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Milana A Kulakova - One of the best experts on this subject based on the ideXlab platform.
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early mesodermal expression of hox genes in the polychaete alitta virens annelida Lophotrochozoa
Development Genes and Evolution, 2017Co-Authors: Milana A Kulakova, N I Bakalenko, Elena L NovikovaAbstract:Hox genes are the key regulators of axial regionalization of bilaterian animals. However, their main function is fulfilled differently in the development of animals from different evolutionary branches. Early patterning of the developing embryos by Hox gene expression in the representatives of protostomes (arthropods, mollusks) starts in the ectodermal cells. On the contrary, the instructive role of the mesoderm in the axial patterning was demonstrated for vertebrates. This makes it difficult to understand if during the axial regionalization of ancestral bilaterians Hox genes first expressed in the developing mesoderm or the ectoderm. To resolve this question, it is necessary to expand the number of models for investigation of the early axial patterning. Here, we show that three Hox genes of the polychaete Alitta virens (formerly Nereis virens, Annelida, Lophotrochozoa)—Hox2, Hox4, and Lox5—are expressed in the mesodermal anlagen of the three future larval chaetigerous segments in spatially colinear manner before the initiation of Hox expression in the larval ectoderm. This is the first evidence of sequential Hox gene expression in the mesoderm of protostomes to date.
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correction expression of hox genes during regeneration of nereid polychaete alitta virens annelida Lophotrochozoa
Evodevo, 2013Co-Authors: Elena L Novikova, N I Bakalenko, Alexander Y Nesterenko, Milana A KulakovaAbstract:After publication it was brought to our attention that there is an ambiguity in the title and in the abstract of our paper [1] that could lead to incorrect understanding of the name of the studied species. To avoid this, the correct title should read “Expression of Hox genes during regeneration of nereid polychaete Alitta virens (Annelida, Lophotrochozoa)” and the sentence “We have recently described the expression of 10 out of 11 Hox genes during postlarval growth of Alitta (Nereis) virens” in the abstract should read as “We have recently described the expression of 10 out of 11 Hox genes during postlarval growth of Alitta virens (formerly Nereis virens).”
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expression of hox genes during regeneration of nereid polychaete alitta nereis virens annelida Lophotrochozoa
Evodevo, 2013Co-Authors: Elena L Novikova, N I Bakalenko, Alexander Y Nesterenko, Milana A KulakovaAbstract:Background Hox genes are the key determinants of different morphogenetic events in all bilaterian animals. These genes are probably responsible for the maintenance of regenerative capacities by providing positional information in the regenerating animal body. Polychaetes are well known for their ability to regenerate the posterior as well as the anterior part of the body. We have recently described the expression of 10 out of 11 Hox genes during postlarval growth of Alitta (Nereis) virens. Hox genes form gradient overlapping expression patterns, which probably do not contribute to the morphological diversity of segments along the anterior-posterior axis of the homonomously segmented worm. We suggest that this gradient expression of Hox genes establishes positional information along the body that can be used to maintain coordinated growth and regeneration.
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parahox gene expression in larval and postlarval development of the polychaete nereis virens annelida Lophotrochozoa
BMC Developmental Biology, 2008Co-Authors: Milana A Kulakova, Charles E Cook, Tatiana F AndreevaAbstract:Background Transcription factors that encode ANTP-class homeobox genes play crucial roles in determining the body plan organization and specification of different organs and tissues in bilaterian animals. The three-gene ParaHox family descends from an ancestral gene cluster that existed before the evolution of the Bilateria. All three ParaHox genes are reported from deuterostomes and Lophotrochozoans, but not to date from any ecdysozoan taxa, and there is evidence that the ParaHox genes, like the related Hox genes, were ancestrally a single chromosomal cluster. However, unlike the Hox genes, there is as yet no strong evidence that the ParaHox genes are expressed in spatial and temporal order during embryogenesis.
