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1

A robust molecular phylogeny of the Tricladida (Platyhelminthes: Seriata) with a discussion on  

E-print Network

(marine planarians); (ii) the Cavernicola (a group of primarily cavernicolan planarians); (iii) the Paludicola (freshwater planarians); and (iv) the Terricola (land planarians). The phylogenetic relationshipsDNA; Tricladida; planarians; Platyhelminthes; phylogeny 1. INTRODUCTION Within the free-living platyhelminthes

Carranza, Salvador

2

Occurrence and abundance of a mariner-like element in freshwater and terrestrial planarians (Platyhelminthes, Tricladida) from southern Brazil  

PubMed Central

Transposable elements are DNA sequences present in all the large phylogenetic groups, both capable of changing position within the genome and constituting a significant part of eukaryotic genomes. The mariner family of transposons is one of the few which occurs in a wide variety of taxonomic groups, including freshwater planarians. Nevertheless, so far only five planarian species have been reported to carry mariner-like elements (MLEs), although several different species have been investigated. Regarding the number of copies of MLEs, Girardia tigrina is the only planarian species in which this has been evaluated, with an estimation of 8,000 copies of the element per haploid genome. Preliminary results obtained in our laboratory demonstrated that MLE is found in a large number of different species of planarians, including terrestrial. With this in mind, the aim was to evaluate the occurrence and estimate the number of MLE copies in different planarian species collected in south Brazil. Twenty-eight individuals from 15 planarian species were analyzed. By using PCR and the hybridization of nucleic acids, it was found that MLE was present in all the analyzed species, the number of copies being high, probably over 103 per haploid genome. PMID:21637447

2009-01-01

3

Genetic network of the eye in Platyhelminthes: expression and functional analysis of some players during planarian regeneration  

Microsoft Academic Search

Planarians are the free-living members (order Tricladida) of the phylum Platyhelminthes. They are triploblastic, acoelomate, unsegmented and located at the base of the Lophotrochozoa clade. Besides their huge regenerative capacity, planarians have simple eyes, considered similar to the prototypic eye suggested by Charles Darwin in his book ‘On the Origin of Species’. The conserved genetic network that determines the initial

Emili Saló; David Pineda; Maria Marsal; Javier Gonzalez; Vittorio Gremigni; Renata Batistoni

2002-01-01

4

Origin and Evolution of Paralogous rRNA Gene Clusters Within the Flatworm Family Dugesiidae (Platyhelminthes, Tricladida)  

E-print Network

(Platyhelminthes, Tricladida) Salvador Carranza,* Jaume Bagun~a`, Marta Riutort Departament de Gene`tica, Facultat -- Platyhelminthes -- Variability -- Multigene fam- ily -- Metazoan -- Phylogeny Introduction The ribosomal DNA (rDNA polymorphism within the genome of a metazoan species, Schmidtea mediterranea, a free-living platyhelminth

Carranza, Salvador

5

Evidence that Two Types of 18s rDNA Coexist in the Genome of Dugesia (Schmidtea) mediterranea (Platyhelminthes, Turbellaria, Tricladida)  

E-print Network

(Platyhelminthes, Turbellaria, Tricladida) Salvador Carranza," Gonzalo Giribet,? Caries Ribera,? Jaume Baguii in the platyhelminth Dug&a (Schmidtea) mediterrunea (Turbellaria, Seriata, Tricladida). Southern blot analysis of phylogenetic history Key words: 18s rDNA, polymorphism, Dug&a (Schmidfea) mrditerranea, Platyhelminthes

Carranza, Salvador

6

Investigation of the ultrastructure of Dendrocoelum constrictum (Platyhelminthes, Tricladida) spermatogenesis and mature spermatozoa.  

PubMed

To add to our understanding of dendrocoelid spermatozoa and to describe additional phylogenetic characters, the ultrastructure of the testis was investigated in the subterranean freshwater planarian Dendrocoelum constrictum. This is the first study investigating spermatogenesis and spermatozoon ultrastructure in a subterranean freshwater planarian species. We found that the basic structure of spermatozoa in D. constrictum is similar to that of other Tricladida that have been studied previously. In fact, D. constrictum spermatozoa possess an elongated nucleus, one giant mitochondrion, and two subterminal flagella with a 9+'1' pattern. The flagella emerge together from one side of the spermatozoon. However, D. constrictum has some characteristics that have not yet been described for other freshwater planarians. In fact, the number of cortical microtubules reaches the maximum number in the anterior and middle part of region I, and then decrease until they disappear towards the posterior extremity of the spermatozoon. The extreme tip of the anterior region of the spermatozoon exhibits a specific external ornamentation of the plasma membrane. PMID:25242690

Harrath, Abdel Halim; Gammoudi, Mehrez; Mansour, Lamjed; Ahmed, Mukhtar; Sirotkin, Alexander V; Al Omar, Suliman Y; Ibrahim, Khalid E; Alwasel, Saleh H

2014-09-01

7

Planarian Homeobox Genes: Cloning, Sequence Analysis, and Expression  

Microsoft Academic Search

Freshwater planarians (Platyhelminthes, Turbellaria, and Tricladida) are acoelomate, triploblastic, unsegmented, and bilaterally symmetrical organisms that are mainly known for their ample power to regenerate a complete organism from a small piece of their body. To identify potential pattern-control genes in planarian regeneration, we have isolated two homeobox-containing genes, Dth-1 and Dth-2 [Dugesia (Girardia) tigrina homeobox], by using degenerate oligonucleotides corresponding

Jordi Garcia-Fernandez; Jaume Baguna; Emili Salo

1991-01-01

8

[Telomere length and phylogenetic relationship of Baikal and Siberian planarians (Turbellaria, Tricladida)].  

PubMed

Dynamics of the telomeric DNA (tDNA) and the phylogeny of the Baikal and Siberian planarians have been studied based on the analysis of the 18S rDNA and beta-actin gene fragments. A relationship between tDNA and the planarians size has been demonstrated. Giant planarians with a minor exception have longer tDNA than little planarians. Phylogenetic affinity between the species that have the stretched tracks of tDNA, big size and similar habitats may indicate possible role of tDNA in the development of the indefinite regenerative capacity of planarians. PMID:23875458

Koroleva, A G; Evtushenko, E V; Timoshkin, O A; Vershinin, A V; Kiril'chik, S V

2013-01-01

9

A new and aberrant species of Dugesia (Platyhelminthes, Tricladida, Dugesiidae) from Madagascar  

PubMed Central

Abstract In this paper we report a new species of Dugesia of the family Dugesiidae from Madagascar, representing the fourth species of freshwater planarian known from this global biodiversity hotspot. In some respects the new species is aberrant, when compared with its congeners, being characterized by a head with smoothly rounded auricles, a peculiar course of the oviducts, including the presence of a common posterior extension, and by the asymmetrical openings of the vasa deferentia at about halfway along the seminal vesicle. Further, it is characterized by a ventral course of the ejaculatory duct with a terminal opening, very long spermiducal vesicles and unstalked cocoons. Its diploid chromosome complement with 18 chromosomes represents an uncommon feature among fissiparous species of Dugesia. PMID:25147450

Stocchino, Giacinta Angela; Sluys, Ronald; Manconi, Renata

2014-01-01

10

Prey-tracking behavior in the invasive terrestrial planarian Platydemus manokwari (Platyhelminthes, Tricladida)  

NASA Astrophysics Data System (ADS)

Platydemus manokwari is a broadly distributed invasive terrestrial flatworm that preys heavily on land snails and has been credited with the demise of numerous threatened island faunas. We examined whether P. manokwari tracks the mucus trails of land snail prey, investigated its ability to determine trail direction, and evaluated prey preference among various land snail species. A plastic treatment plate with the mucus trail of a single species and a control plate without the trail were placed side by side at the exit of cages housing P. manokwari. All trials were then videotaped overnight. The flatworms moved along plates with mucus trails, but did not respond to plates without trails, blank control (distilled water), or with conspecific flatworm trails. When presented at the midpoint of a snail mucus trail, the flatworms followed the trail in a random direction. The flatworms showed a preference when choosing between two plates, each with a mucus trail of different land snail species. Our results suggest that P. manokwari follows snail mucus trails based on chemical cues to increase the chance of encountering prey; however, trail-tracking behavior showed no directionality.

Iwai, Noriko; Sugiura, Shinji; Chiba, Satoshi

2010-11-01

11

Dugesia sicula (Platyhelminthes, Tricladida): the colonizing success of an asexual Planarian  

PubMed Central

Background Dugesia sicula is the only species of its genus not presenting an endemic or restricted distribution within the Mediterranean area. It mostly comprises fissiparous populations (asexual reproduction by body division and regeneration), most likely sexually sterile, and characterized by an extremely low genetic diversity interpreted as the consequence of a recent anthropic expansion. However, its fissiparous reproduction can result in an apparent lack of diversity within the species, since genetic variation within individuals can be as large as between them because most individuals within a population are clones. We have estimated haplotype and nucleotide diversity of cytochrome oxidase I within and among individuals along the species distribution of a broad sample of D. sicula, including asexual and the two only sexual populations known today; and predicted its potential distribution based on climatic variables. Our aim was to determine the centre of colonisation origin, whether the populations are recent, and whether the species is expanding. Results The species presents 3 most frequent haplotypes, differing in a maximum of 11 base pairs. As expected from their fissiparous mode of reproduction, in half of all the analysed localities many individuals have multiple heteroplasmic haplotypes. The distribution of haplotypes is not geographically structured; however, the distribution of haplotypes and heteroplasmic populations shows higher diversity in the central Mediterranean region. The potential distribution predicted by climatic variables based modelling shows a preference for coastal areas and fits well with the observed data. Conclusions The distribution and frequency of the most frequent haplotypes and the presence of heteroplasmic individuals allow us to gain an understanding of the recent history of the species, together with previous knowledge on its phylogenetic relationships and age: The species most probably originated in Africa and dispersed through the central Mediterranean. After one or multiple populations became triploid and fissiparous, the species colonized the Mediterranean basin, likely both by its own means and helped by human activities. Its present distribution practically fulfils its potential distribution as modelled with climatic variables. Its prevalence in coastal regions with higher water temperatures predicts a likely future expansion to northern and more interior areas following the increase in temperatures due to climate change. PMID:24330464

2013-01-01

12

Quantitative cellular analysis of growth and reproduction in freshwater planarians (Turbellaria; Tricladida). I. A cellular description of the intact organism  

Microsoft Academic Search

A better understanding of the mechanisms underlying growth and degrowth in freshwater planarians, and the control systems associated with them, requires a thorough investigation at the cellular and molecular levels. As a first step towards this goal, we have measured the body volume, plan area, number of cells, percentage of different cell types and mean cell area and volume in

RAFAEL ROMERO; JAUME BAGUÑÀ

1991-01-01

13

Phylogenetic Relationships of Platyhelminthes Based on 18S Ribosomal Gene Sequences  

Microsoft Academic Search

Nucleotide sequences of 18S ribosomal RNA from 71 species of Platyhelminthes, the flatworms, were analyzed using maximum likelihood, and the resulting phylogenetic trees were compared with previous phylogenetic hypotheses. Analyses including 15 outgroup species belonging to eight other phyla show that Platyhelminthes are monophyletic with the exception of a sequence putatively from Acoela sp., Lecithoepitheliata, Polycladida, Tricladida, Trematoda (Aspidobothrii+ Digenea),

Andrés Campos; Michael P. Cummings; José Luis Reyes; Juan Pedro Laclette

1998-01-01

14

High Copy Number of Highly Similar mariner-like Transposons in Planarian ( Platyhelminthe ) : Evidence for a Trans-Phyla Horizontal Transfer  

Microsoft Academic Search

Several DNA sequences similar to the mariner element were isolated and characterized in the platyhelminthe Dugesia (Girardia) tigrina. They were 1,288 bp long, flanked by two 32 bp-inverted repeats, and contained a single 339 amino acid open-reading frame (ORF) encoding the transposase. The number of copies of this element is approximately 8,000 per haploid genome, constituting a member of the

Jordi Garcia-Ferndndez; Andreu Casali

15

The Planarian HOM\\/HOX Homeobox Genes ( Plox) Expressed along the Anteroposterior Axis  

Microsoft Academic Search

In the freshwater planarian Dugesia japonica, five cDNAs for HOM\\/HOX homeobox genes were cloned and sequenced. Together with sequence data on HOM\\/HOX homeobox genes of platyhelminthes deposited in databases, comparison of the deduced amino acid sequences revealed that planarians have at least seven HOM\\/HOX homeobox genes, Plox1 to Plox7 (planarian HOM\\/HOX homeobox genes). Whole-mount in situ hybridization and RT-PCR revealed

Hidefumi Orii; Kentaro Kato; Yoshihiko Umesono; Takashige Sakurai; Kiyokazu Agata; Kenji Watanabe

1999-01-01

16

Planarians Sense Simulated Microgravity and Hypergravity  

PubMed Central

Planarians are flatworms, which belong to the phylum Platyhelminthes. They have been a classical subject of study due to their amazing regenerative ability, which relies on the existence of adult totipotent stem cells. Nowadays they are an emerging model system in the field of developmental, regenerative, and stem cell biology. In this study we analyze the effect of a simulated microgravity and a hypergravity environment during the process of planarian regeneration and embryogenesis. We demonstrate that simulated microgravity by means of the random positioning machine (RPM) set at a speed of 60?°/s but not at 10?°/s produces the dead of planarians. Under hypergravity of 3?g and 4?g in a large diameter centrifuge (LDC) planarians can regenerate missing tissues, although a decrease in the proliferation rate is observed. Under 8?g hypergravity small planarian fragments are not able to regenerate. Moreover, we found an effect of gravity alterations in the rate of planarian scission, which is its asexual mode of reproduction. No apparent effects of altered gravity were found during the embryonic development. PMID:25309918

Adell, Teresa; Saló, Emili; van Loon, Jack J. W. A.

2014-01-01

17

Planarians sense simulated microgravity and hypergravity.  

PubMed

Planarians are flatworms, which belong to the phylum Platyhelminthes. They have been a classical subject of study due to their amazing regenerative ability, which relies on the existence of adult totipotent stem cells. Nowadays they are an emerging model system in the field of developmental, regenerative, and stem cell biology. In this study we analyze the effect of a simulated microgravity and a hypergravity environment during the process of planarian regeneration and embryogenesis. We demonstrate that simulated microgravity by means of the random positioning machine (RPM) set at a speed of 60 °/s but not at 10 °/s produces the dead of planarians. Under hypergravity of 3 g and 4 g in a large diameter centrifuge (LDC) planarians can regenerate missing tissues, although a decrease in the proliferation rate is observed. Under 8 g hypergravity small planarian fragments are not able to regenerate. Moreover, we found an effect of gravity alterations in the rate of planarian scission, which is its asexual mode of reproduction. No apparent effects of altered gravity were found during the embryonic development. PMID:25309918

Adell, Teresa; Saló, Emili; van Loon, Jack J W A; Auletta, Gennaro

2014-01-01

18

Alterations in polyamine levels of nematode, earthworm, leech and planarian during regeneration, temperature and osmotic stresses  

Microsoft Academic Search

Free-living nematodes, Caenorhabditis elegans and Dorylaimus fodori, contain putrescine and spermidine. Putrescine, spermidine and spermine occur in the parasitic Nematoda, Ascaris suum, Anisakis simplex and Dirofilaria immitis. Earthworms, Eisenia foetida, Tubifex hattai and Pheretima communissima and the leech, Hirudo nipponia (belonging to Annelida) and the planarian, Dugesia japonica (belonging to Platyhelminthes) contain homospermidine and spermine in addition to putrescine and

Koei Hamana; Hiroshi Hamana; Takao Shinozawa

1995-01-01

19

Stem Cells in Planarian  

Microsoft Academic Search

The high regenerative power of planarian has fascinated scientists for a long time. Although many famous scientists, including\\u000a Thomas Hunt Morgan, extensively devoted themselves to studying mechanisms underlying regeneration, the planarian regeneration\\u000a still remains mysterious phenomenon. Recently, modern approaches have been developed and incorporated in planarian research,\\u000a and several mysterious points were clarified. Here, I focus on old problems of

Kiyokazu Agata

20

Neurobehavioral toxicity of cadmium sulfate to the planarian Dugesia dorotocephala  

SciTech Connect

The authors are developing bioassays which use planarians (free-living platyhelminthes) for the rapid determination of various types of toxicity, including acute mortality, tumorigenicity, and short-term neurobehavioral responses. Their motivation for using these animals is due to their importance as components of the aquatic ecology of unpolluted streams their sensitivity to low concentrations of environmental toxicants and the presence of a sensitive neurological system with a true brain which allows for complex social behavior. A previous paper described the results of a neurobehavioral bioassay using phenol in a crossover study. This paper reports a similar crossover study using cadmium sulfate.

Grebe, E.; Schaeffer, D.J. (Univ. of Illinois, Urbana (United States))

1991-05-01

21

Molecular phylogeny of the Platyhelminthes  

Microsoft Academic Search

Abstract: The phylum,Platyhelminthes has traditionally been considered the most basal bilaterian taxon. The main,dif- ficulty with this placement is the lack of convincing synapomorphies for all Platyhelminthes, which suggest that they are polyphyletic. Recent molecular,findings based on 18S rDNA sequence,data and number,and type of Hox genes strongly suggest that the majority of Platyhelminthes are members of the lophotrochozoan protostomes, whereas

Jaume Baguñà; Marta Riutort

2004-01-01

22

Regulation factor for planarian regeneration  

Microsoft Academic Search

Planarian head extract was fractionated and the fractions were assayed for their effect on cultured cells and planarian regeneration. One fraction (molecular weight larger than 10 000; unadsorbable by DEAE-Sephadex, CM-Sephadex and Con A-Sepharose; and precipitable by ammonium sulfate) inhibited the growth of both Neuro 2a and PC-12 cell lines as well as planarian head- regeneration. This effect was specific

Takao Shinozawa; Syuichi Shiozaki; Masanobu Ezaki; Hideki Fujino; Takeshi Tanaka; Toshihiko Saheki

1995-01-01

23

Triploid planarian reproduces truly bisexually with euploid gametes produced through a different meiotic system between sex.  

PubMed

Although polyploids are common among plants and some animals, polyploidization often causes reproductive failure. Triploids, in particular, are characterized by the problems of chromosomal pairing and segregation during meiosis, which may cause aneuploid gametes and results in sterility. Thus, they are generally considered to reproduce only asexually. In the case of the Platyhelminthes Dugesia ryukyuensis, populations with triploid karyotypes are normally found in nature as both fissiparous and oviparous triploids. Fissiparous triploids can also be experimentally sexualized if they are fed sexual planarians, developing both gonads and other reproductive organs. Fully sexualized worms begin reproducing by copulation rather than fission. In this study, we examined the genotypes of the offspring obtained by breeding sexualized triploids and found that the offspring inherited genes from both parents, i.e., they reproduced truly bisexually. Furthermore, meiotic chromosome behavior in triploid sexualized planarians differed significantly between male and female germ lines, in that female germ line cells remained triploid until prophase I, whereas male germ line cells appeared to become diploid before entry into meiosis. Oocytes at the late diplotene stage contained not only paired bivalents but also unpaired univalents that were suggested to produce diploid eggs if they remained in subsequent processes. Triploid planarians may therefore form euploid gametes by different meiotic systems in female and male germ lines and thus are be able to reproduce sexually in contrast to many other triploid organisms. PMID:24402417

Chinone, Ayako; Nodono, Hanae; Matsumoto, Midori

2014-06-01

24

The freshwater planarian Schmidtea mediterranea: embryogenesis, stem cells and regeneration  

E-print Network

The freshwater planarian Schmidtea mediterranea: embryogenesis, stem cells and regeneration function in planarians during development and regeneration. These advances promise to shed mechanistic Commentary Alejandro Sa´ nchez Alvarado Planarians have been used as a model to study development

Alvarado, Alejandro Sánchez

25

Emerging patterns in planarian regeneration  

PubMed Central

Summary In the last decade, the planarian has become an increasingly tractable invertebrate model for the investigation of regeneration and stem cell biology. Application of a variety of techniques and development of genomic reagents in this system have enabled exploration of the molecular mechanisms by which pluripotent somatic stem cells called neoblasts replenish, repair, and regenerate planarian tissues and organs. Recent investigations have implicated evolutionarily conserved signaling pathways in the re-establishment of anterior-posterior, dorsal-ventral, and medial-lateral polarity after injury. These studies have significantly advanced our understanding of early events during planarian regeneration, and have raised new questions about the mechanisms of stem cell-based tissue repair and renewal. PMID:19574035

Forsthoefel, David J.; Newmark, Phillip A.

2010-01-01

26

Initial study on the safety test using the planarian regeneration  

Microsoft Academic Search

Freshwater planarians have remarkable regeneration ability. We did the elementary experiment which utilized the regeneration capacity of this planarian for safety evaluation of chemicals. The regeneration level of planarian measured the regeneration rate from the tail side where the reproduction of eyes was able to watch. This time, we examined the regeneration inhibition of the planarian by the ethanol. As

Sakiko Okumura; Yasuhiko Kobayashi

27

Inhibition of planarian regeneration by melatonin  

Microsoft Academic Search

Melatonin, which is a substance produced by the pineal body in vertebrates, inhibited regeneration in the planarian Dugesia japonica japonica Ichikawa et Kawakatsu. When decapitated planarians were maintained in a 1 mmol dm-3 solution of melatonin, formation of the head was retarded; formation of the eyes, however, was not disturbed. Similarly in animals from which the tail was cut, regeneration

Yasuhiro Yoshizawa; Katsumi Wakabayashi; Takao Shinozawa

1991-01-01

28

Planarian Regeneration and Stem Cells  

NSDL National Science Digital Library

A mini-documentary discussing the remarkable regenerative capabilities of the planarian, and how HHMI researcher Alejandro Snchez Alvarado uses them to study the biology of stem cells. This presentation is also featured on the DVD Potent Biology: Stem Cells, Cloning, and Regeneration, available for free from HHMI. This video is 11 minutes and 46 seconds in length, and available for download in Quicktime (114 MB) and Windows Media (156 MB) formats. All Stem Cell videos are located at: http://www.hhmi.org/biointeractive/stemcells/video.html.

Alejandro Sánchez Alvarado (Howard Hughes Medical Institute;)

2007-03-31

29

Muscle Cells Provide Instructions for Planarian Regeneration  

E-print Network

Regeneration requires both potential and instructions for tissue replacement. In planarians, pluripotent stem cells have the potential to produce all new tissue. The identities of the cells that provide regeneration ...

Witchley, Jessica N.

30

Phylogeny of the Monopisthocotylea and Polyopisthocotylea (Platyhelminthes) inferred from 28S rDNA sequencesp  

E-print Network

Phylogeny of the Monopisthocotylea and Polyopisthocotylea (Platyhelminthes) inferred from 28S r of monopisthocotyleans, 26 polyopisthocotyleans including six polystomatids, and other Platyhelminthes (61 species. Keywords: Monogenea; Monopisthocotylea; Phylogenetic analysis; Platyhelminthes; Polyopisthocotylea; 28S r

31

Dynamics of asexual reproduction in planarians  

NASA Astrophysics Data System (ADS)

Planaria research is experiencing a resurgence due to the development of molecular tools, the Planarian genome project and database resources. Despite the resulting progress in planarian biology research, an extensive study of their physical properties remains to be undertaken. We developed a method to collect a large amount of data on the dynamics of clonal reproduction in the freshwater planarian S.mediterranea. The capability of planarians to regenerate an entire organism from a minuscule body part is based on a homogeneously distributed stem cell population that comprises 25-30% of all cells. Due to this stem cell contingent, planarians can reproduce spontaneously by dividing into a larger head and a smaller tail piece, which then will rebuild the missing body parts, including a central nervous system, within about a week. Time-lapse imaging allows us to characterize the fission process in detail, revealing the stages of the process as well as capturing the nature of the rupture itself. A traction force measurement setup is being developed to allow us to quantify the forces planarians exert on the substrate during reproduction, a macroscopic analog to the Traction Force Microscopy setups used to determine local cellular forces. We are particularly interested in the molecular processes during division and the interplay between tissue mechanics and cell signaling.

Schoetz, Eva-Maria; Lincoln, Bryan; Quinodoz, Sofia

2011-03-01

32

Linked thioredoxin-glutathione systems in platyhelminths  

Microsoft Academic Search

The thioredoxin and glutathione systems play a central role in thiol-disulfide redox homeostasis in many organisms by providing electrons to essential enzymes, and defence against oxidative stress. These systems have recently been characterized in platyhelminth parasites, and the emerging biochemical scenario is the existence of linked processes with the enzyme thioredoxin glutathione reductase supplying reducing equivalents to both pathways. In

Gustavo Salinas; Murray E. Selkirk; Cora Chalar; Rick M. Maizels; Cecilia Fernández

2004-01-01

33

The evolution of protonephridia of the Platyhelminthes  

Microsoft Academic Search

Three types of flame bulbs are distinguished in the Platyhelminthes: type 1 has two cilia arising from a terminal cell and rootlets extending along the weir; type 2 has many cilia arising from a terminal cell and the proximal canal cell closely aligned with it; and type 3 has a non-terminal perikaryon forming many flame bulbs, each with many cilia

Klaus Rohde

1991-01-01

34

Allometric Scaling and Proportion Regulation in the Freshwater Planarian Schmidtea mediterranea  

E-print Network

scale and proportion regulation during regeneration, growth and degrowth in the freshwater planarian: planarian; regeneration; allometry; scale and proportion; DEG/ENaC Received 16 August 2002; Accepted 9ARTICLE Allometric Scaling and Proportion Regulation in the Freshwater Planarian Schmidtea

Alvarado, Alejandro Sánchez

35

Ribonucleic acid metabolism during planarian regeneration Isabelle MARTELLY A. LE MOIGNE  

E-print Network

Ribonucleic acid metabolism during planarian regeneration Isabelle MARTELLY A. LE MOIGNE during planarian regeneration is discussed in connection with other biochemical events which have been described during regeneration processes in planarians and other animals. Introduction. Although

Paris-Sud XI, Université de

36

Centrosome Loss in the Evolution of Planarians  

PubMed Central

The centrosome, a cytoplasmic organelle formed by cylinder-shaped centrioles surrounded by a microtubule-organizing matrix, is a hallmark of animal cells. The centrosome is conserved and essential for the development of all animal species described so far. Here, we show that, unlike the rest of animals, planarians and possibly other flatworms as well completely lack centrosomes. We found that in planarians, centrioles are only assembled in terminally differentiating ciliated cells through a so-called acentriolar pathway to trigger the assembly of cilia. This unique characteristic allowed us to identify a large set of conserved proteins required for centriole assembly in animals, as well as the centrosome signature proteins missing from the planarian genome. Our study uncovers the molecular architecture and evolution of the animal centrosome and emphasizes the plasticity of animal cell biology and development. PMID:22223737

Wong, Mei Lie; Downhour, Diane Miller; Alvarado, Alejandro Sánchez

2012-01-01

37

Muscle cells provide instructions for planarian regeneration.  

PubMed

Regeneration requires both potential and instructions for tissue replacement. In planarians, pluripotent stem cells have the potential to produce all new tissue. The identities of the cells that provide regeneration instructions are unknown. Here, we report that position control genes (PCGs) that control regeneration and tissue turnover are expressed in a subepidermal layer of nonneoblast cells. These subepidermal cells coexpress many PCGs. We propose that these subepidermal cells provide a system of body coordinates and positional information for regeneration, and identify them to be muscle cells of the planarian body wall. Almost all planarian muscle cells express PCGs, suggesting a dual function: contraction and control of patterning. PCG expression is dynamic in muscle cells after injury, even in the absence of neoblasts, suggesting that muscle is instructive for regeneration. We conclude that planarian regeneration involves two highly flexible systems: pluripotent neoblasts that can generate any new cell type and muscle cells that provide positional instructions for the regeneration of any body region. PMID:23954785

Witchley, Jessica N; Mayer, Mirjam; Wagner, Daniel E; Owen, Jared H; Reddien, Peter W

2013-08-29

38

The phylogenetic position of Udonella (Platyhelminthes) 1  

Microsoft Academic Search

Phylogenetic analysis of molecular data from complete 18S rRNA and partial 28S rRNA genes, of a variety of platyhelminths, places the enigmatic Udonella caligorum firmly as a monopisthocotylean monogenean. Both maximum parsimony and a modified distance measure, operating under a maximum likelihood model, gave identical solutions for each data set. These data further support morphological evidence from ultrastructural studies indicating

D. T. J. Littlewood; K. Rohde; K. A. Clough

1998-01-01

39

Lipid binding proteins from parasitic platyhelminthes  

PubMed Central

Two main families of lipid binding proteins have been identified in parasitic Platyhelminthes: hydrophobic ligand binding proteins (HLBPs) and fatty acid binding proteins (FABPs). Members of the former family of proteins are specific to the Cestoda class, while FABPs are conserved across a wide range of animal species. Because Platyhelminthes are unable to synthesize their own lipids, these lipid-binding proteins are important molecules in these organisms. HLBPs are a high molecular mass complex of proteins and lipids. They are composed of subunits of low molecular mass proteins and a wide array of lipid molecules ranging from CoA esters to cholesterol. These proteins are excretory-secretory molecules and are key serological tools for diagnosis of diseases caused by cestodes. FABPs are mainly intracellular proteins of low molecular weight. They are also vaccine candidates. Despite that the knowledge of their function is scarce, the differences in their molecular organization, ligand preferences, intra/extracellular localization, evolution, and phylogenetic distribution, suggest that platyhelminths HLBPs and FABPs should play different functions. FABPs might be involved in the removal of fatty acids from the inner surface of the cell membrane and in their subsequent targeting to specific cellular destinations. In contrast, HLBPs might be involved in fatty acid uptake from the host environment. PMID:22988444

Alvite, Gabriela; Esteves, Adriana

2012-01-01

40

Planarian Immobilization, Partial Irradiation, and Tissue Transplantation  

PubMed Central

The planarian, a freshwater flatworm, has proven to be a powerful system for dissecting metazoan regeneration and stem cell biology1,2. Planarian regeneration of any missing or damaged tissues is made possible by adult stem cells termed neoblasts3. Although these stem cells have been definitively shown to be pluripotent and singularly capable of reconstituting an entire animal4, the heterogeneity within the stem cell population and the dynamics of their cellular behaviors remain largely unresolved. Due to the large number and wide distribution of stem cells throughout the planarian body plan, advanced methods for manipulating subpopulations of stem cells for molecular and functional study in vivo are needed. Tissue transplantation and partial irradiation are two methods by which a subpopulation of planarian stem cells can be isolated for further study. Each technique has distinct advantages. Tissue transplantation allows for the introduction of stem cells, into a naïve host, that are either inherently genetically distinct or have been previously treated pharmacologically. Alternatively, partial irradiation allows for the isolation of stem cells within a host, juxtaposed to tissue devoid of stem cells, without the introduction of a wound or any breech in tissue integrity. Using these two methods, one can investigate the cell autonomous and non-autonomous factors that control stem cell functions, such as proliferation, differentiation, and migration. Both tissue transplantation5,6 and partial irradiation7 have been used historically in defining many of the questions about planarian regeneration that remain under study today. However, these techniques have remained underused due to the laborious and inconsistent nature of previous methods. The protocols presented here represent a large step forward in decreasing the time and effort necessary to reproducibly generate large numbers of grafted or partially irradiated animals with efficacies approaching 100 percent. We cover the culture of large animals, immobilization, preparation for partial irradiation, tissue transplantation, and the optimization of animal recovery. Furthermore, the work described here demonstrates the first application of the partial irradiation method for use with the most widely studied planarian, Schmidtea mediterranea. Additionally, efficient tissue grafting in planaria opens the door for the functional testing of subpopulations of naïve or treated stem cells in repopulation assays, which has long been the gold-standard method of assaying adult stem cell potential in mammals8. Broad adoption of these techniques will no doubt lead to a better understanding of the cellular behaviors of adult stem cells during tissue homeostasis and regeneration. PMID:23007410

Guedelhoefer IV, Otto C.; Sánchez Alvarado, Alejandro

2012-01-01

41

Planarian immobilization, partial irradiation, and tissue transplantation.  

PubMed

The planarian, a freshwater flatworm, has proven to be a powerful system for dissecting metazoan regeneration and stem cell biology. Planarian regeneration of any missing or damaged tissues is made possible by adult stem cells termed neoblasts. Although these stem cells have been definitively shown to be pluripotent and singularly capable of reconstituting an entire animal, the heterogeneity within the stem cell population and the dynamics of their cellular behaviors remain largely unresolved. Due to the large number and wide distribution of stem cells throughout the planarian body plan, advanced methods for manipulating subpopulations of stem cells for molecular and functional study in vivo are needed. Tissue transplantation and partial irradiation are two methods by which a subpopulation of planarian stem cells can be isolated for further study. Each technique has distinct advantages. Tissue transplantation allows for the introduction of stem cells, into a naïve host, that are either inherently genetically distinct or have been previously treated pharmacologically. Alternatively, partial irradiation allows for the isolation of stem cells within a host, juxtaposed to tissue devoid of stem cells, without the introduction of a wound or any breech in tissue integrity. Using these two methods, one can investigate the cell autonomous and non-autonomous factors that control stem cell functions, such as proliferation, differentiation, and migration. Both tissue transplantation and partial irradiation have been used historically in defining many of the questions about planarian regeneration that remain under study today. However, these techniques have remained underused due to the laborious and inconsistent nature of previous methods. The protocols presented here represent a large step forward in decreasing the time and effort necessary to reproducibly generate large numbers of grafted or partially irradiated animals with efficacies approaching 100 percent. We cover the culture of large animals, immobilization, preparation for partial irradiation, tissue transplantation, and the optimization of animal recovery. Furthermore, the work described here demonstrates the first application of the partial irradiation method for use with the most widely studied planarian, Schmidtea mediterranea. Additionally, efficient tissue grafting in planaria opens the door for the functional testing of subpopulations of naïve or treated stem cells in repopulation assays, which has long been the gold-standard method of assaying adult stem cell potential in mammals. Broad adoption of these techniques will no doubt lead to a better understanding of the cellular behaviors of adult stem cells during tissue homeostasis and regeneration. PMID:23007410

Guedelhoefer, Otto C; Sánchez Alvarado, Alejandro

2012-01-01

42

Bromodeoxyuridine Specifically Labels the Regenerative Stem Cells of Planarians  

Microsoft Academic Search

The singular regenerative abilities of planarians require a population of stem cells known as neoblasts. In response to wounding, or during the course of cell turnover, neoblasts are signaled to divide and\\/or differentiate, thereby replacing lost cell types. The study of these pluripotent stem cells and their role in planarian regeneration has been severely hampered by the reported inability of

Phillip A. Newmark; Alejandro Sánchez Alvarado

2000-01-01

43

Planarian Phototactic Assay Reveals Differential Behavioral Responses Based on Wavelength  

PubMed Central

Planarians are free-living aquatic flatworms that possess a well-documented photophobic response to light. With a true central nervous system and simple cerebral eyes (ocelli), planarians are an emerging model for regenerative eye research. However, comparatively little is known about the physiology of their photoreception or how their behavior is affected by various wavelengths. Most phototactic studies have examined planarian behavior using white light. Here, we describe a novel planarian behavioral assay to test responses to small ranges of visible wavelengths (red, blue, green), as well as ultraviolet (UV) and infrared (IR) which have not previously been examined. Our data show that planarians display behavioral responses across a range of wavelengths. These responses occur in a hierarchy, with the shortest wavelengths (UV) causing the most intense photophobic responses while longer wavelengths produce no effect (red) or an apparent attraction (IR). In addition, our data reveals that planarian photophobia is comprised of both a general photophobic response (that drives planarians to escape the light source regardless of wavelength) and wavelength-specific responses that encompass specific behavioral reactions to individual wavelengths. Our results serve to improve the understanding of planarian phototaxis and suggest that behavioral studies performed with white light mask a complex behavioral interaction with the environment. PMID:25493551

Paskin, Taylor R.; Jellies, John; Bacher, Jessica; Beane, Wendy S.

2014-01-01

44

The Process of Pharynx Regeneration in Planarians  

Microsoft Academic Search

To understand the cellular events during planarian regeneration, we analyzed the process of pharynx regeneration in both head and tail pieces using cell-type-specific markers. Interestingly, cells expressing the pharynx-muscle-specific myosin heavy chain gene (DjMHC-A) appeared within 24 h after amputation (prior to the formation of a pharynx rudiment) in the mesenchymal space of the stump, not in the blastema region.

Chiyoko Kobayashi; Kenji Watanabe; Kiyokazu Agata

1999-01-01

45

Recent identification of an ERK signal gradient governing planarian regeneration.  

PubMed

Planarians have strong regenerative abilities derived from their adult pluripotent stem cell (neoblast) system. However, the molecular mechanisms involved in planarian regeneration have long remained a mystery. In particular, no anterior-specifying factor(s) could be found, although Wnt family proteins had been successfully identified as posterior-specifying factors during planarian regeneration (Gurley et al., 2008; Petersen and Reddien, 2008). A recent textbook of developmental biology therefore proposes a Wnt antagonist as a putative anterior factor (Gilbert, 2013). That is, planarian regeneration was supposed to be explained by a single decreasing gradient of the ?-catenin signal from tail to head. However, recently we succeeded in demonstrating that in fact the extracellular-signal regulated kinases (ERK) form a decreasing gradient from head to tail to direct the reorganization of planarian body regionality after amputation (Umesono et al., 2013). PMID:24854393

Agata, Kiyokazu; Tasaki, Junichi; Nakajima, Elizabeth; Umesono, Yoshihiko

2014-06-01

46

On-chip immobilization of planarians for in vivo imaging  

PubMed Central

Planarians are an important model organism for regeneration and stem cell research. A complete understanding of stem cell and regeneration dynamics in these animals requires time-lapse imaging in vivo, which has been difficult to achieve due to a lack of tissue-specific markers and the strong negative phototaxis of planarians. We have developed the Planarian Immobilization Chip (PIC) for rapid, stable immobilization of planarians for in vivo imaging without injury or biochemical alteration. The chip is easy and inexpensive to fabricate, and worms can be mounted for and removed after imaging within minutes. We show that the PIC enables significantly higher-stability immobilization than can be achieved with standard techniques, allowing for imaging of planarians at sub-cellular resolution in vivo using brightfield and fluorescence microscopy. We validate the performance of the PIC by performing time-lapse imaging of planarian wound closure and sequential imaging over days of head regeneration. We further show that the device can be used to immobilize Hydra, another photophobic regenerative model organism. The simple fabrication, low cost, ease of use, and enhanced specimen stability of the PIC should enable its broad application to in vivo studies of stem cell and regeneration dynamics in planarians and Hydra. PMID:25227263

Dexter, Joseph P.; Tamme, Mary B.; Lind, Christine H.; Collins, Eva-Maria S.

2014-01-01

47

On-chip immobilization of planarians for in vivo imaging.  

PubMed

Planarians are an important model organism for regeneration and stem cell research. A complete understanding of stem cell and regeneration dynamics in these animals requires time-lapse imaging in vivo, which has been difficult to achieve due to a lack of tissue-specific markers and the strong negative phototaxis of planarians. We have developed the Planarian Immobilization Chip (PIC) for rapid, stable immobilization of planarians for in vivo imaging without injury or biochemical alteration. The chip is easy and inexpensive to fabricate, and worms can be mounted for and removed after imaging within minutes. We show that the PIC enables significantly higher-stability immobilization than can be achieved with standard techniques, allowing for imaging of planarians at sub-cellular resolution in vivo using brightfield and fluorescence microscopy. We validate the performance of the PIC by performing time-lapse imaging of planarian wound closure and sequential imaging over days of head regeneration. We further show that the device can be used to immobilize Hydra, another photophobic regenerative model organism. The simple fabrication, low cost, ease of use, and enhanced specimen stability of the PIC should enable its broad application to in vivo studies of stem cell and regeneration dynamics in planarians and Hydra. PMID:25227263

Dexter, Joseph P; Tamme, Mary B; Lind, Christine H; Collins, Eva-Maria S

2014-01-01

48

Are the Platyhelminthes a Monophyletic Primitive Group? An Assessment Using 18s rDNA Sequences  

E-print Network

Are the Platyhelminthes a Monophyletic Primitive Group? An Assessment Using 18s rDNA Sequences. Universitat de Barcelona, Spain In most zoological textbooks, Platyhelminthes are depicted as an early "Turbellaria," 3 species of parasitic Platyhelminthes, and several diploblastic and deuterostome and protostome

Carranza, Salvador

49

The distribution of New Zealand and Australian terrestrial flatworms (Platyhelminthes: Turbellaria: Tricladida: Terricola) in the British Isles—the Scottish survey and MEGALAB WORMS  

Microsoft Academic Search

The New Zealand flatworm, Artioposthia triangulata, and the Australian flatworm, Caenoplana alba, have become quite widespread in the British Isles since their introduction, probably in the early 1960s. They are considered as pest species since they eat earthworms and consequently may affect soil structure and fertility. The distribution of the two species has been recorded by two surveys: a Scottish

H. D. Jones; B. Boag

1996-01-01

50

Berberine exposure triggers developmental effects on planarian regeneration  

PubMed Central

The mechanisms of action underlying the pharmacological properties of the natural alkaloid berberine still need investigation. Planarian regeneration is instrumental in deciphering developmental responses following drug exposure. Here we report the effects of berberine on regeneration in the planarian Dugesia japonica. Our findings demonstrate that this compound perturbs the regenerative pattern. By real-time PCR screening for the effects of berberine exposure on gene expression, we identified alterations in the transcriptional profile of genes representative of different tissues, as well as of genes involved in extracellular matrix (ECM) remodeling. Although berberine does not influence cell proliferation/apoptosis, our experiments prove that this compound causes abnormal regeneration of the planarian visual system. Potential berberine-induced cytotoxic effects were noticed in the intestine. Although we were unable to detect abnormalities in other structures, our findings, sustained by RNAi-based investigations, support the possibility that berberine effects are critically linked to anomalous ECM remodeling in treated planarians. PMID:24810466

Balestrini, Linda; Isolani, Maria Emilia; Pietra, Daniele; Borghini, Alice; Bianucci, Anna Maria; Deri, Paolo; Batistoni, Renata

2014-01-01

51

Berberine exposure triggers developmental effects on planarian regeneration.  

PubMed

The mechanisms of action underlying the pharmacological properties of the natural alkaloid berberine still need investigation. Planarian regeneration is instrumental in deciphering developmental responses following drug exposure. Here we report the effects of berberine on regeneration in the planarian Dugesia japonica. Our findings demonstrate that this compound perturbs the regenerative pattern. By real-time PCR screening for the effects of berberine exposure on gene expression, we identified alterations in the transcriptional profile of genes representative of different tissues, as well as of genes involved in extracellular matrix (ECM) remodeling. Although berberine does not influence cell proliferation/apoptosis, our experiments prove that this compound causes abnormal regeneration of the planarian visual system. Potential berberine-induced cytotoxic effects were noticed in the intestine. Although we were unable to detect abnormalities in other structures, our findings, sustained by RNAi-based investigations, support the possibility that berberine effects are critically linked to anomalous ECM remodeling in treated planarians. PMID:24810466

Balestrini, Linda; Isolani, Maria Emilia; Pietra, Daniele; Borghini, Alice; Bianucci, Anna Maria; Deri, Paolo; Batistoni, Renata

2014-01-01

52

Regeneration and maintenance of the planarian nervous system  

E-print Network

Planarians can regenerate all tissues, including the central nervous system and the eyes. This process depends on a population of cells in the adult, the neoblasts, that includes pluripotent stem cells. Whether the neoblast ...

Lapan, Sylvain William

2012-01-01

53

The Retinoblastoma pathway regulates stem cell proliferation in freshwater planarians.  

PubMed

Freshwater planarians are flatworms of the Lophotrochozoan superphylum and are well known for their regenerative abilities, which rely on a large population of pluripotent adult stem cells. However, the mechanisms by which planarians maintain a precise population of adult stem cells while balancing proliferation and cell death, remain to be elucidated. Here we have identified, characterized, and functionally tested the core Retinoblastoma (Rb) pathway components in planarian adult stem cell biology. The Rb pathway is an ancient and conserved mechanism of proliferation control from plants to animals and is composed of three core components: an Rb protein, and a transcription factor heterodimer of E2F and DP proteins. Although the planarian genome contains all components of the Rb pathway, we found that they have undergone gene loss from the ancestral state, similar to other species in their phylum. The single Rb homolog (Smed-Rb) was highly expressed in planarian stem cells and was required for stem cell maintenance, similar to the Rb-homologs p107 and p130 in vertebrates. We show that planarians and their phylum have undergone the most severe reduction in E2F genes observed thus far, and the single remaining E2F was predicted to be a repressive-type E2F (Smed-E2F4-1). Knockdown of either Smed-E2F4-1 or its dimerization partner Dp (Smed-Dp) by RNAi resulted in temporary hyper-proliferation. Finally, we showed that known Rb-interacting genes in other systems, histone deacetylase 1 and cyclinD (Smed-HDAC1; Smed-cycD), were similar to Rb in expression and phenotypes when knocked down by RNAi, suggesting that these established interactions with Rb may also be conserved in planarians. Together, these results showed that planarians use the conserved components of the Rb tumor suppressor pathway to control proliferation and cell survival. PMID:23123964

Zhu, Shu Jun; Pearson, Bret J

2013-01-15

54

Expression analysis of Djsix-1 gene during regeneration of planarian eyespots  

Microsoft Academic Search

Djsix-1 gene is one of the important eyespots-regulating genes in planarians. In this experiment, the expression of Djsix-1 and morphogenesis of eyespots during planarians eyespots regeneration were investigated. The planarians were subjected to\\u000a two rounds of transverse amputation. Nineteen time points in the first round and ten ones in the second one during the regeneration\\u000a of the planarians post-auricle fragments

Zimei Dong; Yanqing Yuwen; Qinghua Wang; Guangwen Chen; Dezeng Liu

2011-01-01

55

Not your father's planarian: a classic model enters the era of functional genomics  

Microsoft Academic Search

Freshwater planarians were a classic model for studying the problems of development and regeneration. However, as attention shifted towards animals with more rigid developmental processes, the planarians, with their notoriously plastic ontogeny, declined in significance as a model system. This trend was exacerbated with the introduction of genetic and molecular approaches, which did not work well in planarians. More recently,

Alejandro Sánchez Alvarado; Phillip A. Newmark

2002-01-01

56

Characterization of innexin gene expression and functional roles of gap-junctional communication in planarian regeneration  

E-print Network

in planarian regeneration Taisaku Nogi, Michael Levin * Department of Cytokine Biology, The Forsyth Institute family during planarian regeneration. Planarian innexins fall into 3 groups according to both sequence remarkable powers of regeneration. After bisection, one blastema regenerates a head, while the other forms

Levin, Michael

57

The use of planarians to dissect the molecular basis of metazoan regeneration  

E-print Network

The use of planarians to dissect the molecular basis of metazoan regeneration ALEJANDRO-derived regeneration . Ultimately, the genes identified in planarians and their interactions during regeneration SANCHEZALVARADO, PhD, PHILLIP A. NEWMARK, PhD Freshwater planarians possess remarkable regenerative abilities

Alvarado, Alejandro Sánchez

58

Expression and functional analysis of musashi-like genes in planarian CNS regeneration  

Microsoft Academic Search

The remarkable regenerative ability of planarians is made possible by a system of pluripotent stem cells. Recent molecular biological and ultrastructural studies have revealed that planarian stem cells consist of heterogeneous populations, which can be classified into several subsets according to their differential expression of RNA binding protein genes. In this study, we focused on planarian musashi family genes. Musashi

Sayaka Higuchi; Tetsutaro Hayashi; Hiroshi Tarui; Osamu Nishimura; Kaneyasu Nishimura; Norito Shibata; Hiroshi Sakamoto; Kiyokazu Agata

2008-01-01

59

Djeyes absent ( Djeya) controls prototypic planarian eye regeneration by cooperating with the transcription factor Djsix-1  

Microsoft Academic Search

A conserved network of nuclear proteins is crucial to eye formation in both vertebrates and invertebrates. The finding that freshwater planarians can regenerate eyes without the contribution of Pax6 suggests that alternative combinations of regulatory elements may control the morphogenesis of the prototypic planarian eye. To further dissect the molecular events controlling eye regeneration in planarians, we investigated the role

Linda Mannini; Leonardo Rossi; Paolo Deri; Vittorio Gremigni; Alessandra Salvetti; Emili Saló; Renata Batistoni

2004-01-01

60

Reactivating head regrowth in a regeneration-deficient planarian species.  

PubMed

Species capable of regenerating lost body parts occur throughout the animal kingdom, yet close relatives are often regeneration incompetent. Why in the face of 'survival of the fittest' some animals regenerate but others do not remains a fascinating question. Planarian flatworms are well known and studied for their ability to regenerate from minute tissue pieces, yet species with limited regeneration abilities have been described even amongst planarians. Here we report the characterization of the regeneration defect in the planarian Dendrocoelum lacteum and its successful rescue. Tissue fragments cut from the posterior half of the body of this species are unable to regenerate a head and ultimately die. We find that this defect originates during the early stages of head specification, which require inhibition of canonical Wnt signalling in other planarian species. Notably, RNA interference (RNAi)-mediated knockdown of Dlac-?-catenin-1, the Wnt signal transducer, restored the regeneration of fully functional heads on tail pieces, rescuing D. lacteum's regeneration defect. Our results demonstrate the utility of comparative studies towards the reactivation of regenerative abilities in regeneration-deficient animals. Furthermore, the availability of D. lacteum as a regeneration-impaired planarian model species provides a first step towards elucidating the evolutionary mechanisms that ultimately determine why some animals regenerate and others do not. PMID:23883932

Liu, S-Y; Selck, C; Friedrich, B; Lutz, R; Vila-Farré, M; Dahl, A; Brandl, H; Lakshmanaperumal, N; Henry, I; Rink, J C

2013-08-01

61

Optical coherence tomography: a new strategy to image planarian regeneration.  

PubMed

The planarian is widely used as a model for studying tissue regeneration. In this study, we used optical coherence tomography (OCT) for the real-time, high-resolution imaging of planarian tissue regeneration. Five planaria were sliced transversely to produce 5 head and 5 tail fragments. During a 2-week regeneration period, OCT images of the planaria were acquired to analyze the signal attenuation rates, intensity ratios, and image texture features (including contrast, correlation, homogeneity, energy, and entropy) to compare the primitive and regenerated tissues. In the head and tail fragments, the signal attenuation rates of the regenerated fragments decreased from -0.2?dB/?m to -0.05?dB/?m, between Day 1 and Day 6, and then increased to -0.2?dB/?m on Day 14. The intensity ratios decreased to approximately 0.8 on Day 6, and increased to between 0.8 and 0.9 on Day 14. The texture parameters of contrast, correlation, and homogeneity exhibited trends similar to the signal attenuation rates and intensity ratios during the planarian regeneration. The proposed OCT parameters might provide biological information regarding cell apoptosis and the formation of a mass of new cells during planarian regeneration. Therefore, OCT imaging is a potentially effective method for planarian studies. PMID:25204535

Lin, Yu-Sheng; Chu, Chin-Chou; Lin, Jen-Jen; Chang, Chien-Cheng; Wang, Chun-Chieh; Wang, Chiao-Yin; Tsui, Po-Hsiang

2014-01-01

62

Optical coherence tomography: A new strategy to image planarian regeneration  

PubMed Central

The planarian is widely used as a model for studying tissue regeneration. In this study, we used optical coherence tomography (OCT) for the real-time, high-resolution imaging of planarian tissue regeneration. Five planaria were sliced transversely to produce 5 head and 5 tail fragments. During a 2-week regeneration period, OCT images of the planaria were acquired to analyze the signal attenuation rates, intensity ratios, and image texture features (including contrast, correlation, homogeneity, energy, and entropy) to compare the primitive and regenerated tissues. In the head and tail fragments, the signal attenuation rates of the regenerated fragments decreased from ?0.2?dB/?m to ?0.05?dB/?m, between Day 1 and Day 6, and then increased to ?0.2?dB/?m on Day 14. The intensity ratios decreased to approximately 0.8 on Day 6, and increased to between 0.8 and 0.9 on Day 14. The texture parameters of contrast, correlation, and homogeneity exhibited trends similar to the signal attenuation rates and intensity ratios during the planarian regeneration. The proposed OCT parameters might provide biological information regarding cell apoptosis and the formation of a mass of new cells during planarian regeneration. Therefore, OCT imaging is a potentially effective method for planarian studies. PMID:25204535

Lin, Yu-Sheng; Chu, Chin-Chou; Lin, Jen-Jen; Chang, Chien-Cheng; Wang, Chun-Chieh; Wang, Chiao-Yin; Tsui, Po-Hsiang

2014-01-01

63

Pharmacological assessment of methamphetamine-induced behavioral hyperactivity mediated by dopaminergic transmission in planarian Dugesia japonica.  

PubMed

The freshwater planarian Dugesia japonica has a simple central nervous system (CNS) and can regenerate complete organs, even a functional brain. Recent studies demonstrated that there is a great variety of neuronal-related genes, specifically expressed in several domains of the planarian brain. We identified a planarian dat gene, named it D. japonica dopamine transporter (Djdat), and analyzed its expression and function. Both in situ hybridization and immunofluorescence revealed that localization of Djdat mRNA and protein was the same as that of D. japonica tyrosine hydroxylase (DjTH). Although, dopamine (DA) content in Djdat(RNAi) planarians was not altered, Djdat(RNAi) planarians showed increased spontaneous locomotion. The hyperactivity in the Djdat(RNAi) planarians was significantly suppressed by SCH23390 or sulpiride pretreatment, which are D1 or D2 receptor antagonists, respectively. These results suggest that planarians have a Djdat ortholog and the ability to regulate dopaminergic neurotransmission and association with spontaneous locomotion. PMID:24858686

Tashiro, Natsuka; Nishimura, Kaneyasu; Daido, Kanako; Oka, Tomoe; Todo, Mio; Toshikawa, Asami; Tsushima, Jun; Takata, Kazuyuki; Ashihara, Eishi; Yoshimoto, Kanji; Agata, Kiyokazu; Kitamura, Yoshihisa

2014-07-11

64

Effects of 17?-estradiol and bisphenol A on the formation of reproductive organs in planarians.  

PubMed

Planarians have a remarkable capacity for regeneration after ablation, and they reproduce asexually by fission. However, some planarians can also reproduce and maintain their sexual organs. During the regenerative process, their existing sexual organs degenerate and new ones develop. However, little is known about hormonal regulation during the development of reproductive organs in planarians. In this study, we investigated the effects of 17?-estradiol (a steroid) and bisphenol A (an endocrine disrupter) on the formation of sexual organs in the hermaphroditic planarian Dugesia ryukyuensis. Under control conditions, all worm tissues regenerated into sexual planarians with sexual organs within 4 weeks after ablation. However, in the presence of bisphenol A or 17?-estradiol, although they apparently regenerated into sexual planarians, the yolk glands, which are one of the female sexual organs, failed to regenerate even 7 weeks after ablation. These data suggest that planarians have a steroid hormone system, which plays a key role in the formation and maturation of sexual organs. PMID:21385957

Miyashita, Hitoshi; Nakagawa, Haruka; Kobayashi, Kazuya; Hoshi, Motonori; Matsumoto, Midori

2011-02-01

65

The phylogenetic significance of sperm morphology in the Platyhelminthes  

Microsoft Academic Search

The phylogenetic significance of flatworm sperm morphology is discussed against the background of general spermatology. The modified type of spermatozoon of the Nemertodermatida, a group of primitive flatworms, indicates that the Platyhelminthes evolved from forms characterized by the primitive type of metazoan sperm and by the primitive mode of fertilization, implying the release of sperm freely into sea water.

Jan Hendelberg

1986-01-01

66

Interrelationships and Evolution of the Tapeworms (Platyhelminthes: Cestoda)  

Microsoft Academic Search

Interrelationships of the tapeworms (Platyhelminthes: Cestoda) were examined by use of small (SSU) and large (LSU) subunit ribosomal DNA sequences and morphological characters. Fifty new complete SSU sequences were added to 21 sequences previously determined, and 71 new LSU (D1–D3) sequences were determined for the complementary set of taxa representing each of the major lineages of cestodes as currently understood.

