1
|
Wiberg RAW, Brand JN, Viktorin G, Mitchell JO, Beisel C, Schärer L. Genome assemblies of the simultaneously hermaphroditic flatworms Macrostomum cliftonense and Macrostomum hystrix. G3 (BETHESDA, MD.) 2023; 13:jkad149. [PMID: 37398989 PMCID: PMC10468722 DOI: 10.1093/g3journal/jkad149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 06/05/2023] [Accepted: 06/21/2023] [Indexed: 07/04/2023]
Abstract
The free-living, simultaneously hermaphroditic flatworms of the genus Macrostomum are increasingly used as model systems in various contexts. In particular, Macrostomum lignano, the only species of this group with a published genome assembly, has emerged as a model for the study of regeneration, reproduction, and stem-cell function. However, challenges have emerged due to M. lignano being a hidden polyploid, having recently undergone whole-genome duplication and chromosome fusion events. This complex genome architecture presents a significant roadblock to the application of many modern genetic tools. Hence, additional genomic resources for this genus are needed. Here, we present such resources for Macrostomum cliftonense and Macrostomum hystrix, which represent the contrasting mating behaviors of reciprocal copulation and hypodermic insemination found in the genus. We use a combination of PacBio long-read sequencing and Illumina shot-gun sequencing, along with several RNA-Seq data sets, to assemble and annotate highly contiguous genomes for both species. The assemblies span ∼227 and ∼220 Mb and are represented by 399 and 42 contigs for M. cliftonense and M. hystrix, respectively. Furthermore, high BUSCO completeness (∼84-85%), low BUSCO duplication rates (8.3-6.2%), and low k-mer multiplicity indicate that these assemblies do not suffer from the same assembly ambiguities of the M. lignano genome assembly, which can be attributed to the complex karyology of this species. We also show that these resources, in combination with the prior resources from M. lignano, offer an excellent foundation for comparative genomic research in this group of organisms.
Collapse
Affiliation(s)
- R Axel W Wiberg
- Department of Environmental Sciences, Zoological Institute, University of Basel, Basel 4051, Switzerland
| | - Jeremias N Brand
- Department of Environmental Sciences, Zoological Institute, University of Basel, Basel 4051, Switzerland
| | - Gudrun Viktorin
- Department of Environmental Sciences, Zoological Institute, University of Basel, Basel 4051, Switzerland
| | - Jack O Mitchell
- Department of Environmental Sciences, Zoological Institute, University of Basel, Basel 4051, Switzerland
| | - Christian Beisel
- Department of Biosystems Science and Engineering, ETH Zürich, Basel 4058, Switzerland
| | - Lukas Schärer
- Department of Environmental Sciences, Zoological Institute, University of Basel, Basel 4051, Switzerland
| |
Collapse
|
2
|
Shi Y, Zeng Z, Wang J, Zhang S, Deng L, Wang A. Three new species of Macrostomum (Platyhelminthes, Macrostomorpha) from China and Australia, with notes on taxonomy and phylogenetics. Zookeys 2022; 1099:1-28. [PMID: 36761444 PMCID: PMC9848920 DOI: 10.3897/zookeys.1099.72964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 03/31/2022] [Indexed: 11/12/2022] Open
Abstract
In this paper, three species of the macrostomid free-living flatworm genus Macrostomum are described. Two species, Macrostomumlittorale Wang & Shi, sp. nov. and M.shekouense Wang & Shi, sp. nov., were collected from coastal water at Shenzhen, Guangdong Province, China. One species, M.brandi Wang & Shi, sp. nov., was collected from Perth, Western Australia and Queenscliff, Victoria, Australia. Macrostomumlittorale sp. nov. differs from congeneric species within the genus in the length of the stylet, diameter of stylet opening, and the bend of the stylet. Macrostomumshekouense sp. nov. and M.brandi sp. nov. differ from similar species within the genus in the stylet morphology, position of the female antrum and developing eggs, or presence or absence of the false seminal vesicle. Phylogenetic analysis based on cytochrome c oxidase subunit I (COI) gene shows that M.littorale sp. nov. and M.hystrix are sister clades on two well-separated branch, M.shekouense sp. nov. and M.brandi sp. nov. are sister clades on two well-separated branches. Accordingly, both morphological and molecular evidence support M.littorale sp. nov., M.shekouense sp. nov., and M.brandi sp. nov. as three new species.
