Concept explainers
Enhanced Spatial Learning in Mice With an Autism Mutation Autism is a neurobiological disorder with symptoms that include impaired social interactions and stereotyped patterns of behavior. Around 10 percent of autistic people have an extraordinary skill or talent such as greatly enhanced memory.
Mutations in neuroligin 3, an adhesion protein that connects brain cells to one another, have been associated with autism. One mutation changes amino acid 451 from arginine to cysteine. In 2007, Katsuhiko Tabuchi and his colleagues genetically modified mice to carry the same arginine-to-cysteine substitution in their neuroligin 3. Mice with the mutation had impaired social behavior.
To test spatial learning ability, the mice were placed in a water maze: a deep pool of warm water in which a platform is submerged a few millimeters below the surface. The platform is not visible to swimming mice. Mice do not particularly enjoy swimming, so they locate a hidden platform as fast as they can. When tested again, they can remember its location by checking visual cues around the edge of the pool. How quickly they remember the platform’s location is a measure of spatial learning ability (FIGURE 15.18).
FIGURE 15.18 spatial learning ability in mica mutation in neuroligin 3 (R451C), compared with unmodified (wild-type) mica.
1. In the first, how many days did it take unmodified mice to learn to find the location of the hidden platform within 10 seconds?
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Biology: The Unity and Diversity of Life (MindTap Course List)
- Enhanced Spatial Learning in Mice With an Autism Mutation Autism is a neurobiological disorder with symptoms that include impaired social interactions and stereotyped patterns of behavior. Around 10 percent of autistic people have an extraordinary skill or talent such as greatly enhanced memory. Mutations in neuroligin 3, an adhesion protein that connects brain cells to one another, have been associated with autism. One mutation changes amino acid 451 from arginine to cysteine. In 2007, Katsuhiko Tabuchi and his colleagues genetically modified mice to carry the same arginine-to-cysteine substitution in their neuroligin 3. Mice with the mutation had impaired social behavior. To test spatial learning ability, the mice were placed in a water maze: a deep pool of warm water in which a platform is submerged a few millimeters below the surface. The platform is not visible to swimming mice. Mice do not particularly enjoy swimming, so they locate a hidden platform as fast as they can. When tested again, they can remember its location by checking visual cues around the edge of the pool. How quickly they remember the platforms location is a measure of spatial learning ability (FIGURE 15.18). FIGURE 15.18 spatial learning ability in mica mutation in neuroligin 3 (R451C), compared with unmodified (wild-type) mica. 2. Did the modified or the unmodified mice learn the location of the platform faster in the first test?arrow_forwardEnhanced Spatial Learning Ability in Mice Engineered to Carry an Autism Mutation Autism is a neurobiological disorder with symptoms that include impaired social interactions and repetitive, stereotyped patterns of behavior. Around 10 percent of autistic people also have an extraordinary skill or talent such as greatly enhanced memory. Mutations in the gene for neuroligin 3, an adhesion protein that connects brain cells, have been associated with autism. One of these mutations is called R451C because the altered gene encodes a protein with an amino acid substitution: a cysteine (C) instead of an arginine (R) in position 451. In 2007, Katsuhiko Tabuchi and his colleagues introduced the R451C mutation into the neuroligin 3 gene of mice. The researchers discovered that the genetically modified mice had impaired social behavior and superior spatial learning ability. Spatial learning in mice is tested with a water maze, which consists of a small platform submerged a bit below the surface or a pool of water so it is invisible to a swimming mouse. Mice do not particularly enjoy swimming, so they try to locate the hidden platform as quickly as they can. When tested again later, they remember the platforms location by checking visual cues around the edge or the pool. How quickly they remember is a measure of their spatial learning ability. FIGURE 15.14 shows some or Tabuchis result. FIGURE 15.14 Spatial learning ability in mice. Mice with a mutation in neuroligin 3 (R451C) were tested for learning performance: as compared with unmodified (wild-type) mice. Did the modified or the unmodified mice learn the location of the platform faster in the first test?arrow_forwardTwo types of mutations discussed in this chapter are (1) nucleotide changes and (2) unstable genome regions that undergo dynamic changes. Describe each type of mutation.arrow_forward
