RESUMEN
Tetrodotoxin (TTX), a pufferfish toxin, is a highly potent neurotoxin that has been found in a wide variety of animals. The TTX-bearing flatworm Planocera multitentaculata possesses a large amount of TTX and is considered responsible for the toxification of TTX-bearing animals such as pufferfish (Takifugu and Chelonodon) and the toxic goby Yongeichthys criniger. However, the mechanism underlying TTX accumulation in flatworms remains unclear. Previous studies have been limited to identifying the distribution of TTX in multiple organs, such as the digestive organs, genital parts, and the remaining tissues of flatworms. Here, we performed liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis and immunohistochemical staining using a monoclonal anti-TTX antibody to elucidate the detailed localization of TTX in the tissues and organs of the flatworm P. multitentaculata. Immunohistochemical staining for P. multitentaculata showed that TTX-specific signals were detected not only in the ovaries and pharynx but also in many other tissues and organs, whereas no signal was detected in the brain, Lang's vesicle, and genitalia. In addition, combined with LC-MS/MS analysis, it was revealed for the first time that TTX accumulates in high concentrations in the basement membrane and epidermis. These findings robustly support the hypotheses of "TTX utilization protection from predators."
Asunto(s)
Platelmintos , Espectrometría de Masas en Tándem , Tetrodotoxina , Animales , Tetrodotoxina/metabolismo , Tetrodotoxina/análisis , Cromatografía Liquida , Platelmintos/metabolismo , Femenino , Inmunohistoquímica , Distribución TisularRESUMEN
Tetrodotoxin (TTX), known as pufferfish toxin, is a potent neurotoxin blocking sodium channels in muscle and nerve tissues. TTX has been detected in various taxa other than pufferfish, including marine polyclad flatworms, suggesting that pufferfish toxin accumulates in fish bodies via food webs. The composition of TTX and its analogs in the flatworm Planocera multitentaculata was identical to those in wild grass puffer Takifugu alboplumbeus. Previously, Planocera sp. from Okinawa Island, Japan, were reported to possess high level of TTX, but no information was available on TTX analogs in this species. Here we identified TTX and analogs in the planocerid flatworm using high-resolution liquid chromatography-mass spectrometry, and compared the composition of TTX and analogs with those of another toxic and non-toxic planocerid species. We show that the composition of TTX and several analogs, such as 5,6,11-trideoxyTTX, dideoxyTTXs, deoxyTTXs, and 11-norTTX-6(S)-ol, of Planocera sp. was identical to those of toxic species, but not to its non-toxic counterpart. The difference in the toxin composition was reflected in the phylogenetic relationship based on the mitochondrial genome sequence. A toxification experiment using predatory fish and egg plates of P. multitentaculata demonstrated that the composition of TTX and analogs in wild T. alboplumbeus juveniles was reproduced in artificially toxified pufferfish. Additionally, feeding on the flatworm egg plates enhanced the signal intensities of all TTX compounds in Chelonodon patoca and that of deoxyTTXs in Yongeichthys criniger.
Asunto(s)
Tetrodotoxina , Animales , Tetrodotoxina/análisis , Tetrodotoxina/metabolismo , Japón , Platelmintos/genética , Platelmintos/metabolismo , Tetraodontiformes , Takifugu/metabolismo , Takifugu/genética , Cromatografía Liquida , Espectrometría de Masas , Islas , Pueblos del Este de AsiaRESUMEN
Much insight has been gained on how stem cells maintain genomic integrity, but less attention has been paid to how they maintain their transcriptome. Here, we report that the PIWI protein SMEDWI-1 plays a role in the filtering of dysfunctional transcripts from the transcriptome of planarian stem cells. SMEDWI-1 accomplishes this through association with the ribosomes during the pioneer round of translation, and processing of poorly translated transcripts into piRNAs. This results in the removal of such transcripts from the cytoplasmic pool and at the same time creates a dynamic pool of small RNAs for post-transcriptional surveillance through the piRNA pathway. Loss of SMEDWI-1 results in elevated levels of several non-coding transcripts, including rRNAs, snRNAs and pseudogene mRNAs, while reducing levels of several coding transcripts. In the absence of SMEDWI-1, stem cell colonies are delayed in their expansion and a higher fraction of descendants exit the stem cell state, indicating that this transcriptomic sanitation mediated by SMEDWI-1 is essential to maintain stem cell health. This study presents a new model for the function of PIWI proteins in stem cell maintenance, that complements their role in transposon repression, and proposes a new biogenesis pathway for piRNAs in stem cells.
