C57 Strain Research Articles

Strain differences in aggressive behaviour of female mice against lactating and non-lactating individuals

Aggressive behaviour can be expressed by grouped Swiss female mice towards a conspecific female intruder. However, the level of aggression is considerably increased when the intruding female is lactating. The present study was conducted in order to extend this finding to the two inbred strains of mice and to compare their behaviours: C57BL/6 and C3H/He. The results show that females of the C57 strain are aggressive only towards lactating intruders whilst C3H females do not exhibit aggressive responses either in the presence of non-lactating or lactating conspecifics. The significance of these strain differences in aggressive behavior is discussed.

Sex differences in aggressive behaviour in various strains of mice

Two nonalbino inbred (C57 BL/6 and C3H/He) and one albino strain (Swiss) of mice were compared for female aggression toward intruders: 1 in period of lactation, 2 in nonlactating state and (3) in nonlactating state but previously rubbed with urine of lactating females; and for male aggression toward familiar or unfamiliar opponents. The results showed that resident females of the C57 and Swiss strain vigorously attack lactating intruders introduced into their cages. This effect was mediated by urinary cues emitted by the latter mice. It was also shown that Swiss residents displayed aggression towards nonlactating females, irrespective of their strain. Groups of C57 residents reacted most aggressively towards Swiss females, less aggressively towards C3H intruders, but did not show any aggression towards their own nonlactating conspecifics. In contrast, none of the C3H resident female groups displayed aggression towards intruding females of any category or strain. The results also showed that the males of the three strains displayed little (Swiss and C3H) or no aggression (C57) towards familiar opponents, whereas they directed increased aggressive responses towards unfamiliar ones. Comparisons among the three strains of mice revealed that Swiss males were the most aggressive in either situation. On the other hand, the finding that C3H males showed aggressive responses suggested that male and female aggression are, in this strain, under separate genetic or hormonal control.

Effects of pre- and post-trial caffeine administrations on simultaneous visual discrimination in three inbred strains of mice

BALB/cJ, DBA/2J, and C57BL/6J mice were injected with caffeine and tested, in the five choice Yerkes-Thompson Bryant-Bovt Nitti apparatus for patterns discrimination, in two sets of experiments. In the first the patterns were opposite oriented oblique bars, in the second U-shaped figures, one opened toward the right, the other toward the left. As concerns the saline injected animals in both sets of experiments, the BALB mice showed the highest learning abilities; in the second set the C57 strain, whose performance had not been different from that of the DBA mice in the first set, performed at the lowest level. Pre- and post-trial caffeine (5 mg/kg) administrations were followed by performance impairment in the BALB strain, while performance improvements were evident in the drugged animals belonging to the other two strains.

Strain-dependent gonadal effects upon adrenal cholesterol ester concentration and composition in C57BL/10J and DBA/2J mice.

The effects of gonadectomy and sex hormone administration on the concentrations of the individual cholesterol esters in the adrenals of C57BL/10J and DBA/2J mice are described. The methyl esters of the fatty acids derived from the cholesterol ester fraction have been analyzed by gas-liquid chromatography. In both strains the females have a higher total adrenal cholesterol ester concentration than the males. However, different gonadal effects operate in the two strains. In the C57 strain the presence of the ovary or the administration of estradiol benzoate to the ovariectomized female increases the concentrations of all adrenal cholesterol esters. This effect does not occur in the DBA strain. In the DBA strain the presence of the testes or the administration of testosterone propionate to the castrate male lowers the concentration of all adrenal cholesterol esters. This effect does not occur in the C57 strain. The response to testosterone propionate in the castrate male of the DBA strain is significantly greater than that of ovariectomized female. This finding suggests that sexual differentiation influences the magnitude of the response. In both strains cholesteryl adrenate (C22:4) shows these gonadal effects to a greater degree than the other adrenal cholesterol esters. Thus, there are at least two types of gonadal control of adrenal cholesterol esters. One of these affects all the esters in general while the other affects adrenic acid metabolism specifically.

