Optimización de parámetros para la propagación in vitro de Colobanthus quitensis (Kunth) Bartl

Colobanthus quitensis is one of the two native vascular plants that inhabit Antarctica. In addition, it spreads from the south of Mexico to the north of the Antarctic Peninsula and from 0 to 4200 m asl, always in extreme habitats. It is considered a model species for abiotic stress studies. Due to its small size and low accessibility to its habitats, efficient propagation methods are required to maintain it in the laboratory. The aim of this work was to optimize some critical parameters in the in vitro propagation of this species related to physical and chemical aspects to avoid negative effects such as explants yellowing and death and improve the conditioning of new plantlets, as well as response to different hormonal combinations. Explants from previously established in vitro seedlings were used. When the vessels were covered with a double layer of aluminum foil, water loss in the medium and the tissues was avoided, as well as the yellowing of the buds was reduced. The addition of silver thiosulfate to the medium stimulated the regeneration of buds and roots, and at a concentration of 10 ?M inhibited the yellowing and death, of buds by 50% and 25%, respectively. At 28 days of culture in the glass vessels, 49% less yellowing was observed, 7% more new buds and 24% more roots than in the Magenta box. The light intensity between 28-45 ?mol m-2 s-1 decreased the negative effects and stimulated regeneration. C. quitensis responds to different hormonal combinations, but more studies are needed to establish the optimal combination for the individuals originated from different habitats.Colobanthus quitensis es una de las dos plantas vasculares nativas que habitan en la Antártica. Además, se distribuye desde el sur de México hasta el norte de la Península Antártica y desde los 0 hasta los 4.200 m s.n.m., siempre en hábitats extremos. Es considerada una especie modelo para estudios en estrés abióticos. Debido a su pequeño tamaño y la poca accesibilidad a sus hábitats es necesario disponer de métodos eficientes de propagación para mantenerla en el laboratorio. El objetivo del presente trabajo fue optimizar algunos parámetros críticos en la propagación in vitro de esta especie relacionados con aspectos físicos y químicos para evitar efectos negativos como el amarillamiento y muerte de explantes y mejorar el condicionamiento de las nuevas plántulas, así como la respuesta a diferentes combinaciones hormonales. Se utilizaron explantes provenientes de plántulas previamente establecidas in vitro. La cobertura de los frascos con doble capa de papel aluminio evitó la pérdida de agua en el medio y en los tejidos, así como también disminuyó el amarillamiento de los brotes. La adición de tiosulfato de plata al medio estimuló la regeneración de brotes y raíces, en la concentración de 10 ?M inhibió en un 50% y un 25% el amarillamiento y muerte de brotes, respectivamente. A los 28 días de cultivo en el frasco de vidrio se observó 49% menos de amarillamiento, 7% más de nuevos brotes y 24% de raíces que en la caja Magenta. La intensidad lumínica entre los 28-45 ?mol m-2 s-1 disminuyó los efectos negativos y estimuló la regeneración. C. quitensis responde a diferentes combinaciones hormonales, pero más estudios son necesarios para establecer la combinación óptima para los individuos provenientes de los diferentes hábitats

Depression symptoms and mortality in elderly peruvian navy veterans: a retrospective cohort study

Abstract: Our study was design to determine the association between depressive symptoms and mortality in adults over 60 years old Navy Peruvian Veterans. We performed a retrospective cohort study based on a previous cohort study. A total of 1681 patients over 60 years old were included between 2010–2015. Demographic information, self-reported information about falls, physical frailty assessment, tobacco consumption, hypertension, Type 2 Diabetes Mellitus, Chronic Obstructive Pulmonary Disease and was collected. Depression was assessed by the short form of the Geriatric Depression Scale. We found that depressive symptoms were present in 24.9% of the participants and 40.5% of them died. Mortality risk in patients with depressive symptoms, physical frailty, and male sex was: RR of 23.1 (95% CI: 11.7–45.7), 3.84 (95% CI: 2.16–6.82), and 1.37 (95% CI: 1.07–1.75) respectively. We concluded that depressive symptoms in Peruvian retired military personnel and their immediate relatives are high and are significatively associated with mortality. Also, being male and frail was associated with an increased risk of death. This reinforces that early detection and assessment of depressive symptoms could be an opportunity to improve the health status of older adults

