Nowadays, "cat sucking" has become a new fashion that is popular among the younger generation. Raising cats to dry cats, going to cat cafes to pick up cats, and "cloud sucking cats" on various platforms are the daily routines of many young friends. For scientific research dogs like me, when they are ravaged by scientific research to exhaustion, they can suck a cat and cat fiercely, and suddenly they can calm the pressure, resurrect with blood, and fight against the cold data for another three hundred rounds.
But who would have thought that in addition to giving spiritual comfort to scientific research dogs, cats can also contribute to the cause of human health and health scientific research. An article published in Trends in Genetics in July 2021 suggests that cats are also suitable as model animals to contribute to genetics research.[1] After that, the research dog can suck the cat in the laboratory!
Cats are good friends of humans | Pixabay
Selection criteria for pattern animals
When it comes to the term "model animal", everyone may be relatively unfamiliar, but in fact, the medicine we take when we are sick, the injection, and the water we hang, can only be developed without the help of the model animal.
Mice, fruit flies, and zebrafish familiar to friends in the field of life science research are common laboratory animals in basic laboratories, and many model animals in the field of brain science will also involve non-human primates, such as marmosets, cynomolgus and rhesus macaques.
1 Macaca fascicularis | Pixabay
2 非洲爪蟾（Xenopus laevis） | Wikimedia Commons, Chris Brown / Public domain
3 Drosophila melanogaster | Wikimedia Commons,
André Karwath aka Aka / CC BY-SA 2.5 (https://creativecommons.org/licenses/by-sa/2.5)
4 Mus musculus | Wikimedia Commons,
George Shuklin / CC BY-SA 1.0 (https://creativecommons.org/licenses/by-sa/1.0)
5 Zebrafish | Wikimedia Commons, Azul
What do these model animals have in common? What kind of animal can become a qualified model animal?
Laboratory Animal Medicine discusses the history of laboratory animals in detail. As early as 2000 BC, the ancient Babylonians and Syrians at that time retained information on the operation and medication of animals.[3] With the development of the times, the existence of model animals has provided an indispensable help in revealing the secrets of the biomedical field. The proportion of model animals in research is increasing, and the concept and selection criteria of model animals are becoming clearer.
Not all animals can be model animals. In the field of life sciences, medicine and health research, laboratory animals that have very similar physiological and pathological characteristics to humans or other rare studied species, and are easily accessible and easy to operate are eligible as model animals. Therefore, the selection criteria for model animals are mainly three points:
· Research value. It is necessary to have very similar physiological and pathological characteristics to the species under study. The higher the similarity, the greater the value of the study;
Short generations, many offspring, easy to reproduce. Just as no one chooses a turtle as an experimental animal, the excessive lifespan of experimental animals will make it difficult for the experimenter to observe and seriously slow down the experimental process. At the same time, the large number of offspring and easy reproduction will also greatly reduce the cost of experiments;
Easy to perform experimental operations. The physiological characteristics and anatomical structure of different animals are very different, so when selecting animals for experiments, it is necessary to consider the characteristics of each animal. For example, rats without gallbladders cannot be selected for gallbladder-related studies.
"Tom and Jerry"
Mice that meet these three criteria have become experimental animals as early as the 17th century.
At present, mice are the most well-studied mammal experimental animals in the world. The mouse genome sequencing program has been completed. Mouse and human genes are very similar, with 99% of human genes found in the mouse genome and nearly 80% homology (referring to genes with the same ancestor or origin from an evolutionary perspective) [9]. Moreover, transgenic technology is very mature in mice, and can introduce the gene fragments of interest we need to study into the mouse genome to build the mouse model of the disease we need.
Attaching importance to mice, scientists have not forgotten cats and cats. Cats are also a very good model animal. There is a rich veterinary literature on cat diseases, and there are 250 kinds of cat genetic diseases similar to human genetic diseases, of which 18 species such as spherical cell leukodystrophy have found pathogenesis and corresponding treatments [6].
Cats are a very good model animal | Figureworm creative
Cats are also research models of several deadly human viral diseases, notably FEIDS, whose pathogen Feline Immunodeficiency Virus (FIV) is similar in structure and sequence of nucleotine to the HIV virus that causes human AIDS. The virus is endemic in 14 species of free-range cats, including domestic cats.[4] Cats infected with FETS also often develop symptoms similar to immune insufficiency caused by human AIDS infection.
Feline immunodeficiency virus (FIV) and human immunodeficiency virus (HIV) | References[4]
In addition, cat leukemia virus, feline sarcoma virus and feline coronavirus carried by cats have also laid the foundation for the discovery of pathogenic viruses and the establishment of their toxicity models.
