Particular characteristics of laboratory mice are required for certain experimental purpoces. A diversity of animal experiments requests various types of inbred mouse strain so that many inbred strains have to be provided.
In the present study, to bring up the characteristic strains suitable for the experiments employing certain insecticide, BHC, selection of a resistant strain by the BHC was attempted. Gamma BHC (0.5g) was dissolved in ethyl ether (10ml) and 0.1-0.3cc of the solution was dropped on to the neck of mice. Through this procedure, the susceptible mice were killed usually within 2 days after the application following severe convulsion. Survivors could be bred further in a usual manner.
Selection programs were applied to 4 strains of mice. Al and DCS strains appeared to be susceptible BHC. The progenies, whose parents were killed by the BHC treatment, were used for further breeding. DCR and BHC strains were resistant against BHC. The selection of susceptible progeny from Al strain was not successful. In spite of the identical selective procedures for susceptible progency from DCS strain, those procedures resulted rather a resistant strain. DCR strain seemed to become resistant during the course of selection, although the final test against BHC failed to show a clear cut resistance. In BHC strain, the selection was effective and the mice in the strain became resistant generation after generation. However the fertility of both of DCR and BHC strains decreased gradually so that a mass production of mice became difficult.

View full abstract

The blood characters of the hereditary obese hyperglycemic mice, C57BL/6J-ob (OH), and their non-obese litter mates (control) were determined. The results of examination were as follows:
1. Number of erythrocyte and leucocyte, and leucocyte diagnosis did not show marked difference between OH and control mice.
2. Erythrocyte sedimentation rate, erthrocyte fragility and blood coagulation in OH mice were found to be similar to their control.
3. Phagocytosis of leucocyte in OH mice revealed marked decrease in comparison with that of the control.
4. Serum cholesterol levels in OH mice were about twice as much as those in control mice.
5. Total fatty acids, phospholipids and the levels of free fatty acids were higher in OH mice than those of the control.

View full abstract

Animals used for the present experiments consisted of 10 adult male Japanese white rabbits, weighing 2.6-3.1kg, 18 adult male and female pigeons, weighing 380-480g, and 30 Wistar strain adult male rats, weighing 160-185g.
The experiments were conducted as (1) determination of the lethal body temperature when exposed to 44°C, and (2) detection of the critical temperature at which animals could survive if they were removed from the high temperature environment. Following results were obtained.
1) The average lethal body temperature of rabbits was 44°C, and the survival time under this temperature was found to be 60 to 70 minutes.
2) The maximum of the safety range of body temperature for rabbits was 43°C. The rabbits placed at 44°C for 30 minutes, were able to recover in a cooler environment.
3) The average lethal body temperature for pigeons was 47°C and the survival time at this temperature was approximately 30 minutes.
4) The maximum of the safety range of body temperature for pigeons was 45°C in the environmental temperature of 44°C. The pigeons, exposed to 44°C temperature, were able to recover, when taken out to a cooler environment.
5) The average lethal body temperature of rats was 44°C, and the survival time was about 50 minutes.
6) The mortality of rats, calculated from their body temperature, was as follows:
44.0±0.5°C 100%
43.0±0.5 90
42.0±0.5 50

View full abstract

This investigation was supported in part by a WHO Research Grant on “Experimental Filariasis Studies”, and by Public Health Service Research Grant C-00017-04 from Nihon Kiseichu Yobokai, Report No. 40.
Cotton rat, Sigmodon hispidus, has been bred in our laboratory since 1953 as the laboratory animal for experimental filariasis studies and observations were made on its life history and behaviors. The maximum, minimum and average numbers of babies from 158 litters were 9, 1 and 4.4 respectively.
The growth curve was recorded for 24 animals. The body weight at the new born was from 3.9 to 7.2g with the average of 5.6g, and it reached to 130g in males and 120g in females after 15 weeks. In the conditions of our laboratory, the rate of survival was 68 percent for the first month, 54 percent for the second, and 45 percent for the third months. The longest records of life span observed for 113 males and 146 females were 438 and 458 days respectively.
The average amount of food consumed per day per animal was 4.5g of rat-biscuit, 13.7g cabbage and 10.1ml water.
Surveys were made on external and internal parasites. Only 2 cases out of 100 animals autopsied harboured Hymenolepis diminuta and Rhabditis sp.

View full abstract

Several techniques for detection of parasite infestation in mice which used or can be used in our laboratories are described in this report.
For internal parasite infestations, cellophane tape method (or Scotch Tape technique), direct smear method, flotation technique with saturated saline water and autopsy are used. Ova of Syphacia obvelata is detected efficiently by cellophane tape technique. In the contrary, egg of Aspiculuris tetraptera Hymenolepis nana and Hymenolepis diminuta are detected by direct Emear method or flotation technique with saturated saline water. In autopsy, alimentary canal, liver and urinary bladder should be examined in detail for above mentioned parasites and other helminths.
On the other hand, for ectoparasites, hair warming technique, cellophane tape method, wide cellophane tape method, scab-warming technique and stimulation method with carbone dioxide-gas are uEed. Cellophane tape method and hair warming technique are simple and effective to be used for live host checking.

View full abstract