Santa's Little Helper realistic dilemma faced by many families who own dogs. Other episode ideas come from popular culture. For example, Santa's Little Helper fathering 25 puppies in "Two Dozen and One Greyhounds" is a parody of the Disney film "One Hundred and One Dalmatians", and Mr. Burns' technique of brainwashing him into an attack dog in "Dog of Death" parodies "A Clockwork Orange". Susan McHugh, who teaches theories of animals, literature, and culture at the University of New England, wrote in her 2004 book "Dog" that, "remaining loyal to his unlikely saviours, the boy Bart and his father Homer, this greyhound has
Helper dependent virus and capsid encoding DNA, plus helper DNA. Every cell that is successfully transfected with all three DNA fragments will produce the necessary proteins to produce infective viruses. These viruses will only have transgenic DNA encapsidated and therefore once they've infected a patient's cell, they will not be capable of reproducing. Helper dependent viruses can also occur in nature without being "gutted". The term satellite virus has been given to a large group of viruses that all require the presence of another virus to replicate. Many of these are plant viruses, but animal viruses can be seen in the case of