Asunto(s)
Proteínas del Helminto , ARN de Interacción con Piwi , Platelmintos , Células Madre , Proteínas Argonautas/genética , Proteínas Argonautas/metabolismo , Elementos Transponibles de ADN , Proteínas del Helminto/metabolismo , Platelmintos/metabolismo , Proteínas/genética , Interferencia de ARN , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Células Madre/metabolismo , AnimalesRESUMEN
A ß-class carbonic anhydrase (CA, EC 4.2.1.1) present in the genome of the Monogenean platyhelminth Gyrodactylus salaris, a fish parasite, GsaCAß, has been investigated for its inhibitory effects with a panel of sulphonamides and sulfamates, some of which in clinical use. Several effective GsaCAß inhibitors were identified, belonging to simple heterocyclic sulphonamides, the deacetylated precursors of acetazolamide and methazolamide (KIsof 81.9-139.7 nM). Many other simple benezene sulphonamides and clinically used agents, such as acetazolamide, methazolamide, ethoxzolamide, dorzolamide, benzolamide, sulthiame and hydrochlorothiazide showed inhibition constants <1 µM. The least effective GsaCAß inhibitors were 4,6-disubstituted-1,3-benzene disulfonamides, with KIs in the range of 16.9-24.8 µM. Although no potent GsaCAß-selective inhibitors were detected so far, this preliminary investigation may be helpful for better understanding the inhibition profile of this parasite enzyme and for the potential development of more effective and eventually parasite-selective inhibitors.
Asunto(s)
Anhidrasas Carbónicas , Parásitos , Platelmintos , Animales , Acetazolamida , Anhidrasas Carbónicas/metabolismo , Metazolamida , Inhibidores de Anhidrasa Carbónica/farmacología , Parásitos/metabolismo , Platelmintos/metabolismo , Salmón/metabolismo , Relación Estructura-Actividad , Sulfonamidas/farmacología , SulfanilamidaRESUMEN
Non-parasitic flatworms are known to temporarily attach to the substrate by secreting a multicomponent bioadhesive to counteract water movements. However, to date, only species of two higher-level flatworm taxa (Macrostomorpha and Proseriata) have been investigated for their adhesive proteins. Remarkably, the surface-binding protein is not conserved between flatworm taxa. In this study, we sequenced and assembled a draft genome, as well as a transcriptome, and generated a tail-specific positional RNA sequencing dataset of the polyclad Theama mediterranea. This led to the identification of 15 candidate genes potentially involved in temporary adhesion. Using in situ hybridisation and RNA interference, we determined their expression and function. Of these 15 genes, 4 are homologues of adhesion-related genes found in other flatworms. With this work, we provide two novel key components on the flatworm temporary adhesion system. First, we identified a Kringle-domain-containing protein (Tmed-krg1), which was expressed exclusively in the anchor cell. This in silico predicted membrane-bound Tmed-krg1 could potentially bind to the cohesive protein, and a knockdown led to a non-adhesive phenotype. Secondly, a secreted tyrosinase (Tmed-tyr1) was identified, which might crosslink the adhesive proteins. Overall, our findings will contribute to the future development of reversible synthetic glues with desirable properties for medical and industrial applications.
