Potencial dendroclimático del encino rojo, Quercus sideroxyla (Fagaceae) en México / Dendroclimatic potential of red oak, Quercus sideroxyla (Fagaceae) in Mexico

Resumen Introducción: Los estudios dendrocronológicos en México se han basado principalmente en las coníferas, mientras que las especies de madera dura han sido poco estudiadas. Este ha sido el caso del género Quercus, con una alta diversidad taxonómica en el país pero que no ha sido estudiado con fines dendrocronológicos, a pesar de los valores ecológicos y económicos de sus especies. Objetivo: En la presente investigación se determinó el potencial dendroclimático de Quercus sideroxyla en el noroeste de México, y su relación con variables climáticas como precipitación y temperatura. Métodos: La investigación se desarrolló en el estado de Durango en el ejido Chavarría Viejo en las coordenadas (23º43' N & 105º33' W), se recolectaron muestras de 5 a 7 cm en dos sitios bajo aprovechamiento forestal y se procesaron mediante técnicas dendrocronológicas convencionales. Resultados: Se desarrolló una cronología de ancho de anillo total, la cual se compuso por 30 muestras de 16 árboles para el período de 1917 a 2018 (101 años). Se obtuvieron valores de intercorrelación entre series de 0.43, de sensibilidad media de 0.36, relación señal-ruido de 3.53 y autocorrelación de primer orden (0.58). En cuanto a la relación clima-crecimiento, los valores de índice de ancho de anillo se correlacionaron con datos de la estación climática más cercana al sitio de estudio; donde la precipitación invierno-primavera (enero-mayo) fue la variable de mayor influencia en el crecimiento de la especie. Conclusiones: Con base en los parámetros dendrocronológicos se demuestra el alto potencial de la especie para ser empleada en estudios dendroclimáticos en la región, la respuesta de la especie a la precipitación es similar al de las coníferas con las que cohabita.

Abstract Introduction: Dendrochronological studies in Mexico have been mainly based on conifers, while hardwood species have been little studied. This has been the case of the genus Quercus, which has a high taxonomic diversity in the country but has not been previously studied for dendrochronological issues, despite the ecological and economic values of oak species. Objective: In the present investigation, the dendroclimatic potential of Quercus sideroxyla in Northwestern Mexico was determined, as well as its relationship with climatic variables such as precipitation and temperature. Methods: The research was carried out in the state of Durango, Chavarría Viejo with coordinates (23º43' N & -105º33' W). Samples of 5 cm to 7cm were collected in two sites under forest exploitation and processed by conventional dendrochronological techniques. Results: A chronology of total ring width was developed, which was composed of 30 samples from 16 trees for the period from 1917 to 2018 (101 years). Inter-series intercorrelation values of 0.43, mean sensitivity of 0.36, signal-to-noise ratio of 3.53 and first-order autocorrelation (0.58) were obtained. Regarding the climate-growth relationship, the ring width index values were correlated with data from the climatic station nearest to the study site, where winter-spring precipitation (January-May) was the variable with the greatest influence on the growth of the species. Conclusions: Based on the dendrochronological parameters, the high potential of the species that were used in dendroclimatic studies in the region has demonstrated that the response of the species to precipitation is similar to that of the conifers with which the Quercus sideroxyla shares its habitat with.

Can discrepancies between Fusarium graminearum trichothecene genotype and chemotype be explained by the influence of temperature in the relative production of 3-ADON and 15-ADON?

Wheat is one of the most important crops in Argentina and worldwide. One of the major diseases affecting the crop is the Fusarium Head Blight (FHB). It is an endemic disease caused mainly by Fusarium graminearum, the most common agent of FHB around the world. The infection is strongly influenced by environmental parameters and occurs mostly when there are favourable conditions of moisture and temperature during wheat anthesis or flowering. This destructive disease affects wheat, barley and other small grains and has the capability of destroying crops, causing great economic losses due to reduced grain quality, and the accumulation of significant levels of mycotoxins such as trichothecenes. The aim of this study was to evaluate the influence of temperature on mycotoxin biosynthesis, on three strains of F. graminearum of 15-ADON genotype and one of 3-ADON genotype, with different capacity of synthesizing DON, 3-ADON and 15-ADON. Trichothecene production of the strains at different temperatures (5, 10, 15, 20, 25, 30 and 35 °C) was evaluated after 7, 14, 21, 28 and 35 d of incubation. The optimum temperature to produce DON and 3-ADON was between 25 and 30 °C, but the maximum production of 15-ADON occurred at a lower temperature (10 °C) for all the strains. Conversely, the minimum production of DON and 3-ADON was recorded between 5 and 10 °C and of 15-ADON between 30 and 35 °C. A possible explanation for the similar accumulation of both acetyl derivatives by strains of different chemotype and genotypes could be that the acetyl derivatives biosynthesis is regulated by temperature.

