bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermo-Physical Processes During the Production of XLPE Insulated Cables
Authors: Shugai Galina , Yakubenko P. A.
Published: May 2008

The cable manufacturing process involves several stages of mechanical and thermal treatments. Proper apriori estimation and modeling of the treatments outcome can provide a significant cost reduction in both the optimization of the existing installations and design of new manufacturing lines. Synthetic materials such as cross-linked polyethylene (XLPE) are most commonly used for insulation of high voltage cables. After the insulating material is extruded onto the conductor, the cable enters the curing tube with elevated temperatures, where added initiator (usually peroxide) decomposes and induces the cross-linking of polymer. In order to avoid the distortion of the insulation, the cable passes through the cooling zone before being wound on the take-up reel. In the present paper, a model of a vertical line for the thermal treatment of high voltage cables after the extrusion has been developed. The model accounts for various thermo-physical processes that occur in both the curing tube and the subsequent cooling zone. In particular, chemical processes such as the cross-linking and crystallization are incorporated.
Improvement of Tapping Mode AFM Imaging Stability by Operation Far Below Resonance Frequency of a Cantilever
Authors: Kowalewski Tomasz , Legleiter Justin
Published: May 2008

In tapping mode AFM, a cantilever is driven near its resonance frequency and intermittently strikes the sample while raster scanned across a surface. The oscillation amplitude is monitored via a feedback loop to extract topographical information of surfaces at the nanoscale. This paper deals with major factors limiting scanning speed: 1) the slow transient response of the cantilever, and 2) instabilities associated with systems with high quality factors (Q). Due to the slow transient response, the AFM has difficulty in instantly responding to steps along the surface, resulting in the need for slower scan rates. By driving the cantilever well below its resonance frequency, stability of the system is greatly improved, resulting in better feature tracking and the ability to scan at faster speeds.
Transformation of the Nitrogen Cycle: Recent Trends, Questions, and Potential Solutions
Authors: Galloway James N. , Townsend Alan R. , Erisman Jan Willem , Bekunda Mateete , Cai Zucong , Freney John R. , Martinelli Luiz A. , Seitzinger Sybil P. , Sutton Mark A.
Published: May 2008

Humans continue to transform the global nitrogen cycle at a record pace, reflecting an increased combustion of fossil fuels, growing demand for nitrogen in agriculture and industry, and pervasive inefficiencies in its use. Much anthropogenic nitrogen is lost to air, water, and land to cause a cascade of environmental and human health problems. Simultaneously, food production in some parts of the world is nitrogen-deficient, highlighting inequities in the distribution of nitrogen-containing fertilizers. Optimizing the need for a key human resource while minimizing its negative consequences requires an integrated interdisciplinary approach and the development of strategies to decrease nitrogen-containing waste.
Evaluation of
Toxoplasma gondii
Immunoglobulin G (IgG) and IgM Assays Incorporating the New Vidia Analyzer System
Authors: Calderaro Adriana , Piccolo Giovanna , Peruzzi Simona , Gorrini Chiara , Chezzi Carlo , Dettori Giuseppe
Published: May 2008

The new Vidia system is a fully automated system based on chemiluminescence and antigen bound to magnetic microparticles, which allows a fast measurement of
Toxoplasma gondii
-specific immunoglobulin G (IgG) and IgM levels. The analytical performances of the Vidia Toxo IgG and IgM assays were compared with those of the automated Vidas, AxSYM, and Liaison Toxo IgG and IgM assays. The comparative evaluation was performed utilizing 204 frozen sera belonging to 166 subjects and 201 fresh sera collected from 198 subjects. For the Vidia Toxo IgG system, the sensitivities were 100% in both the retrospective and prospective studies, and specificities were 98.39% in the retrospective study and 100% in the prospective study, respectively. The sensitivities of the other three Toxo IgG assays were 100%, and the specificities ranged from 96.77% to 100%. For the Vidia Toxo IgM assay, the sensitivity and specificity were 100% in both the retrospective and prospective studies. The overall sensitivities and specificities of the other three Toxo IgM assays ranged from 80% to 100% and from 99.44% to 100%, respectively. In our study, the Vidia system revealed excellent sensitivity (100% for both IgG and IgM assays) and good specificity (99.25% for IgG and 100% for IgM assays).
Presymptomatic Prediction of Sepsis in Intensive Care Unit Patients
Authors: Lukaszewski R. A. , Yates A. M. , Jackson M. C. , Swingler K. , Scherer J. M. , Simpson A. J. , Sadler P. , McQuillan P. , Titball R. W. , Brooks T. J. G. , Pearce M. J.
Published: May 2008

