Vol. 27, Nº 1: Enero - Abril (2018)
http://bdigital2.ula.ve:8080/xmlui/654321/567
2024-03-28T16:38:10ZMICROSCOPIC TECHNIQUES IN THE DETERMINATION OF THE BIODETERIORATION IN CINEMATOGRAPHIC FILMS
http://bdigital2.ula.ve:8080/xmlui/654321/1673
MICROSCOPIC TECHNIQUES IN THE DETERMINATION OF THE BIODETERIORATION IN CINEMATOGRAPHIC FILMS
Vivar, I.; Borrego, S. F.; García, A.M.
For years, the researchers have been interested in studying the deterioration caused by microorganisms in the cinematographic heritage. To study the biodeterioration caused by microorganisms not only techniques of identification of microorganisms are used but also the microscopic techniques to observe of their structures and the damages in the materials. In Cuba, electron and epifluorescence microscopy are applied in multiple branches of scientific research but so far it is unknown to use it to study the affectation that may have the biodeteriorated documentary supports in our heritage institutions. Therefore the aim of the present work is to apply different microscopic techniques to study the biodeterioration caused by microorganisms in cinematographic films of patrimonial value. Optical microscopy, environmental scanning electron microscopy (ESEM), vacuum scanning electron microscopy (SEM) and epifluorescence microscopy (EPI) were
used. An important microbial colonization, fundamentally fungal on both sides of the films was evidenced with the ESEM and SEM. In addition, a dense biofilm and a bio-fouling formed mainly by mites and pollens were observed. The presence of small holes in the fungal structures as a result of the lytic activity of the bacteria was observed. For the other hand, fluorescence microscopy showed that the majority of the microorganisms on the films were still viable and active. For the first time in Cuba, the microscopic techniques were used to evidence the presence of viable and active microorganisms. Those microorganisms are responsible of the biodeterioration in cinematographic films of heritage value.
2017-11-01T00:00:00ZPALYNOLOGY OF TWENTY ONE SPECIES OF ECHEVERIA GENUS (CRASSULACEAE) FROM MEXICO – HIGH RESOLUTION STUDY
http://bdigital2.ula.ve:8080/xmlui/654321/1672
PALYNOLOGY OF TWENTY ONE SPECIES OF ECHEVERIA GENUS (CRASSULACEAE) FROM MEXICO – HIGH RESOLUTION STUDY
González-Mancera, G.; Reyes-Santiago, P.J.; de la Cruz-López, L.E.; Islas-Luna, M.A.; Sánchez-Sauza, M.A.; Flores-García, M.A.; Vergara-Silva, F.
Mexico has the largest diversity of genus Echeveria. To preserve the biological diversity of this highly endemic plant group, as well as to make its industrial production sustainable, the complete knowledge of their attributes is needed. Nevertheless, few taxonomic characteristics for the genus have been registered so far (little of its taxonomy is known, especially about its palynology); some species have not been described yet, and consequently they are not associated to any taxonomic name. The main aim of this paper is to provide data about its palynology. This work characterizes by Scanning Electron Microscope (SEM) the acetolysed pollen of species of the genus Echeveria (Crassulaceae). Twenty species of Echeveria were studied. The samples were subjected to acetolysis, and processed according to conventional method to be analyzed by SEM. The results revealed the following characteristics for Echeveria pollen: it presented isopolar symmetry; solitary free grain; regularly spheroidal shape, mostly with three compound apertures but sometimes with four; size range from small to medium; morphological features that indicate process of harmomegathy. Exine presented ornamentation typically regulate, and sub-layer structure not continuous (semitectate).
