Granuloma formation to Capillaria hepatica eggs. I. Descriptive definition

The course of the cellular response in the liver to nonembryonated Capillaria hepatica (Bancroft, 1893) eggs given by intravenous injection into the portal circulation of unsensitized and sensitized mice was studied qualitatively and quantitatively. A gradual infiltration of predominantly mononuclear cells occurred around the eggs in the liver, leading to the formation of distinct granulomatous lesions characterized by macrophages and lymphocytes. This was followed by an infiltration of eosinophils. Previous intraperitoneal sensitization led to an earlier and an enhanced reaction to an intravenous challenge with eggs. Specificity of the cellular response was suggested by the lack of an enhanced reaction to presensitization with eggs of a closely related species, Trichuris muris. These studies indicate that granuloma formation to C. hepatica eggs has an immunological basis and furthermore the cell composition of the granuloma would suggest that a cell-mediated component may be involved as part of the specific response.     

Selection for components related to body composition in mice: direct responses

Summary Replicated within full-sib family single-trait selection was conducted for 10 generations in mice for (1) high or low 12-week epididymal fat pad percentage (100 x epididymal fat pad weight/body weight) or (2) high or low 12-week hind carcass percentage (100 x hind carcass weight/body weight). Pooled realized heritabilities based on high, low and divergent selection were 0.66±0.09, 0.65±0.13 and 0.66±0.05 for epididymal fat pad percentage and 0.48±0.08, 0.33±0.08 and 0.40±0.04 for hind carcass percentage. The pooled realized genetic correlation (r_{G R}) between epididymal fat pad percentage and hind carcass percentage based on divergence was –0.67±0.04. Other estimates of (r_{G R}) were: epididymal fat pad percentage with body weight (0.57±0.05); epididymal fat pad percentage with epididymal fat pad weight (1.17±0.05); hind carcass percentage with body weight (–0.61±0.09); hind carcass percentage with hind carcass weight (–0.05±0.11). Indirect measures of fat and lean tissue percentages were highly heritable, and (r_{G R}) between them would be desirable from the standpoint of analogous types of traits in livestock. In the same context, undesirable (r_{G R})'s were found between epididymal fat pad percentage and body weight and between hind carcass percentage and body weight.Paper No. 10957 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, North Carolina 27695-7601, USA. The use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Research Service of the products named, nor criticism of similar ones not mentioned     

Maturing patterns of organ weights in mice selected for rapid postweaning gain

Summary Correlated responses to selection for increased 3–6 week postweaning gain in male mice were estimated for seven internal organs (testes, spleen, liver, kidneys, heart, small intestine (S intest) and stomach) weighed at specific degrees of maturity in body weight (37.5, 50.0, 62.5, 75.0, 87.5 and 100%). Correlated responses in organ weights were generally large, but the magnitude and direction of response depended upon whether 1) comparisons were made at the same age, degree of maturity or body weight and 2) absolute or proportional organ weights were used. The selected line (M16) weighed more and had larger organ weights than controls (ICR) when compared at either the same degree of maturity or the same age, indicating positive genetic correlations between body weight and the respective organ weights. Positive correlated responses were found in spleen weight/body weight at all degrees of maturity and in liver and S intest weights as a proportion of body weight at some degrees of maturity. Testes, kidneys, heart and stomach weights as a proportion of body weight had negative correlated responses, though this was consistent only for kidneys across all degrees of maturity. Correlated responses in organ weights adjusted for body weight by covariance analysis were positive for spleen, S intest and stomach and negative for testes and kidneys. Based on the constrained quadratic model, degree of maturity in organ weight relative to degree of maturity in body weight responded positively for testes, kidneys and S intest and negatively for spleen and liver. Selection for increased growth caused negative correlated responses in allometric growth of testes, kidneys, S intest and stomach.Paper No. 10,545 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, 27695-7601. The use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Research Service of the products named, nor criticism of similar ones not mentioned     

Energy expenditure and locomotor activity in mice selected for food intake adjusted for body weight

Summary The aim of this study was to examine the differences in physical activity and their contribution to differences in energy utilization in mice, selected either high or low for food intake, adjusted for body weight, which show correlated responses in lean content and metabolic rate. Simultaneous measurements of fasting metabolic rate and activity were made in lines of mice selected at either: a young age, 4-to 6-week food intake corrected for 4-week body weight; or an older age, 8- to 10-week food intake corrected for mean weight at 8 and 10 weeks of age. Correlated response in metabolic rate was found to have been accompanied by changes in locomotor activity near the ages at selection in both sets of lines. Activity, however, accounted for only a small proportion of variation in fasting heat production, generally less than 5%, although a highly positive correlation (r=0.63) between the two traits was found. It was concluded that selection for food intake adjusted for body weight has led to correlated response in physical activity. In consequence, mice selected in the upward direction expend some of the excess energy intake rather than assimilating it as body mass and are, therefore, slightly leaner than their counterparts selected in the downward direction.     

