Millions of years before scientists created genetically modified Atlantic salmon with genes from two other fish, nature created genetically modified smelt with a gene from herring, growing evidence shows.
And now the Canadian scientists who first proposed that controversial idea say they have a hunch how nature might have done it.
A new study by Queen’s University researchers Laurie Graham and Peter Davies finds “conclusive” evidence for the controversial idea that the antifreeze gene that helps rainbow smelt survive icy coastal waters originally came from herring and was somehow stolen by smelt about 20 million years ago.
They propose in their new paper in Trends in Genetics that this could have happened through a process quite similar to the way genes are sometimes transferred from one species to another by scientists in the lab today.
Stealing genes from other species
Genes are normally passed on from parents to offspring. But in recent decades, scientists discovered they can also “jump” or be “stolen” from one species to another outside normal reproduction — a process called horizontal gene transfer or lateral gene transfer.
It’s something that happens frequently among microbes such as bacteria — so frequently that Canadian scientist W. Ford Doolittle suggested it might explain a big part of life’s history on Earth.
There’s been some recent evidence of it happening in some more complex organisms. For example, aphids appear to have stolen a fungus gene to make a plant pigment and marine algae seem to have colonized the land 500 million years ago with the help of a gene stolen from soil bacteria. Most recently, scientists reported last week the first known case of a gene getting transferred from a plant to an animal.
In more complex organisms such as fish and people, certain virus-like DNA sequences called “transposable elements” or “transposons” are also known to jump from species to species.
But the same hadn’t been seen for useful genes that code for things like proteins. That’s because genes in multicellular organisms can only be transmitted from generation to generation if they specifically get into reproductive cells such as eggs or sperm.
Davies is a professor and Canada Research Chair in Protein Engineering at Queen’s University. Graham is a research associate in his lab.
When the two first realized more than a decade ago that the herring and smelt must have shared their antifreeze protein via horizontal gene transfer, it was the first time anyone had suggested that a vertebrate — a complex animal with a backbone — had transferred such a gene to another vertebrate. That made it quite controversial.
“We had a really hard time finding a journal to take our first paper,” recalled Graham. “The reviewers were not exactly kind, and there was a lot of doubt.”
It didn’t help that a high-profile report of horizontal gene transfer in complex organisms at the time, from bacteria to humans, had been called into question by other scientists, who proposed other explanations for genes shared among the two types of organisms.
Clues pointing to a stolen gene
Graham had been originally examining different kinds of antifreeze proteins, not just in fish but also insects, bacteria, plants and small soil creatures called springtails.
Most of them appeared to arise from a common ancestor, with a similar structure in closely related animals.
But that wasn’t the case for herring and smelt, which are so distantly related that the last time they shared an ancestor was 250 million years ago, about the time the first dinosaurs arose.
“Every other gene we’ve looked at in these two species, it tends to be quite different,” Graham said.
Meanwhile, she added, closer cousins don’t have the antifreeze protein that Atlantic herring, Pacific herring and rainbow smelt are known to share.
“We’ve got other fish that are more closely related to these species that make completely different kinds of antifreeze protein. So this doesn’t really make sense on an evolutionary basis if everybody’s inheriting their antifreeze protein from their ancestors.”
Skeptics weren’t convinced, so the researchers looked for more evidence. Closely related fish such as different types of smelt tend to have the same genes in the same order. And the researcher found that was the case — except for the antifreeze gene, which was found between two genes that are normally next to each other in other smelt.
“That’s what you would expect when you have a gene that’s just sort of been pasted into a genome through horizontal gene transfer.”
Then, recently, the researchers heard that the genome of Atlantic herring was published in a public database.
They decided to take a closer look.
Remember those transposable elements that often jump between organisms? They can also be used as a fingerprint for a particular organism. Herring have certain transposable elements pasted hundreds of times all over their genome, including in and around their eight antifreeze genes.
When the researchers looked at the smelt’s single antifreeze gene, it had three of those herring transposable elements attached, Graham said. “So it was like a little tag to say, ‘Hey, I’m from herring.'” Those transposable elements weren’t found anywhere else in the smelt.
