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Do Red blood cells(mammals) really have no organelles?

Do Red blood cells(mammals) really have no organelles?



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I have read that mammal mature Red blood cells lack most organelles, including mitochondria, golgi apparatus and an ER. ( https://en.wikipedia.org/wiki/Red_blood_cell#Mammalian_erythrocytes ) This makes sense since there purpose is to transport oxygen via hemoglobin, and according to the wiki, they make any energy needed via glycolysis. But are there really no more organelles in a mature red blood cells? A simple google search did not help me.


Yes. This is true. During the final stages of red blood cell formation in the bone marrow, the nucleus and several other organelles are broken down and/or expelled from the cells. In the process they decrease markedly in size, from about 24 to about 7-9 micrometer. Presumably this makes them small enough to pass through the smallest capillaries. Lacking those organelles also limits their life expectancy to approximately 120 days.


How Red Blood Cells Nuke Their Nuclei

Unlike the rest of the cells in your body, your red blood cells lack nuclei. That quirk dates back to the time when mammals began to evolve. Other vertebrates such as fish, reptiles, and birds, have red cells that contain nuclei that are inactive. Losing the nucleus enables the red blood cell to contain more oxygen-carrying hemoglobin, thus enabling more oxygen to be transported in the blood and boosting our metabolism.

Scientists have struggled to understand the mechanism by which maturing red blood cells eject their nuclei. Now, researchers in the lab of Whitehead Member Harvey Lodish have modeled the complete process in vitro in mice, reporting their findings in Nature Cell Biology. The first mechanistic study of how a red blood cell loses its nucleus, the research sheds light on one of the most essential steps in mammalian evolution.

It was known that as a mammalian red blood cell nears maturity, a ring of actin filaments contracts and pinches off a segment of the cell that contains the nucleus, a type of "cell division." The nucleus is then swallowed by macrophages (one of the immune system's quick-response troops). The genes and signaling pathways that drive the pinching-off process, however, were a mystery.

"Using a cell-culture system we were actually able to watch the cells divide, go through hemoglobin synthesis and then lose their nuclei," says Lodish, who is also a professor of biology at Massachusetts Institute of Technology. "We discovered that the proteins Rac 1, Rac 2 and mDia2 are involved in building the ring of actin filaments."

"We were very interested in that Rac 1 and Rac 2 were involved in disposing the nuclei of red blood cells," says Peng Ji, lead author and postdoctoral researcher in the Lodish lab. "These proteins are known for their role in creating actin fibers in many body cells, and a necessary component of many important cellular functions including cell division that support cell growth."

His cell-culture system began with red blood cell precursors drawn from an embryonic mouse liver (in mammalian embryos, the liver is the main producer of such cells, rather than bone marrow as in adults). The cultured cells, synchronized to develop together, divided four or five times before losing their nuclei and becoming immature red blood cells. The researchers used simple fluorescence-based assays that enabled them to probe the changes in the red blood cells through the different stages leading up to the loss of the nucleus.

The researchers plan to further investigate the entire process of red blood cell formation, which may lead to insights about genetic alterations that underlie certain red blood cell disorders.

"During normal cell division, each daughter cell receives half the DNA," comments Lodish. "In this case, when the red blood cell divides, one daughter cell gets all the DNA. What's fascinating is that in this case, that daughter cell gets eaten by macrophages. Until now, scientists were unable to study these cells because they were unable to see them."

Journal reference: Peng Ji, Senthil Raja Jayapal and Harvey Lodish. Enucleation of cultured mouse fetal erythroblasts requires Rac GTPases and mDia2. Nature Cell Biology, Volume 10, Number 3.

The research was supported by the National Institutes of Health and Amgen, Inc.

Story Source:

Materials provided by Whitehead Institute for Biomedical Research. Note: Content may be edited for style and length.


Many structures and functions in mammals are related to endothermy. Mammals can generate and conserve heat when it&rsquos cold outside. They can also lose heat when they become overheated. How do mammals control their body temperature in these ways?

How Mammals Stay Warm

Mammals generate heat mainly by keeping their metabolic rate high. The cells of mammals have many more mitochondria than the cells of other animals. The extra mitochondria generate enough energy to keep the rate of metabolism high. Mammals can also generate little bursts of heat by shivering. Shivering occurs when many muscles contract a little bit all at once. Each muscle that contracts produces a small amount of heat.

Conserving heat is also important, especially in small mammals. A small body has a relatively large surface area compared to its overall size. Because heat is lost from the surface of the body, small mammals lose a greater proportion of their body heat than large mammals. Mammals conserve body heat with their hair or fur. It traps a layer of warm air next to the skin. Most mammals can make their hair stand up from the skin, so it becomes an even better insulator. Even humans automatically contract these muscles when they are cold, causing goosebumps (see Figure below). Mammals also have a layer of fat under the skin to help insulate the body. This fatty layer is not found in other vertebrates.

Mammals raise their hair with tiny muscles in the skin. Even humans automatically contract these muscles when they are cold. They cause &ldquogoosebumps,&rdquo as shown here.

