Why do avian erythrocytes have nuclei

I personally would doubt the fairy story about mammalian red cells making room for haemoglobin. Typical post hoc justification. They just evolved differently. I'd only add enucleate red cells confer a solid evolutionary advantage for many mammals. Apex land predators, eg cheetahs, probably couldn't sprint if they had the lesser capacity of nucleated red cells.

Add a comment. Active Oldest Votes. Lizards have lower energy than mammals. Improve this answer. It's helped me a lot! According to this website Red blood cells RBC or erythrocytes are continually formed in the bone marrow. Mammals may have diverged here and developed anucleated RBC's with increased oxygen carrying capacity to adapt to the increased oxygen demands Hope this answer is good enough. It is fine to quote sources in support of an explanation, but we expect you to provide that explanation yourself.

You need at least to summarize the gist of the arguments in the sources you quote, especially when they are so ridiculously long. Pearse Pearse 1. Answers are much more likely to receive a favorable response if you include supporting references primary literature is best. Without that support, your answer is indistinguishable from opinion.

Also note that camels like other mammals have enucleated RBCs as discussed in this post ——— Please take the tour and then consult the help pages for additional advice on How to Answer effectively on this site and then edit your answer accordingly. Sign up or log in Sign up using Google.

Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Despite the name, hemerythrin does not contain a heme group and its oxygen-carrying capacity is poor compared to hemoglobin.

Figure 1. In most vertebrates, a hemoglobin delivers oxygen to the body and removes some carbon dioxide. Hemoglobin is composed of four protein subunits, two alpha chains and two beta chains, and a heme group that has iron associated with it. In most mollusks and some arthropods, b hemocyanin delivers oxygen. Unlike hemoglobin, hemolymph is not carried in blood cells, but floats free in the hemolymph. Copper instead of iron binds the oxygen, giving the hemolymph a blue-green color.

In annelids, such as the earthworm, and some other invertebrates, c hemerythrin carries oxygen. Like hemoglobin, hemerythrin is carried in blood cells and has iron associated with it, but despite its name, hemerythrin does not contain heme. The small size and large surface area of red blood cells allows for rapid diffusion of oxygen and carbon dioxide across the plasma membrane. In the lungs, carbon dioxide is released and oxygen is taken in by the blood. In the tissues, oxygen is released from the blood and carbon dioxide is bound for transport back to the lungs.

Studies have found that hemoglobin also binds nitrous oxide NO. NO is a vasodilator that relaxes the blood vessels and capillaries and may help with gas exchange and the passage of red blood cells through narrow vessels. Nitroglycerin, a heart medication for angina and heart attacks, is converted to NO to help relax the blood vessels and increase oxygen flow through the body.

A characteristic of red blood cells is their glycolipid and glycoprotein coating; these are lipids and proteins that have carbohydrate molecules attached. 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 genes and signaling pathways that drive the pinching-off process, however, were a mystery. 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.

Despite the name, hemerythrin does not contain a heme group; its oxygen-carrying capacity is poor compared to hemoglobin. The small size and large surface area of red blood cells allow for rapid diffusion of oxygen and carbon dioxide across the plasma membrane.

In the lungs, carbon dioxide is released while oxygen is taken in by the blood. In the tissues, oxygen is released from the blood while carbon dioxide is bound for transport back to the lungs.

Studies have found that hemoglobin also binds nitrous oxide NO. Nitrous oxide is a vasodilator: an agent that causes dilation of the blood vessels, thereby reducing blood pressure. It relaxes the blood vessels and capillaries which may help with gas exchange and the passage of red blood cells through narrow vessels. Nitroglycerin, a heart medication for angina and heart attacks, is converted to NO to help relax the blood vessels, increasiing oxygen flow throughout the body.

A characteristic of red blood cells is their glycolipid and glycoprotein coating; these are lipids and proteins that have carbohydrate molecules attached.