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hox gene expression in larval development of the polychaetes nereis virens and platynereis dumerilii annelida Lophotrochozoa
Development Genes and Evolution, 2007Co-Authors: Milana A Kulakova, Detlev Arendt, N I Bakalenko, Elena L Novikova, Charles E Cook, Elena Eliseeva, Patrick R H Steinmetz, R P Kostyuchenko, A K Dondua, Michael AkamAbstract:The bilaterian animals are divided into three great branches: the Deuterostomia, Ecdysozoa, and Lophotrochozoa. The evolution of developmental mechanisms is less studied in the Lophotrochozoa than in the other two clades. We have studied the expression of Hox genes during larval development of two Lophotrochozoans, the polychaete annelids Nereis virens and Platynereis dumerilii. As reported previously, the Hox cluster of N. virens consists of at least 11 genes (de Rosa R, Grenier JK, Andreeva T, Cook CE, Adoutte A, Akam M, Carroll SB, Balavoine G, Nature, 399:772–776, 1999; Andreeva TF, Cook C, Korchagina NM, Akam M, Dondua AK, Ontogenez 32:225–233, 2001); we have also cloned nine Hox genes of P. dumerilii. Hox genes are mainly expressed in the descendants of the 2d blastomere, which form the integument of segments, ventral neural ganglia, pre-pygidial growth zone, and the pygidial lobe. Patterns of expression are similar for orthologous genes of both nereids. In Nereis, Hox2, and Hox3 are activated before the blastopore closure, while Hox1 and Hox4 are activated just after this. Hox5 and Post2 are first active during the metatrochophore stage, and Hox7, Lox4, and Lox2 at the late nectochaete stage only. During larval stages, Hox genes are expressed in staggered domains in the developing segments and pygidial lobe. The pattern of expression of Hox cluster genes suggests their involvement in the vectorial regionalization of the larval body along the antero-posterior axis. Hox gene expression in nereids conforms to the canonical patterns postulated for the two other evolutionary branches of the Bilateria, the Ecdysozoa and the Deuterostomia, thus supporting the evolutionary conservatism of the function of Hox genes in development.
Elena L Novikova - One of the best experts on this subject based on the ideXlab platform.
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early mesodermal expression of hox genes in the polychaete alitta virens annelida Lophotrochozoa
Development Genes and Evolution, 2017Co-Authors: Milana A Kulakova, N I Bakalenko, Elena L NovikovaAbstract:Hox genes are the key regulators of axial regionalization of bilaterian animals. However, their main function is fulfilled differently in the development of animals from different evolutionary branches. Early patterning of the developing embryos by Hox gene expression in the representatives of protostomes (arthropods, mollusks) starts in the ectodermal cells. On the contrary, the instructive role of the mesoderm in the axial patterning was demonstrated for vertebrates. This makes it difficult to understand if during the axial regionalization of ancestral bilaterians Hox genes first expressed in the developing mesoderm or the ectoderm. To resolve this question, it is necessary to expand the number of models for investigation of the early axial patterning. Here, we show that three Hox genes of the polychaete Alitta virens (formerly Nereis virens, Annelida, Lophotrochozoa)—Hox2, Hox4, and Lox5—are expressed in the mesodermal anlagen of the three future larval chaetigerous segments in spatially colinear manner before the initiation of Hox expression in the larval ectoderm. This is the first evidence of sequential Hox gene expression in the mesoderm of protostomes to date.
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correction expression of hox genes during regeneration of nereid polychaete alitta virens annelida Lophotrochozoa
Evodevo, 2013Co-Authors: Elena L Novikova, N I Bakalenko, Alexander Y Nesterenko, Milana A KulakovaAbstract:After publication it was brought to our attention that there is an ambiguity in the title and in the abstract of our paper [1] that could lead to incorrect understanding of the name of the studied species. To avoid this, the correct title should read “Expression of Hox genes during regeneration of nereid polychaete Alitta virens (Annelida, Lophotrochozoa)” and the sentence “We have recently described the expression of 10 out of 11 Hox genes during postlarval growth of Alitta (Nereis) virens” in the abstract should read as “We have recently described the expression of 10 out of 11 Hox genes during postlarval growth of Alitta virens (formerly Nereis virens).”
