| 11. |
- Andersson, Håkan S., 1967-, et al.
(author)
-
The toxicity of ribbon worms: alpha-nemertides or tetrodotoxin, or both?
- 2016
-
In: Planta Medica. - : Georg Thieme Verlag KG. - 0032-0943 .- 1439-0221. ; 82:Supplement 1
-
Journal article (other academic/artistic)abstract
- The marine ribbon worms (nemerteans) are predators which capture their prey by everting a proboscis carrying a mixture of toxins which brings on rapid paralysis [1]. Moreover, ribbon worms have a thick layer of epidermal mucus of similar constitution. Tetrodotoxin (TTX) has been identified as one of these toxins [2]. The extreme toxicity of TTX (lethal by ingestion of 0.5-2 mg) is due to its ability to block voltage-gated sodium channels. Although several bacterial species (among these Vibrio sp.) have been linked to its synthesis, the biogenic origin and biosynthesis is unclear. One hypothesis is that TTX production occurs in a symbiotic relationship with its host, in this case the ribbon worm [3]. We have made significant effort to identify TTX in a setup for production through the cultivation of Vibrio alginolyticus in nutrient broth infused with mucus from the ribbon worm Lineus longissimus. Toxicity was demonstrated by fraction injections into shore crabs, but no TTX was found, and it could be shown conclusively that toxicity was unrelated to TTX and the Vibrio culture itself, and rather a constituent of the ribbon worm mucus [4]. The following studies led us to the discovery of a new class of peptides, the alpha-nemertides, in the mucus of the ribbon worms, which could be directly linked to the toxic effects. A literature review of the available evidence for TTX in ribbon worms show that the evidence in most cases are indirect, although notable exceptions exist. This points to the necessity to further investigate the presence and roles of TTX and alpha-nemertides in ribbon worms.
|
|
| 12. |
- ANDRADE, S.C.S, et al.
(author)
-
A transcriptomic approach to ribbon worm systematics (Nemertea): resolving the Pilidiophora problem.
- 2014
-
In: Molecular biology and evolution. - : Oxford University Press (OUP). - 0737-4038 .- 1537-1719. ; 31:12, s. 3206-3215
-
Journal article (peer-reviewed)abstract
- Resolving the deep relationships of ancient animal lineages has proven difficult using standard Sanger-sequencing approaches with a handful of markers. We thus reassess the relatively well-studied phylogeny of the phylum Nemertea (ribbon worms)—for which the targeted gene approaches had resolved many clades but had left key phylogenetic gaps—by using a phylogenomic approach using Illumina-based de novo assembled transcriptomes and automatic orthology prediction methods. The analysis of a concatenated data set of 2,779 genes (411,138 amino acids) with about 78% gene occupancy and a reduced version with 95% gene occupancy, under evolutionary models accounting or not for site-specific amino acid replacement patterns results in a well-supported phylogeny that recovers all major accepted nemertean clades with the monophyly of Heteronemertea, Hoplonemertea, Monostilifera, being well supported. Significantly, all the ambiguous patterns inferred from Sanger-based approaches were resolved, namely the monophyly of Palaeonemertea and Pilidiophora. By testing for possible conflict in the analyzed supermatrix, we observed that concatenation was the best solution, and the results of the analyses should settle prior debates on nemertean phylogeny. The study highlights the importance, feasibility, and completeness of Illumina-based phylogenomic data matrices.
|
|
| 13. |
- Andrade, S. C. S., et al.
(author)
-
Disentangling ribbon worm relationships: multi-locus analysis supports traditional classification of the phylum Nemertea
- 2012
-
In: Cladistics. - : Wiley. - 0748-3007. ; 28:2, s. 141-159
-
Journal article (peer-reviewed)abstract
- The phylogenetic relationships of selected members of the phylum Nemertea are explored by means of six markers amplified from the genomic DNA of freshly collected specimens (the nuclear 18S rRNA and 28S rRNA genes, histones H3 and H4, and the mitochondrial genes 16S rRNA and cytochrome c oxidase subunit I). These include all previous markers and regions used in earlier phylogenetic analyses of nemerteans, therefore acting as a scaffold to which one could pinpoint any previously published study. Our results, based on analyses of static and dynamic homology concepts under probabilistic and parsimony frameworks, agree in the non-monophyly of Palaeonemertea and in the monophyly of Heteronemerta and Hoplonemertea. The position of Hubrechtella and the Pilidiophora hypothesis are, however, sensitive to analytical method, as is the monophyly of the non-hubrechtiid palaeonemerteans. Our results are, however, consistent with the main division of Hoplonemertea into Polystilifera and Monostilifera, the last named being divided into Cratenemertea and Distromatonemertea, as well as into the main division of Heteronemertea into Baseodiscus and the remaining species. The study also continues to highlight the deficient taxonomy at the family and generic level within Nemertea and sheds light on the areas of the tree that require further refinement.
