Twenty-two marine species of Dalytyphloplanida from Cuba, Panama, and Lanzarote are presented, si... more Twenty-two marine species of Dalytyphloplanida from Cuba, Panama, and Lanzarote are presented, sixteen of which are new to science. Five known species are recorded from Cuba: Kytorhynchus microstylus, Ceratopera paragracilis, Trigonostomum armatum, T. franki, and T. vanmecheleni. Neokytorhynchus pacificus is recorded for the first time in the Atlantic (Lanzarote). For one species, a new genus is erected to be included in a new family. A new genus and thirteen new species from Cuba and three new species from Panama are described. The new species are mainly distinguished from their congeners by the specific morphology of the copulatory structures. The new taxa are discussed in the context of a new phylogenetic analysis of Dalytyphloplanida. This analysis includes sequences of 238 species, 14 of which were sequenced for the first time. The phylogenetic analysis and the detailed morphology suggest that K. microstylus may constitute a complex of cryptic species. The internal phylogenetic...
Not sure of the Publishers copyright policy to archiving your journal articles online? Use these ... more Not sure of the Publishers copyright policy to archiving your journal articles online? Use these sites to find a summary of permissions that are normally given as part of each publisher's copyright transfer agreement. ... Willems, Maxime Lerons, F. Huysentruyt, F. Adriaens, D. Claeys, M. ARTOIS, Tom Borgonie, G. ... [Willems, Maxime; Lerons, F.; Claeys, M.; Borgonie, G.] Univ Ghent, Dept Biol, Nematol Sect, Ghent, Belgium. [Huysentruyt, F.; Adriaens, D.] Univ Ghent, Dept Biol, Grp Evolutionary Morphol Vertebrates, Ghent, Belgium. [Artois, T.] Hasselt Univ, Dept ...
Nanoparticles (NPs) are considered safe for prolonged internalization in cells. During the latest... more Nanoparticles (NPs) are considered safe for prolonged internalization in cells. During the latest years, an increasing amount of studies indicates cytotoxic effects of different nanoparticles (NPs). On the subject of genotoxicity, carcinogenicity and stem-cell-related toxicity, conflicting results are reported. Stem cells are an important target in several applications of NPs, f.e. in stem cell tracking systems, regenerative medicine and anti-cancer drugs... New insights in the toxicity of nanoparticles on stem cells not only address these aspects, they also contribute to our knowledge on defense mechanisms of different tissues. It is generally known that the intrinsic cellular repair capacity varies with the degree of cell potency, an important matter in developmental toxicity as well as in species- or tissue-related plasticity. Schmidtea mediterranea is a small invertebrate with an easy accessible population of totipotent stem cells. This makes it possible to study underlying mechanisms of nanoparticle toxicity on stem cells in vivo, and as such link them to physiological parameters. We focus on the toxicity and biocompatibility of silver NPs (AgNPs) and silica NPs (SiNPs) on stem-cell-specific activities. Both AgNPs and SiNPs are extensively used in biomedical applications, s.a. disinfectants, implants, as drug carriers or in bio-imaging. In our in vivo model system, we observed the uptake of AgNPs in stem cells via transmission electron microscopy. Stem cells responded by a proliferation decrease, measured via histon H3 immunostaining. We are currently looking into the underlying cause of this decrease, as the genotoxic character of this element is still under debate. Effects on cell cycle progression and differentiation were investigated by looking into the expression of the smedwi-1 gene and corresponding protein levels, both exclusively present in stem cells and indicative for different phases of the cell cycle. At the phenotypic level, concentration-dependent behavioral effects, including looper movements and curling, were observed. Exposure to a range of SiNPs concentrations showed no clear phenotypic or proliferation effects. This is a promising result for the further use of SiNPs, but extra research on the uptake and the effects of coating, and the influence of external parameters are needed for both NP types to confirm initial results.
... WIM WILLEMS 1, 2 *, TOM ARTOIS 2, MERLIJN JOCQUÉ 3 and LUC BRENDONCK 3 ... The Marine flora a... more ... WIM WILLEMS 1, 2 *, TOM ARTOIS 2, MERLIJN JOCQUÉ 3 and LUC BRENDONCK 3 ... The Marine flora and fauna of Darwin Harbour, Northern Aus-tralia. Museums and Art Galleries of the NorthernTerri-tory and the Australian Marine Sciences Association, Darwin. ...
