By Matthew Wells
BBC News, Louisiana
The electronic metal gates closed ominously behind us as we entered the exotic world of the Audubon Center for Research of Endangered Species, just outside New Orleans.
The centre is trying to save species such as this African caracal cat
Our small group of journalists was escorted into a place reminiscent of the film Jurassic Park in more ways than one.
The movie is based on the fantasy of bringing rampaging dinosaurs back to life through samples of ancient DNA preserved in amber.
The biggest carnivore they have cloned from DNA so far here at the centre is an African wildcat; the science is very real, and it works.
Driving through the dense and lush forest, it wouldn't have been too surprising if a Tyrannosaurus had appeared out of the steamy undergrowth.
After a few minutes, we came upon the cages that house some of the cats that put the centre at the forefront of animal cloning.
Our young guide, Erin Sarrat, who is assistant curator for the precious animals and birds here, explained the extraordinary relationships between the three animals prowling around in front of us: "Jazz was a cat who was created by in vitro fertilisation."
The African wildcats are genetically identical
"He was born from a domestic cat, but he's an African wildcat - interspecies embryo transfer - the first ever for that kind of technology."
Pointing to the right-hand cage, she continued: "We cloned Jazz, and got Ditteaux, then we cloned Jazz again, and got Miles."
They are three genetically identical creatures, developed from one small batch of cells.
The centre does not allow many visitors, and your movements are strictly supervised.
This is partly for safety's sake, but also to protect the many rare and endangered animals which shelter here.
For a humble bird like the Mississippi sandhill crane - whose numbers have fallen to under 200 in the wild - the centre provides a refuge where a new generation can be reared through artificial insemination, and then put back in their natural habitat nearby.
But the most cutting-edge scientific work is happening at the white-walled laboratories inside the centre's elegant wooden lodge.
Frozen for posterity: Tanks contain cells from more than 1,000 species
Dr Betsy Dresser is head of research, and she was keen to show us round her so-called "frozen zoo".
It's not much to look at: a group of liquid nitrogen tanks cover the floor looking more like milk churns than anything else.
But inside, there are cells from more than 1,000 different species which can be kept in a preserved state for hundreds of years.
Dr Dresser held up one of the straws containing cell tissue, and explained how the Noah's Ark of the future works: "Once we've dropped it to the temperature where we know the cryoprotectant is like a slush, we can drop it instantly into liquid nitrogen, and essentially metabolism in the cells just stops."
In theory, no species alive today should ever become extinct, as long as one of the dozen frozen zoos around the world has a cell sample, she said: "If we'd done this with the dinosaurs... the cells would be alive."
Among the species they have suspended in cell form are gorillas, Sumatran tigers and the mountain bongo antelope.
The chief executive of the whole Audubon Nature Institute - which also runs more commercial attractions like the New Orleans zoo and aquarium - is Ron Forman.
He said that although donations were always welcome, they had turned down several lucrative offers from private individuals to clone a beloved pet.
"We're working through science to save species for the next generation. More and more zoos are involved. There are partnerships all over the world to save these species and put them back in their habitat."
Aside from the impressive science involved, some conservationists have voiced concern that frozen zoos will take the focus away from preserving natural habitat.
If animals can be saved in test tubes, why worry about their place of origin?
But Dr Dresser is adamant that a combined approach is the best and surest way to stop the slow slide towards extinction.
"Hopefully in Europe they'll be doing more of this in the future. It's a safety net... it's a way of providing for your kids, and their kids.
"Wouldn't it be awful if habitat was saved, and everyone turned around and said - but where are the animals?"