We have performed new simulations of two different scenarios for the excitation and depletion of the primordial asteroid belt, assuming Jupiter and Saturn on initially circular orbits as predicted by the Nice Model of the evolution of the outer Solar System [Gomes, R., Levison, H.F., Tsiganis, K., Morbidelli, A., 2005. Nature 435, 466–469; Tsiganis, K., Gomes, R., Morbidelli, A., Levison, H.F.,...

In mice, primordial germ cells migrate into the genital ridges by embryonic day 13.5 (E13.5), where they are then subjected to a sex-specific fate with female and male primordial germ cells undergoing mitotic arrest and meiosis, respectively. However, the sex-specific basis of primordial germ cell differentiation is poorly understood. The aim of this study was to investigate the sex-specific fe...

The derivation of germ-line competent avian primordial germ cells establishes a cell-based model system for the investigation of germ cell differentiation and the production of genetically modified animals. Current methods to modify primordial germ cells using DNA or retroviral vectors are inefficient and prone to epigenetic silencing. Here, we validate the use of transposable elements for the ...

Recent research has severely constrained the standard “defect” models of cosmic structure formation. Here I discuss the nature of the problems with defect models, and place this discussion in the context of the big picture of cosmic structure formation. In particular, I classify models of cosmic structure formation as either “causal” or “acausal”, and ask whether the problems with the defect mo...

BACKGROUND Little is known about the factors that control the initiation of growth of primordial follicles. Primordial follicles in pieces of fetal bovine ovarian cortex spontaneously activate in vitro and develop to the primary stage, but few follicles develop further. For decades, embryologists have grafted tissue to the chorioallantoic membrane (CAM) of chick embryos to study the development...

An evolutionary tree of key enzymes from the Complex-Iron-Sulfur-Molybdoenzyme (CISM) superfamily distinguishes "ancient" members, i.e. enzymes present already in the last universal common ancestor (LUCA) of prokaryotes, from more recently evolved subfamilies. The majority of the presented subfamilies and, as a consequence, the Molybdo-enzyme superfamily as a whole, appear to have existed in LU...

In females, germ cells are maintained in ovarian structures called primordial follicles. The number of primordial follicles in the ovarian reserve is a critical determinant of the length of the fertile lifespan. Despite this significance, knowledge of the precise physiological mechanisms that regulate primordial follicle number is lacking. In this study we show that a wave of primordial follicl...

Primordial magnetic fields possibly generated in the very early universe are one of the candidates for the origin of magnetic fields observed in many galaxies and galaxy clusters. After recombination, the dissipation process of the primordial magnetic fields increases the baryon temperature. The Lorentz force acts on the residual ions and electrons to generate density fluctuations. These effect...