A SIMPLE METHOD TO DETECT BACTERIAL ASSOCIATIONS IN BIVALVE GILLS

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Advances in chromosomal studies of gastropod molluscs

Chromosomal studies of gastropods have greatly increased since previous published reviews. This paper provides chromosomal information gathered since 1970 for the Caenogastropoda and Heterobranchia, since 1978 for the Heterobranchia:Pulmonata and since 1986 for taxa of the `traditional' Archaeogastropoda. Out of 291 gastropod species reported here with known chromosome numbers, 243 species have been newly investigated since previous reviews. Karyotypes are reported for 207 species, with banding techniques performed on 27 species. This highlights the increased knowledge on gastropod chromosomal morphology during the last decades. The occurrence of sex chromosomes and of polyploidy is also reported in the studied species. Chromosomal data are discussed in the light of previous reviews and of recent molecular phylogenies

Chromosomal study of spatial variation of the prevalence of a gill neoplasia in Macoma balthica (L.) from the Gulf of Gdansk (Baltic Sea)

Spatial variation of the prevalence of a gill neoplasia in the bivalve Macoma balthica was investigated by chromosomal study of individuals from ten different sites in the Gulf of Gdansk. The prevalence of gill neoplasia, individually identified by the occurrence of abnormal metaphases with higher chromosome numbers than normal metaphases (2n = 38), ranges from 0 to 94% of individuals, according to the site studied. Sites Hel 45 m and Vistula 30 m, located in the zone of the thermocline and halocline were the most affected, probably related to very unstable hydrological conditions at these sites. Out of a total of 152 animals studied from the Gulf of Gdansk, 33% showed the occurrence of gill neoplasia. A chromosome number from 59 to 109 was scored in 29 abnormal metaphases. Karyotypes were constructed from 14 abnormal metaphases and showed a similar general pattern. This study showed that chromosomal abnormalities involving numerical and morphological changes imply similar disorders among the sites studied. Etiology of this disease is still unknown but the seriously polluted Gulf of Gdansk can be used as a model basin to assess the relationship between the incidence of neoplasia and the possible controlling factors of environmental instability and/or level of environmental contaminants

Argyrophilic nucleolar organizer regions (AgNORs) in interphases and metaphases of normal and neoplastic gill cells of Macoma balthica (Bivalvia : Tellinidae) from the Gulf of Gdansk, Baltic Sea

International audienceChromosome analysis of gill cells of different populations of Macoma balthica (L.) from the Bay of Gdansk (Baltic Sea) revealed 2 clam categories, 1 with neoplastic features and 1 without. Silver-staining was performed on interphase and metaphase cells of both categories. The mean argyrophilic nucleolar organizer region (AgNOR) count per abnormal interphase cell was significantly higher than in normal interphase cells. Normal silver-stained metaphases had 3 nucleolar organizer region (NOR) chromosome phenotypes. The location of the NORs in the most frequent phenotype (55.6% in 54 metaphases scored) was interstitial on the largest metacentric chromosome pair, Pair No. 1. Abnormal silver-stained metaphases had a higher number of active NOR sites. Different phenotypes were observed (frequency greater than 10% for 67 metaphases scored); 2 were similar to those in normal metaphases and 5 were ectopic. The higher activity of AgNORs observed in abnormal cells confirmed the diagnosis of malignant neoplasia

Recent trends in the prevalence of neoplasia in the Baltic clam Macoma balthica (L.) from the Gulf of Gdańsk (Baltic Sea)

This study discusses the occurrence of neoplasia in the Baltic clam Macoma balthica from the Gulf of Gdańsk in recent years and investigates potential relationships between toxic compounds in the environment and the presence of the cancer. The disease was identified at four sampling stations during 1999–2002. Comparison with previous results highlighted the substantial prevalence of the tumour between 1998 and 2002. The prevalence of the cancer was strongly dependent on the sampling location (p < 0.001): it was highest at sampling point H45 (the deepest part of the gulf) and lowest at station PB30 (central part of the gulf). Monthly studies showed a trend towards an increasing prevalence of neoplasia during the warm months. However, over several sampling months no strong statistical correlation between the prevalence of the disease and the sampling time was found. The results of the study suggest that several environmental factors may promote the progress of the cancer in M. balthica from the Gulf of Gdańsk: it is most probably an indirect effect of pollution, although causality cannot be proven at this stage. Seriously polluted and exhibiting a considerable asymmetry of contamination, the ecosystem of the gulf provides an ideal environment for testing potential cause-effect relationships between pollutants and their biological effects