bluuebunny/crossref_metadata_2025 huggingface dataset:
A Mouse-Passaged Dengue Virus Strain with Reduced Affinity for Heparan Sulfate Causes Severe Disease in Mice by Establishing Increased Systemic Viral Loads
Authors: Prestwood Tyler R. , Prigozhin Daniil M. , Sharar Kristin L. , Zellweger Raphaël M. , Shresta Sujan
Published: June 2008

The four serotypes of dengue virus (DENV1 to DENV4) cause extensive morbidity and mortality. A major obstacle to studying disease pathogenesis and developing therapies has been the lack of a small-animal model. We previously reported isolation of a DENV2 strain, obtained by passaging a clinical isolate between mosquito cells and mice, that caused severe DENV disease in mice and contained multiple mutations, including many in domain II of the envelope (E) protein. Here, we describe a recombinant virus, differing from the non-mouse-passaged virus by two mutations in the E protein, that induces vascular leakage and tumor necrosis factor alpha (TNF-α)-mediated lethality, while the non-mouse-passaged virus causes paralysis. This recombinant virus has a weaker affinity for heparan sulfate, resulting in an increased serum half-life, higher systemic viral loads, and high levels of TNF-α in the serum of infected mice. These results exemplify the role of the E protein in modulating virion clearance and connect the effect of clearance on the systemic viral loads responsible for severe disease manifestations.
Efficient Multiplication of Human Metapneumovirus in Vero Cells Expressing the Transmembrane Serine Protease TMPRSS2
Authors: Shirogane Yuta , Takeda Makoto , Iwasaki Masaharu , Ishiguro Nobuhisa , Takeuchi Hiroki , Nakatsu Yuichiro , Tahara Maino , Kikuta Hideaki , Yanagi Yusuke
Published: June 2008

Human metapneumovirus (HMPV) is a major causative agent of severe bronchiolitis and pneumonia. Its fusion (F) protein must be cleaved by host proteases to cause membrane fusion, a critical step for virus infection. By generating Vero cells constitutively expressing the transmembrane serine protease TMPRSS2 and green fluorescent protein-expressing recombinant HMPV, we show that TMPRSS2, which is expressed in the human lung epithelium, cleaves the HMPV F protein efficiently and supports HMPV multiplication. The results indicate that TMPRSS2 is a possible candidate protease involved in the development of lower respiratory tract illness in HMPV-infected patients.
Hypermutation of an Ancient Human Retrovirus by APOBEC3G
Authors: Lee Young Nam , Malim Michael H. , Bieniasz Paul D.
Published: June 2008

Human endogenous retroviruses (HERVs) comprise approximately 8% of the human genome, but all are remnants of ancient retroviral infections and harbor inactivating mutations that render them replication defective. Nevertheless, as viral “fossils,” HERVs may provide insights into ancient retrovirus-host interactions and their evolution. Indeed, one endogenous retrovirus [HERV-K(HML-2)], which has replicated in humans for the past few million years but is now thought to be extinct, was recently reconstituted in a functional form, and infection assays based on it have been established. Here, we show that several human APOBEC3 proteins are intrinsically capable of mutating and inhibiting infection by HERV-K(HML-2) in cell culture. We also present striking evidence that two HERV-K(HML-2) proviruses that are fixed in the modern human genome (HERV-K60 and HERV-KI) were subjected to hypermutation by a cytidine deaminase. Inspection of the spectrum of mutations that are found in HERV-K proviruses in the human genome and HERV-K DNA generated during in vitro replication in the presence of each of the human APOBEC3 proteins unequivocally identifies APOBEC3G as the cytidine deaminase responsible for hypermutation of HERV-K60 and HERV-KI. This is a rare example of the antiretroviral effects of APOBEC3G in the setting of natural human infection, whose consequences have been fossilized in human DNA, and a striking example of inactivation of ancient retroviruses in humans through enzymatic cytidine deamination.
Structural Insight into the Human Immunodeficiency Virus Vif SOCS Box and Its Role in Human E3 Ubiquitin Ligase Assembly
Authors: Stanley Bradford J. , Ehrlich Elana S. , Short Leslie , Yu Yunkai , Xiao Zuoxiang , Yu Xiao-Fang , Xiong Yong
Published: June 2008

Human immunodeficiency virus (HIV) virion infectivity factor (Vif) causes the proteasome-mediated destruction of human antiviral protein APOBEC3G by tethering it to a cellular E3 ubiquitin ligase composed of ElonginB, ElonginC, Cullin5, and Rbx2. It has been proposed that HIV Vif hijacks the E3 ligase through two regions within its C-terminal domain: a BC box region that interacts with ElonginC and a novel zinc finger motif that interacts with Cullin5. We have determined the crystal structure of the HIV Vif BC box in complex with human ElonginB and ElonginC. This complex presents direct structural evidence of the recruitment of a human ubiquitin ligase by a viral BC box protein that mimics the conserved interactions of cellular ubiquitin ligases. We further mutated conserved hydrophobic residues in a region downstream of the Vif BC box. These mutations demonstrate that this region, the Vif Cullin box, composes a third E3-ligase recruiting site critical for interaction between Vif and Cullin5. Furthermore, our homology modeling reveals that the Vif Cullin box and zinc finger motif may be positioned adjacent to the N terminus of Cullin5 for interaction with loop regions in the first cullin repeat of Cullin5.
Interferon Regulatory Factor IRF-7 Induces the Antiviral Alpha Interferon Response and Protects against Lethal West Nile Virus Infection
Authors: Daffis Stephane , Samuel Melanie A. , Suthar Mehul S. , Keller Brian C. , Gale Michael , Diamond Michael S.
Published: June 2008