Lake Tanganyika is the deepest of the African Great Lakes and harbours one of the most diverse fi... more Lake Tanganyika is the deepest of the African Great Lakes and harbours one of the most diverse fish assemblages. While dozens of studies focus on this lake’s cichlids as model organisms, our knowledge about the economically important fish species is still poor. The fishing effort is concentrated mainly in the lake’s pelagic zone with two clupeid (Limnothrissa miodon, Stolothrissa tanganicae) and four latid species (Lates angustifrons, L. mariae, L. microlepis, L. stappersii) as dominant targets. Additionally, cichlid species including members of the tribe Bathybatini can be found as valuable catch on fish markets. As previous research failed to give a clear picture of their lake-wide population structure, we examined the abovementioned host taxa for the presence of monogenean parasites (Platyhelminthes) to explore 1) which parasites infect the dominant fish species in the pelagic zone of Lake Tanganyika, 2) the parasites’ potential as tags to reveal their hosts’ population structure or history and 3) the origin of these freshwater parasites on these clupeid and latid hosts of marine origin. Samples of 14 host species (representatives of Cichlidae, Clupeidae, Latidae) originated from localities throughout Lake Tanganyika including all three subbasins of the lake. Parasite species identification was based on the sclerotised haptoral and genital structures. Intraspecific differences were analysed using morphometrics and geomorphometrics. Molecular characterisation was conducted using a range of nuclear and mitochondrial markers with different rates of molecular evolution. In general, a low parasite host specificity in the lake’s pelagic zone was documented in all examined fish taxa. In total, four monogenean species of three different genera were identified combining morphological and molecular data. While clupeids were infected by typical freshwater monogeneans assigned to a new genus called Kapentagyrus, three of the four latid species were parasitized by a representative of the marine genus Diplectanum. Based on phylogenetic reconstruction, the origin of diplectanids in African freshwaters is probably connected with latids diverging into African and Asian lineages. Parasite population structure inferred from part of the COI gene shows no north-south gradient. However, morphometric variation of Kapentagyrus tanganicanus and shape variation related to geographic origin inferred from geomorphometric analyses of Cichlidogyrus casuarinus, a monogenean infecting bathybatine cichlids, could be a sign of limited host migration. Therefore, the existence of parasite morphotypes related to the geographic origin of the hosts supports the possibility of using monogeneans as tags for population structure. Interestingly, morphological analyses of K. tanganicanus indicated that phenotypic variation also depended on host species. Similarly, our morphometric and geomorphometric analyses on C. casuarinus show some differentiation influenced by host preference. This pattern observed in different monogenean genera is probably caused by phenotypic changes during ontogenetic development because of its independence of genetic population structure. Recent demographic expansion in species infecting clupeid and cichlid hosts was detected and can be linked with paleogeographic events and climate change, respectively.
Monitoring the embryonic development is of fundamental importance for developmental biology. Here... more Monitoring the embryonic development is of fundamental importance for developmental biology. Here we report a successful experimental protocol for immunohistological and immunocytological localization of developmental characters in whole-mount embryos of Macrostomum lignano. Conventional techniques for immunolocalization in flatworm embryos engender the use of sharpened needles or a micro-injection system to punctuate the impermeable eggshell. However, these methods are either time-consuming or requiring a lot of dexterity (puncturing) or expensive (micro-injection system). We illustrate the advantages of this new technique by several examples of immunolocalization in M. lignano and discuss the optimal conditions for the protocol in M. lignano.
Pluripotent stem cells hold great potential for regenerative medicine. Increased replication and ... more Pluripotent stem cells hold great potential for regenerative medicine. Increased replication and division, such is the case during regeneration, concomitantly increases the risk of adverse outcomes through the acquisition of mutations. Seeking for driving mechanisms of such outcomes, we challenged a pluripotent stem cell system during the tightly controlled regeneration process in the planarian Schmidtea mediterranea. Exposure to the genotoxic compound methyl methanesulfonate revealed that despite a similar DNA-damaging effect along the anteroposterior axis of intact animals, stem cell responses differed between anterior and posterior fragments after amputation. Stem cell proliferation and differentiation proceeded successfully in the amputated heads, leading to regeneration of missing tissues. Stem cells in the amputated tails showed decreased proliferation and differentiation capacity. As a result, tails could not regenerate. Interference with the body-axis-associated component β-catenin-1 increased regenerative success in tail fragments by stimulating proliferation at an early time point. Our results suggest that differences in the Wnt-signalling gradient along the body axis modulate stem cell responses to MMS.
