A New Hope for Afflicted Mothers

As autonomous entities with our own agency, we have control over a huge portion of our lives; may it be our interactions with others or our food choice, our cognition and autonomy has allowed us to dictate our own fortune. Unfortunately for some, the aforementioned freedom becomes heavily curtailed by the presence of genetic diseases/disorders – one of the few aspects of fate that we are almost helpless to. Millions of people world-wide inherit some sort of disease due to kinship, forever condemned to a lifestyle they never consented to. Within the present unit of hereditary genetics and genetic engineering, we often discussed the prospect of utilizing genetic recombination to cure a multitude of different genetics-based diseases. Due to the brevity on the topic, and the heavy implications of the field, I was immediately captivated by the concept of genetic manipulation and engineering; questions regarding the efficacy and potency of the aforementioned mechanisms, in addition to their ethical grounding, has inspired me to dedicate the February blog post towards biotechnology and its pathological implications. Beyond the assignment, recombination and bio-manipulation lies even closer to heart as certain family members (overseas) have been diagnosed with mild genetics-linked diseases; now, the blog’s discourse can finally act as a springboard for discussion, while simultaneously acknowledging the hopeful future for all those impacted by hereditary conditions. In addition, my one true aspiration involves medicine and applied biology; as I will eventually enter the professional field of genealogy, the issue regarding biotechnology and bio-manipulation weighs even more heavily in my mind.

Out of all the different types of hereditary diseases in the world, this blog post will specifically focus on the devastating effects of mitochondrial disease. As a brief overview, mitochondrial disease involves mutations in the genetic composition of mitochondrial dna (independent dna located in the mitochondria). Due to the principles of prenatal development, all of our mitochondrial dna derives from the mother’s cytoplasm; thus, once the mother develops mutations within the mitochondrial dna of her gametes, there is little escape from a life of mitochondrial disease. According to the Council of Responsible Genetics, “Mitochondrial disease is a genetic disorder that can cause a variety of malfunctions throughout the body, including stunted growth, an increased risk of infection, diabetes, disease of the heart, liver, and kidneys, visual and auditory deficits, and loss of coordination and muscle weakness, various neurological problems, and seizures. Most symptoms affect children before the age of 10, though mitochondrial malfunctions can play a role in age-related diseases as well, such as multiple sclerosis and Parkinson’s disease.4,5 Approximately 1 in 10,000 people suffer from some form of mitochondrial disease today, and as many as 1 in 200 are carriers” (Council of Responsible Genetics n.d.). Afflicting as many as 1 in 10,000, mitochondrial diseases have an extremely wide-spread scope in the forms of a plethora of diseases. Diseases such as mitochondrial myopathy, diabetes mellitus, leber’s hereditary optic neuropathy, wolff-parkinson-white syndrome, leigh syndrome, subacute sclerosing encephalopathy, neuropathy, ataxia, retinitis pigmentosa, ptosis, myoneurogenic gastrointestinal encephalopathy, myoclonic epilepsy ragged red fibers, etc. are all mitochondrial diseases impacting the general population. To this day, mothers afflicted with the aforementioned pathologies have no choice but to refrain from having children.

Recently, advancements and breakthroughs in applied genetics have provided a bit of sunshine amidst all the hereditary “gloom”, presenting afflicted mothers with another option and a new life. In order to avoid the passage of mitochondrial dna to the offspring, major research labs have successfully conducted in-vitro fusion of egg and donor mitochondrial dna: “Using this technique, the donor nuclear DNA is extracted from the donor egg, leaving only the donor mitochondrial DNA. Then, the fertilized nuclear DNA from the mother’s egg is extracted and placed into the donor egg. The end result is a donor egg, containing donor mitochondrial DNA and the nuclear DNA of the intended parents. Developers of this technique claim the child produced would express the genetic traits from her intended parents, but possess the donor’s mitochondria” (Council of Responsible Genetics n.d.). With the original genetic information from the afflicted egg implanted in a “surrogate” egg containing only cytoplasmic contents, the impacts of mutated mitochondrial dna can be avoided while still creating off springs that genetically “belong” with the parents. With the aforementioned technology, millions of mothers world-wide will be granted a second chance at raising a child of their own.

