Reconstrucción de precipitación y temperatura con anillos de crecimiento anual del ciprés Taxodium mucronatum (Taxodiaceae) en Coahuila, México / Reconstruction of precipitation and temperature with annual growth rings of the cypress Taxodium mucronatum (Taxodiaceae) in Coahuila, Mexico

Introducción: La determinación del clima en cuencas productoras de agua, como la del río Sabinas, Coahuila, donde no existe información de su variabilidad, se puede estimar mediante anillos de crecimiento de ahuehuete (Taxodium mucronatum Ten.), especie longeva con anillos bien definidos, presente en las zonas ribereñas, constituye un "proxy" o método indirecto de la variabilidad climática interanual y multianual. Objetivo: Desarrollar una reconstrucción estacional de precipitación y temperatura máxima y analizar la influencia que ejercen fenómenos de circulación global en el crecimiento de la especie. Métodos: Los núcleos de crecimiento de T. mucronatum fueron datados a través de técnicas dendrocronológicas para producir una serie de ancho de anillo. Se utilizaron datos de mallas del clima de dos bases de datos para desarrollar el análisis de la función de respuesta con fines de reconstrucción climática. Resultados: Una cronología de anillo total de 218 años (1808-2018) se desarrolló con especímenes de T. mucronatum en parajes del Río Sabinas, con la que se generó una reconstrucción estacional de precipitación abril-junio y de temperatura máxima junio-julio. El periodo detectado más seco se presentó de 1815 a 1818 con una precipitación de 27.39 mm y una temperatura máxima de 41.16 °C; mientras que el año más húmedo fue 1828 con 393.72 mm. La cronología de anillo total se correlacionó con los índices de sequía SPEI y PDSI, y con índices de fenómenos atmosféricos como El Niño Oscilación del Sur, a través del Índice de Oscilación del Sur (SOI) y el índice Multivariado (MEI); Oscilación Decadal del Pacífico (PDO) y Oscilación Multidecadal del Atlántico (AMO). La relación entre el índice de anillo total y el del Índice Estandarizado de Precipitación Evaporación (SPEI) mostró significancia en el mes de junio (r = 0.52, P < 0.01), al igual que el Índice de Severidad de Sequía del Palmer (PDSI), PDSI anual (r = 0.38, P < 0.05). El SOI reconstruido noviembre-febrero, se asoció significativamente con la serie dendrocronológica (r = -0.41, P < 0.01). La Oscilación Decadal del Pacífico y la Oscilación Multidecadal del Atlántico, no mostraron significancia. Conclusiones: En este estudio, desarrollamos una función de respuesta climática y reconstruimos variables climáticas estacionales (precipitación, temperatura máxima) de importancia para desarrollar estrategias de manejo para la conservación de T. mucronatum en esta cuenca, e implementar acciones de mitigación para la presencia de eventos climáticos extremos que se pueden presentar en los próximos años.

Introduction: Dendroclimatic reconstructions in water-yield basins lacking hydroclimatic data, such as the Rio Sabinas is important to analyze its interannual and multiannual climatic variability. One of the species useful for this purpose is the Montezuma baldcypress (Taxodium mucronatum Ten.), a long-lived species with well-defined annual rings, present along the riparian zone of the Rio Sabinas that constitutes a "proxy" of interannual and multiannual climate variability. Objective: Develop a seasonal precipitation and maximum temperature reconstructions, and to analyze the influence of global circulatory modes on the species annual radial increase. Methods: Increment cores of the Montezuma baldcypress specimens were dated through dendrochronological techniques to produce a ring-width series. Climate gridded data from two databases were used to develop a response function analysis for climate reconstruction purposes. Results: A ring-width chronology extending from 1808 to 2018 (211 years) was developed and used to develop a seasonal April-June precipitation and a mean June-July maximum temperature reconstruction. The driest period detected on the rainfall reconstruction occurred from 1815 to 1818 with 27.4 mm and a maximum temperature of 41.2 °C; while the wettest year was 1828 with 393.72 mm. The ring-width chronology was correlated with the Standardized Precipitation Evaporation Index (SPEI) and the Palmer Drought Severity Index (PDSI), and with indices of atmospheric phenomena such as El Niño Southern Oscillation (ENSO), through the Southern Oscillation Index (SOI) and the Multivariate Index (MEI); Pacific Decadal Oscillation (PDO), and the Atlantic Multidecadal Oscillation (AMO). The relationship between the ring-width series and drought indices (SPEI, PDSI) was significant in June (r = 0.52, P < 0.01), and June-August (r = 0.38, P < 0.05) for the SPEI and reconstructed PDSI, respectively. It was found a significant association between the ring-width chronology and the reconstructed November-February SOI (r = -0.41, P < 0.01). The Pacific Decadal Oscillation and the Atlantic Multidecadal Oscillation were not significant. Conclusions: On this study, we developed a climatic response function and reconstructed seasonal climatic variables (precipitation, maximum temperature) of importance to develop management strategies for conservation of the Montezuma bald cypress on this basin, and to implement mitigation actions for the presence of extreme climatic events that may occur in coming years.

The increase of photosynthetic carbon assimilation as a mechanism of adaptation to low temperature in Lotus japonicus.