Twenty-two marine species of Dalytyphloplanida from Cuba, Panama, and Lanzarote are presented, si... more Twenty-two marine species of Dalytyphloplanida from Cuba, Panama, and Lanzarote are presented, sixteen of which are new to science. Five known species are recorded from Cuba: Kytorhynchus microstylus, Ceratopera paragracilis, Trigonostomum armatum, T. franki, and T. vanmecheleni. Neokytorhynchus pacificus is recorded for the first time in the Atlantic (Lanzarote). For one species, a new genus is erected to be included in a new family. A new genus and thirteen new species from Cuba and three new species from Panama are described. The new species are mainly distinguished from their congeners by the specific morphology of the copulatory structures. The new taxa are discussed in the context of a new phylogenetic analysis of Dalytyphloplanida. This analysis includes sequences of 238 species, 14 of which were sequenced for the first time. The phylogenetic analysis and the detailed morphology suggest that K. microstylus may constitute a complex of cryptic species. The internal phylogenetic...
Not sure of the Publishers copyright policy to archiving your journal articles online? Use these ... more Not sure of the Publishers copyright policy to archiving your journal articles online? Use these sites to find a summary of permissions that are normally given as part of each publisher's copyright transfer agreement. ... Willems, Maxime Lerons, F. Huysentruyt, F. Adriaens, D. Claeys, M. ARTOIS, Tom Borgonie, G. ... [Willems, Maxime; Lerons, F.; Claeys, M.; Borgonie, G.] Univ Ghent, Dept Biol, Nematol Sect, Ghent, Belgium. [Huysentruyt, F.; Adriaens, D.] Univ Ghent, Dept Biol, Grp Evolutionary Morphol Vertebrates, Ghent, Belgium. [Artois, T.] Hasselt Univ, Dept ...
Nanoparticles (NPs) are considered safe for prolonged internalization in cells. During the latest... more Nanoparticles (NPs) are considered safe for prolonged internalization in cells. During the latest years, an increasing amount of studies indicates cytotoxic effects of different nanoparticles (NPs). On the subject of genotoxicity, carcinogenicity and stem-cell-related toxicity, conflicting results are reported. Stem cells are an important target in several applications of NPs, f.e. in stem cell tracking systems, regenerative medicine and anti-cancer drugs... New insights in the toxicity of nanoparticles on stem cells not only address these aspects, they also contribute to our knowledge on defense mechanisms of different tissues. It is generally known that the intrinsic cellular repair capacity varies with the degree of cell potency, an important matter in developmental toxicity as well as in species- or tissue-related plasticity. Schmidtea mediterranea is a small invertebrate with an easy accessible population of totipotent stem cells. This makes it possible to study underlying mechanisms of nanoparticle toxicity on stem cells in vivo, and as such link them to physiological parameters. We focus on the toxicity and biocompatibility of silver NPs (AgNPs) and silica NPs (SiNPs) on stem-cell-specific activities. Both AgNPs and SiNPs are extensively used in biomedical applications, s.a. disinfectants, implants, as drug carriers or in bio-imaging. In our in vivo model system, we observed the uptake of AgNPs in stem cells via transmission electron microscopy. Stem cells responded by a proliferation decrease, measured via histon H3 immunostaining. We are currently looking into the underlying cause of this decrease, as the genotoxic character of this element is still under debate. Effects on cell cycle progression and differentiation were investigated by looking into the expression of the smedwi-1 gene and corresponding protein levels, both exclusively present in stem cells and indicative for different phases of the cell cycle. At the phenotypic level, concentration-dependent behavioral effects, including looper movements and curling, were observed. Exposure to a range of SiNPs concentrations showed no clear phenotypic or proliferation effects. This is a promising result for the further use of SiNPs, but extra research on the uptake and the effects of coating, and the influence of external parameters are needed for both NP types to confirm initial results.
... WIM WILLEMS 1, 2 *, TOM ARTOIS 2, MERLIJN JOCQUÉ 3 and LUC BRENDONCK 3 ... The Marine flora a... more ... WIM WILLEMS 1, 2 *, TOM ARTOIS 2, MERLIJN JOCQUÉ 3 and LUC BRENDONCK 3 ... The Marine flora and fauna of Darwin Harbour, Northern Aus-tralia. Museums and Art Galleries of the NorthernTerri-tory and the Australian Marine Sciences Association, Darwin. ...