Despite the simplistic description of mitochondrial dna transfer, the genetic engineering behind the process is extremely messy. While initial lab results have been positive, the impacts of mitochondrial dna transfer on neonatal babies can be extremely volatile. The Council for Responsible Genetics (CRP) have conducted analysis on the efficacy and ethicality of mitochondrial dna transfer with “studies [that] tracked the effects of MR only to the age of three. Studies in mice and other animals have suggested that harmful effects may not become apparent until adulthood and that problems from swapping mitochondria show up disproportionately in males and often affect fertility” (Council for Responsible Genetics n.d.). Thus, children born from mitochondrial dna transfer have the possibility of possessing more detrimental pathologies than the genetic disease, casting them into the same boat as before the intervention. In addition, several other ethical questions have been raised against the implementation of the dna transfer method. DNA transfer involves the alteration of entire lineage’s mitochondrial dna, changing thousands of years’ worth of genetic kinship without consent. In addition, mitochondrial dna have been found to impact the behavior of children after they have reached a considerable age; manipulating the genetic information inevitably manipulates the offspring’s composition, behavior, and psychology. What’s more, “A secondary line of criticism is the fear that genetic engineering techniques like mitochondrial DNA transfer will lead to genetic engineering for enhancement purposes rather than purely medical ones, acting as a “gateway” genetic engineering technique that could lead to eugenic applications. Some critics of mitochondrial DNA transfer also feel that interfering with something as powerful as mitochondrial DNA would be essentially “playing God.”44 They believe that once we take the first step into modifying the genome, it will be a slippery slope to continue along this path and begin allowing parents to choose “desirable” traits for their children—such as high intelligence, height, and specific hair colors.” (Council for Responsible Genetics n.d.).

Taking into consideration all of the potential benefits and detriments of mitochondrial dna transfer, the technique nevertheless exists as one of humanity’s best chance against mitochondrial pathologies. Other questions such as implementation, cost, and ethics, however, cannot go unconsidered. How much of your child will actually be “yours” if the mitochondrial dna is from a donor? What is the projected cost of mitochondrial dna transfer? Will the UK (and more importantly, the world) ever legalize the usage of the new method? Hopefully, these questions will be answered as research on mitochondrial dna transfer proliferates through the biological community, and as I trudge deeper into the topical literature. Until next time!

– W

Explore these sources!!

http://www.umdf.org/site/c.8qKOJ0MvF7LUG/b.7934627/k.3711/What_is_Mitochondrial_Disease.htm

http://www.councilforresponsiblegenetics.org/pagedocuments/yn3rbrq4go.pdf

http://en.wikipedia.org/wiki/Mitochondrial_disease#Examples

Council for Responsible Genetics, n.d. Human Genetic Engineering Current Science and Ethical Implications. Retrieved from: http://www.councilforresponsiblegenetics.org/pagedocuments/yn3rbrq4go.pdf

Photorespiration – Friend or Foe? (Exploring the beneficial properties of photorespiration)

Throughout our extensive unit on photosynthesis/cellular respiration, the aforementioned concepts were hammered into our memories through multiple packets and instructive videos. By the end of the aforementioned section/topic, I was certain that we had hit every single key point of cellular metabolism in relation to plants and other autotrophs – until I unexpectedly bumped into the concept of photorespiration while flipping through the Campbell book. The concept also surfaced in one of our class discussions regarding the basics of CAM and C4 plants (chalk exercises), inciting further fascination. After closer inspection, I deduced that photorespiration describes a metabolic path way in which Rubisco bonded RuBP with O2 (instead of the usual Co2) resulting in a seemingly useless product; the production of the O2-RuBP product requires input of energy (for the precursory reactions) without generating any ATP in return (it’s missing the crucial carbon source conventionally found in the CO2). Slightly confused and even more so curious regarding the counterintuitive process of photorespiration, the aforementioned topic caught my attention in the evolutionary context: why has photorespiration survived evolutionary selection if the process required more ATP than it produced? Shouldn’t evolution have shunted photorespiration out of existence if the process was metabolically draining and even fatal to plants? The remainder of this blog post explores the evolutionary benefits of photorespiration and the fundamental reasons to its survival throughout the spectrum of time.