How Mammals Stay Cool

One way mammals lose excess heat is by increasing blood flow to the skin. This warms the skin so heat can be given off to the environment. That&rsquos why you may get flushed, or red in the face, when you exercise on a hot day. You are likely to sweat as well. Sweating also reduces body heat. Sweat wets the skin, and when it evaporates, it cools the body. Evaporation uses energy, and the energy comes from body heat. Animals with fur, such as dogs, use panting instead of sweating to lose body heat (see Figure below). Evaporation of water from the tongue and other moist surfaces of the mouth and throat uses heat and helps cool the body.

Panting Dog. This dog is overheated. It is losing excess body heat by panting.


The amazing flexibility of red blood cells

One of today's sharpest imaging tools, super-resolution microscopy, produces sparkling images of what until now has been the blurry interior of cells, detailing not only the cell's internal organs and skeleton, but also providing insights into cells' amazing flexibility.

In the current issue of the journal Cell Reports, Ke Xu and his colleagues at UC Berkeley use the technique to provide a sharp view of the geodesic mesh that supports the outer membrane of a red blood cell, revealing why such cells are sturdy yet flexible enough to squeeze through narrow capillaries as they carry oxygen to our tissues.

The discovery could eventually help uncover how the malaria parasite hijacks this mesh, called the sub-membrane cytoskeleton, when it invades and eventually destroys red blood cells.

"People know that the parasite interacts with the cytoskeleton, but how it does it is unclear because there has been no good way to look at the structure," said Xu, an assistant professor of chemistry. "Now that we have resolved what is really going on in a normal healthy cell, we can ask what changes under infection with parasites and how drugs affect the interaction."

Typical human cells have a two-dimensional skeleton that supports the outer membrane and a three-dimensional interior skeleton that supports all the organelles inside and serves as a transportation system throughout the cell.

Red blood cells, however, have only the membrane supports and no internal scaffolding, so they're basically a balloon filled with molecules of oxygen-carrying hemoglobin. Because of their simpler structure, red blood cells are ideal for studying the skeleton that supports the membrane in all cells.

Electron microscope images earlier showed that the sub-membrane cytoskeleton in red blood cells is a triangular mesh of proteins, reminiscent of a geodesic dome. But measurements of the size of the triangular subunits were made by flattening out the domed membrane of a dead and dried-out cell, which distorts the structure.

STORMing the cytoskeleton

Xu was a postdoctoral fellow in the Harvard University lab of one of the inventors of super-resolution microscopy, Xiaowei Zhuang, and is an expert on the version called STORM (stochastic optical reconstruction microscopy). Super-resolution microscopy gives about 10 times better resolution than standard light microscopy and works well with wet and live cells.

Using STORM, Xu, former Berkeley postdoc Leiting Pan and graduate student Rui Yan were able to image the full sub-membrane cytoskeleton of fresh red blood cells and discovered that the triangles of the mesh are about half the size of found in earlier measurements done with electron microscopy: each side is 80 nanometers long, instead of 190 nanometers.

The distinction is critical: The building blocks of the mesh are a protein called spectrin, which can be stretched to a maximum of about 190 nanometers in length. If the mesh were made of stretched spectrin, it would be rigid, Xu said. But since its normal length is a relaxed 80 nanometers, it acts like a spring. "It is more like a spring in its relaxed state, where it has much flexibility under compression or stretching, so that gives red blood cells a lot of elasticity under different physiological conditions, such as squeezing through a narrow capillary," Yan said.

At the vertices of the mesh, where five to six spectrin proteins come together, is a different protein: actin. Actin is a standard part of the sub-membrane cytoskeleton and one of the main structural components of the cell.

Tears in the mesh

Interestingly, STORM revealed never-before-seen holes in the cytoskeletal mesh that may also be critical to its flexibility.

"This is a defect in the network, but there might be a reason for it," said Xu, who is also a Chan Zuckerberg Biohub Investigator. "The cell would want to change structure rapidly as it goes through the capillaries, and having those defects is helpful in reorganizing the shape without breaking the mesh. It can act as a weak point as they try to squeeze through things, they can start to bend around those points."

Xu actually discovered the key structural role of spectrin. While still at Harvard, he used STORM to look at the skeletal structure of neurons, and discovered that actin proteins form precisely spaced rings along the entire length of the axon -- which can be as much as a foot long -- much like the ribs of a snake. They are separated by exactly 190 nanometers, and when he looked through textbooks for proteins with that length, he came across spectrin. He subsequently used STORM to confirm that in its stretched state, spectrin proteins are the spacers between the rings, keeping them precisely separated.

"The ringed skeleton makes the axon a very stable but bendable structure," Xu said, whereas the regular spacing may be key to its electrical conductivity.

Super-resolution microscopy employs a trick to overcome the diffraction limit of light microscopy, which prevents conventional light microscopes from resolving things smaller than half the size of the wavelength of the light, which for visible light is about 300 nanometers.

STORM involves attaching a blinking light source to individual molecules and then isolating each light's position independently of the others, building up a complete image much like the 1880s artists who developed pointillism, producing images from individual dots of paint.

