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Frederick W Miller - One of the best experts on this subject based on the ideXlab platform.
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machine learning algorithms reveal unique gene expression profiles in muscle biopsies from patients with different types of myositis
Annals of the Rheumatic Diseases, 2020Co-Authors: Iago Pinalfernandez, Assia Derfoul, José César Milisenda, Frederick W Miller, Maria Casaldominguez, Katherine Pak, Josep Maria Graujunyent, Albert Selvaocallaghan, Carme Carrionribas, Julie J. PaikAbstract:Objectives Myositis is a heterogeneous family of diseases that includes dermatomyositis (DM), antisynthetase syndrome (AS), immune-mediated necrotising myopathy (IMNM), inclusion body myositis (IBM), polymyositis and overlap myositis. Additional subtypes of myositis can be defined by the presence of myositis-specific autoantibodies (MSAs). The purpose of this study was to define unique gene expression profiles in muscle biopsies from patients with MSA-positive DM, AS and IMNM as well as IBM. Methods RNA-seq was performed on muscle biopsies from 119 myositis patients with IBM or defined MSAs and 20 controls. Machine learning algorithms were trained on transcriptomic data and recursive feature elimination was used to determine which genes were most useful for classifying muscle biopsies into each type and MSA-defined subtype of myositis. Results The support vector machine learning algorithm classified the muscle biopsies with >90% accuracy. Recursive feature elimination identified genes that are most useful to the machine learning algorithm and that are only overexpressed in one type of myositis. For example, CAMK1G (calcium/calmodulin-dependent protein kinase IG), EGR4 (early growth response protein 4) and CXCL8 (interleukin 8) are highly expressed in AS but not in DM or other types of myositis. Using the same computational approach, we also identified genes that are uniquely overexpressed in different MSA-defined subtypes. These included apolipoprotein A4 (APOA4), which is only expressed in anti-3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) myopathy, and MADCAM1 (mucosal vascular addressin cell adhesion molecule 1), which is only expressed in anti-Mi2-positive DM. Conclusions Unique gene expression profiles in muscle biopsies from patients with MSA-defined subtypes of myositis and IBM suggest that different pathological mechanisms underly muscle damage in each of these diseases.
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identification of distinctive interferon gene signatures in different types of myositis
Neurology, 2019Co-Authors: Assia Derfoul, Paul H. Plotz, Iago Pinalfernandez, Frederick W Miller, Maria Casaldominguez, Katherine Pak, José César MilisendaAbstract:Objective Activation of the type 1 interferon (IFN1) pathway is a prominent feature of dermatomyositis (DM) muscle and may play a role in the pathogenesis of this disease. However, the relevance of the IFN1 pathway in patients with other types of myositis such as the antisynthetase syndrome (AS), immune-mediated necrotizing myopathy (IMNM), and inclusion body myositis (IBM) is largely unknown. Moreover, the activation of the type 2 interferon (IFN2) pathway has not been comprehensively explored in myositis. In this cross-sectional study, our objective was to determine whether IFN1 and IFN2 pathways are differentially activated in different types of myositis by performing RNA sequencing on muscle biopsy samples from 119 patients with DM, IMNM, AS, or IBM and on 20 normal muscle biopsies. Methods The expression of IFN1- and IFN2-inducible genes was compared between the different groups. Results The expression of IFN1-inducible genes was high in DM, moderate in AS, and low in IMNM and IBM. In contrast, the expression of IFN2-inducible genes was high in DM, IBM, and AS but low in IMNM. The expression of IFN-inducible genes correlated with the expression of genes associated with inflammation and muscle regeneration. Of note, ISG15 expression levels alone performed as well as composite scores relying on multiple genes to monitor activation of the IFN1 pathway in myositis muscle biopsies. Conclusions IFN1 and IFN2 pathways are differentially activated in different forms of myositis. This observation may have therapeutic implications because immunosuppressive medications may preferentially target each of these pathways.
