What Is Hereditary Multiple Exostoses?

Acquired inheritance is the abbreviation of "acquired trait inheritance", which refers to the phenomenon that organisms are affected by external environmental conditions in their individual lives, and have trait changes with adaptive meaning and a certain direction, which can be passed on to offspring. Proposed by French evolutionist C. Lamark in the 19th century. It is emphasized that external environmental conditions are the main reason for the variation of organisms, and have a great role in promoting the evolution of organisms.

Acquired inheritance

Acquired inheritance was first proposed by the French biologist Lamarck. In 1809, he published the book "Animal Philosophy", which systematically expounded the earliest theory of evolution. He emphasized the use of advancement and retreat, acquired inheritance, and the evolution of animal will. Important role in. In researching the interaction between animal habits and organs, he proposed two well-known laws: use of waste and acquired inheritance, that is, organisms in the development of individuals due to environmental influences or the use of waste in organs have gained new Traits, this new trait can be passed on to offspring. He said: "If a large change in an environmental constraint becomes a constant change in an animal, it is clear that the new habits of these animals will be derived." At the same time, he pointed out the characteristics of the body due to environmental impact. Changes can be divided into two major categories:

1. Changes in the body directly caused by the environment in a short period of time, such as limb defects, cannot be inherited;

2. Changes in animal habits caused by the long-term influence of the environment, changes in the organism, such as excessive or too few use of certain organs to make them developed or degraded, and such changes can be inherited to future generations . For example, the giraffe's neck gradually grows due to changes in the environment and eats leaves on tall trees; mole eyes lose their eyesight because of ancestors' caves in dark caves. He said: "Everything is due to the long-term environmental impact, or the relationship between long-term use and long-term disuse, and the changes that individual creatures receivewhether they are male and female, or only those who produce new individuals. Can be passed on to future generations by natural forces. " ^[1]

1. Paramecium genetic experiment

Paramecium has a specific protein on its surface, and there can only be one type of specific protein. If the growth temperature of Paramecium is increased for several hours, and then the original temperature is restored, the specific protein can be converted into another form of the specific protein, and the new form of the specific protein can be inherited from generation to generation.

2. Bacillus subtilis genetic experiment

Bacillus subtilis relies on the cell wall to maintain its rod-like traits. When the cell wall is removed, under specific growth conditions, they will become wall-free bacterial bodies of various sizes and shapes. These wall-free bacterial bodies not only can Continue to reproduce, and their offspring are also cell wall-free.

3. Blue-green algae genetic experiment

Blue-green algae is a plant with biological nitrogen fixation ability. Its nitrogenase is composed of three genes: H, D, and K. Under normal circumstances, the D and H genes are close together, and the K gene is separated by a DNA (deoxyribonucleic acid) sequence consisting of 12,000 nucleotides. When the environment has no nitrogen source, these 12,000 nucleotides on its DNA will be cut off, "making the K, D, and H genes close together to form an independent operon. At this time, the nitrogen-fixing enzyme will begin to show vigor. The biological nitrogen-fixing 'machine' in the blue-green algae just started to operate. "

There are also similar experiments such as the genetic test of conjoined Siamese, the genetic experiment of Euglena phycochrome, and the genetic experiment of phage transmission. The above experiments have confirmed that acquired can be inherited from different angles. But the meaning (at least I think so) is not particularly significant. Of great significance are the following experiments:

Keynes experiment

In 1988 (before), Keynes, a molecular biologist, designed an amazing experiment. They chose a defective strain of E. coli that was defective in the gene that breaks down lactose and could not use lactose in the environment as food. Other types of sugar had to be supplied for them to grow and reproduce normally. Every generation of this E. coli has the same flaws. However, these bacteria also have the potential to restore genes' ability to break down lactose through accidental mutations, but at a low frequency. Keynes divided E. coli into several groups, and put them into bacterial media containing only lactose and no other sugars. The storage time was: same day, one day later, two days later, three days later ... 246a

A miracle appeared. The bacteria were dying at the beginning. As time passed, a small number of bacteria became active, indicating that some of these bacteria had mutated, and then more bacteria began to become active. Comparing the various media, the earlier it came in contact with lactose, the 246a mutation. The more bacteria appear.

5. Natural genetic engineering of bacteria

In 1994, other molecular biologists still experimented with E. coli in lactose medium. This time, E. coli did not have a defective gene that breaks down lactose, but lost it at all. But it still has room for self-rescue. On its plasmid, there is a gene that uses lactose. Unfortunately, there is an extra base in the middle of the gene on the plasmid, leaving the gene essentially ineffective.

