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At least 73 records · Page 4Linked to original sources
PubMed2003

Characterization of the chlorosome antenna of the filamentous anoxygenic phototrophic bacterium Chloronema sp. strain UdG9001.

The absorption and fluorescence properties of chlorosomes of the filamentous anoxygenic phototrophic bacterium Chloronema sp. strain UdG9001 were analyzed. The chlorosome antenna of Chloronema consists of bacteriochlorophyll (BChl) d and BChl c together with gamma-carotene as the main carotenoid. HPLC analysis combined with APCI LC-MS/MS showed that the chlorosomal BChls comprise a highly diverse array of homologues that differ in both the degree of alkylation of the macrocycle at C-8 and/or C-12 and the alcohol moiety esterified to the propionic acid group at C-17. BChl c and BChl d from Chloronema were mainly esterified with geranylgeraniol (33% of the total), heptadecanol (24%), octadecenol (19%), octadecanol (14%), and hexadecenol (9%). Despite this pigment heterogeneity, fluorescence emission of the chlorosomes showed a single peak centered at 765 nm upon excitation at wavelengths ranging from 710 to 740 nm. This single emission, assigned to BChl c, indicates an energy transfer from BChl d to BChl c within the same chlorosome. Likewise, incubation of chlorosomes under reducing conditions caused a weak increase in fluorescence emission, which indicates a small redox-dependent fluorescence. Finally, protein analysis of Chloronema chlorosomes using SDS-PAGE and MALDI-TOF-MS revealed the presence of a chlorosomal polypeptide with a molecular mass of 5.7 kDa, resembling the CsmA protein found in Chloroflexus aurantiacus and Chlorobium tepidum chlorosomes. Several minor polypeptides were also detected but not identified. These results indicate that, compared with other members of filamentous anoxygenic phototrophic bacteria and green sulfur bacteria, Chloronema possesses an antenna system with novel features that may be of interest for further investigations.

Bacterial Proteins↗
PubMed2003

Phylogenetic and physiological characterization of a filamentous anoxygenic photoautotrophic bacterium ' Candidatus Chlorothrix halophila' gen. nov., sp. nov., recovered from hypersaline microbial mats.

We report the phylogenetic and physiological characterization of a mesophilic and halophilic member of the filamentous anoxygenic phototrophic (FAP) bacteria, provisionally named ' Candidatus Chorothrix halophila' gen. nov. sp. nov., that has been maintained in a highly enriched culture in our laboratory for over a decade. Phylogenetic analysis of small-subunit RNA-encoding sequences places ' Candidatus Chlorothrix halophila' in a clade that includes cultivated members of the genera Chloroflexus and Oscillochloris. Physiological studies demonstrated sulfide-dependent photosynthetic uptake of (14)C-labeled bicarbonate. Enzymatic assays for the activity of propionyl-coenzyme A synthase indicated that ' Candidatus Chlorothrix halophila' does not use the 3-hydroxypropionate cycle of Chloroflexus aurantiacus OK-70-fl for autotrophic carbon assimilation. New concepts regarding the taxonomy and phylogeny of FAP bacteria have emerged from this work.

Bacterial Physiological Phenomena↗
PubMed2004

Studies on hydrogenase activity and chlorobenzene respiration in Dehalococcoides sp. strain CBDB1.

Hydrogen oxidation and electron transport were studied in the chlorobenzene-utilizing anaerobe Dehalococcoides sp. strain CBDB1. While Cu(2+) and Hg(2+) ions irreversibly inhibited hydrogenase activity in intact cells, Ni(2+) ions inhibited reversibly. About 80% of the initial hydrogenase activity was inactivated within 30 s when the cells were exposed to air. In contrast, hydrogenase was active at a redox potential of +10 mV when this redox potential was established anoxically with a redox indicator. Viologen dyes served both as electron acceptor for hydrogenase and electron donor for the dehalogenase. A menaquinone analogue, 2,3-dimethyl 1,4-naphthoquinone, served neither as electron acceptor for the hydrogenase nor as electron donor for the dehalogenase. In addition, the menaquinone antagonist 2-n-heptyl-4-hydroxyquinoline-N-oxide had no effect on dechlorination catalyzed by cell suspensions or isolated membranes with hydrogen as electron donor, lending further support to the notion that menaquinone is not involved in electron transport. The ionophores tetrachlorosalicylanilide and carbonylcyanide m-chlorophenylhydrazone did not inhibit dechlorination by cell suspensions, indicating that strain CBDB1 does not require reverse electron transport. The ATP-synthase inhibitor N,N'-dicyclohexylcarbodiimide inhibited the dechlorination reaction with cell suspensions; however, the latter effect was partially relieved by the addition of tetrachlorosalicylanilide. 1,2,3,4-tetrachlorobenzene strongly inhibited dechlorination of other chlorobenzenes by cell suspensions with hydrogen as electron donor, but it did not interfere with either hydrogenase or dehalogenase activity.

