Host-bacterial mutualism in the human intestine

The distal human intestine represents an anaerobic bioreactor programmed with an enormous population of bacteria, dominated by relatively few divisions that are highly diverse at the strain/subspecies level. This microbiota and its collective genomes (microbiome) provide us with genetic and metabolic attributes we have not been required to evolve on our own, including the ability to harvest otherwise inaccessible nutrients. New studies are revealing how the gut microbiota has coevolved with us and how it manipulates and complements our biology in ways that are mutually beneficial. We are also starting to understand how certain keystone members of the microbiota operate to maintain the stability and functional adaptability of this microbial organ.     

Azotobacter cysts: reactivation by white light after inactivation by ultraviolet radiation

Cysts of Azotobacter vinelandii 12837 inactivated by ultraviolet radiation can be reactivated by white light. This photoreactivation mechanism is not seen in the vegetative cells of the same organism.     

Bends: detection of circulating gas emboli with external sensor

Circulating gas emboli associated with rapid decompression are detectable in superficial vessels of animals by the use of an ultrasonic Doppler flowmeter transducer which is applied externally.     

Wolves, moose, and the allometry of population cycles

After a decade of dramatic population fluctuations, protected populations of wolves and moose in Isle Royale National Park in Lake Superior returned in 1983 to the levels observed in the 1950's. Inherent lags in this predator-prey system and the strong recovery of the moose population following a wolf population crash suggest that these populations may continue to cycle with a period length of about 38 (95 percent confidence interval, +/-13) years. Such a long-term cycle is consistent with the proposal that period length of herbivore population cycles will characteristically scale according to the fourth root of body mass, a basic allometric relation linking physiological cycles to population processes.     

Cell size and rate of protein synthesis in ventral horn neurones

Autoradiographic studies show that small ventral horn neurones synthesize protein at a greater rate per unit area of cytoplasm than do large ones. It is suggested that this is related to the faster rate of firing of the smaller neurones.