Peter D. Olson; D. Timothy J. Littlewood; Rodney A. Bray; Jean Mariaux

2001-01-01

67

Planarian regeneration under micro- and hyper-gravity simulated contexts  

NASA Astrophysics Data System (ADS)

Planarians are non-parasitic flatworms of the Turbellaria class, some of which show the striking ability to regenerate any part of their body, even the head, in few days. Planarians are common to many parts of the world, living in both saltwater and freshwater, as well as in terrestrial areas. Due to their plasticity Planarians have been a classical model for the study of the mechanisms of regeneration. Currently, their cheap and easy maintenance, as well as the establishment of robust genetic tools, have converted them into an essential system in the field of stem cells and regenerative medicine. The aim of our project is to study the effect that micro- and hyper- gravity could exert during the process of planarians regeneration. The reason for planarians extreme regenerative capability is the maintenance until adulthood of a population of totipotent stem cells as well as the continuous activation of the cell-cell communication molecular pathways. Our prediction is that the alteration of the forces could affect planarians regeneration at different levels: 1) To regenerate, planarians must activate both proliferative and apoptotic responses, in order to create new tissue and to remodel the pre-existing one, respectively. Both cellular processes have been reported to be altered in several models under differential gravitational forces; 2) In planarians, the main intercellular signalling pathways (Wnt, TGFb, BMP, Hh, EGF) must control the process of differentiation and determination of each cell. For instances, it has been demonstrated that the differential activity of the wnt/beta-catenin pathway specifies the posterior (tail) versus the anterior (head) identity. Those pathways rely on the distance that secreted molecules (morphogens) are able to reach. Either this mechanism consist in a passive diffusion or an active transport through phyllopodia, it could sense the magnitude of the gravitational force; 3) The epidermis of planarians is covered by cilia, which beat collectively and in synchrony to propel the mucus and allow the locomotion. The assembly of ciliary structures could be affected by gravity changes. Our strategy consists in the histological, immunological and transcriptomic analysis of planarians that have completely regenerated head and tail structures under different gravity conditions: earth gravity (1g), micro-gravity (in the random positioning machine) and hyper-gravity (in a large diameter centrifuge, at 4g and 8g). Our data shows that planarians regenerate properly head and tail structures, including the eyes and the brain, in all those conditions. However some differences between the groups could be detected: 1) a slight decrease in the number of mitotic cells is observed in hyper-gravity conditions with respect to normal and micro- gravity conditions; 2) an increase in the number of animals that fissioned the tail, which is a mechanism to reproduce asexually for planarians, was observed in hyper-gravity conditions with respect to the rest; 3) although trunk fragments regenerate head and tail properly, smaller fragments, that is, head or tail pieces, could not regenerate the missing tissues under 8g conditions, and they died. Under 4g conditions they could regenerate but not properly; 4) defects in the density and length of the cilia were observed under micro- and hyper- gravity. A transcriptomic analysis is being conducted with samples from all the groups, with the aim to detect gene categories differentially regulated under micro- and hyper- gravity contexts.

Auletta, Gennaro; Van Loon, ing.. Jack J. W. A.; Adell, Teresa; Salo, Emili

68

The head-regeneration transcriptome of the planarian Schmidtea mediterranea  

PubMed Central

Background Planarian flatworms can regenerate their head, including a functional brain, within less than a week. Despite the enormous potential of these animals for medical research and regenerative medicine, the mechanisms of regeneration and the molecules involved remain largely unknown. Results To identify genes that are differentially expressed during early stages of planarian head regeneration, we generated a de novo transcriptome assembly from more than 300 million paired-end reads from planarian fragments regenerating the head at 16 different time points. The assembly yielded 26,018 putative transcripts, including very long transcripts spanning multiple genomic supercontigs, and thousands of isoforms. Using short-read data from two platforms, we analyzed dynamic gene regulation during the first three days of head regeneration. We identified at least five different temporal synexpression classes, including genes specifically induced within a few hours after injury. Furthermore, we characterized the role of a conserved Runx transcription factor, smed-runt-like1. RNA interference (RNAi) knockdown and immunofluorescence analysis of the regenerating visual system indicated that smed-runt-like1 encodes a transcriptional regulator of eye morphology and photoreceptor patterning. Conclusions Transcriptome sequencing of short reads allowed for the simultaneous de novo assembly and differential expression analysis of transcripts, demonstrating highly dynamic regulation during head regeneration in planarians. PMID:21846378

2011-01-01

69

Bromodeoxyuridine Specifically Labels the Regenerative Stem Cells of Planarians  

E-print Network

of these pluripotent stem cells and their role in planarian regeneration has been severely hampered by the reported as an experimental model for studying the problems of metazoan regeneration and the control of stem cell proliferation. © 2000 Academic Press Key Words: planaria; regeneration; stem cells; neoblasts; flatworms

Alvarado, Alejandro Sánchez

70

Genetic regulation of planarian head morphogenesis during regeneration  

Microsoft Academic Search

Planarians possess amazing powers of regeneration and can rebuild any lost body part. The regenerative process, based on stem cells (neoblasts), is mediated by the formation of a blastema. During head regeneration, a complete functional brain, as well as the cephalic sensory structures, including eyes, are rebuilt. Recently, the characterization of a number of neural genes has revealed the complexity

Renata Batistoni; Linda Mannini; Alessandra Salvetti; Leonardo Rossi; Vittorio Gremigni; Paolo Deri

2006-01-01

71

A regulatory program for excretory system regeneration in planarians  

PubMed Central

Planarians can regenerate any missing body part, requiring mechanisms for the production of organ systems in the adult, including their prominent tubule-based filtration excretory system called protonephridia. Here, we identify a set of genes, Six1/2-2, POU2/3, hunchback, Eya and Sall, that encode transcription regulatory proteins that are required for planarian protonephridia regeneration. During regeneration, planarian stem cells are induced to form a cell population in regeneration blastemas expressing Six1/2-2, POU2/3, Eya, Sall and Osr that is required for excretory system formation. POU2/3 and Six1/2-2 are essential for these precursor cells to form. Eya, Six1/2-2, Sall, Osr and POU2/3-related genes are required for vertebrate kidney development. We determined that planarian and vertebrate excretory cells express homologous proteins involved in reabsorption and waste modification. Furthermore, we identified novel nephridia genes. Our results identify a transcriptional program and cellular mechanisms for the regeneration of an excretory organ and suggest that metazoan excretory systems are regulated by genetic programs that share a common evolutionary origin. PMID:21937596

Scimone, M. Lucila; Srivastava, Mansi; Bell, George W.; Reddien, Peter W.

2011-01-01

72

Aspects of the phylogeny of Platyhelminthes based on 18S ribosomal DNA and protonephridial ultrastructure  

Microsoft Academic Search

DNA studies of 23 taxa (20 platyhelminths, 1 nemertean, Homo and Artemia) and electron-microscopic studies of the protonephridia of many platyhelminths (supported by some additional ultrastructural data) have led to the following conclusions: the Neodermata are monophyletic; Temnocephalida and Dalyelliida form one clade and are not the ‘primitive’ sister group of the Neodermata; Gyrocotylidea, Amphilinidea and Eucestoda form one monophylum;

K. Rohde; A. M. Johnson; P. R. Baverstock; N. A. Watson

1995-01-01

73

Ingestion of bacterially expressed double-stranded RNA inhibits gene expression in planarians  

Microsoft Academic Search

population that is present in the adult planarian. The study of these organisms, classic experimental models for investigating metazoan regeneration, has been revitalized by the application of modern molecular biological approaches. The identification of thousands of unique planarian ESTs, coupled with large-scale whole-mount in situ hybridization screens, and the ability to inhibit planarian gene expression through double-stranded RNA-mediated genetic inter-

Phillip A. Newmark; Peter W. Reddien; Francesc Cebria; Alejandro Sanchez Alvarado

2003-01-01

74

Genome-Wide Analyses Reveal a Role for Peptide Hormones in Planarian Germline Development  

Microsoft Academic Search

Genomic\\/peptidomic analyses of the planarian Schmidtea mediterranea identifies >200 neuropeptides and uncovers a conserved neuropeptide required for proper maturation and maintenance of the reproductive system.

James J. Collins; Xiaowen Hou; Elena V. Romanova; Bramwell G. Lambrus; Claire M. Miller; Amir Saberi; Jonathan V. Sweedler; Phillip A. Newmark

2010-01-01

75

A Dual Platform Approach to Transcript Discovery for the Planarian Schmidtea Mediterranea to Establish RNAseq for Stem Cell and Regeneration Biology  

Microsoft Academic Search

The use of planarians as a model system is expanding and the mechanisms that control planarian regeneration are being elucidated. The planarian Schmidtea mediterranea in particular has become a species of choice. Currently the planarian research community has access to this whole genome sequencing project and over 70,000 expressed sequence tags. However, the establishment of massively parallel sequencing technologies has

Martin J. Blythe; Damian Kao; Sunir Malla; Joanna Rowsell; Ray Wilson; Deborah Evans; Jamie Jowett; Amy Hall; Virginie Lemay; Sabrina Lam; A. Aziz Aboobaker; Johannes Jaeger

2010-01-01

76

Ingestion of bacterially expressed double-stranded RNA inhibits gene expression in planarians  

E-print Network

for studying the molecular mechanisms that regulate tissue regeneration and stem cell biol- ogy of new tissue during planarian regeneration (2, 5). These stem cells can be specifically labeled of regeneration and stem cell regulation in planarians, a collection of 3,000 unique ESTs has been generated from

Gibson, Matt

77

Protein phosphorylation and the role of Ca2+ in planarian turbellarian regeneration  

Microsoft Academic Search

During planarian regeneration, relationships in timing were established between variations of calcium and calmodulin contents on one hand, and protein phosphorylation and stimulation of DNA and RNA synthesis on the other. Special attention was paid to changes in histone phosphorylation in regenerating fragments. Using in vitro experiments on dissociated planarian cells, we demonstrated causal relationships between these events. In particular,

J. Moraczewski; I. Martelly; R. Franquinet

1986-01-01

78

beta-Catenin Defines Head Versus Tail Identity During Planarian Regeneration and Homeostasis  

Microsoft Academic Search

After amputation, freshwater planarians properly regenerate a head or tail from the resulting anterior or posterior wound. The mechanisms that differentiate anterior from posterior and direct the replacement of the appropriate missing body parts are unknown. We found that in the planarian Schmidtea mediterranea, RNA interference (RNAi) of beta-catenin or dishevelled causes the inappropriate regeneration of a head instead of

Kyle A. Gurley; Jochen C. Rink; Alejandro Sánchez Alvarado

2008-01-01

79

FGFR-related gene nou-darake restricts brain tissues to the head region of planarians  

Microsoft Academic Search

The study of planarian regeneration may help us to understand how we can rebuild organs and tissues after injury, disease or ageing. The robust regenerative abilities of planarians are based upon a population of totipotent stem cells (neoblasts), and among the organs regenerated by these animals is a well-organized central nervous system. In recent years, methodologies such as whole-mount in

Francesc Cebrià; Chiyoko Kobayashi; Yoshihiko Umesono; Masumi Nakazawa; Katsuhiko Mineta; Kazuho Ikeo; Takashi Gojobori; Mari Itoh; Masanori Taira; Alejandro Sánchez Alvarado; Kiyokazu Agata

2002-01-01

80

Cytophotometric evidence for cell ‘transdifferentiation’ in planarian regeneration  

Microsoft Academic Search

The role and fate of male germ cells in planarian regeneration was studied in a population ofDugesia lugubris s.1. which provided a suitable karyological marker to distinguish diploid male germ cells from triploid embryonic and somatic cells. The nuclear Feulgen-DNA content in non-replicating triploid muscle cells of the pharynx and in non-replicating male gonia of testes from intact animals were

Vittorio Gremigni; Cristina Miceli

1980-01-01

81

Mitochondrial genome data support the basal position of acoelomorpha and the polyphyly of the platyhelminthes  

SciTech Connect

We determined 9.7, 5.2, and 6.8 kb, respectively, of the mitochondrial genomes of the acoel Paratomella rubra, the nemertodermatid Nemertoderma westbladi and the free-living rhabditophoran platyhelminth Microstomum lineare. The identified gene arrangements are unique among metazoans, including each other, sharing no more than one or two single gene boundaries with a few distantly related taxa. Phylogenetic analysis of the amino acid sequences inferred from the sequenced genes confirms that the acoelomorph flatworms (acoels + nemertodermatids) do not belong to the Platyhelminthes, but are, instead, the most basal extant bilaterian group. Therefore, the Platyhelminthes, as traditionally constituted, is a polyphyletic phylum.

Ruiz-Trillo, Inaki; Riutort, Marta; Fourcade, H. Matthew; Baguna, Jaume; Boore, Jeffrey L.

2004-05-01

82

pbx is required for pole and eye regeneration in planarians.  

PubMed

Planarian regeneration involves regionalized gene expression that specifies the body plan. After amputation, planarians are capable of regenerating new anterior and posterior poles, as well as tissues polarized along the anterior-posterior, dorsal-ventral and medial-lateral axes. Wnt and several Hox genes are expressed at the posterior pole, whereas Wnt inhibitory genes, Fgf inhibitory genes, and prep, which encodes a TALE-family homeodomain protein, are expressed at the anterior pole. We found that Smed-pbx (pbx for short), which encodes a second planarian TALE-family homeodomain transcription factor, is required for restored expression of these genes at anterior and posterior poles during regeneration. Moreover, pbx(RNAi) animals gradually lose pole gene expression during homeostasis. By contrast, pbx was not required for initial anterior-posterior polarized responses to wounds, indicating that pbx is required after wound responses for development and maintenance of poles during regeneration and homeostatic tissue turnover. Independently of the requirement for pbx in pole regeneration, pbx is required for eye precursor formation and, consequently, eye regeneration and eye replacement in homeostasis. Together, these data indicate that pbx promotes pole formation of body axes and formation of regenerative progenitors for eyes. PMID:23318641

Chen, Chun-Chieh G; Wang, Irving E; Reddien, Peter W

2013-02-01

83

Histone modifications and regeneration in the planarian Schmidtea mediterranea.  

PubMed

The freshwater planarian Schmidtea mediterranea has emerged as a powerful model system for studying regeneration and adult stem cell (ASC) biology. This is largely due to the developmental plasticity of these organisms and the abundant distribution and experimental accessibility of their ASCs. Techniques such as whole mount in situ hybridization, dsRNA-mediated interference, halogenated thymidine analogs for defining cell lineages, and fluorescence-activated cell sorting among other methods, have allowed researchers to interrogate the biology and attendant pluripotent stem cells of these animals in great detail. Therefore, it has now become possible to interrogate and define the roles that epigenetic states may play in regulating ASCs, and by extension, regeneration proper. Here, we provide a primer on the types and number of histone families found in S. mediterranea, known as epigenetic marks of these molecules and a survey of epigenetic modifying enzymes encoded by the planarian genome. We also review experimental evidence indicating that such modifications may in fact play key roles in determining the activities of planarian stem cells. PMID:24512706

Robb, Sofia M C; Sánchez Alvarado, Alejandro

2014-01-01

84

Effects of dimethylsulfoxide on behavior and antioxidant enzymes response of planarian Dugesia japonica.  

PubMed

In this study, the toxicity, behavioral and antioxidant activity effects of dimethylsulfoxide (DMSO) on planarian Dugesia japonica were investigated. The results showed that the mortality was directly proportional to the DMSO concentration, and planarian locomotor velocity decreased as the concentration of DMSO increased. The recovery of the motility for planarians pre-exposed to DMSO was found to be time- and dose-dependent, and only those pre-exposed to 0.1-3% DMSO resulted in full recovery. The antioxidant enzymes of planarians in response to long-term DMSO stress was also altered in a time- and dose-dependent manner. Planarians revealed more tolerance to DMSO toxicity at low DMSO (0.1%) level in short- and long-term DMSO stress, in which an efficient antioxidant system was involved and the motility was not affected. PMID:21976142

Yuan, Zuoqing; Zhao, Bosheng; Zhang, Yu

2012-06-01

85

Study of planarian stem cell proliferation by means of flow cytometry.  

PubMed

The stem cells in freshwater flatworms (planarian) are called neoblasts. Neoblasts are capable of proliferation and differentiation into every cell type, including the gametes. For the investigation of the mechanisms of stem cells proliferation and differentiation the proper evaluation of changes in the cell cycle of neoblasts in different physiological conditions of planarian is necessary. In the present study the possibility of qualitative and quantitative characteristics of the neoblasts population were investigated using flow cytometry. In the cell suspension prepared from planarian tissue proliferating neoblasts have been observed in heterogenic cell population. Quantitative estimation of the cell cycle related changes of planarian stem cells system have been performed in various physiological conditions (intact and regenerating animals) and under the influence of physical (ionizing radiation) and chemical (melatonin and colchicine) factors. The modified protocol for planarian stem cells isolation proved to be effective and reproducible and can be recommended for flow cytometry analyses of human and animal proliferating cells. PMID:21688150

Ermakov, Artem M; Ermakova, Olga N; Kudravtsev, Andrei A; Kreshchenko, Natalia D

2012-03-01

86

Fine-structural characteristics of female and male germ cells in Proseriata Otoplanidae (Platyhelminthes)  

Microsoft Academic Search

Fine-structural features of female germ cells differentiating within the germaria of Otoplanella baltica and Notocaryoplanella glandulosa are documented and compared with those of other free-living platyhelminths having ectolecithal eggs.

Beate Sopott Ehlers

1986-01-01

87

The interrelationships of all major groups of Platyhelminthes: phylogenetic evidence from morphology and molecules  

Microsoft Academic Search

We used a data matrix of 65 morphological characters from 25 ingroup and 6 outgroup taxa, and an alignment comprising complete 18S rDNA sequences from 82 species of parasitic and free-living Platyhelminthes and from 19 species of lower invertebrates to analyse phylogenetic relationships of various platyhelminth taxa. Of the 1358 unambiguously alignable molecular positions, 995 were variable and 757 were

D. T. J. LITTLEWOOD; K. ROHDE; K. A. CLOUGH

1999-01-01

88

Identification of pluripotent stem cells and characterization of glia in the planarian Schmidtea mediterranea  

E-print Network

Given their regenerative capacity, the planarian Schmidtea mediterranea has emerged as a model system for the study of stem cell biology, tissue specification, and axis formation. Many aspects of the regenerative machinery ...

Wang, Irving E

2014-01-01

89

Transcriptome analysis of the planarian eye identifies ovo as a specific regulator of eye regeneration.  

PubMed

Among the millions of invertebrate species with visual systems, the genetic basis of eye development and function is well understood only in Drosophila melanogaster. We describe an eye transcriptome for the planarian Schmidtea mediterranea. Planarian photoreceptors expressed orthologs of genes required for phototransduction and microvillus structure in Drosophila and vertebrates, and optic pigment cells expressed solute transporters and melanin synthesis enzymes similar to those active in the vertebrate retinal pigment epithelium. Orthologs of several planarian eye genes, such as bestrophin-1 and Usher syndrome genes, cause eye defects in mammals when perturbed and were not previously described to have roles in invertebrate eyes. Five previously undescribed planarian eye transcription factors were required for normal eye formation during head regeneration. In particular, a conserved, transcription-factor-encoding ovo gene was expressed from the earliest stages of eye regeneration and was required for regeneration of all cell types of the eye. PMID:22884275

Lapan, Sylvain W; Reddien, Peter W

2012-08-30

90

The history and enduring contributions of planarians to the study of animal regeneration.  

PubMed

Having an almost unlimited capacity to regenerate tissues lost to age and injury, planarians have long fascinated naturalists. In the Western hemisphere alone, their documented history spans more than 200 years. Planarians were described in the early 19th century as being 'immortal under the edge of the knife', and initial investigation of these remarkable animals was significantly influenced by studies of regeneration in other organisms and from the flourishing field of experimental embryology in the late 19th and early 20th centuries. This review strives to place the study of planarian regeneration into a broader historical context by focusing on the significance and evolution of knowledge in this field. It also synthesizes our current molecular understanding of the mechanisms of planarian regeneration uncovered since this animal's relatively recent entrance into the molecular-genetic age. PMID:23799578

Elliott, Sarah A; Sánchez Alvarado, Alejandro

2013-01-01

91

Innate immune system and tissue regeneration in planarians: an area ripe for exploration.  

PubMed

The immune system has been implicated as an important modulator of tissue regeneration. However, the mechanisms driving injury-induced immune response and tissue repair remain poorly understood. For over 200 years, planarians have been a classical model for studies on tissue regeneration, but the planarian immune system and its potential role in repair is largely unknown. We found through comparative genomic analysis and data mining that planarians contain many potential homologs of the innate immune system that are activated during injury and repair of adult tissues. These findings support the notion that the relationship between adult tissue repair and the immune system is an ancient feature of basal Bilateria. Further analysis of the planarian immune system during regeneration could potentially add to our understanding of how the innate immune system and inflammatory responses interplay with regenerative signals to induce scar-less tissue repair in the context of the adult organism. PMID:25082737

Peiris, T Harshani; Hoyer, Katrina K; Oviedo, Néstor J

2014-08-01

92

Transcriptome analysis of the planarian eye identifies ovo as a specific regulator of eye regeneration  

PubMed Central

Summary Among the millions of invertebrate species with visual systems, the genetic basis of eye development and function is well understood only in Drosophila melanogaster. We describe an eye transcriptome for the planarian Schmidtea mediterranea. Planarian photoreceptors expressed orthologs of genes required for phototransduction and microvillus structure in Drosophila and vertebrates, and optic pigment cells expressed solute transporters and melanin synthesis enzymes similar to those active in the vertebrate retinal pigment epithelium. Orthologs of several planarian eye genes, such as bestrophin-1 and Usher syndrome genes, cause eye defects in mammals when perturbed and were not previously described to have roles in invertebrate eyes. Five previously undescribed planarian eye transcription factors were required for normal eye formation during head regeneration. In particular, a conserved, transcription factor-encoding ovo gene was expressed from the earliest stages of eye regeneration and was required for regeneration of all cell types of the eye. PMID:22884275

Lapan, Sylvain W.; Reddien, Peter W.

2013-01-01

93

Cellular and genetic mechanisms of new tissue production in the regenerating planarian Schmidtea mediterranea  

E-print Network

Regeneration of missing body parts is biologically fascinating, yet poorly understood. Many instances of regeneration, such as the replacement of amphibian limbs or planarian heads, require both a source for new cellular ...

Wagner, Daniel Elger

2012-01-01

94

Molecular mechanisms of regeneration initiation and dorsal-ventral patterning in planarians  

E-print Network

Regeneration is widespread among animals, yet very little is known about the molecular mechanisms that govern regenerative processes. Planarians have emerged in recent years as a powerful model for studying regeneration ...

Gaviño, Michael A. (Michael Alexander)

2013-01-01

95

Transcriptome Analysis of the Planarian Eye Identifies ovo as a Specific Regulator of Eye Regeneration  

E-print Network

Among the millions of invertebrate species with visual systems, the genetic basis of eye development and function is well understood only in Drosophila melanogaster. We describe an eye transcriptome for the planarian ...

Lapan, Sylvain W.

96

The early emergence of platyhelminths is contradicted by the agreement between 18S rRNA and Hox genes data  

Microsoft Academic Search

The phylogenetic position of thé platyhelminths within the metazoan tree is examined using two independent sets of molecular characters, the evolution of 18S ribosomal RNA sequences and the diversity of the genes belonging to the HOX cluster. Among the various hypotheses that have been considered by zoologists, a position of the platyhelminths within the protostomes, related to the phyla with

Guillaume Balavoine

1997-01-01

97

Neoblast specialization in regeneration of the planarian Schmidtea mediterranea.  

PubMed

Planarians can regenerate any missing body part in a process requiring dividing cells called neoblasts. Historically, neoblasts have largely been considered a homogeneous stem cell population. Most studies, however, analyzed neoblasts at the population rather than the single-cell level, leaving the degree of heterogeneity in this population unresolved. We combined RNA sequencing of neoblasts from wounded planarians with expression screening and identified 33 transcription factors transcribed in specific differentiated cells and in small fractions of neoblasts during regeneration. Many neoblast subsets expressing distinct tissue-associated transcription factors were present, suggesting candidate specification into many lineages. Consistent with this possibility, klf, pax3/7, and FoxA were required for the differentiation of cintillo-expressing sensory neurons, dopamine-?-hydroxylase-expressing neurons, and the pharynx, respectively. Together, these results suggest that specification of cell fate for most-to-all regenerative lineages occurs within neoblasts, with regenerative cells of blastemas being generated from a highly heterogeneous collection of lineage-specified neoblasts. PMID:25254346

Scimone, M Lucila; Kravarik, Kellie M; Lapan, Sylvain W; Reddien, Peter W

2014-08-12

98

Estimation of the toxicity of silver nanoparticles by using planarian flatworms.  

PubMed

The regeneration of planarian flatworms - specifically, changes to the area of the regeneration bud (blastema) after surgical dissection - was proposed for use as a robust tool for estimating the toxicity of silver nanoparticles. The use of Planaria species, due to their unique regenerative capacity, could result in a reduction in the use of more-traditional laboratory animals for toxicity testing. With our novel approach, silver nanoparticles were found to be moderately toxic to the planarian, Girardia tigrina. PMID:24773488

Kustov, Leonid; Tiras, Kharlampii; Al-Abed, Souhail; Golovina, Natalia; Ananyan, Mikhail

2014-03-01

99

Smed-betacatenin-1 Is Required for Anteroposterior Blastema Polarity in Planarian Regeneration  

Microsoft Academic Search

Planarian flatworms can regenerate heads at anterior-facing wounds and tails at posterior-facing wounds throughout the body. How this regeneration polarity is specified has been a classic problem for more than a century. We identified a planarian gene, Smed-betacatenin-1, that controls regeneration polarity. Posterior-facing blastemas regenerate a head instead of a tail in Smed-betacatenin-1(RNAi) animals. Smed-betacatenin-1 is required after wounding and

Christian P. Petersen; Peter W. Reddien

2008-01-01

100

Planarian pharynx regeneration in regenerating tail fragments monitored with cell-specific monoclonal antibodies  

Microsoft Academic Search

The special morphological features of freshwater planarians make them an attractive and informative model for studying the\\u000a processes of regeneration and pattern formation. In this work, we investigate pattern formation and maturation of the planarian\\u000a pharynx during regeneration in tail fragments. Using three monoclonal antibodies (TCAV-1, TF-26 and TMUS-13) specific for\\u000a epithelial, secretory and muscle cells, respectively, we followed the

D. Bueno; Lluis Espinosa; Jaume Baguñà; Rafael Romero

1997-01-01

101

SILAC proteomics of planarians identifies Ncoa5 as a conserved component of pluripotent stem cells.  

PubMed

Planarian regeneration depends on the presence of pluripotent stem cells in the adult. We developed an in vivo stable isotope labeling by amino acids in cell culture (SILAC) protocol in planarians to identify proteins that are enriched in planarian stem cells. Through a comparison of SILAC proteomes of normal and stem cell-depleted planarians and of a stem cell-enriched population of sorted cells, we identified hundreds of stem cell proteins. One of these is an ortholog of nuclear receptor coactivator-5 (Ncoa5/CIA), which is known to regulate estrogen-receptor-mediated transcription in human cells. We show that Ncoa5 is essential for the maintenance of the pluripotent stem cell population in planarians and that a putative mouse ortholog is expressed in pluripotent cells of the embryo. Our study thus identifies a conserved component of pluripotent stem cells, demonstrating that planarians, in particular, when combined with in vivo SILAC, are a powerful model in stem cell research. PMID:24268775

Böser, Alexander; Drexler, Hannes C A; Reuter, Hanna; Schmitz, Henning; Wu, Guangming; Schöler, Hans R; Gentile, Luca; Bartscherer, Kerstin

2013-11-27

102

Pedobiologia 42,433--440 (1998) Gustav Fischer Verlag lena  

E-print Network

(Platyhelminthes, Thrbellaria, Tricladida) inferred from 18S rDNA sequences S. Carranzal, I. Ruiz-Trillol, D. T. J, Platyhelminthes Introduction For over 100 years systematists have recognised three major groups within the Order Tricla- dida (Phylum Platyhelminthes, Class Turbellaria, Order Seriata), using Hallez's (1890) eco

Carranza, Salvador

103

Bioelectric signaling regulates head and organ size during planarian regeneration.  

PubMed

A main goal of regenerative medicine is to replace lost or damaged tissues and organs with functional parts of the correct size and shape. But the proliferation of new cells is not sufficient; we will also need to understand how the scale and ultimate form of newly produced tissues are determined. Using the planarian model system, we report that membrane voltage-dependent bioelectric signaling determines both head size and organ scaling during regeneration. RNA interference of the H(+),K(+)-ATPase ion pump results in membrane hyperpolarization, which has no effect on the amount of new tissue (blastema) that is regenerated yet produces regenerates with tiny 'shrunken' heads and proportionally oversized pharynges. Our data show that this disproportionality results from a lack of the apoptosis required to adjust head and organ size and placement, highlighting apoptotic remodeling as the link between bioelectric signaling and the establishment of organ size during regeneration. PMID:23250205

Beane, Wendy Scott; Morokuma, Junji; Lemire, Joan M; Levin, Michael

2013-01-15

104

Chromatin from two classes of platyhelminthes display both protist H1 and higher eukaryote core histones.  

PubMed

Histones from the parasitic platyhelminthes, Echinococcus granulosus and Fasciola hepatica, were systematically characterized. Core histones H2A, H2B, H3 and H4, which were identified on the basis of amino acid sequencing and mass spectrometry data, showed conserved electrophoretic patterns. Histones H1, identified on the basis of physicochemical properties, amino acid composition and amino acid sequencing, showed divergence, both in their number and electrophoretic mobilities, between the two species and among other organisms. According to these data, core histones but not H1 histones, would be stabilized during evolution at the level of platyhelminthes. PMID:15178327

Galindo, Mario; Varela, Nelson; Espinoza, Ingrid; Toro, Gabriela Cecilia; Hellman, Ulf; Wernstedt, Christer; Galanti, Norbel

2004-06-01

105

Analysis of motor function modulated by cholinergic neurons in planarian Dugesia japonica.  

PubMed

Recent studies of the freshwater planarian Dugesia japonica have revealed fundamental mechanisms and unique aspects of neuroscience and neuroregeneration. Here, we identified the gene for planarian choline acetyltransferase (Djchat), which is essential for acetylcholine (ACh) biosynthesis. Immunofluorescence studies using anti-Dugesia japonica ChAT (DjChAT) antibody revealed that cholinergic neurons are widely distributed in the planarian nervous system, including the brain, ventral nerve cords, optic nerves, and pharyngeal nerve plexus. In order to investigate the function of cholinergic neurons in planarians, we used both pharmacological and RNA interference (RNAi) approaches. Administration of physostigmine (an acetylcholinesterase inhibitor) clearly elevated the amount of ACh, and then induced sudden muscle contraction behavior in a concentration-dependent manner. In addition, we found that pretreatment with tubocurarine (a muscle nicotinic ACh receptor antagonist) or atropine (a non-selective muscarinic ACh receptor antagonist), but not pretreatment with mecamylamine (a neural nicotinic ACh receptor antagonist), significantly extended the latency time for physostigmine-induced contraction behavior, suggesting that muscle nicotinic ACh receptors and muscarinic ACh receptors contribute to physostigmine-induced contraction behavior. We also confirmed that ACh biosynthesis ability and DjChAT-immunoreactivity were eliminated in Djchat(RNAi) planarians. Moreover, the decrease of the level of ACh induced by Djchat(RNAi) caused extension of the latency time for contraction behavior. Our findings support the possibility that the cholinergic functions of planarians are similar to those of vertebrates, suggesting that planarians are simple but useful model organisms for getting insight into the cholinergic nervous system in higher animals. PMID:20338223

Nishimura, K; Kitamura, Y; Taniguchi, T; Agata, K

2010-06-16

106

The BMP pathway is essential for re-specification and maintenance of the dorsoventral axis in regenerating and intact planarians  

Microsoft Academic Search

The bone morphogenetic protein (BMP) pathway has been shown to play an important role in the establishment of the dorsoventral axis during development in both vertebrate and invertebrate species. In an attempt to unravel the role of BMPs in pattern formation during planarian regeneration, we studied this signaling pathway in Schmidtea mediterranea. Here, we functionally characterize planarian homologues of two

M Molina; Emili Saló; Francesc Cebrià

2007-01-01

107

Thermosensory signaling by TRPM is processed by brain serotonergic neurons to produce planarian thermotaxis.  

PubMed

For most organisms, sensitive recognition of even slight changes in environmental temperature is essential for adjusting their behavioral strategies to ensure homeostasis and survival. However, much remains to be understood about the molecular and cellular processes that regulate thermosensation and the corresponding behavioral responses. Planarians display clear thermotaxis, although they have a relatively simple brain. Here, we devised a quantitative thermotaxis assay and unraveled a neural pathway involved in planarian thermotaxis by combinatory behavioral assays and RNAi analysis. We found that thermosensory neurons that expressed a planarian Dugesia japonica homolog of the Transient Receptor Potential Melastatin family a (DjTRPMa) gene were required for the thermotaxis. Interestingly, although these thermosensory neurons are distributed throughout their body, planarians with a dysfunctional brain due to regeneration-dependent conditional gene knockdown (Readyknock) of the synaptotagmin gene completely lost their thermotactic behavior. These results suggest that brain function is required as a central processor for the thermosensory response. Therefore, we investigated the type(s) of brain neurons involved in processing the thermal signals by gene knockdown of limiting enzymes for neurotransmitter biosynthesis in the brain. We found that serotonergic neurons with dendrites that were elongated toward DjTRPMa-expressing thermosensory neurons might be required for the processing of signals from thermosensory neurons that results in thermotaxis. These results suggest that serotonergic neurons in the brain may interact with thermosensory neurons activated by TRPM ion channels to produce thermotaxis in planarians. PMID:25411498

Inoue, Takeshi; Yamashita, Taiga; Agata, Kiyokazu

2014-11-19

108

Effects of N,N-dimethylformamide on behaviour and regeneration of planarian Dugesia japonica.  

PubMed

In this study, the toxicity, behavioural and regeneration effects of dimethylformamide (DMF) on planarian Dugesia japonica were investigated. One control and six different concentrations of DMF (10 ppm, 100 ppm, 500 ppm, 1000 ppm, 5000 ppm and 10,000 ppm) were used in triplicate. The results showed that the mortality was directly proportional to the DMF concentration and planarian locomotor velocity (pLMV) was significantly reduced by increasing the exposure time and DMF concentration. pLMV of D. japonica was significantly reduced at a lower concentration of 10 ppm after 7 days of continuous exposure to DMF. The recovery of the motility of planarians pretreated with DMF was found to be time- and dose dependent, all planarians had complete recovery in their motility after 48 h. The appearance of auricles in regenerating animals was easily affected by DMF exposure in comparison with the appearance of eyespot. The present results suggest that the intact adult mobility in the aquatic planarian D. japonica is a more sensitive biomarker than mortality, and the appearance of auricles in regenerating animals is a more sensitive biomarker than eyespot. PMID:22495519

Zhang, Jianyong; Yuan, Zuoqing; Zheng, Mingyue; Sun, Yuqian; Wang, Youjun; Yang, Shudong

2013-09-01

109

A molecular wound response program associated with regeneration initiation in planarians.  

PubMed

Planarians are capable of regenerating any missing body part and present an attractive system for molecular investigation of regeneration initiation. The gene activation program that occurs at planarian wounds to coordinate regenerative responses remains unknown. We identified a large set of wound-induced genes during regeneration initiation in planarians. Two waves of wound-induced gene expression occurred in differentiated tissues. The first wave includes conserved immediate early genes. Many second-wave genes encode conserved patterning factors required for proper regeneration. Genes of both classes were generally induced by wounding, indicating that a common initial gene expression program is triggered regardless of missing tissue identity. Planarian regeneration uses a population of regenerative cells (neoblasts), including pluripotent stem cells. A class of wound-induced genes was activated directly within neoblasts, including the Runx transcription factor-encoding runt-1 gene. runt-1 was required for specifying different cell types during regeneration, promoting heterogeneity in neoblasts near wounds. Wound-induced gene expression in neoblasts, including that of runt-1, required SRF (serum response factor) and sos-1. Taken together, these data connect wound sensation to the activation of specific cell type regeneration programs in neoblasts. Most planarian wound-induced genes are conserved across metazoans, and identified genes and mechanisms should be important broadly for understanding wound signaling and regeneration initiation. PMID:22549959

Wenemoser, Danielle; Lapan, Sylvain W; Wilkinson, Alex W; Bell, George W; Reddien, Peter W

2012-05-01

110

Follistatin antagonizes activin signaling and acts with notum to direct planarian head regeneration.  

PubMed

Animals establish their body plans in embryogenesis, but only a few animals can recapitulate this signaling milieu for regeneration after injury. In planarians, a pluripotent stem cell population and perpetual signaling of polarity axes collaborate to direct a steady replacement of cells during homeostasis and to power robust regeneration after even severe injuries. Several studies have documented the roles of conserved signaling pathways in maintaining and resetting axial polarity in planarians, but it is unclear how planarians reestablish polarity signaling centers after injury and whether these centers serve to influence identity decisions of stem cell progeny during their differentiation. Here we find that a planarian Follistatin homolog directs regeneration of anterior identity by opposing an Activin/ActR-1/Smad2/3 signaling pathway. Follistatin and Notum, a Wnt inhibitor, are mutually required to reestablish an anterior signaling center that expresses both cues. Furthermore, we show that the direction of cells down particular differentiation paths requires regeneration of this anterior signaling center. Just as its amphibian counterpart in the organizer signals body plan and cell fate during embryogenesis, planarian Follistatin promotes reestablishment of anterior polarity during regeneration and influences specification of cell types in the head and beyond. PMID:23297191

Roberts-Galbraith, Rachel H; Newmark, Phillip A

2013-01-22

111

A Pitx transcription factor controls the establishment and maintenance of the serotonergic lineage in planarians.  

PubMed

In contrast to adult vertebrates, which have limited capacities for neurogenesis, adult planarians undergo constitutive cellular turnover during homeostasis and are even able to regenerate a whole brain after decapitation. This enormous plasticity derives from pluripotent stem cells residing in the planarian body in large numbers. It is still obscure how these stem cells are programmed for differentiation into specific cell lineages and how lineage identity is maintained. Here we identify a Pitx transcription factor of crucial importance for planarian regeneration. In addition to patterning defects that are co-dependent on the LIM homeobox transcription factor gene islet1, which is expressed with pitx at anterior and posterior regeneration poles, RNAi against pitx results in islet1-independent specific loss of serotonergic (SN) neurons during regeneration. Besides its expression in terminally differentiated SN neurons we found pitx in stem cell progeny committed to the SN fate. Also, intact pitx RNAi animals gradually lose SN markers, a phenotype that depends neither on increased apoptosis nor on stem cell-based turnover or transdifferentiation into other neurons. We propose that pitx is a terminal selector gene for SN neurons in planarians that controls not only their maturation but also their identity by regulating the expression of the Serotonin production and transport machinery. Finally, we made use of this function of pitx and compared the transcriptomes of regenerating planarians with and without functional SN neurons, identifying at least three new neuronal targets of Pitx. PMID:24131630

März, Martin; Seebeck, Florian; Bartscherer, Kerstin

2013-11-01

112

Land Planarian Assemblages in Protected Areas of the Interior Atlantic Forest: Implications for Conservation  

PubMed Central

Land planarians are an interesting group of free-living flatworms that can be useful as bioindicators because of their high sensitivity to environmental changes and low dispersal capacity. In this study, we describe and compare assemblages of land planarians from areas with different conservation degrees of the Interior Atlantic Forest (Misiones, Argentina), and assess factors that could be related to their abundance and richness. Eight sites were tracked in search of land planarians in Reserva de Vida Silvestre Urugua-í (RVSU) and Campo Anexo Manuel Belgrano (CAMB). Diurnal and nocturnal surveys were performed in each site along nine sampling campaigns. We collected 237 individuals belonging to 18 species of the subfamily Geoplaninae. All sites were dominated by Geoplana sp. 1 and Pasipha hauseri. The richness estimators showed that there would be more species in RVSU than in CAMB. The abundance and richness of land planarians was high during the night and after rainfalls, suggesting an increased activity of flatworms under such conditions. The abundance and richness of land planarians were also related to the conservation condition of the sites. Disturbed sites showed less abundance and richness, and were segregated from non-disturbed ones by nmMDS analysis. Beta diversity between sites was higher than expected, indicating that the species turnover between sites contributed more to the total richness (gamma diversity) than the alpha diversity. PMID:24598934

Negrete, Lisandro; Colpo, Karine D.; Brusa, Francisco

2014-01-01

113

Comparative selenoproteome analysis reveals a reduced utilization of selenium in parasitic platyhelminthes  

PubMed Central

Background. The selenocysteine(Sec)-containing proteins, selenoproteins, are an important group of proteins present in all three kingdoms of life. Although the selenoproteomes of many organisms have been analyzed, systematic studies on selenoproteins in platyhelminthes are still lacking. Moreover, comparison of selenoproteomes between free-living and parasitic animals is rarely studied. Results. In this study, three representative organisms (Schmidtea mediterranea, Schistosoma japonicum and Taenia solium) were selected for comparative analysis of selenoproteomes in Platyhelminthes. Using a SelGenAmic-based selenoprotein prediction algorithm, a total of 37 selenoprotein genes were identified in these organisms. The size of selenoproteomes and selenoprotein families were found to be associated with different lifestyles: free-living organisms have larger selenoproteome whereas parasitic lifestyle corresponds to reduced selenoproteomes. Five selenoproteins, SelT, Sel15, GPx, SPS2 and TR, were found to be present in all examined platyhelminthes as well as almost all sequenced animals, suggesting their essential role in metazoans. Finally, a new splicing form of SelW that lacked the first exon was found to be present in S. japonicum. Conclusions. Our data provide a first glance into the selenoproteomes of organisms in the phylum Platyhelminthes and may help understand function and evolutionary dynamics of selenium utilization in diversified metazoans. PMID:24255816

Jiang, Liang; Zhu, Hua-Zhang; Xu, Yin-Zhen; Ni, Jia-Zuan

2013-01-01

114

Comparative study of adaptive radiations with an example using parasitic flatworms (Platyhelminthes): Cercomeria  

Microsoft Academic Search

Studies of adaptive radiations require robust phylogenies, estimates of species numbers for monophyletic groups within clades, assessments of the adaptive value of putative key innovations, and estimates of the frequency of speciation modes. Four criteria are necessary to identify an adaptive radiation within the parasitic platyhelminths: (1) a group contains significantly more species than its sister group, (2) species richness

Daniel R. Brooks; Deborah A. McLennan

1993-01-01

115

Advances and Trends in the Molecular Systematics of the Parasitic Platyhelminthes  

Microsoft Academic Search

The application of molecular systematics to the parasitic Platyhelminthes (Cestoda, Digenea and Monogenea) over the last decade has advanced our understanding of their interrelationships and evolution substantially. Here we review the current state of play and the early works that led to the molecular-based hypotheses that now predominate in the field; advances in their systematics, taxonomy, classification and phylogeny, as

Peter D. Olson; Vasyl V. Tkach

2005-01-01

116

Evolution of body-wall musculature in the Platyhelminthes (Acoelomorpha, Catenulida, Rhabditophora)  

Microsoft Academic Search

In an effort to understand the phylogeny of the Platyhelminthes, the patterns of body-wall muscula- ture of flatworms were studied using fluorescence micros- copy and Alexa-488-labeled phalloidin. Species of the Catenulida have a simple orthogonal gridwork of longitu- dinal and circular muscles. Members of the Rhabdito- phora have the same gridwork of musculature, but also have diagonal muscles over their

Matthew D. Hooge

2001-01-01

117

Schistosoma mansoni (Platyhelminthes, Trematoda) nuclear receptors: Sixteen new members and a novel subfamily  

Microsoft Academic Search

Nuclear receptors (NRs) are important transcriptional modulators in metazoans. Sixteen new NRs were identified in the Platyhelminth trematode, Schistosoma mansoni. Three were found to possess novel tandem DNA-binding domains that identify a new subfamily of NR. Two NRs are homologues of the thyroid hormone receptor that previously were thought to be restricted to chordates. This study brings the total number

Wenjie Wu; Edward G. Niles; Najib El-Sayed; Matthew Berriman; Philip T. LoVerde

2006-01-01

118

An RNAi screen reveals intestinal regulators of branching morphogenesis, differentiation, and stem cell proliferation in planarians  

PubMed Central

SUMMARY Planarians grow and regenerate organs by coordinating proliferation and differentiation of pluripotent stem cells with remodeling of post-mitotic tissues. Understanding how these processes are orchestrated requires characterizing cell type-specific gene expression programs and their regulation during regeneration and homeostasis. To this end, we analyzed the expression profile of planarian intestinal phagocytes, cells responsible for digestion and nutrient storage/distribution. Utilizing RNA interference, we identified cytoskeletal regulators required for intestinal branching morphogenesis, and a modulator of bioactive sphingolipid metabolism, ceramide synthase, required for the production of functional phagocytes. Additionally, we found that a gut-enriched homeobox transcription factor, nkx-2.2, is required for somatic stem cell proliferation, suggesting a niche-like role for phagocytes. Identification of evolutionarily conserved regulators of intestinal branching, differentiation, and stem cell dynamics demonstrates the utility of the planarian digestive system as a model for elucidating the mechanisms controlling post-embryonic organogenesis. PMID:23079596

Forsthoefel, David J.; James, Noelle P.; Escobar, David J.; Stary, Joel M.; Vieira, Ana P.; Waters, Forrest A.; Newmark, Phillip A.

2012-01-01

119

Planarian MBD2/3 is required for adult stem cell pluripotency independently of DNA methylation.  

PubMed

Planarian adult stem cells (pASCs) or neoblasts represent an ideal system to study the evolution of stem cells and pluripotency as they underpin an unrivaled capacity for regeneration. We wish to understand the control of differentiation and pluripotency in pASCs and to understand how conserved, convergent or divergent these mechanisms are across the Bilateria. Here we show the planarian methyl-CpG Binding Domain 2/3 (mbd2/3) gene is required for pASC differentiation during regeneration and tissue homeostasis. The genome does not have detectable levels of 5-methylcytosine (5(m)C) and we find no role for a potential DNA methylase. We conclude that MBD proteins may have had an ancient role in broadly controlling animal stem cell pluripotency, but that DNA methylation is not involved in planarian stem cell differentiation. PMID:24063805

Jaber-Hijazi, Farah; Lo, Priscilla J K P; Mihaylova, Yuliana; Foster, Jeremy M; Benner, Jack S; Tejada Romero, Belen; Chen, Chen; Malla, Sunir; Solana, Jordi; Ruzov, Alexey; Aziz Aboobaker, A

2013-12-01

120

An RNAi screen reveals intestinal regulators of branching morphogenesis, differentiation, and stem cell proliferation in planarians.  

PubMed

Planarians grow and regenerate organs by coordinating proliferation and differentiation of pluripotent stem cells with remodeling of postmitotic tissues. Understanding how these processes are orchestrated requires characterizing cell-type-specific gene expression programs and their regulation during regeneration and homeostasis. To this end, we analyzed the expression profile of planarian intestinal phagocytes, cells responsible for digestion and nutrient storage/distribution. Utilizing RNA interference, we identified cytoskeletal regulators required for intestinal branching morphogenesis and a modulator of bioactive sphingolipid metabolism, ceramide synthase, required for the production of functional phagocytes. Additionally, we found that a gut-enriched homeobox transcription factor, nkx-2.2, is required for somatic stem cell proliferation, suggesting a niche-like role for phagocytes. Identification of evolutionarily conserved regulators of intestinal branching, differentiation, and stem cell dynamics demonstrates the utility of the planarian digestive system as a model for elucidating the mechanisms controlling postembryonic organogenesis. PMID:23079596

Forsthoefel, David J; James, Noëlle P; Escobar, David J; Stary, Joel M; Vieira, Ana P; Waters, Forrest A; Newmark, Phillip A

2012-10-16

121

Planarian MBD2/3 is required for adult stem cell pluripotency independently of DNA methylation?  

PubMed Central

Planarian adult stem cells (pASCs) or neoblasts represent an ideal system to study the evolution of stem cells and pluripotency as they underpin an unrivaled capacity for regeneration. We wish to understand the control of differentiation and pluripotency in pASCs and to understand how conserved, convergent or divergent these mechanisms are across the Bilateria. Here we show the planarian methyl-CpG Binding Domain 2/3 (mbd2/3) gene is required for pASC differentiation during regeneration and tissue homeostasis. The genome does not have detectable levels of 5-methylcytosine (5mC) and we find no role for a potential DNA methylase. We conclude that MBD proteins may have had an ancient role in broadly controlling animal stem cell pluripotency, but that DNA methylation is not involved in planarian stem cell differentiation. PMID:24063805

Jaber-Hijazi, Farah; Lo, Priscilla J.K.P.; Mihaylova, Yuliana; Foster, Jeremy M.; Benner, Jack S.; Tejada Romero, Belen; Chen, Chen; Malla, Sunir; Solana, Jordi; Ruzov, Alexey; Aziz Aboobaker, A.

2013-01-01

122

Cytosine methylation is a conserved epigenetic feature found throughout the phylum Platyhelminthes  

PubMed Central

Background The phylum Platyhelminthes (flatworms) contains an important group of bilaterian organisms responsible for many debilitating and chronic infectious diseases of human and animal populations inhabiting the planet today. In addition to their biomedical and veterinary relevance, some platyhelminths are also frequently used models for understanding tissue regeneration and stem cell biology. Therefore, the molecular (genetic and epigenetic) characteristics that underlie trophic specialism, pathogenicity or developmental maturation are likely to be pivotal in our continued studies of this important metazoan group. Indeed, in contrast to earlier studies that failed to detect evidence of cytosine or adenine methylation in parasitic flatworm taxa, our laboratory has recently defined a critical role for cytosine methylation in Schistosoma mansoni oviposition, egg maturation and ovarian development. Thus, in order to identify whether this epigenetic modification features in other platyhelminth species or is a novelty of S. mansoni, we conducted a study simultaneously surveying for DNA methylation machinery components and DNA methylation marks throughout the phylum using both parasitic and non-parasitic representatives. Results Firstly, using both S. mansoni DNA methyltransferase 2 (SmDNMT2) and methyl-CpG binding domain protein (SmMBD) as query sequences, we illustrate that essential DNA methylation machinery components are well conserved throughout the phylum. Secondly, using both molecular (methylation specific amplification polymorphism, MSAP) and immunological (enzyme-linked immunoabsorbent assay, ELISA) methodologies, we demonstrate that representative species (Echinococcus multilocularis, Protopolystoma xenopodis, Schistosoma haematobium, Schistosoma japonicum, Fasciola hepatica and Polycelis nigra) within all four platyhelminth classes (Cestoda, Monogenea, Trematoda and ‘Turbellaria’) contain methylated cytosines within their genome compartments. Conclusions Collectively, these findings provide the first direct evidence for a functionally conserved and enzymatically active DNA methylation system throughout the Platyhelminthes. Defining how this epigenetic feature shapes phenotypic diversity and development within the phylum represents an exciting new area of metazoan biology. PMID:23837670

2013-01-01

123

The molecular logic for planarian regeneration along the anterior-posterior axis.  

PubMed

The planarian Dugesia japonica can regenerate a complete individual from a head, trunk or tail fragment via activation of somatic pluripotent stem cells. About a century ago, Thomas Hunt Morgan attempted to explain the extraordinary regenerative ability of planarians by positing two opposing morphogenetic gradients of formative "head stuff" and "tail stuff" along the anterior-posterior axis. However, Morgan's hypothesis remains open to debate. Here we show that extracellular signal-related kinase (ERK) and Wnt/?-catenin signalling pathways establish a solid framework for planarian regeneration. Our data suggest that ERK signalling forms a spatial gradient in the anterior region during regeneration. The fibroblast growth factor receptor-like gene nou-darake (which serves as an output of ERK signalling in the differentiating head) and posteriorly biased ?-catenin activity negatively regulate ERK signalling along the anterior-posterior axis in distinct manners, and thereby posteriorize regenerating tissues outside the head region to reconstruct a complete head-to-tail axis. On the basis of this knowledge about D. japonica, we proposed that ?-catenin signalling is responsible for the lack of head-regenerative ability of tail fragments in the planarian Phagocata kawakatsui, and our confirmation thereof supports the notion that posterior ?-catenin signalling negatively modulates the ERK signalling involved in anteriorization across planarian species. These findings suggest that ERK signalling has a pivotal role in triggering globally dynamic differentiation of stem cells in a head-to-tail sequence through a default program that promotes head tissue specification in the absence of posteriorizing signals. Thus, we have confirmed the broad outline of Morgan's hypothesis, and refined it on the basis of our proposed default property of planarian stem cells. PMID:23883928

Umesono, Yoshihiko; Tasaki, Junichi; Nishimura, Yui; Hrouda, Martina; Kawaguchi, Eri; Yazawa, Shigenobu; Nishimura, Osamu; Hosoda, Kazutaka; Inoue, Takeshi; Agata, Kiyokazu

2013-08-01

124

Monogeneans (Platyhelminthes) from marine fishes of Tongyeong, Korea.  

PubMed

Monogeneans (Platyhelminthes) mostly parasitize on fins, skin and gills of fishes. In Korea, the study on monogeneans is limited, although, fishes are frequently encountered with severe infection of monogeneans. Hence, some of ranched and wild fishes were collected from Tongyeong marine living resources research and conservation center, southern part of Korea to screen and understand the infection of monogeneans. All three fish hosts were found with the infection of monogeneans including five species from four different families. They are: (1) Anoplodiscus spari Yamaguti (Publ Seto Mar Biol Lab Kyoto Univ 7:53-88, 1958) (Anoplodiscidae) from the fins and body surface of blackhead seabream Acanthopagrus schlegelii schlegelii (Bleeker); (2) A. tai Ogawa (Fish Pathol 29:5-10, 1994) from the fins of red seabream Pagrus major (Temminck and Schlegel); (3) Benedenia sekii Yamaguti (Studies on the helminth fauna of Japan. Part 19. Fourteen new ectoparasitic trematodes of fishes. Published by the author, Kyoto, 1937), Meserve (Rep Allan Hancock Paci Exped (1932-1937) 2:31-89, 1938) (Capsalidae) from the body surface of P. major; (4) Choricotyle elongata Goto (J Coll Sci Imp Univ Tokyo 8:1-273, 1894) (Diclidophoridae) from the gills of P. major; (5) Udonella fugu Freeman and Ogawa (Int J Parasitol 40:255-264, 2010) (Udonellidae) hyperparasitized on the body of parasitic copepod Pseudocaligus fugu (Yamaguti 1936) (Caligidae) infecting the wild grass puffer Takifugu niphobles (Jordan and Snyder). Capsalids are commonly reported in Korea, except B. sekii, however, other reported genera are uncommon. Hence, all reported monogeneans are considered as a first record from Korea. PMID:25035585

Venmathi Maran, B A; Oh, Sung-Yong; Moon, Seong Yong; Soh, Ho Young; Kim, Chong-Kwan; Myoung, Jung-Goo

2014-09-01

125

Making heads or tails: planarian stem cells in the classroom.  