Long-term effects of early ethanol on predatory behavior in inbred mice

A system was developed to study the long-lasting neurological and behavioral effects of known amounts of ethanol received transplacentally and via the mother’s milk by C57BL/10 and DBA/1 mice offspring. The present paper is concerned with the cricket-predation behavior of the offspring at ages 50 and 51 days. Treated DBA offspring had a 58% reduction in predatory incidences, compared to control, but the already nonpredatory C57 strain was not affected significantly by ethanol. The treated mice that preyed on the crickets had normal latencies. A few general facts related to the nature of predatory behavior were also noticed: DBA mice had a higher proportion of predation and shorter latencies than C57, improvement across trials was specific to the C57 strain, there was a high correlation between trials, both sexes displayed predatory behavior, and isolation did not affect predation. Predatory behavior offers a simple reliable tool for psychopharmacological research.

Inheritance of sperm head abnormality types in mice - the role of the Y chromosome.

SUMMARYFour inbred strains of mice were used, differing in the total percentages of spermatozoa with abnormal heads (KE, 22·1%; C57, 26·4%; KP, 7·7%; CBA, 5·5%) and in the frequency distribution of abnormality types, as divided into four arbitrary classes. The most variable class 2 (narrow heads with canals inside the nuclear material) accounted for 47% of all abnormalities in KE strain, was common in CBA (29%) and almost missing in KP and C57 strains. F1 hybrids from the diallel crosses of these strains exhibited highly significant heterosis effects and significant reciprocal differences in the total percentage of abnormalities. The relative frequency of class 2 ranked in F1 hybrids in a similar order as calculated from the mid-parental values. After seven generations of backcrosses performed to introduce the Y chromosome from CBA to the genetical background of the KE strain, the total percentage of abnormalities was significantly reduced, although the relative proportion of class 2 was similar to that in KE strain. Also the Y chromosome from C57 strain, introduced into the genetical background of KE strain, caused a significant reduction of total abnormalities, but again the relative frequency of class 2 was not affected. It is concluded that the Y chromosome plays an important role in determining the total percentage of sperm head abnormalities, but does not seem to be involved in influencing specific abnormality types.

Effects of methadone on activity and on brain monoamines in two strains of mice

Two strains of mice (C57BL/6J and DBA/2J) were used to determine the effects of single and multiple injections of methadone on open field activity and on brain monoamines. For the DBA strain, the initial injection of methadone produced an attenuation of locomotor activity. After 7 daily injections, activity increased to that of controls. For the C57 strain, the initial injection produced a slight increase in activity which become more pronounced after further daily injections. Norepinephrine concentration was elevated in brains of DBA mice chronically exposed to methadone. This effect was not observed in C57 mice nor in either strain injected only once with the drug. Serotonin concentration was not altered in animals of either strain whether or chronically exposed to methadone. The results of this study suggest: 1) that activity change following methadone injections is dependent upon genetic factors and previous experience with the drug; 2) that the tolerance develops to the drug produced decreases but not increases in activity; and 3) that chronic exposure to the drug can elevate noropinephrine concentration in brains of DBA mice.

Accumulation of 3H-estradiol in the vaginas and pituitary glands of mice of inbred strains.

The sensitivity of the vaginal epithelium of ovariectomized mice of the A and C57 strains to estradiol differ approximately fivefold. The vaginas of the more sensitive C57 strain did accumulate more 333H-E2 at 1 hr in two or three experiments but the retention at 6 and 12 hr was not significantly different. The pituitary accumulation of H-E2 by the pituitary-tumor susceptable C57 mice, although not significantly greater than that of the nonsusceptable A strain mice at 1 hr was higher at 6 and 12 hr after the injection. Most of the toluene extractable radioactivity from pituitary glands and vaginas was estradiol with no strain differences. The accumulation of H-E2 in other tissues was not significantly different in mice of the two strains.