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expression of hox genes during regeneration of nereid polychaete alitta nereis virens annelida Lophotrochozoa
Evodevo, 2013Co-Authors: Elena L Novikova, N I Bakalenko, Alexander Y Nesterenko, Milana A KulakovaAbstract:Background Hox genes are the key determinants of different morphogenetic events in all bilaterian animals. These genes are probably responsible for the maintenance of regenerative capacities by providing positional information in the regenerating animal body. Polychaetes are well known for their ability to regenerate the posterior as well as the anterior part of the body. We have recently described the expression of 10 out of 11 Hox genes during postlarval growth of Alitta (Nereis) virens. Hox genes form gradient overlapping expression patterns, which probably do not contribute to the morphological diversity of segments along the anterior-posterior axis of the homonomously segmented worm. We suggest that this gradient expression of Hox genes establishes positional information along the body that can be used to maintain coordinated growth and regeneration.
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hox gene expression in larval development of the polychaetes nereis virens and platynereis dumerilii annelida Lophotrochozoa
Development Genes and Evolution, 2007Co-Authors: Milana A Kulakova, Detlev Arendt, N I Bakalenko, Elena L Novikova, Charles E Cook, Elena Eliseeva, Patrick R H Steinmetz, R P Kostyuchenko, A K Dondua, Michael AkamAbstract:The bilaterian animals are divided into three great branches: the Deuterostomia, Ecdysozoa, and Lophotrochozoa. The evolution of developmental mechanisms is less studied in the Lophotrochozoa than in the other two clades. We have studied the expression of Hox genes during larval development of two Lophotrochozoans, the polychaete annelids Nereis virens and Platynereis dumerilii. As reported previously, the Hox cluster of N. virens consists of at least 11 genes (de Rosa R, Grenier JK, Andreeva T, Cook CE, Adoutte A, Akam M, Carroll SB, Balavoine G, Nature, 399:772–776, 1999; Andreeva TF, Cook C, Korchagina NM, Akam M, Dondua AK, Ontogenez 32:225–233, 2001); we have also cloned nine Hox genes of P. dumerilii. Hox genes are mainly expressed in the descendants of the 2d blastomere, which form the integument of segments, ventral neural ganglia, pre-pygidial growth zone, and the pygidial lobe. Patterns of expression are similar for orthologous genes of both nereids. In Nereis, Hox2, and Hox3 are activated before the blastopore closure, while Hox1 and Hox4 are activated just after this. Hox5 and Post2 are first active during the metatrochophore stage, and Hox7, Lox4, and Lox2 at the late nectochaete stage only. During larval stages, Hox genes are expressed in staggered domains in the developing segments and pygidial lobe. The pattern of expression of Hox cluster genes suggests their involvement in the vectorial regionalization of the larval body along the antero-posterior axis. Hox gene expression in nereids conforms to the canonical patterns postulated for the two other evolutionary branches of the Bilateria, the Ecdysozoa and the Deuterostomia, thus supporting the evolutionary conservatism of the function of Hox genes in development.
David A Weisblat - One of the best experts on this subject based on the ideXlab platform.
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Spatiotemporal expression of a twist homolog in the leech Helobdella austinensis
Development Genes and Evolution, 2017Co-Authors: Brenda Irene Medina Jiménez, Hee-jin Kwak, Soon Cheol Park, Ping Xiao, David A WeisblatAbstract:Genes of the twist family encode bHLH transcription factors known to be involved in the regulation and differentiation of early mesoderm. Here, we report our characterization of Hau-twist , a twist homolog from the leech Helobdella austinensis , a tractable Lophotrochozoan representative. Hau-twist was expressed in segmental founder cells of the mesodermal lineage, in subsets of cells within the mesodermal lineage of the germinal plate, in circumferential muscle fibers of a provisional integument during segmentation and organogenesis stages and on the ventral side of the developing proboscis. Thus, consistent with other systems, our results suggest that twist gene of the leech Helobdella might function in mesoderm differentiation.
