Animal fixation device and animal fixation method

In order to provide an animal fixation device and an animal fixation method which are able to euthanize and fix the animal instantaneously and steadily, a columnar cage in which animal is arranged, a rotation mechanism configured to rotate the cage, an euthanizing gas supply mechanism configured to supply euthanizing gas into the cage, and a solid refrigerant supply mechanism configured to supply a solid refrigerant into the cage are provided. The euthanizing gas supply mechanism includes a gas manifold for euthanizing which is connected to the cage so that the euthanizing gas flows on an inner wall of the cage along a circumferential direction. The solid refrigerant supply mechanism includes a solid refrigerant supply line which is connected to the cage so as to be able to supply the solid refrigerant during rotation of the cage.

INCORPORATION BY REFERENCE

This patent application claims a priority on convention based on Japanese Patent Application No. 2009-046745. The disclosure thereof is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an animal biological fixation device and an animal fixation method.

BACKGROUND ART

An experiment using an animal is carried out in order to develop a novel medicine. An experimental animal is analyzed after being reared under a predetermined experimental environment. After rearing under the experimental environment, a long time may elapse before analysis. In addition, after the rearing and before the analysis, the animal may be placed under an environment different from the experimental environment. By the elapse of time and the placement under the different environment, a condition of the animal may change from a state under the experimental environment.

A technique for euthanizing and biologically fixing the animal to keep a condition of the animal to be in a state under the experimental environment is known. As such the technique, euthanasia/fixation means is described in “Summary of Report, “Feasibility Study for Development of Reentry Bioscience Small Experimental Satellite System”, The Mechanical Social Systems Foundation, March, 2008” (document 1).

FIG. 1is a schematic view showing the euthanasia/fixation means described in document 1. The euthanasia/fixation means is mounted on a reentry experimental satellite shuttling between the ground and the space. The euthanasia/fixation means includes a cage106, a liquid nitrogen tank101, and a carbon dioxide tank102. The cage106is provided for rearing a small animal and is covered with a heat insulating cooling mechanism103. The carbon dioxide tank102is provided for euthanizing the small animal. The liquid nitrogen tank101is provided for fixing the small animal. In addition, an exhaust line105to which a relief valve104is attached is provided to the cage106. After the reentry experimental satellite has been launched to the space, the small animal in the cage106is reared under a microgravity environment that is the experimental environment. Before the reentry, the carbon dioxide gas is supplied from the carbon dioxide tank102into the cage106. In this manner, the small animal is suffocated and euthanized. In addition, cooled nitrogen gas is supplied from the liquid nitrogen tank101into the cage106via a temperature adjuster. In this manner, the small animal is cooled to be biologically fixed. The small animal is placed under a hyper gravity at the reentry to the ground. By placement under the hyper gravity, a condition of the small animal may change from a state where the animal was reared under the microgravity environment. However, by using the euthanasia/fixation means described in document 1, the state under the microgravity environment can be maintained because the small animal is fixed.

DISCLOSURE OF INVENTION

In order to biologically fix the animal with maintaining the state under the experimental environment, it is important to carry out euthanasia and fixation instantaneously and steadily. However, the animal before the euthanasia is alive, and accordingly it is expected that the animal actively moves around. Hence, it is difficult to instantaneously euthanize the animal. Additionally, in the fixation process, after starting the fixation process and before the animal is actually fixed, a long time may elapse depending on a means for fixation, and thus there is a possibility that the condition under the experimental environment cannot be maintained.

Consequently, a purpose of the present invention is to provide an animal fixation device and an animal fixation method which are able to euthanize and fix the animal instantaneously and steadily.

In an aspect of the present invention, an animal fixation device includes: a columnar cage in which animal is arranged; a rotation mechanism configured to rotate the cage; an euthanizing gas supply mechanism configured to supply euthanizing gas into the cage; and a solid refrigerant supply mechanism configured to supply a solid refrigerant into the cage. The euthanizing gas supply mechanism includes a gas manifold for euthanizing which is connected to the cage so that the euthanizing gas flows on an inner wall of the cage along a circumferential direction. The solid refrigerant supply mechanism includes a solid refrigerant supply line which is connected to the cage so as to supply the solid refrigerant during rotation of the cage.

According to this invention, the euthanizing gas is supplied to flow on the inner wall of the cage along a circumferential direction. As the results, after starting supply of the euthanizing gas, inside of the cage is rapidly filled every inch with the euthanizing gas. The animal can be instantaneously and steadily euthanized, independent of his position. Additionally, the solid refrigerant supply mechanism supplies the solid refrigerant during rotation of the cage. If the cage is fixed, the solid refrigerant may be accumulated near a reception opening of the cage. The reception opening may be closed, and sufficient amount of the solid refrigerant may not be supplied. On the other hand, according to the present invention, accumulation of the solid refrigerant is prevented by rotation of the cage. As the result, sufficient amount of the solid refrigerant can be supplied into the cage, and the animal can be cooled to be instantaneously fixed.