Type I interferon (IFN-α/β) comprises a family of immunomodulatory cytokines that are critical for controlling viral infections. In cell culture, many RNA viruses trigger IFN responses through the binding of RNA recognition molecules (RIG-I, MDA5, and TLR-3) and induction of interferon regulatory factor IRF-3-dependent gene transcription. Recent studies with West Nile virus (WNV) have shown that type I IFN is essential for restricting infection and that a deficiency of IRF-3 results in enhanced lethality. However, IRF-3 was not required for optimal systemic IFN production in vivo or in vitro in macrophages. To begin to define the transcriptional factors that regulate type I IFN after WNV infection, we evaluated IFN induction and virus control in IRF-7
−/−
mice. Compared to congenic wild-type mice, IRF-7
−/−
mice showed increased lethality after WNV infection and developed early and elevated WNV burdens in both peripheral and central nervous system tissues. As a correlate, a deficiency of IRF-7 blunted the systemic type I IFN response in mice. Consistent with this, IFN-α gene expression and protein production were reduced and viral titers were increased in IRF-7
−/−
primary macrophages, fibroblasts, dendritic cells, and cortical neurons. In contrast, in these cells the IFN-β response remained largely intact. Our data suggest that the early protective IFN-α response against WNV occurs through an IRF-7-dependent transcriptional signal.
Nuclear Pore Composition and Gating in Herpes Simplex Virus-Infected Cells
Authors: Hofemeister Helmut , O'Hare Peter
Published: June 2008

The mechanism by which herpes simplex virus (HSV) exits the nucleus remains a matter of controversy. The generally accepted route proposes that capsids exit via primary envelopment at the inner nuclear membrane and subsequent fusion of this primary particle with the outer nuclear membrane to gain capsid entry to the cytoplasm. However, recent observations indicate that HSV may induce gross morphological alterations of nuclear pores, resulting in the loss of normal pores and the appearance of dilated gaps in the nuclear membrane of up to several 100 nm. On this basis, it was proposed that a main route of capsid exit from the nucleus is directly through these altered pores. Here, we examine the biochemical composition of some of the major nuclear pore components in uninfected and HSV-infected cells. We show that total levels of major nucleoporins and their sedimentation patterns in density gradients remain largely unchanged up to 18 h after HSV infection. Some alteration in modification of one nucleoporin, Nup358/RanBP2, was observed during enrichment with anti-nucleoporin antibody and probing for O glycosylation. In addition, we examine functional gating within the nucleus in live cells, using microinjection of labeled dextran beads and a recombinant virus expressing GFP-VP16 to track the progress of infection. The nuclear permeability barrier for molecules bigger than 70 kDa remained intact throughout infection. Thus, in a functional assay in live cells, we find no evidence for gross perturbation to the gating of nuclear pores, although this might not exclude a small population of modified pores.
PAPER CHROMATOGRAPHY OF SUGARS IN PLANTS
Authors: Bidwell R. G. S. , Krotkov G. , Reed G. B.
Published: June 2008

A chromatographic method for the qualitative and rough quantitative estimation of sugars and soluble phosphates in plants is described. Using this method, representatives of 27 families of Spermatophyta and 10 representatives of Algae have been examined. In Spermatophyta the total sugar content was found to be fairly high, with sucrose usually the main sugar, and glucose predominating over fructose. In Chlorophyta, the concentration and the nature of the sugars present were fairly similar to those in Spermatophyta. In Phaeo-phyta, Rhodophyta, and a diatom Nitzschia, the soluble sugar content was very low, with glucose usually being the main sugar. The distribution of sugars in aquatic Spermatophyta was similar to that of terrestrial Spermatophyta rather than that of Algae. When wheat leaves were detached and placed on water in darkness, subsequent metabolism of their sugars was found to be markedly affected by the conditions of illumination prior to leaf detachment. On illumination, detached wheat leaves accumulated large amounts of alcohol soluble fructosans, while attached leaves did not. In detached wheat leaves during prolonged starvation, soluble phosphates, both organic and inorganic began to accumulate after two days, indicating breakdown of some insoluble forms of phosphorus. By this time free sugars had completely disappeared, though sucrose reappeared in relatively large amounts on the third day and then declined again.
Phytogeography and ecology of the lichen family Cladoniaceae in southwestern Alberta
Authors: Bird C. D. , Marsh A. H.
Published: June 2008

Forty-two species of the genera Cladonia and Baeomyces in the lichen family Cladoniaceae are reported from a 13 400 km2 area in the mountains and foothills of southwestern Alberta. Thirteen of the species are new to Alberta. The distribution and habitats occupied by each of the species are described. The following North American distribution elements are represented: Arctic–Boreal, 48%; Boreal, 26%; Arctic–Alpine, 10%; Temperate, 5%; Arctic–Temperate, 5%; Boreal–Temperate, 2%,; Temperate–Tropic, 2%; and Pan North American, 2%. Only one of the species is endemic to North America.
Some effects of Ceratocystis ulmi on the phloem and vascular cambium of Ulmus americana
Authors: Davis Jerry D. , Saigo Roy , Evert Ray F.
Published: June 2008

Preliminary studies of naturally infected American elm trees show that abnormalities occur in the vascular cambium and the secondary phloem. Abnormalities include deposition of callose on sieve plates, septation of fusiform initials, lack of fiber differentiation, and accumulation of lipoidal substances in the vascular cambium. The sequence of these abnormalities and their importance in the death of the tree are yet to be determined.
Regulation of the Krebs cycle and pentose phosphate pathway activities in the control of dormancy of Avena fatua
Authors: Simmonds J. A. , Simpson G. M.
Published: June 2008