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anti ro52 autoantibodies are associated with interstitial lung disease and more severe disease in patients with juvenile myositis
Annals of the Rheumatic Diseases, 2019Co-Authors: Sara Sabbagh, Iago Pinalfernandez, Takayuki Kishi, Ira N Targoff, Frederick W Miller, Lisa G Rider, Andrew L. MammenAbstract:Objectives Anti-Ro52 autoantibodies are associated with more severe interstitial lung disease (ILD) in adult myositis patients with antiaminoacyl transfer (t)RNA synthetase autoantibodies. However, few studies have examined anti-Ro52 autoantibodies in juvenile myositis. The purpose of this study was to define the prevalence and clinical features associated with anti-Ro52 autoantibodies in a large cohort of patients with juvenile myositis. Methods We screened sera from 302 patients with juvenile dermatomyositis (JDM), 25 patients with juvenile polymyositis (JPM) and 44 patients with juvenile connective tissue disease–myositis overlap (JCTM) for anti-Ro52 autoantibodies by ELISA. Clinical characteristics were compared between myositis patients with and without anti-Ro52 autoantibodies. Results Anti-Ro52 autoantibodies were found in 14% patients with JDM, 12% with JPM and 18% with JCTM. Anti-Ro52 autoantibodies were more frequent in patients with antiaminoacyl tRNA synthetase (64%, p Conclusions Anti-Ro52 autoantibodies are present in 14% of patients with juvenile myositis and are strongly associated with anti-MDA5 and antiaminoacyl tRNA synthetase autoantibodies. In all patients with juvenile myositis, those with anti-Ro52 autoantibodies were more likely to have ILD. Furthermore, patients with anti-Ro52 autoantibodies have more severe disease and a poorer prognosis.
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genome wide association study identifies hla 8 1 ancestral haplotype alleles as major genetic risk factors for myositis phenotypes
Genes and Immunity, 2015Co-Authors: Frederick W Miller, Lisa G Rider, Katalin Dankó, R G Cooper, Ingrid E Lundberg, Wei Vivien Chen, Terrance P Ohanlon, J Vencovsky, Lucy R Wedderburn, Lauren M PachmanAbstract:Autoimmune muscle diseases (myositis) comprise a group of complex phenotypes influenced by genetic and environmental factors. To identify genetic risk factors in patients of European ancestry, we conducted a genome-wide association study (GWAS) of the major myositis phenotypes in a total of 1710 cases, which included 705 adult dermatomyositis, 473 juvenile dermatomyositis, 532 polymyositis and 202 adult dermatomyositis, juvenile dermatomyositis or polymyositis patients with anti-histidyl-tRNA synthetase (anti-Jo-1) autoantibodies, and compared them with 4724 controls. Single-nucleotide polymorphisms showing strong associations (P<5×10(-8)) in GWAS were identified in the major histocompatibility complex (MHC) region for all myositis phenotypes together, as well as for the four clinical and autoantibody phenotypes studied separately. Imputation and regression analyses found that alleles comprising the human leukocyte antigen (HLA) 8.1 ancestral haplotype (AH8.1) defined essentially all the genetic risk in the phenotypes studied. Although the HLA DRB1*03:01 allele showed slightly stronger associations with adult and juvenile dermatomyositis, and HLA B*08:01 with polymyositis and anti-Jo-1 autoantibody-positive myositis, multiple alleles of AH8.1 were required for the full risk effects. Our findings establish that alleles of the AH8.1 comprise the primary genetic risk factors associated with the major myositis phenotypes in geographically diverse Caucasian populations.
