Sperm don’t swim anything like we thought they did, new study finds

Under a microscope, human sperm seem to swim like wiggling eels, tails gyrating to and fro as they seek an egg to fertilize. 

But now, new 3D microscopy and high-speed video reveal that sperm don’t swim in this simple, symmetrical motion at all. Instead, they move with a rollicking spin that compensates for the fact that their tails actually beat only to one side. 

“It’s almost like if you’re a swimmer, but you could only wiggle your leg to one side,” said study author Hermes Gadêlha, a mathematician at the University of Bristol in the U.K. “If you did this in a swimming pool and you only did this to one side, you would always swim in circles. … Nature in its wisdom came [up] with a very complex, ingenious way to go forward.” 

Strange swimmers

The first person to observe human sperm close up was Antonie van Leeuwenhoek, a Dutch scientist known as the father of microbiology. In 1677, van Leeuwenhoek turned his newly developed microscope toward his own semen, seeing for the first time that the fluid was filled with tiny, wiggling cells. 

Under a 2D microscope, it was clear that the sperm were propelled by tails, which seemed to wiggle side-to-side as the sperm head rotated. For the next 343 years, this was the understanding of how human sperm moved. 

“[M]any scientists have postulated that there is likely to be a very important 3D element to how the sperm tail moves, but to date we have not had the technology to reliably make such measurements,” said Allan Pacey, a professor of andrology at the University of Sheffield in England, who was not involved in the research. 

The new research is thus a “significant step forward,” Pacey wrote in an email to Live Science. 

Gadêlha and his colleagues at the Universidad Nacional Autónoma de México started the research out of “blue-sky exploration,” Gadêlha said. Using microscopy techniques that allow for imaging in three dimensions and a high-speed camera that can capture 55,000 frames per second, they recorded human sperm swimming on a microscope slide. 

“What we found was something utterly surprising, because it completely broke with our belief system,” Gadêlha told Live Science. 

The sperm tails weren’t wiggling, whip-like, side-to-side. Instead, they could only beat in one direction. In order to wring forward motion out of this asymmetrical tail movement, the sperm head rotated with a jittery motion at the same time that the tail rotated.The head rotation and the tail are actually two separate movements controlled by two different cellular mechanisms, Gadêlha said. But when they combine, the result is something like a spinning otter or a rotating drill bit. Over the course of a 360-degree rotation, the one-side tail movement evens out, adding up to forward propulsion.

“The sperm is not even swimming, the sperm is drilling into the fluid,” Gadêlha said. 

The researchers published their findings today (July 31) in the journal Science Advances.

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Asymmetry and fertility

In technical terms, how the sperm moves is called precession, meaning it rotates around an axis, but that axis of rotation is changing. The planets do this in their rotational journeys around the sun, but a more familiar example might be a spinning top, which wobbles and dances about the floor as it rotates on its tip. 

“It’s important to note that on their journey to the egg that sperm will swim through a much more complex environment than the drop of fluid in which they were observed for this study,” Pacey said. “In the woman’s body, they will have to swim in narrow channels of very sticky fluid in the cervix, walls of undulating cells in the fallopian tubes, as well have to cope with muscular contractions and fluid being pushed along (by the wafting tops of cells called cilia) in the opposite direction to where they want to go. However, if they are indeed able to drill their way forward, I can now see in much better clarity how sperm might cope with this assault course in order to reach the egg and be able to get inside it,” Pacey said

Sperm motility, or ability to move, is one of the key metrics fertility doctors look at when assessing male fertility, Gadêlha said. The rolling of the sperm’s head isn’t currently considered in any of these metrics, but it’s possible that further study could reveal certain defects that disrupt this rotation, and thus stymy the sperm’s movement. 

Fertility clinics use 2D microscopy, and more work is needed to find out if 3D microscopy could benefit their analysis, Pacey said. 

“Certainly, any 3D approach would have to be quick, cheap and automated to have any clinical value,” he said. “But regardless of this, this paper is certainly a step in the right direction.”

Originally published in Live Science.

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Cassie Shows Off Postpartum Body, But We Wish She Didn't Have To

Since having daughter Frankie in December, singer and model Cassie has not the most prolific of new celebrity moms on social media. But on Monday, she took to her Instagram Stories with an admission that we think might explain her absence. She seems to have gone back and forth with accepting her postpartum body.

“I haven’t posted anything like this in a while, but I’m very proud of myself,” wrote Cassie, who married trainer and bull-rider Alex Fine last year, shortly after ending her 10-plus-year relationship with Diddy. “The female body is truly an amazing thing. I didn’t rush to lose weight after having Frankie in December, but when I was ready to, I struggled with it for some months.”