Malonic acid (10−2 M) promoted germination of excised dormant embryos of Avena fatua L. but inhibited germination of non-dormant embryos. Malonate inhibited oxygen consumption and carbon dioxide evolution of dormant embryos which resulted in an increased respiratory quotient and a decrease in the glucose C6/C1 ratio. Germination is oxygen-dependent, and malonate-sensitive oxygen consumption decreased during afterripening. Succinic acid (5 × 10−2 M) promoted germination of dormant embryos. Gibberellic acid (GA) (1.0 ppm) and succinate (5 × 10−2 M) interacted synergistically in promoting germination. Adenosine diphosphate also promoted germination but only after a considerable lag period. Germination of non-dormant embryos was inhibited by 2,4-dinitrophenol indicating the importance of adenosine triphosphate for germination. Storage of caryopses in various gaseous environments indicated that the response of dormant embryos to GA treatment was dependent on the operation of oxidative processes during afterripening. A model is proposed, indicating the nature of the regulation of the oxidative systems involved in the control of dormancy. The model accounts for the known effects of oxygen treatments on seeds, provides an explanation of the mechanism of afterripening, and explains the survival of imbibed dormant caryopses during adverse conditions. Such a model may be of widespread significance and is discussed in relation to its interaction with GA in developmental processes.
The life history of Chondrus crispus in culture
Authors: Chen L. C-M. , McLachlan J.
Published: June 2008

The life history of the rhodophycean alga, Chondrus crispus, was completed in culture in about 20 months. Plants established from tetraspores formed male and female gametophytes and subsequently carposporophytes; carpospores in turn gave rise to plants with mature tetrasporangia. Tetraspores from these resulted in second generation gametophytes. Carpospores of plants from nature developed into tetrasporophytes; gametophytes derived from the tetraspores became sexually mature within a year. Sporophytic and gametophytic plants were, as expected, morphologically similar. Rate of growth of plants in cultures was comparable with published observations made on plants in nature. Preliminary experiments showed that, in culture, regeneration can occur from both the erect frond and the basal disc. In the latter, erect fronds may arise from any point on the dorsal surface of the disc.
Genetic relationships in Abies (fir) of eastern United States: an electrophoretic study
Authors: Jacobs Brian F. , Werth Charles R. , Guttman Sheldon I.
Published: June 2008

Abies (fir) is widely considered to consist of two species in the eastern United States, A. balsamea (L.) Mill, and A. fraseri (Pursh.) Poir., distinguished by relative cone bract to subtending cone scale lengths and number of leaf hypodermal cells. Intermediate individuals have been recognized as A. balsamea var. phanerolepis Fern. An understanding of the relationship between the two putative species hinges on the interpretation of the intermediate. Two alternative hypotheses view the intermediate as either an interspecific hybrid or as an intraspecific variant. Twenty gene loci were electrophorctically analyzed in samples from 12 populations representing all three taxa. All populations shared similar complements of alleles at comparable frequencies for 13 polymorphic loci. Genetic distances among populations ranged from 0.10 to 0.0. Cluster analysis joined populations of A. fraseri with those representing A. balsamea var. phanerolepis at a distance of 0.03 and linked populations of A. balsamea with the other two taxa at 0.06. A hierarchical analysis of the three taxa, delimited by cluster analysis and bract exsertion, places A. balsamea var. phanerolepis intermediate between the two species. These data support a conspecifie status for all of eastern U.S. Abies with gene exchange between populations relatively unrestricted at last contact (≈ 10 000 years BP). Further, A. balsamea var. phenerolepis, while electrophoretically intermediate, is likely not of hybrid origin. Our results are consistent with those of recent studies which conclude that A. fraseri and A. balsamea are very closely related taxa of Pleistocene origin.
Tétrades irrégulières, développements apoméiotiques et aposporie dans les ovules de Cichorium intybus L. (Chicorée de Bruxelles)
Authors: Longly B.
Published: June 2008

After two reproductive cycles of self-pollination, a plant of Cichorium intybus L. (Belgian endive) shows a wide range of female reproductive structures, presumed apomictic for the most part. These are either archesporial cells dividing late to give rise immediately to a not always eight-nucleate embryo sae, or archesporial cells producing dyads one cell of which gives rise to an embryo sac, or also archesporial cells giving rise to uneven tetrads inserted into "rows of cells." Each flower head usually contains only one kind of formation. Besides the archesporial cells, other cells represent an apomictic potentiality, i.e., nucellar and chalazal cells. The first degenerate before anthesis (except at the antipodal level); the evolution of the second has to be followed after anthesis. Thus in C. intybus generative apospory, apomeiosis forms which need to be specified, uneven tetrads, and potential somatic apospory occur during gametophytogenesis.
Erynia pieris (Zygomycetes: Entomophthoraceae), a new pathogen of Pieris rapae (Lepidoptera: Pieridae): description, host range, and notes on Erynia virescens
Authors: Li Zengzhi , Humber Richard A.
Published: June 2008

