The use of restriction enzymes as a tool for recombining, or joining, different DNA fragments was first illustrated in yet another classic paper, this time by Stanford University researchers Janet Mertz and Ronald Davis (Mertz & Davis, 1972).
Averages for Puerto Vallarta in February. The temperatures are still very warm in Puerto Vallarta, Mexico, in February, even though itâs still winter. Thanks to the cityâs location close to the equator, it enjoys good weather all year round providing the perfect place to head for a winter beach break â it certainly beats the cold European winter.
1 Beach activities are popular in Puerto Vallarta which include wind surfing, scuba diving,and water-skiing. 2  Best time to find cheap direct flights to Puerto Vallarta is during the rainy season - (June-October). 3  Gustavo Diaz Ordaz International Airport (PVR) serves flights to Puerto Vallarta.