Related Experiment Video
Updated: Jul 19, 2026
13:06
Analysis of Single-cell Gene Transcription by RNA Fluorescent In Situ Hybridization (FISH)
Published on: October 7, 2012
Malaria. Cooperative silencing elements in var genes
K W Deitsch1, M S Calderwood, T E Wellems
1Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0425, USA.
Nature
|August 31, 2001
Summary
Malaria parasites silence most var genes during DNA synthesis. This silencing relies on interactions between control regions, crucial for antigenic variation.
Area of Science:
- Molecular biology
- Parasitology
- Genetics
Background:
- Plasmodium falciparum causes malaria and possesses approximately 50 var genes.
- Var genes encode proteins mediating cytoadherence of infected erythrocytes.
- Parasites express only one var gene at a time, silencing others for immune evasion.
Purpose of the Study:
- To investigate the timing and mechanism of var gene silencing in Plasmodium falciparum.
- To identify the genetic elements involved in regulating var gene expression.
- To elucidate the process of antigenic variation in malaria parasites.
Main Methods:
- Cell cycle analysis of Plasmodium falciparum.
- Investigation of var gene regulatory elements, including the 5'-flanking region and intron.
- Assessing the cooperative interaction between distinct control regions.
Main Results:
- Var gene silencing is established during the S phase of the parasite cell cycle.
- Silencing is dependent on cooperative interactions between the 5'-flanking region and the intron of var genes.
- Specific control regions work together to maintain gene silencing.
Conclusions:
- The DNA synthesis (S phase) is a critical window for establishing var gene silencing.
- Cooperative interactions between separate regulatory elements are essential for coordinated var gene silencing.
- Understanding these mechanisms can clarify how malaria parasites achieve antigenic variation.
Related Concept Videos
02:32Position-effect Variegation
In 1928, a German botanist Emil Heitz observed the moss nuclei with a DNA binding dye. He observed that while some chromatin regions decondense and spread out in the interphase nucleus, others do not. He termed them euchromatin and heterochromatin, respectively. He proposed that the heterochromatin regions reflect a functionally inactive state of the genome. It was later confirmed that heterochromatin is transcriptionally repressed, and euchromatin is transcriptionally active chromatin.
02:02Cis-regulatory Sequences
Cis-regulatory sequences are short fragments of non-coding DNA that are present on the same chromosomes as the genes that they regulate. These fragments serve as binding sites for transcriptional regulators, proteins that are responsible for controlling gene transcription and differential gene expression across cell types in eukaryotes. Cis-regulatory sequences can be close to the gene of interest or thousands of bases away in the DNA sequence; however, those sequences that are further away are...
01:29Malaria
Malaria pathogenesis in humans reflects a delicate interplay between parasite biology and host response. Clinical illness reflects a host’s immune response to the parasite’s asexual replication cycle, which is often asymptomatic in individuals with partial immunity. From the parasite's perspective, transmission between mosquito and human with minimal host pathology is evolutionarily advantageous. Among the six Plasmodium species infecting humans, P. falciparum and P. vivax dominate in global...