Multiple late-Pleistocene colonisation events of the Antarctic pearlwort Colobanthus quitensis (Caryophyllaceae) reveal the recent arrival of native Antarctic vascular flora

Aim: Antarctica's remote and extreme terrestrial environments are inhabited by only two species of native vascular plants. We assessed genetic connectivity amongst Antarctic and South American populations of one of these species, Colobanthus quitensis, to determine its origin and age in Antarctica. Location: Maritime Antarctic, sub‐Antarctic islands, South America. Taxon: Antarctic pearlwort Colobanthus quitensis (Caryophyllaceae). Methods: Four chloroplast markers and one nuclear marker were sequenced from 270 samples from a latitudinal transect spanning 21–68° S. Phylogeographic, population genetic and molecular dating analyses were used to assess the demographic history of C. quitensis and the age of the species in Antarctica. Results: Maritime Antarctic populations consisted of two different haplotype clusters, occupying the northern and southern Maritime Antarctic. Molecular dating analyses suggested C. quitensis to be a young (<1 Ma) species, with contemporary population structure derived since the late‐Pleistocene. Main conclusions: The Maritime Antarctic populations likely derived from two independent, late‐Pleistocene dispersal events. Both clusters shared haplotypes with sub‐Antarctic South Georgia, suggesting higher connectivity across the Southern Ocean than previously thought. The overall findings of multiple colonization events by a vascular plant species to Antarctica, and the recent timing of these events, are of significance with respect to future colonizations of the Antarctic Peninsula by vascular plants, particularly with predicted increases in ice‐free land in this area. This study fills a significant gap in our knowledge of the age of the contemporary Antarctic terrestrial biota. Adding to previous inferences on the other Antarctic vascular plant species (the grass Deschampsia antarctica), we suggest that both angiosperm species are likely to have arrived on a recent (late‐Pleistocene) time‐scale. While most major groups of Antarctic terrestrial biota include examples of much longer‐term Antarctic persistence, the vascular flora stands out as the first identified terrestrial group that appears to be of recent origin

Phenotypic variability and genetic differentiation in continental and island populations of Colobanthus quitensis (Caryophyllaceae: Antarctic pearlwort)

Colobanthus quitensis (Antarctic pearlwort) is one of the only two native vascular plants to inhabit the extreme environmental conditions of Antarctica. Colobanthus quitensis has a wide geographic distribution, both in latitude and altitude, and always inhabits extreme environments. This makes it crucial for understanding environmental tolerance mechanisms, and a useful model for studies regarding genetic diversity and intraspecific morphology. Several morphological and molecular descriptors were applied to C. quitensis populations, constituting the first study of its kind in these species. We postulated that morphological variability is strongly linked to geographic distribution, and that this is manifested in external morphological characteristics and genetic structure. A large intra- and interpopulational morphological variability was verified. Both morphological variability and genetics made it possible to form two separate groups between continental and Antarctic island populations. The genetic diversity was high to moderate with the least amount of diversity towards the north. The genetic structure was high, and the gene flow between populations was low. The correlation between morphological, genetic, geographic and altitudinal distances permits the proposal of an isolation by distance model that can be used between populations with high Bio-geographical influence. Understanding what factors lead to local or colonization adaptation, and determining the morphological variations and genetic differentiation in populations of C. quitensis, is vital for the understanding of the evolutionary history that has contributed to the success of the establishment of this species in an environment as extreme as Antarctica. Additionally, this study demonstrates the usefulness of the combined use of morpho-physiological and molecular markers for variability and diversity studies.Chilean Antarctic Institute INACH RT_03-09 INACH RG_02-1