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Leeches of the genus Helobdella as model organisms for Evo-Devo studies
Theory in Biosciences, 2015Co-Authors: Ulrich Kutschera, David A WeisblatAbstract:Model organisms are important tools in modern biology and have been used elucidate mechanism underlying processes, such as development, heredity, neuronal signaling, and phototropism, to name but a few. In this context, the use of model organisms is predicated on uncovering evolutionarily conserved features of biological processes in the expectation that the findings will be applicable to organisms that are either inaccessible or intractable for direct experimentation. For the most part, particular species have been adapted as model organisms because they can be easily reared and manipulated in the laboratory. In contrast, a major goal in the field of evolutionary developmental biology (Evo-Devo) is to identify and elucidate the differences in developmental processes among species associated with the dramatic range of body plans among organisms, and how these differences have emerged over time in various branches of phylogeny. At first glance then, it would appear that the concept of model organisms for Evo-Devo is oxymoronic. In fact, however, laboratory-compatible, experimentally tractable species are of great use for Evo-Devo, subject to the condition that the ensemble of models investigated should reflect the range of taxonomic diversity, and for this purpose glossiphoniid leeches are useful. Four decades ago (1975), leeches of the species-rich genus Helobdella (Lophotrochozoa; Annelida; Clitellata; Hirudinida; Glossiphoniidae) were collected in Stow Lake, Golden Gate Park, San Francisco, CA (USA). These and other Helobdella species may be taken as Evo-Devo models of leeches, clitellate annelids, and the super-phylum Lophotrochozoa. Here we depict/discuss the biology/taxonomy of these Evo-Devo systems, and the challenges of identifying species within Helobdella . In addition, we document that H. austinensis has been established as a new model organism that can easily be cultivated in the laboratory. Finally, we provide an updated scheme illustrating the unique germ line/soma-differentiation during early development and speculate on the mechanisms of sympatric speciation in this group of aquatic annelids.
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lineage analysis of micromere 4d a super phylotypic cell for Lophotrochozoa in the leech helobdella and the sludgeworm tubifex
Developmental Biology, 2011Co-Authors: Stephanie E Gline, Ayaki Nakamoto, David A WeisblatAbstract:The super-phylum Lophotrochozoa contains the plurality of extant animal phyla and exhibits a corresponding diversity of adult body plans. Moreover, in contrast to Ecdysozoa and Deuterostomia, most Lophotrochozoans exhibit a conserved pattern of stereotyped early divisions called spiral cleavage. In particular, bilateral mesoderm in most Lophotrochozoan species arises from the progeny of micromere 4d, which is assumed to be homologous with a similar cell in the embryo of the ancestral Lophotrochozoan, more than 650 million years ago. Thus, distinguishing the conserved and diversified features of cell fates in the 4d lineage among modern spiralians is required to understand how Lophotrochozoan diversity has evolved by changes in developmental processes. Here we analyze cell fates for the early progeny of the bilateral daughters (M teloblasts) of micromere 4d in the leech Helobdella sp. Austin, a clitellate annelid. We show that the first six progeny of the M teloblasts (em1-em6) contribute five different sets of progeny to non-segmental mesoderm, mainly in the head and in the lining of the digestive tract. The latter feature, associated with cells em1 and em2 in Helobdella, is seen with the M teloblast lineage in a second clitellate species, the sludgeworm Tubifex tubifex and, on the basis of previously published work, in the initial progeny of the M teloblast homologs in molluscan species, suggesting that it may be an ancestral feature of Lophotrochozoan development.
