In a basement laboratory abutting an 1,800-acre wildlife park in San Diego, California, Marlys Houck seems as much as see a uniformed man holding a blue insulated lunch bag full of small items of eyes, trachea, toes and feathers.
“Ah,” she says, softly. “Listed below are at the moment’s samples.”
The bag in query accommodates small bits of sentimental tissue collected from animals who’ve died of pure causes on the zoo. At present, the samples embody a leaf frog and a starling.
The person holding the bag is James Boggeln, a volunteer with the zoo, who palms it off to Houck, the curator of this laboratory, generally known as the “Frozen Zoo”. She and her group will begin the method of turning these bits of tissue right into a financial institution of analysis and conservation for the long run. They may put the tissue into flasks the place enzymes digest them, then the lab members will slowly incubate them over the course of a month – rising an abundance of cells that may be frozen and finally reanimated for future use.
At almost 50 years previous, the Frozen Zoo holds the world’s oldest, largest and most various repository of residing cell cultures – greater than 11,000 samples that signify 1,300 totally different species and subspecies, together with three extinct species and extra which are very near extinction.
At present the Frozen Zoo is operated by an all-female group of 4, who watch over an unlimited assortment of hand-marked vials with labels equivalent to “giraffe”, “rhino” and “armadillo”, all saved in huge round tanks full of liquid nitrogen. In a world affected by a local weather and biodiversity disaster, placing species on ice provides one strategy to be hopeful concerning the future.
The work finished right here has at all times felt significant, however an accelerating extinction disaster has put mounting stress on Houck and her group. It’s a race in opposition to time to place samples into the Frozen Zoo earlier than they slip away from the world exterior the lab. The ladies who maintain these jobs see it as their obligation to carry the long run in place.
The work might be painstaking – samples from birds, mammals, amphibians and fish all require totally different processes, for instance. However with stakes so excessive, Houck describes it with a form of sacred reverence.
She feels the stress of the position – when her predecessor was in cost, a mechanical failure led to the lack of 300 samples, a 12 months’s work. So her thoughts is concentrated on maintaining the samples the zoo has frozen protected, Houck says – “however then mixed with the thrill and this pleasure, as a result of it’s an honor to have the ability to do that”.
‘Accumulate issues for causes you don’t but perceive’
The zoo was based by a German American pathologist named Kurt Benirschke in 1972, who began a group of animal pores and skin samples in his lab on the College of California at San Diego after which moved it to the San Diego Zoo a couple of years later. On the time there was no know-how to make use of it past fundamental chromosome analysis, however Benirschke usually quoted the American historian Daniel Boorstin: “You could gather issues for causes you don’t but perceive.”
That quote nonetheless hangs on a poster within the Frozen Zoo, the place Houck pulls vials from tanks of liquid nitrogen that resemble big silver thermoses the scale of a human. The tanks are pressurized at -320F, a temperature that stops cells from shifting or altering – maintaining them alive however in suspended animation. From this temperature, the cells might be revived and proceed residing as if many years – or centuries – hadn’t handed.
No species is precisely the identical, and a few teams are more difficult to protect than others. The Frozen Zoo began with mammals, then expanded to cryobanking birds, reptiles, and amphibians. The success price with mammals is near 99%, Houck says. “With amphibians, it was near 1% for numerous years, and now I believe perhaps we’re 20 to 25%. Birds are fairly excessive.”
Racks within the nitrogen tanks maintain 100 vials every, and every vial accommodates 1m to 3m residing cells. These cells – a giraffe, a lemur, or one thing extra endangered like a vaquita – maintain attainable options for an array of current and future issues.
Finally, the cells may very well be used to carry again totally extinct species – however that’s not the primary aim. As an alternative, the fabric is mostly used to rescue current species which are struggling. In 2020, the Frozen Zoo used cryopreserved DNA to clone a black-footed ferret, the primary endangered species in america to be cloned. Final 12 months, frozen cells cryopreserved 42 years in the past had been used to clone two critically endangered Przewalski’s wild horses, bringing precious genetic range again to the residing inhabitants that may make it extra resilient to new diseases or environmental threats. One of many foals was named Kurt, after the Zoo’s founder.
The work that San Diego’s Frozen Zoo is a part of a worldwide motion to cryobank all the pieces from animals to seeds. At present there are round a dozen wildlife-based cryobanks around the globe, largely situated in North America and Europe.
The work finished in San Diego has been significantly groundbreaking, says Sue Walker, head of science at Chester Zoo, and co-founder and vice-chair of the UK nonprofit Nature’s Secure, a cryobank that collects stay cells and sperm and eggs. She says that in a couple of extra many years, it is perhaps attainable to show these cells into pluripotent stem cells, which might be reprogrammed to provide sperm and eggs.
In a perfect world, species may very well be conserved within the wild – however in actuality, that’s not the case. “We’re dropping species too quick for science to maintain up,” she says. “So the least we will do is try to financial institution that materials down.”
It’s tough to get permits to herald tissues from animals in different nations, so the hope is to develop the capability in different places to cryobank regionally, significantly close to conservation hubs in Africa, South America and south-east Asia. However which means build up the capability to course of and protect the inhabitants of cells in a uniform approach. It’s costly and complicated work – but in addition vital, Walker says.
“I believe we’ve got to throw all the pieces at it with a view to save a few of these species which are getting ready to extinction,” she says. “It’s about banking hope.”
Time machines to previous and future
Engaged on the cell cultures might be like working a time machine. Houck was as soon as learning rhino chromosomes and she or he opened a vial together with her predecessor Arlene Kumamoto’s handwriting on it. Kumamoto had put the cells right into a deep freeze the identical month Houck graduated from highschool. “I simply thought, oh my gosh … she was freezing cells that I’m now utilizing for my research. If she hadn’t finished that, I wouldn’t be doing what I’m doing,” Houck says. “What are we doing at the moment that will probably be used sooner or later?”
Julie Fronczek, who has labored on the zoo for twenty-four years, seems up from her microscope to supply a concept about why a bunch of girls is main this work on the Frozen Zoo. “We’re nurturing the cells. They’re residing creatures they usually must be fed and brought care of, then it’s important to know what they need when they need it,” she says. “It’s form of like infants.”
The group provides round 250 to 350 specimens to the zoo every year. The leaf frog that arrived at the moment is a excessive precedence, Houck says. The starling that additionally arrived? Much less crucial. Such selections weigh closely on her. Since every new animal that arrives must be cultured and preserved, and takes up area within the big containers, she has to think about what number of of that species are already represented, and what number of potentialities there are to get extra of them. “I want to not have to show something away. It will be higher if we might settle for each pattern that got here in as a result of they’re all essential.”
The gathering contains three extinct species: the po’ouli or Hawaiian honeycreeper, Rabbs’ tree frog, and the Saudi gazelle. They’re holding a collective breath as they look ahead to extra species of their assortment to go extinct. “The subsequent will most likely be the white rhino and the vaquita,” Houck says.
The room holding the tanks is full – however the tanks aren’t but at capability, so the group continues its work of culturing and preserving the cells that might imply life or loss of life for endangered animals sooner or later.
Sooner or later, the lab must replace its strategies – these handwritten vials will finally be scannable barcodes. It additionally wants recent scientists to return and preserve a aware watch over the rising zoo on ice.
“I believe we’re all very protecting of the frozen zoo and the legacy and Dr Benirschke’s legacy,” Houck says. “And I hope that we will instill a era who will carry it ahead from us.”
