Interstrain differences in red cell enzyme activities in mice and rats.

1. Interstrain differences in red blood cell enzyme activities were studied in mice (BALB/c, C57BL/6, C3H/He, DBA/2 and ddY) and rats (Donryu, F344/N, SD, Wistar and Wistar/ST), and were also compared with hamster, guinea-pig and rabbit. 2. The enzyme activities measured were: glutathione S-transferase (GST), glucose-6-phosphate dehydrogenase (G-6-PD), 6-phosphogluconate dehydrogenase (6-PGD), NADPH-diaphorase (ND), hexokinase (Hx), glutamate oxaloacetate transaminase (GOT), lactate dehydrogenase (LDH) and acetylcholinesterase (AChE). 3. There were marked variations in the activities of some red cell enzymes (e.g. GST, Hx, ND), while others (e.g. G-6-PD, 6-PGD) were much less variable both within different strains and species.     

Genetic differences in follicular DNA synthesis between two strains of hamsters

This study was designed to compare our previous results on ovarian follicular DNA synthesis by hamsters obtained from Sasco Laboratories with a different breeding colony: Harlan. Follicles from proestrous Harlan hamsters required twice as much [3H] thymidine and a minimum of 4 hr of in vitro exposure to 100 ng of ovine follicle-stimulating hormone (FSH) before a significant increase in DNA synthesis was elicited compared with 30-120 min for the Sasco breed. Peak responsiveness to FSH was observed at 8-hr incubation for the Harlan strain with significant increases in DNA per follicle at 8-12 hr. Both strains increased DNA synthesis with as little as 25 ng of ovine FSH and the response was elicited in all growing follicles, from preantral stages with one to four layers of granulosa cells, lacking theca (Stages 1-4) to mature antral follicles (Stages 8-10). A recombinant bovine FSH, devoid of luteinizing hormone activity, was not as effective as ovine FSH (which has 4% luteinizing hormone contamination) in stimulating DNA synthesis by large preantral and antral follicles. In vitro responsiveness to ovine FSH was abolished in the absence of Ca2+ in the culture medium and 0.05 mM Ca2+ was the optimal amount. For both strains of hamsters, the highest rate of DNA synthesis in response to endogenous gonadotropins was on the morning of estrus--when the second surge of FSH was in progress--and Harlan follicles in vitro also showed maximal stimulation by FSH on this day. Where the two strains differed was that the Harlan strain did not show an increase in follicular DNA synthesis on the afternoon of proestrus--when the preovulatory increase in gonadotropins commenced. When expressed as DNA per follicle, DNA approximately doubled from Stages 1 to 5 and then entered a new growth phase at Stage 6 (large preantral follicles) with a steeper increase. Collectively, these experiments show that strain characteristics can alter the latency and degree of follicular DNA replication in response to endogenous or exogenous FSH.     

Genetic control of the immune response to (T,G)-A--L in C3H in equilibrium C57 tetraparental mice

When 15 C3H ? C57 tetraparental (allophenic) mice were analyzed for coat color, hemoglobin, and immunoglobulin allotype, all but two were shown to be chimeric. These 15 tetraparental mice were immunized with the synthetic polypeptide (T,G)-A--L, and the origin of the (T,G)-A--L-specific antibody produced was determined by using genetic markers (allotypes) on the immunoglobulin heavy chain constant region. Five tetraparental mice were high responders to (T,G)-A--L and had significant amounts of a (low responder) allotype antibody in their total serum. Three of these mice had significant amounts of anti-(T,G)-A--L antibody of the a (low responder) allotype. The antigen binding capacities of the a allotype fractions of these three were 4–5 times higher than the antigen binding capacities of immunized C3H (low responder) control mice. These results are compatible with the hypothesis that the inability of low-responder mice to produce significant amounts of anti-(T,G)-A--L antibody is a function of Ir-1A gene expression at the level of T cells.     

Selective breeding for variations in patterns of mystacial vibrissae of mice. Bilaterally symmetrical strains derived from ICR stock