Effect of genetic background on growth of mice hemizygous for wild-type or dwarf mutated bovine growth hormone transgenes

The effects of a high-growth genetic background on the growth of mice hemizygous for one of two growth hormone transgenes were examined. Male mice hemizygous for wild-type (W) and dwarf mutant (M) bovine growth hormone (bGH) transgenes were crossed with females of a high-growth selected (S) and control (C) line as follows: W x S, W x C, M x S and M x C. Body weights of progeny were recorded weekly from 2 to 10 weeks of age. F₁ progeny were classified as carriers (P) or non-carriers (N) of the transgene by assaying tail DNA for bGH using the polymerase chain reaction and agarose gel electrophoresis. A deficiency in the number of f₁ progeny carrying the W (P<0.05) and M (P<0.01) bGH transgene was most likely due to differential prenatal and early postnatal mortality. Bodyweight means of wild-type transgenic mice were larger (P < 0.05) than those of non-transgenic littermates by 3 weeks of age in a C background in contrast to 5 weeks in S. The wild-type bGH transgene increased adult body weights more in the C (155%) than in the S (136%) background, indicating transgene expression by selection background interaction (P < 0.05). However, the growth response to the wild-type transgene in the S background was still large. The dwarf mutant transgene had a greater effect on growth reduction in the S (70%) than in the C (84%) background, thus causing transgene expression by selection background interaction (P < 0.05). Gender by wild-type transgene effect interactions (P < 0.001) for adult body weight were caused by the transgene reducing the gender difference for body weight in C and eliminating it in S. The dwarf mutant caused a larger negative effect on growth in males than in females, resulting in a gender by dwarf mutant transgene interaction (P < 0.001) for adult body weights. Results indicate that the effect of a GH transgene on growth can be affected both by a high-growth genetic background and the gender of progeny.     

Correlated responses of growth traits to selection for high and low plasma alkaline phosphatase in mice

Summary The effectiveness of two way selection for plasma alkaline phosphatase (ALP) was investigated in order to determine its influences on growth traits through thirteen generations. The responses of the two lines selected for high (HP) and low (LP) ALP at 45 days of age were compared to that of the mice selected for large (L) and small (SM) body size. The selection responses of plasma ALP were very effective for both HP and LP lines, with average responses per generation calculated from linear regressions of 0.227±0.037 and –0.088±0.022 respectively. The final levels of ALP in HP and LP were 5.54±0.71 and 1.27±0.20 in the thirtheenth generation, while the SM, L and base population had levels of 3.49±0.08, 0.86±0.55 and 2.77±0.56 respectively. The body weight at 45 days of age in LP (31.4±1.4 g) as a correlated response was significantly higher than HP (23.4±1.8 g) at generation 10. The correlated response of milk yield, measured by weight gain up to 12 days of age, was significantly greater in the LP line than in HP, but the correlated response of gains after weaning was not so different as the response of milk yield. The response of litter size and weight in LP showed significant higher levels than that of HP, but pups' birth weight did not differ between LP and HP. It is suggested that the correlated response of milk yield contributed more to the divergence of body size between HP and LP than the gain after weaning.Realized heritabilities of ALP were 0.335±0.059 (HP) and 0.279±0.051 (LP). Realized genetic correlations between ALP and 45 days' body weight were –0.27±0.13 (HP with SM) and –0.52±0.19 (LP with L). Realized genetic correlations between ALP and milk yield were –0.95±0.03 (HP) and –0.37±0.29 (LP). Correlations between ALP and postweaning gains were fairly low.     