Erynia pieris Li & Humber (Entomophthorales: Entomophthoraceae) is described for a fungus originally isolated from Pieris rapae (Lepidoptera: Pieridae). The fungus grows and sporulates well on standard mycological media. Primary conidia are ovoid to obovoid, 21–33 × 11–24 μm (averaging 26 × 16 μm, with a length/width ratio of 1.60), uninucleate, bitunicate, and forcibly discharged from bifurcate or irregularly branched conidiophores. Secondary through quaternary conidia are more nearly globose than primary conidia. Nuclei contain prominent, readily stained chromosomal granulations. Cystidia emerge from the host body before the conidiophores, are only slightly thicker than conidiophores at the base, and taper to a blunt apex. Rhizoids are monohyphal on lepidopterans, are little thicker than vegetative hyphae, and have no discoid terminal holdfast; rhizoidal morphology varies considerably between lepidopterous and nonlepidopterous hosts. No resting spores were observed. Laboratory studies demonstrated the pathogenicity of cultures of this fungus on several other lepidopterans (Estigmene acrea, Heliothis zea, Heliothis virescens, Trichoplusia ni, Spodoptera eridania). on the common housefly (Musca domestica), and on potato leafhopper (Etnpoasca fabae). Erynia virescens (Thax.) Remaudière & Hennebert is emended and compared with E. pieris; both species are assigned to Erynia subg. Furia (Batko) Li & Humber, comb. nov. Furia differs from other Erynia subgenera by the presence of cystidia as thick as conidiophores and of rhizoids no thicker than vegetative hyphae and having no differentiated terminal holdfasts, and by the absence of secondary capilliconidia.
Metal accumulation by bryophytes in some zinc-rich blanket bogs, Selwyn Mountains, Yukon Territory
Authors: Lee Julian , Jonasson Ian R. , Goodfellow Wayne D.
Published: June 2008

Collections of Pohlia wahlenbergii, Leptobryum pyriforme, Philonotis fontana, and Drepanocladus aduncus were made at the XY Zn–Pb sulphide deposit, Howard's Pass, Y.T., Canada. Brilliant lime green growths of mosses flourish in hillside blanket bogs fed by Zn-, Pb-, and Cd-rich spring waters derived from faults which crosscut sulphide mineralizations. All species showed elevated levels of accumulation of these metals, but the concentration of Zn in the upper thalli was higher than Pb or Cd. However, the relative enrichments favour accumulation of Pb rather than Cd and Zn. The bryophyte D. aduncus is unusual in that it gathers cadmium in preference to Pb and Zn, according to calculated relative enrichment factors. The bog materials which provide the substrate for moss blankets are unusual in composition; more than 60% of the material comprises secondary Zn minerals, viz., zincic calcite ((Zn,Ca)CO3), smithsonite (ZnCO3), and wurtzite (ZnS), and the remainder is humified peat derived from buried moss strata. The end product of burial and replacement of decaying moss layers is the hydrated zinc silicate, hemimorphite (Zn4Si2O7(OH)2∙H2O), which results from the cell by cell replacement of moss fibre with complete preservation of the rhizoid structure.
Seasonal variation in the radiation regime of a dwarf apple orchard
Authors: Blackburn William J. , Proctor John T. A.
Published: June 2008

Seasonal and daily radiation fluxes showed that the highest monthly albedo was 0.81 in January compared with a growing season mean of about 0.20. These differences correspond to dramatic changes in the surface characteristics with season. Patterns in photosynthetically active radiation were similar to those for incoming solar irradiance. The highest values of incoming long-wave radiation were on days with high temperatures and overcast skies, whereas outgoing long-wave radiation exhibited a midwinter minimum in January corresponding to a cold snow-covered surface. Net radiation was negative in the winter months but increased almost linearly in the late winter, spring, and early summer months. An understanding of these components of the radiation regime which drive the photosynthetic system may be useful in assessing winter injury or crop development during the growing season.
Taxonomic studies in wall barley (Hordeum murinum) and sea barley (Hordeum marinum). 1. Character investigation: assessment of new and traditional characters
Authors: Baum Bernard R. , Bailey L. Grant
Published: June 2008

In the literature about 60 taxa have been described at various taxonomic levels in the wall barley – sea barley group. Considerably less confusion exists between wall and sea barley than within. It appears that five taxa have been recognized and are likely to be valid, but there has been disagreement as to their status. The authors have investigated new micromorphologic characters and reexamined and critically defined traditional characters of material collected throughout the area of the natural habitats of the group. Characters taken from the seed epiblast and the floral lodicules were found useful for conclusively distinguishing between Hordeum murinum (sensu lato), H. glaucum, and H. marinum (sensu lato). Exploratory data analysis of 35 other characters investigated supports this distinction. Thus, in this particular paper three taxa are tentatively recognized. In the subsequent paper the validity of the three taxa will be tested by numerical analysis, and furthermore the possibility of five taxa will be investigated and similarly tested.
Marine tube-dwelling diatoms of eastern Canada: descriptions, checklist, and illustrated key
Authors: Lobban Christopher S.
Published: June 2008

From a study of living materials and specimens in several regional herbaria, a list has been drawn up of all the common and several of the rarer tube-dwelling diatoms of eastern Canada. Descriptions, illustrations of living material and acid-cleaned valves, and a key to the species are provided. Most specimens were from the Atlantic Provinces and the St. Lawrence estuary, but a few were from the Northwest Territories. By far the most common species is Berkeleya rutilans. Other species occurring commonly in the Quoddy Region of the Bay of Fundy, and sporadically in space and time elsewhere, arc Navicula delognei (two forms), Nav. pseudocomoides, Nav. smithii, Haslea crucigera, and a new species, Nav.rusticensis. Navicula ramosissima and Nav. mollis in eastern Canada are usually found as scattered cohabitants in tubes of other species. Nitzschia tubicola and Nz. fontifuga also occur sporadically as cohabitants.
A metabolic comparison between progressive and monocarpic senescence of soybean
Authors: Secor J. , Shibles R. , Stewart C. R.
Published: June 2008