- Diamond–Blackfan anemia (DBA) is a rare, dominant genetic disorder characterized by bone marrow malfunction, birth defects, and a predisposition to certain cancers. Infants with DBA usually develop anemia in the first year of life, have lower than normal production of red blood cells in their bone marrow, and have a high risk of developing leukemia and bone cancer. At the molecular level, DBA is caused by mutations in any one of 10 genes that encode ribosomal proteins. The first-line therapy for DBA is steroid treatment, but more than half of affected children develop resistance to the drugs and in these cases, treatment is halted. DBA can be treated successfully with bone marrow or stem cell transplants from donors with closely matching immune system markers. Trans- plants from unrelated donors have significant levels of complications and mortality. 1. Given that a faulty ribosomal protein is the culprit and causes DBA, discuss the possible role of normal ribosomal proteins. Why might…arrow_forwardDiamond–Blackfan anemia (DBA) is a rare, dominant genetic disorder characterized by bone marrow malfunction, birth defects, and a predisposition to certain cancers. Infants with DBA usually develop anemia in the first year of life, have lower than normal production of red blood cells in their bone marrow, and have a high risk of developing leukemia and bone cancer. At the molecular level, DBA is caused by mutations in any one of 10 genes that encode ribosomal proteins. The first-line therapy for DBA is steroid treatment, but more than half of affected children develop resistance to the drugs and in these cases, treatment is halted. DBA can be treated successfully with bone marrow or stem cell transplants from donors with closely matching immune system markers. Trans- plants from unrelated donors have significant levels of complications and mortality. QUESTIONS: 1. Given that a faulty ribosomal protein is the culprit and causes DBA, discuss the possible role of normal ribosomal…arrow_forwardMutations within the genes for ARSs, are known to be cause certain human maladies, such as the neurodegenerative disorder Charcot-Marie-Tooth (CMT) disease along with other central nervous system dysfunctions, and cancer. Interestingly, not all those who possess mutations within specific ARS genes do not display the disease phenotype. Provide at least one reason why a person might survive. Remember, do not just name a concept. Describe the concept and then explain WHY (on a molecular level) this explanation holds true.arrow_forward
- Based on standard MS- LS3-1: Fish in a cave system in Mexico is missing its eyes, has thin, translucent skin, and is relatively small (7-10 cm in length). Can you describe by model why structural changes to genes (mutations) on chromosomes may affect proteins and may result in beneficial effects to the structure and function of the fish? Can you answer in the following format? 1- Structure How Structure and Function is Affected by Mutations in Blind Fish Eyes Scales Taste Cells Lateral Line 2- Model to explain what causes these changes: Change: ______________ Adapting an Organism to the Dark Cause: ________________ Stop the Growth of Eyes Effect: ___________________ Fish with Heightened Other Senses References: Video: Rare Blind Cave Fish in Mexican Cave System https://www.youtube.com/watch?v=MWdtGuDd8z0 Fact Sheet: Blind Cave Fish https://www.denverzoo.org/animals/blind-cave-fish Information: Mexican Tetra…arrow_forwardMutations in the IL2RG gene cause approximately 30 percent of severe combined immunodeficiency disorder (SCID) cases in humans. These mutations result in alterations to a protein component of cytokine receptors that are essential for proper development of the immune system. The IL2RG gene is composed of eight exons and contains upstream and downstream sequences that are necessary for proper transcription and translation. Below are some of the mutations observed. For each, explain its likely influence on the IL2RG gene product (assume its length to be 375 amino acids). (a) Nonsense mutation in a coding region (b) Insertion in Exon 1, causing frameshift (c) Insertion in Exon 7, causing frameshift (d) Missense mutation (e) Deletion in Exon 2, causing frameshift (f) Deletion in Exon 2, in frame (g) Large deletion covering Exons 2 and 3arrow_forwardYou suspect a protein that is being expressed has been affected by a mutation. When you examine the fully functional protein you find curiously that it still has retained all of its overall function. A friend of yours doing research with you assures you when examining the genetic data a new mutation does in fact exist in this protein. What is the most likely type of mutation that occurred based on this information? Group of answer choices frameshift mutation silent mutation nonsense mutationarrow_forward
- A gene affecting the behavioral outlook of individuals was discovered in several humans who can overcome anxiety caused by life's problems. Part of the gene that į translated into protein has a sequence 3'-GGATCCCGAATGTAATGCGTGCTC AATGGTAGTACGGC-5'. 1. What is the complementary strand of the DNA? 2. What is the sequence of the MRNA product after translation? 3. What is the sequence of the peptide encoded by the portion of the gene? (Use one letter symbol of amino acids)arrow_forwardRetinitis pigmentosa refers to a group of conditions that cause night blindness and loss of peripheral vision before age 20. A form of X-linked retinitis pigmentosa is caused by a frameshift mutation that deletes 199 amino acids. How can a simple mutation have such a great effect?arrow_forwardUse this mRNA coding sequence as your starting point. This sequence begins with a start codon and ends with a stop codon, so it is only looking at the region of DNA that directly encodes a protein sequence. 5’-AUGCACAAAUUAGAGUACCCCCCAGGAAGGUAG-3’ Make the following mutation in this sequence by changing/adding/removing only one nucleotide. Make the mutation easy to see (a different color, circled, something like that) A nonsense mutationarrow_forward
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