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measures of adult and juvenile dermatomyositis polymyositis and inclusion body myositis physician and patient parent global activity manual muscle testing mmt health assessment questionnaire haq childhood health assessment questionnaire c haq
Arthritis Care and Research, 2011Co-Authors: Lisa G Rider, Helene Alexanderson, Victoria P Werth, Adam M Huber, Anand Prahalad Rao, Nicolino Ruperto, Laura Herbelin, Richard J Barohn, David A Isenberg, Frederick W MillerAbstract:The idiopathic inflammatory myopathies, including adult and juvenile dermatomyositis (DM), polymyositis (PM), and inclusion body myositis (IBM), are rare systemic autoimmune diseases that are characterized by chronic proximal muscle inflammation and weakness. In previous decades, there were few commonly used outcome measures in myositis, and those outcome measures were not validated. Thus, in the past the assessment of outcomes in therapeutic trials was focused on non-standardized measurement of muscle strength and function only. Over the last decade, however, two international collaborative groups, the International Myositis Assessment and Clinical Studies Group (IMACS) and the Paediatric Rheumatology International Trials Organisation (PRINTO), have defined consensus core set measures to assess myositis disease activity and damage in adults and children and have begun to validate and standardize these measures (1;2). IMACS and PRINTO have also developed preliminary definitions of improvement, which can be used as outcomes for therapeutic trials. These response criteria combine the core set activity measures to determine clinically meaningful improvement (3;4). Our section on myositis assessment focuses first on these core set measures of disease activity, quality of life (which is part of the PRINTO core set of activity, but a separate assessment domain for IMACS), and disease damage. To date, most of the validation data available for these core set measures are in patients with juvenile DM, with more limited validation in adult patients with DM or PM. Despite these efforts, there are still important gaps in validation of these core set measures, and no validation studies have yet been performed in patients with IBM, although they are now being used frequently in myositis therapeutic trials. We end the chapter with tools that have been used primarily in research studies and a few therapeutic trials, which have some supporting validation in certain subgroups of patients with myositis. These tools are primarily organ-specific measures, including strength and functional assessments and cutaneous assessment tools. Quantitative muscle testing and the IBM Functional Rating Scale are the most commonly used instruments to assess patients with IBM, and although they have little supporting validation in myositis, quantitative muscle testing has been well validated in other myopathies and has been used frequently as an endpoint in therapeutic trials for IBM. Although the methods for the assessment of myositis patients have been limited in their scope, great strides have been made in the last decade in the development of new partially validated tools (see Table 1) and international multidisciplinary consensus in using these measures that should enhance our understanding of the diverse effects of myositis on many organ systems and the development of new therapies. Table 1 Summary of Measures of Disease Activity in Myositis Physician and Patient/Parent Global Activity General Description Purpose An overall rating of the disease activity related to myositis, defined as potentially reversible pathology or physiology resulting from the underlying disease process (1).
Jessica M. Prebble - One of the best experts on this subject based on the ideXlab platform.
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taxonomic revision of the Myosotis australis group boraginaceae native to australia new zealand and new guinea
Australian Systematic Botany, 2020Co-Authors: Heidi M. Meudt, Michael J Thorsen, Jessica M. PrebbleAbstract:The three main aims of this study were to circumscribe the Myosotis australis R.Br. group, determine the taxonomic utility of pollen characters, and delimit species and revise their taxonomy using macro-morphological and palynological data. The M. australis group is here recircumscribed to comprise two species, M. saxatilis Petrie (Marlborough and Otago, New Zealand) and M. australis. Myosotis australis is a widespread, morphologically variable species with two subspecies. M. australis subsp. australis comprises all Australian and most New Zealand specimens, including M. mooreana Lehnebach, M. lytteltonensis (Laing & A.Wall) de Lange, and several white- or yellow-flowered tag-named taxa from New Zealand, whereas M. australis subsp. saruwagedica (Schltr. ex Brand) Meudt, Thorsen & Prebble, comb. et stat. nov. is endemic to New Guinea. The M. australis group can be distinguished from all other ebracteate-erect Myosotis plants sampled to date, including the Australian endemic, M. exarrhena F.Muell., by a suite of characters, i.e. included anthers, calyx with both retrorse and hooked trichomes, rosette leaf trichomes retrorse abaxially and oblique to the midrib adaxially, and leaf length:width ratio of >2:1. Other characters can distinguish the group from M. discolor Pers., M. arvensis (L.) Hill, and M. umbrosa Meudt, Prebble & Thorsen respectively. Pollen characters were not useful for species delimitation within the M. australis group, but they can help distinguish several species outside it, including natural hybrids of M. australis and M. exarrhena in Australia. Myosotis australis, M. saxatilis and M. exarrhena are included in the taxonomic treatment, whereas introduced species M. discolor and M. arvensis are included in the key only.
