DIVERSIDAD GENÉTICA Y MEJORAMIENTO DE PLANTAS MEDICINALES= Medicinal plants and improvement of medicinal herbs

Plants produce small RNAs to neg. regulate genes, viral nucleic acids, and repetitive elements at either the transcriptional or post-transcriptional level in a process that is referred to as RNA silencing. While RNA silencing has been extensively studied across the different phyla of the animal kingdom (e.g., mouse, fly, worm), similar studies in the plant kingdom have focused primarily on angiosperms, thus limiting evolutionary studies of RNA silencing in plants. Here we report on an unexpected phylogenetic difference in the size distribution of small RNAs among the vascular plants. By extg. total RNA from freshly growing shoot tissue, we conducted a survey of small RNAs in 24 vascular plant species. We find that conifers, which radiated from the other seed-bearing plants .apprx.260 million years ago, fail to produce significant amts. of 24-nucleotide (nt) RNAs that are known to guide DNA methylation and heterochromatin formation in angiosperms. Instead, they synthesize a diverse population of small RNAs that are exactly 21-nt long. This finding was confirmed by high-throughput sequencing of the small RNA sequences from a conifer, Pinus contorta. A conifer EST search revealed the presence of a novel Dicer-like (DCL) family, which may be responsible for the obsd. change in small RNA expression. No evidence for DCL3, an enzyme that matures 24-nt RNAs in angiosperms, was found. We hypothesize that the diverse class of 21-nt RNAs found in conifers may help to maintain organization of their unusually large genomes. 

ÚLTIMOS AVANCES EN LA QUÍMICA Y ACTIVIDADES BACTERIOLÓGICAS EN LAS PLANTAS MEDICINALES= Medicinal plants, last advances on chemistry and bacteria activities on the medicinal herbs

1) DNA barcoding involves sequencing a std. region of DNA as a tool for species identification.  However, there has been no agreement on which region(s) should be used for barcoding land plants.  To provide a community recommendation on a std. plant barcode, the authors compared the performance of 7 leading candidate plastid DNA regions (atpF-atpH spacer, matK gene, rbcL gene, rpoB gene, rpoC1 gene, psbK-psbI spacer, and trnH-psbA spacer).  Based on assessments of recoverability, sequence quality, and levels of species discrimination, the 2-locus combination of rbcL+matK was recommended as the plant barcode.  This core 2-locus barcode will provide a universal framework for the routine use of DNA sequence data to identify specimens and contribute toward the discovery of overlooked species of land plants.  Sequence data are deposited in GenBank/EMBL/DDBJ with accession nos. GQ247894-GQ248069, GQ248071-GQ248710, GQ248715-GQ249040, GQ273984-GQ273987, GQ274310-GQ274318, and GQ335519-GQ335521.

2) Araucaria (Araucaria araucana) is a conifer tree, endemic of Chile.  The seed of this tree, named pinon are composed principally of starch.  In this work, pinon seeds and the starch isolated from them were evaluated.  The pinon seeds are composed of starch (64%), dietary fiber (25%), total sugar (7%) and very low concns. of phenolic compds., lipids, proteins and crude fiber.  The process performed to isolate the starch from pinon was simple and easy to realize at lab. scale, with a yield of 36%.  Starch represents a 77% of the isolated starch.  The amylose content was 42%.  Lipids, protein and crude fiber were very low.  The starch hydration properties increased with the temp.  In the 6% suspension of starch, viscosity increases during the cooling period.  The starch granules of pinon were small and round shaped.  The aspects evaluated in this research, suggests that pinon seeds can be considered an interesting new starch source for the food industry.

