Behavior of Biomphalaria glabrata, the intermediate host snail of Schistosoma mansoni, at different depths in water in laboratory conditions

Using three columns of different depths (1.10m, 8.40m and 10.40m), we investigated the possibility of Biomphalaria glabrata moving towards deep regions. In the 1.10m column, we noted that locomotion can occur in two manners: 1) when the foot is in contact with the substrate: a) sliding descent; b) sliding ascent; c) creeping descent; d) creeping ascent, 2) when the foot is not in contact with the substrate: a) sudden descent without emission of air bules; b) sudden descent with emission of air bules; c) sudden ascent. In the 8.40m column containing food on the bottom (experimental group), the snails remained longer at this depth when compared to those of the group which received no food (control). The sliding behavior was characteristic of locomotion occurring at 0 to 1m both in upward and downward directions. Creeping behavior was typical for the ascent of the snails that reached deeper levels. When the snails were creeping, the shell remained hanging as if it were heavier, a fact that may have been due to water entering the pulmonary chamber. In the 10.40m column, the snails slid downward to a depth of 4m or descended suddenly all the way to the bottom. Ascent occurred by creeping from the bottom to the surface. In the 8.40m and 10.40m columns, copulation, feeding and oviposition occurred at the deepest levels.

Profits and votes: Entrepreneurs and the government in Brazilian housing policy

ABSTRACTAfter more than twenty years of low housing construction output, the housing policy recovered its momentum in the country with the ascent of the Partido dos Trabalhadores (Workers' Party, PT) to the seat of the federal government. This article demonstrates - through the analysis of documents, interviews and research conducted with businessmen - that the impetus of such a state policy is a part of the PT electoral strategy, which is based on economic growth and the expansion of social programs. The research analyses the dovetailing of interests between the Lula (the Brazilian President from 2003 to 2010) administration and the civil construction business - the latter concerned with expanding its business, and the former with increasing the supply of jobs and the level of economic activity. This process culminated in the launching of the largest social housing program to be implemented in the country. Minha Casa, Minha Vida (My House, My Life), is a project in whose planning building companies played a key role, performing feasibility studies and carrying out social housing projects.