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.
Guide to Puerto Vallarta weather in May. The average maximum daytime temperature in Puerto Vallarta in May is a hot 33Â°C (91Â°F) with very high heat & humidity. The average night-time temperature is usually a comfortable 18Â°C (64Â°F). There are usually 8 hours of bright sunshine each day, which represents 63% of the 13 hours of daylight.