ABSTRACT
Five genes coding for ice-active proteins were identified from an expressed sequence tag database of Lolium perenne cDNA libraries. Each of the five genes were characterized by the presence of an N-terminal signal peptide, a region enriched in hydrophilic amino acids and a leucine-rich region in four of the five genes that is homologous with the receptor domain of receptor-like protein kinases of plants. The C-terminal region of all five genes contains sequence homologous with Lolium and Triticum ice-active proteins. Of the four ice-active proteins (IAP1, IAP2, IAP3 and IAP5) cloned, three could be expressed in Escherichia coli and recovered in a functional form in order to study their ice activity. All three ice-active proteins had recrystallization inhibition activity but showed no detectable antifreeze or ice nucleation activity at the concentration tested. IAP2 and IAP5 formed distinct hexagonal-shaped crystals in the nanolitre osmometer as compared to the weakly hexagonal crystals produced by IAP3.
Subject(s)
Lolium/genetics , Lolium/metabolism , Plant Proteins/genetics , Plant Proteins/metabolism , Antifreeze Proteins/metabolism , Crystallization , Freezing , Heating , Ice , Osmolar Concentration , Recombinant Proteins/metabolism , Sequence Homology, Amino AcidABSTRACT
Se evaluo la respuesta humoral, medida como anticuerpos especificos anti-criptococcus neoformans, en 69 sueros de un grupo de colombofilos de Bogota; grupo considerado como de alto riesgo dado el freecuente contacto con el material contaminado con el microorganismo. Ademas se estudiaron 65 sueros de un grupo de control constituido por personas dedicadas a actividades diferentes. En las pruebas de inmunofluorescencia indirecta y aglutinacion en tubo, no se evidencio diferencia entre los niveles de anticuerpos de ambos grupos. Se estudiaron adicionalmente 15 palomares con el objeto de aislar el microorganismo lo que se logro en el 66.7% de ellos. En 8 de los aislamientos se hizo serotipificacion del hongo encontrandose que la totalidad correspondia a C, neoformans var. neoformans