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species limits and taxonomic revision of the bracteate prostrate group of southern hemisphere forget me nots Myosotis boraginaceae including description of three new species endemic to new zealand
Australian Systematic Botany, 2018Co-Authors: Heidi M. Meudt, Jessica M. PrebbleAbstract:A taxonomic revision of southern hemisphere bracteate-prostrate forget-me-nots (Myosotis L., Boraginaceae) is presented here. The group comprises mostly species endemic to New Zealand plus the South American Myosotis antarctica Hook.f. (also Campbell Island) and M. albiflora Hook.f. The statistical analyses of morphological data from herbarium specimens reported here support recognition of five main subgroups on the basis of habit. Excluding the M. pygmaea Colenso species group (M. antarctica, M. brevis de Lange & Barkla, M. drucei (L.B.Moore) de Lange & Barkla, M. glauca (G.Simpson & J.S.Thomson) de Lange & Barkla, and M. pygmaea), which is being treated elsewhere, 14 species are recognised in the following four remaining subgroups: (1) creeping-species group: M. matthewsii L.B.Moore, M. chaffeyorum Lehnebach, M. spatulata G.Forst., M. tenericaulis Petrie, and M. albiflora; (2) cushion-species group: M. uniflora Hook.f., M. pulvinaris Hook.f., and M. glabrescens L.B.Moore; (3) M. cheesemanii + M. colensoi species group: M. cheesemanii Petrie and M. colensoi J.F.Macbr.; and (4) M. lyallii species group: M. lyallii Hook.f. and new species M. retrorsa Meudt, Prebble & Hindmarsh-Walls. New species Myosotis umbrosa Meudt, Prebble & Thorsen and M. bryonoma Meudt, Prebble & Thorsen do not fit comfortably within these subgroups. Myosotis elderi L.B.Moore is treated as M. lyallii subsp. elderi (L.B.Moore) Meudt & Prebble. For each of the 14 species revised here, a key to species, descriptions, phenology, distributions, maps, illustrations, specimens examined and notes are provided. Some specimens examined do not fit within these species and require additional comparative studies, including with certain ebracteate-erect species, before taxonomic decisions can be made. Future research on these and other southern hemisphere Myosotis should incorporate the morphological data presented here, with additional genetic, cytological, pollen, and other data in an integrative systematic framework.
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microsatellite markers for the new zealand endemic Myosotis pygmaea species group boraginaceae amplify across species
Applications in Plant Sciences, 2015Co-Authors: Heidi M. Meudt, Jessica M. Prebble, Jennifer A Tate, Vaughan V SymondsAbstract:Premise of the study: Microsatellite loci were developed as polymorphic markers for the New Zealand endemic Myosotis pygmaea species group (Boraginaceae) for use in species delimitation and population and conservation genetic studies. Methods and Results: Illumina MiSeq sequencing was performed on genomic DNA from seedlings of M. drucei. From trimmed paired-end sequences >400 bp, 484 microsatellite loci were identified. Twelve of 48 microsatellite loci tested were found to be polymorphic and consistently scorable when screened on 53 individuals from four populations representing the geographic range of M. drucei. They also amplify in all other species in the M. pygmaea species group, i.e., M. antarctica, M. brevis, M. glauca, and M. pygmaea, as well as 18 other Myosotis species. Conclusions: These 12 polymorphic microsatellite markers establish an important resource for research and conservation of the M. pygmaea species group and potentially other Southern Hemisphere Myosotis.
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Native New Zealand forget-me-nots (Myosotis, Boraginaceae) comprise a Pleistocene species radiation with very low genetic divergence
Plant Systematics and Evolution, 2015Co-Authors: Heidi M. Meudt, Jessica M. Prebble, Carlos A LehnebachAbstract:Reconstruction of molecular phylogenies is an important step towards understanding the evolutionary history of island plant radiations. The New Zealand forget-me-nots ( Myosotis, Boraginaceae) comprise a lineage of over 40 closely related but morphologically and ecologically diverse species whose evolutionary history and taxonomy are unclear. Myosotis is a high priority for systematic research in New Zealand because a high proportion of these species are threatened, and many have restricted geographic ranges and occupy very specific habitats. Here, we investigated the relationships and age of Southern Hemisphere forget-me-nots by performing phylogenetic, molecular dating, and other analyses of DNA sequence datasets from representatives of nearly all described species. To this end, we used both chloroplast ( atp I –atp H + rps 16– trn Q) and nuclear ribosomal (ITS + ETS) DNA sequences, as well as amplified fragment length polymorphisms (AFLPs). Our analyses showed that genus Myosotis likely arose in the Northern Hemisphere during the Miocene with the ancestor of the Southern Hemisphere lineage arising in the Pleistocene and radiating shortly thereafter. The Southern Hemisphere Myosotis species have very low levels of genetic divergence and their relationships are largely unresolved, likely due to a combination of recent radiation, hybridization, and incomplete lineage sorting. Our results are compared to those of similar studies on other New Zealand species radiations, and implications for ongoing and future Myosotis taxonomic and evolutionary research are discussed.
