Genotypic tolerance to metals as indicated by ethylene production

Water, Air, & Soil Pollution - To grow plants in high-metal environments, we need to be able to identify genotypes resistant to metal toxicity. The amount of ethylene evolved by plants may be...     

Dual probe heat pulse technique for measuring soil water content and sunflower water uptake

Soil water content is the most sought-after soil physical parameter. Recent experiments have shown that dual probe heat pulse (DPHP) sensors can be used to determine volumetric water content of soil without roots. Little work has been done to document the performance of DPHP sensors in the presence of roots, and no work has been done with a taprooted plant. Thus, the objective of this experiment was to determine the accuracy of DPHP sensors in measuring volumetric water content (θ_v) and changes in volumetric soil water content (Δθ_v) in soil with a branched taproot system. Another objective was to determine plant water use. A sunflower plant (Helianthus annuus L. ‘Hysun 354') was grown in a column (0.20 m in diameter and height) with Haynie very fine sandy loam (coarse-silty, mixed, calcareous, mesic Mollic Udifluvents; FAO-Eutric Fluvisols) containing 11 DPHP sensors. Results from the sensors were compared with those from the gravimetric method. Discrepancies between measurements of soil volumetric water content and changes of soil volumetric water by the DPHP and gravimetric methods were small (within 0.018 and 0.01 m³ m⁻³, respectively). The sunflower had a small amount of nocturnal transpiration, and roots took up water at a higher rate near the surface of the soil than at deeper depths. The results showed that the DPHP technique can monitor volumetric soil water content in the presence of a taproot.     

The acute phase reaction detected in dogs by concanavalin A binding

Using a kinetic turbidimetric assay based on the binding of serum glycoprotein to concanavalin A the acute phase reaction has been detected in dogs. Raised levels of glycoprotein were found in dogs which had undergone surgery, had been treated with bacterial endotoxin and had various inflammatory conditions.     

Plasma Antimullerian Hormone as a Predictor of Ovarian Antral Follicular Population in Bos indicus (Nelore) and Bos taurus (Holstein) Heifers

In Bos taurus cattle, antimullerian hormone (AMH) has been demonstrated to have a high degree of correlation with ovarian antral follicle count and the number of healthy follicles and oocytes. To document the correlation between the plasma concentration of AMH and follicular number in Bos indicus and Bos taurus heifers, Nelore (Bos indicus, n = 16) and Holstein heifers (Bos taurus, n = 16) had their ovarian follicular waves synchronized. After synchronization, ovarian antral follicular population (AFP) was evaluated three times at 60‐day (d) intervals (T‐120 d, 120 days before plasma AMH determination; T‐60 d, 60 days before; and T0, at the time of plasma AMH determination). The plasma AMH concentration was positively correlated with the number of ovarian follicles on the day of the follicular wave emergence in Bos indicus (Nelore) and Bos taurus (Holstein) heifers at each evaluation time (p < 0.05). The AFP was higher in Bos indicus (Nelore) than in Bos taurus (Holstein) heifers (p < 0.05). Similarly, the AMH concentration was higher in Bos indicus (Nelore) than in Bos taurus (Holstein) heifers (p < 0.0001). When heifers were classified as to present high or low AFP according to the mean of the AFP within each genetic group, high‐AFP heifers presented a greater (p < 0.0001) AMH concentration than low‐AFP heifers, regardless of the genetic group. In conclusion, the AFP is positively correlated with plasma AMH concentration in both Bos indicus (Nelore) and Bos taurus (Holstein) heifers. Furthermore, Bos indicus (Nelore) heifers presented both greater plasma AMH concentrations and AFP than Bos taurus (Holstein) heifers.     

Comparison of Conventional Freezing and Vitrification with Dimethylformamide and Ethylene Glycol for Cryopreservation of Ovine Embryos

The aim of this work was to evaluate the efficiency of the cryoprotectants dimethylformamide and ethylene glycol for cryopreservation of ovine embryos using vitrification and conventional freezing. The recovered embryos were distributed randomly in three treatment groups: Gr. 1: conventional freezing (n = 44), Gr. 2: vitrification with ethylene glycol (n = 39) and Gr. 3: vitrification with dimethylformamide (n = 38). Quality of fresh embryos in control group as well as of frozen and vitrified embryos was examined by three methodologies: staining with propidium iodide and Hoechst 33258 and evaluation under fluorescent microscopy, evaluation of re‐expansion and hatching rates after culture, and determination of apoptotic index with TUNEL technique. It was established that re‐expansion rate in all treatment groups was similar. In the same time, hatching rates were higher in Gr. 1 (40.5%) and Gr. 2 (35.3%) in comparison with Gr. 3 (15.5%, p < 0.05). The number of dead cells in vitrified embryos of Gr. 2 and Gr. 3 was higher (42.6 ± 26.2 and 63.2 ± 34.65, respectively) in comparison with Gr. 1 (conventional freezing, 10.1 ± 8.5, p < 0.05). Embryos vitrified with dimethylformamide included the same quality of apoptotic cells that Gr. 1 (conventional freezing) and fresh embryos. In conclusion, the dimethylformamide and ethylene glycol used as cryoprotectant to vitrify ovine embryos, in the concentrations and exposition time tested in this work, were not as efficient as the conventional freezing for cryopreservation of ovine embryos Thus, the conventional freezing with ethylene glycol was the most efficient method to cryopreserve ovine embryos in comparison with vitrification.     

A Legume Ethylene-Insensitive Mutant Hyperinfected by Its Rhizobial Symbiont

Development of the Rhizobium-legume symbiosis is controlled by the host plant, although the underlying mechanisms have remained obscure. A mutant in the annual legume Medicago truncatula exhibits an increase of more than an order of magnitude in the number of persistent rhizobial infections. Physiological and genetic analyses indicate that this same mutation confers insensitivity to the plant hormone ethylene for multiple aspects of plant development, including nodulation. These data support the hypothesis that ethylene is a component of the signaling pathway controlling rhizobial infection of legumes.     

Gravity Waves in Jupiter's Thermosphere

The Atmosphere Structure Instrument on the Galileo probe detected wavelike temperature fluctuations superimposed on a 700-kelvin temperature increase in Jupiter's thermosphere. These fluctuations are consistent with gravity waves that are viscously damped in the thermosphere. Moreover, heating by these waves can explain the temperature increase measured by the probe. This heating mechanism should be applicable to the thermospheres of the other giant planets and may help solve the long-standing question of the source of their high thermospheric temperatures.