Fertilization in flowering plants is dependent on a protein that is secreted by the egg cell and activates incoming sperm.
Stefanie Sprunck at the University of Regensburg in Germany and her colleagues show that in the model plant Arabidopsis thaliana the arrival of sperm cells near the egg causes the release of a protein they call EGG CELL 1 (EC1). This triggers the redistribution of a second protein — one linked to fusion of the sex cells or gametes — from inside the sperm to the sperm cell surface.
Sperm cells interacting with mutant Arabidopsis eggs that have faulty ec1 genes failed to fuse and the plant's pollen tubes continued to deliver sperm into the embryo sac. These results suggest that EC1 controls gamete fusion.
【The Kyoto Protocol专题】
Even though countries are burning unprecedented amounts of oil and gas the estimates of how much is left continue to grow thanks to high prices and new technologies that have enabled companies to find and extract new resources. A decade ago it was the tar sands of Canada and Venezuela. More recently hydraulic-fracturing technologies have opened up oil and gas resources in the United States. Across the globe proven oil and gas reserves are 60% higher today than they were in 1991. At current consumption rates those reserves would last for about 60 years — and that could be extended by new discoveries and unconventional deposits. Coal reserves have not increased in size but the supply will last for at least a century at current rates of consumption.
Renewables such as solar and wind power are growing faster than any other source of energy but are bare