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Irina R Arkhipova - One of the best experts on this subject based on the ideXlab platform.
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multitasking of the pirna silencing machinery targeting transposable elements and foreign genes in the Bdelloid Rotifer adineta vaga
Genetics, 2016Co-Authors: Fernando Rodriguez, Irina R ArkhipovaAbstract:RNA-mediated silencing processes play a key role in silencing of transposable elements, especially in the germ line, where piRNAs are responsible for suppressing transposon mobility and maintaining genome integrity. We previously reported that the genome of Adineta vaga , the first sequenced representative of the phylum Rotifera (class Bdelloidea), is characterized by massive levels of horizontal gene transfer, by unusually low transposon content, and by highly diversified RNA-mediated silencing machinery. Here, we investigate genome-wide distribution of pi-like small RNAs, which in A. vaga are 25-31 nucleotides in length and have a strong 5' uridine bias, while lacking ping-pong amplification signatures. In agreement with expectations, 71% of mapped reads corresponded to annotated transposons, with 93% of these reads being in the antisense orientation. Unexpectedly, a significant fraction of piRNAs originates from predicted coding regions corresponding to genes of putatively foreign origin. The distribution of piRNAs across foreign genes is not biased towards 3'-UTRs, instead resembling transposons in uniform distribution pattern throughout the gene body, and in predominantly antisense orientation. We also find that genes with small RNA coverage, including a number of genes of metazoan origin, are characterized by higher occurrence of telomeric repeats in the surrounding genomic regions, and by higher density of transposons in the vicinity, which have the potential to promote antisense transcription. Our findings highlight the complex interplay between RNA-based silencing processes and acquisition of genes at the genome periphery, which can result either in their loss or eventual domestication and integration into the host genome.
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endonuclease containing penelope retrotransposons in the Bdelloid Rotifer adineta vaga exhibit unusual structural features and play a role in expansion of host gene families
Mobile Dna, 2013Co-Authors: Irina R Arkhipova, Irina A Yushenova, Fernando RodriguezAbstract:Background Penelope-like elements (PLEs) are an enigmatic group of retroelements sharing a common ancestor with telomerase reverse transcriptases. In our previous studies, we identified endonuclease-deficient PLEs that are associated with telomeres in Bdelloid Rotifers, small freshwater invertebrates best known for their long-term asexuality and high foreign DNA content. Completion of the high-quality draft genome sequence of the Bdelloid Rotifer Adineta vaga provides us with the opportunity to examine its genomic transposable element (TE) content, as well as TE impact on genome function and evolution.
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genomic evidence for ameiotic evolution in the Bdelloid Rotifer adineta vaga
Nature, 2013Co-Authors: Jean-françois Flot, Boris Hespeels, Xiang Li, Irina R Arkhipova, Benjamin Noel, Etienne G J Danchin, Andreas Hejnol, Bernard HenrissatAbstract:The genome of the asexual Rotifer Adineta vaga lacks homologous chromosomes; instead, its allelic regions are rearranged and sometimes found on the same chromosome in a palindromic fashion, a structure reminiscent of the primate Y chromosome and of other mitotic lineages such as cancer cells.
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A subtelomeric non-LTR retrotransposon Hebe in the Bdelloid Rotifer Adineta vaga is subject to inactivation by deletions but not 5' truncations
Mobile DNA, 2010Co-Authors: Eugene A Gladyshev, Irina R ArkhipovaAbstract:Background Rotifers of the class Bdelloidea are microscopic freshwater invertebrates best known for: their capacity for anhydrobiosis; the lack of males and meiosis; and for the ability to capture genes from other non-metazoan species. Although genetic exchange between these animals might take place by non-canonical means, the overall lack of meiosis and syngamy should greatly impair the ability of transposable elements (TEs) to spread in Bdelloid populations. Previous studies demonstrated that Bdelloid chromosome ends, in contrast to gene-rich regions, harbour various kinds of TEs, including specialized telomere-associated retroelements, as well as DNA TEs and retrovirus-like retrotransposons which are prone to horizontal transmission. Vertically-transmitted retrotransposons have not previously been reported in Bdelloids and their identification and studies of the patterns of their distribution and evolution could help in the understanding of the high degree of TE compartmentalization within Bdelloid genomes. Results We identified and characterized a non-long terminal repeat (LTR) retrotransposon residing primarily in subtelomeric regions of the genome in the Bdelloid Rotifer Adineta vaga . Contrary to the currently prevailing views on the mode of proliferation of non-LTR retrotransposons, which results in frequent formation of 5'-truncated ('dead-on-arrival') copies due to the premature disengagement of the element-encoded reverse transcriptase from its template, this non-LTR element, Hebe , is represented only by non-5'-truncated copies. Most of these copies, however, were subject to internal deletions associated with microhomologies, a hallmark of non-homologous end-joining events. Conclusions The non-LTR retrotransposon Hebe from the Bdelloid Rotifer A. vaga was found to undergo frequent microhomology-associated deletions, rather than 5'-terminal truncations characteristic of this class of retrotransposons, and to exhibit preference for telomeric localization. These findings represent the first example of a vertically transmitted putatively deleterious TE in Bdelloids, and may indicate the involvement of microhomology-mediated non-homologous end-joining in desiccation-induced double-strand break repair at the genome periphery.
