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  • 1
    Language: English
    In: The Journal of experimental biology, June 2015, Vol.218(Pt 11), pp.1693-8
    Description: Symsagittifera roscoffensis is a plathelminth living in symbiosis with the green algae Tetraselmis convolutae. Host and symbiont are a model system for the study of endosymbiosis, which has so far mainly focused on their biochemical interactions. Symsagittifera roscoffensis is well known for its positive phototaxis that is hypothesized to optimize the symbiont's light perception for photosynthesis. In this study, we conducted a detailed analysis of phototaxis using light sources of different wavelength and brightness by videotracking. Furthermore, we compared the behavioural data with the electron transfer rate of the photosystem from cultured symbiotic cells. The symbiotic algae is adapted to low light conditions, showing a positive electron transfer rate at a photosynthetically active radiation of 0.112 µmol photons m(-2) s(-1), and S. roscoffensis showed a positive phototactic behaviour for light intensities up to 459.17 µmol photons m(-2) s(-1), which is not optimal regarding the needs of the symbiotic cells and may even harm host and symbiont. Red light cannot be detected by the animals and therefore their eyes seem not to be suitable for measuring the exact photosynthetically active radiation to the benefit of the photosymbionts.
    Keywords: Endosymbionts ; Endosymbioses ; Host ; Photoautotroph ; Phototaxis ; Light ; Chlorophyta -- Radiation Effects ; Platyhelminths -- Radiation Effects
    ISSN: 00220949
    E-ISSN: 1477-9145
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  • 2
    Language: English
    In: Molecular Phylogenetics and Evolution, Nov, 2014, Vol.80, p.79(9)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.ympev.2014.08.001 Byline: Janus Borner, Peter Rehm, Ralph O. Schill, Ingo Ebersberger, Thorsten Burmester Abstract: Display Omitted Article History: Received 18 March 2014; Revised 15 July 2014; Accepted 1 August 2014
    Keywords: Phylogeny
    ISSN: 1055-7903
    Source: Cengage Learning, Inc.
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  • 3
    Language: English
    In: Journal of Limnology, 01 May 2013, Vol.72(1s), pp.e20-e20
    Description: Although tardigrades have been studied for a long time, little is still known about their life-history traits. In the present study, two populations of the parthenogenetic African tardigrade species Paramacrobiotus kenianus, and the parthenogenetic species Paramacrobiotus palaui from the pacific islands of Palau were examined and analysed related to their life-history traits under laboratory conditions. The longevity in days (mean±SD) do not vary between the P. kenianus population (I) (125±35) and (II) (141±54), but P. palaui showed a significant shorter longevity (97±31). A recorded maximum age of 212 days was reached by P. kenianus population (II). P. kenianus population (I) laid 138±71 eggs (mean±SD) and population (II) 124±78 eggs (mean±SD) during their life, whereas P. palaui laid only 42±54 eggs (mean±SD). While the hatching time was similar in all species, starting after 6 to 9 days, the hatching rate in P. kenianus population (I) was 33%, compared with 51% of population (II) and 54% of P. palaui.