The onset of senescence, defined as the time that photosynthesis began to decline irreversibly, was compared with ribulose-1,5-bisphosphate carboxylase (EC 4.1.1.39) (RuBPCase) activity, chlorophyll content, protein content, and leaf diffusive resistance in outdoor-grown soybean (Glycine max (L.) Merr. cv. Amsoy 71) leaves that had emerged and senesced during different stages of plant ontogeny. The purpose was to compare metabolic events in soybean leaves associated with progressive and monocarpic senescence. Soluble protein, chlorophyll, and RuBPCase activity declined coincidently with photosynthesis in all leaves. In leaves that emerged before flowering, the decline in RuBPCase activity could be accounted for by protein degradation, whereas in a leaf that emerged after flowering had begun, the decline also was attributable to, but to a much lesser extent, a change in specific activity. All parameters declined more rapidly in leaves at nodes higher on the plant. There was an indication that developing pods temporarily retarded the rate of decline in photosynthesis. Regression of photosynthesis on chlorophyll, protein, and RuBPCase activity yielded coefficients that were different in a leaf that developed during the vegetative period from those of leaves that developed later, whereas no differences were detected among the later leaves. We conclude from our results that the factors associated with senescence are similar among leaves that senesce during different stages of plant development. But there is evidence that the rate of senescence may be differentially regulated.
Synergistic effect on field-grown soybeans from combinations of sulfur dioxide and nitrogen dioxide
Authors: Irving Patricia M. , Miller Joseph E.
Published: June 2008

Gaseous air pollutants are frequently present together in the environment downwind from industrial developments and thus have the potential to cause interactive effects on biological receptors. Accordingly, an investigation was conducted to determine how combinations of the gaseous pollutants, sulfur dioxide (SO2) and nitrogen dioxide (NO2) affect a major crop. Open-air field plots of soybeans (Glycine max L.) were exposed to eight different dose levels of SO2 and NO2, alone and in combination, in the presence of ambient ozone (O3) during 1980 and 1981. The soybean plots were fumigated on 10 occasions in both years of the study during the pod-filling period for an average exposure time during fumigation of approximately 3 h. Mean concentrations during fumigation periods ranged from 0.13 to 0.42 ppm SO2 and 0.06 to 0.40 ppm NO2. Premature senescence, as measured by chlorophyll degradation, was observed in the combined pollutant plots in both years of the experiment. Fumigations with NO2 alone had no effect on seed yields in either year. Exposures with SO2 alone had no effect on yields in 1980 and decreased yields by up to 6% in 1981, possibly as a result of greater concentration peaks. Combinations of SO2 and NO2 had a synergistic effect in both years of the study and resulted in yield decreases ranging from 9 to 25%, depending on pollutant dose.
Rhabdocline parkeri, a ubiquitous foliar endophyte of Douglas-fir
Authors: Sherwood-Pike Martha , Stone Jeffrey K. , Carroll George C.
Published: June 2008

Rhabdocline parkeri n. sp. (Hemiphacideaceae) is described, together with its sporodochial anamorph, Meria parkeri n. sp. Rhabdocline parkeri occurs as localized endophytic infections of living Douglas-fir needles, fruiting primarily on senescent, galled, or dead needles. It is ubiquitous in western Oregon, occurring on essentially all trees sampled in an extensive survey of Douglas-fir needle endophytes, and has been recorded from Washington and northern California.
Pinus haboroensis sp. nov. and the affinities of permineralized leaves from the Upper Cretaceous of Japan
Authors: Stockey Ruth A. , Nishida Makoto
Published: June 2008

A new species of Pinus is described based on permineralized needles from the Sankebetsugawa, Haboro, and the Koyanosawa, Ikushumbetsu, Mikasa City, Hokkaido, Japan. Leaf fragments were discovered in calcium carbonate nodules with abundant ammonites dated as Santonian–Senonian (Upper Cretaceous). The leaves, borne in fascicles of three or four, are 0.9–1.1 mm in radial and 1.5–1.8 mm in tangential diameters, and fragments up to 0.5 cm long have been recovered. The vascular strand is double and bundles are separated by a large anchor-shaped band of sclerenchyma fibers. Transfusion tissue up to four cells wide and a long-base triangular endodermis with an irregular outline surround the vascular tissues. Six to eight medial and external resin canals occur within the band of small plicate mesophyll cells three or four cells wide. The uniform hypodermis from one to four cells thick lies beneath thick-walled elliptical epidermal cells. These amphistomatic leaves with deeply sunken stomata most closely resemble those of Pinus coulteri D. Don, subgenus Pinus, section Pinus, subsection Sabinianae and have added significantly to our knowledge of permineralized Cretaceous pine needles. Pinus haboroensis sp. nov. is closely compared anatomically with the other Upper Cretaceous pines from Japan and North America and primitive needle characters are discussed. Emended diagnoses for P. flabellifolia Ogura and P. bifoliata Ueda and Nishida are presented, including a description of their possible affinities to sections and subsections of the genus Pinus.
The influence of a weedy habitat on the seed bank of an adjacent cultivated field
Authors: Hume L. , Archibold O. W.
Published: June 2008

