Biomphalaria tenagophila (Orbigny, 1835) (Mollusca): adaptation to desiccation and susceptibility to infection with Schistosoma mansoni Sambon, 1907

Experiments were carried out to test the susceptibility of Biomphalaria tenagophila to the infection with strain SJ of Schistosoma mansoni in the F1, F2 and non-selected parental generation. The potential adaptation of B. tenagophila to desiccation, in healthy mollusks and those exposed to the larvae of S. mansoni of the F1, F2 and non-selected parental generations was also studied. The presence of mucus and soil, at the shell opening, protected the snails against desiccation, favoring survival. The healthy mollusks performed more attempts against desiccation than those exposed to the larvae of the parasite. The mortality rate, during desiccation, was higher among mollusks that remained buried and with the shell opening unobstructed. During the desiccation period the stage of development of the parasite was influenced by the weight loss and the survival of the snails. The longer the period of desiccation, the greater was the weight loss observed, abbreviating survival. The non-selected parental generation was more sensitive to desiccation than the F1 and F2 generations, both in healthy mollusks and in those exposed to S. mansoni larvae. Healthy mollusks were more resistant to desiccation than those exposed to the larvae of the S. mansoni. Desiccation did not interrupt the development of S. mansoni larvae in mollusks, causing a delay in the cercariae elimination. The susceptibility of B. tenagophila to the SJ strain of S. mansoni, in mollusks maintained in water during the larvae incubation period, was similar in all three generations.

Effects of the desiccation on Biomphalaria tenagophila (Orbigny, 1835) (Mollusca) infected by Schistosoma mansoni Sambon, 1907

Specimens of Biomphalaria tenagophila exposed to miracidia of Schistosoma mansoni were submitted to different desiccation periods as follows: group I: 24 h after exposure, desiccated for 28 days; group II: after cercariae elimination, desiccated for 7 days; group III: 21 days after exposure, desiccated for 7 days; group IV: 14 days after exposure, desiccated for 14 days; group V: 7 days after exposure, desiccated for 21 days. From the obtained data it was verified that desiccation was not capable of interrupting the development of larvae of S. mansoni in mollusks. A delay in the development of S. mansoni larvae in groups I, III, IV and V was observed. A pause was verified in the development of S. mansoni larvae in groups II, III, IV and V. Some larvae, in groups I, III, IV and V, did not suffer as a result of desiccation and continued their development. Larvae in the cercariae stage were shown to be more sensitive to desiccation. It was possible to obtain clearing of mollusks infected by sporocysts II and cercariae using a period of 7 days of desiccation.

Henry Phillips als Matteo, Rollenbild, Brustbild, in: Daniel-François-Esprit Auber: Fra Diavolo

Signatur des Originals: S 36/G01895

Report of the agricultural meeting, held in Boston, January 13, 1840, : containing the remarks on that occasion of the Hon. Daniel Webster, of the U.S. Senate, and of Professor Silliman, M.D., L.L.D., of Yale College, Conn. : With notes by Henry Colman, commissioner for the agricultural survey of the state.

Cover title: First agricultural meeting. Speeches of Mr. Webster and Mr. Silliman, with notes by Mr. Colman.

Christ, the image of God : a discourse delivered at the ordination of Rev. Henry Emmons, over the First Unitarian Congregational Church and Parish at Dunstable, N.H., June 10, 1835 /

"Published by request."

Henry Cullen Adams (late a representative from Wisconsin) Memorial addresses. Fifty-ninth Congress, second session. House of Representatives, February 24, 1907. Senate of the United States, March 2, 1907.

Mode of access: Internet.

Eulogies delivered in the Senate and House of representatives of the United States on the life and character of Hon. John C. Calhoun, of South Carolina, Hon. Henry Clay, of Kentucky, and Hon. Daniel Webster, of Massachusetts.

Reprinted from the three "Obituary addresses", published by order of Congress in 1850, 1852 and 1853, respectively.