Larval development and metamorphosis of Sabellaria cementarium Moore, 1906 (Polychaeta: Sabellariidae)

1985 ◽  
Vol 63 (5) ◽  
pp. 1037-1049 ◽  
Author(s):  
Peter R. Smith ◽  
Fu-Shiang Chia
Keyword(s):  
Substrate Specificity ◽  
Larval Development ◽  
Thoracic Segment ◽  
Beach Sand ◽  
Larval Behavior ◽  
Caudal Appendage ◽  
Apical Tuft ◽  
Low Degree ◽  
Settlement And Metamorphosis ◽  
65 H

The development of the polychaete Sabellaria cementarium Moore, 1906 proceeds at 10–14 °C, as follows: 23 h, early trochophore with prototroch and apical tuft; 65 h, 1 pair of provisional setae; 3.5 days, feeding trochophore; 18 days, metatrochophore; 4 weeks, metatrochophore with tentacle buds; 5–6 weeks, nectochaeta competent to metamorphose; 6–8 weeks, settlement and metamorphosis. Larval behavior is described. Tube sand of adult sabellariids (S. cementarium, Phragmatopoma lapidosa, ldanthrysus ornamentatus) and beach sand induced metamorphosis. Larvae exhibit a low degree of substrate specificity in their settlement, but sand is essential. Metamorphosis involves a loss of provisional setae, anterior rotation of tentacles and opercular cirri, and reduction of episphere. Following these changes, the juvenile secretes a mucoid tube to which sand grains are attached. Metamorphosis is considered complete when the caudal appendage has formed; this occurs 7–10 days postsettlement. Juveniles were kept in the laboratory for 38 days. During this time, they develop three pairs of tentacles, lose all larval pigment, and form a second thoracic segment. Within the opercular crown, primary opercular paleae replace settling paleae.

Fasciola hepatica larval development within the intermediate host.

2021 ◽  
pp. 23-64
Author(s):  
Gilles Dreyfuss ◽  
Philippe Sindou ◽  
Philippe Hourdin ◽  
Philippe Vignoles ◽  
Daniel Rondelaud
Keyword(s):  
Intermediate Host ◽  
Larval Development ◽  
Fasciola Hepatica ◽  
Parasitic Infections ◽  
Snail Species ◽  
Larval Behavior ◽  
Host Snail

Abstract This book chapter focuses on host snail species and larval behavior forms in snails, and features of parasitic infections in naturally or experimentally infected snails, or in coinfected snails.

The oncomiracidium and post-oncomiracidial development of the hexabothriid monogenean Rajonchocotyle emarginata

Parasitology ◽  
1970 ◽  
Vol 60 (3) ◽  
pp. 457-479 ◽  
Author(s):  
Maureen Wiskin
Keyword(s):  
Embryonic Development ◽  
Larval Development ◽  
Posterior Part ◽  
Reproductive Organs ◽  
Marginal Hook ◽  
The Other ◽  
Caudal Appendage ◽  
Biological Association ◽  
Marine Biological Association ◽  
Posterior Anterior

SUMMARYA description is given of some features of the embryonic development, the structure of the oncomiracidium and the postlarval development of R. emarginata, a hexabothriid parasite on the gills of Raia clavata.There are three phases in the larval development of the haptor of Rajonchocotyle: an oncomiracidial or marginal hook stage, a hamulus stage and a sucker stage. Neither the embryo nor the oncomiracidium ever possesses more than five pairs of marginal hooks and marginal hooks I (the posterior-most pair) are considered to be missing. The marginal hooks develop within distinct binucleate oncoblasts. During the early stages of post-oncomiracidial growth the secondary attachment organs of the haptor are formed and it is only after the completion of the development of the haptor that the reproductive organs begin to appear. Firstly, a pair of hamuli is acquired, followed by four pairs of suckers, which form in posterior-anterior succession at the site of marginal hooks III-VI. The first pair of suckers remains unarmed while the other three pairs acquire hooked sclerites and become the main functional attachment organs of the adult. As the first pair of suckers appears the posterior part of the haptor lengthens to form a caudal appendage. Hexabothriids are considered to show closer affinity to the 8-suckered chimaericolids and diclidophorids than to the 6-suckered polysto-matids, the unarmed suckers representing a simplification, by loss of the sclerite and reduction in sucker size, of an originally armed sucker.I would like to express my thanks to Dr J. Llewellyn for his interest and for much helpful discussion.Thanks are also due to the Director and Staff of the Marine Biological Association at Plymouth, in particular Mr J. E. Green for material and assistance, and to Dr A.j Brinkmann, of the Department of Zoology, University of Bergen, for supplying specimens of Squalonchocotyle borealis.

scholarly journals The Larval Development of Ophelia Bicornis Savigny

1948 ◽  
Vol 27 (3) ◽  
pp. 540-553 ◽  
Author(s):  
Douglas P. Wilson
Keyword(s):  
Larval Development ◽  
Text Book ◽  
Apical Tuft ◽  
The Third ◽  
Solid Objects ◽  
The Family ◽  
First Time ◽  
Anal Papillae