Lake Tanganyika is the deepest of the African Great Lakes and harbours one of the most diverse fi... more Lake Tanganyika is the deepest of the African Great Lakes and harbours one of the most diverse fish assemblages. While dozens of studies focus on this lake’s cichlids as model organisms, our knowledge about the economically important fish species is still poor. The fishing effort is concentrated mainly in the lake’s pelagic zone with two clupeid (Limnothrissa miodon, Stolothrissa tanganicae) and four latid species (Lates angustifrons, L. mariae, L. microlepis, L. stappersii) as dominant targets. Additionally, cichlid species including members of the tribe Bathybatini can be found as valuable catch on fish markets. As previous research failed to give a clear picture of their lake-wide population structure, we examined the abovementioned host taxa for the presence of monogenean parasites (Platyhelminthes) to explore 1) which parasites infect the dominant fish species in the pelagic zone of Lake Tanganyika, 2) the parasites’ potential as tags to reveal their hosts’ population structure or history and 3) the origin of these freshwater parasites on these clupeid and latid hosts of marine origin. Samples of 14 host species (representatives of Cichlidae, Clupeidae, Latidae) originated from localities throughout Lake Tanganyika including all three subbasins of the lake. Parasite species identification was based on the sclerotised haptoral and genital structures. Intraspecific differences were analysed using morphometrics and geomorphometrics. Molecular characterisation was conducted using a range of nuclear and mitochondrial markers with different rates of molecular evolution. In general, a low parasite host specificity in the lake’s pelagic zone was documented in all examined fish taxa. In total, four monogenean species of three different genera were identified combining morphological and molecular data. While clupeids were infected by typical freshwater monogeneans assigned to a new genus called Kapentagyrus, three of the four latid species were parasitized by a representative of the marine genus Diplectanum. Based on phylogenetic reconstruction, the origin of diplectanids in African freshwaters is probably connected with latids diverging into African and Asian lineages. Parasite population structure inferred from part of the COI gene shows no north-south gradient. However, morphometric variation of Kapentagyrus tanganicanus and shape variation related to geographic origin inferred from geomorphometric analyses of Cichlidogyrus casuarinus, a monogenean infecting bathybatine cichlids, could be a sign of limited host migration. Therefore, the existence of parasite morphotypes related to the geographic origin of the hosts supports the possibility of using monogeneans as tags for population structure. Interestingly, morphological analyses of K. tanganicanus indicated that phenotypic variation also depended on host species. Similarly, our morphometric and geomorphometric analyses on C. casuarinus show some differentiation influenced by host preference. This pattern observed in different monogenean genera is probably caused by phenotypic changes during ontogenetic development because of its independence of genetic population structure. Recent demographic expansion in species infecting clupeid and cichlid hosts was detected and can be linked with paleogeographic events and climate change, respectively.
Monitoring the embryonic development is of fundamental importance for developmental biology. Here... more Monitoring the embryonic development is of fundamental importance for developmental biology. Here we report a successful experimental protocol for immunohistological and immunocytological localization of developmental characters in whole-mount embryos of Macrostomum lignano. Conventional techniques for immunolocalization in flatworm embryos engender the use of sharpened needles or a micro-injection system to punctuate the impermeable eggshell. However, these methods are either time-consuming or requiring a lot of dexterity (puncturing) or expensive (micro-injection system). We illustrate the advantages of this new technique by several examples of immunolocalization in M. lignano and discuss the optimal conditions for the protocol in M. lignano.
Pluripotent stem cells hold great potential for regenerative medicine. Increased replication and ... more Pluripotent stem cells hold great potential for regenerative medicine. Increased replication and division, such is the case during regeneration, concomitantly increases the risk of adverse outcomes through the acquisition of mutations. Seeking for driving mechanisms of such outcomes, we challenged a pluripotent stem cell system during the tightly controlled regeneration process in the planarian Schmidtea mediterranea. Exposure to the genotoxic compound methyl methanesulfonate revealed that despite a similar DNA-damaging effect along the anteroposterior axis of intact animals, stem cell responses differed between anterior and posterior fragments after amputation. Stem cell proliferation and differentiation proceeded successfully in the amputated heads, leading to regeneration of missing tissues. Stem cells in the amputated tails showed decreased proliferation and differentiation capacity. As a result, tails could not regenerate. Interference with the body-axis-associated component β-catenin-1 increased regenerative success in tail fragments by stimulating proliferation at an early time point. Our results suggest that differences in the Wnt-signalling gradient along the body axis modulate stem cell responses to MMS.
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