PANSPERMIA and EVOLUTION

Mars Spirit Lander and Bonneville Crater in Color

 Image Credit: NASA/JPL-Caltech/Univ. of Arizona 

Panspermia  is a concept which portrays how life might be distributed throughout the universe.  These means include a wide variety of astronomical or celestrial objects  including meteors, comets, asteroids, and factors such as the solar wind.  The theory of panspermia, however does not really address how life began in the first place.

As man has ventured out into space, with human space travel, or has used unmanned spaceflight, the issue of man (or machine) as a vector or agent of panspermia has become an issue.  This issue parallels the concept of jet travel and airports as a vector in spreading contagion. Migratory birds have been vectors for centuries, landing in Qinghai Lake, China, a saline and alkaline lake and migratory crossroads  or in the Izembek National Wildlife Refuge in Alaska, along the Bering Sea. . Such bird migratory pathways provide fertile ground for recombination and spread of various contagions.

The NASA photo of the Bonneville Crater and Mars Spirit Lander depicts an impact crater on Mars.  Such an impact would have created a large amount of energy upon impact.  Many theories of life involve the discussion of how reorganization and complexity arises as energy is input into a system.  The Miller and Urey experiment in 1953 attempted to address this issue through recreation of a primordial atmosphere laced with water, methane and lightning storms.
 
Henry Eyring, a chemist, discovered Actual Rate Theory or Transition State Theory, which discusses reaction rates of chemicals in the context of potential energy states, complexes activated by chemical reactions, entropy considerations and products formed by the chemical reaction. In considering the input of exogenous energy into a system, this theory would be important in examining the potential reactions that might take place, as the reaction may change the system through transformational change.

In considering the issue of panspermia, therefore, there are a couple of issues; the development of a system and then the spread of that system.  Issues of energy and mixing concern the development or the boot-strapping of a system through transformational change, while panspermia addresses the spread.  Where panspermia occurs through media that spread via impact, the two issues (bootstrapping and spread) tend to co-exist to some extent.

The concept of panspermia requires a vector that is resilient.  It must be able to adapt to environmental factors such as extremes of temperature, must be able to resist impact as well as radiation and other factors such as high levels of salinity.   Such organisms, extremophiles  fit a profile as a candidate for panspermia.

Santa Catalina Mountains seen from Saguaro National Park, Arizona

Recently, I came across an article in Applied and Environmental Microbiology (AEM) on Bacillus Endospores,  written by Patricia Fajardo-Cavazos and Wayne Nicholson, "Bacillus Endospores Isolated from Granite: Close Molecular Relationships to Globally Distributed Bacillus spp. from Endolithic and Extreme Environments".   This article discusses the issue of the diversity of Bacillus spp. populations, and specifically certain endolithic spore populations obtained from near surface granite from the Santa Catalina mountains near Tucson, Arizona.

An endospore is a tough non-reproductive surface that lies dormant for an extended period of time, and can be later revived after many years to a vegetative state.

Anthrax is a bacillus, and may exist in the dormant state as an endospore.  According to a World Health Organization document on studies of anthrax endospores (bacillus anthracis),  "Sporulation requires the presence of free oxygen. In the natural situation, this means the vegetative cycles occur within the low oxygen environment of the infected host and, within the host, the organism is exclusively in the vegetative form. Once outside the host, sporulation commences upon exposure to the air and the spore forms are essentially the exclusive phase in the environment."  Spores are thus spread by release of spores by the dying host into the environment where they are taken up by another animal.

 The focus of the AEM article is on the very issue of panspermia, the issue of transference of microbes through spaceflight, It concerns the measurement of characteristics of various endolithic spore populations obtained through a variety of near surface granites and basalts and even the ultra clean environments of spacecraft assembly facilities.