Collapse
Affiliation(s)
- Yongshi Shi
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, ChinaShenzhen UniversityShenzhenChina
| | - Zhiyu Zeng
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, ChinaShenzhen UniversityShenzhenChina
| | - Jia Wang
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, ChinaShenzhen UniversityShenzhenChina
| | - Siyu Zhang
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, ChinaShenzhen UniversityShenzhenChina
| | - Li Deng
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, ChinaShenzhen UniversityShenzhenChina
| | - Antai Wang
- Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518055, ChinaShenzhen UniversityShenzhenChina
| |
Collapse
|
3
|
TIM29 is required for enhanced stem cell activity during regeneration in the flatworm Macrostomum lignano. Sci Rep 2021; 11:1166. [PMID: 33441924 PMCID: PMC7806878 DOI: 10.1038/s41598-020-80682-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 12/10/2020] [Indexed: 01/29/2023] Open
Abstract
TIM29 is a mitochondrial inner membrane protein that interacts with the protein import complex TIM22. TIM29 was shown to stabilize the TIM22 complex but its biological function remains largely unknown. Until recently, it was classified as one of the Domain of Unknown Function (DUF) genes, with a conserved protein domain DUF2366 of unclear function. Since characterizing DUF genes can provide novel biological insight, we used previously established transcriptional profiles of the germline and stem cells of the flatworm Macrostomum lignano to probe conserved DUFs for their potential role in germline biology, stem cell function, regeneration, and development. Here, we demonstrate that DUF2366/TIM29 knockdown in M. lignano has very limited effect during the normal homeostatic condition but prevents worms from adapting to a highly proliferative state required for regeneration.
Collapse
|
4
|
Adami M, Damborenea C. Life history of the freshwater microturbellarian Macrostomum velastylum (Macrostomorpha) in the Neotropical region. STUDIES ON NEOTROPICAL FAUNA AND ENVIRONMENT 2020. [DOI: 10.1080/01650521.2020.1835294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Mariana Adami
- División Zoología Invertebrados, Facultad de Ciencias Naturales y Museo, UNLP, La Plata, Argentina, CONICET, Argentina
| | - Cristina Damborenea
- División Zoología Invertebrados, Facultad de Ciencias Naturales y Museo, UNLP, La Plata, Argentina, CONICET, Argentina
| |
Collapse
|
5
|
Kaufmann P, Schärer L. Is the initiation of selfing linked to a hermaphrodite's female or male reproductive function? Behav Ecol Sociobiol 2020; 74:41. [PMID: 32214615 PMCID: PMC7080307 DOI: 10.1007/s00265-020-2816-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 02/11/2020] [Accepted: 02/24/2020] [Indexed: 11/30/2022]
Abstract
ABSTRACT There is an ongoing debate about whether simultaneous hermaphrodites capable of selfing should prefer selfing over outcrossing or vice versa. While many theoretical models predict a transmission advantage for alleles that favour selfing, empirical studies often reveal low selfing rates. Despite these considerations, the underlying mechanisms that determine reproductive strategies in simultaneously hermaphroditic animals are poorly understood. In our study on the facultatively selfing free-living flatworm, Macrostomum hystrix, we ask whether the initiation of selfing, as inferred from the differential spatial distribution of received sperm, is linked to an individual's female or male reproductive function. Specifically, the initiation of selfing could (i) be linked to the male function, when an individual is unable to donate sperm to others and hence donates sperm to self, or it could (ii) be linked to the female function, when an individual fails to receive sperm from others-and hence is unable to fertilize its eggs via outcrossing-thus inducing it to self-fertilize. We experimentally created a social environment that allowed focals to outcross via sperm donation, but simultaneously prevented them from receiving sperm-by pairing them with a partner lacking the male copulatory organ-so that fertilization of the focal's eggs was restricted to selfing. Our results suggest that such focals generally do not initiate selfing, while we readily observe selfing in isolated worms. This suggests that in isolated M. hystrix, it is the male function that is linked to the initiation of selfing, likely due to a lack of opportunities for sperm donation. SIGNIFICANCE STATEMENT A variety of simultaneously hermaphroditic animals are capable of reproducing via both selfing and outcrossing. While the reproductive choices of such animals can be modelled by the joint action of genetic (e.g. inbreeding depression) and ecological factors (e.g. partner availability), experimental evaluation of theoretical results is often lacking. By manipulating the social environment of focal individuals, we here provide evidence that explores the respective role that the co-occurring male and female sex functions have on the initiation of selfing in a simultaneously hermaphroditic flatworm species. Specifically, our results suggest that the initiation of selfing is linked to the worm's male function. Insights about which function is linked to the initiation of selfing may ultimately help to better understand reproductive decisions in simultaneous hermaphrodites.
