New York, Jul 11 (AP/UNB) — If in the beginning there was male and female, fish seem to have forgotten the memo.
For nearly 500 fish species, including the clownfish in "Finding Nemo," the great divide between sexes is more like a murky line: If circumstances call for it, the fish can swap their sex, with females turning into males in some species and males turning into females in others.
People think of sex as being fixed, said biologist Erica Todd from the University of Otago in New Zealand, "but there are so many fish that can push it in the other direction."
Scientists have known for decades about the sex trades, but they've had limited understanding of how the exchange happens. In a study published Wednesday in Science Advances, Todd and her colleagues detail the molecular events behind this ability, as well as what keeps mammals stuck as one sex or another.
The researchers looked at the bluehead wrasse, a reef fish that swims in small groups of a dominant blue-headed male and a posse of smaller yellow females. Normally the male and females stay as they are, feeding together and occasionally mating. But if a predator happens to snatch up the lead male, the dominant female in the group will become a male.
"The sex change in this species is remarkable because it's so quick," Todd said. It takes only minutes to a few hours for the female's behavior to become more territorial and aggressive like a male. In a few days, she courts other females. And after eight to 10 days, she's fully transitioned to a male.
Todd and her team removed the lead males from several wrasse groups in the Florida Keys. As the females changed sexes, the researchers took DNA from cells in the animal's brains and genitals so they could follow what was happening at the genetic level.
They found that removing the males likely stressed females. The hormones released from that stress dial back the activity of the gene that makes the female hormone estrogen, and eventually ovary cells start to die. At the same time, those hormones increase activity in the genes that produce male hormones, and later testicles form.
At a certain point, the reproductive gland "is mostly dying female cells and proliferation of early male cells," Todd said.
But hormones weren't the only thing switching around. The scientists also saw a complete rearrangement of chemical tags that attach to DNA. These tags turn genes on or off and have specific arrangements in males and females.
As female wrasse transitioned to a male, these tags were removed and reorganized, almost as if the fish was being reprogrammed.
"They're sort of poised and ready to go either direction" like a seesaw, she said. The hormones help push it to the male side.
Laura Casas, a biologist in Spain who was not involved in the study, called the results surprising. She expects the findings can apply to other sex-changing fish, including her study animal clownfish, which shift from male to female.
Matthew Grober, of Georgia State University, was more skeptical, especially of stress as the source that triggers the change. He questioned how the fish avoid changing sex from day-to-day stress and suspects something else is at play.
All animals with a backbone, including humans, share these genes, raising the question of whether all of them have a deep-seated capability to switch sex.
That's unlikely. Our reproductive systems are more complex and would be far more complicated to rewire, Todd said. There's also cell machinery that aggressively opposes the seesaw from swinging the other way.
"These fish are just able to go back and remove that suppression," she said.
Nanjing, July 10 (Xinhua/UNB) -- A Chinese university signed an agreement with the team of the Blue Brain Project, an attempt by Swiss scientists to create synthetic brains, to conduct brain science research together.
Southeast University in Nanjing, capital of east China's Jiangsu Province, and the European team will jointly build a database of cranial nerves accessible to global brain scientists for research of brain neurons and related medicine development, according to the deal they inked on Monday.
Sean Hill, member of the Blue Brain Project, said Southeast University, which is the first academic institute they have cooperated with in China, is well-equipped with the neuromorphic reconstruction technology they need.
Researchers of both sides will try to realize large-scale reconstruction of brain neurons through technologies like machine vision and virtual reality in a bid to explore brain and brain-like intelligence, said Peng Hanchuan, a researcher with the university.
Founded in 2005, the Blue Brain Project is a brain research initiative that aims to create a digital reconstruction of rodent and eventually human brains.
Tokyo, July 10 (Xinhua/UNB) -- Japan's Hayabusa2 space probe on Wednesday began its descent to an asteroid called Ryugu about 250 million km from earth where it will collect samples from an artificial crater that may contain water and organic substances, Japan Aerospace Exploration Agency (JAXA) said.
