Survival of the thriftiest: restricted nurture reveals the thrifty nature of a growth gene in Bos indicus.

Growth hormone (GH) is a part of the somatotropic axis that controls metabolism, growth, development and aging in a wide range of animals. Mutations that reduce GH signaling have been associated with extended life spans and increased longevity in ways similar to what is observed in dietary restriction (DR) models. However, the mechanism by which DR works is not well understood. Here, we show that DR works as a factor in the evolution of the genetic make-up of domestic cattle. In a series of 6864 bovines of seven Bos indicus and tropically adapted Bos taurus breeds, the frequency of a short, wild-type allele of the promoter region of the bovine GH gene, G1 allele, varied from 2.7 to 17.7%. The frequency of the long, domestic G2 allele increased from 88 to 95% along 20 calf crops of commercial Bos indicus cattle of the Nelore breed undergoing selection for increasing post-weaning weight gain with ad libitum nutrient intake. Under DR, however, the G1 allele sustained growth better than the G2 allele, as observed in a series of feeding tests. The G2 allele was even detrimental or abiotropic, as it caused rapid body decay under DR. We observed a reflection symmetry of GH allele substitution effects on body weight under different dietary schemes. The G2 allele is featured as the "demanding allele", because it is optimally fitted to ad libitum nutrient intake. The G1 allele is featured as the "thrifty allele" because it is optimally fitted to DR. Our results show that dietary regimens need not extend lifespan or increase longevity in the sense of age-specific fitness. Instead, adaptation to any particular dietary regimen is just as much a consequence of selection as its cause; dietary regimens work as do any selection force, optimizing genotypic fitness to nutritional conditions.

Speaking mode variability in multimodal speech production.

The speech acoustics and the phonetically relevant motion of the face during speech are determined by the time-varying behavior of the vocal tract. A benefit of this linkage is that we are able to estimate face motion from the spectral acoustics during speech production using simple neural networks. Thus far, however, the scope of reliable estimation has been limited to individual sentences; network training degrades sharply when multiple sentences are analyzed together. While there is a number of potential avenues for improving network generalization, this paper investigates the possibility that the experimental recording procedures introduce artificial boundary constraints between sentence length utterances. Specifically, the same sentence materials were recorded individually and as part of longer, paragraph length utterances. The scope of reliable network estimation was found to depend both on the length of the utterance (sentence versus paragraph) and, not surprisingly, on phonetic content: estimation of face motion from speech acoustics was reliable for larger sentence training sets when sentences were recorded in continuous paragraph readings; and greater phonetic diversity reduced reliability.