Heretofore, studies on ochotona has been limited to the distribution of its habitat and their stored food. The main object of this project was to live-trap ochotona, acquire factual ecological in formations which were necessaay in order to develope ochotona as a new experimental animal.
This study was started July, 1957, and is still being continued, and there are still many more problems to be studied concerning ecology and keeping ochotona alive in captivity, but following tare the summary of the results of the study up till now.
Ochotona is about the size of a water rat, they are very tame. They are plant-eating animal and their fondness for dried plants seems to be the ircharacteristics.
1. Distribution of Ochotona is limited to Mt. Daisetsu, central mountain range, and part of Hidaka range. Population is specially dense in Mt. Daisetsu towards Kitami district.
2. Their terrain is mostly in rocky region. Temperature of the interstice is very low even in summer, about 12 to 14 degree centigrade. Their living habit does not seems to be influenced by the outside temperature, humidity nor the vegetation of the region.
3. Life span assumed to be from one to three years. Cruising radius about 30 to 40 m. Once settled they will not move from their range.
4. They live in the hole or interstice together but do not seem to be cooperative towards each other.
5. They do not hibernate. During snowing season, they are active both above the snow and also through the tunnel dug under the snow.
6. As far as food is concerned, Ochotona has been observed to eat almost any plant avaiable in the region. They store their winter food in autumn, but during summer, aside from eating fresh plants, they have the habit of temporarily storing and eating half-dried plants.
7. There are two kinds of faeces. One, round and pellet like, is usually found at fixed place. The other, long and viscuous, defecated mostly during night on the rock where it is airy. Ochotona has the habit of eating the so called night faeces, and there is every reason to suppose that coprophagy provides the ochotona with various supplies of vitamin B.
8. Breeding season assumed between May and July.
9. Litter size of Ochotona is between 2 to 3. Cub is slightly furred with eyes closed. About 15 days after birth, they are quite active and independent and they grow rapidly. By the 40th day, it almost reaches its full adult size.
10. The author has used the following feed for the captive ochotona: a) quartered apple (fresh) b) lespedeza (bicolor) fresh leaves and flowers and/or half dried leaves, c) wheatgerm meal with supplement of mineral, vitamin A. D., salt and calcium, d) water, or block of ice,
11. Growth rate of captive ochotona was favourable. Increase in growth rate of the young was higher than those of Lemming or the Tundra red back vole.
12. Diseases so far found in captive ochotona are as follows: Pneumonia, mycosis, diet defficiency, septicaemia and fly larvae.
I wish to express my appreciation to Mrs. Masu Nomura, Miss Michi Nomura of Oiso-machi, Kanagawa Pref., Dr. K. Suzuki of the Veterinary Section for The Institute of the Infectious Diseases for the help given to the author in keeping captive ochotona.