The researchers say it’s conclusive evidence that the antifreeze gene moved between the two fish via horizontal gene transfer and that it went from herring to smelt and not vice versa.
How did the gene jump species?
When the researchers’ previous papers went through peer review, one of the questions reviewers had was how the gene might have moved between species, so they sought to come up with a hypothesis.
One possibility, they thought, was it might be similar to techniques used in the lab to create genetically modified animals. One called “sperm-mediated gene transfer” involves mixing sperm with the DNA you want to introduce, then using it to fertilize an egg.
“And we thought, ‘Well, couldn’t this also happen in nature?” Graham recalled.
Fish and many other marine animals have external fertilization, where eggs and sperm — known as milt — are released into the water at the same time in massive quantities during spawning, and some of them combine to produce offspring.
Graham noted that when herring spawn on Canada’s Atlantic and Pacific coasts, “you can actually see the ocean is sort of stained white from all of the milt that the male herring are releasing.”
The sperm breaks apart after a few hours, releasing DNA into the water. And the researchers proposed that during one of these events, herring DNA may have found its way into rainbow smelt eggs or sperm.
Graham acknowledges there’s no way to prove that — “not unless we had a time machine.”
But if that is the way the genes were transferred, it has probably happened with other fish genes also, Davies suggested, and scientists should start looking for other examples.
The other implication is that genetically modified organisms, which have been characterized by activists as “Frankenfoods”, might not be so unnatural.
“One of the take-home lessons here is that this genetic modification is actually happening in nature,” Davies said. “Not very often — it’s probably quite rare — but maybe we shouldn’t be so alarmed at this. It’s actually more of a natural event than we previously thought.”
What other scientists think
Garth Fletcher, professor emeritus and head of the ocean sciences department at Memorial University, is the co-inventor of Aquabounty’s genetically modified salmon (but not through sperm-mediated gene transfer) and has previously collaborated with Davies comparing antifreeze proteins in fish. He wasn’t involved in the new study.
Fletcher doesn’t think the research will reassure those opposed to GMOs.
He says it’s significant that the researchers have gotten to the point where they feel their evidence for horizontal gene transfer in this controversial case is so strong. He credited new molecular genetic techniques with making it possible.
“Twenty years ago, you couldn’t have done this stuff.”
Luis Boto, head scientist in the evolutionary biology department at the National Museum of Natural Sciences in Madrid, has been tracking the evidence for horizontal gene transfer in complex organisms, and said the new genetic tools will allow scientists to explore how common this is.
“This paper opens the door to an important research field in that sequencing of new fish genomes will provide us with interesting findings,” he added in an email, “and will allow us to understand more about the possible importance of horizontal gene transfer in the evolution of animals.”
He said evidence for horizontal gene transfer in vertebrates remains rare, but the new paper offers “important support” for the case of it happening between herring and smelt.
Gane Ka-Shu Wong, a University of Alberta biology professor, is also convinced by the study and thinks the proposed way the gene moved from herring to smelt is plausible.
Wong published a study a couple of years ago showing plants, which used to be confined to the oceans, stole a gene from soil bacteria to gain the ability to colonize land.
While such horizontal gene transfer events seem rare in complex organisms, if they help the organism survive, they could make a big difference, he said.
“My guess is that a lot of a lot of important evolutionary events may have been driven by some sort of horizontal gene transfer.”
Breathtaking NASA Image Shows a Magical ‘Sea of Dunes’ on Mars
It also shows wind-sculpted lines surrounding Mars’ frosty northern polar cap.
The section captured in the shot represents an area that is 31 kilometers (19 miles) wide, NASA said. The sea of dunes, however, actually covers an area as large as Texas.
The photo is a false color image, meaning that the colors are representative of temperatures. Blue represents cooler climes, and the shades of yellow mark out “sun-warmed dunes,” the US space agency wrote.
The photo is made of a combination of images captured by the Thermal Emission Imaging System instrument on the Mars Odyssey orbiter, NASA wrote.
