Question

Acute murine leukemia virus (AMLV) causes leukemia in mice. This virus is easily passed from mother to offspring through the mother's milk. (Note: Even though newborn offspring acquire the virus, they may not develop leukemia until much later in life. Testing can determine if an animal carries the virus.) Describe how the development of leukemia via AMLV resembles a maternal inheritance pattern. How could you determine that this form of leukemia is not caused by extranuclear inheritance?

Short answer

The development of leukemia via AMLV mirrors a maternal inheritance pattern as it's passed from the mother to the offspring through the mother's milk. To determine that this form of leukemia isn't caused by extranuclear inheritance, one would need to find no traces of the disease-causing gene in the mitochondrial DNA. This can be done through a DNA test that targets the virus causing the disease.

Step-by-step solution

Understanding Maternal Inheritance of AMLV

Leukemia in mice caused by the Acute Murine Leukemia Virus (AMLV) shows characteristics of maternal inheritance. Upon ingestion of the mother’s milk, newborn mice acquire the virus, even though the development of leukemia may not occur until later in their life. This transmission from a mother to her offspring through the mother's milk is the characteristic pattern of maternal inheritance.

Distinguishing from Extranuclear Inheritance

Extranuclear inheritance refers to the transmission of traits from DNA that is not contained in the nucleus, such as mitochondrial or chloroplast DNA. To confirm that this form of leukemia is not caused by extranuclear inheritance, a conclusive test to determine the source of the DNA causing the disease should be conducted. If the disease-causing gene is identified in the virus (AMLV) and not in the mitochondrial DNA of the mother, it would confirm that this form of leukemia is not caused by extranuclear inheritance. In other words, the leukemia is triggered by the virus, not by any gene located in the mitochondrial DNA.

Experimental Design to Confirm the Inheritance Pattern

An experiment could be designed where a group of newborn mice are separated from their mother right after birth, before they have ingested any milk. This group would be raised on a synthetic milk substitute while a control group would be raised as normal. If the separated mice do not develop leukemia, this would support the argument of leukemia being passed through the mother's milk.