Inhibition of Pasteurella multocida Adhesion to Rabbit Respiratory Epithelium Using Lectins.

This study aimed to evaluate the ability of a panel of lectins to inhibit the ability of Pasteurella multocida to adhere to and affect the rabbit respiratory epithelium. Nasal septa from rabbit fetuses were cultured with various lectins before the addition of P. multocida. The percentage of bacteria adhering to the epithelium was evaluated semiquantitatively by indirect immunoperoxidase (IIP) staining. The goblet cells (GCs) were counted in semithin sections stained with toluidine blue and served as the main morphological criterion to evaluate the inhibitory effect of the lectins. The lectins PNA, WGA, RCA120, and DBA significantly inhibited the adhesion of P. multocida to the ciliated epithelium (P < 0.05) and prevented the pathogen-induced increase in the number of GCs (P < 0.05) compared with those of positive control tissues. In addition, VVA, SJA, UEA I, DSL, SBA, and ECL significantly inhibited the increase in GCs compared with that of the control tissues. The results suggest that less aggressive therapeutic strategies, such as treatment with lectins, may represent alternative approaches to control bacterial respiratory infections.

Ultrastructural Comparison of the Nasal Epithelia of Healthy and Naturally Affected Rabbits with Pasteurella multocida A.

An ultrastructural comparison between the nasal cavities of healthy rabbits and those suffering from two forms of spontaneous infection with Pasteurella multocida was undertaken. Twelve commercially produced rabbits of different ages and respiratory health status were divided into four groups: healthy from 0 to 21 days (G1, n = 2); healthy from 23 to 49 days (G2, n = 2); healthy from 51 to 69 days (G3, n = 2); diseased rabbits with septicemia and the rhinitic form of P. multocida infection (G4, n = 3). The main ultrastructural changes observed were a widening of the interepithelial spaces, increased activity and number of goblet cells, the formation of two types of vacuoles in epithelial cells, the degranulation and migration of heterophils between the epithelial cells, and the association of this migration with some of the other changes. No bacteria were observed adhering to the epithelium, and very few were observed free in the mucus. Scant inter-epithelial spaces were found in healthy rabbits, but they were not as large and numerous as those found in diseased animals. We discuss the origin and meaning of these changes but, we focus on the significance of the inter-epithelial spaces and goblet cells for the defense of the upper respiratory airways against the bacterium and its lipopolysaccharide.

Phenotypic plasticity of Vaccinium meridionale (Ericaceae) in wild populations of mountain forests in Colombia.

Vaccinium meridionale is a promising crop for the Andean region of South America and is currently available only in the wild. Spontaneous populations of this plant are found across the Colombian mountains, but very few published records on this plant morphology are available. A zonification study of V. meridionale was conducted in four principal areas of a low mountain forest of Colombia (Provinces of Boyacá, Cundinamarca, Santander and Nariño) in 2007. A total of 20 populations and 100 plants of V. meridionale were individually characterized and surveyed, using a list of 26 characters of morphological variables (9 quantitative and 17 qualitative characters). Our results indicated that natural populations of V. meridionale might be found in the tropical forest under a highly heterogeneous climate and microclimate conditions, at different mountain regions between 2 357 and 3 168masl. The shrubs of V. meridionale exhibited a high level of intra-population variation in several quantitative (plant height, stem diameter) and qualitative (growth habit, ramification density, presence of anthocyanins in stems) morphological characters, suggesting an environmentally induced phenotypic plasticity. Plant height, stem diameter and foliar density were the most variable morphological traits, with coefficients of variation higher than 50%. However, several quantitative characters of its reproductive potential, such as berry dimensions, rachis length and number of flowers per inflorescence, resulted with low plasticity with coefficients of variation lower than 30.2%, indicating that these characters were genetically determined. The highest correlation coefficients (p < 0.05) resulted to be between fruit length and fruit width (0.90), leaf length and leaf width (0.78), plant height and stem diameter (0.60), and inflorescence length and flowers number per inflorescence (0.57). The results suggest that an important genetic resource exists for this species in the wild. Low variation in fruit size, which constitutes a target trait for plant breeders, could be useful for selection of cultivars of V. meridionale. The results of this study could also be applied in conservation programs aimed to protect these diverse populations in the mountain forests of Colombia.