Asunto(s)
Platelmintos , Animales , Platelmintos/metabolismo , Proteínas/metabolismo , Interferencia de ARN , Análisis de Secuencia de ARN , TranscriptomaRESUMEN
Tetraspanins are a superfamily of transmembrane proteins that in flatworms have structural roles in the development, maturation or stability of the tegument. Several tetraspanins are considered as potential candidates for vaccines or drugs against helminths. Monopisthocotylean monogeneans are ectoparasites of fish that are health hazards for farmed fish. The aim of this study was to identify in silico putative tetraspanins in the genomic datasets of four monopisthocotylean species. The analysis predicted and classified 40 tetraspanins in Rhabdosynochus viridisi, 39 in Scutogyrus longicornis, 22 in Gyrodactylus salaris and 13 in Neobenedenia melleni, belonging to 13 orthologous groups. The high divergence of tetraspanins made it difficult to annotate their function. However, a conserved group was identified in different metazoan taxa. According to this study, metazoan tetraspanins can be divided into 17 monophyletic groups. Of the 114 monogenean tetraspanins, only seven were phylogenetically close to tetraspanins from non-platyhelminth metazoans, which suggests that this group of proteins shows rapid sequence divergence. The similarity of the monopisthocotylean tetraspanins was highest with trematodes, followed by cestodes and then free-living platyhelminths. In total, 27 monopisthocotylean-specific and 34 flatworm-specific tetraspanins were identified. Four monogenean tetraspanins were orthologous to TSP-1, which is a candidate for the development of vaccines and a potential pharmacological target in trematodes and cestodes. Although studies of tetraspanins in parasitic flatworms are scarce, this is an interesting group of proteins for the development of new methods to control monogeneans.
Asunto(s)
Enfermedades de los Peces , Platelmintos , Tetraspaninas , Animales , Enfermedades de los Peces/parasitología , Peces , Filogenia , Platelmintos/genética , Platelmintos/metabolismo , Tetraspaninas/química , Tetraspaninas/clasificación , Tetraspaninas/genéticaRESUMEN
Many free-living flatworms have evolved a temporary adhesion system, which allows them to quickly attach to and release from diverse substrates. In the marine Macrostomum lignano, the morphology of the adhesive system and the adhesion-related proteins have been characterised. However, little is known about how temporary adhesion is performed in other aquatic environments. Here, we performed a 3D reconstruction of the M. lignano adhesive organ and compared it to the morphology of five selected Macrostomum, representing two marine, one brackish, and two freshwater species. We compared the protein domains of the two adhesive proteins, as well as an anchor cell-specific intermediate filament. We analysed the gene expression of these proteins by in situ hybridisation and performed functional knockdowns with RNA interference. Remarkably, there are almost no differences in terms of morphology, protein regions, and gene expression based on marine, brackish, and freshwater habitats. This implies that glue components produced by macrostomids are conserved among species, and this set of two-component glue functions from low to high salinity. These findings could contribute to the development of novel reversible biomimetic glues that work in all wet environments and could have applications in drug delivery systems, tissue adhesives, or wound dressings.
Asunto(s)
Adhesivos/química , Materiales Biomiméticos/química , Proteínas del Helminto , Platelmintos , Estructuras Animales , Animales , Agua Dulce , Proteínas del Helminto/química , Proteínas del Helminto/genética , Proteínas del Helminto/metabolismo , Platelmintos/química , Platelmintos/genética , Platelmintos/metabolismo , Agua de MarRESUMEN
Several polyclad flatworm species are known to contain high levels of tetrodotoxin (TTX), but currently TTX-bearing flatworms seem to be restricted to specific Planocera lineages belonging to the suborder Acotylea. During our ongoing study of flatworm toxins, high concentrations of TTXs were detected for the first time in the flatworm Prosthiostomum trilineatum, suborder Cotylea, from the coastal area of Hayama, Kanagawa, Japan. Toxin levels were investigated by high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS), revealing that this species contains comparable concentrations of toxins as seen in planocerid flatworms such as Planocera multitentaculata. This finding indicated that there may be other species with significant levels of TTXs. The distribution of TTXs among other flatworm species is thus of great interest.