Postoperative or posttraumatic sepsis remains one of the leading causes of morbidity and mortality in hospital populations, especially in populations in intensive care units (ICUs). Central to the successful control of sepsis-associated infections is the ability to rapidly diagnose and treat disease. The ability to identify sepsis patients before they show any symptoms would have major benefits for the health care of ICU patients. For this study, 92 ICU patients who had undergone procedures that increased the risk of developing sepsis were recruited upon admission. Blood samples were taken daily until either a clinical diagnosis of sepsis was made or until the patient was discharged from the ICU. In addition to standard clinical and laboratory parameter testing, the levels of expression of interleukin-1β (IL-1β), IL-6, IL-8, and IL-10, tumor necrosis factor-α, FasL, and CCL2 mRNA were also measured by real-time reverse transcriptase PCR. The results of the analysis of the data using a nonlinear technique (neural network analysis) demonstrated discernible differences prior to the onset of overt sepsis. Neural networks using cytokine and chemokine data were able to correctly predict patient outcomes in an average of 83.09% of patient cases between 4 and 1 days before clinical diagnosis with high sensitivity and selectivity (91.43% and 80.20%, respectively). The neural network also had a predictive accuracy of 94.55% when data from 22 healthy volunteers was analyzed in conjunction with the ICU patient data. Our observations from this pilot study indicate that it may be possible to predict the onset of sepsis in a mixed patient population by using a panel of just seven biomarkers.
MDCK-SIAT1 Cells Show Improved Isolation Rates for Recent Human Influenza Viruses Compared to Conventional MDCK Cells
Authors: Oh Ding Yuan , Barr Ian G. , Mosse Jenny A. , Laurie Karen L.
Published: May 2008

The ability to isolate and propagate influenza virus is an essential tool for the yearly surveillance of circulating virus strains and to ensure accurate clinical diagnosis for appropriate treatment. The suitability of MDCK-SIAT1 cells, engineered to express increased levels of α-2,6-linked sialic acid receptors, as an alternative to conventional MDCK cells for isolation of circulating influenza virus was assessed. A greater number of influenza A (H1N1 and H3N2) and B viruses from stored human clinical specimens collected between 2005 and 2007 were isolated following inoculation in MDCK-SIAT1 cells than in MDCK cells. In addition, a higher titer of virus was recovered following culture in MDCK-SIAT1 cells. All A(H1N1) viruses recovered from MDCK-SIAT1 cells were able to agglutinate both turkey and guinea pig red blood cells (RBC), while half of the A(H3N2) viruses recovered after passage in MDCK-SIAT1 cells lost the ability to agglutinate turkey RBC. Importantly, the HA-1 domain of the hemagglutinin gene was genetically stable after passaging in MDCK-SIAT1 cells, a feature not always seen following MDCK cell or embryonated chicken egg passage of human influenza virus. These data indicate that the MDCK-SIAT1 cell line is superior to conventional MDCK cells for isolation of human influenza virus from clinical specimens and may be used routinely for the isolation and propagation of current human influenza viruses for surveillance, diagnostic, and research purposes.
A Role for E1B-AP5 in ATR Signaling Pathways during Adenovirus Infection
Authors: Blackford Andrew N. , Bruton Rachel K. , Dirlik Orkide , Stewart Grant S. , Taylor A. Malcolm R. , Dobner Thomas , Grand Roger J. A. , Turnell Andrew S.
Published: May 2008

E1B-55K-associated protein 5 (E1B-AP5) is a cellular, heterogeneous nuclear ribonucleoprotein that is targeted by adenovirus (Ad) E1B-55K during infection. The function of E1B-AP5 during infection, however, remains largely unknown. Given the role of E1B-55K targets in the DNA damage response, we examined whether E1B-AP5 function was integral to these pathways. Here, we show a novel role for E1B-AP5 as a key regulator of ATR signaling pathways activated during Ad infection. E1B-AP5 is recruited to viral replication centers during infection, where it colocalizes with ATR-interacting protein (ATRIP) and the ATR substrate replication protein A 32 (RPA32). Indeed, E1B-AP5 associates with ATRIP and RPA complex component RPA70 in both uninfected and Ad-infected cells. Additionally, glutathione
S
-transferase pull-downs show that E1B-AP5 associates with RPA components RPA70 and RPA32 directly in vitro. E1B-AP5 is required for the ATR-dependent phosphorylation of RPA32 during infection and contributes to the Ad-induced phosphorylation of Smc1 and H2AX. In this regard, it is interesting that Ad5 and Ad12 differentially promote the phosphorylation of RPA32, Rad9, and Smc1 during infection such that Ad12 promotes a significant phosphorylation of RPA32 and Rad9, whereas Ad5 only weakly promotes RPA32 phosphorylation and does not induce Rad9 phosphorylation. These data suggest that Ad5 and Ad12 have evolved different strategies to regulate DNA damage signaling pathways during infection in order to promote viral replication. Taken together, our results define a role for E1B-AP5 in ATR signaling pathways activated during infection. This might have broader implications for the regulation of ATR activity during cellular DNA replication or in response to DNA damage.
An Extremely Diverse CD4 Response to Vaccinia Virus in Humans Is Revealed by Proteome-Wide T-Cell Profiling
Authors: Jing Lichen , Davies D. Huw , Chong Tiana M. , Chun Sookhee , McClurkan Christopher L. , Huang Jay , Story Brian T. , Molina Douglas M. , Hirst Siddiqua , Felgner Philip L. , Koelle David M.
Published: May 2008

