Oribatid mites (Acariformes, Sarcoptiformes: Oribatida) in the gills of Salmo spp. (Actinopterygii: Salmonidae) parr – Short communication

Live oribatid mites of the family Malaconothridae were found on Salmo spp. parr caught in the rivers of Northwest Russia. The mites were localised in the gill filaments and enclosed in connective tissue capsules. The encapsulation was accompanied by hyperplasia and displacement of the respiratory epithelium. One mite specimen was an adult female, while all the other specimens were protonymphs. The adult female and one protonymph specimen were identified as Tyrphonothrus sp. Other protonymphs could be identified only at the family level. The obtained partial 18S rDNA sequence of one protonymph was 100% identical to that of Tyrphonothrus maior (NCBI accession No. KY922215). This is the first report of living malaconothrid mites encapsulated in fish gills, and the phenomenon may assume parasitic behaviour. However, the nature of the relationship between the mites and the fish requires further investigations.

First record of Xiphinema hunaniense Wang & Wu, 1992 (Dorylaimida: Longidoridae) associated with tea (Camellia sinensis (L.) Kuntze) in Thanh Hoa, Vietnam

The dagger nematodes, Xiphinema spp., are migratory root-ectoparasitic nematodes that cause damage to a wide range of wild and cultivated plants over the world. In Vietnam, this nematode group has been studied mainly based on morphological characterizations. During a survey of pathogens associated with tea, a plant with many medicinal and therapeutic potentials, a population of Xiphinema hunaniense was recorded. This study provides the first morphological and molecular characterizations of Xiphinema hunaniense found on Tea in Vietnam. The 28S rDNA, and 18S rDNA phylogenetic trees of the genus Xiphinema are also provided. 18S rDNA sequence of X. hunaniense is also submitted to GenBank for the first time.

The long-time orphan protist Meringosphaera mediterranea Lohmann, 1902 [1903] is a centrohelid heliozoan

Meringosphaera is an enigmatic marine protist without clear phylogenetic affiliation, but it has long been suggested to be a chrysophytes-related autotroph. Microscopy-based reports indicate that it has a worldwide distribution, but no sequence data exists so far. We obtained the first 18S rDNA sequence for M. mediterranea (identified using light and electron microscopy) from the West Coast of Sweden. Observations of living cells revealed granulated axopodia and up to 6 globular photosynthesizing bodies about 2 μm in diameter, the nature of which requires further investigation. The ultrastructure of barbed undulating spine scales and patternless plate scales with a central thickening is in agreement with previous reports. Molecular phylogenetic analysis placed M. mediterranea inside the NC5 environmental clade of Centroplasthelida (Haptista) along with additional environmental sequences, together closely related to Choanocystidae. This placement is supported by similar scales in Meringosphaera and Choanocystidae. We searched the Tara Oceans 18S-V9 metabarcoding dataset which revealed four OTUs with 95.5-98.5% similarity, with oceanic distribution similar to that based on morphological observations. The current taxonomic position and species composition of the genus are discussed. The planktonic lifestyle of M. mediterranea contradicts the view of some authors that centrohelids enter the plankton only temporarily.

The neotypification of Frontonia vernalis (Ehrenberg, 1833) Ehrenberg, 1838 and the description of Frontonia paravernalis sp. nov. trigger a critical revision of frontoniid systematics

Background Among Oligohymenophorea (Ciliophora, Alveolata) the subclass Peniculia stands as one of the most well-known groups. Frontonia is the largest genus of Peniculia, and its representatives are spread in any type of water bodies as well as in soil. At a first glance, Frontonia species exhibit an overall similar morphology, and form a well-recognizable taxon of ciliates. Despite the general morphological homogeneity, the phylogenetic analysis based on the 18S rDNA sequencing showed that Frontonia is a non-monophyletic group. The systematics of this genus should be deeply reviewed, although additional issues complicate the task solving. First, type species of the genus is not yet clearly established, and no type material is available. In this context, the situation of F. vernalis, one of the first Frontonia ever described, is somehow puzzled: the description of this ciliate made by Ehrenberg (in 1833 and 1838) contains several inaccuracies and subsequent misidentifications by other authors occurred. Moreover, the 18S rDNA sequence of a putative F. vernalis is available on GenBank, but no morphological description of the correspondent specimens is provided; thus, in our opinion, it should be only prudently associated with F. vernalis or at least indicated as “F. vernalis”. Results In the present work, we provide the neotypification of F. vernalis newly found in Italy, presenting its multidisciplinary description and its neotype material. Similarly, we describe a novel species bearing Chlorella-like endosymbionts, Frontonia paravernalis sp. nov., retrieved in two far distant locations (Italy, Russia). A critical discussion on the status of Frontonia taxonomy and phylogeny is also presented, based on the 18S rDNA sequencing of both these two newly collected species and other 14 frontoniids isolated in different parts of the world. Finally, in the present study F. leucas was neotypified and proposed as the type species of the genus. Conclusions Green frontoniids form a monophyletic clade of freshwater organisms characterized by having a single contractile vacuole and bearing intracytoplasmatic Chlorella-like symbionts. With the neotypification of F. vernalis and F. leucas a fundamental step in Frontonia systematics was taken, and the bases for further taxonomic studies were laid.

