Transcriptional characterisation of the Exaiptasia pallida pedal disc

Background Biological adhesion (bioadhesion), enables organisms to attach to surfaces as well as to a range of other targets. Bioadhesion evolved numerous times independently and is ubiquitous throughout the kingdoms of life. To date, investigations have focussed on various taxa of animals, plants and bacteria, but the fundamental processes underlying bioadhesion and the degree of conservation in different biological systems remain poorly understood. This study had two aims: 1) To characterise tissue-specific gene regulation in the pedal disc of the model cnidarian Exaiptasia pallida, and 2) to elucidate putative genes involved in pedal disc adhesion. Results Five hundred and forty-seven genes were differentially expressed in the pedal disc compared to the rest of the animal. Four hundred and twenty-seven genes were significantly upregulated and one hundred and twenty genes were significantly downregulated. Forty-one condensed gene ontology terms and 19 protein superfamily classifications were enriched in the pedal disc. Eight condensed gene ontology terms and 11 protein superfamily classifications were depleted. Enriched superfamilies were consistent with classifications identified previously as important for the bioadhesion of unrelated marine invertebrates. A host of genes involved in regulation of extra cellular matrix generation and degradation were identified, as well as others related to development and immunity. Ab initio prediction identified 173 upregulated genes that putatively code for extracellularly secreted proteins. Conclusion The analytical workflow facilitated identification of genes putatively involved in adhesion, immunity, defence and development of the E. pallida pedal disc. When defence, immunity and development-related genes were identified, those remaining corresponded most closely to formation of the extracellular matrix (ECM), implicating ECM in the adhesion of anemones to surfaces. This study therefore provides a valuable high-throughput resource for the bioadhesion community and lays a foundation for further targeted research to elucidate bioadhesion in the Cnidaria.

Transcriptional characterisation of the Exaiptasia pallida pedal disc

Background Biological adhesion (bioadhesion), enables organisms to attach to surfaces as well as to a range of other targets. Bioadhesion evolved numerous times independently and is ubiquitous throughout the kingdoms of life. To date, investigations have focussed on various taxa of animals, plants and bacteria, but the fundamental processes underlying bioadhesion and the degree of conservation in different biological systems remain poorly understood. This study had two aims: 1) To characterise tissue-specific gene regulation in the pedal disc of the model cnidarian Exaiptasia pallida, and 2) to elucidate putative genes involved in pedal disc adhesion. Results Five hundred and forty-seven genes were differentially expressed in the pedal disc compared to the rest of the animal. Four hundred and twenty-seven genes were significantly upregulated and one hundred and twenty genes were significantly downregulated. Forty-one condensed gene ontology terms and 19 protein superfamily classifications were enriched in the pedal disc. Eight condensed gene ontology terms and 11 protein superfamily classifications were depleted. Enriched superfamilies were consistent with classifications identified previously as important for the bioadhesion of unrelated marine invertebrates. A host of genes involved in regulation of extra cellular matrix generation and degradation were identified, as well as others related to development and immunity. Ab initio prediction identified 173 upregulated genes that putatively code for extracellularly secreted proteins. Conclusion The analytical workflow facilitated identification of genes putatively involved in adhesion, immunity, defence and development of the E. pallida pedal disc. When defence, immunity and development-related genes were identified, those remaining corresponded most closely to formation of the extracellular matrix (ECM), implicating ECM in the adhesion of anemones to surfaces. This study therefore provides a valuable high-throughput resource for the bioadhesion community and lays a foundation for further targeted research to elucidate bioadhesion in the Cnidaria.

Transcriptional characterisation of the Aiptasia pallida pedal disc

Background Biological adhesion (bioadhesion), enables organisms to attach to surfaces as well as to a range of other targets. Bioadhesion evolved numerous times independently and is ubiquitous throughout the kingdoms of life. To date, investigations have focussed on various taxa of animals, plants and bacteria, but the fundamental processes underlying bioadhesion and the degree of conservation in different biological systems remain poorly understood. This study had two aims: 1) To characterise tissue-specific gene regulation in the pedal disc of a basal metazoan; the model cnidarian Aiptasia pallida, and 2) to elucidate the specific genes involved in pedal disc adhesion. Results Five hundred and forty-seven genes were differentially expressed in the pedal disc compared to the rest of the animal. Four hundred and twenty-seven genes were significantly upregulated and one hundred and twenty genes were significantly downregulated. Forty-one condensed gene ontology terms and 19 protein superfamily classifications were enriched in the pedal disc. Eight condensed gene ontology terms and 11 protein superfamily classifications were depleted. Enriched superfamilies were consistent with classifications identified previously as important for the bioadhesion of unrelated marine invertebrates. A host of genes involved in regulation of extra cellular matrix generation and degradation were identified, as well as others related to development and immunity. Ab initio prediction identified 173 upregulated genes that putatively code for extracellularly secreted proteins. Conclusion The analytical workflow facilitated identification of genes involved in adhesion, immunity, defence and development of the A. pallida pedal disc. When defence, immunity and development-related genes were identified, those remaining corresponded most closely to formation of the extracellular matrix (ECM), implicating ECM in the adhesion of anemones to surfaces. This study therefore provides a valuable high-throughput resource for the bioadhesion community and lays a foundation for further targeted research to elucidate bioadhesion in the Cnidaria.

