Regulation of PGC-1α of the Mitochondrial Energy Metabolism Pathway in the Gills of Indian Medaka (Oryzias dancena) under Hypothermal Stress.

Ectothermic fish exposure to hypothermal stress requires adjusting their metabolic molecular machinery, which was investigated using Indian medaka (Oryzias dancena; 10 weeks old, 2.5 ± 0.5 cm) cultured in fresh water (FW) and seawater (SW; 35‱) at room temperature (28 ± 1 °C). The fish were fed twice a day, once in the morning and once in the evening, and the photoperiod was 12 h:12 h light: dark. In this study, we applied two hypothermal treatments to reveal the mechanisms of energy metabolism via pgc-1α regulation in the gills of Indian medaka; cold-stress (18 °C) and cold-tolerance (extreme cold; 15 °C). The branchial ATP content was significantly higher in the cold-stress group, but not in the cold-tolerance group. In FW- and SW-acclimated medaka, the expression of genes related to mitochondrial energy metabolism, including pgc-1α, prc, Nrf2, tfam, and nd5, was analyzed to illustrate differential responses of mitochondrial energy metabolism to cold-stress and cold-tolerance environments. When exposed to cold-stress, the relative mRNA expression of pgc-1α, prc, and Nrf2 increased from 2 h, whereas that of tfam and nd5 increased significantly from 168 h. When exposed to a cold-tolerant environment, prc was significantly upregulated at 2 h post-cooling in the FW and SW groups, and pgc-1α was significantly upregulated at 2 and 12 h post-cooling in the FW group, while tfam and nd5 were downregulated in both FW and SW fish. Hierarchical clustering revealed gene interactions in the cold-stress group, which promoted diverse mitochondrial energy adaptations, causing an increase in ATP production. However, the cold-tolerant group demonstrated limitations in enhancing ATP levels through mitochondrial regulation via the PGC-1α energy metabolism pathway. These findings suggest that ectothermic fish may develop varying degrees of thermal tolerance over time in response to climate change. This study provides insights into the complex ways in which fish adjust their metabolism when exposed to cold stress, contributing to our knowledge of how they adapt.

Simulating Temperature in a Soil Incubation Experiment.

The study of warming impact on soils requires a realistic and accurate representation of temperature. In laboratory incubation studies, a widely adopted method has been to render constant temperatures in multiple chambers, and via comparisons of soil responses between low- and high-temperature chambers, to derive the warming impact on soil changes. However, this commonly used method failed to imitate both the magnitude and amplitude of actual temperatures as observed in field conditions, thus potentially undermining the validity of such studies. With sophisticated environmental chambers becoming increasingly available, it is imperative to examine alternative methods of temperature control for soil incubation research. This protocol will introduce a state-of-the-art environmental chamber and demonstrate both conventional and new methods of temperature control to improve the experimental design of soil incubation. The protocol mainly comprises four steps: temperature monitoring and programming, soil collection, laboratory incubation, and warming effect comparison. One example will be presented to demonstrate different methods of temperature control and the resultant contrasting warming scenarios; that is, a constant temperature design referred to as stepwise warming (SW) and simulated in situ temperature design as gradual warming (GW), as well as their effects on soil respiration, microbial biomass, and extracellular enzyme activities. In addition, we present a strategy to diversify temperature change scenarios to meet specific climate change research needs (e.g., extreme heat). The temperature control protocol and the recommended well-tailored and diversified temperature change scenarios will assist researchers in establishing reliable and realistic soil incubation experiments in the laboratory.

Validation of 2d ultrasound and volume estimation formulae for volume assessment of kidneys and spleens: an in-vitro study / alidación de la fórmula de estimación de volumen y ultrasonido 2D para la evaluación del volumen de los riñones y el bazo: un estudio in vitro

The accuracy of internal organ volume estimation done with ultrasound (US) was found to be multifactorial. Hence, we aimed to describe and validate the volume assessment of ultrasound and standard volume estimation formulae for different shaped intra-abdominal organs using spleens and kidneys.Dissected cadaveric kidneys (n=25) and spleens (n=29) were scanned to obtain linear measurements and ultrasound auto-generated volumes (USV). Linear measurements were used to calculate the volumes manually with ellipsoid, prolate, and Lambert volume estimating formulae. The actual volumes (AV) of organs were obtained by the water displacement method. Volume assessment accuracy of USV and different formulae were compared by comparing bias, precision and Bland-Altman plot analysis. The US linear and volume measurement procedure was reliable with high inter and intra-observer agreements (linear: Chronbach's α=0.983 to 0.934; volumes: Chronbach's α=0.989). USV estimates were accurate with a high correlation to AV and low estimation bias (-5.9%). Also, prolate (bias=-0.75%) and ellipsoid formulae (bias=-3.75%) were reliable with a negligible bias in estimated volumes. Contrary, the Lambert formula was unreliable due to a high bias (41.6%). For all evaluated methods, the estimation error found to be related to the organ size (T=3.483; p=0.001), mainly when the assessed organ is larger than 50 ml. Also, the shape related estimation error found to be related to the volume estimation formula used.This study has validated the USV for kidney and splenic volume assessments while describing volume-calculating formula employed, organ size and shape as significant contributors for volume estimation accuracy.

