Tag: richard owen

Duck-Billed Platypus Venom: Designed for Discovery

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BY FAZALE RANA – JANUARY 4, 2017

I wouldn’t classify it as a bucket-list experience, but it was off-the-charts cool to see a duck-billed platypus up close a few years ago when my wife and I visited Tasmania. This little creature reminded me of a beaver as he swam around in the water.

But as cute and cuddly as the duck-billed platypus appears to be, I came to learn (not by experience but by listening to the zookeeper) that you don’t want to mess with this egg-laying mammal. The platypus has spurs on its hind feet, and for males, the spurs are loaded with venom. Being struck by a platypus’s spurs is no pleasant thing. The venom can kill a small animal (such as a dog) and cause excruciating pain for humans.

Not only does the duck-billed platypus fascinate animal lovers, it has captured the attention of the scientific community. This creature is neither a placental nor a marsupial mammal. Instead, it belongs to an unusual group called the monotremes. Biologists regard monotremes as primitive mammals. And because they group apart from other mammals, many life scientists believe that they can learn a lot about the mammalian biology (including human biology) through comparative studies of the monotremes.

Recently, researchers from Australia demonstrated the value of studying platypus biology when they discovered that a gut hormone (GLP-1) which regulates blood sugar levels doubles as a component in the duck-billed platypus’s venom.1 They believe that this insight may lead to a new drug treatment for type 2 diabetes.

To appreciate why this research team thinks that the platypus GLP-1 hormone may have use in treating diabetes, a little background is in order.

GLP-1

Found in all mammals, glucagon-like peptide-1 (GLP-1) belongs to a family of biomolecules called incretins. These compounds serve as metabolic hormones that stimulate a decrease in blood glucose levels. Secreted in the gut, GLP-1 ultimately lowers blood sugar levels by making its way through the blood stream to the pancreas. GLP-1 stimulates the beta-cells in the pancreas to release insulin. In turn, insulin causes the liver, muscles, and adipose tissues to take up glucose from the blood.

GLP-1 is named after glucagon. A blood hormone, glucagon has the opposite effect as insulin. When released by the alpha-cells of the pancreas, glucagon stimulates the liver to break down glycogen and then release glucose into the blood stream. Glucagon exerts its effect when the blood sugar level drops. Like GLP-1, glucagon also stimulates insulin release, so when the blood sugar level rises (because of glucagon’s release from the alpha-cells), the sugar is quickly taken up by muscle and adipose tissues.
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Image: Insulin and glucagon regulate blood glucose levels in the human anatomy, specifically the liver and pancreas.

Eating food stimulates the release of GLP-1 in the gut. This ingenious design ensures that insulin is released and the liver, muscles, and fat tissues are poised to take up glucose even before blood sugar levels rise as nutrients are absorbed into the bloodstream via the digestion process. This preparation is vital, because elevated levels of blood sugar have dangerous long-term consequences.

Platypus Venom

To the surprise of the Australian researchers, the venom of the duck-billed platypus contains GLP-1. Other animals, such as the Gila monster, have venom components that are structurally analogous to GLP-1, but are distinct molecules. (In the Gila monster, this bio-compound is called exendin-4.) Again, an ingenious design. Including incretins in venom causes blood sugar levels to drop after the venom is injected into the victim. Lowered blood sugar levels create confusion and lethargy.

Unlike GLP-1, GLP-1-like venom components of, say, the Gila monster, are long-lived in the bloodstream because they have structural features that make them resistant to digestive enzymes such as dipeptidyl peptidase. This enzyme targets GLP-1 after its release to ensure it is quickly destroyed once this gut hormone triggers insulin release. If not quickly removed, insulin release would persist, thereby causing blood sugar to plummet to dangerously low levels.

The structure of the GLP-1 produced by the duck-billed platypus appears to be fine-tuned so that this biomolecule can balance its two roles as a gut hormone and a venom component. And this property makes the platypus GLP-1 an intriguing molecule to biomedical scientists looking for more effective ways to treat type 2 diabetes. The duck-billed platypus GLP-1 is an actual gut hormone (as opposed to an analog), but is much longer lasting, which makes it an ideal anti-diabetic drug.

Type 2 Diabetes

The most common form of the disease, type 2 diabetes results primarily from lifestyle effects: namely, obesity and lack of exercise. (Although there also appears to be a genetic contribution to this form of diabetes.) In type 2 diabetes, the capacity of beta-cells in the pancreas to secrete insulin becomes impaired, usually because of the accumulation of amylose in their interior. Reduced insulin secretion causes blood sugar levels to remain elevated at dangerously high levels. Persistently elevated blood sugar levels can lead to heart disease, stroke, loss of vision, kidney failure, and impaired blood circulation to the extremities.

