@article {183, title = {Embryonic cell lineage of the marine nematode Pellioditis marina}, journal = {Developmental BiologyDevelopmental Biology}, volume = {258}, number = {1}, year = {2003}, note = {Houthoofd, W Jacobsen, K Mertens, C Vangestel, S Coomans, A Borgonie, G}, month = {Jun}, pages = {57-69}, abstract = {We describe the complete embryonic cell lineage of the marine nematode Pellioditis marina (Rhabditidae) up to somatic muscle contraction, resulting in the formation of 638 cells, of which 67 undergo programmed cell death. In comparison with Caenorhabditis elegans, the overall lineage homology is 95.5\%; fate homology, however, is only 76.4\%. The majority of the differences in fate homology concern nervous, epidermal, and pharyngeal tissues. Gut and, remarkably, somatic muscle is highly conserved in number and position. Partial lineage data from the slower developing Halicephalobus sp. (Panagrolaimidae) reveal a lineage largely, but not exclusively, built up of monoclonal sublineage blocs with identical fates, unlike the polyclonal fate distribution in C elegans and P. marina. The fate distribution pattern in a cell lineage could be a compromise between minimizing the number of specification events by monoclonal specification and minimizing the need for migrations by forming the cells close at their final position. The latter could contribute to a faster embryonic development. These results reveal that there is more than one way to build a nematode. (C) 2003 Elsevier Science (USA). All rights reserved.}, isbn = {0012-1606}, author = {Houthoofd, W. and Jacobsen, K. and Mertens, C. and Vangestel, S. and Coomans, A. and Borgonie, G.} } @article {149, title = {The somatic female gonad of Cephalobidae (Nematoda): cellular architecture and associated function}, journal = {NematologyNematology}, volume = {9}, year = {2007}, note = {Times Cited: 0 Article English Bert, W Univ Ghent, Dept Biol, Nematol Unit, Ledeganckstr 35, B-9000 Ghent, Belgium Cited References Count: 46 197FO BRILL ACADEMIC PUBLISHERS PLANTIJNSTRAAT 2, P O BOX 9000, 2300 PA LEIDEN, NETHERLANDS LEIDEN Part 2}, pages = {285-297}, abstract = {The female reproductive system of the free-living nematode family Cephalobidae is examined by means of differential interference contrast, scanning electron and fluorescent microscopy. The model nematode Caenorhabditis elegans and the predatory nematode Prionchulus punctatus are also included in this study; the former mainly to test our results with the very detailed knowledge of this model organism, the latter to provide a representative of the more distantly related Enoplea. In this comparative approach, the analysed gonad structures are discussed with respect to their functional and phylogenetic significance. The general cellular composition of the cephalobid gonad - namely an oviduct comprising two rows of four cells, a distinctly offset spermatheca consisting of 8-16 cells, and a uterus composed of distinct cell rows - differs from all known Nematoda except that of the plant-parasitic Tylenchomorpha. Despite the striking evolutionary conservation of the cellular architecture of the cephalobid gonad there is a complex subcellular specialisation, namely a significant and functionally relevant variation in myofilament organisation, both among Cephalobidae and between major groups of nematodes. We demonstrate the presence of microfilaments that vary in pattern among species and that may play an important role in egg propulsion. The phenomenon of endotokia matricida, in which eggs do not leave the female body, is found to be associated with a massive rupture of the cytoskeleton in the uterus wall. The complexity of the myofibril structure and the associated potential to propagate oocytes actively cannot be solely explained by differences in phylogenetic history, but is also linked to body diameter. In the larger Acrobeloides maximus, the proximal end of the ovary sheath is adorned with 12 distinct longitudinal bands, antibody binding positively for paramyosin, while in the smaller Cephalobus cubaensis myofilament organisation is at random}, keywords = {Acrobeloides, Caenorhabditis, Caenorhabditis elegans, caenorhabditis-elegans, CALIFORNIA, CELLS, CEPHALOBIDAE, Cephalobus, Chiloplacus, cytoskeleton, Evolution, FAMILY, gonad, gonoduct, HERMAPHRODITE, LINEAGES, microscopy, MODEL, Nematoda, NEMATODE, nematodes, paramyosin, PHYLOGENETIC SIGNIFICANCE, Prionchulus, propulsion, REDESCRIPTION, REPRODUCTIVE-SYSTEM, SPERMATHECA, THORNE, TYLENCHIDA, Zeldia}, isbn = {1388-5545}, author = {Bert, W. and Vangestel, S. and Houthoofd, W. and Van Gansbeke, R. and Borgonie, G.