Asunto(s)
Platelmintos/metabolismo , Tetrodotoxina/aislamiento & purificación , Animales , Cromatografía Líquida de Alta Presión , Japón , Espectrometría de Masas en Tándem , Tetrodotoxina/análisis , Tetrodotoxina/químicaRESUMEN
Marine invertebrates are promising sources of novel bioactive secondary metabolites, and organisms like sponges, ascidians and nudibranchs are characterised by possessing potent defensive chemicals. Animals that possess chemical defences often advertise this fact with aposematic colouration that potential predators learn to avoid. One seemingly defenceless group that can present bright colouration patterns are flatworms of the order Polycladida. Although members of this group have typically been overlooked due to their solitary and benthic nature, recent studies have isolated the neurotoxin tetrodotoxin from these mesopredators. This review considers the potential of polyclads as potential sources of natural products and reviews what is known of the activity of the molecules found in these animals. Considering the ecology and diversity of polyclads, only a small number of species from both suborders of Polycladida, Acotylea and Cotylea have been investigated for natural products. As such, confirming assumptions as to which species are in any sense toxic or if the compounds they use are biosynthesised, accumulated from food or the product of symbiotic bacteria is difficult. However, further research into the group is suggested as these animals often display aposematic colouration and are known to prey on invertebrates rich in bioactive secondary metabolites.
Asunto(s)
Productos Biológicos/aislamiento & purificación , Productos Biológicos/metabolismo , Platelmintos/metabolismo , Metabolismo Secundario/fisiología , Animales , Productos Biológicos/química , Platelmintos/química , Estructura Secundaria de Proteína , Estructura Terciaria de ProteínaRESUMEN
Fueled by the discovery of head regeneration in triclads (planarians) two and a half centuries ago, flatworms have been the focus of regeneration research. But not all flatworms can regenerate equally well and to obtain a better picture of the characteristics and evolution of regeneration in flatworms other than planarians, the regeneration capacity and stem cell dynamics during regeneration in the flatworm order Polycladida are studied. Here, we show that as long as the brain remained at least partially intact, the polyclad Prosthiostomum siphunculus was able to regenerate submarginal eyes, cerebral eyes, pharynx, intestine and sucker. In the complete absence of the brain only wound closure was observed but no regeneration of missing organs. Amputated parts of the brain could not be regenerated. The overall regeneration capacity of P. siphunculus is a good fit for category III after a recently established system, in which most polyclads are currently classified. Intact animals showed proliferating cells in front of the brain which is an exception compared with most of the other free-living flatworms that have been observed so far. Proliferating cells could be found within the regeneration blastema, similar to all other flatworm taxa except triclads. No proliferation was observed in epidermis and pharynx. In pulse-chase experiments, the chased cells were found in all regenerated tissues and thereby shown to differentiate and migrate to replace the structures lost upon amputation.
Asunto(s)
Encéfalo/fisiología , Platelmintos , Regeneración , Animales , Proliferación Celular , Platelmintos/crecimiento & desarrollo , Platelmintos/metabolismoRESUMEN
BACKGROUND: The TNF signaling pathway is involved in the regulation of many cellular processes (such as apoptosis and cell proliferation). Previous reports indicated the effect of human TNF-α on metabolism, physiology, gene expression and protein phosphorylation of the human parasite Schistosoma mansoni and suggested that its TNF receptor was responsible for this response. The lack of an endogenous TNF ligand reinforced the idea of the use of an exogenous ligand, but also opens the possibility that the receptor actually binds a non-canonical ligand, as observed for NGFRs. METHODS: To obtain a more comprehensive view, we analyzed platyhelminth genomes deposited in the Wormbase ParaSite database to investigate the presence of TNF receptors and their respective ligands. Using different bioinformatics approaches, such as HMMer and BLAST search tools we identified and characterized the sequence of TNF receptors and ligand homologs. We also used bioinformatics resources for the identification of conserved protein domains and Bayesian inference for phylogenetic analysis. RESULTS: Our analyses indicate the presence of 31 TNF receptors in 30 platyhelminth species. All platyhelminths display a single TNF receptor, and all are structurally remarkably similar to NGFR. It suggests no events of duplication and diversification occurred in this phylum, with the exception of a single species-specific duplication. Interestingly, we also identified TNF ligand homologs in five species of free-living platyhelminths. CONCLUSIONS: These results suggest that the TNF receptor from platyhelminths may be able to bind canonical TNF ligands, thus strengthening the idea that these receptors are able to bind human TNF-α. This also raises the hypothesis that an endogenous ligand was substituted by the host ligand in parasitic platyhelminths. Moreover, our analysis indicates that death domains (DD) may be present in the intracellular region of most platyhelminth TNF receptors, thus pointing to a previously unreported apoptotic action of such receptors in platyhelminths. Our data highlight the idea that host-parasite crosstalk using the TNF pathway may be widespread in parasitic platyhelminths to mediate apoptotic responses. This opens up a new hypothesis to uncover what might be an important component to understand platyhelminth infections.
