Botany & plant ecology.
Unlike animal cells, plant cells display a variety of microtubule arrays throughout the cell cycle, yet characterization of the plant microtubule organizing center remains elusive. Katanin is a microtubule severing ATPase, known to localize at the centrosome in animal cells. Katanin has two subunits, one of which, p60, has catalytic activity. An Arabidopisis thaliana homolog of katanin p60 has been identified and sequenced, and named AtKSS (McClinton et al., 2001). Current research aims to analyze the conservation of the katanin p60 throughout the plant kingdom by means of degenerate PCR probing of seedling tissue cDNA. From the AtKSS amino acid sequence, preliminary blasts of 19 angiosperm databases and 2 gymnosperm databases all show identities of y73%. Alignment of these sequences has allowed us to design degenerate primers which we are using to obtain full-length cDNA sequences of p60 homologs. Analysis of sequences shows a high degree of conservation in important regions, mainly the CAD region, which identifies p60 as an AAA protein, and the microtubule binding region. That katanin p60 homologues are present in two plant phyla, in addition to several animal phyla is a strong indication that this protein is conserved throughout the plant kingdom, and perhaps among eukaryotes.
Do Plants Contain Katanin p80 Homologous Genes? Nathaniel Horwitz and Regina McClinton, Grand Valley State University, Cell and Molecular Biology Program, Allendale, MI 49401
Katanin is a microtubule severing ATPase. It is also a heterodimer, whose catalytic subunit, p60, has orthologs in both animals and plants. However the larger subunit, p80, has not been as well analyzed. The p80 subunit directs katanin to the centrosome in animal cells, the site of microtubule organization. While some green algae still have centrosomes, most plants do not. Should a p80 homolog be present in plants, it might be involved in microtubule organization, and help to define the microtubule organizing center in plants. As an initial step we are analyzing angiosperms for the presence of p80 homologous genes, using degenerate PCR primers to probe seedling tissue cDNA. Already a p80 homolog has been identified in Arabidopsis, and shown to interact with the p60 homolog, AtKSS (Bourqin et al, 2003). We will report on the presence of p80 homologs in angiosperms, and consider how well it is conserved between dicots and monocots.
Exploring the Basis of Hybrid Speciation in Plants; Genomic In-situ Hybridization Studies of Senecio Spp. as Models. Keith Williams, University of Michigan--Flint, Department of Biology, Flint, MI 48502
The chromosomal basis of speciation in two taxa of hybrid origin, Senecio squalidus and Senecio baxteri, was investigated using genomic in-situ hybridization (GISH) techniques. These taxa are being examined for use as biological models of speciation in plants, S. squalidus being of principle interest in the often overlooked area of homoploid speciation events among plants. Preliminary probing revealed chromosomal abnormalities during meiosis in pollen mother cells of each of these plants, but was unable to produce a definitive identification of the mispaired chromosomes utilizing genomic DNA isolated from each of the respective parental species as probe. This indicates a need for greater stringency in future GISH studies of Senecio hybrids, and reveals potential areas of concern in further use of Senecio as a model for plant speciation.
Groundwater and Sediment Nutrient Influences on Submersed Aquatic Macrophyte Growth in White Lake, Muskegon County, Michigan. J. L. Jermalowicz-Jones and M.R. Luttenton, Grand Valley State University, Department of Biology, Allendale, MI, 49401
Increased aquatic macrophyte densities in septic discharge areas support the hypothesis that nutrients present in the leachate and perhaps sediment, may be responsible for substantial macrophyte growth in White Lake, Muskegon County, Michigan. Submersed aquatic macrophyte growth responses to groundwater and sediment TP and SRP were measured during the summer of 2005 to assess the impacts of these nutrient sources on observed accelerated macrophyte growth within the littoral zone of White Lake. Underwater seepage meters were placed at control and septic discharge sites to measure P inputs which ranged from 27-95 mg m-2 yr-1 for TP and 6-55 mg m-2 yr-1 for SRP. A multiple linear regression model is being developed to determine which environmental variables are better predictors of submersed aquatic macrophyte growth. A pilot mesocosm study using tanks with transplanted Vallisneria americana plants on different sediment sites taken from control and septic areas showed a significant sediment growth effect (P <.05) on sediments which contained septic leachate.
