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


Latest research by NTU discovers reasons for malaria's drug resistance
Scientists from Nanyang Technological University (NTU) have discovered exactly how the malaria parasite is developing resistance towards the most important front-line drugs used to treat the disease.

Analogues of a natural product are drug candidates against malaria
Researchers at IRB Barcelona identify a family of efficient and selective molecules to combat the parasite Plasmodium, causal agent of malaria.

Nanotechnology Against Malaria Parasites
Malaria parasites invade human red blood cells, they then disrupt them and infect others. Researchers at the University of Basel and the Swiss Tropical and Public Health Institute have now developed so-called nanomimics of host cell membranes that trick the parasites.

Promising compound rapidly eliminates malaria parasite
An international research collaborative has determined that a promising anti-malarial compound tricks the immune system to rapidly destroy red blood cells infected with the malaria parasite but leave healthy cells unharmed. St. Jude Children's Research Hospital scientists led the study, which appears in the current online early edition of the Proceedings of the National Academy of Sciences (PNAS).

Mosquitoes and malaria: Scientists pinpoint how biting cousins have grown apart
Certain species of mosquitoes are genetically better at transmitting malaria than even some of their close cousins, according to a multi-institutional team of researchers including Virginia Tech scientists.

Malaria from monkeys now dominant cause of human malaria hospitalizations in Malaysia
The majority of malaria hospitalizations in Malaysia are now caused by a dangerous and potentially deadly monkey-borne parasite once rarely seen in humans, and deforestation is the potential culprit in a growing number of infections that could allow this virulent malaria strain to jump from macaque monkeys to human hosts.

Skin patch could replace the syringe for disease diagnosis
Drawing blood and testing it is standard practice for many medical diagnostics. As a less painful alternative, scientists are developing skin patches that could one day replace the syringe.

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.
More Malaria Parasite Current Events and Malaria Parasite News Articles

Malaria Parasite Biology, Pathogenesis, and Protection

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




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, Poems

Malaria, Poems
by Cameron Conaway (Author)


Malaria kills nearly one million people each year. Hundreds of millions more are sickened by the disease, and many of them are permanently disabled. Billions are spent each year to understand it. Researchers know the molecular details of the interaction between the mosquito and our own red blood cells, and the myriad ways in which malaria impacts the global economy and the advancement of humanity. But what of the public? Though its story is told in thousands of articles and in hundreds of books, many in the developed world are unaware of how prevalent malaria still is. Malaria, Poems testifies to the importance of bridging the chasm between science and art. It adds thread to a tattered and tragic global narrative; it is poetry’s attempt to reawaken care in a cold case that keeps...

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: 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...

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.

Undeniable: Evolution and the Science of Creation

Undeniable: Evolution and the Science of Creation
by Bill Nye (Author), Corey S. Powell (Editor)


"Evolution is one of the most powerful and important ideas ever developed in the history of science. Every question it raises leads to new answers, new discoveries, and new smarter questions. The science of evolution is as expansive as nature itself. It is also the most meaningful creation story that humans have ever found."—Bill Nye

Sparked by a controversial debate in February 2014, Bill Nye has set off on an energetic campaign to spread awareness of evolution and the powerful way it shapes our lives. In Undeniable: Evolution and the Science of Creation, he explains why race does not really exist; evaluates the true promise and peril of genetically modified food; reveals how new species are born, in a dog kennel and in a London subway; takes a stroll through 4.5 billion years...

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 Methods and Protocols (Methods in Molecular Medicine)

Malaria Methods and Protocols (Methods in Molecular Medicine)
by Denise L. Doolan (Editor)


The Plasmodium spp. parasite was identified as the causative agent of malaria in 1880, and the mosquito was identified as the vector in 1897. Despite subsequent efforts focused on the epidemiology, cell biology, immunology, molecular biology, and clinical manifestations of malaria and the Plasmodium parasite, there is still no licensed vaccine for the prevention of malaria. Physical barriers (bed nets, window screens) and chemical prevention methods (insecticides and mosquito repellents) intended to interfere with the transmission of the disease are not highly effective, and the profile of resistance of the parasite to chemoprophylactic and chemotherapeutic agents is increasing. The dawn of the new millennium has seen a resurgence of interest in the disease by government and philanthropic...

© 2014 BrightSurf.com