Asunto(s)
Proteínas del Helminto/metabolismo , Platelmintos/metabolismo , Receptores del Factor de Necrosis Tumoral/metabolismo , Infecciones por Trematodos/parasitología , Secuencia de Aminoácidos , Animales , Evolución Molecular , Genoma de los Helmintos , Proteínas del Helminto/química , Proteínas del Helminto/genética , Interacciones Huésped-Parásitos , Filogenia , Platelmintos/química , Platelmintos/clasificación , Platelmintos/genética , Receptores del Factor de Necrosis Tumoral/química , Receptores del Factor de Necrosis Tumoral/genética , Alineación de Secuencia , Transducción de Señal , Infecciones por Trematodos/metabolismo , Factores de Necrosis Tumoral/metabolismoRESUMEN
Parasitic helminths use two benzoquinones as electron carriers in the electron transport chain. In normoxia, they use ubiquinone (UQ), but in anaerobic conditions inside the host, they require rhodoquinone (RQ) and greatly increase RQ levels. We previously showed the switch from UQ to RQ synthesis is driven by a change of substrates by the polyprenyltransferase COQ-2 (Del Borrello et al., 2019; Roberts Buceta et al., 2019); however, the mechanism of substrate selection is not known. Here, we show helminths synthesize two coq-2 splice forms, coq-2a and coq-2e, and the coq-2e-specific exon is only found in species that synthesize RQ. We show that in Caenorhabditis elegans COQ-2e is required for efficient RQ synthesis and survival in cyanide. Importantly, parasites switch from COQ-2a to COQ-2e as they transit into anaerobic environments. We conclude helminths switch from UQ to RQ synthesis principally via changes in the alternative splicing of coq-2.
Asunto(s)
Transferasas Alquil y Aril/genética , Empalme Alternativo , Proteínas de Caenorhabditis elegans/genética , Caenorhabditis elegans/genética , Ubiquinona/análogos & derivados , Transferasas Alquil y Aril/metabolismo , Animales , Caenorhabditis elegans/enzimología , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Nematodos/enzimología , Nematodos/genética , Nematodos/metabolismo , Oxidación-Reducción , Platelmintos/enzimología , Platelmintos/genética , Platelmintos/metabolismo , Ubiquinona/metabolismoRESUMEN
Eudiplozoon nipponicum (Goto, 1891) is a hematophagous monogenean ectoparasite which inhabits the gills of the common carp (Cyprinus carpio). Heavy infestation can lead to anemia and in conjunction with secondary bacterial infections cause poor health and eventual death of the host. This study is based on an innovative approach to protein localization which has never been used in parasitology before. Using laser capture microdissection, we dissected particular areas of the parasite body without contaminating the samples by surrounding tissue and in combination with analysis by mass spectrometry obtained tissue-specific proteomes of tegument, intestine, and parenchyma of our model organism, E. nipponicum. We successfully verified the presence of certain functional proteins (e.g. cathepsin L) in tissues where their presence was expected (intestine) and confirmed that there were no traces of these proteins in other tissues (tegument and parenchyma). Additionally, we identified a total of 2,059 proteins, including 72 peptidases and 33 peptidase inhibitors. As expected, the greatest variety was found in the intestine and the lowest variety in the parenchyma. Our results are significant on two levels. Firstly, we demonstrated that one can localize all proteins in one analysis and without using laboratory animals (antibodies for immunolocalization of single proteins). Secondly, this study offers the first complex proteomic data on not only the E. nipponicum but within the whole class of Monogenea, which was from this point of view until recently neglected.
