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Ostrowski, M, Mazard S, Tetu SG, Phillippy K, Johnson A, Palenik B, Paulsen IT, Scanlan DJ.  2010.  PtrA is required for coordinate regulation of gene expression during phosphate stress in a marine Synechococcus. Isme Journal. 4:908-921.   10.1038/ismej.2010.24   AbstractWebsite

Previous microarray analyses have shown a key role for the two-component system PhoBR (SYNW0947, SYNW0948) in the regulation of P transport and metabolism in the marine cyanobacterium Synechococcus sp. WH8102. However, there is some evidence that another regulator, SYNW1019 (PtrA), probably under the control of PhoBR, is involved in the response to P depletion. PtrA is a member of the cAMP receptor protein transcriptional regulator family that shows homology to NtcA, the global nitrogen regulator in cyanobacteria. To define the role of this regulator, we constructed a mutant by insertional inactivation and compared the physiology of wild-type Synechcococcus sp. WH8102 with the ptrA mutant under P-replete and P-stress conditions. In response to P stress the ptrA mutant failed to upregulate phosphatase activity. Microarrays and quantitative RT-PCR indicate that a subset of the Pho regulon is controlled by PtrA, including two phosphatases, a predicted phytase and a gene of unknown function psip1 (SYNW0165), all of which are highly upregulated during P limitation. Electrophoretic mobility shift assays indicate binding of overexpressed PtrA to promoter sequences upstream of the induced genes. This work suggests a two-tiered response to P depletion in this strain, the first being PhoB-dependent induction of high-affinity PO(4) transporters, and the second the PtrA-dependent induction of phosphatases for scavenging organic P. The levels of numerous other transcripts are also directly or indirectly influenced by PtrA, including those involved in cell-surface modification, metal uptake, photosynthesis, stress responses and other metabolic processes, which may indicate a wider role for PtrA in cellular regulation in marine picocyanobacteria. The ISME Journal (2010) 4, 908-921; doi:10.1038/ismej.2010.24; published online 8 April 2010

Swift, H, Palenik B.  1993.  Prochlorophyte evolution and the origin of chloroplasts: Morphological and molecular evidence. Origins of plastids : symbiogenesis, prochlorophytes, and the origins of chloroplasts. ( Lewin RA, Ed.).:123-139., New York: Chapman & Hall Abstract
Price, NM, Harrison GI, Hering JG, Hudson RJ, Nirel PMV, Palenik B, Morel FMM.  1989.  Preparation and chemistry of the artificial algal culture medium Aquil. Biological Oceanography. 6:443-461. AbstractWebsite
Palenik, B, Price NM, Morel FMM.  1991.  Potential effects of UV-B on the chemical environment of marine organisms . Environmental Pollution. 70:117-130.   10.1016/0269-7491(91)90084-a   AbstractWebsite

An increase in ultraviolet-B (UV-B) due to depletion of stratospheric ozone may affect growth of marine phytoplankton by altering the chemistry of their environment. Production of bioactive free radicals, photodecomposition of organic matter, and availability of trace metals are likely to be altered by increased UV-B flux. Such changes to the chemical environment may be both deleterious and benefical to marine phytoplankton. Extracellular free radicals such as OH, Br2-, and CO3- are predicted to have a negligible impact, but superoxide and its decomposition product hydrogen peroxide may react rapidly with cell surfaces and destroy membrane function and integrity. Increased UV-B will enhance the bioavailability of the redox active trace metals Fe and Cu. Thus, in the Fe-limited high latitude ocean, increased Fe availability may promote phytoplankton production, while in other parts of the ocean increased Cu availability may be toxic. Overall, the interdependent direct and indirect effects of UV-B on phytoplanton may compensate for each other and account for the ability of marine ecosystems to be subjected to widely variable UV-B flux without apparent damage.

