[The distribution and possible competition between Melanoides tuberculata and Tarebia granifera (Prosobranchia: Thiaridae) in Lake Hanabanilla, Cuba]. / Distribución y posible competencia entre Melanoides tuberculata y Tarebia granifera (Prosobranchia: Thiaridae) en el lago Hanabanilla, Cuba.

A study was carried out along three years, on distribution and possible competence between the two thiarid species present in Lake Hanabanilla, Cuba: Melanoides tuberculata and Tarebia granifera. Both species presented significant differences as to its abundance within a determined microhabitat, but they could match their densities for the total sampled area. These variations were mainly due to the ratio of juveniles in each species. Interaction was only detected when high abundance values were reached and some limitation resource existed (mainly in the nearest area to the shore). Both thiarids presented a high nest width, but Tarebia granifera was slightly higher; besides, this species was dominant at the end of the study at most of the sampled areas.

[Laboratory studies of the molluscacidal action of the maguey (Agave legrelliana) on Biomphalaria havanensis]. / Estudios de la acción molusquicida en el laboratorio del maguey (Agave legrelliana), sobre Biomphalaria havanensis.

A study was carried out on the molluscacidal action of agave (Agave legrelliana) on the mollusk Biomphalaria havanensis, host of Schistosoma. Different concentrations of the plant's juice extract were tested to determine lethal doses. 3 experimental series were carried out using 144 mollusks in each. LD50 = 0.14 mL/L and LD90 = 0.47 mL/L were determined using the "probilog" computerized program. The regression equation was Y = 5.29 + 2.53 in X. Density, pH, liquid content and absorbance of the juice were determined. The stability of the A. legrelliana juice extract was compared using LD90 and it was observed that its effectiveness was reduced after long storage periods. The results attained were very encouraging since large volumes of water abounding in intermediate host mollusks can be treated with small quantities of juice at the same time that the toxicity which might be introduced by products of chemical origin is reduced.

[Specificity of the resistance exhibited by peritoneal macrophages of rats immunized against rubeola virus]. / Estudio de la especificidad de la resistencia exhibida por los macrófagos peritoneales de ratas inmunizadas contra el virus de la rubéola.

Peritoneal macrophages in rats with no immunization against rubella virus and inoculted with bovine infectious rhinotracheitis virus are prone to suffer from a cytopathogenic effect with formation of inclusion bodies, and lysis, succeeding in reisolating the virus. The resistance of peritoneal macrophages of rats inoculated against rubella virus in nonspecific, since such resistance continues to show when macrophages interact with bovine infectious rhinotracheitis virus. The results support evidence that in the Inflammatory process suffered by rubella virus-inoculated rats, a cell immunity develops and macrophages are some of the cells performing the response.