Live-action films of worm sperm contain clues to male fertility

November 11, 2011
Fluorescent images of C. elegans sperm. Shown in red are GSP-3/4, phosphatases required for fertility, white are Membranous Organelles, and green is Major Sperm Protein, a C. elegans protein important for motility. GSP-3/4 is shown to be an important regulator of MSP in the Wu et al paper. Photo credit: Jui-ching Wu and Diana Chu

(Medical Xpress) -- Mouse sperm propel themselves with a whip-like molecular tail that lashes back and forth. Sperm in the roundworm Caenorhabditis elegans crawl along using a flat, fibrous foot called a pseudopod. They couldn’t be more different, and yet they depend on the same enzymes to help them develop and move about, according to a new study by SF State researchers.

The startling discovery could guide scientists in new directions as they explore how the DNA is organized in , and packaged properly to deliver to the embryo, said Diana Chu, an associate professor of biology.

Researchers have identified similar enzymes in human sperm, Chu said, although it is not yet clear what role they might play in human fertility.

Chu and her colleagues observed the enzymes -- called PP1 phosphatases -- in live worm sperm with the help of a powerful confocal microscope. Mini-movies of the enzymes at work showed that they were necessary for separating chromosomes during sperm cell division—a role they also play in mouse sperm cell division.

Then things started to get a little strange in the lab. The researchers discovered that worm sperm that lacked the enzymes were stuck in place, unable to move around on their pseudopods. Mice sperm without the enzymes are similarly immobile, even though they have a tail-like flagellum instead of a flat foot. “It’s a very similar thing even though the sperm look really different,” Chu said.

Could the same enzymes be connected to such different ways to get around? Susan Mirsoian and Aiza Go, graduate students in Chu’s lab, kept seeing the enzymes collect after cell division “in a crescent-shaped pattern where the pseudopods would be,” Chu recalled, but it seemed so unlikely that Chu had Mirsoian and Go repeat the experiments to be sure that the result was not a mistake.

Micrograph of a C. elegans ameoboid sperm. Photo credit: Aiza Go and Diana Chu

Persistent experiments confirmed the enzymes’ important role in worm sperm movement. Pseudopods move the sperm through a “treadmilling” motion, and the SF State researchers now say that the enzymes help to disassemble and reassemble the pseudopod’s molecular skeleton in a way that pushes the treadmill forward.

Even stranger, Chu and her colleagues found, the phosphatases in worms and mice seem to have evolved independently in each species. This suggests that they act similarly because they solve a similar adaptive “problem,” rather than acting similarly because they share an evolutionary ancestor.

Compared to most other cells in an organism, sperm undergo a radical transformation to become compact and mobile delivery systems for paternal DNA. The DNA is squeezed together so tightly that it is closed off to the molecular machinery that would normally transcribe new genes and translate them into new proteins.

Without new proteins to control sperm development, Chu explained, the phosphatases fill in as “post-translational machinery that acts as an on/off switch” for controlling key events such as chromosome segregation and sperm motility.

The study suggests these fertility regulators don’t have to be evolutionarily conserved to be important.

SF State co-authors on the paper, published online in the journal Genetics, include Jui-ching Wu, Mark Samson, Thais Cintra, Tammy Wu, Margaret Jow and Eric Routman.

Explore further: Live-action films of worm sperm help researchers track critical fertility enzymes

Related Stories

Live-action films of worm sperm help researchers track critical fertility enzymes

November 1, 2011
Compared to most other cells in an organism, sperm undergo a radical transformation to become compact and mobile delivery systems for paternal DNA. Even though sperm looks and moves quite differently across species, SF State ...

The long and short of sperm tails

August 5, 2011
A team of biologists in Japan has uncovered an unexpected role for mitochondria1, the power houses of cells, in the development of sperm in the fruit fly Drosophila melanogaster.

Crickets show path to chirpier sperm

July 18, 2011
New research suggests that men are what they eat, at least when it comes to reproductive health.

Recommended for you

The 16 genetic markers that can cut a life story short

July 27, 2017
The answer to how long each of us will live is partly encoded in our genome. Researchers have identified 16 genetic markers associated with a decreased lifespan, including 14 new to science. This is the largest set of markers ...

A rogue gene is causing seizures in babies—here's how scientists wants to stop it

July 26, 2017
Two rare diseases caused by a malfunctioning gene that triggers seizures or involuntary movements in children as early as a few days old have left scientists searching for answers and better treatment options.

Scientists provide insight into genetic basis of neuropsychiatric disorders

July 21, 2017
A study by scientists at the Children's Medical Center Research Institute at UT Southwestern (CRI) is providing insight into the genetic basis of neuropsychiatric disorders. In this research, the first mouse model of a mutation ...

Scientists identify new way cells turn off genes

July 19, 2017
Cells have more than one trick up their sleeve for controlling certain genes that regulate fetal growth and development.

South Asian genomes could be boon for disease research, scientists say

July 18, 2017
The Indian subcontinent's massive population is nearing 1.5 billion according to recent accounts. But that population is far from monolithic; it's made up of nearly 5,000 well-defined sub-groups, making the region one of ...

Mutant yeast reveals details of the aberrant genomic machinery of children's high-grade gliomas

July 18, 2017
St. Jude Children's Research Hospital biologists have used engineered yeast cells to discover how a mutation that is frequently found in pediatric brain tumor high-grade glioma triggers a cascade of genomic malfunctions.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.