Isolation of two novel neuropeptides from sea anemones: the unusual, biologically active L-3-phenyllactyl-Tyr-Arg-Ile-NH2 and its des-phenyllactyl fragment Tyr-Arg-Ile-NH2

Using a radioimmunoassay for the carboxyl-terminal sequence Arg-Val-NH₂, two novel peptides were purified from extracts of the sea anemone Anthopleura elegantissima. These peptides were L-3-phenyllactyl-Tyr-Arg-Ile-NH₂ (name: Antho-RIamide I) and its des-phenyllactyl fragment Tyr-Arg-Ile-NH₂ (Antho-RIamide II). Immunocytochemical staining showed that these peptides were localized in neurons of sea anemones. Application of low concentrations (10⁻⁸ M) of Antho-RIamide I inhibited spontaneous contractions in several muscle groups of sea anemones, whereas Antho-RIamide II was inactive. Antho-RIamide I is the second neuropeptide from sea anemones that bears the unusual, amino-terminal L-3-phenyllactyl blocking group. We suggest that this group renders the peptide resistant against degradation by nonspecific aminopeptidases. In addition, the L-3-phenyllactyl residue might also play a role in receptor binding.     

Catecholamines in the coelenterate Renilla köllikeri

Summary The characteristics of uptake of ³H-noradrenaline (³H-NA) and ³H-adrenaline (³H-A) in the tissues of the sea pansy, Renilla köllikeri, were studied by in vivo incubations. Lineweaver-Burk plots indicated two components of catecholamine accumulation, one representing a high-affinity uptake with an apparent K _m of 4.91×10^-7 M (³H-NA) or 4.39×10^-7 M (³H-A), and the other a low affinity process with an apparent Km of 5.52×10^-5 M (³H-NA) or 1.49×10^-5 M (³H-A). The high-affinity uptake of both tracers was strongly inhibited at low temperature and in a calcium-free medium, thus suggesting the involvement of a carrier-mediated transport mechanism, but was largely insensitive to sodium omission and ouabain. Accumulations of ³H-NA, but not ³H-A, were highly desipramine-sensitive.Light-microscopic radioautographic studies demonstrated the presence of cells reactive to both ³H-NA and ³H-A in the ectoderm, mesoglea and endoderm. Extraneuronal accumulations of ³H-NA and ³H-A were prominent in some ectodermal cells, in amoebocytes and spicule cells. Reactive neuronal processes were tentatively identified throughout the mesoglea and over all muscle layers on the basis of several morphological criteria. ³H-A, but not ³H-NA label, was more intense over the presumed photocytic zone and circular muscle than elsewhere. These and other observations support a neurotransmitter role for adrenaline (and probably noradrenaline) in control of luminescence and modulation of slow rachidial contractions.Supported by a grant from the Natural Sciences and Engineering Research Council of Canada     

Morphology,ultrastructure, and development of the parasitic larva and its surrounding trophamnion of Polypodium hydriforme Ussov (Coelenterata)

Summary The larval stage of Polypodium hydriforme is planuliform and parasitic inside the growing oocytes of acipenserid fishes. The larva has inverted germ layers and a special envelope, the trophamnion, surrounding it within the host oocyte. The trophamnion is a giant unicellular provisory structure derived from the second polar body and performing both protective and digestive functions, clearly a result of adaptation to parasitism. The trophamnion displays microvilli on its inner surface, and irregular protrusions anchoring it to the yolk on its outer surface. Its cytoplasm contains long nuclear fragments, ribosomes, mitochondria, microtubules, microfilaments, prominent Golgi bodies, primary lysosomes, and secondary lysosomes with partially digested inclusions.The cells of the larva proper are poorly differentiated. No muscular, glandular, neural, interstitial, or nematocyst-forming cells have been found. The entodermal (outer layer) cells bear flagella and contain rough endoplasmic reticulum; the ectodermal (inner layer) cells lack cilia and contain an apical layer of acid mucopolysaccharid granules. The cells of both layers contain mitochondria, microtubules, and Golgi bodies; their nuclei display large nucleoli with nucleolonema-like structure, decondensed chromatin, and some perichromatin granules. At their apical rims, the ectodermal cells form septate junctions; laterally, the cells of both layers form simple contacts and occasional interdigitations. The lateral surfaces of entodermal cells are strengthened by microtubules.     

