SynopsisThe ultrastrrict,ural morphology and x-ray and electron diffract,ion of poly(Gly-Cr1y-Ala) have been studied. The polymer has two forms; the first, form I possesses a superfolded cross-p striictiire, long fibers of which show some twisting and intert,wining. Form I1 precipitates in a less dist.irict. fibroiis form from aqueous solut,ion. The x-ray diffraction and orient,ed electron diffraction dat,a suggest th%t, form I1 isba polyglyciAie I1 helix situated iii a monoclinic cell with dimensions a = I;.% A, b = 22.0 A, c = 9.42 A, and p = YO0. Combined with the morphological evidence it appears likely that form I1 is also in ail antiparallel superfolded array.

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In Polychaeta, as in many invertebrates, reproduction is controlled by both environmental and endocrine factors. Although the effects of environmental factors on reproductive behaviour are briefly discussed, this review focuses on the endocrinology of reproduction. As Nereidae are the most intensively studied polychaetes, their epigamic monotelic strategy is discussed first in this review. Although a large number of physiological observations have been made, biochemical data have been greatly lacking until recent years, except, however, for the recent isolation of several pheromones. These substances, such as uric acid and L-cysteine gluthathione disulfide, occur widely and must be present at high concentrations in order to exert their physiological effects. Results obtained from iteroparous species are also considered. The stolonization strategy of Syllidae, the control of vitellogenesis in Nephtyidae, Phyllodocidae, Polynoidae, and Cirratulidae, and the regulation of gamete maturation in Arenicolidae and Pectinariidae are discussed. As with Nereidae, our knowledge of endocrine control is mainly based on experimental data, since only spermmaturation factor in the genus Arenicola has been identified. Therefore, despite numerous interesting experimental studies in which functional roles for polychaete reproductive hormones have been described, their nature, their primary targets, and their mechanism of action are unfortunately still largely unknown.Résumé : Chez les polychètes, comme chez de nombreux invertébrés, la reproduction est sous le contrôle de facteurs de l'environnement et de facteurs endocriniens. L'objet essentiel de cette synthèse est le contrôle endocrinien de la reproduction; des données plus fragmentaires ont trait aux effets des facteurs environnementaux. Puisque les Nereidae sont les polychètes les mieux connus, l'étude de leur stratégie monotélique épigame est envisagée dans un premier point. Toutefois, malgré de nombreuses observations physiologiques, peu de données biochimiques sont disponibles, si l'on excepte l'isolement récent de plusieurs phéromones. Celles-ci, comme l'acide urique et le disulfure de L-cystéine glutathion, sont des substances ubiquistes qui, de ce fait, doivent être présentes en concentrations élevées afin de pouvoir exercer une action physiologique. Les résultats obtenus chez les espèces itéropares font l'objet d'un second point. La stratégie de stolonisation des Syllidae, le contrôle de la vitellogenèse des Nephtyidae, des Phyllodocidae, des Polynoidae et des Cirratulidae, ainsi que le contrôle de la maturation des gamètes des Arenicolidae et des Pectinariidae sont examinés. Comme dans le cas des Nereidae, notre compréhension du contrôle endocrinien repose essentiellement sur des données expérimentales. Seul est identifié le facteur de maturation des spermatozoïdes d'Arenicola. Ainsi, malgré les nombreuses études expérimentales réalisées chez les polychètes et les multiples actions hormonales décrites dans les processus de reproduction, la nature des hormones, leurs cibl...

In Polychaeta, as in many invertebrates, reproduction is controlled by both environmental and endocrine factors. Although the effects of environmental factors on reproductive behaviour are briefly discussed, this review focuses on the endocrinology of reproduction. As Nereidae are the most intensively studied polychaetes, their epigamic monotelic strategy is discussed first in this review. Although a large number of physiological observations have been made, biochemical data have been greatly lacking until recent years, except, however, for the recent isolation of several pheromones. These substances, such as uric acid and L-cysteine gluthathione disulfide, occur widely and must be present at high concentrations in order to exert their physiological effects. Results obtained from iteroparous species are also considered. The stolonization strategy of Syllidae, the control of vitellogenesis in Nephtyidae, Phyllodocidae, Polynoidae, and Cirratulidae, and the regulation of gamete maturation in Arenicolidae and Pectinariidae are discussed. As with Nereidae, our knowledge of endocrine control is mainly based on experimental data, since only sperm-maturation factor in the genus Arenicola has been identified. Therefore, despite numerous interesting experimental studies in which functional roles for polychaete reproductive hormones have been described, their nature, their primary targets, and their mechanism of action are unfortunately still largely unknown.

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