    Keywords: Culture, Life-History, Longevity, Population, Tardigrada ; Oceanography ; Ecology
    ISSN: 1129-5767
    E-ISSN: 1723-8633
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  • 4
    Language: English
    In: PLoS ONE, 01 January 2014, Vol.9(3), p.e92663
    Description: Many tardigrade species are capable of anhydrobiosis; however, mechanisms underlying their extreme desiccation resistance remain elusive. This study attempts to quantify the anhydrobiotic transcriptome of the limno-terrestrial tardigrade Milnesium tardigradum.A prerequisite for differential gene expression analysis was the generation of a reference hybrid transcriptome atlas by assembly of Sanger, 454 and Illumina sequence data. The final assembly yielded 79,064 contigs (〉100 bp) after removal of ribosomal RNAs. Around 50% of them could be annotated by SwissProt and NCBI non-redundant protein sequences. Analysis using CEGMA predicted 232 (93.5%) out of the 248 highly conserved eukaryotic genes in the assembly. We used this reference transcriptome for mapping and quantifying the expression of transcripts regulated under anhdydrobiosis in a time-series during dehydration and rehydration. 834 of the transcripts were found to be differentially expressed in a single stage (dehydration/inactive tun/rehydration) and 184 were overlapping in two stages while 74 were differentially expressed in all three stages. We have found interesting patterns of differentially expressed transcripts that are in concordance with a common hypothesis of metabolic shutdown during anhydrobiosis. This included down-regulation of several proteins of the DNA replication and translational machinery and protein degradation. Among others, heat shock proteins Hsp27 and Hsp30c were up-regulated in response to dehydration and rehydration. In addition, we observed up-regulation of ployubiquitin-B upon rehydration together with a higher expression level of several DNA repair proteins during rehydration than in the dehydration stage.Most of the transcripts identified to be differentially expressed had distinct cellular function. Our data suggest a concerted molecular adaptation in M. tardigradum that permits extreme forms of ametabolic states such as anhydrobiosis. It is temping to surmise that the desiccation tolerance of tradigrades can be achieved by a constitutive cellular protection system, probably in conjunction with other mechanisms such as rehydration-induced cellular repair.
    Keywords: Sciences (General)
    E-ISSN: 1932-6203
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  • 5
    Language: English
    In: Molecular Phylogenetics and Evolution, November 2014, Vol.80, pp.79-87
    Description: The monophyly of Ecdysozoa, which comprise molting phyla, has received strong support from several lines of evidence. However, the internal relationships of Ecdysozoa are still contended. We generated expressed sequence tags from a priapulid (penis worm), a kinorhynch (mud dragon), a tardigrade (water bear) and five chelicerate taxa by 454 transcriptome sequencing. A multigene alignment was assembled from 63 taxa, which comprised after matrix optimization 24,249 amino acid positions with high data density (2.6% gaps, 19.1% missing data). Phylogenetic analyses employing various models support the monophyly of Ecdysozoa. A clade combining Priapulida and Kinorhyncha (i.e. Scalidophora) was recovered as the earliest branch among Ecdysozoa. We conclude that Cycloneuralia, a taxon erected to combine Priapulida, Kinorhyncha and Nematoda (and others), are paraphyletic. Rather Arthropoda (including Onychophora) are allied with Nematoda and Tardigrada. Within Arthropoda, we found strong support for most clades, including monophyletic Mandibulata and Pancrustacea. The phylogeny within the Euchelicerata remained largely unresolved. There is conflicting evidence on the position of tardigrades: While Bayesian and maximum likelihood analyses of only slowly evolving genes recovered Tardigrada as a sister group to Arthropoda, analyses of the full data set, and of subsets containing genes evolving at fast and intermediate rates identified a clade of Tardigrada and Nematoda. Notably, the latter topology is also supported by the analyses of indel patterns.
    Keywords: Bayesian Analyses ; Ecdysozoa ; Indel ; Next Generation Sequencing ; Phylogenomics ; Biology
    ISSN: 1055-7903
    E-ISSN: 1095-9513
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  • 6
    Language: English
    In: Physiological and Biochemical Zoology, May-June, 2011, Vol.84(3), p.249(9)
    Keywords: Brine Shrimps -- Physiological Aspects ; Calorimetry -- Usage ; Cell Physiology -- Research
    ISSN: 1522-2152
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  • 7
    Language: English
    In: Comparative Biochemistry and Physiology, Part A, October 2011, Vol.160(2), pp.137-142
