Organism Digests Blood

a microscopy image of a hookworm egg and larvae hatching, the egg is dark red and the saline solution is light pink

Biological Strategy

Hookworm

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Chemically Break Down Organic Compounds

The vast majority of biochemical assembly and breakdown processes–even by the most complex organisms–occur within cells. In fact, cells are able to perform hundreds, even thousands of chemical transformations at the same time under life-friendly conditions (ambient temperature and pressure in an aqueous environment). Part of the reason that decomposition reactions (chemical breakdown) can occur under such mild conditions is because most often, they occur in a stepwise, enzyme-mediated fashion, sipping or releasing small amounts of energy at each step. For example, the breakdown of glucose to pyruvate–and the release of energy–occurs in the 10-step enzyme catalyzed process of glycolysis.

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Animals

Kingdom Animalia (“having breath or soul”): Mammals, reptiles, sponges, corals, insects, birds

This kingdom captures a staggering variety of life—from the smallest coral polyp to the largest elephant. Although animal body shapes and life histories vary, there are a few defining characteristics. Animals are heterotrophs, meaning they gain energy from eating other organisms, and have developed from single-celled ancestors to highly diversified and coordinated multicellular forms. Unlike plant and fungi cells that have rigid cell walls, animal cells are bound by more flexible combinations of proteins. Most animals have cells organized into tissues and are able to move within their environment.

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Hookworms digest blood using a cascade of proteases.

Image: CDC - Department of Parasitic Diseases /

“Bloodsucking hookworms parasitize 700 million people worldwide, and are responsible for a daily blood loss equivalent to the total blood supply of more than a million people.” (Shuker 2001:167)

“Hookworms are blood-feeding nematodes that reside in the small intestine of infected mammalian hosts (12)…To obtain an unimpeded blood meal, hookworms secrete potent anticoagulants, the actions of which have been well characterized (15, 16). Once blood is ingested by adult hookworms, they lyse erythrocytes using a pore-forming, membrane-bound hemolysin (17), releasing the red cell contents into the intestinal lumen for proteolytic degradation. The pH of the hookworm intestine is not definitively known; however, it is presumed to be acidic in nature (18). All of the proteases identified from this anatomic site have acidic pH optima (19–21); Hb digestion by hookworm secretory extracts is optimal at pH 5–7 (22). Moreover, the intestinal contents from the related blood-feeding helminth, Schistosoma mansoni, are acidic pH (11)…Here we show that the canine hookworm digests Hb in a semi-ordered cascade that consists of at least aspartic, cysteine, and metalloproteases, which act in synergy at acidic pH. The classes of proteases involved and the order of their actions are strikingly similar to those used by P. falciparum to digest Hb in the food vacuole.” (Williamson et al. 2004:35950-35951)

Last Updated August 28, 2020

References

Book

The Hidden Powers of Animals: Uncovering the Secrets of Nature

Marshall Editions Ltd. | 01/01/1970 | Dr. Karl P. N. Shuker

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Reference

Journal article

A Multi-enzyme Cascade of Hemoglobin Proteolysis in the Intestine of Blood-feeding Hookworms

Williamson, A. L.; Lecchi, P.; Turk, B. E.; Choe, Y.; Hotez, P. J.; McKerrow, J. H.; Cantley, L. C.; Sajid, M.; Craik, C. S.; Loukas, A.

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