A study of monozygous quadruplet armadillos in relation to mammalian inheritance.

Abstract

In 1951, studies in our laboratories revealed, for example, that among Wistar rats that had been brother-sister mated for 101 generations and were consuming exactly the same diet, individual urinary excretion patterns showed wide diversity. As an instance, in a small group of these animals, urinary phosphate excretion varied 11-fold and lysine excretion at least 14-fold.'Other investigations have shown that within groups of closely inbred animals (including fowl), enormous variations-up to 60-fold or more-may readily be observed with respect to such items as the voluntary consumption of alcohol, choices of various types of foodstuffs, and tendency to exercise.2 We have recently been concerned also with the wide differences in the nutritional needs of individual inbred animals for vitamins A and C.3, 4 All these wide disparities call for more adequate explanation.We have wondered whether unknown factors aside from the gene pool itself do not control the intricate process of differentiation, particularly the extent to which each of the numerous types of differentiated cells proliferates. If there is this sort of control, even animals with identical complements of genes could have organs that differ in size, and every hormone could be produced in characteristic amounts in each individual animal, depending upon the extent to which the various hormoneproducing cells had proliferated during development. Hormone patterns are of particular interest because we have some reason to think that hormonal differences are related to several of the areas in which we observe wide differences (food choices, etc.).Clearly it would be difficult to test this interpretation as long as inbred animals with only similar gene pools are studied, because disparities which are observed might always be attributed to slight differences in the gene complements.In order to find a more clear-cut answer to the question, we have studied a number of structural and biochemical parameters in newborn quadruplet armadillos. The reproduction of the nine-banded armadillo has been thoroughly studied by Newman and Patterson,'-7 who found the normal mode to involve the regular production of monozygous quadruplets. Sets of animals are thus produced which should have, barring rare mutations, exactly the same genes. It is interesting that in early work, Newman and Patterson commented on variations in scute numbers and aberrations in banding. These differences, though small, may be highly significant.In the process of producing monozygous quadruplets, the single fertilized ovum develops to the blastocyst stage, later becomes implanted, and four primordial buds are formed in two stages. These develop independently. While the chromosomal material of the zygote is duplicated in these buds, it seems un-910

Insights from animal models on the immunogenetics of leprosy: a review

“…Genetically identical quadruplicates -Armadillos always give birth to genetically identical quadruplicates and a heritable component in the armadillo's response to M. leprae also can be seen among litter-mates (Storrs & Williams 1968). As shown in Table III, seven/eight of the sibling sets that we experimentally infected with M. leprae showed similar susceptibility and manifested similar numbers of bacilli at the time of harvest or removal.…”

Is aging an evolved developmental program?

“…Perhaps the most dramatic example of developmental plasticity was an experiment reported by Storrs and Williams [34]. The nine-banded armadillo normally gives birth to monozygous quadruplets.…”

“…Once the zygote does implant it splits into four genetically identical embryos. Storrs and Williams [34] collected 16 sets of newborn quadruplets, and measured 20 parameters including body weights, organ weights, and neurotransmitter tissue levels. These investigators made the fascinating observation that within the sets of quadruplets there were always differences in the measured parameters.…”

The armadillo: a model for neuropathy of leprosy and potentially other neurodegenerative diseases

“…Studies involving this animal have contributed to our knowledge of embryology (Storrs and Williams, 1968; Peppler and Stone, 1980), reproductive biology (D’Addamio et al, 1977; Peppler and Stone, 1980), immunology (Harboe et al, 1978; Guerra-Infante et al, 1996) and various infectious diseases, including syphilis and Chagas disease (Chaussinand and Besse, 1952; Wicher et al, 1983). However, the nine-banded armadillo has been most exploited as a model for leprosy (Peña et al, 2008; Scollard, 2008).…”