The process of germ band extension pushes the posterior end over dorsal side. The first signs of segmentation grooves appear to outline parasegments which give rise to segments. Segments are formed from the posterior of one parasegment and the anterior of the next.
What is Drosophila segmentation?
Segmentation in Drosophila is a sequential process directed by at least 30 genes that encode various types of proteins, including: many transcription factors; a putative RNA-binding protein; a membrane-associated receptor kinase; several intracellular protein kinases; a number of secreted signaling molecules; and …
What is body segmentation in Drosophila controlled by?
For instance, over the past 25 years, more than 40 genes have been identified as playing a role in segmentation in Drosophila melanogaster (Peel et al., 2005). Segmentation in fruit flies is controlled by a cascade of transcription factors, some of which have been found in other arthropods.
What is the role of morphogens in development?
Morphogens are substances that establish a graded distribution and elicit distinct cellular responses in a dose dependent manner. They function to provide individual cells within a field with positional information, which is interpreted to give rise to spatial patterns.
What is the life cycle of Drosophila?
The Drosophila life cycle is divided into four stages: embryo, larva, pupa, and adult. The time length of the stages is approximate and is shown in hours for embryos and days for larvae and pupae.
Are gap genes Morphogens?
The transition from an embryo characterized by gradients of morphogens to an embryo with distinct units is accomplished by the products of the gap genes. The gap genes are activated or repressed by the maternal effect genes, and they divide the embryo into broad regions, each containing several parasegment primordia.
Is caudal a gap gene?
Gap genes constitute the first layer of the Drosophila segmentation gene hierarchy, downstream of maternal gradients such as that of Caudal (Cad).
What happens if gap genes mutate?
If a gap gene is mutated (inactivated), the corresponding broad region of the embryo does not develop and a “gap” in the pattern results. The Gap genes encode transcription factors of the zinc-finger class.
Which is a function of gap genes in Drosophila?
The gap gene system controls the early cascade of the segmentation pathway in Drosophila melanogaster as well as other insects. Owing to its tractability and key role in embryo patterning, this system has been the focus for both computational modelers and experimentalists.
What do selector genes do?
Selector proteins regulate the formation and identity of animal body regions, organs, tissues, and cell types. Recent studies have focused on the regulation of the DNA binding and transcriptional regulatory activity of this special class of transcription factors.