Seed traps positioned 1 to 100 m into a cultivated field were used to assess the seed rain from an adjacent weedy pasture. The cultivated field was in the fallow phase of a crop-fallow rotation. Two sets of traps were used: one set contained steampasteurized soil and the other contained untreated soil from the field. Traps were left in the field for 12 months and then transported to a greenhouse where they were kept for 12 additional months. Seed content was determined by field and greenhouse emergence of seedlings. The pasture was dominated by grasses, the most abundant being Poa pratensis, Stipa comata, Bromus inermis, and Agropyron repens. Seeds of pasture species were found in decreasing numbers in the fallow field, with few found more than 7 m from the fence line in traps of both sterilized and nonsterilized soil. The fallow field was dominated by species such as Setaria viridis, Thlaspi arvense, Descurainia sophia, and Salsola kali which were not found in abundance in the pasture. It was concluded that seed rain from the pasture had a significant influence on the germinable seed content of the soil of the cultivated field (at the edge only). The incursion of pasture species into cultivated land presumably has been restricted by cultural practices.
Extraction and characterization of the enzymes of fructan biosynthesis in timothy (Phleum pratense)
Authors: Suzuki Michio , Pollock Christopher J.
Published: June 2008

A preparation of phlein sucrase from seedling shoots of timothy (Phleum pratense L.) is described which catalyzed the synthesis of fructan with a mean molecular size of 34 000 using sucrose as the substrate. Activity was fully sedimentable at 25 000 × g, had a pH optimum of 7.0, and a Km for sucrose of 0.15 M. Activity was inhibited by β-mercaptoethanol and sodium diethyl dithiocarbamate. Raffinose and stachyose, but not members of the kestose series of oligofructans, could act as fructosyl donors in addition to sucrose. Formation of oligosaccharides during high molecular weight fructan synthesis was minimal, with synthesis occurring by a mechanism apparently analogous to bacterial levansucrase. These observations are discussed in relation to the in vivo patterns of fructan biosynthesis observed in different species of higher plants.
Ecological relationships of wild rice, Zizania aquatica. 4. Environmental regions within a wild rice lake
Authors: Lee P. F.
Published: June 2008

Four environmental regions with similar characteristics were identified within a lake that had been uniformly seeded with wild rice. Q-type cluster analysis was used to identify the environmental regions and discriminant analysis verified their existence. The regions differed from one another in the amount of plant competition and the phosphorus, zinc, and organic content of the sediment. By superimposing weight per wild rice plant categories with the locations of the environmental regions, it was found that the environmental regions were related to wild rice production. Low weights per wild rice plant were due to low phosphorus levels, low organic content of the sediment, or high plant competition values. Only where these variables were at suitable levels were high weights per wild rice plant obtained.
Changes in the activity of the enzymes involved in nitrogen metabolism in Catharanthus roseus depending on different nitrogen sources
Authors: Loyola-Vargas Victor Manuel , Gómez Irene , López Ma. Eugenia , Reyes Jorge , Fierro Miriam , Robert Manuel L.
Published: June 2008

The activities of the enzymes nitrate reductase (EC 1.6.6.1) and nitrite reductase (EC 1.7.99.3) were measured in the leaves and roots of whole plants of Catharanthus roseus grown in different nitrogen sources: water (control), 20 mM KNO3, 2 mM NH4Cl, and a mixture of nitrate and ammonium. The activities of these enzymes were also measured in leaf explants incubated in the same nitrogen sources. The results indicate that nitrate reductase and nitrite reductase in leaves behaved very differently from those in roots. Activity of leaf nitrate reductase measured in vitro decreased with nitrate and increased with ammonium, while in the root, it only decreased when the mixture of both nitrogen sources was employed. In contrast, nitrite reductase from roots was modified by the nitrogen source while the enzyme from the leaves was not. The amino acid pool was increased by all of the nitrogen sources in both whole plants and explants.
Cell determination during embryogenesis in Citrus jambhiri. III. Graft formation and nonformation in embryonic tissues
Authors: Bruck David K. , Walker Dan B.
Published: June 2008

Approach grafts were constructed using embryos in vitro with and without surface tissue removal along the root–hypocotyl axis. All embryonic stages from mid-heart through mature proved competent to graft after surface excision. Early heart-shaped embryos grafted back to themselves when a longitudinal incision was made which cut the hypocotyl in half but left the root intact. Cut globular embryos could not be maintained in position for a sufficient period to generate a graft union. Callus tissue was produced in all cut embryos by internal cells but not by surface cells neighboring the cut region. Intact embryos failed to graft or respond in any fashion. The incompetence to graft of surface tissues at all embryonic stages indicates that those tissues are determined as epidermal even in the earliest stages of embryogenesis. Internal cells of the embryo were not epidermal in response. They were able to form callus and graft with increasing ease toward older stages of embryogenesis.
La dynamique récente des combes à neige du golfe de Richmond (Québec nordique): une analyse dendrochronologique
Authors: Morin Hubert , Payette Serge
Published: June 2008

Recent trends of variations in snowfall and in the duration of the clearing period of snow patches in Richmond Gulf (northern Quebec) have been studied using dendrochronological analysis of mechanical damage and the age structure of spruce populations. The mechanical damage (branch scars, bending of stems, and apical recovery) suffered by individuals of white spruce and black spruce found around the snow patches indicates the years or periods of overabundant snowfall during the 20th century (ca. 1919, 1930 to 1936, 1953 to 1955, 1958 and 1959, 1962 and 1963, 1968, 1972, 1976 and 1977, 1980 and 1981). Those years or periods also correspond to periods of good growth, as shown by trends of the standardized dendrochronological curve, plotted from data obtained from the oldest trees found nearby. Colonization of forest snow patches by white and black spruce since 1940 shows that overabundant snowfall does not prevent plant establishment. This spruce invasion is linked to early thawing resulting in a longer growth period. Also, a decrease in spruce establishment, an increase in the mortality rate of seedlings and coppice branches, as well as a reduction in the growth of trees after 1970 are linked to climatic cooling as evidenced by late thawing. [Translated by the Journal]
THE CNOT QUANTUM LOGIC GATE USING q-DEFORMED OSCILLATORS
Authors: GANGOPADHYAY DEBASHIS
Published: June 2008

