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Related Concept Videos

Giardiasis01:12

Giardiasis

Giardiasis is a globally prevalent intestinal infection caused by the protozoan parasite Giardia duodenalis (also known as G. lamblia or G. intestinalis). This flagellated protozoan is the most frequently identified intestinal parasite in the United States and worldwide. Transmission primarily occurs via the fecal-oral route, with infection arising from ingestion of water or food contaminated with cysts. Individuals in low-resource settings, international travelers, outdoor enthusiasts, daycare...
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Excavata is a diverse group of protists that includes both chemoorganotrophic and phototrophic species, with some thriving in anaerobic environments. Among the key groups within Excavata are diplomonads and parabasalids, which are flagellated protists that lack mitochondria and chloroplasts. These microorganisms typically inhabit anoxic environments, such as the intestines of animals, where they exist either symbiotically or as parasites, relying on fermentation for energy production. Some...
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While every living organism has a genome of some kind (be it RNA, or DNA), there is considerable variation in the sizes of these blueprints. One major factor that impacts genome size is whether the organism is prokaryotic or eukaryotic. In prokaryotes, the genome contains little to no non-coding sequence, such that genes are tightly clustered in groups or operons sequentially along the chromosome. Conversely, the genes in eukaryotes are punctuated by long stretches of non-coding sequence.
Exon Recombination02:32

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The evolution of new genes is critical for speciation. Exon recombination, also known as exon shuffling or domain shuffling, is an important means of new gene formation. It is observed across vertebrates, invertebrates, and in some plants such as potatoes and sunflowers. During exon recombination, exons from the same or different genes recombine and produce new exon-intron combinations, which might evolve into new genes. 
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Horizontal gene transfer (HGT) is a process where genetic material moves between organisms within the same generation, unlike vertical gene transfer, which occurs from parent to offspring. HGT plays a crucial role in microbial evolution, adaptation, and survival, particularly in shared environments like the human gut.Mobile genetic elements such as plasmids, prophages, integrons, insertion sequences, and transposons facilitate this process. HGT occurs through three primary mechanisms:...
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The seminal work of Ohno in 1970 popularized the idea of gene duplication and divergence. DNA sequence comparison studies reveal that a large portion of the genes in bacteria, archaebacteria, and eukaryotes was  generated by gene duplication and divergence, indicating its critical role in evolution.
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are characterized.

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Mapping Bacterial Functional Networks and Pathways in Escherichia Coli using Synthetic Genetic Arrays
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Published on: November 12, 2012

Split genes: another surprise from Giardia.

Thomas Blumenthal1

  • 1Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309, USA. Tom.Blumenthal@Colorado.EDU

Current Biology : CB
|February 22, 2011
PubMed
Summary
This summary is machine-generated.

Genes in the early eukaryote Giardia lamblia are transcribed in separate pieces. These pre-mRNAs join and are spliced by the spliceosome, suggesting this may be an ancient feature of spliceosomal evolution.

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Automated Separation of C. elegans Variably Colonized by a Bacterial Pathogen
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Area of Science:

  • Molecular Biology
  • Genetics
  • Evolutionary Biology

Background:

  • The early evolution of gene expression mechanisms in eukaryotes is not fully understood.
  • The spliceosome, a complex molecular machine, is responsible for RNA splicing in eukaryotes.
  • Unusual gene organization has been observed in some primitive eukaryotes.

Purpose of the Study:

  • To investigate the gene structure and expression in the early-branching eukaryote Giardia lamblia.
  • To explore the potential implications of fragmented gene transcription for the evolution of the spliceosome.

Main Methods:

  • Analysis of gene structure in Giardia lamblia.
  • Examination of pre-messenger RNA (pre-mRNA) processing and splicing mechanisms.
  • Comparative genomics to infer evolutionary relationships.

Main Results:

  • Certain genes in Giardia lamblia are transcribed from non-contiguous chromosomal locations as separate pre-mRNAs.
  • These distinct pre-mRNAs exhibit complementarity, enabling them to associate.
  • The spliceosome subsequently splices these associated pre-mRNAs together.

Conclusions:

  • The fragmented gene transcription and splicing observed in Giardia lamblia provide a potential model for early spliceosomal function.
  • This mechanism suggests that genes-in-pieces, transcribed into separate pre-mRNAs, could represent an ancestral state in spliceosomal evolution.
  • Further research is needed to confirm the prevalence and evolutionary significance of this phenomenon in other early eukaryotes.