Metaciclogénesis de Trypanosoma cruzi en Belminus ferroae (Reduviidae: Triatominae) y capacidad infectiva de las heces en condiciones de laboratorio

Introduction: Belminus ferroae is a triatominae with entomophagous behavior. However, it may occasionally feed on vertebrates. Currently, there is no evidence of natural infection with Trypanosoma cruzi or the occurrence of metacyclogenesis in this species.Objective: To test T. cruzi metacyclogenesis in B. ferroae and the infectivity of their feces or intestinal contents in rodents under laboratory conditions.Materials and methods: Twenty nymphs of B. ferroae were infected with an autochthonous strain of T. cruzi (M/HOM/VE/09/P6). Fecal and urine samples were collected from spontaneous droppings or by compressing the bugs’ abdomens and, eventually, by removing their gut contents, and then examined at 10, 20, 30, 40, 50, and 60 days. We quantified T. cruzi parasitic load, as well as the evolutionary forms in feces, urine, and intestinal contents by Giemsa staining. Similarly, we evaluated the infectivity of T. cruzi metacyclic trypomastigotes in albino mice.Results: The parasitological analysis showed three insects (15%) infected with T. cruzi at 30 (n=1), 40 (n=1), and 50 (n=1) days post-infection. We observed parasitic loads of up to 1.62 x 105 trypanosomes/mm3 and metacyclogenesis percentages between 3.5% and 6.78%.Conclusions: This is the first time that T. cruzi metacyclogenesis is reported in a species of the genus Belminus under laboratory conditions and the infectivity of Belminus’ feces is demonstrated on a vertebrate host.Introducción. Belminus ferroae es un triatomino de comportamiento entomófago, sin embargo, puede alimentarse de vertebrados ocasionalmente. No se ha demostrado infección natural por Trypanosoma cruzi en esta especie, como tampoco la metaciclogénesis del parásito.Objetivo. Examinar la metaciclogénesis de T. cruzi en B. ferroae y la capacidad infectiva de las heces o sus contenidos intestinales en roedores.Materiales y métodos. Se analizaron las heces y la orina expulsadas espontáneamente por los insectos o mediante compresión abdominal o extracción del contenido intestinal a los 10, 20, 30, 40, 50 y 60 días. Se cuantificó la carga parasitaria de T. cruzi y sus formas evolutivas se identificaron con tinción de Giemsa. Asimismo, se evaluó en ratones albinos la apacidad infectiva de los tripomastigotes metacíclicos de T. cruzi obtenidos de las heces o contenidos intestinales de los especímenes infectados.Resultados. El análisis parasitológico reveló tres (15 %) insectos infectados con T. cruzi a los 30 (n=1), 40 (n=1) y 50 (n=1) días después de la infección con cargas parasitarias de hasta 1,62 x 105 tripanosomas/mm3 y porcentajes de metaciclogénesis entre el 3,5 y el 6,78 %. Conclusiones. Se demuestra por primera vez, en una especie del género Belminus, la metaciclogenésis de T. cruzi en condiciones de laboratorio y la capacidad infectiva de las heces para un huésped vertebrado

Non-Invasive In Vivo Imaging of Calcium Signaling in Mice

Rapid and transient elevations of Ca2+ within cellular microdomains play a critical role in the regulation of many signal transduction pathways. Described here is a genetic approach for non-invasive detection of localized Ca2+ concentration ([Ca2+]) rises in live animals using bioluminescence imaging (BLI). Transgenic mice conditionally expressing the Ca2+-sensitive bioluminescent reporter GFP-aequorin targeted to the mitochondrial matrix were studied in several experimental paradigms. Rapid [Ca2+] rises inside the mitochondrial matrix could be readily detected during single-twitch muscle contractions. Whole body patterns of [Ca2+] were monitored in freely moving mice and during epileptic seizures. Furthermore, variations in mitochondrial [Ca2+] correlated to behavioral components of the sleep/wake cycle were observed during prolonged whole body recordings of newborn mice. This non-invasive imaging technique opens new avenues for the analysis of Ca2+ signaling whenever whole body information in freely moving animals is desired, in particular during behavioral and developmental studies

Neuregulins: Primary or secondary signals for the control of synapse-specific gene expression.