In another aspect of the present invention, an animal fixation method includes: supplying euthanizing gas into a columnar cage, in which an animal is arranged, so that said euthanizing gas flows on an inner wall of said cage along a circumferential direction; rotating said cage after said supplying euthanizing gas; and supplying a solid refrigerant into said cage during rotation of said cage.

According to the present invention, an animal fixation device and an animal fixation method can be provided, which are able to euthanize and fix the animal instantaneously and steadily.

DESCRIPTION OF EMBODIMENTS

Referring to drawings, an embodiment of the present invention will be explained below.FIG. 2is a schematic diagram showing an animal fixation system11according to the present embodiment.

As shown inFIG. 2, the animal fixation system11is mounted in an experimental satellite10. The experimental satellite10is equipment launched from the ground to the space and returns from the space to the ground.

The animal fixation system11is a device for rearing an animal (for example, a mouse) under a microgravity environment in the space and biologically fixing the animal before reentry. The animal fixation system11includes an animal fixation device1and a control device9for controlling the animal fixation device1. The control device9is exemplified by a computer, and operates in accordance with a preliminarily installed program.

The animal fixation device1includes a cage2, a carbon dioxide gas supply mechanism6, a ventilation mechanism5, a dry ice supply mechanism4, a rotation mechanism3, and an exhaust line7.

The cage2is a chassis for rearing the animal, and is in a cylindrical shape.

The carbon dioxide gas supply mechanism6(a euthanizing gas supply mechanism) is provided for euthanizing the animal. The carbon dioxide gas supply mechanism6supplies the carbon dioxide gas into the cage2as euthanizing gas.

The dry ice supply mechanism4(a solid refrigerant supply mechanism) is provided for fixing the animal. The dry ice supply mechanism4supplies dry ice into the cage2as a solid refrigerant.

The rotation mechanism3is provided for rotating the cage2while the dry ice is supplied.

The ventilation mechanism5is provided for ventilating inside of the cage2when the animal is reared.

The exhaust line7is provided for keeping an internal pressure of the cage2constant while the carbon dioxide gas is supplied. The exhaust line7connects the cage2to the outside of the experimental satellite10. A relief valve8is provided in the exhaust line7. When the carbon dioxide gas is supplied, the relief valve8is opened to keep the internal pressure of the cage2. In this manner, the gas in the cage2is exhausted to the outside of the satellite and the pressure in the cage2is kept constant.

Subsequently, a configuration of the animal fixation device1will be explained in detail. The state (a) ofFIG. 3shows a schematic diagram of the cage2. In addition, (b) ofFIG. 3is a diagram seeing the case2from a direction A shown in (a) ofFIG. 3, and (c) ofFIG. 3is a diagram seeing the cage2from a direction B shown in (a) ofFIG. 3.

As shown in (a) to (c) ofFIG. 3, the cage2is in a cylindrical shape. The inside of the cage2is a living space for the animal. The cage2is connected to the rotation mechanism3. The rotation mechanism3is configured so as to rotate the cage2around a central axis c.

As shown in (a) ofFIG. 3, the carbon dioxide gas supply mechanism6, the ventilation mechanism5, and the dry ice supply mechanism4are connected to the cage2.

The carbon dioxide gas supply mechanism6will be explained. As shown in (c) ofFIG. 3, the carbon dioxide gas supply mechanism6includes a GCO2manifold61and a GCO2port62. The GCO2port62is connected to a carbon dioxide tank not shown in the drawing. The GCO2manifold61is connected to the GCO2port62at one end, and is connected to the cage2at the other end. When the GCO2port62is opened, the carbon dioxide gas is supplied from the carbon dioxide tank into the cage2via the GCO2manifold61. Here, the GCO2manifold61is connected to the cage2so that the carbon dioxide gas flows on an internal wall of the cage2along a circumferential direction. When the carbon dioxide gas flows along the circumferential direction, it is possible to distribute the carbon dioxide gas in every corner of the cage2.

In addition, as shown in (b) and (c) ofFIG. 3, the GCO2manifold61is branched into a plurality of lines (four in the present embodiment). The pluralities of lines are arranged along a longitudinal direction of the cage2. And, respective tip end portions of the plurality of the lines are connected to the cage2. In this configuration, the carbon dioxide gas is accordingly supplied from a plurality of portions arranged along the longitudinal direction of the cage2into the cage2. As a result, the carbon dioxide gas can be evenly distributed also in the longitudinal direction of the cage2.