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a subtelomeric non ltr retrotransposon hebe in the Bdelloid Rotifer adineta vaga is subject to inactivation by deletions but not 5 truncations
Mobile Dna, 2010Co-Authors: Eugene Gladyshev, Irina R ArkhipovaAbstract:Background Rotifers of the class Bdelloidea are microscopic freshwater invertebrates best known for: their capacity for anhydrobiosis; the lack of males and meiosis; and for the ability to capture genes from other non-metazoan species. Although genetic exchange between these animals might take place by non-canonical means, the overall lack of meiosis and syngamy should greatly impair the ability of transposable elements (TEs) to spread in Bdelloid populations. Previous studies demonstrated that Bdelloid chromosome ends, in contrast to gene-rich regions, harbour various kinds of TEs, including specialized telomere-associated retroelements, as well as DNA TEs and retrovirus-like retrotransposons which are prone to horizontal transmission. Vertically-transmitted retrotransposons have not previously been reported in Bdelloids and their identification and studies of the patterns of their distribution and evolution could help in the understanding of the high degree of TE compartmentalization within Bdelloid genomes.
Claudia Ricci - One of the best experts on this subject based on the ideXlab platform.
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surviving starvation changes accompanying starvation tolerance in a Bdelloid Rotifer
Journal of Morphology, 2012Co-Authors: Roberto Marotta, Claudia Ricci, Andrea Uggetti, Francesca Leasi, Giulio MeloneAbstract:Bdelloid Rotifers survive desiccation and starvation by halting activity and entering a kind of dormancy. To understand the mechanisms of survival in the absence of food source, we studied the anatomical and ultrastructural changes occurring in a Bdelloid species, Macrotrachela quadricornifera Milne 1886, after starvation for different periods. The starved Rotifers present a progressive reduction of body size accompanied with a consistent reduction of the volume of the stomach syncytium, where lipid inclusions and digestive vacuoles tend to fade with prolonged starvation. Similar reduction occurs in the vitellarium gland, in which yolk granules progressively decrease in number and size. The changes observed in the syncytia of the stomach and the vitellarium suggest that during starvation M. quadricornifera uses resources diverted from the stomach syncytium first and from the vitellarium syncytium later, resources that are normally allocated to reproduction. The fine structure of starved Bdelloids is compared with that of anhydrobiotic Bdelloids, revealing that survival during either forms of dormancy is sustained by different physiological mechanisms. J. Morphol., 2011. © 2011 Wiley Periodicals, Inc.
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dry and survive morphological changes during anhydrobiosis in a Bdelloid Rotifer
Journal of Structural Biology, 2010Co-Authors: Roberto Marotta, Claudia Ricci, Andrea Uggetti, Francesca Leasi, Giulio MeloneAbstract:Abstract Bdelloid Rotifers are aquatic microinvertebrates able to cope with the loss of environmental water by entering dormancy, and are thus capable of living in temporary habitats. When water is evaporating, Bdelloids contract into “tuns”, silence metabolism and lose water from the body, a condition known as anhydrobiosis. Under controlled conditions, a Bdelloid species ( Macrotrachela quadricornifera ) was made anhydrobiotic, and its morphology was studied by light, confocal and electron microscopy. A compact anatomy characterizes the anhydrobiotic Rotifer, resulting in a considerable reduction of its body volume: the internal organs, precisely packed together, occupy the body cavity almost completely and the lumen of hollow organs disappears. Remarkable ultrastructural changes characterize the anhydrobiotic condition. The mitochondria are wholly surrounded by a ring of electron-dense particles, and the epidermal pores, open in the hydrated specimens, become gradually closed by structures similar to epithelial junctions. The cilia are densely packed: microtubules are still identifiable, but the axonemal organization appears disrupted. This is the first extensive comparative study on the morphological changes associated with the anhydrobiosis process in a Rotifer, providing the basis for an improved understanding of the processes involved in this extreme adaptation.