Isolation and identification of a 2,3,7,8-Tetrachlorodibenzo-P-dioxin degrading strain and its biochemical degradation pathway

This study aims to find a high-efficiency degradation strain which can biodegrade the 2,3,7,8-Tetrachlorodibenzo-P-dioxin (2,3,7,8-TCDD). In this paper, a new fungus strain was isolated from activated sludge of Dagu Drainage River in Tianjin which was able to degrade 2,3,7,8-TCDD in the medium. Based on its morphology and phylogenetic analysis of its 18S rDNA sequence, the strain was identified as Penicillium sp. QI-1. Response surface methodology using central composite rotatable design of cultural conditions was successfully employed for optimization resulting in 87.9 % degradation of 2,3,7,8-TCDD (1 µg/mL) within 6 days. The optimum condition for degrading 2,3,7,8-TCDD was at 31℃ and pH 7.4. The biodegradation process was fitted to a first-order kinetic model. The kinetic equation was Ct=0.939e− 0.133t and its half-life was 5.21d. The fungus strain degraded 2,3,7,8-TCDD to form intermediates, they were 4,5-Dichloro-1,2-benzoquinone, 4,5-Dichlorocatechol, 2-Hydrooxy-1,4-benzoquinone, 1,2,4-Trihydroxybenzene and β-ketoadipic acid. A novel degradation pathway for 2,3,7,8-TCDD was proposed based on analysis of these metabolites. The results suggest that Penicillium sp. QI-1 may be an ideal microorganism for biodegradation of the 2,3,7,8-TCDD-contaminated environments.

18S rDNA Sequence-Structure Phylogeny of The Trypanosomatida (Kinetoplastea, Euglenozoa) with Special Reference on Trypanosoma

Background: Parasites of the order Trypanosomatida are known due to their medical relevance. Trypanosomes cause African sleeping sickness and Chagas disease in South America, and Leishmania Ross, 1903 species mutilate and kill hundreds of thousands of people each year. However, human pathogens are very few when compared to the great diversity of trypanosomatids. Despite the progresses made in the past decades on understanding the evolution of this group of organisms, there are still many open questions which require robust phylogenetic markers to increase the resolution of trees. Methods: Using two known 18S rDNA template structures (from Trypanosoma cruzi Chagas, 1909 and Trypanosoma brucei Plimmer & Bradford, 1899), individual 18S rDNA secondary structures were predicted by homology modeling. Sequences and their secondary structures, automatically encoded by a 12-letter alphabet (each nucleotide with its three structural states, paired left, paired right, unpaired), were simultaneously aligned. Sequence-structure trees were generated by neighbor joining and/or maximum likelihood.Results: With a few exceptions, all nodes within a sequence-structure maximum likelihood tree of 43 representative 18S rDNA sequence-structure pairs are robustly supported (bootstrap support >75). Even a quick and easy sequence-structure neighbor-joining analysis yields accurate results and enables reconstruction and discussion of the big picture for all 240 18S rDNA sequence-structure pairs of trypanosomatids that are currently available.Conclusions: We reconstructed the phylogeny of a comprehensive sampling of trypanosomes evaluated in the context of trypanosomatid diversity, demonstrating that the simultaneous use of 18S rDNA sequence and secondary structure data can reconstruct robust phylogenetic trees.

