Science Current Events | Science News | Brightsurf.com
 

Researchers discover how malaria parasite disperses from red blood cells

September 20, 2005
Researchers at the National Institute of Child Health and Human Development have determined the sequence in which the malaria parasite disperses from the red blood cells it infects. The National Institute of Child Health and Human Development is one of the Institutes comprising the National Institutes of Health.

The study appears in the September 20 Current Biology.

"This discovery provides the groundwork for possible new approaches to treating malaria, " said Duane Alexander, M.D., Director of the NICHD. "The malaria parasite is growing resistant to the drugs used to treat it, and new knowledge is essential for developing strategies to protect against the disease."

The study supplants earlier theories on how the malaria parasite spreads from the red blood cells it infects.

According to the World Health Organization, malaria kills more than 1 million people a year. (The WHO fact sheet, "What is Malaria?" is available on the organization's Web site at http://mosquito.who.int/cmc_upload/0/000/015/372/RBMInfosheet_1.htm )

Malaria is caused by four species of the parasite Plasmodium, the most common and deadly of which is Plasmodium falciparum. P. falciparum spends part of its life cycle in the salivary glands of mosquitoes and is transmitted to human beings through the bite of infected mosquitoes. The parasite infects red blood cells. Called a merozoite at the stage of its life when it infects red blood cells, the parasite multiplies inside the cell, until the cell ruptures and releases them. The newly released merozoites infect still other cells, and the process begins again.

To conduct the study, the researchers stained red blood cells infected with P. falciparum with two kinds of dye, explained the study's senior author, Joshua Zimmerberg, M.D., Ph.D., Chief of NICHD's Laboratory of Cellular and Molecular Biophysics. One dye stained the blood cells green, the other stained the parasites red.

In the first stage of the merozoites' release, which the researchers dubbed the "irregular schizont" stage, the red blood cell resembles a lop-sided fried egg, with the parasites visible as a sphere near the center of the cell. (A diagram of the entire sequence appears at http://www.nichd.nih.gov/new/releases/malaria_graphic.cfm ) The cell's lop-sided appearance probably results from destruction of the cytoskeleton, the molecular scaffolding that helps the cell to maintain its rounded shape.

In the next stage, called the "flower" stage, the red blood cell assumes a roughly spherical shape, covered with rounded structures that resemble the petals of a flower. Shortly thereafter, the blood cell's membrane appears to break apart. At roughly the same time, cellular compartments, called vacuoles, which encase the newly formed merozoites, also break apart. The entire process has an explosive appearance, dispersing the merozoites some distance from the cell.

During the release, Dr. Zimmerberg explained, the cell membrane appears to collapse inward upon itself and fragment into pieces.

One previous theory held that the red blood cells and the merozoite-containing vacuoles inside them swelled and then burst like a balloon containing too much air.

"The swelling was an artifact of too much light from the microscope," Dr. Zimmerberg said. "The cell membrane was light sensitive. When we turned the light down, we didn't see the swelling." Rather, he said, upon release of the merozoites, the cell membrane appeared to contract in upon itself.

Another theory held that the merozoite-containing vacuoles would fuse with the cell membrane, and then release their contents.

"But we didn't see any fusion," Dr. Zimmerberg said.

The third theory held that the cell membrane ruptured, expelling merozoite-containing vacuoles. Again, however, the researchers observed that this theory also offered an inaccurate picture, as the vacuoles ruptured at roughly the same time as the cell membrane.

Each step in the release process is a potential avenue for new therapies to treat the disease, Dr. Zimmerberg said. By first understanding how the parasite brings about these steps, it may be possible to find ways to prevent them from occurring.

NIH/National Institute of Child Health and Human D


Related Malaria Parasite Current Events and Malaria Parasite News Articles


Weakness in malaria parasite fats could see new treatments
A new study has revealed a weak spot in the complex life cycle of malaria, which could be exploited to prevent the spread of the deadly disease.