Genotype-dependent electroencephalographic, behavioral and analgesic correlates of morphine: An analysis in normal mice and in mice with septal lesions

Electroencephalographic, locomotor, and analgesic responses were studied in two strains of inbred mice (C57BL/6J and DBA/2J) implanted with epidural cortical electrodes. For the C57 strain the injection of morphine produced a sharp increase of locomotor activity and the EEG showed high amplitude slow waves similar to sleep, while the same strain was less sensitive to the analgesic effects of the opiate. For the DBA strain the locomotor activity was not enhanced following morphine and there was no alteration of the EEG pattern, while a pronounced analgesic response was evident in this strain. Septal lesions antagonized morphine analgesia in both strains while locomotor and electroencephalographic responses were unaffected in C57 mice. The findings suggest the following. o (1) The electroencephalographic responses to morphine are genetically determined. (2) The septal area is implicated in morphine-induced analgesia but not in the locomotor responses or in the brain electrical responses to the opiate. (3) The electroencephalographic alterations induced by morphine do not seem to be directly connected with the analgesic properties of the drug.

Correlation between choline acetyltransferase activity and learning ability in different mice strains and their offspring

The enzymes related to acetylcholine metabolism were investigated in several cortical regions of 3 inbred strains of mice (SEC, DBA and C57) differing in learning ability, and in their F1 offsprings. A higher choline acetyltransferase (ChAc) activity was found in the temporal lobe of mice with high learning ability (SEC and DBA) than in C57 mice which score poorly. The genetic behavioural analysis conducted on the F1 offsprings of these strains 18 demonstrated that F1 hybrids of SEC and C57 crosses were able to reach the same high learning levels as the parental SEC strain. In contrast, the DBA × C57 offsprings performed as poorly as the C57 strain which had low levels of performance. We showed that ChAc activity in the temporal lobe of the SEC × C57 hybrids was close to that of the SEC strain and in the F1 offspring of DBA × C57 crosses, near the values of the parental line C57. It was suggested that these differences may constitute a neurochemical correlate of the differences in learning abilities of these mice strains.

Reductive metabolism of corticosterone in mice: differences in NADPH requirements of liver homogenates of males of two inbred strains.

The metabolism of 3H-corticosterone by C57BL/1OJ and DBA/2J mice has been studied in homogenates of liver from the two strains with and without the addition of a NADPH-generating system. A complete quantitative and structural analysis has been made of reduced metabolites produced by both strains, in the presence or absence of exogenous NADPH. These studies show that 3H-corticosterone is metabolized more efficiently to polar steroids in homogenates of the C57 strain and reveal a strong dependence upon exogenous NADPH for hepatic corticosterone metabolism in the DBA strain that is not apparent in C57. 3H-corticosterone is metabolized by both strains in vitro mainly to mixtures of products that are either reduced in ring A (tetrahydro-derivatives) or reduced both in ring A and at C-20 (hexahydro-derivatives). Among both tetrahydro- and hexahydro-derivatives 3β,5α metabolites predominate in both strains but 3β-reduction and C-20 reduction are markedly more active in the CS7 than in the DBA strain. In both str...

Metabolism of vitamin B 6 in the I-strain mouse : II. Oxidation of pyridoxal

The relationship of the higher vitamin B 6 requirement of the I/St mouse to enzymatic oxidation of the vitamin to 4-pyridoxic acid has been investigated. 4-Pyridoxic acid, the principal urinary metabolite of vitamin B 6, is formed from pyridoxal by an aldehyde oxidase whose probable identity with N-methylnicotinamide oxidase is demonstrated. When vitamin B 6 intake is limited, the I-strain mouse excretes more 4-pyridoxic acid than does a control strain, the C57B1/6J. Whether increased 4-pyridoxic acid excretion results in more rapid depletion of vitamin B 6 stores in the I-strain mouse than in the C57 strain mouse remains to be determined. No explanation for the increased 4-pyridoxic acid excretion is found in a comparison of aldehyde oxidase activity in the two strains. Under all dietary conditions, aldehyde oxidase activity in I-strain mice is about half that in C57 animals. The Michaelis constants of aldehyde oxidase preparations from the two strains for pyridoxal and N-methylnicotinamide are similar.

