JP4332273B2 - Method for producing plant not containing carbon isotope 14C, method for producing animal not containing carbon isotope 14C, and plant and animal not containing carbon isotope 14C produced by these production methods - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
INDUSTRIAL APPLICABILITY The present invention provides a method for producing experimental animals and plants in which the concentration of the radioactive isotope ¹⁴ C among the isotopes of carbon, which is the main element constituting the animals and plants, is extremely reduced, and is produced by such a production method. It relates to animals and plants.
[0002]
[Prior art]
Carbon 14 is an isotope of stable carbon ^{12 C, 13 C (14 C} ) is a half-life 5730 years beta ^- a radioactive isotope decay, isotopically slide into decay over time from being generated is there. On the other hand, the abundance of carbon 14 present in the earth's atmosphere is generated at a relatively constant generation rate by cosmic rays, and therefore maintains a substantially constant value (equilibrium state) except for short-term fluctuations caused by nuclear tests. . As a result, the carbon isotope ratio of carbon dioxide in the modern earth atmosphere is ¹² C: ¹³ C: ¹⁴ C = 0.899: 0.011: 1.2 × 10 ⁻¹² , that is, ¹⁴ C / ¹² C = 1.2 × 10 ^−12. The almost constant value is maintained.
[0003]
For this reason, the isotope ratio of carbon constituting a plant (including vegetables, fruits, cereals, etc., which grows naturally in the natural environment, the same as in the present specification) is referred to as a modern carbon isotope ratio. The ratio is substantially the same, and the isotope ratio of carbon constituting the living body of an animal that grows using such a plant as food also has a value almost the same as the above ratio. In other words, the carbon isotope ratio of carbon, which is the main element constituting the living organisms of animals and plants that currently live on the ground, is composed of almost the same ratio as the modern carbon isotope ratio.
[0004]
When conducting research such as investigation of drug efficacy by examining movement in a subject such as pharmaceuticals and agricultural chemicals (hereinafter referred to as “medicine etc.”), these pharmaceuticals are used using the isotope ratio of modern carbon as described above. etc. labeled by incorporating carbon 14 ⁽¹⁴ C), the tracer experiment to investigate the movement of the medicines and the like are performed by tracking by introducing this way the labeled pharmaceuticals, etc. to the subject. For example, by introducing a labeled drug into the body of a laboratory animal such as a rat or mouse and measuring the ¹⁴ C concentration in an organ or tissue such as a rat after a certain period of time, the movement of the drug in the body Tracer experiments that track (diffusion and aggregation) are widely used in pharmaceutical research.
[0005]
[Problems to be solved by the invention]
However, in order to effectively detect the movement of the tracer ( ¹⁴ C) in the tissue, that is, the change in the carbon isotope ratio in the tissue, by the tracer experiment using carbon 14 as described above, the tracer ¹⁴ C The carbon isotope ratio needs to be at least 100 to 1000 times the above-mentioned modern carbon isotope ratio, and in the case where the tracer diffuses in the living body and the concentration decreases, it is necessary to introduce a larger amount of tracer. There is.
[0006]
For the above reasons, it has been necessary to handle radioisotopes that are at least two orders of magnitude higher than normal radiation levels in pharmaceutical research and research. However, there are problems associated with the handling of radiation in all aspects, such as the development of areas for breeding and cultivation of experimental animals and plants, the management of exposure doses, the release into the environment after the experiment and the problem of contamination.
[0007]
The present invention has been made in view of the above problems, and provides an experimental animal or plant capable of performing a tracer experiment with a medicine containing carbon having a modern carbon isotope ratio without special handling for radiation. The purpose is to do.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention, an artificial atmosphere constituted by mixing carbon dioxide consisting of dead carbon not containing carbon isotope ¹⁴ C and other gas components other than carbon dioxide constituting the atmosphere, carbon by cultivating plants using the artificial water without the isotope ¹⁴ C, producing a plant that does not contain carbon isotope ¹⁴ C.
