pod-2, along with pod-1, defines a new class of genes required for polarity in the early Caenorhabditis elegans embryo

The asymmetric division of the one-cell Caenorhabditis elegans zygote gives rise to two cells of different size and fate, thereby establishing the ani mal's anterior-posterior (a-p) axis. Through genetics, a number of genes re quired for this polarity have been characterized, but many components remai n unidentified. Recently, our laboratory discovered a mutation in the pod-1 gene (for polarity and osmotic defective) that uniquely perturbed polarity and osmotic protection. Here, we describe a new C. elegans polarity gene i dentified during screens for conditional embryonic lethals. Embryos in whic h this gene has been mutated show a loss of physical and developmental asym metries in the one-cell embryo, including the mislocalization of PAR and PO D-1 proteins required for early polarity. Furthermore, mutant embryos are o smotically sensitive, allowing us to designate this gene pod-2. Thus, pod-2 , along with pod-1, defines a nc rv class of C. elegans polarity genes. Gen etic analyses indicate that pod-2 functions in the same pathway as pod-1. T emperature-shift studies indicate that pod-2 is required during oogenesis, indicating that aspects of embryonic polarization may precede fertilization . pod-2 mutant embryos also exhibit a unique germline inheritance defect in which germline identity localizes to the wrong spot in the one-cell embryo and is therefore inherited by the wrong cell at the four-cell stage. Our d ata suggest that pod-2 may be required to properly position an a-p polarity cue. (C) 2001 Academic Press.