Collapse
Affiliation(s)
- Philipp Kaufmann
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
- Present Address: Department of Evolutionary Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18D, 752 36 Uppsala, Sweden
| | - Lukas Schärer
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
| |
Collapse
|
6
|
Schärer L, Brand JN, Singh P, Zadesenets KS, Stelzer C, Viktorin G. A phylogenetically informed search for an alternative
Macrostomum
model species, with notes on taxonomy, mating behavior, karyology, and genome size. J ZOOL SYST EVOL RES 2019. [DOI: 10.1111/jzs.12344] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Lukas Schärer
- Evolutionary Biology Zoological Institute University of Basel Basel Switzerland
| | - Jeremias N. Brand
- Evolutionary Biology Zoological Institute University of Basel Basel Switzerland
| | - Pragya Singh
- Evolutionary Biology Zoological Institute University of Basel Basel Switzerland
| | - Kira S. Zadesenets
- The Federal Research Center Institute of Cytology and Genetics SB RAS Novosibirsk Russia
| | | | - Gudrun Viktorin
- Evolutionary Biology Zoological Institute University of Basel Basel Switzerland
| |
Collapse
|
7
|
Mouton S, Grudniewska M, Glazenburg L, Guryev V, Berezikov E. Resilience to aging in the regeneration-capable flatworm Macrostomum lignano. Aging Cell 2018; 17:e12739. [PMID: 29488325 PMCID: PMC5946080 DOI: 10.1111/acel.12739] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/19/2018] [Indexed: 12/15/2022] Open
Abstract
Animals show a large variability of lifespan, ranging from short-lived as Caenorhabditis elegans to immortal as Hydra. A fascinating case is flatworms, in which reversal of aging by regeneration is proposed, yet conclusive evidence for this rejuvenation-by-regeneration hypothesis is lacking. We tested this hypothesis by inducing regeneration in the sexual free-living flatworm Macrostomum lignano. We studied survival, fertility, morphology, and gene expression as a function of age. Here, we report that after regeneration, genes expressed in the germline are upregulated at all ages, but no signs of rejuvenation are observed. Instead, the animal appears to be substantially longer lived than previously appreciated, and genes expressed in stem cells are upregulated with age, while germline genes are downregulated. Remarkably, several genes with known beneficial effects on lifespan when overexpressed in mice and C. elegans are naturally upregulated with age in M. lignano, suggesting that molecular mechanism for offsetting negative consequences of aging has evolved in this animal. We therefore propose that M. lignano represents a novel powerful model for molecular studies of aging attenuation, and the identified aging gene expression patterns provide a valuable resource for further exploration of anti-aging strategies.
Collapse
Affiliation(s)
- Stijn Mouton
- European Research Institute for the Biology of AgeingUniversity of GroningenUniversity Medical Center GroningenGroningenThe Netherlands
| | - Magda Grudniewska
- European Research Institute for the Biology of AgeingUniversity of GroningenUniversity Medical Center GroningenGroningenThe Netherlands
| | - Lisa Glazenburg
- European Research Institute for the Biology of AgeingUniversity of GroningenUniversity Medical Center GroningenGroningenThe Netherlands
| | - Victor Guryev
- European Research Institute for the Biology of AgeingUniversity of GroningenUniversity Medical Center GroningenGroningenThe Netherlands
| | - Eugene Berezikov
- European Research Institute for the Biology of AgeingUniversity of GroningenUniversity Medical Center GroningenGroningenThe Netherlands
| |
Collapse
|
8
|
Grudniewska M, Mouton S, Grelling M, Wolters AHG, Kuipers J, Giepmans BNG, Berezikov E. A novel flatworm-specific gene implicated in reproduction in Macrostomum lignano. Sci Rep 2018; 8:3192. [PMID: 29453392 PMCID: PMC5816591 DOI: 10.1038/s41598-018-21107-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 01/30/2018] [Indexed: 12/20/2022] Open
Abstract
Free-living flatworms, such as the planarian Schmidtea mediterranea, are extensively used as model organisms to study stem cells and regeneration. The majority of flatworm studies so far focused on broadly conserved genes. However, investigating what makes these animals different is equally informative for understanding its biology and might have biomedical value. We re-analyzed the neoblast and germline transcriptional signatures of the flatworm M. lignano using an improved transcriptome assembly and show that germline-enriched genes have a high fraction of flatworm-specific genes. We further identified the Mlig-sperm1 gene as a member of a novel gene family conserved only in free-living flatworms and essential for producing healthy spermatozoa. In addition, we established a whole-animal electron microscopy atlas (nanotomy) to visualize the ultrastructure of the testes in wild type worms, but also as a reference platform for different ultrastructural studies in M. lignano. This work demonstrates that investigation of flatworm-specific genes is crucial for understanding flatworm biology and establishes a basis for such future research in M. lignano.
Collapse
Affiliation(s)
- Magda Grudniewska
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, 9713AV, Groningen, The Netherlands
| | - Stijn Mouton
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, 9713AV, Groningen, The Netherlands
| | - Margriet Grelling
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, 9713AV, Groningen, The Netherlands
| | - Anouk H G Wolters
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, 9713AV, Groningen, The Netherlands
| | - Jeroen Kuipers
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, 9713AV, Groningen, The Netherlands
| | - Ben N G Giepmans
- Department of Cell Biology, University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, 9713AV, Groningen, The Netherlands
| | - Eugene Berezikov
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Antonius Deusinglaan 1, 9713AV, Groningen, The Netherlands.