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and Lophotrochozoa makes three notch hes signaling in annelid segmentation
Development Genes and Evolution, 2009Co-Authors: Ajna S Rivera, David A WeisblatAbstract:Segmentation is unquestionably a major factor in the evolution of complex body plans, but how this trait itself evolved is unknown. Approaching this problem requires comparing the molecular mechanisms of segmentation in diverse segmented and unsegmented taxa. Notch/Hes signaling is involved in segmentation in sequentially segmenting vertebrates and arthropods, as judged by patterns of expression of one or more genes in this network and by the disruption of segmental patterning when Notch/Hes signaling is disrupted. We have previously shown that Notch and Hes homologs are expressed in the posterior progress zone (PPZ), from which segments arise, in the leech Helobdella robusta, a sequentially segmenting Lophotrochozoan (phylum Annelida). Here, we show that disrupting Notch/Hes signaling disrupts segmentation in this species as well. Thus, Notch/Hes functions in either the maintenance of the PPZ and/or the patterning processes of segmentation in representatives of all three superphyla of bilaterally symmetric animals. These results are consistent with two evolutionary scenarios. In one, segmentation was already present in the ancestor of all three superphyla. In the other, Notch/Hes signaling functioned in axial growth by terminal addition in an unsegmented bilaterian ancestor, and was subsequently exapted to function in segmentation as that process evolved independently in two or more taxa.
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And Lophotrochozoa makes three: Notch/Hes signaling in annelid segmentation.
Development Genes and Evolution, 2008Co-Authors: Ajna S Rivera, David A WeisblatAbstract:Segmentation is unquestionably a major factor in the evolution of complex body plans, but how this trait itself evolved is unknown. Approaching this problem requires comparing the molecular mechanisms of segmentation in diverse segmented and unsegmented taxa. Notch/Hes signaling is involved in segmentation in sequentially segmenting vertebrates and arthropods, as judged by patterns of expression of one or more genes in this network and by the disruption of segmental patterning when Notch/Hes signaling is disrupted. We have previously shown that Notch and Hes homologs are expressed in the posterior progress zone (PPZ), from which segments arise, in the leech Helobdella robusta, a sequentially segmenting Lophotrochozoan (phylum Annelida). Here, we show that disrupting Notch/Hes signaling disrupts segmentation in this species as well. Thus, Notch/Hes functions in either the maintenance of the PPZ and/or the patterning processes of segmentation in representatives of all three superphyla of bilaterally symmetric animals. These results are consistent with two evolutionary scenarios. In one, segmentation was already present in the ancestor of all three superphyla. In the other, Notch/Hes signaling functioned in axial growth by terminal addition in an unsegmented bilaterian ancestor, and was subsequently exapted to function in segmentation as that process evolved independently in two or more taxa.
Kevin M. Kocot - One of the best experts on this subject based on the ideXlab platform.