Subsequently, the ventilation mechanism5will be explained. As shown in (a) ofFIG. 3, the ventilation mechanism5includes a ventilation line53, a ventilation port51, and a ventilation port shutter52. The ventilation line53is connected to the cage2at one end and connected to the ventilation port51at the other end. As shown in (c) ofFIG. 3, a mesh lid is arranged in the ventilation port51. The ventilation port51prevents an animal from escaping to outside of the cage2, and connects a cabin of the experimental satellite10to the ventilation line53. The ventilation port shutter52is provided for opening and closing the ventilation port51. At the rearing of the animal, the ventilation port shutter52is arranged on a position other than the ventilation port51, and the inside of the cage2connects to the cabin. Accordingly, the inside of the cage2is ventilated. On the other hand, during performance of an euthanasia process and a fixation process, the ventilation port shutter52covers the ventilation port51. Thus, the inside of the cage2is isolated from the cabin.

As shown in (c) ofFIG. 3, the exhaust line7is connected to the middle of the ventilation line53. As described above, the ventilation line7is connected to the outside of the satellite via the relief valve8.

Next, the dry ice supply mechanism4will be explained. As shown in (a) ofFIG. 3, the dry ice supply mechanism4includes a dry ice supply line41, a compressed spring42, and a plate43. The inside of the dry ice supply line41is filled with dry ice. The dry ice supply line41is connected to the cage2at a tip end portion. The compressed spring42is attached to a base end portion of the dry ice supply line41. The plate43is attached to a tip end portion of the compressed spring42. In this configuration, the dry ice filled in the dry ice supply line41is pressed to a cage2side by the plate43and the compressed spring42.

Here, the cage2will be explained in detail. As shown in (a) ofFIG. 3, the cage2has a double structure of an outer cage23and an inner cage24. In a part of (c) ofFIG. 3, a shape of the inner cage24is shown by a dotted line. As shown in (c) ofFIG. 3, in the inner cage24, a plurality of the dry ice reception openings21for receiving the dry ice are provided along a circumferential direction. In addition, a dry ice reception opening shutter22for opening and closing the plurality of the dry ice reception openings21is provided in the cage2. The dry ice reception opening shutter22is configured so as to open a plurality of the dry ice reception openings21during supply of the dry ice and to close the plurality of the dry ice reception openings21during other operations.

FIG. 4is a schematic diagram for explaining the configuration of the cage2in more detail. As described above, the cage2has a double structure of the outer cage23and the inner cage24. The outer cage23is in a cylindrical shape, and both of the end surfaces are closed. On the other hand, the inner cage23is in a cylindrical shape, and is inserted in the outer cage23so as to cover an inner side wall of the outer cage23. Here, the outer cage23is fixed to the dry ice supply line41, the ventilation line53, and the GCO2manifold61. On the other hand, the inner cage24is a portion rotated by the rotation mechanism3. That is, the rotation mechanism3is configured so as to rotate only the inner cage24without rotating the outer cage23.

The outer cage23is made of a material having heat insulation properties. The outer cage23has a dry ice supply line connection opening29, a ventilation line connection opening28, and a GCO2supply line connection opening27. The outer cage23is connected to the dry ice supply line41at the dry ice supply line connection opening29. In addition, the outer cage23is connected to the ventilation line53at the ventilation line connection opening28. Moreover, the outer cage23is connected to the GCO2manifold61at the GCO2supply line connection opening27.

Meanwhile, as described above, the plurality of the dry ice reception openings21are provided in the inner cage24. The plurality of the dry ice reception openings21are provided along the circumferential direction at a position corresponding to the dry ice supply line connection opening29. During the supply of the dry ice, the plurality of the dry ice reception openings21are positioned in sequence on the dry ice supply line connection opening29, because the inner cage24is rotated. As the result, the dry ice is supplied to the cage2in sequence from the plurality of the dry ice reception openings21. As the result, the dry ice is prevented from filling the respective dry ice reception openings21, and accordingly a sufficient amount of the dry ice can be input into the cage2.

In addition, the inner cage24includes, a ventilation opening26provided on a position corresponding to the ventilation line53, and a GCO2reception opening25provided on a position corresponding to the GCO2manifold61. The inside of the inner cage24is connected to the ventilation line53via the ventilation opening26. Moreover, the carbon dioxide gas is supplied from the GCO2manifold via the GCO2reception opening25.

Subsequently, an operation method of the animal fixation device according to the present embodiment will be explained.FIG. 5is a flowchart showing the operation method of the animal fixation device.

Step S1: Mounting on the Experimental Satellite (Rocket)

At first, the animal is put into the cage2, and the animal fixation system1is mounted on the experimental satellite10.

