El interés en el uso de péptidos antimicrobianos para el control de enfermedades de hongos en plantas de banano ha aumentado en los últimos años. En este trabajo se analizó la actividad antifúngica de diferentes péptidos sobre el desarrollo in vitro de Mycosphaerella fijiensis y se encontró que estos inhiben el crecimiento micelial del hongo y la germinación de sus ascosporas. Todos los péptidos evaluados mostraron actividad contra el hongo, aunque con marcadas diferencias en los valores de IC50 los cuales variaron entre 3,06 y 239,61 µg/mL. Los péptidos que presentaron mayor actividad fueron los designados Ib-AMP4 e Ib-AMP2, ambos derivados de la planta Impatiens balsamina. De otro lado, la actividad in vitro de estos péptidos parece ser compatible con algunos fungicidas químicos ya que cuando se usaron en forma combinada, no se encontraron efectos antagónicos o sinérgicos con estos agentes. Los hallazgos sugieren que los péptidos antimicrobianos podrían ser utilizados como posibles estrategias alternativas para el control de la Sigatoka negra.

The interest in the use of antimicrobial peptides to control fungal diseases in banana plants has been rising in the last years. In this paper we analyzed the antifungal activity of different peptides on the in vitro development of Mycosphaerella fijiensis and found that they inhibited fungal mycelial growth and ascospore germination. All peptides evaluated displayed activity against the fungus although with marked differences in IC50 values ranging between 3.06 and 239.61 µg/mL. The peptides exhibiting better activity were the designated peptides Ib-AMP4 and Ib-AMP2, both derived from Impatiens balsamina. Furthermore, the in vitro activity of these peptides seemed compatible with existing chemical fungicides, having no antagonistic or synergistic effect with these agents. The effect of these peptides on M. fijiensis mycelial elongation and ascospores germination suggests that they can be used as potential alternative strategies for the control of black Sigatoka disease.

In this study, the use of Mtp-40 and alpha antigen polymerase chain reaction (PCR) amplification fragments for the precise tuberculosis (TB) diagnosis was evaluated. One hundred and ninety two different samples were obtained from 113 patients with suspected TB. Mtp-40 and alpha antigen protein genes were amplified by the PCR technique and compared to both the "gold standard" (culture) test, as well as the clinical parameters (including a clinical record and X-ray film exam in 113 patients). Thirty-eight of the 113 patients had a presumptive clinical diagnosis of TB; 74% being detected by PCR technique, 58% by culture and 44% by direct microscopic visualization. Weconclude that it is possible to use PCR as a suitable technique for the detection of any mycobacteria by means of the alpha antigen product, or the specific infection of Mycobacterium tuberculosis by means of the mtp-40 gene. This might be a good supporting tool in difficult clinical TB diagnosis and pauci-bacillary cases.

Differential display technique was applied in order to identify transcripts which are present in axenic amastigotes but not in promastigotes of the Leishmania panamensis parasites. One of them was cloned and the sequence reveals an open reading frame of 364 amino acids (aprox. 40 kDa). The deduced protein is homologous to the serine/threonine protein kinases and specially to the mitogen activates protein kinases from eukaryotic species. Southern blot analysis suggest that this transcript, named lpmkh, is present in the genome of the parasite as a single copy gene. These results could imply that lpmkh could be involved in the differentiation process or the preservation of amastigotes in axenic conditions.

The malarial GBP 130 protein binds weakly to intact human erythrocytes; the binding sites seem to be located in the repeat region and this region's antibodies block the merozoite invasion. A peptide from this region (residues from 701 to 720) which binds to human erythrocytes was identified. This peptide named 2220 did not bind to sialic acid; the binding site on human erythrocyte was affected by treatment with trypsin but not by chymotrypsin. The peptide was able to inhibit Plasmodium falciparum merozoite invasion of erythrocytes. The residues F701, K703, L705, T706, E713 (FYKILTNTDPNDEVERDNAD) were found to be critical for peptide binding to erythrocytes.