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Increased levels of polyadenylated histone H2B mRNA accumulate during Entamoeba invadens cyst formation
L B Sanchez1, V Enea, D Eichinger
1Department of Medical and Molecular Parasitology, New York University, School of Medicine, NY 10016.
Abstract:
We have isolated cDNA clones of a member of the histone H2B protein family by differential screening of an Entamoeba invadens cDNA library with cDNA probes from vegetatively growing or encysting parasites. The cDNA clones reveal two polyadenylation sites, 26 nucleotides and 31 nucleotides downstream from the stop codon. RNA species recognized by E. invadens histone H2B clones are found at increased levels during cyst formation. Histone H2B RNA could be detected in both the poly(A)+ and poly(A)- RNA fractions, with stage-specific differences in the steady state levels of the two RNAs: trophozoites contain predominantly the poly(A)- RNA, while encysting parasites express predominantly the poly(A)+ RNA. Southern blot analysis suggests that both forms are transcribed from a single copy gene.
Insights
We identified histone H2B gene expression in Entamoeba invadens during cyst formation. This study reveals stage-specific regulation of histone H2B RNA, crucial for parasite development.
Area of Science:
- Molecular Biology
- Parasitology
- Genetics
Background:
- Histones are crucial for DNA packaging and gene regulation.
- Entamoeba invadens undergoes a complex life cycle involving distinct parasitic stages.
Purpose of the Study:
- To isolate and characterize cDNA clones of histone H2B from Entamoeba invadens.
- To investigate the expression patterns of histone H2B during parasite differentiation, specifically encystment.
Main Methods:
- Differential screening of an Entamoeba invadens cDNA library.
- Analysis of polyadenylation sites and RNA species using Northern blot.
- Southern blot analysis to determine gene copy number.
Main Results:
- Isolated cDNA clones corresponding to Entamoeba invadens histone H2B.
- Identified two polyadenylation sites downstream of the stop codon.
- Observed increased histone H2B RNA levels during cyst formation.
- Demonstrated stage-specific differences in polyadenylated (poly(A)+) and non-polyadenylated (poly(A)-) RNA fractions.
- Southern blot analysis indicated a single-copy gene for histone H2B.
Conclusions:
- Histone H2B gene expression is upregulated during Entamoeba invadens encystment.
- The regulation of histone H2B RNA involves differential polyadenylation and stage-specific accumulation.
- Histone H2B in Entamoeba invadens is encoded by a single gene.