| |
Collapse
|
9
|
Lai AG, Aboobaker AA. EvoRegen in animals: Time to uncover deep conservation or convergence of adult stem cell evolution and regenerative processes. Dev Biol 2018; 433:118-131. [PMID: 29198565 DOI: 10.1016/j.ydbio.2017.10.010] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 10/09/2017] [Accepted: 10/10/2017] [Indexed: 01/08/2023]
Abstract
How do animals regenerate specialised tissues or their entire body after a traumatic injury, how has this ability evolved and what are the genetic and cellular components underpinning this remarkable feat? While some progress has been made in understanding mechanisms, relatively little is known about the evolution of regenerative ability. Which elements of regeneration are due to lineage specific evolutionary novelties or have deeply conserved roots within the Metazoa remains an open question. The renaissance in regeneration research, fuelled by the development of modern functional and comparative genomics, now enable us to gain a detailed understanding of both the mechanisms and evolutionary forces underpinning regeneration in diverse animal phyla. Here we review existing and emerging model systems, with the focus on invertebrates, for studying regeneration. We summarize findings across these taxa that tell us something about the evolution of adult stem cell types that fuel regeneration and the growing evidence that many highly regenerative animals harbor adult stem cells with a gene expression profile that overlaps with germline stem cells. We propose a framework in which regenerative ability broadly evolves through changes in the extent to which stem cells generated through embryogenesis are maintained into the adult life history.
Collapse
Affiliation(s)
- Alvina G Lai
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom
| | - A Aziz Aboobaker
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom.
| |
Collapse
|
10
|
Schärer L. The varied ways of being male and female. Mol Reprod Dev 2017; 84:94-104. [PMID: 28032683 DOI: 10.1002/mrd.22775] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Accepted: 12/23/2016] [Indexed: 12/18/2022]
Abstract
Our understanding of sexual reproduction is mainly informed by research on gonochorists (i.e., species with separate sexes), including insects, birds, and mammals. But the male and female sexes are not two types of individuals; they actually represent two different reproductive strategies, and in many organisms, these two strategies are distributed among individuals in a population in a variety of ways. For example, sequential hermaphrodites (or sex-changers) exhibit one strategy early in life and later switch to the other, while simultaneous hermaphrodites exhibit both strategies at the same time. There are also many intermediate sexual systems that mix gonochorists and hermaphrodites in the same species and within many organismal groups, shifts occur between these sexual systems. A fascinating collection of six articles in this special issue on Hermaphroditism & Sex Determination impressively documents some important challenges to our understanding of sex determination, and the specification of male and female reproductive function when these need to occur within the same individual rather than in two separate individuals. Moreover, hermaphroditism changes how we need to think about reproductive allocation to sexual functions, how such allocation can be specified, as well as how the sexual system affects sexual conflict and the resulting antagonistic coevolution. Our understanding of sexual reproduction will profit greatly from exploring the varied ways of being male and female. Mol. Reprod. Dev. 84: 94-104, 2017. © 2017 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Lukas Schärer
- Evolutionary Biology, Zoological Institute, University of Basel, Basel, Switzerland
| |
Collapse
|
11
|
Giannakara A, Ramm SA. Self-fertilization, sex allocation and spermatogenesis kinetics in the hypodermically inseminating flatworm Macrostomum pusillum. ACTA ACUST UNITED AC 2017; 220:1568-1577. [PMID: 28183866 DOI: 10.1242/jeb.149682] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 02/03/2017] [Indexed: 01/15/2023]
Abstract
The free-living flatworm genus Macrostomum is an emerging model system for studying the links between sex allocation, sexual selection and mating system evolution, as well as the underlying developmental and physiological mechanisms responsible for wide intra- and inter-specific variability in reproductive phenotypes. Despite compelling comparative morphological evidence of sexual diversity, detailed experimental work on reproductive behaviour and physiology in Macrostomum has so far been largely limited to just two species, M. lignano and M. hystrix, an obligate and a preferential outcrosser, respectively. In this study, we establish that a third species, M. pusillum, exhibits a combination of reproductive traits strikingly different from both of its congeners. Unlike M. lignano, we demonstrate that M. pusillum does not adjust sex allocation or the speed of spermatogenesis to the prevailing social group size. Macrostomumpusillum's relatively simple sperm morphology likely explains the short spermatogenesis duration we report, and is linked to a hypodermically inseminating mode of fertilization, which we show also means that these worms are capable of self-fertilization. Surprisingly, and unlike M. hystrix, selfing in isolated worms commences after only a short (if any) delay compared with the onset of reproduction in grouped individuals, with little evidence of differential inbreeding depression in 'isolated' progeny. These combined results suggest that, in nature, M. pusillum may be regularly selfing, in contrast to the congeners studied to date. Our findings highlight the rapid and correlated evolution of reproductive traits, and reinforce the utility of the genus Macrostomum for understanding the evolutionary and developmental mechanisms responsible for this diversity.