New discovery could help turn antibiotic into antimalarial drug
Melbourne researchers are making progress towards new antimalarial drugs, after revealing how an antibiotic called emetine blocks the molecular machinery that produces the proteins required for malaria parasite survival.

New insights into the survival and transmission strategy of malaria parasites
HP1 proteins are found in most eukaryotic organisms and are important regulators of gene silencing. In short, HP1 induces heritable condensation of chromosomal regions.

Native bacteria block Wolbachia from being passed to mosquito progeny
Native bacteria living inside mosquitoes prevent the insects from passing Wolbachia bacteria -- which can make the mosquitoes resistant to the malaria parasite -- to their offspring, according to a team of researchers.

A vaccine alternative protects mice against malaria
A study led by Johns Hopkins Bloomberg School of Public Health researchers found that injecting a vaccine-like compound into mice was effective in protecting them from malaria.

An easier way to manipulate malaria genes
Plasmodium falciparum, the parasite that causes malaria, has proven notoriously resistant to scientists' efforts to study its genetics. It can take up to a year to determine the function of a single gene, which has slowed efforts to develop new, more targeted drugs and vaccines.

Drug-resistant malaria has spread to critical border regions of Southeast Asia
Drug-resistant malaria parasites have spread to critical border regions of Southeast Asia, seriously threatening global malaria control and elimination programmes, according to a study published in the New England Journal of Medicine.

New malaria vaccine candidates identified
Researchers have discovered new vaccine targets that could help in the battle against malaria.

One route to malaria drug resistance found
Researchers have uncovered a way the malaria parasite becomes resistant to an investigational drug.

Anti-tank missile detector joins the fight against malaria
State-of-the-art military hardware could soon fight malaria, one of the most deadly diseases on the planet.
More Malaria Parasite Current Events and Malaria Parasite News Articles

The Malaria Capers: Tales of Parasites and People

The Malaria Capers: Tales of Parasites and People
by Robert S. Desowitz (Author)


"Reads like a murder mystery. . . . [Desowitz] writes with uncommon lucidity and verse, leaving the reader with a vivid understanding of malaria and other tropical diseases, and the ways in which culture, climate and politics have affected their spread and containment."—New York Times Why, Robert S. Desowitz asks, has biotechnical research on malaria produced so little when it had promised so much? An expert in tropical diseases, Desowtiz searches for answers in this provocative book.

Malaria Parasites: Comparative Genomics, Evolution and Molecular Biology

Malaria Parasites: Comparative Genomics, Evolution and Molecular Biology
by Jane M Carlton (Editor), Susan L Perkins (Editor), Kirk W Deitsch (Editor)


Since the publication of the first two Plasmodium genome sequences in 2002, numerous other parasite genomes have been sequenced. These include the genomes of several more Plasmodium species, as well as those of other apicomplexans, including species of Toxoplasma, Cryptosporidium, Babesia, and Eimeria. This wealth of genome sequence data has provided researchers with a powerful new tool, comparative genomics, which has revolutionized research in this area. In this book, expert contributors from around the world comprehensively review the current advances in Plasmodium comparative genomics, highlighting the fascinating new insights into parasite evolution and molecular biology that have ensued. Topics include: Plasmodium taxonomy and phylogeny * the apicomplexan genomic landscape * the...

Malaria Parasite Biology, Pathogenesis, and Protection

Malaria Parasite Biology, Pathogenesis, and Protection
by Irwin W. Sherman (Editor)




The Malaria Parasite (Parasites)

The Malaria Parasite (Parasites)
by Sheila Wyborny (Author)


Malaria is a serious disease caused by a tiny mosquito-borne parasite called Plasmodium. It once affected entire empires, but thanks to the work of health organizations, malaria is now mostly confined to warm, moist climates. Scientists are still at work today, however, developing methods of curing the disease and destroying its carriers.