CD4 T cells are required for the maintenance and recall of antiviral CD8 T cells and for antibody responses. Little is known concerning the overall architecture of the CD4 response to complex microbial pathogens. In a whole-proteome approach, 180 predicted open reading frames (ORFs) in the vaccinia virus genome were expressed and tested using responder cells from 20 blood samples from 11 vaccinees. Validation assays established the sensitivity and specificity of the system. Overall, CD4 responses were detected for 122 ORFs (68%). A mean of 39 ORFs were recognized per person (range, 13 to 63). The most frequently recognized ORFS were present in virions, including A3L and A10L (core proteins), WR148 (a fragmented homolog of an orthopoxvirus protein that forms inclusions in cells), H3L (a membrane protein), D13L (a membrane scaffold protein), and L4R (a nucleic acid binding protein). Serum immunoglobulin G profiling by proteome microarray detected responses to 45 (25%) of the ORFs and confirmed recent studies showing a diverse response directed to membrane and nonmembrane antigens. Our results provide the first empirical whole-proteome data set regarding the global CD4 response to full-length proteins in a complex virus and are consistent with the theory that abundant structural proteins are immunodominant.
Reverse Transcriptase- and RNA Packaging Signal-Dependent Incorporation of APOBEC3G into Hepatitis B Virus Nucleocapsids
Authors: Nguyen David H. , Hu Jianming
Published: May 2008

APOBEC3G (A3G) is a cytidine deaminase that can inhibit a wide range of retroviruses, including the para-retrovirus hepatitis B virus (HBV). The antiviral function of A3G depends on its incorporation into assembling viral particles. However, it remains enigmatic how A3G is specifically packaged into a variety of unrelated viruses. By adopting a native agarose gel electrophoresis assay that can specifically measure the levels of A3G incorporation into HBV nucleocapsids, we found that A3G is specifically packaged into replication-competent HBV nucleocapsids in a fashion that is dependent on both the viral reverse transcriptase (RT) and viral RNA packaging signal, ε. In contrast, A3G is not incorporated into empty capsids formed in the absence of RT or ε. We demonstrated that the packaged A3G was protected from protease digestion by the nucleocapsids, thus confirming its interior localization. We also showed that A3G could bind RT specifically in an RNA-independent manner, which may be responsible for mediating the specific incorporation of A3G into replication-competent nucleocapsids. Finally, we provide evidence that the N-terminal domain of A3G is required for packaging into HBV nucleocapsids.
Extreme Dependence of gH and gL Expression on ORF57 and Association with Highly Unusual Codon Usage in Rhesus Monkey Rhadinovirus
Authors: Bilello John P. , Morgan Jennifer S. , Desrosiers Ronald C.
Published: May 2008

Standard vectors for high-level expression elicited undetectable levels of the gH and gL glycoproteins of rhesus monkey rhadinovirus (RRV) following transient-transfection assays under a variety of conditions. These same vectors and conditions yielded high levels of RRV gB expression. Unlike other genes of RRV, both the gH and gL genes were noted to have a highly aberrant, suboptimal codon usage. High levels of RRV gH and gL expression were achieved by two alternative means: codon optimization or coexpression of RRV ORF57. The failure of gH and gL to be expressed in the absence of ORF57 and in the absence of codon optimization could not be explained by the failure of RNA to egress from the nucleus. Rather, the defect in gH and gL expression appeared to be cytoplasmic in nature. It is not clear at the present time whether the aberrant codon usage for gH and gL of RRV is an intentional regulatory strategy used by the virus or whether it is driven by some external force, such as intrinsic immunity. In any event, our results indicate that the need of ORF57 for gH and gL expression can be circumvented by codon optimization, that RRV ORF57 acts principally to allow translation of gH and gL RNA in the cytoplasm, and that this activity of ORF57 is related in some way to the aberrant codon usage of the gH and gL RNAs.
Aberrant Lymphocyte Activation Precedes Delayed Virus-Specific T-Cell Response after both Primary Infection and Secondary Exposure to Hepadnavirus in the Woodchuck Model of Hepatitis B Virus Infection
Authors: Gujar Shashi A. , Jenkins Adam K. , Guy Clifford S. , Wang Jinguo , Michalak Tomasz I.
Published: May 2008

