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Breeding and development have been studied in a number of sipunculans, includingGolfingia elongata(Keferstein),G. vulgaris(de Blainville),G. minuta(Keferstein),G. pugettensisFisher,Phascolosoma agassiziKeferstein,Phascolopsis gouldi(Pourtalès),Themiste pyroides(Chamberlin),Phascolion strombi(Montagu) andSipunculus nudusL. (see Åkesson, 1958, 1961; Gerould, 1903, 1904, 1906; Hatschek, 1884; Rice, 1967; Selenka, 1875). However, the annual cycle of gametogenesis has been investigated in very few sipunculans, notablyG. vulgaris(Gonse, 1956a, b, 1957a, b) andP. agassizi(Towle & Giese, 1966, 1967).

SUMMARY Trie gregarines of Sipunculus, so often recorded during the last hundred years, prove to belong to two or more species of the genera Urospora and Lithocystis, and further information especially about the gametes and zygotes is much needed. The structure of the spores, the most diagnostic feature of gregarines, forces one to recognize three species, viz. Urospora Mgeri, U. hardyi, and Lithocystis lankesteri, as distinct from the original U. sipunculi Koll. "\ /TORE than a hundred years ago Kolliker (1848) described a parasite of JLVA the coelom of Sipunculus nudus from Naples which he called Gregarina sipunculi. He appears only to have examined a few specimens of S. nudus; one contained trophozoites described as generally roundish or pear-shaped, smooth, and active, later becoming associated and approximately spherical (see his Figs. 1-3); another specimen had many cysts near its posterior end, each containing numerous oval spores with thread-like tails rather more than half as long again as the spores themselves (his Fig. 4a). There is little doubt that this parasite should be put in Schneider's (1875) genus Urospora as U. sipunculi Koll., in spite of its being less elongated than most Urospora, and, as I pointed out (1915, p; 99), it requires much further study. Lankester working in Naples in the winter of 1871-2 on the anatomy of S. nudus had found numerous specimens infected with gregarines, and some of the spores drawn by him (Fig. 6 b, c), probably represent the above species. However, he described, p. 348, another spore found on various occasions, with a long 'shred-like filament dependent from one extremity, which is perfectly motionless'. This gregarine, which I was able to examine alive in Naples, 1929 (Text-fig. 3), should belong almost certainly to the genus Lithocystis (Giard 1876) and I propose to call it L. lankesteri for the present. Lankester said that the spores were preceded by spherical corpuscles; these were undoubtedly gametes or zygotes and presumably motionless, but apparently neither he nor any subsequent worker has been able to examine them alive, so that we do not know for certain that they are motionless, as are those of other Lithocystis (emended characteristics, Pixell Goodrich, 1915, 1925). From January to June 1921 A. C. Hardy was working in Naples, and some S. nudus he examined were infected with parasites. Among these were motile trophozoites of two distinct gregarines—one with a spiny cuticle (Text-fig. 1, A and B), the other smooth and squirming (Text-fig. 2); but, as no spores were

Determination of carboxyl-terminal residues of two arginine kinases (ATP: l -arginine phosphotransferases, EC 2.7.3.3) has been carried out by hydrazinolysis and carboxypeptidase digestion. On the basis of evidence obtained by these two methods, their carboxyl terminal sequences are concluded to be valylmethionine for Homarus vulgaris arginine kinase and leucyllysine for Sipunculus nudus arginine kinase. By studying the number of C-terminal amino acids released, evidence is provided that the Homarus vulgaris enzyme (mol. wt. 43 000) consists of a single polypeptide chain and that the Sipunculus nudus enzyme (mol. wt. 86 000), like creatine kinase, consists of two subunits.