Typically chemists attach these flashing sources to all molecules of the same type in a cell, such as all actin molecules, but since only a small percentage of the sources blink on at any one time, it's possible to pinpoint the exact location of each. Today's best resolution is about 10 nanometers, Xu said, which is about the size of a single protein or molecule.


ELI5 Do animals and humans have the same blood?

Do animals and humans have the same blood? If not .. why? What makes them different?

No, they do not have the same blood.

The specific thing that makes makes them different is our different genes. More broadly, it’s our different needs that make us different.

You will find that most creatures have the same basic elements to their blood - plasma, platelets, red blood cells, white blood cells, etc. But what those cells look like and what they can do is very different in different animals. Camels, for example, have oval-shaped red blood cells where we have disk-shaped red blood cells. This is so that camels can drink and take onboard huge amounts of water all of a sudden without their RBCs bursting. Dolphins and whales have red bloods cells shaped in a way that maximises oxygen carrying capacity, more than ours do. This allows them to hold their breath far longer than we do.

Not to mention different animals have different blood types (humans having A, B, AB and O with them the added complication of an Rh factor).

Going back to the dolphins and whales, would any endurance athletes have a more mutated blood cell that change the shape of them or are they just still disk shaped ?

Not the same, but pretty similar if you look at similar animals. Like humans, other mammals have red blood cells, white blood cells, platelets, and blood plasma, which all perform basically the same function in those animals as they do in humans: red blood cells carry oxygen, white blood cells destroy invaders and damaged cells, platelets form clots to stop bleeding, and plasma contains various dissolved proteins and nutrients needed for life. There are slight differences (e.g., in the size of red blood cells), but the basic plan is the same.

The further you go from mammals, the more different things are. Non-mammals don't have platelets, for example (although their blood still clots). Some other animals use a different chemical to carry oxygen (humans use hemoglobin but, say, squid use a related chemical called hemocyanin). Very simple animals like jellyfish don't have blood at all.


Protein found to regulate red blood cell size and number

The adult human circulatory system contains between 20 and 30 trillion red blood cells (RBCs), the precise size and number of which can vary from person to person. Some people may have fewer, but larger RBCs, while others may have a larger number of smaller RBCs. Although these differences in size and number may seem inconsequential, they raise an important question: Just what controls these characteristics of RBCs?

This question is particularly relevant for the roughly one-quarter of the population that suffers from anemia, which is often caused by flawed RBC production. A better understanding of how RBC production is controlled may offer greater insight into the development and potential treatment of anemia.

By analyzing the results of genome-wide association studies (GWAS) in conjunction with experiments on mouse and human red blood cells, researchers in the lab of Whitehead Institute Founding Member Harvey Lodish have identified the protein cyclin D3 as regulating the number of cell divisions RBC progenitors undergo, which ultimately affects the resulting size and quantity of RBCs. Their findings are reported in the September 14 issue of Genes and Development.

"This is one of the rare cases where we can explain a normal human-to-human variation," says Lodish, who is also a professor of biology and bioengineering at MIT. "In a sense, it's a window on human evolution. Why this should have happened, we have no idea, but it does."

Lodish likens cyclin D3's role in RBCs to that of a clock. In some people, the clock triggers RBC progenitors to mature after four rounds of cell division, resulting in fewer but larger RBCs. In others it goes off after five cell division cycles, which leads to production of a greater number of smaller RBCs. In both cases, the blood usually has the same ability to carry oxygen to distant tissues.

The initial hint of cyclin D3's importance came from GWAS, genetic surveys of large numbers of people with or without a particular trait. Researchers compare the groups in an attempt to identify genetic variations.

"The problem with most GWAS is that you get a bunch of potentially interesting genes, but that doesn't tell you anything about the functional biology, so you really have to figure it out," says Leif Ludwig, a Lodish graduate student and co-author of the Genes and Development paper. "You only know something has a role, but you don't know how it can cause variation. This work on cyclin D3 is a really nice example of how functional follow-up on a GWAS association can really teach us something about underlying biology."

In the case of RBC size and number, a mutation affecting cyclin D3 production bubbled to the surface from the GWAS's murky genetic data. Ludwig and co-author Vijay Sankaran then confirmed that reduced or inhibited cyclin D3 expression in mice and in human RBC progenitors caused those cells to halt cell division and mature earlier, producing larger and fewer red blood cells than mice and cells with uninhibited cyclin D3 production.

As one of only a handful of studies that have successfully used GWAS to produce definitive biological results, Sankaran is excited that this work confirms the value of such genetic studies.

"Can genetics teach us about biology?" asks Sankaran, also a postdoctoral researcher in the Lodish lab. "Yes! This work tells us that as genetic studies identify new genes, there will probably have been a lot of things biologists may have ignored. Genetics allows you to shine a spotlight on something interesting and then home in on it see what can be learned."

This work was supported by the National Institutes of Health (NIH), Boehringer Ingelheim Fonds, and Amgen, Inc.