|
|
| 14. |
|
|
| 15. |
- Andre, C., et al.
(author)
-
Species identification of bivalve larvae using random amplified polymorphic DNA (RAPD): differentiation between Cerastoderma edule and C-lamarcki
- 1999
-
In: Journal of the Marine Biological Association of the United Kingdom. - 0025-3154. ; 79:3, s. 563-565
-
Journal article (peer-reviewed)abstract
- The polymerase chain reaction (PCR) was used to produce species-specific DNA markers (RAPDs) from two sibling cockle species and five other co-occurring intertidal bivalves. Amplification reactions with one single primer readily distinguished larvae and adults of Cerastoderma edule from larvae and adults of C. lamarcki, and from adults of Mya arenaria Macoma balthica, Scrobicularia plana, Venerupis pulastra and Mytilus edulis. Random amplified polymorphic DNA (RAPD) is suggested as a simple and quick method to determine species identity in taxa that are difficult to identify on the basis of morphological characters alone, such as marine bivalve larvae.
|
|
| 16. |
- Bachmann, L., et al.
(author)
-
Systematics and biodiversity research in the era of genomics
- 2016
-
In: Zoologica Scripta. - : Wiley. - 0300-3256 .- 1463-6409. ; 45, s. 3-4
-
Journal article (peer-reviewed)abstract
- On 5 November 2015, The Norwegian Academy of Sciences and Letters (DNVA) and the editors of the Zoologica Scripta invited to the one-day symposium ‘Systematics and Biodiversity Research in the Era of Genomics’. Some 80 scientists gathered at the premises of the DNVA in Oslo, Norway, to explore and discuss the current trends and future developments in the field of Animal Systematics. © 2016 The Authors. Zoologica Scripta published by John Wiley & Sons Ltd on behalf of Royal Swedish Academy of Sciences.
|
|
| 17. |
- Bachmann, L., et al.
(author)
-
The role of systematics for understanding ecosystem functions: Proceedings of the Zoologica Scripta Symposium, Oslo, Norway, 25 August 2022
- 2023
-
In: Zoologica Scripta. - : Wiley. - 0300-3256 .- 1463-6409. ; 52:3, s. 187-214
-
Journal article (peer-reviewed)abstract
- On 25 August 2022, the Zoologica Scripta - An International Journal of Systematic Zoology and the Norwegian Academy of Sciences and Letters arranged a symposium entitled 'The role of systematics for understanding ecosystem functions' in the Academy's premises in Oslo, Norway. The symposium aimed at offering a forum for exploring and discussing trends and future developments in the field of systematics. Eleven international experts contributed expertise on various issues related to global challenges, such as biodiversity assessments, databases, cutting-edge analysis tools, and the consequences of the taxonomic impediment. Here, we compiled a multi-author proceedings paper of the symposium contributions that are arranged in chapters and presents the content and the key conclusions of the majority of the presentations.
|
|
| 18. |
- Bergkvist, Johanna, et al.
(author)
-
Provtagningsdesign för övervakning av främmande arter : Övervakning i marin miljö
- 2020
-
Reports (other academic/artistic)abstract
- Denna rapport beskriver metod och resultat för identifiering av optimala övervakningsstationer för tidigt upptäckt av marina invasiva främmande arter samt uppföljning av dess spridningsmönster. Metoden är baserad på beräkning av en samlad invasionsrisk för 34 målarter som analyseras individuellt och samlade i relevanta ekologiska grupperingar som till exempel sötvattenstoleranta arter, marina arter eller bentiska arter. I analysen ingår tre faktorer:• Geografisk fördelning av lämpliga habitat beräknat med hjälp av utbredningsmodeller för varje art.• Artspecifik riskbedömning.• Introduktionsrisk i samband med fartygstrafik och vattenströmmar. Resultatet pekar på två separata spridningsmönster för invasiva arter till marina miljöer i Sverige; spridning av marina arter längs nordeuropeiska kustvatten och spridning av sötvattenstoleranta arter via den europeiska kontinenten. Dessa två spridningsvägar analyserades separat och resultaten stöder en jämn fördelning av övervakningsstationer längs den svenska kusten mellan Strömstad och Gävle, med fokus på de områden som pekas ut av de marina modellerna på västkusten och de områden som pekas ut av sötvattensmodellerna på östkusten. De mest lämpliga övervakningsplatserna är hamnområden.