Chlorobenzenes↗
PubMed2003

Detection and quantitative estimation of Dehalococcoides spp. in a dechlorinating bioreactor by a combination of fluorescent in situ hybridisation (FISH) and kinetic analysis.

The unique capacity of Dehalococcoides ethenogenes of completely dechlorinating the common groundwater pollutant tetrachloroethene (PCE) to the harmless ethene makes this microorganism very attractive for application in natural or engineered bioremediation systems. In this study, the qualitative and quantitative determination of Dehalococcoides spp. in a lab-scale bioreactor was performed based on the combination of fluorescent in situ hybridisation (FISH) for specific detection, and kinetic batch tests at non-limiting hydrogen and PCE concentration for quantitative determination. The dechlorinating bioreactor was operated at a high and constant PCE loading rate of 255 micromol PCE [g volatile suspended solids (VSS)](-1) day(-1). Pale coccoid cells resembling the distinctive morphotype of D. ethenogenes were present in the microbial culture. These cocci hybridised with both eubacterial probes and the Dhe1259t probe recently designed for detecting Dehalococcoides spp. Positive hybridisation was also observed when the DHC1377 reverse primer was used as a specific probe and applied to the dechlorinating microbial consortium. The maximum dechlorination rate obtained under non-limiting hydrogen and PCE concentrations was 3.22 +/- 0.08 mmol Cl(-) l(-1 )day(-1). From the specific activity of D. ethenogenes [i.e. 0.055 +/- 0.008 mmol Cl(-) (mg VSS)(-1) day(-1)], as reported from pure culture study, this observed maximum rate corresponded to a concentration of this bacterium in the mixed liquor of the bioreactor of 59.0+/-10.4 mg VSS.l(-1) (41.5+/-11.2% of overall VSS). This calculated relative abundance of D. ethenogenes was in agreement with the percentage of methanol (in terms of reducing equivalents) channeled to reductive dechlorination (approximately 30%) supporting the assumption that most reductive dechlorination was actually due to this microorganism.

Biodegradation, Environmental↗
PubMed2006

Microbial diversity in natural environments: focusing on fundamental questions.

Interactions with Gijs Kuenen and other Dutch scientists have led my lab to fundamental insights into the composition, structure and function of a hot spring cyanobacterial mat community that should influence our thinking about all microbial communities. By focusing on the distribution of molecular sequence variants of predominant mat phototrophs, we have discovered that small-scale sequence variation can be ecologically meaningful. By applying novel cultivation approaches, we have been able to obtain genetically relevant community members and thus to test the hypothesis that closely related sequence variants arose via adaptive evolutionary radiation. By applying the analytical tools of organic geochemistry we have gained insight into the metabolisms of major phototrophic members of the mat community as well as interactions between phototrophic guilds. These observations challenge traditional paradigms about prokaryotic species and cause us to consider evolutionary ecology theory as we develop genome-based methods for high-resolution analysis of the species-like fundamental units comprising microbial communities, and for investigating how such units coordinate the physiological activities within guilds of the community.

Autotrophic Processes↗
PubMed2006

Anaerobic bioremediation of groundwater containing a mixture of 1,1,2,2-tetrachloroethane and chloroethenes.

