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Genetic information that directs a cell during different phases of embryogenesis is locked up in the genome. Therein is contained the road map for growth, proliferation, differentiation and morphogenesis. The cellular transportation machinery plays a major role to ensure that all the components for transcription and translation are available at the right place at the right time. Nucleolar complex associated protein2 (NOC2) has a highly conserved UPF0120 domain, and is an element involved in ribosome transportation from the nucleoplasm to the cytoplasm. However, its gene expression pattern is still unknown. We chose the developing chick embryo to investigate the possible involvement of avian NOC2 (cNOC2) in developmental processes, particularly neurogenesis and myogenesis. For this purpose, we constructed a fragment of chicken cNOC2, which contains the UPF0120 domain coding sequence, into pDrive vector, and performed in situ hybridization on chicken embryos of different stages with this gene probe. A dynamic expression pattern of cNOC2 transcripts can be seen beginning as early as from stage HH7 until stage HH32. Using in situ hybridization we could detect that cNOC2 transcripts were expressed ubiquitously, but prominent expression could be found in the neural tissue, the somites and in the developing limbs. Comparison of cNOC2 gene expression with the proliferation marker gene cPCNA, muscle specific marker genes cMyf5 and cMyoD in single or double in situ hybridisation show that cNOC2 is expressed in the myotome, similar to cMyf5 and cMyoD, but not like cPCNA, which is hardly detectable in the myotome. Our results suggest that cNOC2 is involved in the development of neural tissue, somites and limbs.

The chemokine receptor CXCR4 plays a decisive role in physiological cell migration both in developmental processes and adult tissues; it has also been implicated in metastasis formation of different human cancers (Balkwill 2004) and in HIV pathogenesis (Murdoch 2000). Here we present the expression pattern of this important chemokine receptor CXCR4 in the chick embryo. A dynamic expression pattern can be detected beginning as early as the gastrulation stages until the observed stage of HH28. During gastrulation, expression was observed in the epiblast at the level of the primitive streak and in the endoderm. Later, expression was noticeable in the ventral foregut portal, developing somites, tail bud, neural tube, the intermediate mesoderm, Wolffian duct, the lateral plate mesoderm and the developing blood vessels. Our descriptive data suggest a role for CXCR4 in gastrulation and other morphogenetic events connected with angiogenesis and kidney development.