Climatic influence on the growth pattern of Panthasaurus maleriensis from the Late Triassic of India deduced from paleohistology.

Metoposaurids are representatives of the extinct amphibian clade Temnospondyli, found on almost every continent exclusively in the Late Triassic deposits. Osteohistologically, it is one of the best-known temnospondyl groups, analyzed with a wide spectrum of methods, such as morphology, morphometry, bone histology or computed modelling. The least known member of Metoposauridae is Panthasaurus maleriensis from the Pranhita-Godavari basin in Central India, being geographically the most southern record of this family. For the first time the bone histology of this taxon was studied with a focus on the intraspecific variability of the histological framework and the relationship between the observed growth pattern and climatic and/or environmental conditions. The studied material includes thin-sections of five long bones, a rib, an ilium and an intercentrum belonging most likely to eight individuals ranging from different ontogenetic stages. All bones have a large medullary region with progressively increasing remodeling, surrounded by a lamellar-zonal tissue type. The primary cortex consists of parallel-fibered matrix showing various degrees of organization, less organized collagen fibers in the zones and higher organized in the annuli. Growth marks occur in the form of alternating zones and annuli in every bone except the ilium and the intercentrum. The vascularity becomes less dense towards the outermost cortex in all sampled limb bones. Towards the outermost cortex the zone thickness is decreasing, in contrast to the avascular annuli, that become thicker or are of the same thickness. The growth pattern of P. maleriensis is uniform and represents changes in ontogenetic development. Multiple resting lines are prominent in the outer annuli of the limb bones and the rib and they presumably indicate climatic and environmental influence on the growth pattern. Therefore, a prolonged phase of slowed-down growth occurred during the unfavorable phase, but a complete cessation of growth indicated by Lines of Arrested Growth (LAGs) is not recorded in the studied samples. Based on the histological framework we conclude that the climate had an impact on the growth pattern. As we do not see any LAGs in the Indian metoposaurid, we assume that the local climate was relatively mild in India during the Late Triassic. A similar prolonged phase of slowed down growth without the occurrence of LAGs was observed in Metoposaurus krasiejowensis from the Late Triassic of Krasiejów (Poland). This is in contrast to Moroccan metoposaurid Dutuitosaurus ouazzoui from the Late Triassic of Argana Basin, where LAGs are regularly deposited throughout ontogeny indicating most likely harsher climatic conditions.

Significance of geographical factors to the COVID-19 outbreak in India.

Recently, the large outbreak of COVID-19 cases all over the world has whacked India with about 30,000 confirmed cases within the first 3 months of transmission. The present study used long-term climatic records of air temperature (T), rainfall (R), actual evapotranspiration (AET), solar radiation (SR), specific humidity (SH), wind speed (WS) with topographic altitude (E) and population density (PD) at the regional level to investigate the spatial association with the number of COVID-19 infections (NI). Bivariate analysis failed to find any significant relation (except SR) with the number of infected cases within 36 provinces in India. Variable Importance of Projection (VIP) through Partial Least Square (PLS) technique signified higher importance of SR, T, R and AET. However, generalized additive model fitted with the log-transformed value of input variables and applying spline smoothening to PD and E, significantly found high accuracy of prediction (R 2 = 0.89), and thus well-explained complex heterogeneity among the association of regional parameters with COVID-19 cases in India. Our study suggests that comparatively hot and dry regions in lower altitude of the Indian territory are more prone to the infection by COVID-19 transmission.

