RESUMO

Four serine/threonine kinases are present in all mycobacteria: PknA, PknB, PknG and PknL. PknA and PknB are essential for growth and replication, PknG regulates metabolism, but little is known about PknL. Inactivation of pknL and adjacent regulator MSMEG_4242 in rough colony M. smegmatis mc2155 produced both smooth and rough colonies. Upon restreaking rough colonies, smooth colonies appeared at a frequency of ~ 1/250. Smooth mutants did not form biofilms, showed increased sliding motility and anomalous lipids on thin-layer chromatography, identified by mass spectrometry as lipooligosaccharides and perhaps also glycopeptidolipids. RNA-seq and Sanger sequencing revealed that all smooth mutants had inactivated lsr2 genes due to mutations and different IS1096 insertions. When complemented with lsr2, the colonies became rough, anomalous lipids disappeared and sliding motility decreased. Smooth mutants showed increased expression of IS1096 transposase TnpA and MSMEG_4727, which encodes a protein similar to PKS5. When MSMEG_4727 was deleted, smooth pknL/MSMEG_4242/lsr2 mutants reverted to rough, formed good biofilms, their motility decreased slightly and their anomalous lipids disappeared. Rough delpknL/del4242 mutants formed poor biofilms and showed decreased, aberrant sliding motility and both phenotypes were complemented with the two deleted genes. Inactivation of lsr2 changes colony morphology from rough to smooth, augments sliding motility and increases expression of MSMEG_4727 and other enzymes synthesizing lipooligosaccharides, apparently preventing biofilm formation. Similar morphological phase changes occur in other mycobacteria, likely reflecting environmental adaptations. PknL and MSMEG_4242 regulate lipid components of the outer cell envelope and their absence selects for lsr2 inactivation. A regulatory, phosphorylation cascade model is proposed.

RESUMO

La transmisión de parásitos protozoarios patógenos a través del agua representa uno de los problemas de salud pública más prominentes en el mundo entero. Los estudios sobre presencia de parásitos protozoarios en aguas son fundamentales para conocer a fondo la epidemiología de enfermedades que afectan a poblaciones humanas en diferentes zonas geográficas. De esta manera, se pueden implementar en todo el mundo las medidas de salud pública que permitan el control y prevención de enfermedades transmitidas a través del agua. Los métodos corrientes para el monitoreo de Cryptosporidium parvum, C. hominis y Giardia intestinalis son empleados para la detección de Toxoplasma gondii y Cyclospora cayetanensis en ambientes acuáticos. La combinación de nuevas técnicas de filtración y concentración junto con los métodos moleculares y cultivo celular forma parte de la estrategia científica dirigida a evaluar la significancia de microorganismos patógenos actuales y emergentes de interés para la salud pública. Este artículo revisa avances recientes en métodos de concentración y detección de protozoarios patógenos transmitidos a través del agua, cuya aplicación reviste importancia en ambientes acuáticos de toda América Latina, donde se requiere mayor investigación científica en esta área.

Waterborne transmission of pathogenic parasitic protozoa represents one of the most prominent public health issues worldwide. Studies on occurrence of waterborne protozoan parasites are fundamental to the understanding of the epidemiology of waterborne diseases affecting human populations in different geographical regions. Thus, public health measures can be implemented to control and to prevent waterborne infectious diseases. Current methods for monitoring waterborne Cryptosporidium parvum, C. hominis and Giardia intestinalis are being applied for assessing the occurrence of waterborne Toxoplasma gondii and Cyclospora cayetanensis. The combination of novel filtration and concentration techniques along with molecular and tissue cell culture methods is part of the approach aimed to evaluate the public health significance of current and emerging waterborne pathogens. This paper reviews recent advances in concentration and detection methods that could be applied to assess occurrence of waterborne protozoan parasites in Latin America, where further research in this field is needed.

A transmissão de patógenos pela água representa um dos problemas de saúde pública mais proeminentes no mundo. Os estudos sobre ocorrência de parasitas patogênicos são importantes para entender a epidemiologia das doenças que afetam populações humanas em regiões geográficas diferentes. Assim, as medidas de saúde pública podem ser implementados para controlar e prevenir a transmissão de doenças pela água. Os métodos atuais para detectar Cryptosporidium parvum, C. hominis e Giardia intestinalis são usados para determinar ocorrência de Toxoplama gondii e Cyclospora cayetanensis em ambientes aquaticos. A aplicação de novas técnicas para filtração e concentração junto com métodos moleculares e de cultura de células é parte da estratégia para avaliar a importância de parasitas patogênicos correntes e emergentes em águas. Em este artigo se faz uma revisão dos avanços recentes em métodos de concentração e detecção de protozoários patogênicos transmitidos pela água. A aplicação desses métodos em ambientes aquáticos da América Latina é importante, pois se requer maior pesquisa nessa área.