategies. We used oribatid mites to test the frozen niche variation hypothesis; we hypothesized that parthenogenetic oribatid mites occupy narrow specialized ecological niches. We used the geographic range of species as a proxy for specialization as specialized species typically do have narrower geographic ranges than generalistic species. After correcting for phylogenetic signal in reproductive mode and demonstrating that geographic range size has no phylogenetic signal, we found that parthenogenetic lineages have a higher probability to have broader geographic ranges than sexual species arguing against the frozen niche variation hypothesis. Rather, the results suggest that parthenogenetic oribatid mite species are more generalistic than sexual species supporting the general-purpose genotype hypothesis. The reason why parthenogenetic oribatid mite species are generalists with wide geographic range sizes might be that they are of ancient origin reflecting that they adapted to varying environmental conditions during evolutionary history. Overall, our findings indicate that parthenogenetic oribatid mite species possess a widely adapted general-purpose genotype and therefore might be viewed as "Jack-of-all-trades."
PubMed: 35784052
DOI: 10.1002/ece3.9036 -
Genes Apr 2021Sexual reproduction in plants is a complex, stringently regulated process that leads to the creation of diaspores for a new generation: sexual seeds [...].
Sexual reproduction in plants is a complex, stringently regulated process that leads to the creation of diaspores for a new generation: sexual seeds [...].
Topics: Apomixis; Gene Expression Regulation, Plant; Plant Physiological Phenomena; Plant Proteins; Plants
PubMed: 33923377
DOI: 10.3390/genes12040576 -
Proceedings. Biological Sciences Mar 2023Parthenogenesis has been documented in almost every phylum of animals, and yet this phenomenon is largely understudied. It has particular importance in dipterans since... (Review)
Review
Parthenogenesis has been documented in almost every phylum of animals, and yet this phenomenon is largely understudied. It has particular importance in dipterans since some parthenogenetic species are also disease vectors and agricultural pests. Here, we present a catalogue of parthenogenetic dipterans, although it is likely that many more remain to be identified, and we discuss how their developmental biology and interactions with diverse environments may be linked to different types of parthenogenetic reproduction. We discuss how the advances in genetics and genomics have identified chromosomal loci associated with parthenogenesis. In particular, a polygenic cause of facultative parthenogenesis has been uncovered in allowing the corresponding genetic variants to be tested for their ability to promote parthenogenesis in another species, . This study probably identifies just one of many routes that could be followed in the evolution of parthenogenesis. We attempt to account for why the phenomenon has evolved so many times in the dipteran order and why facultative parthenogenesis appears particularly prevalent. We also discuss the significance of coarse genomic changes, including non-disjunction, aneuploidy, and polyploidy and how, together with changes to specific genes, these might relate to both facultative and obligate parthenogenesis in dipterans and other parthenogenetic animals.
Topics: Animals; Drosophila melanogaster; Reproduction; Drosophila; Parthenogenesis; Agriculture
PubMed: 36946111
DOI: 10.1098/rspb.2023.0261 -
Cells Sep 2021Recently, it was pointed out that classic models for the evolution of anisogamy do not take into account the possibility of parthenogenetic reproduction, even though sex...
Recently, it was pointed out that classic models for the evolution of anisogamy do not take into account the possibility of parthenogenetic reproduction, even though sex is facultative in many relevant taxa (e.g., algae) that harbour both anisogamous and isogamous species. Here, we complement this recent analysis with an approach where we assume that the relationship between progeny size and its survival may differ between parthenogenetically and sexually produced progeny, favouring either the former or the latter. We show that previous findings that parthenogenesis can stabilise isogamy relative to the obligate sex case, extend to our scenarios. We additionally investigate two different ways for one mating type to take over the entire population. First, parthenogenesis can lead to biased sex ratios that are sufficiently extreme that one type can displace the other, leading to de facto asexuality for the remaining type that now lacks partners to fuse with. This process involves positive feedback: microgametes, being numerous, lack opportunities for syngamy, and should they proliferate parthenogenetically, the next generation makes this asexual route even more prominent for microgametes. Second, we consider mutations to strict asexuality in producers of micro- or macrogametes, and show that the prospects of asexual invasion depend strongly on the mating type in which the mutation arises. Perhaps most interestingly, we also find scenarios in which parthenogens have an intrinsic survival advantage yet facultatively sexual isogamous populations are robust to the invasion of asexuals, despite us assuming no genetic benefits of recombination. Here, equal contribution from both mating types to zygotes that are sufficiently well provisioned can outweigh the additional costs associated with syngamy.
Topics: Biological Evolution; Gametogenesis; Germ Cells; Models, Biological; Mutation; Parthenogenesis; Phaeophyceae; Zygote
PubMed: 34572116
DOI: 10.3390/cells10092467 -
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 -
Frontiers in Plant Science 2022In plants, embryogenesis and reproduction are not strictly dependent on fertilization. Several species can produce embryos in seeds asexually, a process known as... (Review)
Review
In plants, embryogenesis and reproduction are not strictly dependent on fertilization. Several species can produce embryos in seeds asexually, a process known as apomixis. Apomixis is defined as clonal asexual reproduction through seeds, whereby the progeny is identical to the maternal genotype, and provides valuable opportunities for developing superior cultivars, as its induction in agricultural crops can facilitate the development and maintenance of elite hybrid genotypes. In this review, we summarize the current understanding of apomixis and highlight the successful introduction of apomixis methods into sexual crops. In addition, we discuss several genes whose overexpression can induce somatic embryogenesis as candidate genes to induce parthenogenesis, a unique reproductive method of gametophytic apomixis. We also summarize three schemes to achieve engineered apomixis, which will offer more opportunities for the realization of apomictic reproduction.
PubMed: 35371148
DOI: 10.3389/fpls.2022.864987 -
Medical Hypotheses Sep 2017Spontaneous parthenogenetic and androgenetic events occur in humans, but they result in tumours: the ovarian teratoma and the hydatidiform mole, respectively. However,...
Spontaneous parthenogenetic and androgenetic events occur in humans, but they result in tumours: the ovarian teratoma and the hydatidiform mole, respectively. However, the observation of fetiform (ovarian) teratomas, the serependious identification of several chimeric human parthenotes and androgenotes in the last two decades, along with the creation of viable bi-maternal mice in the laboratory based on minor genetic interferences, raises the question of whether natural cases of clinically healthy human parthenotes have gone unnoticed to science. Here we present a hypothesis based on three elements to support the existence of such elusive individuals: mutations affecting (i) genomic imprinting, (ii) meiosis and (iii) oocyte activation. Additionally, we suggest that the routine practice of whole genome sequencing on every single newborn worldwide will be the ultimate test to this controversial, yet astonishing hypothesis. Finally, several medical implications of such intriguing event are presented.
Topics: Animals; Chimera; Diploidy; Female; Genomic Imprinting; Heterozygote; Humans; Meiosis; Mice; Models, Genetic; Mutation; Oocytes; Ovarian Neoplasms; Parthenogenesis; Teratoma; Whole Genome Sequencing
PubMed: 28818272
DOI: 10.1016/j.mehy.2017.07.008