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  • 1
    Electronic Resource
    Electronic Resource
    Intraspecific variation in gametogenesis in two populations of the Chilean molluscan bivalve, Argopecten purpuratus (Lamarck) (1997)
    Oxford, UK : Blackwell Publishing Ltd
    Aquaculture research 28 (1997), S. 0 
    Details
    ISSN: 1365-2109
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: An increased understanding of the general biology of Argopecten purpuratus (Lamarck) is necessary to produce successfully high quality larvae in hatcheries and to collect enough spat in situ for growth on long lines. In the present study, the reproductive cycles of two populations of A. purpuratus were examined, the Mejillones and Rinconada scallop banks, from 1989 to 1993. Calculation of the gonosomatic index and a complementary histological study of the gonad revealed differences between the two populations in their reproductive cycle as well as in the quantity of gamete emissions. The Rinconada population has a major spawning period occuring at the end of the year and lasting about three months. Minor spawnings also occur in early July to late September. In Mejillones individuals, only one major period of gametogenesis and spawning occurs. Gametogenesis begins in January and spawning occurs between February and March. This is followed by a period of quiescence lasting four to five weeks. These results suggest that the Mejillones individuals are a more appropriate source of genitors to be used for conditioning in hatcheries. Existing data on biometrics, particularly the dimensions of the adductor muscle, as well as enzyme polymorphism, suggest that the Rinconada population would be a more appropriate source of genitors to be used in future aquaculture attempts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2109.1997.00844.x
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  • 2
    Electronic Resource
    Electronic Resource
    Genetic variability of the Lucinidae:Loripes lucinalis,Lucinella divaricata and Lucinoma borealis minor (Mollusca: Bivalvia) from Brittany, France
    Amsterdam : Elsevier
    Biochemical Systematics and Ecology 17 (1989), S. 463-468 
    Details
    ISSN: 0305-1978
    Keywords: Bivalvia ; Loripes lucinalis ; Lucinella divaricata ; Lucinidae ; Lucinoma borealis minor ; diagnostic locus ; electromorphs ; electrophoresis ; genetic variability
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0305-1978(89)90025-2
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  • 3
    Electronic Resource
    Electronic Resource
    Observations on ingestion and digestion of unicellular algae by Strombus gigas larvae (Mollusca, Gastropoda) using epifluorescence microscopy
    Amsterdam : Elsevier
    Aquaculture 92 (1991), S. 359-366 
    Details
    ISSN: 0044-8486
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0044-8486(91)90041-5
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  • 4
    Electronic Resource
    Electronic Resource
    Antibiotics in larval rearing of marine bivalves
    Amsterdam : Elsevier
    Aquaculture 12 (1977), S. 15-30 
    Details
    ISSN: 0044-8486
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0044-8486(77)90043-6
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  • 5
    Electronic Resource
    Electronic Resource
    Observations by epifluorescence microscopy of ingestion and digestion of unicellular algae by young larvae of Pecten maximus (Pectinidae Bivalvia)
    Amsterdam : Elsevier
    Aquaculture 47 (1985), S. 39-51 
    Details
    ISSN: 0044-8486
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0044-8486(85)90006-7
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  • 6
    Electronic Resource
    Electronic Resource
    Survival of Nucella lapillus in a tributyltin-polluted area in west Brittany: a further example of a male genital defect (Dumpton syndrome) favouring survival (1996)
    Springer
    Marine biology 125 (1996), S. 543-549 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A male genital defect was reported in a Nucella lapillus (L.) population at Dumpton Gap (England). This defect was termed “Dumpton syndrome” (DS) and appears to be a genetic feature. Its main characteristic is the absence of penis (aphally) in males and in females. In 1992, such a phenomenon was discovered in populations in the vicinity of Brest (Brittany, France). DS-affected females exhibit fewer tributyltin-induced imposex characteristics than expected in normal individuals. The percentage of female sterilization is thus lower, favouring population survival. In consequence, the DS is considered to be a “pollution-resistance” feature. Comparison with the Dumpton population revealed similarities and differences in the DS characteristics. It is thus hypothesized that the DS observed at the two locations is due to two different biological mechanisms. Indeed, aphallic males with a split prostate were observed but no underdevelopment of their vas deferens and testis was noted in the present study. In this gonochoristic gastropod species, the most DS-affected males in Brest possess an ovotestis and it is thus hypothesized that feminity is remnant in N. lapillus. Incidence of abnormality is ten times higher in females than in males. This suggested that a sex-difference operates in the Brest phenomenon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00353267
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  • 7
    Electronic Resource
    Electronic Resource
    Ultrastructure of the gill of the hydrothermal-vent mytilid Bathymodiolus sp. (1986)
    Springer
    Marine biology 92 (1986), S. 65-72 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Specimens of Bathymodiolus sp. were collected at 2 620 m depth during the “Biocyarise” Cruise (12°58′80″N; 13°56′60″W) in March 1984, and samples of the gill were fixed for ultrastructural observations. The gill of this hydrothermal-vent mytilid constitutes the main organ in the nutritional processes. The lamellae display abundant ciliation, normally comprised of frontal cilia, compound latero-frontal cirri and lateral cilia. At the ventral margin of each demi-branch, a longitudinal, ciliated, feeding groove is present. the lamellae are composed of numerous homorhabdic filaments connected by tufts of cilia. Each filament is made of a thin wall overlying a central lumen containing amoebocytes. Ultrastructural observations revealed the filament wall to be composed of four types of cells: (1) The ciliated cells of the frontal, latero-frontal and lateral ciliation, characterized by an abundance of mitochondria. (2) Mucous cells present to some degree among the ciliated cells, but more abundant on the distal edge and containing dense droplets of mucus. (3) Cells colonized at their apical pole by numerous bacteria enclosed in membrane-delimited clear spaces and composing the major part of the filament wall. (4) Thin ciliated cells separating the bacterial cells and characterised by a dense fringe of microvilli at their apical pole. The lumen of the filament contains amoebocytes of different morphological aspects which seem to accumulate electron-dense granules, possibly related to detoxification processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392747