As briefly aforementioned, the term “photorespiration” describes the rare scenario when either Co2 levels are too low and/or O2 levels are extraordinarily high within the plant. In either of these conditions, the carbon fixation with the Ribulose Phosphate (RuBP) fails to occur; instead, Rubisco mistakenly binds O2 with RuBP. Unfortunately, the complete lack of carbon within O2 deprives the Calvin-Benson Cycle of the necessary carbon that constitutes C6H12O6, preventing the creation of glucose and ultimately depriving the plant of necessary energy storing molecules. Fortunately, photorespiration exists as a rare phenomenon, with certain beneficial uses under specific conditions. Explored extensively within Wingler, Lea, Quick, and Leegood’s Photorespiration: metabolic pathways and their role in stress protection, the process of photorespiration provides three crucial impacts to plant function: glutathione production, drought protection, and excess light protection – all explored below. The first key implication of photorespiration involves the metabolic production of glutathione as a byproduct of the RuBP-O2 product. Catherine Gutherie of Experience Life Magazines describes glutathione “as [a peptide that] protects the cell’s engine, called the mitochondria, from bacteria and viruses as well as toxins. It’s considered “the mother of all antioxidants,” as Hyman calls it, because all other antioxidants, including vitamin C and vitamin E, rely on it to give them a second life. The average antioxidant has a short life span, sacrificing itself whenever it wipes out a free radical. But glutathione carries enough extra zip to not only bring spent antioxidants back from the dead but also to recharge itself, explains Leslie Fuller, ND, an educator at the National College of Natural Medicine and practitioner at the Nature Cures Clinic, both in Portland, Ore” (Gutherie 2011) This “mother of all antioxidants” as dubbed by Gutherie/Hyman is absolutely crucial to all cellular life as it combats and mitigates the effects of oxygen free radicals. Oxygen free radicals are molecules that are missing electrons. In a desperate and frantic attempt to acquire the missing electron(s), these “free radicals” forcefully steal subatomic particles from neighboring molecules, disrupting chemical composition and hence function. Antioxidants can be perceived as the cell’s protector: it acts to neutralize the free radicals, preventing the pesky molecules from “stealing” other electrons. As Gutherie describes, glutathione allows for recharging of other antioxidants (Vit C, Vit E, etc.) that allow for further “combat” against the destructive free radicals. With the aforementioned in mind, researchers Wingler, Lea, Quick and Leegood found in their study of GS2  mutant plants and implications of photorespiration that:  “Photorespiratory metabolites can be provided as substrates for other processes (Keys 1999). Glycine produced in the photorespiratory pathway can be used for the synthesis of glutathione [an important antioxidant used by plants to prevent damage from reactive oxygen radicals, free radicals, and peroxides] (Noctor et al. 1997, 1998, 1999) or be exported out of the leaves (Madore & Grodzinski 1984). Some flexibility in photorespiratory nitrogen metabolism is achieved by the use of alternative amino donors. In addition to [photorespiration-generated] glutamate and serine, alanine and asparagine provide amino nitrogen for the synthesis of glycine” (Astrid Wingler, Peter J. Lea, W. Paul Quick, and Richard C. Leegood 2000). Thus during the process of photorespiration, glutathione and other essential amino acids (glutamate, serine, alanine, asparagine) are formed from the byproducts of the RuBP-O2 reaction, allowing for the production of essential antioxidants for the afflicted plants. In turn, these antioxidants provide an elevation in protection against oxidization and the disruptive effects of oxygen free radicals, allowing for plant health and efficient functioning.

