Search results for "gastropod"
showing 10 items of 95 documents
A male XO sex-determining mechanism in Theodoxus meridionalis (Neritidae) (Prosobranchia, Archaeogastropoda).
1988
The haploid number of chromosomes n=12+h and the diploid values 2n=25 in males, and 2n=26 in females, have been determined for three geographically separated populations of Theodoxus meridionalis (Neritidae). A male XO sex-determining mechanism has been observed for this species.
Settlement performance of the Mediterranean reef-builders Dendropoma cristatum (Biondi 1859) in response to natural bacterial films.
2017
The gastropod Dendropoma cristatum is a biogenic engineer of the central Mediterranean, forming reefs along the lower rocky intertidal fringe with a remarkable ecological role. To understand whether reef-associated biofilm cultivable bacterial and biofilm ageing may trigger the settlement of the juvenile snails, a combination of laboratory techniques and field experiments was used. Reef-associated biofilm cultivable bacteria were isolated, and a settlement-choice experiment was performed in situ on artificial biofilms composed of i) a mixture of six biofilm-forming selected isolates, ii) all the cultivable bacteria, and iii) 13-, 23-, 32-day old biofilms formed under natural conditions. Ove…
Relationship between egg features and maternal body size in the simultaneous hermaphrodite Oxynoe olivacea (Mollusca, Opisthobranchia, Sacoglossa)
2005
This paper provides information on spawn morphology and egg features of the stenophagous planktotrophic Mediterranean sacoglossan Oxynoe olivacea. Smith and Fretwell’s hypothesis, predicting that individuals of the same population growing in the same environmental conditions and varying in size should spawn eggs of a constant size, was tested in a population of O. olivacea living in the Straits of Messina. To determine whether (a) spawn mass size, (b) total egg number per spawn, and (c) egg size were related to parent size of O. olivacea, 21 egg masses (seven egg masses deposited by seven different 20 mm animals, seven egg masses deposited by seven different 25 mm animals and seven egg mass…
Cytogenetics of the land snails Cantareus aspersus and C. mazzullii (Mollusca: Gastropoda: Pulmonata).
2004
A cytogenetic study was carried out on the chromosomes and nuclear DNA contents of the land snails Cantareus aspersus and C. mazzullii (Gastropoda: Pulmonata). Chromosomes were studied using Giemsa staining, banding methods and fluorescent in situ hybridization (FISH) with three repetitive DNA probes [18S rDNA, (GATA)n and (TTAGGG)n]. Results were very similar in the two species both showing (1) 54 bi-armed chromosomes [submetacentrics (SM) C metacentrics (M) C subtelocentrics (ST)]; (2) 10 terminal NORs after sequential application of rDNA FISH and silver staining; (3) uniform DNA fluorescence with CMA3 and DAPI staining and (4) genomic composition considerably enriched both in highly- and…
Influence of proprioceptive information on space orientation on the ground and in orbital weightlessness
1989
Conscious space orientation depends on afferent information from different sense organs including the labyrinth, the eyes, tactile cues from the skin, joint receptors, muscle spindles, tendon organs and possibly viscera. An important role is played by impulses from the cervical position receptors in interaction with concomitant information from the otolith system. In order to isolate the effect of cervical position receptors from that of the otolith system, space experiments in orbital weightlessness and in parabolic aircraft flight were performed. It was found that stimulation of the neck receptors in weightlessness markedly influences the perception of the subjective vertical and horizont…
On the Occurrence of the Invasive Freshwater Limpet Ferrissia californica (Mollusca: Gastropoda: Planorbidae) in Japan.
2018
Two members of the genus Ferrissia Walker, 1903, namely Ferrissia nipponica (Kuroda, 1949) and F. japonica Habe and Burch, 1965, have been reported to occur in Japan, but due to a lack of molecular data, doubts have been expressed as to their validity. Furthermore, the possible presence of allochthonous Ferrissia taxa has been stated under a variety of names, so that even now there is no consensus on their presence and identity. Recently, freshwater limpets belonging to the planorbid genus Ferrissia were collected in an irrigation trough on the Izu island of Hachijōjima, Tokyo, Japan. Molecular identification of the collected specimens, based on a fragment of the large ribosomal subunit 16S…
Life cycle of Renylaima capensis, a brachylaimid trematode of shrews and slugs in South Africa: two-host and three-host transmission modalities sugge…
2012
Abstract Background The life cycle of the brachylaimid trematode species Renylaima capensis, infecting the urinary system of the shrew Myosorex varius (Mammalia: Soricidae: Crocidosoricinae) in the Hottentots Holland Nature Reserve, South Africa, has been elucidated by a study of its larval stages, epizootiological data in local snails and mammals during a 34-year period, and its verification with mtDNA sequencing. Methods Parasites obtained from dissected animals were mounted in microscope slides for the parasitological study and measured according to standardized methods. The mitochondrial DNA cox 1 gene was sequenced by the dideoxy chain-termination method. Results The slugs Ariostralis …
Geometric Measurement Analysis Versus Fourier Series Analysis for Shape Characterization Using the Gastropod Shell (Trivia) as an Example
2003
Varied and efficient methods have been developed to describe and quantify natural objects. The most common ones use superimposition techniques (e.g. Procrustes methods; Bookstein, 1991), decomposition into harmonics (Fourier series and functions, wavelets; Anstey and Delmet, 1973; Christopher and Waters, 1974; Gevirtz, 1976; Lestrel, 1997; Toubin and others, 1999; Verrecchia, Van Grootel, and Guillemet, 1996; Younger and Ehrlich, 1977), analysis of spiral functions (e.g. Raup parameters; Raup, 1961, 1966; Tursch, 1998), and combinations of parameters from elementary geometry (e.g. circularity index, lengthening; Coster and Chermant, 1989; Schmidt-Kittler, 1986; Viriot, Chaline, and Schaaf, …
Effects of ocean acidification on the shells of four Mediterranean gastropod species near a CO2 seep
2017
Marine CO2seeps allow the study of the long-term effects of elevated pCO2(ocean acidification) on marine invertebrate biomineralization. We investigated the effects of ocean acidification on shell composition and structure in four ecologically important species of Mediterranean gastropods (two limpets, a top-shell snail, and a whelk). Individuals were sampled from three sites near a volcanic CO2seep off Vulcano Island, Italy. The three sites represented ambient (8.15 pH), moderate (8.03 pH) and low (7.73 pH) seawater mean pH. Shell mineralogy, microstructure, and mechanical strength were examined in all four species. We found that the calcite/aragonite ratio could vary and increased signifi…
Laparoscopic management of an isolated left fallopian tube torsion due to twisted Morgagni hydatid in a pre-menarcheal girl.
2014
Isolated torsion of fallopian tube, meanwhile uncommon, should be considered in diagnosis of pelvic and lower abdominal pain. US investigation is an useful diagnostic tool. A prompt diagnosis could avoid salpingectomy and preserve fertility. Laparoscopy, as the first approach, should be preferred. We report a case of isolated tubal torsion occurring in a premenarcheal girl successfully managed by laparoscopy.