Tag Archives: umwelt

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Lives of muskrat lymphocytes

Large lymphocyte from a normal blood film

One of my favorite essays by the immunologist-poet, Miroslav Holub, describes the symphony of cellular life enacted after a muskrat drowns in the writer’s pool and is shot by a neighbor. The scene itself is grim yet fairly boring and commonplace; dead animals, be it a robin flown into our window or a white-footed mouse decapitated by our cat, seem to be an ordinary part of suburban life. But Holub views the situation from the interior view of the animal and with the sense and extrapolation of a poet. His interest in the phenomenon of death lies in the cellular process that are taking place long after we conceive of the animal as “dead.” While ordinarily we see the spectrum of alive to dead as having a definitive moment of change from A to B, a universe of interactions, an ecosystem of cellular bodies, continues to communicate, move, exist. I’ve copied my favorite excerpt from the essay, that of the lymphocytes (an immunologist’s specialty), below.

So there was this muskrattish courage, an elemental bravery transcending life.

But mainly, among the denaturing proteins and the disintegrating peptide chains, the white blood cells lived, really lived, as anyone knows who has ever peeked into a microscope, or anyone knows who remembers how live tissue cells were grown from a sausage in a Cambridge laboratory (the sausage having certainly gone through a longer funereal procedure than blood that is still flowing). There were these shipwrecked white blood cells in the cooling ocean, millions and billions of them on the concrete, on the rags, in the wrung-out murkiness. Bewildered by the unusual temperature and salt concentration, lacking unified signals and gentle ripples of the vascular endothelium, they were nevertheless alive and searching for whatever they were destined to search for. The T lymphocytes were using their receptors to distinguish the muskrat’s self markers from nonself bodies. The B lymphocytes were using their antibody molecules to pick up everything the muskrat had learned about the outer world in the course of its evolution. Plasma cells were dropping antibodies in various places. Phagocyte cells were creeping like amoebas on the bottom of the pool, releasing their digestive granules in an attempt to devour its infinite surface. And here and there a blast cell divided, creating two new, last cells.

Jean-Henri Fabre on bees

The victuals are now collected: honey and flower-dust. If there is a pink carpet of sainfoin anywhere in the neighbourhood, tis there that the Mason goes plundering by preference, though it cost her a four hundred yards‘ journey every time. Her crop swells with honeyed exudations, her belly is floured with pollen. Back to the cell, which slowly fills; and back straightway to the harvest-field. And all day long, with not a sign of weariness, the same activity is maintained as long as the sun is high enough. When it is late, if the house is not yet closed, the Bee retires to her cell to spend the night there, head downwards, tip of her abdomen outside, a habit foreign to the Chalicodoma of the Sheds. Then and then alone the Mason rests; but it is a rest that is in a sense equivalent to work, for, thus placed, she blocks the entrance to the honey-store and defends her treasure against twilight or night marauders.

—Jean-Henri Fabre, “The Tribulations of the Mason Bee,” Mason Bees (1925)

"first contact," photograph by author.

The painted lives of ciliates and schistosomes

Art has always been one way to mediate tensions, tensions such as those between the logic-driven mind of scientific inquiry and the subjective experience of the non-human, what Jakob  von Uexküll called an organism’s umwelt. Thomas Nagel famously argued that we can never know what it is like to be a bat, or any non-human organism, but whether through experimental-minded writings on what the world might be through a tortoise’s point of view  or through watercolor paintings, the artistic hopes to bridge various umwelten more so than a declaration of scientific understanding—the difference lies within the distinction of this is how a starling sees the spectrum of light and thus the world (science) and this is how a starling might see the world (art). Might opens possibilities, a window into creative endeavor.

The paintings of Emilie Clark might be one answer to Nagel. Clark, a painter based on Brooklyn, NY, has worked on a series of projects involved in life on a microscopic scale. In a 2004 gallery showingPondering the Marvelous, Clark responds to the writings of Mary Ward, a 19th-century Irish natural historian and painter, specifically Ward’s A World of Wonders Revealed by the Microscope. In imagining Ward’s writings as personal letters to the artist, Clark produced two series of her own watercolors—the first based on Ward’s description of Ireland’s microscopic landscape, and the second on Clark’s own collection.

Untitled MW-#50. Painting by and courtesy of Emilie Clark.

Untitled MW-#12. Painting by and courtesy of Emilie Clark.

The paintings are not meant in their entirety to be illustrations of these organisms’ umwelten, and nor do they achieve this ideal. But these paintings play with the possibility of “what if?” And it is this play that creates an opening in our imagining of the umwelt of other species. Perhaps best said by the poet–immunologist Miroslav Holub, the act of play allows us, simply, to “avoid the aridities of rationalism.” Yet this is not Clark’s first foray into toying with the lifeworld of other microorganisms.