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first description of the serotonergic nervous system in a Bdelloid Rotifer macrotrachela quadricornifera milne 1886 philodinidae
Zoologischer Anzeiger – A Journal of Comparative Zoology, 2009Co-Authors: Francesca Leasi, Roberta Pennati, Claudia RicciAbstract:Abstract Class Bdelloidea of phylum Rotifera comprises aquatic microinvertebrates that are known for both obligate parthenogenesis and for resisting desiccation through a dormant reversible state. In the frame of an investigation about the role of the nervous system in controlling life cycle, reproduction and dormancy, we describe the serotonergic system of a Bdelloid, Macrotrachela quadricornifera , using serotonin immunohistochemistry and confocal laser scanning microscopy. Serotonin immunoreactivity is present in the cerebral ganglion, lateral nerve cords and peripheral neurites. The cerebral ganglion consists of perikarya that send neurites cephalically to the rostrum and corona. A pair of neurites exits the cerebral ganglion as lateral nerve cords, and proceeds caudally to the pedal ganglion where additional neurites enter the foot. Based on the location of serotonergic immunoreactivity, we hypothesize that the neurotransmitter is involved in both motor activity (e.g., ciliary beating, inchworm-like locomotion) and sensory activity. A comparison between the serotonergic nervous systems of M. quadricornifera and species of Monogononta reveals differences in the numbers and patterns of cerebral perikarya, peripheral perikarya, and periperhal neurites. These differences may have functional significance for understanding adaptations to specific environments and/or systematic significance for reconstructing the Rotiferan ground pattern.
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Epigenetic inheritance systems in Bdelloid Rotifers. I. Maternal‐age‐related biochemical effects
Italian Journal of Zoology, 2009Co-Authors: Claudia Ricci, N. Santo, Elena Radaelli, Anna Maria BolzernAbstract:Abstract The present study focuses on the changes of protein patterns that occur with age and on their maintenance across orthoclonal generations (i.e., lines that belong to the same clone and that differ with the age of their ancestors). About 500 individuals of the Bdelloid Rotifer Macrotrachela quadricornifera were cultivated and processed, and their protein phenotypes compared by a similarity test. The number of protein bands decreased with the age of the individuals. Young Rotifers had the young protein pheno‐type when born from young mothers, and the old protein pattern when born from aged ones. The age of their grandmother was irrelevant. On the basis of these results, Bdelloid Rotifers seemed to transmit to the offspring their biochemical phenotype modified by age and the modified phenotype could persist over the two generations considered. Thus, a truly evolutionarily ancient partheno‐genetic taxon, such as Bdelloidea, apparently produces variable offspring by transmitting phenotypic variations i...
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cryptic diversification in ancient asexuals evidence from the Bdelloid Rotifer philodina flaviceps
Journal of Evolutionary Biology, 2008Co-Authors: Diego Fontaneto, Chiara Boschetti, Claudia RicciAbstract:Bdelloid Rotifers, darwinulid ostracods and some oribatid mites have been called ‘ancient asexuals’ as they speciated and survived over long-term evolutionary timescale without sexual recombination. Data on their genetic diversification are contrasting: within-species diversification is present mostly at a continental scale in a parthenogenetic oribatid mite, whereas almost no genetic diversification at all seems to occur within darwinulid ostracod species. Strangely enough, no clear data for Bdelloid Rotifers are available so far. In this paper, we analyse partial COI mtDNA sequences to show that a Bdelloid Rotifer, Philodina flaviceps, so far considered a single traditional morphological species, has actually been able to diversify into at least nine distinct evolutionary entities, with genetic distances between lineages comparable with those between different traditional species within the same genus. We discovered that local coexistence of such different independent lineages is very common: up to four lineages were found in a same stream, and up to three in a single moss sample of 5 cm2. In contrast to the large-scale geographic pattern that has recently been reported in the oribatid mite, the spatial distribution of the Bdelloid lineages provided evidence of micro-phylogeographic patterns. If the mtDNA diversity indicates that the lineages are independent and represent sympatric cryptic species within P. flaviceps, then the actual Bdelloid diversity can be expected to be much greater than that recognized today.
Alan Tunnacliffe - One of the best experts on this subject based on the ideXlab platform.
