Supercritical CO2 extraction of velutinol A from Mandevilla velutina (Apocynaceae) cultured cells and MALDI-TOF MS analysis

MALDI-TOF MS analysis of supercritical CO₂ extracted samples obtained from Mandevilla velutina cell cultures allowed the detection of the anti-bradykinin pregnanic steroid, velutinol A, using low amount of sample (1 g lyophilized cells), with minimum analyte isolation.     

A Simple Method for Fixing, Dehydrating and Embedding Pollen Tubes Cultivated in Vitro for Optical and Transmission Electron Microscopy

A simple method to cultivate pollen tubes in a gelatin medium is presented. After the growth of the pollen tubes in the culture medium, they are fixed, dehydrated, and embedded in resin for ultramicrotomy. The method is easy and does not require the purchase of special materials beyond those needed for the usual techniques for studying biological specimens under transmission electron microscopy.     

Solar radiation exposure accelerates decomposition and biotic activity in surface litter but not soil in a semiarid woodland ecosystem in Patagonia,Argentina

Plant and Soil - The intensity of extreme rainfall events is increasing in many regions of the world, with important impacts on community dynamics and ecosystem functioning especially in...     

Induction of size reduction in Escherichia coli by near-ultraviolet light

Escherichia coli AB1157 cells, growing exponentially at 37 degrees C in 63B1 medium (supplemented with glucose and casamino acids) with a doubling time of 50 min, were subjected to continuous illumination with 366-nm light at a fluence of 1.5 kJ . m-2 X min-1. Under these conditions, the growth rate decreased and after 1 h of illumination, a new stable exponential mode was reached with a doubling-time of 73 min. This reduction in growth rate occurred without any change in the rate of cell division for two generations after the beginning of illumination. Survival was unaffected, implying that cell size must have decreased. This was confirmed with size distribution curves of control and illuminated cells obtained with a Coulter counter. Furthermore electron micrographs of negatively stained cells indicated that illumination results in a 30-40% decrease in cell length, the diameter increasing by 8%. Hence 366-nm light uncouples growth and division rates. Illumination under the above conditions triggered the accumulation in vivo of 8-13-linked tRNA. The stationary level of the 8-13 link, 80% of the maximal level, was reached precisely when the growth rate reached its new stable value. Furthermore, no reduction in growth rate occurred in a nuv- cell lacking 4-thiouridine in its tRNAs. Hence we conclude that the 366-nm photons trigger partial tRNA inactivation with consequent slowing down of protein synthesis and accordingly of the cell growth rate. In addition, the stringent response has at most a minor effect. In conclusion, near-ultraviolet light is able to decrease the rate of cell growth by restricting the availability of charged tRNAs, and this occurs without affecting the cell division rate.     

A review of caryocar brasiliense (caryocaraceae)—an economically valuable species of the central brazilian cerrados

Caryocar brasiliense Camb. is a member of the Central and South American family Caryocaraceae. Most species of the family are found in tropical rainforests and are economically valuable.C. brasiliense is the main representative in the Brazilian cerrados and grows naturally wherever this type of vegetation is found. Ecologically, the species plays a significant role in the cerrado’s composition. The fruits and seeds are over-exploited due to their wide range of uses, and questions have been raised about whether the intensive exploitation poses any threat to the conservation of the species.