Environmental maternal influences on body composition in mice selected for body weight

Summary The effect of the postnatal maternal environment, simulated by rearing mice in litters of three, six or nine, on body weight and body composition was investigated in three lines of mice differing widely in growth rate. The lines were selected for high (H₆) and low (L₆) 6-week body weight while the control line was maintained by random selection. Body weight and weights and percentages of ether extract, water, ash and protein at 21, 42, 63 and 84 days were recorded. With few exceptions, there were positive correlated responses to selection in body weight and in weights of body components. At 21 and 42 days the correlated responses were larger in L₆ mice than in H₆ mice. Body weight and weights of body components were larger for mice reared in litters of three than for those reared in litters of nine. Also, mice reared in litters of six were intermediate in body weight and weights of some of the body components between those reared in litters of three and nine. Differences in body weight and weights of body components due to postnatal maternal environment were small by comparison with differences due to genetic line. There were significant line by maternal environment interactions in body weight at 21 days and in ether extract weight at 21 and 63 days. Line and maternal environment differences in percentages of body components did not follow any consistent trend. The results for percentages of body components were further complicated by line x maternal environment interactions. In general, both line and postnatal maternal environmental differences in percentages of body components diminished with age.Paper No. 5670 of the Journal Series of the North Carolina Agricultural Experiment Station, Raleigh, North Carolina 27650. The use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Experiment Station of the products named, nor criticism of similar ones not mentioned     

Boophilus microplus: characterization of larval proteases.

Cercariae of Schistosoma mansoni were treated with undecenyl-pseudothiourea. After centrifugation, they agglutinated into a mass. Resuspended in water, they remained immobilized. When injected sub-cutaneously into mice, they produced bisexual infections. The immobilizing drug effect, together with a reduced worm recovery rate, are time and concentration dependent. The cercariae become avirulent (99.8%) only when the flame cell is affected. Immobilizing and “cercaricidal” effects are not necessarily related properties; the latter can be determined only by in vivo tests of infectivity. No protection against reinfection was noticed in mice injected with immobilized cercariae of reduced virulence. The immobilized cercariae produced infections with a 0.7% worm recovery rate by percutaneous exposure, compared to 2.2% by subcutaneous injection. Normal cercariae produced infections with average recovery rates of 11.1% subcutaneously and 45% percutaneously.     

Trypanosoma musculi infections in complement-deficient mice

Strains of mice (CFW, C57B1/10Sn, B10.D2/nSn, and B10.D2/oSn) were infected with Trypanosoma musculi (Trypanosoma duttoni). The complement-deficient B10.D2/oSn mice showed typical parasitemias similar to those presented by the strains possessing hemolytic complement activity. Peak parasitemias occurred 12 days postinoculation. The highest parasitemias were measured in CFW mice (657 ± 82 T. musculi/30 hi-power fields), while infections in C56BL/10Sn (528 ±44 T. musculi/30 h.p.f.), B10.D2/oSn (502 ± 20 T. musculi/30 h.p.f.) and B10.D2/nSn (512 ± 35 T. musculi/30 h.p.f.) were less severe and quantitatively comparable. The percentages of dividing forms were similar during infections in each of the strains. While parasites were detected in peripheral blood until Day 22 of infection in three of 10 C57BL/10Sn mice, none could be found at this time in blood films of CFW, B10.D2/nSn or B10.D2/oSn mice. Giemsa stained kidney imprints indicated the presence of parasites in animals of each of the strains after 33 days, when trypanosomes could no longer be detected in the peripheral blood of the mice. The minor variations in the parasitemias appeared related to the mouse strain. Complement dependent, antibody mediated immune cytolysis was not indicated as a mechanism for the elimination of T. musculi by the infected mouse.     

Ablastin: Control of Trypanosoma musculi infections in mice

Trypanosoma musculi infections in CBA mice consist of a phase of increasing parasitemia during which dividing forms of the parasite are present in the blood, followed by a period when only nondividing trypomastigotes are seen. A second crisis terminates the blood infection and leaves the host immune, but small numbers of trypanosomes, including multiplicative forms, persist in the kidneys for many months. Studies were made involving infections in T-lymphocyte deprived mice, the effects of passive transfer of serum and cells, measurement of DNA synthesis by the parasite, serological responses, and in vitro effects of serum on the trypanosomes. These indicated that the initial check on the increase in blood parasitemia is due in part to two humoral factors. One of these has a trypanocidal effect (this is thought to be an IgM antibody) while the other, which may be an IgG antibody, is the ablastin that inhibits further reproduction by the parasite. Both trypanocidal and ablastic effects were demonstrable in the serum of immune mice yet the parasite was still able to survive and multiply in the kidneys.