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8-cell human embryo

Researchers in pursuit of creation of human-monkey embryos in laboratory

In a controversial move, scientists have created embryos that are partially human and partially monkey. According to Spanish daily El País, Juan Carlos Izpisúa Belmonte, a Spanish biologist operates a lab at Salk Institute, California, has been collaborating with researchers in China to conduct this controversial research. Their main goal is to produce “human-animal chimeras”, where human cells are added to the monkey embryos. Just a few days back, the Japanese government also approved experiments to be conducted on human-animal embryos.

The main motive behind this research is to create animals which possess organs such as liver or kidney that are composed of human cells. As a result, these animals could be used for sources for organ transplantation. The technique for creating chimeras is that human embryonic stem cells are injected into the embryos of another species which are a day-old. Researchers hope that with this addition the growth of human cells would take place with the embryo.

Previously, Izpisúa Belmonte tried to create human-animal chimeras with the addition of human cells to the pig embryos however, in that case, human cells did not take an effective hold. However as monkeys are closer to humans genetically, chances are more for the experiment to succeed. Researchers are using gene-editing technology so that the formation of certain kinds of cells can be disabled in the animal embryos and as a result, the human cells have a better chance of taking hold.

However, this is highly controversial in the United States. According to the National Institutes of Health, federal funds can never be used for the creation of mixed monkey-human embryos. Although China does not have such a rule which facilitates the research in that country.

Till now, a part-human and part-monkey has not taken birth. Estrella Núñez, an administrator and biologist at the Catholic University of Murcia, Spain told that the mixed embryos are only allowed to develop for a week or two in the laboratory, where they can be studied. Catholic University of Murcia is helping to fund this research. There have been no comments from the Salk Institute about this and Núñez has refused to comment till the final results are published.

Pablo Ross, a veterinary researcher at University of California, Davis, worked previously with Salk on pig-human chimeras. He said that it does not make any sense to try to grow human organs in the monkeys. As they are quite small, it takes a long time for their development. He thinks that the injection of human cells into the monkey embryos could resolve questions of evolutionary distance and interspecies barriers.

human embryo

Japanese Government approves experiments to be conducted for human-animal embryos

Japan has approved the first human-animal embryo that could lead to new sources of organ transplant. Though there are still technical and ethical hurdles. Government of Japan is supporting a stem cell scientist Hiromitsu Nakauchi who leads teams at the University of Tokyo and Stanford University in California for creating animal embryos that contain human cells and transplant them into surrogate creatures as the restriction to practice was overturned this year.

Human cells are planned to be grown in mouse and rat embryos and then it could be transplanted into surrogate animals. Nakauchi said that he wants to produce animals with organs made from human cells which can be eventually transplanted into individuals. He also said that he is planning to grow a hybrid mouse for 14.5 days when the organs are mostly formed, almost to be termed and 15.5 days for the same experiment on rats. He is awaiting government approval for up to 70 days, for growing hybrid embryos in pigs. The study has been published in Nature journal.

Bioethicists are concerned that the human cells might stray beyond the development of the specific organ and travel to the animal’s brain and affect the cognition. He also added that these concerns were taken into consideration during experiments and that he made sure that cells go only to the pancreas and not the entire body.

Scientists are investigating a strategy to make an animal embryo that lacks a gene vital for the generation of a specific organ, like the pancreas and then infuse human induced pluripotent stem (iPS) into the animal fetus. iPS cells have been programmed to an embryonic-like state which can offer ascent to all cell types. As the animal starts to develop, it will make use of the human iPS cells to make an organ which it cannot make on its own.

At the American Association for the Advancement of Science meeting in Austin, Texas in 2018 scientists reported they had put human iPS cells into the sheep embryos and had been engineered not to produce a pancreas but even after growth for 28 days, it contained very less human cells and nothing resembling organs. Nakauchi thinks that is due to the genetic distance between humans and sheep.

Jun Wu who is a researcher at the University of Texas Southwestern Medical Center in Dallas said that it is not useful to bring human-animal hybrid embryos in evolutionarily distant species like pigs and sheep as human cells will be eliminated by the host early on. There is a need to understand the molecular basics and then develop strategies to overcome problems. The approval in Japan will be helpful in experimenting with iPS cells at different stages to find out the limit of growth of human cells in animal embryos.

 

Pterodactyl fossil reconstitution

Researchers discover ancient creature to be able to fly right after birth

A recent breakthrough has found that pterodactyl which is an extinct flying reptile which is also known as pterosaurs has been found to have a remarkable ability that it can fly from birth. No other vertebrate living as of today or the ones who have lived in history has this kind of ability. There is no replicate for this creature till now and this revelation has had a profound impact on our understanding as to how pterodactyls have lived and in our understanding of the dinosaur world as a whole.

Pterodactyls were initially thought to able to take flight only when grown up to full size and assumptions were made based on fossilized embryos which were found in China. Dr David Unwin, a University of Leicester palaeobiologist and Dr Charles Deeming, a University of Lincoln zoologist who are specialized in study of pterodactyls and avian and reptilian reproduction were able to disprove this theory. There was a data comparison between the prenatal growth observed in birds and crocodiles in the early stage of development before hatching. Embryos found in China and Argentina had died just before they were hatched and provided the evidence that pterodactyls had the ability to fly from birth. The study has been published in Proceedings of the Royal Society B

The basic fundamental difference between the baby pterodactyls and baby birds and bats is that they are not given any parental care and had to look after themselves from birth and search for their feed. The ability to fly provided them with a life-saving mechanism with which they could protect themselves from the carnivores dinosaurs. This ability also proved to be one of their biggest killers, as the demanding and dangerous process of flight led to many of them dying at a very early age.

The research provides answers to some key questions surrounding these animals. Flaplings (baby pterodactyls) were known to fly and grow from birth and provides a possible explanation as to why they were able to achieve enormous wingspans which were larger than any historic or known species of bird or bat. Their wing finger is also known as manus digit IV had an early elongation and development, making them flight capable quite early in postnatal development. 

Further study is required to understand as to how they are able to carry out this process and with more developments raises more questions that were not posed earlier due to our limited understanding of the species. Complete and comparative anatomy can reveal novel developmental modes in the species of pterosaurs and how they can strikingly differ from birds and bats.