If the bacteria can delete this base, it will survive. But deleting the base gene often has a negative effect (equivalent to a genetic mutation), affects the physiological function of the bacteria, and even causes death. Therefore, where deletion occurs, bacteria often call specialized protein tools to try to fill them up. The deletion is basically random, and the repair is also random, with a strong chance. In other words, we must try to delete the excess bases and try our best to prevent the bacterial repair system from replenishing the deleted bases. Both are "too difficult." "But bacteria really do. They use their natural genetic engineering technology to start a complex genetic recombination process that involves a series of recombinant proteins, eventually successfully deleting that extra base, and then at that site. Reduce the efficiency of the repair work, or not repair it, and you have a normal gene that can use lactose! "The entire bacteria survived.

6. "Mutual Rescue Information" Enhances Bacterial Resistance

Bacteria are usually killed by targeted antibiotics, but they are used more often, and individual bacteria will mutate to obtain resistance, and this part of the bacteria will multiply, replacing the original non-resistant bacteria.

But "Science and Technology Daily" reported the fact that the resistance of bacteria is related to the "teaching" of other bacteria. "Mathematical physicist Alan Parsons and biologist Richard Sear cultivated two bacterial communities in the laboratory, one in ordinary nutrients and one in antibiotic-containing food In the middle, the two communities were separated by a plastic barrier. During the experiment, scientists observed that initially, the bacteria exposed to antibiotics began to die, but after a few hours, these dying bacteria gradually regained their vitality. They found that this This phenomenon occurs only when air is in circulation, and when the two communities are completely isolated (the original text may refer to moving or separated by a tighter barrier), the bacteria exposed to antibiotics will completely die. For this reason they It is speculated that these bacteria may be using molecules emitted into the air to communicate with each other. "

7. Bailey Haier's research findings

In September 2002, the American Journal of Molecular Evolution published the discovery of Barry Hall, a molecular evolutionist at Rockefeller University. "Beli Haier and his colleagues reconstructed the evolutionary history of this gene family by comparing the sequences of the OXA -lactamase gene in different strains." The OXA -lactamase gene is one such gene that Antibiotics that eliminate Salmonella and Staphylococcus are resistant. "The researchers found that these genes jumped onto the plasmid in three separate occasions. Using the number of genetic variations that occur naturally over time to estimate when these three events occurred, the researchers determined that two of the transfers occurred in Millions of years ago. " ^[2]

Acquiredness is the acquired mutation, which is the abbreviation of acquired acquired traits produced by organisms under the influence of the environment. Can acquisition be inherited? This is one of the focuses of debate between the two factions in genetics. ·

As early as 1809, French biologist Lamarck in his book "Zooology Philosophy" affirmed that: under the influence of living conditions and organ exercise, the new traits obtained by the liver can be inherited. Later in Darwin's "The Origin of Species," he also acknowledged that acquisition can be inherited. The Michurin School emphasizes that heritability can be inherited. For example, in the pig industry, under artificial conditions, many excellent breeds have been formed, which have acquired new traits that their ancestors have not experienced. Sex cannot be inherited, and how these facts will be explained.

According to the Morgan School: acquisition is not inherited. Weisman once conducted 22 generations of rat tail-breaking experiments. As a result, he still had tails in each generation. Therefore, he denied that inheritance can be inherited and created the "germplasm theory." Changes can occur under environmental influences, but cannot be passed on to future generations.

The Michurin School believes that: Weisman's tail-breaking test of mice is not a mutation produced by the organism, but an injury caused by external forces. Organisms are not heritable to mechanical injuries and disabilities. For example, the pigs were numbered and recorded, and a few notches were cut in their ears. Although their parents have been cut, the offspring are still intact. The emergence of the obtained animal is the result of the assimilation of new environmental conditions during the growth and development of the organism. If the acquired new traits can affect the formation of sex cells, then such new traits will be inherited. Due to the strong genetic conservation of sex cells in organisms, the influence of new traits on sex cells can be weakened. Therefore, the size of the organism's mutations affects the depth of the metabolic process and determines the probability of inheritance to future generations.

The Morgan School replaces "germplasm" with genes and genetic material, and believes that genetic material is constant, and only genetic mutations can produce new mutations. Genetic mutations include two aspects: chromosomal aberrations and genetic mutations (ie point mutations). Chromosomal aberrations can be observed under a microscope, while point mutations are chemical changes. Narrow mutations generally refer to genetic mutations (ie point mutations). How does hornless cattle occur? They believe that cattle have horns or no horns because certain genetic factors sometimes change from one generation to another. And it is known that the proportion of hornless calves in horned herds is about one in 20,000. The production of hornless parents by horned calves is the result of mutations in genetic factors of the horned parents. ^[3]