This will be the second time the probe has landed on the asteroid, with the latest landing aimed at collecting debris from a crater made in April by the probe when it fired a projectile at the Ryugu’s surface, the agency said.
Organic substances and water may be contained in the new samples to be collected by Hayabusa2, and along with a number of exploratory activities, JAXA's mission to Ryugu and the probe’s findings are hoped to possibly reveal clues about the solar system’s evolution and possibly the beginning of life itself.
According to JAXA, the probe began its descent at around 11:00 a.m. local time, from a position of 20 km above the asteroid’s surface, at a speed of 40 centimeters per second.
When the probe is five km above Ryugu’s surface on Wednesday night, its speed of descent will be slowed to 10 cm per second, said JAXA.
Johannesburg, Jul 8 (AP/UNB) — Mandla Maseko, a South African man who had won the opportunity to become the first black African to go into space, has died in a motorcycle crash. He was 30.
Maseko was killed in Pretoria over the weekend, according to a family statement reported by local media Monday.
Maseko became known as an "Afronaut" and was an inspiration to many South Africans when he won an international competition to get a place in the Axe Apollo Space Academy and spent a week in training at the Kennedy Space Center in Florida in 2015. His goal was to go into suborbital flight in which he would experience weightlessness.
"I want to be able to float and see outside the window and see this big round blue and white ball that is called earth," Maseko told The Associated Press in 2014.
Maseko, who came from a poor township outside Pretoria, said that his role model was Nelson Mandela.
"He broke new ground by being the first black president in South Africa ... that was inspiration for me," said Maseko.
Although the space flight didn't take place, Maseko was still trying. He was working as a part-time disc jockey and was a candidate officer in the South African air force, according to South Africa's Eye Witness News.
Maseko gave motivational speeches in South Africa, and in 2014 he said: "Defy gravity in everything that you do by shooting for the moon."
Dhaka, Jul 8 (AP/UNB) -As a NASA airborne astronomy ambassador and director of the University of Wisconsin-Milwaukee Manfred Olson Planetarium, I know that the technologies behind weather forecasting, GPS and even smartphones can trace their origins to the race to the Moon.
October 4, 1957 marked the dawn of the Space Age, when the Soviet Union launched Sputnik 1, the first human-made satellite. The Soviets were the first to make powerful launch vehicles by adapting World War II-era long-range missiles, especially the German V-2.
From there, space propulsion and satellite technology moved fast: Luna 1 escaped the Earth’s gravitational field to fly past the Moon on January 4, 1959; Vostok 1 carried the first human, Yuri Gagarin, into space on April 12, 1961; and Telstar, the first commercial satellite, sent TV signals across the Atlantic Ocean on July 10, 1962.
The 1969 lunar landing also harnessed the expertise of German scientists, such as Wernher von Braun, to send massive payloads into space. The F-1 engines in Saturn V, the Apollo program’s launch vehicle, burned a total of 2,800 tons of fuel at a rate of 12.9 tons per second.
Saturn V still stands as the most powerful rocket ever built, but rockets today are far cheaper to launch. For example, whereas Saturn V cost US$185 million, which translates into over $1 billion in 2019, today’s Falcon Heavy launch costs only $90 million. Those rockets are how satellites, astronauts and other spacecraft get off the Earth’s surface, to continue bringing back information and insights from other worlds.
The quest for enough thrust to land a man on the Moon led to the building of vehicles powerful enough to launch payloads to heights of 21,200 to 22,600 miles (34,100 to 36,440 km) above the Earth’s surface. At such altitudes, satellites’ orbiting speed aligns with how fast the planet spins – so satellites remain over a fixed point, in what is called geosynchronous orbit. Geosynchronous satellites are responsible for communications, providing both internet connectivity and TV programming.
At the beginning of 2019, there were 4,987 satellites orbiting Earth; in 2018 alone, there were more than 382 orbital launches worldwide. Of the currently operational satellites, approximately 40% of payloads enable communications, 36% observe the Earth, 11% demonstrate technologies, 7% improve navigation and positioning and 6% advance space and earth science.
