Fourth Transplant Patient Dies, Proving Again That Pig Organs Are for Pigs, Not Humans

 

    In an era of improving technology, scientists are trying to find a way to use animal organs as human transplants. But is this actually working? What are the consequences to the animal, and is it safe for humans to use it? In an article published in May 2024 and updated in July 2024, PETA reported on cases of animal organ transplants and data revolving around the outcomes. 

    While the idea of using animal organs as human transplants sounds promising, the results have not been very effective. Updated in July 2024, four patients receiving an organ transplant from genetically altered pigs have died, continuing the 100% failure rate of xenotransplantation. The author emphasized: 

"Humans need organs. But in case this has escaped anyone’s attention, pigs and other animals also need theirs. They don’t belong to us." (PETA, 2024). 

    And as my previous blog discussed, Japan's new legislation on creating human chimera to create more opportunities for xenotransplantation has allowed scientists there to have more chances to conduct deeper research on the topic. The approach from Japanese scientists is more promising in terms of success in transplanting, as it was cultured with stem cells, therefore creating a higher chance that the human body would accept it. But this also raises a major question about bioethics: whether or not this is an ideal way to do transplanting, what regulations can be passed to control these controversial studies, and to what point is the experiment too extreme? 

WORKS CITED

PETA (2024). Fourth Transplant Patient Dies, Proving Again That Pig Organs Are for Pigs, Not Humans. https://www.peta.org/blog/pig-kidney-transplant-patient-dies/

Pontbriand, H. D. (2019). Pig-human chimeras: a clinical trial announced in Japan. Bioethics News. https://bioethics-news.com/2019/05/13/pig-human-chimeras-a-clinical-trial-announced-in-japan/ 

Pig-human chimeras: a clinical trial announced in Japan

 

    In an article published in 2019 on Bioethics Press Synthesis, Henrianne introduced one of the new advancements in biology and the medical field, but it is also one of the most controversial experiments in recent years. 

    In this era, there is a high demand for organ transplants. In the past, the organs were mostly from human donors. But as science becomes more advanced, we have found ways to use organs from animals to transplant for those in need, rather than waiting for a donor, which is very rare. In 2019, a Japanese researcher, Hiromitsu Nakauchi, announced his new experiment in Japan to culture human pancreas in pigs. This was proposed soon after Japan had relaxed its chimera law. 

    In this experiment, he planned to inject human induced pluripotent stem cells into genetically modified pig embryos. The result after these cells are injected was described as: 

"These iPS cells will take the place of the removed gene in the embryos to create a human pancreas. The chimera embryo will then be implanted into a carrier sow’s uterus. The foetus will be removed before birth to study how much pancreatic tissue is derived from human iPS cells and how it functions." (Pontbriand, 2019). 

This is a big advancement in the study of chimeras. But at this time, these animal-human chimera embryos can only be implanted into animals; implanting chimeric embryos into humans is still prohibited. 

WORKS CITED

Pontbriand, H. D. (2019). Pig-human chimeras: a clinical trial announced in Japan. Bioethics News. https://bioethics-news.com/2019/05/13/pig-human-chimeras-a-clinical-trial-announced-in-japan/

Raposo, V. L. (2021). The new Japanese regulation on human/non-human chimeras: should we worry? National Library of Medicine. https://pmc.ncbi.nlm.nih.gov/articles/PMC7863089/

Rat Species Has No Y Chromosome!

Amami Spiny Rat

A team of researchers at Hokkaido University in Japan has figured out how a species of rat is able to survive and reproduce despite not having a Y chromosome. The rat species they studied was the Amami spiny rat (Tokudaia osimensis), a rodent native to the island of Amami Ōshima in southern Japan. The species, also called the Ryukyu spiny rat, is unique in that males do not have a Y chromosome and females only have one X chromosome as well. Previous attempts to study the rat have not been able to reveal how males are able to develop within the population with no Y chromosome. Typically in mammals, a gene on the Y chromosome called SRY tells the organism's body to express male genes like the SOX9 gene for testes. Not having the Y chromosome scientists were stumped at how males could develop. Lead researcher, Asato Kuroiwa, and her colleagues at Hokkaido have now discovered the answer! The secret was looking at the autosomes, non-sex chromosomes, in the rat. On chromosome 3 they found that one copy had a duplicated region next to the SOX9 gene. The duplication increases the activity of the SOX9 gene and it is able to code for testes. This duplicated region effectively replaces the SRY gene on the Y chromosome and explains how males of this species are formed. If a rat has the duplication region it acts as a proto-Y and the rat will be a male, and if the duplication region is absent, it acts as a proto-X and the rat will be a female. Further work to explore this is limited as the rat is an endangered species but the research so far has shown an amazing trait inherited by this rat population. The researchers predict the trait appeared about 2 million years ago when the Amami spiny rats diverged from their ancestors with a Y chromosome. Kuroiwa believes that a mixed population existed initially on the island but then a natural disaster like flooding or rising seas left mostly rats without the Y chromosome and over time the rats reproduced and evolved into a new species with this trait. 