} } @article {153, title = {Different roads to form the same gut in nematodes}, journal = {Evolution \& DevelopmentEvolution \& Development}, volume = {8}, number = {4}, year = {2006}, note = {Times Cited: 1 Article English Borgonie, G Univ Ghent, Dept Biol, KL Ledeganckstr 35, B-9000 Ghent, Belgium Cited References Count: 40 058HC BLACKWELL PUBLISHING 9600 GARSINGTON RD, OXFORD OX4 2DQ, OXON, ENGLAND OXFORD}, pages = {362-369}, abstract = {The morphogenesis of a gut from the endoderm has been well studied among the animal kingdom and is also well described in the nematode Caenorhabditis elegans. But are there other ways to build a nematode intestine? Sulston et al. (1983) described a different intestinal cell lineage in the species Panagrellus redivivus and Turbatrix aceti that includes two programmed cell deaths. However, no details are known about the three-dimensional (3D) configuration and the role of the cell deaths. Here, we describe the intestinal morphogenesis of P. redivivus and five other nematode species by means of four-dimensional microscopy, which gives us a 3D representation of gut formation at the cellular level. The morphological pathway of gut formation is highly conserved among these distantly related species. However, we found the P. redivivus pattern in another related species Halicephalobus gingivalis. In this pattern, the intestinal precursors migrate inward in concert with the mesoderm precursors. Based on the observations, we propose a hypothesis that could explain the differences. The positions of the mesoderm precursors create a possible spatial constraint, by which the establishment of bilateral symmetry in the intestine is delayed. This symmetry is corrected by cell migrations; other cells are eliminated and compensated by supplementary cell divisions. This pattern leads to the same result as in the other nematodes: a bilateral symmetrical intestine with nine rings. This illustrates how conserved body plans can be achieved by different developmental mechanisms}, keywords = {C-ELEGANS, Caenorhabditis, Caenorhabditis elegans, caenorhabditis-elegans, CELLS, EMBRYOGENESIS, EMBRYONIC-CELL LINEAGE, Evolution, FATE, INDUCTION, microscopy, MODEL, NEMATODE, nematodes, SPECIFICATION}, isbn = {1520-541X}, author = {Houthoofd, W. and Willems, M. and Vangestel, S. and Mertens, C. and Bert, W. and Borgonie, G.} } @article {158, title = {Evolutionary loss of parasitism by nematodes? Discovery of a free-living filaroid nematode}, journal = {Journal of ParasitologyJournal of Parasitology}, volume = {92}, number = {3}, year = {2006}, note = {Times Cited: 2 Article English Bert, W Univ Ghent, Dept Biol, Ledeganckstr 35, B-9000 Ghent, Belgium Cited References Count: 15 065CD AMER SOC PARASITOLOGISTS 810 EAST 10TH STREET, LAWRENCE, KS 66044 USA LAWRENCE}, pages = {645-647}, abstract = {A cattle-drinking pool in nature reserve "Zwin" on the Belgian coast contained free-living third-stage infective filaroid juveniles. These juveniles clearly differ morphologically from all known nematodes. Morphological and molecular analyses indicate a position within the Filaroidea. The aberrant biology of this nematode, namely. a free-living stage in ail aquatic environment. is unknown within this superfamily. and the evolution of the parasitic phenotype to a free-living state is generally thought to be unlikely. However, the obtained placement in the small subunit molecular phylogenetic tree suggests that this free-living stage is most likely a secondary adaptation. It is reasonable to assert that nematodes with complex life cycles still have the genetic potential for a reversion from parasitism to a (partial) free-living stage}, keywords = {Evolution, NEMATODE, nematodes, pool, SEQUENCE}, isbn = {0022-3395}, author = {Bert, W. and Messiaen, M. and Manhout, J. and Houthoofd, W. and Borgonie, G.} } @article {163, title = {Unusual intestinal lamellae in the nematode Rhabditophanes sp KR3021 (Nematoda : Alloinematidae)}, journal = {Journal of MorphologyJournal of Morphology}, volume = {264}, number = {2}, year = {2005}, note = {Willems, M Houthoofd, W Claeys, M Couvreur, M Van Driessche, R Adriaens, D Jacobsen, K Borgonie, G}, month = {May}, pages = {223-232}, abstract = {The free-living nematode Rhabditophanes sp. has recently been placed in a clade of animal parasites and may be a unique example of a reversal to a nonparasitic lifestyle. Detailed morphological analysis of the intestine reveals the unusual and unique structure of splitting microlamellae forming a meshwork with cavities along the entire intestinal tract. Secretion vesicles were observed along the whole tract and along the length of the lamellae. It is suggested that these lamellae are adaptations to a different digestive strategy where low food availability and a low absorption surface are compensated for by maximizing the nutrient uptake efficiency along the entire length of the intestine. The likely reversal to a free-living life cycle may have caused drastic changes in diet, providing the necessary driving forces to such morphological changes. (c) 2005 Wiley-Liss, Inc.