Blue fluorescence obtained through medium wavelength UV illumination, distinguished certain endospores obtained from near surface granites.  Endospores were grouped into species or strains based on their rRNA  gene sequences. Numbers and diversity of endospores from granite were greater than those obtained from basalts.  This may be due to the lower porosity of basalt versus granite. Limited subsets of Bacillus spp. appeared to occur in certain rock environments that favored them and not other strains. Certain bacillus strains (bacillus subtilis) were used as proxies for bacillus anthracis fluorescence properties in the study.

The issue of panspermia is a very important one, set in the context of space exploration and in consideration of how extraterrestrial impacts may have impacted (and may still be impacting) human life.  The AEM study provides interesting results as to the diversity and characteristics of Bacillus spp. from a variety of environments, including, importantly, granite, set in the context of fluorescence properties.   A bacillus such as anthrax, as studied by the World Health Organization (WHO) or the CDC may provide clues as to how bacillus and endospores fit into our evolutionary framework.

Trinity Nuclear Test

Bosque del Apache National Wildlife Refuge

near San Antonio, New Mexico

On July 16, 1945, the first atomic bomb test was performed at a site about 35 southeast of Soccorro, New Mexico.  The test was code named 'Trinity' by Dr Robert Oppenheimer, director of the Los Alamos Laboratory involved in the Manhattan Project.  It used a 20 kiloton Plutonium implosion device, of a similar design to what would ultimately be dropped over Nagasaki on August 9, 1945, less than a month later.  The Manhattan Project was a war-time effort to develop an atomic bomb, which occurred over a time period from 1942 to 1946.  The effort extended to a number of facilities, including Hanford, Washington and Oak Ridge, Tennessee in addition to the Los Alamos, New Mexico  site where major design work occurred.  Ultimately testing would be done in a number of areas, including Nevada and the Pacific Islands, including Bikini Atoll, after World War II.

The Trinity test differed in nature from that used on the first atomic blast at Hiroshima.  The Hiroshima blast used a gun type, or projectile type detonation of uranium while the Nagasaki and Trinity Blast involved implosion of a plutonium core.

The Trinity atomic bomb test followed a period of development of nuclear expertise in a number of areas, from study of the atom itself, to study of high energy collisions and the study of nuclear chain reactions. A key development was a letter by physicists Eugene Szilard  and Albert Einstein,   expressing their concern that Germany could develop an atomic bomb.  The result of their efforts, which included collaborations with other physicists such as Eugene Wigner and Edward Teller , was that President Franklin Delano Roosevelt accelerated scientific research with a new committee on June 28, 1941 and approved the atomic program on October 9, 1941.  The response to their letter came on October 19, 1941.

This timeline is interesting, taken in the context of the historical evolution, from World War I, in 1914-1918 to World War II and its aftermath in the nuclear arms race.  The historical context included the 1918 Flu Pandemic (Spanish Flu), aided by a World War I fought in the trenches, the Great Depression,  and the ever continuing battle between commercialization, globalization and nationalist interests.  The development of nuclear weapons ratcheted up the stakes, due to the wider implications of their use and the attendant risks.

Nuclear risks include the potential manufacture, storage, transportation, testing and potential use of nuclear weapons in conflict (including WWII).  These risks are in addition to risks arising from nuclear usages in other areas, such as power generation and medical usages.  We have seen impacts from the Three Mile Island, Chernobyl and Fukushima nuclear power plant incidents.  I've discussed some of these issues in other blog articles, including: Nuclear Balance of Risks, Chernobyl 25th Anniversary and Energy Choices and Risk.

Development, testing and use of nuclear weapons has left a long lasting radiological footprint on the landscape in areas such as Hanford and the Pacific Northwest, the Trinity Site and White Sands and the Southwest, the Pacific Islands, including Japan during WWII, and downwind (and water) areas.

The above photograph is taken at Bosque Del Apache National Wildlife Refuge, near San Antonio, New Mexico in February, 2009, about 20 -30 miles from the Trinity Test Site, some 63-64 years after the test.  Another image, taken at Valley of the Fires State Park, New Mexico, was taken near Carrizozo, New Mexico, one of the areas harder hit by the Trinity plume.

