Análisis estructural y cromático como método de clasificación taxonómica: estudio fisicoquímico de las escleritas de octocorales del género pacifigorgia
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Fecha
2024-07-30
Tipo
tesis de maestría
Autores
Arturo Josué Álvarez Valverde
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RESUMEN
Este estudio investiga las características fisicoquímicas de las escleritas de octocorales del género Pacifigorgia con el objetivo de establecer una base para su clasificación taxonómica. Se utilizaron varias técnicas para caracterizar las escleritas e identificar los compuestos orgánicos en los pigmentos. Una combinación de difracción de rayos-X en polvos y espectroscopía infrarroja reveló que las escleritas de Pacifigorgia están compuestas de calcita magnésica y materia orgánica intracristalina, conformada por pigmentos, oligosacáridos y proteínas ácidas. El análisis estructural con microscopía electrónica de barrido (SEM) mostró escleritas mesocristalinas hechas de columnas de calcita submicrométricas formadas por gránulos cristalinos nanométricos.
La microscopía Raman indicó que los pigmentos que dan color a los octocorales son polienales parcialmente metilados, dónde la longitud de cadena determina el color observado. El estudio sugirió que sutiles diferencias estructurales, la combinación de varios pigmentos muy similares entre sí y su concentración en la matriz mineral determinan los tonos específicos y la saturación de cada muestra. Los estudios de fluorescencia identificaron bandas de emisión específicas correspondientes a la autofluorescencia de proteínas, centros fluorescentes de calcita y pigmentos. El análisis cromático de fotografías digitales en el espacio de color RGB proporcionó datos cuantitativos y cualitativos sobre el color y la estructura de las escleritas.
Los métodos estadísticos multivariantes demostraron que los análisis de color en fotografías digitales podrían utilizarse para apoyar la diferenciación entre especies de Pacifigorgia. Además, los análisis de componentes principales mostraron que la microscopía visible-NIR también es efectiva para lograr esta tarea y se identificó como el segundo mejor método para distinguir entre especies. Aunque la microscopía de fluorescencia fue menos efectiva, muestra potencial como un potencial nuevo carácter taxonómico. La microscopía Raman e infrarroja fueron ineficaces para la diferenciación de especies, y el SEM y la difracción de rayos X en polvo no fueron adecuadas para la distinción de especies.
ABSTRACT This study investigates the physicochemical characteristics of octocoral sclerites from the genus Pacifigorgia with the objective to establish a basis for taxonomic classification. Various techniques were used to characterize the sclerites and identify the organic compounds in the pigments. A combination of powder X-ray diffraction and infrared spectroscopy revealed that Pacifigorgia sclerites are composed of magnesium calcite with intracrystalline organics, including pigments, oligosaccharides, and acidic proteins. Structural analysis with scanning electron microscopy (SEM) showed mesocrystalline sclerites made of sub-micrometric calcite columns formed by nanometric crystalline granules. Raman microspectroscopy indicated that the pigments which give octocorals their coloration are partially methylated polyenals, with chain length affecting the color. The study suggested that subtle structural differences, the combination of similar pigments and their concentration in the mineral matrix determine the specific hues and saturation of each sample. Fluorescence studies identified specific emission bands corresponding to protein autofluorescence, calcite fluorescent centers, and pigments. The chromatic analysis of digital photographs using RGB color space provided quantitative and qualitative data on sclerite color and structure. Multivariate statistical analysis of variance demonstrated that color analysis of digital photographs could be used to differentiate between species of Pacifigorgia. Additionally, a principal component analysis showed that visible-NIR microspectroscopy was also effective to accomplish this task and was identified as the second-best method to distinguish between species. Although fluorescence microspectroscopy was less effective, it shows potential as a new taxonomic characteristic. Raman and infrared microspectroscopy were ineffective for species differentiation, and SEM and powder X-ray diffraction were unsuitable for species distinction.
ABSTRACT This study investigates the physicochemical characteristics of octocoral sclerites from the genus Pacifigorgia with the objective to establish a basis for taxonomic classification. Various techniques were used to characterize the sclerites and identify the organic compounds in the pigments. A combination of powder X-ray diffraction and infrared spectroscopy revealed that Pacifigorgia sclerites are composed of magnesium calcite with intracrystalline organics, including pigments, oligosaccharides, and acidic proteins. Structural analysis with scanning electron microscopy (SEM) showed mesocrystalline sclerites made of sub-micrometric calcite columns formed by nanometric crystalline granules. Raman microspectroscopy indicated that the pigments which give octocorals their coloration are partially methylated polyenals, with chain length affecting the color. The study suggested that subtle structural differences, the combination of similar pigments and their concentration in the mineral matrix determine the specific hues and saturation of each sample. Fluorescence studies identified specific emission bands corresponding to protein autofluorescence, calcite fluorescent centers, and pigments. The chromatic analysis of digital photographs using RGB color space provided quantitative and qualitative data on sclerite color and structure. Multivariate statistical analysis of variance demonstrated that color analysis of digital photographs could be used to differentiate between species of Pacifigorgia. Additionally, a principal component analysis showed that visible-NIR microspectroscopy was also effective to accomplish this task and was identified as the second-best method to distinguish between species. Although fluorescence microspectroscopy was less effective, it shows potential as a new taxonomic characteristic. Raman and infrared microspectroscopy were ineffective for species differentiation, and SEM and powder X-ray diffraction were unsuitable for species distinction.
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Palabras clave
Octocorales, Análisis cromático, Análisis estructural, Taxonomía, Pacifigorgia, Escleritas