VIROCELL CONCEPT APPLIED TO PARASITES

 

Virocell Concept Applied To Non-Viral Parasites

Post # 33

Donald A. Windsor

Viruses that harm their hosts are parasites. The popular notion that viruses are not alive has been dispelled by Patrick Forterre with his virocell concept (1, 2, 3). A virus is composed of a virion and a virocell. The virion is a protein capsule that contains a nucleic acid genome. The virocell is the host cell that accepts a virion and then produces more virions. The virus is the living organism. The virion is the equivalent of a plant seed.

If non-viral parasites (hereafter just called parasites) were regarded this way, the definitive host and its parasite, together, would be the living organism. The definitive host would be analogous to the virocell and the parasite would be analogous to the virion. The parasite would also be analogous to a seed.

Admittedly, this is an unconventional way of considering parasites.

But, it is consistent with my concept of considering parasitism as a property of life (4).

It is also consistent with my concept of the biocartel, first reported in 1997 (5).

A lot more thought has to go into this concept. For instance, some parasites have intermediate hosts in their life cycles. Do some viruses have intermediate virocells? Parasites may or may not reproduce in their intermediate hosts. Sometimes the intermediate host serves simply to transmit the parasite to its next host.

References cited:

1. Forterre, Patrick. Manipulation of cellular syntheses and the nature of viruses. The virocell concept. Comptes Rendus Chimie 2011; 14: 393-399.

2. Forterre, Patrick. The virocell concept and environmental microbiology. The ISME Journal [International Society for Microbial Ecology] 2013; 7:233-236.

3. Forterre, Patrick. Viruses in the 21st century: from the curiosity-driven discovery of giant viruses to new concepts and definition of life. Clinical Infectious Diseases 2017; 65 Supplement 1: S74-S78.

4. Windsor, Donald A. Parasitism as a property of life. Parasites Dominate 2013 September 3; Post #2. http://www.parasitesdominate.blogspot.com

5. Windsor, Donald A. The basic unit of evolution is the host-symbiont "biocartel". Evolutionary Theory 1997 August; 11(4): 275.

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HOW MANY HABITATS IN OUR BIOSPHERE?

 

Post # 32

How Many Habitats In Our Biosphere?

Donald A. Windsor

Many more than realized — some multiple of the total number of free-living species. Because every free-living species hosts one or more species of parasite. To a parasite, its host is its habitat. Parasites with complex life cycles dwell in several habitats. Moreover, some parasites host their own parasites.

A host provides several habitats. Each organ or tissue could be a habitat for parasites. Parasites that enter the gastrointestinal tract and travel to a specific tissue have to pass through other tissues to get to their final destination. So, the total number of habitats is a multiple of the total number of hosts.

Some free-living species host large numbers of parasite species. The American Robin (Turdus migratorious) is the host for at least 94 parasite species (1). The European Starling (Sturnus vulgaris), a cosmopolitan bird, is host to at least 175 parasite species (2). These are just the species I could document in the literature. There are likely to be many more yet to be discovered.

In addition to all the biological habitats are the non-biological habitats.

The upshot is that while the exact number of habitats on Earth may be too elusive to calculate, it is safe to proclaim that the number is astronomical.

References cited:

1. Windsor, Donald A. Biocartel of the American Robin (Turdus migratorious). Archives of the SciAesthetics Institute 2000 August; 1(1): 13-18.

2. Windsor, Donald A. Biocartel of the European Starling (Sturnus vulgaris). Archives of the SciAesthetics Institute 2000 August; 1(1): 19-28.

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CONSERVATION OF PARASITES: Emphasis as Species

 Post #31

Conservation of Parasites: Emphasis as Species

Donald A. Windsor

Successful conservation of parasites is being handicapped because people (including many scientists) are not always differentiating between parasites as individuals and parasites as species.

Here is what must be emphasized. Species evolve. Individuals do not.

Parasites, as individuals, harm their hosts, by definition.

Parasites, as species, actually benefit their host species.

At the species level, parasites benefit their hosts by enabling them to survive. Parasites manage the ecosystems in which the hosts live. Without suitable ecosystems, the hosts would have to either go extinct or evolve into new species.

Without parasites, ecosystems would deteriorate into just a few monocultures of very aggressively invasive species. Biodiversity is due to parasites. 

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ARE PARASITES SINGING THEIR OWN UNCEASING SONG OF LIFE?

