Cytoplasmic Solvent Structure of Single Barnacle Muscle Cells Studied by Electron Spin Resonance

A free radical probe was introduced into single barnacle muscle cells, and its freedom of motion inferred from the spin resonance spectra. The probe reported an average local viscosity of 5-10 cp compared with 1 cp for pure water. From a comparison of the temperature dependence of the probe's tumbling rate in model aqueous systems and in the muscle we concluded that in the muscle the probe was undergoing fast exchange between sites of different mobility. Thus 10 cp must be taken as an upper limit for the viscosity of most cell water.     

Remodeling of the uterine artery during and early after pregnancy in the mouse

Biomechanics and Modeling in Mechanobiology - Pregnancy associates with dramatic changes in maternal cardiovascular physiology that ensure that the utero-placental circulation can support the...     

Toward minimal bacterial cells: evolution vs. design

Recent technical and conceptual advances in the biological sciences opened the possibility of the construction of newly designed cells. In this paper we review the state of the art of cell engineering in the context of genome research, paying particular attention to what we can learn on naturally reduced genomes from either symbiotic or free living bacteria. Different minimal hypothetically viable cells can be defined on the basis of several computational and experimental approaches. Projects aiming at simplifying living cells converge with efforts to make synthetic genomes for minimal cells. The panorama of this particular view of synthetic biology lead us to consider the use of defined minimal cells to be applied in biomedical, bioremediation, or bioenergy application by taking advantage of existing naturally minimized cells.     

Ion Transport Through Excitability-Inducing Material (EIM) Channels in Lipid Bilayer Membranes

Two different methods were used to determine the relative permeability and the voltage-dependent conductance of several different cations in excitability-inducing material (EIM)-doped lipid bilayers. In one method, the conductances of individual channels were measured for Li, Na, K, Cs, NH₄, and Ca, and in the other method biionic potentials of a membrane with many channels were measured for Li, Na, K, Cs, and Rb. The experimental results for the two methods are in agreement. The relative permeabilities are proportional to the ionic mobilities in free aqueous solution. The voltage dependence of the conductance is the same for all cations measured.     

Sewage dilution and loss of antibiotic resistance and virulence determinants in E. coli

The possession of potential virulence factors (serum resistance, aerobactin production, colicin production) and antibiotic resistance was evaluated in 418 E. coli strains isolated from river water. The strains were isolated from 11 points showing different levels of contamination. From the data obtained, it can be concluded that bacteria from less contaminated water present less antibiotic resistance and virulence factors than those isolated from highly contaminated water. This situation suggests that E. coli strains producing plasmid encoded antibiotic resistance and/or virulence factors, survive less well in aquatic environments without selective pressure) than the sensitive non-virulent ones.     

Comparison between phenological and aerobiological patterns of some arboreal species of Mar del Plata (Argentina)

An atmospheric pollen survey and a periodical quantitative check of the flowering phases of trees were performed during 1993. Most of specific flowering seasons lasted from 4 to 8 weeks. October is the month with the highest number of species in bloom. Anemophylous species flower mainly in coincidence with the relatively low temperatures of late winter and early spring, while the enthomophylous ones correlate with the high temperatures of late spring and summer. The anemophylous ‘community’ follow a sigmoid pattern with respect to both the flowering development and the cumulative pollen concentration. Agreement between floral phenophases and pollen counts were evaluated for 14 genera (27 species). Pollen data of anemophylous species coincide fairly well with the phenological behaviour. Particular features must be taken into account to interpret this relationship.