Obituary: William Mark Whitten (1954−2019)

On April 11, 2019, Dr. William Mark Whitten, a prolific neotropical orchid biologist passed away unexpectedly. He leaves an extensive corpus of work focused on (but not limited to) orchid pollination and systematics, and over four thousand beautifully prepared herbarium specimens. Everyone that met Mark can agree that he was a wonderful human being, kind to everyone, incredibly knowledgeable and yet very humble. Always of a calm demeanor, great sense of humor, and willingness to help, Mark was an outstanding and relatable collaborator, and his publications (more than a hundred; see list below) are evidence of a productive and highly collaborative academic career.UCR::Vicerrectoría de Docencia::Ciencias Básicas::Facultad de Ciencias::Escuela de BiologíaUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Jardín Botánico Lankester (JBL

Altered Gene Regulatory Networks Are Associated With the Transition From C3 to Crassulacean Acid Metabolism in Erycina (Oncidiinae: Orchidaceae)

Crassulacean acid metabolism (CAM) photosynthesis is a modification of the core C3 photosynthetic pathway that improves the ability of plants to assimilate carbon in water-limited environments. CAM plants fix CO2 mostly at night, when transpiration rates are low. All of the CAM pathway genes exist in ancestral C3 species, but the timing and magnitude of expression are greatly altered between C3 and CAM species. Understanding these regulatory changes is key to elucidating the mechanism by which CAM evolved from C3. Here, we use two closely related species in the Orchidaceae, Erycina pusilla (CAM) and Erycina crista-galli (C3), to conduct comparative transcriptomic analyses across multiple time points. Clustering of genes with expression variation across the diel cycle revealed some canonical CAM pathway genes similarly expressed in both species, regardless of photosynthetic pathway. However, gene network construction indicated that 149 gene families had significant differences in network connectivity and were further explored for these functional enrichments. Genes involved in light sensing and ABA signaling were some of the most differently connected genes between the C3 and CAM Erycina species, in agreement with the contrasting diel patterns of stomatal conductance in C3 and CAM plants. Our results suggest changes to transcriptional cascades are important for the transition from C3 to CAM photosynthesis in Erycina

REVISION DE EVIDENCIAS EN INFECCIONES ASOCIADAS A LA ATENCIÓN EN SALUD POR CATÉTER VENOSO CENTRAL

Objetivo: Adquirir conocimientos y así ampliar las competencias y habilidades. El grupo investigador realizó una revisión de la literatura, indagando en bases de datos científicas en un periodo comprendido entre los años 2005-2015.Metodología: Estudio cualitativo de revisión de bibliografías que consistió en la búsqueda de literatura científica; tuvo una población de 50 artículos y una muestra de 36 artículos buscadas en diferentes bases de datos. Los criterios de inclusión tenidos en cuenta para los artículos es que estos fuesen publicados en el periodo 2005-2015, escritos en idioma español, inglés o portugués. Se excluyeron estados del arte, monografías, tesis y artículos que no cumpliesen con el período de tiempo establecido.Resultados: Los estudios se basaron en variables sociodemográficas y epidemiológicas en las cuales incluyeron pacientes de todas las edades y sexos, con una población de 3294 pacientes de ambos sexos mayores. El microorganismo más frecuente fue Staphylococcus coagulasa (-), los factores de riesgo más frecuentes fueron inserción del catéter sin barreras estériles, dificultades durante la colocación, colonización bacteriana del sitio de inserción, localización de la vía en la vena femoral, nutrición parenteral total, transfusiones, permanencia del catéter por más de 7 días, diagnóstico, edad, y peso del paciente, inmunosupresión.Conclusión: Este estudio nos permite identificar las causas que pueden desencadenar una infección asociada a la atención en salud por diferentes factores referentes a la técnica de invasión por cáteter venoso central

Byrsonima crassifolia

Angiosperm

Crassulacean acid metabolism in tropical orchids: integrating phylogenetic, ecophysiological and molecular genetic approaches

