The life cycle of fruit flies is an insect of the genus Drosophila in the family Drosophilidae. About 1,000 species. It is widely used as indoor and outdoor research materials on genetics and evolution, especially the fruit fly (D. melanogaster) is easy to cultivate. Its life cycle is short, less than two weeks at room temperature. More genetic data has been collected on fruit flies than on any other animal. Use Drosophila chromosomes, especially the largest chromosomes in the salivary glands of mature larvae, to study the basis of inherited traits and gene action. Not enough is known about the biology of fruit flies in nature. Some species live on rotting fruit. Some species live in fungi or fleshy flowers. [Edit this paragraph] Appearance characteristics Drosophila melanogaster is small in size, with a body length of 3 to 4 mm. It is difficult to identify similar species, and its main characteristic is its large red compound eyes. The female body length is 2.5 mm, and the male body length is even smaller. Males have dark hind limbs to distinguish them from females. [Edit this paragraph] Distribution range Drosophila insects are distributed all over the world like humans, and spend the winter in human homes. Due to their small size, they can easily pass through sand windows, so they are also commonly seen in home environments. [Edit this paragraph] Living environment Some species live on rotten fruits. Some species live in fungi or fleshy flowers. As long as you find many small red-eyed flies next to garbage cans or on fruits that have been left for a long time, they are fruit flies; fruit fly larvae are accustomed to breed in garbage dumps or rotten fruits. [Edit this paragraph] Drosophila melanogaster Drosophila melanogaster was first described in 1830. The first time it was used as an experimental research object was in 1901, by the zoologist and geneticist William Ernst Custer. Through germline research on fruit flies, he tried to understand the results of multiple generations of inbreeding and the phenomena that occurred when crosses were taken from one of the generations. In 1910, Thomas Hunt Morgan began to breed fruit flies in the laboratory and conduct systematic research on them. After that, many geneticists began to use fruit flies for research and obtained a lot of genetic knowledge, including the distribution of genes in the fly genome on the chromosomes. Female flies can lay 400 eggs of 0.5 mm in size at one time. They are surrounded by chorion and a layer of yolk membrane. Its development rate is affected by ambient temperature. In an environment of 25°C, the larvae will emerge from their shells after 22 hours and start looking for food immediately. Because the parent will place them on rotting fruit or other fermenting organic matter, their first food source is fruit-rotting microorganisms such as yeast and bacteria, followed by sugary fruit. The larvae will molt for the first time after 24 hours and continue to grow to reach the second larval development stage. After three larval development stages and four days of pupal stage, they will develop into adults after one day at 25°C. [Edit this paragraph] Scientific research on genetically modified fruit flies Genetically modified fruit flies are born: they can be remotely controlled by laser irradiation. Remote control is no longer a patent for electronic products. Scientists have newly bred a genetically modified fruit fly that can use laser irradiation to remotely control their behavior, making lazy The fruit flies become active and begin to crawl, jump or fly away. The relevant paper was published in the latest issue of the journal Cell. Although remote control of this fruit fly is not as convenient as driving a remote control car, the relevant methods are of great significance for studying the nerves and behavior of animals. In the past, when scientists studied the neural basis of animal behavior, they generally used methods such as electrode stimulation of nerves. But these methods are invasive and can impede an animal's movement or even paralyze it, and it's impossible for electrodes to reach every neuron in the entire nervous system. Neurobiologists at Yale University School of Medicine in the United States inserted a gene from rats into fruit flies. This gene encodes an ion channel protein. In the presence of the bioenergetic molecule ATP in the environment, this ion channel allows charged particles to pass through the cell membrane, thereby transmitting electrical impulses. Drosophila chromosomes Next, the researchers injected the flies with ATP molecules that were inactive because they were wrapped in another molecule. Irradiating fruit flies with ultraviolet laser can liberate ATP molecules from their restraints, activate ion channels, and stimulate the nerves of fruit flies with electrical signals.
