JAMES R. MANHART

Publications of JAMES R. MANHART

• Isolation and characterization of microsatellite markers for Bothriochloa ischaemum (Poaceae).

  Authors: Sarah Matakis, R Deborah Overath, Brandi Kutil, Alan E Pepper, James R Manhart

  American journal of botany. 06/2011; 98(7):e192-4.

  • Premise of the study: Microsatellite primers were developed for Bothriochloa ischaemum to investigate the structure of invasive populations within Texas and determine the origin of introduction• Premise of the study: Microsatellite primers were developed for Bothriochloa ischaemum to investigate the structure of invasive populations within Texas and determine the origin of introduction from within the native range. • Methods and Results: We adapted the biotinylated nucleotide method of developing an enriched genomic library to isolate and characterize 10 polymorphic microsatellite markers. The number of alleles per locus (A) ranged from five to 18 (mean A = 10.45), expected heterozygosity (H(E)) ranged from 0.620 to 0.895 (mean H(E) = 0.785), and expected heterozygosity corrected for sample size (H(EC)) ranged from 0.635 to 0.909 (mean H(EC) = 0.799). The primers were also tested for amplification in Schizachyrium scoparium var. scoparium, Andropogon gerardii, Bothriochloa saccharoides, and Dichanthium annulatum. • Conclusions: The use of microsatellite markers may assist in understanding the pattern of spread, determining the source of invasive populations, and developing biological control agents for invasive populations of Bothriochloa ischaemum.

• Molecular Characterization of the Calvin Cycle Enzyme Phosphoribulokinase in the Stramenopile Alga Vaucheria litorea and the Plastid Hosting Mollusc Elysia chlorotica.

  Authors: Mary E Rumpho, Sirisha Pochareddy, Jared M Worful, Elizabeth J. Summer, Debashish Bhattacharya, Karen N Pelletreau, Mary S Tyler, Jungho Lee, James R Manhart, Kara M Soule

  Molecular plant. 11/2009; 2(6):1384-96.

  Phosphoribulokinase (PRK), a nuclear-encoded plastid-localized enzyme unique to the photosynthetic carbon reduction (Calvin) cycle, was cloned and characterized from the stramenopile alga VaucheriaPhosphoribulokinase (PRK), a nuclear-encoded plastid-localized enzyme unique to the photosynthetic carbon reduction (Calvin) cycle, was cloned and characterized from the stramenopile alga Vaucheria litorea. This alga is the source of plastids for the mollusc (sea slug) Elysia chlorotica which enable the animal to survive for months solely by photoautotrophic CO(2) fixation. The 1633-bp V. litorea prk gene was cloned and the coding region, found to be interrupted by four introns, encodes a 405-amino acid protein. This protein contains the typical bipartite target sequence expected of nuclear-encoded proteins that are directed to complex (i.e. four membrane-bound) algal plastids. De novo synthesis of PRK and enzyme activity were detected in E. chlorotica in spite of having been starved of V. litorea for several months. Unlike the algal enzyme, PRK in the sea slug did not exhibit redox regulation. Two copies of partial PRK-encoding genes were isolated from both sea slug and aposymbiotic sea slug egg DNA using PCR. Each copy contains the nucleotide region spanning exon 1 and part of exon 2 of V. litorea prk, including the bipartite targeting peptide. However, the larger prk fragment also includes intron 1. The exon and intron sequences of prk in E. chlorotica and V. litorea are nearly identical. These data suggest that PRK is differentially regulated in V. litorea and E. chlorotica and at least a portion of the V. litorea nuclear PRK gene is present in sea slugs that have been starved for several months.

• Horizontal gene transfer of the algal nuclear gene psbO to the photosynthetic sea slug Elysia chlorotica.

  Authors: Mary E Rumpho, Jared M Worful, Jungho Lee, Krishna Kannan, Mary S Tyler, Debashish Bhattacharya, Ahmed Moustafa, James R Manhart

  Proceedings of the National Academy of Sciences of the United States of America. 12/2008; 105(46):17867-71.