Tenactisgen. nov. (Actiniaria, Haloclavidae) a new genus of sea anemones from the Gulf of California, Mexico

We describe and illustrate a new genus and species of sea anemone from the intertidal in the Gulf of California (Mexico).Tenactisgen. nov. is characterized by mesenteries decamerously arranged, a single pair of directives attached to a single and strong siphonoglyph, small conchula, endodermal marginal sphincter muscle, pedal disc with basilar muscles, cinclides in pedal disc and proximal column, column with verrucae and pseudoacrorhagi, and a cnidom withp-mastigophores A2 andp-mastigophores B1 and B2a.Tenactis riosmenaigen. et sp. nov. is characterized by having a column not divisible into regions with longitudinal rows of verrucae distally and pseudoacrorhagi forming spherical structures at the tip, only 10 pairs of perfect mesenteries, diffuse endodermal marginal sphincter muscle andp-mastigophores A2 andp-mastigophores B1 and B2a in the filaments. Because of the decamerous arrangement of the mesenteriesTenactisgen. nov. most closely resembles some members of Actiniidae, Haloclavidae, Minyadidae, Oractiidae and Limnactinidae (Actinioidea), Halcampidae (Metridioidea) and Halcuriidae (Actinernoidea). However, the combination of having a decamerous arrangement of mesenteries, single siphonoglyph, conchula and cinclides indicate this new genus belongs to Haloclavidae. Additionally, the presence of a diffuse endodermal marginal sphincter muscle, basilar muscles, a single pair of directives, column with longitudinal rows of verrucae distally and pseudoacrorhagi,p-mastigophores A2, andp-mastigophores B1 and B2a in the filaments distinguishTenactis riosmenaigen. et sp. nov. within Haloclavidae. This is the first record of the family Haloclavidae for the Gulf of California.

Actinia ebhayiensis sp. nov., a new species of sea anemone (Anthozoa: Actiniaria: Actiniidae) from South Africa

In this work we describe Actinia ebhayiensis sp. nov. from South Africa. The species is externally similar to the type species of the genus, Actinia equina, from which it can be distinguished by nematocyst and allozyme data. Actinia ebhayiensis has a smooth, red column, with well-delimited parapet leading to a deep fosse where conspicuous blue acrorhagi can be found. Tentacles and oral disc are crimson red, and the pedal disc has a lighter pink colour. The microbasic p-mastigophores and b-mastigophores of the mesenterial filaments of the new species are significantly smaller than those of A. equina. Actinia ebhayiensis can also be clearly distinguished from other species of the genus in nematocyst measurements, genetic data and muscle morphology.

Basal-disc creeping combined with rotation, an undescribed behaviour with preferred directionality in bivalve-inhabiting hydrozoans (Cnidaria: Hydrozoa: Leptomedusae)

A creeping movement, which often results in clockwise or counterclockwise bodily rotation, is described for ordinary zooids of two species of bivalve-inhabiting hydrozoans, Eutima japonica Uchida and Eugymnanthea japonica Kubota, attached to artificial hard substrata (polystyrene and glass) in the laboratory. Time-lapse video recordings furthermore showed that the non-transparent half of the flat, ellipsoidal pedal disc always faces forward during this motion, with no lateral or backward creeping during either day or night. Because an ordinary zooid generally crept in a circle of small radius, the zooid's body rotated as the creeping proceeded. One full rotation of a zooid of either species took about 5–6 hours on average at 21–25°C. The direction of rotation of an individual zooid was nearly constant irrespective of developmental state, this being true for zooids with or without a medusa bud on the hydrocaulus or a daughter zooid on the pedal disc, those with a normal or a double hydranth, or those consisting of a bare hydrocaulus. Asexually produced tiny daughter zooids quickly became well separated from their mother zooids. The attachment site of the latter did not shift much as they rotated, but daughter zooids and other tiny free zooids creep along a nearly straight line, thereby markedly shifting their position. This may contribute to the prevention of crowding of zooids in the restricted space between soft body parts in the host bivalve's mantle cavity.

Relative Intraspecific Aggressiveness of Pedal Disc Colour Phenotypes of the Beadlet Anemone, Actinia Equina

Anemones of the genus Actinia exhibit a well documented, stereotyped aggressive sequence (Bonnin, 1964; Brace & Pavey, 1978; Brace et ah, 1979) involving specialized, nematocyst-bearing structures called acrorhagi, which can be directed against an opponent. Experiments on the Australian species, A. tenebrosa Farquhar, and on the clonal anemone, Anthopleura elegantissima (Brandt) (which similarly bears acrorhagi), indicate that aggression occurs principally between genetically dissimilar (allogeneic) opponents (Ayre, 1982; Francis, 1973a, b; Bigger, 1980). Once acrorhagial contact has been made with an allogeneic individual, massive discharges of nematocysts ensue, which can cause severe necrotic lesions.