Actividad de un "ensamblaje" de murciélagos en el norte de Brasil (Mammalia: Chiroptera) / Activity of a bat assemblage in northern Brazil (Mammalia: Chiroptera)

Resumen La Amazonía es uno de los ecosistemas tropicales más biodiversos del mundo, característica atribuida a la complejidad estructural que le brinda la geología y la gran riqueza de sus suelos. Los murciélagos constituyen uno de los taxones de la clase Mammalia mejor representados en esta región, aun así, existen claros vacíos de conocimiento, principalmente, respecto a su ecología, con lo cual, en el presente estudio se pretende evaluar la influencia que tienen factores ambientales, como la temporada climática, temperatura (máxima y mínima), humedad relativa y porcentaje de fase iluminada de la Luna, en los patrones de actividad (riqueza, abundancia y gremios tróficos) de un ensamblaje de murciélagos en la Amazonía central brasilera. El estudio fue llevado a cabo en dos municipios del estado de Rondônia, empleando ocho redes de niebla, durante 62 noches de muestreo, abarcando las temporadas lluviosa y seca. En total fueron capturados 2 499 individuos de 58 especies, la familia mejor representada fueron los Phyllostomidae, mientras que la especie que registró la mayor frecuencia de capturas fue Carollia perspicillata (N = 859), seguida de C. brevicauda (N = 209). No se presentaron diferencias entre la estructura del ensamblaje considerando la temporada climática (lluviosa-seca), sin embargo, durante la temporada seca se registró un mayor número de especies e individuos (57 especies, N = 1 597), que en la temporada lluviosa (44 especies, N = 902). La abundancia de murciélagos estuvo influenciada principalmente, por la humedad relativa (P = 0.00) y la temperatura (mínima) (P = 0.04), mientras que, las especies respondieron diferencialmente al porcentaje de fase iluminada de la luna. En estos resultados se evidencia la influencia de factores ambientales en los patrones de actividad del ensamblaje de murciélagos en la Amazonía, en donde la ecología de las especies determina el tipo de influencia. Sin embargo, se requieren de estudios llevados a cabo por períodos más prolongados, para determinar si estos patrones se mantienen a lo largo del tiempo.(AU)

Abstract The Amazon is considered one of the most biodiverse tropical ecosystems in the world thanks to the structural complexity that geology offers and the great biological richness of its soils. Further, concerning the Mammalian class, bats are one of the best represented taxa in the region, nevertheless their ecology is poorly studied. This study, evaluates the influence of environmental factors such as the climate season, temperature (maximum and minimum), relative humidity and lunar phase on the activity patterns (abundance and trophic guilds) of an assemblage of bats in the Brazilian central Amazon. This study was carry out in two municipalities of the state of Rondônia using eight mist nets during 62 nights of sampling, covering humid and dry periods. A total of 2 499 individuals of 58 species were captured. The best represented family was the Phyllostomidae, while the species that recorded the highest frequency of captures was Carollia perspicillata (N = 859), followed by C. brevicauda(N = 209). There were no significant differences between the structure of the assemblage considering the climatic season (rain-dry). However, during the dry season a greater number of species and individuals was recorded (57 species, N = 1 597) than in the rainy season (44 species, N = 902). The abundance of bats was influenced mainly by relative humidity (P = 0.00) and minimal temperature (P = 0.04), while the species responded differentially to the lunar phase. These results show the influence of environmental factors on the activity patterns of a bat assemblage in the Amazon, where the factors that influence them depends on the ecology of each species. However, studies carried out for longer periods are required to determine if these patterns are maintained over time.(AU)

Influência da temperatura e umidade nas atividades de voo de operárias de Melipona eburnea (Apidae, Meliponina) / Influence of temperature and humidity in the flight activities of worker Melipona eburnea (Apidae, Meliponina) / Influencia de la temperatura y humedad en las actividades de vuelo de obreras de Melipona eburnea (Apidae, Meliponina)

As abelhas da espécie Melipona eburnea forrageiam em busca de recursos como néctar, pólen, resinas, barro e água, além de transportar o lixo para fora da colônia. A atividade de voo das abelhas pode ser influenciada pela oferta de recursos florais, condições internas do ninho, temperatura, umidade relativa, luminosidade, precipitação e velocidade do vento. No entanto, a temperatura influencia diretamente as atividades de forrageamento das abelhas. O presente estudo foi realizado em Rio Branco-Acre, em um meliponário contendo 14 colmeias de M. eburnea, distribuídas em uma área de 600m2, entre dezembro de 2015 e maio de 2016, abrangendo o período chuvoso, com altas temperaturas, e o de seca, em que ocorrem as friagens. As atividades de voo para forrageamento da espécie M. eburnea ocorreram de forma intensa, durante o dia todo, quando as temperaturas estiveram próximas de 20 °C, com variações de, no máximo, 1,9 °C e umidade relativa do ar em torno de 90%. M. eburnea inicia as atividades de forrageio nas primeiras horas da manhã, coletando néctar, água, pólen, resina e barro, com pico de coleta de pólen entre as 05h e 07h; resina e barro entre 09h e 11h e néctar/água entre as 16h e 17h30min. As atividades de voo de M. eburnea são influenciadas quando a temperatura se encontra abaixo de 20 °C ou acima de 30 °C, e a umidade relativa superior a 90%.(AU)

