(Press-News.org) Mealybugs only eat plant sap, but sap doesn't contain all the essential amino acids the insects need to survive. Luckily, the bugs have a symbiotic relationship with two species of bacteria – one living inside the other in a situation unique to known biology – to manufacture the nutrients sap doesn't provide.
The net result: The bacteria get a comfy mealybug home, and the bugs get the nutrition they need to live.
University of Montana microbiologist John McCutcheon describes such mutually beneficial relationships used to solve life's little problems as "almost hilariously complicated. But animal-bacterial relationships are extremely common in nature, and it's my goal in life to help people understand that it's normal."
McCutcheon and his research partners recently delved deeper into the genes involved in the "tripartite nested mealybug symbiosis," and their work was published in the June 20 issue of Cell, a prestigious scientific journal. The researchers discovered the already complex three-way symbiosis actually depends on genes from six different organisms – three more than the number of species that currently exist in the symbiosis.
Tremblaya princeps is the larger of the two bacteria species living within special organs inside mealybugs. Tremblaya houses the smaller bacterial species, Moranella endobia, within its cytoplasm. But what makes Tremblaya truly odd is the size of its genome, or genetic code. With only 120 genes, its genome is the smallest known and smaller than many scientists consider necessary for life. By comparison, common E. coli bacteria have about 4,200 genes and humans have about 21,000.
"We wanted to discover how this genome got so small," McCutcheon said. "We suspected Tremblaya's genome may have gotten smaller by transferring genes to the host animal, which is called horizontal transfer."
The researchers looked for genes in the mealybug genome that resemble bacteria genes. However, after extensive analysis they only found one weak possibility for horizontal transfer from Tremblaya.
"Our hypothesis that Tremblaya was transferring genes to the host was dead wrong," said McCutcheon. They did, however, find 22 other bacterial genes mixed in with the mealybug code – genes that seem to support activities missing in Tremblaya, Moranella and the mealybug.
How can this be?
"The genes are probably from historical bacterial infections," McCutcheon said. "These bacteria are no longer present in the mealybugs we work with, but their horizontally transferred genes are, and these genes allow the symbiosis to work."
The research team also examined a strain of Tremblaya that doesn't have Moranella living inside it. This variety employs about 50 more genes than the one containing Moranella, which strongly suggests Moranella plays a key role in allowing the insect-dwelling Tremblaya to operate with such a tiny genome.
McCutcheon said Tremblaya, with its shrinking genome, in many ways resembles organelles called mitochondria – tiny structures found within all plant and animal cells that scientists believe started out as symbiotic bacteria in the early history of life. The mealybug/bacteria relationship he studies may illustrate one pathway bacteria take in becoming essential and highly integrated components of other cells.
"So this research really touches on some fundamental questions of the origin of life," he said. "It's exciting to see if we can get some insight into the origin of organelles."
McCutcheon said this study involved an international cast of 12 collaborators. Filip Husnik, the study's lead author, is a Czech doctoral student from the University of South Bohemia who worked in McCutcheon's UM lab. Other team members were from Japan, England, California, Utah and Florida.
The study was funded by a $529,000 grant from the National Science Foundation.
"Our work illustrates how an animal's interactions with bacteria can drive hidden organismal complexity," McCutcheon said. "A tree is more than a tree, and an animal is more than an animal. They are really mosaics of plants and animals and bacteria all working together."
INFORMATION:
Study of insect bacteria reveals genetic secrets of symbiosis
2013-06-21
ELSE PRESS RELEASES FROM THIS DATE:
Researchers discover how a mutated protein outwits evolution and fuels leukemia
2013-06-21
Scientists have discovered the survival secret to a genetic mutation that stokes leukemia cells, solving an evolutionary riddle and paving the way to a highly targeted therapy for leukemia. In a paper published today in Cell, researchers at NYU Langone Medical Center describe how a mutated protein, called Fbxw7, behaves differently when expressed in cancer cells versus healthy cells. "Fbxw7 is essential for making blood cells, so the big mystery is why a mutation on a gene so important for survival would persist," says lead author Iannis Aifantis, PhD, chair of pathology ...
High rates of burnout and depression among anesthesia residents
2013-06-21
San Francisco, CA. (June 20, 2013) – Residents in anesthesiology training programs have high rates of burnout and depression, reports a survey study in the July issue of Anesthesia & Analgesia, official journal of the International Anesthesia Research Society (IARS).