It is shown that the two qubit CNOT (controlled NOT) gate can also be realized using q-deformed angular momentum states constructed via the Jordan–Schwinger mechanism. Thus, all the three gates necessary for universality i.e. Hadamard, Phase Shift and the two qubit CNOT gate are realizable with q-deformed oscillators.
REMOTE PREPARATION OF THE TWO-PARTICLE STATE
Authors: YAN FENG-LI , ZHANG GUO-HUA
Published: June 2008

We present a scheme of remote preparation of the two-particle state by using two Einstein–Podolsky–Rosen pairs or two partially entangled two-particle states as the quantum channel. The probability of the successful remote state preparation is obtained.
oxLDL facilitates flow-induced realignment of aortic endothelial cells
Authors: Kowalsky Gregory B. , Byfield Fitzroy J. , Levitan Irena
Published: June 2008

Alignment of vascular endothelial cells (ECs) in the direction of the flow is considered a key factor in maintaining endothelial integrity in an active hemodynamic environment. Our recent studies showed that exposure to oxidized LDL (oxLDL), one of the major proatherogenic lipoproteins, significantly increases the stiffness of human aortic ECs, suggesting that oxLDL may have a significant impact on the sensitivity of ECs to mechanical stimuli. In this study, we show that oxLDL strongly enhances the ability of ECs to realign in the direction of the flow and facilitates the formation of F-actin stress fibers under static and flow conditions. The impact of oxLDL on the flow-induced realignment is observed on whole cell and single-fiber levels. We also show that, similar to the effect of oxLDL on endothelial stiffness, the impact of oxLDL on flow-induced realignment can be simulated by methyl-β-cyclodextrin-induced cholesterol depletion, supporting the hypothesis that oxLDL acts as cholesterol acceptor, rather than cholesterol donor, for ECs. Finally, we propose that oxLDL/cholesterol depletion-induced sensitization of ECs to flow may be a result of an increase in cellular stiffness and a respective increase in membrane-cytoskeleton tension.
Hydrogen sulfide as an oxygen sensor in trout gill chemoreceptors
Authors: Olson Kenneth R. , Healy Michael J. , Qin Zhaohong , Skovgaard Nini , Vulesevic Branka , Duff Douglas W. , Whitfield Nathan L. , Yang Guangdong , Wang Rui , Perry Steve F.
Published: June 2008

O2chemoreceptors elicit cardiorespiratory reflexes in all vertebrates, but consensus on O2-sensing signal transduction mechanism(s) is lacking. We recently proposed that hydrogen sulfide (H2S) metabolism is involved in O2sensing in vascular smooth muscle. Here, we examined the possibility that H2S is an O2sensor in trout chemoreceptors where the first pair of gills is a primary site of aquatic O2sensing and the homolog of the mammalian carotid body. Intrabuccal injection of H2S in unanesthetized trout produced a dose-dependent bradycardia and increased ventilatory frequency and amplitude similar to the hypoxic response. Removal of the first, but not second, pair of gills significantly inhibited H2S-mediated bradycardia, consistent with the loss of aquatic chemoreceptors. mRNA for H2S-synthesizing enzymes, cystathionine β-synthase and cystathionine γ-lyase, was present in branchial tissue. Homogenized gills produced H2S enzymatically, and H2S production was inhibited by O2, whereas mitochondrial H2S consumption was O2dependent. Ambient hypoxia did not affect plasma H2S in unanesthetized trout, but produced a Po2-dependent increase in a sulfide moiety suggestive of increased H2S production. In isolated zebrafish neuroepithelial cells, the putative chemoreceptive cells of fish, both hypoxia and H2S, produced a similar ∼10-mV depolarization. These studies are consistent with H2S involvement in O2sensing/signal transduction pathway(s) in chemoreceptive cells, as previously demonstrated in vascular smooth muscle. This novel mechanism, whereby H2S concentration ([H2S]) is governed by the balance between constitutive production and oxidation, tightly couples tissue [H2S] to Po2and may provide an exquisitely sensitive, yet simple, O2sensor in a variety of tissues.
Repeated ethanol exposure during late gestation decreases nephron endowment in fetal sheep
Authors: Gray Stephen P. , Kenna Kelly , Bertram John F. , Hoy Wendy E. , Yan Edwin B. , Bocking Alan D. , Brien James F. , Walker David W. , Harding Richard , Moritz Karen M.
Published: June 2008

