What is the Syncytium structure of the Drosophila embryo?
In early development, Drosophila melanogaster embryos form a syncytium, i.e., multiplying nuclei are not yet separated by cell membranes, but are interconnected by cytoskeletal polymer networks consisting of actin and microtubules.
What is a syncytial blastoderm?
During these stages of nuclear division, the embryo is called a syncytial blastoderm, meaning that all the cleavage nuclei are contained within a common cytoplasm. No cell membranes exist other than that of the egg itself.
What is the role of maternal genes in the development of Drosophila?
Bicoid and Hunchback are the maternal effect genes that are most important for patterning of anterior parts (head and thorax) of the Drosophila embryo. Nanos and Caudal are maternal effect genes that are important in the formation of more posterior abdominal segments of the Drosophila embryo.
What are the different stages of development of Drosophila?
The Drosophila life cycle is divided into four stages: embryo, larva, pupa, and adult.
What is pattern formation in Drosophila?
During the early stages of drosophila (or fruit fly) embryonic development, pattern formation determines how the fly will develop into an adult fly based on a specific planned spatial arrangement. Pattern formation is controlled by gene expression, which begins before an egg is fertilized.
What does Hunchback protein do?
The Hunchback protein, also a transcription factor, represses abdominal-specific genes, thereby allowing the region of hunchback expression to form the head and thorax. The Hunchback protein also works with Bicoid in generating the anterior pattern of the embryo.
What is cellular blastoderm?
At the end of the 13th division, membranes grow inward from the cell surface to surround the nuclei. This large-scale form of cytokinesis, called cellularization, results in the formation of a layer of about 6,000 cells beneath the embryo’s surface. This is the cellular blastoderm.
What is a Syncytium and how does this influence the early development of Drosophila?
Drosophila Begins Its Development as a Syncytium
Like the eggs of other insects, but unlike vertebrates, it begins its development in an unusual way: a series of nuclear divisions without cell division creates a syncytium. The early nuclear divisions are synchronous and extremely rapid, occurring about every 8 minutes.
How does a maternal effect gene effect embryo development?
Maternal effect genes produce mRNA or proteins that accumulate in the egg during oogenesis. We show here that Mater, a mouse oocyte protein dependent on the maternal genome, is essential for embryonic development beyond the two-cell stage. Females lacking the maternal effect gene Mater are sterile.
Why is propionic acid used in Drosophila culture?
Propionic acid in the culture medium improves larval survival and supports growth. (a) Analysis of the pupariation rate (graph in the left) and pupal volume (graph in the right) in a normal medium (6.5% yeast).
What regulates gap genes?
Gap genes are regulated by the maternal gradients, so their expression appears to be hardwired to the spatial (positional) cues provided by the maternal gradients [1]; in addition, gap genes are involved into mutual repression [2].
Is Hunchback an activator or repressor?
The hunchback protein is a strikingly concentration-dependent activator of transcription, capable of functioning both by itself and also synergistically with the pair-rule proteins fushi tarazu and paired.
Is hunchback a gap gene?
The gap genes include hunchback, kruppel and knirps, which define relatively broad regions of the embryo – two to four future segments.
What is the difference between blastoderm and blastodisc?
On the surface of every egg yolk there can be seen a tiny, whitish spot called the blastodisc. This contains a single female cell. If sperm is present when a yolk enters the infundibulum, a single sperm penetrates the blastodisc, fertilizing it and the blastodisc becomes a blastoderm.
What defines a morphogen?
A morphogen is defined as signaling molecules (proteins or otherwise) that act over long distances to induce responses in cells based on the concentration of morphogen that the cells interact with (Rogers and Schier, 2011).
What controls the initial course of development in Drosophila quizlet?
Two different sets of genes control embryonic development in Drosophila: maternal-effec genes and zygotic genes.
What would happen the Drosophila larvae if the bicoid gene is not expressed?
Abstract. The Drosophila gene bicoid functions as the anterior body pattern organizer of Drosophila. Embryos lacking maternally expressed bicoid fail to develop anterior segments including head and thorax.
What is the difference between maternal effect and maternal inheritance?
Those phenotypes that are controlled by nuclear factors found in the cytoplasm of the female are said to express a maternal effect. Those phenotypes controlled by organelle genes exhibit maternal inheritance.
What is the difference between maternal genes and zygotic genes?
Maternal genes are transcribed and stored as maternal RNA during oogenesis. Depending on the organism, these maternal mRNAs are translated after oocyte maturation or fertilization. Zygotic genes are transcribed after fertilization (in some cases as late as the midblastula transition).
What is Drosophila medium made of?
This is the recipe for the fly food we use at the fly facility: Media Preparation: Weigh corn flour, D-Glucose, Sugar, Agar and yeast powder separately and keep them aside.
How is culture media prepared for Drosophila?
For the culture of Drosophila, molten medium is poured into bottles or flasks to a depth of about 2 inches. After the medium is poured into bottles, strips of filter paper cut to the length of bottle are inserted to provide a place for the flies to pupate.
Why gap genes are called so?
A gap gene is a type of gene involved in the development of the segmented embryos of some arthropods. Gap genes are defined by the effect of a mutation in that gene, which causes the loss of contiguous body segments, resembling a gap in the normal body plan.
What are gap genes and pair-rule genes?
Gap genes are expressed early in development in broad regions. Pair-rule genes are expressed later in development to define the edges of individual segments. Next, segment polarity genes are expressed even later in development to create polarity within individual segments.
What does hunchback do in Drosophila?
Summary: Hunchback is a bifunctional transcription factor that can activate and repress gene expression in Drosophila development. This study investigated the regulatory DNA sequence features that control Hunchback function by perturbing enhancers for one of its target genes, even-skipped (eve).