The fungal genus Puccinia contains more than 4,000 species. Puccinia triticina, causal agent of wheat leaf rust, is an economically significant, biotrophic basidiomycete. Little is known about the molecular biology of this group, and tools for understanding gene function have not yet been established. A set of parameters was established for the transient transformation of urediniospores. The expression of three heterologous promoters (actin, elongation factor 1-alpha, and Hss1, Heat Shock 70 protein), derived from Puccinia graminis, was evaluated along with the potential for insertional mutagenesis. The UidA (GUS) gene was used as a marker for transient expression. When transferred into P. triticina urediniospores, transient expression was observed across four helium pressures using one size of gold and three sizes of tungsten microprojectiles. Each of the three promoters displayed strong transient expression in germinated urediniospores; however, higher numbers of GUS-positive urediniospores were observed when either the actin or Hss1 promoters were used. Possible concomitant insertional mutagenesis of several avirulence genes was selected in wheat cultivars harboring the cognate resistance genes. Using a linearized cloning plasmid, stable integration into the genome was achieved as demonstrated by PCR and sequencing analysis.
Organic material exposed within a small swale fill in Pit 6 of the Wedron Silica Sand Co. near Wedron in LaSalle County, Illinois, includes well-preserved pollen, plant macrofossils, and insect remains. This material occurs in slackwater sediment in the lower part of the Peddicord Formation, which was deposited as existing valleys were dammed by fluvial aggradation during the initial late Wisconsinan advance of Laurentide ice into the Wedron area. Wood from the organic horizon has a radiocarbon age of 21,460 ± 470 yr B.P. (ISGS-1486). The pollen spectrum is dominated byPicea, Pinus, and Cyperaceae. Plant macrofossils comprise a mix of boreal-forest taxa, includingPicea, Larix laricina, and the mossCampylium stellatum; subarctic species includingBetula glandulosa, Empetrum nigrum, andSelaginella selaginoides; along with the predominantly arcticVaccinium uliginosumvar.alpinum, Dryas integrifolia, andRhododendron lapponicum. The insect fauna contains the western montane ground beetleOpisthius richardsoni; several arctic-subarctic ground beetles includingDiacheila polita, Helophorus sibiricus, andPterostichus (Cryobius) caribou; and a diverse assemblage of insects that today inhabit the boreal forest. We interpret the biotic record to record a phase in the transition from closed boreal forest to open tundra as climatic conditions deteriorated in advance of continental glaciation.
Studies of approximately 7000 Aedes triseriatus (Say) and Aedes hendersoni Cockerell larvae showed that the frequencies of occurrence (expressed as percentages) of several morphological characteristics among populations of each species are quite constant. In populations of unmixed A. triseriatus, attached acus, S-branched lateral hair, 2-branched siphonal tuft, unequal gill length_, and 6 pairs of 3-to multiple-branched ventral brush hairs predominated. All of these larvae were dark in color when alive. In unmixed A. hendersoni populations, well detached acus, 2-and 3-branched lateral hairs, 3-branched siphonal tuft, equal gill length, and 5 pairs of 2-to 3branched ventral brush hairs predominated; all of these larvae were light in color when alive. Laboratoryproduced hybrids exhibited predominant percentages of several characteristics, including color, that were intermediate between those of the parent stocks. Less than 0.5% of field-collected larvae appeared to be hybrids. Hybrids showed adult mesoscutal patterns intermediate between A. triseriatus and A. hendersoni. Two mesoscutal patterns were noted in A. hendersoni adults. Breland' s (1960) restoration of the name A&es hendersoni Cockerell to full specific rank resulted in reports of this species throughout much of the United States (Hedeen 1963, Truman and Craig 1968, Zavortink 1972). The apparently similar habitat of this species and taxonomic relationship to Aedes triseriatus (Say) has necessitated great caution in identifying specimens of each species. Hybridization in the laboratory is possible (Truman and Craig 1968) and apparently occurs on occasion in the field. It was necessary to know which species were present in Lacrosse Encephalitis foci in Wisconsin since laboratory transmission work was being conducted with stock from various southwestern Wisconsin sites. A project was initiated to identify and characterize populations of both species in Wisconsin, to determine if hybridization occurred in any of our study areas and to assure that laboratory stocks were pure or unmixed. MATERIALS AND METHODS Collection sites were described previously (Hanson and Hanson 1970, Watts et al. 1974, Garry 1974)." Larval populations at these sites were sampled by standard methods throughout southwestern Wisconsin. A minimum of 1 of every 10 larvae per sample was examined and characterized, and many samples were examined in their entirety. Since some discoloration was evident on occasion with preserved material, and gill breakage and loss of hairs occurred, live larval characterization was emphasized, although larvae collected in previous years and stored in ethanol were also examined. Many of the larvae examined in this study were kept alive and the adults used for virus transmission studies and hybridization matings. l Supported in part by Nat. Inst. of Health Grant AI-07453.
A Twocreekan organic horizon, which is underlain by till of the Haven Member and overlain by till of the Two Rivers Member of the Kewaunee Formation, was investigated near Kewaunee, Wisconsin. Wood from this horizon was dated at 11,700 ± 110 B.P. (ISGS-1061) and 11,650 ± 170 B.P. (ISGS-1234). The insect fauna from the Kewaunee site has many elements in common with the insects from the type section of the Two Creeks Forest Bed, 14 km to the south. These include the northwestern carabid Asaphidion yukonense, northern carabids Carabus taedatus and Bembidion grapii, and the northern staphylinid Acidota quad rata. In contrast, the Kewaunee site fauna appears to have inhabited a somewhat colder environment, as suggested by the occurrence of the carabids Cymindis unicolor and Pterostichus (Cryobius) spp. We interpret the Kewaunee specimens of aquatic, water-marginal, and upland species to represent an allochthonous rather than an autochthonous assemblage.
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