Heterochronic developmental plasticity of the juvenile rudiment and larval body of sea urchin larvae occurs in response to supply of food. Evolutionary increase in egg size can also be associated with earlier development of the juvenile rudiment. We examined effects of egg volume of feeding larvae on this heterochrony and other changes in larval form. (1) Evolutionary and experimental enlargeme...

The size of the pathogenic agent of influenza A has, until recently, been generally accepted as that of a sphere about 100 m# in diameter. The viruscontaining preparations used in both the ultrafiltration (1) and the centrifugation experiments (2) upon which this estimate was based, consisted of emulsified lung tissue from infected mice. In the preceding paper two of us have shown that particle...

-To measure the changes in substrate composition produced by spawning brook trout Salvefinus fontinalis, we collected 187 freeze-core samples, both before and after spawning, from egg pockets, inside redds but excluding egg pockets, and outside redds. In the upper strata of reddassociated samples, we found that the proportions of particles 0.85-1.70,0.425-0.85,0.2 12-0.425, and less than 0.212 ...

Mouse sperm-egg fusion was examined using two-photon and confocal microscopy. A delay of several minutes occurred between the first observable event of fusion (which was the diffusion of Ca2+-sensitive dyes from egg into sperm) and any change in egg cytoplasmic Ca2+. When indo-1 dextran was used to obtain ratiometric two-photon images, there was no detectable local increase in egg cytoplasmic C...