}, isbn = {0362-2525}, author = {Willems, M. and Houthoofd, W. and Claeys, M. and Couvreur, M. and Van Driessche, R. and Adriaens, D. and Jacobsen, K. and Borgonie, G.} } @article {144, title = {The embryonic cell lineage of the nematode Halicephalobus gingivalis (Nematoda : Cephalobina : Panagrolaimoidea)}, journal = {NematologyNematology}, volume = {9}, year = {2007}, note = {Houthoofd, Wouter Borgonie, GaetanPart 4}, pages = {573-584}, abstract = {This paper describes the nearly complete embryonic cell lineage of the terrestrial nematode, Halicephalobus gingivalis, up to somatic muscle contraction, resulting in the formation of 536 cells, of which 24 undergo programmed cell death. Halicephalobus gingivalis has a 94\% lineage homology with both Caenorhabditis elegans and Pellioditis marina, and a fate homology of only 86\% and 78\%, respectively. Although H. gingivalis belongs to a different superfamily than C. elegans and P marina, its cell lineage is remarkably consistent with them. Variations in the fate distribution of cells among the different species were only observed at the end of the cell lineage. The data presented here show that the polyclonal cell specification is much more widespread in clades 9 and 10 and is not a highly derived trait that is specifically linked to the fast development of the model organism C. elegans.}, isbn = {1388-5545}, author = {Houthoofd, W. and Borgonie, G.} } @article {117, title = {Analysis of the translationally controlled tumour protein in the nematodes Ostertagia ostertagi and Caenorhabditis elegans suggests a pivotal role in egg production}, journal = {International Journal for ParasitologyInternational Journal for Parasitology}, volume = {39}, number = {11}, year = {2009}, note = {Meyvis, Yves Houthoofd, Wouter Visser, Aline Borgonie, Gaetan Gevaert, Kris Vercruysse, Jozef Claerebout, Edwin Geldhof, Peter}, month = {Sep}, pages = {1205-1213}, abstract = {The translationally controlled tumour protein (TCTP) is a conserved protein which has been described for a wide range of eukaryotic organisms including protozoa, yeasts, plants, nematodes and mammals. Several parasitic organisms have been shown to actively secrete TCTP during host infection as part of their immuno-evasive strategy. In this study, we have studied TCTP in Ostertagia ostertagi, a parasitic nematode of cattle, and in the free-living nematode Caenorhabditis elegans. An analysis of the transcription and expression patterns showed that TCTP was present in the eggs of both species. This localisation is consistent for some other Strongylida such as Teladorsagia circumcincta, Cooperia oncophora and Haemonchus contortus. TCTP was also detected at low levels in excretory-secretory material from adult O. ostertagi worms. The role of TCTP in nematode biology was also investigated by RNA interference in C elegans. Knock-down of C elegans tctp (tct-1) transcription reduced the numbers of eggs laid by the hermaphrodite in the F(0) and F(1) generations by 90\% and 72\%, respectively, indicating a pivotal role of TCTP in reproduction. (C) 2009 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.}, isbn = {0020-7519}, author = {Meyvis, Y. and Houthoofd, W. and Visser, A. and Borgonie, G. and Gevaert, K. and Vercruysse, J. and Claerebout, E. and Geldhof, P.} } @article {132, title = {Assessment of the configuration of the posterior cells of the nematode embryo as potential phylogenetic marker}, journal = {Russian Journal of NematologyRussian Journal of Nematology}, volume = {16}, number = {2}, year = {2008}, note = {Times Cited: 0 Article English Vangestel, S Univ Ghent, Dept Biol, Nematol Sect, KL Ledeganckstr 35, B-9000 Ghent, Belgium Cited References Count: 55 383BP MYLNEFIELD RESEARCH SERVICES INVERGOWRIE, DUNDEE DD2 5DA, SCOTLAND DUNDEE}, pages = {107-120}, abstract = {We have reconstructed the evolutionary history of an early developmental character by mapping the configuration of the posterior cells in the early embryo onto the SSU-based molecular phylogeny of Holterman (2006). We have analyzed the early embryonic development of 19 species, complemented with 20 species from the literature, covering representatives in each clade. We show that the Caenorhabditis elegans configuration, found in most species in clade III-X, is the ancestral state for these clades. alternative configurations arose inependently in clade IX, (Diploscapter coronatus), X (Halicephalobus gingivalis), XI (all investigated species) and XII (Meloidogyne