This study investigated the biotransformation pathways of 1,1,2,2-tetrachloroethane (1,1,2,2-TeCA) in the presence of chloroethenes (i.e. tetrachloroethene, PCE; trichloroethene, TCE) in anaerobic microcosms constructed with subsurface soil and groundwater from a contaminated site. When amended with yeast extract, lactate, butyrate, or H2 and acetate, 1,1,2,2-TeCA was initially dechlorinated via both hydrogenolysis to 1,1,2-trichloroethane (1,1,2-TCA) (major pathway) and dichloroelimination to dichloroethenes (DCEs) (minor pathway), with both reactions occurring under sulfidogenic conditions. In the presence of only H2, the hydrogenolysis of 1,1,2,2-TeCA to 1,1,2-TCA apparently required the presence of acetate to occur. Once formed, 1,1,2-TCA was degraded predominantly via dichloroelimination to vinyl chloride (VC). Ultimately, chloroethanes were converted to chloroethenes (mainly VC and DCEs) which persisted in the microcosms for very long periods along with PCE and TCE originally present in the groundwater. Hydrogenolysis of chloroethenes occurred only after highly reducing methanogenic conditions were established. However, substantial conversion to ethene (ETH) was observed only in microcosms amended with yeast extract (200 mg/l), suggesting that groundwater lacked some nutritional factors which were likely provided to dechlorinating microorganisms by this complex organic substrate. Bioaugmentation with an H2-utilizing PCE-dechlorinating Dehalococcoides spp. -containing culture resulted in the conversion of 1,1,2,2-TeCA, PCE and TCE to ETH and VC. No chloroethanes accumulated during degradation suggesting that 1,1,2,2-TeCA was degraded through initial dichloroelimination into DCEs and then typical hydrogenolysis into ETH and VC.

Anaerobiosis↗
PubMed2004

Dechlorination of PCE in the presence of Fe0 enhanced by a mixed culture containing two Dehalococcoides strains.

A mixed culture capable of supplying its energy requirements by the oxidation of zero-valent iron (Fe0) and concomitant reduction of chlorinated ethenes was established. The culture contained Dehalococcoides species as determined by polymerase chain reaction (PCR) with genus specific primers. The use of a newly designed ARDRA procedure and subsequent sequencing revealed the presence of two Dehalococcoides strains, one closely related to Dehalococcoides ethenogenes strain 195, a bacterium respiring with chlorinated ethenes, and one closely related to strain CBDB1 a chlorobenzene and dioxin dehalogenating anaerobe. The mixed culture was used to study dechlorination of tetrachloroethene (PCE) to ethene in the presence of Fe0. Whereas abiotic transformation of PCE by Fe0 led to incomplete dechlorination, the mixed culture mediated fast and complete dechlorination of PCE to ethene with Fe0 as electron donor. Compared to cultures with hydrogen added as electron donor, cultures with Fe0 as electron donor showed the same or higher rates of PCE dechlorination. Growth of the Dehalococcoides strains in the mixed culture is linked to the presence of Fe0 as electron donor and PCE as electron acceptor demonstrating that Dehalococcoides spp. play a pivotal role in the dechlorination of chlorinated ethenes in Fe0 systems.

Anaerobiosis↗
PubMed2004

Development of a real-time PCR method for quantification of the three genera Dehalobacter, Dehalococcoides, and Desulfitobacterium in microbial communities.

We developed standard curves based on plasmids containing a 16S rRNA gene of a member of one of the three genera Dehalobacter, Desulfitobacterium, and Dehalococcoides. A large difference in amplification efficiency between the standard curves was observed ranging from 1.5 to 2.0. The total eubacterial 16S rRNA gene copy number determined in a sample DNA by using eubacterial primers and the three standard curves led to differences in the estimated copy numbers of a factor up to 73. However, the amplification efficiencies for one specific standard curve were the same independent of the PCR primer pair used. This allowed the determination of the abundance of a population expressed as fractional number, hence, the percentage of genus-specific copy numbers within the total eubacterial 16S rRNA gene copy numbers. Determination of the fractional numbers in DNA mixtures of known composition showed the accuracy of this approach. The average difference in threshold value between two 10-fold dilutions of DNA of pure cultures, mixtures thereof and of environmental samples was -3.45+/-0.34, corresponding to an average almost optimal amplification efficiency of 1.95. This indicated that the low amplification efficiency of certain standard curves seemed to be mainly a problem of the plasmid DNA used and not of the 16S rRNA gene of the target genera.

Bacteria, Anaerobic↗
PubMed2006

Relationship between Dehalococcoides DNA in ground water and rates of reductive dechlorination at field scale.