Asunto(s)
Mucosa Intestinal/metabolismo , Tejido Parenquimatoso/metabolismo , Platelmintos/metabolismo , Proteoma/análisis , Proteómica/métodos , Animales , Carpas/parasitología , Catepsinas/análisis , Catepsinas/metabolismo , Cromatografía Líquida de Alta Presión , Branquias/parasitología , Captura por Microdisección con Láser , Péptido Hidrolasas/análisis , Péptido Hidrolasas/metabolismo , Espectrometría de Masas en TándemRESUMEN
The contamination of coastal regions with different toxicants, including heavy metal ions such as copper and cadmium jeopardize health and survival of organisms exposed to this habitat. To study the effects of high copper and cadmium concentrations in these marine environments, we used the flatworm Macrostomum lignano as a model. This platyhelminth lives in shallow coastal water and is exposed to high concentrations of all toxicants that accumulate in these sea floors. We could show that both, cadmium and copper show toxicity at higher concentrations, with copper being more toxic than cadmium. At concentrations below acute toxicity, a reduced long-term survival was observed for both metal ions. The effects of sublethal doses comprise reduced physical activities, an increase in ROS levels within the worms, and alterations of the mitochondrial biology. Moreover, cell death events were substantially increased in response to sublethal concentrations of both metal ions and stem cell activity was reduced following exposure to higher cadmium concentrations. Finally, the expression of several genes involved in xenobiotic metabolism was substantially altered by this intervention. Taken together, M. lignano has been identified as a suitable model for marine toxicological studies as it allows to quantify several relevant life-history traits as well as of physiological and behavioral read-outs.
Asunto(s)
Cadmio/toxicidad , Cobre/toxicidad , Estrés Oxidativo/efectos de los fármacos , Platelmintos/efectos de los fármacos , Contaminantes Químicos del Agua/toxicidad , Animales , Relación Dosis-Respuesta a Droga , Platelmintos/genética , Platelmintos/metabolismo , Pruebas de ToxicidadRESUMEN
Tetrodotoxin (TTX), a potent neurotoxin, is found in various phylogenetically diverse taxa. In marine environments, the pufferfish is at the top of the food chain among TTX-bearing organisms. The accumulation of TTX in the body of pufferfish appears to be of the food web that begins with bacteria. It is known that toxic pufferfishes possess TTX from the larval/juvenile stage. However, the source of the TTX is unknown because the maternally sourced TTX is extremely small in quantity. Therefore, the TTX has to be obtained from other organisms or directly from the environment. Here, we report evidence that the source of TTX for toxic fish juveniles including the pufferfish (Chelonodon patoca) and the goby (Yongeichthys criniger) is in the food organisms, as seen in their gut contents. Next generation sequencing analysis for the mitochondrial COI gene showed that the majority of the sequence recovered from intestinal contents of these toxic fishes belonged to the flatworm Planocera multitentaculata, a polyclad flatworm containing highly concentrated TTX from the larval stage. PCR specific to P. multitentaculata also showed that DNA encoding the planocerid COI gene was strongly detected in the intestinal contents of the goby and pufferfish juveniles. Additionally, the planocerid specific COI sequence was detected in the environmental seawater collected from the water around the sampling locations for TTX-bearing fish. These results suggest that planocerid larvae are the major TTX supplier for juveniles of TTX-bearing fish species.
Asunto(s)
Platelmintos/metabolismo , Tetraodontiformes/metabolismo , Tetrodotoxina/metabolismo , Animales , Cadena Alimentaria , Larva , Perciformes , FilogeniaRESUMEN
Nematocysts are characteristic organelles of the phylum Cnidaria. The free-living Platyhelminth Microstomum lineare preys on Hydra oligactis and sequesters nematocysts. All nematocyst types become phagocytosed without adherent cytoplasm by intestinal cnidophagocytes. Desmoneme and isorhiza nematocysts disappear within 2 days after ingestion whereas cnidophagocytes containing the venom-loaded stenotele nematocysts migrate out of the intestinal epithelia through the parenchyma to the epidermis. Epidermally localized stenoteles are still able to discharge suggesting that this hydra organelle does preserve its physiological properties. Three to four weeks after ingestion, the majority of stenoteles disappear from M. lineare. To search for alterations of nematocysts that might precede their disappearance, flatworms were stained with acridine orange, a dye that binds to poly-γ-glutamic acid present in hydra nematocysts. The staining properties of all three nematocyst types were indistinguishable during the first 60 min after ingestion of hydra tissue whereas 15 h later, the majority of desmoneme and isorhiza had lost their stainability in striking contrast to stenoteles. In M. lineare inspected 2, 4 and 10 days after feeding, 20-40% of stenoteles had lost their stainability with acridine orange. Non-stained stenoteles had sizes similar to their stained counterparts but some of them were slightly deformed. The presented data indicate that acridine orange staining allows the detection of early alterations of all three ingested nematocyst types preceding their disappearance from M. lineare. Furthermore, they support the notion that the transport of venom-loaded stenoteles to the epidermis provides a strategy of excretion.