Space missions – back then and even today – have strict limits on how big and how heavy their equipment can be, because so much energy is required to lift off and achieve orbit. These constraints pushed the space industry to find ways to make smaller and lighter versions of almost everything: Even the walls of the lunar landing module were reduced to the thickness of two sheets of paper.
From the late 1940s to the late 1960s, the weight and energy consumption of electronics was reduced by a factor of several hundred at least – from the 30 tons and 160 kilowatts of the Electric Numerical Integrator and Computer to the 70 pounds and 70 watts of the Apollo guidance computer. This weight difference is equivalent to that between a humpback whale and an armadillo.
Manned missions required more complex systems than earlier, unmanned ones. For example, in 1951, the Universal Automatic Computer was capable of 1,905 instructions per second, whereas the Saturn V’s guidance system performed 12,190 instructions per second. The trend toward nimble electronics has continued, with modern hand-held devices routinely capable of performing instructions 120 million times faster than the guidance system that enabled the liftoff of Apollo 11. The need to miniaturize computers for space exploration in the 1960s motivated the entire industry to design smaller, faster and more energy-efficient computers, which have affected practically every facet of life today, from communications to health and from manufacturing to transportation.
4. Global network of ground stations
Communicating with vehicles and people in space was just as important as getting them up there in the first place. An important breakthrough associated with the 1969 lunar landing was the construction of a global network of ground stations, called the Deep Space Network, to let controllers on Earth communicate constantly with missions in highly elliptical Earth orbits or beyond. This continuity was possible because the ground facilities were placed strategically 120 degrees apart in latitude so that each spacecraft would be in range of one of the ground stations at all times.
Because of the spacecraft’s limited power capacity, large antennas were built on Earth to simulate “big ears” to hear weak messages and to act as “big mouths” to broadcast loud commands. In fact, the Deep Space Network was used to communicate with the astronauts on Apollo 11 and was used to relay the first dramatic TV images of Neil Armstrong stepping onto the Moon. The network was also critical for the survival of the crew on Apollo 13 because they needed guidance from ground personnel without wasting their precious power on communications.
Several dozen missions use the Deep Space Network as part of the continuing exploration of our solar system and beyond. In addition, the Deep Space Network permits communications with satellites that are on highly elliptical orbits, to monitor the poles and deliver radio signals.
5. Looking back at Earth
Getting to space has allowed people to turn their research efforts toward Earth. In August 1959, the unmanned satellite Explorer VI took the first crude photos of Earth from space on a mission researching the upper atmosphere, in preparation for the Apollo program.
Almost a decade later, the crew of Apollo 8 took a famous picture of the Earth rising over the lunar landscape, aptly named “Earthrise.” This image helped people understand our planet as a unique shared world and boosted the environmental movement.
Understanding of our planet’s role in the universe deepened with Voyager 1’s “pale blue dot” photo – an image received by the Deep Space Network.
People and our machines have been taking pictures of the Earth from space ever since. Views of Earth from space guide people both globally and locally. What started in the early 1960s as a U.S. Navy satellite system to track its Polaris submarines to within 600 feet (185 meters) has blossomed into the Global Positioning System network of satellites providing location services worldwide.
Images from a series of Earth-observing satellites called Landsat are used to determine crop health, identify algae blooms and find potential oil deposits. Other uses include identifying which types of forest management are most effective in slowing the spread of wildfires or recognizing global changes such as glacier coverage and urban development.
As we learn more about our own planet and about exoplanets – planets around other stars – we become more aware of how precious our planet is. Efforts to preserve Earth itself may yet find help from fuel cells, another technology from the Apollo program. These storage systems for hydrogen and oxygen in the Apollo Service Module, which contained life-support systems and supplies for the lunar landing missions, generated power and produced potable water for the astronauts. Much cleaner energy sources than traditional combustion engines, fuel cells may play a part in transforming global energy production to fight climate change.
We can only wonder what innovations from the effort to send people to other planets will affect earthlings 50 years after the first Marswalk.