The Odd Couple: The Mitochondria and the Cell Nucleus

Mitochondrion (Creative Image)

Mitochondria are key to understanding many life processes, in the body, in nature,
and in our environment.

Years ago, the Eukaryotic cell   developed as a symbiotic relationship between a prokaryotic cell and a proteobacteria.  The prokaryotic cell may have been an archaea. The proteobacteria was was incorporated into the cell as an endosymbiont.  As gene transfer took place between mitochondrial DNA  and the cell's nuclear DNA, the extent of the  mitochondrial DNA (mtDNA) decreased and the nuclear DNA incorporated more of the functions performed previously by mitochondrial DNA.  As this occured, the relationship changed from being symbiotic to the development of the mitochondrion as an organelle within the cell.

Much of the work developing the theory of symbiogenesis was done by Lynn Margulis in a 1967 paper..  The theory behind symbiogenesis is a very important topic with wide ranging implications due to the complexities involved in the interoperablity of nuclear DNA and mitochondrial DNA.  These issues are ongoing and represent a major challenge in understanding a wide range of scientific issues confronting our society today.

Mitochondria are present in most living cells that include DNA.  Mitochondria are responsible for  a large portion of the energy generated by the cell.  Mitochondria are responsible for the generation of adenosine triphosphate (ATP) from adenosine diphosphate (ADP)  through aerobic processes using its electron transport chain (ETC).  The energy generated as ATP is many times greater than the energy generated through anaerboic glycolysis, which is an energy generation process that does not use oxygen.

The use by the cell of anaerobic  vs aerobic respiration has significance in studying various physiological processes which occur throughout the body.  These issues have implications in wide ranging areas from cancer to the relationship between sleep and wakefulness.

As energy is generated throughout the body, principles of conservation of energy must be satisfied.  Whether energy is generated through aerobic respiration and Oxidative Phosphoylation (OXPHOS)  using the mitochondrial electron transport chain (ETC), energy generation requires inputs and outputs that must be balanced.  This is a principle called "conservation of energy".  OXPHOS generates ATP,  the "energy equivalent of currency" in the body, energy in the form of heat, and outputs such as oxygen radicals (Reactive Oxygen Species (ROS))  as a byproduct of the process.

Oxygen Canisters

Oxygen reactive species such as superoxide (O-), hydrogen peroxide (H202) and the hydroxyl radical (OH-) can be generated depending upon a number of factors.   This includes natural process in the body involving signaling and homeostasis and also exposure to a number of environmental factors which may increase their generation.  Antioxidants may help the cell counter some of the impacts of reactive species.

Exposure to pollution, chemicals, toxins and radiation may increase oxygen reactive species exposure.  Radiation exposure may include ionizing radiation or non-ionizing radiation  such as cosmic rays  (e.g. gamma rays ).  Geomagnetic storms  and reduced ozone layer  protection at polar regions as Antarctica and the Arctic may increase such exposure, with greater historical ozone depletion  over the Antarctic.

I photographed in Antarctica in November/December 2004, and in October 2006 and photographed in the Arctic in July 2005.  The year 2006 saw the worst levels of depletion (2004 Image-Halley Bay Station, Antarctica) in recorded history.

Cellular processes guide apoptosis, or programmed cell death under a number of circumstances, generating  an intrinsic pathway or extrinsic pathway for cell death.  Reactive species play key roles in this process, as signaling mechanisms, and also in promoting cell death, as free radicals generated by a variety of situations trigger apoptosis.

Mitochondria play a large role in enforcing 'group identity' in a cell. The mitochondria helps to sustain certain energy needs within the body and when certain system parameters (group identity system requirements) are not fulfilled, the process of apoptosis or programmed cell death is intended to kill off certain cells that do not meet those system parameters.

