Reverse transcriptase is characteristic of retroviruses, including HIV (human immunodeficiency virus), the virus responsible for AIDS (acquired immunodeficiency syndrome). All retroviruses encode a polymerase enzyme in their pol gene that is both necessary and sufficient for the replication of their RNA genomes.
PDO positive phase global pattern. The Pacific Decadal Oscillation (PDO) is a robust, recurring pattern of ocean-atmosphere climate variability centered over the mid-latitude Pacific basin.
A large scale abnormal warming in the equatorial Pacific is called El Nino, a term which also refers to the large scale atmospheric effects related to the warming. This phenomenon is closely related to a global atmospheric oscillation known to scientists as the Southern Oscillation (SO). During El Nino episodes lower than normal pressure is observed in the eastern tropical Pacific and higher than normal pressure is found over Indonesia and northern Australia. These conditions characterize the warm phase of the SO, which is often referred to as an El Nino/Southern Oscillation (ENSO) episode.