Effects of Logging at Brandt Woods, Calhoun County, Michigan. Hillary K. Burgess and J. Dan Skean, Jr., Albion College, Department of Biology, Albion, MI 49224
Brandt Woods is a ca. 100-acre (40 ha) tract located in Sections 7 & 8, T2S, R4W in Sheridan Township, which is owned by the Calhoun Conservation District and operated as a demonstration woodlot and summer outdoor education center. Approximately 70 acres (28 ha) is beech-maple forest. The woods has been visited by Albion College classes since the 1950s and studied floristically since 1988. In May and September, 1991, the point-quarter method was used to sample woody plants (> 2.5 cm dbh) in the woods; the five species with the highest importance values (rel. density + rel. dominance + rel. frequency) were Acer saccharum Marsh. (110.1), Acer saccharinum L. (24.1), Ulmus americana L. (22.2), Tilia americana L. (22.0), Acer rubrum L. (19.7), and Fagus grandifolia Ehrh. (17.1). Selective logging took place in 1997, 2000 and 2004 in three different tracts of the woods. Vegetation was re-sampled in 2004, with the addition of plot sampling of understory species in the different logging tracts of various ages. Changes in woody plant composition were documented. GIS was used to create a map of the woods showing the different logging areas.
A Comparison of Canopy Vegetation in Wetland Forest Habitats in an Urban Natural Area. Katherine L. Evans and Orin G. Gelderloos, University of Michigan-Dearborn, Department of Natural Sciences, Dearborn, MI 48128
The University of Michigan-Dearborn is steward of approximately 300 acres of Natural Area along the Rouge River, including extensive forested floodplain habitat. A comparison of the canopy vegetation (trees >10 cm diameter) in upstream and downstream sections of the floodplain showed a difference in species composition. In the downstream floodplain with a shorter hydroperiod, the most common species are Silver Maple (Acer saccharinum), Boxelder (Acer negundo), Red Ash (Fraxinus pennsylvanica), and Red Maple (Acer rubrum). In the upstream floodplain with a longer hydroperiod the most numerous species are American elm (Ulmus americana), and Red Ash (Fraxinus pennsylvanica). Calculations of dominance by basal area included the addition of Eastern Cottonwood (Populus deltoidis), and Crack Willow (Salix fragilis). The majority of the trees in the upstream floodplain are dead due to Dutch Elm disease and the Emerald Ash Borer, which opened the canopy in the recent years to the invasion of Reed Canary Grass (Phalaris arundinacea), Yellow Iris (Iris psuedacorus), Phragmites (Phragmites communis), and some Purple Loosestrife (Lythrium salicaria). Future studies will monitor the successional changes in the upstream floodplain.
The Jensen Landscape at Henry and Clara Ford's Home: An Eight-year Comparison of Canopy Vegetation. Jeffrey Boutain and Orin G. Gelderloos, University of Michigan-Dearborn, Department of Natural Sciences, Dearborn, MI 48128
The initial inventory in 1998 of the canopy trees >10 cm diameter in the Jensen landscape at the Henry and Clara Ford Estate on the University of Michigan-Dearborn indicated that Jensen vision of a mesic forest characteristic of southeast Michigan was fulfilled. A slightly more extensive inventory in 2005 found 2,088 trees of 60 species. The most abundant species was Sugar Maple (Acer saccharum) at 17.5% followed by Silver Maple (Acer saccharinum) at 8.8%, White Ash (Fraxinus americana) at 8.2% most of which are dead due to Emerald Ash Borer, Boxelder (Acer negundo) at 8.1%, Hop-hornbeam (Ostrya virginiana) at 5.4%, Red Oak (Quercus rubra) at 5.3% and Black Walnut (Juglans nigra) at 4.8%. Analysis of numbers of trees in each 10 cm size category indicate that recruitment of new trees into canopy status is occurring in all of the major species except Red Oak indicating a perpetuation of the mesic forest. Comparison of the increase in biomass of individual trees over the past seven in three sections of the landscape showed that expected growth rates are occurring.
An Ecological Study and Mitigation of a Woodlot. Rachel Vannette, Randy VanDragt and John Beebe, Calvin College, Department of Biology, Grand Rapids, MI 49546
In this study, we describe the ecological parameters and composition of an old wooded site on the Calvin College campus, slated to be cut down for the college's new health and wellness center. We found that this nearly 200 year-old oak-hickory forest has remained surprisingly ecologically intact despite many encroachments upon it. Through this study of the ecology and composition of the forest and through the description of various soil and light parameters, our main goal is the development of a mitigation plan for this woodland and adjacent lawn area. We also focused on native shrub propagation, mainly cuttings, to generate identical material to woodlot flora for this mitigation project. We found hormone levels needed to stimulate rooting for six shrub species important to this habitat type, and focused especially on the propagation and ecology of Staphylea trifolia, one of the more significant shrubs growing in the woodlot. Using environmental parameters from this wooded area, we have developed specific goals for the mitigation plan. Following hydrological modification of new sites and removal of invasive species, we will transplant propagated plants and forest soils containing flora to mitigation areas.
