Different reactions to foreign particles in the apple-snail Pomacea canaliculata.

CUETO, J.A,; ORTEGA, H.H.; ALFREDO JUAN CASTRO VAZQUEZ

Congreso; XXVIII Reunión Anual de la Sociedad de Biología de Cuyo; 2010

Sociedad de Biología de Cuyo

We studied the changes in circulating hemocyte concentration (CHC) after injection of heat-inactivated bacteria (Escherichia coli) or after insertion of a polystyrene bead in the foot. Both sham-injection and sham-insertion provoked a 2-3 fold increase in CHC, which was sustained for several days. Bacterial injection, however, provoked within 2 h a decrease to less than one third of the initial CHC and these values were slowly recovered in subsequent days. Since India ink injection results in the retention of carbon particles in renal hemocyte islets, it is thought that the decreased CHC observed after bacterial injection is due to hemocyte migration to the islets. Conversely, the insertion of a polystyrene bead did not modify CHC (as compared to sham-inserted controls) but induced a massive hemocyte accumulation around the inserted bead. PCNA (‘proliferative cell nuclear antigen’) was histochemically detected in renal islet hemocytes after bacterial injection and in those of the developing capsule around the bead. It is tentatively concluded that: (1) the injuries of sham-operations induce a lasting increase in CHC through an unknown mechanism; (2) hemocyte proliferation is enhanced both in the developing capsule around the bead and within renal islets after bacterial injection; (3) hemocyte proliferation in these islets may account for the slow recovery of CHC after bacterial injection; and (4) hemocyte proliferation in the developing capsules does not affect CHC.