incognita). A variable configuration of the posterior cells arose at least twice independently during nematode evolution, once in clade IX (D. coronatus) and once in an ancestor, shared by clade XI and XII and thus can be used as a phylogenetic marker to delineate these clades. Statistical tests based on our data-set show that the presence of a variable configuration is related to developmental tempo and egg shape}, keywords = {Belgium, C-ELEGANS EMBRYOS, Caenorhabditis, Caenorhabditis elegans, caenorhabditis-elegans, CELLS, CLEAVAGE, EARLY EMBRYOGENESIS, embryology, ENOPLIDA, Evolution, GUT, LINEAGE, MELOIDOGYNE, MOLECULAR PHYLOGENY, Nematoda, NEMATODE, phylogenetic marker, PHYLOGENIES, phylogeny, spatial configuration, SPECIFICATION}, isbn = {0869-6918}, author = {Vangestel, S. and Houthoofd, W. and Bert, W. and Vanholme, B. and Calderon-Urrea, A. and Willems, M. and Artois, T. and Borgonie, G.} } @article {133, title = {The early embryonic development of the satellite organism Pristionchus pacificus: differences and similarities with Caenorhabditis elegans}, journal = {NematologyNematology}, volume = {10}, year = {2008}, note = {Times Cited: 1 Article English Borgonie, G Univ Ghent, Dept Biol, Nematol Sect, KL Ledeganckstr 35, B-9000 Ghent, Belgium Cited References Count: 47 293NC BRILL ACADEMIC PUBLISHERS PLANTIJNSTRAAT 2, P O BOX 9000, 2300 PA LEIDEN, NETHERLANDS LEIDEN Part 3}, pages = {301-312}, abstract = {As a comparative counterpart for the model organism Caenorhabditis elegans, the nematode Pristionchus pacificus was established as a satellite organism to study developmental processes. However, these studies mainly focused on post-embryonic development and little is known about the early embryonic development. Using 4D microscopy we reconstructed the early embryonic cell lineage of 12 individuals of P. pacificus. By analysing several parameters of early development, including the division sequence, the spatial arrangement of blastomeres, the cell cycle patterns of the AB lineage and cell-cell contacts in different cell stages of the embryo, it was shown that the early embryonic development is nearly identical to C. elegans. Known cell-cell contacts necessary for induction of blastomere fates in C. elegans are also present in P pacificus. Thus, the spatio-temporal conditions that would allow possible homologous inductions are present. However, at least one model for blastomere specification seems not to apply to P pacificus since the third division in the AB lineage differs from that of C elegans. Furthermore, naturally occurring variability of early development was demonstrated, which is clearly permitted since there seems to be no influence on further development into an adult worm}, keywords = {4D microscopy, Belgium, C-ELEGANS, Caenorhabditis, Caenorhabditis elegans, caenorhabditis-elegans, cell lineage, CELL-CELL INTERACTIONS, development, EARLY EMBRYOGENESIS, EMBRYOGENESIS, Evolution, FATE, INDUCTION, LINEAGE, microscopy, MODEL, NEMATODE, neodiplogastridae, PATTERN-FORMATION, PHYLOGENETIC IMPLICATIONS, SEQUENCE, SPECIFICATION, VULVA DEVELOPMENT}, isbn = {1388-5545}, author = {Vangestel, S. and Houthoofd, W. and Bert, W. and Borgonie, G.} } @article {136, title = {The embryonic cell lineage of the nematode Rhabditophanes sp}, journal = {International Journal of Developmental BiologyInternational Journal of Developmental Biology}, volume = {52}, number = {7}, year = {2008}, note = {Houthoofd, Wouter Willems, Maxime Jacobsen, Kim Coomans, August Borgonie, Gaetan}, pages = {963-967}, abstract = {One of the unique features of the model organism Caenorhabditis elegans is its invariant development, where a stereotyped cell lineage generates a fixed number of cells with a fixed cell type. It remains unclear how embryonic development evolved within the nematodes to give rise to the complex, invariant cell lineage of C. elegans. Therefore, we determined the embryonic cell lineage of the nematode, Rhabditophanes sp. (family Alloionematidae) and made detailed cell-by-cell comparison with the known cell lineages of C. elegans, Pellioditis marina and Halicephalobus gingivalis. This gave us a unique data set of four embryonic cell lineages, which allowed a detailed comparison between these cell lineages at the level of each individual cell. This lineage comparison revealed a similar complex polyclonal fate distribution in all four nematode species (85\% of the cells have the same fate). It is striking that there is a conservation of a {\textquoteright}C. elegans{\textquoteright} like polyclonal cell lineage with strong left-right asymmetry. We propose that an early symmetry-breaking event in nematodes of clade IV-V is a major developmental constraint which shapes their asymmetric cell lineage.