After six decades of research, scientists have discovered the gene responsible for the orange fur seen in domestic cats. Two separate research teams found that the characteristic ginger, calico, and tortoiseshell colours in cats are due to a missing piece of DNA in a part of the cat’s genome that doesn’t make proteins. This breakthrough explains why some cats have their distinctive fiery fur.

“The sex-linked orange mutation in domestic cats causes variegated patches of reddish/yellow hair and is a defining signature of random X-inactivation in female tortoiseshell and calico cats. Unlike the situation for most coat colour genes, there is no apparent homolog for sex-linked orange in other mammals,” the authors of the study wrote.

“We show that the sex-linked orange is caused by a 5 kb deletion that leads to ectopic and melanocyte-specific expression of the Rho GTPase Activating Protein 36 (Arhgap36) gene. Single-cell RNA-seq studies from foetal cat skin reveal that red/yellow hair colour is caused by reduced expression of melanogenic genes that are normally activated by the melanocortin 1 receptor (Mc1r)-cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) pathway, but the Mc1r gene and its ability to stimulate cAMP accumulation are intact.”

“Instead, we show that increased expression of Arhgap36 in melanocytes leads to reduced levels of the PKA catalytic subunit (PKAC); thus, sex-linked orange is genetically and biochemically downstream of Mc1r. Our findings solve a comparative genomic conundrum, provide in vivo evidence for the ability of Arhgap36 to inhibit PKA, and reveal a molecular explanation for a charismatic colour pattern with a rich genetic history.”

“I am fully convinced this is the gene and am happy,” Carolyn Brown, a University of British Columbia geneticist who was not involved in either study, told Science. “It’s a question I’ve always wanted the answer to.”

As per a release, scientists have long been fascinated by tortoiseshell and calico cats: the offspring of a black cat and an orange cat. Multicoloured cats from such a cross are almost always female, suggesting the gene variant that makes fur orange or black is located on the X chromosome. The male offspring of such a cross are typically unicolor because they inherit just one parent’s X chromosome: We can guess, for instance, that Garfield’s mother is orange because he inherited his only X chromosome from her.

A DNA test has confirmed that a 70-year-old man who claimed to be one of Japan’s most wanted criminals was telling the truth. According to the BBC, Satoshi Kirishima made his confession on his hospital deathbed last month. “I want to meet my death with my real name,” he told the police. Now, a month later, officials have confirmed that the 70-year-old was indeed Kirishima, a member of a militant group behind several deadly bombings in the 1970s. He was wanted for nearly 50 years. 

It is unclear how Kirishima remained at large for so many years. He is suspected of helping plant a homemade bomb that blasted away parts of a building in Tokyo’s Ginza district in 1975, the outlet reported. There were no casualties. Back then, he belonged to the East Asia Anti-Japan Armed Front, a radical, left-wing organisation believed to be behind several bombings against companies in Tokyo in the 70s – including one targeting a Mitsubishi Heavy Industries building which left eight dead and more than 160 injured.

The 70-year-old is also believed to have been involved in four other attacks the ground carried out. Two other members of the group were sentenced to death for their involvement in attacks. It is thought he is the only member of the group never caught by the cops.

For years, Kirishima had been going under the name Hiroshi Uchida. He had reportedly lived in the city of Fujisawa, on the western edge of Tokyo, for almost 40 years. He told the cops he had worked day labour jobs before ending up working at a construction company. He had been paid in cash and didn’t have a phone to help him stay under the radar. He also didn’t have a driving licence or any health insurance when he arrived at the hospital. 

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The saga took a sudden turn when the terminally ill man hospitalised near Tokyo confessed on his deathbed that he was Kirishima. This prompted the hospital staff to alert the police and through subsequent DNA analysis, “the person who died at the hospital on January 29 was confirmed to be Satoshi Kirishima himself”, a Tokyo police spokesman said, as per Japan Times. 

While interrogated by police shortly before his death, Mr Kirishima recounted details about his family and extremist group that only he could have known. 

Police will now continue to investigate whether or not anyone helped Kirishima stay undetected for all this time. 

A view shows fossil cells, in Bogota, Colombia, in this image taken in 2022.
| Photo Credit: Reuters

Remnants of DNA have been discovered in fossilised remains dating to 6 million years ago of a sea turtle closely related to today’s Kemp’s ridley and olive ridley turtles, marking one of the rare times genetic material has been identified in such ancient fossils of a vertebrate, researchers said on Thursday.

The researchers said some bone cells, called osteocytes, were exquisitely preserved in the fossil, which was excavated along Panama’s Caribbean coast in 2015. The fossil is partial, with a relatively complete carapace – the turtle’s shell – but not the rest of the skeleton. The turtle would have been about a foot (30 cm) long when alive, they said.

In some of the osteocytes, the cell nuclei were preserved and reacted to a chemical solution that allowed the researchers to recognise the presence of remnants of DNA, the molecule that carries genetic information for an organism’s development and functioning, said palaeontologist Edwin Cadena, lead author of the study published in the Journal of Vertebrate Paleontology.

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“I want to point out that we did not extract DNA, we only were able to recognise the presence of DNA traces in the nuclei,” added Cadena, of Universidad del Rosario in Bogota and the Smithsonian Tropical Research Institute.

DNA is quite perishable, though in the right conditions it has been preserved in some ancient remains. Researchers last year reported the discovery of DNA from animals, plants and microbes dating to about 2 million years ago from sediment at Greenland’s remote northernmost point.

Cadena said the only older vertebrate fossils than the newly described turtle to have been found with similar DNA remnants were of two dinosaurs – Tyrannosaurus, which lived about 66 million years ago, and Brachylophosaurus, which lived about 78 million years ago. Cadena said DNA remnants also have been reported in insects dating to tens of millions of years ago.

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The turtle is from the same genus – Lepidochelys – as two of the world’s seven living species of sea turtles – the Kemp’s ridley, the world’s smallest sea turtle, and the olive ridley, Cadena said. Kemp’s ridley, with a triangular-shaped head and a slightly hooked beak, is primarily found in the Gulf of Mexico. The olive ridley, which closely resembles the Kemp’s ridley, has a larger distribution, primarily found in the tropical regions of the Pacific, Indian and Atlantic oceans.

The fossil represents the oldest-known member of Lepidochelys and helps to shed light on the poorly understood evolutionary history of this genus, the researchers said. They did not identify it by species because the remains were too incomplete, Cadena said.

“Each fossil, each fossil site has specific conditions of preservation that in some cases could have favored preservation of original biomolecular remains such as proteins and DNA,” Cadena said.

“Maybe in the future and with more studies of this kind, we could be able at some point to sequence very small pieces of DNA and to infer things about their close relatives or involve that information in a broader molecular evolutionary study,” Cadena added.