Mitochondria can be loosely or tightly coupled; this means that they can "leak" protons so that more heat is produced (uncoupled) relative to amount of ATP produced;  there are certain uncoupling proteins  that aid in this process, which decreases  the generation of potentially damaging oxygen radicals.  A highly coupled system will thus be more efficient in the generation of energy, less efficient in generating heat, and will generate more oxygen radicals, which can cause damage to the system.  A more loosely coupled system will produce more heat, will generate less oxygen radicals, and will be less efficient in generating energy.  A loosely coupled system will be more valuable in colder climates due to the greater heat protection.  A tightly coupled one will result in more conditions, such as diabetes, which are impacted by the generation of oxygen reactive species.

The generation of reactive oxygen species is a significant issue in DNA damage  and mutations involving mutagenesis.  Mitochondrial DNA (mtDNA) are much less protected from the generation of reactive species than nuclear DNA.  In the proverbial sense, they sit at the edge of the  oxidative phosphorylation 'fiery furnace' and absorb more damage than nuclear DNA.  Nuclear DNA has greater protection from reactive species, being protected by histones   and telomeres.

Mitochondria can be damaged by reactive species, however, there is a certain amount of punishment that mitochondria can take before a process called heteroplasmy  takes place. Heteroplasmy in the mitochondria is a process where, due to mutation, mitochondrial damage or other process, more than one mitochondrial genome can exist.  This process may be associated with mitochondrial disease and be more extensive the greater the degree of heteroplasmy.  However some individuals may live to long ages with some degree of heteroplasmy.

There is a basic problem with mitochondrial damage and mutation in so far as the mtDNA and the nuclear DNA interoperate in the OXPHOS process.  This is because, as mentioned earlier in the article, some mitochondrial functions ages ago were shifted into the nuclear DNA through the process of gene transfer.  Cytochrome C belongs to the cytochrome c family of proteins and is an integral part of the ETC.  Cytochrome C has a long history, which goes back to time periods when the Earth was subject to heavy amounts of radiation.  Illnesses associated with Cytochrome C may involve both nuclear DNA and mitochondrial DNA.

Since Nuclear DNA has greater protection than mitochondrial DNA (mtDNA) from the insult of reactive species, the degree of damage in each case will differ, or in the case of nuclear DNA, there may be minimal or no damage.  This will lead to interoperability issues as mutations and damage occurs. Interoperability is the ability of systems to work together.  As oxidative stress occurs at different rates and to different but  inter-operating parts of the cell (mtDNA and nuclear DNA), illness and damage occurs, and potentially mutations.  This occurs in systems requiring heavier use of energy, including muscles.  Respiratory muscles bear the burden of oxidative stress, as these muscles are those subject to the greatest use during sleep.  Sleep apnea may be associated with higher levels of exposure to oxidative stress.

As we are subject to greater and greater levels of substances that create oxygen reactive species, we can see that problems can add up.  There are greater and greater chances of damage and mutations, the probability of heteroplasmy increases, the levels of heteroplasmy in the cell may come closer to the levels of heteroplasmy that may be tolerated in the cell without incurring mitochondrial disease.

We can see, therefore, that exposure to reactive species such as environmental toxins and radiation may provide for mutations in both nuclear and mitochondrial DNA, that these processes may occur at different rates, and that past a certain point, mitochondrial disorders may develop as the result of such exposure. At the same time, mutations that are beneficial may sometimes occur, and mutations and damage that are harmful may indeed result.  The ability for mutations that are adaptive to occur may reflect the ability of the mitochondrial DNA and the nuclear DNA to inter-operate, which is statistically difficult, considering the conditions under which each of these processes work.

Thus any process which seeks to advance a species by introducing mutagenic factors via the use of the creation of oxygen radicals must take into consideration that mutations and damage may result in the process and that individuals may be harmed in such process.  Due consideration must exist for who is subject to such exposure, and when the risk of subjecting certain individuals to such exposure constitutes a material risk that makes such experimentation untenable in  a civilized society.