After spending her career modeling and performing, we imagine it was difficult for Cassie not to feel she was in the same physical shape as she had been in for most of her life. Pregnancy and childbirth take a toll on the body — changing everything from lung capacity to bone density — and it’s not necessarily realistic to expect that once the baby is finally outside your body that you can get it “back” just by exercising and dieting a lot.

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♐️♍️

A post shared by Casandra (@cassie) on

But we very much wish that no new parent felt that this is something they have to do. If we could live in a world in which women weren’t compelled to show off how they lost the baby weight — or even feel the need to explain that doing so is taking some time — we might all be a little healthier and happier.

For her part, Cassie said she realized she needed to be easier on herself.

“I stopped putting so much pressure on myself and with less stress and healthier habits,” she wrote. “This is me today 7 months postpartum. Feeling really good, I’m healthy and working on my strength. Love your body!”

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Day dreaming ✨

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Congratulations to Cassie for feeling good and being proud of herself, truly. Everyone else reading this, please know that you absolutely do not need to have abs like that seven months after having a baby, or ever. Do postpartum workouts and eat right so that you have the strength and endurance to care for your child and do everything else that makes your life fulfilling, not so that you have that extra line down your middle when you wear a bikini.

Cassie has managed to spend her career going by just one name. We wonder if her daughter or any of these celebrity kids with unique names will have the same privilege.

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Flu researchers say we should make a NEW antiviral to stop coronavirus

Flu researchers say we should make a NEW antiviral to prevent coronavirus from replicating throughout the body and stop focusing on repurposing old drugs

  • Researchers looked an older treatment for the flu, Tamiflu, and a newer treatment, Xofluza, the first new type of flu drug in 20 years
  • Xofluza limited the amount of time a person was sick by quickly stopping the virus from replicating and spreading throughout the body
  • The team says the same approach needs to work for coronavirus, creating a new drug that stops the virus from multiplying rather then repurposing old drugs
  • In the US, there are more than 1.8 million confirmed cases of the virus and more than 105,000 deaths
  • Here’s how to help people impacted by Covid-19

A new antiviral drug should be created to stop the novel coronavirus rather than repurposing old medication, a new study suggests.

Researchers compared an older antiviral treatment that most flu patients know compared to a newer one.

The newer treatment cut the amount of time people were sick with the flu, which limited the spread of the virus, because it stopped the disease from multiplying within an infected person. 

The team, from the University of Texas at Austin, says creating a drug that does the same for the coronavirus in early-stage patients would be more beneficial that trying to get existing drugs to treat late-stage patients.

A newer treatment fro flu Xofluza (blue) limited the amount of time a person was sick by quickly stopping the virus from replicating and spreading throughout the body rather than the older treatment of Tamiflu (green)

The team says the same approach needs to work for coronavirus, creating a new drug that stops the virus from multiplying rather then repurposing old drugs. Pictured: COVID-19 patients are taken into to the Wakefield Campus of the Montefiore Medical Center in the Bronx, New York, April 6

For the study, published in Nature Communications, the team looked at influenza and its implications for COVID, the disease caused by the virus.

Researchers first looked at the effects of Tamiflu, or its generic oseltamivir, one of three drugs the Centers for Disease Control and Prevention has endorsed to treat the flu.  

Then they looked at baloxavir, which is sold under the brand name Xofluza, the first new type of flu drug in 20 years.

The new treatment from the same company that developed Tamiflu, was shown in past studies to cut the amount of time people were sick and reduce the length of a fever. 

While Xofluza didn’t work faster than Tamiflu, it did reduce the level of the virus in patients’ nose and throat quicker. 

The new study showed that the newer treatment limited the amount of time a person was sick by quickly stopping the virus from replicating and spreading throughout the body. 

‘We found that treating even 10 percent of infected patients with baloxavir shortly after the onset of their symptoms can indirectly prevent millions of infections and save thousands of lives during a typical influenza season,’ said Dr Robert Krug, a professor emeritus of molecular biosciences, in a blog that accompanied the paper.  

Krug and his team say that a similar antiviral treatment would help to prevent thousands of infections and deaths from the coronavirus    

‘Imagine a drug that quashes viral load within a day and thus radically shortens the contagious period,’ said Dr Lauren Ancel Meyers, a professor of integrative biology.

‘Basically, we could isolate COVID-19 cases pharmaceutically rather than physically and disrupt chains of transmission.’