In a previous post, I briefly touched on the topic of cover art for scientific journals—in this case, a watercolor of a stag beetle by Albrecht Dürer for a 2005 issue of Emerging Infectious Diseases. One of Emilie Clark’s projects, which one can find on her webpage, is likewise producing watercolor medical illustrations, many of which have found their way onto the covers of The Journal of Experimental Medicine. The JEM, since its beginnings in 1896, publishes original research on the physiological, pathological, and molecular mechanisms that are encountered by or reactions of the host in response to disease. In the case of a November 2005 issue of the journal, the target pathogenic organism of Clark’s illustration was Schistosoma mansoni, one of three causative agents of human schistosomiasis.

From the cover caption of JEM 2005; 202 (10). Emilie Clark's watercolor of S. mansoni eggs. The eggs secrete a chemokine binding protein, thereby suppressing the inflammatory response.

Schistosomes are blood flukes (trematodes) that belong to the genus Schistosoma. In addition to S. mansoni, the other two members of this genus that cause disease in humans are S. hematobium and S. japonicum. The disease itself, caused by human contact with water home to schistosome cercaria, is a definitive chronic condition whereby the mature schistosomes, after reaching the final stage of their life cycle, migrate to the mesenteric or rectal veins and begin to mate, thereby producing up to 300 eggs per day for the rest of their reproductive lives—which can be as long as 4–20 years. A proportion of these eggs will become lodged in the target veins, where they mature and secrete antigens that elicit an intense immune response in the host. It is this immunological reaction, which can continue as long as the mating worms and the eggs continue to exist in the body, that characterizes schistosomiasis. It was the point of the primary research communication by Philip Smith et al., the inspiration for the choice of Clark’s watercolor, to demonstrate one way in which S. mansoni modifies the human host to tolerate decades-long chronic infection without causing death. In particular, the researchers demonstrated that S. mansoni eggs secrete a protein into host tissues that binds certain chemokines—proteins that induce directed chemotaxis, how certain cells direct their movements according to particular chemicals in their environment, in nearby responsive cells—and inhibits their interaction with host chemokine receptors and their biological activity.

Now, compare Clark’s interpretation of the organisms and this phenomenon with a direct realistic representation through a microscope. Continue reading

The umwelt of a paramecium

On days when it rains and I am stuck inside at a desk, I often find my thoughts return to a single thematic idea: how does a single-celled organism perceive the world? Having recently read Devin Johnston’s Creaturely and Other Essays, I was struck by the author’s same general thought with regard to the higher vertebrates—in this case, the starling: “As science discovers the spectral sensitivities of birds, their sensory world proves alien to ours, their consciousness recessed from us.” Unlike that of humans, the eye of the starling does not filter out the ultraviolet spectrum of light. The organism sees the world with a fourth dimension attached—its world is, in essence, unknowable to us.

Season: organic/plant motifs and structures of microorganisms. Print by Yellena James (www.yellena.com)

As a sensory experience of one’s environment, this seeing is subjective, what the German biologist Jakob von Uexküll called each organism’s umwelt—what in German literally means “environment,” but which is typically taken as “subjective universe.” The term stands against a typical assumption of modern ecology that all organisms in an ecosystem share the same environment. Instead, von Uexküll argued that the subjective perception of organisms drives ecological interactions—parasitism, mutualism, etc. The entomologist/molecular biologist Alexei A. Sharov, who himself moved from ecology into the emerging field of biosemiotics, contextualizes the theory best with an example from plant ecology:

Uexküll thought that organisms may have different umwelts even if they live in the same place. A stem of a blooming flower is perceived differently by an ant, cicada-larva, cow, and human. Umwelt is not an ecological niche because niches are assumed to be objective units of an ecosystem which can be quantified using external measuring devices. On the contrary, umwelt is subjective and is not accessible for direct measurement for the same reason that we have no direct access to perceptions of other people.

Pistil. Photograph by author.

von Uexküll argued we cannot know the precise, quantified experience of the ant, cicada, or cow, just as Johnston struggles against studies of animal behavior that claim to have understood the way a starling sees. Each organism’s umwelt exists in a reciprocal exchange between phenomenological experience and the biophysical world—one of von Uexküll’s main ideas from the umwelt theory is that each component of this subjective universe has functional meaning to the agent. The stem of a blooming flower may be food, shelter, landmark, etc, depending on the species and context of the interaction. Each organism actively participates in the production of umwelt through these repeated interactions. In Sharov’s words,  the organism “simultaneously observes the world and changes it; the phenomenon which Uexküll called a functional circle.” Because these interactions are tied up with functional use and subjective experience, von Uexküll’s approach to animal behavior could not separate subjective (experience) from objective (biophysical matter), as modern-day approaches to the subject commonly insist—mind makes the world meaningful, a staple of cultural anthropology. In the related field of the philosophy of science, Sharov allies von Uexküll with pragmatism, the school of thought that argues how objects cannot be separated from interpreters.

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