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Georg Krohne
Nematocysts are characteristic organelles of the phylum cnidaria. They are designated kleptocnidae when sequestered in animals that feed on cnidaria. Kleptocnidae are known for more than a century. Nevertheless it is still enigmatic how selected nematocyst types survive in the predator and how they reach their final destination in the foreign body. In the free-living Platyhelminth Microstomum lineare the fate of nematocysts of the prey Hydra oligactis was analyzed at the ultrastructural level and by fluorescence microscopy using hydra polyps that had been stained in vivo with the fluorescent dyes TROMI and TRITC...
April 8, 2018: European Journal of Cell Biology
Takato Izumi, Yuji Ise, Kensuke Yanagi, Daisuke Shibata, Rei Ueshima
A new species in a new genus of sea anemone, Tempuractis rinkai gen. et sp. nov., was discovered at several localities along the temperate rocky shores of Japan. The new species is approximately 4 mm in length and has been assigned to family Edwardsiidae, because it has eight macrocnemes, lacks sphincter and basal muscles, and possesses rounded aboral end. The sea anemone, however, also has a peculiar body shape unlike that of any other known taxa. This new species resembles some genera, especially Drillactis and Nematostella, in smooth column surface without nemathybomes or tenaculi, but is distinguishable from them by several morphological features: the presence of holotrichs and absence of nematosomes...
April 2018: Zoological Science
Okuto Takama, Iria Fernandez-Silva, Cataixa López, James Davis Reimer
Millepora (Cnidaria: Hydrozoa: Milleporidae) spp. are distributed throughout shallow subtropical and tropical marine environments in the Indo-Pacific and Caribbean-Atlantic, and have traditionally been identified using pore characteristics and colony form. Until now, representatives of Millepora spp. on the island of Okinawa-jima, Japan, have been divided into five species; three branching species (Millepora intricata, M. tenera, M. dichotoma), one species with plate-like morphology (M. platyphylla), and one encrusting species (M...
April 2018: Zoological Science
Luis Martell, Roberta Bracale, Steven A Carrion, Jennifer E Purcell, Marco Lezzi, Cinzia Gravili, Stefano Piraino, Ferdinando Boero
Aquaculture is increasing rapidly to meet global seafood demand. Some hydroid populations have been linked to mortality and health issues in finfish and shellfish, but their dynamics in and around aquaculture farms remain understudied. In the present work, two experiments, each with 36 panels, tested colonization (factors: depth, season of immersion) and succession (factors: depth, submersion duration) over one year. Hydroid surface cover was estimated for each species, and data were analyzed with multivariate techniques...
2018: PloS One
Jorge C Eiras, Cristina Cruz, Aurélia Saraiva
A synopsis of the species of Ceratomyxa Thélohan, 1892 (Cnidaria, Myxosporea, Ceratomyxidae) described between 2007 and 2017 is presented, including 83 nominal species. For each species, the most important morphological and morphometric features are indicated in tabulated format. Included are also the site of infection within the host, and geographical location, plus a full bibliography of the original records of species. Molecular data (GenBank accession numbers) are also provided whenever possible.
March 28, 2018: Systematic Parasitology
Joseph J Brennan, Thomas D Gilmore
Toll-like receptors (TLRs) are transmembrane pattern recognition receptors that are best known for their roles in innate immunity for the detection of and defense against microbial pathogens. However, TLRs also have roles in many non-immune processes, most notably development. TLRs direct both immune and developmental programs by activation of downstream signaling pathways, often by activation of the NF-κB pathway. There are two primary TLR subtypes: 1) TLRs with multiple cysteine clusters in their ectodomain (mccTLRs) and 2) TLRs with a single cysteine cluster in their ectodomain (sccTLRs)...
March 26, 2018: Molecular Biology and Evolution
Stephen D Atkinson, Sascha L Hallett, Jerri L Bartholomew
Genotypes of the myxosporean parasite Ceratonova shasta are defined by the number of ATC repeats in the parasite's ribosomal DNA internal transcribed spacer region 1. These genotypes correlate with specific salmonid fish hosts. We observed coho salmon (Oncorhynchus kisutch) and rainbow trout (Oncorhynchus mykiss) with mixtures of genotypes II and III, and assumed that this was a consequence of fish having an aggregate infection from multiple individual parasites. We hypothesized that although multiple ITS copies are present within a parasite spore, the DNA sequences of these copies are identical, and thus individual C...