Neuregulins: Primary or secondary signals for the control of synapse-specific gene expression.(Colasante, Cesare.) Abstract The selective transcription of acetylcholine receptor (AChR) subunit genes in synaptic myonuclei leads to the accumulation of AChR subunit mRNAs at the neuromuscular junction (NMJ). This mechanism contributes to the concentration of AChRs at the postsynaptic sarcolemma, and its physiological significance is underscored by the cases of human congenital myasthenias caused by mutation in a cis-regulatory element of the AChR£-subunit promoter, which is necessary for its synaptic expression. The signal(s) that drives synapse-specific expression is unknown but neuregulin-1 (Nrg-1), a group of growth-factor-like polypeptides encoded by the nrg-1 gene, has been a favorite candidate. Nrg-1 was originally thought as a nerve-derived factor, acting in parallel to pathways controlling AChR clustering at the synapse (i.e. agrin signaling). However, recent work suggests that Nrg-1 may actually be a muscle-derived signal that is concentrated at the NMJ, together with its receptors, by agrin and that acts as a secondary, downstream signal to enhance synapse-specific AChR transcription. Here, I review studies for and against Nrg-1 as a secondary signal driving synapse-specific expression at the NMJ. In addition, I briefly present new evidence that raise the possibility that Nrgs encoded by the ngr-1-related gene nrg-2 might have a role controlling AChR expression. This paper was published on Journal of Neurocytology 32, 665-675 (2003) Section of Neurobiology, Institute for Cell and Molecular Biology, and Institute for Neuroscience, University of Texas at Austin, Austin, TX 78712, [email protected] monográfic

Información Investigador: Colasante Martínez, Cesare Olindo

Resumen Curricular Biólogo egresado en el King's College de la Universidad de Londres, Inglaterra en 1981; Maestría en Ciencias Médicas Fundamentales en Neurobiología (ULA); Doctorado en Neurociencias en la Universidad Pierre et Marie Curie (Paris VI), París, Francia. Trabajo en la ULA desde 1981 en el Centro de Microscopía Electrónica y luego en El Departamento de Fisiología y Laboratorio de Fisiología de la Conducta de la Facultad de Medicina. Es miembro del PPI en el Nivel III y profesor invitado del Instituto IDEA, Caracas Venezuela. Investigador Asociado del CNRS Francia y ha sido profesor invitado de la Universidad de Texas en Austin USA. Trabaja en Neurobiología en particular en los mecanismos de liberación de neurotransmisores y reciclaje de las vesículas sinápticas, así como en los mecanismos de acción de algunas neurotoxinas. Tutor del Doctorado Individualizado de Medicina de la Universidad Central de Venezuela y Coordinador del Doctorado en Medicina Experimental Proyecto de creación del Doctorado en Medicina Experimental mención Neurociencias de la Universidad de Los Andes. Autor de 39 publicaciones listadas en el Science Citation Index.Doctorado1082II - 2002115 - 2005; 85 - 2003; 47 - 2001Neurociencias, neurobiología celular, neuropatología, inmunocitoquímica.Marzo de 2007Biólogo+58 274 2403110Facultad de [email protected]

Differential entry of Botulinum Neurotoxin A into neuronal and intestinal cells: an ultrastructural approach