PubMed

Stem cells hold great promise in the treatment of diseases ranging from cancer to dementia. However, as rapidly as the field of stem cell biology has emerged, heated political debate has followed, scrutinizing the ethical implications of stem cell use. It is therefore imperative to promote scientific literacy by educating students about stem cell biology. Yet, there is a definite lack of material to engage students in this subject at the basic science level. Therefore, we have developed and implemented a hands-on introductory laboratory module that introduces students to stem cell biology and can be easily incorporated into existing curricula. Students learn about stem cell biology using an in vivo planarian model system in which they down-regulate two genes important in stem cell differentiation using RNA interference and then observe the regenerative phenotype. The module was piloted at the high school, community college, and university levels. Here, we report that introductory biology students enrolled at a community college were able to demonstrate gains in learning after completion of a one-hour lecture and four 45-minute laboratory sessions over the course of three weeks. These gains in learning outcomes were objectively evaluated both before and after its execution using a student quiz and experimental results. Furthermore, students' self-assessments revealed increases in perceived knowledge as well as a general interest in stem cells. Therefore, these data suggest that this module is a simple, useful way to engage and to teach students about stem cell biology. PMID:24839511

Srougi, Melissa C; Thomas-Swanik, Jackie; Chan, John D; Marchant, Jonathan S; Carson, Susan

2014-05-01

126

Making Heads or Tails: Planarian Stem Cells in the Classroom†  

PubMed Central

Stem cells hold great promise in the treatment of diseases ranging from cancer to dementia. However, as rapidly as the field of stem cell biology has emerged, heated political debate has followed, scrutinizing the ethical implications of stem cell use. It is therefore imperative to promote scientific literacy by educating students about stem cell biology. Yet, there is a definite lack of material to engage students in this subject at the basic science level. Therefore, we have developed and implemented a hands-on introductory laboratory module that introduces students to stem cell biology and can be easily incorporated into existing curricula. Students learn about stem cell biology using an in vivo planarian model system in which they down-regulate two genes important in stem cell differentiation using RNA interference and then observe the regenerative phenotype. The module was piloted at the high school, community college, and university levels. Here, we report that introductory biology students enrolled at a community college were able to demonstrate gains in learning after completion of a one-hour lecture and four 45-minute laboratory sessions over the course of three weeks. These gains in learning outcomes were objectively evaluated both before and after its execution using a student quiz and experimental results. Furthermore, students’ self-assessments revealed increases in perceived knowledge as well as a general interest in stem cells. Therefore, these data suggest that this module is a simple, useful way to engage and to teach students about stem cell biology. PMID:24839511

Srougi, Melissa C.; Thomas-Swanik, Jackie; Chan, John D.; Marchant, Jonathan S.; Carson, Susan

2014-01-01

127

Evolution of Developmental Control Mechanisms Cell death and tissue remodeling in planarian regeneration  

E-print Network

of regeneration has focused on adult stem cells, which give rise to new tissue necessary for the replacement in concert with stem cell division to restore anatomical form and function during metazoan regeneration 18 September 2009 Keywords: Planaria Planarian Cell death Apoptosis Regeneration Tissue remodeling

Alvarado, Alejandro Sánchez

128

High-resolution profiling and discovery of planarian Marc R. Friedlandera,1  

E-print Network

in animals. microRNAs miRNAs piRNAs regeneration stem cells Planarians have become a molecularly tractable model system in which to study regeneration, tissue homeostasis, and stem-cell biology (1). Planaria cells. Key functions of these cells during regeneration and tissue homeostasis have been shown to depend

Alvarado, Alejandro Sánchez

129

Multicellularity, stem cells, and the neoblasts of the planarian Schmidtea mediterranea  

E-print Network

Review Multicellularity, stem cells, and the neoblasts of the planarian Schmidtea mediterranea Available online 25 April 2005 Abstract All multicellular organisms depend on stem cells for their survival of stem cells may have been a prerequisite in the evolution of multicellular organisms. We present

Alvarado, Alejandro Sánchez

130

RNA interference by feeding in vitro synthesized double-stranded RNA to planarians: methodology and dynamics  

PubMed Central

Background The ability to assess gene function is essential for understanding biological processes. Currently, RNA interference (RNAi) is the only technique available to assess gene function in planarians, in which it has been induced via injection of double-stranded RNA (dsRNA), soaking, or ingestion of bacteria expressing dsRNA. Results We describe a simple and robust RNAi protocol, involving in vitro synthesis of dsRNA that is fed to the planarians. Advantages of this protocol include the ability to produce dsRNA from any vector without subcloning, resolution of ambiguities in quantity and quality of input dsRNA, as well as time, and ease of application. We have evaluated the logistics of inducing RNAi in planarians using this methodology in careful detail, from the ingestion and processing of dsRNA in the intestine, to timing and efficacy of knockdown in neoblasts, germline, and soma. We also present systematic comparisons of effects of amount, frequency, and mode of dsRNA delivery. Conclusions This method gives robust and reproducible results and is amenable to high-throughput studies. Overall, this RNAi methodology provides a significant advance by combining the strengths of current protocols available for dsRNA delivery in planarians and has the potential to benefit RNAi methods in other systems. PMID:23441014

Rouhana, Labib; Weiss, Jennifer A.; Forsthoefel, David J.; Lee, Hayoung; King, Ryan S.; Inoue, Takeshi; Shibata, Norito; Agata, Kiyokazu; Newmark, Phillip A.

2013-01-01

131

Planarian regeneration involves distinct stem cell responses to wounds and tissue absence  

Microsoft Academic Search

Regeneration requires signaling from a wound site for detection of the wound and a mechanism that determines the nature of the injury to specify the appropriate regenerative response. Wound signals and tissue responses to wounds that elicit regeneration remain poorly understood. Planarians are able to regenerate from essentially any type of injury and present a novel system for the study

Danielle Wenemoser; Peter W. Reddien

2010-01-01

132

Clonogenic Neoblasts Are Pluripotent Adult Stem Cells That Underlie Planarian Regeneration  

Microsoft Academic Search

Pluripotent cells in the embryo can generate all cell types, but lineage-restricted cells are generally thought to replenish adult tissues. Planarians are flatworms and regenerate from tiny body fragments, a process requiring a population of proliferating cells (neoblasts). Whether regeneration is accomplished by pluripotent cells or by the collective activity of multiple lineage-restricted cell types is unknown. We used ionizing

Daniel E. Wagner; Irving E. Wang; Peter W. Reddien

2011-01-01

133

Planarians require an intact brain to behaviorally react to cocaine, but not to react to nicotine.  

PubMed

Planarians possess a rudimentary brain with many features in common with vertebrate brains. They also display a remarkable capacity for tissue regeneration including the complete regeneration of the nervous system. Using the induction of planarian seizure-like movements (pSLMs) as a behavioral endpoint, we demonstrate that an intact nervous system is necessary for this organism to react to cocaine exposure, but not necessary to react to nicotine administration. Decapitated planarians (Girardia tigrina) display pSLMs indistinguishable from intact worms when exposed to nicotine, but cocaine-induced pSLMs are reduced by about 95% upon decapitation. Decapitated worms recover their normal sensitivity to cocaine within 5 days after head amputation. In worms where half of the brain was removed or partially dissected, the expression of cocaine-induced pSLMs was reduced by approximately 75%. Similar amputations at the level of the tail did not show a significant decrease to cocaine exposure. To the best of our knowledge, our work is the first report that explores how regenerating planarians react to the exposure of cocaine. PMID:23684614

Pagán, O R; Deats, S; Baker, D; Montgomery, E; Wilk, G; Tenaglia, M; Semon, J

2013-08-29

134

Different requirements for conserved post-transcriptional regulators in planarian regeneration and stem cell maintenance  

Microsoft Academic Search

Planarian regeneration depends on the presence and precise regulation of pluripotent adult somatic stem cells named neoblasts, which differentiate to replace cells of any missing tissue. A characteristic feature of neoblasts is the presence of large perinuclear nonmembranous organelles named “chromatoid bodies”, which are comparable to ribonucleoprotein structures found in germ cells of organisms across different phyla. In order to

Labib Rouhana; Norito Shibata; Osamu Nishimura; Kiyokazu Agata

2010-01-01

135

Germ layer specification and axial patterning in the embryonic development of the freshwater planarian Schmidtea polychroa.  

PubMed

Although patterning during regeneration in adult planarians has been studied extensively, very little is known about how the initial planarian body plan arises during embryogenesis. Herein, we analyze the process of embryo patterning in the species Schmidtea polychroa by comparing the expression of genes involved in the establishment of the metazoan body plan. Planarians present a derived ectolecithic spiralian development characterized by dispersed cleavage within a yolk syncytium and an early transient embryo capable of feeding on the maternally supplied yolk cells. During this stage of development, we only found evidence of canonical Wnt pathway, mostly associated with the development of its transient pharynx. At these stages, genes involved in gastrulation (snail) and germ layer determination (foxA and twist) are specifically expressed in migrating blastomeres and those giving rise to the temporary gut and pharyngeal muscle. After yolk ingestion, the embryo expresses core components of the canonical Wnt pathway and the BMP pathway, suggesting that the definitive axial identities are established late. These data support the division of planarian development into two separate morphogenetic stages: a highly divergent gastrulation stage, which segregates the three germ layers and establishes the primary organization of the feeding embryo; and subsequent metamorphosis, based on totipotent blastomeres, which establishes the definitive adult body plan using mechanisms that are similar to those used during regeneration and homeostasis in the adult. PMID:20100474

Martín-Durán, José María; Amaya, Enrique; Romero, Rafael

2010-04-01

136

Infertility in the hyperplasic ovary of freshwater planarians: the role of programmed cell death.  

PubMed

Ex-fissiparous planarians produce infertile cocoons or, in very rare cases, cocoons with very low fertility. Here, we describe the features of programmed cell death (PCD) occurring in the hyperplasic ovary of the ex-fissiparous freshwater planarian Dugesia arabica that may explain this infertility. Based on TEM results, we demonstrate a novel extensive co-clustering of cytoplasmic organelles, such as lysosomes and microtubules, and their fusion with autophagosomes during the early stage of oocyte cell death occurring through an autophagic pattern. During a later stage of cell death, the generation of apoptotic vesicles in the cytoplasm can be observed. The immunohistochemical labeling supports the ultrastructural results because it has been shown that the proapoptotic protein bax was more highly expressed in the hyperplasic ovary than in the normal one, whereas the anti-apoptotic protein bcl2 was slightly more highly expressed in the normal ovary compared to the hyperplasic one. TUNEL analysis of the hyperplasic ovary confirmed that the nuclei of the majority of differentiating oocytes were TUNEL-positive, whereas the nuclei of oogonia and young oocytes were TUNEL-negative; in the normal ovary, oocytes are TUNEL-negative. Considering all of these data, we suggest that the cell death mechanism of differentiating oocytes in the hyperplasic ovary of freshwater planarians is one of the most important factors that cause ex-fissiparous planarian infertility. We propose that autophagy precedes apoptosis during oogenesis, whereas apoptotic features can be observed later. PMID:25107610

Harrath, Abdel Halim; Semlali, Abdelhabib; Mansour, Lamjed; Ahmed, Mukhtar; Sirotkin, Alexander V; Al Omar, Suliman Y; Arfah, Maha; Al Anazi, Mohamed S; Alhazza, Ibrahim M; Nyengaard, Jens R; Alwasel, Saleh

2014-11-01

137

A forkhead Transcription Factor Is Wound-Induced at the Planarian Midline and Required for Anterior Pole Regeneration  

E-print Network

Planarian regeneration requires positional information to specify the identity of tissues to be replaced as well as pluripotent neoblasts capable of differentiating into new cell types. We found that wounding elicits rapid ...

Scimone, M. Lucila

138

Epigenetic regulation of planarian stem cells by the SET1/MLL family of histone methyltransferases.  

PubMed

Chromatin regulation is a fundamental mechanism underlying stem cell pluripotency, differentiation, and the establishment of cell type-specific gene expression profiles. To examine the role of chromatin regulation in stem cells in vivo, we study regeneration in the freshwater planarian Schmidtea mediterranea. These animals possess a high concentration of pluripotent stem cells, which are capable of restoring any damaged or lost tissues after injury or amputation. Here, we identify the S. mediterranea homologs of the SET1/MLL family of histone methyltransferases and COMPASS and COMPASS-like complex proteins and investigate their role in stem cell function during regeneration. We identified six S. mediterranea homologs of the SET1/MLL family (set1, mll1/2, trr-1, trr-2, mll5-1 and mll5-2), characterized their patterns of expression in the animal, and examined their function by RNAi. All members of this family are expressed in the stem cell population and differentiated tissues. We show that set1, mll1/2, trr-1, and mll5-2 are required for regeneration and that set1, trr-1 and mll5-2 play roles in the regulation of mitosis. Most notably, knockdown of the planarian set1 homolog leads to stem cell depletion. A subset of planarian homologs of COMPASS and COMPASS-like complex proteins are also expressed in stem cells and implicated in regeneration, but the knockdown phenotypes suggest that some complex members also function in other aspects of planarian biology. This work characterizes the function of the SET1/MLL family in the context of planarian regeneration and provides insight into the role of these enzymes in adult stem cell regulation in vivo. PMID:23235145

Hubert, Amy; Henderson, Jordana M; Ross, Kelly G; Cowles, Martis W; Torres, Jessica; Zayas, Ricardo M

2013-01-01

139

Mitochondrial genome data support the basal position of Acoelomorpha and the polyphyly of the Platyhelminthes  

Microsoft Academic Search

We determined 9.7, 5.2, and 6.8kb, respectively, of the mitochondrial genomes of the acoel Paratomella rubra, the nemertodermatid Nemertoderma westbladi, and the free-living rhabditophoran platyhelminth Microstomum lineare. The identified gene arrangements are unique among metazoans, including each other, sharing no more than one or two single gene boundaries with a few distantly related taxa. Phylogenetic analysis of the amino acid

Iñaki Ruiz-Trillo; Marta Riutort; H. Matthew Fourcade; Jaume Baguñà; Jeffrey L. Boore

2004-01-01

140

Phylogeny of the Prolecithophora (Platyhelminthes) Inferred from 18S rDNA Sequences  

Microsoft Academic Search

Complete nuclear 18S rDNA sequences from 14 species of the Prolecithophora were obtained and used, in combination with literature data, to generate the first parsimony-based hypothesis of the phylogeny of the order Prolecithophora (Platyhelminthes). Bootstrap, parsimony jack-knife, and Bremer support values were computed and compared. The monophyly of the Prolecithophora sensu stricto and the family Plagiostomidae is strongly supported. The

Michael Norén; Ulf Jondelius

1999-01-01

141

Remarks on the phylogeny and structure of fatty acid binding proteins from parasitic platyhelminths.  

PubMed

Four fatty acid binding proteins (FABPs) have been described in 4 parasitic platyhelminths: Schistosoma mansoni, Schistosoma japonicum, Fasciola hepatica and Echinococcus granulosus. FABPs form a multigenic family of cytosolic proteins widely distributed in metazoan tissues, the function of which is still poorly understood. These helminth proteins have recently received attention, since there are reports to indicate that S. mansoni and F. hepatica FABPs may be protective antigens. In addition, these proteins could play a major role in the parasites' life-cycles because platyhelminths are unable to synthesize de novo most of their lipids. We have undertaken phylogenetic and structural analyses of platyhelminth FABPs in an attempt to characterize features of biological relevance. Phylogenetically, these FABPs appear to be more closely related to those of vertebrate heart, mammary gland, muscle, retina, skin, brain and myelin, although no clear functional relationships were established between them. We describe several conserved motifs characteristic of specific groups of FABPs. Hydrophilicity, flexibility and accessibility analyses revealed several major putative epitopes for the E. granulosus FABP, EgDf1, that appear to be centred in loops of the EgDf1 3-dimensional structure modelled by molecular replacement. PMID:9363483

Esteves, A; Joseph, L; Paulino, M; Ehrlich, R

1997-09-01

142

Planarians as a model to assess in vivo the role of matrix metalloproteinase genes during homeostasis and regeneration.  

PubMed

Matrix metalloproteinases (MMPs) are major executors of extracellular matrix remodeling and, consequently, play key roles in the response of cells to their microenvironment. The experimentally accessible stem cell population and the robust regenerative capabilities of planarians offer an ideal model to study how modulation of the proteolytic system in the extracellular environment affects cell behavior in vivo. Genome-wide identification of Schmidtea mediterranea MMPs reveals that planarians possess four mmp-like genes. Two of them (mmp1 and mmp2) are strongly expressed in a subset of secretory cells and encode putative matrilysins. The other genes (mt-mmpA and mt-mmpB) are widely expressed in postmitotic cells and appear structurally related to membrane-type MMPs. These genes are conserved in the planarian Dugesia japonica. Here we explore the role of the planarian mmp genes by RNA interference (RNAi) during tissue homeostasis and regeneration. Our analyses identify essential functions for two of them. Following inhibition of mmp1 planarians display dramatic disruption of tissues architecture and significant decrease in cell death. These results suggest that mmp1 controls tissue turnover, modulating survival of postmitotic cells. Unexpectedly, the ability to regenerate is unaffected by mmp1(RNAi). Silencing of mt-mmpA alters tissue integrity and delays blastema growth, without affecting proliferation of stem cells. Our data support the possibility that the activity of this protease modulates cell migration and regulates anoikis, with a consequent pivotal role in tissue homeostasis and regeneration. Our data provide evidence of the involvement of specific MMPs in tissue homeostasis and regeneration and demonstrate that the behavior of planarian stem cells is critically dependent on the microenvironment surrounding these cells. Studying MMPs function in the planarian model provides evidence on how individual proteases work in vivo in adult tissues. These results have high potential to generate significant information for development of regenerative and anti cancer therapies. PMID:23405188

Isolani, Maria Emilia; Abril, Josep F; Saló, Emili; Deri, Paolo; Bianucci, Anna Maria; Batistoni, Renata

2013-01-01

143

The More the Merrier?. Entropy and Statistics of Asexual Reproduction in Freshwater Planarians  

NASA Astrophysics Data System (ADS)

The trade-off between traits in life-history strategies has been widely studied for sexual and parthenogenetic organisms, but relatively little is known about the reproduction strategies of asexual animals. Here, we investigate clonal reproduction in the freshwater planarian Schmidtea mediterranea, an important model organism for regeneration and stem cell research. We find that these flatworms adopt a randomized reproduction strategy that comprises both asymmetric binary fission and fragmentation (generation of multiple offspring during a reproduction cycle). Fragmentation in planarians has primarily been regarded as an abnormal behavior in the past; using a large-scale experimental approach, we now show that about one third of the reproduction events in S. mediterranea are fragmentations, implying that fragmentation is part of their normal reproductive behavior. Our analysis further suggests that certain characteristic aspects of the reproduction statistics can be explained in terms of a maximum relative entropy principle.

Quinodoz, Sofia; Thomas, Michael A.; Dunkel, Jörn; Schötz, Eva-Maria

2011-04-01

144

Single-cell analysis reveals functionally distinct classes within the planarian stem cell compartment.  

PubMed

Planarians are flatworms capable of regenerating any missing body region. This capacity is mediated by neoblasts, a proliferative cell population that contains pluripotent stem cells. Although population-based studies have revealed many neoblast characteristics, whether functionally distinct classes exist within this population is unclear. Here, we used high-dimensional single-cell transcriptional profiling from over a thousand individual neoblasts to directly compare gene expression fingerprints during homeostasis and regeneration. We identified two prominent neoblast classes that we named ? (zeta) and ? (sigma). Zeta-neoblasts encompass specified cells that give rise to an abundant postmitotic lineage, including epidermal cells, and are not required for regeneration. By contrast, sigma-neoblasts proliferate in response to injury, possess broad lineage capacity, and can give rise to zeta-neoblasts. These findings indicate that planarian neoblasts comprise two major and functionally distinct cellular compartments. PMID:25017721

van Wolfswinkel, Josien C; Wagner, Daniel E; Reddien, Peter W

2014-09-01

145

Then, in the early fifties, the World Health Organization  

E-print Network

? The capacity of planarians for regeneration is familiar, yet less is known about their internal anatomy, modes@helios.rai.umds.ac.uk Quick guide Planarians Alejandro Sánchez Alvarado What are planarians? As any high school student will tell you, planarians are flat, free-living worms, members of the phylum Platyhelminthes (Platy, flat

Alvarado, Alejandro Sánchez

146

Genome-Wide Analyses Reveal a Role for Peptide Hormones in Planarian Germline Development  

PubMed Central

Bioactive peptides (i.e., neuropeptides or peptide hormones) represent the largest class of cell-cell signaling molecules in metazoans and are potent regulators of neural and physiological function. In vertebrates, peptide hormones play an integral role in endocrine signaling between the brain and the gonads that controls reproductive development, yet few of these molecules have been shown to influence reproductive development in invertebrates. Here, we define a role for peptide hormones in controlling reproductive physiology of the model flatworm, the planarian Schmidtea mediterranea. Based on our observation that defective neuropeptide processing results in defects in reproductive system development, we employed peptidomic and functional genomic approaches to characterize the planarian peptide hormone complement, identifying 51 prohormone genes and validating 142 peptides biochemically. Comprehensive in situ hybridization analyses of prohormone gene expression revealed the unanticipated complexity of the flatworm nervous system and identified a prohormone specifically expressed in the nervous system of sexually reproducing planarians. We show that this member of the neuropeptide Y superfamily is required for the maintenance of mature reproductive organs and differentiated germ cells in the testes. Additionally, comparative analyses of our biochemically validated prohormones with the genomes of the parasitic flatworms Schistosoma mansoni and Schistosoma japonicum identified new schistosome prohormones and validated half of all predicted peptide-encoding genes in these parasites. These studies describe the peptide hormone complement of a flatworm on a genome-wide scale and reveal a previously uncharacterized role for peptide hormones in flatworm reproduction. Furthermore, they suggest new opportunities for using planarians as free-living models for understanding the reproductive biology of flatworm parasites. PMID:20967238

Collins, James J.; Hou, Xiaowen; Romanova, Elena V.; Lambrus, Bramwell G.; Miller, Claire M.; Saberi, Amir; Sweedler, Jonathan V.; Newmark, Phillip A.

2010-01-01

147

Proportion regulation in the planarian, Dugesia tigrina following regeneration of structures  

Microsoft Academic Search

Planarian regenerates with abnormal body proportioning were followed after structure formation in order to determine if body\\u000a proportion will ‘normalize’ over time. Results show proportioning will occur following structure formation since the pharynx\\u000a in regenerates with proportionally larger heads and prepharyngeal area moved anteriorly over time. This occurred regardless\\u000a of whether regenerates were provided with a normal feeding regime which

Robert W. Mead; Jenifer Christman

1998-01-01

148

Early planarian brain regeneration is independent of blastema polarity mediated by the Wnt\\/?-catenin pathway  

Microsoft Academic Search

Analysis of anteroposterior (AP) axis specification in regenerating planarian flatworms has shown that Wnt\\/?-catenin signaling is required for posterior specification and that the FGF-like receptor molecule nou-darake (ndk) may be involved in restricting brain regeneration to anterior regions. The relationship between re-establishment of AP identity and correct morphogenesis of the brain is, however, still poorly understood. Here we report the

Marta Iglesias; Maria Almuedo-Castillo; A. Aziz Aboobaker; Emili Saló

2011-01-01

149

Analysis of the cell kinetics during planarian regeneration by means of SAMBA 200 cell image processor  

Microsoft Academic Search

The relationships between cell kinetics and nuclear transformations in regeneration were investigated in the planarianPolycelis nigra by means of image analysis. A SAMBA 200 cell image processor was used to compute densitometric, textural and morphological parameters on Feulgen-stained nuclei in the blastema and near the cut 2–96 h after decapitation. On the basis of these parameters, the phase of the

Gérard Brugal; Françoise Giround; André Gabriel

1985-01-01

150

Polarized notum Activation at Wounds Inhibits Wnt Function to Promote Planarian Head Regeneration  

Microsoft Academic Search

Regeneration requires initiation of programs tailored to the identity of missing parts. Head-versus-tail regeneration in planarians presents a paradigm for study of this phenomenon. After injury, Wnt signaling promotes tail regeneration. We report that wounding elicits expression of the Wnt inhibitor notum preferentially at anterior-facing wounds. This expression asymmetry occurs at essentially any wound, even if the anterior pole is

Christian P. Petersen; Peter W. Reddien

2011-01-01

151

Distinct structural domains in the planarian brain defined by the expression of evolutionarily conserved homeobox genes  

Microsoft Academic Search

Homeobox genes such as orthodenticle in Drosophila and its mouse homologues, Otx1 and Otx2, are known to be essential for rostral brain development. To investigate the molecular basis of brain evolution, we searched\\u000a for otd\\/Otx-related homeobox genes in the planarian Dugesia japonica, and identified two genes, DjotxA and B, whose expression appears to be restricted to the cephalic ganglion (brain).

Y. Umesono; Kenji Watanabe; K. Agata

1999-01-01

152

Molecular characterization of the glucose-regulated protein 78 (GRP78) gene in planarian Dugesia japonica.  

PubMed

GRP78 (78 kDa glucose-regulated protein) has ubiquitously existed in nearly all organisms from yeast to humans, reflecting the central roles it plays in cell survival. In this report, we isolated and sequenced the full-length cDNA of GRP78 (designated DjGRP78) from the planarian Dugesia japonica. The cDNA is 2121 bp, including an open reading frame (ORF) of 1983 bp encoding a polypeptide of 660 amino acids with three HSP70 family signatures. DjGRP78 contains signal peptides at the N-terminus and a KTEL peptide motif at the C-terminus, which suggests that it localizes in the endoplasmic reticulum (ER). Fluorescent real time RT-PCR was employed to detect the expression pattern of Djgrp78 in response to different stressors. Our results show that heat shock and heavy metals (Hg(2+) and Pb(2+)) induce Djgrp78 expression, but starvation does not. Interestingly, we found that Djgrp78 was up-regulated in planarians with septic tissues, and also verified that it was up-regulated in response to bacterial challenge. Our data indicate that Djgrp78 may be a multifunctional gene, and play important roles in physiological and pathological stress in planarians. PMID:24632484

Ma, Ke-Xue; Chen, Guang-Wen; Shi, Chang-Ying; Cheng, Fang-Fang; Dou, He; Feng, Cheng-Cheng; Liu, De-Zeng

2014-05-01

153

Gap junction proteins: master regulators of the planarian stem cell response to tissue maintenance and injury.  

PubMed

Gap junction (GJ) proteins are crucial mediators of cell-cell communication during embryogenesis, tissue regeneration and disease. GJ proteins form plasma membrane channels that facilitate passage of small molecules across cells and modulate signaling pathways and cellular behavior in different tissues. These properties have been conserved throughout evolution, and in most invertebrates GJ proteins are known as innexins. Despite their critical relevance for physiology and disease, the mechanisms by which GJ proteins modulate cell behavior are poorly understood. This review summarizes findings from recent work that uses planarian flatworms as a paradigm to analyze GJ proteins in the complexity of the whole organism. The planarian model allows access to a large pool of adult somatic stem cells (known as neoblasts) that support physiological cell turnover and tissue regeneration. Innexin proteins are present in planarians and play a fundamental role in controlling neoblast behavior. We discuss the possibility that GJ proteins participate as cellular sensors that inform neoblasts about local and systemic physiological demands. We believe that functional analyses of GJ proteins will bring a complementary perspective to studies that focus on the temporal expression of genes. Finally, integrating functional studies along with molecular genetics and epigenetic approaches would expand our understanding of cellular regulation in vivo and greatly enhance the possibilities for rationally modulating stem cell behavior in their natural environment. This article is part of a Special Issue entitled: The communicating junctions, roles and dysfunctions. PMID:22450236

Peiris, T Harshani; Oviedo, Néstor J

2013-01-01

154

TORC1 is required to balance cell proliferation and cell death in planarians.  

PubMed

Multicellular organisms are equipped with cellular mechanisms that enable them to replace differentiated cells lost to normal physiological turnover, injury, and for some such as planarians, even amputation. This process of tissue homeostasis is generally mediated by adult stem cells (ASCs), tissue-specific stem cells responsible for maintaining anatomical form and function. To do so, ASCs must modulate the balance between cell proliferation, i.e. in response to nutrients, and that of cell death, i.e. in response to starvation or injury. But how these two antagonistic processes are coordinated remains unclear. Here, we explore the role of the core components of the TOR pathway during planarian tissue homeostasis and regeneration and identified an essential function for TORC1 in these two processes. RNAi-mediated silencing of TOR in intact animals resulted in a significant increase in cell death, whereas stem cell proliferation and stem cell maintenance were unaffected. Amputated animals failed to increase stem cell proliferation after wounding and displayed defects in tissue remodeling. Together, our findings suggest two distinct roles for TORC1 in planarians. TORC1 is required to modulate the balance between cell proliferation and cell death during normal cell turnover and in response to nutrients. In addition, it is required to initiate appropriate stem cell proliferation during regeneration and for proper tissue remodeling to occur to maintain scale and proportion. PMID:22445864

Tu, Kimberly C; Pearson, Bret J; Sánchez Alvarado, Alejandro

2012-05-15

155

A comparative transcriptomic analysis reveals conserved features of stem cell pluripotency in planarians and mammals.  

PubMed

Many long-lived species of animals require the function of adult stem cells throughout their lives. However, the transcriptomes of stem cells in invertebrates and vertebrates have not been compared, and consequently, ancestral regulatory circuits that control stem cell populations remain poorly defined. In this study, we have used data from high-throughput RNA sequencing to compare the transcriptomes of pluripotent adult stem cells from planarians with the transcriptomes of human and mouse pluripotent embryonic stem cells. From a stringently defined set of 4,432 orthologs shared between planarians, mice and humans, we identified 123 conserved genes that are ?5-fold differentially expressed in stem cells from all three species. Guided by this gene set, we used RNAi screening in adult planarians to discover novel stem cell regulators, which we found to affect the stem cell-associated functions of tissue homeostasis, regeneration, and stem cell maintenance. Examples of genes that disrupted these processes included the orthologs of TBL3, PSD12, TTC27, and RACK1. From these analyses, we concluded that by comparing stem cell transcriptomes from diverse species, it is possible to uncover conserved factors that function in stem cell biology. These results provide insights into which genes comprised the ancestral circuitry underlying the control of stem cell self-renewal and pluripotency. PMID:22696458

Labbé, Roselyne M; Irimia, Manuel; Currie, Ko W; Lin, Alexander; Zhu, Shu Jun; Brown, David D R; Ross, Eric J; Voisin, Veronique; Bader, Gary D; Blencowe, Benjamin J; Pearson, Bret J

2012-08-01

156

Restoration of anterior regeneration in a planarian with limited regenerative ability.  

PubMed

Variability of regenerative potential among animals has long perplexed biologists. On the basis of their exceptional regenerative abilities, planarians have become important models for understanding the molecular basis of regeneration. However, planarian species with limited regenerative abilities are also found. Despite the importance of understanding the differences between closely related, regenerating and non-regenerating organisms, few studies have focused on the evolutionary loss of regeneration, and the molecular mechanisms leading to such regenerative loss remain obscure. Here we examine Procotyla fluviatilis, a planarian with restricted ability to replace missing tissues, using next-generation sequencing to define the gene expression programs active in regeneration-permissive and regeneration-deficient tissues. We found that Wnt signalling is aberrantly activated in regeneration-deficient tissues. Notably, downregulation of canonical Wnt signalling in regeneration-deficient regions restores regenerative abilities: blastemas form and new heads regenerate in tissues that normally never regenerate. This work reveals that manipulating a single signalling pathway can reverse the evolutionary loss of regenerative potential. PMID:23883929

Sikes, James M; Newmark, Phillip A

2013-08-01

157

The in vivo effect of chelidonine on the stem cell system of planarians.  

PubMed

The presence of adult pluripotent stem cells and the amazing regenerative capabilities make planarian flatworms an extraordinary experimental model to assess in vivo the effects of substances of both natural and synthetic origin on stem cell dynamics. This study focuses on the effects of chelidonine, an alkaloid obtained from Chelidonium majus. The expression levels of molecular markers specific for stem or differentiated cells were compared in chelidonine-treated and control planarians. The use of these markers demonstrates that chelidonine produces in vivo a significant anti-proliferative effect on planarian stem cells in a dose-dependent fashion. In response to chelidonine treatment mitotic abnormalities were also observed and the number of cells able to proceed to anaphase/telophase appeared significantly reduced with respect to the controls. Our results support the possibility that chelidonine acts on cell cycle progression by inhibition of tubulin polymerization. These studies provide a basis for preclinical evaluation in vivo of the effects of chelidonine on physiologically proliferating stem cells. PMID:22503932

Isolani, Maria Emilia; Pietra, Daniele; Balestrini, Linda; Borghini, Alice; Deri, Paolo; Imbriani, Marcello; Bianucci, Anna Maria; Batistoni, Renata

2012-07-01

158

Identification of small non-coding RNAs in the planarian Dugesia japonica via deep sequencing.  

PubMed

Freshwater planarian flatworm possesses an extraordinary ability to regenerate lost body parts after amputation; it is perfect organism model in regeneration and stem cell biology. Recently, small RNAs have been an increasing concern and studied in many aspects, including regeneration and stem cell biology, among others. In the current study, the large-scale cloning and sequencing of sRNAs from the intact and regenerative planarian Dugesia japonica are reported. Sequence analysis shows that sRNAs between 18nt and 40nt are mainly microRNAs and piRNAs. In addition, 209 conserved miRNAs and 12 novel miRNAs are identified. Especially, a better screening target method, negative-correlation relationship of miRNAs and mRNA, is adopted to improve target prediction accuracy. Similar to miRNAs, a diverse population of piRNAs and changes in the two samples are also listed. The present study is the first to report on the important role of sRNAs during planarian Dugesia japonica regeneration. PMID:22425900

Qin, Yun-Fei; Zhao, Jin-Mei; Bao, Zhen-Xia; Zhu, Zhao-Yu; Mai, Jia; Huang, Yi-Bo; Li, Jian-Biao; Chen, Ge; Lu, Ping; Chen, San-Jun; Su, Lin-Lin; Fang, Hui-Min; Lu, Ji-Ke; Zhang, Yi-Zhe; Zhang, Shou-Tao

2012-05-01

159

The use of planarians as in vivo animal model to study laser biomodulation effects  

NASA Astrophysics Data System (ADS)

A variety of effects is attributed to the photo stimulation of tissues, such as improved healing of ulcers, analgesic and anti-inflammatory effects, stimulation of the proliferation of cells of different origins and stimulation of bone repair. Some investigations that make qualitative evaluations, like wound healing and evaluation of pain and edema, can be conducted in human subjects. However, deeper investigations on the mechanisms of action of the light stimulus and other quantitative works that requires biopsies or destructive analysis has to be carried out in animal models or in cell cultures. In this work, we propose the use of planarians as a model to study laser-tissue interaction. Contrasting with cell cultures and unicellular organisms, planarians are among the simplest organism having tissue layers, central nerve system, digestive and excretory system that might have been platforms for the evolution of the complex and highly organized tissues and organs found in higher organisms. For the present study, 685 nm laser radiation was employed. Planarians were cut transversally, in a plane posterior to the auricles. The body fragments were left to regenerate and the proliferation dynamics of stem cells was studied by using histological analysis. Maximum cell count was obtained for the laser treated group at the 4 th experimental day. At that experimental time, we also had the largest difference between the irradiated and the non-irradiated control group. We concluded that the studied flatworm could be an interesting animal model for in vivo studies of laser-tissue interactions.

Munin, Egberto; Garcia, Neila Maria Rocha; Braz, Allison Gustavo; de Souza, Sandra Cristina; Alves, Leandro Procópio; Salgado, Miguel Angel Castillo; Pilla, Viviane

2007-02-01

160

Stem cell-based growth, regeneration, and remodeling of the planarian intestine  

PubMed Central

Although some animals are capable of regenerating organs, the mechanisms by which this is achieved are poorly understood. In planarians, pluripotent somatic stem cells called neoblasts supply new cells for growth, replenish tissues in response to cellular turnover, and regenerate tissues after injury. For most tissues and organs, however, the spatiotemporal dynamics of stem cell differentiation and the fate of tissue that existed prior to injury have not been characterized systematically. Utilizing in vivo imaging and bromodeoxyuridine pulse-chase experiments, we have analyzed growth and regeneration of the planarian intestine, the organ responsible for digestion and nutrient distribution. During growth, we observe that new gut branches are added along the entire anteroposterior axis. We find that new enterocytes differentiate throughout the intestine rather than in specific growth zones, suggesting that branching morphogenesis is achieved primarily by remodeling of differentiated intestinal tissues. During regeneration, we also demonstrate a previously unappreciated degree of intestinal remodeling, in which pre-existing posterior gut tissue contributes extensively to the newly formed anterior gut, and vice versa. By contrast to growing animals, differentiation of new intestinal cells occurs at preferential locations, including within newly generated tissue (the blastema), and along pre-existing intestinal branches undergoing remodeling. Our results indicate that growth and regeneration of the planarian intestine are achieved by coordinated differentiation of stem cells and the remodeling of pre-existing tissues. Elucidation of the mechanisms by which these processes are integrated will be critical for understanding organogenesis in a post-embryonic context. PMID:21664348

Forsthoefel, David J.; Park, Amanda E.; Newmark, Phillip A.

2011-01-01

161

PIWI homologs mediate Histone H4 mRNA localization to planarian chromatoid bodies  

PubMed Central

The well-known regenerative abilities of planarian flatworms are attributed to a population of adult stem cells called neoblasts that proliferate and differentiate to produce all cell types. A characteristic feature of neoblasts is the presence of large cytoplasmic ribonucleoprotein granules named chromatoid bodies, the function of which has remained largely elusive. This study shows that histone mRNAs are a common component of chromatoid bodies. Our experiments also demonstrate that accumulation of histone mRNAs, which is typically restricted to the S phase of eukaryotic cells, is extended during the cell cycle of neoblasts. The planarian PIWI homologs SMEDWI-1 and SMEDWI-3 are required for proper localization of germinal histone H4 (gH4) mRNA to chromatoid bodies. The association between histone mRNA and chromatoid body components extends beyond gH4 mRNA, since transcripts of other core histone genes were also found in these structures. Additionally, piRNAs corresponding to loci of every core histone type have been identified. Altogether, this work provides evidence that links PIWI proteins and chromatoid bodies to histone mRNA regulation in planarian stem cells. The molecular similarities between neoblasts and undifferentiated cells of other organisms raise the possibility that PIWI proteins might also regulate histone mRNAs in stem cells and germ cells of other metazoans. PMID:24903754

Rouhana, Labib; Weiss, Jennifer A.; King, Ryan S.; Newmark, Phillip A.

2014-01-01

162

Insights into the origin and distribution of biodiversity in the Brazilian Atlantic forest hot spot: a statistical phylogeographic study using a low-dispersal organism.  

PubMed

The relative importance of the processes that generate and maintain biodiversity is a major and controversial topic in evolutionary biology with large implications for conservation management. The Atlantic Forest of Brazil, one of the world's richest biodiversity hot spots, is severely damaged by human activities. To formulate an efficient conservation policy, a good understanding of spatial and temporal biodiversity patterns and their underlying evolutionary mechanisms is required. With this aim, we performed a comprehensive phylogeographic study using a low-dispersal organism, the land planarian species Cephaloflexa bergi (Platyhelminthes, Tricladida). Analysing multi-locus DNA sequence variation under the Approximate Bayesian Computation framework, we evaluated two scenarios proposed to explain the diversity of Southern Atlantic Forest (SAF) region. We found that most sampled localities harbour high levels of genetic diversity, with lineages sharing common ancestors that predate the Pleistocene. Remarkably, we detected the molecular hallmark of the isolation-by-distance effect and little evidence of a recent colonization of SAF localities; nevertheless, some populations might result from very recent secondary contacts. We conclude that extant SAF biodiversity originated and has been shaped by complex interactions between ancient geological events and more recent evolutionary processes, whereas Pleistocene climate changes had a minor influence in generating present-day diversity. We also demonstrate that land planarians are an advantageous biological model for making phylogeographic and, particularly, fine-scale evolutionary inferences, and propose appropriate conservation policies. PMID:24549112

Álvarez-Presas, M; Sánchez-Gracia, A; Carbayo, F; Rozas, J; Riutort, M

2014-06-01

163

An automated training paradigm reveals long-term memory in planarians and its persistence through head regeneration.  

PubMed

Planarian flatworms are a popular system for research into the molecular mechanisms that enable these complex organisms to regenerate their entire body, including the brain. Classical data suggest that they may also be capable of long-term memory. Thus, the planarian system may offer the unique opportunity to study brain regeneration and memory in the same animal. To establish a system for the investigation of the dynamics of memory in a regenerating brain, we developed a computerized training and testing paradigm that avoided the many issues that confounded previous, manual attempts to train planarians. We then used this new system to train flatworms in an environmental familiarization protocol. We show that worms exhibit environmental familiarization, and that this memory persists for at least 14 days - long enough for the brain to regenerate. We further show that trained, decapitated planarians exhibit evidence of memory retrieval in a savings paradigm after regenerating a new head. Our work establishes a foundation for objective, high-throughput assays in this molecularly tractable model system that will shed light on the fundamental interface between body patterning and stored memories. We propose planarians as key emerging model species for mechanistic investigations of the encoding of specific memories in biological tissues. Moreover, this system is lik ely to have important implications for the biomedicine of stem-cell-derived treatments of degenerative brain disorders in human adults. PMID:23821717

Shomrat, Tal; Levin, Michael

2013-10-15

164

Smed-dynA-1 is a planarian nervous system specific dynamin 1 homolog required for normal locomotion  

PubMed Central

ABSTRACT Dynamins are GTPases that are required for separation of vesicles from the plasma membrane and thus are key regulators of endocytosis in eukaryotic cells. This role for dynamin proteins is especially crucial for the proper function of neurons, where they ensure that synaptic vesicles and their neurotransmitter cargo are recycled in the presynaptic cell. Here we have characterized the dynamin protein family in the freshwater planarian Schmidtea mediterranea and showed that it possesses six dynamins with tissue specific expression profiles. Of these six planarian homologs, two are necessary for normal tissue homeostasis, and the loss of another, Smed-dynA-1, leads to an abnormal behavioral phenotype, which we have quantified using automated center of mass tracking. Smed-dynA-1 is primarily expressed in the planarian nervous system and is a functional homolog of the mammalian Dynamin I. The distinct expression profiles of the six dynamin genes makes planarians an interesting new system to reveal novel dynamin functions, which may be determined by their differential tissue localization. The observed complexity of neurotransmitter regulation combined with the tools of quantitative behavioral assays as a functional readout for neuronal activity, renders planarians an ideal system for studying how the nervous system controls behavior. PMID:24950970

Talbot, Jared A.; Currie, Ko W.; Pearson, Bret J.; Collins, Eva-Maria S.

2014-01-01

165

Platyhelminth Venom Allergen-Like (VAL) proteins: revealing structural diversity, class-specific features and biological associations across the phylum.  

PubMed

During platyhelminth infection, a cocktail of proteins is released by the parasite to aid invasion, initiate feeding, facilitate adaptation and mediate modulation of the host immune response. Included amongst these proteins is the Venom Allergen-Like (VAL) family, part of the larger sperm coating protein/Tpx-1/Ag5/PR-1/Sc7 (SCP/TAPS) superfamily. To explore the significance of this protein family during Platyhelminthes development and host interactions, we systematically summarize all published proteomic, genomic and immunological investigations of the VAL protein family to date. By conducting new genomic and transcriptomic interrogations to identify over 200 VAL proteins (228) from species in all 4 traditional taxonomic classes (Trematoda, Cestoda, Monogenea and Turbellaria), we further expand our knowledge related to platyhelminth VAL diversity across the phylum. Subsequent phylogenetic and tertiary structural analyses reveal several class-specific VAL features, which likely indicate a range of roles mediated by this protein family. Our comprehensive analysis of platyhelminth VALs represents a unifying synopsis for understanding diversity within this protein family and a firm context in which to initiate future functional characterization of these enigmatic members. PMID:22717097

Chalmers, Iain W; Hoffmann, Karl F

2012-09-01

166

Smithsoniarhynches, a new genus of interstitial Gnathorhynchidae (Platyhelminthes: Kalyptorhynchia) from Mosquito Lagoon and Indian River Lagoon, Florida  

Microsoft Academic Search

A new genus of marine, interstitial schizorhynch (Platyhelminthes: Kalyptorhynchia) is described from sediment collected in Mosquito Lagoon and Indian River Lagoon, Florida, USA. Smithsoniarhynches is char- acterized by the presence of proboscis hooks constructed of ten individual spine-like teeth that emerge separately from a basal plate. Histology and confocal laser scanning microscopy are used to reveal addi- tional details of

Rick Hochberg

2004-01-01

167

Suppression of the tapeworm order Pseudophyllidea (Platyhelminthes: Eucestoda) and the proposal of two new orders, Bothriocephalidea and Diphyllobothriidea  

Microsoft Academic Search

Pseudophyllidea van Beneden in Carus, 1863, a well recognised order of tapeworms (Platyhelminthes: Eucestoda), is suppressed because it is composed of two phylogenetically unrelated groups, for which the new names Bothriocephalidea and Diphyllobothriidea are proposed. The new orders differ from each other in the following characters: (i) position of the genital pore: on the dorsal, dorso-lateral or lateral aspects and

R. Kuchta; T. Scholz; J. Brabec; R. A. Bray

2008-01-01

168

Whole-mount in situ hybridization using DIG-labeled probes in planarian.  

PubMed

In recent years freshwater flatworms (planarian) have become a powerful model for studies of regeneration and stem cell biology. Whole-mount in situ hybridization (WISH) and fluorescent in situ hybridization (FISH) are key and most commonly used techniques to determine and visualize gene expression patterns in planaria. Here, we present the established version of whole-mount in situ hybridization (WISH) and whole-mount fluorescence in situ hybridization (WFISH) protocol optimized over the last years by several labs from the rapidly growing planaria field and give an overview of recently introduced modifications which can be critical in the study of low abundant transcripts. PMID:25218375

Rybak-Wolf, Agnieszka; Solana, Jordi

2014-01-01

169

?-Catenin-Dependent Control of Positional Information along the AP Body Axis in Planarians Involves a Teashirt Family Member.  

PubMed

Wnt/?-catenin signaling regulates tissue homeostasis and regeneration in metazoans. In planarians-flatworms with high regenerative potential-Wnt ligands are thought to control tissue polarity by shaping a ?-catenin activity gradient along the anterior-posterior axis, yet the downstream mechanisms are poorly understood. We performed an RNA sequencing (RNA-seq)-based screen and identified hundreds of ?-catenin-dependent transcripts, of which several were expressed in muscle tissue and stem cells in a graded fashion. In particular, a teashirt (tsh) ortholog was induced in a ?-catenin-dependent manner during regeneration in planarians and zebrafish, and RNAi resulted in two-headed planarians. Strikingly, intact planarians depleted of tsh induced anterior markers and slowly transformed their tail into a head, reminiscent of ?-catenin RNAi phenotypes. Given that ?-catenin RNAi enhanced the formation of muscle cells expressing anterior determinants in tail regions, our study suggests that this pathway controls tissue polarity through regulating the identity of differentiating cells during homeostasis and regeneration. PMID:25558068

Reuter, Hanna; März, Martin; Vogg, Matthias C; Eccles, David; Grífol-Boldú, Laura; Wehner, Daniel; Owlarn, Suthira; Adell, Teresa; Weidinger, Gilbert; Bartscherer, Kerstin

2015-01-13

170

Transcriptome profiling and digital gene expression by deep-sequencing in normal\\/regenerative tissues of planarian Dugesia japonica  

Microsoft Academic Search

Planarians exhibit an extraordinary ability to regenerate lost body parts which is attributed to an abundance of pluripotent somatic stem cells called neoblasts. In this article, we report a transcriptome sequence of a Planaria subspecies Dugesia japonica derived by high-throughput sequencing. In addition, we researched transcriptome changes during different periods of regeneration by using a tag-based digital gene expression (DGE)

Yun-Fei Qin; Hui-Min Fang; Qing-Nan Tian; Zhen-Xia Bao; Ping Lu; Jin-Mei Zhao; Jia Mai; Zhao-Yu Zhu; Lin-Lin Shu; Li Zhao; San-Jun Chen; Feng Liang; Yi-Zhe Zhang; Shou-Tao Zhang

2011-01-01

171

Planarian yorkie/YAP functions to integrate adult stem cell proliferation, organ homeostasis and maintenance of axial patterning.  

PubMed

During adult homeostasis and regeneration, the freshwater planarian must accomplish a constant balance between cell proliferation and cell death, while also maintaining proper tissue and organ size and patterning. How these ordered processes are precisely modulated remains relatively unknown. Here we show that planarians use the downstream effector of the Hippo signaling cascade, yorkie (yki; YAP in vertebrates) to control a diverse set of pleiotropic processes in organ homeostasis, stem cell regulation, regeneration and axial patterning. We show that yki functions to maintain the homeostasis of the planarian excretory (protonephridial) system and to limit stem cell proliferation, but does not affect the differentiation process or cell death. Finally, we show that Yki acts synergistically with WNT/?-catenin signaling to repress head determination by limiting the expression domains of posterior WNT genes and that of the WNT-inhibitor notum. Together, our data show that yki is a key gene in planarians that integrates stem cell proliferation control, organ homeostasis, and the spatial patterning of tissues. PMID:24523458

Lin, Alexander Y T; Pearson, Bret J

2014-03-01

172

Relationship between variations of cAMP, neuromediators and the stimulation of nucleic acid synthesis during planarian (Polycelis tenuis) regeneration  

Microsoft Academic Search

Regenerating planarians of the species Polycelis tenuis have been studied with respect to the two distinct phases which occur during regeneration, viz., the first 24 h involving cellular activation, and the following days when differentiation of the blastema occurs after a period of cellular proliferation. We have studied particularly the biochemical events that control regeneration with respect to the nature

Isabelle Martelly; Raphael Franquinet; Albert Le Moigne

1981-01-01

173

The freshwater planarian Polycelis felina as a sensitive species to assess the long-term toxicity of ammonia.  

PubMed

Behavioural endpoints are a good link between physiological and ecological effects. However long-term behavioural endpoints are not uniformly studied over all different organism groups. For example behaviour has been scarcely studied in planarians. Unionized ammonia (NH(3)) is one of the most widespread pollutants in developed countries, and is known to alter animal behaviour. In this study a long-term (30 d) bioassay was conducted to assess the effect of this pollutant on survival and behavioural activity (e.g. locomotion activity) of the freshwater planarian Polycelis felina. One control and three environmentally-realistic concentrations of unionized ammonia (treatments of 0.02, 0.05, and 0.09 mg N-NH(3) L(-1)) were used in quintuplicate. The behaviour of planarians was measured after 0, 10, 20 and 30 d of ammonia exposure. Mortality was recorded every 2 d. Unionized ammonia increased mortality in the two highest NH(3) concentrations and the locomotory activity was depressed in all treatments after 20 d of exposure. Behavioural effect was observed at concentrations 20 times lower than the short-term LC50 for this species. Previous studies proposed safe concentrations of unionized ammonia of 0.01-0.10 mg N-NH(3) L(-1) to aquatic ecosystems, but our study has shown that these concentrations will affect planarians. Because planarians play a key role in streams (as predator/scavenger), safe concentrations should be below 0.02 mg N-NH(3) L(-1) to protect this species in the freshwater community. Our results can contribute to improve the knowledge about ammonia toxicity to freshwater ecosystems, we recommend that safe concentrations of unionized ammonia should be based on very sensitive species. PMID:21546058

Alonso, Alvaro; Camargo, Julio A

2011-07-01

174

COE loss-of-function analysis reveals a genetic program underlying maintenance and regeneration of the nervous system in planarians.  

PubMed

Members of the COE family of transcription factors are required for central nervous system (CNS) development. However, the function of COE in the post-embryonic CNS remains largely unknown. An excellent model for investigating gene function in the adult CNS is the freshwater planarian. This animal is capable of regenerating neurons from an adult pluripotent stem cell population and regaining normal function. We previously showed that planarian coe is expressed in differentiating and mature neurons and that its function is required for proper CNS regeneration. Here, we show that coe is essential to maintain nervous system architecture and patterning in intact (uninjured) planarians. We took advantage of the robust phenotype in intact animals to investigate the genetic programs coe regulates in the CNS. We compared the transcriptional profiles of control and coe RNAi planarians using RNA sequencing and identified approximately 900 differentially expressed genes in coe knockdown animals, including 397 downregulated genes that were enriched for nervous system functional annotations. Next, we validated a subset of the downregulated transcripts by analyzing their expression in coe-deficient planarians and testing if the mRNAs could be detected in coe+ cells. These experiments revealed novel candidate targets of coe in the CNS such as ion channel, neuropeptide, and neurotransmitter genes. Finally, to determine if loss of any of the validated transcripts underscores the coe knockdown phenotype, we knocked down their expression by RNAi and uncovered a set of coe-regulated genes implicated in CNS regeneration and patterning, including orthologs of sodium channel alpha-subunit and pou4. Our study broadens the knowledge of gene expression programs regulated by COE that are required for maintenance of neural subtypes and nervous system architecture in adult animals. PMID:25356635

Cowles, Martis W; Omuro, Kerilyn C; Stanley, Brianna N; Quintanilla, Carlo G; Zayas, Ricardo M

2014-10-01

175

COE Loss-of-Function Analysis Reveals a Genetic Program Underlying Maintenance and Regeneration of the Nervous System in Planarians  

PubMed Central

Members of the COE family of transcription factors are required for central nervous system (CNS) development. However, the function of COE in the post-embryonic CNS remains largely unknown. An excellent model for investigating gene function in the adult CNS is the freshwater planarian. This animal is capable of regenerating neurons from an adult pluripotent stem cell population and regaining normal function. We previously showed that planarian coe is expressed in differentiating and mature neurons and that its function is required for proper CNS regeneration. Here, we show that coe is essential to maintain nervous system architecture and patterning in intact (uninjured) planarians. We took advantage of the robust phenotype in intact animals to investigate the genetic programs coe regulates in the CNS. We compared the transcriptional profiles of control and coe RNAi planarians using RNA sequencing and identified approximately 900 differentially expressed genes in coe knockdown animals, including 397 downregulated genes that were enriched for nervous system functional annotations. Next, we validated a subset of the downregulated transcripts by analyzing their expression in coe-deficient planarians and testing if the mRNAs could be detected in coe+ cells. These experiments revealed novel candidate targets of coe in the CNS such as ion channel, neuropeptide, and neurotransmitter genes. Finally, to determine if loss of any of the validated transcripts underscores the coe knockdown phenotype, we knocked down their expression by RNAi and uncovered a set of coe-regulated genes implicated in CNS regeneration and patterning, including orthologs of sodium channel alpha-subunit and pou4. Our study broadens the knowledge of gene expression programs regulated by COE that are required for maintenance of neural subtypes and nervous system architecture in adult animals. PMID:25356635

Cowles, Martis W.; Omuro, Kerilyn C.; Stanley, Brianna N.; Quintanilla, Carlo G.; Zayas, Ricardo M.

2014-01-01

176

Schistosoma mansoni (Platyhelminthes, Trematoda) nuclear receptors: sixteen new members and a novel subfamily.  

PubMed

Nuclear receptors (NRs) are important transcriptional modulators in metazoans. Sixteen new NRs were identified in the Platyhelminth trematode, Schistosoma mansoni. Three were found to possess novel tandem DNA-binding domains that identify a new subfamily of NR. Two NRs are homologues of the thyroid hormone receptor that previously were thought to be restricted to chordates. This study brings the total number of identified NR in S. mansoni to 21. Phylogenetic and comparative genomic analyses demonstrate that S. mansoni NRs share an evolutionary lineage with that of arthropods and vertebrates. Phylogenic analysis shows that more than half of the S. mansoni nuclear receptors evolved from a second gene duplication. As the second gene duplication of NRs was thought to be specific to vertebrates, our data challenge the current theory of NR evolution. PMID:16406405

Wu, Wenjie; Niles, Edward G; El-Sayed, Najib; Berriman, Matthew; LoVerde, Philip T

2006-02-01

177

A simple technique for staining of platyhelminths with the lactophnol cotton blue stain.  

PubMed

This paper describes a simple technique for staining of flatworms using lactophenol cotton blue (LPCB). The staining was tested on 2 trematode species: Heterophyes heterophyes and Mesostephanus appendiculatus, and one cestode: Diplopylidium acanthotetra, which were collected from the intestine of stray cats in Kuwait. The specimens were mounted in a small amount of the LPCB stain on a clean slide for 2-3 minutes before covering with a cover slip. The technique rapidly and clearly differentiated the internal structures of the helminthes. Its speed and simplicity are advantages over other staining methods. It is easily used in wide-scale surveys where a large number of platyhelminths have to be identified and it is suitable for field studies. PMID:24260820

Henedi, Adawia A M; El-Azazy, Osama M E

2013-08-01

178

A lophotrochozoan-specific nuclear hormone receptor is required for reproductive system development in the planarian.  