Captured during the period from December 2002 to November 2004, the breathtaking images have been released to mark the 20th anniversary of Odyssey.
The Mars Odyssey orbiter is a robotic spacecraft circling Mars that uses a thermal imager to detect evidence of water and ice on the planet.
It was launched in 2001, making it the longest-working Mars spacecraft in history.
Humans actually hunted large animals and ate mostly meat for 2 millions years: study – CTV News
Despite a widespread belief that humans owe their evolution to the dietary flexibility in eating both meat and vegetables, researchers in Israel suggest that early humans were actually apex predators who hunted large animals for two million years before they sought vegetables to supplement their diet.
In a study recently published in the American Journal of Physical Anthropology, academics from Tel Aviv University in Israel and the University of Minho in Portugal examined modern biology to determine if stone-age humans were specialized carnivores or generalist omnivores.
“So far, attempts to reconstruct the diet of Stone-Age humans were mostly based on comparisons to 20th century hunter-gatherer societies,” one of the study’s authors, Miki Ben-Dor, a researcher at Tel Aviv University, said in a press release.
“This comparison is futile, however, because two million years ago hunter-gatherer societies could hunt and consume elephants and other large animals – while today’s hunter gatherers do not have access to such bounty.”
Instead, the researchers looked at approximately 400 previous scientific studies on human anatomy and physiology as well as archeological evidence from the Pleistocene period, or “Ice Age” period, which began about 2.6 million years ago, and lasted until 11,700 years ago.
“We decided to use other methods to reconstruct the diet of Stone-Age humans: to examine the memory preserved in our own bodies, our metabolism, genetics and physical build,” Ben-Dor said.
“Human behaviour changes rapidly, but evolution is slow. The body remembers.”
They discovered 25 lines of evidence from the studied papers on human biology that seem to show that earlier Homo sapiens were apex predators at the top of the food chain.
For example, the academics explained that humans have a high acidity in their stomachs when compared to omnivores or even other predators, which is important for consuming animal products.
“Strong acidity provides protection from harmful bacteria found in meat, and prehistoric humans, hunting large animals whose meat sufficed for days or even weeks, often consumed old meat containing large quantities of bacteria, and thus needed to maintain a high level of acidity,” Ben-Dor said.
Another piece of evidence, according to the study, is the structure of human fat cells.
“In the bodies of omnivores, fat is stored in a relatively small number of large fat cells, while in predators, including humans, it’s the other way around: we have a much larger number of smaller fat cells,” Ben-Dor said.
In addition to the evidence they collected by studying human biology, the researchers said archeological evidence from the Pleistocene period supports their theory.
In one example, the study’s authors examined stable isotopes in the bones of prehistoric humans as well as their hunting practices and concluded these early humans specialized in hunting large and medium-sized animals with high fat content.
“Comparing humans to large social predators of today, all of whom hunt large animals and obtain more than 70% of their energy from animal sources, reinforced the conclusion that humans specialized in hunting large animals and were in fact hypercarnivores,” the academics noted.
Ben-Dor said Stone-Age humans’ expertise in hunting large animals played a major role in the extinction of certain large animals, such as mammoths, mastodons, and giant sloths.
“Most probably, like in current-day predators, hunting itself was a focal human activity throughout most of human evolution. Other archeological evidence – like the fact that specialized tools for obtaining and processing vegetable foods only appeared in the later stages of human evolution – also supports the centrality of large animals in the human diet, throughout most of human history,” he said.
This is not to say, however, that humans during this period didn’t eat any plants. Ben-Dor said they also consumed plants, but they weren’t a major component of their diet until the end of the era when the decline of animal food sources led humans to increase their vegetable intake.
Eventually, the researchers said humans had no choice but to domesticate both plants and animals and become farmers.
Ran Barkai, one of the study’s authors and a professor at Tel Aviv University, said their findings have modern-day implications.
