PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

Females supercharge sperm evolution in animals

2021-06-21
(Press-News.org) Sperm size varies dramatically among different animal species. But why is sperm size so variable when they share the same job - to fertilize eggs? In a new article published in Nature Ecology and Evolution, researchers from Stockholm University show that animal sperm evolution become supercharged only when sperm swim inside females.

Sperm are the most variable cell type known, ranging in size from 0.002 millimeters in a freshwater rotifer to nearly 6 centimeters in a fruit fly. Explaining why sperm are so variable has been a major focus in evolutionary biology over the last 100 years because sperm, no matter from what organism, always have the same function: to fertilize eggs.

"Researchers usually try to explain sperm diversity by focusing on how sperm compete to fertilize eggs or how females choose which sperm fertilize their eggs", says Ariel Kahrl, a researcher in the Department of Zoology at Stockholm University.

"But it turns out that there is a missing piece of the puzzle - the location where sperm and eggs meet can also influence sperm size".

To examine how the location of fertilization influences sperm evolution, the researchers compiled data on sperm size from more than 3,200 animal species - ranging from corals to mammals, including humans - and classified each species based on where sperm and eggs meet.

"In species with internal fertilization - like mammals, birds and insects - sperm fertilize eggs inside the female's body, while in species with external fertilization - like sea urchins and many fish species - sperm and eggs are released into the water and fertilization happens outside of the female's body", explains Ariel Kahrl.

The researchers found that sperm were on average six times longer and changed size more rapidly in animals that use internal fertilization compared to sperm from animals that use external fertilization.

"When sperm are released externally, selection keeps sperm size small to allow males to produce a lot of sperm", says Rhonda Snook, a professor in Zoology and an author of the paper. "But when sperm are transferred to the females in internal fertilizers, males may compete better with bigger sperm and females may prefer to fertilize eggs with bigger sperm".

The researchers also examined a third form of fertilization found in invertebrates called spermcasting, where sperm are released externally and then filtered out of the water by females where they then fertilize eggs inside the female.

"Spermcasting represents a mix of internal and external fertilizations, which gave us the opportunity to see what part of the fertilization process influenced sperm evolution", says John Fitzpatrick, an associate professor in Zoology at Stockholm University and the senior author of the study.

In spermcasters, the study found that sperm were small, like external fertilizers, but evolved rapidly, like internal fertilizers. "Our results clearly show that interactions between sperm and females help generate the tremendous diversity in sperm size we see in animals today. The greater the potential for interactions between sperm and females, the faster sperm evolve", says John Fitzpatrick.

Since humans are internal fertilizers, does this mean that men have supersized sperm? It turns out this isn't the case; human sperm are about the same size as animals that release their sperm into water.

"In animals with large bodies, like humans, sperm are diluted inside the female's reproductive tract. From the sperm perspective, it doesn't matter if dilution occurs inside a female or in the ocean - dilution keeps sperm small. It's only when sperm are confined in small spaces within the female that sperm become supersized", explains Ariel Kahrl.

More about the study The idea that fertilization environment influences how sperm size has been around for more than 60 years. But researchers haven't been able to test this idea throughout animal evolution. In the article, researchers from Stockholm University compiled the largest database on sperm morphology ever assembled and show that sperm size increases and changes rapidly when sperm operate inside the female's body.

INFORMATION:

Read more about the research of John Fitzpatrick: https://www.su.se/english/profiles/jfrit-1.253654

Publication: Find the publication "Fertilization mode drives sperm length evolution across the animal tree of life" in Nature Ecology and Evolution: Link DOI number https://doi.org/10.1038/s41559-021-01488-y

Contacts:

Dr Ariel Kahrl: Postdoctoral Researcher, Department of Zoology, Stockholm University, E-mail: ariel.kahrl@zoologi.su.se

Dr John Fitzpatrick: Wallenberg Academy Fellow, Associate Professor, Docent, Department of Zoology, Stockholm University. E-mail: john.fitzpatrick@zoologi.su.se. Mobile: +46 73 710 6359.