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multiple horizontally acquired genes from fungal and prokaryotic donors encode cellulolytic enzymes in the Bdelloid Rotifer adineta ricciae
Gene, 2015Co-Authors: L Szydlowski, Chiara Boschetti, Alastair Crisp, E G G Barbosa, Alan TunnacliffeAbstract:Abstract The Bdelloid Rotifer, Adineta ricciae, an anhydrobiotic microinvertebrate, exhibits a high rate of horizontal gene transfer (HGT), with as much as 10% of its transcriptome being of foreign origin. Approximately 80% of these foreign transcripts are involved in metabolic processes, and therefore Bdelloids represent a useful model for assessing the contribution of HGT to biochemical diversity. To validate this concept, we focused on cellulose digestion, an unusual activity in animals, which is represented by at least 16 genes encoding cellulolytic enzymes in A. ricciae. These genes have been acquired from a variety of different donor organisms among the bacteria and fungi, demonstrating that Bdelloids use diverse genetic resources to construct a novel biochemical pathway. A variable complement of the cellulolytic gene set was found in five other Bdelloid species, indicating a dynamic process of gene acquisition, duplication and loss during Bdelloid evolution. For example, in A. ricciae, gene duplications have led to the formation of three copies of a gene encoding a GH45 family glycoside hydrolase, at least one of which encodes a functional enzyme; all three of these gene copies are present in a close relative, Adineta vaga, but only one copy was found in each of four Rotaria species. Furthermore, analysis of expression levels of the cellulolytic genes suggests that a bacterial-origin cellobiase is upregulated upon desiccation. In summary, Bdelloid Rotifers have apparently developed cellulolytic functions by the acquisition and domestication of multiple foreign genes.
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trafficking of Bdelloid Rotifer late embryogenesis abundant proteins
The Journal of Experimental Biology, 2012Co-Authors: Rashmi Tripathi, Chiara Boschetti, Brian Mcgee, Alan TunnacliffeAbstract:SUMMARY The Bdelloid Rotifer Adineta ricciae is an asexual microinvertebrate that can survive desiccation by entering an ametabolic state known as anhydrobiosis. Two late embryogenesis abundant (LEA) proteins, ArLEA1A and ArLEA1B, have been hypothesized to contribute to desiccation tolerance in these organisms, since in vitro assays suggest that ArLEA1A and ArLEA1B stabilize desiccation-sensitive proteins and membranes, respectively. To examine their functions in vivo , it is important to analyse the cellular distribution of the Bdelloid LEA proteins. Bioinformatics predicted their translocation into the endoplasmic reticulum (ER) via an N-terminal ER translocation signal and persistence in the same compartment via a variant C-terminal retention signal sequence ATEL. We assessed the localization of LEA proteins in Bdelloids and in a mammalian cell model. The function of the N-terminal sequence of ArLEA1A and ArLEA1B in mediating ER translocation was verified, but our data showed that, unlike classical ER-retention signals, ATEL allows progression from the ER to the Golgi and limited secretion of the proteins into the extracellular medium. These results suggest that the N-terminal ER translocation signal and C-terminal ATEL sequence act together to regulate the distribution of Rotifer LEA proteins within intracellular vesicular compartments, as well as the extracellular space. We speculate that this mechanism allows a small number of LEA proteins to offer protection to a large number of desiccation-sensitive molecules and structures both inside and outside cells in the Bdelloid Rotifer.
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foreign genes and novel hydrophilic protein genes participate in the desiccation response of the Bdelloid Rotifer adineta ricciae
The Journal of Experimental Biology, 2011Co-Authors: Chiara Boschetti, Natalia N Pouchkinastantcheva, Pia Hoffmann, Alan TunnacliffeAbstract:Bdelloid Rotifers are aquatic micro-invertebrates with the ability to survive extreme desiccation, or anhydrobiosis, at any life stage. To gain insight into the molecular mechanisms used by Bdelloids during anhydrobiosis, we constructed a cDNA library enriched for genes that are upregulated in Adineta ricciae 24 h after onset of dehydration. Resulting expressed sequence tags (ESTs) were analysed and sequences grouped into categories according to their probable identity. Of 75 unique sequences, approximately half (36) were similar to known genes from other species. These included genes encoding an unusual group 3 late embryogenesis abundant protein, and a number of other stress-related and DNA repair proteins. Open reading frames from a further 39 novel sequences, without counterparts in the database, were screened for the characteristics of intrinsically disordered proteins, i.e. hydrophilicity and lack of stable secondary structure. Such proteins have been implicated in desiccation tolerance and at least five were found. The majority of the genes identified was confirmed by real-time quantitative PCR to be capable of upregulation in response to evaporative water loss. Remarkably, further database and phylogenetic analysis highlighted four ESTs that are present in the A. ricciae genome but which represent genes probably arising from fungi or bacteria by horizontal gene transfer. Therefore, not only can Bdelloid Rotifers accumulate foreign genes and render them transcriptionally competent, but their expression pattern can be modified for participation in the desiccation stress response, and is presumably adaptive in this context. * BLAST : Basic Local Alignment Search Tool EST : expressed sequence tag GRAVY : grand average hydropathy HGT : horizontal gene transfer IDP : intrinsically disordered protein LEA : late embryogenesis abundant ORF : open reading frame PCR : polymerase chain reaction PONDR : predictor of natural disordered regions RH : relative humidity ROS : reactive oxygen species
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Foreign genes and novel hydrophilic protein genes participate in the desiccation response of the Bdelloid Rotifer Adineta ricciae.