“For many people today, the Paleolithic diet is a critical issue, not only with regard to the past, but also concerning the present and future. It is hard to convince a devout vegetarian that his/her ancestors were not vegetarians, and people tend to confuse personal beliefs with scientific reality,” he said.
Marimaca Copper: First Drill Hole Intersects Broad Zone of Sulphide Copper Mineralization at Marimaca – Junior Mining Network
VANCOUVER, British Columbia, April 07, 2021 (GLOBE NEWSWIRE) — Marimaca Copper Corp. (“Marimaca Copper” or the “Company”) (TSX: MARI) is pleased to announce the assay results of the first drill hole of a five-hole program targeting extensions of sulphide mineralization below the Company’s flagship Marimaca Oxide Deposit (“MOD”). Drilling encountered a broad zone of chalcopyrite and minor chalcocite, indicating potential for economic sulphide mineralization.
- Drill hole MAR-125 intersected 116m (expected approximate true width) at an average grade of 0.51% CuT from 162m, including two higher grade zones of:
- 20m with an average grade of 0.77% CuT from 162m; and
- 42m with an average grade of 0.92% CuT from 236m.
- Intersection represents a significantly broader zone of mineralization than anticipated from earlier, nearby, sulphide drilling intersections
- First drill hole of an initial five-hole campaign to test for extensions of mineralization at depth
- First hole designed to extend mineralization closer to sulphide zones identified in historical drilling
- Remaining four holes designed to test the limits of mineralization with step outs of approximately 300m at depth and between 400m and 700m along strike to the north and south of the first hole
- Sulphide drilling to be completed shortly, with assay results on remaining holes expected by the end of April 2021
- In response to escalating COVID situation in Chile, the Company has initiated a break in drilling which is not expected to impact the original target of testing all identified targets by the end of 1H 2021.
Sergio Rivera, VP Exploration of Marimaca Copper, commented:
“The results of the first hole of this initial campaign are extremely pleasing, exceeding both the widths and grades we had projected for this zone based on earlier drilling completed nearby. The broad intercept of chalcopyrite mineralization shows good continuity downhole, with potentially economic grades, especially at the bottom of the intercept.
“The drilling has also provided additional geological information, which we are using to refine our understanding of the controls of mineralization and to inform future drillhole locations, targeting mineralized extensions at depth and along strike.
“The next four holes are significant step outs from the known mineralized zones outside of the Mineral Resource Estimate area and are designed to test the limits of the mineralized body, both at depth and along strike. The second hole will be collared approximately 350m to the east of MAR-125, targeting mineralization up to 300m below the current deepest mineralization. The third, fourth and fifth holes will be located between 400m and 700m to the north and south of MAR-125, aiming to test for extensions along strike.
“This first hole has provided encouragement that there is potential for economically interesting sulphide mineralization at Marimaca, while the next four drill holes are designed to better delineate the tonnage potential of this.”
Discussion of Campaign Objectives and Results
The current five-hole drilling campaign at the Marimaca Copper Project is designed to test for extensions to mineralization below the MOD. Based on the structural controls of the mineralization, the results of previous geophysical campaigns and earlier drilling, which extended beyond the current Mineral Resource Estimate (“MRE”) area, the Company believes there is the potential for extensions of the mineralized body at depth across the full strike length of the MOD. All drill holes will be drilled at an azimuth of 270o and at -60o, roughly perpendicular to the north-south striking, easterly dipping mineralizing structures. Intercepts should, therefore, be relatively close to the true width of the mineralization.
The first drill hole (MAR-125) encountered a broad zone of dominantly chalcopyrite mineralization with some pyrite and minor chalcocite over a down hole width (expected to be equivalent to approximate true width) of 116m with an average grade of 0.51% CuT. This includes two zones of higher-grade mineralization including 20m with an average grade of 0.77% CuT and 42m with an average grade of 0.92% CuT at the end of the mineralized intercept. The hole was collared to test mineralization approximately 100m to the east of the earlier hole ATR-82, which intersected 44m of sulphide copper mineralization with an average grade of 1.05% CuT, and 200m and 300m east of holes ATR-93 and ATR-94 respectively, which both intersected mineralization with true widths of around 40m with average grades above 1.0% CuT. MAR-125 has demonstrated an extension to this higher-grade mineralization and provides further areas to target for follow up drilling.