Do Red blood cells(mammals) really have no organelles? - Biology

Today I found out the red juice in raw red meat is not blood. Nearly all blood is removed from meat during slaughter, which is also why you don’t see blood in raw “white meat” only an extremely small amount of blood remains within the muscle tissue when you get it from the store.

So what is that red liquid you are seeing in red meat? Red meats, such as beef, are composed of quite a bit of water. This water, mixed with a protein called myoglobin, ends up comprising most of that red liquid.

In fact, red meat is distinguished from white meat primarily based on the levels of myoglobin in the meat. The more myoglobin, the redder the meat. Thus most animals, such as mammals, with a high amount of myoglobin, are considered “red meat”, while animals with low levels of myoglobin, like most poultry, or no myoglobin, like some sea-life, are considered “white meat”.

Myoglobin is a protein that stores oxygen in muscle cells, very similar to its cousin, hemoglobin, that stores oxygen in red blood cells. This is necessary for muscles which need immediate oxygen for energy during frequent, continual usage. Myoglobin is highly pigmented, specifically red so the more myoglobin, the redder the meat will look and the darker it will get when you cook it.

This darkening effect of the meat when you cook it is also due to the myoglobin or more specifically, the charge of the iron atom in myoglobin. When the meat is cooked, the iron atom moves from a +2 oxidation state to a +3 oxidation state, having lost an electron. The technical details aren’t important here, though if you want them, read the “bonus factoids” section, but the bottom line is that this ends up causing the meat to turn from pinkish-red to brown.

Pro-tip: when searching for non-copyrighted pictures for an article, don’t search for “white meat” or really any variation of that on Google Image Search.

If you liked this article and the Bonus Facts below, you might also enjoy:

  • It is possible for meat to remain pinkish-red all through the cooking if it has been exposed to nitrites. It is even possible for packagers, through artificial means, to keep the meat looking pink, even after it has spoiled, by binding a molecule of carbon monoxide to produce metmyoglobin. Consumers associate pink meat with “fresh”, so this increases sales, even though the pink color has little to do with the freshness of meat.
  • Pigs are often considered “white meat”, even though their muscles contain a lot more myoglobin than most other white meat animals. This however, is a much lower concentrate of myoglobin than other “red meat”, such as cows, due to the fact that pigs are lazy and mostly just lay around all day. So depending on who you talk to, pigs can be considered white meat or red meat they more or less sit in between the two classifications.
  • Chickens and Turkeys are generally considered white meat, however due to the fact that both use their legs extensively, their leg muscles contain a significant amount of myoglobin which causes their meat to turn dark when cooked so in some sense they contain both red and white meat. Wild poultry, which tend to fly a lot more, tend to only contain “dark” meat, which contains a higher amount of myoglobin due to the muscles needing more oxygen from frequent, continual usage.
  • White meat is made up of “fast fibers” that are used for quick bursts of activity. These muscles get energy from glyocogen which, like myoglobin, is stored in the muscles.
  • Fish are primarily white meat due to the fact that they don’t ever need their muscles to support themselves and thus need much less myoglobin or sometimes none at all in a few cases they float, so their muscle usage is much less than say a 1000 pound cow who walks around a lot and must deal with gravity. Typically, the only red meat you’ll find on a fish is around their fins and tail, which are used almost constantly.
  • Some fish, such as sharks and tuna, have red meat because they are fast swimmers and are migratory and thus almost always moving they use their muscles extensively and so they contain a lot more myoglobin than most other sea-life.
  • For contrast, the white meat from chickens is made up of about .05% myoglobin with their thighs having about .2% myoglobin pork and veal contain about .2% myoglobin non-veal beef contains about 1%-2% of myoglobin, depending on age and muscle use.
  • The USDA considers all meats obtained from livestock to be “red” because they contain more myoglobin than chicken or fish.
  • Beef meat that is vacuum sealed, thus not exposed to oxygen, tends to be more of a purple shade. Once the meat is exposed to oxygen, it will gradually turn red over a span of 10-20 minutes as the myoglobin absorbs the oxygen.
  • Beef stored in the refrigerator for more than 5 days will start to turn brown due to chemical changes in the myoglobin. This doesn’t necessarily mean it has gone bad, though with this length of unfrozen storage, it may have. Best to use your nose to tell for sure, not your eyes.
  • Before you cook the red meat, the iron atom’s oxidation level is +2 and is bound to a dioxygen molecule (O2) with a red color as you cook it, this iron loses an electron and goes to a +3 oxidation level, and now coordinates with a water molecule (H2O). This process ends up turning the meat brown.

43 comments

So, next time I’m barbecuing and my friend says, “The bloodier the better!” I’m going to correct him and say, “No. The more myoglobin, the better!”

On second thought, I may get punched!