Low temperature is one of the most important factors affecting plant growth, it causes an stress that directly alters the photosynthetic process and leads to photoinhibition when severe enough. In order to address the photosynthetic acclimation response of Lotus japonicus to cold stress, two ecotypes with contrasting tolerance (MG-1 and MG-20) were studied. Their chloroplast responses were addressed after 7 days under low temperature through different strategies. Proteomic analysis showed changes in photosynthetic and carbon metabolism proteins due to stress, but differentially between ecotypes. In the sensitive MG-1 ecotype acclimation seems to be related to energy dissipation in photosystems, while an increase in photosynthetic carbon assimilation as an electron sink, seems to be preponderant in the tolerant MG-20 ecotype. Chloroplast ROS generation was higher under low temperature conditions only in the MG-1 ecotype. These data are consistent with alterations in the thylakoid membranes in the sensitive ecotype. However, the accumulation of starch granules observed in the tolerant MG-20 ecotype indicates the maintenance of sugar metabolism under cold conditions. Altogether, our data suggest that different acclimation strategies and contrasting chloroplast redox imbalance could account for the differential cold stress response of both L. japonicus ecotypes.

Impacto do tempo de isquemia na análise de expressão gênica global em tecidos criopreservados / Impact of cold ischemia on global gene expression in cryopreserved tissues

O perfil de expressão gênica tem passado do cenário da pesquisa básica para a prática clínica, sendo cada vez mais utilizado como ferramenta na classificação de subtipos moleculares do câncer. No entanto, deve-se ter cautela ao interpretar as assinaturas gênicas, uma vez que os métodos de manuseio e preservação da amostra podem afetar a expressão gênica. "Isquemia fria", quando aplicada à coleta e preservação de tecidos para pesquisa, refere-se ao período transcorrido desde a retirada do órgão do corpo e coleta da amostra, até o momento do seu congelamento em nitrogênio líquido. O objetivo geral deste trabalho foi avaliar o impacto do tempo de isquemia fria na expressão gênica global pela técnica de microarray em um modelo animal. Avaliamos 3 órgãos (pulmão, fígado e rim) de 52 camundongos (Mus musculus C57Bl/6), gerando 312 tecidos submetidos a diferentes tempos de isquemia (zero ou referência, 15, 30, 45 e 60 minutos). A expressão gênica global foi avaliada na plataforma SurePrint G3 Mouse GE 8x60K Microarray, que cobre o genoma completo do camundongo. Como resultado deste trabalho, os RNA totais extraídos tiveram alta qualidade (RIN médio de 9,4) e observamos alterações em genes que podem ser atribuídas ao processo isquêmico per se (p<0.05 e fold-change |2|). Alguns desses genes são conhecidamente relacionados ao câncer: fatores de transcrição (Fos, Hif3A), oncogenes (Ret, Srsf3), supressores tumorais (Btg1, Hnf1a), genes envolvidos no reparo do DNA, diferenciação e atividades de quinase. Esses genes devem ser olhados com cautela nas assinaturas genômicas para um desempenho analítico mais confiável. Foram encontradas variações de expressão gênica relacionadas a processos de controle de íons intracelulares e controle do pH. Evidenciou-se a importância da criopreservação imediata do tecido, ou, pelo menos, o mais rápido possível após a coleta, visando minimizar os efeitos de variação da expressão gênica decorrentes da isquemia (AU)

Gene expression profile has been moved from basic research to clinical practice, and it is increasingly being used as a tool in the classification of molecular subtypes in cancer. However, caution should be exercised when interpreting gene signatures, as sample handling and preservation methods may affect gene expression. "Cold ischemia", when applied to tissue collection and preservation for research, refers to the period from organ removal from the body and sample collection until it is frozen in liquid nitrogen. The general objective of this work was to evaluate the impact of cold ischemia time on global gene expression by microarray technique in an animal model. We evaluated 3 organs (lung, liver and kidney) from 52 mice (Mus musculus C57Bl / 6), generating 312 tissues submitted to different ischemia times (zero or reference, 15, 30, 45 and 60 minutes). Global gene expression was evaluated on the SurePrint G3 Mouse GE 8x60K Microarray platform that covers the complete mouse genome. As a result of this work, the extracted total RNAs had high quality (mean RIN of 9.4) and we evidenced changes in genes that can be attributed to the ischemic process per se (p <0.05 and fold-change | 2 |). Some of these genes are known to be related to cancer: transcription factors (Fos, Hif3A), oncogenes (Ret, Srsf3), tumor suppressors (Btg1, Hnf1a), genes involved in DNA repair, differentiation and kinase activities. These genes should be viewed with caution in genomic signatures for more reliable analytical performance. Gene expression variations related to intracellular ion control and pH control processes were observed. The importance of immediate tissue cryopreservation, or at least as soon as possible after collection, was evidenced in order to minimize the effects of gene expression variation resulting from ischemia (AU)

Crioablação: tratamento minimamente invasivo para tumores renais / Cryoablation: minimally invasive treatment for renal tumors

Atualmente, cerca de 60% dos tumores são diagnosticados por meio da ultra-sonografia ou da tomografia.As opções de tratamento padrão para os tumores renais menores do que 4 cm são a nefrectomia radical e parcial.Várias fontes de energia têm sido testadas de forma experimental para destruir tumores renais pequenos (criocirurgia, radiofreqüência, ultrasonografia de alta intensidade e outras) associadas a técnicas menos invasivas (percutânea ou laparoscópica).A cirurgia crioablativa oferece acesso minimamente invasivo no tratamento da maioria dos tumores renais pequenos (menores que 4 cm), minimizando o risco e morbidade da nefrectomia parcial aberta ou laparoscópica. A presença da ultra-sonografia no intra-operatório é essencial para o sucesso da crioablação.Alguns estudos com acompanhamento de três anos após crioablação de tumores renais demonstraram resultados com controle local da lesão de 85-95%.