Striking variation in the sex ratio of pups born to mice according to whether maternal diet is high in fat or carbohydrate

Abstract

In female mammals, it remains controversial whether maternal diet and particularly the source and availability of energy can influence sex of offspring born. Outbred female mice were fed ad libitum from 30 days to Ϸ45 wk of age on defined, complete diets that differed only in their relative content of fat and carbohydrate to determine whether calorie source influenced litter size and sex ratio of pups. Diet 1 (very high in saturated fat, VHF) provided 60% of calories as fat, mainly lard. Diet 2 (low in saturated fat, LF) was low in fat (10% of calories) but high in carbohydrate. Mice delivered four litters of pups, resulting in a total of 1,048 young born over 108 pregnancies. Gestation length and litter size did not differ between VHF and LF groups and did not change as mice aged. Sex ratio of pups (fraction male) born to mothers on VHF diet was unusually high (0.67) and to mothers on LF diet very low (0.39) over litters 2, 3, and 4. This skewing of sex ratio was related to diets fed and not to body mass of mothers. Age of mothers was an important variable, however. Mice that were first bred at 10 wk of age delivered similar numbers of sons and daughters, whereas virgin mice bred later than 20 wk of age produced litters that were skewed toward males or females according to diet. The data show that the source of calories provided in a nutritionally complete diet to mature female mice can influence sex of offspring born.

Fluorescent in situ hybridization for sex chromosome determination before and after fertilization in mice

“…For several years, this laboratory has been studying mice and ruminant species to determine whether there might be a link between the diet consumed by a mother and the sex of her offspring [ [1][2][3]; Green and Roberts, unpublished work]. A diet high in fat, for example, leads to male-biased litters from mature outbred mice, whereas a diet highly restricted in its fat content has the reverse effect.…”

Experimental alteration of litter sex ratios in a mammal

“…For example, studies investigating diabetes that induce an increase in circulating glucose result in male-biased sex ratios (Machado et al 2001). Furthermore, a recent study showed that a high-fat diet resulted in more sons even when the total caloric value was the same as a low-fat diet (Rosenfeld et al 2003). The role of glucose levels in offspring sex ratio has yet to be tested in vivo.…”

“…Meikle & Westberg 2001) and significant sex ratio variation in line with the TWH has been reported (e.g. Rosenfeld et al 2003).…”

Sex-ratio adjustment in response to local mate competition is achieved through an alteration of egg size in a haplodiploid spider mite

“…In humans, sex differences have also been reported in the placental protein human chorionic gonadotropin (hCG) [10]. Concentration of glucose and other nutrients during early cell division might also influence secondary sex ratio, as higher levels of glucose favour the development and the implantation of male blastocysts, providing a potential mechanism for sex-ratio variation in relation to maternal condition (in bovines [11] and in mice [12,13]). Over the past few years, there has been increasing evidence that females are also able to control the sex of their offspring at conception, thus overcoming the rigid process of chromosomal sex determination (e.g.…”