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Biomedical subjects

V F Irish

Publications and source records attributed to V F Irish.

22 records · Page 2Linked to original sources
PubMed1990

Function of the apetala-1 gene during Arabidopsis floral development.

We have characterized the floral phenotypes produced by the recessive homeotic apetala 1-1 (ap1-1) mutation in Arabidopsis. Plants homozygous for this mutation display a homeotic conversion of sepsis into brachts and the concomitant formation of floral buds in the axil of each transformed sepal. In addition, these flowers lack petals. We show that the loss of petal phenotype is due to the failure of petal primordia to be initiated. We have also constructed double mutant combinations with ap1 and other mutations affecting floral development. Based on these results, we suggest that the AP1 and the apetala 2 (AP2) genes may encode similar functions that are required to define the pattern of where floral organs arise, as well as for determinate development of the floral meristem. We propose that the AP1 and AP2 gene products act in concert with the product of the agamous (AG) locus to establish a determinate floral meristem, whereas other homeotic gene products are required for cells to differentiate correctly according to their position. These results extend the proposed role of the homeotic genes in floral development and suggest new models for the establishment of floral pattern.

Arabidopsis↗
PubMed1989

Spatial regulation of the Antennapedia and Ultrabithorax homeotic genes during Drosophila early development.

Both maternally supplied products and zygotically acting segmentation genes are required to establish the segment pattern of the Drosophila embryo. These genes are thought to act in part by regulating the expression of the homeotic genes. Products of the maternal and zygotic gap genes are present in the egg prior to blastoderm formation, when the homeotic genes are initially expressed within precisely bounded domains. In order to assess the first regulatory interactions between some of these gap gene products and the homeotic genes, we have examined the spatial distribution of transcripts arising from the homeotic Antp and Ubx genes during early embryogenesis in various mutant backgrounds. Here we show that mutations in both maternally and zygotically acting gap genes differentially affect the initial spatial domains of transcripts arising from each of these homeotic gene promoters. Later in embryogenesis, the patterns of homeotic gene expression change in both the wild-type and mutant cases, suggesting that other regulatory activities come into play. We propose a model in which the initial activation of each homeotic gene promoter depends on a unique combination of gap and pair-rule gene activities.

Animals↗
PubMed1987

The decapentaplegic gene is required for dorsal-ventral patterning of the Drosophila embryo.

The decapentaplegic gene (dpp), which encodes a growth factor-like protein (Padgett et al. 1987), is implicated in several morphogenetic events in Drosophila melanogaster. We define here a novel embryonic function encoded by dppHin+ alleles of the dpp gene. dppHin null homozygotes die as ventralized embryos. dppHin activity is not required in the maternal germ line since lack of dppHin function during oogenesis has no effect on the zygotic phenotype. Since dppHin null embryos are already abnormal early in gastrulation, the dppHin product is an early-acting, strictly zygotic function involved in establishing the embryonic dorsal-ventral pattern. Several maternally acting dorsalizing genes are thought to be required for the establishment of a dorsal-ventral morphogenetic gradient (Anderson et al. 1985b). We have examined the interactions of dppHin mutations with three of these genes. Embryos null for dppHin and derived from a mother homozygous for a dorsalizing mutation exhibit a lateralized phenotype, indicating that the dorsal-ventral identity of the epidermis in part derives from the direct or indirect regulation of dppHin activity by these genes.

Animals↗