Nitrite soaking of meat is one of the oldest myoglobin fixes. The procedure was discussed at length in several German chemistry journals as early as the 19th century. The structure of MbNO2 was one of the first bioinorganic structures solved and continues to this day to be a system of great interest. Nitrites and nitrosyls are important biological signaling molecules. While nitrite soaking of meat may improve their sale value, high concentrations of nitrites should be avoided. Foods like packaged pepperoni (while delicious) do contain very high amounts of nitrite. When proteins are exposed to heat, thermal degradation occurs and the free nitrite groups will attach, forming nitrosamines. Nitrosamines have been implicated in pancreatic cancer (among other types). Strangely, nitrite should theoretically kill any organism whose respiration is dependent on Mb/Hb systems, since nitrite is favorable to oxygen. This means that nitrite displaces oxygen from myoglobin and hemoglobin at a very fast rate. The reversal of this process, believed to be mediated by cd1 nitrite reductase is the subject of a great deal of study in biochemistry (on experimental, analytical and theoretical fronts).

Yi, J. Heinecke, H. Tan, H. Ford, P. Richter-Addo, G. The Distal Pocket Histidine Residue in Horse Heart Myoglobin Directs the O-Binding Mode of Nitrite to the Heme Iron. J. Am. Chem. Soc. 2009, 131, 18119-18128.
Visser, S. Density functional theory (DFT) and combined quantum mechanical/molecular mechanics (QM/MM) studies on the oxygen activation step in nitric oxide synthase enzymes. Biochem. Soc. Trans. 2009, 37, 373-377.
Chen, H. Hirao, H. Derat, E. Schlichting, I. Shaik, S. Quantum Mechanical/Molecular Mechanical Study on the Mechanisms of Compound I Formation in the Catalytic Cycle of Chloroperoxidase: An Overview on Heme Enzymes. J. Phys. Chem. B 2008, 112, 9490-9500.
Cho, K. Hirao, H. Chen, H. Carvajal, M. Cohen, S. Derat, E. Thiel, W. Shaik, S. Compound I in Heme Thiolate Enzymes: A Comparative QM/MM Study. J. Phys. Chem. A 2008, 112, 13128-13138.
Marti, M. Crespo, A. Bari, S. Doctorovich, F. Estrin, D. QM-MM Study of Nitrite Reduction by Nitrite Reductase of Pseudomonas aeruginosa. J. Phys. Chem. B 2004, 108, 18073-18080.
Copeland, D. Soares, A. West, A. Richter-Addo, G. Crystal structures of the nitrite and nitric oxide complexes of horse heart myoglobin. J. Inorg. Biochem. 2006, 100, 1413-1425.
Cho, K. Derat, E. Shaik, S. Compound I of Nitric Oxide Synthase: The Active Site Protonation State. J. Am. Chem. Soc. 2007, 129, 3182-3188.
Sundararajan, M. Hillier, I. Burton, N. Mechanism of Nitrite Reduction at T2Cu Centers: Electronic Structure Calculations of Catalysis by Copper Nitrite Reductase and by Synthetic Model Compounds. J. Phys. Chem. B 2007, 111, 5511-5517.
Crespos, A. Marti, M. Kalko, S. Morreale, A. Orozco, M. Gelpi, J. Luque, J. Estrin, D. Theoretical Study of the Truncated Hemoglobin HbN: Exploring the Molecular Basis of the NO Detoxification Mechanism. J. Am. Chem. Soc. 2005, 127, 4433-4444.
Gladwin, M. Grubina, R. Doyle, M. The New Chemical Biology of Nitrite Reactions with Hemoglobin: R-State Catalysis, Oxidative Denitrosylation, and Nitrite Reductase/Anhydrase. Accts. Chem. Research. 2009, 42, 157-167.
Drago, R. Physical Methods For Chemists, 2nd ed. Saunders College Publishing: Gainesville, 1977.
Voet, D. Voet, J. Pratt, C. Fundamentals of Biochemistry: Life at the Molecular Level, 2nd ed. Fitzgerald, P., Ed. Wiley: New York, 2007 p 295, 759.
Price, C. Geometry of Molecules, 1st ed. McGraw-Hill: Boston, 1971.
Dyall, K. Faegri, K. Relativistic Quantum Chemistry, 1st ed. Oxford University Press: New York, 2007.
Levine, I. Quantum Chemistry, 5th ed. Prentice Hall: New Jersey, 2000.
Rhodes, G. Crystallography Made Crystal Clear, 2nd ed. Academic Press: San Diego, 2000.
Skoog, D. Holler, F. Crouch, S. Principles of Instrumental Analysis, 6th ed. Thomson: Belmont, 2007.
Biochemistry and Nutrition, Nuclear and Particle Physics. David R. Lide CRC Handbook of Chemistry and Physics, 71st ed. CRC Presss, 1991.


Do Red blood cells(mammals) really have no organelles? - Biology

Most mammalian red blood cells are highly evolved and have lost their nucleus. The nucleated red blood cells illustrated in the phase contrast optical micrograph below were derived from a frog, but are common to all amphibians.

Circulatory systems have evolved to form the most efficient oxygen transport mechanism that is possible for the organism. Oxygen is carried by hemoglobin molecules that reside within red blood cells in all advanced species. In order to maximize the distribution of blood throughout the vessels, hearts have increasingly evolved to accommodate more complex creatures. Fish hearts are relatively primitive and have only two chambers, whereas amphibian hearts are somewhat more advanced with three. The most sophisticated four-chamber hearts are found in reptiles, birds, and mammals.

