Jaime Jiménez-Ramírez

Lacandonia granules are present in Ginkgo biloba cell nuclei

Summry— Lacandonia schismatica is a rare flowering plant with the sex organs spatially inverted. Several aspects of its cell biology are now known. Interestingly, within the cell nucleus, the chromatin is reticulated and it is associated to a novel structure named Lacandonia granules, a very abundant ribonucleoprotein particle showing similarities to perichromatin and Balbiani ring granules, which are involved in nuclear mRNA metabolism. To see whether these particles are present in other plants, we study the nucleus of Ginkgo biloba, a non‐flowering plant. Light, electron and atomic force microscopy show that the cell nuclei of G. biloba are reticulated. Ultrastructural analysis showed that in the nucleoplasm, abundant intranuclear particles 32 nm in diameter are present. The EDTA regressive staining suggested that they contain RNA. Ultrastructural in situ hybridization confirmed the presence of RNA in these particles. Therefore, we conclude that the nuclei of G. biloba are reticulated and contain Lacandonia granules. We suggest that these particles may also be present in other plants.

Una nueva especie de Desmopsis (Annonaceae) endémica de Guerrero, México

Desmopsis guerrerensis, a new species endemic to Guerrero, Mexico is described and illustrated. The new species is related to Desmopsis verrucipes, endemic to Costa Rica, but it differs in several morphological characters and geographical distribution. A key to the species of Desmopsis of Mexico and Central America that have persistent sepals in fruit is presented.ResumenSe describe e ilustra a Desmopsis guerrerensis, como una especie nueva, endémica del estado de Guerrero, México. El nuevo taxón es afín a Desmopsis verrucipes, especie endémica de Costa Rica, pero difiere en varios caracteres morfológicos y en la distribución geográfica. Se incluye una clave para las especies de Desmopsis con cáliz persistente en el fruto de México y Centroamérica.

Improved method for genomic DNA extraction for Opuntia Mill. (Cactaceae)

BackgroundGenomic DNA extracted from species of Cactaceae is often contaminated with significant amounts of mucilage and pectin. Pectin is one of the main components of cellular walls, whereas mucilage is a complex polysaccharide with a ramified structure. Thus, pectin- and mucilage-free extraction of DNA is a key step for further downstream PCR-based analyses.ResultsWe tested our DNA extraction method on cladode tissue (juvenile, adult, and herbaria exemplars) of 17 species of Opuntia Mill., which are characterized by a large quantity of pectin and mucilage.ConclusionWe developed a method for the extraction of gDNA free of inhibitory compounds common in species of Opuntia Mill., such as pectin and mucilage. Compared to previously extraction protocols, our method produced higher yields of high-quality genomic DNA.

Morphological variation related with environmental factors in endemic and threatened Jatropha species of Tehuacan-Cuicatlan, Mexico

Jatropha spp. from Mexico includes high species richness and endemism; five species inhabit in the Tehuacan-Cuicatlan Biosphere Reserve (TCBR), and they are important resources as food, medicine and biofuel. The assessment of morphological and agronomic characteristics is essential to identify, use and maintain plant genetic resources. Given the lack of information on the morphological variability of Jatropha species in relation to environment, the objective was to analyze the influence of physiographic, climatic, and anthropogenic factors in the morphological variability of the species: Jatrophaneopauciflora and J. rzedowskii, both not-endangered; J. oaxacana, special protection; J. ciliata and J. rufescens, both endangered in the Reserve. Twelve quantitative morphological variables were measured in 24 populations of these species; 14 environmental variables were registered, and the disturbance index in the sites was estimated. The information was analyzed with Principal Components Analysis (PCA), Cluster Analysis and Canonical Correspondence Analysis (CCA). PCA detected interspecific variation: J. ciliata and J. rufescens have longer and broader leaves and longer flowers, while the other three species have smaller leaves and flowers. J. oaxacana population has intermediate size of leaves, fruits and seeds, compared with those of J. neopauciflora and J. rzedowskii. CCA detected intra-specific variation among the populations of J. neopauciflora and J. rzedowskii, which were separated in two groups due to fruit and seed size. Axis 1 of CCA correlated positively with altitude and annual temperature range, and negatively with mean annual temperature; at the intra-specific level, both species are adapted to variations of temperature and altitude.

EL GÉNERO ORMOSIA JACKS. (LEGUMINOSAE, PAPILIONOIDEAE) EN EL ESTADO DE GUERRERO, MÉXICO

Se registra por primera vez la presencia del genero Ormosia para el estado de Guerrero, Mexico, con dos especies: Ormosia carinata y O. oaxacana (Leguminosae, Papilionoideae, tribe Sophoreae). Se incluyen las descripciones de ambas, datos referentes a los ejemplares, una clave dicotomica para diferenciarlas, y la ilustracion de O. carinata. Ormosia carinata era conocida como elemento endemico de los estados de Veracruz y Oaxaca, en las regiones de Los Tuxtlas y de Uxpanapa

Magnolia guerrerensis (Magnoliaceae), a new species of cloud forest in the state of Guerrero, Mexico

Resumen es: Resumen: Se propone e ilustra a Magnolia guerrerensis (Magnoliaceae) como una entidad nueva del bosque mesofilo de montana en el estado de Guerrero, Mex...