Collapse
Affiliation(s)
- Athina Giannakara
- Evolutionary Biology, Bielefeld University, Morgenbreede 45, Bielefeld 33615, Germany
| | - Steven A Ramm
- Evolutionary Biology, Bielefeld University, Morgenbreede 45, Bielefeld 33615, Germany
| |
Collapse
|
12
|
Gammoudi M, Salvenmoser W, Tekaya S, Egger B. Ultrastructure of the ovary and oogenesis in the flatwormProsthiostomum siphunculus(Polycladida, Cotylea). Cell Biol Int 2016; 40:1174-1186. [DOI: 10.1002/cbin.10657] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 08/13/2016] [Indexed: 12/24/2022]
Affiliation(s)
- Mehrez Gammoudi
- Université de Tunis El manar, Faculté des Sciences de Tunis; UR11ES12 Biologie de la reproduction et du Développement animal; 2092 El Manar Tunis Tunisia
| | - Willi Salvenmoser
- Research Unit Evolutionary Developmental Biology; Institute of Zoology; University of Innsbruck; Technikerstr. 25 6020 Innsbruck Austria
| | - Saïda Tekaya
- Université de Tunis El manar, Faculté des Sciences de Tunis; UR11ES12 Biologie de la reproduction et du Développement animal; 2092 El Manar Tunis Tunisia
| | - Bernhard Egger
- Research Unit Evolutionary Developmental Biology; Institute of Zoology; University of Innsbruck; Technikerstr. 25 6020 Innsbruck Austria
| |
Collapse
|
13
|
Ramm SA. Exploring the sexual diversity of flatworms: Ecology, evolution, and the molecular biology of reproduction. Mol Reprod Dev 2016; 84:120-131. [PMID: 27292123 DOI: 10.1002/mrd.22669] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Accepted: 06/01/2016] [Indexed: 12/12/2022]
Abstract
Flatworms exhibit huge diversity in their reproductive biology, making this group an excellent model system for exploring how differences among species in reproductive ecology are reflected in the physiological and molecular details of how reproduction is achieved. In this review, I consider five key "lifestyle choices" (i.e., alternative evolutionary/developmental outcomes) that collectively encompass much of flatworm sexual diversity, beginning with the decisions: (i) whether to be free-living or parasitic; (ii) whether to reproduce asexually or sexually; and (iii) whether to be gonochoristic (separate-sexed) or hermaphroditic. I then examine two further decisions involving hermaphroditism: (iv) outcrossing versus selfing and (v) the balance of investment into the male versus the female sex function (sex allocation). Collectively, these lifestyle choices set the basic rules for how reproduction occurs, but as I emphasize in the second part of the review, the reproductive biology of flatworms is also greatly impacted by the near-pervasive and powerful pressure of sexual selection, together with the related phenomena of sperm competition and sexual conflict. Exactly how this plays out, however, is strongly affected by the particular combination of reproductive strategies adopted by each species. Mol. Reprod. Dev. 84: 120-131, 2017. © 2016 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Steven A Ramm
- Department of Evolutionary Biology, Bielefeld University, Bielefeld, Germany
| |
Collapse
|
14
|
Gammoudi M, Salvenmoser W, Harrath AH, Tekaya S, Egger B. Ultrastructure of spermatogenesis and mature spermatozoa in the flatworm
Prosthiostomum siphunculus
(Polycladida, Cotylea). Cell Biol Int 2015; 40:277-88. [DOI: 10.1002/cbin.10562] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 11/01/2015] [Indexed: 11/08/2022]
Affiliation(s)
- Mehrez Gammoudi
- Université de Tunis El‐ManarFaculté des Sciences de TunisUR11ES12 Biologie de la Reproduction et du Développement AnimalTunis2092Tunisie
| | - Willi Salvenmoser
- Research Unit Evolutionary Developmental Biology, Institute of ZoologyUniversity of InnsbruckTechnikerstr. 25Innsbruck6020Austria
| | - Abdel Halim Harrath
- Department of Zoology, College of ScienceKing Saud UniversityP.O. Box 2455RiyadhSaudi Arabia
| | - Saïda Tekaya
- Université de Tunis El‐ManarFaculté des Sciences de TunisUR11ES12 Biologie de la Reproduction et du Développement AnimalTunis2092Tunisie
| | - Bernhard Egger
- Research Unit Evolutionary Developmental Biology, Institute of ZoologyUniversity of InnsbruckTechnikerstr. 25Innsbruck6020Austria
| |
Collapse
|
15
|
Arbore R, Sekii K, Beisel C, Ladurner P, Berezikov E, Schärer L. Positional RNA-Seq identifies candidate genes for phenotypic engineering of sexual traits. Front Zool 2015; 12:14. [PMID: 26146508 PMCID: PMC4490696 DOI: 10.1186/s12983-015-0106-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 05/15/2015] [Indexed: 12/11/2022] Open
Abstract
INTRODUCTION RNA interference (RNAi) of trait-specific genes permits the manipulation of specific phenotypic traits ("phenotypic engineering") and thus represents a powerful tool to test trait function in evolutionary studies. The identification of suitable candidate genes, however, often relies on existing functional gene annotation, which is usually limited in emerging model organisms, especially when they are only distantly related to traditional genetic model organisms. A case in point is the free-living flatworm Macrostomum lignano (Lophotrochozoa: Platyhelminthes: Rhabditophora), an increasingly powerful model organism for evolutionary studies of sex in simultaneous hermaphrodites. To overcome the limitation of sparse functional annotation, we have performed a positional RNA-Seq analysis on different body fragments in order to identify organ-specific candidate transcripts. We then performed gene expression (in situ hybridization) and gene function (RNAi) analyses on 23 candidate transcripts, both to evaluate the predictive potential of this approach and to obtain preliminary functional characterizations of these candidate genes. RESULTS We identified over 4000 transcripts that could be expected to show specific expression in different reproductive organs (including testis, ovary and the male and female genital systems). The predictive potential of the method could then be verified by confirming organ-specific expression for several candidate transcripts, some of which yielded interesting trait-specific knock-down phenotypes that can now be followed up in future phenotypic engineering studies. CONCLUSIONS Our positional RNA-Seq analysis represents a highly useful resource for the identification of candidate transcripts for functional and phenotypic engineering studies in M. lignano, and it has already been used successfully in several studies. Moreover, this approach can overcome some inherent limitations of homology-based candidate selection and thus should be applicable to a broad range of emerging model organisms.