Stimulated Growth of Azotobacter vinelandii by Root Extracts of Ailanthus altissima. Jeremy May, Rod Morgan, Preston Aldrich, and Gary K. Greer, Grand Valley State University, Department of Biology, Allendale, MI 49401
Ailanthus altissima is an invasive Asiatic tree whose presence in forests of the Eastern U.S. is considered a growing threat. Ailanthus invasiveness is linked to a suite of life history and allelochemical traits and an ability to grow rapidly in a wide-range of soils. Ailanthus vigor on nutrient poor soils may result from an ability to induce increased rates of nitrogen-fixation by neighboring free-living soil bacteria such as Azotobacter vinelandii. To explore this possibility, we compared growth of A. vinelandii grown on selective media (control) with that observed on selective media enhanced with aqueous extracts of pulverized Ailanthus roots (treatment). Experiments were conducted with both agar and aqueous suspensions and across a range of dilutions from 1:500 to 1:5,000. Results from both experimental approaches revealed a stimulatory effect by Ailanthus root extracts on A. vinelandii growth. Whether the observed increase in A. vinelandii resulted in increased nitrogen availability in the media and whether Ailanthus exudes the active compound into its rhizosphere in sufficient concentrations to stimulate neighboring Azotobacter remain unknown.
Stimulation of Legume Nodulation by Root Exudates of Ailanthus altissima. Jeff Dock, Heather Reed, and Gary K. Greer, Grand Valley State University, Department of Biology, Allendale, MI 49401
Vigorous growth in nutrient poor soils by Ailanthus altissima may result from signal-induced nodulation and subsequent nitrogen-fixation by neighboring legumes. To explore this possibility, we paired Robinia psuedoacacia seedlings with those of Liriodendron tulipifera (control) and Ailanthus (treatment) in a 2x2 common garden experiment that employed high versus low watering regimes. 2-way ANCOVA revealed a significant treatment interaction; nodulation was greatest in the Liriodendron x low water and Ailanthus x high water treatments. These results are consistent with previously observed phytotoxicity of Ailanthus in dry habitats, but do not provide clear evidence of Ailanthus-stimulated nodulation. A greenhouse experiment was subsequently conducted in which Trifolium repens plants were grown from seed in sandxtop-soil mix and watered with: (1) tap water that had been poured through pots containing the same soil mix (control) or (2) pots of the same mix that also contained an Ailanthus sapling (treatment). All 30 treatment plants possessed nodules, whereas only 2/30 control plants possessed nodules. These results indicate that Ailanthus alters surrounding soil in a manner that stimulates nodulation in T. repens.
Shade Requirements for the Suppression of Buckthorn Seedling Growth. Erica Vandergaast and David Dornbos, Calvin College, Department of Biology, Grand Rapids, MI 49546
This summer I worked to remove buckthorn, an invasive plant that has spread throughout much of the United States. I aimed to determine the relationship between sun exposure, photosynthesis rate, and growth of glossy buckthorn seedlings, and to compare buckthorn photosynthesis rates and the rates of native species. If we can quantify the minimum light requirement of buckthorn seedlings, we will know if shade could prevent growth. Comparison to native species will identify those species most useful in restoring infested areas. I set up shade tents at six sites, with four different levels of shade at each site then measured photosynthesis rates. I also measured plant growth, and compared the photosynthesis rates of native species to buckthorn. My study of photosynthesis showed that both species of buckthorn have high C[O.sub.2] exchange rates. However, there are some natives capable of competing. The two best competitors are buttonbush and highbush cranberry. Treatment did have an effect on the photosynthesis rate. In general, increasing shade decreased photosynthesis rate. What I found surprising, however, was that seedling growth did not seem to be affected by shade level, and other factors must be involved in growth. Overall, this research provided some data that can be used in restoration planning.
Efficacy of Glyphosate on the Control of Buckthorn Shrubs. Drew W. Moeller and David L. Dornbos Jr., Calvin College, Department of Biology, Grand Rapids, MI 49546
Buckthorn (Rhamnus cathartica) shrubs are frequently the target of restoration activities due to its invasiveness and competitive superiority over native flora. A preferred control method involves treatment of cut stumps with the systemic herbicide glyphosate, but success is variable. Mature buckthorn shrubs were cut in soils varying in moisture content between 15 and 80% variable water content (VWC) and treated with 0 to 41% glyphosate. Only control plants exhibited re-growth after ten weeks, but 40% of stumps treated with 10% glyphosate in moist soil exhibited re-growth after 20 weeks, consistent with observations suggesting glyphosate was less efficacious in high soil moisture soils. Then, field-grown buckthorn seedlings were cut and treated with various glyphosate concentrations, in different soil moistures, and after various time delays post- cutting. Plant sap extracted from the roots after 48 hours using a pressure bomb was assayed for glyphosate using an ELISA test. Glyphosate was detected in sap from lower percentages of plants as soil moisture increased from 15 to 80% VWC and herbicide application delay increased from 0 to 90 minutes. These results suggest that restoration of moist soils infested with buckthorn utilize a minimum of 20% glyphosate applied to stumps within fifteen minutes of cutting.