The regulation of glycogen metabolism in mouse liver

The enzymes involved in the synthesis and the degradation of liver glycogen were studies in two inbred strains of mice in an attempt to assess the mechanisms that regulate glycogen concentration. Glycogen content was greater initially, and increased more rapidly, in fasted mice of the C57BL/FnLn strain than the I/FnLn strain following injections of glucose or of glucose plus insulin. These strain differences in glycogen content were correlated with a greater activity of, and more rapid increases in, the glucose 6-phosphate-independent form of glycogen transferase. The conversion in vitro of the glucose 6-phosphate-dependent form to the independent form was also more rapid in C57-strain mice. Under all experimental conditions, the total activity of glycogen transferase was the same. The activity of glucose-6-phosphate was consistent with the strain differences in glycogen content and was greater in I-strain mice. Here the content of glucose 6-phosphate was also consistently less. The regulatory role of glycogen phosphorylase was difficult to evaluate. In fasted mice of the C57 strain, the activities of glycogen phosphorylase and its converting enzymes, phophorylase kinase and phosphorylase phosphatase, were greater than in I-strain mice. Glucose administration reduced the activities of all three enzymes in C57-strain mice but had no effect on the enzymes in I-strain mice.

Endocrine changes in two strains of mice exposed to constant illumination.

Female mice of DBA and C57 strains were exposed to constant illumination for 10 months and comparisons of the endocrine glands and secondary sex organs were made. As compared with ovaries of control mice, there was an increase of interstitium and cystic follicles and an absence of corpora lutea in those exposed to light. Tubular adenomas of the ovary were present in 2 mice. Endometrium was hyperplastic and the vagina markedly cornified. Degree of morphological changes in DBA mice exceeded that in C57 mice, suggesting that the ovaries of DBA mice are more responsive to illumination. (Endocrinology 86: 914, 1970)

Spermatozoal head shape in two inbred strains of mice and their F1 and F2 progenies.

Seven available inbred strains of mice-A, C57, SWR, C3H, 101, CBA, and DBA-were examined for differences in the shape of their spermatozoal heads. The two most extreme strains with respect to spermatozoal head shape were found to be SWR and C57. The Fl and F2 progenies derived from crossing C57 and SWR strains were found to be roughly intermediate between the parent inbred strains. Spermatozoal head shape for these preliminary investigations was calculated as outlined by Penrose (1953). Discriminant analysis was then carried out on F2 data and a linear discriminant function was obtained whereby 13 characteristics of the spermatozoal head were combined into one "super-character" or discriminant score. The numerical value of the discriminant score was taken as an estimate of spermatozoal head shape for each spermatozoon measured. 4nalyses of variance carried out on the discriminant scores for each generation revealed that intrastrain variation was not significant in the SWR strain and reached only low levels of significance in the C57 strain. The Fl males were found to be more variable than the inbred males. A large portion of the variability between the Fl males was shown to arise from "maternal effects". The F2 males were found to be much more variable than the Fl males and an estimate of heritability was approximately 0 -9. A minimal estimate of the number of "effective factors" operating to distinguish the two inbred parent strains was found to be two. The within-male variance was found not to differ significantly from generation to generation. The implications of these results are discussed.

Mercury retention in two strains of mice

Two strains of mice were given 3.0 mg of mercury as mercuric chloride, phenylmercuric acetate, or methyl- mercuric chloride. The type A mice tended to retain more mercury in the liver and kidneys from injections of all three mercurials over an 8-day test period than did type C57 mice. Mercury from mercuric chloride was retained primarily in the kidneys of both strains and from phenylmercuric acetate by the A strain. Mercury from methylmercuric chloride was retained in about equal amounts by the liver and kidneys of both strains and by the C57 strain from phenylmercuric acetate.

In vitro steroidogenesis by the adrenal glands of mice.

Corticosterone and aldosterone were demonstrated after in vitro incubation of adrenals from mice of the BALB/c, RIII, C3H and C57 strains. In addition, 11-dehydrocorti-costerone appeared to be present in small amounts in incubates of BALB/c and RIII adrenals. Cortisol was not positively identified in any in vitro incubates, nor was its presence detected in the peripheral plasma of 14- to 18-week-old BALB/c male mice. However, cortisol was present in small quantities in the plasma of young (4- to 6-week-old) BALB/c males. Quantitative studies of adrenal corticosterone production were made, although it was noted that the corticoste-rone-like material analyzed may also have included some 17-hydroxy, 11-deoxycorticosterone. These quantitative studies revealed that the adrenals of 3-month-old BALB/c, C3H and C57 males have a lower in vitro secretory activity than do those of 3-month-old females. Castration of BALB/c males resulted in enhanced adrenal activity. Except for C3H females, which show a relatively lo...

