In order to evaluate the temporal occurrence of Cryptosporidium oocysts in Ruditapes philippinarum clams bred along the northeastern Italian Adriatic coast and molecularly characterize the isolates, 2,160 specimens (180 clams per month) were collected from three clam farms from January to December 2004. Two farms (sites A and B) were located in Venice (Chioggia, Veneto region) and one (site C) in the Marano Lagoons (Friuli Venezia Giulia region). Clams from 36 pools (i.e., one pool of 60 clams per month per site) were subjected to a high-sensitivity seminested PCR assay specific for a 360-bp diagnostic region internal to the Cryptosporidium spp. outer wall protein gene. Positive amplicons were sequenced and analyzed. Cryptosporidium DNA was found in clams from seven pools (sites A and B) during 1 month of sampling at site A and 6 months of sampling at site B, with Cryptosporidium hominis and Cryptosporidium parvum being detected. The expected infection rate of the clams was 0.36%. Site B showed a significantly higher expected infection rate (1.15%) than did the other sites (A = 0.14% and C = 0%). Given its high sensitivity and specificity, this seminested PCR assay can be considered a reliable tool for detecting and distinguishing species within the Cryptosporidium genus. The seasonal pattern of contamination and the related public health risks are of particular concern.

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The possibility of increasing n-3 and n-6 long-chain polyunsaturated fatty acids (PUFA) content in microalgal mixtures used to feed Tapes philippinarum larvae was explored by lowering culture temperature from 26 to 14°C. Although fatty acid composition of different microalgal species has a genetic basis, the algal cultures grown at 14°C significantly increased the content of long-chain n-3 PUFA in Isocrysis galbana and in Thalassiosira pseudonana, while in Tetraselmis tetrathelo, the PUFA increase only involved shorter chain PUFA, namely 16:4n-3 and 18:4n-3. However, larvae fed on the PUFA enriched microalgal mixture did not show improvements in growth and survival performances with respect to the control group fed the microalgal mixture grown at 26°C. From a biochemical perspective, two key aspects emerged from the results: (i) clam larvae have adequate biotransformation and selection skills to adjust fatty acid profile to their requirements as they can even modulate the incorporation of essential long-chain PUFA as 20:5n-3 and 22:6n-3 when the dietary supply exceeds the physiological requirements; (ii) bivalve can biosynthesize non-methylene-interrupted dienoic (NMID) fatty acids as confirmed by the constancy of relative proportion with larvae growth in spite of the NMID fatty acid absence in the diet.