Resumen Contexto: La ausencia de un marco conceptual común sobre trazabilidad en la cadena de suministro de alimentos (CSA), impide su desarrollo de manera unificada. Dicha ausencia ha generado confusion y no ha permitido evidenciar las ventajas sociales y empresariales de implementarla; además, no contar con un marco comtin en países como Colombia, impide el desarrollo adecuado de políticas publicas. Metodo: Se realizo una revision sistematica de la literatura en cuatro etapas: protocolo de btisqueda para consultar artículos de las bases Scopus, Science Direct, ISI Web; revision y seleccion de artículos relevantes, extraccion de datos en tablas y formatos diseüados para dicho fin y elaboracion del marco conceptual. Resultados: Se propone un marco conceptual comíin que abarca los siguientes aspectos, definicion de trazabilidad, características y propiedades, esquemas, unidad de recurso trazable, motivadores y sistemas de captura; para el diseno e implementacion de un sistema de trazabilidad en la CSA. Se evalua la legislacion internacional y nacional y se establecen elementos para su implementacion. Se ejemplifica el marco conceptual propuesto para la cadena de suministro camica que permitiría orientar la implementacion de sistemas de trazabilidad en CSA en Colombia. Conclusiones: El marco conceptual para la trazabilidad de CSA puede ser una guía para la implementacion y desarrollo en las cadenas alimentarias en el contexto colombiano. Una implementacion en cadenas agropecuarias permitirá la diferenciacion de origen, lo que puede ser un factor competitivo para aquellos productores que realicen buenas prácticas agrícolas, así como capacidades logísticas efectivas por los demas agentes de la CSA, el efecto de su implementacion debe evaluarse en especial en la incidencia sobre posicionamiento de marca y el establecimiento de precios justos, como efecto del rastreo y seguimiento del sistema de trazabilidad.

Abstract Background: The absence of a common conceptual framework on traceability in the food supply chain (SCF), prevents a cohesive development of this concept. The absence has generated confusion and has made it impossible to demonstrate the social and commercial advantages of its implementation. In addition, not having a common framework in countries such as Colombia obstructs the development of public policies. Method: A systematic review of the literature was carried out in four stages: search protocol to consult articles in the databases Scopus, Science Direct and ISI Web; review and selection of relevant articles; extraction and incorporation of data into tables and formats designed for this purpose and elaboration of the conceptual framework. Results: A common conceptual framework is proposed for the design and implementation of a traceability system in the SCF covering the following aspects: definition of traceability, characteristics and properties, schemes, traceable resource unit, motivators and recording systems. The international and national legislation is evaluated and aspects for its incorporation are established. The proposed conceptual framework is exemplified by the meat supply chain to guide the implementation of traceability systems in CSA in Colombia. Conclusions: The conceptual framework for SCF traceability can be a guide for the implementation and development of food chains in the Colombian context. Implementing this in agricultural chains would allow the differentiation of origin, which can be a competitive factor for producers with good agricultural practices, as well as provide effective logistic capacities for all agents of the SCF. The effect of its implementation should be evaluated with special emphasis on the impact on brand positioning and the establishment of fair prices as an effect of tracking and tracing the traceability system.

Este estudio es el primer registro para Colombia del género Hildenbrandia, representando el primer hallazgo de Rhodophyta dulceacuícola. Se incluye la descripción detallada de los caracteres morfométricos, así como la distribución ambiental de las poblaciones recolectadas en tres localidades del departamento de Santander. Se concluye que la especie corresponde a la circunscripción de Hildenbrandia angolensis; caracterizada por su diámetro celular pequeño (<img src="/img/revistas/cal/v28n2/v28n2a10img.jpg" > o = 4.8 μm) y de distribución tropical a subtropical. Se documentaron propágulos vegetativos en una sola población. H. angolensis se presentó en ríos cercanos a zonas de cascada, con temperatura de 16- 18 ºC, pH de neutral a ligeramente alcalino (6.9-7.6), alto contenido de iones (272-1174 μS cm-1), velocidad de corriente muy alta ( 140 cm s-1) y sitios sombreados con poca profundidad (< 60 cm); cobertura algal de esta especie sobre la roca entre 3.2- 4.1 m2. H. angolensis se registra en la cuenca alta del río de Oro y río Frío, en bosque seco a muy húmedo montano bajo, municipios de Piedecuesta y Floridablanca (Santander, Colombia).

This study is the first report for Colombia of the genus Hildenbrandia, representing the first record of a freshwater Rhodophyta. It is includes the detailed description of the morfometrics characters, as well as the environmental distribution of the populations collected from three localities of the department of Santander. It is concluded that the species fit within Hildenbrandia angolensis circumscription; it is characterized by it is small cell diameter (<img src="/img/revistas/cal/v28n2/v28n2a10img.jpg" > or = 4.8 μm) and of tropical or subtropical distribution. Vegetatives propagules were reported in one single population. H. angolensis occurred in rivers near to cascade zones, with temperature of 16- 18 ºC, pH circumneutral to slightly alkaline (6.9-7.6), high ion content (272-1174 μS cm-1), high current velocity ( 140 cm s-1) and shallow waters (< 60 cm); algal cover of this species on the rock ranged from 3.2 to 4.1 m2. H. angolensis is reported in upper streams basins of the Oro and Frio streams, in dry forest to very humid low montane belonging to Piedecuesta and Floridablanca municipalities ( Santander, Colombia ).

Several primary immunodeficiency diseases affecting the interleukin 12/interferon gamma (IFN-gamma) pathway have been identified, most of them characterized by recurrent and protracted infections produced by intracellular microorganisms, particularly by several species of mycobacteria. In the present study we analyzed the expression of IFN-gamma receptor (IFN-gammaR) and signal transducer and activator of transcription 1 (STAT-1) in 4 children with Mycobacterium tuberculosis infection of uncommon clinical presentation. These molecules were evaluated by flow cytometry and Western blotting in B cells transformed with Epstein-Barr virus and mutations were scanned by single-strand conformational polymorphisms and DNA sequencing. The expression of IFN-gammaR1 was normal in all 4 patients. The genetic analysis of IFN-gammaR1 and IFN-gammaR2 coding sequences did not reveal any mutation. The expression of the STAT-1 molecule was similar in patients and healthy controls; however, when the phosphorylation of this transcription factor in response to IFN-gamma activation was evaluated by Western blot, a significant lower signal was evident in one patient. These data indicate that there are no alterations in the expression or function of the IFN-gammaR chains in these patients. However, the low level of STAT-1 phosphorylation found in one of these patients might be explained by a defect in one of the molecules involved in the signal transduction pathway after IFN-gamma interacts with its receptor. In the other three patients the inability to eliminate the mycobacteria may be due to a defect in another effector mechanism of the mononuclear phagocytes.