Maternal alcohol consumption during pregnancy can affect fetal development, but little is known about the effects on the developing kidney. Our objectives were to determine the effects of repeated ethanol exposure during the latter half of gestation on glomerular (nephron) number and expression of key genes involved in renal development or function in the ovine fetal kidney. Pregnant ewes received daily intravenous infusion of ethanol (0.75 g/kg, n = 5) or saline (control, n = 5) over 1 h from 95 to 133 days of gestational age (DGA; term is ∼147 DGA). Maternal and fetal arterial blood samples were taken before and after the start of the daily ethanol infusions for determination of blood ethanol concentration (BEC). Necropsy was performed at 134 DGA, and fetal kidneys were collected for determination of total glomerular number using the physical disector/fractionator technique; at this gestational age nephrogenesis is completed in sheep. Maximal maternal and fetal BECs of 0.12 ± 0.01 g/dl (mean ± SE) and 0.11 ± 0.01 g/dl, respectively, were reached 1 h after starting maternal ethanol infusions. Ethanol exposure had no effect on fetal body weight, kidney weight, or the gene expression of members of the renin-angiotensin system, insulin-like growth factors, and sodium channels. However, fetal glomerular number was lower after ethanol exposure (377,585 ± 8,325) than in controls (423,177 ± 17,178, P < 0.001). The data demonstrate that our regimen of fetal ethanol exposure during the latter half of gestation results in an 11% reduction in nephron endowment without affecting the overall growth of the kidney or fetus or the expression of key genes involved in renal development or function. A reduced nephron endowment of this magnitude could have important implications for the cardiovascular health of offspring during postnatal life.
Mechanism of dietary salt-mediated increase in intravascular production of TGF-β1
Authors: Ying Wei-Zhong , Aaron Kristal , Sanders Paul W.
Published: June 2008

Clinical and preclinical studies have demonstrated an important effect of arterial pathobiology on the progressive loss of renal function that occurs in chronic kidney disease. Chronic kidney disease, in turn, promotes alterations in vascular function. A modulating role for dietary salt has been suggested, with the amount of salt intake regulating endothelial cell production of transforming growth factor-β1 (TGF-β1), a fibrogenic growth factor that promotes arteriosclerosis and glomerulosclerosis. The purpose of the present studies was to determine how the interaction between dietary salt intake and vasculature promoted the production of TGF-β1 in rats. Two different vascular tissues, aortic rings and glomeruli, were chosen for study. Dietary salt induced, in a dose-dependent fashion, activation of proline-rich tyrosine kinase-2 (Pyk2) and further identified c-Src as an important binding partner of Pyk2 in these tissues. Use of pharmacological inhibitors and dominant negative strategies confirmed that dietary salt induced complex formation of Pyk2 and c-Src with downstream activation of p38 and p42/44 mitogen-activated protein kinases and generation of TGF-β1. The experiments defined the molecular signaling events that promoted the production of TGF-β1, a key growth factor involved in the vascular response to increased salt intake.
Separate Peripheral Pathways for Pruritus in Man
Authors: Namer Barbara , Carr Richard , Johanek Lisa M. , Schmelz Martin , Handwerker Hermann O. , Ringkamp Matthias
Published: June 2008

Recent findings suggest that itch produced by intradermal insertion of cowhage spicules in human is histamine independent. Neuronal mechanisms underlying nonhistaminergic itch are poorly understood. To investigate which nerve fibers mediate cowhage induced itch in man, action potentials were recorded from cutaneous C-fibers of the peroneal nerve in healthy volunteers using microneurography. Mechano-responsive and -insensitive C-nociceptors were tested for their responsiveness to cowhage spicules, histamine, and capsaicin. Cowhage spicules induced itching and activated all tested mechano-responsive C-units (24/24, but no mechano-insensitive C-fibers (0/17). Histamine also induced itch, but in contrast to cowhage, it caused lasting activation only in mechano-insensitive units (8/12). In mechano-responsive C-units, histamine caused no or only short and weak responses unrelated to the time course of itching. Capsaicin injections activated four of six mechano-responsive fibers and three of four mechano-insensitive C-fibers. Cowhage and histamine activate distinctly different nonoverlapping populations of C-fibers while inducing similar sensations of itch. We hypothesize that cowhage activates a pathway for itch that originates peripherally from superficial mechano-responsive (polymodal) C-fibers and perhaps other afferent units. It is distinct from the pathway for histamine-mediated pruritus and does not involve the histamine-sensitive mechano-insensitive fibers.
A Fixed Point Approach to the Stability of Quadratic Functional Equation with Involution
Authors: Jung Soon-Mo , Lee Zoon-Hee
Published: June 2008

Cădariu and Radu applied the fixed point method to the investigation of Cauchy and Jensen functional equations. In this paper, we will adopt the idea of Cădariu and Radu to prove the Hyers-Ulam-Rassias stability of the quadratic functional equation with involution.
Hierarchical Pathfinding and AI‐Based Learning Approach in Strategy Game Design
Authors: Duc Le Minh , Sidhu Amandeep Singh , Chaudhari Narendra S.
Published: June 2008

Strategy game and simulation application are an exciting area with many opportunities for study and research. Currently most of the existing games and simulations apply hard coded rules so the intelligence of the computer generated forces is limited. After some time, player gets used to the simulation making it less attractive and challenging. It is also costly and tedious to incorporate new rules for an existing game. The main motivation behind this research project is to improve the quality of artificial intelligence‐ (AI‐) based on various techniques such as qualitative spatial reasoning (Forbus et al., 2002), near-optimal hierarchical pathfinding (HPA*) (Botea et al., 2004), and reinforcement learning (RL) (Sutton and Barto, 1998).
Permanence for a Discrete Model with Feedback Control and Delay
Authors: Fan Yong-Hong , Wang Lin-Lin
Published: June 2008

The permanence of a single‐species population discrete model with feedback control is considered.
We found that if we use the method of comparison theorem, then the additional condition, to some
extent, is necessary. But for the system itself, this condition may not be necessary. Here, we use new
methods instead of the comparison theorem to get the permanence of the system in consideration;
the additional condition in Chen′s paper (2007) is deleted.