Treatment for type 2 diabetes centers around dietary changes designed for keeping blood sugar levels low, weight loss, and increased exercise. Anti-diabetic medications also play an important role in managing type 2 diabetes. Pharmacologists have developed an arsenal of drugs, but all of them have their shortcomings.

Platypus GLP-1 as an Anti-Diabetic Medication

Because of the limitations of current anti-diabetic medications, pharmacologists are intrigued by the platypus version of GLP-1. Like all variants found among mammals, this gut hormone lowers blood glucose levels, but because it doubles as a venom component, it has a longer half-life than the GLP-1 hormones produced by other mammals—an ideal set of properties for an anti-diabetic drug. In fact, there is already a precedent for using venom components to treat diabetes. Exendin-4 from the Gila monster has been developed into a last resort anti-diabetic drug called Exenatide.

The Case for Evolution, the Case for Creation

It’s provocative that the biology of a creature, such as the duck-billed platypus, could provide such important insight into human biology that it can drive new drug development, positively impacting human health.

This study highlights the clever designs that characterize biochemical systems. The function of GLP-1 as an incretin and, in turn, its employ as a venom component are nothing less than genius. The elegance and sophistication of biochemical systems are precisely the characteristics I, a Christian biochemist, would expect to see, if, indeed, life stems from a Creator’s handiwork. In contrast, sophistication and ingenuity aren’t the features I would expect if evolutionary mechanisms—which are unguided, co-opting preexisting designs and cobbling them together to produce new designs—have generated biochemical systems.

Still, many people in the scientific community would argue that as hard as it may be to believe that biochemical systems evolved, it must be the case. Why? Because of the shared features that characterize these systems. As a case in point, the GLP-1 gut hormone is found in all mammals. So, presumably, this biomolecule emerged in the evolutionary ancestor of mammals and persists in all mammals today. Likewise, the shared features of GLP-1 and exendin-4 found in the Gila monster venom indicate to many biologists that the venom component must be evolutionarily derived from GLP-1.

Yet, as a creationist and an intelligent design proponent, I choose to interpret the universal nature of the cell’s chemistry and shared features of biochemical systems as manifestations of archetypical designs that emanate from the Creator’s mind—inspired by the thinking of Sir Richard Owen. To put it differently, for me, the shared features reflect common design, not common descent.

Of course, this leads to the follow-up rebuttal: Why would God create using the same template? Why not create each biochemical system from scratch to be ideally suited for its function? As I pointed out recently, there may well be several reasons why a Creator would design living systems around a common set of templates. In my estimation, the most significant reason is discoverability. The shared features of biochemical systems make it possible to apply what we learn by studying one organisms to all others, in some cases. As a case in point: The occurrence of GLP-1 in all mammals and the shared features of GLP-1 and exendin-4 make it possible to gain insight into human biology by studying the duck-billed platypus.

This discoverability makes it easier to appreciate God’s glory and grandeur, as evinced in biochemical systems by their elegance, sophistication, and ingenuity.

Discoverability of biochemical systems also reflect God’s providence and care for humanity. If not for the shared features, it would be nearly impossible for us to learn enough about the living realm for our benefit. Where would biomedical science be without the ability to learn fundamental aspects about our biology by studying model organisms such as yeast, fruit flies, and mice? How would it be possible to identify new medications if not for the biochemical similarities between humans and other creatures, such as the duck-billed platypus?

Far from making no sense, the shared features in biochemistry are a manifestation of the Creator’s care and love for humanity.

Resources

Endnotes

  1. Enkhjargal Tsend-Ayush et al., “Monotreme Glucagon-Like Peptide-1 in Venom and Gut: One Gene—Two Very Different Functions,” Scientific Reports 6 (November 29, 2016): id. 37744, doi:10.1038/srep37744.
Reprinted with permission by the author
Original article at:
https://www.reasons.org/explore/blogs/the-cells-design/read/the-cells-design/2017/01/04/duck-billed-platypus-venom-designed-for-discovery

Q&A: Why Would an Infinite Creator Employ the Same Designs?

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BY FAZALE RANA – DECEMBER 21, 2016

Because I am a Christian, I see evidence for design in the biological realm. But for me, the converse is also true. Because I see design in the biological realm, I am a Christian. In fact, the elegant designs of biochemical systems convinced me as a graduate student that a Creator must exist and be responsible for life’s origin, paving the way for my conversion to Christianity.

Yet, many skeptics see the features of biological systems very differently than I do. They maintain that life’s origin, design, and diversity are best explained as the outworking of evolutionary processes. As evidence for this view, biologists point to the shared biological and biochemical features (homologies) possessed by organisms that naturally group or cluster together.

Homologous features may perform different functions and superficially appear different, yet they are fundamentally built around the same design. The quintessential example of a biological homology is the vertebrate forelimb—the human hand, the whale’s flipper, a dog’s paw, a bird’s wing, etc. Though these forelimbs are structurally distinct and perform different biological tasks, they are fundamentally built around the same design. The forelimb of every vertebrate consists of a long bone (humerus) in the arm, an elbow, two bones in the forearm (the radius and ulna), wrist bones (carpals), bones in the “hand” (metacarpals), and “fingers” (phalanges).

