Concept explainers
Figure 18.6 shows a picture of Glofish ®, transgenic zebrafish (Danio rerio) that express GFP, RFP, and some of their derivatives. Glofish® were the first GM pets. Genes can be transferred into the zebrafish genome using a transposable element called Tol2 from medaka fish (Oryzias latipes). The Tol2 transposon serves as a vector for gene transfer in a manner similar to Drosophila P elements as shown in Fig. 18.4. To use the Tol2 vector, researchers inject two-cell stage zebrafish embryos with two DNAs: One DNA expresses the Tol2 transposase gene, while the other recombinant transposon contains the transgene. If the transposon hops into a chromosome of a germ-line cell, a stable line of transgenic fish can be established.
Scientists have synthesized several different genes encoding derivatives of GFP and RFP. The derivatives have amino acid changes that alter their color, so that fish glowing green, red, orange, blue, or purple are available in many pet stores.
a. | Diagram the two recombinant DNA constructs needed to generate the fluorescent fish. |
b | Why is a transposon from medaka fish used rather than a zebrafish transposon? |
Want to see the full answer?
Check out a sample textbook solutionChapter 18 Solutions
Genetics: From Genes to Genomes
- A research group is studying a bacterium X that binds to mucosal cells in the lung and invades. Wildtype X has an LD50 value of 10 bacteria when administered to mice by inhalation. Using transposon mutagenesis, the researchers have isolated two mutants of X that they call Xmut1 and Xmut2, both of which have LD50 values of 105 when inhaled by mice. However, in tissue culture cells, Xmut1 can invade the cells just as well as wild-type X, while Xmut2 cannot. Provide a possible explanation for these results.arrow_forwardArsenic is a toxic element found in both aquatic and terrestrial environments. Scientists have found genes that allow bacteria to remove arsenic from their cytoplasm. Arsenic enters cells as arsenate that must be converted to arsenite to leave cells. Figure 1 provides a summary of the arsenic resistance genes found in the operons of three different bacteria. E. coli R773 is found in environments with low arsenic levels. Herminiimonas arsenicoxydans and Ochrobactrum tritici are both found in arsenic‑rich environments. Researchers claim that bacteria that live in environments heavily contaminated with arsenic are more efficient at processing arsenic into arsenite and removing this toxin from their cells. Justify this claim based on the evidence shown in Figure 1. Both H. arsenicoxydans and O. tritici contain the arsR gene that codes for a repressor that turns on the operon to eliminate arsenite from the cell. Both O. tritici and E. coli contain the…arrow_forwardA graduate student studying the pathogenic bacteria Acinetobacter baumannii made cDNA from planktonic cells and biofilm cells and performed RNA-Seq on both samples. She aligned her sequencing reads to a locus of the baumannii genome as shown. a. Which genes are on an operon together? Explain which data supports this? b. What is the most expressed transcript from the locus in Planktonic culture? c. Order the transcripts from largest increase in relative expression between biofilm and planktonic cells to the largest decrease in relative expression. d. When this data was compared to microarray transcriptional profiling, the microarray data provided lower expression levels for the most highly expressed transcripts. Why did this occur?arrow_forward
- In the bacteriophage T7 system used to express recombinant proteins, the gene of interest is fused to T7 promoter and T7 RNA polymerase is separately cloned into the same cell. What is the main reason this system uses T7 RNA polymerase instead of relying on the bacterial RNA polymerase? To restrict the expression of bacterial protein expression To enhance the amount of recombinant protein expression To enhance the expression of bacterial protein expression To restrict the amount of recombinant protein expression To enable the expression of T7 viral protein expressionarrow_forwardResearchers have identified a gene (FR) responsible for watermelon resistance to infection by Dacus curcurbitae (a close relative of Drosophila melanogaster). They isolate RNA from resistant (FR+) and sensitive (fr-) watermelons and use a probe that will recognize both FR+ and fr- transcripts. They also isolate protein from resistant and sensitive watermelons and perform a Western blot using an antibody that can recognize the fr- and FR+ protein. Describe the results illustrated below and give a plausible molecular explanation for these observations.arrow_forwardAustin Taylor and Edward Adelberg isolated some new strains of Hfr cells that they then used to map several genes in Escherichia coli by using interrupted conjugation. In one experiment, the researchers mixed cells of Hfr strain AB‑312, which were xyl+ mtl+ mal+ met+ and sensitive to phage T6, with F− strain AB‑531, which was xyl− mtl− mal− met− and resistant to phage T6. The cells were allowed to undergo conjugation. At regular intervals, the researchers removed a sample of cells and interrupted conjugation by killing the Hfr cells with phage T6. The F− cells, which were resistant to phage T6, survived and were then tested for the presence of genes transferred from the Hfr strain. The results of this experiment are shown in the graph. On the basis of these data, give the order of the xyl, mtl, mal, and met genes on the bacterial chromosome and the minimum distances between them in minutes. The origin of transfer is represented by the red triangle. The distances between genes are not…arrow_forward