The findings raise concerns that, "In addition to effects on the health of anesthesiology trainees, burnout and depression may also affect patient care and safety," write Dr Gildasio S. de Oliveira, Jr, and colleagues of Northwestern University, Chicago.
Burnout and Depression Are Common in Anesthesia Trainees…
The ...
Reports of retained guidewires draw attention to 'never events' in anesthesia
2013-06-21
San Francisco, CA. (June 20, 2013) – Retention of guidewires used to place central venous catheters (CVCs) is a complication that is considered always preventable—but nevertheless still happens, according to a report in the July issue of Anesthesia & Analgesia, official journal of the International Anesthesia Research Society (IARS).
Dr Andrea Vannucci and colleagues report their hospital's experience of four patients with retained guidewires, and analyze risk factors for these rare, preventable medical errors. A pair of accompanying editorials support the need for more ...
Most unscheduled hospital admissions now come through the ER
2013-06-21
WASHINGTON —More than three-quarters (81.8 percent) of unscheduled admissions to the hospital now come through the emergency department, which is a sharp increase from the previous decade when only 64.5 percent of unscheduled admissions came through the ER. A study, published early online this week in the journal Medical Care, re-confirms recent findings by the RAND Corporation highlighting the growing role emergency physicians play in health care beyond the emergency department ("Changes in the Source of Unscheduled Hospitalizations in the United States").
"Although ...
Solar splashdown
2013-06-21
VIDEO:
This time-lapse movie shows a solar eruption that happened on June 7, 2011. At lower right, material blasts outward from the sun and then splashes down again, creating dramatic flashes...
Click here for more information.
On June 7, 2011, our Sun erupted, blasting tons of hot plasma into space. Some of that plasma splashed back down onto the Sun's surface, sparking bright flashes of ultraviolet light. This dramatic event may provide new insights into how young stars ...
How did a third radiation belt appear in the Earth's upper atmosphere?
2013-06-21
Since the discovery of the Van Allen radiation belts in in the Earth's upper atmosphere in 1958, space scientists have believed that these belts consisted of two doughnut-shaped rings of highly charged particles — an inner ring of high-energy electrons and energetic positive ions, and an outer ring of high-energy electrons.
However, in February of this year, a team of scientists reported in the journal Science the surprising discovery of a previously unknown third radiation ring. This narrow ring had briefly circled the Earth between the inner and outer rings in September ...
Researchers determine factors that influence spinach contamination pre-harvest
2013-06-21
A team of researchers from Texas and Colorado has identified a variety of factors that influence the likelihood of E. coli contamination of spinach on farms prior to harvest. Their research is published in the July 2013 issue of the journal Applied and Environmental Microbiology.
"Microbial contamination of produce seems strongly influenced by the time since the last irrigation, the workers' personal hygiene and the field's use prior to planting of produce," says first author Sangshin Park of Texas A&M University, College Station. "These factors, together with the role ...
Student engagement more complex, changeable than thought
2013-06-21
"Enhancing student engagement has been identified as the key to addressing problems of low achievement, high levels of student misbehavior, alienation, and high dropout rates." – Pitt professor Ming-Te Wang
PITTSBURGH—A student who shows up on time for school and listens respectfully in class might appear fully engaged to outside observers, including teachers. But other measures of student engagement, including the student's emotional and cognitive involvement with the course material, may tell a different story—one that could help teachers recognize students who are ...
Bacterial DNA may integrate into human genome more readily in tumor tissue
2013-06-21
Bacterial DNA may integrate into the human genome more readily in tumors than in normal human tissue, according to a new study from the University of Maryland School of Medicine's Institute for Genome Sciences. Researchers analyzed genomic sequencing data available from the Human Genome Project, the 1,000 Genomes Project and The Cancer Genome Atlas (TCGA). They considered the phenomenon of lateral gene transfer (LGT), the transmission of genetic material between organisms in the absence of sex.
Scientists have already shown that bacteria can transfer DNA to the genome ...
Light and nanoprobes detect early signs of infection
2013-06-21
DURHAM, N.C. -- Duke University biomedical engineers and genome researchers have developed a proof-of-principle approach using light to detect infections before patients show symptoms.
The approach was demonstrated in human samples, and researchers are now developing the technique for placement on a chip, which could provide fast, simple and reliable information about a patient. A diagnostic device based on this chip also could be made portable.
The researchers developed a silver-based nanoparticle that homes in on a specific molecular marker that spills into the bloodstream ...