[0009]
As is well known, plants including fruits and cereals photosynthesize water absorbed from fine roots and carbon dioxide absorbed from the leaf surface by the light energy of sunlight, and assimilate the carbon to organic matter (cellulose (C ₆ H It grows by synthesizing ₁₀ O ₅ ) _n ). In the above plant production method, the plant is composed of an artificial atmosphere constituted by mixing carbon dioxide composed of dead carbon not containing carbon isotope ¹⁴ C and other gas components other than carbon dioxide constituting the atmosphere, carbon It is cultivated using artificial water that does not contain isotope ¹⁴ C. For this reason, cultivated and grown plants are synthesized with organic matter that does not contain ¹⁴ C, and the value of ¹⁴ C / ¹² C is higher than that of modern carbon isotopes compared to plants cultivated in a natural environment. Plants that are as low as digits can be produced. In this specification, “ ¹⁴ C is not included” means a state in which the constituent ratio of ¹⁴ C is extremely reduced compared to the isotope ratio of modern carbon, and specifically, the value of ¹⁴ C / ¹² C. Is reduced by about two orders of magnitude or more.
[0010]
When a tracer experiment is performed using such a plant as a specimen, the ¹⁴ C concentration in the background plant tissue is low, so the pesticide produced in the normal production process (a pesticide containing ¹⁴ C with a modern carbon isotope ratio) Even if is used, the isotope ratio (level difference) of ¹⁴ C, which is a tracer, can be ensured by two digits or more, and thereby, a tracer experiment can be easily performed in a general environment. Therefore, it is not necessary to use a pesticide containing a high level of tracer in a test for pesticides and the like, and it is possible to provide a laboratory plant that does not require special handling for radiation. Moreover, the food for breeding the laboratory animal which hardly contains ¹⁴ C mentioned later can be provided.
[0011]
In order to achieve the above-mentioned object, the present invention uses a plant that does not contain carbon isotope ¹⁴ C produced by the above method as a bait, and raises animals (referred to as animals other than humans) to raise carbon isotope ¹⁴ C. Produce animals that do not contain Animals grow by taking orally ingested food as a source of carbon. Therefore, an animal bred using a ^14C- free plant produced by the above method as a bait can be composed of carbon containing almost no ^{14C in} somatic cells. It is possible to produce animals whose ¹⁴ C / ¹² C value is many orders of magnitude lower than the isotope ratio of modern carbon compared to the animals used as food.
[0012]
When performing tracer experiment as the subject of such animal, for ¹⁴ C concentration in the biological tissue as a background is low, the normal isotopic tracer serving ¹⁴ C be used by pharmaceutical production in the production process Two or more digits can be secured, so that the test can be easily performed in a general environment. Therefore, it is not necessary to use a medicine containing a high level of tracer in a medicine test, and it is possible to provide a laboratory animal that does not require special handling for radiation.
[0013]
In addition, when plants that are taken orally by animals contain a lot of water like vegetables and fruits and do not need other hydration, it is not necessary to give water separately. When it is necessary to ingest the body from other sources, it is preferable to provide artificial water not containing ¹⁴ C as in the case of the above-mentioned plant.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described. First, a method for producing a plant that does not contain the carbon isotope ¹⁴ C (the ¹⁴ C content is extremely reduced) will be described. Aquatic plants such as chlorella and land plants such as vegetables, fruits, and grains absorb water and carbon dioxide in the atmosphere (or dissolved from the atmosphere into the water) and assimilate the carbon by photosynthesis, It grows by synthesizing organic substances such as cellulose. For this reason, the carbon isotope ratio in the organic matter constituting the plant almost reflects the isotope ratio of water in the growth environment and carbon in the carbon dioxide. In the present invention, ¹⁴ C is excluded from water and air in the plant cultivation environment, and plants are cultivated using artificial air and artificial water not containing ¹⁴ C.
