Briefly describe the experiment shown in figure 1 (f-h)? Why did they perform th

Question

Briefly describe the experiment shown in figure 1 (f-h)?

Why did they perform this experiment?

How did they perform this experiment?

What did they show with this experiment? Briefly describe what they saw. Just describe what you see! Do not interpret what it means, just make observations about what is shown in the pictures.

So what? What is the main conclusion from the data shown in Figure 1f-h?

expressed in a broad posterior domain located between eve stripes 4 ventral surface of the embryo (Fig. lf, k). The ectopic domain and 6 (Fig. la). In kni mutants, the two-stripe patterns driven by eve directed by this promoter is uniformly distributed along the 3 + 7-lacZ and eve 4 + 6-lacZ reporter genes are completely de- anterior-posterior axis15, and forms a ventral to dorsal gradient of repressed in the region between the stripes68. By contrast, hb is protein diffusion (data not shown). As all seven eve stripes are expressed in an anterior domain that abuts eve 3 and a broad subject to the same increase in protein concentration, differential posterior stripe that overlaps eve 7 (Fig. lb). In zygotic hb mutants, sensitivities among stripes can be assayed directly. Weakly affected there are marked derepressions of the outer borders of the stripes driven by both the eve 3 + 7 and eve 4 + 6 reporter genes68. stripes will be repressed only in the ventral-most nuclei, whereas strongly affected stripes will show repression in more lateral or even To test whether the eve 3 + 7 and eve 4 + 6 enhancers are dorsal regions differentially sensitive to Kni- and Hb-mediated repression, we Ventral expression of either Kni (sna:kni) or Hb (sna:hb) is used the snail(sna) promoter to misexpress these genes along the sufficient for repression of eve stripes 3, 4, 6 and 7 in ventral regions eve 3 eve 4 eve eve eve WT 7 WT 6 WT 3 4 5 kni eve 9 2x sna: hb eve eve sna:hb sna:hb sna:hb Figure 1 Individual eve stripes are differentially responsive to gradients of Kni and Hb. expression pattern of endogenous sna (red). f-o, Expression patterns in embryos a-e, mRNA expression patterns in wild-type embryos at mid-cleavage cycle 14 a, b, Lateral views showing the spatial relationships between hb, kni and eve. c, Ventral embryonic surface.f-h, k-m, Ventral views showing stripe-specific repression (compare view of the expression pattern of eve. Stripes 3-7 are numbered. d, e Lateral views of with c . Affected stripes are marked by asterisks. i n o Lateral views of embryos embryos carrying the eve 3 + 7-lacZ(d) or the eve4 6-lacZ(e) transgenes. Only the carrying the eve 3 + 7-lacZ (i, n) or the eve 46-lacZtransgene (j, o), in addition to regions of stripe 3 or stripe 4 (black) are shown. Embryos are also stained to detect the the sna:kni or sna.hb misexpression constructs (compare with d and e) containing an ectopic domain of Kni (f-i) or Hb (k-o) expression along the ventral

Explanation / Answer

To know whether the enhacers eve 3 + 7 and eve 4 + 6 are dorsal regions distinguishably sensitive to expression mediated by Kni- and Hb.

In this experiment, promoter of snail (sna) for gene misexpression along the embryo's ventral surface. The ectopic domain administered by this promoter is distriuted uniformly along the anterior- posterior axis and produce protein diffusion gradient from ventral to dorsal. As all seven eve stripes are admister to concentration of protein elevated, stripes differential sensitivities evaluated directly. In the ventral most nuclei only, strips that are weakly affected will be repressed, while the stripes that are strongly affected will indicate more lateral or dorsal region repression.

Here scientist shows that conflicting gradients of Hunchback (Hb) and Knirps (Kni) that are two Drosophila transcriptional repressors, situated different segments by distinguishly repressing two specific regulatory regions (enhancers) of the pair-rule gene even-skipped (eve). Computational and in vivo analyses that sensitivity of emhancer to repression is managed by the number as well as affinity of repressor-binding sites. Due to the expression domain of the kni is placed between two Hb gradients of Hb, every enhancer mediates a pair of symmetrical stripes pair expression, one on every kni domain side. Hence, two enhancers are needed for the accurate placement of border of eight stripe (four stripes), or more than half of the overall pattern of eve. Results indicate that developmental pattern of expression complex can be produced by simple gradient of repressor. They also help the use of computational analyses for explaining and analysing regulatory information consist in genomic DNA.

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