PubMed

Germ cells of sexually reproducing organisms receive an array of cues from somatic tissues that instruct developmental processes. Although the nature of these signals differs amongst organisms, the importance of germline-soma interactions is a common theme. Recently, peptide hormones from the nervous system have been shown to regulate germ cell development in the planarian Schmidtea mediterranea; thus, we sought to investigate a second class of hormones with a conserved role in reproduction, the lipophilic hormones. In order to study these signals, we identified a set of putative lipophilic hormone receptors, known as nuclear hormone receptors, and analyzed their functions in reproductive development. We found one gene, nhr-1, belonging to a small class of functionally uncharacterized lophotrochozoan-specific receptors, to be essential for the development of differentiated germ cells. Upon nhr-1 knockdown, germ cells in the testes and ovaries fail to mature, and remain as undifferentiated germline stem cells. Further analysis revealed that nhr-1 mRNA is expressed in the accessory reproductive organs and is required for their development, suggesting that this transcription factor functions cell non-autonomously in regulating germ cell development. Our studies identify a role for nuclear hormone receptors in planarian reproductive maturation and reinforce the significance of germline-soma interactions in sexual reproduction across metazoans. PMID:25278423

Tharp, Marla E; Collins, James J; Newmark, Phillip A

2014-12-01

179

PBX/extradenticle is required to re-establish axial structures and polarity during planarian regeneration.  

PubMed

Recent advances in a number of systems suggest many genes involved in orchestrating regeneration are redeployed from similar processes in development, with others being novel to the regeneration process in particular lineages. Of particular importance will be understanding the architecture of regenerative genetic regulatory networks and whether they are conserved across broad phylogenetic distances. Here, we describe the role of the conserved TALE class protein PBX/Extradenticle in planarians, a representative member of the Lophotrocozoa. PBX/Extradenticle proteins play central roles in both embryonic and post-embryonic developmental patterning in both vertebrates and insects, and we demonstrate a broad requirement during planarian regeneration. We observe that Smed-pbx has pleiotropic functions during regeneration, with a primary role in patterning the anterior-posterior (AP) axis and AP polarity. Smed-pbx is required for expression of polarity determinants notum and wnt1 and for correct patterning of the structures polarized along the AP axis, such as the brain, pharynx and gut. Overall, our data suggest that Smed-pbx functions as a central integrator of positional information to drive patterning of regeneration along the body axis. PMID:23318635

Blassberg, Robert A; Felix, Daniel A; Tejada-Romero, Belen; Aboobaker, A Aziz

2013-02-01

180

Prohibitin 2 regulates cell proliferation and mitochondrial cristae morphogenesis in planarian stem cells.  

PubMed

Prohibitins are pleiotropic proteins, whose multiple roles are emerging as key elements in the regulation of cell survival and proliferation. Indeed, prohibitins interact with several intracellular proteins strategically involved in the regulation of cell cycle progression in response to extracellular growth signals. Prohibitins also have regulatory functions in mitochondrial fusion and cristae morphogenesis, phenomena related to the ability of self-renewing embryonic stem cells to undergo differentiation, during which mitochondria develop numerous cristae, increase in number, and generate an extensive reticular network. We recently identified a Prohibitin 2 homolog (DjPhb2) that is expressed in adult stem cells (neoblasts) of planarians, a well-known model system for in vivo studies on stem cells and tissue regeneration. Here, we show that in DjPhb2 silenced planarians, most proliferating cells disappear, with the exception of a subpopulation of neoblasts localized along the dorsal body midline. Neoblast depletion impairs regeneration and, finally, leads animals to death. Our in vivo findings demonstrate that prohibitin 2 plays an important role in regulating stem cell biology, being involved in both the control of cell cycle progression and mitochondrial cristae morphogenesis. PMID:24974103

Rossi, Leonardo; Bonuccelli, Lucia; Iacopetti, Paola; Evangelista, Monica; Ghezzani, Claudio; Tana, Luigi; Salvetti, Alessandra

2014-12-01

181

Identification of neoblast- and regeneration-specific miRNAs in the planarian Schmidtea mediterranea.  

PubMed

In recent years, the planarian Schmidtea mediterranea has emerged as a tractable model system to study stem cell biology and regeneration. MicroRNAs are small RNA species that control gene expression by modulating translational repression and mRNA stability and have been implicated in the regulation of various cellular processes. Though recent studies have identified several miRNAs in S. mediterranea, their expression in neoblast subpopulations and during regeneration has not been examined. Here, we identify several miRNAs whose expression is enriched in different neoblast subpopulations and in regenerating tissue at different time points in S. mediterranea. Some of these miRNAs were enriched within 3 h post-amputation and may, therefore, play a role in wound healing and/or neoblast migration. Our results also revealed miRNAs, such as sme-miR-2d-3p and the sme-miR-124 family, whose expression is enriched in the cephalic ganglia, are also expressed in the brain primordium during CNS regeneration. These results provide new insight into the potential biological functions of miRNAs in neoblasts and regeneration in planarians. PMID:23974438

Sasidharan, Vidyanand; Lu, Yi-Chien; Bansal, Dhiru; Dasari, Pranavi; Poduval, Deepak; Seshasayee, Aswin; Resch, Alissa M; Graveley, Brenton R; Palakodeti, Dasaradhi

2013-10-01

182

Proteomic profiling of the planarian Schmidtea mediterranea and its mucous reveals similarities with human secretions and those predicted for parasitic flatworms.  

PubMed

The freshwater planarian Schmidtea mediterranea has been used in research for over 100 years, and is an emerging stem cell model because of its capability of regenerating large portions of missing body parts. Exteriorly, planarians are covered in mucous secretions of unknown composition, implicated in locomotion, predation, innate immunity, and substrate adhesion. Although the planarian genome has been sequenced, it remains mostly unannotated, challenging both genomic and proteomic analyses. The goal of the current study was to annotate the proteome of the whole planarian and its mucous fraction. The S. mediterranea proteome was analyzed via mass spectrometry by using multidimensional protein identification technology with whole-worm tryptic digests. By using a proteogenomics approach, MS data were searched against an in silico translated planarian transcript database, and by using the Swiss-Prot BLAST algorithm to identify proteins similar to planarian queries. A total of 1604 proteins were identified. The mucous subproteome was defined through analysis of a mucous trail fraction and an extract obtained by treating whole worms with the mucolytic agent N-acetylcysteine. Gene Ontology analysis confirmed that the mucous fractions were enriched with secreted proteins. The S. mediterranea proteome is highly similar to that predicted for the trematode Schistosoma mansoni associated with intestinal schistosomiasis, with the mucous subproteome particularly highly conserved. Remarkably, orthologs of 119 planarian mucous proteins are present in human mucosal secretions and tear fluid. We suggest planarians have potential to be a model system for the characterization of mucous protein function and relevant to parasitic flatworm infections and diseases underlined by mucous aberrancies, such as cystic fibrosis, asthma, and other lung diseases. PMID:22653920

Bocchinfuso, Donald G; Taylor, Paul; Ross, Eric; Ignatchenko, Alex; Ignatchenko, Vladimir; Kislinger, Thomas; Pearson, Bret J; Moran, Michael F

2012-09-01

183

Analysis of planarian Adh3 supports an intron-rich architecture and tissue-specific expression for the urbilaterian ancestral form  

Microsoft Academic Search

The alcohol dehydrogenase class 3 enzyme (ADH3) is the presumed ancestral form of the medium-chain dehydrogenase-reductase ADH family. This enzyme has been involved in formaldehyde and nitric oxide metabolism of a variety of deuterostomes and ecdysozoan protostomes. We have now characterized the structure and expression of the Adh3 gene in the lophotrochozoan Schmidtea mediterranea, a freshwater planarian. The planarian gene

Laura Godoy; Roser Gonzàlez-Duarte; Ricard Albalat

2007-01-01

184

Proteomic Profiling of the Planarian Schmidtea mediterranea and Its Mucous Reveals Similarities with Human Secretions and Those Predicted for Parasitic Flatworms*  

PubMed Central

The freshwater planarian Schmidtea mediterranea has been used in research for over 100 years, and is an emerging stem cell model because of its capability of regenerating large portions of missing body parts. Exteriorly, planarians are covered in mucous secretions of unknown composition, implicated in locomotion, predation, innate immunity, and substrate adhesion. Although the planarian genome has been sequenced, it remains mostly unannotated, challenging both genomic and proteomic analyses. The goal of the current study was to annotate the proteome of the whole planarian and its mucous fraction. The S. mediterranea proteome was analyzed via mass spectrometry by using multidimensional protein identification technology with whole-worm tryptic digests. By using a proteogenomics approach, MS data were searched against an in silico translated planarian transcript database, and by using the Swiss-Prot BLAST algorithm to identify proteins similar to planarian queries. A total of 1604 proteins were identified. The mucous subproteome was defined through analysis of a mucous trail fraction and an extract obtained by treating whole worms with the mucolytic agent N-acetylcysteine. Gene Ontology analysis confirmed that the mucous fractions were enriched with secreted proteins. The S. mediterranea proteome is highly similar to that predicted for the trematode Schistosoma mansoni associated with intestinal schistosomiasis, with the mucous subproteome particularly highly conserved. Remarkably, orthologs of 119 planarian mucous proteins are present in human mucosal secretions and tear fluid. We suggest planarians have potential to be a model system for the characterization of mucous protein function and relevant to parasitic flatworm infections and diseases underlined by mucous aberrancies, such as cystic fibrosis, asthma, and other lung diseases. PMID:22653920

Bocchinfuso, Donald G.; Taylor, Paul; Ross, Eric; Ignatchenko, Alex; Ignatchenko, Vladimir; Kislinger, Thomas; Pearson, Bret J.; Moran, Michael F.

2012-01-01

185

The evolution of life-history traits in parasitic and free-living platyhelminthes: a new perspective  

Microsoft Academic Search

Parasite life histories have been assumed to be shaped by their particular mode of existence. To test this hypothesis, we\\u000a investigate the relationships between life-history traits of free-living and parasitic platyhelminthes. Using phylogenetically\\u000a independent contrasts we examine patterns of interspecific covariation in adult size, progeny volume, daily fecundity, total\\u000a reproductive capacity, age at first reproduction and longevity. The correlations obtained

Sandrine Trouvé; Pierre Sasal; Joseph Jourdane; François Renaud; Serge Morand

1998-01-01

186

Paraphyly of the Pseudophyllidea (Platyhelminthes: Cestoda): Circumscription of monophyletic clades based on phylogenetic analysis of ribosomal RNA  

Microsoft Academic Search

Phylogenetic relationships of cestodes of the order Pseudophyllidea (Platyhelminthes: Cestoda) were examined using sequences of complete small subunit and partial (D1-D3 region) large subunit nuclear rDNA of members of all pseudophyllidean families. The results provide evidence of paraphyly of the order as indicated by previous molecular phylogenetic analyses based on a much lower number of species sequenced. Pseudophyllidean tapeworms represent

J. Brabec; R. Kuchta; T. Scholz

2006-01-01

187

Evolution of ITS1 rDNA in the Digenea (Platyhelminthes: Trematoda): 3? End Sequence Conservation and Its Phylogenetic Utility  

Microsoft Academic Search

.   A comparison of ribosomal internal transcribed spacer 1 (ITS1) elements of digenetic trematodes (Platyhelminthes) including\\u000a unidentified digeneans isolated from Cyathura carinata (Crustacea: Isopoda) revealed DNA sequence similarities at more than half of the spacer at its 3? end. Primary sequence similarity\\u000a was shown to be associated with secondary structure conservation, which suggested that similarity is due to identity by

J. Hinrich G. v. d. Schulenburg; Ulrike Englisch; J.-Wolfgang Wägele

1999-01-01

188

Preparation of the planarian Schmidtea mediterranea for high-resolution histology and transmission electron microscopy.  

PubMed

The flatworm Schmidtea mediterranea is an emerging model species in fields such as stem cell biology, regeneration and evolutionary biology. Excellent molecular tools have been developed for S. mediterranea, but ultrastructural techniques have received far less attention. Processing specimens for histology and transmission electron microscopy (TEM) is notoriously idiosyncratic for particular species or specimen types. Unfortunately, however, most methods for S. mediterranea described in the literature lack numerous essential details, and those few that do provide them rely on specialized equipment that may not be readily available. Here we present an optimized protocol for ultrastructural preparation of S. mediterranea. The protocol can be completed in 6 d, much of which is 'hands-off' time. To aid with troubleshooting, we also illustrate the major effects of seemingly minor variations in fixative, buffer concentration and dehydration steps. This procedure will be useful for all planarian researchers, particularly those with relatively little experience in tissue processing. PMID:24556788

Brubacher, John L; Vieira, Ana P; Newmark, Phillip A

2014-03-01

189

Long-range Neural and Gap Junction Protein-mediated Cues Control Polarity During Planarian Regeneration  

PubMed Central

SUMMARY Having the ability to coordinate the behavior of stem cells to induce regeneration of specific large-scale structures would have far reaching consequences in the treatment of degenerative diseases, acute injury, and aging. Thus, identifying and learning to manipulate the sequential steps that determine the fate of new tissue within the overall morphogenetic program of the organism is fundamental. We identified novel early signals, mediated by the central nervous system and 3 innexin proteins, which determine the fate and axial polarity of regenerated tissue in planarians. Modulation of gap junction-dependent and neural signals specifically induces ectopic anterior regeneration blastemas in posterior and lateral wounds. These ectopic anterior blastemas differentiate new brains that establish permanent primary axes re-established during subsequent rounds of unperturbed regeneration. These data reveal powerful novel controls of pattern formation and suggest a constructive model linking nervous inputs and polarity determination in early stages of regeneration. PMID:20026026

Oviedo, Néstor J.; Morokuma, Junji; Walentek, Peter; Kema, Ido P.; Gu, Man Bock; Ahn, Joo-Myung; Hwang, Jung Shan; Gojobori, Takashi; Levin, Michael

2010-01-01

190

Toxicity profiles and solvent-toxicant interference in the planarian Schmidtea mediterranea after dimethylsulfoxide (DMSO) exposure.  

PubMed

To investigate hydrophobic test compounds in toxicological studies, solvents like dimethylsulfoxide (DMSO) are inevitable. However, using these solvents, the interpretation of test compound-induced responses can be biased. DMSO concentration guidelines are available, but are mostly based on acute exposures involving one specific toxicity endpoint. Hence, to avoid solvent-toxicant interference, we use multiple chronic test endpoints for additional interpretation of DMSO concentrations and propose a statistical model to assess possible synergistic, antagonistic or additive effects of test compounds and their solvents. In this study, the effects of both short- (1?day) and long-term (2?weeks) exposures to low DMSO concentrations (up to 1000?µl?l(-1) ) were studied in the planarian Schmidtea mediterranea. We measured different biological levels in both fully developed and developing animals. In a long-term exposure set-up, a concentration of 500?µl?l(-1) DMSO interfered with processes on different biological levels, e.g. behaviour, stem cell proliferation and gene expression profiles. After short exposure times, 500?µl?l(-1) DMSO only affected motility, whereas the most significant changes on different parameters were observed at a concentration of 1000?µl?l(-1) DMSO. As small sensitivity differences exist between biological levels and developmental stages, we advise the use of this solvent in concentrations below 500?µl?l(-1) in this organism. In the second part of our study, we propose a statistical approach to account for solvent-toxicant interactions and discuss full-scale solvent toxicity studies. In conclusion, we reassessed DMSO concentration limits for different experimental endpoints in the planarian S. mediterranea. Copyright © 2014 John Wiley & Sons, Ltd. PMID:24964768

Stevens, An-Sofie; Pirotte, Nicky; Plusquin, Michelle; Willems, Maxime; Neyens, Thomas; Artois, Tom; Smeets, Karen

2015-03-01

191

Molecular analysis of stem cells and their descendents during cell turnover and regeneration in the planarian Schmidtea mediterranea  

PubMed Central

In adult planarians the replacement of cells lost to physiological turnover or injury is sustained by the proliferation and differentiation of stem cells known as neoblasts. Neoblast lineage relationships and the molecular changes that take place during differentiation into the appropriate cell types are poorly understood. Here we report the identification and characterization of a cohort of genes specifically expressed in neoblasts and their descendents. We find that genes with severely downregulated expression after irradiation molecularly define at least three discrete subpopulations of cells. Simultaneous BrdU labeling and in situ hybridization experiments in intact and regenerating animals indicate that these cell subpopulations are related by lineage. Our data demonstrate not only the ability to measure and study the in vivo population dynamics of adult stem cells during tissue homeostasis and regeneration, but also the utility of studies in planarians to broadly inform stem cell biology in adult organisms. PMID:18786419

Eisenhoffer, George T.; Kang, Hara; Alvarado, Alejandro Sánchez

2008-01-01

192

Specific features of the planarian Dugesia tigrina regeneration and mollusk Helix albescens nociception under weak electromagnetic shielding  

NASA Astrophysics Data System (ADS)

It has been demonstrated that weak electromagnetic shielding stimulates regeneration in the planarian Dugesia tigrina, the stimulating intensity being dependent on both the initial state of the animals, which is determined by season, and their functional asymmetry. As has been shown, the effect of a weak electromagnetic field induces phasic changes in the nociceptive sensitivity of the mollusk Helix albescens: an increase in the sensitivity to a thermal stimulus is replaced by the development of the hypalgesic effect.

Temur'yants, N. A.; Demtsun, N. A.; Kostyuk, A. S.; Yarmolyuk, N. S.

2012-12-01

193

Transgenic planarian lines obtained by electroporation using transposon-derived vectors and an eye-specific GFP marker  

Microsoft Academic Search

To generate transgenic planarians we used a set of versatile vectors for animal transgenesis based on the promiscuous transposons, mariner, Hermes and piggyBac, and a universal enhanced GFP (EGFP) marker system with three Pax6 dimeric binding sites, the 3xP3-EGFP developed by Berghammer et al. [Berghammer, A. J., Klinger, M. & Wimmer, E. A. (1999) Nature 402, 370-371]. This marker is

C. González-Estévez; T. Momose; W. J. Gehring; E. Saló

2003-01-01

194

Detection of apoptosis during planarian regeneration by the expression of apoptosis-related genes and TUNEL assay  

Microsoft Academic Search

Apoptosis is a tightly organized cell death process that plays a crucial role in metazoan development, but it has not yet been revealed whether apoptotic events are involved in the process of regeneration. Here, we tried to detect apoptotic cells during planarian regeneration using the TdT-mediated dUTP nick-end labeling (TUNEL) assay as well as the expression of apoptosis-related genes. Three

Jung Shan Hwang; Chiyoko Kobayashi; Kiyokazu Agata; Kazuho Ikeo; Takashi Gojobori

2004-01-01

195

Molecular cloning and characterization of SL3: A stem cell-specific SL RNA from the planarian Schmidtea mediterranea  

PubMed Central

Spliced leader (SL) trans-splicing is a biological phenomenon, common among many metazoan taxa, consisting in the transfer of a short leader sequence from a small SL RNA to the 5? end of a subset of pre-mRNAs. While knowledge of the biochemical mechanisms driving this process has accumulated over the years, the functional consequences of such post-transcriptional event at the organismal level remain unclear. In addition, the fact that functional analyses have been undertaken mainly in trypanosomes and nematodes leaves a somehow fragmented picture of the possible biological significance and evolution of SL trans-splicing in eukaryotes. Here, we analyzed the spatial expression of SL RNAs in the planarian flatworm Schmidtea mediterranea, with the goal of identifying novel developmental paradigms for the study of trans-splicing in metazoans. Besides the previously identified SL1 and SL2, S. mediterranea expresses a third SL RNA described here as SL3. While, SL1 and SL2 are collectively expressed in a broad range of planarian cell types, SL3 is highly enriched in a subset of the planarian stem cells engaged in regenerative responses. Our findings provide new opportunities to study how trans-splicing may regulate the phenotype of a cell. PMID:24120894

Rossi, Alessandro; Ross, Eric J.; Jack, Antonia; Alvarado, Alejandro Sánchez

2014-01-01

196

Comparative study of adaptive radiations with an example using parasitic flatworms (Platyhelminthes): Cercomeria  

SciTech Connect

Studies of adaptive radiations require robust phylogenies, estimates of species numbers for monophyletic groups within clades, assessments of the adaptive value of putative key innovations, and estimates of the frequency of speciation modes. Four criteria are necessary to identify an adaptive radiation within the parasitic platyhelminths: (1) a group contains significantly more species than its sister group, (2) species richness is apomorphic, (3) apomorphic traits enhance the potential for adaptively driven modes of speciation (sympatric speciation and speciation by peripheral isolation via host switching), and (4) the frequency of adaptively driven speciation modes is high within the group when compared with data from free-living groups. Only the species-rich Monogenea fulfill all four criteria. The Digenea and Eucestoda also are more species rich than their sister groups, their species richness is derived, and they possess unique characters that increase the potential for host switching to occur. However, because there is not enough information to determine whether the frequency of adaptive modes of speciation is high for those groups, we cannot yet assert that their radiations have been adaptive. 102 refs., 3 figs., 1 tab.

Brooks, D.R.; McLennan, D.A. (Univ. of Toronto, Ontario (Canada))

1993-11-01

197

Spatial Distribution and Differentiation Potential of Stem Cells in Hatchlings and Adults in the Marine Platyhelminth Macrostomum sp.: A Bromodeoxyuridine Analysis  

Microsoft Academic Search

Stem cells (neoblasts) in Platyhelminthes are pluripotent, and likely totipotent, undifferentiated cells which retain throughout adult life the capacity to proliferate and from which all somatic cells as well as the germ cells derive. However, basic data on the pool and heterogeneity of neoblasts, their rates of differentiation into sets and subsets of differentiated cells, and their migration to different

Peter Ladurner; Reinhard Rieger

2000-01-01

198

Embryonic development of the nervous system in the planarian Schmidtea polychroa.  

PubMed

The development of a nervous system is a key innovation in the evolution of metazoans, which is illustrated by the presence of a common developmental toolkit for the formation of this organ system. Neurogenesis in the Spiralia, in particular the Platyhelminthes, is, however, poorly understood when compared with other animal groups. Here, we characterize embryonic neurogenesis in the freshwater flatworm Schmidtea polychroa and analyze the expression of soxB and a set of proneural bHLH genes, which are gene families with a well-established role in metazoan early neural development. We show that the nervous system is fully de novo assembled after the early embryo ingests the maternal nutrients. At early stages of neurogenesis, soxB1 genes are expressed in putative neural progenitor cells, whereas soxB2 and neural bHLH genes (achaete-scute, neuroD and beta3) are associated with late neurogenesis and the specification of neural subpopulations of the central and peripheral nervous system. Our findings are consistent with the role of proneural genes in other bilaterians, suggesting that the ancestral neural-specific gene regulatory network is conserved in triclads, despite exhibiting a divergent mode of development. PMID:25446032

Monjo, Francisco; Romero, Rafael

2015-01-15

199

Microanatomy of the trophosome region of Paracatenula cf. polyhymnia (Catenulida, Platyhelminthes) and its intracellular symbionts.  

PubMed

Marine catenulid platyhelminths of the genus Paracatenula lack mouth, pharynx and gut. They live in a symbiosis with intracellular bacteria which are restricted to the body region posterior to the brain. The symbiont-housing cells (bacteriocytes) collectively form the trophosome tissue, which functionally replaces the digestive tract. It constitutes the largest part of the body and is the most important synapomorphy of this group. While some other features of the Paracatenula anatomy have already been analyzed, an in-depth analysis of the trophosome region was missing. Here, we identify and characterize the composition of the trophosome and its surrounding tissue by analyzing series of ultra-thin cross-sections of the species Paracatenula cf. polyhymnia. For the first time, a protonephridium is detected in a Paracatenula species, but it is morphologically reduced and most likely not functional. Cells containing needle-like inclusions in the reference species Paracatenula polyhymnia Sterrer and Rieger, 1974 were thought to be sperm, and the inclusions interpreted as the sperm nucleus. Our analysis of similar cells and their inclusions by EDX and Raman microspectroscopy documents an inorganic spicule consisting of a unique magnesium-phosphate compound. Furthermore, we identify the neoblast stem cells located underneath the epidermis. Except for the modifications due to the symbiotic lifestyle and the enigmatic spicule cells, the organization of Paracatenula cf. polyhymnia conforms to that of the Catenulida in all studied aspects. Therefore, this species represents an excellent model system for further studies of host adaptation to an obligate symbiotic lifestyle. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00435-011-0135-y) contains supplementary material, which is available to authorized users. PMID:22131640

Leisch, Nikolaus; Dirks, Ulrich; Gruber-Vodicka, Harald R; Schmid, Markus; Sterrer, Wolfgang; Ott, Jörg A

2011-12-01

200

Amputation induces stem cell mobilization to sites of injury during planarian regeneration  

PubMed Central

How adult stem cell populations are recruited for tissue renewal and repair is a fundamental question of biology. Mobilization of stem cells out of their niches followed by correct migration and differentiation at a site of tissue turnover or injury are important requirements for proper tissue maintenance and regeneration. However, we understand little about the mechanisms that control this process, possibly because the best studied vertebrate adult stem cell systems are not readily amenable to in vivo observation. Furthermore, few clear examples of the recruitment of fully potent stem cells, compared with limited progenitors, are known. Here, we show that planarian stem cells directionally migrate to amputation sites during regeneration. We also show that during tissue homeostasis they are stationary. Our study not only uncovers the existence of specific recruitment mechanisms elicited by amputation, but also sets the stage for the systematic characterization of evolutionarily conserved stem cell regulatory processes likely to inform stem cell function and dysfunction in higher organisms, including humans. PMID:22899852

Guedelhoefer, Otto C.; Alvarado, Alejandro Sánchez

2012-01-01

201

Gene expression of pluripotency determinants is conserved between mammalian and planarian stem cells.  

PubMed

Freshwater planaria possess extreme regeneration capabilities mediated by abundant, pluripotent stem cells (neoblasts) in adult animals. Although planaria emerged as an attractive in vivo model system for stem cell biology, gene expression in neoblasts has not been profiled comprehensively and it is unknown how molecular mechanisms for pluripotency in neoblasts relate to those in mammalian embryonic stem cells (ESCs). We purified neoblasts and quantified mRNA and protein expression by sequencing and shotgun proteomics. We identified ?4000 genes specifically expressed in neoblasts, including all ?30 known neoblast markers. Genes important for pluripotency in ESCs, including regulators as well as targets of OCT4, were well conserved and upregulated in neoblasts. We found conserved expression of epigenetic regulators and demonstrated their requirement for planarian regeneration by knockdown experiments. Post-transcriptional regulatory genes characteristic for germ cells were also enriched in neoblasts, suggesting the existence of a common ancestral state of germ cells and ESCs. We conclude that molecular determinants of pluripotency are conserved throughout evolution and that planaria are an informative model system for human stem cell biology. PMID:22543868

Onal, Pinar; Grün, Dominic; Adamidi, Catherine; Rybak, Agnieszka; Solana, Jordi; Mastrobuoni, Guido; Wang, Yongbo; Rahn, Hans-Peter; Chen, Wei; Kempa, Stefan; Ziebold, Ulrike; Rajewsky, Nikolaus

2012-06-13

202

zic-1 Expression in Planarian neoblasts after injury controls anterior pole regeneration.  

PubMed

Mechanisms that enable injury responses to prompt regenerative outgrowth are not well understood. Planarians can regenerate essentially any tissue removed by wounding, even after decapitation, due to robust regulation of adult pluripotent stem cells of the neoblast population. Formation of pole signaling centers involving Wnt inhibitors or Wnt ligands promotes head or tail regeneration, respectively, and this process requires the use of neoblasts early after injury. We used expression profiling of purified neoblasts to identify factors needed for anterior pole formation. Using this approach, we identified zic-1, a Zic-family transcription factor, as transcriptionally activated in a subpopulation of neoblasts near wound sites early in head regeneration. As head regeneration proceeds, the Wnt inhibitor notum becomes expressed in the newly forming anterior pole in zic-1-expressing cells descended from neoblasts. Inhibition of zic-1 by RNAi resulted in a failure to express notum at the anterior pole and to regenerate a head, but did not affect tail regeneration. Both injury and canonical Wnt signaling inhibition are required for zic-1 expression, and double-RNAi experiments suggest zic-1 inhibits Wnt signaling to allow head regeneration. Analysis of neoblast fate determinants revealed that zic-1 controls specification of notum-expressing cells from foxD-expressing neoblasts to form the anterior pole, which organizes subsequent outgrowth. Specialized differentiation programs may in general underlie injury-dependent formation of tissue organizing centers used for regenerative outgrowth. PMID:24992682

Vásquez-Doorman, Constanza; Petersen, Christian P

2014-07-01

203

DrRad51 is required for chiasmata formation in meiosis in planarian Dugesia ryukyuensis.  

PubMed

Rad51, a conserved eukaryotic protein, mediates the homologous-recombination repair of DNA double-strand breaks that occur during both mitosis and meiosis. During prophase I of meiosis, homologous recombination enhances the linkage between homologous chromosomes to increase the accuracy of segregation at anaphase I. In polyploidy situations, however, difficulties with homologous chromosome segregation often disrupt meiosis. Yet, triploid individuals of the planarian Dugesia ryukyuensis are able to produce functional gametes through a specialized form of meiosis. To shed light on the molecular mechanisms that promote successful meiosis in triploid D. ryukyuensis, we investigated rad51 gene function. We isolated three genes of the Rad51 family, the Rad51 homolog Dr-rad51 and the Rad51 paralogs Dr-rad51B and Dr-rad51C. Dr-rad51 was expressed in germ-line and presumably in somatic stem cells, but was not necessary for the regeneration of somatic tissue. RNA-interference (RNAi) depletion of Dr-rad51 during sexualization did not affect chromosome behavior in zygotene oocytes, but did result in the loss of chiasmata at the diplotene stage. Thus, homologous recombination does not appear to be necessary for synapsis, but is needed for crossover and proper segregation in D. ryukyuensis. PMID:24488935

Chinone, Ayako; Matsumoto, Midori

2014-05-01

204

Amputation induces stem cell mobilization to sites of injury during planarian regeneration.  

PubMed

How adult stem cell populations are recruited for tissue renewal and repair is a fundamental question of biology. Mobilization of stem cells out of their niches followed by correct migration and differentiation at a site of tissue turnover or injury are important requirements for proper tissue maintenance and regeneration. However, we understand little about the mechanisms that control this process, possibly because the best studied vertebrate adult stem cell systems are not readily amenable to in vivo observation. Furthermore, few clear examples of the recruitment of fully potent stem cells, compared with limited progenitors, are known. Here, we show that planarian stem cells directionally migrate to amputation sites during regeneration. We also show that during tissue homeostasis they are stationary. Our study not only uncovers the existence of specific recruitment mechanisms elicited by amputation, but also sets the stage for the systematic characterization of evolutionarily conserved stem cell regulatory processes likely to inform stem cell function and dysfunction in higher organisms, including humans. PMID:22899852

Guedelhoefer, Otto C; Sánchez Alvarado, Alejandro

2012-10-01

205

zic-1 Expression in Planarian Neoblasts after Injury Controls Anterior Pole Regeneration  

PubMed Central

Mechanisms that enable injury responses to prompt regenerative outgrowth are not well understood. Planarians can regenerate essentially any tissue removed by wounding, even after decapitation, due to robust regulation of adult pluripotent stem cells of the neoblast population. Formation of pole signaling centers involving Wnt inhibitors or Wnt ligands promotes head or tail regeneration, respectively, and this process requires the use of neoblasts early after injury. We used expression profiling of purified neoblasts to identify factors needed for anterior pole formation. Using this approach, we identified zic-1, a Zic-family transcription factor, as transcriptionally activated in a subpopulation of neoblasts near wound sites early in head regeneration. As head regeneration proceeds, the Wnt inhibitor notum becomes expressed in the newly forming anterior pole in zic-1-expressing cells descended from neoblasts. Inhibition of zic-1 by RNAi resulted in a failure to express notum at the anterior pole and to regenerate a head, but did not affect tail regeneration. Both injury and canonical Wnt signaling inhibition are required for zic-1 expression, and double-RNAi experiments suggest zic-1 inhibits Wnt signaling to allow head regeneration. Analysis of neoblast fate determinants revealed that zic-1 controls specification of notum-expressing cells from foxD-expressing neoblasts to form the anterior pole, which organizes subsequent outgrowth. Specialized differentiation programs may in general underlie injury-dependent formation of tissue organizing centers used for regenerative outgrowth. PMID:24992682

Vásquez-Doorman, Constanza; Petersen, Christian P.

2014-01-01

206

JNK Controls the Onset of Mitosis in Planarian Stem Cells and Triggers Apoptotic Cell Death Required for Regeneration and Remodeling  

PubMed Central

Regeneration of lost tissues depends on the precise interpretation of molecular signals that control and coordinate the onset of proliferation, cellular differentiation and cell death. However, the nature of those molecular signals and the mechanisms that integrate the cellular responses remain largely unknown. The planarian flatworm is a unique model in which regeneration and tissue renewal can be comprehensively studied in vivo. The presence of a population of adult pluripotent stem cells combined with the ability to decode signaling after wounding enable planarians to regenerate a complete, correctly proportioned animal within a few days after any kind of amputation, and to adapt their size to nutritional changes without compromising functionality. Here, we demonstrate that the stress-activated c-jun–NH2–kinase (JNK) links wound-induced apoptosis to the stem cell response during planarian regeneration. We show that JNK modulates the expression of wound-related genes, triggers apoptosis and attenuates the onset of mitosis in stem cells specifically after tissue loss. Furthermore, in pre-existing body regions, JNK activity is required to establish a positive balance between cell death and stem cell proliferation to enable tissue renewal, remodeling and the maintenance of proportionality. During homeostatic degrowth, JNK RNAi blocks apoptosis, resulting in impaired organ remodeling and rescaling. Our findings indicate that JNK-dependent apoptotic cell death is crucial to coordinate tissue renewal and remodeling required to regenerate and to maintain a correctly proportioned animal. Hence, JNK might act as a hub, translating wound signals into apoptotic cell death, controlled stem cell proliferation and differentiation, all of which are required to coordinate regeneration and tissue renewal. PMID:24922054

Almuedo-Castillo, María; Crespo, Xenia; Seebeck, Florian; Bartscherer, Kerstin; Salò, Emili; Adell, Teresa

2014-01-01

207

JNK controls the onset of mitosis in planarian stem cells and triggers apoptotic cell death required for regeneration and remodeling.  

PubMed

Regeneration of lost tissues depends on the precise interpretation of molecular signals that control and coordinate the onset of proliferation, cellular differentiation and cell death. However, the nature of those molecular signals and the mechanisms that integrate the cellular responses remain largely unknown. The planarian flatworm is a unique model in which regeneration and tissue renewal can be comprehensively studied in vivo. The presence of a population of adult pluripotent stem cells combined with the ability to decode signaling after wounding enable planarians to regenerate a complete, correctly proportioned animal within a few days after any kind of amputation, and to adapt their size to nutritional changes without compromising functionality. Here, we demonstrate that the stress-activated c-jun-NH2-kinase (JNK) links wound-induced apoptosis to the stem cell response during planarian regeneration. We show that JNK modulates the expression of wound-related genes, triggers apoptosis and attenuates the onset of mitosis in stem cells specifically after tissue loss. Furthermore, in pre-existing body regions, JNK activity is required to establish a positive balance between cell death and stem cell proliferation to enable tissue renewal, remodeling and the maintenance of proportionality. During homeostatic degrowth, JNK RNAi blocks apoptosis, resulting in impaired organ remodeling and rescaling. Our findings indicate that JNK-dependent apoptotic cell death is crucial to coordinate tissue renewal and remodeling required to regenerate and to maintain a correctly proportioned animal. Hence, JNK might act as a hub, translating wound signals into apoptotic cell death, controlled stem cell proliferation and differentiation, all of which are required to coordinate regeneration and tissue renewal. PMID:24922054

Almuedo-Castillo, María; Crespo, Xenia; Seebeck, Florian; Bartscherer, Kerstin; Salò, Emili; Adell, Teresa

2014-06-01

208

Evaluation of endogenous reference genes for analysis of gene expression with real-time RT-PCR during planarian regeneration  

Microsoft Academic Search

It is important that endogenous reference genes for real-time RT-PCR be empirically evaluated for stability in different cell\\u000a types, developmental stages, and\\/or sample treatment. To select the most stable endogenous reference genes during planarian\\u000a regeneration, three housekeeping genes, 18S rRNA, ACTB and DjEF2, were identified and established expression levels by real-time RT-PCR. The data were analyzed by GeNorm and NormFinder

Yan-qing YuwenZi-mei; Zi-mei Dong; Qing-hua Wang; Xiao-juan Sun; Chang-ying Shi; Guang-wen Chen

209

The physiological response of the marine platyhelminth Macrostomum lignano to different environmental oxygen concentrations.  

PubMed

The respiration rate of meiofauna is difficult to measure, and the response to variations in the environmental oxygen concentration has so far been mainly addressed through behavioral investigation. We investigated the effect of different oxygen concentrations on the physiology of the marine platyhelminth Macrostomum lignano. Respiration was measured using batches of 20 animals in a glass microtiter plate equipped with optical oxygen sensor spots. At higher oxygen saturations (>12 kPa), the animals showed a clear oxyconforming behavior. However, below this value, the flatworms kept respiration rates constant at 0.064±0.001 nmol O2 l(-1) h(-1) individual(-1) down to 3 kPa PO2, and this rate was increased by 30% in animals that were reoxygenated after enduring a period of 1.5 h in anoxia. Physiological changes related to tissue oxygenation were assessed using live imaging techniques with different fluorophores in animals maintained in normoxic (21 kPa), hyperoxic (40 kPa) or near-anoxic (~0 kPa) conditions and subjected to anoxia-reoxygenation. The pH-sensitive dyes Ageladine-A and BCECF both indicated that pHi under near-anoxia increases by about 0.07-0.10 units. Mitochondrial membrane potential, ??m, was higher in anoxic and hyperoxic than in normoxic conditions (JC1 dye data). Staining with ROS-sensitive dyes - DHE for detection of superoxide anion (O2•(-)) formation and C-H DFFDA for other ROS species aside from O2•(-) (H2O2, HOO• and ONOO) - showed increased ROS formation following anoxia-reoxygenation treatment. Animals exposed to hyperoxic, normoxic and anoxic treatments displayed no significant differences in O2•(-) formation, whereas mitochondrial ROS formation as detected by C-H2DFFDA was higher after hyperoxic exposure and lowest under near-anoxia conditions compared with the normoxic control group. Macrostomum lignano seems to be a species that is tolerant of a wide range of oxygen concentrations (being able to maintain aerobic metabolism from extremely low PO2 up to hyperoxic conditions), which is an essential prerequisite for successfully dealing with the drastic environmental oxygen variations that occur within intertidal sediments. PMID:23531823

Rivera-Ingraham, G A; Bickmeyer, U; Abele, D

2013-07-15

210

Venus Kinase Receptors Control Reproduction in the Platyhelminth Parasite Schistosoma mansoni  

PubMed Central

The Venus Kinase Receptor (VKR) is a single transmembrane molecule composed of an intracellular tyrosine kinase domain close to that of insulin receptor and an extracellular Venus Flytrap (VFT) structure similar to the ligand binding domain of many class C G Protein Coupled Receptors. This receptor tyrosine kinase (RTK) was first discovered in the platyhelminth parasite Schistosoma mansoni, then in a large variety of invertebrates. A single vkr gene is found in most genomes, except in S. mansoni in which two genes Smvkr1 and Smvkr2 exist. VKRs form a unique family of RTKs present only in invertebrates and their biological functions are still to be discovered. In this work, we show that SmVKRs are expressed in the reproductive organs of S. mansoni, particularly in the ovaries of female worms. By transcriptional analyses evidence was obtained that both SmVKRs fulfill different roles during oocyte maturation. Suppression of Smvkr expression by RNA interference induced spectacular morphological changes in female worms with a strong disorganization of the ovary, which was dominated by the presence of primary oocytes, and a defect of egg formation. Following expression in Xenopus oocytes, SmVKR1 and SmVKR2 receptors were shown to be activated by distinct ligands which are L-Arginine and calcium ions, respectively. Signalling analysis in Xenopus oocytes revealed the capacity of SmVKRs to activate the PI3K/Akt/p70S6K and Erk MAPK pathways involved in cellular growth and proliferation. Additionally, SmVKR1 induced phosphorylation of JNK (c-Jun N-terminal kinase). Activation of JNK by SmVKR1 was supported by the results of yeast two-hybrid experiments identifying several components of the JNK pathway as specific interacting partners of SmVKR1. In conclusion, these results demonstrate the functions of SmVKR in gametogenesis, and particularly in oogenesis and egg formation. By eliciting signalling pathways potentially involved in oocyte proliferation, growth and migration, these receptors control parasite reproduction and can therefore be considered as potential targets for anti-schistosome therapies. PMID:24875530

Cailliau, Katia; Morel, Marion; Hahnel, Steffen; Leutner, Silke; Beckmann, Svenja; Grevelding, Christoph G.; Dissous, Colette

2014-01-01

211

Venus kinase receptors control reproduction in the platyhelminth parasite Schistosoma mansoni.  

PubMed

The Venus kinase receptor (VKR) is a single transmembrane molecule composed of an intracellular tyrosine kinase domain close to that of insulin receptor and an extracellular Venus Flytrap (VFT) structure similar to the ligand binding domain of many class C G protein coupled receptors. This receptor tyrosine kinase (RTK) was first discovered in the platyhelminth parasite Schistosoma mansoni, then in a large variety of invertebrates. A single vkr gene is found in most genomes, except in S. mansoni in which two genes Smvkr1 and Smvkr2 exist. VKRs form a unique family of RTKs present only in invertebrates and their biological functions are still to be discovered. In this work, we show that SmVKRs are expressed in the reproductive organs of S. mansoni, particularly in the ovaries of female worms. By transcriptional analyses evidence was obtained that both SmVKRs fulfill different roles during oocyte maturation. Suppression of Smvkr expression by RNA interference induced spectacular morphological changes in female worms with a strong disorganization of the ovary, which was dominated by the presence of primary oocytes, and a defect of egg formation. Following expression in Xenopus oocytes, SmVKR1 and SmVKR2 receptors were shown to be activated by distinct ligands which are L-Arginine and calcium ions, respectively. Signalling analysis in Xenopus oocytes revealed the capacity of SmVKRs to activate the PI3K/Akt/p70S6K and Erk MAPK pathways involved in cellular growth and proliferation. Additionally, SmVKR1 induced phosphorylation of JNK (c-Jun N-terminal kinase). Activation of JNK by SmVKR1 was supported by the results of yeast two-hybrid experiments identifying several components of the JNK pathway as specific interacting partners of SmVKR1. In conclusion, these results demonstrate the functions of SmVKR in gametogenesis, and particularly in oogenesis and egg formation. By eliciting signalling pathways potentially involved in oocyte proliferation, growth and migration, these receptors control parasite reproduction and can therefore be considered as potential targets for anti-schistosome therapies. PMID:24875530

Vanderstraete, Mathieu; Gouignard, Nadège; Cailliau, Katia; Morel, Marion; Hahnel, Steffen; Leutner, Silke; Beckmann, Svenja; Grevelding, Christoph G; Dissous, Colette

2014-05-01

212

In vivo and in vitro metabolism of tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), by the freshwater planarian, Dugesia japonica.  

PubMed

Cigarette smoke is a risk factor for human health, and many studies were conducted to investigate its adverse effects on humans and other mammals. However, since large amounts of cigarette products are produced and consumed, it is possible that tobacco chemicals can end up in aquatic environments through several routes, thus influencing aquatic organisms. In this study, the presence of tobacco-specific nitrosamine (TSNA), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), in aquatic environment was demonstrated. Since toxic effects on and distribution patterns of tobacco chemicals in aquatic organisms were rarely studied, after results of an acute toxicity pretest were obtained, experiment was conducted to investigate the bioaccumulation pattern of NNK and distribution patterns of its metabolites, mainly 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), in NNK-treated freshwater planarians, Dugesia japonica. Results from in vivo and in vitro studies showed that NNK was readily converted to NNAL through the carbonyl reduction in bodies of NNK-treated planarians. Tissue concentrations of both chemicals increased in time- and dose-dependent manners. Furthermore, we examined the end products of NNK/NNAL ?-hydroxylation in NNK-treated planarians, but only 1-(3-pyridyl)-1,4-butanediol was detected, suggesting that NNK metabolism in planarians partially differs from that in mammalian systems. This is the first report on NNK metabolism in an aquatic organism and can be used as a foundation for developing freshwater planarians as a new in vivo model for the study of NNK toxicology in the future. PMID:22386463

Wu, Jui-Pin; Li, Mei-Hui; Chen, Jhih-Sheng; Lee, Hui-Ling

2012-06-01

213

Stem cells from innate sexual but not acquired sexual planarians have the capability to form a sexual individual.  

PubMed

Planarian species may harbor as many as three populations with different reproductive strategies. Animals from innate asexual (AS) and innate sexual (InS) populations reproduce only by fission and cross-fertilization, respectively, whereas the third population switches seasonally between the two reproductive modes. AS worms can be experimentally sexualized by feeding them with minced InS worms; we termed the resulting animals "acquired sexual" (AqS) worms. Both AqS and InS worms exhibit sexualizing activity when used as feed, suggesting that they maintain their sexual state via endogenous sexualizing substances, although the mechanisms underlying determination of reproductive strategy and sexual switching in these metazoans remain enigmatic. Therefore, we compared the endogenous sexualizing activity of InS worms and AqS worms. First, we amputated mature worms and assessed if they could re-enter a sexual state. Regenerants of InS worms, but not AqS worms, were only sexual, indicating that sexual state regulation comprises two steps: (1) autonomous initiation of sexualizing substance production and (2) maintenance of the sexual state by continuous production of sexualizing substances. Next, InS neoblasts were characterized by transplantation, finding that they successfully engrafted, proliferated, and replaced all recipient cells. Under such conditions, the AS recipients of InS worm neoblasts, but not those of AqS worms, became sexual. These results clearly show that there is a neoblast-autonomous determination of reproductive strategy in planarians. PMID:22968921

Nodono, Hanae; Ishino, Yugo; Hoshi, Motonori; Matsumoto, Midori

2012-11-01

214

Weak extremely-low-frequency magnetic field-induced regeneration anomalies in the planarian, Dugesia tigrina  

SciTech Connect

The authors recently reported that cephalic regeneration in the planarian Dugesia tigrina was significantly delayed in populations exposed continuously to combined parallel DC and AC magnetic fields. This effect was consistent with hypotheses suggesting an underlying resonance phenomenon. The authors report here, in a parallel series of investigations on the same model system, that the incidence of regeneration anomalies presenting as tumor-like protuberances also increases significantly (P < .001) in association with exposure to weak 60 Hz magnetic fields, with peak intensities ranging between 1.0 and 80.0 {micro}T. These anomalies often culminate in the complete disaggregation of the organism. Similar to regeneration rate effects, the incidence of regeneration anomalies is specifically dependent upon the planaria possessing a fixed orientation with respect to the applied magnetic field vectors. However, unlike the regeneration rate effects, the AC magnetic field alone, in the absence of any measurable DC field, is capable of producing these anomalies. Moreover, the incidence of regeneration anomalies follows a clear dose-response relationship as a function of AC magnetic field intensity, with the threshold for induced electric field intensity estimated at 5 {micro} V/m. The addition of either 51.1 or 78.4 {micro}T DC magnetic fields, applied in parallel combination with the AC field, enhances the appearance of anomalies relative to the 60 Hz AC field alone, but only at certain AC field intensities. Thus, whereas the previous study of regeneration rate effects appeared to involve exclusively resonance interactions, the regeneration anomalies reported here appear to result primarily from Faraday induction coupling.

Jenrow, K.A.; Smith, C.H.; Liboff, A.R. [Oakland Univ., Rochester, MI (United States). Dept. of Physics] [Oakland Univ., Rochester, MI (United States). Dept. of Physics

1996-12-31

215

Modeling Planarian Regeneration: A Primer for Reverse-Engineering the Worm  

PubMed Central

A mechanistic understanding of robust self-assembly and repair capabilities of complex systems would have enormous implications for basic evolutionary developmental biology as well as for transformative applications in regenerative biomedicine and the engineering of highly fault-tolerant cybernetic systems. Molecular biologists are working to identify the pathways underlying the remarkable regenerative abilities of model species that perfectly regenerate limbs, brains, and other complex body parts. However, a profound disconnect remains between the deluge of high-resolution genetic and protein data on pathways required for regeneration, and the desired spatial, algorithmic models that show how self-monitoring and growth control arise from the synthesis of cellular activities. This barrier to progress in the understanding of morphogenetic controls may be breached by powerful techniques from the computational sciences—using non-traditional modeling approaches to reverse-engineer systems such as planaria: flatworms with a complex bodyplan and nervous system that are able to regenerate any body part after traumatic injury. Currently, the involvement of experts from outside of molecular genetics is hampered by the specialist literature of molecular developmental biology: impactful collaborations across such different fields require that review literature be available that presents the key functional capabilities of important biological model systems while abstracting away from the often irrelevant and confusing details of specific genes and proteins. To facilitate modeling efforts by computer scientists, physicists, engineers, and mathematicians, we present a different kind of review of planarian regeneration. Focusing on the main patterning properties of this system, we review what is known about the signal exchanges that occur during regenerative repair in planaria and the cellular mechanisms that are thought to underlie them. By establishing an engineering-like style for reviews of the molecular developmental biology of biomedically important model systems, significant fresh insights and quantitative computational models will be developed by new collaborations between biology and the information sciences. PMID:22570595

Lobo, Daniel; Beane, Wendy S.; Levin, Michael

2012-01-01

216

Some Platyhelminths inhabiting white-throated sparrows, Zonotrichia albicollis (Aves: Emberizidae: Emberizinae), from Algonquin Park, Ontario, Canada.  

PubMed

Twenty-two of 26 white-throated sparrows, Zonotrichia albicollis, from Algonquin Park, Ontario, Canada, hosted 1 or 2 species of platyhelminths. One species of cestode and 3 of digeneans were collected. Anonchotaenia quiscali inhabited 50% of the sparrows. This is the third report of A. quiscali; Z. albicollis is a new host. Brachylecithum nanum inhabited 43%, Zonorchis alveyi 15%, and Prosthogonimus macrorchis 8% of the sparrows examined. Ontario is a new geographic distribution record from all 4 parasite species. The proportion of hosts infected with 2 species was not significantly different from expected based on single species prevalences, indicating that there is no competitive interaction among these species of parasites for access to the avian hosts. PMID:8331482

Brooks, D R; Hoberg, E P; Houtman, A

1993-08-01

217

The CCR4-NOT complex mediates deadenylation and degradation of stem cell mRNAs and promotes planarian stem cell differentiation.  

PubMed

Post-transcriptional regulatory mechanisms are of fundamental importance to form robust genetic networks, but their roles in stem cell pluripotency remain poorly understood. Here, we use freshwater planarians as a model system to investigate this and uncover a role for CCR4-NOT mediated deadenylation of mRNAs in stem cell differentiation. Planarian adult stem cells, the so-called neoblasts, drive the almost unlimited regenerative capabilities of planarians and allow their ongoing homeostatic tissue turnover. While many genes have been demonstrated to be required for these processes, currently almost no mechanistic insight is available into their regulation. We show that knockdown of planarian Not1, the CCR4-NOT deadenylating complex scaffolding subunit, abrogates regeneration and normal homeostasis. This abrogation is primarily due to severe impairment of their differentiation potential. We describe a stem cell specific increase in the mRNA levels of key neoblast genes after Smed-not1 knock down, consistent with a role of the CCR4-NOT complex in degradation of neoblast mRNAs upon the onset of differentiation. We also observe a stem cell specific increase in the frequency of longer poly(A) tails in these same mRNAs, showing that stem cells after Smed-not1 knock down fail to differentiate as they accumulate populations of transcripts with longer poly(A) tails. As other transcripts are unaffected our data hint at a targeted regulation of these key stem cell mRNAs by post-transcriptional regulators such as RNA-binding proteins or microRNAs. Together, our results show that the CCR4-NOT complex is crucial for stem cell differentiation and controls stem cell-specific degradation of mRNAs, thus providing clear mechanistic insight into this aspect of neoblast biology. PMID:24367277

Solana, Jordi; Gamberi, Chiara; Mihaylova, Yuliana; Grosswendt, Stefanie; Chen, Chen; Lasko, Paul; Rajewsky, Nikolaus; Aboobaker, A Aziz

2013-01-01

218

Genome-wide analysis of the bHLH gene family in planarians identifies factors required for adult neurogenesis and neuronal regeneration.  

PubMed

In contrast to most well-studied model organisms, planarians have a remarkable ability to completely regenerate a functional nervous system from a pluripotent stem cell population. Thus, planarians provide a powerful model to identify genes required for adult neurogenesis in vivo. We analyzed the basic helix-loop-helix (bHLH) family of transcription factors, many of which are crucial for nervous system development and have been implicated in human diseases. However, their potential roles in adult neurogenesis or central nervous system (CNS) function are not well understood. We identified 44 planarian bHLH homologs, determined their patterns of expression in the animal and assessed their functions using RNAi. We found nine bHLHs expressed in stem cells and neurons that are required for CNS regeneration. Our analyses revealed that homologs of coe, hes (hesl-3) and sim label progenitors in intact planarians, and following amputation we observed an enrichment of coe(+) and sim(+) progenitors near the wound site. RNAi knockdown of coe, hesl-3 or sim led to defects in CNS regeneration, including failure of the cephalic ganglia to properly pattern and a loss of expression of distinct neuronal subtype markers. Together, these data indicate that coe, hesl-3 and sim label neural progenitor cells, which serve to generate new neurons in uninjured or regenerating animals. Our study demonstrates that this model will be useful to investigate how stem cells interpret and respond to genetic and environmental cues in the CNS and to examine the role of bHLH transcription factors in adult tissue regeneration. PMID:24173799

Cowles, Martis W; Brown, David D R; Nisperos, Sean V; Stanley, Brianna N; Pearson, Bret J; Zayas, Ricardo M

2013-12-01

219

The CCR4-NOT Complex Mediates Deadenylation and Degradation of Stem Cell mRNAs and Promotes Planarian Stem Cell Differentiation  

PubMed Central

Post-transcriptional regulatory mechanisms are of fundamental importance to form robust genetic networks, but their roles in stem cell pluripotency remain poorly understood. Here, we use freshwater planarians as a model system to investigate this and uncover a role for CCR4-NOT mediated deadenylation of mRNAs in stem cell differentiation. Planarian adult stem cells, the so-called neoblasts, drive the almost unlimited regenerative capabilities of planarians and allow their ongoing homeostatic tissue turnover. While many genes have been demonstrated to be required for these processes, currently almost no mechanistic insight is available into their regulation. We show that knockdown of planarian Not1, the CCR4-NOT deadenylating complex scaffolding subunit, abrogates regeneration and normal homeostasis. This abrogation is primarily due to severe impairment of their differentiation potential. We describe a stem cell specific increase in the mRNA levels of key neoblast genes after Smed-not1 knock down, consistent with a role of the CCR4-NOT complex in degradation of neoblast mRNAs upon the onset of differentiation. We also observe a stem cell specific increase in the frequency of longer poly(A) tails in these same mRNAs, showing that stem cells after Smed-not1 knock down fail to differentiate as they accumulate populations of transcripts with longer poly(A) tails. As other transcripts are unaffected our data hint at a targeted regulation of these key stem cell mRNAs by post-transcriptional regulators such as RNA-binding proteins or microRNAs. Together, our results show that the CCR4-NOT complex is crucial for stem cell differentiation and controls stem cell-specific degradation of mRNAs, thus providing clear mechanistic insight into this aspect of neoblast biology. PMID:24367277

Solana, Jordi; Gamberi, Chiara; Mihaylova, Yuliana; Grosswendt, Stefanie; Chen, Chen; Lasko, Paul; Rajewsky, Nikolaus; Aboobaker, A. Aziz

2013-01-01

220

Flumazenil-sensitive dose-related physical dependence in planarians produced by two benzodiazepine and one non-benzodiazepine benzodiazepine receptor agonists  

PubMed Central

Two benzodiazepine (midazolam and clorazepate) and one non-benzodiazepine (zolpidem) benzodiazepine-receptor agonists produced dose-related physical dependence, as evidenced by abstinence-induced decrease in planarian locomotor velocity (pLMV) when drug-exposed planarians were placed into drug-free water, but not when they were placed into drug-containing water (i.e., an abstinence-induced withdrawal, since the effect was only obtained in the removal of dug and not in the continued presence of drug). We have previously shown that the decrease in pLMV is associated with specific and transient withdrawal signs. In the present study, the selective benzodiazepine receptor antagonist flumazenil significantly antagonized (P < 0.05), by co-application, the ability of each agonist to produce the withdrawal. These results: (1) suggest that benzodiazepine receptor agonists, for two different chemical categories, produce dose-related physical dependence manifested as abstinence-induced withdrawal in this simple and convenient model, and (2) in the absence of cloning or radioligand binding literature, suggest a possible specific interaction site (receptor?) for these compounds in planarians. PMID:17368613

Raffa, Robert B.; Cavallo, Federica; Capasso, Anna

2009-01-01

221

Flumazenil-sensitive dose-related physical dependence in planarians produced by two benzodiazepine and one non-benzodiazepine benzodiazepine-receptor agonists.  