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phylogenomics of Lophotrochozoa with consideration of systematic error
Systematic Biology, 2016Co-Authors: Kevin M. Kocot, Torsten H Struck, Julia Merkel, Damien S Waits, Christiane Todt, Pamela M Brannock, David Weese, Johanna T CannonAbstract:Phylogenomic studies have improved understanding of deep metazoan phylogeny and show promise for resolving incongruences among analyses based on limited numbers of loci. One region of the animal tree that has been especially difficult to resolve, even with phylogenomic approaches, is relationships within Lophotrochozoa (the animal clade that includes molluscs, annelids, and flatworms among others). Lack of resolution in phylogenomic analyses could be due to insufficient phylogenetic signal, limitations in taxon and/or gene sampling, or systematic error. Here, we investigated why Lophotrochozoan phylogeny has been such a difficult question to answer by identifying and reducing sources of systematic error. We supplemented existing data with 32 new transcriptomes spanning the diversity of Lophotrochozoa and constructed a new set of Lophotrochozoa-specific core orthologs. Of these, 638 orthologous groups (OGs) passed strict screening for paralogy using a tree-based approach. In order to reduce possible sources of systematic error, we calculated branch-length heterogeneity, evolutionary rate, percent missing data, compositional bias, and saturation for each OG and analyzed increasingly stricter subsets of only the most stringent (best) OGs for these five variables. Principal component analysis of the values for each factor examined for each OG revealed that compositional heterogeneity and average patristic distance contributed most to the variance observed along the first principal component while branch-length heterogeneity and, to a lesser extent, saturation contributed most to the variance observed along the second. Missing data did not strongly contribute to either. Additional sensitivity analyses examined effects of removing taxa with heterogeneous branch lengths, large amounts of missing data, and compositional heterogeneity. Although our analyses do not unambiguously resolve Lophotrochozoan phylogeny, we advance the field by reducing the list of viable hypotheses. Moreover, our systematic approach for dissection of phylogenomic data can be applied to explore sources of incongruence and poor support in any phylogenomic data set. [Annelida; Brachiopoda; Bryozoa; Entoprocta; Mollusca; Nemertea; Phoronida; Platyzoa; Polyzoa; Spiralia; Trochozoa.].
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On 20 years of Lophotrochozoa
Organisms Diversity & Evolution, 2016Co-Authors: Kevin M. KocotAbstract:Lophotrochozoa is a protostome clade that includes disparate animals such as molluscs, annelids, bryozoans, and flatworms, giving it the distinction of including the most body plans of any of the three major clades of Bilateria. This extreme morphological disparity has prompted numerous conflicting phylogenetic hypotheses about relationships among Lophotrochozoan phyla. Here, I review the current understanding of Lophotrochozoan phylogeny with emphasis on recent insights gained through approaches taking advantage of high-throughput DNA sequencing (phylogenomics). Of significance, Platyzoa, a hypothesized clade of mostly small-bodied animals, appears to be an artifact of long-branch attraction. Recent studies recovered Gnathifera (Syndermata, Gnathostomulida, and Micrognathozoa) sister to all other Lophotrochozoans and a clade called Rouphozoa (Platyhelminthes and Gastrotricha) sister to the remaining non-gnathiferan Lophotrochozoans. Although Bryozoa was traditionally grouped with Brachiopoda and Phoronida (Lophophorata), most molecular studies have supported a clade including Entoprocta, Cycliophora, and Bryozoa (Polyzoa). However, recent phylogenomic work has shown that entoprocts and bryozoans have compositionally heterogeneous genomes that may cause systematic artifacts affecting their phylogenetic placement. Lastly, relationships within Trochozoa (Mollusca, Annelida, and relatives) largely remain ambiguous. Recent work has shown that phylogenomic studies must identify and reduce sources of systematic error, such as amino acid compositional heterogeneity and long-branch attraction. Still, other approaches such as the analysis of rare genomic changes may be needed to overcome challenges to standard phylogenomic approaches. Resolving Lophotrochozoan phylogeny will provide important insight into how these complex and diverse body plans evolved and provide a much-needed framework for comparative studies.
