Author
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Nayduch, Dana |
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JOYNER, CHESTER - Emory University |
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Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/25/2013 Publication Date: 7/10/2013 Citation: Nayduch, D., Joyner, C. 2013. Expression of lysozyme in the life history of the house fly (Musca domestica L.). Journal of Medical Entomology. 50: 847-852. Interpretive Summary: All life history stages of house flies associate with septic environments teeming with bacteria, and employ physical and chemical defenses that allow them to thrive and persist in this niche. The bacteria and fungi digesting enzyme lysozyme is found in many animals, and in house flies was first described in the larval midgut, where it is used for digestion of microbe-rich meals. This study looked at the production of lysozyme on the mRNA (gene product) and protein (active enzyme) level across life history from egg through larva, pupa and adult. In addition, we determined the spatial location of lysozyme in the body of adult house flies exposed to high doses of bacteria. House flies produced lysozyme mRNA from 30-min after oviposition (when the embryo is first in contact with the septic environment) throughout all life stages to adulthood. In adult flies, lysozyme mRNA was detected both locally in the alimentary canal (where bacteria are located) and systemically in the fat body. Interestingly, lysozyme protein was only detected in larval stages and older adults, likely due to ingestion of immune-stimulating levels bacteria during these stages and not at other times in life history. Activation of the lysozyme gene to produce mRNA throughout the entire life of the fly ensures that this important defense molecule that can be readily synthesized into active protein when flies encounter bacteria. Thus, the production of enzyme from mRNA must be tightly regulated in flies, and merits further study. Lysozyme active enzyme primarily serves both a digestive and defensive function in larval and adult flies, and may be a key player in the ability of Musca domestica to thrive in microbe-rich environments. Technical Abstract: From egg to adult, all life history stages of house flies associate with septic environments teeming with bacteria. House fly lysozyme was first identified in the larval midgut, where it is used for digestion of microbe-rich meals due to its broad-spectrum activity against Gram positive and Gram negative bacteria as well as fungi. This study aimed to determine the temporal expression of lysozyme in the life history of house flies (from egg through adults) on both the mRNA and protein level, and to determine the tissue-specific expression of lysozyme in adult flies induced by feeding Staphylococcus aureus. From 30-min post-oviposition through adulthood, all life history stages of the house fly express lysozyme on the mRNA level. In adult flies, lysozyme is expressed both locally in the alimentary canal and systemically in the fat body. Interestingly, we found that during the normal life history of flies, lysozyme protein was only detected in larval stages and older adults, likely due to ingestion of immune-stimulating levels bacteria, not experienced during egg, pupa and teneral adult stages. Constitutive expression on the mRNA level implies that this effector is a primary defense molecule in all stages of the house fly life history, and that a mechanism for post-transcriptional control of mature lysozyme enzyme expression may be present. Lysozyme active enzyme primarily serves both a digestive and defensive function in larval and adult flies, and may be a key player in the ability of Musca domestica to thrive in microbe-rich environments. |