PubMed

Two benzodiazepine (midazolam and clorazepate) and one non-benzodiazepine (zolpidem) benzodiazepine-receptor agonists produced dose-related physical dependence, as evidenced by abstinence-induced decrease in planarian locomotor velocity (pLMV) when drug-exposed planarians were placed into drug-free water, but not when they were placed into drug-containing water (i.e., an abstinence-induced withdrawal, since the effect was only obtained in the removal of drug and not in the continued presence of drug). We have previously shown that the decrease in pLMV is associated with specific and transient withdrawal signs. In the present study, the selective benzodiazepine-receptor antagonist flumazenil significantly antagonized (P<0.05), by co-application, the ability of each agonist to produce the withdrawal. These results: (1) suggest that benzodiazepine-receptor agonists, for two different chemical categories, produce dose-related physical dependence manifested as abstinence-induced withdrawal in this simple and convenient model, and (2) in the absence of cloning or radioligand binding literature, suggest a possible specific interaction site (receptor?) for these compounds in planarians. PMID:17368613

Raffa, Robert B; Cavallo, Federica; Capasso, Anna

2007-06-14

222

Transcription factors lhx1/5-1 and pitx are required for the maintenance and regeneration of serotonergic neurons in planarians.  

PubMed

In contrast to most adult organisms, freshwater planarians can regenerate any injured body part, including their entire nervous system. This allows for the analysis of genes required for both the maintenance and regeneration of specific neural subtypes. In addition, the loss of specific neural subtypes may uncover previously unknown behavioral roles for that neural population in the context of the adult animal. Here we show that two homeodomain transcription factor homologs, Smed-lhx1/5-1 and Smed-pitx, are required for the maintenance and regeneration of serotonergic neurons in planarians. When either lhx1/5-1 or pitx was knocked down by RNA interference, the expression of multiple canonical markers for serotonergic neurons was lost. Surprisingly, the loss of serotonergic function uncovered a role for these neurons in the coordination of motile cilia on the ventral epidermis of planarians that are required for their nonmuscular gliding locomotion. Finally, we show that in addition to its requirement in serotonergic neurons, Smed-pitx is required for proper midline patterning during regeneration, when it is required for the expression of the midline-organizing molecules Smed-slit in the anterior and Smed-wnt1 in the posterior. PMID:23903188

Currie, Ko W; Pearson, Bret J

2013-09-01

223

Taxonomy of Cotylea (Platyhelminthes: Polycladida) from Cabo Frio, southeastern Brazil, with the description of a new species.  

PubMed

Polyclads are free-living Platyhelminthes with a simple, dorsoventrally flattened body and a much ramified intestine. In Brazil, 66 species are reported; only three from Rio de Janeiro State (RJ). The main objective of this study is to describe and illustrate coloration pattern, external morphology, reproductive system morphology and, when possible, biological and ecological aspects of species of the suborder Cotylea found in Cabo Frio, RJ. Of the 13 cotylean polyclad species found, Pseudobiceros pardalis, Cycloporus variegatus and Eurylepta aurantiaca are new records from the Brazilian coast and one species is new to science, Pseudoceros juani sp. nov. Feeding observations were made of four species. It is the first time that Lurymare utarum, Cycloporus gabriellae, C. variegatus and E. aurantiaca are illustrated with digital photographs of live specimens and histological preparations. This study increases to 70 the number of Brazilian Polycladida and to 14 the number of species known from Rio de Janeiro State. However, the knowledge about Polycladida in Brazil still has gaps, with great parts of the coast remaining unsampled.  PMID:25544234

Bahia, Juliana; Padula, Vinicius; Lavrado, Helena Passeri; Quiroga, Sigmer

2014-01-01

224

Complete Sequence of the mitochondrial genome of the tapeworm Hymenolepis diminuta: Gene arrangements indicate that platyhelminths are eutrochozoans  

SciTech Connect

Using ''long-PCR'' we have amplified in overlapping fragments the complete mitochondrial genome of the tapeworm Hymenolepis diminuta (Platyhelminthes: Cestoda) and determined its 13,900 nucleotide sequence. The gene content is the same as that typically found for animal mitochondrial DNA (mtDNA) except that atp8 appears to be lacking, a condition found previously for several other animals. Despite the small size of this mtDNA, there are two large non-coding regions, one of which contains 13 repeats of a 31 nucleotide sequence and a potential stem-loop structure of 25 base pairs with an 11-member loop. Large potential secondary structures are identified also for the non-coding regions of two other cestode mtDNAs. Comparison of the mitochondrial gene arrangement of H. diminuta with those previously published supports a phylogenetic position of flatworms as members of the Eutrochozoa, rather than being basal to either a clade of protostomes or a clade of coelomates.

von Nickisch-Rosenegk, Markus; Brown, Wesley M.; Boore, Jeffrey L.

2001-01-01

225

A new genus and species for the first recorded cave-dwelling Cavernicola (Platyhelminthes) from South America  

PubMed Central

Abstract Species diversity of Brazilian cave fauna has been seriously underestimated. A karst area located in Felipe Guerra, northeastern Brazil, which is a hotspot of subterranean diversity in Brazil, has revealed more than 20 troglobitic species, most of them still undescribed. Based on recent samplings in this karst area, we document the occurrence of the suborder Cavernicola (Platyhelminthes) in South American hypogean environments for the first time and describe a new genus and species for this suborder. Hausera Leal-Zanchet & Souza, gen. n. has features concordant with those defined for the family Dimarcusidae. The new genus is characterized by two unique features, viz. an intestine extending dorsally to the brain and ovovitelline ducts located dorsally to the nerve cords, which is complemented by a combination of other characters. The type-specimens of Hausera hauseri Leal-Zanchet & Souza, sp. n. are typical stygobionts, unpigmented and eyeless, and they may constitute an oceanic relict as is the case of other stygobiotic invertebrates found in this karst area in northeastern Brazil. PMID:25349486

Leal-Zanchet, Ana Maria; de Souza, Stella Teles; Ferreira, Rodrigo Lopes

2014-01-01

226

Identification and characterization of a nuclear receptor subfamily I member in the Platyhelminth Schistosoma mansoni (SmNR1).  

PubMed

A cDNA encoding a nuclear receptor subfamily I member in the platyhelminth Schistosoma mansoni (SmNR1) was identified and characterized. SmNR1 cDNA is 2406 bp long and contains an open reading frame encoding a 715 residue protein. Phylogenetic analysis demonstrates that SmNR1 is a divergent member of nuclear receptor subfamily I with no known orthologue. SmNR1 was localized to S. mansoni chromosome 1 by fluorescent in situ hybridization. Gene structure of SmNR1 was determined showing it to consist of eight exons spanning more than 14 kb. Quantitative real-time RT-PCR showed that SmNR1 was expressed throughout schistosome development with a higher expression in eggs, sporocysts and 21-day worms. SmNR1 contains an autonomous transactivation function (AF1) in the A/B domain as demonstrated in a yeast one-hybrid assay; it interacts with SmRXR1 in a yeast two-hybrid assay and in a glutathione S-transferase pull-down assay. Electrophoretic mobility shift assay showed that SmNR1 could form a heterodimer with SmRXR1 to bind to DNA elements containing the half-site AGGTCA, a direct repeat of the half-site separated by 0-5 nucleotides (DR1-DR5) and a palindrome repeat of the half-site not separated by nucleic acids (Pal0). Transient transfection in mammalian COS-7 cells showed that SmNR1/SmRXR1 could enhance the transcriptional activation of a DR2-dependent reporter gene. Our results demonstrate that SmNR1 is a partner of SmRXR1. PMID:17173548

Wu, Wenjie; Niles, Edward G; Hirai, Hirohisa; LoVerde, Philip T

2007-01-01

227

A forkhead transcription factor is wound-induced at the planarian midline and required for anterior pole regeneration.  

PubMed

Planarian regeneration requires positional information to specify the identity of tissues to be replaced as well as pluripotent neoblasts capable of differentiating into new cell types. We found that wounding elicits rapid expression of a gene encoding a Forkhead-family transcription factor, FoxD. Wound-induced FoxD expression is specific to the ventral midline, is regulated by Hedgehog signaling, and is neoblast-independent. FoxD is subsequently expressed within a medial subpopulation of neoblasts at wounds involving head regeneration. Ultimately, FoxD is co-expressed with multiple anterior markers at the anterior pole. Inhibition of FoxD with RNA interference (RNAi) results in the failure to specify neoblasts expressing anterior markers (notum and prep) and in anterior pole formation defects. FoxD(RNAi) animals fail to regenerate a new midline and to properly pattern the anterior blastema, consistent with a role for the anterior pole in organizing pattern of the regenerating head. Our results suggest that wound signaling activates a forkhead transcription factor at the midline and, if the head is absent, FoxD promotes specification of neoblasts at the prior midline for anterior pole regeneration. PMID:24415944

Scimone, M Lucila; Lapan, Sylvain W; Reddien, Peter W

2014-01-01

228

[Effect of the extremely weak alternating magnetic fields on the regeneration of planarians and the gravitropic response of plants].  

PubMed

The influence of extremely weak alternating magnetic fields (EW AMF) directed colinearly to the static Earth magnetic field on the rate of regeneration of planarians and the rate of gravitropic response in the stem segments of flax has been studied. The value of bioeffects of EW AMF is determined by the parameter gamma B(AC)/f, where y is the gyromagnetic ratio of the magnetic moments induced by the orbital movements of electrons in atoms, and B(AC) and f correspond to magnetic induction and frequency of the alternating magnetic component. It was shown that the magnitude of bioeffects depends on the amplitude (at fixed 1000 Hz - frequency) and frequency (at fixed 192 nT - amplitude) of the alternating component. Maxima of bioeffects are observed at gamma B(AC)/f = 0.9; 2.75, and minor maxima gamma B(AC)/f = 4.5; 6.1. The bioeffects are absent at gamma B(AC)/f = 1.8, 3.8, 5.3, 6.7. The positions of the maxima and minima of bioeffects correspond to the theoretical prediction (at gamma = 14000 Hz/microT). Primary targets for the EW AMF of this type are the magnetic moments induced by the orbital movements of electrons in atoms. PMID:20968085

Belova, N A; Ermakov, A M; Znobishcheva, A V; Skrebnitskaia, L K; Lednev, V V

2010-01-01

229

egr-4, a target of EGFR signaling, is required for the formation of the brain primordia and head regeneration in planarians.  

PubMed

During the regeneration of freshwater planarians, polarity and patterning programs play essential roles in determining whether a head or a tail regenerates at anterior or posterior-facing wounds. This decision is made very soon after amputation. The pivotal role of the Wnt/?-catenin and Hh signaling pathways in re-establishing anterior-posterior (AP) polarity has been well documented. However, the mechanisms that control the growth and differentiation of the blastema in accordance with its AP identity are less well understood. Previous studies have described a role of Smed-egfr-3, a planarian epidermal growth factor receptor, in blastema growth and differentiation. Here, we identify Smed-egr-4, a zinc-finger transcription factor belonging to the early growth response gene family, as a putative downstream target of Smed-egfr-3. Smed-egr-4 is mainly expressed in the central nervous system and its silencing inhibits anterior regeneration without affecting the regeneration of posterior regions. Single and combinatorial RNA interference to target different elements of the Wnt/?-catenin pathway, together with expression analysis of brain- and anterior-specific markers, revealed that Smed-egr-4: (1) is expressed in two phases - an early Smed-egfr-3-independent phase and a late Smed-egfr-3-dependent phase; (2) is necessary for the differentiation of the brain primordia in the early stages of regeneration; and (3) that it appears to antagonize the activity of the Wnt/?-catenin pathway to allow head regeneration. These results suggest that a conserved EGFR/egr pathway plays an important role in cell differentiation during planarian regeneration and indicate an association between early brain differentiation and the proper progression of head regeneration. PMID:24700819

Fraguas, Susanna; Barberán, Sara; Iglesias, Marta; Rodríguez-Esteban, Gustavo; Cebrià, Francesc

2014-05-01

230

Optimal durations of single exposures to a frequency-modulated magnetic field immediately after bisection in planarian predict final growth values.  

PubMed

Planarian (Dugesia tigrinia) were exposed to a frequency-modulated ("Thomas"), patterned electromagnetic field (EMF) immediately following transection through the pharynx. Subjects were exposed from 15 min to 3 h as well as single versus repeated exposures. Results from multiple experiments indicated that those planaria exposed from 45 to 90 min regenerated at significantly higher rates than those exposed less than 45 min. In addition, the study revealed that exposures greater than 45 min were not significantly different beyond this inflection point. We suggest that this particular pattern of EMF is capable of inducing biochemical pathways associated with cell proliferation, in particular the p38-MAPK and hsp70 pathways. PMID:24115101

Tessaro, Lucas W E; Persinger, Michael A

2013-12-01

231

The beta-lactam antibiotic ceftriaxone inhibits physical dependence and abstinence-induced withdrawal from cocaine, amphetamine, methamphetamine, and clorazepate in planarians.  

PubMed

Ceftriaxone (a beta-lactam antibiotic) has recently been identified as having the rare ability to increase the expression and functional activity of the glutamate transporter subtype 1 (GLT-1) in rat spinal cord cultures. GLT-1 has been implicated in diverse neurological disorders and in opioid dependence and withdrawal. It has been speculated that it might also be involved in the physical dependence and withdrawal of other abused drugs, but demonstration of this property can be difficult in mammalian models. Here, we demonstrate for the first time using a planarian model that ceftriaxone attenuates both the development of physical dependence and abstinence-induced withdrawal from cocaine, amphetamine, methamphetamine, and a benzodiazepine (clorazepate) in a concentration-related manner. These results suggest that physical dependence and withdrawal from several drugs involve a common - beta-lactam-sensitive - mechanism in planarians. If these findings can be shown to extend to mammals, beta-lactam antibiotics might represent a novel pharmacotherapy or adjunct approach for treating drug abuse or serve as a template for drug discovery efforts aimed at treating drug abuse, recovery from drug abuse, or ameliorating the withdrawal from chronic use of therapeutic medications. PMID:18342307

Rawls, Scott M; Cavallo, Federica; Capasso, Anna; Ding, Zhe; Raffa, Robert B

2008-04-28

232

Analysis of planarian Adh3 supports an intron-rich architecture and tissue-specific expression for the urbilaterian ancestral form.  

PubMed

The alcohol dehydrogenase class 3 enzyme (ADH3) is the presumed ancestral form of the medium-chain dehydrogenase-reductase ADH family. This enzyme has been involved in formaldehyde and nitric oxide metabolism of a variety of deuterostomes and ecdysozoan protostomes. We have now characterized the structure and expression of the Adh3 gene in the lophotrochozoan Schmidtea mediterranea, a freshwater planarian. The planarian gene expands over 8.7 kb and is organized into 7 exons. The 1340 bp long Adh3cDNA contains a 1137 bp open reading frame corresponding to a deduced protein of 379 amino acids. The protein sequence is consistent with that expected for a typical class III enzyme. Twenty out of the twenty-two amino acid positions associated with enzymatic roles are strictly preserved, which suggests that the enzymatic capabilities have been conserved. In situ hybridization experiments show that Adh3 is expressed along the intestine of S. mediterranea specimens. This is consistent with the pattern observed in invertebrates and in contrast with the widespread expression of vertebrate Adh3. The comparative study across bilateria, which now includes a lophotrochozoan representative, further supports the idea that the urbilaterian Adh3 ancestor showed an intron-rich architecture and tissue-specific expression, and strengthens the view that widespread expression of Adh3 was a vertebrate innovation. PMID:17270479

Godoy, Laura; Gonzàlez-Duarte, Roser; Albalat, Ricard

2007-04-01

233

Molecular Characterization of Gastrothylax crumenifer (Platyhelminthes: Gastrothylacidae) from Goats in the Western Part of India by LSU of Nuclear Ribosomal DNA  

PubMed Central

The rumen parasite, Gastrothylax crumenifer (Platyhelminthes: Gastrothylacidae), is a highly pathogenic trematode parasite of goat (Capra hircus). It sucks blood that causes acute disease like anemia, and severe economic losses occur due to morbidity and mortality of the ruminant infected by these worms. The study of these rumen paramphistomes, their infection, and public health importance remains unclear in India especially in the western part of state Uttar Pradesh (U.P.), Meerut, India, where the goat meat consumption is very high. This paper provides the molecular characterization of G. crumenifer recovered from the rumen of Capra hircus from Meerut, U.P., India by the partial sequence of 28S rDNA. Nucleotide sequence similarity searching on BLAST of 28S rDNA from parasites showed the highest identity with those of G. crumenifer from the same host Capra hircus. This is the first report of molecular identification of G. crumenifer from this part of India. PMID:25548426

Kumar, Ashwani; Verma, Chandni; Singh, Hridaya Shanker

2014-01-01

234

Protostomia: Lophotrochozoa: Annelida Platyhelminthes  

E-print Network

worms · Marine, freshwater, damp terrestrial · Coelom · Closed circulatory system · Complete gut with segmental ganglia Circulatory system vessels Subpharyngeal ganglion Mouth Cerebral ganglia Anus #12;Annelida with anus · Well-developed nervous system · Metanephridia · Paired, segmental setae/chaetae · Well developed

235

Protostomia: Ecdysozoa: Nematoda Platyhelminthes  

E-print Network

appendages · ¾ of all known animals! #12;Uniramia: Myriapoda · Centipedes, millipedes #12;Myriapoda Figure 33.34 · Diplopods (millipedes): 2 pairs of legs/segment · Eat dead plant matter · Chilopods (centipedes): 1 pair

236

Platyhelminth mitochondrial DNA: Evidence for early evolutionary origin of a tRNA ser AGN that contains a dihydrouridine arm replacement loop, and of serine-specifying AGA and AGG codons  

Microsoft Academic Search

Summary  The nucleotide sequence of a segment of the mitochondrial DNA (mtDNA) molecule of the liver flukeFasciola hepatica (phylum Platyhelminthes, class Trematoda) has been determined, within which have been identified the genes for tRNAala, tRNAasp, respiratory chain NADH dehydrogenase subunit I (ND1), tRNAasn, tRNApro, tRNAile, tRNAlys, ND3, tRNAserAGN, tRNAtrp, and cytochromec oxidase subunit I (COI). The 11 genes are arranged in

James R. Garey; David R. Wolstenholme

1989-01-01

237

Toxicity of selenium (Na sub 2 SeO sub 3 ) and mercury (HgCl sub 2 ) on the planarian Dugesia gonocephala  

SciTech Connect

The toxicity of selenium (Na{sub 2}SeO{sub 3}) and mercury (HgCl{sub 2}) was determined by using a freshwater planarian which is particularly sensitive to pollution, and belongs to a fissiparous breed of Dugesia gonocephala. The mortality and fissiparity frequency of the subjects were studied. They were exposed to intense treatments (48 hours) or for medium to long periods of time (21 days) to either the single compounds or a combination of both, and were fed or fasting. The lethal effect of sodium selenite is correlated to the food intake, whereas the toxicity of mercurous chloride is probably the result of a fixative effect which does not depend on feeding. The 21-day treatment with the first compound has a non-negligible lethal effect which is probably due to an accumulation phenomenon. At doses where an antioxidant effect prevails, fissiparity is stimulated. On the other hand, the second compound reduces reproduction frequency to half the base values. Compared to the Paracentrotus lividus, the Dugesia gonocephala offers various advantages concerning toxicological experiments; besides being easier to handle in the laboratory, it is available all year round and is not subject to seasonal cycles. It is also more susceptible to the toxic effect of mercury, which is a common and highly toxic pollutant, than the sea urchin.

Congiu, A.M.; Casu, S.; Ugazio, G. (Istituto di Genetica (Italy))

1989-10-01

238

A common origin of complex life cycles in parasitic flatworms: evidence from the complete mitochondrial genome of Microcotyle sebastis (Monogenea: Platyhelminthes)  

PubMed Central

Background The parasitic Platyhelminthes (Neodermata) contains three parasitic groups of flatworms, each having a unique morphology, and life style: Monogenea (primarily ectoparasitic), Trematoda (endoparasitic flukes), and Cestoda (endoparasitic tapeworms). The evolutionary origin of complex life cyles (multiple obligate hosts, as found in Trematoda and Cestoda) and of endo-/ecto-parasitism in these groups is still under debate and these questions can be resolved, only if the phylogenetic position of the Monogenea within the Neodermata clade is correctly estimated. Results To test the interrelationships of the major parasitic flatworm groups, we estimated the phylogeny of the Neodermata using complete available mitochondrial genome sequences and a newly characterized sequence of a polyopisthocotylean monogenean Microcotyle sebastis. Comparisons of inferred amino acid sequences and gene arrangement patterns with other published flatworm mtDNAs indicate Monogenea are sister group to a clade of Trematoda+Cestoda. Conclusion Results confirm that vertebrates were the first host for stem group neodermatans and that the addition of a second, invertebrate, host was a single event occurring in the Trematoda+Cestoda lineage. In other words, the move from direct life cycles with one host to complex life cycles with multiple hosts was a single evolutionary event. In association with the evolution of life cycle patterns, our result supports the hypothesis that the most recent common ancestor of the Neodermata giving rise to the Monogenea adopted vertebrate ectoparasitism as its initial life cycle pattern and that the intermediate hosts of the Trematoda (molluscs) and Cestoda (crustaceans) were subsequently added into the endoparasitic life cycles of the Trematoda+Cestoda clade after the common ancestor of these branched off from the monogenean lineage. Complex life cycles, involving one or more intermediate hosts, arose through the addition of intermediate hosts and not the addition of a vertebrate definitive host. Additional evidence is required from monopisthocotylean monogeneans in order to confirm the monophyly of the group. PMID:17270057

Park, Joong-Ki; Kim, Kyu-Heon; Kang, Seokha; Kim, Won; Eom, Keeseon S; Littlewood, DTJ

2007-01-01

239

Schmidtea mediterranea phylogeography: an old species surviving on a few Mediterranean islands?  

PubMed Central

Background Schmidtea mediterranea (Platyhelminthes, Tricladida, Continenticola) is found in scattered localities on a few islands and in coastal areas of the western Mediterranean. Although S. mediterranea is the object of many regeneration studies, little is known about its evolutionary history. Its present distribution has been proposed to stem from the fragmentation and migration of the Corsica-Sardinia microplate during the formation of the western Mediterranean basin, which implies an ancient origin for the species. To test this hypothesis, we obtained a large number of samples from across its distribution area. Using known and new molecular markers and, for the first time in planarians, a molecular clock, we analysed the genetic variability and demographic parameters within the species and between its sexual and asexual populations to estimate when they diverged. Results A total of 2 kb from three markers (COI, CYB and a nuclear intron N13) was amplified from ~200 specimens. Molecular data clustered the studied populations into three groups that correspond to the west, central and southeastern geographical locations of the current distribution of S. mediterranea. Mitochondrial genes show low haplotype and nucleotide diversity within populations but demonstrate higher values when all individuals are considered. The nuclear marker shows higher values of genetic diversity than the mitochondrial genes at the population level, but asexual populations present lower variability than the sexual ones. Neutrality tests are significant for some populations. Phylogenetic and dating analyses show the three groups to be monophyletic, with the west group being the basal group. The time when the diversification of the species occurred is between ~20 and ~4 mya, although the asexual nature of the western populations could have affected the dating analyses. Conclusions S. mediterranea is an old species that is sparsely distributed in a harsh habitat, which is probably the consequence of the migration of the Corsica-Sardinia block. This species probably adapted to temperate climates in the middle of a changing Mediterranean climate that eventually became dry and hot. These data also suggest that in the mainland localities of Europe and Africa, sexual individuals of S. mediterranea are being replaced by asexual individuals that are either conspecific or are from other species that are better adapted to the Mediterranean climate. PMID:21943163

2011-01-01

240

Classification of the Temnocephaloidea (Platyhelminthes)  

Microsoft Academic Search

A brief historical survey of the classification of the Temnocephaloidea is presented. Schemes of classification are discussed in the light of recent anatomical and ultrastructural studies on Temnocephala. The Temnocephaloidea are not closely related to the Monogenea; however, they show an immediate affinity with the Turbellaria, which should be reflected by their taxonomic position. Inclusion of the group within the

Joan Bowman Williams

1981-01-01

241

Eumetazoa: Bilateria Bilateral symmetry  

E-print Network

;Platyhelminthes Protostomia: Lophotrochozoa: Platyhelminthes Porifera Cnidaria Platyhelminthes Other Lophotrochozoa Deuterostomes Ecdysozoa #12;Platyhelminthes Protostomia: Lophotrochozoa: Platyhelminthes Figure 32.11 #12;Platyhelminthes Protostomia: Lophotrochozoa: Platyhelminthes · Flatworms · Marine, freshwater

242

INTRODUCTION The phylum Platyhelminthes (flatworms) consists of  

E-print Network

significantly to fundamental biomedical research in the areas of tissue regeneration, stem cell maintenance possess large populations of undifferentiated mesenchymal stem cells, the study of which could contribute and degenerative disorders. In most free- living species these stem cells, which are often referred to as neoblasts

Alvarado, Alejandro Sánchez

243

Occurrence of Echeneibothrium (Platyhelminthes, Cestoda) in the  

E-print Network

. Nu- merous macrophagous hemocytes (M) surround the connective tissue capsule (eT) and nearby tissue of the cestode Echeneibothrium sp., were found within the connective tissue of the gonads in calico scallops by a connective tissue capsule of host ori- gin and were located immediately subjacent to the wall ofthe gut. Each

244

Nutritional adaptations to parasitism within the Platyhelminthes  

Microsoft Academic Search

Some of the most significant alterations to the basic turbellarian plan are evident in the adaptations that relate to the acquisition of food by parasitic flatworms, reflecting the most potent of selection pressures in initiating and maintaining the host-parasite association. Nutritionally, ectoparasitic monogeneans show most correspondence with the predatory turbellarians, with certain monopisthocotylean members feeding by means of a protrusible

David W. Halton

1997-01-01

245

Stem cells and the Planarian Schmidtea mediterranea  

Microsoft Academic Search

In recent years, stem cells have been heralded as potential therapeutic agents to address a large number of degenerative diseases. Yet, in order to rationally utilize these cells as effective therapeutic agents, and\\/or improve treatment of stem-cell-associated malignancies such as leukemias and carcinomas, a better understanding of the basic biological properties of stem cells needs to be acquired. A major

Alejandro Sánchez Alvarado

2007-01-01

246

Phylum Platyhelminthes Most parasitic platyhelminths belong to one of three classes: Mono-  

E-print Network

are distinguished from sporocysts by the presence of a mouth and digestive system. They are usually motile and can and female reproductive hermaphrodite protogynous protandrous systems. Usually both systems develop simultaneously or the male system develops first (protandrous) but in Gyrodactylid monogenea, the female system

Schluter, Dolph

247

Diversity of introduced terrestrial flatworms in the Iberian Peninsula: a cautionary tale  

PubMed Central

Many tropical terrestrial planarians (Platyhelminthes, Geoplanidae) have been introduced around the globe. One of these species is known to cause significant decline in earthworm populations, resulting in a reduction of ecological functions that earthworms provide. Flatworms, additionally, are a potential risk to other species that have the same dietary needs. Hence, the planarian invasion might cause significant economic losses in agriculture and damage to the ecosystem. In the Iberian Peninsula only Bipalium kewense Moseley, 1878 had been cited till 2007. From that year on, four more species have been cited, and several reports of the presence of these animals in particular gardens have been received. In the present study we have: (1) analyzed the animals sent by non-specialists and also the presence of terrestrial planarians in plant nurseries and garden centers; (2) identified their species through morphological and phylogenetic molecular analyses, including representatives of their areas of origin; (3) revised their dietary sources and (4) used Species Distribution Modeling (SDM) for one species to evaluate the risk of its introduction to natural areas. The results have shown the presence of at least ten species of alien terrestrial planarians, from all its phylogenetic range. International plant trade is the source of these animals, and many garden centers are acting as reservoirs. Also, landscape restoration to reintroduce autochthonous plants has facilitated their introduction close to natural forests and agricultural fields. In conclusion, there is a need to take measures on plant trade and to have special care in the treatment of restored habitats. PMID:24949245

Álvarez-Presas, Marta; Tudó, Àngels; Jones, Hugh; Riutort, Marta

2014-01-01

248

Stem cell systems and regeneration in planaria.  

PubMed

Planarians are members of the Platyhelminthes (flatworms). These animals have evolved a remarkable stem cell system. A single pluripotent adult stem cell type ("neoblast") gives rise to the entire range of cell types and organs in the planarian body plan, including a brain, digestive-, excretory-, sensory- and reproductive systems. Neoblasts are abundantly present throughout the mesenchyme and divide continuously. The resulting stream of progenitors and turnover of differentiated cells drive the rapid self-renewal of the entire animal within a matter of weeks. Planarians grow and literally de-grow ("shrink") by the food supply-dependent adjustment of organismal turnover rates, scaling body plan proportions over as much as a 50-fold size range. Their dynamic body architecture further allows astonishing regenerative abilities, including the regeneration of complete and perfectly proportioned animals even from tiny tissue remnants. Planarians as an experimental system, therefore, provide unique opportunities for addressing a spectrum of current problems in stem cell research, including the evolutionary conservation of pluripotency, the dynamic organization of differentiation lineages and the mechanisms underlying organismal stem cell homeostasis. The first part of this review focuses on the molecular biology of neoblasts as pluripotent stem cells. The second part examines the fascinating mechanistic and conceptual challenges posed by a stem cell system that epitomizes a universal design principle of biological systems: the dynamic steady state. PMID:23138344

Rink, Jochen C

2013-03-01

249

Developmental diversity in free-living flatworms  

PubMed Central

Flatworm embryology has attracted attention since the early beginnings of comparative evolutionary biology. Considered for a long time the most basal bilaterians, the Platyhelminthes (excluding Acoelomorpha) are now robustly placed within the Spiralia. Despite having lost their relevance to explain the transition from radially to bilaterally symmetrical animals, the study of flatworm embryology is still of great importance to understand the diversification of bilaterians and of developmental mechanisms. Flatworms are acoelomate organisms generally with a simple centralized nervous system, a blind gut, and lacking a circulatory organ, a skeleton and a respiratory system other than the epidermis. Regeneration and asexual reproduction, based on a totipotent neoblast stem cell system, are broadly present among different groups of flatworms. While some more basally branching groups - such as polyclad flatworms - retain the ancestral quartet spiral cleavage pattern, most flatworms have significantly diverged from this pattern and exhibit unique strategies to specify the common adult body plan. Most free-living flatworms (i.e. Platyhelminthes excluding the parasitic Neodermata) are directly developing, whereas in polyclads, also indirect developers with an intermediate free-living larval stage and subsequent metamorphosis are found. A comparative study of developmental diversity may help understanding major questions in evolutionary biology, such as the evolution of cleavage patterns, gastrulation and axial specification, the evolution of larval types, and the diversification and specialization of organ systems. In this review, we present a thorough overview of the embryonic development of the different groups of free-living (turbellarian) platyhelminths, including the Catenulida, Macrostomorpha, Polycladida, Lecithoepitheliata, Proseriata, Bothrioplanida, Rhabdocoela, Fecampiida, Prolecithophora and Tricladida, and discuss their main features under a consensus phylogeny of the phylum. PMID:22429930

2012-01-01

250

Marine macrostomorpha (platyhelminthes, rhabditophora) from the algarve (southern portugal).  

PubMed

Ten species of Macrostomorpha were found in marine environments of the Algarve (Portugal). Six of them were found in the Ria Formosa, a vast intertidal euryhaline lagoon system that dominates the most Eastern coast of the Algarve: two unidentified species of Microstomum Schmidt, 1848, Macrostomum cf. rubrocinctum Ax, 1951 and two unidentified species of Macrostomum Schmidt, 1848, Paromalostomum dubium (de Beauchamps, 1927), Paromalostomum minutum Rieger, 1971 and Cylindromacrostomum faroensis n.sp.. Comparison of this species with C. mediterraneum (Ax, 1955) and the species from Venice, considered to be C. mediterraneum by Rieger (1977), leads to the conclusion that the individuals studied by Rieger are in fact representatives of a separate species, C. riegeri n.sp.. Acanthomacrostomum spiculiferum Papi & Swedmark, 1959 was found in the Atlantic, 10-15 m deep, near the western coast of the Algarve. Haplopharynx papii n. sp. occurs on the beach exposed to the Atlantic as well as in the Ria Formosa. All identified and previously known (marine) species found in the Algarve had been found before, either in the Atlantic or in the Mediterranean basin.  PMID:25544102

Schockaert, Ernest R

2014-01-01

251

Evolutionary biology of parasitic platyhelminths: The role of molecular phylogenetics  

Microsoft Academic Search

As our appreciation of the diversity within the flatworms has grown, so too has our curiosity about the ways in which these varied creatures are related to one another. In particular, the parasitic groups (trematodes, cestodes and monogeneans have been the focus of enquiry. Until recently, morphology, anatomy and life histories have provided the raw data for building hypotheses on

D. Blair; A. Campos; M. P. Cummings; J. P. Laclette

1996-01-01

252

The major parasitic platyhelminth classes — progressive or regressive evolution?  

Microsoft Academic Search

The evolution of certain ontogenetic processes appears to be of special importance to subsequent evolution of a phyletic line, and their occurrence suggests there are various ‘evolutionary capacity levels’ occupied by major taxa. Two groups that are at the same evolutionary capacity level probably originated in common within that level, which in turn is often shared with several other groups.

G. Malmberg

1986-01-01

253

Salinity tolerance of Gyrodactylus salaris (Platyhelminthes, Monogenea): laboratory studies  

Microsoft Academic Search

The salinity tolerance of the freshwater monogenean Gyrodactylus salaris, infecting Atlantic salmon (Salmo salar) parr, was studied experimentally. Following direct transfer of infected fish from fresh water to 5.0‰ salinity, parasite population growth increased at the same rate as in fresh water and was positively correlated with temperature (1.4, 6.0, and 12.0°C). In 7.5‰ salinity the populations declined and became

Arnulf Soleng; Tor A. Bakke

1997-01-01

254

Embryonic Muscle Development of Convoluta pulchra (Turbellaria–Acoelomorpha, Platyhelminthes)  

Microsoft Academic Search

We studied the embryonic development of body-wall musculature in the acoel turbellarian Convoluta pulchra by fluorescence microscopy using phalloidin-bound stains for F-actin. During stage 1, which we define as development prior to 50% of the time between egg-laying and hatching, actin was visible only in zonulae adhaerentes of epidermal cells. Subsequent development of muscle occurred in two distinct phases: first,

Peter Ladurner; Reinhard Rieger

2000-01-01

255

New primers for DNA barcoding of digeneans and cestodes (Platyhelminthes).  

PubMed

Digeneans and cestodes are species-rich taxa and can seriously impact human health, fisheries, aqua- and agriculture, and wildlife conservation and management. DNA barcoding using the COI Folmer region could be applied for species detection and identification, but both 'universal' and taxon-specific COI primers fail to amplify in many flatworm taxa. We found that high levels of nucleotide variation at priming sites made it unrealistic to design primers targeting all flatworms. We developed new degenerate primers that enabled acquisition of the COI barcode region from 100% of specimens tested (n=46), representing 23 families of digeneans and 6 orders of cestodes. This high success rate represents an improvement over existing methods. Primers and methods provided here are critical pieces towards redressing the current paucity of COI barcodes for these taxa in public databases. This article is protected by copyright. All rights reserved. PMID:25490869

Van Steenkiste, Niels; Locke, Sean A; Castelin, Magalie; Marcogliese, David J; Abbott, Cathryn L

2014-12-10

256

Cell death and tissue remodeling in planarian regeneration  

Microsoft Academic Search

Many long-lived organisms, including humans, can regenerate some adult tissues lost to physical injury or disease. Much of the previous research on mechanisms of regeneration has focused on adult stem cells, which give rise to new tissue necessary for the replacement of missing body parts. Here we report that apoptosis of differentiated cells complements stem cell division during regeneration in

Jason Pellettieri; Patrick Fitzgerald; Shigeki Watanabe; Joel Mancuso; Douglas R. Green; Alejandro Sánchez Alvarado

2010-01-01

257

Small, mostly single-celled eukaryotes Polyphyletic -"Protista" is not a good name  

E-print Network

Eumetazoa Metazoa Porifera Cnidaria Ctenophora Ectoprocta Brachiopoda Echinodermata Chordata Platyhelminthes Ctenophora Cnidaria Acoela Echinodermata Chordata Platyhelminthes Rotifera Ectoprocta Brachiopoda Mollusca

258

InternationalJournalfor Parasitology Vol.21, No. 7, pp. 821-838, 1991 Printed in Great Britain  

E-print Network

IN THE MONOGENEA (PLATYHELMINTHES), BASED UPON A PARSIMONY ANALYSIS OF SPERMIOGENETIC AND SPERMATOZOAL.Cladisticstudyin the Monogenea(Platyhelminthes),based upon aparsimony analysis of spermiogenetic and spermatozoal: Monogenea, Platyhelminthes; Polyopisthocotylea; MonopisthocotyIea; phylogeny; cladistics; systematics

259

A Reevaluation of the Taxonomy of the Mesocoelium monas Complex (Platyhelminthes: Digenea: Mesoceliidae)  

E-print Network

available worldwide and based on the presence or absence of tegumental spines, the ratio of the width of the ventral sucker to the width of the oral sucker, egg length and width, and the posterior extent of the uterus recognized only 7 species... subterminal; oral sucker wider than long, 256 (221?290) long by 269 (213?325) wide; prepharynx absent; pharynx wider than long, 90 (88?91) long by 103 (91?107) wide, ratio of width of pharynx to width of oral sucker 1:3.1 (1:3.0?1:3.2); esophagus...

Calhoun, Dana Marie

2012-07-16

260

Comparative genomic analysis of aspartic proteases in eight parasitic platyhelminths: Insights into functions and evolution.  

PubMed

We performed genome-wide identifications and comparative genomic analyses of the predicted aspartic proteases (APs) from eight parasitic flatworms, focusing on their evolution, potentials as drug targets and expression patterns. The results revealed that: i) More members of family A01 were identified from the schistosomes than from the cestodes; some evidence implied gene loss events along the class Cestoda, which may be related to the different ways to ingest host nutrition; ii) members in family A22 were evolutionarily highly conserved among all the parasites; iii) one retroviral-like AP in family A28 shared a highly similar predicted 3D structure with the HIV protease, implying its potential to be inhibited by HIV inhibitor-like molecules; and iiii) retrotransposon-associated APs were extensively expanded among these parasites. These results implied that the evolutionary histories of some APs in these parasites might relate to adaptations to their parasitism and some APs might have potential serving as intervention targets. PMID:25595353

Wang, Shuai; Wei, Wei; Luo, Xuenong; Wang, Sen; Hu, Songnian; Cai, Xuepeng

2015-03-15

261

A new genus with six new species of Typhlopolycystidinae Evdonin, 1977 (Platyhelminthes, Kalyptorhynchia, Polycystididae).  

PubMed

Five new species of the new taxon Brunetorhynchus n. gen. are described: B. deconincki n. sp., B. microstylis n. sp. and B. complicatus n. sp. are from the Mediterranean, B. canariensis n. sp. is from the Canary Island Lanzarote, B. cannoni n. sp. is from the Australian East coast and one species from the Galapagos, formerly described as Limipolycystis spec., is transferred to the new genus as B. dubius n. sp.. As in Limipolycystis, these species have a single stylet, (accessory stylet type II), an accessory secretion vesicle (type II) and a prostate vesicle (type III) in the male atrium, although the latter vesicle is absent in some species. Unlike the species of Limipolycystis, where the seminal receptacle is a sclerotized tubule, the species of the new taxon have a pear-shaped seminal receptacle on the oviduct.  PMID:24869820

Schockaert, Ernest R; Martens, Paul M; Revis, Nathalie; Janssen, Toon; Willems, Wim; Artois, Tom J

2014-01-01

262

Platyhelminthes (vers plats) Acoelomate,Amplification larvaire, Cellule flamme, Cphalisation, Cercaire, Cestodes,  

E-print Network

Brachiopoda Phoronida Arthropoda Onychophora Tardigrada Nematomorpha Nematoda Priapulida Kinorhyncha Sipuncula Nemertea Bryozoa Brachiopoda Phoronida Arthropoda Onychophora Tardigrada Nematomorpha Nematoda

Blouin-Demers, Gabriel

263

Phylogenetic relationships within the polyopisthocotylean monogeneans (Platyhelminthes) inferred from partial 28S rDNA sequences.  

PubMed

Recent studies based on molecular data (18S rDNA and partial 28S rDNA) and morphology did not resolve a terminal polytomy within the Polyopisthocotylea. Here, we have used sequences from the full domain D2 of the 28S rDNA for 24 species (18 new sequences) with three phylogenetic methods, maximum parsimony, neighbour-joining and maximum likelihood, to infer the relationships among the Polyopisthocotylea. The analysis of the domain D2 of the 28S rDNA has been performed on two data sets. The first one, complete, included the Polystomatidae as the outgroup in order to infer general relationships, and the second one, reduced, excluded the Polystomatidae and the polyopisthocotylean parasites of chondrichthyans, but used the Mazocraeidae as the outgroup in order to resolve the relationships between the terminal groups. The topology found, sustained by high bootstrap and decay index value, is: (outgroup (Chimaericolidae (Mazocraeidae (Gastrocotylinea, other Polyopisthocotylea)))). The polyopisthocotylean parasites of chondrichthyans are the sister-group of the polyopisthocotylean parasites of teleosts. In the latter, the Mazocraeidae, essentially parasites of Clupeidae, have a basal position. The polytomy between Gastrocotylinea, Discocotylinea and Microcotylinea is partially resolved in this study for the first time: the Gastrocotylinea are the sister-group of an unresolved group including the Microcotylinea, Discocotylinea and Plectanocotylidae. Inclusion of the Plectanocotylidae in the suborder Mazocraeinea is rejected. Monophyly of the Microcotylinea and Plectanocotylidae is confirmed, but monophyly of the Discocotylinea is questioned by the exclusion of Diplozoon. PMID:11306118

Jovelin, R; Justine, J L

2001-04-01

264

On the morphology and karyology of the genus Archilopsis (Meixner) (Platyhelminthes, Proseriata)  

Microsoft Academic Search

Two new Archilopsis species are described: Archilopsis marifuga sp.n. and Archilopsis arenaria sp.n.; Archilopsis unipunctata (Fabricius, 1826) and Archilopsis spinosa (Jensen, 1878) are redescribed. The latter taxon is re-established. The descriptions are based on morphological and karyological data. The four species of the genus can unequivocally be recognized by the morphology of the cirrus and the presence or absence of

Paul M. Martens; Marco C. Curini-Galletti; Ileana Puccinelli

1989-01-01

265

Neuropeptides in free-living and parasitic flatworms (Platyhelminthes). An immunocytochemical study  

Microsoft Academic Search

The nervous systems of the turbellarians Microstomum lineare and Polycelis nigra and of the cestodes Diphyllobothrium dendriticum and Schistocephalus solidus were studied by means of the peroxidase-antiperoxidase (PAP) immunocytochemical method, with the use of antisera to the neuropeptides FMRF-amide, vasotocin, leu-enkephalin, met-enkephalin, neurotensin, somatostatin, and VIP, and to the bioamine serotonin. Anti-FMRF-amide positive perikarya and fibers occurred in all species,

Marianne Wikgren; Maria Reuter; Margaretha Gustafsson

1986-01-01

266

MicroRNA loci support conspecificity of Gyrodactylus salaris and Gyrodactylus thymalli (Platyhelminthes: Monogenea).  

PubMed

The monogenean flatworm Gyrodactylus salaris is a serious threat to wild and farmed Atlantic salmon stocks in Norway. Morphologically, the closely related but harmless Gyrodactylus thymalli on grayling can hardly be distinguished from G. salaris. Until now, molecular approaches could not resolve unambiguously whether G. salaris and G. thymalli represent just one polytypic species, two polytypic species or a complex of more than two species. In the first known genome-wide analysis utilizing 37 conserved microRNA loci, the genetic differentiation of seven populations of G. salaris and G. thymalli was assessed. The concatenated alignment spanned 21,742bp including 62 variable positions. A neighbor-joining cluster analysis did not support any host-based or mitochondrial haplotype-based grouping of strains. We conclude that a two species concept for G. salaris and G. thymalli does not reflect meaningful biological entities. Instead, G. salaris and G. thymalli are just one species comprising several pathogenic and non-pathogenic strains on various primary hosts. Following the International Code for Zoological Nomenclature, G. salaris Malmberg, 1957 is the valid species name with G. thymalli Žit?an, 1960 becoming the junior synonym. Accordingly, the range of G. salaris is significantly increased, given that formerly G. salaris-free countries such as e.g., Great Britain are now within the species' natural range. The synonymization of G. salaris and G. thymalli implies severe challenges to current disease management routines, which assume that G. salaris and G. thymalli are readily distinguishable. Protocols for reliable identification of pathogenic and non-pathogenic strains of G. salaris need to be developed. PMID:24998346

Fromm, Bastian; Burow, Susann; Hahn, Christoph; Bachmann, Lutz

2014-10-01

267

Spermiogenesis and spermatozoon of Echinostoma caproni ( Platyhelminthes, Digenea): transmission and scanning electron microscopy, and tubulin immunocytochemistry  

Microsoft Academic Search

Spermiogenesis and the spermatozoon of Echinostoma caproni (from experimentally infested laboratory mice) were investigated by several methods. Transmission electron microscopy shows that spermiogenesis consists of a proximo-distal fusion of three processes followed by elongation of the spermatid. Scanning electron microscopy shows that the spermatozoon is a filiform cell, 235 ?m in length, with a cylindrical anterior extremity and a broader

C. Iomini; J.-L. Justine

1997-01-01

268

A molecular approach for the identification of meiofaunal turbellarians (Platyhelminthes, Turbellaria)  

Microsoft Academic Search

In the absence of reliable morphological characters, or in conjunction with morphology-based identifications, meiofaunal turbellarians may also be identified using the nucleotide sequence of a portion of the large subunit of the ribosomal RNA (26\\/28S rRNA). A 284 base pair-long region of the 26\\/28S rRNA has been identified by isolating genomic DNA from ten species of turbellarians belonging to four

M. K. Litvaitis; G. Nunn; W. K. Thomas; T. D. Kocher

1994-01-01

269

The Interrelationships of Proseriata (Platyhelminthes: Seriata) Tested with Molecules and Morphology  

Microsoft Academic Search

Proseriate flatworms are common members of the interstitial benthic fauna worldwide, predominantly occupying marine environments. As minute animals, having relatively few characters useful for cladistic analysis, they have been difficult to present in a phylogenetic framework using morphology alone. Here we present a new morphological matrix consisting of 16 putatively homologous characters and two molecular data sets to investigate further

D. T. J. Littlewood; Marco Curini-Galletti; Elisabeth A. Herniou

2000-01-01

270

Host-specificity of monogenean (platyhelminth) parasites: a role for anterior adhesive areas?  

Microsoft Academic Search

Monogeneans (flatworms) are among the most host-specific of parasites in general and may be the most host-specific of all fish parasites. Specificity, in terms of a restricted spatial distribution within an environment, is not unique to parasites and is displayed by some fungi, insects, birds, symbionts and pelagic larvae of free-living marine invertebrates. The nature of cues, how “habitats” are

Ian D. Whittington; Bronwen W. Cribb; Tamarind E. Hamwood; Judy A. Halliday

2000-01-01

271

Linking specialisation to diversification in the Diplectanidae Bychowsky 1957 (Monogenea, Platyhelminthes)  

Microsoft Academic Search

The hypothesis of a positive correlation between host specificity and taxonomic diversification was tested in a family of\\u000a fish ectoparasites, the Diplectanidae Bychowsky 1957 (Monogenea). A comparative analysis of correlation of species richness\\u000a with host specificity was performed using an adapted independent contrasts method. In order to control for phylogenetic effects,\\u000a a phylogenetic tree of the genera in the Diplectanidae

Y. Desdevises; S. Morand; G. Oliver

2001-01-01

272

STUDIES ON FEEDING, DIGESTION, AND FOOD STORAGE IN FREE-LIVING FLATWORMS (PLATYHELMINTHES : TURBELLARIA)  

Microsoft Academic Search

Investigations upon turbellarian nutrition (summarized by Hyman, 1951 and Yonge, 1954) have so far dealt mainly with triclads, where intracellular digestion has been demonstrated but the possibility of some supplementary intraluminar di gestion not fully explored. Triclad nutrition has therefore been re-examined, us ing Polycelis cornuta, and the opportunity taken to make comparable investigations on representatives of the other turbellarian

J. B. JENNINGS

273

Molecular systematics of the Acoela (Acoelomorpha, Platyhelminthes) and its concordance with morphology  

Microsoft Academic Search

The phylogenetic relationships of the lower worm group Acoela were investigated using newly obtained nuclear 18S rDNA sequences from 16 acoels in combination with 16 acoel sequences available on GenBank from other laboratories. Parsimony and maximum likelihood analyses of the molecular data supported the concept that the Acoela is monophyletic; however, the gene tree produced by these analyses conflicts with

Matthew D. Hooge; Pilar A. Haye; Seth Tyler; Marian K. Litvaitis; Irv Kornfield

2002-01-01

274

Coevolution of the Monogenoidea (Platyhelminthes) based on a revised hypothesis of parasite phylogeny  

Microsoft Academic Search

A revised hypothesis for the phylogeny of the Subclass Polyonchoinea (Monogenoidea) was contructed employing phylogenetic systematics. The Acanthocotylidae (formerly of the Order Capsalidea) is transferred to the Order Gyrodactylidea based on this analysis. The new phylogeny is used to determine coevolutionary relationships of the familial taxa of Monogenoidea with their hosts. The coevolutionary analysis suggests that the Monogenoidea apparently underwent

Walter A. Boeger; Delane C. Kritsky

1997-01-01

275

Phylogeny and a revised classification of the Monogenoidea Bychowsky, 1937 (Platyhelminthes)  

Microsoft Academic Search

A hypothesis (CI=57.3%) on the evolutionary relationships of families comprising the class Monogenoidea is proposed based on 141 character states in 47 homologous series and employing phylogenetic systematics. Based on the analysis, three subclasses, the Polyonchoinea, Polystomatoinea and Oligonchoinea, are recognised. The analysis supports independent origins of the Montchadskyellidae within the Polyonchoinea and of the Neodactylodiscidae and Amphibdellatidae within the

Walter A. Boeger; Delane C. Kritsky

1993-01-01

276

Spermiogenesis and submicroscopic morphology of spermatozoa in Myozona purpurea (Platyhelminthes, Macrostomida)  

Microsoft Academic Search

Within the unpaired testis, spermatogonia, spermatocytes, spermatids and spermatozoa were found. In early spermatids, mitochondria take perinuclear positions and centrioles a diplosomal arrangement. Rootlet-like striated differentiations occur in slightly more advanced stages. Then a conical cytoplasmic projection develops, supported by a single row of closely spaced microtubules. At this stage of maturation, giant Golgi stacks occur within the cytoplasm of

BEATE SOPOTT-EHLERS; ULRICH EHLERS

1998-01-01

277

The first troglobitic species of freshwater flatworm of the suborder Continenticola (Platyhelminthes) from South America  

PubMed Central

Abstract Brazilian cave diversity, especially of invertebrates, is poorly known. The Bodoquena Plateau, which is located in the Cerrado Biome in central Brazil, has approximately 200 recorded caves with a rich system of subterranean water resources and high troglobitic diversity. Herein we describe a new troglobitic species of Girardia that represents the first obligate cave-dwelling species of the suborder Continenticola in South America. Specimens of the new species, which occur in a limestone cave in the Bodoquena Plateau, in the Cerrado biome, are unpigmented and eyeless. Species recognition in the genus Girardia is difficult, due to their great morphological resemblance. However, the new species can be easily recognized by a unique feature in its copulatory apparatus, namely a large, branched bulbar cavity with multiple diverticula. PMID:25632242

de Souza, Stella Teles; Morais, Ana Laura Nunes; Cordeiro, Lívia Medeiros; Leal-Zanchet, Ana Maria

2015-01-01

278

First records of Cotylea (Polycladida, Platyhelminthes) for the Atlantic coast of the Iberian Peninsula  

PubMed Central

Abstract A study of polyclad fauna of the Atlantic coast of the Iberian Peninsula was carried out from 2010 to 2013. The paper reports nine new records belonging to three Cotylean families: the family Euryleptidae Lang, 1884, Pseudocerotidae Lang, 1884 and the family Prosthiostomidae Lang, 1884, and describes one new species, Euryleptodes galikias sp. n. PMID:24843268

Noreña, Carolina; Marquina, Daniel; Perez, Jacinto; Almon, Bruno

2014-01-01

279

Parasite hybridization in African Macrogyrodactylus spp. (Monogenea, Platyhelminthes) signals historical host distribution.  

PubMed

Macrogyrodactylus spp. from the gills of Clarias gariepinus in Zimbabwe and Kenya, and C. anguillaris in Senegal were identified using haptoral sclerite morphology and by sequencing the nuclear ribosomal DNA internal transcribed spacers (ITS) 1 and 2, partial 18S and the complete 5.8S rRNA gene. A molecular phylogeny was constructed using all sequenced Macrogyrodactylus species to date. Based on morphology, Macrogyrodactylus congolensis, M. heterobranchii, M. clarii, and M. karibae were identified, with one specimen from Zimbabwe displaying morphological features that were intermediate between M. heterobranchii and M. clarii. In the intermediate form, the partial 18S and ITS1 sequence was identical to that of M. clarii while the remaining ITS1 and complete ITS2 region was almost identical to M. heterobranchii as was the partial cox1 fragment, thus strongly suggesting a hybrid origin. At present, the catfish host of M. heterobranchii and M. clarii do not co-occur in southern Zimbabwe; this hybridization event is therefore proof of historical sympatry of both fish species. PMID:20444301

Barson, Maxwell; Prikrylová, Iva; Vanhove, Maarten P M; Huyse, Tine

2010-09-01

280

The first troglobitic species of freshwater flatworm of the suborder Continenticola (Platyhelminthes) from South America.  