Iago Pinalfernandez - One of the best experts on this subject based on the ideXlab platform.
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machine learning algorithms reveal unique gene expression profiles in muscle biopsies from patients with different types of myositis
Annals of the Rheumatic Diseases, 2020Co-Authors: Iago Pinalfernandez, Assia Derfoul, José César Milisenda, Frederick W Miller, Maria Casaldominguez, Katherine Pak, Josep Maria Graujunyent, Albert Selvaocallaghan, Carme Carrionribas, Julie J. PaikAbstract:Objectives Myositis is a heterogeneous family of diseases that includes dermatomyositis (DM), antisynthetase syndrome (AS), immune-mediated necrotising myopathy (IMNM), inclusion body myositis (IBM), polymyositis and overlap myositis. Additional subtypes of myositis can be defined by the presence of myositis-specific autoantibodies (MSAs). The purpose of this study was to define unique gene expression profiles in muscle biopsies from patients with MSA-positive DM, AS and IMNM as well as IBM. Methods RNA-seq was performed on muscle biopsies from 119 myositis patients with IBM or defined MSAs and 20 controls. Machine learning algorithms were trained on transcriptomic data and recursive feature elimination was used to determine which genes were most useful for classifying muscle biopsies into each type and MSA-defined subtype of myositis. Results The support vector machine learning algorithm classified the muscle biopsies with >90% accuracy. Recursive feature elimination identified genes that are most useful to the machine learning algorithm and that are only overexpressed in one type of myositis. For example, CAMK1G (calcium/calmodulin-dependent protein kinase IG), EGR4 (early growth response protein 4) and CXCL8 (interleukin 8) are highly expressed in AS but not in DM or other types of myositis. Using the same computational approach, we also identified genes that are uniquely overexpressed in different MSA-defined subtypes. These included apolipoprotein A4 (APOA4), which is only expressed in anti-3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) myopathy, and MADCAM1 (mucosal vascular addressin cell adhesion molecule 1), which is only expressed in anti-Mi2-positive DM. Conclusions Unique gene expression profiles in muscle biopsies from patients with MSA-defined subtypes of myositis and IBM suggest that different pathological mechanisms underly muscle damage in each of these diseases.
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identification of distinctive interferon gene signatures in different types of myositis
Neurology, 2019Co-Authors: Assia Derfoul, Paul H. Plotz, Iago Pinalfernandez, Frederick W Miller, Maria Casaldominguez, Katherine Pak, José César MilisendaAbstract:Objective Activation of the type 1 interferon (IFN1) pathway is a prominent feature of dermatomyositis (DM) muscle and may play a role in the pathogenesis of this disease. However, the relevance of the IFN1 pathway in patients with other types of myositis such as the antisynthetase syndrome (AS), immune-mediated necrotizing myopathy (IMNM), and inclusion body myositis (IBM) is largely unknown. Moreover, the activation of the type 2 interferon (IFN2) pathway has not been comprehensively explored in myositis. In this cross-sectional study, our objective was to determine whether IFN1 and IFN2 pathways are differentially activated in different types of myositis by performing RNA sequencing on muscle biopsy samples from 119 patients with DM, IMNM, AS, or IBM and on 20 normal muscle biopsies. Methods The expression of IFN1- and IFN2-inducible genes was compared between the different groups. Results The expression of IFN1-inducible genes was high in DM, moderate in AS, and low in IMNM and IBM. In contrast, the expression of IFN2-inducible genes was high in DM, IBM, and AS but low in IMNM. The expression of IFN-inducible genes correlated with the expression of genes associated with inflammation and muscle regeneration. Of note, ISG15 expression levels alone performed as well as composite scores relying on multiple genes to monitor activation of the IFN1 pathway in myositis muscle biopsies. Conclusions IFN1 and IFN2 pathways are differentially activated in different forms of myositis. This observation may have therapeutic implications because immunosuppressive medications may preferentially target each of these pathways.