Asunto(s)
Hydra/metabolismo , Nematocisto/metabolismo , Platelmintos/metabolismo , Animales , Digestión , Fagocitosis , Coloración y EtiquetadoRESUMEN
Nuclear receptors (NRs) belong to a large protein superfamily which includes intracellular receptors for secreted hydrophobic signal molecules, such as steroid hormones and thyroid hormones. They regulate development and reproduction in metazoans by binding to the promoter region of their target gene to activate or repress mRNA synthesis. Isolation and characterization of NRs in the parasitic trematode Schistosoma mansoni identified two homologues of mammalian thyroid receptor (TR). This was the first known protostome exhibiting TR homologues. Three novel NRs each possess a novel set of two DNA binding domains (DBD) in tandem with a ligand binding domain (LBD) (2DBD-NRs) isolated in Schistosoma mansoni revealed a novel NR modular structure: A/B-DBD-DBD-hinge-LBD. Full length cDNA of several NRs have been isolated and studied in the parasitic trematodes S. mansoni, S. japonicum and in the cestode Echinococcus multilocularis. The genome of the blood flukes S. mansoni, S. japonicum and S. haematobium, the liver fluke Clonorchis sinensis and the cestode Echinococcus multilocularis have been sequenced. Study of the NR complement in parasitic Platyhelminths will help us to understand the role of NRs in regulation of their development and understand the evolution of NR in animals.
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Platelmintos/metabolismo , Receptores Citoplasmáticos y Nucleares/genética , Animales , Clonorchis sinensis/metabolismo , Echinococcus multilocularis/metabolismo , Evolución Molecular , Proteínas del Helminto/genética , Filogenia , Receptores Citoplasmáticos y Nucleares/química , Receptores Citoplasmáticos y Nucleares/metabolismo , Schistosoma/metabolismo , Schistosoma mansoni/metabolismoRESUMEN
Hosts of chemoautotrophic bacteria typically have much higher biomass than their symbionts and consume symbiont cells for nutrition. In contrast to this, chemoautotrophic Candidatus Riegeria symbionts in mouthless Paracatenula flatworms comprise up to half of the biomass of the consortium. Each species of Paracatenula harbors a specific Ca Riegeria, and the endosymbionts have been vertically transmitted for at least 500 million years. Such prolonged strict vertical transmission leads to streamlining of symbiont genomes, and the retained physiological capacities reveal the functions the symbionts provide to their hosts. Here, we studied a species of Paracatenula from Sant'Andrea, Elba, Italy, using genomics, gene expression, imaging analyses, as well as targeted and untargeted MS. We show that its symbiont, Ca R. santandreae has a drastically smaller genome (1.34 Mb) than the symbiont´s free-living relatives (4.29-4.97 Mb) but retains a versatile and energy-efficient metabolism. It encodes and expresses a complete intermediary carbon metabolism and enhanced carbon fixation through anaplerosis and accumulates massive intracellular inclusions such as sulfur, polyhydroxyalkanoates, and carbohydrates. Compared with symbiotic and free-living chemoautotrophs, Ca R. santandreae's versatility in energy storage is unparalleled in chemoautotrophs with such compact genomes. Transmission EM as well as host and symbiont expression data suggest that Ca R. santandreae largely provisions its host via outer-membrane vesicle secretion. With its high share of biomass in the symbiosis and large standing stocks of carbon and energy reserves, it has a unique role for bacterial symbionts-serving as the primary energy storage for its animal host.