In addition to the beneficial impacts of anti-oxidant production, photorespiration provides for two additional lines of defense against external influences of drought and light. In each of the two scenarios, a lack of carbon fixation prevents the continuation of electron flow, causing for the build-up of high energy (unstable) carrier molecules, ultimately leading to plant tissue harm. In the former situation, drought stress prevents the opening of stomata; with water retention already a huge concern in levels of low precipitation, water cannot not be further lost through transpiration. Hence the plant is forced to close their stomata. Unfortunately, the closing of stomata also implies a lack of Co2 flowing into the plant (due to the blockage in gas exchange), preventing the Calvin cycle from occurring. The charged and reactive NADPH and ATP molecules that would originally deposit their energy for the formation of PGA/G3P find themselves with nowhere to go – the Calvin cycle is literally at a standstill due to the lack of Co2. Thus photorespiration (RuBP + O2) performs the role of accepting the energy from ATP and NAPDH, preventing any further tissue damage from excess energy. The London team of researchers confirms the aforementioned theoretical process by finding that “Long term, drought stress has, however, been shown to result in lower fructose-1,6-bisphosphatase activities and a decline in the amounts of sedoheptulose-1,7-bisphosphatase and NADP-dependent glyceraldehyde-3-phosphate dehydrogenase proteins (Wingler et al. 1999b). [However]. the amounts of photo respiratory enzyme proteins (proteins of the GDC complex, GS-2, SGAT) were not affected by drought stress. Therefore, photorespiration could serve as an important means to maintain electron flow; with decreasing rates of CO2 assimilation almost linearly in the wild-type, the mutants with reduced activities of photorespiratory enzymes accelerated [this decrease], resulting in lower rates of CO2 assimilation at moderate drought stress [compared to with photorespiration]” (Astrid Wingler, Peter J. Lea, W. Paul Quick, and Richard C. Leegood 2000). Hence, photorespiration provides for significant drought stress alleviation by providing a “drop off zone” for energy carrier molecules reduced from the light dependent reactions. Under dramatic situations and utilized sparingly, photorespiration proves to be less of a detriment and more as a mode of protection against drought/Co2 depletion. The same logic applies to excess light, where the plant absorbs too many photons of light but lacks sufficient Co2 to fix during the Calvin Cycle. In order to oxidize ATP and NADPH for the prevention of over accumulation and tissue damage, photorespiration provides for a way to “use up” excess energy without producing glucose. What’s even more, the evolutionary selection for plants capable of utilizing photorespiration as a means of light protection have been extensively studied: “Plants that are impaired in their ability to carry out photorespiration (due to defective genes) are more susceptible to damage induced by excess light. Researchers consider this clear evidence that photorespiration acts to neutralize the otherwise damaging products of the light reactions, which build up when a low CO2 concentration limits the progress of the Calvin cycle. “(Campbell 2009). Despite initial intuition regarding the wasteful nature of photorespiration, closer analyses of the metabolic process uncovers the beneficial implications of RuBP+O2 in moderation.

Arriving at the end of my journey through the different facets of photorespiration, it is clear to see that amidst the detrimental impacts of an inherently wasteful metabolic process are glimmers of beneficial assets. The production of Glutathione, drought stress protection, plant “sunscreen”, etc. all affirm the premise that photorespiration does deserve to evolutionary exist and persist into the future. Hence the ultimate question and thesis of this blog appears to be answered: photorespiration survived despite its wasteful properties due to its protective properties (in moderation of course) against drought, free radicals, overexposure, etc. With that said, other questions still lurk beneath the surface. What is the threshold for photorespiration –exactly how much photorespiration is too much? Can photorespiration be genetically induced via biotechnology? If so, what are the economic and agricultural implications of genetically engineered photorespiration in regions of heavy droughts? Hopefully, these questions will be answered as research on photorespiration proliferates through the biological community, and as I trudge deeper into the topical literature. Until next time!

– W

Explore these sources!

Astrid Wingler, Peter J. Lea, W. Paul Quick, and Richard C. Leegood, 2000. Photorespiration: metabolic pathways and their role in stress protection. Retrieved from http://eprints.whiterose.ac.uk/164/1/leegoodrc6.pdf

Jane B. Reece, Neil A Campbell, et.al. 2011. Campbell Biology. Pearson.

Catherine Gutherie , 2014. Glutathione: The Great ProtectorExperience Life. Retrieved from <https://experiencelife.com/article/glutathione-the-great-protector/&gt;.