The Journal of experimental biology, 2011Co-Authors: Chiara Boschetti, Pia Hoffmann, Natalia Pouchkina-stantcheva, Alan TunnacliffeAbstract:Bdelloid Rotifers are aquatic micro-invertebrates with the ability to survive extreme desiccation, or anhydrobiosis, at any life stage. To gain insight into the molecular mechanisms used by Bdelloids during anhydrobiosis, we constructed a cDNA library enriched for genes that are upregulated in Adineta ricciae 24 h after onset of dehydration. Resulting expressed sequence tags (ESTs) were analysed and sequences grouped into categories according to their probable identity. Of 75 unique sequences, approximately half (36) were similar to known genes from other species. These included genes encoding an unusual group 3 late embryogenesis abundant protein, and a number of other stress-related and DNA repair proteins. Open reading frames from a further 39 novel sequences, without counterparts in the database, were screened for the characteristics of intrinsically disordered proteins, i.e. hydrophilicity and lack of stable secondary structure. Such proteins have been implicated in desiccation tolerance and at least five were found. The majority of the genes identified was confirmed by real-time quantitative PCR to be capable of upregulation in response to evaporative water loss. Remarkably, further database and phylogenetic analysis highlighted four ESTs that are present in the A. ricciae genome but which represent genes probably arising from fungi or bacteria by horizontal gene transfer. Therefore, not only can Bdelloid Rotifers accumulate foreign genes and render them transcriptionally competent, but their expression pattern can be modified for participation in the desiccation stress response, and is presumably adaptive in this context.
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a putative lea protein but no trehalose is present in anhydrobiotic Bdelloid Rotifers
Hydrobiologia, 2005Co-Authors: Alan Tunnacliffe, Jens Lapinski, Brian McgeeAbstract:Some eukaryotes, including Bdelloid Rotifer species, are able to withstand desiccation by entering a state of suspended animation. In this ametabolic condition, known as anhydrobiosis, they can remain viable for extended periods, perhaps decades, but resume normal activities on rehydration. Anhydrobiosis is thought to require accumulation of the non-reducing disaccharides trehalose (in animals and fungi) or sucrose (in plant seeds and resurrection plants), which may protect proteins and membranes by acting as water replacement molecules and vitrifying agents. However, in clone cultures of Bdelloid Rotifers Philodina roseola and Adineta vaga, we were unable to detect trehalose or other disaccharides in either control or dehydrating animals, as determined by gas chromatography. Indeed, trehalose synthase genes (tps) were not detected in these Rotifer genomes, suggesting that Bdelloids might not have the capacity to produce trehalose under any circumstances. This is in sharp contrast to other anhydrobiotic animals such as nematodes and brine shrimp cysts, where trehalose is present during desiccation. Instead, we suggest that adaptations involving proteins might be more important than those involving small biochemicals in Rotifer anhydrobiosis: on dehydration, P. roseola upregulates a hydrophilic protein related to the late embryogenesis abundant (LEA) proteins associated with desiccation tolerance in plants. Since LEA-like proteins have also been implicated in the desiccation tolerance of nematodes and micro-organisms, it seems that hydrophilic protein biosynthesis represents a common element of anhydrobiosis across several biological kingdoms.
Giulio Melone - One of the best experts on this subject based on the ideXlab platform.
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surviving starvation changes accompanying starvation tolerance in a Bdelloid Rotifer
Journal of Morphology, 2012Co-Authors: Roberto Marotta, Claudia Ricci, Andrea Uggetti, Francesca Leasi, Giulio MeloneAbstract:Bdelloid Rotifers survive desiccation and starvation by halting activity and entering a kind of dormancy. To understand the mechanisms of survival in the absence of food source, we studied the anatomical and ultrastructural changes occurring in a Bdelloid species, Macrotrachela quadricornifera Milne 1886, after starvation for different periods. The starved Rotifers present a progressive reduction of body size accompanied with a consistent reduction of the volume of the stomach syncytium, where lipid inclusions and digestive vacuoles tend to fade with prolonged starvation. Similar reduction occurs in the vitellarium gland, in which yolk granules progressively decrease in number and size. The changes observed in the syncytia of the stomach and the vitellarium suggest that during starvation M. quadricornifera uses resources diverted from the stomach syncytium first and from the vitellarium syncytium later, resources that are normally allocated to reproduction. The fine structure of starved Bdelloids is compared with that of anhydrobiotic Bdelloids, revealing that survival during either forms of dormancy is sustained by different physiological mechanisms. J. Morphol., 2011. © 2011 Wiley Periodicals, Inc.