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  • 8
    Electronic Resource
    Electronic Resource
    Peribuccal organs ofPlacopecten magellanicus andChlamys varia (Mollusca: Bivalvia): Structure, ultrastructure and implications for feeding (1990)
    Springer
    Marine biology 107 (1990), S. 215-223 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to better understand the structure of bivalve peribuccal organs and relate this to existing functional paradigms of their role in feeding, the labial palps of two scallop species,Placopecten magellanicus from the Bay of Fundy, Canada (1985 and 1986), andChlamys varia from the Bay of Brest, France (1986), were examined using histological techniques and electron microscopy. The ridged palp surface displays a uniformly dense ciliation with relatively few mucocytes; these are essentially concentrated in the region of the secondary ledge and may, through their secretory activity, determine the fate of particle masses in this area. The mucus secretions of the ridged palp surface are qualitatively different from those of the smooth palp surface. Mucocytes are much more abundant on the smooth palp surface, where it is suggested that their homogeneous secretions attenuate the potentially adverse effects of anteriorly-directed cleansing and swimming currents. Two other cell types are found in the palp epithelia: ciliated cells, which are very numerous on the ridged surface and relatively rare on the smooth surface, and non-ciliated epithelial cells, which are very numerous on the smooth surface and rare on the ridged surface, where they are confined to the palp margin. In addition to the mechanical role of the ciliated cells and mucocytes, the ultrastructural characteristics of the ciliated and non-ciliated epithelial cells indicate a dichotomy of function between the ridged and smooth surfaces. The ridged surface epithelial cells present an ultrastructural specialization in the absorption of dissolved and colloidal matter, suggesting an accessory nutritive role, whereas the smooth surface simple epithelial cells show signs of active molecular synthesis. No specialised sensory cells were observed on the ridged surface; it is therefore not yet possible to conclude whether the labial palps are capable of selection based on individual particle characteristics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01319820
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  • 9
    Electronic Resource
    Electronic Resource
    The osphradium in Placopecten magellanicus and Pecten maximus (Bivalvia, Pectinidae): histology, ultrastructure, and implications for spawning synchronisation (1995)
    Springer
    Marine biology 123 (1995), S. 121-129 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The bivalve osphradium is a band of putatively sensory tissue located in the gill axis, whose function is uncertain. In the present study, extending from 1987 to 1994, anatomical, histological, and electron microscopical techniques were used to elucidate the structure and ultrastructure of the osphradium in hatchery Pecten maximus L. and Placopecten magellanicus (Gmelin) (collected from Passamaquoddy Bay, New Brunswick, Canada). The osphradium consists of two distinct regions which run longitudinally on both sides of each gill axis: the osphradial ridge, and the dorsal tuft cilia region. The osphradial ridge was largely devoid of cilia other than those of the few free nerve fibres. The dorsal tuft cilia region contained free nerve fibres and ciliary tufts, separated by undifferentiated epithelial cells. No paddle cilia were observed under isosmotic fixation conditions, although under hypotonic conditions such cilia were quite common, suggesting an artefactual nature. Most of the cells of the osphradial ridge were highly secretory, the principal products being large pigment granules (in Pecten maximus) directly secreted by the Golgi bodies, and numerous small, electron-dense vesicles. These vesicles were arranged along extensive microtubule arrays in the basal region, indicative of axonal transport. These data support and extend Haszprunar's hypothesis of the role of the osphradium in the reception of chemical spawning cues and in the synchronization of gamete emission. Together with independent data on nerve pathways, osphradial sensory modalities, and monoamine localisation, an anatomical pathway and neurophysiological mediator are postulated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00350330
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  • 10
    Electronic Resource
    Electronic Resource
    Utrastructural study of oogenesis and oocytic degeneration in Pecten maximus from the Bay of St. Brieuc (1989)
    Springer
    Marine biology 103 (1989), S. 339-348 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An ultrastructural study of oocytic development enabled the identification of changes occurring during oogenesis in Pecten maximus collected from the Bay of St. Brieuc, France, in 1987. “Auxiliary cells”, closely associated with developing oocytes were observed. Each oocyte seems to be associated with only one secretory cell, which is characterised by an abundant rough endoplasmic reticulum at the onset of vitellogenesis. Contact between this cell and a developing oocyte is maintained by a desmosome-like junction which can be observed when the vitelline coat is formed. These “auxiliary cells” seem to play a trophic role in vitellogenesis, and may be involved in the formation of the vitelline coat of the oocytes. Oocytic degeneration is discussed in detail; in this species, it is a continuous phenomenon of varying intensity throughout the year. The ultrastructural changes resulting in lysis of the oocyte are described, and the evolution of atretic oocytes is examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397268
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