Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

How Volvox Got Its Groove

20.02.2009
Some algae have been hanging together rather than going it alone much longer than previously thought, according to new research.

Ancestors of Volvox algae made the transition from being a single-celled organism to becoming a multicellular colony at least 200 million years ago, during the Triassic Period.

At that time, Earth was a hot-house world whose inhabitants included tree ferns, dinosaurs and early mammals. Previous estimates had suggested Volvox's ancestors arose only 50 million years.

The algae switched to a communal lifestyle in only 35 million years -- "a geological eyeblink," said lead researcher Matthew D. Herron of The University of Arizona in Tucson.

Figuring out how algae made the leap can provide clues to how multicellular organisms such as plants and animals evolved from single cells.

Cooperating successfully is the key, Herron said.

"All the macroscopic organisms we see around us trace back to unicellular ancestors," said Herron, a doctoral candidate in the UA's department of ecology and evolutionary biology. "Each of those groups had to go through a transition like this one.

"We think the early changes in this process were related to cooperation among cells and conflicts among cells -- and finally to the resolution of those conflicts," he said.

The researchers used DNA sequences from about 45 different species of Volvox and related species to reconstruct the group's family tree and determine how long ago the first colonial ancestor arose.

The team's article "Triassic origin and early radiation of multicellular volvocine algae," is in this week's online Early Edition of the Proceedings of the National Academy of Sciences.

Herron's co-authors Jeremiah D. Hackett and Richard E. Michod are members of the UA's department of ecology and evolutionary biology. Co-author Frank O.

Aylward was at the UA when the research was conducted and is now at the University of Wisconsin in Madison. The Society of Systematic Biologists and Sigma Xi helped fund the research.

Volvox and its relatives live in freshwater ponds all over the world. Some of the species are unicellular, while others live in colonies of up to 50,000 cells.

Many of the colonial algae species are visible to the eye and appear to be little green spheres rolling through the water. The most complex species have a division of labor -- some cells do the swimming, others do the reproducing.

Although an earlier estimate suggested the algae's ancestors banded together 50 million years ago, Herron wanted to check the estimate using 21st-century genetic and molecular techniques.

In addition to constructing the Volvox family tree, the team determined how long ago the group's oldest common ancestor lived by comparing the amount of genetic differences between species.

One of the earliest traits to evolve is the clear jelly-like substance visible between the cells of the spherical Volvox colonies, Herron said. "We think that stuff is what held the earliest multicellular colonies together."

Banding together in a larger mass can provide protection from predators, he said. "Some things can't eat you if you're bigger."

But producing the goo, called extracellular matrix, takes resources and is one of the costs of cooperation.

"So now there's a temptation to cheat," Herron said. "Let's say I'm in a four-cell colony. I'm going to let the other three guys make the extracellular matrix, and I'm going to focus on growing and reproducing.

That's the conflict."

Overcoming that conflict is essential to becoming a multicellular organism, he said. The benefits of cheating have to be reduced for the cells to cooperate successfully.

Some traits the team studied are genetic traits that mediate conflict.

Genetic control of cell number is one of those, he said. "If my number of offspring is fixed at four, now there's no reason for me to cheat. I can't have eight offspring when everyone else is having only four."

Herron is now studying whether the size of the colony affects the degree to which there are different types of cells within the colony.

Researcher contact:
Matthew Herron
520-621-1844
mherron@email.arizona.edu
Related Web sites:
Matthew Herron
http://www.eebweb.arizona.edu/Grads/mherron/
UA Department of Ecology and Evolutionary Biology
http://eebweb.arizona.edu/

Mari N. Jensen | The University of Arizona
Further information:
http://www.arizona.edu
http://eebweb.arizona.edu/

More articles from Life Sciences:

nachricht Protein interaction helps Yersinia cause disease
21.08.2018 | Schwedischer Forschungsrat - The Swedish Research Council

nachricht Nanobot pumps destroy nerve agents
21.08.2018 | American Chemical Society

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: It’s All in the Mix: Jülich Researchers are Developing Fast-Charging Solid-State Batteries

There are currently great hopes for solid-state batteries. They contain no liquid parts that could leak or catch fire. For this reason, they do not require cooling and are considered to be much safer, more reliable, and longer lasting than traditional lithium-ion batteries. Jülich scientists have now introduced a new concept that allows currents up to ten times greater during charging and discharging than previously described in the literature. The improvement was achieved by a “clever” choice of materials with a focus on consistently good compatibility. All components were made from phosphate compounds, which are well matched both chemically and mechanically.

The low current is considered one of the biggest hurdles in the development of solid-state batteries. It is the reason why the batteries take a relatively long...

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

A paper battery powered by bacteria

21.08.2018 | Power and Electrical Engineering

Protein interaction helps Yersinia cause disease

21.08.2018 | Life Sciences

Biosensor allows real-time oxygen monitoring for 'organs-on-a-chip'

21.08.2018 | Medical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>