Are Parasites Singing Their Own Unceasing Song Of Life?

Post #30

Donald A. Windsor

Well, parasites may not be singing, but they sure are showing off their most visible presence – biodiversity.

James Lovelock referred to the infrared signal of the oxygen-methane disequilibrium radiating from Earth's atmosphere as an "unceasing song of life".

"This unceasing song of life is audible to anyone with a receiver, even from outside the Solar System." (1).

If Lovelock's statement is correct, then this song would indicate life on any extraterrestrial entity.

After such life is found, perhaps it could reveal whether parasitism is, or is not, a universal property of life. I suspect that it is.

Here on Earth, our life exhibits parasitism. But, what would life look like without parasitism? I suspect that the signature hallmark of life is biodiversity. But biodiversity can result from life adapting to environmental forces, such as competition, predation, habitat, and climate.

Parasites enhance biodiversity by thwarting monocultures. Therefore, the absence of monocultures on extraterrestrial entities could be a signature of parasitism.

However, how would a monoculture be recognized? On Earth we have no naturally occurring pure monocultures; they exists only in labs or buildings. Our so-called monocultures, such as with agricultural crops like corn and wheat, always have other species living among them.

Here is a handy metric that I propose. In a monoculture, the number of individuals of one species is at least 1 magnitude higher than the total number of individuals of all the other species combined, in the same area.

For example, if a bean field had 10,000 individual bean plants, then it would be a monoculture if the total number of individuals of all the other species in that field was under 1,000, a difference of 1 order of magnitude.

This metric would not be able to compare macro-species with microbial species, because the microbes would always outnumber the macros. However, it may be useful in comparing a monoculture of a microbe with other microbial species.

So, while the unceasing song of parasitism may not be a song, it may be an image visible to anyone with a viewer.

Reference cited:

1. Lovelock, James. The Ages of Gaia. A Biography of Our Living Earth. 2nd Edition. New York, NY: Oxford University Press. 2000. 268 pages. Quote on page 7 of the Introductory.

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DID HUMANS ORIGINATE FROM MANIPULATION BY PARASITES?

Did Humans Originate From Manipulation By Parasites?

Post #29

Donald A. Windsor

Humans are very different from other hominid primates. How did we get this way?

The Savanna Hypothesis postulates that our ancient ancestors abandoned their arboreal life to live in a savanna, a habitat with mostly grass and few trees. It attributes our upright posture and bipedalism to this change of venue. Our keen intellect, organizational skills, and language evolved in this savanna habitat (1).

I suspect that parasites instigated this transition from arboreal to terrestrial.

My suspicions were aroused by the model of the pill bug and the bird. The acanthocephalan Plagiorhynchus cylindraceus is parasitic in its definitive host, the European Starling Sturnus vulgaris, and in its intermediate host, the isopod "pill bug" Armadillidiuum vulgare. The parasite manipulates the pill bug to behave in ways that increase its chances of being eaten by the bird, Normally, pill bugs prefer dark, humid, covered places. Infected pill bugs tend to wander out into the open where it is lighter and drier, where they become easy prey for the bird (2).

Could some arboreal hominids have been manipulated by a parasite to venture into the more dangerous savanna? How similar is the pill bug and bird example to an early hominid coming down from the safety of an arboreal lifestyle to roam in the dangerously open savanna? While there may be no way of knowing for certain, the possibility is intriguing.

Consider that the parasite Toxoplasma gondii is notorious for manipulating humans. Moreover, its definitive host is felines (3). Large feline predators inhabit grasslands. Its intermediate host is an array of prey animals, especially rodents (4). Humans could be an intermediate host.

I pose this hypothetical parasite involvement because the Savanna Hypothesis has been discussed for over two centuries and, while it may be out of favor now, it still has merits. Besides, numerous migrations allowed humans to become a cosmopolitan species. Parasites could well have been instrumental in moving people around.

References cited:

1. Anon. Savannah hypothesis. Wikipedia 2019 June 9: 1-7.

2. Moore, Janice. Responses of an avian predator and its isopod prey to an acanthocephalan parasite. Ecology 1983 October; 64(5): 1000-1015.

3. Anon. Toxoplasma gondii. Wikipedia 2019 June 13: 1-23.

4. Tenter, Astrid M. ; Heckeroth, Anja R. ; Weiss, Louis M. Toxoplasma gondii: from animals to humans. International Journal for Parasitology 2000 November: 30(12-13): 1217-1258.