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anti ro52 autoantibodies are associated with interstitial lung disease and more severe disease in patients with juvenile myositis
Annals of the Rheumatic Diseases, 2019Co-Authors: Sara Sabbagh, Iago Pinalfernandez, Takayuki Kishi, Ira N Targoff, Frederick W Miller, Lisa G Rider, Andrew L. MammenAbstract:Objectives Anti-Ro52 autoantibodies are associated with more severe interstitial lung disease (ILD) in adult myositis patients with antiaminoacyl transfer (t)RNA synthetase autoantibodies. However, few studies have examined anti-Ro52 autoantibodies in juvenile myositis. The purpose of this study was to define the prevalence and clinical features associated with anti-Ro52 autoantibodies in a large cohort of patients with juvenile myositis. Methods We screened sera from 302 patients with juvenile dermatomyositis (JDM), 25 patients with juvenile polymyositis (JPM) and 44 patients with juvenile connective tissue disease–myositis overlap (JCTM) for anti-Ro52 autoantibodies by ELISA. Clinical characteristics were compared between myositis patients with and without anti-Ro52 autoantibodies. Results Anti-Ro52 autoantibodies were found in 14% patients with JDM, 12% with JPM and 18% with JCTM. Anti-Ro52 autoantibodies were more frequent in patients with antiaminoacyl tRNA synthetase (64%, p Conclusions Anti-Ro52 autoantibodies are present in 14% of patients with juvenile myositis and are strongly associated with anti-MDA5 and antiaminoacyl tRNA synthetase autoantibodies. In all patients with juvenile myositis, those with anti-Ro52 autoantibodies were more likely to have ILD. Furthermore, patients with anti-Ro52 autoantibodies have more severe disease and a poorer prognosis.
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the diagnostic work up of cancer associated myositis
Current Opinion in Rheumatology, 2018Co-Authors: Albert Selvaocallaghan, Xavier Martinezgomez, Ernesto Tralleroaraguas, Iago PinalfernandezAbstract:Purpose of reviewDespite the well-recognized association between malignancy and myositis, definite data indicating the best strategy for diagnosing cancer in myositis patients is lacking. In this article, we review the data on cancer screening in patients with myositis, and propose an algorithm for
D G Herbert - One of the best experts on this subject based on the ideXlab platform.
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myosotella Myosotis mollusca ellobiidae an overlooked but well established introduced species in south africa
African Journal of Marine Science, 2012Co-Authors: D G HerbertAbstract:Myosotella Myosotis is shown to be a well-established alien species in South Africa. Discovered in Port Elizabeth more than 100 years ago, it was initially thought to be indigenous and was described under two different names, but subsequent taxonomic work has demonstrated that these are synonyms of the variable and widely introduced European M. Myosotis. This information, published in a revision of western Atlantic Ellobiidae, has escaped the attention of the South African marine science community. There has been no recent mention of M. Myosotis or its two pseudoindigenous synonyms in the literature pertaining to either the estuaries or the malacofauna of South Africa, or to marine bioinvasions in the region. This example serves to demonstrate that invasion biology has a global context and that taxonomic literature is an important source of pertinent data. The fact that a species, which evidently occurs in abundance, can be overlooked for so long is both surprising and sobering.
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short communication myosotella Myosotis mollusca ellobiidae an overlooked but well established introduced species in south africa
African Journal of Marine Science, 2012Co-Authors: D G HerbertAbstract:Myosotella Myosotis is shown to be a well-established alien species in South Africa. Discovered in Port Elizabeth more than 100 years ago, it was initially thought to be indigenous and was described under two different names, but subsequent taxonomic work has demonstrated that these are synonyms of the variable and widely introduced European M. Myosotis . This information, published in a revision of western Atlantic Ellobiidae, has escaped the attention of the South African marine science community. There has been no recent mention of M. Myosotis or its two pseudoindigenous synonyms in the literature pertaining to either the estuaries or the malacofauna of South Africa, or to marine bioinvasions in the region. This example serves to demonstrate that invasion biology has a global context and that taxonomic literature is an important source of pertinent data. The fact that a species, which evidently occurs in abundance, can be overlooked for so long is both surprising and sobering. Keywords : Alexia acuminata, Alexia pulchella , introduced estuarine species, invasive, pseudoindigenous synonyms African Journal of Marine Science 2012, 34(3): 459–464
Heidi M. Meudt - One of the best experts on this subject based on the ideXlab platform.
