The Response of the Corbiculidae (Mollusca: Bivalvia) to Osmotic Stress: The Cellular Response

Abstract

When Polymesoda was transferred from 10‰ to fresh water, the free amino acid (FAA) pool decreased by 70% in 24 h; alanine accounted for 85% of the decrease. In Polymesoda blood, FAA doubled within 10 h after hypoosmotic stress; between 10 and 24 h the FAA decreased by 24%. Most of the increase and subsequent decrease were accounted for by alanine. In Corbicula, transferred from 5‰ to fresh water, the FAA pool decreased by 87% in 48 h; alanine accounted for 73% of the decrease. Upon transfer from fresh water to 10‰, the free amino acid (FAA) pool of Polymesoda foot muscle increased from 27 to 176 μmol/g dry weight during the first 36 h; between 36 and 73 h the FAA pool increased only to 187 μmol/g dry weight. Alanine accounted for 56% of the increase before 36 h and 77% after 36 h. When Corbicula was transferred from fresh water to 5‰ the FAA pool increased from 20 to 115 μmol/g dry weight; between 70 h and 30 days the pool increased to 197 μmol/g dry weight. Alanine accounted for 78% of the initial increase in the FAA pool.