Correction to: Breaking evolutionary and pleiotropic constraints in mammals: on sloths, manatees and homeotic mutations

Octopod (Octo) is a mutation of the moth Manduca sexta, which results in the homeotic transformation of the ventral surface of the first (A1) and less often the second (A2) abdominal segments in the anterior direction. The extent of the transformation ranges from a slight deformation of the ventral cuticle, up to the formation of miniature thoracic legs on A1. The extent of the transformation is always less within A2 as compared to A1. A genetic analysis revealed that Octo is an autosomal mutation which shows incomplete dominance. The effect of this mutation on the central nervous system (CNS) was assessed by examining the distribution and fate of the postembryonic neuroblasts in the segmental ganglia of Octo larvae. In each of the thoracic ganglia of wild-type larvae, there is a set of 45–47 neuroblasts; a reduced but homologous array of 24 and 10 neuroblasts are found in A1 and A2, respectively. Ganglion A1 of Octo larvae had 1 to 6 supernumerary neuroblasts, and 20% of the A2 ganglia showed a single ectopic neuroblast. The supernumerary neuroblasts corresponded to identifiable neuroblasts normally found in more anterior ganglia. The Octo mutation also influenced the mitotic activity of stem cells normally present in A1. In this case, the neuroblasts generated a lineage of cells that were typical of a thoracic location rather than A1. These data demonstrate that homeotic mutations can influence the fate of identifiable pattern elements within the CNS of an insect.

Download Full-text

Homeotic genes controlling flower development in Antirrhinum

Development ◽

10.1242/dev.113.supplement_1.149 ◽

1991 ◽

Vol 113 (Supplement_1) ◽

pp. 149-155

Author(s):

Enrico S. Coen ◽

Sandra Doyle ◽

Jose M. Romero ◽

Robert Elliott ◽

Ruth Magrath ◽

...

Keyword(s):

Flower Development ◽

Homeotic Genes ◽

Wild Type ◽

Developmental Pathway ◽

The Third ◽

Gene Functions ◽

Overlapping Domains ◽

Second Category ◽

Homeotic Mutations ◽

Primary Gene

In order to study genes controlling flower development, we have carried out an extensive transposon-mutagenesis experiment in Antirrhinum majus. More than 15 independent homeotic mutations were obtained, allowing three categories of genes to be defined. The first includes floricaula (flo), a primary gene required for the initiation of the floral developmental pathway. In the absence of the wild-type flo product, proliferating inflorescence meristems arise in place of flowers. The flo gene has been isolated and shown to be expressed transiently in a subset of organ primordia in the floral meristem. The second category includes genes that affect the identity, and also sometimes the number, of whorls of organs in the flower. These genes act in overlapping domains so that each whorl has a distinct combination of gene functions, suggesting a model for the genetic control of whorl identity and number. Genes of the third category control differences between organs In the same whorl and hence the overall symmetry of the flower. We discuss how the basic plan of the flower and inflorescence may arise through the interactions between the three categories of genes.

Download Full-text

Control of Drosophila adult pattern by extradenticle

Development ◽

10.1242/dev.121.7.2117 ◽

1995 ◽

Vol 121 (7) ◽

pp. 2117-2125 ◽

Cited By ~ 15

Author(s):

S. Gonzalez-Crespo ◽

G. Morata

Keyword(s):

Homeobox Gene ◽

Homeotic Genes ◽

Body Parts ◽

Developmental Processes ◽

Adult Pattern ◽

Homeotic Mutations ◽

Ectopic Eyes

The homeobox gene extradenticle (exd) acts as a cofactor of the homeotic genes in the specification of larval patterns during embryogenesis. To study its role in adult patterns, we have generated clones of mutant exd- cells and examined their effect on the different body parts. In some regions, exd- clones exhibit homeotic transformations similar to those produced by known homeotic mutations such as Ultrabithorax (Ubx), labial (lab), spineless-aristapedia (ssa) or Antennapedia (Antp). In other regions, the lack of exd causes novel homeotic transformations producing ectopic eyes and legs. Moreover, exd is also required for functions normally not associated with homeosis, such as the maintenance of the dorsoventral pattern, the specification of subpatterns in adult appendages or the arrangement of bristles in the mesonotum and genitalia. Our findings indicate that exd is critically involved in adult morphogenesis, not only in the homeotic function but also in several other developmental processes.

Download Full-text