MAR-125 is located in the center of the current MRE area, proximal to a zone of relatively high-grade sulphide mineralization intercepted in several drill holes over widths of between 30m and 50m. The remaining four drill holes have been located to test the limits of the mineralization by stepping out significantly at depth and along strike beyond the current MRE area. The collar of the second hole, MAS-03, is located approximately 100m to the south and 350m to the east of MAR-125 and is aimed to intersect mineralization approximately 300m below MAR-125. MAS-02 and MAS-04, located approximately 400m and 700m, respectively, south of MAR-125, and are planned as significant step outs along strike, targeting the conductivity high noted in the IP survey completed across the MOD
Sampling and Assay Protocol
True widths cannot be determined with the information available at this time. Marimaca Copper RC holes were sampled on a 2-metre continuous basis, with dry samples riffle split on site and one quarter sent to the Andes Analytical Assay preparation laboratory in Calama and the pulps then sent to the same company laboratory in Santiago for assaying. A second quarter was stored on site for reference. Samples were prepared using the following standard protocol: drying; crushing to better than 85% passing -10#; homogenizing; splitting; pulverizing a 500-700g subsample to 95% passing -150#; and a 125g split of this sent for assaying. All samples were assayed for CuT (total copper), CuS (acid soluble copper) by AAS. A full QA/QC program, involving insertion of appropriate blanks, standards and duplicates was employed with acceptable results. Pulps and sample rejects are stored by Marimaca Copper for future reference.
The technical information in this news release, including the information that relates to geology, drilling and mineralization was prepared under the supervision of, or has been reviewed by Sergio Rivera, Vice President of Exploration, Marimaca Copper Corp, a geologist with more than 36 years of experience and a member of the Colegio de Geólogos de Chile and of the Institute of Mining Engineers of Chile, and who is the Qualified Person for the purposes of NI 43-101 responsible for the design and execution of the drilling program.
Mr. Rivera confirms that he has visited the Marimaca Project on numerous occasions, is responsible for the information contained in this news release and consents to its publication.
For further information please visit www.marimaca.com or contact:
+44 (0) 207 920 3150
Jos Simson/Emily Moss
Forward Looking Statements
This news release includes certain “forward-looking statements” under applicable Canadian securities legislation. These statements relate to future events or the Company’s future performance, business prospects or opportunities. Forward-looking statements include, but are not limited to, the impact of a rebranding of the Company, the future development and exploration potential of the Marimaca Project. Actual future results may differ materially. There can be no assurance that such statements will prove to be accurate, and actual results and future events could differ materially from those anticipated in such statements. Forward-looking statements reflect the beliefs, opinions and projections on the date the statements are made and are based upon a number of assumptions and estimates that, while considered reasonable by Marimaca Copper, are inherently subject to significant business, economic, competitive, political and social uncertainties and contingencies. Many factors, both known and unknown, could cause actual results, performance or achievements to be materially different from the results, performance or achievements that are or may be expressed or implied by such forward-looking statements and the parties have made assumptions and estimates based on or related to many of these factors. Such factors include, without limitation: risks related to share price and market conditions, the inherent risks involved in the mining, exploration and development of mineral properties, the uncertainties involved in interpreting drilling results and other geological data, fluctuating metal prices, the possibility of project delays or cost overruns or unanticipated excessive operating costs and expenses, uncertainties related to the necessity of financing, the availability of and costs of financing needed in the future as well as those factors disclosed in the Company’s documents filed from time to time with the securities regulators in the Provinces of British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, New Brunswick, Nova Scotia, Prince Edward Island and Newfoundland and Labrador. Accordingly, readers should not place undue reliance on forward-looking statements. Marimaca Copper undertakes no obligation to update publicly or otherwise revise any forward-looking statements contained herein whether as a result of new information or future events or otherwise, except as may be required by law.