Prof. Rhonda Snook: Professor, Department of Zoology, Stockholm University, E-mail: rhonda.snook@zoologi.su.se

Media Contacts:

Press Office at Stockholm University
press@su.se
Tel: +46-(0)8-16 40 90?



ELSE PRESS RELEASES FROM THIS DATE:

Popular sepsis prediction tool less accurate than claimed

2021-06-21
One in three patients who dies in a hospital has sepsis, a severe inflammatory response to an infection, marked by organ dysfunction, according to the Centers for Disease Control and Prevention. This heavy toll makes predicting which patients are at risk for developing the devastating condition a top priority for clinicians. Additional motivation to identify and treat sepsis cases lies in the fact that sepsis serves as a system-level quality measure, with hospitals judged by both the by the federal Department of Health and Human Services and the CDC on their sepsis rates. Complicating efforts to reduce sepsis is how difficult it can be to diagnose--both accurately and quickly. "Sepsis is something we can ...

Virtual reality as pain relief: reducing dressing change pain in pediatric burn patients

2021-06-21
(COLUMBUS, Ohio) - According to the American Burn Association, burn injuries affect approximately 250,000 children in the United States each year. The pain associated with burn injuries extends beyond the injury itself; there is also significant pain from dressing changes, which can be exacerbated by the anxiety of anticipating this additional pain. Although opioids relieve burn injury-related pain, they have serious adverse side effects. Prior studies have investigated alternative approaches to pain reduction in burn injury patients that focus on distraction, such as music, hypnosis, toys, and virtual reality (VR). In a study published today in JAMA Network Open, Henry Xiang, MD, MPH, PhD, MBA, and his research team reported the ...

Preventive aspirin use in older US adults with, without diabetes

2021-06-21
What The Study Did: In the context of recently revised guidelines that discourage routine use of aspirin in adults 70 years and older, these findings suggest that older adults may have potential overuse of aspirin therapy if it is not actively discontinued, especially among those with diabetes. Authors: Rita R. Kalyani, M.D., of the Johns Hopkins University School of Medicine in Baltimore, is the corresponding author. To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/ (doi:10.1001/jamanetworkopen.2021.12210) Editor's Note: The article includes funding/support disclosures. Please see the article for additional information, including other authors, author ...

Experiences of family members of patients with severe COVID-19 who died in ICUs in France

2021-06-21
What The Study Did: This qualitative study reports that, in the midst of a major public health crisis, the erosion of family-centered care practices was associated with a dramatic impact on the experiences of family members of patients who died. Authors: Nancy Kentish-Barnes, Ph.D., of  Saint Louis University Hospital in Paris, France, is the corresponding author. To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/ (doi:10.1001/jamanetworkopen.2021.13355) Editor's Note: The article includes conflict of interest and funding/support disclosures. Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial ...

Association between race, COVID-19 outcomes among children in England

2021-06-21
What The Study Did: Results of this study suggest race-specific disparities in SARS-CoV-2 testing and COVID-19 hospital outcomes seen in adults also exist among children, after accounting for several clinical and sociodemographic factors thought to play a role in the disease. Authors: Defne Saatci, M.D., of the University of Oxford in the United Kingdom, is the corresponding author. To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/ (doi:10.1001/jamapediatrics.2021.1685) Editor's Note: The article includes conflict of interest and funding/support disclosures. Please see the article for additional information, including other authors, ...

Using birthdays to assess association between social gatherings, COVID-19 risk

2021-06-21
What The Study Did: Using administrative healthcare data on 2.9 million households, this study suggests that events that lead to small and informal social gatherings, such as birthdays, and in particular, children's birthdays, are a potentially important source in SARS-CoV-2 transmission. Authors: Anupam B. Jena, M.D., Ph.D., of Harvard Medical School in Boston, is the corresponding author. To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/ (doi:10.1001/jamainternmed.2021.2915) Editor's Note: The article includes conflict of interest and funding/support disclosures. Please ...