  The sea slug Elysia chlorotica acquires plastids by ingestion of its algal food source Vaucheria litorea. Organelles are sequestered in the mollusc's digestive epithelium, where they photosynthesizeThe sea slug Elysia chlorotica acquires plastids by ingestion of its algal food source Vaucheria litorea. Organelles are sequestered in the mollusc's digestive epithelium, where they photosynthesize for months in the absence of algal nucleocytoplasm. This is perplexing because plastid metabolism depends on the nuclear genome for >90% of the needed proteins. Two possible explanations for the persistence of photosynthesis in the sea slug are (i) the ability of V. litorea plastids to retain genetic autonomy and/or (ii) more likely, the mollusc provides the essential plastid proteins. Under the latter scenario, genes supporting photosynthesis have been acquired by the animal via horizontal gene transfer and the encoded proteins are retargeted to the plastid. We sequenced the plastid genome and confirmed that it lacks the full complement of genes required for photosynthesis. In support of the second scenario, we demonstrated that a nuclear gene of oxygenic photosynthesis, psbO, is expressed in the sea slug and has integrated into the germline. The source of psbO in the sea slug is V. litorea because this sequence is identical from the predator and prey genomes. Evidence that the transferred gene has integrated into sea slug nuclear DNA comes from the finding of a highly diverged psbO 3' flanking sequence in the algal and mollusc nuclear homologues and gene absence from the mitochondrial genome of E. chlorotica. We demonstrate that foreign organelle retention generates metabolic novelty ("green animals") and is explained by anastomosis of distinct branches of the tree of life driven by predation and horizontal gene transfer.

• Mollusc/algal chloroplast symbiosis: how can isolated chloroplasts continue to function for months in the cytosol of a sea slug in the absence of an algal nucleus?

  Authors: Mary E. Rumpho, Elizabeth J. Summer, Brian J. Green, Theodore C. Fox, James R. Manhart

  Zoology.

  A marine sea slug, Elysia chlorotica, has acquired the ability to carry out photosynthesis as a result of forming an intracellular symbiotic association with chloroplasts of the chromophytic alga,A marine sea slug, Elysia chlorotica, has acquired the ability to carry out photosynthesis as a result of forming an intracellular symbiotic association with chloroplasts of the chromophytic alga, Vaucheria litorea. The symbiont chloroplasts (kleptoplasts) are functional, i.e. they evolve oxygen and fix CO2 and actively transcribe and translate proteins for several months in the sea slug cytosol. Considering the dependency of plastid function on nuclear genes, the level of kleptoplast activity observed in the animal cell is quite remarkable. Possible factors contributing to this long-lasting functional association that are considered here include: the presence of an algal nuclear genome in the sea slug, autonomous chloroplasts, unusual chloroplast/protein stability, re-directing of animal proteins to the kleptoplast, and lateral gene transfer. Based on our current understanding, the acquisition and incorporation of intact algal plastids by E. chlorotica is aided by the robustness of the plastids and the long-term functional activity of the kleptoplasts appears to be supported by both plastid and protein stability and contributions from the sea slug.

• Isolation and characterization of 10 polymorphic microsatellites in saltcedars (Tamarix chinensis and Tamarix ramosissima)

  Authors: JOHN F. GASKIN, ALAN E. PEPPER, JAMES R. MANHART

  Tamarix ramosissima and Tamarix chinensis are invasive weed species in western North America. Previous studies based on single locus DNA sequence data revealed some information about the invasionTamarix ramosissima and Tamarix chinensis are invasive weed species in western North America. Previous studies based on single locus DNA sequence data revealed some information about the invasion process, but multilocus markers can provide additional information about levels of introgression and genotype origins. We have developed primers that amplify 10 polymorphic microsatellite loci from T. ramosissima; these primer pairs also successfully amplify polymorphic microsatellites from the closely related T. chinensis, a species that forms hybrids with T. ramosissima in the western USA.

• Latitudinal variation in cold hardiness in introduced Tamarix and native Populus.

  Authors: Jonathan M. Friedman, James E. Roelle, JOHN F. GASKIN, ALAN E. PEPPER, JAMES R. MANHART

  To investigate the evolution of clinal variation in an invasive plant, we compared cold hardiness in the introduced saltcedar (Tamarix ramosissima, Tamarix chinensis, and hybrids) and the nativeTo investigate the evolution of clinal variation in an invasive plant, we compared cold hardiness in the introduced saltcedar (Tamarix ramosissima, Tamarix chinensis, and hybrids) and the native plains cottonwood (Populus deltoides subsp. monilifera). In a shadehouse in Colorado (41°N), we grew plants collected along a latitudinal gradient in the central United States (29–48°N). On 17 occasions between September 2005 and June 2006, we determined killing temperatures using freeze-induced electrolyte leakage and direct observation. In midwinter, cottonwood survived cooling to −70°C, while saltcedar was killed at −33 to −47°C. Frost sensitivity, therefore, may limit northward expansion of saltcedar in North America. Both species demonstrated inherited latitudinal variation in cold hardiness. For example, from September through January killing temperatures for saltcedar from 29.18°N were 5–21°C higher than those for saltcedar from 47.60°N, and on September 26 and October 11, killing temperatures for cottonwood from 33.06°N were >43°C higher than those for cottonwood from 47.60°N. Analysis of nine microsatellite loci showed that southern saltcedars are more closely related to T. chinensis while northern plants are more closely related to T. ramosissima. Hybridization may have introduced the genetic variability necessary for rapid evolution of the cline in saltcedar cold hardiness.