The establishment of certain patterns of mystacial vibrissae in mice has been the aim of an extensive breeding program carried on in this laboratory since 1977. In a companion paper we have reported on variations in this pattern in an outbred population of ICR mice. Starting with 21 ICR animals we bred, mostly by brother-sister mating, for 13 bilaterally symmetric patterns of mystacial vibrissae characterized by the presence (or absence) of supernumerary whiskers (SWs). The strains are classified as follows: I, a mouse strain with the standard pattern; II, eight strains bred for the occurrence of SWs at a given site or sites; and III, four mouse strains bred for a maximal number of SWs in different regions of the whiskerpad. Commonly, SWs occur in regions that coincide with the zones of mergence between the three facial processes except for two class II strains in which we bred for SWs in the "straddler" row of vibrissae, and for one class III strain, in which we cultivated the tendency (that appeared late in our program) to have SWs at the crest of a facial process. For classes I and II we analyzed the results for about 18 generations in terms of "improvement," meaning an increase in the percentages of animals with the desired phenotype together with a decreased frequency of undesired SWs. For class III, success in breeding meant the increase of the mean number of the desired SWs. All results led to the same conclusion: there is a genetic basis for the occurrence of SWs. The side preference of a particular SW is not strain dependent. It disappears in those class I and II strains in which almost 100% of animals obtained the desired phenotype. The increase in number of SWs in one zone of mergence does not depend on the presence of SWs in the other. Where tested, we almost always found a representation of an SW in a topologically equivalent location within the "barrelfield" area of the somatosensory cerebral cortex. Except for some diseases early in the breeding program, and some side effects of inbreeding that were eliminated, the population was without obvious defects. Where tested, there was no correlation between the occurrence of SWs and sex. The observed variations in pattern of mystacial vibrissae and their genetic background led us to propose a morphogenetic model for the formation of the pattern of mystacial vibrissae.     

The developmental patterns of lysosomal enzyme activities during Ca++-induced sporangium formation in Achlya bisexualis

The present paper describes intracellular changes in α-mannosidase specific activity during Ca⁺⁺-induced sporangium formation in the water mold Achlya bisexualis. The enzyme, which is concentrated in a cellular fraction with lysosome-like characteristics, undergoes a four-fold increase during sporangium differentiation. Addition of cycloheximide (100 μg/ml) or actinomycin D (10 μg/ml) at any time during the developmental sequence prevents further increase in the enzyme activity. These data suggest that coincident RNA and protein synthesis are essential for the accumulation of enzyme activity. Mixing of cell extracts from different developmental stages provides evidence that activators or inhibitors of the enzyme activity are not responsible for the enzyme activity evident at the different stages.     

Genetic control of mutability in laboratory mice. I. Genetic analysis of the sensitivity of mice of strains 101/H and C57BL/6 to the mutagenic effect of thio-TEPA]

The distribution of male mice of the BC1 generation was analysed with respect to the frequency of chromosome aberrations in bone marrow cells induced by thio-TEPA. The BC1 descendants were derived from the F1 of the cross (C3H X 101) X 101 and the F1 of the cross (CBA X B6) X B6. With respect to mutability the BC1 descendants of both types could be divided into two classes. The average frequencies of the cells with chromosome aberrations in the BC1 descendants of the 101 line were in the two classes 33.4 and 64.2 percent respectively. The corresponding values for the two classes of the BC1 descendants of the B6 line were 24 percent and 33.2 percent respectively. These data suggest that each of the lines studied has one recessive mutator gene. Preliminary symbols are proposed: mut-1 for the gene of the line 101/H and mut-2 for the gene of the line B6. The gene mut-2 is linked with the gene a (nonagouti) (Vth linkage group, chromosome 2).     

Genetic and biological characteristics of noninbred mice from the ICR colony]

Noninbred mice of the ICR colony were studied by a set of characters making it possible to estimate the range of genetic polymorphism in the given population. Genotypes of mice for loci A-, B-, D-, S-, PP, Se Se, and cc were determined. Noninbred mice were polymorphic for loci A, B, D, and S. Frequencies of recessive alleles of loci A, B, and D was calculated. Noninbred mice have a high fecundity and a low level of embryonic mortality, which indicate population heterogeneity. The age of the mother was shown to have no effect on the ovulation norm. The population standard of the colony for age-dependent change in the body weight and size was established. Age-dependent survival in females and males was shown to be associated.     

Digestive tract cell proliferation and food consumption patterns of Ha/ICR mice

The relationship between the daily pattern of food consumption and the proliferation rate of the oesophagus, stomach, forestomach, small intestine and colon of Ha/ICR mice was examined. Proliferative activity was determined by [3H]TdR incorporation on a wet weight tissue basis, along with selective counting of labelled nuclei. Under conditions of ad libitum feeding with a 12 hr light cycle (lights on at 0600) mice eat most of their food during the dark period. A distinct circadian rhythm was observed in the oesophagus, stomach, forestomach and colon with the peak of [3H]TdR incorporation between 0400 and 0600 and the nadir between 1600 and 1800. Although a circadian fluctuation was observed in the small intestine, its amplitude was much less than in other areas. This rhythmic change in proliferation rate could be phase shifted by allowing the mice to feed only between 0800 and 1600 for 14 days. Under these conditions the peak in proliferative activity occurred between 1800 and 2000. Fasting reduced the daily level of proliferative activity in all of the digestive tract sites studied, and for all areas except the oesophagus greatly reduced or eliminated the circadian fluctuation. The forestomach and colon were the most influenced by fasting with 24 hr [3H]TdR incorporation reduced to 30-40% of the control value. Refeeding following a 48 hr fast produced a rapid increase in proliferative activity peaking at levels well above the control value at 16 hr after the onset of refeeding. The major exception to this was the small intestine which slowly returned to the control value during the first 24 hr. Partial refeeding produced a diminished refeeding response. Once the normal pattern of food consumption was re-established following refeeding the normal proliferative fluctuations were again observed.     

