PRP gene variability in the us cattle population

Abstract

The primary amino acid sequence of the prion protein (PrP) has previously been correlated with changes in the incubation period of subacute spongiform encephalopathies. We have analyzed the PrP gene from 65 different cattle representing 14 breeds by polymerase chain reaction and restriction enzyme analysis. Two distinct PrP alleles differing in the number of octapeptide repeats are present. The predominant genotype is homozygous for 6 octapeptide repeats. Few individuals (8) were found to be heterozygous for these repeats and only 1 animal was homozygous for the 5 octapeptide repeat allele.     

Of mast and mean: differential‐temperature cue makes mast seeding insensitive to climate change

Mast‐seeding plants often produce high seed crops the year after a warm spring or summer, but the warm‐temperature model has inconsistent predictive ability. Here, we show for 26 long‐term data sets from five plant families that the temperature difference between the two previous summers (ΔT) better predicts seed crops. This discovery explains how masting species tailor their flowering patterns to sites across altitudinal temperature gradients; predicts that masting will be unaffected by increasing mean temperatures under climate change; improves prediction of impacts on seed consumers; demonstrates that strongly masting species are hypersensitive to climate; explains the rarity of consecutive high‐seed years without invoking resource constraints; and generates hypotheses about physiological mechanisms in plants and insect seed predators. For plants, ΔT has many attributes of an ideal cue. This temperature‐difference model clarifies our understanding of mast seeding under environmental change, and could also be applied to other cues, such as rainfall.