    Description: Using differential scanning calorimetry we demonstrated the presence of biological glasses and measured the glass transition temperatures (Tg) in dry encysted gastrula embryos (cysts) of the brine shrimp, , from eleven different locations, two of which provided cysts from parthenogenetic animals. Values for Tg were highest, by far, in cysts from the Mekong Delta, Vietnam (VN), these cysts having been produced from previous sequential inoculations into growth ponds of cysts from the San Francisco Bay, California, USA. Tg values for three groups of cysts were significantly higher than those of other cysts (except those of ) studied here, as well as all other desiccation-tolerant animal systems studied to date. We also measured three stress proteins (hsc70, artemin and p26) in all these cysts as well as the total alcohol soluble carbohydrates (ASC), about 90% of which is the disaccharide trehalose, a known component of biological glasses. We interpret the results in terms of mechanisms involved with desiccation tolerance and, to some extent, with thermal conditions at the sites of cyst collection
    Keywords: Artemia Cysts ; Dsc ; Glass Transition Temperature ; Biological Glasses ; Stress Proteins ; Chemistry ; Anatomy & Physiology
    ISSN: 1095-6433
    E-ISSN: 1531-4332
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  • 8
    Language: English
    In: Journal of Insect Physiology, 2011, Vol.57(5), pp.595-601
    Description: ► Physiological and biochemical investigations on dormant statoblasts of . ► Very low amounts of trehalose are found in all statoblasts. ► Present vitreous states in dry statoblasts as adaptation for desiccation tolerance and dispersal. ► Freeze tolerance in hydrated statoblasts as adaptation to low temperatures. Freshwater invertebrates often disperse between discrete habitat patches via the production of dormant propagules. Being dispersed passively by animal vectors or wind, certain adaptations for exposures to terrestrial and aerial conditions like desiccation and freezing are required. In the present study, we investigate the mechanisms of survival and physiological adaptations due to desiccation and low temperatures in the statoblasts of two populations of the freshwater bryozoan . Our results show that both sessoblasts and floatoblasts tolerate almost complete desiccation and subzero temperatures. Trehalose, a non-reducing disaccharide which has been related to desiccation tolerance, was detected by amperometric chromatography. However, due to the low concentrations found, it is unlikely that trehalose is playing a major part in desiccation tolerance of bryozoan statoblasts. Vitrification is assumed to be important in the survival of desiccation tolerant organisms. Differential scanning calorimetry revealed thermal transitions ( onset around 70 °C) in desiccated statoblasts, indicating that a vitreous matrix is present. During the exposure to subzero temperatures, freeze tolerance of statoblasts was confirmed by the detection of internal ice formation, which took place at a crystallisation temperature of between −6 °C and −12 °C.
    Keywords: Differential Scanning Calorimetry ; Statoblast ; Floatoblast ; Cristatella Mucedo ; Desiccation Tolerance ; Cold Tolerance ; Zoology
    ISSN: 0022-1910
    E-ISSN: 1879-1611
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  • 9
    Language: English
    In: 2012, Vol.7(9), p.e45682
    Description: Tardigrades have fascinated researchers for more than 300 years because of their extraordinary capability to undergo cryptobiosis and survive extreme environmental conditions. However, the survival mechanisms of tardigrades are still poorly understood mainly due to the absence of detailed knowledge about the proteome and genome of these organisms. Our study was intended to provide a basis for the functional characterization of expressed proteins in different states of tardigrades. High-throughput, high-accuracy proteomics in combination with a newly developed tardigrade specific protein database resulted in the identification of more than 3000 proteins in three different states: early embryonic state and adult animals in active and anhydrobiotic state. This comprehensive proteome resource includes protein families such as chaperones, antioxidants, ribosomal proteins, cytoskeletal proteins, transporters, protein channels, nutrient reservoirs, and developmental proteins. A comparative analysis of protein families in the different states was performed by calculating the exponentially modified protein abundance index which classifies proteins in major and minor components. This is the first step to analyzing the proteins involved in early embryonic development, and furthermore proteins which might play an important role in the transition into the anhydrobiotic state.