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dry and survive morphological changes during anhydrobiosis in a Bdelloid Rotifer
Journal of Structural Biology, 2010Co-Authors: Roberto Marotta, Claudia Ricci, Andrea Uggetti, Francesca Leasi, Giulio MeloneAbstract:Abstract Bdelloid Rotifers are aquatic microinvertebrates able to cope with the loss of environmental water by entering dormancy, and are thus capable of living in temporary habitats. When water is evaporating, Bdelloids contract into “tuns”, silence metabolism and lose water from the body, a condition known as anhydrobiosis. Under controlled conditions, a Bdelloid species ( Macrotrachela quadricornifera ) was made anhydrobiotic, and its morphology was studied by light, confocal and electron microscopy. A compact anatomy characterizes the anhydrobiotic Rotifer, resulting in a considerable reduction of its body volume: the internal organs, precisely packed together, occupy the body cavity almost completely and the lumen of hollow organs disappears. Remarkable ultrastructural changes characterize the anhydrobiotic condition. The mitochondria are wholly surrounded by a ring of electron-dense particles, and the epidermal pores, open in the hydrated specimens, become gradually closed by structures similar to epithelial junctions. The cilia are densely packed: microtubules are still identifiable, but the axonemal organization appears disrupted. This is the first extensive comparative study on the morphological changes associated with the anhydrobiosis process in a Rotifer, providing the basis for an improved understanding of the processes involved in this extreme adaptation.
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volume and morphology changes of a Bdelloid Rotifer species macrotrachela quadricornifera during anhydrobiosis
Journal of Morphology, 2008Co-Authors: Claudia Ricci, Manuela Caprioli, Diego Fontaneto, Giulio MeloneAbstract:Following a study on the changes occurring in a Bdelloid species (Macrotrachela quadricornifera, Rotifera, Bdelloidea) when entering anhydrobiosis, we investigated the changes in morphology, including weight and volume during the transition from the active hydrated to the dormant anhydrobiotic state by scanning electron microscopy, confocal microscopy and light microscopy. We compared sizes and morphologies of hydrated extended, hydrated contracted and anhydrobiotic specimens. Bdelloid musculature is defined: longitudinal muscles are contracted in the hydrated contracted animal (head and foot are retracted inside the trunk), but appear loose in the anhydrobiotic animal. When anhydrobiotic, M. quadricornifera appears much smaller in size, with a volume reduction of about 60% of the hydrated volume, and its internal organization undergoes remarkable modifications. Internal body cavities, clearly distinguishable in the hydrated extended and contracted specimens, are no longer visible in the anhydrobiotic specimen. Concomitantly, M. quadricornifera loses more than 95% of its weight when anhydrobiotic; this is more than expected from the volume reduction data and could indicate the presence of space-filling molecular species in the dehydrated animal. We estimate that the majority of body mass loss and volume reduction can be ascribed to the water loss from the body cavity during desiccation. J. Morphol., 2008. © 2007 Wiley-Liss, Inc.
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Bdelloid Rotifers Recorded from Australia with Description of Philodinavus aussiensis n.sp.
Zoologischer Anzeiger – A Journal of Comparative Zoology, 2004Co-Authors: Claudia Ricci, Diego Fontaneto, Russell J. Shiel, Giulio MeloneAbstract:Abstract Bdelloid Rotifer research in Australia is reviewed, the current systematic status of the group is summarized. Based on a survey of floodplain and alpine sites in northern Victoria and Tasmania conducted in January-February 1999 we recorded 20 new Bdelloid species for Australia. This brings the continental record to 106 species. The description of Philodinavus aussiensis n.sp. is given, with SEM images of its trophi. Trophi of three more Bdelloid species are here presented.
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morphological response of a Bdelloid Rotifer to desiccation
Journal of Morphology, 2003Co-Authors: Claudia Ricci, N. Santo, Giulio Melone, Manuela CaprioliAbstract:We desiccated Bdelloid Rotifers (Macrotrachela quadricornifera), submitting the animals to four desiccation procedures (protocols A, B, C, D) that differed in the rate of water evaporation, in the time of desiccation, and in the substrates provided. We observed external morphological changes of the Rotifer bodies during drying with scanning electron microscopy and, in parallel, assessed rates of recovery after a 7-day period of dormancy. Two protocols produced disorganized morphologies of the anhydrobiotic animals, with no (A) or very poor (B) recovery. Protocols C and D gave rather high rates of recovery and dry Rotifers appeared unaltered and well organized. The different protocols affected Rotifer morphology during the 7-day anhydrobiosis and rates of recovery after the 7-day anhydrobiosis; high recovery rates corresponded to well-organized morphologies of anhydrobiotic Bdelloids, suggesting that a proper contraction of the body into a tun shape and probably a rigorous packing of internal structures are necessary for survival after anhydrobiosis. These features are affected by the time between water shortage and full desiccation, but also by the surrounding relative humidity and by the nature of the substrate. Possible adaptations of anhydrobiotic Rotifers are discussed. J. Morphol. 257:246–253, 2003. © 2003 Wiley-Liss, Inc.
