Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers Find Smallest Cellular Genome

13.10.2006
The smallest collection of genes ever found for a cellular organism comes from tiny symbiotic bacteria that live inside special cells inside a small insect.

The bacteria Carsonella ruddii has the fewest genes of any cell. The bacteria's newly sequenced genome, the complete set of DNA for the organism, is only one-third the size of the previously reported "smallest" cellular genome.

"It's the smallest genome -- not by a bit but by a long way," said co-author Nancy A. Moran, UA Regents' Professor of ecology and evolutionary biology and a member of the National Academy of Sciences. "It's very surprising. It's unbelievable, really. We would not have predicted such a small size. It's believed that more genes are required for a cell to work."

Carsonella ruddii has only 159,662 base-pairs of DNA, which translates to only 182 protein-coding genes, reports a team of scientists from The University of Arizona in Tucson and from Japan.

... more about:
»DNA »Evolution »Moran »endosymbiont

The finding provides new insights into bacterial evolution, the scientists write in the Oct. 13 issue of the journal Science.

Atsushi Nakabachi, a postdoctoral research associate in UA's department of ecology and evolutionary biology and a visiting scientist at RIKEN in Wako, Japan, is the first author on the research report, "The 160-kilobase genome of the bacterial endosymbiont Carsonella." The research was conducted in senior author Masahira Hattori's laboratory in Japan and in Moran's lab at the UA.

A complete list of authors is at the bottom of this release. The Ministry of Education, Culture, Sports, Science and Technology of Japan funded the work.

Many insects feed on plant sap, a nutrient-poor diet. To get a balanced diet, some sap-feeders rely on resident bacteria. The bacteria manufacture essential nutrients, particularly amino acids, and share the goodies with their hosts.

In many such associations, the bacteria live within the insect's cells and cannot survive on their own. Often the insect host cannot survive without its bacteria, known as endosymbionts.

The relationship between some insects and their endosymbionts is so close and so ancient that the insects house their resident bacteria in special cells called bacteriocytes within specialized structures called bacteriomes.

Studying the genomes of such endosymbionts can provide clues to how microorganisms' metabolic capabilities contribute to both their hosts and to biological communities.

An organism's genome, its complete complement of DNA, provides the operating instructions for everything the organism needs to do to survive and reproduce.

Endosymbiotic bacteria live in an extremely sheltered world and have a pared-down lifestyle, so they need a simpler set of instructions. Many of the metabolic pathways that free-living bacteria maintain have been lost after so many generations of living within insects.

Nakabachi and Hattori were interested in sequencing the genome of the bacteria Carsonella.

Moran had done some previous work on the Carsonella genome and found its DNA composition and evolution to be unusual. She suggested the team pursue the Carsonella that lived inside an Arizona psyllid insect called Pachypsylla venusta. The insect has only one species of endosymbiotic bacteria, which would simplify the genomic analysis.

The researchers collected Pachypsylla venusta psyllids from hackberry trees on the UA campus and around Tucson. The team extracted the Carsonella DNA and sequenced it.

Even though endosymbionts need fewer operating instructions to survive, the bacteria's itsy bitsy genome was a surprise.

"It lost genes that are considered absolutely necessary. Trying to explain it will probably help reveal how cells can work," said Moran, who is a member of UA's BIO5 Institute.

The scientists speculate that in the bacteria's evolutionary past, some of its genes were transferred into the insect's genome, allowing the insect to make some of the metabolites the bacteria needed. Once the insect shouldered those responsibilities and provided the bacteria with those metabolites, the bacteria lost those genes.

Animal and plant cells have specialized structures inside them called organelles that are derived from symbiotic bacteria that became incorporated into the cell over the course of evolution.

Carsonella's stripped-down genome may indicate that it is on its way to becoming an organelle, the researchers write in their article.

Authors on the paper are:

Atsushi Nakabachi of the UA and RIKEN; Helen E. Dunbar and Nancy A. Moran of the UA; Atsushi Yamashita and Hidehiro Toh of Kitasato University in Sagamihara, Japan; Hajime Ishikawa of The University of the Air in Mihama, Japan; and Masahira Hattori of The University of Tokyo in Kashiwa, Japan and RIKEN Genomic Sciences Center in Yokohama, Japan.

Mari N. Jensen | University of Arizona
Further information:
http://www.arizona.edu
http://genome.ls.kitasato-u.ac.jp/
http://www.bio5.org/

Further reports about: DNA Evolution Moran endosymbiont

More articles from Life Sciences:

nachricht Nanobot pumps destroy nerve agents
21.08.2018 | American Chemical Society

nachricht How do muscles know what time it is?
21.08.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

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

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

21.08.2018 | Medical Engineering

Researchers discover link between magnetic field strength and temperature

21.08.2018 | Physics and Astronomy

IHP technology ready for space flights

21.08.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>