Association of changes in seasonal respiratory virus activity, antibiotic prescriptions with COVID-19 pandemic

2021-06-21
What The Study Did:  This study demonstrated a decrease in respiratory virus detections and a decline in antibiotic prescribing rates for respiratory tract infections during the COVID-19 pandemic. Authors: Alexander J. Lepak, M.D., of the University of Wisconsin School of Medicine and Public Health in Madison, is the corresponding author. To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/ (doi:10.1001/jamainternmed.2021.2363) Editor's Note: The article includes conflict of interest disclosures. Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and ...

Birthdays and COVID-19

2021-06-21
In counties with already high COVID-19 infection rates, birthday bashes may have fueled infection spread during the peak months of the pandemic, according to a new analysis led by researchers at Harvard Medical School and the RAND Corporation. The report, published June 21 in JAMA Internal Medicine, shows that in counties with high rates of COVID-19, households with recent birthdays were 30 percent more likely to have a COVID-19 diagnosis, compared with households with no birthdays. The analysis is based on data from health insurance claims. The researchers ...

Implantable brain device relieves pain in early study

2021-06-21
A computerized brain implant effectively relieves short-term and chronic pain in rodents, a new study finds. The experiments, conducted by investigators at NYU Grossman School of Medicine, offer what the researchers call a "blueprint" for the development of brain implants to treat pain syndromes and other brain-based disorders, such as anxiety, depression, and panic attacks. Publishing June 21 in the journal Nature Biomedical Engineering, the study showed that device-implanted rats withdrew their paws 40 percent more slowly from sudden pain compared with times when their device was turned off. According to the study authors, this suggests that the device reduced ...

Inkjet printing 'impossible materials'

Inkjet printing impossible materials
2021-06-21
Engineers at Tufts University have developed new methods to more efficiently fabricate materials that behave in unusual ways when interacting with microwave energy, with potential implications for telecommunications, GPS, radar, mobile devices, and medical devices. Known as metamaterials, they are sometimes referred to as "impossible materials" because they could, in theory, bend energy around objects to make them appear invisible, concentrate the transmission of energy into focused beams, or have chameleon like abilities to reconfigure their absorption or transmission of different frequency ranges. The innovation, described today in Nature Electronics, constructs the metamaterials using ...

LAST 30 PRESS RELEASES:

Heat and heavy metals are changing the way that bees buzz

What’s behind the enormous increase in early-onset gastrointestinal cancers?

Pharmacogenomics expert advances precision medicine for bipolar disorder

Brazilian researcher explores centenarian stem cells for aging insights

Dr. Xuyu Qian's breakthrough analysis of 18 million brain cells advances understanding of human brain development

Gene networks decode human brain architecture from health to glioma

How artificial light at night damages brain health and metabolism

For ultrasound, ultra-strength not always a good thing

Matching your workouts to your personality could make exercising more enjoyable and give you better results

Study shows people perceive biodiversity

Personality type can predict which forms of exercise people enjoy

People can accurately judge biodiversity through sight and sound

People diagnosed with dementia are living longer, global study shows

When domesticated rabbits go feral, new morphologies emerge

Rain events could cause major failure of Waikīkī storm drainage by 2050

Breakthrough in upconversion luminescence research: Uncovering the energy back transfer mechanism

Hidden role of 'cell protector' opens cancer treatment possibilities

How plants build the microbiome they need to survive in a tough environment

Depression due to politics and its quiet danger to democracy addressed in new book 'The Sad Citizen'

International experts and patients unite to help ensure all patients are fully informed before consenting to new surgical procedures

Melting glaciers could trigger more explosive eruptions globally, finds research

Nearly half of U.S. grandchildren live within 10 miles of a grandparent

Study demonstrates low-cost method to remove CO₂ from air using cold temperatures, common materials

Masonic Medical Research Institute (MMRI) welcomes 13 students to prestigious Summer Fellowship program

Mass timber could elevate hospital construction

A nuanced model of soil moisture illuminates plant behavior and climate patterns

$2.6 million NIH grant backs search for genetic cure in deadly heart disease

Pennsylvania’s medical cannabis program changed drastically when anxiety was added as a qualifying condition

1 in 5 overweight adults could be reclassified with obesity according to new framework

Findings of study on how illegally manufactured fentanyl enters U.S. contradict common assumptions, undermining efforts to control supply

[Press-News.org] Females supercharge sperm evolution in animals