Collapse
Affiliation(s)
- Roberto Arbore
- />Evolutionary Biology, Zoological Institute, University of Basel, Vesalgasse 1, CH-4051 Basel, Switzerland
| | - Kiyono Sekii
- />Evolutionary Biology, Zoological Institute, University of Basel, Vesalgasse 1, CH-4051 Basel, Switzerland
| | | | - Peter Ladurner
- />Institute of Zoology and CMBI, University of Innsbruck, Innsbruck, Austria
| | - Eugene Berezikov
- />ERIBA, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Lukas Schärer
- />Evolutionary Biology, Zoological Institute, University of Basel, Vesalgasse 1, CH-4051 Basel, Switzerland
| |
Collapse
|
16
|
Lapraz F, Rawlinson KA, Girstmair J, Tomiczek B, Berger J, Jékely G, Telford MJ, Egger B. Put a tiger in your tank: the polyclad flatworm Maritigrella crozieri as a proposed model for evo-devo. EvoDevo 2013; 4:29. [PMID: 24107307 PMCID: PMC4124852 DOI: 10.1186/2041-9139-4-29] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 08/14/2013] [Indexed: 12/02/2022] Open
Abstract
Polyclad flatworms are an early branching clade within the rhabditophoran Platyhelminthes. They provide an interesting system with which to explore the evolution of development within Platyhelminthes and amongst Spiralia (Lophotrochozoa). Unlike most other flatworms, polyclads undergo spiral cleavage (similar to that seen in some other spiralian taxa), they are the only free-living flatworms where development via a larval stage occurs, and they are the only flatworms in which embryos can be reared outside of their protective egg case, enabling embryonic manipulations. Past work has focused on comparing early cleavage patterns and larval anatomy between polyclads and other spiralians. We have selected Maritigrella crozieri, the tiger flatworm, as a suitable polyclad species for developmental studies, because it is abundant and large in size compared to other species. These characteristics have facilitated the generation of a transcriptome from embryonic and larval material and are enabling us to develop methods for gene expression analysis and immunofluorescence techniques. Here we give an overview of M. crozieri and its development, we highlight the advantages and current limitations of this animal as a potential evo-devo model and discuss current lines of research.
Collapse
Affiliation(s)
- François Lapraz
- Department of Genetics, Evolution and Environment, University College London, London, UK.
| | | | | | | | | | | | | | | |
Collapse
|
17
|
Measurement of S-phase duration of adult stem cells in the flatworm Macrostomum lignano by double replication labelling and quantitative colocalization analysis. Cell Biol Int 2013; 36:1251-9. [PMID: 23005924 DOI: 10.1042/cbi20120187] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Platyhelminthes are highly attractive models for addressing fundamental aspects of stem cell biology in vivo. These organisms possess a unique stem cell system comprised of neoblasts that are the only proliferating cells during adulthood. We have investigated Ts (S-phase duration) of neoblasts during homoeostasis and regeneration in the flatworm, Macrostomum lignano. A double immunohistochemical technique was used, performing sequential pulses with the thymidine analogues CldU (chlorodeoxyuridine) and IdU (iododeoxyuridine), separated by variable chase times in the presence of colchicine. Owing to the localized nature of the fluorescent signals (cell nuclei) and variable levels of autofluorescence, standard intensity-based colocalization analyses could not be applied to accurately determine the colocalization. Therefore, an object-based colocalization approach was devised to score the relative number of double-positive cells. Using this approach, Ts (S-phase duration) in the main population of neoblasts was ∼13 h. During early regeneration, no significant change in Ts was observed.