Se encontró que la precisión de la estimación del volumen de órganos internos realizada con ultrasonido (US) es multifactorial. El objetivo fue describir y validar la evaluación de volumen mediante ecografía y las fórmulas estándar de estimación de volumen para órganos intraabdominales de diferentes formas utilizando bazos y riñones.Se evaluaron riñones cadavéricos disecados (n = 25) y bazos (n = 29) para obtener medidas lineales y volúmenes autogenerados por ultrasonido (USV). Se utilizaron medidas lineales para calcular los volúmenes manualmente con fórmulas de estimación de volumen elipsoide, prolate y Lambert. Los volúmenes reales (AV) de los órganos se obtuvieron mediante el método de desplazamiento de agua. Se comparó la precisión de la evaluación del volumen de USV y diferentes fórmulas comparando el sesgo, la precisión y el análisis de la gráfica de Bland-Altman. El procedimiento de medición lineal y de volumen mediante US fue confiable con alta concordancia inter e intraobservadores (lineal: α de Chronbach = 0,983 a 0,934; volúmenes: α de Chronbach = 0,989). Las estimaciones de USV fueron precisas con una alta correlación con AV y un bajo sesgo de estimación (-5,9%). Además, las fórmulas prolate (sesgo= -0,75%) y elipsoide (sesgo = -3,75%) fueron confiables con un sesgo insignificante en los volúmenes estimados. Por el contrario, la fórmula de Lambert no fue confiable debido a un alto sesgo (41,6%). Para todos los métodos evaluados, se encontró que el error de estimación estaba relacionado con el tamaño del órgano (T = 3.483; p = 0.001), principalmente cuando el órgano evaluado es mayor de 50 ml. Además, se encontró que el error de estimación de forma está relacionado con la fórmula de estimación de volumen utilizada.Este estudio ha validado el USV para evaluaciones de volumen renal y esplénico al mismo tiempo que describe la fórmula de cálculo de volumen empleada, el tamaño y la forma de los órganos como contribuyentes significativos de la precisión de la estimación de volumen.

Effects of nitrogen fertilization and bioenergy crop species on central tendency and spatial heterogeneity of soil glycosidase activities.

Extracellular glycosidases in soil, produced by microorganisms, act as major agents for decomposing labile soil organic carbon (e.g., cellulose). Soil extracellular glycosidases are significantly affected by nitrogen (N) fertilization but fertilization effects on spatial distributions of soil glycosidases have not been well addressed. Whether the effects of N fertilization vary with bioenergy crop species also remains unclear. Based on a 3-year fertilization experiment in Middle Tennessee, USA, a total of 288 soil samples in topsoil (0-15 cm) were collected from two 15 m2 plots under three fertilization treatments in switchgrass (SG: Panicum virgatum L.) and gamagrass (GG: Tripsacum dactyloides L.) using a spatially explicit design. Four glycosidases, α-glucosidase (AG), ß-glucosidase (BG), ß-xylosidase (BX), cellobiohydrolase (CBH), and their sum associated with C acquisition (Cacq) were quantified. The three fertilization treatments were no N input (NN), low N input (LN: 84 kg N ha-1 year-1 in urea) and high N input (HN: 168 kg N ha-1 year-1 in urea). The descriptive and geostatistical approaches were used to evaluate their central tendency and spatial heterogeneity. Results showed significant interactive effects of N fertilization and crop type on BX such that LN and HN significantly enhanced BX by 14% and 44% in SG, respectively. The significant effect of crop type was identified and glycosidase activities were 15-39% higher in GG than those in SG except AG. Within-plot variances of glycosidases appeared higher in SG than GG but little differed with N fertilization due to large plot-plot variation. Spatial patterns were generally more evident in LN or HN plots than NN plots for BG in SG and CBH in GG. This study suggested that N fertilization elevated central tendency and spatial heterogeneity of glycosidase activities in surficial soil horizons and these effects however varied with crop and enzyme types. Future studies need to focus on specific enzyme in certain bioenergy cropland soil when N fertilization effect is evaluated.