PubMed

Brazilian cave diversity, especially of invertebrates, is poorly known. The Bodoquena Plateau, which is located in the Cerrado Biome in central Brazil, has approximately 200 recorded caves with a rich system of subterranean water resources and high troglobitic diversity. Herein we describe a new troglobitic species of Girardia that represents the first obligate cave-dwelling species of the suborder Continenticola in South America. Specimens of the new species, which occur in a limestone cave in the Bodoquena Plateau, in the Cerrado biome, are unpigmented and eyeless. Species recognition in the genus Girardia is difficult, due to their great morphological resemblance. However, the new species can be easily recognized by a unique feature in its copulatory apparatus, namely a large, branched bulbar cavity with multiple diverticula. PMID:25632242

de Souza, Stella Teles; Morais, Ana Laura Nunes; Cordeiro, Lívia Medeiros; Leal-Zanchet, Ana Maria

2015-01-01

281

Comparative Genomics of Flatworms (Platyhelminthes) Reveals Shared Genomic Features of Ecto- and Endoparastic Neodermata  

PubMed Central

The ectoparasitic Monogenea comprise a major part of the obligate parasitic flatworm diversity. Although genomic adaptations to parasitism have been studied in the endoparasitic tapeworms (Cestoda) and flukes (Trematoda), no representative of the Monogenea has been investigated yet. We present the high-quality draft genome of Gyrodactylus salaris, an economically important monogenean ectoparasite of wild Atlantic salmon (Salmo salar). A total of 15,488 gene models were identified, of which 7,102 were functionally annotated. The controversial phylogenetic relationships within the obligate parasitic Neodermata were resolved in a phylogenomic analysis using 1,719 gene models (alignment length of >500,000 amino acids) for a set of 16 metazoan taxa. The Monogenea were found basal to the Cestoda and Trematoda, which implies ectoparasitism being plesiomorphic within the Neodermata and strongly supports a common origin of complex life cycles. Comparative analysis of seven parasitic flatworm genomes identified shared genomic features for the ecto- and endoparasitic lineages, such as a substantial reduction of the core bilaterian gene complement, including the homeodomain-containing genes, and a loss of the piwi and vasa genes, which are considered essential for animal development. Furthermore, the shared loss of functional fatty acid biosynthesis pathways and the absence of peroxisomes, the latter organelles presumed ubiquitous in eukaryotes except for parasitic protozoans, were inferred. The draft genome of G. salaris opens for future in-depth analyses of pathogenicity and host specificity of poorly characterized G. salaris strains, and will enhance studies addressing the genomics of host–parasite interactions and speciation in the highly diverse monogenean flatworms. PMID:24732282

Hahn, Christoph; Fromm, Bastian; Bachmann, Lutz

2014-01-01

282

Insight into the role of cetaceans in the life cycle of the tetraphyllideans (Platyhelminthes: Cestoda).  

PubMed

Four types of tetraphyllidean larvae infect cetaceans worldwide: two plerocercoids differing in size, 'small' (SP) and 'large' (LP), and two merocercoids referred to as Phyllobothrium delphini and Monorygma grimaldii. The latter merocercoid larvae parasitize marine mammals exclusively and exhibit a specialised cystic structure. Adult stages are unknown for any of the larvae and thus the role of cetaceans in the life cycle of these species has been a long-standing problem. The SP and LP forms are thought to be earlier stages of P. delphini and M. grimaldii that are presumed to infect large pelagic sharks that feed on cetaceans. A molecular analysis of the D2 variable region of the large subunit ribosomal DNA gene based on several individuals of each larval type collected from three Mediterranean species of cetaceans showed consistent and unique molecular signatures for each type regardless of host species or site of infection. The degree of divergence suggested that LP, P. delphini and M. grimaldii larvae may represent separate species, whereas SP may be conspecific with M. grimaldii. In all host species, individuals of SP accumulated in the gut areas in which the lymphoid tissue was especially developed. We suggest therefore that these larvae use the lymphatic system to migrate to the abdominal peritoneum and mesenteries where they develop into forms recognizable as M. grimaldii. The plerocercoid stage of P. delphini remains unknown. In a partial phylogenetic tree of the Tetraphyllidea, all larvae formed a clade that included a representative of the genus Clistobothrium, some species of which parasitize sharks such as the great white which is known to feed on cetaceans. A bibliographic examination of tetraphyllidean infections in marine mammals indicated that these larvae are acquired mostly offshore. In summary, the evidence suggests that cetaceans play a significant role in the life cycle of these larvae. In addition, it seems clear that cetaceans act as natural intermediate hosts for P. delphini and M. grimaldii, as within these hosts they undergo development from the plerocercoid stage to the merocercoid stage. Because tetraphyllidean species use fish, cephalopods and other marine invertebrates as intermediate hosts, the inclusion of cetaceans in the life cycle would have facilitated their transmission to apex predators such as the large, lamnid sharks. The biological significance of infections of LP in cetaceans is unclear, but infections do not seem to be accidental as such larvae show high prevalence and abundance as well as a high degree of site specificity, particularly in the anal crypts and bile ducts. PMID:17161403

Aznar, F J; Agustí, C; Littlewood, D T J; Raga, J A; Olson, P D

2007-02-01

283

Insight into the role of cetaceans in the life cycle of the tetraphyllideans (Platyhelminthes: Cestoda)  

Microsoft Academic Search

Four types of tetraphyllidean larvae infect cetaceans worldwide: two plerocercoids differing in size, ‘small’ (SP) and ‘large’ (LP), and two merocercoids referred to as Phyllobothrium delphini and Monorygma grimaldii. The latter merocercoid larvae parasitize marine mammals exclusively and exhibit a specialised cystic structure. Adult stages are unknown for any of the larvae and thus the role of cetaceans in the

F. J. Aznar; C. Agustí; D. T. J. Littlewood; J. A. Raga; P. D. Olson

2007-01-01

284

Molecular phylogeny and evolution of the Trypanorhyncha Diesing, 1863 (Platyhelminthes: Cestoda)  

Microsoft Academic Search

Complete ssrDNA and partial lsrDNA (D1–D3) of 31 species, mainly from the Indo-Pacific region, were sequenced and added to 66 species of the marine cestode order Trypanorhyncha; thus 35% of the 277 known species were sampled. The resulting phylogenetic tree resolved two major clades that represent trypanorhynchs originally parasitizing rajiform (skate and ray) or galeoform hosts. The tree topology supports

Harry W. Palm; Andrea Waeschenbach; Peter D. Olson; D. Timothy J. Littlewood

2009-01-01

285

Mar Biol (2007) 151:12151223 DOI 10.1007/s00227-006-0563-2  

E-print Network

belong to members of various phyla including Porifera, Cnidaria, Platyhelminthes, and Mollusca (Douglas to the well-studied cnidarians, symbiotic platyhelminth worms, and particularly acoelomorphs are the most

286

Vestigial prototroch in a basal nemertean, Carinoma tremaphoros (Nemertea; Palaeonemertea)  

E-print Network

affinities of ne- merteans. Although some authors traditionally view them as related to platyhelminthes based 1964) or platyhelminthes and nemerteans (Ivanova- Kazas 1985). Rouse (1999) suggested an apomorph

Maslakova, Svetlana

287

A proteomics approach to decipher the molecular nature of planarian stem cells  

PubMed Central

Background In recent years, planaria have emerged as an important model system for research into stem cells and regeneration. Attention is focused on their unique stem cells, the neoblasts, which can differentiate into any cell type present in the adult organism. Sequencing of the Schmidtea mediterranea genome and some expressed sequence tag projects have generated extensive data on the genetic profile of these cells. However, little information is available on their protein dynamics. Results We developed a proteomic strategy to identify neoblast-specific proteins. Here we describe the method and discuss the results in comparison to the genomic high-throughput analyses carried out in planaria and to proteomic studies using other stem cell systems. We also show functional data for some of the candidate genes selected in our proteomic approach. Conclusions We have developed an accurate and reliable mass-spectra-based proteomics approach to complement previous genomic studies and to further achieve a more accurate understanding and description of the molecular and cellular processes related to the neoblasts. PMID:21356107

2011-01-01

288

Modeling Planarian Regeneration: A Primer for Reverse-Engineering the Worm  

Microsoft Academic Search

A mechanistic understanding of robust self-assembly and repair capabilities of complex systems would have enormous implications for basic evolutionary developmental biology as well as for transformative applications in regenerative biomedicine and the engineering of highly fault-tolerant cybernetic systems. Molecular biologists are working to identify the pathways underlying the remarkable regenerative abilities of model species that perfectly regenerate limbs, brains, and

Daniel Lobo; Wendy S. Beane; Michael Levin

2012-01-01

289

EGFR signaling regulates cell proliferation, differentiation and morphogenesis during planarian regeneration and homeostasis  

Microsoft Academic Search

Similarly to development, the process of regeneration requires that cells accurately sense and respond to their external environment. Thus, intrinsic cues must be integrated with signals from the surrounding environment to ensure appropriate temporal and spatial regulation of tissue regeneration. Identifying the signaling pathways that control these events will not only provide insights into a fascinating biological phenomenon but may

Susanna Fraguas; Sara Barberán; Francesc Cebrià

2011-01-01

290

Acute toxic responses of the freshwater planarian, Dugesia dorotocephala, to methylmercury  

SciTech Connect

Toxic responses of planaria to various aquatic habitat concentrations of methylmercury chloride (MMC) were investigated. One hundred percent lethality occurred within 5 h in 2 ppM MMC, 24 h in 1 ppM MMC, and 5 days in 0.5 ppM MMC. No deaths occurred in 0.2 ppM MMC over a 10 day period, however, non-lethal toxic responses were observed. Varying degrees of head resorption, progressing caudally from the snout were observed. With continuing exposure, partial head regeneration and recovery toward more normal appearance occurred by 10 days. Teratogenic effects were observed in surgical decapitation experiments. Head regeneration was retarded in 0.1 and 0.2 ppM MMC. Malformations, visible lesions, or gross behavioral abnormalities were produced by 2 week exposure of planaria to concentrations of 20 ppB MMC or lower. (RJC)

Best, J.B.; Morita, M.; Ragin, J.; Best, J. Jr.

1981-07-01

291

Long-range neural and gap junction protein-mediated cues control polarity during planarian regeneration  

Microsoft Academic Search

Having the ability to coordinate the behavior of stem cells to induce regeneration of specific large-scale structures would have far-reaching consequences in the treatment of degenerative diseases, acute injury, and aging. Thus, identifying and learning to manipulate the sequential steps that determine the fate of new tissue within the overall morphogenetic program of the organism is fundamental. We identified novel

Néstor J. Oviedo; Junji Morokuma; Peter Walentek; Ido P. Kema; Man Bock Gu; Joo-Myung Ahn; Jung Shan Hwang; Takashi Gojobori; Michael Levin

2010-01-01

292

Weak extremely-low-frequency magnetic fields and regeneration in the planarian Dugesia tigrina  

SciTech Connect

Extremely-low-frequency (ELF), low-intensity magnetic fields have been shown to influence cell signaling processes in a variety of systems, both in vivo and in vitro. Similar effects have been demonstrated for nervous system development and neurite outgrowth. The authors report that regeneration in planaria, which incorporates many of these processes, is also affected by ELF magnetic fields. The rate of cephalic regeneration, reflected by the mean regeneration time (MRT), for planaria populations regenerating under continuous exposure to combined DC (78.4 {mu}T) and AC (60.0 Hz at 10.0 {mu}T{sub peak}) magnetic fields applied in parallel was found to be significantly delayed (P {much_lt} 0.001) by 48 {+-} 1 h relative to two different types of control populations (MRT {minus}140 {+-} 12 h). One control population was exposed to only the AC component of this field combination, while the other experienced only the ambient geomagnetic field. All measurements were conducted in a low-gradient, low-noise magnetics laboratory under well-maintained temperature conditions. This delay in regeneration was shown to be dependent on the planaria having a fixed orientation with respect to the magnetic field vectors. Results also indicate that this orientation-dependent transduction process does not result from Faraday induction but is consistent with a Ca{sup 2+} cyclotron resonance mechanism. Data interpretation also permits the tentative conclusion that the effect results from an inhibition of events at an early stage in the regeneration process before the onset of proliferation and differentiation.

Jenrow, K.A.; Smith, C.H.; Liboff, A.R. [Oakland Univ., Rochester, MI (United States). Dept. of Physics

1995-06-01

293

A wound-induced Wnt expression program controls planarian regeneration polarity  

E-print Network

Regeneration requires specification of the identity of new tissues to be made. Whether this process relies only on intrinsic regulative properties of regenerating tissues or whether wound signaling provides input into ...

Petersen, Christian P.

294

Double-Stranded RNA Specifically Disrupts Gene Expression during Planarian Regeneration  

Microsoft Academic Search

Metazoan regeneration is one of the least understood fundamental problems of biology. The lack of progress in understanding this phenomenon at the molecular level has been due to the poor regenerative abilities of the genetic organisms used for developmental studies, as well as the difficulties encountered with molecular and genetic manipulations of the commonly studied vertebrate models (the urodele amphibians).

Alejandro Sanchez Alvarado; Phillip A. Newmark

1999-01-01

295

Double-stranded RNA specifically disrupts gene expression during planarian regeneration  

Microsoft Academic Search

Metazoan regeneration is one of the least understood fundamental problems of biology. The lack of progress in understanding this phenomenon at the molecular level has been due to the poor regenerative abilities of the genetic organisms used for developmental studies, as well as the difficulties encountered with molecular and genetic ma- nipulations of the commonly studied vertebrate models (the urodele

ALEJANDRO SANCHEZ ALVARADO; PHILLIP A. NEWMARK

1999-01-01

296

Induction of a noggin-Like Gene by Ectopic DV Interaction during Planarian Regeneration  

Microsoft Academic Search

In previous studies, we have shown that dorsoventral (DV) interaction evokes not only blastema formation, but also morphogenetic events similar to those that occur in regeneration. However, it is still unclear what kinds of signal molecules are involved in the DV interaction. To investigate the signal systems involved in the DV interaction, we focused on a noggin-like gene (Djnlg) identified

Kazuya Ogawa; Shogo Ishihara; Yumi Saito; Katsuhiko Mineta; Masumi Nakazawa; Kazuho Ikeo; Takashi Gojobori; Kenji Watanabe; Kiyokazu Agata

2002-01-01

297

Characterization of innexin gene expression and functional roles of gap-junctional communication in planarian regeneration  

Microsoft Academic Search

Planaria possess remarkable powers of regeneration. After bisection, one blastema regenerates a head, while the other forms a tail. The ability of previously-adjacent cells to adopt radically different fates could be due to long-range signaling allowing determination of position relative to, and the identity of, remaining tissue. However, this process is not understood at the molecular level. Following the hypothesis

Taisaku Nogi; Michael Levin

2005-01-01

298

Planarian Worms, Shock Generators and Apathetic Witnesses: Teaching Psychology and Graphic Novels  

ERIC Educational Resources Information Center

Comics and graphic novels have made a greater impact on popular culture in recent years and can be used for enhancing the learning experience of psychology students. One of the best known and respected comic book writers of the last 30 years is Alan Moore, who has included a number of detailed references to psychological studies and experiments in…

Aleixo, Paul A.; Norris, Claire E.

2013-01-01

299

Carnival of SL RNAs: Structural variants and the possibility of a common origin  

E-print Network

Rotifera Nematoda Drosophilamelanogaster Platyhelminths Tunicates Homosapiens (a) Euglenida Kinetoplastida Dinophyceae Arabidopsisthaliana Saccharomycescerevisae Cnidaria Rotifera Nematoda Drosophilamelanogaster

Stadler, Peter F.

300

Mitochondrial pathway of apoptosis is ancestral in metazoans  

PubMed Central

The mitochondrial pathway of apoptosis is the major mechanism of physiological cell death in vertebrates. In this pathway, proapoptotic members of the Bcl-2 family cause mitochondrial outer membrane permeabilization (MOMP), allowing the release of cytochrome c, which interacts with Apaf-1 to trigger caspase activation and apoptosis. Despite conservation of Bcl-2, Apaf-1, and caspases in invertebrate phyla, the existence of the mitochondrial pathway in any invertebrate is, at best, controversial. Here we show that apoptosis in a lophotrochozoan, planaria (phylum Platyhelminthes), is associated with MOMP and that cytochrome c triggers caspase activation in cytosolic extracts from these animals. Further, planarian Bcl-2 family proteins can induce and/or regulate cell death in yeast and can replace Bcl-2 proteins in mammalian cells to regulate MOMP. These results suggest that the mitochondrial pathway of apoptosis in animals predates the emergence of the vertebrates but was lost in some lineages (e.g., nematodes). In further support of this hypothesis, we surveyed the ability of cytochrome c to trigger caspase activation in cytosolic extracts from a variety of organisms and found this effect in cytosolic extracts from invertebrate deuterostomes (phylum Echinodermata). PMID:22416118

Bender, Cheryl E.; Fitzgerald, Patrick; Tait, Stephen W. G.; Llambi, Fabien; McStay, Gavin P.; Tupper, Douglas O.; Pellettieri, Jason; Alvarado, Alejandro Sánchez; Salvesen, Guy S.; Green, Douglas R.

2012-01-01

301

Phylogenetic analysis of dicyemid mesozoans (phylum Dicyemida) from innexin amino acid sequences: dicyemids are not related to Platyhelminthes.  

PubMed

Dicyemid mesozoans are endoparasites, or endosymbionts, found only in the renal sac of benthic cephalopod molluscs. The body organization of dicyemids is very simple, consisting of usually 10 to 40 cells, with neither body cavities nor differentiated organs. Dicyemids were considered as primitive animals, and the out-group of all metazoans, or as occupying a basal position of lophotrochozoans close to flatworms. We cloned cDNAs encoding for the gap junction component proteins, innexin, from the dicyemids. Its expression pattern was observed by whole-mount in situ hybridization. In adult individuals, the innexin was expressed in calottes, infusorigens, and infusoriform embryos. The unique temporal pattern was observed in the developing infusoriform embryos. Innexin amino acid sequences had taxon-specific indels which enabled identification of the 3 major protostome lineages, i.e., 2 ecdysozoans (arthropods and nematodes) and the lophotrochozoans. The dicyemids show typical, lophotrochozoan-type indels. In addition, the Bayesian and maximum likelihood trees based on the innexin amino acid sequences suggested dicyemids to be more closely related to the higher lophotrochozoans than to the flatworms. Flatworms were the sister group, or consistently basal, to the other lophotrochozoan clade that included dicyemids, annelids, molluscs, and brachiopods. PMID:20557208

Suzuki, Takahito G; Ogino, Kazutoyo; Tsuneki, Kazuhiko; Furuya, Hidetaka

2010-06-01

302

Adding resolution to ordinal level relationships of tapeworms (Platyhelminthes: Cestoda) with large fragments of mtDNA.  

PubMed

The construction of a stable phylogeny for the Cestoda, indicating the interrelationships of recognised orders and other major lineages, has proceeded iteratively since the group first received attention from phylogenetic systematists. Molecular analyses using nuclear ribosomal RNA gene fragments from the small (ssrDNA) and large (lsrDNA) subunits have been used to test competing evolutionary scenarios based on morphological data but could not arbitrate between some key conflicting hypotheses. To the ribosomal data, we have added a contiguous fragment of mitochondrial (mt) genome data (mtDNA) of partial nad1-trnN-trnP-trnI-trnK-nad3-trnS-trnW-cox1-trnT-rrnL-trnC-partial rrnS, spanning 4034-4447 bp, where new data for this region were generated for 18 species. Bayesian analysis of mtDNA and rDNA as nucleotides, and where appropriate as amino acids, demonstrated that these two classes of genes provide complementary signal across the phylogeny. In all analyses, except when using mt amino acids only, the Gyrocotylidea is sister group to all other Cestoda (Nephroposticophora), and Amphilinidea forms the sister group to the Eucestoda. However, an earliest-diverging position of Amphilinidea is strongly supported in the mt amino acid analysis. Amphilinidea exhibit a unique tRNA arrangement (nad1-trnI-trnL2-trnP-trnK-trnV-trnA-trnN-nad3), whereas Gyrocotylidea shares that of the derived lineages, providing additional evidence of the uniqueness of amphilinid genes and genomes. The addition of mtDNA to the rDNA genes supported the Caryophyllidea as the sister group to (Spathebothriidea+remaining Eucestoda), a hypothesis consistently supported by morphology. This relationship suggests a history of step-wise evolutionary transitions from simple monozoic, unsegmented tapeworms to the more familiar polyzoic, externally segmented (strobilate) forms. All our data partitions recovered Haplobothriidea as the sister group to Diphyllobothriidae. The sister-group relationship between Diphyllidea and Trypanorhyncha, as previously established using rDNA, is not supported by the mt data, although it is supported by the combined mt and rDNA analysis. With regards to the more derived taxa, in all except the mt amino acid analysis, the following topology is supported: (Bothriocephalidea (Litobothriidea (Lecanicephalidea (Rhinebothriidea (Tetraphyllidea, (Acanthobothrium, Proteocephalidea), (Nippotaeniidea, Mesocestoididae, Tetrabothriidea, Cyclophyllidea)))))), where the Tetraphyllidea are paraphyletic. Evidence from the mt data provides strong (nucleotides) to moderate (amino acids) support for Tetraphyllidea forming a group to the inclusion of Proteocephalidea, with the latter consistently forming the sister group to Acanthobothrium. The interrelationships among Nippotaeniidea, Mesocestoididae, Tetrabothriidea and Cyclophyllidea remain ambiguous and require further systematic attention. Mitochondrial and nuclear rDNA data provide conflicting signal for certain parts of the cestode tree. In some cases mt data offer results in line with morphological evidence, such as the interrelationships of the early divergent lineages. Also, Tetraphyllidea, although remaining paraphyletic with the inclusion of the Proteocephalidea, does not include the most derived cestodes; a result which has consistently been obtained with rDNA. PMID:22406529

Waeschenbach, Andrea; Webster, B L; Littlewood, D T J

2012-06-01

303

Making the most of mitochondrial genomes--markers for phylogeny, molecular ecology and barcodes in Schistosoma (Platyhelminthes: Digenea).  

PubMed

An increasing number of complete sequences of mitochondrial (mt) genomes provides the opportunity to optimise the choice of molecular markers for phylogenetic and ecological studies. This is particularly the case where mt genomes from closely related taxa have been sequenced; e.g., within Schistosoma. These blood flukes include species that are the causative agents of schistosomiasis, where there has been a need to optimise markers for species and strain recognition. For many phylogenetic and population genetic studies, the choice of nucleotide sequences depends primarily on suitable PCR primers. Complete mt genomes allow individual gene or other mt markers to be assessed relative to one another for potential information content, prior to broad-scale sampling. We assess the phylogenetic utility of individual genes and identify regions that contain the greatest interspecific variation for molecular ecological and diagnostic markers. We show that variable characters are not randomly distributed along the genome and there is a positive correlation between polymorphism and divergence. The mt genomes of African and Asian schistosomes were compared with the available intraspecific dataset of Schistosoma mansoni through sliding window analyses, in order to assess whether the observed polymorphism was at a level predicted from interspecific comparisons. We found a positive correlation except for the two genes (cox1 and nad1) adjoining the putative control region in S. mansoni. The genes nad1, nad4, nad5, cox1 and cox3 resolved phylogenies that were consistent with a benchmark phylogeny and in general, longer genes performed better in phylogenetic reconstruction. Considering the information content of entire mt genome sequences, partial cox1 would not be the ideal marker for either species identification (barcoding) or population studies with Schistosoma species. Instead, we suggest the use of cox3 and nad5 for both phylogenetic and population studies. Five primer pairs designed against Schistosoma mekongi and Schistosoma malayensis were tested successfully against Schistosoma japonicum. In combination, these fragments encompass 20-27% of the variation amongst the genomes (average total length approximately 14,000bp), thus providing an efficient means of encapsulating the greatest amount of variation within the shortest sequence. Comparative mitogenomics provides the basis of a rational approach to molecular marker selection and optimisation. PMID:17570370

Zarowiecki, M Z; Huyse, T; Littlewood, D T J

2007-10-01

304

Genetic differentiation among populations of Minona ileanae (Platyhelminthes: Proseriata) from the Red Sea and the Suez Canal  

Microsoft Academic Search

The phenomenon of Lessepsian migration has stimulated the interest of biologists ever since the opening of the Suez Canal in 1869, concerning, in particular, the possible effects of migrants on Mediterranean autochthonous communities. So far, most attention has been devoted to macrofaunal taxa – yet, the nature of the sandy shores of the Canal may constitute an ideal habitat for

Tiziana Lai; Marco Curini-Galletti; Marco Casu

2008-01-01

305

CALORIFIC VALUES IN THE PHYLUM PLATYHELMINTHES: THE RELATIONSHIP BETWEEN POTENTIAL ENERGY, MODE OF LIFE AND THE EVOLUTION OF ENTOPARASITISM  

Microsoft Academic Search

An analysis of the calorific values (kcal\\/g) of seventeen species of animals from six phyla has shown that they have a skewed distribution with a modal fre quency at or near the lower range limit (Slobodkin and Richman, 1%1 ) . This was regarded as support for the hypothesis that natural selection generally favors production of the maximum number of

P. CALOW; J. B. JENNINGS

306

The complete mitochondrial genome of Neobenedenia melleni (Platyhelminthes: Monogenea): mitochondrial gene content, arrangement and composition compared with two Benedenia species.  

PubMed

The complete mitochondrial (mt) genome sequences of Neobenedenia melleni were determined and compared with those of Benedenia seriolae and B. hoshinai. This circular genome comprises 13,270 bp and includes all 36 typical mt genes found in flatworms. Total AT content of N. melleni is 75.9 %. ATG is the most common start codon, while nad4L is initiated by GTG. All protein-coding genes are predicted to terminate with TAG and TAA. N. melleni has the trnR with a TCG anticodon, which is the same to B. seriolae but different from B. hoshinai (ACG). The mt gene arrangement of N. melleni is similar to that of B. seriolae and B. hoshinai with the exception of three translocations (trnF, trnT and trnG). The overlapped region between nad4L and nad4 was found in the N. melleni mt genome, which was also reported for the published Gyrodactylus species, but it was not found in those of B. seriolae and B. hoshinai, which are non-coding regions instead. The present study provides useful molecular characters for species or strain identification and systematic studies of this parasite. PMID:25024046

Zhang, Juan; Wu, Xiangyun; Li, Yanwei; Zhao, Mengwei; Xie, Mingquan; Li, Anxing

2014-10-01

307

Cryptostylochus hullensis sp. nov. (Polycladida, Acotylea, Platyhelminthes): A possible case of transoceanic dispersal on a ship's hull  

NASA Astrophysics Data System (ADS)

In July 1993, the car carrier “Faust” entered Bremerhaven after a voyage from the North-American Atlantic coast to Europe. In a dockyard, five living specimens of the order Polycladida were collected from the hull of the ship. This could be a possible case of trans-atlantic dispersal of plathelminths living as fouling organisms of ships. The specimens found represent a new species of the genus Cryptostylochus Faubel, 1983, Cryptostylochus hullensis sp. nov.

Faubel, A.; Gollasch, S.

1996-12-01

308

A revision of the family Zoogonidae Odhner, 1902 (Platyhelminthes: Digenea): Subfamily Lepidophyllinae and comments on some aspects of biology  

Microsoft Academic Search

Summary  A detailed revision of the zoogonid subfamily Lepidophyllinae is presented, using morphological characters discussed in an earlier paper. Twelve genera and 50 species are treated in detail with keys and cladograms to genera and species. The genera and species covered are: Lepidophyllum steenstrupi, L. appyi, L. armatum, L. brachycladium, L. cameroni, L. pleuronectini, L. pyriforme, L. schantaricum, Urinatrema hispidum, U.

Rodney A. Bray

1987-01-01

309

Added resolution among ordinal level relationships of tapeworms (Platyhelminthes: Cestoda) with complete small and large subunit nuclear ribosomal RNA genes  

Microsoft Academic Search

The addition of large subunit ribosomal DNA (lsrDNA) to small subunit ribosomal DNA (ssrDNA) has been shown to add resolution to phylogenies at various taxonomic levels for a diversity of phyla. We added nearly complete lsrDNA (4057–4593bp) sequences to ssrDNA (1940–2228bp) for 26 ingroup and 3 outgroup taxa in an attempt to provide an improved ordinal phylogeny for the Cestoda.

Andrea Waeschenbach; Bonnie L. Webster; Rodney A. Bray; D. T. J. Littlewood

2007-01-01

310

A DNA-based demonstration of a three-host life-cycle for the Bivesiculidae (Platyhelminthes: Digenea)  

Microsoft Academic Search

Immature bivesiculid trematodes collected from the intestine of Thalassomalunare (Labridae) are shown to be morphologically consistent with adults of Bivesiculaclaviformis from Epinephelus fasciatus (Serranidae). In addition, the immature bivesiculids have the same sequence for the second internal transcribed spacer of the ribosomal DNA. Comparison with three other species of Bivesiculidae showed differences of between 23% and 30%. These results show

Thomas H Cribb; Glenn R anderson; Robert D Adlard; Rodney A Bray

1998-01-01

311

A new and alien species of ``oyster leech'' (Platyhelminthes, Polycladida, Stylochidae) from the brackish North Sea Canal, The Netherlands  

NASA Astrophysics Data System (ADS)

A new species of polyclad flatworm, Imogine necopinata Sluys, sp. nov., is described from a brackish habitat in The Netherlands. Taxonomic affinities with Asian species and the ecology of the animals suggest that the species is an introduced, exotic component of the Dutch fauna. The new species belongs to a group of worms with species that are known to predate on oysters.

Sluys, Ronald; Faubel, Anno; Rajagopal, Sanjeevi; Velde, Gerard Van Der

2005-11-01

312

Spathebothriidea: survey of species, scolex and egg morphology, and interrelationships of a non-segmented, relictual tapeworm group (Platyhelminthes: Cestoda).  

PubMed

Tapeworms of the order Spathebothriidea Wardle et McLeod, 1952 (Cestoda) are reviewed. Molecular data made it possible to assess, for the first time, the phylogenetic relationships of all genera and to confirm the validity of Bothrimonus Duvernoy, 1842, Diplocotyle Krabbe, 1874 and Didymobothrium Nybelin, 1922. A survey of all species considered to be valid is provided together with new data on egg and scolex morphology and surface ultrastructure (i.e. microtriches). The peculiar morphology of the members of this group, which is today represented by five effectively monotypic genera whose host associations and geographical distribution show little commonality, indicate that it is a relictual group that was once diverse and widespread. The order potentially represents the earliest branch of true tapeworms (i.e. Eucestoda) among extant forms. PMID:25185404

Kuchta, Roman; Pearson, Rebecca; Scholz, Tomás; Ditrich, Oleg; Olson, Peter D

2014-08-01

313

The evolution of the Proteocephalidea (Platyhelminthes, Eucestoda) based on an enlarged molecular phylogeny, with comments on their uterine development  

Microsoft Academic Search

We present a molecular phylogeny of the Proteocephalidea based on 28S rDNA sequence data that is a follow-up to the paper by Zehnder & Mariaux (1999). Twenty-three new sequences, including three outgroups are added in our new data-set. The Gangesiinae Mola, 1929 and the Acanthotaeniinae Freze, 1963 appear to be the most primitive clades. They are followed by a robust clade

Alain de Chambrier; Marc Zehnder; Claude Vaucher; Jean Mariaux

2004-01-01

314

A new species of Unilatus (Platyhelminthes: Monogenoidea) from the gills of Leporacanthicus galaxias Isbrücker et Nijssen (Siluriformes: Loricariidae) from Brazil.  

PubMed

Unilatus irae sp. nov. (Dactylogyridae) is described from the gills of the armored catfish, Leporacanthicus galaxias Isbrücker et Nijssen (Loricariidae: Ancistrinae), from Guamá river, Pará State, Brazil. The new species can be differentiated from its cogeneners by the combination of the following features: anterior anchor with well-developed superficial root, inconspicuous deep root, shaft bent at midpoint, forming angle of approximately 60°, evenly short curved point; posterior anchor with inconspicuous roots, sclerotized cap of base with small protuberance for articulation to posterior bar; evenly curved shaft and short point; anterior bar broadly V-shaped, with small posteromedial projection; and posterior bar anteriorly expanded on it midportion, with expanded ends slightly curved in posterior direction. PMID:24570054

Branches, Bárbara; Domingues, Marcus V

2014-03-01

315

A Bmp/Admp Regulatory Circuit Controls Maintenance and Regeneration of Dorsal-Ventral Polarity in Planarians  

E-print Network

Animal embryos have diverse anatomy and vary greatly in size. It is therefore remarkable that a common signaling pathway, BMP signaling, controls development of the dorsoventral (DV) axis throughout the Bilateria [1, 2, ...

Reddien, Peter

316

Special Feature: Searching for the prototypic eye genetic network: Sine oculis is essential for eye regeneration in planarians  

Microsoft Academic Search

* Departament de Genètica, Facultat de Biologia, Universitat de Barcelona, Diagonal 645, 08071 Barcelona, Spain; Department of Biology and Biochemistry, University of Houston, Houston, TX 77204-5513; Center for Information Biology, National Institute of Genetics, Mishima, Yata 411, Japan; and § Department of Cell Biology, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland Contributed by W. J. Gehring, December 23,

D. Pineda; J. Gonzalez; P. Callaerts; K. Ikeo; W. J. Gehring; E. Salo

2000-01-01

317

Dorsal and Ventral Positional Cues Required for the Onset of Planarian Regeneration May Reside in Differentiated Cells  

Microsoft Academic Search

We previously showed by grafting experiments that the dorsoventral (DV) interaction evokes morphogenetic events similar to those that occur in regeneration. However, it is not yet understood whether the stem cells themselves or differentiated cells have the ability to induce regeneration. Here we demonstrated by a combination of X-ray irradiation and grafting experiments that the dorsal and ventral positional cues

Kentaro Kato; Hidefumi Orii; Kenji Watanabe; Kiyokazu Agata

2001-01-01

318

NOAA Technical Rep_o_rt_N_M_F_S_I_2_1 A_u..gu_s_t1_9_94 Marine Flora and Fauna of the  

E-print Network

United States Platyhelminthes: Monogenea Sherman S. Hendrix u.s. Department of Commerce #12;u Bulletin Marine Flora and Fauna of the Eastern United States Platyhelminthes: Monogenea Sherman S. Hendrix

319

Division of Ultrastructure Research and Evolutionary Biology, Department of Zoology and Limnology, University of Innsbruck, Technikerstrae 25, Innsbruck, Austria; 2  

E-print Network

Platyhelminthes: Macrostomum lignano, n. sp. (Rhabditophora, Macrostomorpha) P. Ladurner1 , L. Scha¨rer1,2 , W, the basal-most subtaxon of the Platyhelminthes­Rhabditophora. This new species can be easily cultured including the main groups of the Platyhelminthes, Ehlers 1985). There is considerable recent debate over

Schärer, Lukas

320

Biology II--1750 Dr. Scott D. Snyder  

E-print Network

, Porifera Chapter 11 Chapter 12 Systematics II Protozoa 5 February 6 Exam I Cnidaria, Platyhelminthes Chapter 13 Chapter 14 Porifera, Cnidaria 6 February 13 Platyhelminthes Nemata, Rotifera Chapter 14 Chapter 15 Platyhelminthes Pseudocoleomates 7 February 20 Mollusca Chapter 16 Mollusca 8 February 27 Annelida

Snyder, Scott D.

321

First evidence of maternal transmission of algal endosymbionts at an oocyte stage in a triploblastic host, with observations on reproduction  

E-print Network

, Cnidaria, Platyhelminthes, and Mollusca (Douglas 1995) as well as members of the recently designated phylum Platyhelminthes. However, re- cent molecular and morphological evidence suggests that this taxon falls outside of the Platyhelminthes in the new phylum Acoelomorpha, the most basal bila- terian-triploblastic taxon (Bagun~ a

Benayahu, Yehuda

322

Acknowledgements This work was supported by grants from the National Eye Institute and the Human Frontier Science Program. J.H.R.M. is an Investigator with the Howard Hughes Medical  

E-print Network

............................................................................................................................................................................. The study of planarian regeneration may help us to understand how we can rebuild organs and tissues after molecules involved in the process of brain regeneration in planarians, we prepared microarrays containing 1@bcm.tmc.edu) .............................................................. FGFR-related gene nou-darake restricts brain tissues to the head region of planarians Francesc Cebria

Alvarado, Alejandro Sánchez

323

SMEDWI-2 Is a PIWI-Like Protein That Regulates  

E-print Network

in homeostasis and regeneration and because the genetic study of planarian stem cells is now possible (12, 13, 15SMEDWI-2 Is a PIWI-Like Protein That Regulates Planarian Stem Cells Peter W. Reddien,* Ne´stor J, smedwi-1 and smedwi-2, expressed in the di- viding adult stem cells (neoblasts) of the planarian

Oviedo, Néstor J.

324

Proc. Natl. Acad. Sci. USA Vol. 96, pp. 50495054, April 1999  

E-print Network

-stranded RNA specifically disrupts gene expression during planarian regeneration ALEJANDRO SA´NCHEZ ALVARADO of regeneration. The ability to eliminate gene function in a regenerating organism such as the planarian overcomes with their morphological simplicity and phylogenetic position, make planarians ideally suited for the study of regeneration

Alvarado, Alejandro Sánchez

325

The Amazing Worm: Planaria Background: We have been learning about the regenerative  

E-print Network

. 2. To test the planarian's ability to regenerate. 3. To understand the properties of stem cells!! We will be looking at planarians to see if their cells can differentiate into the tissues they need after you dissect them. Objectives: 1. To examine the body structure of an invertebrate called planarian

Rose, Michael R.

326

Evolution of Developmental Control Mechanisms Germ layer specification and axial patterning in the embryonic development of the  

E-print Network

Regeneration Although patterning during regeneration in adult planarians has been studied extensively, very in the embryonic development of the freshwater planarian Schmidtea polychroa José María Martín-Durán a, , Enrique Available online 25 January 2010 Keywords: Planarian Embryo Patterning Gastrulation Germ layers Polarity

Amaya, Enrique

327

Regeneration in Planaria Phillip A Newmark,Carnegie Institution of Washington, Baltimore, Maryland, USA  

E-print Network

dissected from a planarian head was capable of regenerating a complete organism (see Brøndsted, 1969 Loeb and Hans Driesch, planarian regeneration presented an intriguing dilemma in which isolated parts Child to study planarian regeneration in the late 1890s and early 1900s. It is interesting to note

Alvarado, Alejandro Sánchez

328

INTRODUCTION The replacement of cells that are lost to normal physiological  

E-print Network

.1242/dmm.000117 Planarian PTEN homologs regulate stem cells and regeneration through TOR signaling Néstor J planarian Schmidtea mediterranea possesses an abundant population of undifferentiated cells, many of which). Neoblasts are considered the adult stem cells in planarians because they constantly self-renew and produce

Oviedo, Néstor J.

329

Gen564 Readings Spring 2014 Prof: Ahna Skop  

E-print Network

.1038/nrg2484. Movie: http://www.hhmi.org/biointeractive/planarian-regeneration-and-stem-cells Mar 25th in planarians and mammals. Stem Cells. 2012 Aug;30(8):1734-45. doi: 10.1002/stem.1144. Review: Phillip A. Newmark & Alejandro Sánchez Alvarado Not your father's planarian: a classic model enters the era

Skop, Ahna

330

Volume 1, 2000 March 7, 2000  

E-print Network

of animal regeneration. The developmental plasticity and phylogenetic position of planarians, coupled. OVERVIEW Planarians are discussed as a viable system in which molecular studies of regeneration can-established animal models indicate that molecular studies of regeneration in planarians will have far reaching conse

Alvarado, Alejandro Sánchez

331

TECHNOLOGY REPORT Identification of Immunological Reagents for Use in the  

E-print Network

, interest in planarians as a model system for the study of metazoan regeneration, adult stem cell biology of planarian regeneration is RNA in- terference (RNAi) (Sa´nchez Alvarado and Newmark, 1999). This method Planarians by Means of Whole-Mount Immunofluorescence and Confocal Microscopy Sofia M.C. Robb and Alejandro

Alvarado, Alejandro Sánchez

332

Advanced Review The history and enduring  

E-print Network

to regenerate tissues lost to age and injury, planarians have long fascinated naturalists. In the Western to place the study of planarian regeneration into a broader historical context by focusing of the mechanisms of planarian regeneration uncovered since this animal's relatively recent entrance

Alvarado, Alejandro Sánchez

333

DEVELOPMENT 3121RESEARCH ARTICLE  

E-print Network

-mediated signals in regeneration and homeostasis, using the planarian species Schmidtea mediterranea as a tractableDEVELOPMENT 3121RESEARCH ARTICLE INTRODUCTION The planarian flatworm exhibits a remarkable ability-conserved and widely relevant molecular controls of morphogenesis. Planarian stem cells (neoblasts) have the potential

Oviedo, Néstor J.

334

Speciation and host–parasite relationships in the parasite genus Gyrodactylus (Monogenea, Platyhelminthes) infecting gobies of the genus Pomatoschistus (Gobiidae, Teleostei)  

Microsoft Academic Search

Using species-level phylogenies, the speciation mode of Gyrodactylus species infecting a single host genus was evaluated. Eighteen Gyrodactylus species were collected from gobies of the genus Pomatoschistus and sympatric fish species across the distribution range of the hosts. The V4 region of the ssrRNA and the internal transcribed spacers encompassing the 5.8S rRNA gene were sequenced; by including published sequences

Tine Huyse; Vanessa Audenaert; Filip A. M. Volckaert

2003-01-01

335

First description of monogenean parasites in Lake Tanganyika: the cichlid Simochromis diagramma (Teleostei, Cichlidae) harbours a high diversity of Gyrodactylus species (Platyhelminthes, Monogenea).  

PubMed

Lake Tanganyika harbours the most diverse endemic cichlid fish assemblage of Africa, but its monogenean fish parasites have not been investigated. Here we report, for the first time, on the Gyrodactylus parasites in this hotspot of fish biodiversity. Haptor morphometrics and nuclear ribosomal DNA sequences revealed 3 new species on Zambian Simochromis diagramma: Gyrodactylus sturmbaueri n. sp., G. thysi n. sp. and G. zimbae n. sp. Their distinct morphology and strong genetic differentiation suggest that they belong to distant lineages within the genus Gyrodactylus, and phylogenetic reconstructions suggest affinities with other genera of gyrodactylids. Additional U-shaped haptoral plates in G. thysi n. sp. and a second large spine-like structure in the male copulatory organ of G. zimbae seem to represent new features for the genus. Such large diversity on a single host species can probably be explained by host-switching events during the course of evolution, in agreement with the generally accepted concept that ecological transfer is an important aspect of gyrodactylid speciation. Additional parasitological surveys on other host species, covering a broader phylogenetic and geographical range, should clarify the evolutionary history of Gyrodactylidae on cichlids in the African Great Lake and other parts of Africa. PMID:20946697

Vanhove, Maarten P M; Snoeks, Jos; Volckaert, Filip A M; Huyse, Tine

2011-03-01

336

The majority of parasitic worms belong to either the Platyhelminthes (flatworms/flukes and tape-worms) or Nematoda (roundworms/nematodes).  

E-print Network

infected snails or paratenic hosts (in whole or in part). Food items contaminated with slime, which has infection can also occur. The exotic giant African land snail has been found at several sites in Miami ­ a wide variety of molluscs including species of land and freshwater snails as well as slugs. First stage

Jawitz, James W.

337

Bioassays for testing effects of Al, Cr and Cd using development in the amphibian Pleurodeles waltl and regeneration in the planarian Dugesia etrusca  

Microsoft Academic Search

Historically, water quality studies have been directed toward obtaining physical and chemical measurements on toxicants occurring in the aquatic environment. At present, bioassays are increasingly used as sensitive indicators of pollutant toxicity, since they are rapid, inexpensive, applicable to a variety of toxicants and allow several acute and chronic endpoints to be assessed simultaneously. The analysis of the potential toxicity

F Calevro; S Campani; C Filippi; R Batistoni; P Deri; S Bucci; M Ragghianti; G Mancino

1999-01-01

338

DOI: 10.1126/science.283.5409.1923 , 1923 (1999);283Science  

E-print Network

(deuterostomes; ecdysozoans, with the exception of Nematoda; and lophotrochozoans, with the exception of Platyhel (Platyhelminthes including acoels, Nematoda, Chaetognata, Mesozoa, Gnathostomulida, Rotifera, and Acanthocephala

Sereno, Martin

339

What is Biomphalaria glabrata? Biomphalaria glabrata is a mollusc and thus represents the lophotrochozoan clade of animal  

E-print Network

BRYOZOA BRACHIOPODA PHORONIDA ANNELIDA MOLLUSCA SIPUNCULIDA PLATYHELMINTHS PLACOZOA CNIDARIA PORIFERA DEUTEROSTOMES ECDYSOZOANS LOPHO- TROCHOZOANS #12;Phylum Mollusca · >50 thousand living species · Includes

Loker, Eric "Sam"

340

The Importance of Archived Programmatic Collections: Minerals Management Service and Department of  

E-print Network

that Platyhelminthes Nemertea Bryozoa Sipuncula Meiofauna Chordata Chordata: unidentified pelagic tunicate, MMS slide Described Total: 298 175 - Annelida 87 - Arthropoda 2 - Chordata 11 - Cnidaria 6 - Echinodermata 8

Mathis, Wayne N.

341

Regulation of Early Pattern Formation in the Sea Urchin Embryo by the Wnt Pathway Components Dishevelled and Axin.  

E-print Network

??Data from diverse species within the deuterostomes (mouse, frog, fish, amphioxus, hemichordate, ascidians, sea urchin, sea star) and protostomes (annelids, planarians, nemerteans, mollusks) suggest that… (more)

Peng, Chieh-Fu

2012-01-01

342

Identification of Genes Needed for Regeneration, Stem Cell Function, and Tissue Homeostasis by Systematic Gene Perturbation in Planaria  

Microsoft Academic Search

Summary generating a regeneration blastema consisting of ini- tially undifferentiated cells covered by epidermal cells. Planarians have been a classic model system for the Moreover, essentially all tissues in adult planarians turn study of regeneration, tissue homeostasis, and stem over and are replaced by neoblast progeny. Although cell biology for over a century, but they have not his- the characteristics

Peter W. Reddien; Adam L. Bermange; Kenneth J. Murfitt; Joya R. Jennings; Alejandro Sánchez Alvarado

2005-01-01

343

Developmental Cell, Vol. 8, 623627, May, 2005, Copyright 2005 by Elsevier Inc. DOI 10.1016/j.devcel.2005.04.007 improvements in hand, Reddien et al. (2005) moved on  

E-print Network

surprising. Many of the genes yielding ob-Planarian regeneration relies upon a stem cell popula- tion, 2000). These stem cells (the neoblasts) are the in knockdown animals to characterize further the RNAi to those observed after X-irradiation, which is known to destroy the planarian stem cells; genes in this

Alvarado, Alejandro Sánchez

344

Cell Stem Cell Molecular Analysis of Stem Cells and Their  

E-print Network

homeostasis and regeneration, but also the utility of studies in planarians to broadly inform stem cellCell Stem Cell Article Molecular Analysis of Stem Cells and Their Descendants during Cell Turnover@neuro.utah.edu DOI 10.1016/j.stem.2008.07.002 SUMMARY In adult planarians, the replacement of cells lost

Alvarado, Alejandro Sánchez

345

lineages during gonadal regeneration in the annelid Enchytraeus japonensis.  

E-print Network

of evolutionarily conserved genes defined by piwi are essential for stem cell self-renewal. Genes Dev. 12, 3715 Press). 5. Sanchez Alvarado, A. (2006). Planarian regeneration: its end is its beginning. Cell 124, 241). SMEDWI-2 is a PIWI-like protein that regulates planarian stem cells. Science 310, 1327­1330. 7. Baguna, J

Page, Rachel

346

DOI: 10.1126/science.1178712 , 1406 (2009);326Science  

E-print Network

Pathway Evolution to Cilia Planarian Hh Signaling Regulates Regeneration This copy is for your personal, by theScience onFebruary7,2010www.sciencemag.orgDownloadedfrom #12;Planarian Hh Signaling Regulates Regeneration Polarity and Links Hh Pathway Evolution to Cilia Jochen C. Rink,* Kyle A. Gurley,* Sarah A

Gibson, Matt

347

Automated Analysis of Behavior: A Computer-Controlled System for Drug  

E-print Network

to overcome these problems dur- ing investigation of neural function in planarian flat- worms and frog larvae of controversies in neurobiology. For exam- ple, the lack of consensus on the learning ability of planarian flatworms, and in particular on the ability of memories to persist during the regeneration of the central

Levin, Michael

348

Guides to the Freshwater Invertebrates of Southern Africa. Volume 5: Non-Arthropods. The Protozoans, Porifera, Cnidaria, Platyhelminthes, Nemertea, Rotifera, Nematoda, Nematomorpha, Gastrotrichia, Bryozoa, Tardigrada, Polychaeta, Oligochaeta and Hirudinea  

Microsoft Academic Search

March 2002, Water Research Commission, Pretoria, South AfricaRing-bound soft cover, 293 pagesWRC Report No. TT 167\\/02; ISBN 978-1-86845-827-1; price R100.00 (South Africa), US$50.00 (international)Obtainable from the Water Research Commission, Private Bag X03, Gezina, Pretoria 0031, South Africa; or orders@wrc.org.za

Ian Gaigher

2010-01-01

349

Phylogeny and classification of the Digenea (Platyhelminthes: Trematoda) 1 1 Nucleotide sequence data reported in this paper are available in the GenBank™, EMBL and DDBJ databases under the accession numbers AY222082–AY222285  

Microsoft Academic Search

Complete small subunit ribosomal RNA gene (ssrDNA) and partial (D1–D3) large subunit ribosomal RNA gene (lsrDNA) sequences were used to estimate the phylogeny of the Digenea via maximum parsimony and Bayesian inference. Here we contribute 80 new ssrDNA and 124 new lsrDNA sequences. Fully complementary data sets of the two genes were assembled from newly generated and previously published sequences

P. D. Olson; T. H. Cribb; V. V. Tkach; R. A. Bray; D. T. J. Littlewood

2003-01-01

350

Comparative ultrastructure of adhesive systems in the turbellaria  

Microsoft Academic Search

Summary  Glandular adhesive organs and other structures by which turbellarians attach themselves temporarily to surfaces have been\\u000a studied by electron microscopy.\\u000a \\u000a Adhesive organs in representatives of the turbellarian orders Haplopharyngida, Macrostomida, Polycladida, Rhabdocoela, Proseriata,\\u000a and Tricladida are composed of three cell types: two gland cell types and a modified epidermal cell type through which the\\u000a necks of the glands project. One

S. Tyler

1976-01-01

351

[The determination of the species classification of Baikal planarian cocoons found in the stomach of the black grayling (Thymallus arcticus baicalensis) by a comparative analysis of the nucleotide sequences of the ribosomal RNA gene].  

PubMed

Comparative analysis of nucleotide sequences of gene 18S of ribosome RNA was carried out. The results show that the genetic sequences of the given locus could be used as a molecular marker to identify the species of planaria irrespective of ontogenetic stage. The articles deals with problem of specific determination of cocoons of Baikal planaria from the stomach of Baikal black grayling using comparative analysis of nucleotide sequences of ribosome RNA fragments with known sequences determined earlier for Baikal planaria. The cocoons belong to two species of Rimacephalus. The authors discuss also the importance of feeding relationships of planaria and benthophage fish to investigate the biotic factors that influence the evolution of Baikal planaria. PMID:10520297

Kuznedelov, K D; Dziuba, E V

1999-01-01

352

Arkansas Water Resources Center  

E-print Network

Coelenterata. 43 Platyhelminthes (flatworms) 45 ematodes (round worms) 49 Oligochaetes (aquatic earthworms, that this was done without inquiring of the scientific biological community: Who is living in the Arkansas River

Soerens, Thomas

353

Plan de cours Facult des arts et des sciences  

E-print Network

: Anthozoa; Ctenophora Bilateria: Caractéristiques générales Protostomia & Deuterostomia Lab 4: Cnidaria et Ctenophora F�VRIER mercredi 5 (lire chap.: 10, 11) Introduction aux Platyhelminthes, Turbellaria

Parrott, Lael

354

BIOLOGICAL EVOLUTION Origin and Evolution of Animals  

E-print Network

Species Mammalia Aves Primates Carnivora Hominidae Hylobatidae Homo Hylobates sapiens antecessor Chordata (arthropods) Nematoda Priapula Mollusca (mollusks) Annelida Platyhelminthes Brachiopoda Chordata (chordates Vertebrates: sometimes considered a subphylum of Chordata, but sometimes considered a phylum by itself

Cooper, Brenton G.

355

www.nature.com/naturemethods nature methods | VOL.9 NO.5 | MAY 2012  

E-print Network

Tyson 426 `self-healing' dyes: intramolecular stabilization of organic fluorophores Philip TinnefeldGhliGhts 431 a technology for memory 432 together we shine 432 the planarian Prometheus, quantified 434 etch

Cai, Long

356

Tissue absence initiates regeneration through Follistatin-mediated inhibition of Activin signaling  

E-print Network

Regeneration is widespread, but mechanisms that activate regeneration remain mysterious. Planarians are capable of whole-body regeneration and mount distinct molecular responses to wounds that result in tissue absence and ...

Gavino, Michael A.

357

J A N U A R Y 2 0 1 2 U.S. DEPARTMENT OF  

E-print Network

Belly Button Bacteria Spotlights on Hot Science 4 Just Found: Making Heads or Tails of Regeneration 8 Trypanosoma brucei, Centers for Disease Control and Prevention/Mae Melvin 12 Planarian, Phillip Newmark 13

Bandettini, Peter A.

358

dlx and sp6-9 Control Optic Cup Regeneration in a Prototypic Eye  

E-print Network

Optic cups are a structural feature of diverse eyes, from simple pit eyes to camera eyes of vertebrates and cephalopods. We used the planarian prototypic eye as a model to study the genetic control of optic cup formation ...

Lapan, Sylvain William

359

Innate sexuality determines the mechanisms of telomere maintenance.  

PubMed

Recently, telomere length has been shown to be differentially regulated in asexually and sexually reproducing planarians. In addition, it was found that asexual worms maintain telomere length somatically during reproduction by fission or when regeneration is induced by amputation, whereas sexual worms only achieve telomere elongation through sexual reproduction. We have established an experimental bioassay system to induce switching from asexual to sexual reproduction in planarians, that is, sexualization. In this study, the relationship between the reproductive mode and telomere maintenance was investigated using innate asexually reproducing worms, innate sexually reproducing worms, and experimentally sexualized worms. Here, we show that innate asexual planarians maintain telomere length during cell division and that innate sexual planarians exhibit telomere shortening. However, experimental sexualized worms maintain telomere length during cell division. These results indicate that innate sexuality is linked to the mechanism of telomere maintenance. PMID:23319366

Tasaka, Kenta; Yokoyama, Naoki; Nodono, Hanae; Hoshi, Motonori; Matsumoto, Midori

2013-01-01

360

Regeneration of neuronal cell types in Schmidtea mediterranea: an immunohistochemical and expression study.  

PubMed

Freshwater planarians are unique in their ability to regenerate a complete Central Nervous System (CNS) from almost any small piece of their body in just a few days. The planarian CNS contains a pair of anterior cephalic ganglia lying on top of two ventral nerve cords that extend along the length of the animal. Studies of planarian CNS regeneration have generally used pan-neural markers, which provide only a general overview of the process. Nevertheless, some reports have started to characterize the genes that are required for this process. In this study, to obtain a more detailed description of planarian neural regeneration, we monitored the regeneration of neuronal populations specifically labelled with antibodies against serotonin, allatostatin, neuropeptide F, GYRFamide and FMRFamide. We also characterized the regeneration of dopaminergic and octopaminergic cell populations by in situ hybridization. Finally, we characterized the expression pattern of a set of receptors for neurotransmitters, neuropeptides and hormones that are suggested to play a role in the regeneration process itself. Together, these data provide a more detailed description of the cellular events occurring during anterior and posterior CNS regeneration in planarians and provide the foundations for future mechanistic studies into the regeneration process in this important model system. PMID:22451002

Fraguas, Susanna; Barberán, Sara; Ibarra, Begoña; Stöger, Linda; Cebrià, Francesc

2012-01-01

361

Phylogenetic analysis of the suborder Plagiorchiata (Platyhelminthes, Digenea) based on partial lsrDNA sequences 1 Note: Nucleotide sequence data reported in this paper are available in the GenBank database under the accession numbers AF151910, AF151912–AF151942 (see Appendix A). 1  

Microsoft Academic Search

The phylogenetic relationships and systematic position of the members of the suborder Plagiorchiata, one of the derived and most diverse groups of Digenea, have always been controversial. Here, we present a phylogeny of this group based on the analysis of partial sequences of the lsrDNA in 28 species representing 13 families of Plagiorchiata, as well as four outgroups. Our results

Vasyl Tkach; Jan Pawlowski; Jean Mariaux

2000-01-01

362

Nuclear hormone receptors in parasitic helminths.  