Renaturation — The Exploration of Denaturation’s Counterpart

Throughout my 3 years of studying biochemistry – especially regarding that of protein folding discussed in class – the curriculum has always emphasized the important implications of protein denaturation due to excessive heat, pH, etc. The biology curriculum has etched within our minds the importance of protein limitation as they constitute a significant percentage of enzymes – the ultimate catalyst for life. However, the 3 years of biology (this year included) has failed to enlighten about denaturation’s counterpart: renaturation and the powerful implications of protein refolding. The aforementioned topic has always held value, tingling my curiosity, for the study of renaturation can bring about powerful remedies in the bio-medical field (one that I plan to explore in the near future)

Currently, medical innovation have given rise to “elegant and well established recombinant DNA methodologies [which] have set the stage for the production of heterologous proteins in microbial hosts” (Lilie, Schwarz, Rudolph 1998); through the application of recombination, a plethora of host microbial organisms have been genetically modified to produce certain desired proteins (insulin being a fine example). Unfortunately, the limited regulation of recombination/protein production has resulted in multiple cases of over production; “An increase in the concentration of non-native polypeptides due to high expression levels seems to be responsible for aggregation of the recombinant protein. This assumption was quantified in a kinetic model that analyzed the yield of native protein as a function of the competition between folding and aggregation” (Lilie, Schwarz, Rudolph 1998). The kinetic model establishes the tendency for protein production rates to vary time to time, to the point where the number of proteins requiring chaparonin enzymes for proper folding outweighs the number of chaparonin (protein folding) complexes present. These “extra” protein segments then accumulate into insoluble, wasted protein aggregates, inflicting massive losses and immense reduction in protein production efficiency. However, researchers Hauke Lilie, Elisabeth Schwarz, and Rainer Rudolph of Germany have investigated the usage of protein revitalization and renaturation as a solution to these inclusion protein aggregates. Utilizing different methods of renaturing protein aggregates in E.coli hosts (CoFactor addition, Sulfur methods, etc.), Lilie, Schwarz, and Rudolph have found that renaturation requires “the control of parameters such as temperature, pH or redox conditions, the presence of low molecular weight compounds in the renaturation buffer” (Lilie, Schwarz, Rudolph 1998) for unimpaired functioning. In addition, several other components in renaturation baths are required to A) prevent future protein aggregation and B) to facilitate efficient and optimal conditions for protein refolding. According to the German team’s trials, “Specific cofactors, such as Zn2+ or Ca2+, can stabilize proteins already at the level of folding intermediates, thus, preventing off-pathway reactions. Besides such cofactors and prosthetic groups, a large series of low molecular weight additives are, in certain cases, very efficient folding enhancers: non-denaturing concentrations of chaotrophs, such as urea or GdmCl, for example, are essential for the renaturation of reduced chymotrypsinogen A and have been shown to promote folding of several other proteins” (Lilie, Schwarz, Rudolph 1998), providing a solution to the pesky inclusion protein aggregates and shedding light to a promising field of research and development. Thus, renaturation stabilizes the intermediates of proteins, preventing them from entering “off road” pathways. In addition, the process breaks down the inclusion aggregations, restructuring the protein fragments to its original format. Through the aforementioned procedure, A) protein production rates would reach its prime state, producing more of the essential proteins demanded (i.e. insulin) while also B) opening the doors for more applications utilizing the renaturation as a solution to the detrimental effects of denaturation.

After reading the esoteric article (wow that was laborious to get through!) presented by researchers Hauke Lilie, Elisabeth Schwarz, and Rainer Rudolph, several other questions regarding the renaturation process still linger. How will the rates of renaturation compare to rates of protein aggregate formation and denaturation? Can renaturation still function without the removal of the denaturant? How costly will the process of renaturation be, and will it present itself as a practical solution (financially-wise) for inclusion protein aggregates? Hopefully, these questions will be answered as research on the renaturation process proliferates through the biological community, and as I trudge deeper into the topical literature. Until next time!

– W.

Lilie Hauke, Schwarz Elisabeth, Rudolph Rainer, 1998. Advances in refolding of proteins produced in E. coli. Retrieved from http://web.mnstate.edu/provost/Advancesproteinrefolding.pdf

The Arms Race

The clearest examples of coevolution often fall into the category of predator-prey relationships; through a small scale arms race, the influence of the predator on the prey (and vice versa) is morphological-ly and physiologically apparent. Take a population of garter snakes and rough skinned newts for example. As a natural predator, the garter snake feeds upon rough skinned newts. Newts that fail to produce effective defense mechanisms are picked off and consumed, whereas those that excel at repelling garter snakes — due to genetic mutations — are left to reproduce (simple Darwinian evolution). Due to the selection pressures, the newt population became slowly dominated by individuals who excelled at producing the tetrodotoxin (TTX) venom as a deterrent for predators. lol

In response to the newt adaptations, the garter snake population also undergoes evolution; those that fail to neutralize the TTX venom are less evolutionarily fit as the “TTX does not kill resistant snakes, [but] often slows [the less resistant] down for a while. Less-resistant snakes move slower after TTX injection, and some are even temporarily paralyzed” (Martin 2008), causing them to 1. lose their prey, and to 2. expose themselves in unfavorable conditions (paralyzed and unable to fend off predators). On the other hand, garter snakes that are (through mutations) unaffected by newt poisons remain to proliferate within the population.

