Question

The apterous gene in Drosophila encodes a protein required for wing patterning and growth. It is also known to function in nerve development, fertility, and viability. When human and mouse genes whose protein products closely resemble apterous were used to generate transgenic Drosophila (RinconLimas et al. \(1999 .\) Proc. Nat. Acad. Sci. \([\mathrm{USA}] 96: 2165-2170\) ) the apterous mutant phenotype was rescued. In addition, the whole-body expression patterns in the transgenic Drosophila were similar to normal apterous. (a) What is meant by the term rescued in this context? (b) What do these results indicate about the molecular nature of development?

Short answer

Answer: In the context of the experiment, the term "rescued" refers to the restoration of the normal phenotype in the apterous mutant Drosophila using human and mouse genes encoding proteins similar to apterous. These results indicate that the molecular nature of development shares a high level of conservation across different species, such as humans, mice, and Drosophila, suggesting that the underlying mechanisms of development are highly conserved across different organisms.

Step-by-step solution

(a) Understanding the term "rescued" in the context of the experiment

The term "rescued" in this context refers to the restoration of the normal phenotype in the apterous mutant Drosophila, using the human and mouse genes encoding proteins similar to apterous. The fact that the mutant phenotype was rescued indicates that the human and mouse genes were able to replace the function of the mutated Drosophila apterous gene and contribute to the normal development of the organisms.

(b) Implications of the experiment for the molecular nature of development

The results of the experiment indicate that the molecular nature of development shares a high level of conservation across different species, such as humans, mice, and Drosophila. This conservation is demonstrated by the fact that human and mouse genes were able to rescue the apterous mutant phenotype in Drosophila, restoring normal development. Additionally, the whole-body expression patterns in the transgenic Drosophila were similar to those of normal apterous, suggesting that these genes from different species have similar functions and are involved in the same developmental processes. This finding also implies that the underlying mechanisms of development, such as gene regulation, protein-protein interactions, and signaling pathways, are highly conserved across different organisms.

Key concepts

apterous gene

The apterous gene in Drosophila is crucial for several functions, primarily in wing development. It determines how wings are patterned and grow but also has roles in nerve development, fertility, and the overall survival of the organism. In simpler terms, without the functioning apterous gene, Drosophila would face multiple developmental issues that may even be fatal.

- It codes for a particular protein essential for these biological functions.
- The protein guides normal developmental processes, enabling the fruit fly to develop as expected.
- Any mutations in this gene can lead to drastic changes in development, like malformed wings or fertility issues.

This gene's failure can be "rescued" by introducing similar genes from other species, such as humans or mice. This process involves replacing the non-functional gene with a working version from a different organism that fulfills the same critical roles in development.

molecular conservation

Molecular conservation refers to the idea that certain molecular structures and functions are preserved throughout evolution across different species. It suggests a shared ancestry and highlights the universal nature of some biological mechanisms observed in a wide range of organisms.

- In the context of the experiment involving the apterous gene, molecular conservation is evident because the human and mouse genes could functionally substitute the fly's apterous gene.
- This implies that the basic machinery supervising development is quite similar across these species.
- Conservation at the molecular level involves genes, protein structures, signaling pathways, and other genetic components operating in a conserved manner.

For instance, if a gene in one species has a specific role, similar genes in other species often perform the same function, even if they are distantly related. This phenomenon of shared genetic elements allows scientists to study one organism's genes and apply the findings to another, using model organisms to understand human biology.

transgenic organisms

Transgenic organisms are living organisms that have undergone genetic modification, where new DNA is introduced into their genome. This process is typically achieved through inserting genes from one species into another. The result is organisms that exhibit new traits or have enhanced functions due to the inserted genes.

- In the case of the Drosophila study, transgenic flies were created by introducing human or mouse genes to substitute for the malfunctioning apterous gene.
- This highlights the advanced capacity of transgenics in research, allowing scientists to explore and manipulate genetic relationships and functions.
- Transgenic organisms are used not only in scientific research but also in agriculture and medicine, such as generating crops with better resilience or producing pharmaceuticals.

While creating transgenic organisms opens many possibilities, it also raises ethical considerations about genetic manipulation. Scientists and regulators work to address these concerns to ensure that transgenic research benefits humanity responsibly.