PubMed

Nuclear receptors (NRs) belong to a large protein superfamily that are important transcriptional modulators in metazoans. Parasitic helminths include parasitic worms from the Lophotrochozoa (Platyhelminths) and Ecdysozoa (Nematoda). NRs in parasitic helminths diverged into two different evolutionary lineages. NRs in parasitic Platyhelminths have orthologues in Deuterostomes, in arthropods or both with a feature of extensive gene loss and gene duplication within different gene groups. NRs in parasitic Nematoda follow the nematode evolutionary lineage with a feature of multiple duplication of SupNRs and gene loss. PMID:20600585

Wu, Wenjie; LoVerde, Philip T

2011-03-01

363

Nuclear hormone receptors in parasitic helminths  

PubMed Central

Nuclear receptors (NRs) belong to a large protein superfamily that are important transcriptional modulators in metazoans. Parasitic helminths include parasitic worms from the Lophotrochozoa (Platyhelminths) and Ecdysozoa (Nematoda). NRs in parasitic helminths diverged into two different evolutionary lineages. NRs in parasitic Platyhelminths have orthologues in Deuterostomes, in arthropods or both with a feature of extensive gene loss and gene duplication within different gene groups. NRs in parasitic Nematoda follow the nematode evolutionary lineage with a feature of multiple duplication of SupNRs and gene loss. PMID:20600585

Wu, Wenjie; LoVerde, Philip T

2010-01-01

364

Specialized progenitors and regeneration.  

PubMed

Planarians are flatworms capable of regenerating all body parts. Planarian regeneration requires neoblasts, a population of dividing cells that has been studied for over a century. Neoblast progeny generate new cells of blastemas, which are the regenerative outgrowths at wounds. If the neoblasts comprise a uniform population of cells during regeneration (e.g. they are all uncommitted and pluripotent), then specialization of new cell types should occur in multipotent, non-dividing neoblast progeny cells. By contrast, recent data indicate that some neoblasts express lineage-specific transcription factors during regeneration and in uninjured animals. These observations raise the possibility that an important early step in planarian regeneration is the specialization of neoblasts to produce specified rather than naïve blastema cells. PMID:23404104

Reddien, Peter W

2013-03-01

365

'Death and axes': unexpected Ca²? entry phenologs predict new anti-schistosomal agents.  

PubMed

Schistosomiasis is a parasitic flatworm disease that infects 200 million people worldwide. The drug praziquantel (PZQ) is the mainstay therapy but the target of this drug remains ambiguous. While PZQ paralyses and kills parasitic schistosomes, in free-living planarians PZQ caused an unusual axis duplication during regeneration to yield two-headed animals. Here, we show that PZQ activation of a neuronal Ca²? channel modulates opposing dopaminergic and serotonergic pathways to regulate 'head' structure formation. Surprisingly, compounds with efficacy for either bioaminergic network in planarians also displayed antischistosomal activity, and reciprocally, agents first identified as antischistocidal compounds caused bipolar regeneration in the planarian bioassay. These divergent outcomes (death versus axis duplication) result from the same Ca²? entry mechanism, and comprise unexpected Ca²? phenologs with meaningful predictive value. Surprisingly, basic research into axis patterning mechanisms provides an unexpected route for discovering novel antischistosomal agents. PMID:24586156

Chan, John D; Agbedanu, Prince N; Zamanian, Mostafa; Gruba, Sarah M; Haynes, Christy L; Day, Timothy A; Marchant, Jonathan S

2014-02-01

366

Specialized progenitors and regeneration  

PubMed Central

Planarians are flatworms capable of regenerating all body parts. Planarian regeneration requires neoblasts, a population of dividing cells that has been studied for over a century. Neoblast progeny generate new cells of blastemas, which are the regenerative outgrowths at wounds. If the neoblasts comprise a uniform population of cells during regeneration (e.g. they are all uncommitted and pluripotent), then specialization of new cell types should occur in multipotent, non-dividing neoblast progeny cells. By contrast, recent data indicate that some neoblasts express lineage-specific transcription factors during regeneration and in uninjured animals. These observations raise the possibility that an important early step in planarian regeneration is the specialization of neoblasts to produce specified rather than naïve blastema cells. PMID:23404104

Reddien, Peter W.

2013-01-01

367

DRUG ACTION IN GALVANOTROPIC RESPONSES  

PubMed Central

Under strychninization involving reversal of reciprocal inhibition of the circular and longitudinal muscles, planarians and earthworms show reversed, i.e., anodal, galvanotropic responses, which neither nicotine nor atropine induce (in planarians). The results strengthen the conclusion (Crozier, 1926–27) that in causing reversal of inhibition strychnine acts primarily on central synapses or on homologous elements. Like other arthropods, on the other hand, Asellus is little affected by strychnine; no reversal occurs. Caffeine and atropine are even less effective. Nicotine evokes abnormal posture and movements, perhaps reversed, but no alteration of anodal galvanotropism. PMID:19872416

Fries, E. F. B.

1928-01-01

368

DRUG ACTION IN GALVANOTROPIC RESPONSES.  

PubMed

Under strychninization involving reversal of reciprocal inhibition of the circular and longitudinal muscles, planarians and earthworms show reversed, i.e., anodal, galvanotropic responses, which neither nicotine nor atropine induce (in planarians). The results strengthen the conclusion (Crozier, 1926-27) that in causing reversal of inhibition strychnine acts primarily on central synapses or on homologous elements. Like other arthropods, on the other hand, Asellus is little affected by strychnine; no reversal occurs. Caffeine and atropine are even less effective. Nicotine evokes abnormal posture and movements, perhaps reversed, but no alteration of anodal galvanotropism. PMID:19872416

Fries, E F

1928-05-20

369

Back in time: a new systematic proposal for the Bilateria  

Microsoft Academic Search

Conventional wisdom suggests that bilateral organisms arose from ancestors that were radially, rather than bilaterally, symmetrical and, therefore, had a single body axis and no mesoderm. The two main hypotheses on how this transformation took place consider either a simple organism akin to the planula larva of extant cnidarians or the acoel Platyhelminthes (planuloid-acoeloid theory), or a rather complex organism

Pere Martinez; Jordi Paps; Marta Riutort

2009-01-01

370

HelmCoP: An Online Resource for Helminth Functional Genomics and Drug and Vaccine Targets Prioritization  

Microsoft Academic Search

A vast majority of the burden from neglected tropical diseases result from helminth infections (nematodes and platyhelminthes). Parasitic helminthes infect over 2 billion, exerting a high collective burden that rivals high-mortality conditions such as AIDS or malaria, and cause devastation to crops and livestock. The challenges to improve control of parasitic helminth infections are multi-fold and no single category of

Sahar Abubucker; John Martin; Christina M. Taylor; Makedonka Mitreva

2011-01-01

371

Evolutionary analysis of the cystatin family in three Schistosoma species  

PubMed Central

The cystatin family comprises cysteine protease inhibitors distributed in 3 subfamilies (I25A–C). Family members lacking cystatin activity are currently unclassified. Little is known about the evolution of Schistosoma cystatins, their physiological roles, and expression patterns in the parasite life cycle. The present study aimed to identify cystatin homologs in the predicted proteome of three Schistosoma species and other Platyhelminthes. We analyzed the amino acid sequence diversity focused in the identification of protein signatures and to establish evolutionary relationships among Schistosoma and experimentally validated human cystatins. Gene expression patterns were obtained from different developmental stages in Schistosoma mansoni using microarray data. In Schistosoma, only I25A and I25B proteins were identified, reflecting little functional diversification. I25C and unclassified subfamily members were not identified in platyhelminth species here analyzed. The resulting phylogeny placed cystatins in different clades, reflecting their molecular diversity. Our findings suggest that Schistosoma cystatins are very divergent from their human homologs, especially regarding the I25B subfamily. Schistosoma cystatins also differ significantly from other platyhelminth homologs. Finally, transcriptome data publicly available indicated that I25A and I25B genes are constitutively expressed thus could be essential for schistosome life cycle progression. In summary, this study provides insights into the evolution, classification, and functional diversification of cystatins in Schistosoma and other Platyhelminthes, improving our understanding of parasite biology and opening new frontiers in the identification of novel therapeutic targets against helminthiases. PMID:25071834

Cuesta-Astroz, Yesid; Scholte, Larissa L. S.; Pais, Fabiano Sviatopolk-Mirsky; Oliveira, Guilherme; Nahum, Laila A.

2014-01-01

372

Intronic hammerhead ribozymes are ultraconserved in the human genome  

Microsoft Academic Search

Small ribozymes have been regarded as living fossils of a prebiotic RNA world that would have remained in the genomes of modern organisms. In this study, we report the ultraconserved occurrence of hammerhead ribozymes in Amniota genomes (reptiles, birds and mammals, including humans), similar to those described previously in amphibians and platyhelminth parasites. The ribozymes mapped to intronic regions of

Inmaculada García-Robles; Marcos de la Peña

2010-01-01

373

Bell Pettigrew Museum of Natural History  

E-print Network

. The lack of a circulatory system to distribute respiratory gases has required the flatworms to adopt. Platyhelminths have no circulatory system to move oxygen around the body and many species have become long (up that lack a body cavity, lack a blood system, lack a through gut and lack any distinguishing features

Brierley, Andrew

374

Evolutionary analysis of the cystatin family in three Schistosoma species.  

PubMed

The cystatin family comprises cysteine protease inhibitors distributed in 3 subfamilies (I25A-C). Family members lacking cystatin activity are currently unclassified. Little is known about the evolution of Schistosoma cystatins, their physiological roles, and expression patterns in the parasite life cycle. The present study aimed to identify cystatin homologs in the predicted proteome of three Schistosoma species and other Platyhelminthes. We analyzed the amino acid sequence diversity focused in the identification of protein signatures and to establish evolutionary relationships among Schistosoma and experimentally validated human cystatins. Gene expression patterns were obtained from different developmental stages in Schistosoma mansoni using microarray data. In Schistosoma, only I25A and I25B proteins were identified, reflecting little functional diversification. I25C and unclassified subfamily members were not identified in platyhelminth species here analyzed. The resulting phylogeny placed cystatins in different clades, reflecting their molecular diversity. Our findings suggest that Schistosoma cystatins are very divergent from their human homologs, especially regarding the I25B subfamily. Schistosoma cystatins also differ significantly from other platyhelminth homologs. Finally, transcriptome data publicly available indicated that I25A and I25B genes are constitutively expressed thus could be essential for schistosome life cycle progression. In summary, this study provides insights into the evolution, classification, and functional diversification of cystatins in Schistosoma and other Platyhelminthes, improving our understanding of parasite biology and opening new frontiers in the identification of novel therapeutic targets against helminthiases. PMID:25071834

Cuesta-Astroz, Yesid; Scholte, Larissa L S; Pais, Fabiano Sviatopolk-Mirsky; Oliveira, Guilherme; Nahum, Laila A

2014-01-01

375

A New Family of Receptor Tyrosine Kinases with a Venus Flytrap Binding Domain in Insects and Other Invertebrates Activated by Aminoacids  

Microsoft Academic Search

BackgroundTyrosine kinase receptors (RTKs) comprise a large family of membrane receptors that regulate various cellular processes in cell biology of diverse organisms. We previously described an atypical RTK in the platyhelminth parasite Schistosoma mansoni, composed of an extracellular Venus flytrap module (VFT) linked through a single transmembrane domain to an intracellular tyrosine kinase domain similar to that of the insulin

Arnaud Ahier; Philippe Rondard; Nadège Gouignard; Naji Khayath; Siluo Huang; Jacques Trolet; Daniel J. Donoghue; Monique Gauthier; Jean-Philippe Pin; Colette Dissous; Gordon Langsley

2009-01-01

376

A New Family of Receptor Tyrosine Kinases with a Venus Flytrap Binding Domain in Insects and Other Invertebrates Activated by Aminoacids  

Microsoft Academic Search

Background: Tyrosine kinase receptors (RTKs) comprise a large family of membrane receptors that regulate various cellular processes in cell biology of diverse organisms. We previously described an atypical RTK in the platyhelminth parasite Schistosoma mansoni, composed of an extracellular Venus flytrap module (VFT) linked through a single transmembrane domain to an intracellular tyrosine kinase domain similar to that of the

Arnaud Ahier; Philippe Rondard; Nadège Gouignard; Naji Khayath; Siluo Huang; Jacques Trolet; Daniel J. Donoghue; Monique Gauthier; Jean-Philippe Pin; Colette Dissous

2009-01-01

377

Thyroid hormone receptor orthologues from invertebrate species with emphasis on Schistosoma mansoni  

Microsoft Academic Search

BACKGROUND:: Thyroid hormone receptors (TRs) function as molecular switches in response to thyroid hormone to regulate gene transcription. TRs were previously believed to be present only in chordates. RESULTS:: We isolated two TR genes from the Schistosoma mansoni and identified TR orthologues from other invertebrates: the platyhelminths, S. japonium and Schmidtea mediterranea, the mollusc, Lottia gigantean and the arthropod Daphnia

Wenjie Wu; Edward G Niles; Philip T LoVerde

2007-01-01

378

Conservation and Diversification of Msx Protein in Metazoan Evolution  

Microsoft Academic Search

Msx (\\/msh) family genes encode homeodomain (HD) proteins that control ontogeny in many animal species. We compared the structures of Msx genes from a wide range of Metazoa (Porifera, Cnidaria, Nematoda, Arthropoda, Tardigrada, Platyhelminthes, Mollusca, Brachiopoda, Annelida, Echiura, Echinodermata, Hemichordata, and Chordata) to gain an understanding of the role of these genes in phylogeny. Exon-intron boundary analysis suggested that the

Hirokazu Takahashi; Akiko Kamiya; Akira Ishiguro; Atsushi C. Suzuki; Naruya Saitou; Atsushi Toyoda; Jun Aruga

2007-01-01

379

Variation in Rates of Asexual Reproduction By Convolutriloba retrogemma  

Microsoft Academic Search

Convolutriloba retrogemma, an acoel turbellarian (phylum Platyhelminthes), engages in an obligate symbiotic relationship with unicellular algae, This species reproduces asexually by budding from the posterior end of the parent individual. The rate of reproduction of 24 newly budded flatworms of various sizes was studied over a period of six weeks, Flatworms were individually placed into 6 mL of 0.2 ?m

Rahim Sara

2003-01-01

380

Using parasites to infer host population history: a new rationale for parasite conservation  

Microsoft Academic Search

Only one of the 5000 extant louse species (Phthiraptera) and no species of flea (Siphonaptera), parasitic helminth (Platyhelminthes), parasitic nematode (Nemata), mite, or tick (Acari) is listed as threatened by the IUCN, despite impassioned pleas for parasite conservation beginning more than a decade ago. Although they should be conserved for their own sake, past arguments, highlighting the intrinsic and utilitarian

Noah Kerness Whiteman; Patricia G. Parker

2005-01-01

381

Substantial Loss of Conserved and Gain of Novel MicroRNA Families in Flatworms  

PubMed Central

Recent studies on microRNA (miRNA) evolution focused mainly on the comparison of miRNA complements between animal clades. However, evolution of miRNAs within such groups is poorly explored despite the availability of comparable data that in some cases lack only a few key taxa. For flatworms (Platyhelminthes), miRNA complements are available for some free-living flatworms and all major parasitic lineages, except for the Monogenea. We present the miRNA complement of the monogenean flatworm Gyrodactylus salaris that facilitates a comprehensive analysis of miRNA evolution in Platyhelminthes. Using the newly designed bioinformatics pipeline miRCandRef, the miRNA complement was disentangled from next-generation sequencing of small RNAs and genomic DNA without a priori genome assembly. It consists of 39 miRNA hairpin loci of conserved miRNA families, and 22 novel miRNAs. A comparison with the miRNA complements of Schmidtea mediterranea (Turbellaria), Schistosoma japonicum (Trematoda), and Echinococcus granulosus (Cestoda) reveals a substantial loss of conserved bilaterian, protostomian, and lophotrochozoan miRNAs. Eight of the 46 expected conserved miRNAs were lost in all flatworms, 16 in Neodermata and 24 conserved miRNAs could not be detected in the cestode and the trematode. Such a gradual loss of miRNAs has not been reported before for other animal phyla. Currently, little is known about miRNAs in Platyhelminthes, and for the majority of the lost miRNAs there is no prediction of function. As suggested earlier they might be related to morphological simplifications. The presence and absence of 153 conserved miRNAs was compared for platyhelminths and 32 other metazoan taxa. Phylogenetic analyses support the monophyly of Platyhelminthes (Turbellaria + Neodermata [Monogenea {Trematoda + Cestoda}]). PMID:24025793

Fromm, Bastian; Worren, Merete Molton; Hahn, Christoph; Hovig, Eivind; Bachmann, Lutz

2013-01-01

382

Teratological research using in vitro systems. V. Nonmammalian model systems.  

PubMed Central

In this review of alternative tests to whole-animal rodent studies, the use of sub-mammalian and sub-vertebrate systems is investigated. The history, methodology, known limitations, end points, dose response, and requirements of virus, hydra, planarian, cricket, fish, amphibia, Drosophila, and chicken embryo systems are discussed. PMID:3113934

Collins, T F

1987-01-01

383

Evolution of Developmental Control Mechanisms Long-range neural and gap junction protein-mediated cues control polarity during  

E-print Network

of stem cells to induce regeneration of specific large-scale structures would have far of regenerative medicine. Planarians possess an accessible adult somatic stem cell population (neoblasts with the large-scale morphogenetic state of the organism. This requires the stem cells to integrate information

Oviedo, Néstor J.

384

Seminars in Cell & Developmental Biology 20 (2009) 557564 Contents lists available at ScienceDirect  

E-print Network

: Regeneration Cancer Stem cells Wound healing Amphibians Planarians a b s t r a c t A better understandingSeminars in Cell & Developmental Biology 20 (2009) 557­564 Contents lists available at ScienceDirect Seminars in Cell & Developmental Biology journal homepage: www.elsevier.com/locate/semcdb Review

Oviedo, Néstor J.

385

Published online 16 April 2004 Regeneration and the need for simpler model  

E-print Network

Published online 16 April 2004 Regeneration and the need for simpler model organisms Alejandro Sa 1900 East, Salt Lake City, UT 84132-3401, USA (sanchez@neuro.utah.edu) The problem of regeneration the study of simpler animals. We have chosen to study and develop the freshwater planarian Schmidtea

Alvarado, Alejandro Sánchez

386

Temporal pattern of the posterior expression of Wingless in Drosophila blastoderm Peggy P. Vorwald-Denholtz, Edward M. De Robertis  

E-print Network

of the A-P patterning system is best exemplified by planarians, in which knock-down of canonical Wnt signaling with b-Catenin RNAi leads to regeneration of heads instead of tails (Gurley et al., 2008; Petersen adenopolyposis coli RNAi causes the regeneration of tails instead of heads (Gurley et al., 2008). One notable

De Robertis, Eddy M.

387

The Scientist Volume 23 | Issue 8 | Page 51  

E-print Network

with those of humans. Others, such as planarian flatworms, frog larvae, and Drosophila melanogaster, offer against a flexible membrane, allowing researchers to automate their nerve regeneration screen. The Yanik, Cambridge Project: Chemical and genetic screens of nerve regeneration in C. elegans Problem: Several years

Yanik, Mehmet Fatih

388

People & Ideas JCB VOLUME 186 NUMBER 2 2009166  

E-print Network

in high school, who did actual experiments with us. I re- member doing one big project on planarian regeneration. That really turned me on to experimental science. The first biology course I took in college, but it turned out that they play a critical role in regeneration. That's what got me think- ing about how

Gibson, Matt

389

Deciphering the molecular machinery of stem cells: a look at the neoblast gene expression profile  

Microsoft Academic Search

BACKGROUND: Mammalian stem cells are difficult to access experimentally; model systems that can regenerate offer an alternative way to characterize stem cell related genes. Planarian regeneration depends on adult pluripotent stem cells - the neoblasts. These cells can be selectively destroyed using X-rays, enabling comparison of organisms lacking stem cells with wild-type worms. RESULTS: Using a genomic approach we produced

Leonardo Rossi; Alessandra Salvetti; Francesco M Marincola; Annalisa Lena; Paolo Deri; Linda Mannini; Renata Batistoni; Ena Wang; Vittorio Gremigni

2007-01-01

390

Smed454 dataset: unravelling the transcriptome of Schmidtea mediterranea  

PubMed Central

Background Freshwater planarians are an attractive model for regeneration and stem cell research and have become a promising tool in the field of regenerative medicine. With the availability of a sequenced planarian genome, the recent application of modern genetic and high-throughput tools has resulted in revitalized interest in these animals, long known for their amazing regenerative capabilities, which enable them to regrow even a new head after decapitation. However, a detailed description of the planarian transcriptome is essential for future investigation into regenerative processes using planarians as a model system. Results In order to complement and improve existing gene annotations, we used a 454 pyrosequencing approach to analyze the transcriptome of the planarian species Schmidtea mediterranea Altogether, 598,435 454-sequencing reads, with an average length of 327 bp, were assembled together with the ~10,000 sequences of the S. mediterranea UniGene set using different similarity cutoffs. The assembly was then mapped onto the current genome data. Remarkably, our Smed454 dataset contains more than 3 million novel transcribed nucleotides sequenced for the first time. A descriptive analysis of planarian splice sites was conducted on those Smed454 contigs that mapped univocally to the current genome assembly. Sequence analysis allowed us to identify genes encoding putative proteins with defined structural properties, such as transmembrane domains. Moreover, we annotated the Smed454 dataset using Gene Ontology, and identified putative homologues of several gene families that may play a key role during regeneration, such as neurotransmitter and hormone receptors, homeobox-containing genes, and genes related to eye function. Conclusions We report the first planarian transcript dataset, Smed454, as an open resource tool that can be accessed via a web interface. Smed454 contains significant novel sequence information about most expressed genes of S. mediterranea. Analysis of the annotated data promises to contribute to identification of gene families poorly characterized at a functional level. The Smed454 transcriptome data will assist in the molecular characterization of S. mediterranea as a model organism, which will be useful to a broad scientific community. PMID:21194483

2010-01-01

391

The Acoela: on their kind and kinships, especially with nemertodermatids and xenoturbellids (Bilateria incertae sedis)  

PubMed Central

Acoels are among the simplest worms and therefore have often been pivotal in discussions of the origin of the Bilateria. Initially thought primitive because of their “planula-like” morphology, including their lumenless digestive system, they were subsequently dismissed by many morphologists as a specialized clade of the Platyhelminthes. However, since molecular phylogenies placed them outside the Platyhelminthes and outside all other phyla at the base of the Bilateria, they became the focus of renewed debate and research. We review what is currently known of acoels, including information regarding their morphology, development, systematics, and phylogenetic relationships, and put some of these topics in a historical perspective to show how the application of new methods contributed to the progress in understanding these animals. Taking all available data into consideration, clear-cut conclusions cannot be made; however, in our view it becomes successively clearer that acoelomorphs are a “basal” but “divergent” branch of the Bilateria. PMID:24098090

Chiodin, Marta; Salvenmoser, Willi; Tyler, Seth

2012-01-01

392

The dawn of bilaterian animals: the case of acoelomorph flatworms.  

PubMed

The origin of the bilaterian metazoans from radial ancestors is one of the biggest puzzles in animal evolution. A way to solve it is to identify the nature and main features of the last common ancestor of the bilaterians (LCB). Recent progress in molecular phylogeny has shown that many platyhelminth flatworms, regarded for a long time as basal bilaterians, now belong to the lophotrochozoan protostomates. In contrast, the LCB is now considered a complex organism bearing several features of modern bilaterians. Here we discuss an alternative view, in which acoelomorph (Acoela + Nemertodermatida) flatworms, which do not belong to the Platyhelminthes, represent the earliest extant bilaterian clade. Sequences from ribosomal and other nuclear genes, Hox cluster genes, and reinterpretation of some morphological features strongly support the basal position of acoelomorphs arguing against a complex LCB. This reconstruction backs the old planuloid-acoeloid hypothesis and may help our understanding of the evolution of body axes, Hox genes and the Cambrian explosion. PMID:15382134

Baguñà, Jaume; Riutort, Marta

2004-10-01

393

Molecular Phylogeny of Metazoan Intermediate Filament Proteins  

Microsoft Academic Search

.   We have cloned cytoplasmic intermediate filament (IF) proteins from a large number of invertebrate phyla using cDNA probes,\\u000a the monoclonal antibody IFA, peptide sequence information, and various RT-PCR procedures. Novel IF protein sequences reported\\u000a here include the urochordata and nine protostomic phyla, i.e., Annelida, Brachiopoda, Chaetognatha, Echiura, Nematomorpha,\\u000a Nemertea, Platyhelminthes, Phoronida, and Sipuncula. Taken together with the wealth of

Andreas Erber; Dieter Riemer; Marc Bovenschulte; Klaus Weber

1998-01-01

394

A phylogenetic analysis of myosin heavy chain type II sequences corroborates that Acoela and Nemertodermatida are basal bilaterians  

PubMed Central

Bilateria are currently subdivided into three superclades: Deuterostomia, Ecdysozoa, and Lophotrochozoa. Within this new taxonomic frame, acoelomate Platyhelminthes, for a long time held to be basal bilaterians, are now considered spiralian lophotrochozoans. However, recent 18S rDNA [small subunit (SSU)] analyses have shown Platyhelminthes to be polyphyletic with two of its orders, the Acoela and the Nemertodermatida, as the earliest extant bilaterians. To corroborate such position and avoid the criticisms of saturation and long-branch effects thrown on the SSU molecule, we have searched for independent molecular data bearing good phylogenetic information at deep evolutionary nodes. Here we report a phylogenetic analysis of DNA sequences from the myosin heavy chain type II (myosin II) gene from a large set of metazoans, including acoels and nemertodermatids. Our study demonstrates, both for the myosin II data set alone and for a combined SSU + myosin II data set, that Platyhelminthes are polyphyletic and that acoels and nemertodermatids are the extant earliest bilaterians. Hence, the common bilaterian ancestor was not, as currently held, large and complex but small, simple, and likely with direct development. This scenario has far-reaching implications for understanding the evolution of major body plans and for perceptions of the Cambrian evolutionary explosion. PMID:12177440

Ruiz-Trillo, I.; Paps, J.; Loukota, M.; Ribera, C.; Jondelius, U.; Baguñà, J.; Riutort, M.

2002-01-01

395

Phylogenetic Analysis of the Endoribonuclease Dicer Family  

PubMed Central

Dicers are proteins of the ribonuclease III family with the ability to process dsRNA, involved in regulation of gene expression at the post-transcriptional level. Dicers are conserved from basal metazoans to higher metazoans and contain a number of functional domains that interact with dsRNA. The completed genome sequences of over 34 invertebrate species allowed us to systematically investigate Dicer genes over a diverse range of phyla. The majority of invertebrate Dicers clearly fell into the Dicer1 or Dicer2 subfamilies. Most nematodes possessed only one Dicer gene, a member of the Dicer1 subfamily, whereas two Dicer genes (Dicer1 and Dicer2) were present in all platyhelminths surveyed. Analysis of the key domains showed that a 5? pocket was conserved across members of the Dicer1 subfamily, with the exception of the nematode Bursaphelenchus xylophilus. Interestingly, Nematostella vectensis DicerB grouped into Dicer2 subfamily harbored a 5? pocket, which is commonly present in Dicer1. Similarly, the 3? pocket was also found to be conserved in all Dicer proteins with the exceptions of Schmidtea mediterranea Dicer2 and Trichoplax adherens Dicer A. The loss of catalytic residues in the RNase III domain was noted in platyhelminths and cnidarians, and the ‘ball’ and ‘socket’ junction between two RNase III domains in platyhelminth Dicers was different from the canonical junction, suggesting the possibility of different conformations. The present data suggest that Dicers might have duplicated and diversified independently, and have evolved for various functions in invertebrates. PMID:24748168

Gao, Zeqian; Wang, Miao; Blair, David; Zheng, Yadong; Dou, Yongxi

2014-01-01

396

A pumilio homolog in Polycelis sp.  

PubMed

Pumilio proteins (PUMs), members of the pumilio/fem-3 mRNA-binding factor (PUF) family, are eukaryote-specific RNA-binding proteins. We isolated a 2,048-basepair cDNA fragment of a pumilio homolog from the planarian flatworm Polycelis sp. This pumilio protein (PyPUM) contains a conserved pumilio homology domain (PUM-HD) consisting of eight repeats and two flanking half repeats. PyPUM shows high similarity to Dugesia japonica pumilio (DjPUM) from another planarian D. japonica, and their PUM-HD also shows high similarity to each other. Furthermore, our data showed that there is a flatworm-specific spacer between repeats 7 and 8. Phylogenetic analysis showed that PyPUM has a closer relationship to other PUM homologs from flatworms. These results provide a foundation for future functional studies of pumilio gene in Polycelis sp. PMID:24292205

Yuwen, Yanqing; Dong, Zimei; Si, Xiaohui; Chen, Guangwen

2014-02-01

397

The protection of invertebrates, fish, and vascular plants against inorganic mercury poisoning by sulfur and selenium derivatives.  

PubMed

Protection of organisms against mercury (Hg) poisoning is most commonly associated with the antagonistic effects of selenium (Se)-compounds against mercury alkyls in higher animals. This study shows that there is no consistent difference among Periodic Group VIA derivatives including S(IV), S(II) organic, Se (IV), Se (II) organic, possibly Se VI, as well and Te (IV) in their ability to protect against mercury poisoning. The organisms used in assays were: Coleus explants (leaf abscission); turnip (germination); pea (growth inhibition and Hg uptake); a planarian (regeneration); the brineshrimp (excystment, phototaxy); the mealworm larva Tenebrio (metamorphosis) and the fish "tilapia" (survival, Hg uptake). Thiamine was the most effective of the Group VIA derivatives against the widest spectrum of organisms and test systems. In planarian regeneration, it was active where S and Se compounds failed. The most unexpected observation was the hastening of insect metamorphosis by HgCl2 and the enhancement of that effect by thiamine. PMID:2014999

Siegel, B Z; Siegel, S M; Correa, T; Dagan, C; Galvez, G; LeeLoy, L; Padua, A; Yaeger, E

1991-02-01

398

Attachment of the cap to the central microtubules of tetrahymena cilia  

E-print Network

) ends. Further studies of the sites of central microtubule assembly in regenerating flagella will be necessary to determine the sites of central microtubule assembly. Since the plug structures are present at the apparent sites of microtubule assembly... (Allen & Wolf, 1979; Scott & Hufnagel, 1983) and with secretory cells in planarians (Dent- ler, unpublished data). Characterization of this dense material and its comparison with proteins associated with the plugs in ciliary microtubules will depend...

Dentler, William L., Jr

1984-03-01

399

Towards a bioinformatics of patterning: a computational approach to understanding regulative morphogenesis.  

PubMed

The mechanisms underlying the regenerative abilities of certain model species are of central importance to the basic understanding of pattern formation. Complex organisms such as planaria and salamanders exhibit an exceptional capacity to regenerate complete body regions and organs from amputated pieces. However, despite the outstanding bottom-up efforts of molecular biologists and bioinformatics focused at the level of gene sequence, no comprehensive mechanistic model exists that can account for more than one or two aspects of regeneration. The development of computational approaches that help scientists identify constructive models of pattern regulation is held back by the lack of both flexible morphological representations and a repository for the experimental procedures and their results (altered pattern formation). No formal representation or computational tools exist to efficiently store, search, or mine the available knowledge from regenerative experiments, inhibiting fundamental insights from this huge dataset. To overcome these problems, we present here a new class of ontology to encode formally and unambiguously a very wide range of possible morphologies, manipulations, and experiments. This formalism will pave the way for top-down approaches for the discovery of comprehensive models of regeneration. We chose the planarian regeneration dataset to illustrate a proof-of-principle of this novel bioinformatics of shape; we developed a software tool to facilitate the formalization and mining of the planarian experimental knowledge, and cured a database containing all of the experiments from the principal publications on planarian regeneration. These resources are freely available for the regeneration community and will readily assist researchers in identifying specific functional data in planarian experiments. More importantly, these applications illustrate the presented framework for formalizing knowledge about functional perturbations of morphogenesis, which is widely applicable to numerous model systems beyond regenerating planaria, and can be extended to many aspects of functional developmental, regenerative, and evolutionary biology. PMID:23429669

Lobo, Daniel; Malone, Taylor J; Levin, Michael

2013-02-15

400

Galantamine reverses scopolamine-induced behavioral alterations in Dugesia tigrina.  

PubMed

In planaria (Dugesia tigrina), scopolamine, a nonselective muscarinic receptor antagonist, induced distinct behaviors of attenuated motility and C-like hyperactivity. Planarian locomotor velocity (pLMV) displayed a dose-dependent negative correlation with scopolamine concentrations from 0.001 to 1.0 mM, and a further increase in scopolamine concentration to 2.25 mM did not further decrease pLMV. Planarian hyperactivity counts was dose-dependently increased following pretreatment with scopolamine concentrations from 0.001 to 0.5 mM and then decreased for scopolamine concentrations ? 1 mM. Planarian learning and memory investigated using classical Pavlovian conditioning experiments demonstrated that scopolamine (1 mM) negatively influenced associative learning indicated by a significant decrease in % positive behaviors from 86 % (control) to 14 % (1 mM scopolamine) and similarly altered memory retention, which is indicated by a decrease in % positive behaviors from 69 % (control) to 27 % (1 mM scopolamine). Galantamine demonstrated a complex behavior in planarian motility experiments since co-application of low concentrations of galantamine (0.001 and 0.01 mM) protected planaria against 1 mM scopolamine-induced motility impairments; however, pLMV was significantly decreased when planaria were tested in the presence of 0.1 mM galantamine alone. Effects of co-treatment of scopolamine and galantamine on memory retention in planaria via classical Pavlovian conditioning experiments showed that galantamine (0.01 mM) partially reversed scopolamine (1 mM)-induced memory deficits in planaria as the % positive behaviors increased from 27 to 63 %. The results demonstrate, for the first time in planaria, scopolamine's effects in causing learning and memory impairments and galantamine's ability in reversing scopolamine-induced memory impairments. PMID:24402079

Ramakrishnan, Latha; Amatya, Christina; DeSaer, Cassie J; Dalhoff, Zachary; Eggerichs, Michael R

2014-09-01

401

Evolution of a novel subfamily of nuclear receptors with members that each contain two DNA binding domains  

PubMed Central

Background Nuclear receptors (NRs) are important transcriptional modulators in metazoans which regulate transcription through binding to the promoter region of their target gene by the DNA binding domain (DBD) and activation or repression of mRNA synthesis through co-regulators bound to the ligand binding domain (LBD). NRs typically have a single DBD with a LBD. Results Three nuclear receptors named 2DBD-NRs, were identified from the flatworm Schistosoma mansoni that each possess a novel set of two DBDs in tandem with a LBD. They represent a novel NR modular structure: A/B-DBD-DBD-hinge-LBD. The 2DBD-NRs form a new subfamily of NRs, VII. By database mining, 2DBD-NR genes from other flatworm species (Schmidtea mediterranea and Dugesia japonica), from Mollusks (Lottia gigantean) and from arthropods (Daphnia pulex) were also identified. All 2DBD-NRs possess a P-box sequence of CEACKK in the first DBD, which is unique to 2DBD-NRs, and a P-box sequence of CEGCKG in the second DBD. Phylogenetic analyses of both DBD and ligand binding domain sequences showed that 2DBD-NR genes originate from a common two DBD-containing ancestor gene. A single 2DBD-NR orthologue was found in Arthropoda, Platyhelminths and Mollusca. Subsequent 2DBD-NR gene evolution in Mollusks and Platyhelminths involved gene duplication. Chromosome localization of S. mansoni 2DBD-NR genes by Fluorescent in situ hybridization (FISH) suggests that 2DBD-NR genes duplicated on different chromosomes in the Platyhelminths. Dimerization of Sm2DBD? indicates that 2DBD-NRs may act as homodimers, suggesting either that two repeats of a half-site are necessary for each DBD of 2DBD-NRs to bind to its target gene, or that each 2DBD-NR can recognize multiple sites. Conclusion 2DBD-NRs share a common ancestor gene which possessed an extra DBD that likely resulted from a recombination event. After the split of the Arthropods, Mollusks and Platyhelminths, 2DBD-NR underwent a recent duplication in a common ancestor of Mollusks, while two rounds of duplication occurred in a common ancestor of the Platyhelminths. This demonstrates that certain NR gene underwent recent duplication in Prostostome lineages after the split of the Prostostomia and Deuterostomia. PMID:17319953

Wu, Wenjie; Niles, Edward G; Hirai, Hirohisa; LoVerde, Philip T

2007-01-01

402

Inhibition of planar cell polarity extends neural growth during regeneration, homeostasis, and development.  

PubMed

The ability to stop producing or replacing cells at the appropriate time is essential, as uncontrolled growth can lead to loss of function and even cancer. Tightly regulated mechanisms coordinate the growth of stem cell progeny with the patterning needs of the host organism. Despite the importance of proper termination during regeneration, cell turnover, and embryonic development, very little is known about how tissues determine when patterning is complete during these processes. Using planarian flatworms, we show that the planar cell polarity (PCP) pathway is required to stop the growth of neural tissue. Although traditionally studied as regulators of tissue polarity, we found that loss of the PCP genes Vangl2, DAAM1, and ROCK by RNA interference (individually or together) resulted in supernumerary eyes and excess optical neurons in intact planarians, while regenerating planarians had continued hyperplasia throughout the nervous system long after controls ceased new growth. This failure to terminate growth suggests that neural tissues use PCP as a readout of patterning, highlighting a potential role for intact PCP as a signal to stem and progenitor cells to halt neuronal growth when patterning is finished. Moreover, we found this mechanism to be conserved in vertebrates. Loss of Vangl2 during normal development, as well as during Xenopus tadpole tail regeneration, also leads to the production of excess neural tissue. This evolutionarily conserved function of PCP represents a tractable new approach for controlling the growth of nerves. PMID:22339734

Beane, Wendy S; Tseng, Ai-Sun; Morokuma, Junji; Lemire, Joan M; Levin, Michael

2012-08-10

403

Thyroid hormone receptor orthologues from invertebrate species with emphasis on Schistosoma mansoni  

PubMed Central

Background: Thyroid hormone receptors (TRs) function as molecular switches in response to thyroid hormone to regulate gene transcription. TRs were previously believed to be present only in chordates. Results: We isolated two TR genes from the Schistosoma mansoni and identified TR orthologues from other invertebrates: the platyhelminths, S. japonium and Schmidtea mediterranea, the mollusc, Lottia gigantean and the arthropod Daphnia pulex. Phylogenetic analysis of the DNA binding domain and/or ligand binding domain shows that invertebrate and vertebrate TRs cluster together, TRs from the vertebrates and from the jawless vertebrate (lamprey) clustered within separate subgroups, Platyhelminth TRs cluster outside of the vertebrate TR subgroups and that the schistosome TRs and S. mediterranea TRs clustered within separate subgroups. Alignment of the C-terminus of the A/B domain revealed a conserved TR-specific motif, termed TR 'N-terminus signature sequence', with a consensus sequence of (G/P)YIPSY(M/L)XXXGPE(D/E)X. Heterodimer formation between S. mansoni TRs and SmRXR1 suggests that the invertebrate TR protein gained the ability to form a heterodimer with RXR. ESMA analysis showed that SmTR? could bind to a conserved DNA core motif as a monomer or homodimer. Conclusion: Vertebrate TR genes originated from a common ancestor of the Bilateria. TR genes underwent duplication independently in the Protostomia and Deuterostomia. The duplication of TRs in deuterostomes occurred after the split of jawless and jawed vertebrates. In protostomes, TR genes underwent duplication in Platyhelminths, occurring independently in trematode and turbellarian lineages. Using S. mansoni TRs as an example, invertebrate TRs exhibited the ability to form a dimer with RXR prior to the emergence of the vertebrate TRs and were able to bind to vertebrate TR core DNA elements as a monomer or homodimer. PMID:17727708

Wu, Wenjie; Niles, Edward G; LoVerde, Philip T

2007-01-01

404

INVERTEBRADOS 2014 Cronograma de Atividades -Diurno  

E-print Network

08 de abril 14:00 2ª AVALIA��O: Assunto da prova: de Mollusca até Lophophorata 20 de maio 14:00 3ª Platyhelminthes II 12 quarta Teórica Mollusca I 18 terça PROVA 1ª AVALIA��O (conteúdo até Platyheminthes) 19 quarta Teórica e Prática Mollusca II 25 terça Teórica e Prática Mollusca III 26 quarta Teórica e Prática

Morandini, Andre C.

405

INVERTEBRADOS 2014 Cronograma de Atividades -Noturno  

E-print Network

Platyheminthes 08 de abril 19:00 2ª AVALIA��O: Assunto da prova: de Mollusca até Lophophorata 20 de maio 19:00 3ª Platyhelminthes II 12 quarta Teórica Mollusca I 18 terça PROVA 1ª AVALIA��O (conteúdo até Platyheminthes) 19 quarta Teórica e Prática Mollusca II 25 terça Teórica e Prática Mollusca III 26 quarta Teórica e Prática

Morandini, Andre C.

406

Glutamate carboxypeptidase II (GCPII) inhibitor displays anti-glutamate and anti-cocaine effects in an invertebrate assay.  

PubMed

Glutamate carboxypeptidase II (GCPII) inhibitors are promising anti-glutamatergic and anti-addictive agents. We hypothesized that a GCPII inhibitor 2 (phosphonomethyl) pentanedioic acid (2-PMPA) would display anti-stereotypical activity in planarians. Experiments revealed that 2-PMPA displayed no overt behavioral activity by itself but attenuated stereotypical counts (C-shape hyperkinesias) elicited by four compounds (2-PMPA rank order potency: glutamate>NMDA>pilocarpine>cocaine). These data suggest GCPII inhibitors display broad-spectrum efficacy against behavioral activity produced by glutamatergic and non-glutamatergic compounds in an invertebrate assay. PMID:21850438

Tallarida, Chris; Song, Kevin; Raffa, Robert B; Rawls, Scott M

2012-06-01

407

Wnt Signaling in Axial Patterning and Regeneration: Lessons from Planaria  

NSDL National Science Digital Library

Wnt signal transduction plays a crucial role in stem cell proliferation and regeneration. When canonical Wnt signaling is low, heads develop, and when it is high, tails are formed. In planarians, Wnt transcription is activated by wounding in a β-catenin−independent way. Hedgehog is one of the signals involved, because it induces regeneration of tails (instead of heads) through the activation of Wnt transcription. Depletion of Smad4 blocks regeneration entirely, which suggests that the bone morphogenetic protein signaling pathway and the Wnt pathway are required for regeneration and body patterning.

Edward M. De Robertis (Los Angeles;University of California REV)

2010-06-22

408

Put a tiger in your tank: the polyclad flatworm Maritigrella crozieri as a proposed model for evo-devo  

PubMed Central

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. PMID:24107307

2013-01-01

409

Changes in mitochondrial genetic codes as phylogenetic characters: Two examples from the flatworms  

PubMed Central

Shared molecular genetic characteristics other than DNA and protein sequences can provide excellent sources of phylogenetic information, particularly if they are complex and rare and are consequently unlikely to have arisen by chance convergence. We have used two such characters, arising from changes in mitochondrial genetic code, to define a clade within the Platyhelminthes (flatworms), the Rhabditophora. We have sampled 10 distinct classes within the Rhabditophora and find that all have the codon AAA coding for the amino acid Asn rather than the usual Lys and AUA for Ile rather than the usual Met. We find no evidence to support claims that the codon UAA codes for Tyr in the Platyhelminthes rather than the standard stop codon. The Rhabditophora are a very diverse group comprising the majority of the free-living turbellarian taxa and the parasitic Neodermata. In contrast, three other classes of turbellarian flatworm, the Acoela, Nemertodermatida, and Catenulida, have the standard invertebrate assignments for these codons and so are convincingly excluded from the rhabditophoran clade. We have developed a rapid computerized method for analyzing genetic codes and demonstrate the wide phylogenetic distribution of the standard invertebrate code as well as confirming already known metazoan deviations from it (ascidian, vertebrate, echinoderm/hemichordate). PMID:11027335

Telford, Maximilian J.; Herniou, Elisabeth A.; Russell, Robert B.; Littlewood, D. Timothy J.

2000-01-01

410

Molecular phylogeny of metazoan intermediate filament proteins.  

PubMed

We have cloned cytoplasmic intermediate filament (IF) proteins from a large number of invertebrate phyla using cDNA probes, the monoclonal antibody IFA, peptide sequence information, and various RT-PCR procedures. Novel IF protein sequences reported here include the urochordata and nine protostomic phyla, i.e., Annelida, Brachiopoda, Chaetognatha, Echiura, Nematomorpha, Nemertea, Platyhelminthes, Phoronida, and Sipuncula. Taken together with the wealth of data on IF proteins of vertebrates and the results on IF proteins of Cephalochordata, Mollusca, Annelida, and Nematoda, two IF prototypes emerge. The L-type, which includes 35 sequences from 11 protostomic phyla, shares with the nuclear lamins the long version of the coil 1b subdomain and, in most cases, a homology segment of some 120 residues in the carboxyterminal tail domain. The S-type, which includes all four subfamilies (types I to IV) of vertebrate IF proteins, lacks 42 residues in the coil 1b subdomain and the carboxyterminal lamin homology segment. Since IF proteins from all three phyla of the chordates have the 42-residue deletion, this deletion arose in a progenitor prior to the divergence of the chordates into the urochordate, cephalochordate, and vertebrate lineages, possibly already at the origin of the deuterostomic branch. Four phyla recently placed into the protostomia on grounds of their 18S rDNA sequences (Brachiopoda, Nemertea, Phoronida, and Platyhelminthes) show IF proteins of the L-type and fit by sequence identity criteria into the lophotrochozoic branch of the protostomia. PMID:9847417

Erber, A; Riemer, D; Bovenschulte, M; Weber, K

1998-12-01

411

Tissue absence initiates regeneration through Follistatin-mediated inhibition of Activin signaling.  

PubMed

Regeneration is widespread, but mechanisms that activate regeneration remain mysterious. Planarians are capable of whole-body regeneration and mount distinct molecular responses to wounds that result in tissue absence and those that do not. A major question is how these distinct responses are activated. We describe a follistatin homolog (Smed-follistatin) required for planarian regeneration. Smed-follistatin inhibition blocks responses to tissue absence but does not prevent normal tissue turnover. Two activin homologs (Smed-activin-1 and Smed-activin-2) are required for the Smed-follistatin phenotype. Finally, Smed-follistatin is wound-induced and expressed at higher levels following injuries that cause tissue absence. These data suggest that Smed-follistatin inhibits Smed-Activin proteins to trigger regeneration specifically following injuries involving tissue absence and identify a mechanism critical for regeneration initiation, a process important across the animal kingdom. DOI:http://dx.doi.org/10.7554/eLife.00247.001. PMID:24040508

Gaviño, Michael A; Wenemoser, Danielle; Wang, Irving E; Reddien, Peter W

2013-01-01

412

Selective amputation of the pharynx identifies a FoxA-dependent regeneration program in planaria.  

PubMed

Planarian flatworms regenerate every organ after amputation. Adult pluripotent stem cells drive this ability, but how injury activates and directs stem cells into the appropriate lineages is unclear. Here we describe a single-organ regeneration assay in which ejection of the planarian pharynx is selectively induced by brief exposure of animals to sodium azide. To identify genes required for pharynx regeneration, we performed an RNAi screen of 356 genes upregulated after amputation, using successful feeding as a proxy for regeneration. We found that knockdown of 20 genes caused a wide range of regeneration phenotypes and that RNAi of the forkhead transcription factor FoxA, which is expressed in a subpopulation of stem cells, specifically inhibited regrowth of the pharynx. Selective amputation of the pharynx therefore permits the identification of genes required for organ-specific regeneration and suggests an ancient function for FoxA-dependent transcriptional programs in driving regeneration. DOI: http://dx.doi.org/10.7554/eLife.02238.001. PMID:24737865

Adler, Carolyn E; Seidel, Chris W; McKinney, Sean A; Sánchez Alvarado, Alejandro

2014-01-01

413

Whole-body acoel regeneration is controlled by Wnt and Bmp-Admp signaling.  

PubMed

Whole-body regeneration is widespread in the Metazoa, yet little is known about how underlying molecular mechanisms compare across phyla. Acoels are an enigmatic phylum of invertebrate worms that can be highly informative about many questions in bilaterian evolution, including regeneration. We developed the three-banded panther worm, Hofstenia miamia, as a new acoelomorph model system for molecular studies of regeneration. Hofstenia were readily cultured, with accessible embryos, juveniles, and adults for experimentation. We developed molecular resources and tools for Hofstenia, including a transcriptome and robust systemic RNAi. We report the identification of molecular mechanisms that promote whole-body regeneration in Hofstenia. Wnt signaling controls regeneration of the anterior-posterior axis, and Bmp-Admp signaling controls regeneration of the dorsal-ventral axis. Perturbation of these pathways resulted in regeneration-abnormal phenotypes involving axial feature duplication, such as the regeneration of two heads following Wnt perturbation or the regeneration of ventral cells in place of dorsal ones following bmp or admp RNAi. Hofstenia regenerative mechanisms are strikingly similar to those guiding regeneration in planarians. However, phylogenetic analyses using the Hofstenia transcriptome support an early branching position for acoels among bilaterians, with the last common ancestor of acoels and planarians being the ancestor of the Bilateria. Therefore, these findings identify similar whole-body regeneration mechanisms in animals separated by more than 550 million years of evolution. PMID:24768051

Srivastava, Mansi; Mazza-Curll, Kathleen L; van Wolfswinkel, Josien C; Reddien, Peter W

2014-05-19

414

Heterochromatin protein 1 promotes self-renewal and triggers regenerative proliferation in adult stem cells.  

PubMed

Adult stem cells (ASCs) capable of self-renewal and differentiation confer the potential of tissues to regenerate damaged parts. Epigenetic regulation is essential for driving cell fate decisions by rapidly and reversibly modulating gene expression programs. However, it remains unclear how epigenetic factors elicit ASC-driven regeneration. In this paper, we report that an RNA interference screen against 205 chromatin regulators identified 12 proteins essential for ASC function and regeneration in planarians. Surprisingly, the HP1-like protein SMED-HP1-1 (HP1-1) specifically marked self-renewing, pluripotent ASCs, and HP1-1 depletion abrogated self-renewal and promoted differentiation. Upon injury, HP1-1 expression increased and elicited increased ASC expression of Mcm5 through functional association with the FACT (facilitates chromatin transcription) complex, which consequently triggered proliferation of ASCs and initiated blastema formation. Our observations uncover an epigenetic network underlying ASC regulation in planarians and reveal that an HP1 protein is a key chromatin factor controlling stem cell function. These results provide important insights into how epigenetic mechanisms orchestrate stem cell responses during tissue regeneration. PMID:23629965

Zeng, An; Li, Yong-Qin; Wang, Chen; Han, Xiao-Shuai; Li, Ge; Wang, Jian-Yong; Li, Dang-Sheng; Qin, Yong-Wen; Shi, Yufang; Brewer, Gary; Jing, Qing

2013-04-29

415

Selective amputation of the pharynx identifies a FoxA-dependent regeneration program in planaria  

PubMed Central

Planarian flatworms regenerate every organ after amputation. Adult pluripotent stem cells drive this ability, but how injury activates and directs stem cells into the appropriate lineages is unclear. Here we describe a single-organ regeneration assay in which ejection of the planarian pharynx is selectively induced by brief exposure of animals to sodium azide. To identify genes required for pharynx regeneration, we performed an RNAi screen of 356 genes upregulated after amputation, using successful feeding as a proxy for regeneration. We found that knockdown of 20 genes caused a wide range of regeneration phenotypes and that RNAi of the forkhead transcription factor FoxA, which is expressed in a subpopulation of stem cells, specifically inhibited regrowth of the pharynx. Selective amputation of the pharynx therefore permits the identification of genes required for organ-specific regeneration and suggests an ancient function for FoxA-dependent transcriptional programs in driving regeneration. DOI: http://dx.doi.org/10.7554/eLife.02238.001 PMID:24737865

Adler, Carolyn E; Seidel, Chris W; McKinney, Sean A; Sánchez Alvarado, Alejandro

2014-01-01

416

The characteristics of sox gene in Dugesia japonica.  

PubMed

Sox genes play important roles in animal developmental processes, including embryogenesis, neural cell stemness, neurogenesis, sex determination, among others. Here, the full length sox gene in planarian Dugesia japonica, named DjsoxB, was cloned using rapid amplification of cDNA ends (RACE). Phylogenetic analysis demonstrates that DjsoxB is highly conserved evolutionarily in metazoans. Whole-mount in situ hybridization found DjsoxB mRNA to be mainly expressed in the head, intestine and mouth in both sexually mature and immature planarians. Moreover, DjsoxB transcripts were detected in the blastema after amputation and throughout the head regeneration processes. The data from real-time PCR showed that the mRNA expression levels of DjsoxB were distinctly up-regulated from 3 to 7days after amputation. These results suggest that DjsoxB gene might be active in CNS formation and functional recovery during head regeneration, maintenance of adult CNS function and the development of other tissues (e.g. intestine) in D. japonica. PMID:24768739

Dong, Zimei; Shi, Changying; Zhang, Haixia; Dou, He; Cheng, Fangfang; Chen, Guangwen; Liu, Dezeng

2014-07-10

417

dlx and sp6-9 Control Optic Cup Regeneration in a Prototypic Eye  

PubMed Central

Optic cups are a structural feature of diverse eyes, from simple pit eyes to camera eyes of vertebrates and cephalopods. We used the planarian prototypic eye as a model to study the genetic control of optic cup formation and regeneration. We identified two genes encoding transcription factors, sp6-9 and dlx, that were expressed in the eye specifically in the optic cup and not the photoreceptor neurons. RNAi of these genes prevented formation of visible optic cups during regeneration. Planarian regeneration requires an adult proliferative cell population with stem cell-like properties called the neoblasts. We found that optic cup formation occurred only after migration of progressively differentiating progenitor cells from the neoblast population. The eye regeneration defect caused by dlx and sp6-9 RNAi can be explained by a failure to generate these early optic cup progenitors. Dlx and Sp6-9 genes function as a module during the development of diverse animal appendages, including vertebrate and insect limbs. Our work reveals a novel function for this gene pair in the development of a fundamental eye component, and it utilizes these genes to demonstrate a mechanism for total organ regeneration in which extensive cell movement separates new cell specification from organ morphogenesis. PMID:21852957

Lapan, Sylvain W.; Reddien, Peter W.

2011-01-01

418

Design of a flexible component gathering algorithm for converting cell-based models to graph representations for use in evolutionary search  

PubMed Central

Background The ability of science to produce experimental data has outpaced the ability to effectively visualize and integrate the data into a conceptual framework that can further higher order understanding. Multidimensional and shape-based observational data of regenerative biology presents a particularly daunting challenge in this regard. Large amounts of data are available in regenerative biology, but little progress has been made in understanding how organisms such as planaria robustly achieve and maintain body form. An example of this kind of data can be found in a new repository (PlanformDB) that encodes descriptions of planaria experiments and morphological outcomes using a graph formalism. Results We are developing a model discovery framework that uses a cell-based modeling platform combined with evolutionary search to automatically search for and identify plausible mechanisms for the biological behavior described in PlanformDB. To automate the evolutionary search we developed a way to compare the output of the modeling platform to the morphological descriptions stored in PlanformDB. We used a flexible connected component algorithm to create a graph representation of the virtual worm from the robust, cell-based simulation data. These graphs can then be validated and compared with target data from PlanformDB using the well-known graph-edit distance calculation, which provides a quantitative metric of similarity between graphs. The graph edit distance calculation was integrated into a fitness function that was able to guide automated searches for unbiased models of planarian regeneration. We present a cell-based model of planarian that can regenerate anatomical regions following bisection of the organism, and show that the automated model discovery framework is capable of searching for and finding models of planarian regeneration that match experimental data stored in PlanformDB. Conclusion The work presented here, including our algorithm for converting cell-based models into graphs for comparison with data stored in an external data repository, has made feasible the automated development, training, and validation of computational models using morphology-based data. This work is part of an ongoing project to automate the search process, which will greatly expand our ability to identify, consider, and test biological mechanisms in the field of regenerative biology. PMID:24917489

2014-01-01

419

Platyzoan mitochondrial genomes.  

