A major role for zygotichunchbackin patterning theNasoniaembryo

Abstract

Developmental genetic analysis has shown that embryos of the parasitoid wasp Nasonia vitripennis depend more on zygotic gene products to direct axial patterning than do Drosophila embryos. In Drosophila, anterior axial patterning is largely established by bicoid, a rapidly evolving maternal-effect gene, working with hunchback, which is expressed both maternally and zygotically. Here,we focus on a comparative analysis of Nasonia hunchback function and expression. We find that a lesion in Nasonia hunchback is responsible for the severe zygotic headless mutant phenotype, in which most head structures and the thorax are deleted, as are the three most posterior abdominal segments. This defines a major role for zygotic Nasonia hunchback in anterior patterning, more extensive than the functions described for hunchback in Drosophila or Tribolium. Despite the major zygotic role of Nasonia hunchback, we find that it is strongly expressed maternally, as well as zygotically. NasoniaHunchback embryonic expression appears to be generally conserved; however, the mRNA expression differs from that of Drosophila hunchback in the early blastoderm. We also find that the maternal hunchback message decays at an earlier developmental stage in Nasonia than in Drosophila, which could reduce the relative influence of maternal products in Nasonia embryos. Finally, we extend the comparisons of Nasonia and Drosophila hunchback mutant phenotypes, and propose that the more severe Nasonia hunchback mutant phenotype may be a consequence of differences in functionally overlapping regulatory circuitry.

AcaudalmRNA gradient controls posterior development in the waspNasonia

“…3H). Similarly, in the zygotic Nvit hb hl mutant (Pultz et al, 2005), the posterior Nvit cad stripe is duplicated at the anterior of the embryo. Additionally, faint Nvit cad staining spans the region between the wild-type posterior Nvit cad stripe and the ectopic anterior Nvit cad stripe (Fig.…”

“…To determine whether head only was linked with Nv caudal, degenerate PCR was used to also clone caudal from the sister species Nasonia giraulti (Ng) for molecular mapping (Pultz et al, 2005). A polymorphism distinguishing the Nv and Ng caudal was detected by Ambion RNAse Mismatch Detect II kit.…”

“…This parasitic wasp is a model system where a forwards genetic screen and functional parental RNAi studies have been performed (Pultz et al, 1999;Pultz et al, 2000;Pultz et al, 2005;Lynch et al, 2006a;Lynch et al, 2006b). Nasonia uses a long-germ mode of embryogenesis similar to that of highly derived Drosophila.…”

The Expanding Genetic Toolbox of the Wasp Nasonia vitripennis and Its Relatives

“…Nasonia have a small number of chromosomes (five) and the advantage of haploid males, which greatly aid in screening for recessive mutations because phenotypes can be screened in the male progeny of F 1 females ( Figure 3A). The advantages of haploidy have already been demonstrated by Mary Anne Pultz, whose screens generated and identified many interesting mutations affecting embryonic patterning (Pultz et al 1999(Pultz et al , 2000(Pultz et al , 2005.…”

“…Embryogenesis is also quite rapid in these wasps, with larvae emerging a little more than 24 hr after egg laying (Pultz et al 2005). After larval emergence, the wasps begin to feed on the host hemolymph and undergo up to four larval instars before the onset of pupation (Pultz and Leaf 2003) (Figure 1).…”