Experiments show that if this ion channel protein is expressed in the dopaminergic neurons that control fruit flies' crawling, otherwise lazy fruit flies become hyperactive when exposed to laser light. If the ion channel is expressed in the large nerves that control the fly's escape response, the laser light can make the fly jump around, flutter its wings and fly away. The researchers said that this technology can be used to study many other behaviors of organisms, such as courtship, mating and eating. Drosophila are divided into white eyes and red eyes. White eyes are the result of genetic mutations and are recessive inheritance located on the X chromosome, because they only have 4 pairs of chromosomes facilitate experimental observation and are often used to study sex-linked inheritance. American biologist Morgan once used this trait to study the laws of gene linkage and interchange. But it should be noted that fruit flies can backcross and their growth cycle is short, but Morgan has done backcross experiments. Drosophila and Morgan——The Spring of the Law of Heredity [1] Morgan mainly used fruit flies as experimental materials in his genetic experiments, and his important discoveries were all made from fruit flies. Some people say: God created fruit flies for Morgan. Cute little fruit flies Fruit flies are small flies, only a few millimeters in length. , because it likes to fly on rotten fruits, so it is called fruit fly. In fact, what it likes is wine produced by the fermentation of rotten fruits, so many fruit flies will be attracted in front of the wine fermentation tank. The ancient Greeks called fruit flies "alcoholics." As experimental animals, fruit flies have many advantages. First of all, it is easy to raise. You can raise hundreds or even thousands of fruit flies with a milk bottle and some mashed bananas. The second is the rapid reproduction. One generation can be reproduced in just ten days at a temperature of about 25°C. One female fruit fly can reproduce hundreds of flies in one generation. Mendel used peas as experimental materials and only planted one generation a year. Morgan initially used mice and pigeons as experimental animals to study genetics, but the results were not satisfactory. Later, someone introduced that Morgan started raising fruit flies in 1908. Drosophila has only four pairs of chromosomes, which are small in number and have obvious differences in shape. Fruit flies have many variations in traits, such as eye color, wing shape and other traits. These characteristics are also of great benefit to genetic research. Morgan did not understand these favorable characteristics all at once, but gradually realized them during his research work. Because there were many fruit flies raised in Morgan's laboratory, and researchers waited on and observed fruit flies all day long, people called the experiment he led the "fly room." Under Morgan's leadership, the "Fly Room" became a center for genetics research around the world. Their research results have attracted the attention of the genetics community around the world, and the papers and books they wrote are must-reads and important references for geneticists around the world. This "fly room" also produced many famous geneticists. Some people, represented by Lysenko of the former Soviet Union, once vigorously attacked the Morgan School, which used fruit flies as its main research object, as having no practical significance and not caring about the national economy and people's livelihood. This attack has proven untenable. The genetic rules discovered in fruit flies are also applicable to other animals, plants, and humans. There has been important development in theory and it will be of great significance in practice. Discovery of Sex-Linked Inheritance Morgan’s laboratory initially used fruit flies to study whether acquired traits could be inherited. He cultivated fruit flies in a dark environment for many generations. According to Lamarck's theory of use or loss and the inheritance of acquired traits, their vision should gradually deteriorate. But that was not the case, and Morgan believed the experiment was in vain. Morgan made important genetic discoveries using fruit flies, starting with a white-eyed fruit fly, from which he discovered sex-linked inheritance. Wild fruit flies all have red eyes, but in 1910 Morgan discovered a male fruit fly with white eyes. According to genetic theory, this is a genetic mutation. If you mate this white-eyed male fly with an ordinary red-eyed female fly, the next generation of fruit flies will all have red eyes. According to Mendelian theory, red eyes are a dominant trait and white eyes are a recessive trait. The first generation of fruit flies mates to produce a second generation. As a result, all female fruit flies have red eyes, and half of the male fruit flies have red eyes and half have white eyes. Regardless of male or female, the ratio of red-eyed fruit flies to white-eyed fruit flies is 3:1, which is consistent with Mendel's law.
However, what are genes? How do genes control traits? It was still unknown until the 1930s. Mendelian-Morganian genetics is essentially formal genetics. Although genes have a material basis, Morgan's genetic research using fruit flies did not start from the understanding of the genetic material itself. Various conclusions were drawn based on the analysis and reasoning of experimental results. Morgan wanted to take his genetics research to a new level and study how genes function to control traits. At the beginning of the 20th century, a British doctor discovered that alkapsis is a hereditary disease, and found that the cause of alkapsis is the lack of homogentisic acid oxidase in the patient's body, which prevents the decomposition of homogentisic acid. He therefore proposed that genes could control the formation of enzymes, thereby affecting metabolic processes. Morgan's laboratory continued to conduct research in this area using fruit flies as early as the 1930s. Their experimental results showed that there is a transformation process for the substance that determines the eye color of fruit flies, and they could analyze which eye color mutation lacked the enzyme required for which step of the reaction. However, they were unable to test and separate the various related substances, and the experiments could not go in depth. Today, with the rapid development of biological sciences, although the biological research fields and research organisms are gradually diversified, Drosophila, as a classic model organism, plays an extremely important role in the research and development of the biological field. As a model organism, Drosophila still has great research potential.