}, isbn = {0214-6282}, author = {Houthoofd, W. and Willems, M. and Jacobsen, K. and Coomans, A. and Borgonie, G.} } @article {79, title = {Lack of metabolic ageing in the long-lived flatworm Schmidtea polychroa}, journal = {Experimental GerontologyExperimental Gerontology}, volume = {46}, number = {9}, year = {2011}, note = {Mouton, Stijn Willems, Maxime Houthoofd, Wouter Bert, Wim Braeckman, Bart P.}, month = {Sep}, pages = {755-761}, abstract = {Freshwater planarians have a large totipotent stem cell population allowing high rates of cell renewal and morphological plasticity. It is often suggested that they are able to rejuvenate during fission, regeneration and starvation. These features, together with the rapidly expanding molecular toolset, make planarians such as Schmidtea polychroa and S. mediterranea interesting for ageing research. Yet, the basic demographic and physiological data are lacking or still based on fragmentary observations of one century ago. Here, we present the first longitudinal physiological study of the species S. polychroa. Survival, size and metabolic rate, measured by microcalorimetry, of a cohort of 28 individuals were followed over a period of three years. Sexual maturity was reached during the second month after which the worms continued growing up to 5 months. This initial growth phase was followed by alternating periods of synchronised growth and degrowth. Although mass-specific metabolic rates declined during the initial growth phase, no changes were found later in life. The absence of metabolic ageing may be explained by the very high rate of cell renewal during homeostasis and alternating phases of degrowth and growth during which tissues are renewed. Surprisingly, all deaths occurred in pairs of worms that were housed in the same culture recipient, suggesting that worms did not die from ageing. Taking into account the metabolic and demographic data, we suggest that S. polychroa shows negligible ageing. Detailed analyses of size and metabolic rate revealed a remarkable biphasic allometric scaling relation. During the initial growth phase (months 1-5) the allometric scaling exponent b was 0.86 while later in life, it increased to an unusually large value of 1.17, indicating that mass-specific metabolic rate increases with size in adult S. polychroa. (C) 2011 Elsevier Inc. All rights reserved.}, isbn = {0531-5565}, author = {Mouton, S. and Willems, M. and Houthoofd, W. and Bert, W. and Braeckman, B. P.} } @article {83, title = {First record of Nemertodermatida from Belgian marine waters}, journal = {Belgian Journal of ZoologyBelgian Journal of Zoology}, volume = {141}, number = {1}, year = {2011}, pages = {50-54}, author = {Boone, M. and Houthoofd, W. and Bert, W. and Artois, T.} } @article {84, title = {Spermatogenesis and the structure of the testes in Nemertodermatida}, journal = {ZoomorphologyZoomorphology}, volume = {130}, number = {4}, year = {2011}, note = {Boone, Mieke Bert, Wim Claeys, Myriam Houthoofd, Wouter Artois, Tom}, month = {Dec}, pages = {273-282}, abstract = {The ultrastructure of the testes in two representatives of the enigmatic taxon Nemertodermatida was studied using transmission electron microscopy. Nemertoderma westbladi has paired testes, which are delineated by lining cells. Within each testis, different follicles, each surrounded by a membrane-like structure, are found. Flagellophora apelti has genuinely follicular testes, consisting of several follicles, each containing a certain stage of spermatogenesis. As the gametes are not enclosed by a structure that can be called a true gonad, the structure of the testes differs from most bilaterian animals, but resembles the organization of gametogenic areas of ctenophores. Each stage of spermatogenesis in F. apelti is described, enabling the inference of the origin of the structures seen in mature spermatozoa. The overall structure of the mature spermatozoa is similar in all nemertodermatids and unique within the Metazoa: an elongated head containing the nucleus; a middle piece containing an axoneme, mitochondrial derivatives and in F. apelti granular derivatives; and a flagellar tail.}, isbn = {0720-213X}, author = {Boone, M. and Bert, W. and Claeys, M. and Houthoofd, W. and Artois, T.