Certain strains of Dehalococcoides bacteria can dechlorinate chlorinated ethylenes to harmless products. This study was conducted to determine if there is a valid association between the density of Dehalococcoides DNA in ground water and the observed rates of reductive dechlorination at field scale. Dehalococcoides DNA in water from monitoring wells was determined using the quantitative real time polymerase chain reaction (q-PCR) with DNA primer set specific for Dehalococcoides organisms. Dechlorination rate constants were extracted from field data using the BIOCHLOR software. Of the six conventional plumes surveyed, "generally useful" rates of dechlorination (greater than or equal to 0.3 per year) of cis-dichloroethylene (cis-DCE) and vinyl chloride (VC) along the flow path were observed at three sites where Dehalococcoides DNA was detected, and little attenuation of cis-DCE and VC occurred at two sites where Dehalococcoides DNA was not detected. At the two sites where there was no net direction of ground water flow, the relationship between the density of Dehalococcoides DNA in ground water and the trend in concentrations of chlorinated ethylenes over time in monitoring wells was not so consistent as that observed for the conventional plumes. A comparison of our study to a field study performed by Lendvay and his coworker indicated that monitoring wells did not efficiently sample the Dehalococcoides organisms in the aquifer.

Chlorine↗
PubMed2006

Temperature dependence of anaerobic TCE-dechlorination in a highly enriched Dehalococcoides-containing culture.

Temperature dependence of reductive trichloroethene (TCE) dechlorination was investigated in an enrichment culture (KB-1), using lactate or propionate as electron donors at a temperature interval from 4 to 60 degrees C. Dechlorination was complete to ethene at temperatures between 10 and 30 degrees C (lactate-amended) and between 15 and 30 degrees C (propionate-amended). Dechlorination stalled at cis-1,2-dichloroethene (cDCE) at 4 degrees C (lactate-amended), at and below 10 degrees C (propionate-amended), and at 40 degrees C with both electron donors. No dechlorination of TCE was observed at 50 and 60 degrees C. Concentrations of Dehalococcoides had increased or remained constant after 15 days of incubation at temperatures involving complete dechlorination to ethene. Temperature dependence of dechlorination rates was compared using zero order degradation kinetics and a Monod growth-rate model for multiple electron acceptor usage with competition. Maximum growth rates (mu) and zero order degradation rates were highest for TCE dechlorination at 30 degrees C with lactate as substrate (mu(TCE) of 7.00+/-0.14 days(-1)). In general, maximum growth rates and dechlorination rates of TCE were up to an order of magnitude higher than rates for utilization of cis-dichloroethene (cDCE, mu(c)(DCE) up to 0.17+/-0.02 days(-1)) and vinyl chloride (VC, mu(VC) up to 0.52+/-0.09 days(-1)). Temperature dependence of maximum growth rates and degradation rates of cDCE and VC were similar and highest at 15-30 degrees C, with growth rates on cDCE being lower than on VC. This study demonstrates that bioaugmentation of chlorinated ethene sites may be more efficient at elevated temperatures.

Anaerobiosis↗
PubMed2004

Dehalococcoides ethenogenes strain 195 reductively dechlorinates diverse chlorinated aromatic pollutants.

Dehalococcoides ethenogenes strain 195 dechlorinates tetrachloroethene to vinyl chloride and ethene, and its genome has been found to contain up to 17 putative dehalogenase gene homologues, suggesting diverse dehalogenation ability. We amended pure or mixed cultures containing D. ethenogenes strain 195 with 1,2,3,4-tetrachlorodibenzo-p-dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin, 2,3-dichlorodibenzo-p-dioxin, 1,2,3,4-tetrachlorodibenzofuran, 2,3,4,5,6-pentachlorobiphenyl, 1,2,3,4-tetrachloronaphthalene, various chlorobenzenes, or a mixture of 2-, 3-, and 4-chlorophenol to determine the dehalogenation ability. D. ethenogenes strain 195 dechlorinated 1,2,3,4-tetrachlorodibenzo-p-dioxin to a mixture of 1,2,4-trichlorodibenzo-p-dioxin and 1,3-dichlorodibenzo-p-dioxin. 2,3,4,5,6- Pentachlorobiphenyl was dechlorinated to 2,3,4,6- and/or 2,3,5,6-tetrachlorobiphenyl and 2,4,6-trichlorobiphenyl. 1,2,3,4-Tetrachloronaphthalene was dechlorinated primarily to an unidentified dichloronaphthalene congener. The predominant end products from hexachlorobenzene dechlorination were 1,2,3,5-tetrachlorobenzene and 1,3,5-trichlorobenzene. We did not detect dechlorination daughter products from monochlorophenols, 2,3-dichlorodibenzo-p-dioxin or 2,3,7,8- tetrachlorodibenzo-p-dioxin. D. ethenogenes strain 195 has the ability to dechlorinate many different types of chlorinated aromatic compounds, in addition to its known chloroethene respiratory electron acceptors. Remediation of sediments contaminated with aromatic halogenated organic pollutants such as polychlorinated biphenyls and polychlorinated dibenzo-p-dioxins could require billions of dollars in the coming years. Harnessing microorganisms such as Dehalococcoides spp. that detoxify these compounds via removal of halogens may lead to cost-effective biotechnological approaches for remediation.