Personally, this was my favorite article to read so far about genetics. I find it incredible that a species can exist without a Y chromosome and that another chromosome was able to replace its function to make males. This is a really interesting example of population evolution, genetic drift, and speciation. I hope that these rats can be studied more to learn about this unique and interesting trait. 

Researchers Found the Genes Responsible for Changing Ground Beetle Genitalia

Japan's Carabus male beetles mate with females by inserting their chitin-covered appendage. Two pieces of the appendage break off: a sperm delivery tube and a copulatory piece. Researchers identified several genes that control the size of the male beetle's "piece" and the female beetle's pocket. Initial hypotheses demonstrated that the male and female's genes for genitals should be connected through coevolution which should show in their genome. In other words, the size and shapes of genitalia in species should be analogous because the same genes influence male and female dimorphism. However, researchers found that there is much genetic diversity between the genes that determine these beetle's genitalia sizes. The discovery is a significant case in speciation because it contributes to an old speciation model called the "Lock-and-Key Hypothesis".

The Lock-and-Key Hypothesis is a method of reproductive isolation, specifically mechanical isolation which separates a species from mating. For example, the beetles described in the article have such a large genetic diversity contributing to genitalia that some of the male appendages do not fit into females. The article states, "Out-of-sync sizes can cause ruptures, snap-offs and generally low numbers of offspring." Talk about painful! These beetles are now contributing to hybridization which can eventually evolve into a whole other species altogether. Genetic hybrids tend to be infertile, but researchers found that the hybrids of two different beetle species in Japan can produce offspring.





It is truly interesting to see evolution in motion especially with the Lock-and-Key Hypothesis. It's no secret that genitalia in male species may not fit into a female in either the same species or another. The Lock-and-Key Hypothesis was proposed over a hundred years ago, but it's often overlooked because other reproductive isolations such as gametic isolation or chromosomal differences are better modes of preventing hybridization. The discovery here is fascinating because genetic diversity actually prevented some of these beetles from mating within their own species.

Sources:
https://www.sciencenews.org/article/ground-beetle-genitals-genetics-evolution-battle-sexes
https://advances.sciencemag.org/content/5/6/eaav9939

Japanese Researchers Successfully Decoded Morning Glories Entire Genome

The Morning Glory is a popular flower in Japan and is used as a traditional garden plant that blooms in the summer. The plants have something in their DNA known as "jumping genes" called transposons, which are mutants that frequently appear in the flowers. These mutations have been making the morning glories flowers and leaves have strangle shapes since the Edo period (200 years ago). These strangle shapes make the flowers more appreciated by the Japanese and have developed into a unique Japanese gardening culture. The popularity of the mutant morning glories, a lot of natural mutants have been collected. By analyzing the flowers mutants closely, the research team found the genes that cause the leaf shapes and flower color and patterns. 

Researchers in Japan have studied the Japanese Morning Glory and successfully decoded the flower's entire genome, obtaining a high-quality nearly complete genome sequence. This lead to the identification of the coding sequences in morning glory's 43,000 genes. Researchers also discovered the the number and distribution of transposons. The research group used the flowers entire genome to identify the mutants including dwarfism categorized by dark green, thick wrinkled leaves as well as the gene for plant biosynthesis that is disrupted by the transposons in the mutants.

One of the researchers said that after the morning glory's genome was decoded, the value of using the flower as a model organism has sky rocketed and could possibly used by researchers all around the world. The leader of the research said The genome sequence of the Japanese morning glory helped us to better understand the flower itself, as well as used to better understand related crops such as sweet potatoes. 

I think it's astonishing that flowers have have genes that make them different just like humans and animals do. This was the first time I've heard of transposons. It sparks an interest in me to learn more about how genes are transmitted. I hope to eventually see more studies similar to this one in the future. These studies can lead to way to more genetic discoveries.