In autumn and winter, our Weibo received questions like this - "Why do the grapefruit/orange/orange I bought have two colors?" Is it genetically modified? Is it toxic? ”
Looking at being able to eat, I dare not take a bite rashly
This question is not clear in three or two sentences, it is a complex and mysterious problem, and even, it is a metaphysical problem...
01
Two sets of teams, one brand
First of all, is this bicolor fruit artificial? No.
Although artificial can be achieved, this kind of rare and natural work bought in the market is really a masterpiece of nature. Well, it can't be called a masterpiece, it's a bug of nature.
This phenomenon is called "chimera". In short, there are many cells with different genetic information in a living individual, but they are not fighting and are safe, which is called chimera. These two different types of cells can come from a variety of sources, both natural and unnatural.
This is not a splash of paint, but a chimera of different colors of leaves
Image source network
It doesn't matter if you don't understand, it's a bit complicated. For example, our organ transplantation is to make cells from two people chimeric in a person's body, of course, the genetic material in these two cells is different, and the body knows that they are not the same, which will produce rejection and prevent them from successfully chimering.
But how can naturally grown grapefruit have two sets of genetic information? It is not easy to put it in other fruits, but it is much more likely to be placed in the citrus family, the rutacea.
Rutace, that's all right
Old fans should know that the Rutaceae family is a family with a lot of natural hybrids, and the private life between species is more chaotic, and different varieties and even different species of pollen and pistils look at each other and accept each other without paying attention. Even in normal growth of the Rutaceae family, the probability of mutation in one branch is higher than in other families.
No one knows this famous picture, right?
Plants do not "reject" chimeras seriously as animals and can often be safe. If a branch is genetically mutated and does not die, the grapefruit tree has two sets of genetic information at the same time, both of which may be expressed in the fruit.
Or maybe the grapefruit tree is grafted from two different varieties or species. Originally, grafting was like sharing a house, each under the eaves. But some live and have feelings and go together. New shoots and branches are produced by chance near the grafting site, and there are two kinds of genetic information, both of which are expressed, which is a grafted chimera.
The production of this two-colored grapefruit is mostly the first possibility.
Chimerism is a specialty of citrus families
Image source network
We often see that plants have a leaf with multiple colors, or a branch with different colors, a flower half red and half white, and so on, which is usually the result of chimera. Some chimeric does not suddenly occur in this tree, but comes out of its old ancestors, and after horticulturists find and select, these chimeric characteristics are retained through asexual reproduction (most of the chimerism cannot be inherited through sexual reproduction), and have become famous in the garden.
A random expression of the two colors of "jumping plum" full of chimerism
Photography: Old Letter
02
You and your brother can't tell you clearly
Well, having said so much about chimera, I'll give you a thinking question. We all know that horses and donkeys can give birth to mules by mating, so is the mule a chimera?
So the question is, is this a donkey or a mule?
The answer is no. There are two or more sets of genetic information in the chimera at the same time, and the information of horses and donkeys does not coexist, but merges into one, generating a new set - the genetic information of mules. This is hybridization, not chimerism.
Chimerism in animals is much more difficult to occur than plants, and the more "higher" the animal, the more difficult it is. The proportion of chimerism in arthropods is relatively high, such as male and female chimeric insects, half-black and half-red lobsters, and so on. Why arthropods are prone to chimerism is currently unknown, but it can only be said that they have a higher chance of mutation or error in the reproductive process.
Male and female chimeric lobsters
Image source network
Some people say, no, I've seen chimeric cats, and mammals can also chimer. That's right, not to mention cats, people can also chimeric under natural conditions!
In the past ten or twenty years, there has been more than one such news in the world - a mother and her child do a paternity test, and it turns out that it is not a parent. Mind you, it's Mom, not Dad. It makes sense that the father is not a relative, but when the baby is pregnant in October, the child is the meat that fell from the mother's body, how can it not be a kiss?
Is it a mistake? Not really.
In the end, the scientist's answer was that this is a very rare chimeric phenomenon. When this mother was a fetus, she actually had twin siblings, but she was stillborn so early that she stopped growing so much that no one knew of his existence. The surviving individual will absorb some of the cells of the dead individual for his own use, so in some parts of the body is his own set of genes, and the other part (usually hair, skin, reproductive system and other special places) is his brother and sister's set.
Heteropupil is a manifestation of a chimeric individual
Image source:
Yes, a certain comedian said: "It's you who dies, you're your brother!" ”
The truth is, you're not dead, your brother is too! Coincidentally, this mother's egg cells and her own regular somatic cells are not a set, then the child is naturally "not pro", in theory may have to be called a nephew...
The chimera of the cat is also produced in the embryonic stage, but compared to humans, their chimerism is often written on the face, which can be seen at a glance.
Cat: Not good, chimeric a little obvious
Image source network
03
Pandora's box
Whether it is a lobster or a cat, or a person, it is a homogeneous chimera, cat and cat chimera, and a human chimera. Are there animal chimeras between different species?
Yes, such as him - a chimera of man and lotus.
Nezha: Thank you for the invitation, I'm still a lotus
And him - a chimera of man and spider.
Spider-Man: Thanks for the invitation, I never expected to appear in this kind of article
Don't think I'm kidding. Although Nezha and Spider-Man are fictional "mythical characters", the process of human cognition of chimeras has really not left God and strange.
Chimera (Chinese is sometimes transliterated as "chimera") in English, which is originally a mythical beast in Greek mythology, with a lion's head, a sheep's body, and a snake's tail. When scientists wanted to find a word for chimera, they thought of the legendary "xenochimera", and naming it after it is really accurate and cultural.
chimera
Image source: wiki
In fact, xenochimeric animals do not exist in nature. Allogeneic organ transplantation is still so risky, and xenomorphs are even more unlikely to occur and cannot survive.
However, xenochimeras under artificial conditions have long existed. In the seventies of the last century, scientists began experiments with xenochimerism, and finally successfully "synthesized" the xenochimera of viable mice and Karl Karinii mice. Over the next thirty years, chimeras of goats and sheep and between different cattle were also "synthesized".
A chimera of Goat and Sheep, called geep in English, can be turned into a sheep? Image source: wiki
A year ago, Maryland, USA, performed the first pig heart transplant operation in history. The patient has a serious heart problem, which has been incurable, and he has made an exploration of science by simply killing a horse as a living horse doctor. The patient died two months after the operation, which means that the pig heart worked well in his body for two months. This is the first surviving human xenochimera.
Mr. Nebet and his doctor who received a pig heart transplant
Image source: BBC
Hearing this, maybe you are already covered in sweat and handstand. Yes, while these experiments are scientifically great, they also face huge safety implications and ethical issues.
With the development of stem cell technology, in fact, humans have succeeded in creating chimeric embryos of humans and other animals in the laboratory, such as human rabbits, human pigs and even human monkeys, which of course are eventually "destroyed". These studies will bring a lot of progress to embryology and medicine, and may even be a way out for human organ transplantation and optimization of genetic diseases in the future. But at present, the scientific community's attitude towards these studies is still very cautious and conservative.
After all, animal xenochima is like a Pandora's box, and the risk is unknown when opened. Even if the risk is controllable, the bottom line of morality and ethics is the "shackles" that science has to face. Maybe in a few tens of hundreds of years, humans can technically make Nezha or Spider-Man, but how many of us want to live in the world of gods or superheroes? Even if people want to, what about our animal friends?
Tang Monk: You guys reflect on your identity
What is it like to have a pair of natural "Mandarin Duck Eyes"?
👇
Written by | Letters float and sink
WeChat Editor | Ah what cool