Hence, both populations underwent evolution due to each other’s adaptations. With every “round” of co-evolution, natural selection favors the newts most apt at producing the TTX poison and the garter snakes with the greatest tolerance. Over time, the rough skinned newt population became more and more toxic by producing greater amounts of TTX, while the garter snake population became more and more immune to the aforementioned toxin. The predator-prey relationship of the garter snakes/rough skinned newts provides a clear example of how coevolution functions.

– W

Shelby Martin, March 12, 2008. Snakes slither past toxic newts in evolving race. Retrieved from http://news.stanford.edu/news/2008/march12/newts-031208.html

Paedomorphosis – An Introduction to Human Body Plans

In almost every single class dedicated to the study of natural sciences (biology especially), a central “dogma” has always been engrained into our minds – that mutations associated with mental/physical retardations and the like are “un-natural”, often embraced with a negative connotation synonymous with “detriment”. Even within the social context, we tend to view those with stunted/impaired morphological development in a pitying/negative light. It is from this aforementioned springboard, that I became increasingly interested in function of body plans, ultimately leading me to ask the question: Are there any “natural” forms of morphological retardation shared by the human species? And the answer was …

Paedomorphosis – the developmental processes in which adults retain body plans seen in the infant stage, most commonly associated with A.  progenesis (acceleration of sexual maturity) or B. neoteny  (retardation of body parts). My initial exposure to this particular biological concept came from my best friend — Campbell’s AP Biology textbook (Chapter 34), in which the most basic explanation of paedomorphosis was provided. Prior to research, I knew that the aforementioned was associated with the natural alteration of body plans (early sexual maturation or retardation of physical development), most likely naturally selected for. I was also aware of its significant presence within the amphibian and reptilian classes, but that was pretty much all. The next leap was to expand my knowledge on paedomorphosis, with a “twist” – the application of the principle to the human species. Interestingly enough, paedomorphosis in the human sense “refers to the phylogenetic processes that lead to the evolution of facial underdevelopment. The paedomorphic feature, then, is one that has evolved through changes in the timing and rate of development and is species specific” (Wehr, 2005). The article, “Three theories for facial paedomorphosis in human evolution and the preference for facial underdevelopment”, then continues to provide explanations to why natural selection has facilitated paedomorphosis in humans specifically. According to Dr. Wehr, underdevelopment of the human facial structure allows for the “mimicry associated with youth and fertility, while also being a necessary antecedent to brain expansion and human cognition” (Wehr 2005) — all characteristics that increase the functionality and reproductive success of human individuals. Further, the author discusses different attraction oriented studies observing our biological affinity to larger eyes, smaller noses, and shorter chins – all characteristics seen in the infant stages of our species. Hence through Wehr’s article, I have answered my original question regarding “natural” body retardation; I have learned that the paedomorphic process in humans was most commonly associated with the underdevelopment of faces, and is positively correlated with the sexual success that the look of “youthful fertility” brings about. Like all beautifully written research papers, Dr. Wehr’s study in human paedomorphology incited a plethora of additional questions such as: “Evolutionarily wise, are there any other anthropoids that exhibit facial under-development ?” and “how does the facial structure differ, if a person is afflicted with a condition that prevents natural paedomorphosis?”. These questions and more will continue to fuel my interest in the biological concept of paedomorphosis, as we continue our exploration in the study of body plans.

– W

Wehr, P. (2005). Three Theories For Facial Paedomorphosis in Human Evolution and the Preference for Facial Underdevelopment. Retrieved from https://circle.ubc.ca/bitstream/handle/2429/16943/ubc_2005-104554.pdf?sequence=1

For further information, visit https://circle.ubc.ca/bitstream/handle/2429/16943/ubc_2005-104554.pdf?sequence=1