Chiara Boschetti - One of the best experts on this subject based on the ideXlab platform.
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multiple horizontally acquired genes from fungal and prokaryotic donors encode cellulolytic enzymes in the Bdelloid Rotifer adineta ricciae
Gene, 2015Co-Authors: L Szydlowski, Chiara Boschetti, Alastair Crisp, E G G Barbosa, Alan TunnacliffeAbstract:Abstract The Bdelloid Rotifer, Adineta ricciae, an anhydrobiotic microinvertebrate, exhibits a high rate of horizontal gene transfer (HGT), with as much as 10% of its transcriptome being of foreign origin. Approximately 80% of these foreign transcripts are involved in metabolic processes, and therefore Bdelloids represent a useful model for assessing the contribution of HGT to biochemical diversity. To validate this concept, we focused on cellulose digestion, an unusual activity in animals, which is represented by at least 16 genes encoding cellulolytic enzymes in A. ricciae. These genes have been acquired from a variety of different donor organisms among the bacteria and fungi, demonstrating that Bdelloids use diverse genetic resources to construct a novel biochemical pathway. A variable complement of the cellulolytic gene set was found in five other Bdelloid species, indicating a dynamic process of gene acquisition, duplication and loss during Bdelloid evolution. For example, in A. ricciae, gene duplications have led to the formation of three copies of a gene encoding a GH45 family glycoside hydrolase, at least one of which encodes a functional enzyme; all three of these gene copies are present in a close relative, Adineta vaga, but only one copy was found in each of four Rotaria species. Furthermore, analysis of expression levels of the cellulolytic genes suggests that a bacterial-origin cellobiase is upregulated upon desiccation. In summary, Bdelloid Rotifers have apparently developed cellulolytic functions by the acquisition and domestication of multiple foreign genes.
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trafficking of Bdelloid Rotifer late embryogenesis abundant proteins
The Journal of Experimental Biology, 2012Co-Authors: Rashmi Tripathi, Chiara Boschetti, Brian Mcgee, Alan TunnacliffeAbstract:SUMMARY The Bdelloid Rotifer Adineta ricciae is an asexual microinvertebrate that can survive desiccation by entering an ametabolic state known as anhydrobiosis. Two late embryogenesis abundant (LEA) proteins, ArLEA1A and ArLEA1B, have been hypothesized to contribute to desiccation tolerance in these organisms, since in vitro assays suggest that ArLEA1A and ArLEA1B stabilize desiccation-sensitive proteins and membranes, respectively. To examine their functions in vivo , it is important to analyse the cellular distribution of the Bdelloid LEA proteins. Bioinformatics predicted their translocation into the endoplasmic reticulum (ER) via an N-terminal ER translocation signal and persistence in the same compartment via a variant C-terminal retention signal sequence ATEL. We assessed the localization of LEA proteins in Bdelloids and in a mammalian cell model. The function of the N-terminal sequence of ArLEA1A and ArLEA1B in mediating ER translocation was verified, but our data showed that, unlike classical ER-retention signals, ATEL allows progression from the ER to the Golgi and limited secretion of the proteins into the extracellular medium. These results suggest that the N-terminal ER translocation signal and C-terminal ATEL sequence act together to regulate the distribution of Rotifer LEA proteins within intracellular vesicular compartments, as well as the extracellular space. We speculate that this mechanism allows a small number of LEA proteins to offer protection to a large number of desiccation-sensitive molecules and structures both inside and outside cells in the Bdelloid Rotifer.