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Genoma Bacteriano/genética , Platelmintos , Rhodospirillaceae , Simbiosis , Animales , Crecimiento Quimioautotrófico/genética , Crecimiento Quimioautotrófico/fisiología , Redes y Vías Metabólicas , Platelmintos/metabolismo , Platelmintos/microbiología , Platelmintos/fisiología , Rhodospirillaceae/genética , Rhodospirillaceae/fisiología , Simbiosis/genética , Simbiosis/fisiologíaRESUMEN
The flatworm Macrostomum lignano features a duo-gland adhesive system that allows it to repeatedly attach to and release from substrates in seawater within a minute. However, little is known about the molecules involved in this temporary adhesion. In this study, we show that the attachment of M. lignano relies on the secretion of two large adhesive proteins, M. lignano adhesion protein 1 (Mlig-ap1) and Mlig-ap2. We revealed that both proteins are expressed in the adhesive gland cells and that their distribution within the adhesive footprints was spatially restricted. RNA interference knockdown experiments demonstrated the essential function of these two proteins in flatworm adhesion. Negatively charged modified sugars in the surrounding water inhibited flatworm attachment, while positively charged molecules impeded detachment. In addition, we found that M. lignano could not adhere to strongly hydrated surfaces. We propose an attachment-release model where Mlig-ap2 attaches to the substrate and Mlig-ap1 exhibits a cohesive function. A small negatively charged molecule is secreted that interferes with Mlig-ap1, inducing detachment. These findings are of relevance for fundamental adhesion science and efforts to mitigate biofouling. Further, this model of flatworm temporary adhesion may serve as the starting point for the development of synthetic reversible adhesion systems for medicinal and industrial applications.
Asunto(s)
Adhesión Celular/fisiología , Gónadas/metabolismo , Proteínas del Helminto/metabolismo , Platelmintos/fisiología , Adhesivos , Animales , Femenino , Técnicas de Silenciamiento del Gen , Gónadas/citología , Proteínas del Helminto/genética , Péptidos y Proteínas de Señalización Intracelular , Masculino , Platelmintos/citología , Platelmintos/metabolismo , Interferencia de ARN , Transducción de SeñalRESUMEN
BACKGROUND: Along with sperm, in many taxa ejaculates also contain large numbers of seminal fluid proteins (SFPs). SFPs and sperm are transferred to the mating partner, where they are thought to play key roles in mediating post-mating sexual selection. They modulate the partner's behavior and physiology in ways that influence the reproductive success of both partners, thus potentially leading to sexual conflict. Despite the presumed general functional and evolutionary significance of SFPs, their identification and characterization has to date focused on just a few animal groups, predominantly insects and mammals. Moreover, until now seminal fluid profiling has mainly focused on species with separate sexes. Here we report a comprehensive screen for putative SFPs in the simultaneously hermaphroditic flatworm Macrostomum lignano. RESULTS: Based on existing transcriptomic data, we selected 150 transcripts known to be (a) predominantly expressed in the tail region of the worms, where the seminal fluid-producing prostate gland cells are located, and (b) differentially expressed in social environments differing in sperm competition level, strongly implying that they represent a phenotypically plastic aspect of male reproductive allocation in this species. For these SFP candidates, we then performed whole-mount in situ hybridization (ISH) experiments to characterize tissue-specific expression. In total, we identified 98 transcripts that exhibited prostate-specific expression, 76 of which we found to be expressed exclusively in the prostate gland cells; additional sites of expression for the remaining 22 included the testis or other gland cells. Bioinformatics analyses of the prostate-limited candidates revealed that at least 64 are predicted to be secretory proteins, making these especially strong candidates to be SFPs that are transferred during copulation. CONCLUSIONS: Our study represents a first comprehensive analysis using a combination of transcriptomic and ISH screen data to identify SFPs based on transcript expression in seminal fluid-producing tissues. We thereby extend the range of taxa for which seminal fluid has been characterized to a flatworm species with a sequenced genome and for which several methods such as antibody staining, transgenesis and RNA interference have been established. Our data provide a basis for testing the functional and evolutionary significance of SFPs.