March 27, 2018: Parasitology
Astrid S Holzer, Pavla Bartošová-Sojková, Ana Born-Torrijos, Alena Lövy, Ashlie Hartigan, Ivan Fiala
The relationships between parasites and their hosts are intimate, dynamic and complex; the evolution of one is inevitably linked to the other. Despite multiple origins of parasitism in the Cnidaria, only parasites belonging to the Myxozoa are characterized by a complex life cycle, alternating between fish and invertebrate hosts, as well as by high species diversity. This inspired us to examine the history of adaptive radiations in myxozoans and their hosts by determining the degree of congruence between their phylogenies and by timing the emergence of myxozoan lineages in relation to their hosts...
March 24, 2018: Molecular Ecology
Roger Revilla-I-Domingo, Oleg Simakov
The biannual international workshop entitled "The diversification of early emerging metazoans: A window into animal evolution?" took place at the Evangelische Akademie Tutzing, Germany, 11-14. September 2017. It was organized by Thomas Bosch (Kiel), Thomas Holstein (Heidelberg), and Ulrich Technau (Vienna), and it was sponsored by the Deutsche Forschungsgemeinschaft (DFG). The meeting gathered over 140 researchers to discuss the contribution of non-bilaterian metazoan models (Porifera, Ctenophora, Placozoa, and Cnidaria) to our understanding of: a...
March 25, 2018: BioEssays: News and Reviews in Molecular, Cellular and Developmental Biology
Jimena García-Rodríguez, Cheryl Lewis Ames, José Eduardo A R Marian, Antonio Carlos Marques
Cubozoans (box jellyfish) are gonochoristic cnidarians with distinct reproductive strategies. This comparative histological study examines the gonad organization of Alatina alata and Copula sivickisi, two box jellyfish species that exhibit different modes of internal fertilization. A. alata reproduces via spermcasting aggregations while C. sivickisi reproduces via copulation; in both cases, internal fertilization occurs in the gastrovascular cavity. Herein, we provide the first histological description of subgastric sacs-structures unique to C...
March 23, 2018: Journal of Morphology
Alessia Remigante, Roberta Costa, Rossana Morabito, Giuseppa La Spada, Angela Marino, Silvia Dossena
Cnidaria include the most venomous animals of the world. Among Cnidaria, Scyphozoa (true jellyfish) are ubiquitous, abundant, and often come into accidental contact with humans and, therefore, represent a threat for public health and safety. The venom of Scyphozoa is a complex mixture of bioactive substances-including thermolabile enzymes such as phospholipases, metalloproteinases, and, possibly, pore-forming proteins-and is only partially characterized. Scyphozoan stings may lead to local and systemic reactions via toxic and immunological mechanisms; some of these reactions may represent a medical emergency...
March 23, 2018: Toxins
Rebecca R Helm, Maria Laura Martín-Díaz, Ann M Tarrant
Peroxiredoxins (PRXs) are a family of antioxidant enzymes present in all domains of life. To date, the diversity and function of peroxiredoxins within animals has only been studied in a few model species. Thus, we sought to characterize peroxiredoxin diversity in cnidarians and to gain insight into their function in one cnidarian-the sea anemone Nematostella vectensis. Phylogenetic analysis using all six known PRX subfamilies (PRX1-4, PRX5, PRX6, PRXQ/AHPE1, TPX, BCP-PRXQ) revealed that like bilaterians, cnidarians contain representatives from three subfamilies (PRX1-4, PRX5, PRX6)...
March 19, 2018: Comparative Biochemistry and Physiology. Part A, Molecular & Integrative Physiology
Pavla Bartošová-Sojková, Alena Lövy, Cecile C Reed, Martina Lisnerová, Tereza Tomková, Astrid S Holzer, Ivan Fiala
INTRODUCTION: Intertidal rock pools where fish and invertebrates are in constant close contact due to limited space and water level fluctuations represent ideal conditions to promote life cycles in parasites using these two alternate hosts and to study speciation processes that could contribute to understanding the roles of parasitic species in such ecosystems. MATERIAL AND METHODS: Gall bladder and liver samples from five clinid fish species (Blenniiformes: Clinidae) were morphologically and molecularly examined to determine the diversity, prevalence, distribution and host specificity of Ceratomyxa parasites (Cnidaria: Myxozoa) in intertidal habitats along the coast of South Africa...