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taxonomic revision of five species groups of ebracteate erect Myosotis boraginaceae endemic to new zealand based on morphology and description of new subspecies
Australian Systematic Botany, 2021Co-Authors: Heidi M. MeudtAbstract:Macro-morphological data were analysed to assess the distinctiveness and revise the taxonomy of 14 species, varieties and tag-named taxa in five informal species groups of ebracteate-erect forget-me-nots endemic to New Zealand. The following nine species are recognised: Myosotis albosericea Hook.f., M. brockiei L.B.Moore & M.J.A.Simpson, M. capitata Hook.f., M. concinna Cheeseman, M. goyenii Petrie, M. laeta Cheeseman, M. monroi Cheeseman, M. rakiura L.B.Moore, and M. traversii Hook.f. Three species have two allopatric subspecies each in the South Island, distinguished by few, minor morphological characters, including Myosotis brockiei subsp. brockiei and M. brockiei subsp. dysis Courtney & Meudt subsp. nov., M. goyenii subsp. goyenii and M. goyenii subsp. infima Meudt & Heenan, and M. traversii subsp. cantabrica (L.B.Moore) Meudt comb. et stat. nov. and M. traversii subsp. traversii. Myosotis × cinerascens Petrie is hypothesised to be a rare natural hybrid involving M. traversii subsp. cantabrica and another species, possibly M. colensoi. Several vegetative and floral characteristics can distinguish the study taxa from one another and from other ebracteate-erect species. The nine species plus M. × cinerascens are included in the taxonomic treatment, and the key also includes other recently revised ebracteate-erect species.
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taxonomic revision of the Myosotis australis group boraginaceae native to australia new zealand and new guinea
Australian Systematic Botany, 2020Co-Authors: Heidi M. Meudt, Michael J Thorsen, Jessica M. PrebbleAbstract:The three main aims of this study were to circumscribe the Myosotis australis R.Br. group, determine the taxonomic utility of pollen characters, and delimit species and revise their taxonomy using macro-morphological and palynological data. The M. australis group is here recircumscribed to comprise two species, M. saxatilis Petrie (Marlborough and Otago, New Zealand) and M. australis. Myosotis australis is a widespread, morphologically variable species with two subspecies. M. australis subsp. australis comprises all Australian and most New Zealand specimens, including M. mooreana Lehnebach, M. lytteltonensis (Laing & A.Wall) de Lange, and several white- or yellow-flowered tag-named taxa from New Zealand, whereas M. australis subsp. saruwagedica (Schltr. ex Brand) Meudt, Thorsen & Prebble, comb. et stat. nov. is endemic to New Guinea. The M. australis group can be distinguished from all other ebracteate-erect Myosotis plants sampled to date, including the Australian endemic, M. exarrhena F.Muell., by a suite of characters, i.e. included anthers, calyx with both retrorse and hooked trichomes, rosette leaf trichomes retrorse abaxially and oblique to the midrib adaxially, and leaf length:width ratio of >2:1. Other characters can distinguish the group from M. discolor Pers., M. arvensis (L.) Hill, and M. umbrosa Meudt, Prebble & Thorsen respectively. Pollen characters were not useful for species delimitation within the M. australis group, but they can help distinguish several species outside it, including natural hybrids of M. australis and M. exarrhena in Australia. Myosotis australis, M. saxatilis and M. exarrhena are included in the taxonomic treatment, whereas introduced species M. discolor and M. arvensis are included in the key only.
