Cross-fostering

Nordenhall K, Dock L, Vahter M. 1998. Cross-fostering study of methyl mercury retention, demethylation and excretion in the neonatal hamster. Pharmacol Toxicol 82 132-136. 

Timed-pregnant rats were dosed with l.Opg TCDD/kg on GD14. One day after birth, litters were cross-fostered to produce control, placental-only, lactational-only, and placental/lactational exposure groups. The DTH response to BSA was assessed in 5-month-old males. In these rats the severity of the suppression of the DTH response was related to the route of TCDD exposure (i.e., placental/lactational > lactational > placental), with suppression occurring only in the males receiving both placental and lactational exposure.128 In order to determine the lowest maternal dose of TCDD required to suppress the DTH response in pups, dams were dosed with 0.1,0.3, or l.Opg TCDD/kg on GD14 and the DTH response to BSA was evaluated in 4- and 14-month-old pups. In the males, suppression was observed at a maternal dose of O.lpg TCDD/kg at 14 months of age, while a maternal dose of 0.3pg TCDD/kg was required to cause suppression in... 

Penn, D. and Potts, W.K. (1998a) MHC-disassortative mating preferences reversed by cross-fostering. Proc. R. Soc. Lond. B 265, 1299-1306. 

Much of the previous research on the role of early olfactory experience on adult odor preferences has used the approach of cross-fostering young pups to a lactating dam of a different species (D Udine 1983). Thus, a shift in preference toward odor of the foster parent indicates that species-specific odors are learned via the early experience with the foster parent. Several important themes have emerged from this literature that shed light on the degree to which species preference is learned during early life. 

McDonald, D. L. and Forslund, L. G. (1978) The development of social preferences in the voles Microtus montanus and Microtus canicaudus effects of cross-fostering. Behav. Biol. 22, 497-508. 

Quadagno, D. M. and Banks, E. M. (1970) The effect of reciprocal cross fostering on the behaviour of two sepcies of rodents, Mus musculus and Baiomys taylori ater. Anim. Behav. 18,379-390. 

Since time immemorial, animal breeders have had to cross-foster motherless lambs or calves, or had to attach newborn mammals to a mother of a different species. They have been aware of odor barriers and developed methods to overcome them. A ewe will accept a non-related lamb if it has been rubbed with the hide or amniotic fluid of her own, perhaps stillborn, lamb. A classical case of successful cross-fostering between species is a technique employed by Peruvian livestock breeders to produce hybrids between alpacas and vicunas. The cross is called paco-vicuM and combines the large quantity of wool of the alpaca with the fine quality of vicufia hair. To breed an alpaca female with a vicufia male, first a male has to be imprinted on alpacas. A newborn male vicuna is covered with the hide of a newborn alpaca and presented to a lactating female alpaca without young. The young vicuna is accepted and nursed on account of his alpaca odor. Successfully raised by his alpaca mother, he will imprint on, and breed with, alpacas when adult. 

Along with eating the afterbirth, female ungulates lick amniotic fluid during and after giving birth. For cross-fostering experiments, it is important to know whether acceptance of amniotic fluid is species specific. In one experiment, ewes accepted food treated with ovine amniotic fluid, also caprine amniotic fluid (albeit less so) at and after parturition, but always rejected bovine amniotic fluid (Arnould etal, 1991). 

Wigger A, Loerscher P, Weissenbacher P, Holsboer F, Landgraf R (2001) Cross-fostering and cross-breeding of HAB and LAB rats a genetic rat model of anxiety. Behav Genet... 

Cross-fostering adoption studies have similarly demonstrated support for a genetic contribution to risk for developing alcohol or drug abuse problems. In an examination of 913 women adopted by nonrelatives at an early age Bohman and colleagues (1981) found a... 

Bohman, M., Sigvardsson, S., and Cloninger, C.R. (1981) Maternal inheritance of alcohol abuse cross-fostering analysis of adopted women. Arch Gen Psychiatry 38 965-969. 

There are also cross-fostering studies of children of schizophrenic parents, adopted away by nonschizophrenic foster parents, who were compared with adopted children of normal parents raised by schizophrenic foster parents ( 53, 54). Invariably, those children whose biological parents had schizophrenia developed this disorder more frequently than the offspring of nonschizophrenic parents, even when the latter were reared by schizophrenic foster families. In addition, the concordance rate for the illness in schizophrenic monozygotic twins reared apart was comparable with monozygotic twins reared together. These findings leave little doubt of a hereditary factor in schizophrenia. 

Because both males and females are treated in this type of study design, it is not possible to distinguish between maternal and paternal effects in the reproductive performance. To permit this separation, it is necessary to dose additional animals to the stage of mating and then breed them to untreated members of the opposite sex. Similarly, if effects are seen postnatally, it may not be possible to distinguish between effects mediated in utero or mediated by lactation. This distinction can be made by cross-fostering the offspring of treated females to untreated females, and vice versa. 

Wolf CJ, Fenton SE, Schmid JE, Calafat AM, Kuklenyik Z, Bryant XA, Thibodeaux J, Das KP, White SS, Lau CS, Abbott BD. Developmental toxicity of perfluorooctanoic acid in the CD-I mouse after cross-foster and restricted gestational exposures. Toxicological Sciences 2007, 95, 462 -73. 

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