The Immunoglobulins of Mice

Summary Serum levels of 7 S γ2-, 7 S γ1-, γ1A- and γ1M- globulins and of hemagglutinating antibody were determined in 10 strains of mice immunized with hemocyanin and ferritin. The effect of five factors on the response to immunization were investigated: a) difference between single and repeated injections of antigen, b) differences between antigen administration in saline and in adjuvant, c) effect of different time intervals between first and second administration of antigen, d) effect of adjuvant alone and e) mouse strain differences. A single injection of antigens in saline produced no appreciable change in the serum immunoglobulin levels. After a single injection of antigen emulsified in Freund's adjuvant, the levels of the 7 S γ1-globulins showed a two- to five-fold increase. After a second injection of the antigens in adjuvant, 7 S γ1-globulins showed a 10- to 30-fold increase. The absolute and relative changes in the other three immunoglobulins (7 S γ2, γ1A(IgA) and γ1M(IgM)-globulins) following primary and secondary challenge were not as marked as the increase in 7 S γ1-globulins. Repeated injections of antigen in saline produced a greater increase of γ1M(IgM)-globulins than did several injections of antigen in Freund's adjuvant. The response of specific immunoglobulins to antigenic challenge is strain dependent. The most notable strains were a) the C57BL mice, which showed marked increase of γ1M(IgM) and γ1A (IgA)-globulins and b) the white Swiss (GP) mice, which showed very little increase in γ1M-(IgM)- and γ1A(IgA)-globulins while developing the highest levels of 7 S γ1-globulin. Injection of adjuvant without antigen had no notable effect except in C57 strains of mice, where marked increases of γ1M(IgM)-globulins occurred.

Persistent genotypic differences in mouse activity under unusually varied circumstances

Twenty-one comparisons of activity differences among C57, DBA and C3H strains of mice have appeared over the past 11 yr. Despite wide variations in the use of substrains, experimental techniques and testing devices, strain rank order remains statistically stable. Such uniformity may indicate well-buffered physiological correlates.

X-IRRADIATION-INDUCED CONGENITAL ANOMALIES IN HYBRID MICE

1. Increased radioresistance is manifested in hybrid embryos exposed to 200 r at 8.5 days of embryonic development when divergent stocks of mice are crossbred, as determined by the incidence of congenital anomalies. This is evidence of embryonic heterosis.2. When hybrid mice are mated with hybrids (of the same crosses) or with either of the parental stocks, it is apparent that the presence of CF1 influence (genes?) affords the embryos more radioresistance only when the cross is with the CF1 line. The presence of CF1 genes brings the results up to the pure CF1 data so that it appears that there is a sort of dominance effect which becomes heterosis when the proportion of CF1 genes exceeds this minimum in these heterozygous embryos.3. In hybrid combinations the development of CNS congenital anomalies appears to be more frequently related to the presence of CF1 genes than to those from the C57 strain. Conversely, resorptions appear to be more directly related to the presence of the C57 genes. Even in the pure strains this is substantiated because 14% of the CF1 embryos and none of the C57 embryos showed CNS anomalies following 200 r x-rays at 8.5 days' gestation. Likewise, the C57 strain embryos reacted to this exposure by producing 92% resorptions while the CF1 embryos showed only 32%.4. The data on congenital anomalies seem at first to be confused. This is due to the simple fact of relative radioresistance of the CF1 embryos, which allows them to survive and hence to develop x-irradiation-induced congenital anomalies, particularly of the central nervous system. The radiosensitivity of the C57 strain reduced their survival. As a result of this, there are fewer survivors to develop CNS anomalies.5. As in other studies in heterosis, it appears that this embryonic hybrid vigor is correlated with maximum heterozygosity and is reduced as this condition is diluted toward either of the parental conditions.6. Radioresistance (or, conversely, radiosensitivity) of the embryo appears to be closely allied to inherent genetic factors quite different in the two strains of mice. In one strain there is the greater tendency to resorption and death and in the other to survival with attendant development of congenital anomalies.