Related Experiment Video
Updated: Aug 5, 2026
08:07
Spectrophotometric Determination of Phycobiliprotein Content in Cyanobacterium Synechocystis
Published on: September 11, 2018
Comparative molecular population genetics of phycoerythrin locus in Prochlorococcus
1Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao, China.
Genetica
|August 10, 2006
Summary
Phycoerythrin in Prochlorococcus shows distinct genetic variations between high light (HL) and low light (LL) populations. These differences suggest varying selective pressures and hint at phycoerythrin
Area of Science:
- Marine microbiology
- Molecular evolution
- Photosynthetic pigments
Background:
- Prochlorococcus, a key marine cyanobacterium, utilizes phycobiliproteins for light harvesting.
- Phycoerythrin is the sole remaining phycobiliprotein type in Prochlorococcus, but its function is unknown.
- Distinct phycoerythrin gene forms exist in high light (HL) and low light (LL) adapted ecotypes.
Purpose of the Study:
- To investigate patterns of phycoerythrin nucleotide variation in HL and LL Prochlorococcus populations.
- To identify potential selective pressures acting on phycoerythrin genes.
- To gain insights into the functional role of phycoerythrin in different light environments.
Main Methods:
- Analysis of phycoerythrin nucleotide variation patterns.
- Comparison of non-synonymous fixed substitutions in phycoerythrin genes (peB, peA) versus other related genes.
- Application of neutrality statistical tests and likelihood ratio tests.
- Mapping of positively selected sites onto the phycoerythrin tertiary structure.
Main Results:
- Significantly higher non-synonymous fixed substitutions in peB and peA compared to other phycoerythrin-related genes.
- Distinct patterns of nucleotide polymorphisms: excess rare polymorphisms in LL-Prochlorococcus, excess intermediate polymorphisms in HL-Prochlorococcus.
- Identification of different selective patterns for HL- and LL-phycoerythrin based on structural mapping.
Conclusions:
- Evidence suggests differential selection acting on phycoerythrin genes in Prochlorococcus ecotypes.
- The observed genetic variations indicate a potentially specialized role for phycoerythrin in adapting to light conditions.
- Further research is needed to elucidate the specific function of phycoerythrin in Prochlorococcus.
Related Concept Videos
00:46Genomic DNA in Prokaryotes
The genome of most prokaryotic organisms consists of double-stranded DNA organized into one circular chromosome in a region of cytoplasm called the nucleoid. The chromosome is tightly wound, or supercoiled, for efficient storage. Prokaryotes also contain other circular pieces of DNA called plasmids. These plasmids are smaller than the chromosome and often carry genes that confer adaptive functions, such as antibiotic resistance.
Genomic Diversity in Bacteria
Although bacterial genomes are much...
Genomic Diversity in Bacteria
Although bacterial genomes are much...
02:05Gene Evolution - Fast or Slow?
The genomes of eukaryotes are punctuated by long stretches of sequence which do not code for proteins or RNAs. Although some of these regions do contain crucial regulatory sequences, the vast majority of this DNA serves no known function. Typically, these regions of the genome are the ones in which the fastest change, in evolutionary terms, is observed, because there is typically little to no selection pressure acting on these regions to preserve their sequences.
In contrast, regions which code...
In contrast, regions which code...
02:16Comparing Mitochondrial, Chloroplast, and Prokaryotic Genomes
The present-day mitochondrial and chloroplast genomes have retained some of the characteristics of their ancestral prokaryotes and also have acquired new attributes during their evolution within eukaryotic cells. Like prokaryotic genomes, mitochondrial and chloroplast genomes neither bind with histone-like proteins nor show complex packaging into chromosome-like structures, as observed in eukaryotes. Unlike mitotic cell divisions observed in eukaryotic cells, mitochondria and chloroplasts...
02:54Evolutionary Relationships through Genome Comparisons
Genome comparison is one of the excellent ways to interpret the evolutionary relationships between organisms. The basic principle of genome comparison is that if two species share a common feature, it is likely encoded by the DNA sequence conserved between both species. The advent of genome sequencing technologies in the late 20th century enabled scientists to understand the concept of conservation of domains between species and helped them to deduce evolutionary relationships across diverse...
01:30Bacterial Phylum Cyanobacteria
Cyanobacteria are a diverse group of oxygenic, phototrophic bacteria that played a pivotal role in converting Earth’s atmosphere from anoxic to oxygen-rich billions of years ago. They exhibit remarkable morphological diversity, ranging from unicellular forms to filamentous types, with cell sizes varying between 0.5 μm and 100 μm. Cyanobacteria are classified into five groups: Chroococcales (unicellular, dividing by binary fission), Pleurocapsales (unicellular, dividing by multiple fission),...
01:22Phylogenetic Species Concept in Microbiology
The phylogenetic species concept (PSC) is a framework used to delineate species based on evolutionary relationships, emphasizing shared ancestry and diagnosable genetic traits. Unlike morphological or biological species concepts, the PSC is particularly advantageous for microbial taxonomy, where traditional reproductive or phenotypic criteria often fall short due to the prevalence of asexual reproduction, minimal morphological differentiation, and widespread horizontal gene transfer among...