Most drugs being researched to treat COVID-19 have focused on existing antivirals that can be given to critically ill patient.

But the team says research should shift towards developing a new antiviral for the coronavirus that is used early on in infection and stops the virus from replicating,  , just as baloxavir does for the flu.

‘It may seem counterintuitive to focus on treatments, not for the critically ill patient in need of a life-saving intervention, but rather for the seemingly healthy patient shortly after a COVID-19 positive test,’ Krug said. 

‘Nonetheless, our analysis shows that the right early-stage antiviral treatment can block transmission to others and, in the long run, may well save more lives.’

In the US, there were more than 1.8 million confirmed cases of the virus and more than 105,000 deaths.

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We may be able to eliminate coronavirus, but we’ll probably never eradicate it. Here’s the difference

Compared to many other countries around the world, Australia and New Zealand have done an exceptional job controlling COVID-19.

As of May 7, there were 794 active cases of COVID-19 in Australia. Only 62 were in hospital.

The situation in New Zealand is similar, with 136 active cases, only two of whom are in hospital.

If we continue on this path, could we eliminate COVID-19 from Australia and New Zealand?

Control –> elimination –> eradication

In order to answer this question, we first to need to understand what elimination means in the context of disease, and how it differs from control and eradication.

Disease control is when we see a reduction in disease incidence and prevalence (new cases and current cases) as a result of public health measures. The reduction does not mean to zero cases, but rather to an acceptable level.

Unfortunately, there’s no consensus on what is acceptable. It can differ from disease to disease and from jurisdiction to jurisdiction.

As an example, there were only 81 cases of measles reported in Australia in 2017. Measles is considered under control in Australia.

Conversely, measles is not regarded as controlled in New Zealand, where there was an outbreak in 2019. From January 1, 2019, to February 21, 2020, New Zealand recorded 2,194 measles cases.

For disease elimination, there must be zero new cases of the disease in a defined geographic area. There is no defined time period this needs to be sustained for—it usually depends on the incubation period of the disease (the time between being exposed to the virus and the onset of symptoms).

For example, the South Australian government is looking for 28 days of no new coronavirus cases (twice the incubation period of COVID-19) before they will consider it eliminated.

Even when a disease has been eliminated, we continue intervention measures such as border controls and surveillance testing to ensure it doesn’t come back.

For example, in Australia, we have successfully eliminated rubella (German measles). But we maintain an immunization schedule and disease surveillance program.

Finally, disease eradication is when there is zero incidence worldwide of a disease following deliberate efforts to get rid of it. In this scenario, we no longer need intervention measures.

Only two infectious diseases have been declared eradicated by the World Health Organisation – smallpox in 1980 and rinderpest (a disease in cattle caused by the paramyxovirus) in 2011.

Polio is close to eradication with only 539 cases reported worldwide in 2019.

Guinea worm disease is also close with a total of just 19 human cases from January to June 2019 across two African countries.

What stage are we at with COVID-19?

In Australia and New Zealand we currently have COVID-19 under control.

Importantly, in Australia, the effective reproduction number (Reff) is close to zero. Estimates of Reff come from mathematical modelling, which has not been published for New Zealand, but the Reff is likely to be close to zero in New Zealand too.

The Reff is the average number of people each infected person infects. So a Reff of 2 means on average, each person with COVID-19 infects two others.

If the Reff is greater than 1 the epidemic continues; if the Reff is equal to 1 it becomes endemic (that is, it grumbles along on a permanent basis); and if the Reff is lower than 1, the epidemic dies out.

So we could be on the way to elimination.

In both Australia and New Zealand we have found almost all of the imported cases, quarantined them, and undertaken contact tracing. Based on extensive community testing, there also appear to be very few community-acquired cases.

The next step in both countries will be sentinel surveillance, where random testing is carried out in selected groups. Hopefully in time these results will be able to show us COVID-19 has been eliminated.

It’s unlikely COVID-19 will ever be eradicated

To be eradicated, a disease needs to be both preventable and treatable. At the moment, we neither have anything to prevent COVID-19 (such as a vaccine) nor any proven treatments (such as antivirals).

Even if a vaccine does become available, SARS-CoV-2 (the virus that causes COVID-19) easily mutates. So we would be in a situation like we are with influenza, where we need annual vaccinations targeting the circulating strains.

The other factor making COVID-19 very difficult if not impossible to eradicate is the fact many infected people have few or no symptoms, and people could still be infectious even with no symptoms. This makes case detection very difficult.

At least with smallpox, it was easy to see whether someone was infected, as their body was covered in pustules (fluid-containing swellings).

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