} } @article {86, title = {Distribution of proliferating cells and vasa-positive cells in the embryo of Macrostomum lignano (Rhabditophora, Platyhelminthes)}, journal = {Belgian Journal of ZoologyBelgian Journal of Zoology}, volume = {140}, year = {2010}, note = {Willems, Maxime Couvreur, Marjolein Boone, Mieke Houthoofd, Wouter Artois, Tom11th International Symposium on Flatworm BiologyJul 26-31, 2009Diepenbeek, BELGIUMS}, month = {Jul}, pages = {149-153}, abstract = {The neoblast stem cell system of flatworms is considered to be unique within the animal kingdom. How this stem cell system arises during embryonic development is intriguing. Therefore we performed bromodeoxyuridine labelling on late stage embryos of Macrostomum lignano to assess when the pattern of proliferating cells within the embryo is comparable to that of hatchlings. This pattern can be found in late embryonic stages ( stage 8). We also used the freeze cracking method to perform macvasa embryonic labelling. Macvasa is a somatic and germ line stem cell marker. We showed macvasa protein distribution during the whole embryonic development. In the macvasa-positive blastomeres the protein is localized around the nucleus in the putative chromatoid bodies. However, at a specific embryonic stage, it is also ubiquitously present in the cytoplasm of some blastomeres. We compare our data with what is known from Schmidtea polychroa of the expression of the vasa-like gene SpolvlgA and the protein distribution of the chromatoid body component Spoltud-1. The embryonic origin of the somatic stem cell system and the germ line is discussed.}, isbn = {0777-6276}, author = {Willems, M. and Couvreur, M. and Boone, M. and Houthoofd, W. and Artois, T.} } @article {93, title = {Establishing a flatworm ageing model}, journal = {Belgian Journal of ZoologyBelgian Journal of Zoology}, volume = {140}, year = {2010}, note = {Mouton, Stijn Verdoodt, Freija Willems, Maxime Dhondt, Ineke Crucke, Jeroen Braeckman, Bart P. Houthoofd, WouterS}, month = {Jul}, pages = {195-197}, isbn = {0777-6276}, author = {Mouton, S. and Verdoodt, F. and Willems, M. and Dhondt, I. and Crucke, J. and Braeckman, B. P. and Houthoofd, W.} } @article {102, title = {Refuge From Predation, the Benefit of Living in an Extreme Acidic Environment?}, journal = {Biological BulletinBiological Bulletin}, volume = {219}, number = {3}, year = {2010}, note = {Borgonie, Gaetan Dierick, Manuel Houthoofd, Wouter Willems, Maxime Jacobs, Patric Bert, Wim}, month = {Dec}, pages = {268-276}, abstract = {Organisms living in extreme habitats require costly adaptations to cope with these conditions. Among the suggested potential benefits that trade off these costs is refuge from predation. To study these interactions in extreme environments, samples were taken in the cave Cueva de Villa Luz, Tabasco, Mexico, where more than 32 subterranean springs, some H,S rich, rise from the floor. Hydrogen sulfide gas plus oxygen is absorbed by freshwater, and oxidation forms concentrated sulfuric acid. Snottites, whitish hollow mucous tubes, hang from the ceiling of the cave. Fluid drops from these snottites were recorded as having pH values of 0-3. We report the discovery of a new species of nematode that thrives in the highly acidic environment of the snottite. Micro CT scan of snottites reveals a complex interaction between the acidic snottite, nematodes, and abundant nematode-eating mites. The nematode adaptation to low pH probably protects them against mite predation, for which nematodes are most likely the most important source of carbon in this sulfur-driven ecosystem.}, isbn = {0006-3185}, author = {Borgonie, G. and Dierick, M. and Houthoofd, W. and Willems, M. and Jacobs, P. and Bert, W.} } @article {103, title = {Morphological, morphometrical and molecular characterisation of Filenchus fungivorus n. sp., a fungivorous nematode from Japan in a most likely polyphyletic genus (Nematoda: Tylenchina)}, journal = {NematologyNematology}, volume = {12}, year = {2010}, note = {Bert, Wim Okada, Hiroaki Tavernier, Ines Borgonie, Gaetan Houthoofd, WouterPart 2}, pages = {235-246}, abstract = {Filenchus fungivorus n. sp., isolated from autumn bellflower (Gentiana scrabra Bunge) in Japan and maintained on a fungus culture, is described based on LM, SEM and molecular data. The new species is characterised by combination of the following features: two lateral lines, short body (284-331 mu m), short stylet (7.0-8.7 mu m), amphid aperture associated with characteristic depression, short ovary, undifferentiated spermatheca, post-vulval sac shorter than corresponding body diam. and short (59-80 mu m) nonfiliform, almost straight tail and absence of males. According to a principal component analysis, a small tail/ vulva-anus (1.3-1.8) and V{\textquoteright} ratio have the highest morphometrical power to separate F. fungivorus n. sp. from the remaining analysed Filenchus spp. (with the exception of F. misellus). Molecular analyses based on SSU rDNA placed F. fungivorus n. sp. within a clade that contained Filenchus sp. (heathland, Belgium), F. (Ottolenchus) discrepans, Malenchus andrassyi and F. misellus. However, the position of this clade could not be resolved within the Tylenchomorpha. Although the phylogenetic analyses, confirmed by Shimodaira-Hasegawa tests, significantly rejected the monophyly of Filenchus (P < 0.001), F. fungivorus n. sp. is placed within Filenchus in anticipation of a review of the Tylenchidae.