2018: PloS One
Longhua Guo, Alice Accorsi, Shuonan He, Carlos Guerrero-Hernández, Shamilene Sivagnanam, Sean McKinney, Matthew Gibson, Alejandro Sánchez Alvarado
BACKGROUND: The ability to efficiently visualize and manipulate chromosomes is fundamental to understanding the genome architecture of organisms. Conventional chromosome preparation protocols developed for mammalian cells and those relying on species-specific conditions are not suitable for many invertebrates. Hence, a simple and inexpensive chromosome preparation protocol, adaptable to multiple invertebrate species, is needed. RESULTS: We optimized a chromosome preparation protocol and applied it to several planarian species (phylum Platyhelminthes), the freshwater apple snail Pomacea canaliculata (phylum Mollusca), and the starlet sea anemone Nematostella vectensis (phylum Cnidaria)...
February 26, 2018: BMC Biology
Kyoung Hwan Lee, Guidenn Sulbarán, Shixin Yang, Ji Young Mun, Lorenzo Alamo, Antonio Pinto, Osamu Sato, Mitsuo Ikebe, Xiong Liu, Edward D Korn, Floyd Sarsoza, Sanford I Bernstein, Raúl Padrón, Roger Craig
Electron microscope studies have shown that the switched-off state of myosin II in muscle involves intramolecular interaction between the two heads of myosin and between one head and the tail. The interaction, seen in both myosin filaments and isolated molecules, inhibits activity by blocking actin-binding and ATPase sites on myosin. This interacting-heads motif is highly conserved, occurring in invertebrates and vertebrates, in striated, smooth, and nonmuscle myosin IIs, and in myosins regulated by both Ca 2+ binding and regulatory light-chain phosphorylation...
February 14, 2018: Proceedings of the National Academy of Sciences of the United States of America
Stephen D Cairns
Thirteen species of deep-water calcaxonian octocorals belonging to the families Primnoidae, Chrysogorgiidae, and Isididae collected from off the Galápagos and Cocos Islands are described and figured. Seven of these species are described as new; nine of the 13 are not known outside the Galápagos region. Of the four species occurring elsewhere, two also occur in the eastern Pacific, one off Hawaii, and one from off Antarctica. A key to the 22 Indo-Pacific species of Callogorgia is provided to help distinguish those species...
2018: ZooKeys
Suellen Aparecida Zatti, Stephen D Atkinson, Antônio A M Maia, Jerri L Bartholomew, Edson A Adriano
We describe three new Henneguya spp. (Myxobolidae) found parasitizing two species of cichlid fish from the Amazon basin, Brazil: H. tucunarei n. sp. from gill filaments of Cichla monoculus and H. tapajoensis n. sp. from gill filaments of Cichla pinima, both from the Tapajós River, Pará State and H. jariensis n. sp. in the fins of Cichla monoculus from the Jari River, Amapá State. We based descriptions on myxospore morphology and small subunit ribosomal DNA sequences, and used a phylogenetic analysis to compare the new Henneguya species with known relatives...
January 27, 2018: Parasitology Research
Lauren E Friedman, Thomas D Gilmore, John R Finnerty
Nematostella vectensis is a member of the phylum Cnidaria, a lineage that includes anemones, corals, hydras, and jellyfishes. This estuarine anemone is an excellent model system for investigating the evolution of stress tolerance because it is easy to collect in its natural habitat and to culture in the laboratory, and it has a sequenced genome. Additionally, there is evidence of local adaptation to environmental stress in different N. vectensis populations, and abundant protein-coding polymorphisms have been identified, including polymorphisms in proteins that are implicated in stress responses...
2018: PloS One
Suellen A Zatti, Stephen D Atkinson, Antônio A M Maia, Jerri L Bartholomew, Edson A Adriano
We describe a new freshwater myxosporean species Ceratomyxa gracillima n. sp. from the gall bladder of the Amazonian catfish Brachyplatystoma rousseauxii; the first myxozoan recorded in this host. The new Ceratomyxa was described on the basis of its host, myxospore morphometry, ssrDNA and internal transcribed spacer region (ITS-1) sequences. Infected fish were sampled from geographically distant localities: the Tapajós River, Pará State, the Amazon River, Amapá State and the Solimões River, Amazonas State...
January 17, 2018: Parasitology
Jun-Yuan Li, Dong-Hui Guo, Peng-Cheng Wu, Li-Sheng He
Ontogeny reversal, as seen in some cnidarians, is an unprecedented phenomenon in the animal kingdom involving reversal of the ordinary life cycle. Three species of Turritopsis have been shown to be capable of inverted metamorphosis, a process in which the pelagic medusa transforms back into a juvenile benthic polyp stage when faced with adverse conditions. Turritopsis sp.5 is a species of Turritopsis collected from Xiamen, China which presents a similar ability, being able to reverse its life cycle if injured by mechanical stress...
2018: PeerJ
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