Method for simultaneous study of peristaltic and pendular movements of isolated rabbit ileum]

A method is described for studying simultaneously the peristalsis and the pendular movements in the isolated pieces of rabbit ileum. At the same time, using this method it is possible to analyse the actions of drugs on the mechanisms which ensure the pendular movements and the propulsive activity, as well as their relationship. The method is relatively simple and only classical and commercially available equipments are needed. With this method the records and the volume of fluid expelled are suitable for statistical analysis.     

DNA methylation of embryogenic carrot cell cultures and its variations as caused by mutation,differentiation, hormones and hypomethylating drugs

Summary The level of auxin - both natural and synthetic — in the medium has a strong effect on the level of 5-methyl-cytosine in the DNA of carrot cells in culture. This level may vary from approximately 15% to 70% of total cytosine without apparent effects on growth rate and cell morphology. No effect was seen with cytokinin. During somatic embryogenesis, in the absence of hormones, variations were seen in the level of methylation according to a characteristic pattern. If hypomethylation is induced with drugs such as azacytidine, ethionine or ethoxy-carbonyl-pyrimidine, embryogenesis is immediately blocked. A mutant was isolated which is resistant to the action of hypomethylating drugs. It shows variations in the methylation pattern and variations in indole-acetic acid metabolism. In addition its regeneration is often associated with the production of tumors.Deceased     

Microclimatic indexes and limits of safe exposure in work activity at risk of thermal stress

The working time in work places thermically uncomfortable must be limited in order to prevent the risk of thermal stress. In a previous study we have demonstrated that the best method for calculation of the safe exposure times is based on the required sweat rate index. In the present work we verified in different work places termically uncomfortable, grouped for equivalent values of WBGT index, the variability of the safe exposure times calculated by means of a method just now mentioned for various levels of energetic expenditure. The results point out the possibility of a mathematical relation between energetic expenditure, WBGT index and mean of safe exposure times.     

Isolation and developmental characterization of temperature-sensitive carrot cell variants

Summary Carrot cell lines multiply indefinitely in the presence of the auxin 2,4-D. If auxin is removed, the cells regenerate plantlets in a process that closely resembles embryogenesis in vivo. We isolated a temperature-sensitive variant, ts 2, which is unable to regenerate at 31 °C (non-permissive temperature), but does form embryos and plants at 24 °C (permissive temperature). The temperature treatment had no effect on fully differentiated ts 2 plantlets. In other variants (ts 5 and ts 11) cell proliferation was inhibited at the restrictive temperature. These lines were leaky with respect to the inhibition of embryogenesis at 31 °C.Abbreviations EMS ethylmethanesulfonate - EU embryogenic unit (see Materials and methods) - ts temperature-sensitive - 2,4-D 2,4-dichlorophenoxyacetic acid     

Decrease in environmental pollution and changes in biological indicators in occupational exposure to lead

The Authors examine the variations of the levels of PbB and EPP in 39 workers at known lead exposure and evaluate the capacity of these parameters to follow the measured decreases of the environmental pollution. They conclude that the variations of the mean PbB values are well related to environmental pollution and that the diagram on the probability paper of median values and their corresponding standard deviations allows to calculate the number of exposed workers with biological values above a fixed limit.     

Gastric evacuation in endangered Russian sturgeon (Acipenser gueldenstaedtii): Effects of body and meal sizes

This study aimed to parameterize the effects of body and meal sizes on the gastric evacuation (GE) of farmed Russian sturgeon (Acipenser gueldenstaedtii) fed on live food (whiting fish) or commercial pellets. The radiography technique was used to monitor the evacuation of food from the stomach into the intestine at postprandial time. Acipenser gueldenstaedtii of different body sizes (total length ranged 82–105 cm) were fed on meal sizes ranged from 23 to 72 g composed of either live food or commercial pellets (had a 20% of BaSO₄ as a radiopaque material). The square root model was found to adequality describe the process of GE in A. gueldenstaedtii independently of meal type and size. The effects of fish size on GER was described by simple power model and can be summarized by , where ρ_L was 0.000053 for live food and 0.000062 for commercial pellets (estimated from combined GE data), S_t is stomach contents (g), L is fish total length (cm) and t is time (h). The results of this study will provide a useful tool to estimate the stomach fullness of A. gueldenstaedtii at postprandial time t. Such information should assess the feeding strategy to minimize feed wastage and optimize the fish growth.