Female Mosquito Digestive Enzymes

Introduction

Mosquitoes are remembered by most as being the bane of the outdoor barbecue; the reason that bug zappers were invented. However, mosquitoes are not really as bad as some people think. To begin with, mosquitoes are equal opportunity pests. They will go after anything with blood, not just human flesh. In fact, it is only the female mosquito who bites; the male mosquitoes don't drink blood and are relatively innocent. Finally, mosquitoes are extremely well adapted to what they do. When a female mosquito bites an animal, certain chemicals in the animal's blood tell her when she has hit a blood vessel. Then, the mosquito's specialized saliva kicks in to keep the wound from clotting. In this manner, a typical 2 mg. mosquito can take in two to three times its own weight in blood.

Experiment One

When a mosquito takes in blood, it needs to be able to break the proteins in that blood down into their component amino acids in order to get any nutrition from the meal. The gut of the mosquito employs a class of enzymes called proteolytic enzymes to accomplish this. Trypsin, the enzyme being studied in this project, is one such enzyme. It is separated into two categories: early trypsin, which appears shortly after a blood-meal, and late trypsin, which appears later in digestion, and which does most of the work of digestion. The project found evidence that early trypsin activity (that is, the presence of early trypsin in the gut following a meal) was essential to the production of late trypsin later in the experiment. The early trypsin is present in small amounts about two hours after a meal, and the amounts fade out after about eight hours. At about twelve hours after the meal, the late trypsin begins to form. The early try...

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...vel of late trypsin translated in relation to the amount of protein in the meal. Regulation at both the transcriptional and translational levels allows the mosquito to adjust the levels of late trypsin with remarkable flexibility in response to a particular meal. In other words, the mosquito has the ability to assess the quality of its meals and then appropriately synthesize the late trypsin gene. This tight regulation might be important in reserving the synthesis of late trypsin when it isn't needed.

By studying trypsin (early and late) activity in the midgut of the mosquito it is possible that a "mosquito contraceptive" might be developed. A block of trypsin equates to no eggs and no offspring. Therefore, if we find a way to block trypsin production we can stop mosquitoes from reproducing; greatly decreasing or even diminishing these disease carrying insects.