2017-11-01T00:00:00ZCARACTERIZACIÓN HISTOLÓGICA DE ADAPTACIONES DE LA RETINA DE PECES ANUALES Austrolebias charrua, EN RELACIÓN A CAMBIOS EN LA LUMINOSIDAD EN SU CICLO DE VIDA
http://bdigital2.ula.ve:8080/xmlui/654321/1671
CARACTERIZACIÓN HISTOLÓGICA DE ADAPTACIONES DE LA RETINA DE PECES ANUALES Austrolebias charrua, EN RELACIÓN A CAMBIOS EN LA LUMINOSIDAD EN SU CICLO DE VIDA
Berrosteguieta, I.; Rosillo, J. C.; Torres-Pérez, M.; Fernández, A. S.
Si bien la retina posee una citoarquitectura conservada en los vertebrados, es sabido que sus características dependen de la especie y de las condiciones lumínicas del entorno. Austrolebias charrua es un pez anual que vive en charcos donde la luminosidad varía drásticamente en su corto ciclo de vida. En este trabajo se aplicaron las técnicas de: Cajal de Castro, Inmunohistoquímica, marcado con un trazador neuronal (DiI) y Microscopía Electrónica de Transmisión (MET) con el fin
de identificar posibles características de la retina que le permitan adaptarse a un medio lumínico cambiante. La técnica Cajal de Castro y la Inmunohistoquímica, revelaron la composición celular y los grosores de las capas de la retina, característicos de peces con hábitos diurnos. Sin embargo, la capa de células ganglionares mostró una organización en grupos celulares separados por haces axonales, disposición descrita en la retina de peces nocturnos. La MET nos proporcionó detalles
ultraestructurales de los fotorreceptores. En particular se evidenció la distribución de los melanosomas del epitelio pigmentario, que se encuentran distribuidos tanto a lo largo de los segmentos externos e internos de los fotorreceptores como a nivel perinuclear de las células del epitelio pigmentario. Los animales adaptados a la luz presentan una distribución de melanosomas a lo largo de los segmentos de los fotorreceptores, mientras que en los adaptados a la oscuridad los pigmentos se ubican en la zona perinuclear. Este resultado nos permite proponer que A. charrua posee características histomorfológicas que le permiten adaptarse a un medio de luz variable.
2017-11-01T00:00:00ZFUNGI INVOLVED IN BIODETERIORATION OF DOCUMENTS IN PAPER AND EFFECT ON SUBSTRATE
http://bdigital2.ula.ve:8080/xmlui/654321/1670
FUNGI INVOLVED IN BIODETERIORATION OF DOCUMENTS IN PAPER AND EFFECT ON SUBSTRATE
Borrego, S.; Guiamet, P.; Vivar, I.; Battistoni, P.
Fungi damage valuable documents mechanically, chemically and aesthetically because they form hyphae, excrete pigments and organic acids, generating particular local conditions that modify the physical-chemical properties of the different documentary supports. The aims of this research were to determine the fungal genera associated with the paper documents biodeterioration and to demonstrate the biofilm formation and the damages. Sampling was done from documents with signs of biodeterioration using sterile cotton swabs. After serial dilutions from the samples, plates with Extract Malt Agar were inoculated and incubated at 30 °C for 7 days. Additional little fragments of the damage zone from each analyzed document were observed using stereomicroscopy, environmental scanning electron microscopy (ESEM) and scanning electron microscopy (SEM). To evaluate the biodeterioration potential risk the strains were grown on cellulose, the acids production
and pigments secretion were evaluated too. The genera Aspergillus, Cladosporium, Fusarium and Scopulariopsis were predominant. Isolated strains excreted acids into the culture medium; most of them grew well on cellulose and a few excreted pigments. The formation of a mature biofilm and the production of extracellular polymeric substances by fungi, as well as a dense biofouling mainly formed by dust mites, were evidenced by the SEM and ESEM observations. Also the observations showed that these strains were able to attach to paper fibre causing damage on them. The observation underoptical microscopy of dead insect found inside the book showed fungal adhesion on the insect body and SEM support that this adhesion was formed by Aspergillus sp.
2017-11-01T00:00:00Z