Crassulacean Acid Metabolism (CAM) is a water-conserving mode of photosynthesis present in approximately 7% of vascular plant species worldwide. CAM photosynthesis minimizes water loss by limiting CO2 uptake from the atmosphere at night, improving the ability to acquire carbon in water and CO2-limited environments. In neotropical orchids, the CAM pathway can be found in up to 50% of species. To better understand the role of CAM in species radiations and the molecular mechanisms of CAM evolution in orchids, we performed carbon stable isotopic composition of leaf samples from 1,102 species native to Panama and Costa Rica, and character state reconstruction and phylogenetic trait analysis of CAM and epiphytism. When ancestral state reconstruction of CAM is overlain onto a phylogeny of orchids, the distribution of photosynthetic pathways shows that C3 photosynthesis is the ancestral state and that CAM has evolved independently several times within the Orchidaceae. Using phylogenetic trait analysis, we found that divergences in photosynthetic pathway and epiphytism are consistently correlated through evolutionary time and are related to the prevalence of CAM epiphytes in lower elevations and abundant species diversification of high elevation epiphytes. The multiple independent evolutionary origins of CAM in orchids suggest that evolution from C3 to weak and strong CAM might involve relatively few genetic changes. In plants performing CAM, phosphoenolpyruvate carboxylase (PEPC) catalyzes the initial fixation of atmospheric CO2 into C4-dicarboxylic acids forming oxaloacetate and inorganic phosphate as a product. PEPC is a ubiquitous enzyme that belongs to a multigene family with each gene encoding a function- and tissue-specific isoform of the enzyme. CAM-specific PEPC isoforms might have evolved from ancestral nonphotosynthetic C3 isoforms by gene duplication and acquired transcriptional control sequences that mediate increased mRNA expression and leaf-specific or leaf-preferential expression patterns. In order to understand patterns of PEPC family diversification over evolutionary times, PEPC genes families in ten closely-related orchid species from the Subtribe Oncidiinae with a range of photosynthetic pathways from C3-photosynthesis (Oncidium maduroi, Ticoglossum krameri, and Oncidium sotoanum) to weak CAM (Oncidium panamense, Oncidium sphacelatum, Gomesa flexuosa and Rossioglossum insleayi) to strong CAM (Rossioglossum ampliatum, Trichocentrum nanum, and Trichocentrum carthaginense) were characterized. At least three major changes are hypothesized to have occurred during evolution to adapt the CAM progenitor genes for function in CAM plants: 1) CAM isoform genes in orchids have evolved highly expressed mRNA expression patterns; 2) leaf preferential (or specific) expression patterns; and 3) circadian clock control expression patterns. We found that up to five PEPC isoforms are present in orchids, with one putative CAM-specific PEPC isogene with discrete amino acid changes identified in CAM species based on cDNA clone sampling, and an evident shift in PEPC isoform number from 2-3 isoforms in C3 species, to 3-4 isoforms in weak CAM species, to 4-5 isoforms in strong CAM species. Validation of the isotopic analysis and the molecular genetic analysis of PEPC gene family using 24- hour gas exchange showed that weak CAM species exhibit limited amounts of nocturnal CO2 uptake and fixation when compared to strong CAM species. To understand the molecular mechanisms responsible for the recruitment of CAM-specific genes, 454 sequencing of cDNA prepared from RNA of the strong CAM species Rossioglossum ampliatum was conducted, and resulted in 189 Mb of DNA sequence, 41,115 contigs, and 100,889 singletons. A NimbleGen microarray constructed and used in a C3 species (Oncidium maduroi), a weak CAM species (Oncidium panamense) and a strong CAM species (Rossioglossum ampliatum), showed that C3 and weak CAM species had average hybridization intensities that diverged from the strong CAM species by 2 and 3 percent, respectively. From 13,566 genes that showed a significant 4.6-fold difference in expression levels from the comparisons between CAM, C3 and weak CAM, 4,520 genes showed a greater than 4.6-fold increase in the ratio of CAM/C3 relative transcript abundance, whereas 3,745 genes showed a greater than 4.6- fold decrease in the ratio of CAM/C3 relative transcript abundance. A maximal increase or decrease in relative transcript abundance of more than 1,000- and 500-fold, respectively, was observed. The results of the microarray analysis will serve as a catalogue of gene expression patterns available for future work aimed at understanding CAM specific expression patterns, and can be used to further understand gene regulation by in-depth analysis of the transcriptional control regions responsible for altered gene expression patterns associated with CAM evolution. Several patterns of CAM evolution have been demonstrated in orchids, thus improving our understanding of the functional significance and evolutionary origins of CAM. The results of this project will aid in understanding photosynthetic plasticity in plants

Crassulacean Acid Metabolism and Epiphytism Linked to Adaptive Radiations in the Orchidaceae1[OA]

Species of the large family Orchidaceae display a spectacular array of adaptations and rapid speciations that are linked to several innovative features, including specialized pollination syndromes, colonization of epiphytic habitats, and the presence of Crassulacean acid metabolism (CAM), a water-conserving photosynthetic pathway. To better understand the role of CAM and epiphytism in the evolutionary expansion of tropical orchids, we sampled leaf carbon isotopic composition of 1,103 species native to Panama and Costa Rica, performed character state reconstruction and phylogenetic trait analysis of CAM and epiphytism, and related strong CAM, present in 10% of species surveyed, to climatic variables and the evolution of epiphytism in tropical regions. Altitude was the most important predictor of photosynthetic pathway when all environmental variables were taken into account, with CAM being most prevalent at low altitudes. By creating integrated orchid trees to reconstruct ancestral character states, we found that C3 photosynthesis is the ancestral state and that CAM has evolved at least 10 independent times with several reversals. A large CAM radiation event within the Epidendroideae, the most species-rich epiphytic clade of any known plant group, is linked to a Tertiary species radiation that originated 65 million years ago. Our study shows that parallel evolution of CAM is present among subfamilies of orchids, and correlated divergence between photosynthetic pathways and epiphytism can be explained by the prevalence of CAM in low-elevation epiphytes and rapid speciation of high-elevation epiphytes in the Neotropics, contributing to the astounding diversity in the Orchidaceae

Occurrence of crassulacean acid metabolism in Colombian orchids determined by leaf carbon isotope ratios

Abstract: Many Orchidaceae, especially those occupying periodically dry, epiphytic microhabitats in the humid tropics, are believed to engage in the water-conserving crassulacean acid metabolism (CAM) photosynthetic pathway. However, the photosynthetic pathway has been studied in only c. 5% of all orchid species. Here we extend the survey to 1079 orchid species, mainly from Colombia, by assessing the presence of CAM based on the carbon isotopic signature (δ 13C values) of herbarium specimens. Ninety-six species, representing 8.9% of those analysed, had δ 13C values less negative than −20‰, indicating CAM. Epiphytism was the predominant life form (75.2% of species sampled), and 9.4% of these epiphytes showed a CAM-type isotopic signature. Isotope values suggested CAM in 19 terrestrial orchid species, 14 species from high elevation (2000–3400 m) and species from six genera that were previously unknown to engage in CAM (Jacquiniella, Meiracyllium, Pabstiella, Psychopsis, Pterostemma and Solenidium). We conclude that CAM is the major pathway of carbon acquisition in a small but broadly distributed fraction of tropical orchids and is more prevalent at lower elevations