Collapse
|
18
|
Sekii K, Vizoso DB, Kuales G, De Mulder K, Ladurner P, Schärer L. Phenotypic engineering of sperm-production rate confirms evolutionary predictions of sperm competition theory. Proc Biol Sci 2013; 280:20122711. [PMID: 23446521 DOI: 10.1098/rspb.2012.2711] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Sperm production is a key male reproductive trait and an important parameter in sperm competition theory. Under sperm competition, paternity success is predicted to depend strongly on male allocation to sperm production. Furthermore, because sperm production is inherently costly, individuals should economize in sperm expenditure, and conditional adjustment of the copulation frequency according to their sperm availability may be expected. However, experimental studies showing effects of sperm production on mating behaviour and paternity success have so far been scarce, mainly because sperm production is difficult to manipulate directly in animals. Here, we used phenotypic engineering to manipulate sperm-production rate, by employing dose-dependent RNA interference (RNAi) of a spermatogenesis-specific gene, macbol1, in the free-living flatworm Macrostomum lignano. We demonstrate (i) that our novel dose-dependent RNAi approach allows us to induce high variability in sperm-production rate; (ii) that a reduced sperm-production rate is associated with a decreased copulation frequency, suggesting conditional adjustment of mating behaviour; and (iii) that both sperm production and copulation frequency are important determinants of paternity success in a competitive situation, as predicted by sperm competition theory. Our study clearly documents the potential of phenotypic engineering via dose-dependent RNAi to test quantitative predictions of evolutionary theory.
Collapse
Affiliation(s)
- Kiyono Sekii
- Evolutionary Biology, Zoological Institute, University of Basel, , Basel, Switzerland, Department of Zoology, University of Oxford, Oxford, UK.
| | | | | | | | | | | |
Collapse
|
19
|
De Mulder K, Kuales G, Pfister D, Egger B, Seppi T, Eichberger P, Borgonie G, Ladurner P. Potential of Macrostomum lignano to recover from gamma-ray irradiation. Cell Tissue Res 2010; 339:527-42. [PMID: 20127258 PMCID: PMC2831187 DOI: 10.1007/s00441-009-0915-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Accepted: 12/10/2009] [Indexed: 12/27/2022]
Abstract
Stem cells are the only proliferating cells in flatworms and can be eliminated by irradiation with no damage to differentiated cells. We investigated the effect of fractionated irradiation schemes on Macrostomum lignano, namely, on survival, gene expression, morphology and regeneration. Proliferating cells were almost undetectable during the first week post-treatment. Cell proliferation and gene expression were restored within 1 month in a dose-dependent manner following exposure to up to 150 Gy irradiation. During recovery, stem cells did not cross the midline but were restricted within lateral compartments. An accumulated dose of 210 Gy resulted in a lethal phenotype. Our findings demonstrate that M. lignano represents a suitable model system for elucidating the effect of irradiation on the stem cell system in flatworms and for improving our understanding of the recovery potential of severely damaged stem-cell systems.
Collapse
Affiliation(s)
- Katrien De Mulder
- Institute of Zoology and Center for Molecular Biosciences, University of Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
- Department of Biology, University of Ghent, Ledeganckstraat 35, 9000 Ghent, Belgium
- Present Address: Hubrecht Institute, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Georg Kuales
- Institute of Zoology and Center for Molecular Biosciences, University of Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
| | - Daniela Pfister
- Institute of Zoology and Center for Molecular Biosciences, University of Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
| | - Bernhard Egger
- Institute of Zoology and Center for Molecular Biosciences, University of Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
| | - Thomas Seppi
- Department of Radiotherapy and Radiation Oncology, Innsbruck Medical University Hospital, Innsbruck Medical University, Anichstrasse 35, 6020 Innsbruck, Austria
| | - Paul Eichberger
- Department of Radiotherapy and Radiation Oncology, Innsbruck Medical University Hospital, Innsbruck Medical University, Anichstrasse 35, 6020 Innsbruck, Austria
| | - Gaetan Borgonie
- Department of Biology, University of Ghent, Ledeganckstraat 35, 9000 Ghent, Belgium
| | - Peter Ladurner
- Institute of Zoology and Center for Molecular Biosciences, University of Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
| |
Collapse
|
20
|
De Mulder K, Kuales G, Pfister D, Willems M, Egger B, Salvenmoser W, Thaler M, Gorny AK, Hrouda M, Borgonie G, Ladurner P. Characterization of the stem cell system of the acoel Isodiametra pulchra. BMC DEVELOPMENTAL BIOLOGY 2009; 9:69. [PMID: 20017953 PMCID: PMC2806412 DOI: 10.1186/1471-213x-9-69] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Accepted: 12/18/2009] [Indexed: 12/27/2022]
Abstract
Background Tissue plasticity and a substantial regeneration capacity based on stem cells are the hallmark of several invertebrate groups such as sponges, cnidarians and Platyhelminthes. Traditionally, Acoela were seen as an early branching clade within the Platyhelminthes, but became recently positioned at the base of the Bilateria. However, little is known on how the stem cell system in this new phylum is organized. In this study, we wanted to examine if Acoela possess a neoblast-like stem cell system that is responsible for development, growth, homeostasis and regeneration. Results We established enduring laboratory cultures of the acoel Isodiametra pulchra (Acoela, Acoelomorpha) and implemented in situ hybridization and RNA interference (RNAi) for this species. We used BrdU labelling, morphology, ultrastructure and molecular tools to illuminate the morphology, distribution and plasticity of acoel stem cells under different developmental conditions. We demonstrate that neoblasts are the only proliferating cells which are solely mesodermally located within the organism. By means of in situ hybridisation and protein localisation we could demonstrate that the piwi-like gene ipiwi1 is expressed in testes, ovaries as well as in a subpopulation of somatic stem cells. In addition, we show that germ cell progenitors are present in freshly hatched worms, suggesting an embryonic formation of the germline. We identified a potent stem cell system that is responsible for development, homeostasis, regeneration and regrowth upon starvation. Conclusions We introduce the acoel Isodiametra pulchra as potential new model organism, suitable to address developmental questions in this understudied phylum. We show that neoblasts in I. pulchra are crucial for tissue homeostasis, development and regeneration. Notably, epidermal cells were found to be renewed exclusively from parenchymally located stem cells, a situation known only from rhabditophoran flatworms so far. For further comparison, it will be important to analyse the stem cell systems of other key-positioned understudied taxa.