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foreign genes and novel hydrophilic protein genes participate in the desiccation response of the Bdelloid Rotifer adineta ricciae
The Journal of Experimental Biology, 2011Co-Authors: Chiara Boschetti, Natalia N Pouchkinastantcheva, Pia Hoffmann, Alan TunnacliffeAbstract:Bdelloid Rotifers are aquatic micro-invertebrates with the ability to survive extreme desiccation, or anhydrobiosis, at any life stage. To gain insight into the molecular mechanisms used by Bdelloids during anhydrobiosis, we constructed a cDNA library enriched for genes that are upregulated in Adineta ricciae 24 h after onset of dehydration. Resulting expressed sequence tags (ESTs) were analysed and sequences grouped into categories according to their probable identity. Of 75 unique sequences, approximately half (36) were similar to known genes from other species. These included genes encoding an unusual group 3 late embryogenesis abundant protein, and a number of other stress-related and DNA repair proteins. Open reading frames from a further 39 novel sequences, without counterparts in the database, were screened for the characteristics of intrinsically disordered proteins, i.e. hydrophilicity and lack of stable secondary structure. Such proteins have been implicated in desiccation tolerance and at least five were found. The majority of the genes identified was confirmed by real-time quantitative PCR to be capable of upregulation in response to evaporative water loss. Remarkably, further database and phylogenetic analysis highlighted four ESTs that are present in the A. ricciae genome but which represent genes probably arising from fungi or bacteria by horizontal gene transfer. Therefore, not only can Bdelloid Rotifers accumulate foreign genes and render them transcriptionally competent, but their expression pattern can be modified for participation in the desiccation stress response, and is presumably adaptive in this context. * BLAST : Basic Local Alignment Search Tool EST : expressed sequence tag GRAVY : grand average hydropathy HGT : horizontal gene transfer IDP : intrinsically disordered protein LEA : late embryogenesis abundant ORF : open reading frame PCR : polymerase chain reaction PONDR : predictor of natural disordered regions RH : relative humidity ROS : reactive oxygen species
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Foreign genes and novel hydrophilic protein genes participate in the desiccation response of the Bdelloid Rotifer Adineta ricciae.
The Journal of experimental biology, 2011Co-Authors: Chiara Boschetti, Pia Hoffmann, Natalia Pouchkina-stantcheva, Alan TunnacliffeAbstract:Bdelloid Rotifers are aquatic micro-invertebrates with the ability to survive extreme desiccation, or anhydrobiosis, at any life stage. To gain insight into the molecular mechanisms used by Bdelloids during anhydrobiosis, we constructed a cDNA library enriched for genes that are upregulated in Adineta ricciae 24 h after onset of dehydration. Resulting expressed sequence tags (ESTs) were analysed and sequences grouped into categories according to their probable identity. Of 75 unique sequences, approximately half (36) were similar to known genes from other species. These included genes encoding an unusual group 3 late embryogenesis abundant protein, and a number of other stress-related and DNA repair proteins. Open reading frames from a further 39 novel sequences, without counterparts in the database, were screened for the characteristics of intrinsically disordered proteins, i.e. hydrophilicity and lack of stable secondary structure. Such proteins have been implicated in desiccation tolerance and at least five were found. The majority of the genes identified was confirmed by real-time quantitative PCR to be capable of upregulation in response to evaporative water loss. Remarkably, further database and phylogenetic analysis highlighted four ESTs that are present in the A. ricciae genome but which represent genes probably arising from fungi or bacteria by horizontal gene transfer. Therefore, not only can Bdelloid Rotifers accumulate foreign genes and render them transcriptionally competent, but their expression pattern can be modified for participation in the desiccation stress response, and is presumably adaptive in this context.
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cryptic diversification in ancient asexuals evidence from the Bdelloid Rotifer philodina flaviceps
Journal of Evolutionary Biology, 2008Co-Authors: Diego Fontaneto, Chiara Boschetti, Claudia RicciAbstract:Bdelloid Rotifers, darwinulid ostracods and some oribatid mites have been called ‘ancient asexuals’ as they speciated and survived over long-term evolutionary timescale without sexual recombination. Data on their genetic diversification are contrasting: within-species diversification is present mostly at a continental scale in a parthenogenetic oribatid mite, whereas almost no genetic diversification at all seems to occur within darwinulid ostracod species. Strangely enough, no clear data for Bdelloid Rotifers are available so far. In this paper, we analyse partial COI mtDNA sequences to show that a Bdelloid Rotifer, Philodina flaviceps, so far considered a single traditional morphological species, has actually been able to diversify into at least nine distinct evolutionary entities, with genetic distances between lineages comparable with those between different traditional species within the same genus. We discovered that local coexistence of such different independent lineages is very common: up to four lineages were found in a same stream, and up to three in a single moss sample of 5 cm2. In contrast to the large-scale geographic pattern that has recently been reported in the oribatid mite, the spatial distribution of the Bdelloid lineages provided evidence of micro-phylogeographic patterns. If the mtDNA diversity indicates that the lineages are independent and represent sympatric cryptic species within P. flaviceps, then the actual Bdelloid diversity can be expected to be much greater than that recognized today.