ATP:l-arginine phosphotransferase has been isolated from Sipunculus nudus muscle; the preparation is homogeneous to analytical centrifugation, molecular sieving on Sephadex G-100 and electrophoresis on cellogel and on polyacrylamide discs. Treated by 8 M urea, arginine phosphokinase from Sipunculus is dissociated into two subunits having the same molecular weight whereas arginine kinase from lobster gives no dissociation evidence. Furthermore the number of peptides shown on fingerprints of the tryptic hydrolysate of the first enzyme amounts to half of its lysine plus arginine residues. The enzyme from Sipunculus is named arginine kinase type II, to be distinguished from that of molecular weight near 40 000 (arginine kinase type I) and from that of molecular weight 160 000 (arginine kinase type III). Unlike arginine kinase type I which contains 6 total SH groups and a single reactive and essential SH, arginine kinase type II is found to have 12 total thiols and 6 SH groups reacting at the same rate with 5,5′-dithio-bis-(2-nitrobenzoic) acid or with N-ethylmaleimide. From the numerous thiols similarly exposed results the particular autooxydisability and lability of the enzyme on study. No evidence is shown of the content of the disulfide bridges. Like arginine kinase type I, arginine kinase type II is strictly specific. The kinetics of the reaction are the same for both: no cooperative effect is observed between guanidine and nucleotide substrates fixation on the enzymes.

Arginine kinase has been purified from body-wall muscle of a marine polychaetous annelid, Sabella pavonina. The preparation is homogeneous to analytical ultracentrifugation and disc electrophoresis on polyacrylamide gel. The enzyme is labile and undergoes a rapid decrease of its specific activity, even in the presence of protecting agents. The molecular weight of the native enzyme is 150 000 ± 5000, the sedimentation coefficient s°20,b being found to be equal to 7.5. Unlike the enzyme from lobster muscle (mol. wt ≃ 43000) and that from Sipunculus nudus muscle (mol. wt ≃ 83000), the phosphokinase from Sabella pavonina muscle is not strictly specific towards l-arginine. The enzyme shows no optical isomer specificity and is slightly active on a number of analogues of l-arginine, the integrity of the guanidine and carboxylic groups of which is indispensable to their activity. The enzyme is strictly specific for the nucleotidic substrate ATP. Partial isotopic exchange and kinetic studies suggest that the reaction mechanism is somewhat different from that described for sea-water crustacean muscle arginine kinase and more similar to that reported for other phosphagen phosphokinases.

A detailed description of both rotatory dispersion and circular dichroism of oxy- and deoxyhemerythrin from Sipunculus nudus is reported. In the visible region, the deoxygenated form shows complete absence of active transitions, while three negative dichroic bands, centered at 520,430 and 340 nm, are present in the oxygenated derivative. These bands, attributable to an oxygenated iron chromophore, agree with the Cotton effects exhibited by the dispersion curves of hemerythrin; two dichroic bands (those centered at 520 and at 340 nm) show a clear red shift of their maxima with respect to those of the corresponding absorption spectra. In the 350–250 nm region, both oxy- and deoxyhemerythrin show several dichroic bands with marked differences between the spectra of the two derivatives; a small difference can also be detected in the dispersion curves. These data, in conjunction with difference spectra, are suggestive of a reorientation of aromatic side chains upon O 2 binding, although an implication of optically active transitions of the iron cannot be ruled out. The two derivatives of hemerythrin have the same far ultraviolet dispersion curves and circular dichroism spectra, thus excluding gross conformational changes of the protein backbone upon ligand binding.

Solen ensisensis muscle arginine kinase (ATP : l -arginine phosphotransferase, EC 2.7.3.3.) was isolated in an homogeneous state. Its molecular weight was found to be about 80 000. The properties of this enzyme were compared with those of arginine kinase from Sipunculus nudus , an enzyme which also has a molecular weight of about 80 000 Both enzymes have several reactive thiol groups (8 thiol groups in the Solen kinase and 12 in the Sipunculus enzyme were titrateable with 5,5′- dithio -bis-(2- nitrobenzoic ) acid and histidine residues (both enzymes have 6 reactive histidine residues). These kinases were, therefore, highly susceptible to oxidation. Both enzymes show the same pH optimum and absolute specificity towards the guanidine substrate, l -arginine. The reaction kinetics of both enzymes are of the sequential type. In the presence of α-aminoacids or Mg 2+ -ADP, similar spectral effects were obtained. The enzymes differ in their enzymic activities and in their rate of recovery following urea denaturation. The most important difference that appeared to be a special feature of the Sipunculus enzyme is that the spectrum of the Mg 2+ -ADP-enzyme complex is strongly intensified by l -arginine.