Biodegradation, Environmental↗
PubMed2004

Comparative evaluation of chloroethene dechlorination to ethene by Dehalococcoides-like microorganisms.

Reductive dehalogenation of tetrachloroethene (PCE), trichloroethene (TCE), cis-1,2-dichloroethene (DCE), and vinyl chloride (VC) was examined in four cultures containing Dehalococcoides-like microorganisms. Dechlorination and growth kinetics were compared using a Monod growth-rate model for multiple electron acceptor usage with competition. Included were the Victoria mixed culture containing Dehalococcoides species strain VS (from Victoria, TX), the mixed culture KB-1/VC (from southern Ontario), the Pinellas mixed culture (from Pinellas, FL), and D. ethenogenes strain 195. All cultures, with the exception of D. ethenogenes strain 195, grew with VC as catabolic electron acceptor. A dilution method was developed that allows a valid comparison to be made of dehalogenating kinetics between different mixed cultures. Using this procedure, maximum growth rates on VC were found to be similar for strain VS and KB-1/VC (0.42-0.49 +/- 0.02 d(-1)) but slower for the Pinellas culture (0.28 +/- 0.01 d(-1)). The 16S rRNA gene sequences were determined to ensure that no cross contamination between cultures had occurred. Following enrichment of the VC dechlorinating microorganisms on VC, the cultures were amended with DCE, TCE, or PCE. The three mixed cultures failed to dechlorinate PCE or did so very slowly. However, the dilution technique indicated that all experienced growth on TCE and DCE as well as on VC. Maximum growth rates on DCE alone were quite similar (0.43-0.46 d(-1)), while the Pinellas culture grew faster on TCE alone (0.49 d(-1)) than did the other two mixed cultures (0.33-0.35 d(-1)). Half-velocity and inhibition constants for growth on TCE were also determined for the three mixed cultures; both constants were found to be essentially equal and the same for the different cultures, varying between only 8.6 and 10.5 microM. The ability of the strain VS, KB-1/VC, and Pinellas cultures to utilize TCE rapidly with conversion to ethene is quite different from that of any other reported microorganism. It was separately confirmed with more traditional cell-counting techniques that strain VS coupled TCE, as well as DCE and VC, utilization with growth. This is the first report of an organism obtaining energy for growth through every step in the reduction of TCE to ethene. Also, as suggested by the dilution technique, the dehalogenating organisms in the KB-1/VC and Pinellas cultures appear to obtain growth from TCE utilization as well. Such ability to grow while dehalogenating TCE to ethene will be an important advantage for their use in bioaugmentation.

Biodegradation, Environmental↗
PubMed2006

1,1-dichloroethene as a predominant intermediate of microbial trichloroethene reduction.

A microbial culture derived from a landfill site in Dover, DE consistently reduced trichloroethene (TCE) to ethene through 1,1-dichloroethene (DCE) as a dominant intermediate in the presence of ampicillin. A constant 1,1-DCE-to-cis-DCE ratio of 2.4 +/- 0.3 was observed for more than two years, while trans-DCE was never detected. Without ampicillin, however, TCE was reduced to ethene almost exclusively through cis-DCE, suggesting that the culture contained at leasttwo TCE-dechlorinating populations. Two subcultures, which were established using 1,1-DCE or vinyl chloride as an electron acceptor, exhibited the same 1,1-DCE-to-cis-DCE ratio when TCE was introduced. PCR amplification of 16S rRNA gene followed by sequencing and DGGE analysis indicate that these (sub)cultures contained a Dehalococcoides population(s). TCE dechlorination assays with crude cell extract showed a DCE distribution pattern similar to that with whole cells. The enzyme involved in 1,1-DCE formation was likely a cobalt corrinoid enzyme, as suggested by the inhibitory effect of CH3I and photoreversibility of the inhibition. This study provides a possible biological mechanism forthe occurrence of 1,1-DCE in TCE-contaminated sites.