View full abstract

Although the Yoshida sarcoma and ascites hepatomas which are most commonly used in the field of cancer research in Japan, were originated from non-inbred strains of rats and consequently can grow well in some of non-inbred strains of rats, it might be of value from the practical points of view to find out and establish the best colony of rats for these tumors, because these tumors offer very interesting materials with characteristic peculiarity not only for the cancer chemotherapy scre-ening but also for the morphological and biochemical researches of cancer. This observation deals with the selection of the suitable colony of rats for four rat ascites tumors, including the Yoshida sarcoma, ascites hepatoma 7974, ascites hepatoma 130 and nitromin resistant ascites hepaloma 130 K. The colonies so far tested are indicated in Table 1, and the percent of lethal take (transplantation rate) and survival days of the intraperitoneal transplantation are observed. The cytological checking of the growth of tumor cell's and gross pathological findings of the dead animals are also carefuly undertaken with every rat as well. The results are shown in Table 3, 4, 5, 6, 7 as well as in Figures 1, 2, and several already reported results are summarized in Table 8 and 9. From these observations the followings might be pointed out as a summary.
1.The colony“H-1” (tentavively named, propagated originally from one pair of non-inbred rats by Dr. R. SATO and supplied in large scaels by Dr. J. KANEKO, Div. of Bacteriology of Hikari Factory, Takeda Pharmaceutical Ind., Ltd.) is the best in connection with the transplantation rate of the Yosh-ida sarcoma among several colonies so far tested. The colony“TH”, which originated from one pair of the common colony with“H-1”and has been propagated by Mr. K. OSAWA, Tokyo, showed high susceptibility like the“H-1”colony, which will be supported by Dr. H. SATOH through his experiments with this colony.
2. There existed some colony (“C”-colony), the susceptibility of which to the transplantation of the Yoshida sarcoma is very poor, and it is suggested not to use such rats even for the keeping of the Yoshida sarcoma. It is also noted that some of non-inbred colony such as“T”and/or“SD”is fairly good concerning the transplantation rate and is feasible to be used in practice, provided some adequate precaution are given.
3. The life span of the Yoshida sarcoma for the year 1955, 1956 and 1957 was 7.28±0.12, 7.53±0.16 and 8.12±0.15 days respectively and the range of deviation was found to be fairly narrow.
4. The transplantation rate and survival time of three ascites hepatomas were also compared among several colonies, and the“H-1”colony is considered to be suitable for the practical use for these tumors. It is also noted that there was no difference in the transplantation rate and survival days among the ascites hepatoma 130 and nitromin resistant ascites hepatoma130K which was induced from the former. (with technical assistance of T. KOMETA)

View full abstract

Suggested by Dr. K. Ando, Director of the Japan Experimental Animals Research Association, to decide the name of a colony of Japanese rats which have been proliferated from single pair by random breeding since 1950 and were noticed to be highly susceptible to the Yoshida sarcoma in 1952, the committee on experimental cancer research of the Association discussed the experimental results obtained among the scientists concerned and have got the following conclusion.
1. It was confirmed from the results of 5 independent laboratories using more than 3, 000 animals that the rats belonging to this colony are very susceptible to the intraperitoneal transplantation. of the Yoshida sarcoma. The rate of the transplantation is 99-100%, significantly higher than 88.3% in Japanese random colony from dealers, and 94 to 0% in 12 American strains. The survival days of the Yoshida sarcoma bearing animal are unif ormely 7 to8 days.
2. It was suggested to call this colony as“Donryu-rats”for the conveniency of the usage; Donryu is associated with the place where the animals were originally bred.
3. Present situations of the supply and the breeding of“Donryu-rats”have been checked with three independent fascilites.
The following scientists cooperated with the investigation.
I. Hirono : Dpt Pathology, Nagoya Univ., Med. School, Nagoya
H. Isaka : Sasaki Institute, Surugadai, Kanda, Tokyo
K. Kaziwara : Takeda Institute, Jyuso, Osaka
J. Kaneko : Hikari Factory, Takeda Pharmaceutical Co., Hikari, Yamaguchi-Pref.
S. Makino : Dpt. Zoology, Hokkaido Univ., Sapporo
K. Osawa : Osawa Farm., Futaba-cho, Shinagawa-ku, Tokyo
R. Sato : Sato Farm., Oizumi-cho, Gumma-Pref.
H. Sato : Dpt. Pathology, Fukushima Univ., Med. Scool, Fukushima-shi
H. Satoh : Jatrochemical Institute, Nishigahara, Kita-ku, Tokyo
K. Tsuchikawa : Institute of Genetics, Mishima, Shizuoka-Pref.
K. Warabioka : Institute of Cancer, Nishisugamo, Toshima-ku, Tokyo
T. Yamamoto : Institute of Infectious Diseases, Shibashiroganedai-machi, Minato-ku, Tokya
Drs. J. Kaneko, R. Sato and Mr. K. Osawa are taking care of the breeding so far checked.

View full abstract