Mid-Spring Burning Reduces Spotted Knapweed and Increases Native Grasses on a Degraded, Knapweed-Infested Site. Neil W. MacDonald, Brian T. Scull, and Scott R. Abella, Grand Valley State University, Department of Biology, Natural Resources Management Program, Allendale, MI 49401
Infestations of the exotic perennial Centaurea maculosa Lam. (spotted knapweed) hinder the restoration and management of native ecosystems on droughty, infertile sites throughout the Midwestern United States. We studied the effects of annual mid-spring burning on spotted knapweed persistence in 48 plots seeded to native warm-season grasses on a severely degraded, knapweed-infested site in western Michigan for three years (2003-2005). In mid-August of each year, we counted seedling, juvenile, and adult knapweed and sampled biomass by major species groups on four quadrats per plot. In the first year, burning reduced knapweed biomass by 90%, and maintained 80% lower knapweed biomass as compared to unburned plots in subsequent years. Total knapweed densities were reduced on burned plots by 62 to 87% compared to unburned plots in all years. By 2005, mean adult knapweed densities on both burned (0.4 m-2) and unburned plots (1.3 m-2) were reduced to levels where the seeded grasses should persist with normal management, including the use of prescribed fire. These results support the use of burning to help establish and maintain fire-adapted native plant communities on knapweed-infested sites by reducing knapweed density, biomass, and seedling recruitment, and by further shifting the competitive balance toward native warm-season grasses.
The Use of Ecological Detrended Correspondence Analysis (DCA) in Evaluating the Dissemination of Ethnobotanical Knowledge Within the Anishinaabek Great Lakes Indian Culture. Scott Herron, The University of Michigan Biological Station and Ferris State University, Department of Biology, Big Rapids, MI 49307
Ecologists often use a quantitative technique known as Detrended Correspondence Analysis (DCA) to perform multivariate analysis of ecological data. This technique arranges scientific species along gradients of environmental variables within a community. It basically compares samples of plots to the species found within those plots. I have extended the use of DCA to compare samples of human informants (equivalent to plots), where the knowledge of plant use exists, to folk species (equivalent to scientific species). This analysis allowed for determination of what environmental and cultural variables most predicted and affected the control and dissemination of specialized uses of plants only communicated thru the oral tradition in the modern day Great Lakes Indian culture. The Anishinaabek culture consists of the Ojibwe, Odawa, Potawatomi, and Cree tribes. I conducted four years of ethnographic fieldwork with seven Anishinaabek communities in Michigan, Wisconsin, and Ontario from 1998-2002. The results indicated that the cultural-environmental variables explaining the most clustering on DCA ordination scatterplots were (1) geographic region (i.e. Lake Michigan region), (2) community affiliation (i.e. Bad River Band of Lake Superior Ojibwe), and (3) informant type (i.e. each community clustered around one or more elders often classified as medicine persons).
Helitrons: Surreptitious Abductor and Mobilizers of Maize Gene Sequences. Natalie Jameson, Genevieve Cahoon, and Shailesh Lal, Oakland University, Department of Biological Sciences, Rochester, MI 48309
Transposable elements constitute the major portion of many eukaryotic genes and have played essential role in genome evolution. Until recently virtually all eukaryotic transposable elements could be broadly grouped into two classes based on the mechanistic mode of their transposition. Class I elements transpose via RNA intermediate catalyzed by reverse transcriptase enzyme encoded by an autonomous member of the family. Elements of Class II transpose via DNA intermediate catalyzed by transposase encoded by autonomous element. Recently a novel family of eukaryotic transposable elements, termed Helitrons was discovered. These bear no apparent similarity to the known Class I and II groups of elements. These were initially discovered by computational analysis of the complete genome sequence of Arabidopsis and C. elegans. We recently described two maize mutants caused by the recent insertion of Helitrons. This provided evidence that Helitrons are active in the present day maize genome. In this report, we have used the conserved terminal ends of Helitrons to search the maize genome database for other family members. Our data indicates that Helitrons are highly abundant and by frequently capturing and multiplying gene segments have caused massive changes of the maize genome.
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|Date:||Jan 1, 2008|
|Previous Article:||Biochemistry & Molecular Biology.|