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species limits and taxonomic revision of the bracteate prostrate group of southern hemisphere forget me nots Myosotis boraginaceae including description of three new species endemic to new zealand
Australian Systematic Botany, 2018Co-Authors: Heidi M. Meudt, Jessica M. PrebbleAbstract:A taxonomic revision of southern hemisphere bracteate-prostrate forget-me-nots (Myosotis L., Boraginaceae) is presented here. The group comprises mostly species endemic to New Zealand plus the South American Myosotis antarctica Hook.f. (also Campbell Island) and M. albiflora Hook.f. The statistical analyses of morphological data from herbarium specimens reported here support recognition of five main subgroups on the basis of habit. Excluding the M. pygmaea Colenso species group (M. antarctica, M. brevis de Lange & Barkla, M. drucei (L.B.Moore) de Lange & Barkla, M. glauca (G.Simpson & J.S.Thomson) de Lange & Barkla, and M. pygmaea), which is being treated elsewhere, 14 species are recognised in the following four remaining subgroups: (1) creeping-species group: M. matthewsii L.B.Moore, M. chaffeyorum Lehnebach, M. spatulata G.Forst., M. tenericaulis Petrie, and M. albiflora; (2) cushion-species group: M. uniflora Hook.f., M. pulvinaris Hook.f., and M. glabrescens L.B.Moore; (3) M. cheesemanii + M. colensoi species group: M. cheesemanii Petrie and M. colensoi J.F.Macbr.; and (4) M. lyallii species group: M. lyallii Hook.f. and new species M. retrorsa Meudt, Prebble & Hindmarsh-Walls. New species Myosotis umbrosa Meudt, Prebble & Thorsen and M. bryonoma Meudt, Prebble & Thorsen do not fit comfortably within these subgroups. Myosotis elderi L.B.Moore is treated as M. lyallii subsp. elderi (L.B.Moore) Meudt & Prebble. For each of the 14 species revised here, a key to species, descriptions, phenology, distributions, maps, illustrations, specimens examined and notes are provided. Some specimens examined do not fit within these species and require additional comparative studies, including with certain ebracteate-erect species, before taxonomic decisions can be made. Future research on these and other southern hemisphere Myosotis should incorporate the morphological data presented here, with additional genetic, cytological, pollen, and other data in an integrative systematic framework.
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microsatellite markers for the new zealand endemic Myosotis pygmaea species group boraginaceae amplify across species
Applications in Plant Sciences, 2015Co-Authors: Heidi M. Meudt, Jessica M. Prebble, Jennifer A Tate, Vaughan V SymondsAbstract:Premise of the study: Microsatellite loci were developed as polymorphic markers for the New Zealand endemic Myosotis pygmaea species group (Boraginaceae) for use in species delimitation and population and conservation genetic studies. Methods and Results: Illumina MiSeq sequencing was performed on genomic DNA from seedlings of M. drucei. From trimmed paired-end sequences >400 bp, 484 microsatellite loci were identified. Twelve of 48 microsatellite loci tested were found to be polymorphic and consistently scorable when screened on 53 individuals from four populations representing the geographic range of M. drucei. They also amplify in all other species in the M. pygmaea species group, i.e., M. antarctica, M. brevis, M. glauca, and M. pygmaea, as well as 18 other Myosotis species. Conclusions: These 12 polymorphic microsatellite markers establish an important resource for research and conservation of the M. pygmaea species group and potentially other Southern Hemisphere Myosotis.
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Native New Zealand forget-me-nots (Myosotis, Boraginaceae) comprise a Pleistocene species radiation with very low genetic divergence
Plant Systematics and Evolution, 2015Co-Authors: Heidi M. Meudt, Jessica M. Prebble, Carlos A LehnebachAbstract:Reconstruction of molecular phylogenies is an important step towards understanding the evolutionary history of island plant radiations. The New Zealand forget-me-nots ( Myosotis, Boraginaceae) comprise a lineage of over 40 closely related but morphologically and ecologically diverse species whose evolutionary history and taxonomy are unclear. Myosotis is a high priority for systematic research in New Zealand because a high proportion of these species are threatened, and many have restricted geographic ranges and occupy very specific habitats. Here, we investigated the relationships and age of Southern Hemisphere forget-me-nots by performing phylogenetic, molecular dating, and other analyses of DNA sequence datasets from representatives of nearly all described species. To this end, we used both chloroplast ( atp I –atp H + rps 16– trn Q) and nuclear ribosomal (ITS + ETS) DNA sequences, as well as amplified fragment length polymorphisms (AFLPs). Our analyses showed that genus Myosotis likely arose in the Northern Hemisphere during the Miocene with the ancestor of the Southern Hemisphere lineage arising in the Pleistocene and radiating shortly thereafter. The Southern Hemisphere Myosotis species have very low levels of genetic divergence and their relationships are largely unresolved, likely due to a combination of recent radiation, hybridization, and incomplete lineage sorting. Our results are compared to those of similar studies on other New Zealand species radiations, and implications for ongoing and future Myosotis taxonomic and evolutionary research are discussed.