Cellular events in the reestablishment of a symbiosis between a marine dinoflagellate and a coelenterate

Summary Within 24 h after the initial phagocytotic uptake of freshly isolated (from host tissue) symbiotic algae (Symbiodinium microadriaticum) by the endodermal cells of the polyp (scyphistoma) stage of the jellyfish Cassiopeia xamachana, the algal population was observed to decline despite evidence of algal cell division. Analyses of the frequency of phago-lysosome fusion as an indicator of possible attempts of the host to digest the algae indicated that, although phago-lysosome fusion did occur, the low frequency of occurrence is inconsistent with the interpretation that the animals digested the algae. Animal cell lysosomes were located predominantly at the apices of the endodermal cells, and the symbiotic algae were transported toward the bases of the endodermal cells.Within 3 days after initial infection, most endodermal cells with algae ceased to be phagocytotically active (with respect to the uptake of carmine particles). Many of these endodermal cells soon migrated into the mesoglea to become what are traditionally referred to as amoebocytes. Within amoebocytes the algae proliferated. The onset of strobilation by the scyphistomae was directly correlated with the increase in the algal population within these amoebocytes.     

Changes in the distribution of filament-containing septate junctions as coelenterate myoepithelial cells change shape

This paper describes the redistribution of septate junctions during an increase in diameter of myoepithelial cells from mesenteries of the sea anemone Metridium senile (L). Each septum was composed of a filament core, 9.5-10.2 nm in diameter, which had a double row of lateral projections from each side to the adjacent cell membrane. Septa were arranged in patches in which neighbouring septa lay parallel, 28-33 nm apart. When anaesthetized mesenteries were stretched, myoepithelial cell layers decreased from a mean of 32 to 8 micron thick; each cell shortened and its apical diameter increased. The integrity of the septate junctions was, however, maintained. The mean perimeter of septate junctions, corresponding to that of the cells, increased from 20 to 31 micron; mean depth decreased from 3.7 to 2.1 micron. There was no significant change in spacing between septa. Patches of septa, free to move in a fluid matrix of junction cell membranes, may form mobile attachment sites between cells, thus allowing those cells to change shape. Number and distribution density of microvilli decreased when cell diameter increased. This implies that the microvilli contribute membrane to the cell surface as its surface area increases. Gastrodermal cells are compared with epidermal cells that do not undergo dramatic changes in diameter.     

腔肠动物平衡感觉器官结构的研究进展

本文概述了腔肠动物的平衡感觉器官结构：刺胞动物掌状伞形螅（Corymorpha palma）固着器末端的无纤毛平衡囊、软水母（Leptomedusae）钟形伞缘的开放型和封闭型平衡囊、筐水母（Narcomedusae）外伞表面外伞神经环上方边缘有感觉棍的间囊水母（Aegina）和有感觉乳突及感觉棍的嗜阳水母（Solmissus）的平衡囊、硬水母（Trachymedusae）外伞神经环上方边缘的平衡囊、钵水母（Scyphozoa）伞缘的感觉棍和立方水母（Cubozoa）伞缘稍上方的感觉棍,栉水母（Ctenophore）反口面中央的平衡囊或顶器官。本文内容对理解其他水生无脊椎动物的平衡感觉器官的结构及功能有重要意义,同时也可能作为对现行动物学相关教材内容的有益补充。     

Helical fibrils in the mesoglea of a hydropolyp

A hitherto unknown type of helical fibrils has been detected in the mesoglea of Myriothela cocksi. In the heads of the tentacles these fibrils occur in bundles and are especially well developed in the mesoglea of the mouth tentacles. From the structure of the bundles, from their extension, and from an associated increased number of nematocytes with a strong pedicel in the mouth tentacles it is suggested that the fibril bundles play a supportive role in nematocyte attachment.     

Coelenterate organs

Cnidaria and ctenophores, though of the ‘tissue grade of construction’, can form organs of considerable complexity, for example the prehensile tentilla of Euplokamis, the erupting nematocyst batteries of the siphonophores Stephanophyes and Nanomia and the complex eyes of cubomedu‐sae such as Carybdea and Tripedalia. The polypoid and medusoid members of siphonophore colonies are functionally equivalent to organs and may be considered as ‘zooid‐derived organs’. There is no reason to regard the lack of a single, dominant nerve centre as a factor constraining organ development in coelenterates.