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


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.

Malaria parasite manipulates host's scent
Malaria parasites alter the chemical odor signal of their hosts to attract mosquitos and better spread their offspring, according to researchers, who believe this scent change could be used as a diagnostic tool.

Genetic 'barcode' for malaria could help contain outbreaks
A new genetic 'barcode' for malaria parasites has been found which could be used to track and contain the spread of the disease, according to new research led by the London School of Hygiene & Tropical Medicine.

Scientists identify potential vaccine candidate for pediatric malaria
Researchers have identified a substance, or antigen, that generates antibodies that can hinder the ability of malaria parasites to multiply, which may protect against severe malaria infection.

Lethal parasite evolved from pond scum
A genomic investigation by University of British Columbia researchers has revealed that a lethal parasite infecting a wide range of insects actually originated from pond scum, but has completely shed its green past on its evolutionary journey.

Malaria severity not determined solely by parasite levels in blood
Although malaria kills some 600,000 African children each year, most cases of the mosquito-borne parasitic disease in children are mild.

The malaria pathogen's cellular skeleton under a super-microscope
The tropical disease malaria is caused by the Plasmodium parasite. For its survival and propagation, Plasmodium requires a protein called actin.

Study sheds light on how the immune system protects children from malaria
According to a study published today in PLOS Pathogens, children who live in regions of the world where malaria is common can mount an immune response to infection with malaria parasites that may enable them to avoid repeated bouts of high fever and illness and partially control the growth of malaria parasites in their bloodstream.

Scientists find new way to fight Malaria drug resistance
An anti-malarial treatment that lost its status as the leading weapon against the deadly disease could be given a new lease of life, with new research indicating it simply needs to be administered differently.

A tailor-made molecule against malaria
The malaria parasite is particularly pernicious since it is built to develop resistance to treatments.
More Malaria Parasite Current Events and Malaria Parasite News Articles

Avian Malaria Parasites and other Haemosporidia

Avian Malaria Parasites and other Haemosporidia
by Gediminas Valkiunas (Author)


When studying the effects of parasites on natural populations, the avian haematozoa fulfills many of the specifications of an ideal model. Featuring a multitude of tables and illustrations, Avian Malaria Parasites and Other Haemosporidia summarizes more than a century of research on bird haemosporidians. For a long time, bird blood parasites served as important models in studying human diseases. Although now largely replaced, the wealth of data and research remain. With chapters addressing life cycles and morphology, pathogenicity, ultrastructure, geographical distribution, and illustrated keys to all known species of the parasites, this book is a masterful assessment of the biology of bird haemosporidian parasites.

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 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...

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 Parasite Biology, Pathogenesis, and Protection

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




Malaria Parasites: Genomes and Molecular Biology

Malaria Parasites: Genomes and Molecular Biology
by Andrew P. Water (Editor), Chris J. Janse (Editor)


The completion of the Plasmodium falciparum genome sequence in late 2002 heralded a new era in malaria research. The search began in earnest for new drugs and vaccines to combat malaria, a disease which afflicts up to 500 million people worldwide and is responsible for the deaths of more than one million people each year. The new genomic data is aiding a greater understanding of the living parasite and its interaction with the insect vector and human host. In this book internationally renowned experts provide up-to-date reviews of the most important aspects of post-genomic malaria research. Topics covered include: the P. falciparum genome and model parasites, bioinformatics and genome databases, microsatellite analysis, analysis of chromosome structure, cell cycle to RNA polymerase I and...

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 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 parasites And Traditional medicinal plants: Severe malaria is caused by P.falciparum infection. Natural products have been important sources of antimalarial agent

Malaria parasites And Traditional medicinal plants: Severe malaria is caused by P.falciparum infection. Natural products have been important sources of antimalarial agent
by Abdolhossein Rustaiyan (Author)


Malaria statistics have become familiar. It is estimated that 300 to 500 million malaria infections occur annually, 90% of these in sub-Sahara Africa. A third of those visiting rural dispensaries are seeking treatment for malaria. Malaria accounts for between 20 and 50% of all admissions in African health services, with the poorest countries bearing the greatest burden of morbidity and mortality. Studies in a number of African countries have shown that the emergence of the chloroquine-resistant malaria parasites is associated with a two-fold increase in malaria deaths, but in one study in Mlomp Senegal, it was shown that malaria mortality in children under the age of four increased 11-fold within six years of the emergence of the chloroquine-resistance. The emergence of drug-resistant...

Malaria Parasite

Malaria Parasite
by Cengage Learning (Kidhaven) (Publisher)




© 2014 BrightSurf.com