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On 20 years of Lophotrochozoa
Organisms Diversity & Evolution, 2016Co-Authors: Kevin M. KocotAbstract:Lophotrochozoa is a protostome clade that includes disparate animals such as molluscs, annelids, bryozoans, and flatworms, giving it the distinction of including the most body plans of any of the three major clades of Bilateria. This extreme morphological disparity has prompted numerous conflicting phylogenetic hypotheses about relationships among Lophotrochozoan phyla. Here, I review the current understanding of Lophotrochozoan phylogeny with emphasis on recent insights gained through approaches taking advantage of high-throughput DNA sequencing (phylogenomics). Of significance, Platyzoa, a hypothesized clade of mostly small-bodied animals, appears to be an artifact of long-branch attraction. Recent studies recovered Gnathifera (Syndermata, Gnathostomulida, and Micrognathozoa) sister to all other Lophotrochozoans and a clade called Rouphozoa (Platyhelminthes and Gastrotricha) sister to the remaining non-gnathiferan Lophotrochozoans. Although Bryozoa was traditionally grouped with Brachiopoda and Phoronida (Lophophorata), most molecular studies have supported a clade including Entoprocta, Cycliophora, and Bryozoa (Polyzoa). However, recent phylogenomic work has shown that entoprocts and bryozoans have compositionally heterogeneous genomes that may cause systematic artifacts affecting their phylogenetic placement. Lastly, relationships within Trochozoa (Mollusca, Annelida, and relatives) largely remain ambiguous. Recent work has shown that phylogenomic studies must identify and reduce sources of systematic error, such as amino acid compositional heterogeneity and long-branch attraction. Still, other approaches such as the analysis of rare genomic changes may be needed to overcome challenges to standard phylogenomic approaches. Resolving Lophotrochozoan phylogeny will provide important insight into how these complex and diverse body plans evolved and provide a much-needed framework for comparative studies.
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repurposed transcriptomic data facilitate discovery of innate immunity toll like receptor tlr genes across Lophotrochozoa
The Biological Bulletin, 2014Co-Authors: Kenneth M. Halanych, Kevin M. KocotAbstract:The growing volume of genomic data from across life represents opportunities for deriving valuable biological information from data that were initially collected for another purpose. Here, we use transcriptomes collected for phylogenomic studies to search for toll-like receptor (TLR) genes in poorly sampled Lophotrochozoan clades (Annelida, Mollusca, Brachiopoda, Phoronida, and Entoprocta) and one ecdysozoan clade (Priapulida). TLR genes are involved in innate immunity across animals by recognizing potential microbial infection. They have an extracellular leucine-rich repeat (LRR) domain connected to a transmembrane domain and an intracellular toll/interleukin-1 receptor (TIR) domain. Consequently, these genes are important in initiating a signaling pathway to trigger defense. We found at least one TLR ortholog in all but two taxa examined, suggesting that a broad array of Lophotrochozoans may have innate immune systems similar to those observed in vertebrates and arthropods. Comparison to the SMART database confirmed the presence of both the LRR and the TIR protein motifs characteristic of TLR genes. Because we looked at only one transcriptome per species, discovery of TLR genes was limited for most taxa. However, several TRL-like genes that vary in the number and placement of LRR domains were found in phoronids. Additionally, several contigs contained LRR domains but lacked TIR domains, suggesting they were not TLRs. Many of these LRR-containing contigs had other domains (e.g., immunoglobin) and are likely involved in innate immunity.
N I Bakalenko - One of the best experts on this subject based on the ideXlab platform.
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early mesodermal expression of hox genes in the polychaete alitta virens annelida Lophotrochozoa
Development Genes and Evolution, 2017Co-Authors: Milana A Kulakova, N I Bakalenko, Elena L NovikovaAbstract:Hox genes are the key regulators of axial regionalization of bilaterian animals. However, their main function is fulfilled differently in the development of animals from different evolutionary branches. Early patterning of the developing embryos by Hox gene expression in the representatives of protostomes (arthropods, mollusks) starts in the ectodermal cells. On the contrary, the instructive role of the mesoderm in the axial patterning was demonstrated for vertebrates. This makes it difficult to understand if during the axial regionalization of ancestral bilaterians Hox genes first expressed in the developing mesoderm or the ectoderm. To resolve this question, it is necessary to expand the number of models for investigation of the early axial patterning. Here, we show that three Hox genes of the polychaete Alitta virens (formerly Nereis virens, Annelida, Lophotrochozoa)—Hox2, Hox4, and Lox5—are expressed in the mesodermal anlagen of the three future larval chaetigerous segments in spatially colinear manner before the initiation of Hox expression in the larval ectoderm. This is the first evidence of sequential Hox gene expression in the mesoderm of protostomes to date.