This note reports upon the eighteen species of sipunculans from the coast of the Gulf of Tonkin. Detailed descriptions of Physcosoma albolineatum, Physcosoma scolops, Physcosoma nigrescens, Physcosoma pacificum, Physcosoma lurco, Physcosoma pelma, Siphonosoma cumanense, Siphonosoma australense, Sipunculus nudus, Sipunculus discrepans, Sipunculus robustus, Sipunculus phalloïdes, Aspidosiphon aspergillum, Aspidosiphon steenstrupii, Aspidosiphon exilis., Lilhacrosiphon, Dendrostoma Signifer are given.

The relationship between coelomic pressures and body movements has been investigated in Phascolosoma gouldi and, mainly, Sipunculus nudus.During "defense movements, pressure in Phascolosoma is commonly 50 cm. of water, in Sipunculus 70 to 80 cm. During "defense immobility," the highest pressure recorded, in Phascolosoma, was 108 cm. There does not seem to be a relation between body size and maximum pressure.Six phases of burrowing movements have been distinguished in Sipunculus and related to coelomic pressure. An important pressure rise coincides with a bending movement of the central part the body. This "hump" and the high pressures associated with it have functions which are described. Very low coelomic fluid pressures suffice to cause evension of the proboscis. Pressure is a necessary and sufficient condition for proboscis eversion in free water, while in sand the proboscis muscles seem to play an essential role during proboscis eversion in relation to the thixotropic property of stirred sand.During m...

IN the winter of 1871–2 I studied the richly corpusculated perivisceral fluid of Sipunculus nudus at Naples. I was with Anton Dohrn, who was making arrangements for the building of his celebrated laboratory. That remarkable marine zoologist Krohn, who in 1851 had described the ciliated “urns” (Topfchen) of the body-fluid of Sipunculus as parasites, was there, and spent an evening with us. I described the ciliated urns briefly in the Annals and Mag. of Nat. Hist., vol. xi. (fourth series), 1873, p. 89, and pointed out their mode of origin. I say, “Further, I have found out the source of the ‘Topfchen.’ They are to be observed in great numbers attached within the curious pair of tubes or vessels formed by duplicatures of the peritoneal membrane, which lie on each side of the œsophagus”. I then give a wood-cut figure of the attached “urns” with long stalks, and state that “they develop as buttons on the cellular surface”, and that “they become detached and swim off into the fluid”.

RECOGNITION of foreign particles in invertebrates is shown by the sticking of these particles to the circulating free amoebocytes of the host. The marine invertebrate Sipunculus nudus, phylum Sipunculida, has among its coelomic fluid (‘blood’) cells a remarkable ‘urn cell’ which secretes mucus that is sticky for foreign cells, but not for autologous cells. We have studied the biological specificity of this phenomenon and have attempted to alter the surface of autologous erythrocytes to render them sufficiently ‘foreign’ to stick to urn mucus.

The total non-protein nitrogen in the excretory products of fasting specimens of Dendrostomum cymodoceae Edmonds was found to be 1.18-1.40 mg N/100 g wet wt./24 hr. Of the total nitrogen, 83-90 per cent. was excreted as ammonia nitrogen, 4-6 percent, as urea nitrogen, 0-4 percent. as amino acid nitrogen, and none as uric acid; 89-94 percent. of the nitrogen was thus accounted for. The results are compared with the corresponding values obtained by other workers for Sipunculus nudus and some other invertebrates.