International audienceRecombinant C-terminus (Hc) of botulinum neurotoxin A (BoNT/A) was used to monitor toxin entry into NG108-15 neuronal cells and m-ICcl2 intestinal cells by both fluorescence and electronic microscopy. BoNT/A Hc entered neuronal cells via a clathrin pathway and intestinal cells mainly via non-clathrin vesicles. Upon incubation at 4°C, BoNT/A Hc gold particles were mainly distributed to neuronal cell periphery and to a lower extent to m-ICcl2 cells. After incubation at 37°C, BoNT/A Hc mostly transited in coated vesicles in NG108-15 cells and in uncoated vesicles of m-ICcl2 cells, which support the transcytotic passage of the toxin

Red-Shifted Aequorin-Based Bioluminescent Reporters for in Vivo Imaging of Ca Signaling

Real-time visualization of calcium (Ca 2+ ) dynamics in the whole animal will enable important advances in understanding the complexities of cellular function. The genetically encoded bioluminescent Ca 2+ reporter green fluorescent protein–aequorin (GA) allows noninvasive detection of intracellular Ca 2+ signaling in freely moving mice. However, the emission spectrum of GA is not optimal for detection of activity from deep tissues in the whole animal. To overcome this limitation, two new reporter genes were constructed by fusing the yellow fluorescent protein (Venus) and the monomeric red fluorescent protein (mRFP1) to aequorin. Transfer of aequorin chemiluminescence energy to Venus (VA) is highly efficient and produces a 58 nm red shift in the peak emission spectrum of aequorin. This substantially improves photon transmission through tissue, such as the skin and thoracic cage. Although the Ca 2+ -induced bioluminescence spectrum of mRFP1-aequorin (RA) is similar to that of aequorin, there is also a small peak above 600 nm corresponding to the peak emission of mRFP1. Small amounts of energy transfer between aequorin and mRFP1 yield an emission spectrum with the highest percentage of total light above 600 nm compared with GA and VA. Accordingly, RA is also detected with higher sensitivity from brain areas. VA and RA will therefore improve optical access to Ca 2+ signaling events in deeper tissues, such as the heart and brain, and offer insight for engineering new hybrid molecules

IP³ receptors and Ca²+ signals in adult skeletal muscle satellite cells in situ.

IP³ receptors and Ca²+ signals in adult skeletal muscle satellite cells in situ.(Molgó, Jordi, Colasante, Cesare, Adams, Dany S. and Jaimovich, Enrique.) Abstract In this short article we review muscle satellite cell characteristics and our studies in adult rodent muscle satellite cells in situ. Using confocal laser scanning microscopy and immunocytochemistry, a high level of receptor (IP3R) immunostaining was detected in satellite cells. These cells were identified by their peripheral position, their size, the shape of their nucleus, the paucity of the apparent cytoplasm, and the immunostaining with specific molecular markers such as a-actinin, the neural cell adhesion molecule (N-CAM) and desmin. High extracellular K+ (60 mM) induced long-lasting Ca²+; signals in satellite cells in situ. We suggest that electrical activity stimulates IP3-associated Ca²+; signals that could act in concert with signaling pathways triggered by growth factors and/or hormones. This paper is dedicated to the memory of Dr. Jeanne A. [email protected] monográfic

IP3 receptors and Ca2+ signals in adult skeletal muscle satellite cells in situ

In this short article we review muscle satellite cell characteristics and our studies in adult rodent muscle satellite cells in situ. Using confocal laser scanning microscopy and immunocytochemistry, a high level of IP3 receptor (IP3R) immunostaining was detected in satellite cells. These cells were identified by their peripheral position, their size, the shape of their nucleus, the paucity of the apparent cytoplasm, and the immunostaining with specific molecular markers such as a-actinin, the neural cell adhesion molecule (N-CAM) and desmin. High extracellular K+ (60 mM) induced long-lasting Ca2+ signalsin satellite cells in situ. We suggest that electrical activity stimulates IP3-associated Ca2+ signals that could act in concert with signaling pathways triggered by growth factors and/or hormone

Recycling and refilling of transmitter quanta at the frog neuromuscular junction

Artículo Publicado en: Journal of Physiology (2000), 523.1, pp. 247-258 [email protected] monográfic