Ampicillin↗
PubMed2006

A modeling study and implications of competition between Dehalococcoides ethenogenes and other tetrachloroethene-respiring bacteria.

Bioaugmentation with cultures containing Dehalococcoides strains that dechlorinate cis-1,2-dichloroethene (cDCE) to ethene is often recommended at sites where indigenous populations dechlorinate tetrachloroethene (PCE) to cDCE. In these cases, Dehalococcoides populations may have to compete with other dehalorespirers for chlorinated ethenes and/or electron donors. A continuous-flow stirred tank reactor model was used to describe the substrate interactions in three conceptual models of competition between PCE-respiring populations under natural attenuation and engineered bioremediation scenarios. Model simulations were used to evaluate the effects of other chlorinated ethene respirers on substrate utilization by, and growth of, a Dehalococcoides strain (Dhc. ethenogenes strain 195) and identify the key factors influencing the outcome of competition among different dehalorespirers. The results suggest that, under natural attenuation conditions, Dhc. ethenogenes is unlikely to be the dominant population if a dehalorespirer that can compete for limiting amounts of reducing equivalents is present. Engineered bioremediation conditions resulted in greater enrichment of Dhc. ethenogenes than of competing dehalorespirers. Under several conditions, Dhc. ethenogenes coexisted with a PCE-to-cDCE (or PCE-to-TCE) dehalorespirer, primarily by functioning as a cDCE- (or TCE)-to-ethene dechlorinating specialist. From a bioremediation standpoint, maintenance of multiple dehalorespiring specialists appears ideal because it may result in the fastest and most extensive chlorinated ethene transformations. Thus, to improve our ability to successfully implement bioremediation, it may be helpful to characterize the indigenous PCE-to-cDCE respiring populations and the nature and distribution of electron donors used by these dehalorespirers at contaminated sites. Further understanding of these interactions requires more accurate information on the kinetics of known dehalorespiring populations.

Chloroflexi↗
PubMed2004

A new thermostable alpha-L-arabinofuranosidase from a novel thermophilic bacterium.

An alpha-L-arabinofuranosidase gene was identified in a sequenced genome of a novel thermophilic bacterium, which belongs to the recently described phylum of Thermomicrobia. Amino acid sequence comparison of the enzyme (designated AraF) revealed similarity to glycoside hydrolases of family 51. The gene was cloned into Escherichia coli and its recombinant product expressed and purified. The enzyme appeared to be a hexamer. AraF was optimally active at 70 degrees C (over 10 min) and pH 6 having 92% residual activity after 1 h at 70 degrees C. AraF had a Km) value of 0.6 mM and V(max) value of 122 U mg(-1) on p-nitrophenyl-alpha-L-arabinofuranoside. AraF was almost equally active on branched arabinan and debranched arabinan, properties not previously found in alpha-L-arabinofuranosidases in GH family 51.

Bacterial Proteins↗
PubMed2005

Genome sequence of the chlorinated compound-respiring bacterium Dehalococcoides species strain CBDB1.

Dehalococcoides species are strictly anaerobic bacteria, which catabolize many of the most toxic and persistent chlorinated aromatics and aliphatics by reductive dechlorination and are used for in situ bioremediation of contaminated sites. Our sequencing of the complete 1,395,502 base pair genome of Dehalococcoides strain CBDB1 has revealed the presence of 32 reductive-dehalogenase-homologous (rdh) genes, possibly conferring on the bacteria an immense dehalogenating potential. Most rdh genes were associated with genes encoding transcription regulators such as two-component regulatory systems or transcription regulators of the MarR-type. Four new paralog groups of rdh-associated genes without known function were detected. Comparison with the recently sequenced genome of Dehalococcoides ethenogenes strain 195 reveals a high degree of gene context conservation (synteny) but exceptionally high plasticity in all regions containing rdh genes, suggesting that these regions are under intense evolutionary pressure.

Base Sequence↗