 The risks of exposure to reactive species increases with the degree and length of the exposure, impacting the risk of early morbidity and mortality. Mutagenesis is more effective when it occurs in germ line cells which can pass mutations, either favorable, or unfavorable on to the next generation

Where such experiments are conducted, they must be conducted in an ethical fashion, they must be done with full informed consent of those involved, they must adhere to the law of civilized nations, and the ongoing experience of such studies must be monitored and measured so that those involved are not unduly harmed and the patient population put at excessive risk.

It must be made abundantly clear that if our society depends upon mutations to adapt the species to future environmental (or other) challenges, that those who have been subject to environmental (or other) assaults for such purpose be treated with due respect, that their contributions be valued, and their condition be measured, monitored and treated. It is clear that what these individuals are doing on a collective basis is aiding the future development of humanity. They are test subjects in a process that will benefit others, later.

What are our future ecological and planetary challenges and how can we adapt to them?  How do these challenges impact our exposure to environment risks and how we deal with them?  These are all important issues.

The mitochondria, as a vital cog in the production of energy has a very important part of the story that must be told as we seek to deal with the environment, climate change and other planetary challenges that we face.

Leptin

Butter

I attended a lecture in 2008 about leptin signaling given at Harborview Medical Center through their research programs on diabetes, metabolism and obesity.  The lecture, although highly technical, was  interesting and it gave me plenty to think and read about.

Leptin is what is called a signal transducer.  A signal transducer is an extracellular  signaling molecule that activates a receptor inside or on the cell surface, initiating a series of events, biochemical reactions.    Leptin signaling is involved in a number of areas relating to the management of energy throughout the body, regulating or giving permission for the use of energy for a variety of vital functions.  As I read more about leptin, it led me into a labyrinth of other, associated issues.

Leptin is involved in signaling relating to mesolimbic (dopaminergic) reward centers, food, satisfaction, glycemic control, saiety and reproduction.  Leptin deals with long term energy storage, provision of energy to the brain and gives permission for the use of energy falling within its defined duties.  Intuitively, one wonders what happens if energy demands are requested for things that aren't associated with its associated duties.

Leptin acts to communicate to the Central Nervous System the availability of energy stores.  It acts to restrain food intake and induce energy expenditure, when necessary.   Leptin acts with other systems, such as the Sympathetic Nervous System,  and with factors such as thyroid hormone  and insulin,  in regulating energy use throughout the body and in insuring the thermodynamic  efficiency of skeletal muscle, for example.  Leptin is also involved involved in the cardiovascular system, for example in cardiac hypertrophy.

Leptin is increased, or up-regulated, in obese people.  It increases appetite, generates a low metabolic rate, decreases thyroid function and is impacted by sleep apnea  issues.  Dysregulation of leptin adversely impacts fertility.  Leptin acts on lipid and glucose metabolism.  Leptin also regulates bone metabolism.  This may serve to improve structure with increasing weight by regulating the allocation of higher density bone development.    Leptin resistance occurs during obesity when increasing leptin levels do not have an impact.

Leptin acts in the brain in a neuroprotective  fashion that may also impact memory.  Leptin may be necessary to protect the cell against cell death (apoptosis).

Leptin plays a key role in thermoregulation, working through diverse systems such as the brain's preoptic area and hypothalamus.  Studies in the brown adipose tissue (BAT)  of mice injected by virus indicated involvement of leptin in regulating BAT circuits.  Severely obese mice that lack leptin or its receptor show decreased BAT thermogenesis, and are thus challenged to maintain their body temperature and adapt to cold temperatures.

Leptin may be a key component in considering survival issues under a variety of scenarios or projections associated with climate change modeling.  It may react to a variety of seasonal (zeitgeber) cues, as well as sexual cues regarding melatonin , odor and reproduction.  It will react to hedonistic feelings regarding food, appetite and to the allocation of resources regarding shorter term versus longer term energy needs.

Leptin plays its role along with a host of other players in this complicated web of life.