Malaria in Pregnancy: Deadly Parasite, Susceptible Host

Malaria in Pregnancy: Deadly Parasite, Susceptible Host
by Patrick E. Duffy (Editor), Michael Fried (Editor)


Malaria in pregnancy has been a long-standing conundrum - why do women immune to the parasite after years of exposure suddenly become susceptible to infection during first pregnancies? Recent scientific breakthroughs have shed new light on interactions between the malaria parasite and the placenta, and raised hope for new drugs and vaccines to protect young mothers.
The current understanding of malaria in pregnancy and the continued controversies surrounding this syndrome will fascinate all students, scientists and policy-makers interested in infectious disease and women's health.

Parasites on Parade: Edition 2

Parasites on Parade: Edition 2
by Dr. Stan Eisen (Author)


Parasites on Parade is a survey of parasitic organisms, most of which are of medical or veterinary importance. Details of the life cycle, pathology, intermediate hosts, and treatment are included for each parasite. This edition differs from Edition 1 in that it has color photomicrographs taken by the author.

The Fever: How Malaria Has Ruled Humankind for 500,000 Years

The Fever: How Malaria Has Ruled Humankind for 500,000 Years
by Sonia Shah (Author)


In recent years, malaria has emerged as a cause célèbre for voguish philanthropists. Bill Gates, Bono, and Laura Bush are only a few of the personalities who have lent their names—and opened their pocketbooks—in hopes of curing the disease. Still, in a time when every emergent disease inspires waves of panic, why aren’t we doing more to eradicate one of our oldest foes? And how does a parasitic disease that we’ve known how to prevent for more than a century still infect 500 million people every year, killing nearly 1 million of them?

In The Fever, the journalist Sonia Shah sets out to answer these questions, delivering a timely, inquisitive chronicle of the illness and its influence on human lives. Through the centuries, she finds, we’ve invested our hopes in a panoply...

Malaria: Methods and Protocols (Methods in Molecular Biology)

Malaria: Methods and Protocols (Methods in Molecular Biology)
by Robert Ménard (Editor)


Over the past ten years, many powerful new techniques have been developed that have dramatically changed malaria research. The second edition of  Malaria: Methods and Protocols expands upon the previous edition with current, detailed techniques for laboratory research. With new chapters on parasite culture techniques, genome manipulation methods, 'omic' approaches, and  techniques for studying the biology of the red blood cell and pre-erythrocytic stages of Plasmodium. Written in the highly successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls.  Authoritative and...

The Making of a Tropical Disease: A Short History of Malaria (Johns Hopkins Biographies of Disease)

The Making of a Tropical Disease: A Short History of Malaria (Johns Hopkins Biographies of Disease)
by Randall M. Packard (Author)


Malaria sickens hundreds of millions of people—and kills one to three million—each year. Despite massive efforts to eradicate the disease, it remains a major public health problem in poorer tropical regions. But malaria has not always been concentrated in tropical areas. How did other regions control malaria and why does the disease still flourish in some parts of the globe?From Russia to Bengal to Palm Beach, Randall Packard’s far-ranging narrative traces the natural and social forces that help malaria spread and make it deadly. He finds that war, land development, crumbling health systems, and globalization—coupled with climate change and changes in the distribution and flow of water—create conditions in which malaria's carrier mosquitoes thrive. The combination of these...

CURRENT Medical Diagnosis and Treatment 2015

CURRENT Medical Diagnosis and Treatment 2015
by Maxine Papadakis (Author), Stephen J. McPhee (Author), Michael W. Rabow (Author)


To deliver the best care to your patients, turn to the #1 annually updated guide in internal medicine and clinical practice. The 2015 Edition is packed with important NEW information! NEW TO THIS EDITION: Latest 2014 American Heart Association/American College of Cardiology guidelines for anticoagulation in atrial fibrillation, and indications for interventions in valvular heart disease Update on the epidemic of opioid-based prescription drug abuse, misuse and overdose, and new section on opioids for chronic, noncancer pain Revised treatment options for Helicobacter pylori and chronic hepatitis C Latest hypertension information from 2013 UK National Institute of Health and Clinical Excellence and US Joint National Committee (JNC8) Reports Discussion of which patients benefit from...

© 2014 BrightSurf.com