18S rDNA Sequence-Structure Phylogeny of the Trypanosomatida (Kinetoplastea, Euglenozoa) with Special Reference on Trypanosoma

BackgroundParasites of the order Trypanosomatida are known due to their medical relevance. Trypanosomes cause African sleeping sickness and Chagas disease in South America, and Leishmania Ross, 1903 species mutilate and kill hundreds of thousands of people each year. However, human pathogens are very few when compared to the great diversity of trypanosomatids. Despite the progresses made in the past decades on understanding the evolution of this group of organisms, there are still many open questions which require robust phylogenetic markers to increase the resolution of trees.MethodsUsing two known 18S rDNA template structures (from Trypanosoma cruzi Chagas, 1909 and Trypanosoma brucei Plimmer & Bradford, 1899), individual 18S rDNA secondary structures were predicted by homology modeling. Sequences and their secondary structures, automatically encoded by a 12-letter alphabet (each nucleotide with its three structural states, paired left, paired right, unpaired), were simultaneously aligned. Sequence-structure trees were generated by neighbor joining and/or maximum likelihood.ResultsWith a few exceptions, all nodes within a sequence-structure maximum likelihood tree of 43 representative 18S rDNA sequence-structure pairs are robustly supported (bootstrap support >75). Even a quick and easy sequence-structure neighbor-joining analysis yields accurate results and enables reconstruction and discussion of the big picture for all 240 18S rDNA sequence-structure pairs of trypanosomatids that are currently available.ConclusionsWe reconstructed the phylogeny of a comprehensive sampling of trypanosomes evaluated in the context of trypanosomatid diversity, demonstrating that the simultaneous use of 18S rDNA sequence and secondary structure data can reconstruct robust phylogenetic trees.

First record of natural Baylisascaris transfuga (Ascaridoidea, Nematoda) infection in wild rodents

The intestinal parasitic nematode, Baylisascaris transfuga, was recorded in wild rodents for the first time. Representatives of four murid species (15 Myodes rufocanus, 10 M. rutilus, 3 M. glareolus and 27 Microtus oeconomus) were collected in the White Sea coastal habitats in the south of the Kola Peninsula, Russia in July 2015 and examined for parasites. Encapsulated nematode larvae were detected in the mesentery and the large intestine wall of one grey-sided vole (M. rufocanus) and one tundra vole (M. oeconomus). Based on morphology, the larvae were identified as belonging to the genus Baylisascaris Sprent 1968. The partial 18S rDNA sequence of the larvae from the voles was obtained and fully corresponded to the sequence of Baylisascaris transfuga in the NCBI GenBank. The ITS rDNA and CoxI mtDNA sequences these larvae were also similar to the respective B. transfuga sequences in GenBank. The presence of B. transfuga in wild rodents suggests that rodents can participate in the B. transfuga life cycle.

Isolation, Characterization and Biotechnological Potentials of Thraustochytrids from Icelandic Waters

The following study reports on the first thraustochytrid isolates identified from Iceland. They were collected from three different locations off the northern coast of the country (Location A, Skagaströnd; Location B, Hveravík; and Location C, Eyjafjörður). Using 18S rDNA sequence analysis, isolates from Locations A and B were identified within the Thraustochytrium kinnei species while other isolates within the Sicyoidochytrium minutum species when compared to other known strains. Cells isolated from Locations A ( 2 . 10 ± 0 . 70 g/L) and B ( 1 . 54 ± 0 . 17 g/L) produced more biomass than the ones isolated from Location C ( 0 . 43 ± 0 . 02 g/L). This study offers the first-time examination of the utility of byproducts from fisheries as a nitrogen source in media formulation for thraustochytrids. Experiments showed that isolates produced more biomass (per unit of substrate) when cultured on nitrogen of marine ( 2 . 55 ± 0 . 74 g/L) as compared to of commercial origin ( 1 . 06 ± 0 . 57 g/L). Glycerol ( 2 . 43 ± 0 . 56 g/L) was a better carbon source than glucose ( 1 . 84 ± 0 . 57 g/L) in growth studies. Fatty acid (FA) profiles showed that the isolates from Location C (S. minutum) had low ratios of monounsaturated ( 4 . 21 ± 2 . 96 % ) and omega-6 ( 0 . 68 ± 0 . 59 % ) FAs. However, the isolates also had high ratios of docosahexaenoic acid (DHA; 35 . 65 ± 1 . 73 % ) and total omega-3 FAs ( 40 . 39 ± 2 . 39 % ), indicating that they could serve as a source of marine oils for human consumption and in aquaculture feeds. The T. kinnei isolates from Location A could be used in biodiesel production due to their high ratios of monounsaturated ( 18 . 38 ± 6 . 27 % ) long chain ( 57 . 43 ± 8 . 27 % ) FAs.