3) Several lakes in Chile are near-important volcanic areas where eruption impacts can limit the quality of lacustrine sediments for reconstructing past environmental changes.  In this study, we report changes in diatoms, pollen, and chironomids assemblages after a tephra deposition in Lake Galletue (Chilean Andes).  A sediment core obtained from Lake Galletue (40 m water depth) was sliced in 1 cm intervals and subsamples were taken to analyze each proxy.  210Pb and 137Cs activities were measured to obtain the geochronol. and mineralogical analyses were performed to det. the mineral compn. of the tephra.  Diatom species compn. and productivity were modified when the lake received the tephra; Aulacoseira granulata decreased and was later replaced by Cyclotella af. glomerata.  After the tephra input, Aulacoseira granulata abundance increased to pre-disturbance levels and Cyclotella af. glomerata decreased.  These changes seem to suggest a momentary increase in lake nutrient levels after the tephra deposition.  Chironomid assemblages also decreased in head capsules just after the tephra deposition, but the most important change was the replacement of Ablabesmyia by Parakiefferiella, probably due to the sedimentol. changes produced by the input of coarse tephra grains.  Furthermore, unlike other studies, chironomid assemblages in Lake Galletue did not show a decrease drastically in diversity within the tephra layer.  The pollen anal. indicated that, prior to the volcanic event, the vegetal community was dominated by Nothofagus sp., Araucaria araucana, and Blechnum sp.-type.  After the tephra deposition, the same taxa are dominant, indicating that the volcanic event seems not produce changes in the vegetation.  Nevertheless, within the tephra layer it is possible to see an increase in Poaceae, which represent - due to the percolation process - the effect of eruption on the vegetation.
 According to our results, diatoms were the most sensitive proxy for describing the changes produced by tephra deposition into the aquatic ecosystem and, despite the noticeable changes in its sedimentol. properties; the lake seems to have a high resilience capacity, allowing it to return to pre-tephra input conditions.

PARTE UTILIZADA= Used part: Resina. 

ACCIÓN FARMACOLÓGICA= Pharmacological action: Balsámico (resina).

COMPOSICIÓN QUÍMICA= Chemical composition: The resin from the tree Araucaria araucana (Araucariaceae) has been used since pre-columbian times by the Mapuche amerindians to treat ulcers. The gastroprotective effect of the resin was assessed in the ethanol–HCl-induced gastric ulcer in mice showing a dose-dependent gastroprotective activity at 100, 200 and 300 mg/kg per os. The main three diterpene constituents of the resin, namely imbricatolic acid, 15-hydroxyimbricatolal and 15-acetoxyimbricatolic acid were isolated and evaluated for gastroprotective effect at doses of 50, 100 and 200 mg/kg. A dose-related gastroprotective effect with highly significant activity (P < 0.01) was observed at doses up to 200 mg/kg. At 100 mg/kg, the highest gastroprotective activity was provided by 15-hydroxyimbricatolal and 15-acetoxyimbricatolic acid, all of them being as active as the reference drug lansoprazole at 20 mg/kg. The cytotoxicity of the main diterpenes as well as lansoprazole was studied towards human lung fibroblasts (MRC-5) and determined by the MTT reduction assay. A concentration-dependent cell viability inhibition was found with IC50 values ranging from 125 up to 290 μM. Our results support the traditional use of the Araucaria araucana resin by the Mapuche culture. 

ZONA GEOGRÁFICA= Geografical zone: S. de Chile y Argentina (Neuquén). 

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Distribución: Regiones Biobio, Araucania, Los Rios.

Usos medicinales: La resina que sale del tronco se usa como parche para curar contusiones y heridas ulcerosas, y tambien como cicatrizante. Ademas, alivia dolores de cabeza provocados por jaquecas. Las semillas son galactogogas.

1) TOURSARKISSIAN, Martín. Plantas medicinales de Argentina : sus nombres botánicos, vulgares, usos y distribución geográfica. Buenos Aires : Hemisferio Sur, 1980, p.10.

2) SCHMEDA-HIRSCHMANN, Guillermo, et al. Gastroprotective effect of the Mapuche crude drug Araucaria araucana resin and its main constituents. Journal of Ethnopharmacology.  2005, vol.101, nº1-3, p.271-276.
 
3) DOLGOSHEINA, Elena V., et al. Conifers have a unique small RNA silencing signature. RNA. 2008, vol.14, nº8, p.1508-1515.
 
4) HOLLINGSWORTH, Peter M., et al. A DNA barcode for land plants. Proceedings of the National Academy of Sciences of the United States of America. 2009. V, vol.106, nº31, p.12794-12797.
 
5) HENRIQUEZ, Carolina, et al. Characterization of pinon seed (Araucaria araucana (Mol) K. Koch) and the isolated starch from the seed. Food Chemistry. 2008, Vol.107, nº2, p.592-601.
 
6) URRUTIA, Roberto, et al. Changes in diatom, pollen, and chironomid assemblages in response to a recent volcanic event in Lake Galletue (Chilean Andes). Limnologica. 2007, vol.37, nº1, p.49-62.

7) Plantas silvestres comestibles y medicinales de Chile y otras partes del mundo/Cordero R., Sebastián; Abella A., Lucía; Galvez L. Francisca; Corporación chilena de la madera: Concepción, 2017 . -- 292 p.