Phenotypic plasticity of Vaccinium meridionale (Ericaceae) in wild populations of mountain forests in Colombia

Vaccinium meridionale is a promising crop for the Andean region of South America and is currently available only in the wild. Spontaneous populations of this plant are found across the Colombian mountains, but very few published records on this plant morphology are available. A zonification study of V. meridionale was conducted in four principal areas of a low mountain forest of Colombia (Provinces of Boyacá, Cundinamarca, Santander and Nariño) in 2007. A total of 20 populations and 100 plants of V. meridionale were individually characterized and surveyed, using a list of 26 characters of morphological variables (9 quantitative and 17 qualitative characters). Our results indicated that natural populations of V. meridionale might be found in the tropical forest under a highly heterogeneous climate and microclimate conditions, at different mountain regions between 2 357 and 3 168masl. The shrubs of V. meridionale exhibited a high level of intra-population variation in several quantitative (plant height, stem diameter) and qualitative (growth habit, ramification density, presence of anthocyanins in stems) morphological characters, suggesting an environmentally induced phenotypic plasticity. Plant height, stem diameter and foliar density were the most variable morphological traits, with coefficients of variation higher than 50%. However, several quantitative characters of its reproductive potential, such as berry dimensions, rachis length and number of flowers per inflorescence, resulted with low plasticity with coefficients of variation lower than 30.2%, indicating that these characters were genetically determined. The highest correlation coefficients (p<0.05) resulted to be between fruit length and fruit width (0.90), leaf length and leaf width (0.78), plant height and stem diameter (0.60), and inflorescence length and flowers number per inflorescence (0.57). The results suggest that an important genetic resource exists for this species in the wild. Low variation in fruit size, which constitutes a target trait for plant breeders, could be useful for selection of cultivars of V. meridionale. The results of this study could also be applied in conservation programs aimed to protect these diverse populations in the mountain forests of Colombia. Rev. Biol. Trop. 59 (2): 569-583. Epub 2011 June 01.

Vaccinium meridionale es una planta promisoria para la región Andina de Sudamérica y está disponible actualmente sólo en forma silvestre. Las poblaciones espontáneas de esta planta se encuentran en las montañas colombianas y existen muy pocos reportes publicados respecto a su morfología. Se realizó un estudio de zonificación de V. meridionale en cuatro áreas principales de un bosque de baja montaña de Colombia (Provincias de Boyacá, Cundinamarca, Santander y Nariño) en 2007. Un total de 20 poblaciones y 100 plantas de V. meridionale fueron individualmente caracterizadas usando una lista de 26 descriptores de variables morfológicas (9 caracteres cuantitativos y 17 caracteres cualitativos). Nuestros resultados indicaron que las poblaciones naturales de V. meridionale podrían ser encontradas en el bosque tropical bajo unas condiciones de clima y microclima muy heterogéneas, en regiones de montaña diferentes entre 2 357 y 3 168masl. Los arbustos de V. meridionale presentaron un nivel alto de la variación intrapoblacional en varios caracteres morfológicos cuantitativos (altura de planta, diámetro de tallo) y cualitativos (hábito de crecimiento, densidad de ramificación, presencia de antocianinas en tallos), sugiriendo una plasticidad fenotípica ambientalmente inducida. La altura de planta, el diámetro de tallo y la densidad foliar fueron los rasgos morfológicos más variables, con coeficientes de variación superior al 50%. Sin embargo, varios caracteres cuantitativos de su potencial reproductivo, como dimensiones de baya, longitud de raquis y número de flores por inflorescencia, presentaron plasticidad baja con coeficientes de la variación inferior al 30.2%, indicando que estos caracteres fueron genéticamente determinados. Los coeficientes de correlación más altos (p<0.05) fueron para longitud de fruto y ancho de fruto (0.90), longitud de hoja y ancho de hoja (0.78), altura de planta y diámetro de tallo (0.60), y longitud de inflorescencia y número de flores por inflorescencia (0.57). Los resultados sugieren que en condiciones naturales existe un recurso genético importante para esta especie. La poca variación en el tamaño de fruto, puede ser útil para la selección de cultivares de V. meridionale y se constituye un rasgo objetivo para fitomejoradores. Los resultados de este estudio también pueden ser aplicados en programas de conservación para proteger estas poblaciones diversas en los bosques de montaña de Colombia.