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Image: Homologous structures of the vertebrate forelimb. Image Credit: Wikipedia

Evolutionary biologists interpret homologous structures as evolutionarily derived from ancestral features possessed by the common ancestor of the group. With respect to the vertebrate forelimbs, biologists maintain that the forelimb of the first tetrapods had the same design as all vertebrate forelimbs. However, through the course of evolutionary history, natural selection altered the vertebrate forelimbs to perform a variety of functional roles.

However, as a creationist and a design proponent, I maintain that homologous structures have been designed around an archetypical plan that existed in the Creator’s mind. To put it another way, homologous structures reflect common design, not the outworking of common descent.

My view on shared biological features led my Facebook friend Phil, a skeptic, to ask the following questions:

“Just think about the diverse range of creatures an actual creator could have made. And yet we see creatures appearing like and acting like family cousins instead. What would compel an actual designer with unlimited power to design all creatures with the same template, as if the design was a restriction on the designer? Perhaps it was to make belief more difficult, to make only rebellious (non-credulous) hearts disbelieve?”

Interesting questions, to be certain. This question gets to the core reason why evolutionary biologists reject the arguments for intelligent design. For these many biologists, homologous structures only make sense from within an evolutionary framework.

The View of Biological Homologies before Darwin

Part of the response to my friend Phil’s question can be found in the theoretical work of Sir Richard Owen, a prominent biologist from the UK who predated Darwin. One of the world’s most important anatomists in his day, Owen played a key role in discovering, describing, and interpreting biological homologies. Owen understood homologies from a design perspective. Specifically, Owen saw these mutual features as manifestations of a common blueprint that existed in the Creator’s mind, and, in turn, were physically manifested in the created order.

Archetypes and God’s Creativity

Instead of seeing the concept of the archetype as restricting God’s creativity, Owen regarded the archetype as reflecting teleology of the highest order. In his presentation to the Royal Institution of Great Britain, Owen lectured: “The satisfaction felt by the rightly constituted mind must ever be great in recognizing the fitness of parts for their appropriate functions; but when this fitness is gained as in the great toe of the foot of man or the ostrich, by a structure which at the same time betokens harmonious concord with a common type, the prescient operations of the One Cause of all organization becomes strikingly manifested to our limited intelligence.”1

In other words, Owen marveled at the way the Creator generated so much functional diversity from a single template—for example, the pentadactyl architecture of the vertebrate forelimb.

In fact, the diversity of life on Earth today—even throughout life’s history—built from 30 or so body plans (corresponding to the known animal phyla) is nothing short of mind-boggling. So, apparently creating life on Earth around design templates has done little to limit the Creator. In fact, I would argue—as Owen did— it highlights God’s ingenuity.

Designed for Discovery

There are a few reasons why God would have created life’s diversity using a limited set of templates. But, perhaps the most important reason is discoverability.

The universal nature of biochemistry and the homologous and convergent biological systems allow scientists to generalize what they learn studying one organism to the entirety of the biological realm, in some instances. The universal and homologous designs in biology allow the scientific community to make use of organisms as model systems. For example: by studying DNA replication in bacteria, we have gained key insight that allows us to understand DNA replication in all life on the planet. Studying gene regulation in yeast helps us understand gene regulation in human beings. Studying the developmental pathways of the nematode C. elegans has yielded important knowledge that helps us understand growth and development in many multicellular organisms. Studying genetics in the fruit fly Drosophila has provided key understanding regarding inheritance.

If, as my friend Phil wants, the Creator used a near infinite array of biological designs when he created, it would be virtually impossible for us to know anything about the living realm. The process of discovery in biology would become cumbersome and laborious.

Because the living realm is intelligible, it is possible for human beings to take advantage of God’s provision for us, made available within the creation. As we study and develop an understanding of the living realm, we can deploy that knowledge to benefit humanity—in fact, all life on Earth—through agriculture, medicine, conservation efforts, and emerging biotechnologies.

Ultimately, I believe that God has designed the biological realm for discoverability because He wants us to see, understand, and appreciate his handiwork as a Creator, so through his creation we can know him.

“It is the glory of God to conceal a matter; to search out a matter is the glory of kings.”

–Proverbs 25:2

Resources

Endnotes

  1. Richard Owen, On the Nature of Limbs: A Discourse, ed. Ron Amundson (Chicago: University of Chicago Press, 2007), 38.
Reprinted with permission by the author
Original article at:
https://www.reasons.org/explore/blogs/the-cells-design/read/the-cells-design/2016/12/21/q-a-why-would-an-infinite-creator-employ-the-same-designs