}, isbn = {1388-5545}, author = {Bert, W. and Okada, H. and Tavernier, I. and Borgonie, G. and Houthoofd, W.} } @article {108, title = {Embryonic origins of hull cells in the flatworm Macrostomum lignano through cell lineage analysis: developmental and phylogenetic implications}, journal = {Development Genes and EvolutionDevelopment Genes and Evolution}, volume = {219}, number = {8}, year = {2009}, note = {Willems, Maxime Egger, Bernhard Wolff, Carsten Mouton, Stijn Houthoofd, Wouter Fonderie, Pamela Couvreur, Marjolein Artois, Tom Borgonie, Gaetan}, month = {Aug}, pages = {409-417}, abstract = {The development of macrostomid flatworms is of interest for evolutionary developmental biology research because these taxa combine characteristics of the canonical spiral cleavage pattern with significant deviations from this pattern. One such deviation is the formation of hull cells, which surround the remaining embryonic primordium during early development. Using live observations with a 4D microscope system, histology, and 3D reconstructions, we analyzed the ontogeny of these hull cells in the macrostomid model organism Macrostomum lignano. Our cell lineage analysis allowed us to find the precursors of the hull cells in this species. We discuss the relation between macrostomid development and the development of other spiralians and the question of whether hull cells are homologous within rhabditophoran flatworms.}, isbn = {0949-944X}, author = {Willems, M. and Egger, B. and Wolff, C. and Mouton, S. and Houthoofd, W. and Fonderie, P. and Couvreur, M. and Artois, T. and Borgonie, G.} } @article {67, title = {Anthelmintic tolerance in free-living and facultative parasitic isolates of Halicephalobus (Panagrolaimidae)}, journal = {ParasitologyParasitology}, volume = {139}, number = {10}, year = {2012}, note = {Fonderie, P. Bert, W. Hendrickx, F. Houthoofd, W. Moens, T.}, month = {Sep}, pages = {1301-1308}, abstract = {Studies on anthelmintic resistance in equine parasites do not include facultative parasites. Halicephalobus gingivalis is a free-living bacterivorous nematode and a known facultative parasite of horses with a strong indication of some form of tolerance to common anthelmintic drugs. This research presents the results of an in vitro study on the anthelmintic tolerance of several isolates of Halicephalobus to thiabendazole and ivermectin using an adaptation of the Micro-Agar Larval Development Test hereby focusing on egg hatching and larval development. Panagrellus redivivus and Panagrolaimus superbus were included as a positive control. The results generally show that the anthelmintic tolerance of Halicephalobus to both thiabendazole and ivermectin was considerably higher than that of the closely related Panagrolaimidae and, compared to other studies, than that of obligatory equine parasites. Our results further reveal a remarkable trend of increasing tolerance from fully free-living isolates towards horse-associated isolates. In vitro anthelmintic testing with free-living and facultative parasitic nematodes offers the advantage of observing drug effect on the complete life cycle as opposed to obligatory parasites that can only be followed until the third larval stage. We therefore propose Halicephalobus gingivalis as an experimental tool to deepen our understanding of the biology of anthelmintic tolerance.}, isbn = {0031-1820}, author = {Fonderie, P. and Bert, W. and Hendrickx, F. and Houthoofd, W. and Moens, T.} } @article {72, title = {Mature spermatozoa of Brevibucca sp (Nematoda: Rhabditida: Brevibuccidae)}, journal = {Russian Journal of NematologyRussian Journal of NematologyRussian Journal of Nematology}, volume = {19}, number = {2}, year = {2011}, note = {ISI Document Delivery No.: 895YZTimes Cited: 0Cited Reference Count: 30Yushin, Vladimir V. Claeys, Myriam Houthoofd, WouterEUMAINE [RFBR 11-04-00368, RFBR 11-04-98555, FEB RAS 09-III-A-06-216]; RF government [2010-220-01-180]This research was supported in part by EUMAINE; RFBR 11-04-00368; RFBR 11-04-98555; FEB RAS 09-III-A-06-216 and RF government grant 2010-220-01-180. The authors are grateful to D.V. Fomin (Institute of Marine Biology, Vladivostok) for technical assistance.Russian acad sci, inst parasitologyMoscow}, pages = {131-138}, type = {Article}, abstract = {Mature spermatozoa found in the female gonoduct of the nematode Brevibucca sp. (Brevibuccidae, Rhabditida) were studied with transmission electron microscopy. As in other nematodes, the spermatozoa