systems
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A comparison of the present bulge data with DLAs is possible thanks to the availability of a large data base of Zn abundances over a wide range of metallicities for these objects. Such a comparison can shed light not only on the nature of DLAs, but also on the formation process of bulges.

The high H I column densities that characterize the DLAs indicate that they belong to environments with relatively high gas density, which could give rise to components of present day massive galaxies. The presence of metals in their spectra is also a clue that star formation has already taken place at significant rates inside them or in their neighbourhood. In this way, two favoured candidates for sites hosting DLAs are proto-disks and young star-forming spheroids. Lanfranchi and Friaça (2003) have investigated the evolution of the metallicity of DLAs in order to set constraints on the nature of these objects and also to shed light on the connections between DLAs and galaxy formation. The comparison of the observed trends of \[$\alpha$/Fe\] and \[N/$\alpha$\] with the predictions of a chemo-dynamical model is consistent with a scenario in which the DLA population is dominated by disks at low 