Fertilizations of Ophelia bicornis Savigny were made and the larvae reared. This is the first time the larval development of any member of the family Opheliidae has been described.The trochosphere is small and somewhat yolky; it has a broad prototroch, a narrow telotroch, a strong apical tuft and a long anal cilium.Annulation is accompanied by the appearance of parapodial lobes and bristles. When the first pair of bristles of the third setiger protrude the larva is ready to metamorphose. It has two, sometimes three eyes.The larva in its later stages can adhere strongly to solid objects, such as sand grains, by a secretion from the four anal papillae and the parapodial lobes. This is interpreted as an adaptive aid to settlement on sand banks swept by strong currents.At metamorphosis the larval external cilia are lost and the bristles rapidly elongate, especially those of the third setiger.Some of the larval bristles are slightly winged. So far only capillary bristles have been known in the Opheliidae.It is pointed out that a development such as that of Ophelia is more typical of polychaetes as a whole than are the developments of certain species commonly used as text-book types.

Larval development and metamorphosis of the serpulid polychaete Galeolaria caespitosa Lamarck

1981 ◽  
Vol 32 (4) ◽  
pp. 667 ◽  
Author(s):  
JR Marsden ◽  
DT Anderson
Keyword(s):  
Food Intake ◽  
Larval Development ◽  
The Other ◽  
Head Region ◽  
Larval Body ◽  
Rapid Succession ◽  
Apical Tuft ◽  
Larval Behaviour ◽  
Causal Processes ◽  
Shape Changes

Larval behaviour in G. caespitosa is described from trochophore to settled juvenile. The trochophore swims, spiralling counterclockwise, with the apical tuft outstretched. Large cilia on the lips of the mouth assist in food intake. Two sphincter muscles control passage of food along the gut. By 4-5 days; the trochophore has circular, oblique, radial and longitudinal larval muscles. The radial muscles move the apical tuft. The other muscles brace the larval body and assist the passage of food through the gut. At 6-7 days the larva becomes demersal. Feeding and growth continue. At 8-9 days three pairs of setal sacs develop in rapid succession. Metamorphosis now takes place. beginning at 11 days with collapse of the prototroch. Tentacle buds and thoracic membrane rudiments develop even if settlement is not achieved. Other events of metamorphosis (collar evagination, tube secretion. tentacle growth and shrinkage of the head region) require prior settlement. Larval muscles play a part in the shape changes occurring during metamorphosis. Settlement conditions are complex and may include a response to light-coloured surfaces. Development to the three- setiger stage appears to be genetically preprogrammed. Metamorphosis and settlement must involve an interplay of several internal and external causal processes in a sequential manner.

A description of the embryology, larval development, and feeding of the sea anemones Anthopleura elegantissima and A. xanthogrammica

1974 ◽  
Vol 52 (11) ◽  
pp. 1383-1388 ◽  
Author(s):  
Arthur E. Siebert Jr.
Keyword(s):  
Larval Development ◽  
Phylogenetic Significance ◽  
Sea Anemones ◽  
Apical Tuft ◽  
Anthopleura Elegantissima ◽  
Anthopleura Xanthogrammica

The embryology of Anthopleura elegantissima and Anthopleura xanthogrammica is described. Ova of A. elegantissima are 120–150 μm in diameter and brown, while those of A. xanthogrammica are 175–225 μm in diameter and purple. In both species, cleavage is complete and equal: endoderm formation is by emboly. The planulae of both species are similar in appearance and are 150–250 μm in length with an apical tuft 60–75 μm in length. Feeding of the planulae is discussed, as is the function and phylogenetic significance of the apical sensory tuft of the planula.

Substrate specificity and inducibility of TACE (tumour necrosis factor α-converting enzyme) revisited: the Ala-Val preference, and induced intrinsic activity

2003 ◽  
Vol 70 ◽  
pp. 39-52 ◽  
Author(s):  
Roy A. Black ◽  
John R. Doedens ◽  
Rajeev Mahimkar ◽  
Richard Johnson ◽  
Lin Guo ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Recent Work ◽  
Tumour Necrosis Factor ◽  
Tumour Necrosis ◽  
Transforming Growth Factor ◽  
Intrinsic Activity ◽  
Converting Enzyme ◽  
Tumour Necrosis Factor Α ◽  
Factor Α ◽  
Necrosis Factor

Tumour necrosis factor α (TNFα)-converting enzyme (TACE/ADAM-17, where ADAM stands for a disintegrin and metalloproteinase) releases from the cell surface the extracellular domains of TNF and several other proteins. Previous studies have found that, while purified TACE preferentially cleaves peptides representing the processing sites in TNF and transforming growth factor α, the cellular enzyme nonetheless also sheds proteins with divergent cleavage sites very efficiently. More recent work, identifying the cleavage site in the p75 TNF receptor, quantifying the susceptibility of additional peptides to cleavage by TACE and identifying additional protein substrates, underlines the complexity of TACE-substrate interactions. In addition to substrate specificity, the mechanism underlying the increased rate of shedding caused by agents that activate cells remains poorly understood. Recent work in this area, utilizing a peptide substrate as a probe for cellular TACE activity, indicates that the intrinsic activity of the enzyme is somehow increased.

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