Having three chambers, the amphibian heart is rather unusual in that it has two atria and only a single ventricle. This complicates matters because blood accumulates oxygen in the lungs and is then returned to the heart before being pumped into the rest of the circulatory system. A problem arises because blood returning to the heart from the lungs is mixed with incoming blood from the body, causing a mixing between oxygenated and deoxygenated blood. Amphibians deal with this situation by having a very slow metabolism, and also by absorbing some oxygen through their skin. In addition there is some directionality in controlling the distribution of blood flow by the ventricle.

The presence of a nucleus in the amphibian red blood cells allows researchers easy access to large quantities of amphibian DNA. This is also true for birds. Blood can be collected from these creatures and the red blood cells isolated by centrifugation. After removal of the residual plasma, purified cells can then be treated with specific enzymes and detergents to digest the cellular envelope and release DNA from its protein complex.


Evolutionist questions CMI report&mdash Have red blood cells really been found in T. rex fossils?

This unique full-color family magazine gives God the glory, refutes evolution, and gives you the answers to defend your faith. Exciting articles and great witnessing material you won&rsquot find anywhere else! Includes a beautifully illustrated full-color children&rsquos section in every issue. Powerful ammunition to intelligently discuss nature, history, science, the Bible, and related subjects. Delivered to your home every three months!

In a recent exchange with a CMI supporter, an evolutionist attacked the credibility of our article Sensational dinosaur blood report, first published in Creation magazine in 1997. 1 In an effort to discredit the story, evolutionist Jack DeBaun actually contacted the scientist who first reported &lsquored blood cells&rsquo in T. rex fossils. They raise some serious questions that require a detailed answer.

Dr Carl Wieland, Managing Director of CMI-Australia and author of the article in question, answers each charge in turn. And yes, it&rsquos still safe to say that the evidence is highly consistent with red blood cells having been found in T. rex fossils. (DeBaun&rsquos original remarks appear below, indented and in red.)

JB: One of the [Creation Ministries International] articles to which you referred your readers was entitled, &lsquoSensational dinosaur blood report&rsquo. According to this article, Dr Mary Schweitzer working in Dr John Horner&rsquos research group at Montana State University uncovered &lsquoactual red blood cells in fossil bones from T. rex. With traces of the blood protein hemoglobin&rsquo. This evidence led the authors to conclude that the discovery &lsquocasts immense doubt upon the &ldquomillions of years&rdquo idea&rsquo.

Having developed a healthy skepticism towards the &lsquosensational&rsquo discoveries that are periodically trumpeted by the [CMI] apologists, I contacted Dr Horner directly to ask him about these claims. He informed me that actual red blood cells had most certainly not been detected in his specimens. He wrote, &lsquoWhat we found was heme, a form of iron that has a biological origin, but of course, not any soft tissue or any other component of a cell. It&rsquos preserved because it&rsquos iron.&rsquo

CW: This seems rather disingenuous, since they saw what appeared to be red blood cells under the microscope. Obviously, this was stunning, and it was Dr Horner who, as we cited, suggested to Mary Schweitzer that she try to disprove that they were red blood cells that were being seen by these people under the microscope. The immunological reaction was the factor that, coupled with the histological appearance, made it more than reasonable to claim that these were actual red blood cells (i.e. their remains). As you will see from the rest of this, they have most definitely not succeeded in disproving that these are red cells.

CW: When you read this, remember that to these people, the truth is that the millions of years are fact. Therefore&mdashand this is not said in any disparaging way&mdashthey must have some sort of explanation. Let me put it this way, before looking at the explanation in more detail&mdashwhen DNA was first reported in a fossil millions of years old, a well-known scientist in Nature said that it was just as well that those looking for it were not aware of laboratory-measured rates of decay which indicated that DNA should not last more than about 10,000 years (he later said 100,000)&mdashor else they would not have looked for it. His implication: by definition, once you find the DNA, the previous belief, i.e. that it would not last, is proved wrong. Thus, if one finds heme, hemoglobin, and/or red blood cells in a millions-of-years-old bone (as they see it), this proves that under certain, remarkable, rare conditions, such things can happen. Note&mdashI would not claim that the preservation proves the millions of years is wrong, but it strongly suggests it, and it is certainly more consistent with the belief that the fossil is only thousands of years old.

Now, let&rsquos look at what has been said here. Hemoglobin is what was being looked for, and hemoglobin consists of heme (the small molecule we are looking for) and globin (protein which consists of long chains of amino acids strung together in a specific sequence). Heme certainly is tougher than the globin, but to suggest that therefore it is no problem to explain how it lasted millions of years is again disingenuous, as it was certainly a surprise to the researchers, when you read the paper, and no wonder. But note that the immune response is specific to the sequence of amino acids, which forms the protein, not to the heme. To suggest that 3&ndash4 amino acids may have given a response specific to that protein is mindblowing. There would have to be far more specificity (i.e. a specific sequence) than that. I asked a Ph.D. molecular biologist who works with us and who did work for his thesis on identifying proteins using monoclonal antibodies. He is most sceptical about the notion that 3&ndash4 amino acids, even with the heme, will be recognised by the antibody.