Collapse
Affiliation(s)
- Katrien De Mulder
- University of Innsbruck, Institute of Zoology, Technikerstrasse 25, A-6020 Innsbruck, Austria.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
21
|
Egger B, Gschwentner R, Hess MW, Nimeth KT, Adamski Z, Willems M, Rieger R, Salvenmoser W. The caudal regeneration blastema is an accumulation of rapidly proliferating stem cells in the flatworm Macrostomum lignano. BMC DEVELOPMENTAL BIOLOGY 2009; 9:41. [PMID: 19604404 PMCID: PMC2717932 DOI: 10.1186/1471-213x-9-41] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2009] [Accepted: 07/15/2009] [Indexed: 11/10/2022]
Abstract
BACKGROUND Macrostomum lignano is a small free-living flatworm capable of regenerating all body parts posterior of the pharynx and anterior to the brain. We quantified the cellular composition of the caudal-most body region, the tail plate, and investigated regeneration of the tail plate in vivo and in semithin sections labeled with bromodeoxyuridine, a marker for stem cells (neoblasts) in S-phase. RESULTS The tail plate accomodates the male genital apparatus and consists of about 3,100 cells, about half of which are epidermal cells. A distinct regeneration blastema, characterized by a local accumulation of rapidly proliferating neoblasts and consisting of about 420 cells (excluding epidermal cells), was formed 24 hours after amputation. Differentiated cells in the blastema were observed two days after amputation (with about 920 blastema cells), while the male genital apparatus required four to five days for full differentiation. At all time points, mitoses were found within the blastema. At the place of organ differentiation, neoblasts did not replicate or divide. After three days, the blastema was made of about 1420 cells and gradually transformed into organ primordia, while the proliferation rate decreased. The cell number of the tail plate, including about 960 epidermal cells, was restored to 75% at this time point. CONCLUSION Regeneration after artificial amputation of the tail plate of adult specimens of Macrostomum lignano involves wound healing and the formation of a regeneration blastema. Neoblasts undergo extensive proliferation within the blastema. Proliferation patterns of S-phase neoblasts indicate that neoblasts are either determined to follow a specific cell fate not before, but after going through S-phase, or that they can be redetermined after S-phase. In pulse-chase experiments, dispersed distribution of label suggests that S-phase labeled progenitor cells of the male genital apparatus undergo further proliferation before differentiation, in contrast to progenitor cells of epidermal cells. Mitotic activity and proliferation within the blastema is a feature of M. lignano shared with many other regenerating animals.
Collapse
Affiliation(s)
- Bernhard Egger
- Institute of Zoology, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria.
| | | | | | | | | | | | | | | |
Collapse
|
22
|
Use of freeze-cracking in ontogenetic research in Macrostomum lignano (Macrostomida, Rhabditophora). Dev Genes Evol 2009; 219:273-9. [PMID: 19408011 DOI: 10.1007/s00427-009-0284-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Accepted: 04/01/2009] [Indexed: 10/20/2022]
Abstract
A method for studying whole mount flatworm embryos based on freeze-cracking of the eggs is described. This method allows successful immunohistological and immunocytological studies of whole mount embryos. It does not require the use of sharpened needles or a microinjection system to puncture the eggshell. Moreover, this method is more practical and less time-consuming than classical puncturing and much cheaper than the use of a microinjection system. The advantages of this method are illustrated by results of several immunolocalisation experiments in the macrostomid flatworm Macrostomum lignano. The optimal procedure and crucial steps for this method are discussed.
Collapse
|