[Bovine leukemia virus (BLV): prevalence in the Cuenca Lechera Mar y Sierras from 1994 to 1995]. / Virus de la leucosis bovina (BLV): prevalencia en la Cuenca Lechera Mar y Sierras entre 1994 y 1995.

The Cuenca Lechera Mar y Sierras (CLMS) includes about 300 dairy farms located in the counties of Tandil, Balcarce, Juarez, Ayacucho, General Pueyrredón, Gonzalez Chavez and Necochea, in the province of Buenos Aires. The purpose of this investigation was to determine the prevalence of infection caused by Bovine Leukemia Virus (BLV) in the CLMS. We investigated the presence of anti-BLV antibodies in 4,203 milk samples taken from 73 dairy farms belonging to the CLMS. An indirect ELISA, which is described and evaluated in this paper, was used to test the antibodies in milk. We classified the dairy farms according to their rate of infection. The percentage of dairy farms free of infection resulted in 31.50. On the other hand, 49.40% of the dairy farms showed a figure between 1% and 15% of infected cattle; 17.80% between 16% and 30%, and the remaining 1.30% turned out more than 30% of infected cattle. If compared with data obtained in the 1979-1981 period, which showed that 95.65% of the dairy farms was BLV-free, it is clear that a dramatic progress of the BLV infection has occurred for the last 15 years. Nevertheless, the CLMS is in a privileged position so as to incorporate an inexpensive control plan to eradicate the BLV infection, as almost 1/3 of its dairy farms is still BLV-free and 49.40% still has a low rate of BLV infection. Only about 20% of the dairy farms would require costly strategies of control.

Presence of secretory IgA in human periapical lesions.

The concentration of secretory IgA in fluids present in the canals of 33 teeth was determined by the rocket immunoelectrophoresis technique. Except for the presence or absence of communication between the oral cavity and the root canals of the affected teeth, no other clinical finding showed significant statistical correlation with the presence of secretory IgA. The canals which were open to the oral flora had significantly higher concentrations of secretory IgA. Leaving canals open to the oral cavity may result in formation of periapical cysts.

The Involvement of Endogenous Cytokinin-like and Gibberellin-like Substances in Germination and Early Seedling Growth of Cucurbita pepo L.

Mature dry seeds of Cucurbita pepo contained measurable quantities of both gibberellin-like and cytokinin-like materials. During germination, levels of endogenous gibberellin-like substances initially fell, but subsequently increased again. At no time, however, was there more endogenous gibberellin activity present than in the dry seeds. In terms of the amounts of gibberellin reported in other tissues, the levels in these seeds were low. Most of the cytokinin-like activity present was in the form of free bases, although small amounts of bound cytokinin-like. material were consistently present. Free cytokinin-like activity was appreciably reduced during imbibition, partly as a result of leaching, and did not increase again until late in the germination sequence. The increases in levels of both gibberellin-like and free cytokinin-like activity occurred much later than germination, as measured by radicle protrusion, and corresponded more closely with a rapid acceleration of extension growth in both the radicle and hypocotyl.