- Explain the difference between gene modification and gene addition.Are the following examples of gene modification or gene addition?A. A mouse model to study cystic fibrosisB. Introduction of a pesticide-resistance gene into corn using theT-DNA vector of A. tumefaciensarrow_forwardYou are employed in a gene therapy laboratory to test the effectiveness of a vector for correcting the DF508 –CFTR mutation. The vector uses CRISPR –CAS9 genome editing to correct the mutated gene in situ (CFTR-CRISPR). An Ussing chamber experiment was performed using nasal airway cells obtained from a patient with the DF508 CFTR mutation which were transformed with either a control vector consisting of an inert CRISPR-CAS-9 construct (CONTROL) or the active, gene correcting CRISPR CAS-9 construct (CFTR-CRISPR). The following transepithelial voltage values were obtained for the drug regimen shown under open circuit and current clamp (injected current of 10mA) conditions: CONTROL Baseline Amiloride Forskolin Inh172 Vte (mV) -78 -2 -4 -3 DVRt (mV) 8 16 7.5 13 R (W.cm-2) 800 1600 750 1300 I (mA.cm-2) 98 1 5 2 CFTR-CRISPR Vte (mV) -38 -6 -23 -9 DVRt (mV) 9 27 6 11 R (W.cm-2) 900 2700 600…arrow_forwardYou are employed in a gene therapy laboratory to test the effectiveness of a vector for correcting the DF508 –CFTR mutation. The vector uses CRISPR –CAS9 genome editing to correct the mutated gene in situ (CFTR-CRISPR). An Ussing chamber experiment was performed using nasal airway cells obtained from a patient with the DF508 CFTR mutation which were transformed with either a control vector consisting of an inert CRISPR-CAS-9 construct (CONTROL) or the active, gene correcting CRISPR CAS-9 construct (CFTR-CRISPR). The following transepithelial voltage values were obtained for the drug regimen shown under open circuit and current clamp (injected current of 10mA) conditions: CONTROL Baseline Amiloride Forskolin Inh172 Vte (mV) -78 -2 -4 -3 DVRt (mV) 8 16 7.5 13 R (W.cm-2) 800 1600 750 1300 I (mA.cm-2) 98 1 5 2 CFTR-CRISPR Vte (mV) -38 -6 -23 -9 DVRt (mV) 9 27 6 11 R (W.cm-2) 900 2700 600…arrow_forward
- You are employed in a gene therapy laboratory to test the effectiveness of a vector for correcting the DF508 –CFTR mutation. The vector uses CRISPR –CAS9 genome editing to correct the mutated gene in situ (CFTR-CRISPR). An Ussing chamber experiment was performed using nasal airway cells obtained from a patient with the DF508 CFTR mutation which were transformed with either a control vector consisting of an inert CRISPR-CAS-9 construct (CONTROL) or the active, gene correcting CRISPR CAS-9 construct (CFTR-CRISPR). The following transepithelial voltage values were obtained for the drug regimen shown under open circuit and current clamp (injected current of 10mA) conditions: CONTROL Baseline Amiloride Forskolin Inh172 Vte (mV) -78 -2 -4 -3 DVRt (mV) 8 16 7.5 13 R (W.cm-2) 800 1600 750 1300 I (mA.cm-2) 98 1 5 2 CFTR-CRISPR Vte (mV) -38 -6 -23 -9 DVRt (mV) 9 27 6 11 R (W.cm-2) 900 2700 600…arrow_forwardYou are employed in a gene therapy laboratory to test the effectiveness of a vector for correcting the DF508 –CFTR mutation. The vector uses CRISPR –CAS9 genome editing to correct the mutated gene in situ (CFTR-CRISPR). An Ussing chamber experiment was performed using nasal airway cells obtained from a patient with the DF508 CFTR mutation which were transformed with either a control vector consisting of an inert CRISPR-CAS-9 construct (CONTROL) or the active, gene correcting CRISPR CAS-9 construct (CFTR-CRISPR). The following transepithelial voltage values were obtained for the drug regimen shown under open circuit and current clamp (injected current of 10mA) conditions: CONTROL Baseline Amiloride Forskolin Inh172 Vte (mV) -78 -2 -4 -3 DVRt (mV) 8 16 7.5 13 R (W.cm-2) 800 1600 750 1300 I (mA.cm-2) 98 1 5 2 CFTR-CRISPR Vte (mV) -38 -6 -23 -9 DVRt (mV) 9 27 6 11 R (W.cm-2) 900 2700 600…arrow_forwardYou are employed in a gene therapy laboratory to test the effectiveness of a vector for correcting the DF508 –CFTR mutation. The vector uses CRISPR –CAS9 genome editing to correct the mutated gene in situ (CFTR-CRISPR). An Ussing chamber experiment was performed using nasal airway cells obtained from a patient with the DF508 CFTR mutation which were transformed with either a control vector consisting of an inert CRISPR-CAS-9 construct (CONTROL) or the active, gene correcting CRISPR CAS-9 construct (CFTR-CRISPR). The following transepithelial voltage values were obtained for the drug regimen shown under open circuit and current clamp (injected current of 10mA) conditions: CONTROL Baseline Amiloride Forskolin Inh172 Vte (mV) -78 -2 -4 -3 DVRt (mV) 8 16 7.5 13 R (W.cm-2) 800 1600 750 1300 I (mA.cm-2) 98 1 5 2 CFTR-CRISPR Vte (mV) -38 -6 -23 -9 DVRt (mV) 9 27 6 11 R (W.cm-2) 900 2700 600…arrow_forward
- Biology Today and Tomorrow without Physiology (Mi...BiologyISBN:9781305117396Author:Cecie Starr, Christine Evers, Lisa StarrPublisher:Cengage Learning