Today is International Laboratory Animal Day . Currently, animals are still necessary to carry out certain scientific investigations, and not only in biomedicine or in veterinary medicine. Behavioral studies or genetic analyses, in addition to advancing the knowledge of these areas, result in better and more efficient ways of protecting species and ecosystems.
When we talk about laboratory animals, we usually think of rats, mice, guinea pigs and, perhaps, primates , because of their implications in the development of drugs and vaccines. However, many other animals are used in laboratories around the world and help us answer questions in various areas of knowledge.
Hydra
No, it is not about the mythological monster that if one head was cut off, two others took its place. Hydra is a genus of the phylum Cnidaria , a small polyp that recently became famous for being animals that have reached the secret of eternal youth .
It really is an animal that does not get old; he is potentially immortal. In addition, this fascinating creature can regenerate any part that is amputated. Even if its head is cut off, it does not grow two in its place, but it does grow another.
Hydras display complex regulatory genetic structures.
Unraveling its mysteries can give us many clues about how certain tumors proliferate — also made up of cells that don’t die — or how hydras avoid these types of problems. Research using hydra as a model animal can provide many answers to current scientific questions.
Caenorhabditis elegans
Caenorhabditis elegans is a species of nematode and one of the simplest animals with a nervous system. Thanks to this peculiarity, in 1963, the biologist Sydney Brenner took these animals as a model for the study of neuronal development in animals , a fact that earned him the Nobel Prize in 2002. During the 70s of the last century, thoroughly studied its genetics and metabolism.
In 1998, this free-living nematode became the first multicellular organism with a complete genome sequenced . Its genome contains 20,470 protein-coding genes, 35% of which have homologous genes in humans. It is a species that accepts transgenesis well, so human genes are inserted to carry out studies related to human genetics.
Among the investigations in which it has been used as a model, studies related to cell development and metabolism stand out. It has been used to map cell lineages, to study programmed cell death processes, and for sensory biology.
It has multiple biomedical applications, including research on obesity, drug addiction, sleep studies, aging , and has even been used in the fight against Alzheimer’s . In addition, they have been used in the study of the effects of microgravity on the International Space Station.
Drosophila melanogaster
Few animals have been used as much in research as the fruit fly . These insects are characterized by a very short life cycle and ease of rearing and handling, with low maintenance costs, making them good candidates for a laboratory.
The fruit fly as an animal model is applied in disciplines ranging from fundamental genetics —interactions between inherited mutations can be traced in a Mendelian fashion— to the development of organs and tissues , or the effect of certain toxins on such development. There is even investigation of experimental evolutionary biology .
The fruit fly genome is less redundant than the human one, 60% of its genes have homologies with human genes, and up to 75% of the genes responsible for human diseases, in turn, have their counterparts in the fly .
In recent years, the amount of research using the fruit fly as a biomedical model has grown significantly, especially in cancer-related research . However, its full potential has not yet been exploited.
Danio laughed
The so-called zebrafish is one of the most versatile laboratory model animals. During its embryonic phase, the body of the zebrafish is transparent, which allows direct developmental applications to be studied in vivo. It is an easy and cheap maintenance animal, and very simple to breed.
Among the multiple applications of zebrafish, the study of pathologies related to development, toxicology, pharmacology, behavior, molecular genetics and cancer stands out.
It is used as a genetic model for human and veterinary biomedical research . In this aspect, the zebrafish is used as a model organism for the investigation of treatments of species related to aquaculture .
It supports transgenesis fairly well, and up to 70% of disease-associated genes have functional homologues in zebrafish, so you can easily use fish that have a mutation-carrying human gene inserted and test its effects or possible treatments.
Xenopus laevis
Central nervous system lesions are rarely reversible in mammals , including humans. However, other vertebrates have the ability to partially or even fully recover. In the African clawed frog we find this great potential for recovery , both of the brain and of the spinal cord, during larval development, but it loses it during metamorphosis, with the exception of the optic nerve, which can regenerate it throughout its life.
This property makes the African clawed frog an excellent laboratory model for the study of neurobiology . It offers the possibility of carrying out comparative experiments between regenerative and non-regenerative stages, which allow identifying which factors induce and which inhibit this capacity.
The investigations that have to do with X. laevis are, therefore, aimed at understanding the regeneration of the central nervous system , in the search for novel therapeutic approaches.
REFERENCES:
Farmanur Rahman Khan et al. 2019. Zebrafish (Danio rerio) as a Model Organism. En L. Streba et al. (Eds.), Current Trends in Cancer Management (pp. 3-11). IntechOpen. DOI: 10.5772/intechopen.73816Feng, Z. et al. 2006. A C. elegans Model of Nicotine-Dependent Behavior: Regulation by TRP-Family Channels. Cell, 127(3), 621-633. DOI: 10.1016/j.cell.2006.09.035Martı́nez, D. E. 1998. Mortality Patterns Suggest Lack of Senescence in Hydra.Experimental Gerontology, 33(3), 217-225. DOI: 10.1016/S0531-5565(97)00113-7Mirzoyan, Z. et al. 2019. Drosophila melanogaster: A Model Organism to Study Cancer. Frontiers in Genetics, 10, 51. DOI: 10.3389/fgene.2019.00051
