Selection for hematocrit percent in the house mouse.

Area of Science:

• Genetics
• Physiology
• Animal Science

Background:

• Hematocrit, a measure of red blood cell volume, is a key indicator of oxygen-carrying capacity.
• Understanding the genetic basis of hematocrit is crucial for physiological and disease research.

Purpose of the Study:

• To investigate the genetic control of hematocrit levels in mice through artificial selection.
• To determine the realized heritability and the number of genes involved in hematocrit regulation.

Main Methods:

• Two-way selection experiments were conducted on mice to alter hematocrit levels.
• Hematocrit was measured at different ages (60 and 100 days) across generations.
• Realized heritability was calculated, and crosses between inbred strains were analyzed.

Main Results:

• One experiment showed rapid hematocrit increase in the first generation with no further response.
• A second experiment demonstrated a sustained two-way selection response for three generations.
• Realized heritability estimates ranged from 24-97%, higher than the 40% genetic determination from inbred strains.
• The relationship between hematocrit and systolic blood pressure was inconsistent.

Conclusions:

• Few genes appear to control normal hematocrit levels in inbred mouse strains.
• Selection experiment outcomes suggest that the timing of measurement influences the observed genetic response.
• The genetic architecture of hematocrit is complex and may involve a limited number of major genes.