Experiments explain why almost all multicellular organisms begin life as a single cell. Any multicellular animal, from a blue whale to a human being, poses a special difficulty for the theory of evolution.
During plant growth and development chloroplasts divide repeatedly in order to maintain their population. The site of division is specified by the medial placement of the FtsZ ring. Altered FtsZ ring placement can result in disrupted chloroplast division, a phenomenon observed in msl2 msl3 double mutant plants. This image illustrates that two mechanosensitive channel homologs, MSL2 and MSL3, are necessary for proper FtsZ ring placement and chloroplast division. Cauline leaf mesophyll cells of msl2 msl3 double mutant plants expressing FtsZ1-GFP contain grossly enlarged chloroplasts with aberrant FtsZ ring placement. FtsZ1-GFP and chlorophyll fluorescence are represented by pseudo-color green and red, respectively.
20-year study of collared lizard restoration reveals secrets of the Ozarks. In a time when a five-year grant is considered a long-term grant, Alan R. Templeton, PhD, a professor of biology in Arts & Sciences at Washington University in St. Louis, has managed to follow some of the species he studies for 10, 20 or even 30 years.
In the genus Paramoryrops (top), electric organ discharges have rapidly evolved, resulting in dramatic differences in signal waveform among closely-related species. In the genus Petrocephalus (bottom), electric organ discharges have evolved much more slowly, resulting in similar waveforms among species. The study by Carlson et al. reveals that this difference in signal diversification rates resulted from evolutionary change in the electro-sensory and electro-motor systems that these fish use to communicate with each other. The duration of each pulse ranges from about 500 microseconds in various Petrocephalus species to nearly 10 milliseconds in Paramormyrops gabonensis.