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correction expression of hox genes during regeneration of nereid polychaete alitta virens annelida Lophotrochozoa
Evodevo, 2013Co-Authors: Elena L Novikova, N I Bakalenko, Alexander Y Nesterenko, Milana A KulakovaAbstract:After publication it was brought to our attention that there is an ambiguity in the title and in the abstract of our paper [1] that could lead to incorrect understanding of the name of the studied species. To avoid this, the correct title should read “Expression of Hox genes during regeneration of nereid polychaete Alitta virens (Annelida, Lophotrochozoa)” and the sentence “We have recently described the expression of 10 out of 11 Hox genes during postlarval growth of Alitta (Nereis) virens” in the abstract should read as “We have recently described the expression of 10 out of 11 Hox genes during postlarval growth of Alitta virens (formerly Nereis virens).”
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expression of hox genes during regeneration of nereid polychaete alitta nereis virens annelida Lophotrochozoa
Evodevo, 2013Co-Authors: Elena L Novikova, N I Bakalenko, Alexander Y Nesterenko, Milana A KulakovaAbstract:Background Hox genes are the key determinants of different morphogenetic events in all bilaterian animals. These genes are probably responsible for the maintenance of regenerative capacities by providing positional information in the regenerating animal body. Polychaetes are well known for their ability to regenerate the posterior as well as the anterior part of the body. We have recently described the expression of 10 out of 11 Hox genes during postlarval growth of Alitta (Nereis) virens. Hox genes form gradient overlapping expression patterns, which probably do not contribute to the morphological diversity of segments along the anterior-posterior axis of the homonomously segmented worm. We suggest that this gradient expression of Hox genes establishes positional information along the body that can be used to maintain coordinated growth and regeneration.
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hox gene expression in larval development of the polychaetes nereis virens and platynereis dumerilii annelida Lophotrochozoa
Development Genes and Evolution, 2007Co-Authors: Milana A Kulakova, Detlev Arendt, N I Bakalenko, Elena L Novikova, Charles E Cook, Elena Eliseeva, Patrick R H Steinmetz, R P Kostyuchenko, A K Dondua, Michael AkamAbstract:The bilaterian animals are divided into three great branches: the Deuterostomia, Ecdysozoa, and Lophotrochozoa. The evolution of developmental mechanisms is less studied in the Lophotrochozoa than in the other two clades. We have studied the expression of Hox genes during larval development of two Lophotrochozoans, the polychaete annelids Nereis virens and Platynereis dumerilii. As reported previously, the Hox cluster of N. virens consists of at least 11 genes (de Rosa R, Grenier JK, Andreeva T, Cook CE, Adoutte A, Akam M, Carroll SB, Balavoine G, Nature, 399:772–776, 1999; Andreeva TF, Cook C, Korchagina NM, Akam M, Dondua AK, Ontogenez 32:225–233, 2001); we have also cloned nine Hox genes of P. dumerilii. Hox genes are mainly expressed in the descendants of the 2d blastomere, which form the integument of segments, ventral neural ganglia, pre-pygidial growth zone, and the pygidial lobe. Patterns of expression are similar for orthologous genes of both nereids. In Nereis, Hox2, and Hox3 are activated before the blastopore closure, while Hox1 and Hox4 are activated just after this. Hox5 and Post2 are first active during the metatrochophore stage, and Hox7, Lox4, and Lox2 at the late nectochaete stage only. During larval stages, Hox genes are expressed in staggered domains in the developing segments and pygidial lobe. The pattern of expression of Hox cluster genes suggests their involvement in the vectorial regionalization of the larval body along the antero-posterior axis. Hox gene expression in nereids conforms to the canonical patterns postulated for the two other evolutionary branches of the Bilateria, the Ecdysozoa and the Deuterostomia, thus supporting the evolutionary conservatism of the function of Hox genes in development.