Genetic differences between two strains of Xylella fastidiosa revealed by suppression subtractive hybridization

Suppression subtractive hybridization was used to rapidly identify 18 gene differences between a citrus variegated chlorosis (CVC) strain and a Pierce's disease of grape (PD) strain of Xylella fastidiosa. The results were validated as being highly representative of actual differences by comparison of the completely sequenced genome of a CVC strain with that of a PD strain.     

The developmental patterns of lysosomal enzyme activities during Ca2+-induced sporangium formation in Achlya bisexualis

The present paper describes intracellular changes in ribonuclease specific activity during Ca²⁺-induced sporangium formation in the water mold Achlya bisexualis. The enzymes undergo a decrease in activity prior to crosswall formation followed by an increase in activity during spore cleavage. As spore discharge occurs the RNase activity again decreases. A large percentage of the nuclease activity is associated with a lysosomal-like fraction of the cell, but there is also considerably activity associated with nuclear and microsomal fractions. Addition of cycloheximide or actinomycin D at various times during development prevents further decrease or increase in the enzyme activity. Mixing of cell extracts from different developmental stages provides evidence that inhibitors or activators of the enzyme activity are not responsible for the activity levels evident at the different stages. There is a change in the total levels of presumptive mRNA during Ca²⁺-induced sporangial formation which appears to be associated with the patterns of RNase activity. Utilizing total cellular RNA and Poly(A)⁺ RNA with the crude ribonuclease preparations, no substrate specificity could be ascertained.     

Genetic marker patterns of inbred strains of mice at the Cancer Research Institute, Bombay

36 genetic markers were examined in 14 inbred strains of mice maintained at the Cancer Research Institute, Bombay. The genetic marker profiles of these strains when compared with the profiles of similar strains maintained elsewhere revealed discrepancies in 4 of them which are reported and discussed. The results emphasize the importance of genetic monitoring of inbred strains.     

Measurement of carnitine biosynthesis enzyme activities by tandem mass spectrometry: differences between the mouse and the rat

Although the mouse frequently is used to study metabolism and deficiencies therein, little is known about carnitine biosynthesis in this animal. To this point, only laborious procedures have been described to measure the activity of carnitine biosynthesis enzymes using subcellular fractions as the enzyme source. We developed two simple tandem mass spectrometry-based methods to determine the activity of three carnitine biosynthesis enzymes (6-N-trimethyllysine dioxygenase, 4-trimethylaminobutyraldehyde dehydrogenase, and 4-trimethylaminobutyric acid dioxygenase) in total homogenates that can be prepared from frozen tissue. The new assays were used to characterize these enzymes in mouse liver homogenate. Because carnitine biosynthesis has been studied extensively in the rat, we compared the mouse tissue distribution of carnitine biosynthesis enzyme activities and levels of the biosynthesis metabolites with those in the rat to determine which tissues contribute to carnitine biosynthesis in these species. Surprisingly, large differences in enzyme activities were found between the rat and the mouse, whereas carnitine biosynthesis metabolite levels were very similar in both species, possibly due to the different kinetic properties of the first enzyme of carnitine biosynthesis. Also, muscle carnitine levels were found to vary considerably between these two species, suggesting that there is a metabolic dissimilarity between the mouse and the rat.     

Analysis of coat-color patterns in aggregation chimeras between BALB/cA and C3H/HeN mice with special reference to migratory patterns and clone number of epidermal melanoblasts

Chimeras provide unique opportunities to study interactions between the phenotypically similar but genotypically allogeneic cell populations during embryogenesis in vivo. From the quantitative analysis of coat-color patterns in C3H/HeN----BALB/cA chimeras, a model was proposed stating that the aggregability of the C3H/HeN-derived melanoblasts in the chimeras was inversely related to the ratio between the mean free path of the epidermal melanoblasts in the normal C3H/HeN mouse and that in the chimeras. As a corollary, the possibility was suggested that during the migration of melanoblasts, mechanisms identical with or similar to contact inhibition of movement might operate after collision between the isogeneic, but not between the allogeneic melanoblasts. With regard to the number of melanoblast clones in the trunk region of the mouse, the present series of analyses yielded the value of 24-28 arranged unilaterally; the value closely approximated the number of the somites in that region and provided further support for the proposition made earlier by Tachi [Dev Genet 9: 121-154, 1988; "Development of Preimplantation Embryos and Their Environment." New York: Alan R. Liss, Inc., 1989, pp 263-274].