in Brevibucca sp. represent an aberrant type of male gametes characterised by the absence of an axoneme and an acrosome. Mature spermatozoa of Brevibucca sp. are amoeboid bipolar cells Ca 4-4.5 mu m diam.; each cell is subdivided into a main cell body and a pseudopod devoid of organelles. The main cell body includes a condensed nucleus, many mitochondria and so-called {\textquoteright}membranous organelles{\textquoteright} (MO). These unique organelles are characteristic of developing, as well as of mature, spermatozoa of many nematodes. The MO in Brevibucca sp. sperm resemble large (ca 0.5 diam.) vesicles with transparent content and a system of internal finger-like projections of the outer membrane. Each MO is joined to the plasmalemma of the main cell body and is open to the intercellular exterior via a pore. Each spermatozoon has a prominent pseudopod filled with the filamentous components of the cytoskeleton. The structure and development of the rhabditid (order Rhabditida apud De Ley \& Blaxter, 2002) sperm is somewhat conserved throughout the order. That is, the general pattern of spermatozoon recognized as "rhabditid" in Brevibucca sp. is similarly expressed in Spiruromorpha, Ascaridomorpha, Panagrolaimomorpha, Tylenchomorpha and Rhabditomorpha. Thus, such conservation lacks phylogenetic pointers at the scale of order. The spermatozoa of the rhabditid pattern observed also in Brevibucca sp. may be considered as an ancestral or symplesiomorphic character for several clades of the order Rhabditida.}, keywords = {caenorhabditis-elegans, dimorphism, female gonoduct, fibrous bodies, filarioidea, membranous organelles, mitochondria, phylogenetic-relationships, phylogeny, pseudopod, sperm development, spermatogenesis, sphaerularioidea, steinernematidae, tylenchomorpha, ultrastructure}, isbn = {0869-6918}, author = {Yushin, V. V. and Claeys, M. and Houthoofd, W.} } @article {75, title = {Mononchoides composticola n. sp. (Nematoda: Diplogastridae) associated with composting processes: morphological, molecular and autecological characterisation}, journal = {NematologyNematology}, volume = {13}, year = {2011}, note = {Steel, Hanne Moens, Tom Scholaert, Annelies Boshoff, Magdalena Houthoofd, Wouter Bert, WimPart 3}, pages = {347-363}, abstract = {Mononchoides composticola n. sp. was isolated from compost and is described based on light and scanning electron microscopy, supplemented with SSU rDNA sequence data. It is characterised by the following features: a denticulate ridge in addition to the dorsal claw-like tooth, a small tooth-like swelling at the stegostom base, ca 26 longitudinal ridges on the female body, a uterine sac associated with two dumb-bell-shaped pouches, relatively small spicules (30-38 mu m long), a simple gubernaculum shorter than half the spicule length, the genital subventral papillae (v6) consisting of three very small papillae, and a long filiform tail (female: 391-550 mu m, 18-26 anal body diam.; male: 304-548 mu m, 19-30 anal body diam.). Phylogenetic analyses placed the new species together with M. striatus, sister to Tylopharynr foetida. Since the use of nematodes as functional indicators often relies on the allocation of nematodes to feeding groups, experiments were performed to elucidate the feeding strategy of the new species. Both its ability to move actively to bacterial food sources and to prey on other compost nematodes were tested. Mononchoides composticola n. sp. actively moved towards the compost bacterium Achromobacter, a taxis that was temperature dependent, and also preyed on other nematodes. Predation was selective, with a higher predation rate on the relatively small and slow-moving Rhabditella sp. than on the considerably larger and more motile Rhabditis (Poikilolaimus) sp. Adults of M. composticola n. sp. have a dual feeding behaviour and can apparently alternate between bacterial and nematode prey.}, isbn = {1388-5545}, author = {Steel, H. and Moens, T. and Scholaert, A. and Boshoff, M. and Houthoofd, W. and Bert, W.} } @article {56, title = {Stem cells propagate their DNA by random segregation in the flatworm Macrostomum lignano.}, journal = {PLoS ONEPLoS ONE}, volume = {7:e30227}, year = {2012}, author = {Verdoodt, F. and Willems, M. and Mouton, S. and De Mulder, K. and Bert, W., and Houthoofd, W. and Smith, J. and Ladurner, P.} } @article {57, title = {Measuring S-phase duration of adult stem cells in the flatworm Macrostomum lignano by double replication labelling and quantitative colocalization analysis}, journal = {Cell Biology InternationalCell Biology International}, volume = {doi:10.1042/CBI20120187}, year = {2012}, author = {Verdoodt, F. and Willems, M. and Dhondt, I. and Houthoofd, W. and Bert, W. and De Vos, W.H.} }