Remember that the evolutionists cited may be experts in their field, but their field is not immunology or molecular biology. Above all, remember that this is their way to &lsquoexplain away&rsquo the evidence. There is no evidence that this reaction was spiked by only &lsquo3&ndash4&rsquo amino acids, they are surmising this, but there is evidence that there was a reaction to hemoglobin, not &lsquoheme&rsquo as such. Their chain of reasoning probably goes something like this: &lsquoWell, we have to explain the specificity of the immune response. What is the smallest no. of amino acids that could give that response?&rsquo (As indicated, I believe their assumption is way out, that it almost certainly would have to be many more, as antibodies lock onto shapes rather than short amino acid sequences. Thus, the onus of proof is on them to show you evidence that 3&ndash4 could do it. Then (continuing my suggestion on their chain of thought), &lsquohow could even that number have survived in that sequence? Well, we&rsquoll have to assume that they were glued into position by being stuck to heme, and heme is more durable as a molecule.&rsquo (It is still a surprise to find any organic structure in any millions of years old fossil by normal chemical laws.) And so on.

NB: they argue that &lsquowell, we do sometimes find heme in millions of years old fossils&rsquo but once again this begs the question of how they know that the fossils are millions of years old, and would they have predicted this finding from chemical knowledge? The answer to the second is most certainly no, but as indicated, once they find it, then by definition it is possible to get heme in bones millions of years old. But note that osteocalcin has also been found, a protein which is much more fragile than heme, and note how below they squirm around the issue:

CW: Analyze the above very carefully in light of what has already been said, and you will see that there is no reason for a scrap of retreat from my statements above that a) the evidence is consistent with morphologically intact red blood cells having been discovered, as strongly suggested by the histological appearance, and as reinforced by the hemoglobin immune response. b) The evidence is overwhelmingly more consistent with the belief that the fossils are not millions of years old than with the converse.

CW: Note how an assumption to prop up a belief has suddenly become fact.

CW: No, this is not &lsquoindicated&rsquo by the results at all, as pointed out above&mdashit is post hoc story telling to avoid the clear implications of the results.

CW: This was not just &lsquosomewhat unexpected&rsquo! See:

CW: Au contraire, it should surely qualify as &lsquowishful thinking&rsquo to try to believe that red blood cells and at least part of some hemoglobin molecules could last 65 million years. This would be a tall order, even if they were kept frozen in liquid nitrogen in a lab. Such is the stifling effect of the evolutionary dogma that scientists can be blinded to the clear implications of their own data.

JB: The other [CMI] article to which you refer your readers is entitled, &lsquoInterview with Buddy Davis&rsquo. Mr Davis, who appears to have no formal training as a paleontologist, claims that &lsquoThe Liscomb Bone Bed has probably thousands of frozen unfossilized dinosaur bones&mdashsome of them have the ligaments still attached.&rsquo Mr Davis says that he collected some of these specimens and that this discovery &lsquoplaces dinosaurs well within the time of man.&rsquo Does it really? I don&rsquot know of any reputable paleontologist who would think so.

First, one might ask if Mr Davis is actually messing with dinosaur bones. There is the possibility that what he is dealing with are mastodon and/or mammoth bones which would be expected to be rather widely distributed in the upper strata in that area. Has any qualified paleontologist with expertise in dinosaur classification been allowed to examine Davis&rsquo specimens? If not, how can he be certain that they are dinosaur bones?

CW: This is, respectfully, ridiculous. The literature [see Davies, below] has long ago recognized that these are hadrosaur bones. But this will likely be seen as one more example of &lsquowell, we didn&rsquot know before and we did not expect it on the basis of the age of these things, but it appears that under certain conditions &hellip &rsquo.

CW: Since when has &lsquobeing a mineral&rsquo made something stable? It depends what sort of mineral. Many minerals are very unstable (iron sulfite for example).

CW: That is a fair enough comment. Just about all bones, including fossil bones even a few hundred years old, will have some degree of infiltration by surrounding minerals. So we should be careful and assess the bones more fully in due course. Buddy is a singer and sculptor and adventurer, and not a scientist. One problem for us is that the bones collected officially belong to the US government under special permits, and [CMI] does not have official access to them as yet.

Nevertheless, the existence of ligaments etc. has been reported on &lsquodinosaur age&rsquo marine fossils coming out of a mud spring in England on a regular basis, and is a well accepted fact. It was written about by a Ph.D. geologist in our Creation magazine some time ago [Dr Andrew Snelling, &lsquo165 million year&rsquo surprise, Creation 19(2):14&ndash17, March&ndashMay 1997].

CW: These bones are from the same bone bed as studied by the evolutionist Davies:

Davies, Duck-bill dinosaurs (Hadrosauridae, Ornithischia) from the North Slope of Alaska. Journal of Paleontology 61(1):198&ndash200, 1987. He says on page 198:

CW: Naturally, I categorically reject this unfortunate ad hominem attack. No falsehood on the part of CMI has been demonstrated.