PubMed

Platyzoa is a putative lophotrochozoan (spiralian) subtaxon within the protostome clade of Metazoa, comprising a range of biologically diverse, mostly small worm-shaped animals. The monophyly of Platyzoa, the relationships between the putative subgroups Platyhelminthes, Gastrotricha and Gnathifera (the latter comprising at least Gnathostomulida, "Rotifera" and Acanthocephala) as well as some aspects of the internal phylogenies of these subgroups are highly debated. Here we review how complete mitochondrial (mt) genome data contribute to these debates. We highlight special features of the mt genomes and discuss problems in mtDNA phylogenies of the clade. Mitochondrial genome data seem to be insufficient to resolve the position of the platyzoan clade within the Spiralia but can help to address internal phylogenetic questions. The present review includes a tabular survey of all published platyzoan mt genomes. PMID:23274056

Wey-Fabrizius, Alexandra R; Podsiadlowski, Lars; Herlyn, Holger; Hankeln, Thomas

2013-11-01

420

Two novel Mesocestoides vogae fatty acid binding proteins--functional and evolutionary implications.  

PubMed

This work describes two new fatty acid binding proteins (FABPs) identified in the parasite platyhelminth Mesocestoides vogae (syn. corti). The corresponding polypeptide chains share 62% identical residues and overall 90% similarity according to CLUSTALX default conditions. Compared with Cestoda FABPs, these proteins share the highest similarity score with the Taenia solium protein. M. vogae FABPs are also phylogenetically related to the FABP3/FABP4 mammalian FABP subfamilies. The native proteins were purified by chromatographical procedures, and apparent molecular mass and isoelectric point were determined. Immunolocalization studies determined the localization of the expression of these proteins in the larval form of the parasite. The genomic exon-intron organization of both genes is also reported, and supports new insights on intron evolution. Consensus motifs involved in splicing were identified. PMID:18076655

Alvite, Gabriela; Canclini, Lucía; Corvo, Ileana; Esteves, Adriana

2008-01-01

421

Cytosine methylation regulates oviposition in the pathogenic blood fluke Schistosoma mansoni.  

PubMed

Similar to other metazoan pathogens, Schistosoma mansoni undergoes transcriptional and developmental regulation during its complex lifecycle and host interactions. DNA methylation as a mechanism to control these processes has, to date, been discounted in this parasite. Here we show the first evidence for cytosine methylation in the S. mansoni genome. Transcriptional coregulation of novel DNA methyltransferase (SmDnmt2) and methyl-CpG-binding domain proteins mirrors the detection of cytosine methylation abundance and implicates the presence of a functional DNA methylation machinery. Genome losses in cytosine methylation upon SmDnmt2 silencing and the identification of a hypermethylated, repetitive intron within a predicted forkhead gene confirm this assertion. Importantly, disruption of egg production and egg maturation by 5-azacytidine establishes an essential role for 5-methylcytosine in this parasite. These findings provide the first functional confirmation for this epigenetic modification in any worm species and link the cytosine methylation machinery to platyhelminth oviposition processes. PMID:21829186

Geyer, Kathrin K; Rodríguez López, Carlos M; Chalmers, Iain W; Munshi, Sabrina E; Truscott, Martha; Heald, James; Wilkinson, Mike J; Hoffmann, Karl F

2011-01-01

422

Multigene analysis of lophophorate and chaetognath phylogenetic relationships.  

PubMed

Maximum likelihood and Bayesian inference analyses of seven concatenated fragments of nuclear-encoded housekeeping genes indicate that Lophotrochozoa is monophyletic, i.e., the lophophorate groups Bryozoa, Brachiopoda and Phoronida are more closely related to molluscs and annelids than to Deuterostomia or Ecdysozoa. Lophophorates themselves, however, form a polyphyletic assemblage. The hypotheses that they are monophyletic and more closely allied to Deuterostomia than to Protostomia can be ruled out with both the approximately unbiased test and the expected likelihood weights test. The existence of Phoronozoa, a putative clade including Brachiopoda and Phoronida, has also been rejected. According to our analyses, phoronids instead share a more recent common ancestor with bryozoans than with brachiopods. Platyhelminthes is the sister group of Lophotrochozoa. Together these two constitute Spiralia. Although Chaetognatha appears as the sister group of Priapulida within Ecdysozoa in our analyses, alternative hypothesis concerning chaetognath relationships could not be rejected. PMID:17937996

Helmkampf, Martin; Bruchhaus, Iris; Hausdorf, Bernhard

2008-01-01

423

Replacement names for Eutrigaster (Graffia) Csuzdi & Zicsi, 1991 and Dichogaster (Malawia) Csuzdi, 2010 (Oligochaeta, Acanthodrilidae).  

PubMed

The earthworm genus Eutrigaster Cognetti, 1904 has long been in synonymy with Dichogaster Beddard, 1888 until Sims (1987) resurrected it for the Central American Dichogaster-like species possessing a muscular proventriculus in segment 5. Today the genus consists of some 50 species distributed in two subgenera (Csuzdi 2012). The subgenus Eutrigaster (Graffia) Csuzdi & Zicsi, 1991 was erected for species that differ from the type species of the genus in possessing penial setae. According to the summary by Fragoso & Brown (2007) the subgenus Graffia contained 27 taxa. Later, further three species were described (Sherlock et al. 2011; Sherlock & Csuzdi 2013). However, the subgenus name Graffia is a junior homonym of the turbellarian genus Graffia Levinsen, 1879. (A further junior homonym Graffia Ihering, 1880 (Platyhelminthes: Turbellaria) has already been renamed as Graffilla Ihering, 1880). Here the replacement name Eutrigaster (Graffiona) nom. nov. is proposed for the earthworm subgenus Eutrigaster (Graffia). PMID:24943156

Csuzdi, Csaba

2014-01-01

424

Evolution of the let-7 microRNA Family  

PubMed Central

The increase of bodyplan complexity in early bilaterian evolution is correlates with the advent and diversification of microRNAs. These small RNAs guide animal development by regulating temporal transitions in gene expression involved in cell fate choices and transitions between pluripotency and differentiation. One of the two known microRNAs whose origins date back before the bilaterian ancestor is mir-100. In Bilateria, it appears stably associated in polycistronic transcripts with let-7 and mir-125, two key regulators of development. In vertebrates, these three microRNA families have expanded to form a complex system of developmental regulators. In this contribution, we disentangle the evolutionary history of the let-7 locus, which was restructured independently in nematodes, platyhelminths, and deuterostomes. The foundation of a second let-7 locus in the common ancestor of vertebrates and urochordates predates the vertebrate-specific genome duplications, which then caused a rapid expansion of the let-7 family. PMID:22617875

Hertel, Jana; Bartschat, Sebastian; Wintsche, Axel; Otto, Christian; of the Bioinformatics Computer Lab, The Students; Stadler, Peter F.

2012-01-01

425

Ultrastructure of the spermatozoon of Acanthostomum spiniceps (Digenea: Acanthostomidae), a parasite of Bagrus spp. (Siluriformes:Bagridae).  

PubMed

The present study describes, for the first time, the sperm ultrastructure of the parasite Acanthostomum spiniceps (Digenea: Acanthostomidae). The adult worms of this species were collected from the freshwater fishes, Bagrus bayad and Bagrus docmac, caught from the Damietta branch of the River Nile in Dakahlia Governorate, Egypt. Ultrastructure of the sperm of this species revealed that it can be differentiated into seven regions. It is characterized by its filiform shape, tapers anterior, and posterior ends; the two axonemes are in close contact with the plasma membrane and the presence of two mitochondria as one anterior and the other is posterior. The two mitochondria are parallel at a short distance enclosing the first part of nucleus in between. The nucleus is characteristically formed of unusual network of chromatin which is vacuolated. The spermatozoon of A. spiniceps is similar to that of most parasitic Platyhelminthes. PMID:21922241

Mansour, Mohamed Fathy A

2012-04-01

426

Malacological assessment and natural infestation of Biomphalaria straminea (Dunker, 1848) by Schistosoma mansoni (Sambon, 1907) And Chaetogaster limnaei (K. Von Baer, 1827) in an urban eutrophic watershed.  

PubMed

The objective of this study was to perform a malacological assessment at the Ibirité reservoir watershed in the metropolitan region of Belo Horizonte (Minas Gerais) and to evaluate the natural infestation rate of Biomphalaria straminea (Gastropoda: Planorbidae) by Schistosoma mansoni (Platyhelminthes: Trematoda) and Chaetogaster limnaei (Oligochaeta: Naididae). The samples were collected from July to August 2002. The B. straminea individuals collected were kept in the laboratory; the natural infestation rate by S. mansoni and C. limnaei was assessed weekly. The malacological assessment identified five mollusk species present in the Ibirité reservoir watershed: B. straminea, Physa marmorata, Lymnea sp., Melanoides tuberculatus, and Pomacea austrum. Laboratory observations showed that the B. straminea individuals were infected by C. limnaei rather than S. mansoni. Although there was no infection of B. straminea by S. mansoni, presence of B. straminea in itself merits close attention due to possible risk of human schistosomiasis by the local population. PMID:16097724

Callisto, M; Moreno, P; Gonçalves, J F; Ferreira, W R; Gomes, C L Z

2005-05-01

427

Visualization and 3D Reconstruction of Flame Cells of Taenia solium (Cestoda)  

PubMed Central

Background Flame cells are the terminal cells of protonephridial systems, which are part of the excretory systems of invertebrates. Although the knowledge of their biological role is incomplete, there is a consensus that these cells perform excretion/secretion activities. It has been suggested that the flame cells participate in the maintenance of the osmotic environment that the cestodes require to live inside their hosts. In live Platyhelminthes, by light microscopy, the cells appear beating their flames rapidly and, at the ultrastructural, the cells have a large body enclosing a tuft of cilia. Few studies have been performed to define the localization of the cytoskeletal proteins of these cells, and it is unclear how these proteins are involved in cell function. Methodology/Principal Findings Parasites of two different developmental stages of T. solium were used: cysticerci recovered from naturally infected pigs and intestinal adults obtained from immunosuppressed and experimentally infected golden hamsters. Hamsters were fed viable cysticerci to recover adult parasites after one month of infection. In the present studies focusing on flame cells of cysticerci tissues was performed. Using several methods such as video, confocal and electron microscopy, in addition to computational analysis for reconstruction and modeling, we have provided a 3D visual rendition of the cytoskeletal architecture of Taenia solium flame cells. Conclusions/Significance We consider that visual representations of cells open a new way for understanding the role of these cells in the excretory systems of Platyhelminths. After reconstruction, the observation of high resolution 3D images allowed for virtual observation of the interior composition of cells. A combination of microscopic images, computational reconstructions and 3D modeling of cells appears to be useful for inferring the cellular dynamics of the flame cell cytoskeleton. PMID:21412407

Valverde-Islas, Laura E.; Arrangoiz, Esteban; Vega, Elio; Robert, Lilia; Villanueva, Rafael; Reynoso-Ducoing, Olivia; Willms, Kaethe; Zepeda-Rodríguez, Armando; Fortoul, Teresa I.; Ambrosio, Javier R.

2011-01-01

428

Venus Kinase Receptors: Prospects in Signaling and Biological Functions of These Invertebrate Kinases  

PubMed Central

Venus kinase receptors (VKRs) form a family of invertebrate receptor tyrosine kinases (RTKs) initially discovered in the parasitic platyhelminth Schistosoma mansoni. VKRs are single transmembrane receptors that contain an extracellular venus fly trap structure similar to the ligand-binding domain of G protein-coupled receptors of class C, and an intracellular tyrosine kinase domain close to that of insulin receptors. VKRs are found in a large variety of invertebrates from cnidarians to echinoderms and are highly expressed in larval stages and in gonads, suggesting a role of these proteins in embryonic and larval development as well as in reproduction. VKR gene silencing could demonstrate the function of these receptors in oogenesis as well as in spermatogenesis in S. mansoni. VKRs are activated by amino acids and are highly responsive to arginine. As many other RTKs, they form dimers when activated by ligands and induce intracellular pathways involved in protein synthesis and cellular growth, such as MAPK and PI3K/Akt/S6K pathways. VKRs are not present in vertebrates or in some invertebrate species. Questions remain open about the origin of this little-known RTK family in evolution and its role in emergence and specialization of Metazoa. What is the meaning of maintenance or loss of VKR in some phyla or species in terms of development and physiological functions? The presence of VKRs in invertebrates of economical and medical importance, such as pests, vectors of pathogens, and platyhelminth parasites, and the implication of these RTKs in gametogenesis and reproduction processes are valuable reasons to consider VKRs as interesting targets in new programs for eradication/control of pests and infectious diseases, with the main advantage in the case of parasite targeting that VKR counterparts are absent from the vertebrate host kinase panel. PMID:24860549

Dissous, Colette; Morel, Marion; Vanderstraete, Mathieu

2014-01-01

429

Developmentally regulated expression, alternative splicing and distinct sub-groupings in members of the Schistosoma mansoni venom allergen-like (SmVAL) gene family  

PubMed Central

Background The Sperm-coating protein/Tpx-1/Ag5/PR-1/Sc7 (SCP/TAPS) domain is found across phyla and is a major structural feature of insect allergens, mammalian sperm proteins and parasitic nematode secreted molecules. Proteins containing this domain are implicated in diverse biological activities and may be important for chronic host/parasite interactions. Results We report the first description of an SCP/TAPS gene family (Schistosoma mansoni venom allergen-like (SmVALs)) in the medically important Platyhelminthes (class Trematoda) and describe individual members' phylogenetic relationships, genomic organization and life cycle expression profiles. Twenty-eight SmVALs with complete SCP/TAPS domains were identified and comparison of their predicted protein features and gene structures indicated the presence of two distinct sub-families (group 1 & group 2). Phylogenetic analysis demonstrated that this group 1/group 2 split is zoologically widespread as it exists across the metazoan sub-kingdom. Chromosomal localisation and PCR analysis, coupled to inspection of the current S. mansoni genomic assembly, revealed that many of the SmVAL genes are spatially linked throughout the genome. Quantitative lifecycle expression profiling demonstrated distinct SmVAL expression patterns, including transcripts specifically associated with lifestages involved in definitive host invasion, transcripts restricted to lifestages involved in the invasion of the intermediate host and transcripts ubiquitously expressed. Analysis of SmVAL6 transcript diversity demonstrated statistically significant, developmentally regulated, alternative splicing. Conclusion Our results highlight the existence of two distinct SCP/TAPS protein types within the Platyhelminthes and across taxa. The extensive lifecycle expression analysis indicates several SmVAL transcripts are upregulated in infective stages of the parasite, suggesting that these particular protein products may be linked to the establishment of chronic host/parasite interactions. PMID:18294395

Chalmers, Iain W; McArdle, Andrew J; Coulson, Richard MR; Wagner, Marissa A; Schmid, Ralf; Hirai, Hirohisa; Hoffmann, Karl F

2008-01-01

430

Opioid receptor types involved in the development of nicotine physical dependence in an invertebrate (Planaria) model.  

PubMed

Recent data suggest that opioid receptors are involved in the development of nicotine physical dependence in mammals. Evidence in support of a similar involvement in an invertebrate (Planaria) is presented using the selective opioid receptor antagonist naloxone, and the more receptor subtype-selective antagonists CTAP (D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2) (?, MOR), naltrindole (?, DOR), and nor-BNI (norbinaltorphimine) (?, KOR). Induction of physical dependence was achieved by 60-min pre-exposure of planarians to nicotine and was quantified by abstinence-induced withdrawal (reduction in spontaneous locomotor activity). Known MOR and DOR subtype-selective opioid receptor antagonists attenuated the withdrawal, as did the non-selective antagonist naloxone, but a KOR subtype-selective antagonist did not. An involvement of MOR and DOR, but not KOR, in the development of nicotine physical dependence or in abstinence-induced withdrawal was thus demonstrated in a sensitive and facile invertebrate model. PMID:24084318

Raffa, Robert B; Baron, Steve; Bhandal, Jaspreet S; Brown, Tevin; Song, Kevin; Tallarida, Christopher S; Rawls, Scott M

2013-11-01

431

Opening the genetic toolbox of niche model organisms with high throughput techniques: novel proteins in regeneration as a case study.  

PubMed

Understanding in vivo regeneration of complex structures offers a fascinating perspective for translation into medical applications. Unfortunately, mammals in general lack large-scale regenerative capacity, whereas planarians, newts or Hydra can regenerate complete body parts. Such organisms are, however, poorly annotated because of the lack of sequence information. This leads to limited access for molecular biological investigations. In the last decade, high throughput technologies and new methods enabling the effective generation of transgenic animals have rapidly evolved. These developments have allowed the extensive use of niche model organisms as part of a trend towards the accessibility of a greater panel of model species for scientific research. The case study that follows provides an insight into the impact of high throughput techniques on the landscape of models of regeneration. The cases presented here give evidence of alternative stem cell maintenance pathways, the identification of new protein families and new stem cell markers. PMID:24741707

Looso, Mario

2014-04-01

432

Evolutionarily Conserved Repulsive Guidance Role of Slit in the Silkworm Bombyx mori  

PubMed Central

Axon guidance molecule Slit is critical for the axon repulsion in neural tissues, which is evolutionarily conserved from planarians to humans. However, the function of Slit in the silkworm Bombyx mori was unknown. Here we showed that the structure of Bombyx mori Slit (BmSlit) was different from that in most other species in its C-terminal sequence. BmSlit was localized in the midline glial cell, the neuropil, the tendon cell, the muscle and the silk gland and colocalized with BmRobo1 in the neuropil, the muscle and the silk gland. Knock-down of Bmslit by RNA interference (RNAi) resulted in abnormal development of axons and muscles. Our results suggest that BmSlit has a repulsive role in axon guidance and muscle migration. Moreover, the localization of BmSlit in the silk gland argues for its important function in the development of the silk gland. PMID:25285792

Liu, Chun; Cui, Wei-Zheng; Mu, Zhi-Mei; Zhao, Xiao; Liu, Qing-Xin

2014-01-01

433

A common cellular basis for muscle regeneration in arthropods and vertebrates.  

PubMed

Many animals are able to regenerate amputated or damaged body parts, but it is unclear whether different taxa rely on similar strategies. Planarians and vertebrates use different strategies, based on pluripotent versus committed progenitor cells, respectively, to replace missing tissues. In most animals, however, we lack the experimental tools needed to determine the origin of regenerated tissues. Here, we present a genetically tractable model for limb regeneration, the crustacean Parhyale hawaiensis. We demonstrate that regeneration in Parhyale involves lineage-committed progenitors, as in vertebrates. We discover Pax3/7-expressing muscle satellite cells, previously identified only in chordates, and show that these cells are a source of regenerating muscle in Parhyale. These similarities point to a common cellular basis of regeneration, dating back to the common ancestors of bilaterians. PMID:24385602

Konstantinides, Nikolaos; Averof, Michalis

2014-02-14

434

Deep sequencing identifies regulated small RNAs in Dugesia japonica.  

PubMed

MicroRNAs (miRNAs), which are 18 ~ 24 nucleotides length, play important roles in regulating the expression of gene at the post-transcription level. Dugesia japonica is a branch of planarian organism. It is a model organism for studying the role of miRNAs in stem cell function. Next generation sequencing technology was used to identify the miRNAs of D. japonica. Bioinformatic analysis showed that 262 miRNA and miRNA* sequences were discovered, of which 102 miRNAs were the same as Schmidtea mediterranea and 160 miRNAs were related to other animals. There were 21 miRNAs expressed differentially after amputation. Results also revealed that some key miRNAs might play essential roles in the regeneration progress and some miRNAs might take part in the regulation progress of polarity regeneration in D. japonica. PMID:23314792

Xu, Zhenbiao; Chen, Maoshan; Ren, Zhonggan; Zhang, Nian; Xu, Hanmei; Liu, Xiao; Tian, Geng; Song, Linxia; Yang, Huanming

2013-06-01

435

What RNAi screens in model organisms revealed about microbicidal response in mammals?  

PubMed Central

The strategies evolved by pathogens to infect hosts and the mechanisms used by the host to eliminate intruders are highly complex. Because several biological pathways and processes are conserved across model organisms, these organisms have been used for many years to elucidate and understand the mechanisms of the host-pathogen relationship and particularly to unravel the molecular processes enacted by the host to kill pathogens. The emergence of RNA interference (RNAi) and the ability to apply it toward studies in model organisms have allowed a breakthrough in the elucidation of host-pathogen interactions. The aim of this mini-review is to highlight and describe recent breakthroughs in the field of host-pathogen interactions using RNAi screens of model organisms. We will focus specifically on the model organisms Drosophila melanogaster, Caenorhabditis elegans, and Danio rerio. Moreover, a recent study examining the immune system of planarian will be discussed. PMID:25629007

Abnave, Prasad; Conti, Filippo; Torre, Cedric; Ghigo, Eric

2015-01-01

436

SAPling: a Scan-Add-Print barcoding database system to label and track asexual organisms  

PubMed Central

SUMMARY We have developed a ‘Scan-Add-Print’ database system, SAPling, to track and monitor asexually reproducing organisms. Using barcodes to uniquely identify each animal, we can record information on the life of the individual in a computerized database containing its entire family tree. SAPling has enabled us to carry out large-scale population dynamics experiments with thousands of planarians and keep track of each individual. The database stores information such as family connections, birth date, division date and generation. We show that SAPling can be easily adapted to other asexually reproducing organisms and has a strong potential for use in large-scale and/or long-term population and senescence studies as well as studies of clonal diversity. The software is platform-independent, designed for reliability and ease of use, and provided open source from our webpage to allow project-specific customization. PMID:21993779

Thomas, Michael A.; Schötz, Eva-Maria

2011-01-01

437

Multiple isoform recovery (MIR)-PCR: a simple method for the isolation of related mRNA isoforms.  

PubMed Central

We present a rapid and efficient method for the detection of related transcripts with different expression levels. This approach combines the rapid amplification of cDNA ends (RACE) method with a cDNA subtractive technique. The strategy is based on successive subtractions of prevalent isoforms resulting in enrichment of less expressed transcripts. For each subtraction, a biotinylated primer specific for the prevalent isoform is hybridized on the total cDNA and the hybrid is retained on a streptavidin affinity column. The unbound cDNA serves as a template for subsequent isoform identification. To illustrate its application we describe the isolation of three new actin cDNA isoforms in the freshwater planarian Dugesia (S) polychroa. PMID:9518500

Fagotti, A; Gabbiani, G; Pascolini, R; Neuville, P

1998-01-01

438

Evolution of multicellular animals as deduced from 5S rRNA sequences: a possible early emergence of the Mesozoa.  

PubMed Central

The nucleotide sequences of 5S rRNA from a mesozoan Dicyema misakiense and three metazoan species, i.e., an acorn-worm Saccoglossus kowalevskii, a moss-animal Bugula neritina, and an octopus Octopus vulgaris have been determined. A phylogenic tree of multicellular animals has been constructed from 73 5S rRNA sequences available at present including those from the above four sequences. The tree suggests that the mesozoan is the most ancient multicellular animal identified so far, its emergence time being almost the same as that of flagellated or ciliated protozoans. The branching points of planarians and nematodes are a little later than that of the mesozoan but are clearly earlier than other metazoan groups including sponges and jellyfishes. Many metazoan groups seem to have diverged within a relatively short period. PMID:6539911

Ohama, T; Kumazaki, T; Hori, H; Osawa, S

1984-01-01

439

Evolution of multicellular animals as deduced from 5S rRNA sequences: a possible early emergence of the Mesozoa.  

PubMed

The nucleotide sequences of 5S rRNA from a mesozoan Dicyema misakiense and three metazoan species, i.e., an acorn-worm Saccoglossus kowalevskii, a moss-animal Bugula neritina, and an octopus Octopus vulgaris have been determined. A phylogenic tree of multicellular animals has been constructed from 73 5S rRNA sequences available at present including those from the above four sequences. The tree suggests that the mesozoan is the most ancient multicellular animal identified so far, its emergence time being almost the same as that of flagellated or ciliated protozoans. The branching points of planarians and nematodes are a little later than that of the mesozoan but are clearly earlier than other metazoan groups including sponges and jellyfishes. Many metazoan groups seem to have diverged within a relatively short period. PMID:6539911

Ohama, T; Kumazaki, T; Hori, H; Osawa, S

1984-06-25

440

A Colony Multiplex Quantitative PCR-Based 3S3DBC Method and Variations of It for Screening DNA Libraries  

PubMed Central

A DNA library is a collection of DNA fragments cloned into vectors and stored individually in host cells, and is a valuable resource for molecular cloning, gene physical mapping, and genome sequencing projects. To take the best advantage of a DNA library, a good screening method is needed. After describing pooling strategies and issues that should be considered in DNA library screening, here we report an efficient colony multiplex quantitative PCR-based 3-step, 3-dimension, and binary-code (3S3DBC) method we used to screen genes from a planarian genomic DNA fosmid library. This method requires only 3 rounds of PCR reactions and only around 6 hours to distinguish one or more desired clones from a large DNA library. According to the particular situations in different research labs, this method can be further modified and simplified to suit their requirements. PMID:25646755

An, Yang; Toyoda, Atsushi; Zhao, Chen; Fujiyama, Asao; Agata, Kiyokazu

2015-01-01

441

Cell death: a program to regenerate.  

PubMed

Recent studies in Drosophila, Hydra, planarians, zebrafish, mice, indicate that cell death can open paths to regeneration in adult animals. Indeed injury can induce cell death, itself triggering regeneration following an immediate instructive mechanism, whereby the dying cells release signals that induce cellular responses over short and/or long-range distances. Cell death can also provoke a sustained derepressing response through the elimination of cells that suppress regeneration in homeostatic conditions. Whether common properties support what we name "regenerative cell death," is currently unclear. As key parameters, we review here the injury proapoptotic signals, the signals released by the dying cells, the cellular responses, and their respective timing. ROS appears as a common signal triggering cell death through MAPK and/or JNK pathway activation. But the modes of ROS production vary, from a brief pulse upon wounding, to repeated waves as observed in the zebrafish fin where ROS supports two peaks of cell death. Indeed regenerative cell death can be restricted to the injury phase, as in Hydra, Drosophila, or biphasic, immediate, and delayed, as in planarians and zebrafish. The dying cells release in a caspase-dependent manner a variety of signaling molecules, cytokines, growth factors, but also prostaglandins or ATP as recorded in Drosophila, Hydra, mice, and zebrafish, respectively. Interestingly, the ROS-producing cells often resist to cell death, implying a complex paracrine mode of signaling to launch regeneration, involving ROS-producing cells, ROS-sensing cells that release signaling molecules upon caspase activation, and effector cells that respond to these signals by proliferating, migrating, and/or differentiating. PMID:24512708

Vriz, Sophie; Reiter, Silke; Galliot, Brigitte

2014-01-01

442

[Dopaminergic neuroprotection and reconstruction of neural network tiara].  

PubMed

Parkinson's disease (PD) is an age-related neurodegenerative disorder in whose brain massive loss of dopaminergic neurons and formation of Lewy bodies occur in the substantia nigra (SN). L-Dihydroxyphenylamine (L-DOPA) substitution is still considered the gold standard of antiparkinsonian drug therapy. However, there has been little information available on neuroprotective and regenerative therapies. Recently, we have found that pramipexole and talipexole (D(2)/D(3)-dopaminergic agonists) inhibit dopaminergic neurotoxin-induced production of reactive oxygen species and apoptotic cell death. In addition, treatment with these drugs induces enhancement of anti-apoptotic Bcl-2 expression and inhibition of ?-synuclein aggregation. Interestingly, recent study suggests that pramipexole treatment delays the progression of early PD symptom. On the other hand, we investigated the transplantation strategy for PD by assessing whether double-transplants of mouse embryonic stem (ES) cell-derived neurons in the striatum (ST) and SN, or subthalamic nucleus (STN), induce functional recovery in rat hemi-parkinsonian model. The study indicates that both the involvement of ST as a place of transplantation and the number of ES cell-derived neurons are essential factors for efficacy on PD animal model. Interestingly, an invertebrate planarian can regenerate complete organs, including a well-organized central nervous system (brain), within about 7 days. The regeneration process of the planarian dopaminergic neural network (tiara) may be divided into five steps: 1) anterior blastema formation, 2) brain rudiment formation, 3) brain pattern formation, 4) the formation of dopaminergic tiara, and 5) functional recovery of dopaminergic motor regulation, with several kinds of genes and molecular cascades acting at each step. PMID:20930477

Kitamura, Yoshihisa

2010-10-01

443

Stereochemistry and neuropharmacology of a 'bath salt' cathinone: S-enantiomer of mephedrone reduces cocaine-induced reward and withdrawal in invertebrates.  

PubMed

Knowledge about the neuropharmacology of mephedrone (MEPH) applies primarily to the racemate, or street form of the drug, but not to its individual enantiomers. Here, through chemical isolation of MEPH enantiomers and subsequent behavioral characterization in established invertebrate (planarian) assays, we began separating adverse effects of MEPH from potential therapeutic actions. We first compared stereotypical and environmental place conditioning (EPC) effects of racemic MEPH, S-MEPH, and R-MEPH. Stereotypy was enhanced by acute treatment (100-1000 ?M) with each compound; however, S-MEPH was less potent and efficacious than racemate and R-MEPH. Both R-MEPH (10, 100, 250 ?M) and racemate (100 ?M) produced EPC, but S-MEPH was ineffective at all concentrations (10-100 ?M). After showing that S-MEPH lacked rewarding efficacy, we investigated its ability to alter three of cocaine's behavioral effects (EPC, withdrawal, and stereotypy). Cocaine (1 ?M) produced EPC that was abolished when S-MEPH (100 ?M) was administered after cocaine conditioning. Spontaneous withdrawal from chronic cocaine exposure caused a reduction in motility that was not evident during acute or continuous cocaine treatment but was attenuated by S-MEPH (100 ?M) treatment during the cocaine abstinence interval. Acute stereotypy produced by 1 mM cocaine, nicotine or racemic MEPH was not affected by S-MEPH (10-250 ?M). The present results obtained using planarian assays suggest that the R-enantiomer of MEPH is predominantly responsible for its stimulant and rewarding effects and the S-enantiomer is capable of antagonizing cocaine's addictive-like behaviors without producing rewarding effects of its own. PMID:25496724

Vouga, Alexandre; Gregg, Ryan A; Haidery, Maryah; Ramnath, Anita; Al-Hassani, Hassan K; Tallarida, Christopher S; Grizzanti, David; Raffa, Robert B; Smith, Garry R; Reitz, Allen B; Rawls, Scott M

2015-04-01

444

Synaptonemal complex extension from clustered telomeres mediates full-length chromosome pairing in Schmidtea mediterranea.  

PubMed

In the 1920s, József Gelei proposed that chromosome pairing in flatworms resulted from the formation of a telomere bouquet followed by the extension of synapsis from telomeres at the base of the bouquet, thus facilitating homolog pairing in a processive manner. A modern interpretation of Gelei's model postulates that the synaptonemal complex (SC) is nucleated close to the telomeres and then extends progressively along the full length of chromosome arms. We used the easily visible meiotic chromosomes, a well-characterized genome, and RNAi in the sexual biotype of the planarian Schmidtea mediterranea to test that hypothesis. By identifying and characterizing S. mediterranea homologs of genes encoding synaptonemal complex protein 1 (SYCP1), the topoisomerase-like protein SPO11, and RAD51, a key player in homologous recombination, we confirmed that SC formation begins near the telomeres and progresses along chromosome arms during zygotene. Although distal regions pair at the time of bouquet formation, pairing of a unique interstitial locus is not observed until the formation of full-length SC at pachytene. Moreover, neither full extension of the SC nor homologous pairing is dependent on the formation of double-strand breaks. These findings validate Gelei's speculation that full-length pairing of homologous chromosomes is mediated by the extension of the SC formed near the telomeres. S. mediterranea thus becomes the first organism described (to our knowledge) that forms a canonical telomere bouquet but does not require double-strand breaks for synapsis between homologous chromosomes. However, the initiation of SC formation at the base of the telomere bouquet, which then is followed by full-length homologous pairing in planarian spermatocytes, is not observed in other species and may not be conserved. PMID:25404302

Xiang, Youbin; Miller, Danny E; Ross, Eric J; Sánchez Alvarado, Alejandro; Hawley, R Scott

2014-12-01

445

The invasive New Guinea flatworm Platydemus manokwari in France, the first record for Europe: time for action is now  

PubMed Central

Non-indigenous terrestrial flatworms (Platyhelminthes) have been recorded in thirteen European countries. They include Bipalium kewense and Dolichoplana striata that are largely restricted to hothouses and may be regarded as non-invasive species. In addition there are species from the southern hemisphere such as the invasive New Zealand flatworm Arthurdendyus triangulatus in the United Kingdom, Eire and the Faroe Islands, the Australian flatworm Australoplana sanguinea alba in Eire and the United Kingdom, and the Australian Blue Garden flatworm Caenoplana coerulea in France, Menorca and the United Kingdom. The United Kingdom has some twelve or more non-indigenous species most of which are Australian and New Zealand species. These species may move to an invasive stage when optimum environmental and other conditions occur, and the flatworms then have the potential to cause economic or environmental harm. In this paper, we report the identification (from morphology and molecular analysis of COI sequences) of non-indigenous terrestrial flatworms found in a hothouse in Caen (France) as the New Guinea flatworm Platydemus manokwari de Beauchamp, 1963 (Platyhelminthes, Continenticola, Geoplanidae, Rhynchodeminae). Platydemus manokwari is among the “100 World’s Worst Invader Alien Species”. Lists of World geographic records, prey in the field and prey in laboratories of P. manokwari are provided. This species is considered a threat to native snails wherever it is introduced. The recent discovery of P. manokwari in France represents a significant extension of distribution of this Invasive Alien Species from the Indo-Pacific region to Europe. If it escaped the hothouse, the flatworm might survive winters and become established in temperate countries. The existence of this species in France requires an early warning of this incursion to State and European Union authorities, followed by the eradication of the flatworm in its locality, tightening of internal quarantine measures to prevent further spread of the flatworm to and from this site, identifying if possible the likely primary source of the flatworm, and tracing other possible incursions that may have resulted from accidental dispersal of plants and soil from the site. PMID:24688873

Winsor, Leigh; Gey, Delphine; Gros, Pierre; Thévenot, Jessica

2014-01-01

446

The invasive New Guinea flatworm Platydemus manokwari in France, the first record for Europe: time for action is now.  

PubMed

Non-indigenous terrestrial flatworms (Platyhelminthes) have been recorded in thirteen European countries. They include Bipalium kewense and Dolichoplana striata that are largely restricted to hothouses and may be regarded as non-invasive species. In addition there are species from the southern hemisphere such as the invasive New Zealand flatworm Arthurdendyus triangulatus in the United Kingdom, Eire and the Faroe Islands, the Australian flatworm Australoplana sanguinea alba in Eire and the United Kingdom, and the Australian Blue Garden flatworm Caenoplana coerulea in France, Menorca and the United Kingdom. The United Kingdom has some twelve or more non-indigenous species most of which are Australian and New Zealand species. These species may move to an invasive stage when optimum environmental and other conditions occur, and the flatworms then have the potential to cause economic or environmental harm. In this paper, we report the identification (from morphology and molecular analysis of COI sequences) of non-indigenous terrestrial flatworms found in a hothouse in Caen (France) as the New Guinea flatworm Platydemus manokwari de Beauchamp, 1963 (Platyhelminthes, Continenticola, Geoplanidae, Rhynchodeminae). Platydemus manokwari is among the "100 World's Worst Invader Alien Species". Lists of World geographic records, prey in the field and prey in laboratories of P. manokwari are provided. This species is considered a threat to native snails wherever it is introduced. The recent discovery of P. manokwari in France represents a significant extension of distribution of this Invasive Alien Species from the Indo-Pacific region to Europe. If it escaped the hothouse, the flatworm might survive winters and become established in temperate countries. The existence of this species in France requires an early warning of this incursion to State and European Union authorities, followed by the eradication of the flatworm in its locality, tightening of internal quarantine measures to prevent further spread of the flatworm to and from this site, identifying if possible the likely primary source of the flatworm, and tracing other possible incursions that may have resulted from accidental dispersal of plants and soil from the site. PMID:24688873

Justine, Jean-Lou; Winsor, Leigh; Gey, Delphine; Gros, Pierre; Thévenot, Jessica

2014-01-01

447

Modular evolution of glutathione peroxidase genes in association with different biochemical properties of their encoded proteins in invertebrate animals  

PubMed Central

Background Phospholipid hydroperoxide glutathione peroxidases (PHGPx), the most abundant isoforms of GPx families, interfere directly with hydroperoxidation of lipids. Biochemical properties of these proteins vary along with their donor organisms, which has complicated the phylogenetic classification of diverse PHGPx-like proteins. Despite efforts for comprehensive analyses, the evolutionary aspects of GPx genes in invertebrates remain largely unknown. Results We isolated GPx homologs via in silico screening of genomic and/or expressed sequence tag databases of eukaryotic organisms including protostomian species. Genes showing strong similarity to the mammalian PHGPx genes were commonly found in all genomes examined. GPx3- and GPx7-like genes were additionally detected from nematodes and platyhelminths, respectively. The overall distribution of the PHGPx-like proteins with different biochemical properties was biased across taxa; selenium- and glutathione (GSH)-dependent proteins were exclusively detected in platyhelminth and deuterostomian species, whereas selenium-independent and thioredoxin (Trx)-dependent enzymes were isolated in the other taxa. In comparison of genomic organization, the GSH-dependent PHGPx genes showed a conserved architectural pattern, while their Trx-dependent counterparts displayed complex exon-intron structures. A codon for the resolving Cys engaged in reductant binding was found to be substituted in a series of genes. Selection pressure to maintain the selenocysteine codon in GSH-dependent genes also appeared to be relaxed during their evolution. With the dichotomized fashion in genomic organizations, a highly polytomic topology of their phylogenetic trees implied that the GPx genes have multiple evolutionary intermediate forms. Conclusion Comparative analysis of invertebrate GPx genes provides informative evidence to support the modular pathways of GPx evolution, which have been accompanied with sporadic expansion/deletion and exon-intron remodeling. The differentiated enzymatic properties might be acquired by the evolutionary relaxation of selection pressure and/or biochemical adaptation to the acting environments. Our present study would be beneficial to get detailed insights into the complex GPx evolution, and to understand the molecular basis of the specialized physiological implications of this antioxidant system in their respective donor organisms. PMID:19344533

Bae, Young-An; Cai, Guo-Bin; Kim, Seon-Hee; Zo, Young-Gun; Kong, Yoon

2009-01-01

448

The ultrastructure of hypersymbionts on the monogenean Gyrodactylus salaris infecting Atlantic salmon Salmo salar.  

PubMed

There is increasing pressure to develop alternative control strategies against the pathogen Gyrodactylus salaris, which has devastated wild Atlantic salmon Salmo salar in Norway. Hyperparasitism is one option for biological control and electron microscopy has revealed two ectosymbionts associated with G. salaris: unidentified rod-shaped bacteria, and the protist, Ichthyobodo necator. No endosymbionts were detected. The flagellate I. necator occurred only occasionally on fish suffering costiosis, whereas bacterial infections on the tegument of G. salaris were observed throughout the year, but at variable densities. Bacteria were seldom observed attached to fish epidermis, even when individuals of G. salaris on the same host were heavily infected. Wounds on salmon epidermis caused by the feeding activity of bacteria-infected G. salaris did not appear to be infected with bacteria. On heavily infected gyrodactylids, bacteria were most abundant anteriorly on the cephalic lobes, including the sensory structures, but no damaged tissue was detected by transmission electron microscopy in the region of bacterial adherence. Furthermore, transmission and survival of infected G. salaris on wild salmon did not appear to be influenced by the bacterial infection. The lack of structural damage and impact on G. salaris biology indicates that these bacteria are not a potential agent for control of gyrodactylosis. However, this may not be the case for all gyrodactylid-bacterial interactions and a review of bacterial infections of platyhelminths is presented. PMID:17125547

Bakke, T A; Cable, J; Ostbø, M

2006-12-01

449

Mixed Infections and Hybridisation in Monogenean Parasites  

PubMed Central

Theory predicts that sexual reproduction promotes disease invasion by increasing the evolutionary potential of the parasite, whereas asexual reproduction tends to enhance establishment success and population growth rate. Gyrodactylid monogeneans are ubiquitous ectoparasites of teleost fish, and the evolutionary success of the specious Gyrodactylus genus is thought to be partly due to their use of various modes of reproduction. Gyrodactylus turnbulli is a natural parasite of the guppy (Poecilia reticulata), a small, tropical fish used as a model for behavioural, ecological and evolutionary studies. Using experimental infections and a recently developed microsatellite marker, we conclusively show that monogenean parasites reproduce sexually. Conservatively, we estimate that sexual recombination occurs and that between 3.7–10.9% of the parasites in our experimental crosses are hybrid genotypes with ancestors from different laboratory strains of G. turnbulli. We also provide evidence of hybrid vigour and/or inter-strain competition, which appeared to lead to a higher maximum parasite load in mixed infections. Finally, we demonstrate inbreeding avoidance for the first time in platyhelminths which may influence the distribution of parasites within a host and their subsequent exposure to the host's localized immune response. Combined reproductive modes and inbreeding avoidance may explain the extreme evolutionary diversification success of parasites such as Gyrodactylus, where host-parasite coevolution is punctuated by relatively frequent host switching. PMID:22808040

Schelkle, Bettina; Faria, Patricia J.; Johnson, Mireille B.; van Oosterhout, Cock; Cable, Joanne

2012-01-01

450

Enhanced primers for amplification of DNA barcodes from a broad range of marine metazoans  

PubMed Central

Background Building reference libraries of DNA barcodes is relatively straightforward when specifically designed primers are available to amplify the COI-5P region from a relatively narrow taxonomic group (e.g. single class or single order). DNA barcoding marine communities have been comparatively harder to accomplish due to the broad taxonomic diversity and lack of consistently efficient primers. Although some of the so-called “universal” primers have been relatively successful, they still fail to amplify COI-5P of many marine animal groups, while displaying random success even among species within each group. Here we propose a new pair of primers designed to enhance amplification of the COI-5P region in a wide range of marine organisms. Results Amplification tests conducted on a wide range of marine animal taxa, rendered possible the first–time sequencing of DNA barcodes from eight separated phyla (Annelida, Arthropoda, Chordata, Cnidaria, Echinodermata, Mollusca, Nemertea and Platyhelminthes), comprising a total of 14 classes, 28 orders, 57 families, 68 genus and 76 species. Conclusions These primers demonstrated to be highly cost-effective, which is of key importance for DNA barcoding procedures, such as for building comprehensive DNA barcode libraries of marine communities, where the processing of a large numbers of specimens from a wide variety of marine taxa is compulsory. PMID:24020880

2013-01-01

451

The Global Invertebrate Genomics Alliance (GIGA): Developing Community Resources to Study Diverse Invertebrate Genomes  

PubMed Central

Over 95% of all metazoan (animal) species comprise the “invertebrates,” but very few genomes from these organisms have been sequenced. We have, therefore, formed a “Global Invertebrate Genomics Alliance” (GIGA). Our intent is to build a collaborative network of diverse scientists to tackle major challenges (e.g., species selection, sample collection and storage, sequence assembly, annotation, analytical tools) associated with genome/transcriptome sequencing across a large taxonomic spectrum. We aim to promote standards that will facilitate comparative approaches to invertebrate genomics and collaborations across the international scientific community. Candidate study taxa include species from Porifera, Ctenophora, Cnidaria, Placozoa, Mollusca, Arthropoda, Echinodermata, Annelida, Bryozoa, and Platyhelminthes, among others. GIGA will target 7000 noninsect/nonnematode species, with an emphasis on marine taxa because of the unrivaled phyletic diversity in the oceans. Priorities for selecting invertebrates for sequencing will include, but are not restricted to, their phylogenetic placement; relevance to organismal, ecological, and conservation research; and their importance to fisheries and human health. We highlight benefits of sequencing both whole genomes (DNA) and transcriptomes and also suggest policies for genomic-level data access and sharing based on transparency and inclusiveness. The GIGA Web site (http://giga.nova.edu) has been launched to facilitate this collaborative venture. PMID:24336862

2014-01-01

452

ClonorESTdb: a comprehensive database for Clonorchis sinensis EST sequences  

PubMed Central

Background Clonorchiasis, which is primarily caused by liver fluke (Platyhelminthes), is a fatal infectious disease that is mainly associated with bile duct malignancy and the subsequent development of cholangiocarcinoma. Thus, a genomic approach now represents an important step to further our knowledge of biology and the pathology of these parasites. The results of expressed sequence tags (ESTs) sequencing need to be well organized into databases to provide an integrated set of tools and functional information. Findings Here, the ClonorESTdb database represents a collection of Clonorchis sinensis ESTs that is intended as a resource for parasite functional genomics. A total of 55,736 successful EST sequences, which are cleaned and clustered into non-redundant 13,305 C. sinensis assembled EST sequences (6,497 clusters and 6,808 singletons), were obtained from three in-house prepared cDNA libraries of C. sinensis at different developmental stages. The assembled consensus sequences were annotated using the BLAST algorithm or/and hmm against NCBI NR, UniProt, KEGG and InterProScan. The ClonorESTdb database provides functional annotation, their expression profiles, tandem repeats and putative single nucleotide polymorphisms with utility tools such as local BLAST search and text retrieval. Conclusions This resource enables the researcher to identify and compare expression signatures under different biological stages and promotes ongoing parasite drug and vaccine development and biological research. Database URL: http://pathod.cdc.go.kr/clonorestdb/ PMID:24957044

2014-01-01

453

Gene suppression in schistosomes using RNAi.  

PubMed

Schistosomiasis is a neglected tropical disease responsible for the death of more than 300,000 people every year. The disease is caused by intravascular parasitic platyhelminths called schistosomes. Treatment and control of schistosomiasis rely on a single drug, praziquantel, and concern exists over the possible emergence of resistance to this drug. The recent completion of the genome sequences of the three main worm species that cause schistosomiasis in humans has raised hope for the development of new interventions to treat the disease. RNA interference (RNAi), a mechanism by which gene-specific double-stranded RNA (dsRNA) triggers degradation of homologous mRNA transcripts, has emerged as an important tool to evaluate and validate new potential drug targets. In addition, RNAi has been used to explore the basic biology of these debilitating parasites. RNAi can be achieved in all stages of the parasite's life cycle in which it has been tested. In this review, we describe methods for applying RNAi to suppress gene expression in the intra-mammalian life stages (adults and schistosomula) of Schistosoma mansoni. We describe procedures for isolating and culturing the parasites, preparing and delivering dsRNA targeting a specific gene, as well as a procedure to evaluate gene suppression by quantitative real-time PCR. PMID:25388112

Da'dara, Akram A; Skelly, Patrick J

2015-01-01

454

Invasive species threat: parasite phylogenetics reveals patterns and processes of host-switching between non-native and native captive freshwater turtles.  

PubMed

One of the major threats to biodiversity involves biological invasions with direct consequences on the stability of ecosystems. In this context, the role of parasites is not negligible as it may enhance the success of invaders. The red-eared slider, Trachemys scripta elegans, has been globally considered among the worst invasive species. Since its introduction through the pet trade, T. s. elegans is now widespread and represents a threat for indigenous species. Because T. s. elegans coexists with Emys orbicularis and Mauremys leprosa in Europe, it has been suggested it may compete with the native turtle species and transmit pathogens. We examined parasite transfer from American captive to the two native species that co-exist in artificial pools of a Turtle Farm in France. As model parasite species we used platyhelminth worms of the family Polystomatidae (Monogenea) because polystomes have been described from American turtles in their native range. Phylogenetic relationships among polystomes parasitizing chelonian host species that are geographically widespread show patterns of diversification more complex than expected. Using DNA barcoding to identify species from adult and/or polystome eggs, several cases of host switching from exotic to indigenous individuals were illustrated, corroborating that parasite transmission is important when considering the pet trade and in reintroduction programmes to reinforce wild populations of indigenous species. PMID:21767431

Verneau, O; Palacios, C; Platt, T; Alday, M; Billard, E; Allienne, J-F; Basso, C; DU Preez, L H

2011-11-01

455

What helminth genomes have taught us about parasite evolution.  

PubMed

SUMMARY The genomes of more than 20 helminths have now been sequenced. Here we perform a meta-analysis of all sequenced genomes of nematodes and Platyhelminthes, and attempt to address the question of what are the defining characteristics of helminth genomes. We find that parasitic worms lack systems for surface antigenic variation, instead maintaining infections using their surfaces as the first line of defence against the host immune system, with several expanded gene families of genes associated with the surface and tegument. Parasite excretory/secretory products evolve rapidly, and proteases even more so, with each parasite exhibiting unique modifications of its protease repertoire. Endoparasitic flatworms show striking losses of metabolic capabilities, not matched by nematodes. All helminths do however exhibit an overall reduction in auxiliary metabolism (biogenesis of co-factors and vitamins). Overall, the prevailing pattern is that there are few commonalities between the genomes of independently evolved parasitic worms, with each parasite having undergone specific adaptations for their particular niche. PMID:25482650

Zarowiecki, Magdalena; Berriman, Matt

2015-02-01

456

Evolutionarily Ancient Association of the FoxJ1 Transcription Factor with the Motile Ciliogenic Program  

PubMed Central

It is generally believed that the last eukaryotic common ancestor (LECA) was a unicellular organism with motile cilia. In the vertebrates, the winged-helix transcription factor FoxJ1 functions as the master regulator of motile cilia biogenesis. Despite the antiquity of cilia, their highly conserved structure, and their mechanism of motility, the evolution of the transcriptional program controlling ciliogenesis has remained incompletely understood. In particular, it is presently not known how the generation of motile cilia is programmed outside of the vertebrates, and whether and to what extent the FoxJ1-dependent regulation is conserved. We have performed a survey of numerous eukaryotic genomes and discovered that genes homologous to foxJ1 are restricted only to organisms belonging to the unikont lineage. Using a mis-expression assay, we then obtained evidence of a conserved ability of FoxJ1 proteins from a number of diverse phyletic groups to activate the expression of a host of motile ciliary genes in zebrafish embryos. Conversely, we found that inactivation of a foxJ1 gene in Schmidtea mediterranea, a platyhelminth (flatworm) that utilizes motile cilia for locomotion, led to a profound disruption in the differentiation of motile cilia. Together, all of these findings provide the first evolutionary perspective into the transcriptional control of motile ciliogenesis and allow us to propose a conserved FoxJ1-regulated mechanism for motile cilia biogenesis back to the origin of the metazoans. PMID:23144623

Ho, Hao Kee; Babu, Deepak; Eitel, Michael; Narasimhan, Vijayashankaranarayanan; Tiku, Varnesh; Westbrook, Jody; Schierwater, Bernd; Roy, Sudipto

2012-01-01

457

New Research Tools for Urogenital Schistosomiasis.  

PubMed

Approximately 200 000 000 people have schistosomiasis (schistosome infection). Among the schistosomes, Schistosoma haematobium is responsible for the most infections, which are present in 110 million people globally, mostly in sub-Saharan Africa. This pathogen causes an astonishing breadth of sequelae: hematuria, anemia, dysuria, stunting, uremia, bladder cancer, urosepsis, and human immunodeficiency virus coinfection. Refined estimates of the impact of schistosomiasis on quality of life suggest that it rivals malaria. Despite S. haematobium's importance, relevant research has lagged. Here, we review advances that will deepen knowledge of S. haematobium. Three sets of breakthroughs will accelerate discoveries in the pathogenesis of urogenital schistosomiasis (UGS): (1) comparative genomics, (2) the development of functional genomic tools, and (3) the use of animal models to explore S. haematobium-host interactions. Comparative genomics for S. haematobium is feasible, given the sequencing of multiple schistosome genomes. Features of the S. haematobium genome that are conserved among platyhelminth species and others that are unique to S. haematobium may provide novel diagnostic and drug targets for UGS. Although there are technical hurdles, the integrated use of these approaches can elucidate host-pathogen interactions during this infection and can inform the development of techniques for investigating schistosomes in their human and snail hosts and the development of therapeutics and vaccines for the control of UGS. PMID:25240172

Rinaldi, Gabriel; Young, Neil D; Honeycutt, Jared D; Brindley, Paul J; Gasser, Robin B; Hsieh, Michael H

2014-09-19

458

Diagnostic PCR can be used to illuminate meiofaunal diets and trophic relationships.  

PubMed

Analysis of the meiofaunal food web is hampered because few prey have features that persist long enough in a predator's digestive tract to allow identification to species. Hence, at least for platyhelminth predators, direct observations of prey preference are almost nonexistent, and where they occur, prey identification is often limited to phylum. Studies using an in vitro approach are rare because they are extremely time-consuming and are subject to the criticism that predators removed from their natural environment may exhibit altered behaviors. Although PCR-based approaches have achieved wide application in food-web analysis, their application to meiofaunal flatworms suffers from a number of limitations. Most importantly, the microscopic size of both the predator and prey does not allow for removal of prey material from the digestive tract of the predator, and thus the challenge is to amplify prey sequences in the presence of large quantities of predator sequence. Here, we report on the successful use of prey-taxon-specific primers in diagnostic PCR to identify, to species level, specific prey items of 13 species of meiofaunal flatworms. Extension of this method will allow, for the first time, the development of a species-level understanding of trophic interactions among the meiofauna. PMID:25071364

Maghsoud, Hanna; Weiss, Austin; Smith, Julian P S; Litvaitis, Marian K; Fegley, Stephen R

2014-06-01

459

Kicking in the Guts: Schistosoma mansoni Digestive Tract Proteins are Potential Candidates for Vaccine Development  

PubMed Central

Schistosomiasis is a debilitating disease that represents a major health problem in at least 74 tropical and subtropical countries. Current disease control strategies consist mainly of chemotherapy, which cannot prevent recurrent re-infection of people living in endemic area. In the last decades, many researchers made a remarkable effort in the search for an effective vaccine to provide long-term protection. Parasitic platyhelminthes of Schistosoma genus, which cause the disease, live in the blood vessels of definitive hosts where they are bathed in host blood for many years. Among the most promising molecules as vaccine candidates are the proteins present in the host–parasite interface, so numerous tegument antigens have been assessed and the achieved protection never got even close to 100%. Besides the tegument, the digestive tract is the other major site of host–parasite interface. Since parasites feed on blood, they need to swallow a considerable amount of blood for nutrient acquisition. Host blood ingested by schistosomes passes through the esophagus and reaches the gut where many peptidases catalyze the proteolysis of blood cells. Recent studies show the emergence of antigens related to the parasite blood feeding, such as esophageal gland proteins, proteases, and other proteins related to nutrient uptake. Herein, we review what is known about Schistosoma mansoni digestive tract proteins, emphasizing the ones described as potential vaccine candidates.

Figueiredo, Barbara Castro-Pimentel; Ricci, Natasha Delaqua; de Assis, Natan Raimundo Gonçalves; de Morais, Suellen Batistoni; Fonseca, Cristina Toscano; Oliveira, Sergio Costa

2015-01-01

460

Spiral cleavage and early embryology of a loxosomatid entoproct and the usefulness of spiralian apical cross patterns for phylogenetic inferences  

PubMed Central

Background Among the four major bilaterian clades, Deuterostomia, Acoelomorpha, Ecdysozoa, and Lophotrochozoa, the latter shows an astonishing diversity of bodyplans. While the largest lophotrochozoan assemblage, the Spiralia, which at least comprises Annelida, Mollusca, Entoprocta, Platyhelminthes, and Nemertea, show a spiral cleavage pattern, Ectoprocta, Brachiopoda and Phoronida (the Lophophorata) cleave radially. Despite a vast amount of recent molecular phylogenetic analyses, the interrelationships of lophotrochozoan phyla remain largely unresolved. Thereby, Entoprocta play a key role, because they have frequently been assigned to the Ectoprocta, despite their differently cleaving embryos. However, developmental data on entoprocts employing modern methods are virtually non-existent and the data available rely exclusively on sketch drawings, thus calling for thorough re-investigation. Results By applying fluorescence staining in combination with confocal microscopy and 3D-imaging techniques, we analyzed early embryonic development of a basal loxosomatid entoproct. We found that cleavage is asynchronous, equal, and spiral. An apical rosette, typical for most spiralian embryos, is formed. We also identified two cross-like cellular arrangements that bear similarities to both, a "molluscan-like" as well as an "annelid-like" cross, respectively. Conclusions A broad comparison of cleavage types and apical cross patterns across Lophotrochozoa shows high plasticity of these character sets and we therefore argue that these developmental traits should be treated and interpreted carefully when used for phylogenetic inferences. PMID:22458754

2012-01-01