|
|
| 19. |
- Chen, Hai-Xia, et al.
(author)
-
A comparative study of nemertean complete mitochondrial genomes, including two new ones for Nectonemertes cf. mirabilis and Zygeupolia rubens, may elucidate the fundamental pattern for the phylum Nemertea
- 2012
-
In: Bmc Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 13
-
Journal article (peer-reviewed)abstract
- Background: The mitochondrial genome is important for studying genome evolution as well as reconstructing the phylogeny of organisms. Complete mitochondrial genome sequences have been reported for more than 2200 metazoans, mainly vertebrates and arthropods. To date, from a total of about 1275 described nemertean species, only three complete and two partial mitochondrial DNA sequences from nemerteans have been published. Here, we report the entire mitochondrial genomes for two more nemertean species: Nectonemertes cf. mirabilis and Zygeupolia rubens. Results: The sizes of the entire mitochondrial genomes are 15365 bp for N. cf. mirabilis and 15513 bp for Z. rubens. Each circular genome contains 37 genes and an AT-rich non-coding region, and overall nucleotide composition is AT-rich. In both species, there is significant strand asymmetry in the distribution of nucleotides, with the coding strand being richer in T than A and in G than C. The AT-rich non-coding regions of the two genomes have some repeat sequences and stem-loop structures, both of which may be associated with the initiation of replication or transcription. The 22 tRNAs show variable substitution patterns in nemerteans, with higher sequence conservation in genes located on the H strand. Gene arrangement of N. cf. mirabilis is identical to that of Paranemertes cf. peregrina, both of which are Hoplonemertea, while that of Z. rubens is the same as in Lineus viridis, both of which are Heteronemertea. Comparison of the gene arrangements and phylogenomic analysis based on concatenated nucleotide sequences of the 12 mitochondrial protein-coding genes revealed that species with closer relationships share more identical gene blocks. Conclusion: The two new mitochondrial genomes share many features, including gene contents, with other known nemertean mitochondrial genomes. The tRNA families display a composite substitution pathway. Gene order comparison to the proposed ground pattern of Bilateria and some lophotrochozoans suggests that the nemertean ancestral mitochondrial gene order most closely resembles the heteronemertean type. Phylogenetic analysis proposes a sister-group relationship between Hetero- and Hoplonemertea, which supports one of two recent alternative hypotheses of nemertean phylogeny.
|
|
| 20. |
- Chen, Hai-Xia, et al.
(author)
-
Mutation and selection cause codon usage and bias in mitochondrial genomes of ribbon worms (Nemertea)
- 2014
-
In: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:1
-
Journal article (peer-reviewed)abstract
- The phenomenon of codon usage bias is known to exist in many genomes and it is mainly determined by mutation and selection. To understand the patterns of codon usage in nemertean mitochondrial genomes, we use bioinformatic approaches to analyze the protein-coding sequences of eight nemertean species. Neutrality analysis did not find a significant correlation between GC12 and GC3. ENc-plot showed a few genes on or close to the expected curve, but the majority of points with low-ENc values are below it. ENc-plot suggested that mutational bias plays a major role in shaping codon usage. The Parity Rule 2 plot (PR2) analysis showed that GC and AT were not used proportionally and we propose that codons containing A or U at third position are used preferentially in nemertean species, regardless of whether corresponding tRNAs are encoded in the mitochondrial DNA. Context-dependent analysis indicated that the nucleotide at the second codon position slightly affects synonymous codon choices. These results suggested that mutational and selection forces are probably acting to codon usage bias in nemertean mitochondrial genomes. 7copy; 2014 Chen et al.
|
|
