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


The hidden burden of dengue fever in West Africa
Misdiagnosis of febrile illnesses as malaria is a continuing problem in Africa. A new study shows that in Ghana, dengue fever is circulating in urban areas and going undiagnosed.

Malaria plays hide-and-seek with immune system by using long noncoding RNA to switch genes
Up to one million people -- mainly pregnant woman and young children -- are killed each year by the Plasmodium falciparum parasite, which causes the most devastating form of human malaria.

Children who get vitamin A may be less likely to develop malaria
Children under age 5 living in sub-Saharan Africa were 54 percent less likely to develop malaria if they had been given a single large dose of vitamin A, new research led by the Johns Hopkins Bloomberg School of Public Health suggests.

Genetics underpinning antimalarial drug resistance revealed
The largest genome-wide association study to date of the malaria parasite Plasmodium falciparum unveils a complex genetic architecture that enables the parasite to develop resistance to our most effective antimalarial drug, artemisinin.

Hybrid 'super mosquito' resistant to insecticide-treated bed nets
Interbreeding of two malaria mosquito species in the West African country of Mali has resulted in a "super mosquito" hybrid that's resistant to insecticide-treated bed nets.

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.
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)




Parasite Life Cycles

Parasite Life Cycles
by Dickson D. Despommier (Author), John W. Karapelou (Author)


In a unique, visual approach to the depiction of parasite life cycles, this detailed atlas presents a clear, concise, and complete overview of the parasite/human host interrelationship. 75 life cycles include all the major protozoan and helminth pathogens of man with new and updated information on several organisms. The illustrations follow the route of infection from point of entry, through the developmental stages, to completion of the cycle as the parasite reinfects the next host. Precise biological anatomical and medical depiction provides reinforcement. Distinguished by its organization, continuity, and accuracy, this comprehensive work will be a valuable reference for students, clinicians and others interested in the field of parasitology.

  Malaria Parasites: Diverse Topics
by Jamie Spooner (Editor)


Malaria is a global disease today but most common in underdeveloped countries of the world. Nearly 90% of deaths due to this fatal disease occur in Sub-Saharan Africa. This book presents information regarding global endeavors undertaken by scientists from across the world. Collaborated efforts such as symbiont based malaria control, latest applications in avian malaria studies, advancement of humanized mice to study P. falciparum (the most virulent species of malaria parasite) and contemporary issues in laboratory diagnosis will aid efficient treatment of malaria. Research has been progressing rapidly in the quest for providing an effective vaccine for the prevention of malaria. This book presents research aimed at bringing forward abiding solutions to malaria issues and the methods 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.

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...

The Wild Life of Our Bodies: Predators, Parasites, and Partners That Shape Who We Are Today

The Wild Life of Our Bodies: Predators, Parasites, and Partners That Shape Who We Are Today
by Rob Dunn (Author)


“An extraordinary book. . . . With clarity and charm [Dunn] takes the reader into the overlap of medicine, ecology, and evolutionary biology to reveal an important domain of the human condition.”—Edward O. Wilson, author of Anthill and The Future of LifeBiologist Rob Dunn reveals the crucial influence that other species have upon our health, our well being, and our world in The Wild Life of Our Bodies—a fascinating tour through the hidden truths of nature and codependence. Dunn illuminates the nuanced, often imperceptible relationships that exist between homo sapiens and other species, relationships that underpin humanity’s ability to thrive and prosper in every circumstance. Readers of Michael Pollan’s The Omnivore’s Dilemma will be enthralled by Dunn’s powerful, lucid...

© 2015 BrightSurf.com