The bees in the Melipona eburnea species forage in search of resources such as nectar, pollen, resins, clay and water, in addition to transporting the garbage out of the colony. The flight activity of the bees can be influenced by the supply of floral resources, internal conditions of the hive, temperature, relative humidity, luminosity, precipitation and wind speed. However, temperature has a direct influence on the foraging activities of bees. This study was carried out in the city of Rio Branco, Acre, in a meliponary containing 14 M. eburnea hives distributed in a 600m2 area between December 2015 and May 2016, including the rainy season with high temperatures and the dry season, when cold chills take place. The foraging activities of the M. eburnea species occurred intensively throughout the day, when temperatures were close to 20 °C, with variations of a maximum of 1.9 °C, and air relative humidity of approximately 90%. M. eburnea initiates the foraging activities in the early hours of the morning, collecting nectar, water, pollen, resin and clay, with a peak of pollen collection between 5 a.m. and 7 a.m.; resin and clay between 9 a.m. and 11 a.m., and nectar/water between 4 p.m. and 5:30 p.m. The flight activities of M. eburnea are influenced when temperature is below 20 °C or above 30 °C, and the relative humidity is greater than 90%.(AU)

Las abejas de la especie Melipona eburnea forrajean en busca de recursos como néctar, polen, resinas, barro y agua, además de transportar la basura hacia fuera de la colonia. La actividad de vuelo de las abejas puede verse influenciada por la oferta de recursos florales, condiciones internas del nido, temperatura, humedad relativa, luminosidad, precipitación y velocidad del viento. Sin embargo, la temperatura influye directamente en las actividades de forraje de las abejas. El presente estudio ha sido realizado en Rio Branco-Acre, en un meliponario que contenía 14 colmenas de M. eburnea, distribuidas en un área de 600m2, entre diciembre de 2015 y mayo de 2016, abarcando el período lluvioso con altas temperaturas y el de sequía, en que se producen los enfriamientos. Las actividades de vuelo para forraje de la especie M. eburnea ocurrieron de forma intensa durante todo el día, cuando las temperaturas estuvieron cerca de los 20 °C, con variaciones de, como máximo, 1,9 °C y humedad relativa del aire alrededor del 90%. M. eburnea inicia las actividades de forraje en las primeras horas de la mañana, recogiendo néctar, agua, polen, resina y barro, con pico de recolección de polen entre las 05 h y 07 h; resina y barro entre las 09 h y las 11 h y néctar / agua entre las 16 h y las 17.30 h. Las actividades de vuelo de M. eburnea se influencian cuando la temperatura se encuentra por debajo de 20 °C o superior a 30 °C y la humedad relativa superior al 90%.(AU)

Study of the Accumulation of Toxic and Essential Ultra-Trace Elements in Fruits of Sorbus domestica L.

In the present work, the accumulation of selected toxic and essential ultra-trace elements in fruits of service tree (Sorbus domestica L.) were determined depending on harvest time. Samples were collected from the same sampling area in two different years and within one year in September and October (maturity state). Harvesting the fruits in the same area excludes the influence of metals taken up via roots, thus the impact of airborne contamination by heavy metal translocation can be studied. All samples were dried and digested using an acidic microwave assisted digestion system prior to quantification by inductively coupled plasma-sector field mass spectrometry (ICP-SFMS). The elements chosen were Arsenic and Cadmium as well as Lithium, Molybdenum, and Selenium. The Arsenic content rose with maturity in mesocarp. Cadmium found in the mesocarp was unaffected by ripeness. For Selenium and Molybdenum, no statistically significant effect of ripeness could be found on their content in mesocarp. Lithium could not be detected in the majority of fruit samples. Differences between the metal concentrations based on the year of harvest were found for Arsenic, Molybdenum, and Selenium, depending on precipitation. The drier the season, the more Arsenic was accumulated. For Molybdenum and Selenium, the opposite effect was observed.