Physical localization of the mesoderm development (mesd) functional region

The mesoderm development (mesd) functional interval is essential for primit ive streak formation and mesoderm induction. Mesd is defined by overlapping albino (c) deletions on chromosome 7. We have constructed a bacterial arti ficial chromosome (BAC) contig that spans the meed functional region. BAC e nd-sequence identifies three segments that recognize novel expressed sequen ces. Localization of the proximal breakpoints from Del(7)Tyr(c-3YPSd) and D el(7)Tyr(c-112K) within the contig defines a deletion interval of 310-350 k b that is essential for mesd function. Importantly, using BAC transgene res cue, we define a 75-kb mesd critical region containing at least one express ed sequence. (C) 2000 Academic Press.