Haag ES (2004) Developmental Cell "Germline imprinting: battle of the sexes or battle of the X's?"

Haag ES

[Developmental Cell, 2004]

The X chromosome is largely inactivated in spermatogenesis of heterogametic males, and in multiple phyla it encodes few genes specifically expressed in the male germline. Writing in Nature Genetics, Bean et al. report a parallel between male germline X inactivation in nematodes and a fungal gene-silencing mechanism that alters the way we view the evolution of both phenomena.

Haag ES et al. (2005) PLoS Biology "Sex determination across evolution: connecting the dots."

Haag ES, Doty AV

[PLoS Biology, 2005]

Haag ES et al. (2013) Adv Exp Med Biol "Using Caenorhabditis to explore the evolution of the germ line."

Liu Q, Haag ES

[Adv Exp Med Biol, 2013]

Germ cells share core attributes and homologous molecular components across animal phyla. Nevertheless, abrupt shifts in reproductive mode often occur that are mediated by the rapid evolution of germ cell properties. Studies of Caenorhabditis nematodes show how the otherwise conserved RNA-binding proteins (RBPs) that regulate germline development and differentiation can undergo surprisingly rapid functional evolution. This occurs even as the narrow biochemical tasks performed by the RBPs remain constant. The biological roles of germline RBPs are thus highly context-dependent, and the inference of archetypal roles from isolated models in different phyla may therefore be premature.

Haag ES (2009) Curr Top Dev Biol "Chapter 3. Caenorhabditis nematodes as a model for the adaptive evolution of germ cells."

Haag ES

[Curr Top Dev Biol, 2009]

A number of major adaptations in animals have been mediated by alteration of germ cells and their immediate derivatives, the gametes. Here, several such cases are discussed, including examples from echinoderms, vertebrates, insects, and nematodes. A feature of germ cells that make their development (and hence evolution) distinct from the soma is the prominent role played by posttranscriptional controls of mRNA translation in the regulation of proliferation and differentiation. This presents a number of special challenges for investigation of the evolution of germline development. Caenorhabditis nematodes represent a particularly favorable system for addressing these challenges, both because of technical advantages and (most importantly) because of natural variation in mating system that is rooted in alterations of germline sex determination. Recent studies that employ comparative genetic methods in this rapidly maturing system are discussed, and likely areas for future progress are identified.