ABSTRACT
Here we describe of a novel Drosophila LTR-type retrotransposon that is expressed in the embryonic CNS midline glia and in the embryonic germ cells. The element is related to the gypsy and burdock retrotransposons and was termed midline-jumper. In addition to cDNA clones generated from internal retrotransposon sequences, we have identified one cDNA clone that appears to reflect a transposition event, indicating that the midline-jumper retrotransposon is not only transcribed but also able to transpose during Drosophila development.
Subject(s)
Central Nervous System/cytology , Central Nervous System/embryology , Retroelements , Animals , DNA, Complementary/metabolism , Drosophila , In Situ Hybridization , Models, Genetic , Neuroglia/metabolismABSTRACT
Salivary glands are simple structured organs which can serve as a model system in the study of organogenesis. Following a large EMS mutagenesis we have identified a number of genes required for normal salivary gland development. Mutations in the locus small salivary glands-1 (ssg-1) lead to a drastic reduction in the size of the salivary glands. The gene ssg-1 was cloned and subsequent sequence and genetic analysis showed identity to the recently published gene brinker. The salivary gland placode in brinker mutants appears reduced along both the anterior-posterior and dorso-ventral axis. Analysis of the brinker cuticle phenotype revealed a similar loss of anterior-posterior as well as lateral cell fates. The abdominal ventral denticle belts show a reduced number of setae in the first denticle row. Furthermore, we observed a preferential loss of lateral neuroblasts in the anterior parasegment. Together, these phenotypes suggest that brinker not only plays a role in dorso-ventral but also in anterior-posterior axis patterning.
Subject(s)
Adhesins, Bacterial , Central Nervous System/embryology , Drosophila Proteins , Drosophila/embryology , Epidermis/embryology , Insect Proteins/genetics , Repressor Proteins , Salivary Glands/embryology , Transcription Factors , Animals , Bacterial Proteins/metabolism , Body Patterning/genetics , Cell Differentiation/genetics , Central Nervous System/cytology , Chromosome Mapping , Drosophila/genetics , Embryo, Nonmammalian , Embryonic Induction/genetics , Epidermal Cells , Gene Expression Regulation, Developmental , Genetic Complementation Test , Homeodomain Proteins/metabolism , Insect Proteins/metabolism , Mutation , Neuropeptides/metabolism , Receptors, Steroid/metabolism , Salivary Glands/abnormalities , Salivary Glands/cytologyABSTRACT
To identify X chromosomal genes required for salivary gland development in the Drosophila embryo, we screened embryos hemizygous for EMS-induced lethal mutations to find mutations causing gross morphological defects in salivary gland development. The parental strain carried a lac Z transgene on the second chromosome, which was specifically expressed in the salivary glands so the mutations could be unambiguously identified. Embryos from 3,383 lines were tested for salivary gland abnormalities following lacZ staining. From 63 lines exhibiting aberrant salivary gland phenotypes, 52 stable lines were established containing mutations affecting salivary gland development. From these, 39 lines could be assigned to nine complementation groups: armadillo, brinker, folded gastrulation, giant, hindsight, Notch, runt, stardust and twisted gastrulation.