But in deciphering the relationship between the human genome and disease, studying the genome of cats has greater potential and prospect than we currently know. An article published in Trends in Genetics in July showed that the genomes of cats and humans are more conservative and have fewer chromosome rearrangements than those of dogs or mice, based on similar gene sizes. Moreover, the distribution of genes on the 23 pairs of chromosomes in humans is more similar to that of 19 pairs of cats than in other common mammalian models such as mice, rats, dogs, or pigs.
It is precisely because of the high similarity in gene size, number, and distribution that studying the genomes of cats may be of great help to us decipher the genetic "dark matter". Like the unknown matter that makes up 85 percent of the total mass of the universe, 95 percent of the sequences in our human genome don't code for proteins, and are also figuratively called genes "dark matter."
We used to think of these sequences as "junk" because they don't code for proteins, and only proteins are the bearers of life activities. However, studies have shown that the onset and development of many diseases may be associated with sequence changes in these non-coding proteins.
For example, if we insert a certain length, meaningless sequence in the "dark matter" of a gene that does not code for proteins around kit, a gene associated with the cat's plaque albinism, it will affect the normal expression of the KIT gene, resulting in the inability to produce melanin and migrate normally in the body. Abnormal changes in melanin in the body will cause the cat to get all-white hair or white spots in the cat's hair. And melanocytes can also help maintain the high potassium level of the liquid around the hair cells in the cat's ear, once the melanin is abnormal and cannot maintain high potassium levels, the hair cells in the ear will die, resulting in deafness. So even if it's a gene "dark matter" that doesn't directly code for proteins, we can't ignore that its alterations may play an important role in regulating life activities.
In addition to disease research, cat neurobiology has also contributed to traditional topics. Cats have a number of strange behaviors related to parenting, defense, suggestion, and taming, which also seem to be influenced by genes [5].
In many ways, cats can be an excellent model animal with great research potential.
Be kind to laboratory animals and pay attention to animal welfare
Perhaps cat lovers from the time they saw the title of the article, they fell into the tangled mentality of "being proud of the cat, and worrying that the cat and cat have to go through too much". But don't worry too much, in the United States, for example, the number of cats as experimental animals has decreased from more than 74,000 in 1974 to more than 18,000 in 2019.
In the United States, the number of cats used for research each year is declining year by year | References[8]
And now, there is a global consensus to maintain the welfare of laboratory animals. World Animals Day is celebrated on 24 April each year, and the week before and after is known as Laboratory Animal Week, where people around the world hold various events to call attention to the health and well-being of laboratory animals. In addition, the basic principles of the "3Rs" of laboratory animals are internationally recognized, namely Replace, Reduce, and Refine. Try to replace live animals with unconscious experimental materials, reduce the amount of laboratory animals, create a good experimental environment or reduce the pain and uneasiness caused to animals.
Herd cats are more outgoing and more willing to interact with their breeders. Mounting shelves allows cats to take advantage of vertical and horizontal spaces, reducing overcrowding | References[6]
Where we can't see, these cats silently give a lot. When we enjoy the benefits brought by the development of medical technology, we may as well add a handful of dried fish to the cat owner at home.
bibliography
[1] Lyons L A. Cats–telomere to telomere and nose to tail[J]. Trends in Genetics, 2021.
[2] Fox J G. Laboratory animal medicine[M]. Elsevier, 2015.
[3] Troyer J L, Pecon-Slattery J, Roelke M E, et al. Seroprevalence and genomic divergence of circulating strains of feline immunodeficiency virus among Felidae and Hyaenidae species[J]. Journal of virology, 2005, 79(13): 8282-8294.
[4] Lin Y C, Torbett B E, Elder J H. Generation of infectious feline immunodeficiency virus (FIV) encoding FIV/human immunodeficiency virus chimeric protease[J]. Journal of virology, 2010, 84(13): 6799-6809.
[5] O’Brien S J, Johnson W, Driscoll C, et al. State of cat genomics[J]. Trends in genetics, 2008, 24(6): 268-279.
[6] Griffin B, Baker H J. Domestic cats as laboratory animals[J]. Laboratory animal medicine, 2002: 459.
[7]http://www.simm.cas.cn/kxcb/kxcb_kpwz/201704/t20170424_4779185.html
[8]https://navs.org/learn-more/cats-in-research/
[9] Waterston R H, Pachter L. Initial sequencing and comparative analysis of the mouse genome[J]. Nature, 2002, 420(6915): 520-562.
Source: I am a scientist iScientist
Editors: Lychee, yrLewis