Palenik, B.  1992.  Polymerase evolution and organism evolution. Current opinion in genetics & development. 2:931-6.   10.1016/s0959-437x(05)80118-2   AbstractWebsite

The continuing exploration of the structure-function relationships of polymerases and the use of polymerases as phylogenetic tools complement each other, as seen in the literature for the past year. DNA-dependent RNA-polymerase gene sequences, in particular, have been used both to define functional domains in the protein encoded and recently to explore fundamental questions in evolution.

Collier, JL, Palenik B.  2003.  Phycoerythrin-containing picoplankton in the Southern California Bight. Deep-Sea Research Part Ii-Topical Studies in Oceanography. 50:2405-2422.   10.1016/s0967-0645(03)00127-9   AbstractWebsite

Flow cytometry was used to examine the distribution of phycoerythrin-rich picophytoplankton. referred to here as Synechococcus, off the Southern California coast during six California Cooperative oceanic Fisheries Investigations (CalCOFI) cruises. Depth profiles revealed that Synechococcus was most abundant in the surface mixed layer, gradually disappearing with depth below the thermocline. Within the surface mixed layer, Synechococcus abundance was generally greater and more variable at stations shoreward of the California Current than at stations offshore of it. In waters associated with the California Current not impacted by upwelling, Synechococcus abundance increased with increasing bulk chlorophyll. In contrast, Synechococcus abundance declined with increasing bulk chlorophyll at stations that were impacted by upwelling. Synechococcus at stations impacted by upwelling also had more phycoerythrin per cell than at non-upwelling stations. Offshore of the California Current, Synechococcus cells in waters intruding from the Central North Pacific displayed higher side-scatter relative to forward scatter than did Synechococcus cells elsewhere in the region. Flow cytometrically distinct Synechococcus cell types were also detected below the thermocline at most of the stations where depth profiles were analyzed. These patterns in Synechococcus abundance and cellular characteristics might reflect physiological and/or genetic differences among Synechococcus associated with the various water masses that comprise the CalCOFI region. The data presented here provide a framework from which to launch more detailed and mechanistic studies examining the role of Synechococcus in the CalCOFI ecosystem. (C) 2003 Elsevier Ltd. All rights reserved.

Dyhrman, ST, Palenik B.  1999.  Phosphate stress in cultures and field populations of the dinoflagellate Prorucentrum minimum detected by a single-cell alkaline phosphatase assay. Applied and Environmental Microbiology. 65:3205-3212. AbstractWebsite

Alkaline phosphatase activity is a common marker of phosphate stress in many phytoplankton, but it has been difficult to attribute alkaline phosphatase activity to specific organisms or groups of phytoplankton in the field with traditional biochemical procedures, A ne cv alkaline phosphatase substrate, ELF-97 (enzyme-labeled fluorescence), shows promise in this regard. When a phosphate group is cleaved from the ELF-97 reagent, the remaining molecule precipitates near the site of enzyme activity, thus fluorescently tagging cells with alkaline phosphatase activity. We characterized ELF-97 labeling in axenic cultures of a common dinoflagellate, Prorocentrum minimum, in order to understand ELF-97 labeling dynamics when phosphate nutrition varies. Enzyme activity, as detected by ELF-97 labeling, appears to be induced in late-log- or early-stationary-phase cultures if cells are grown in low-phosphate media and is lost when phosphate-stressed cells are refed with phosphate, ELF-97 appears to label an inducible intracellular alkaline phosphatase in P, minimum based on confocal microscopy studies. This may limit the use of this reagent to organisms that lack high levels of constitutive intracellular phosphatases, After laboratory cultures were characterized, ELF-97 was used to assay field populations of P, minimum in Narragansett Bay during two 1-week periods, and 12 to 100% of the P. minimum cells were labeled. The level of cell labeling was reduced by 3 days of incubation with added inorganic phosphate. Our results indicate that ELF-97 is an excellent new tool for monitoring phytoplankton phosphate stress in the environment when the data are supported by appropriate laboratory studies.