Step S2: Launch

Next, the experimental satellite10is launched from the ground to the space. The experimental satellite10is put into an orbit in the space, and is placed under a microgravity environment. The animal in the cage2is reared under the microgravity environment. On this occasion, the ventilation port51in the ventilation mechanism5is opened by the control device9. In addition, the relief valve8provided in the exhaust line7is closed. Moreover, the plurality of the dry ice reception opening21in the inner cage24are closed by the dry ice supply opening shutter22. Additionally, the GCO2supply port62is also closed.

Step S3: Supplying Euthanasia Gas

When the rearing under the microgravity environment is complete, the euthanasia process and the fixation process are carried out by the control device9. In particular, the ventilation port51is firstly closed by the ventilation port shutter52. Then, the GCO2supply port62is opened. As the result, the carbon dioxide gas is supplied from the carbon dioxide tank into the cage2. Hence, the animal is suffocated and euthanized. On this occasion, as described above, the carbon dioxide gas flows along a circumferential direction in the cage2. Accordingly, the carbon dioxide gas is distributed rapidly in the cage2. As the result, the animal can be euthanized steadily and instantaneously.

In addition, during the supply of the carbon dioxide gas, the relief valve8provided in the exhaust line7is opened as needed. As the result, the excess gas in the cage2is exhausted to the outside of the satellite. As the result, an internal pressure of the cage2is prevented from extraordinarily rising.

Step S4: Cage Rotation

After euthanasia of the animal, the cage2is rotated by the rotation mechanism3. In particular, only the inner cage24of the cage24is rotated.

The plurality of the dry ice reception openings21provided on the inner cage24is opened when the cage2is rotated. In this manner, the dry ice is supplied from the dry ice supply mechanism4into the cage2via the respective dry ice reception openings21. On this occasion, as described above, the plurality of the dry ice reception openings21receive the dry ice in sequence. Accordingly, the filling by the dry ice can be avoided, and thus a sufficient amount of the dry ice can be put into the cage2. In this manner, the euthanized animal is immediately frozen (biologically fixed).

After the fixation of the animal, the control device9seals the cage2. That is, the plurality of the dry ice reception openings21are closed by the dry ice reception opening shutter22, and the GCO2supply port is closed. In addition, the ventilation port51is also maintained to be in a closed state. In this state, the experimental satellite10returns to the ground. On this occasion, the animal is put under an hyper gravity environment. However, since the animal is fixed, the hyper gravity does not affect a biological condition of the animal.

After the returning to the ground, the animal is retrieved from the inside of the cage2and is analyzed. On this occasion, since the animal maintains a condition in the rearing under the microgravity environment, influence given to the animal by the microgravity environment can be known.

As described above, according to the present embodiment, the euthanasia process and the fixation process can be automatically carried out.

Additionally, in the present embodiment, since the carbon dioxide gas is supplied so as to flow on the inner wall of the cage2along the circumferential direction, the carbon dioxide gas can be rapidly distributed entirely in the cage2. Thus, the animal can be euthanized and fixed instantaneously and steadily.

Moreover, according to the present embodiment, the dry ice is supplied into the cage2in a state where the cage2is rotated. In this manner, the dry ice is prevented from filling the supply opening, and a sufficient amount of the dry ice can be put into the cage2. As the result, the animal can be cooled and fixed instantaneously and steadily.

Meanwhile, in the present embodiment, a case where the animal fixation device is mounted on the experimental satellite10has been described. Since it is assumed that no person is in the experimental satellite10, the euthanasia process and the fixation process are required to be automatically carried out. Additionally, the euthanasia process and the fixation process are required to be steadily carried out in considering that the animal is put into the hyper gravity environment during the returning to the earth. Since a period between time when the fixation operation has been carried out and time when the analysis is carried out becomes long, it is required to steadily carry out the euthanasia process and the fixation process. The animal fixation device of the present embodiment can respond to these requests, and accordingly it is preferable that the animal fixation device is used by being mounted on the experimental satellite10. However, the animal fixation device according to the present invention does not necessarily have to be mounted on the experimental satellite10and may be used on the ground. Even when the device is used on the ground, the same effect as that described in the present embodiment can be obtained.

Moreover, in the present embodiment, the explanation has been made by exemplifying the carbon dioxide gas as the euthanasia gas. However, the euthanasia gas is not limited to the carbon dioxide gas, and accordingly other kinds of gas which is able to euthanize the animal may be used.

Furthermore, in the present embodiment, the explanation has been made by exemplifying the dry ice as the solid refrigerant. However, the solid refrigerant is not limited to the dry ice. Other kinds of refrigerant, for example, ice may be used as the solid refrigerant. Meanwhile, in a case of using the dry ice, the inside of the cage2is kept to be in a frozen state (below zero). On the other hand, in a case of using the ice as the solid refrigerant, the inside of the cage2is kept to be in a refrigeration state (4° C. to 10° C.). By keeping the inside of the cage2to be in the refrigeration state, the biological condition of the animal also can be fixed.