[0015]
The artificial atmosphere is configured by mixing carbon dioxide composed of dead carbon not containing ¹⁴ C and other gas components other than carbon dioxide constituting the atmosphere. Dead carbon is a carbon isotope that is composed of stable isotopes ¹² C and ¹³ C, most of which is destroyed due to the progress of β ^- decay of ¹⁴ C, which is a radioactive isotope. In general, it ^means carbon with an isotope ratio of ¹⁴ C / ¹² C of the order of 10 ^-16 or less. Such carbon is old carbon with an elapsed time of several hundred thousand years or more since it is generated. For example, it is used for carbon in so-called fossil fuels such as oil, coal, natural gas, and rocks such as limestone. The carbon contained is dead carbon.
[0016]
By refining these fossil fuels and limestone as raw materials, carbon dioxide composed of dead carbon can be easily obtained. For example, carbon dioxide composed of dead carbon can be obtained by mixing fossil fuel as described above with oxygen and burning it, or by burning limestone or reacting limestone with an acid such as hydrochloric acid. Can do.
[0017]
An artificial atmosphere is created by mixing the obtained carbon dioxide composed of dead carbon and other gas components other than carbon dioxide constituting the earth atmosphere. The purification and mixing method of gaseous components other than carbon dioxide is not particularly specified. For example, it consists of dead carbon after carbon dioxide is physically or chemically adsorbed and removed from the ground air by a catalyst or adsorption device. An artificial atmosphere can be created by a method of mixing carbon dioxide in the same ratio, a method of mixing separately purified nitrogen gas, oxygen gas, and carbon dioxide composed of dead carbon at a ratio substantially equal to the composition of the ground air. In addition, when synthesizing the artificial atmosphere from each single gas, it is possible to configure by excluding composition components (for example, ozone, nitric oxide gas, etc.) that hardly contribute to plant growth among components constituting the atmosphere. it can.
[0018]
Artificial water not containing ¹⁴ C can also be obtained by various production methods. For example, it is common to produce highly pure water by ion exchange of groundwater or tap water using ion exchange resin, and carbon dissolved in water is removed by such a method. Artificial water can be easily obtained. The obtained artificial water is preferably stored and managed so that modern carbon does not dissolve, or purified and used in an artificial atmosphere.
[0019]
Plant cultivation is performed using the artificial air and artificial water not containing ¹⁴ C thus obtained. As described above, moisture, carbon dioxide, and light are essential requirements for plant growth, and plants will not grow smoothly if they are missing. Therefore, as the plant cultivation environment, the artificial atmosphere is kept airtight, or the general atmosphere does not enter from the outside so that the artificial atmosphere overflows, and the sunlight can be introduced directly or indirectly To do. For example, sunlight is introduced into a glass house filled with artificial atmosphere or a factory building filled with artificial atmosphere using an optical fiber. And the target plant is cultivated in the floor environment according to plants, such as hydroponics and artificial soil which does not contain ^14C .
[0020]
In addition, for other conditions such as sunshine conditions, temperature and humidity management, and fertilizers used for cultivation of plants, in principle, conditions suitable for the target plant can be adopted. For those that may be absorbed by the plant, it is necessary to use a member that does not contain ¹⁴ C. For example, it is necessary to use artificial water as the moisture to keep humidity constant, and the flooring materials etc. that are hydroponically cultivated are based on dead carbon (fossil fuel) that does not bleed out ¹⁴ C. It is preferable to use a material or a metal material.
[0021]
Cultivated plants (vegetables, fruits, cereals, etc.) can reduce the abundance of ¹⁴ C in the carbon isotope ratio compared to plants cultivated in a general atmospheric environment. By carrying out over several generations, a plant almost free of ¹⁴ C can be obtained.
[0022]
Next, experimental animals such as experimental rats, research mice, and rhesus monkeys are bred using the plant obtained as described above and containing almost no ¹⁴ C. As is apparent from what has been described so far, the environment for breeding, the food to be fed, and the like are constituted by peripheral members that do not contain ¹⁴ C for those that may be ingested and accumulated in the body of the experimental animal. In other words, the plant environment almost free of ¹⁴ C obtained by the above cultivation method is used as a feed, and a breeding environment where artificial water is supplied as necessary is a basic condition, and other breeding environments are set to be suitable for growing laboratory animals. I do. At this time, other necessary nutrients and components that are likely to be ingested or accumulated by laboratory animals such as cages to be kept or penetrated into the body from the lungs, skin, etc. are composed of materials that do not contain ^14C. To do.
