The results found here highlight the need to consider asexual reproduction along with mixed mating in models of genetic load and mutation-selection balance. (C) 2012
Elsevier Ltd. All rights reserved.”
“BACKGROUND
The onset of puberty is first detected as an increase in pulsatile secretion of gonadotropin-releasing hormone (GnRH). Early activation of the hypothalamic-pituitary-gonadal axis results in central precocious puberty. The timing of pubertal development is driven in part by genetic factors, but selleck products only a few, rare molecular defects associated with central precocious puberty have been identified.
METHODS
We performed whole-exome sequencing in 40 members of 15 families with central precocious puberty. Candidate variants were confirmed with Sanger sequencing. We also performed quantitative real-time polymerase-chain-reaction assays to determine levels of messenger RNA (mRNA) in buy PRN1371 the hypothalami of mice at different ages.
RESULTS
We identified four novel heterozygous mutations in MKRN3, the gene encoding makorin RING-finger protein 3, in 5 of the 15 families; both sexes
were affected. The mutations included three frameshift mutations, predicted to encode truncated proteins, and one missense mutation, predicted to disrupt protein function. MKRN3 is a paternally expressed, imprinted gene located in the Prader-Willi syndrome critical region (chromosome 15q11-q13). All affected persons inherited the mutations from their fathers, a finding that indicates perfect segregation selleck screening library with the mode of inheritance expected
for an imprinted gene. Levels of Mkrn3 mRNA were high in the arcuate nucleus of prepubertal mice, decreased immediately before puberty, and remained low after puberty.
CONCLUSIONS
Deficiency of MKRN3 causes central precocious puberty in humans.”
“An organism can be defined as omnivorous if it feeds on more than one trophic level. Omnivory is present in many ecosystems and multiple omnivorous species can coexist in the same ecosystem. How coexisting omnivores are able to avoid competitive exclusion is very much an open question. In this paper we analyze a model of a community consisting of two omnivorous predators and a basal resource. The population of both predators is explicitly structured into juveniles and adults, of which juveniles only feed on basal resource and adults feed on a varied proportion of basal resource and juveniles of the other population. We thereby separate the omnivorous roles (competitor for basal resource and predator of competitors) over life history. We show in this study that persistence of multiple omnivorous predators is possible when predators differ in adult diets. In this case, coexistence occurs because community dynamics force one of the model species to act as a predator and the other to act as a consumer.