Overcoating of Toxoplasma Parasitophorous Vacuoles with Host Cell Vimentin Type Intermediate Filaments

The interaction between the Toxoplasma parasitophorous vacuole and vimentin-type intermediate filaments in Vero cells was investigated via immunofluorescence microscopy. A significant rearrangement of host cell vimentin around the Toxoplasma parasitophorous vacuoles occurs throughout the course of infection. Host cell vimentin associates with the parasitophorous vacuoles within an hour after invasion. This vimentin overcoating of the vacuole is initiated at the host cell nuclear surface. During parasite multiplication, vimentin retains a closely defined association with the cytosolic surface of the parasitophorous vacuole. In addition, the vimentin intermediate filaments originating from the host cell nuclear surface are progressively rearranged around the enlarging parasitophorous compartment. During infections, the order of vimentin cytoskeleton is normal throughout the cell and appears redefined only at the vicinity of the parasitophorous vacuole. Depolymerization of the intermediate filaments was achieved with the phosphatase inhibitors okadaic acid and calyculin A. Disruption of the intermediate filament networks resulted in displacement of the parasitophorous vacuoles from the host cell nuclear surface. The data indicate that host cell vimentin binds to the Toxoplasma parasitophorous vacuoles and that the host intermediate filament network serves to dock the parasite compartment to the host cell nuclear surface.     

Microsporidian Spore Discharge and the Transfer of Polaroplast Organelle Membrane into Plasma Membrane

Electron microscopic examinations of Glugea hertwigi and Spraguea lophii spores indicated the presence of a single plasma membrane; however, this membrane remained in the spore during the discharge of the sporoplasm from the spore. Although discharged spores retained the old plasma membrane, the extruded sporoplasms acquired a new plasma membrane. In order to determine where the new plasma membrane came from, we used two fluorescent probes with membrane affinities. The markers were tested on unfired and discharged spores. The probe, N-phenyl-1-naphthylamine (NPN), labeled the polaroplast membrane in addition to the apolar groups in the posterior vacuoles of unfired spores. After spore discharge, NPN label disappeared from the spore ghosts except for a slight fluorescence on residual plasma membranes. Much of the NPN-labeled membrane reappeared after spore discharge on the outer envelope of discharged sporoplasms. The probe chlorotetracycline (CTC) labeled calcium-associated membranes of spore polaroplasts. During spore discharge, the CTC fluorescence shifted from the polaroplast organelle of unfired spores to the outer envelope of discharged sporoplasms. These results indicate that the polaroplast organelle may provide the new plasma membrane for discharged microsporidian sporoplasms.     

Small Mammal Responses to Fine Woody Debris and Forest Fuel Reduction in Southwest Oregon

Abstract: Despite its importance for wildlife, most forests in the Pacific Northwest contain low volumes of large downed wood compared to fine woody debris (FWD). We used a replicated experiment to compare short-term responses of deer mice (Peromyscus maniculatus) and western red-backed voles (Clethrionomys californicus) among 3 arrangements of FWD: piled, lopped and scattered, and pile burning, a commonly used method of fuel reduction in commercial Douglas fir (Pseudotsuga menziesii) forests in southwest Oregon, USA. We assessed habitat use, density, and survival of mice and voles during 2 consecutive summers (Jun—Aug 1999 and 2000). Both mice and voles used FWD cover disproportionately from its availability, and they differed in their responses to specific FWD arrangements. Mice used piled FWD (proportional use = 37.0%, 90% CI = 33.0–44.0) 43% more than expected (26.0). Number of mice captured (x̄ = 1.9 mice, 90% CI = 1.5–2.5) and index of home range size (x̄ = 4.8 m, 90% CI = 0.7–8.9) at individual FWD piles decreased up to 16% and increased up to 50%, respectively, for each 1-m increase in distance from piles. Voles used all FWD cover classes in proportion to availability, but number of voles captured increased slightly (x̄ = 0.016 voles/m, 90% CI = 0.001–0.031) for each 1-m increase in distance from piles. Piled FWD had no discernable effect on population density and apparent survival of mice, but analyses had low power (0.25, 0.67). Our results suggest that piling FWD would benefit deer mice, whereas lopped and scattered FWD might benefit voles. Thus, a combination of methods to reduce fire risk should be considered to accommodate multiple small mammal species. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):625–632; 2008)     

Post-Pleistocene evolution of Bornean shrews Crocidura foetida (Mammalia, Soricidae)

Fossil mandibles of the Bornean shrew Crocidura foetida recovered from excavations at the west mouth of Niah cave, Sarawak, Malaysia, show that the late Pleistocene population at this lowland location was comparable in size with the large subspecies Crocidura foetida doriae , presently occurring at inland, upland locations. Two Holocene specimens fall in the size range of the smaller lowland subspecies C. f. foetida . Comparable post-Pleistocene size-reduction is known among other mammals of Borneo, but this is the first instance of dated examples. The evolutionary trend conforms with Bergmann's 'rule' but, other than climate change, no selective agent is apparent.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 413–419.     

"Our Beer": Ethnographic Brands in Postsocialist Georgia

Although Georgia is known for its wines, industrial production of beer far outstrips industrial wine production for local markets: wine consumption occurs in ritual contexts in which new wine, typically purchased from peasant producers, is preferred; bottled, aged wines are primarily for exports. Beer, therefore, is a key area in which industrial production for indigenous consumers has been elaborated. Such goods are packaged and presented as being both ecologically "pure" and following "traditional" methods, often referencing "ethnographic" materials about traditional life in brand images, even as they proclaim their reliance on Western technologies.     

Ultrastructure of the Peripheral Zone of a Glugea-Induced Xenoma*

SYNOPSIS. The Glugea stephani-induced xenoma in the winter flounder, Pseudopleuronectes americanus, is a large spherical host-parasite complex, up to 4.0 mm in diameter, with the host and parasite components of the xenoma being most active in the peripheral zone. The xenoma has an extensive periodic acid-silver methenamine-positive surface coat covering the plasma membrane. The surface of this membrane is amplified by the presence of numerous folds and fine tubular extensions. The peripheral zone of the xenoma contains many host-cell mitochondria in addition to numerous microsporidan parasites. At the ultrastructural level, the peripheral zone of the host-cell cytoplasm appears normal. Inside the peripheral region of the 0.4–1.0 mm xenoma, the host-cell component largely disintegrates in the presence of microsporidan parasites undergoing sporogenesis.