[0023]
Animals reared and raised can reduce the abundance ratio of ¹⁴ C in the carbon isotope ratio compared to animals reared in a general environment. By carrying out such rearing process for several generations of experimental animals, experimental animals containing almost no ¹⁴ C can be obtained.
[0024]
The experimental animals and plants cultivated or bred by the above method were cultivated in an environment where the influence of modern carbon was not completely blocked from the viewpoint of production economy, and the contamination by ¹⁴ C was completely eliminated. Although it is difficult to do so, the ¹⁴ C constituent ratio in somatic cells is greatly reduced, and the value of ¹⁴ C / ¹² C is compared with the ratio of modern carbon isotopes compared to animals and plants cultivated and raised in natural environments. It is possible to produce relatively low-cost and easy-to-produce experimental animals and plants that are extremely low (for example, this value is about 10 ⁻¹⁴ ).
[0025]
When conducting tracer experiments using the above animals and plants as subjects, the ¹⁴ C concentration in the background tissue is low. Therefore, even if a pharmaceutical produced in the normal production process is used, the ¹⁴ C isotope ratio is 2 digits. Thus, a tracer test (for example, a tissue analysis using an accelerator) can be easily performed in a general environment. Therefore, it is not necessary to use a medicine containing a high level of tracer in a medicine test, and it is possible to provide a laboratory animal that does not require special handling for radiation.
[0026]
【The invention's effect】
As described above, in the present invention, an artificial atmosphere constituted by mixing carbon dioxide composed of dead carbon not containing carbon isotope ¹⁴ C and other gas components other than carbon dioxide constituting the atmosphere, carbon to grow plants using the artificial water without the isotope ¹⁴ C, plants grown cultivated become be synthesized by organic substances not containing a ¹⁴ C, as compared to plants grown in a natural environment ¹⁴ It is possible to produce plants having a C / ¹² C value significantly lower than the isotope ratio of modern carbon. Therefore, it is not necessary to use a pesticide containing a high level of tracer in a test for pesticides and the like, and it is possible to provide a laboratory plant that does not require special handling for radiation. Moreover, the food for breeding the laboratory animal which hardly contains ¹⁴ C can be provided.
[0027]
In the present invention, since the animals are bred using the plant containing no carbon isotope ¹⁴ C produced by the above method as a food, the bred animals are composed of carbon containing almost no ¹⁴ C in somatic cells. In other words, it is possible to produce an animal having a value of ¹⁴ C / ¹² C significantly lower than that of modern carbon isotopes compared to animals bred using plants cultivated in a natural environment. Therefore, it is not necessary to use a medicine containing a high level of tracer in a medicine test, and it is possible to provide a laboratory animal that does not require special handling for radiation.

Claims (4)

An artificial atmosphere constituted by mixing carbon dioxide composed of dead carbon not containing carbon isotope ¹⁴ C and other gas components other than carbon dioxide constituting the atmosphere;
By cultivating plants with artificial water that does not contain carbon isotope ¹⁴ C,
A method for producing a plant free of carbon isotope ¹⁴ C. An artificial atmosphere constituted by mixing carbon dioxide composed of dead carbon not containing carbon isotope ¹⁴ C and other gas components other than carbon dioxide constituting the atmosphere;
Plants containing no carbon isotope ¹⁴ C, which is produced using the artificial water containing no carbon isotope ¹⁴ C. By breeding animals (except humans ) using a plant that does not contain carbon isotope ¹⁴ C according to claim 2 as a bait,
A method for producing animals (except humans ) that do not contain carbon isotope ¹⁴ C. An animal (excluding humans ) that does not contain carbon isotope ¹⁴ C produced by feeding a plant that does not contain carbon isotope ¹⁴ C according to claim 2.