CW: There are a number of anomalous finds, such as the Tampa figurine, and the &lsquoMalachite Man&rsquo remains in dinosaur rock in Utah. But of course evolutionists can easily resort to secondary explanations such as &lsquointrusive burial&rsquo. The bones are such that one cannot determine either way whether they were primary or secondary in the strata. So we are careful about the use of such evidence.

CW: Deeper is a relative term. Sometimes dinosaur rock is indeed found at the surface, as this person would (or should) know.

CW: Perhaps that&rsquos because rocks that have dinosaurs in them are by definition at least 65 million years old, so how would anyone find any that are younger? Take for example the statement by Dr Schweitzer:

Note also (again) Dr Schweitzer&rsquos extreme surprise at the blood cells, contrary to the attempts to downplay the surprise at finding such in bones supposedly millions of years old.

CW: The whole question of Flood&ndashpost-Flood animal distribution, which is highly relevant to the issue of which animals are buried with which, is the subject of discussion in our technical literature. It is true that many animals contemporaneous with man have not been found with dino bones, but then many which are contemporaneous with man HAVE been found with dino bones, or at least in the same layer. Crocodiles, turtles, sharks, and more. The &lsquoorder of first appearance&rsquo of creatures in the fossil record is, some 90% of the time, not that which one would expect if evolution were true, so both sides have some things in the fossil record which require explanation.

CW: For one thing, an argument from silence is a poor one. The Bible was written for a specific purpose, inspired by God. It leaves out a whole host of extraneous issues not relevant to its purpose. But in any case, presumably by the time of Job, there were only a very few such creatures left. They may never have established themselves again in large numbers following the Flood.

CW: That is an interpretation based on the finding of dino fossils in that region, but since they were buried there in the Flood, there is no reason to believe that they hunted in today&rsquos Middle East. Furthermore, there is much evidence that T. rex, e.g. would have been easy prey for man, frightened of falling lest he kill himself, unable to run fast (despite Jurassic Park) etc. This has been documented by evolutionists of recent days. Our June Creation magazine will have an item on this [T. rex: The bigger they are, the slower they go, Creation 24(3):56, June&ndashAugust 2002].

CW: There are extra-Biblical records of &lsquodragons&rsquo that match what we would today call dinosaurs. See Q&A: Dinosaurs.

JB: Until creationists proffer reasonable answers to these questions, their man/dinosaur connection can justifiably be shrugged off as just another one of the faith-based myths that they must buy into in order to cling to their literal interpretation of the Bible.

Sincerely,

Jack DeBaun

Obviously, the reader must decide who is clinging to what, and whether or not these were &lsquoreasonable answers&rsquo (1 Peter 3:15).

CW: Sincerely,
Carl Wieland (editor, Creation magazine)


Biochemical Basis of Medicine

Biochemical Basis of Medicine discusses academic biochemistry and the applications of biochemistry in medicine. This book deals with the biochemistry of the subcellular organelles, the biochemistry of the body , and of the specialized metabolism occurring in many body tissues. This text also discusses the various applications of biochemistry as regards environmental hazards, as well as in the diagnosis of illnesses and their treatment. This text explains the structure of the mammalian cell, the cell's metabolism, the nutritional requirements of the whole body, and the body's metabolism. This book explains the specialized metabolisms involved in tissues such as those occurring in blood clotting, in the liver during carbohydrate metabolism, or in the kidneys during water absorption. The text explains toxicology or biochemical damage caused by excess presence of copper, mercury, or lead in the body. Chelation therapy can remove these toxic metals. This book describes the effects of alcohol on plasma liquids, the multistage concept of carcinogenesis, and the biochemical basis of diagnosis. Diagnosis and treatment include the determination of typical enzymes found in the plasma, tests for genetic defects in blood proteins, and the use of chemotherapeutic drugs. This book is suitable for chemists, students and professors in organic chemistry, and laboratory technicians whose work is related to pharmacology.

Biochemical Basis of Medicine discusses academic biochemistry and the applications of biochemistry in medicine. This book deals with the biochemistry of the subcellular organelles, the biochemistry of the body , and of the specialized metabolism occurring in many body tissues. This text also discusses the various applications of biochemistry as regards environmental hazards, as well as in the diagnosis of illnesses and their treatment. This text explains the structure of the mammalian cell, the cell's metabolism, the nutritional requirements of the whole body, and the body's metabolism. This book explains the specialized metabolisms involved in tissues such as those occurring in blood clotting, in the liver during carbohydrate metabolism, or in the kidneys during water absorption. The text explains toxicology or biochemical damage caused by excess presence of copper, mercury, or lead in the body. Chelation therapy can remove these toxic metals. This book describes the effects of alcohol on plasma liquids, the multistage concept of carcinogenesis, and the biochemical basis of diagnosis. Diagnosis and treatment include the determination of typical enzymes found in the plasma, tests for genetic defects in blood proteins, and the use of chemotherapeutic drugs. This book is suitable for chemists, students and professors in organic chemistry, and laboratory technicians whose work is related to pharmacology.


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