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HEMIPARASITES BENEFIT THEIR HOSTS AT THE SPECIES AND ECOSYSTEM LEVELS

Hemiparasites Benefit Their Hosts At The Species And Ecosystem Levels

Post #28

Donald A. Windsor

Hemiparasites are photosynthetic plants that parasitize free-living plants to obtain nutrients (1).

Growth of the host plants can be stunted by the hemiparasites, thus allowing more sunlight to reach lower growing plants and increasing biodiversity.

Hemiparasites benefit prairie ecosystems similar to the way grazing animals do, by preventing the taller plants from taking over. For this reason they are sometimes called "pseudograzers" (2).

Individual hemiparasites harm their individual hosts, but the hemiparasites as species benefit other species, and the resulting biodiversity benefits the ecosystem. All species in the ecosystem benefit from the ecosystem staying intact.

References cited:

1. Těšitel, Jakub ; Plavcova, Lenka ; Cameron, Duncan. Interactions between hemiparasitic plants and their hosts: The importance of organic carbon transfer. Plant Signaling & Behavior 2010 August; 5(9): 1072-1076.

2. DiGiovanni, Jane P. ; Wysocki, William P. ; Burke, Sean V. ; Duvall, Melvin R. ; Barber, Nicholas A. The role of hemiparasitic plants: influencing tallgrass prairie quality, diversity, and structure. Restoration Ecology 2017 May; 25(3): 405-413.

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DEEP SUBSURFACE BIOSPHERE ─ ANY PARASITES?

Deep Subsurface Biosphere ─ Any Parasites?

Post #27

Donald A. Windsor

As even more information comes in on the deep subsurface biosphere, the more I wonder about generalities already made about our surface biosphere.

The deep subsurface biosphere is composed of archaea, bacteria, and eukaryotes that live underground down to great depths, even under the oceans (1 - 6). It could have more species than our surface biosphere does (2).

Six years ago I proposed that parasitism was a property of life on Earth and if it is found on extraterrestrial planets, it would be a universal property. If it were not found on other planets, then it would be a property of Earth alone (7).

So far, I have not uncovered any reports of parasites in the deep subsurface biosphere.

In 1998 I proclaimed that most of the species on Earth were parasites (8). If there are no parasites in the deep subsurface biosphere, my hypothesis would be nullified. However, I did say "on" Earth, not "in". Nevertheless, I meant "on", because I was not aware of how massive the deep subsurface biosphere is.

Another thought I advocated is that parasites produce biodiversity by stopping monocultures before they get too large (9). Some of the colonies in the deep subsurface may have monocultures. That in itself could indicate a lack of parasites.

I find this all very exciting because I thought that finding extraterrestrial life on Mars would be a test of my hypotheses (10). But now the deep subsurface biosphere may provide that test.

References cited:

1. Lawton, Graham. Earth's deep, dark secret. New Scientist 2019 May 11; 242(3229): 42-45.

2. Klein, JoAnna. Deep beneath your feet, they live in the octillions. The New York Times 2018 December 19.

3. Purkamo, Lotta. et al. Diversity and functionality of archaeal, bacterial, and fungal communities in deep archaean bedrock. FEMS Microbiology Ecology 2018; 94: 1-14.

4. D'Hondt, Steven; et al. Presence of oxygen and aerobic communities from sea floor to basement in deep-sea sediments. Nature Geoscience 2015; 8: 299-304.

5. Magnabosco, C. et al. The biomass and biodiversity of the continental subsurface. Nature Geoscience 2018 October; 11(10): 707.

6. Puente-Sánchez, Fernando. et al. Viable cyanobacteria in the deep continental subsurface. PNAS 2018 October 16; 115(42): 10702-10707.

7. Windsor, Donald A. Parasitism as a property of life. parasitesdominate.blogspot.com 2013 September 3. Post #2.

8. Windsor, Donald A. Most of the species on Earth are parasites. International Journal for Parasitology 1998 December; 28(12): 1939-1941.

9. Windsor, Donald A. Role of parasites in Earth's biosphere. parasitesdominate.blogspot.com 2017 September 30. Post #13.

10. Windsor, Donald A. Parasitism on Mars. parasitesdominate.blogspot.com 2015 November 8. Post #10

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