    Keywords: Research Article ; Biology ; Biochemistry
    E-ISSN: 1932-6203
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  • 10
    Language: English
    In: Journal of Zoological Systematics and Evolutionary Research, May, 2011, Vol.49, p.66(5)
    Description: To authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1439-0469.2010.00601.x Byline: Ralph O. Schill (1), K.Ingemar Jonsson (2), Martin Pfannkuchen (1), Franz Brummer (1) Keywords: Algae; diagnostic PCR; gut-content analysis; invertebrate; moss; predation Abstract: Abstract Mosses are an excellent habitat for tardigrades because of their ability to ensure a high humidity and to provide a rich food supply for both carnivorous and herbivorous species. Food choice can be correlated with the morphology of the buccal apparatus, and consequentially, their distribution is sometimes linked to food availability (nematodes, rotifers, plant cells, algae, yeast and bacteria). In many species, material containing chlorophyll is often observed in the midgut. However, little information has been available until now on the actual food preference of tardigrades. Since trophic interactions within soil food webs are difficult to study, here we use a polymerase chain reaction-based approach as a highly sensitive detection method. The study was carried out to investigate the presence of chlorophyll matter in the gut of active specimens, based on sequence analyses of the chloroplast ribulose 1,5-bisphosphate carboxylase/oxygenase large subunit (rbcL) gene from mosses and algae. The sequences found in the gut of Macrobiotus sapiens were derived from the moss families Pottiaceae and Erpodiaceae, in Macrobiotus persimilis and Echiniscus granulatus from the moss family Grimmiaceae, and in Richtersius coronifer from the green algae genus Trebouxia. Furthermore, we show the emission of green autofluorescence from the chloroplasts in the algae within the gut of tardigrades and followed the progress of digestion over a 48-h period. The autofluorescent emission level declined significantly, and after 2 days, the signal level was similar to the level of the starved control. Abstract (German): Zusammenfassung Nahrung von Tardigraden: Untersuchungen zum Verstandnis der Nahrungsauswahl, Nahrungsaufnahme und Verdauung Moose sind aufgrund ihrer Fahigkeiten, eine hohe Luftfeuchtigkeit zu gewahrleisten und fur carnivore und herbivore Tardigradenarten genugend Nahrung zur Verfugung zu stellen, ein hervorragender Lebensraum fur Tardigraden. Die Wahl der Nahrung korreliert mit der Morphologie des Buccalapparates und ihre Verbreitung wird von der Nahrungsverfugbarkeit (Nematoden, Rotatorien, Pflanzenzellen, Algen, Hefen und Bakterien) bestimmt. Bei vielen Arten kann chlorophyllhaltiges Material im Mitteldarm beobachtet werden. Es gibt bis jetzt jedoch nur wenige Informationen uber die Nahrungspraferenz von Tardigraden. Da trophische Interaktionen innerhalb des Nahrungsnetzes im Boden schwierig zu untersuchen sind, haben wir eine sehr sensitive Nachweismethode, basierend auf der Polymerasen-Kettenreaktion, angewandt. Basierend auf der Sequenzanalyse des Gens Ribulose-1,5-bisphosphat-Carboxylase/-Oxygenase (rbcL) in den Chloroplasten der Moose und Algen wurde das chlorophyllhaltige Material im Darm aktiver Tardigraden untersucht. Die Sequenzen, die im Darm von Macrobiotus sapiens gefunden wurden, gehoren zu Moosen der Familien Pottiaceae und Erpodiaceae, die in Macrobiotus persimilis und Echiniscus granulatus zu Moosen der Familie Grimmiaceae und die in Richtersius coronifer zu Grunalgen der Gattung Trebouxia. Zusatzlich zeigen wir die Emission der grunen Autofluoreszenz der gefressenen Chloroplasten im Darm der Tardigraden und die anschlie[sz]ende Verdauung uber einen Zeitraum von 48 Stunden. Die Autofluoreszenz nahm signifikant ab und nach zwei Tagen war das Signal ahnlich stark wie bei der ausgehungerten Kontrolle. Author Affiliation: (1)Department of Zoology, Universitat Stuttgart, Biological Institute, Stuttgart, Germany (2)Kristianstad University, School of Teacher Education, Aquatic Biology & Chemistry Group, Kristianstad, Sweden Article History: Accepted on 1 October 2010 Article note: Corresponding author: Ralph O. Schill (ralph.schill@bio.uni-stuttgart.de)
    Keywords: Monosaccharides -- Case Studies ; Food Habits -- Case Studies ; Humidity -- Case Studies ; Roundworms -- Case Studies ; Chlorophyll -- Case Studies ; Fluorescence -- Case Studies ; Food -- Case Studies
    ISSN: 0947-5745
    Source: Cengage Learning, Inc.
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