The contribution of virus-specific T lymphocytes to the outcome of acute hepadnaviral hepatitis is well recognized, but a reason behind the consistent postponement of this response remains unknown. Also, the characteristics of T-cell reactivity following reexposure to hepadnavirus are not thoroughly recognized. To investigate these issues, healthy woodchucks (Marmota monax) were infected with liver-pathogenic doses of woodchuck hepatitis virus (WHV) and investigated unchallenged or after challenge with the same virus. As expected, the WHV-specific T-cell response appeared late, 6 to 7 weeks postinfection, remained high during acute disease, and then declined but remained detectable long after the resolution of hepatitis. Interestingly, almost immediately after infection, lymphocytes acquired a heightened capacity to proliferate in response to mitogenic (nonspecific) stimuli. This reactivity subsided before the WHV-specific T-cell response appeared, and its decline coincided with the cells' augmented susceptibility to activation-induced death. The analysis of cytokine expression profiles confirmed early in vivo activation of immune cells and revealed their impairment of transcription of tumor necrosis factor alpha and gamma interferon. Strikingly, reexposure of the immune animals to WHV swiftly induced hyperresponsiveness to nonspecific stimuli, followed again by the delayed virus-specific response. Our data show that both primary and secondary exposures to hepadnavirus induce aberrant activation of lymphocytes preceding the virus-specific T-cell response. They suggest that this activation and the augmented death of the cells activated, accompanied by a defective expression of cytokines pivotal for effective T-cell priming, postpone the adaptive T-cell response. These impairments likely hamper the initial recognition and clearance of hepadnavirus, permitting its dissemination in the early phase of infection.
A Five-Amino-Acid Deletion of the Eastern Equine Encephalitis Virus Capsid Protein Attenuates Replication in Mammalian Systems but Not in Mosquito Cells
Authors: Aguilar Patricia V. , Leung Lawrence W. , Wang Eryu , Weaver Scott C. , Basler Christopher F.
Published: May 2008

Eastern equine encephalitis virus (EEEV) is a human and veterinary pathogen that causes sporadic cases of fatal neurological disease. We previously demonstrated that the capsid protein of EEEV is a potent inhibitor of host cell gene expression and that this function maps to the amino terminus of the protein. We now identify amino acids 55 to 75, within the N terminus of the capsid, as critical for the inhibition of host cell gene expression. An analysis of stable EEEV replicons expressing mutant capsid proteins corroborated these mapping data. When deletions of 5 to 20 amino acids within this region of the capsid were introduced into infectious EEEV, the mutants exhibited delayed replication in Vero cells. However, the replication of the 5-amino-acid deletion mutant in C710 mosquito cells was not affected, suggesting that virus replication and assembly were affected in a cell-specific manner. Both 5- and 20-amino-acid deletion mutant viruses exhibited increased sensitivity to interferon (IFN) in cell culture and impaired replication and complete attenuation in mice. In summary, we have identified a region within the capsid protein of EEEV that contributes to the inhibition of host gene expression and to the protection of EEEV from the antiviral effects of IFNs. This region is also critical for EEEV pathogenesis.
Blocking Antibody Access to Neutralizing Domains on Glycoproteins Involved in Entry as a Novel Mechanism of Immune Evasion by Herpes Simplex Virus Type 1 Glycoproteins C and E
Authors: Hook Lauren M. , Huang Jialing , Jiang Ming , Hodinka Richard , Friedman Harvey M.
Published: May 2008

Herpes simplex virus type 1 (HSV-1) glycoprotein C (gC) blocks complement activation, and glycoprotein E (gE) interferes with IgG Fc-mediated activities. While evaluating gC- and gE-mediated immune evasion in human immunodeficiency virus (HIV)-HSV-1-coinfected subjects, we noted that antibody alone was more effective at neutralizing a strain with mutations in gC and gE (gC/gE) than a wild-type (WT) virus. This result was unexpected since gC and gE are postulated to interfere with complement-mediated neutralization. We used pooled human immunoglobulin G (IgG) from HIV-negative donors to confirm the results and evaluated mechanisms of the enhanced antibody neutralization. We demonstrated that differences in antibody neutralization cannot be attributed to the concentrations of HSV-1 glycoproteins on the two viruses or to the absence of an IgG Fc receptor on the gC/gE mutant virus or to enhanced neutralization of the mutant virus by antibodies that target only gB, gD, or gH/gL, which are the glycoproteins involved in virus entry. Since sera from HIV-infected subjects and pooled human IgG contain antibodies against multiple glycoproteins, we determined whether differences in neutralization become apparent when antibodies to gB, gD, or gH/gL are used in combination. Neutralization of the gC/gE mutant was greatly increased compared that of WT virus when any two of the antibodies against gB, gD, or gH/gL were used in combination. These results suggest that gC and gE on WT virus provide a shield against neutralizing antibodies that interfere with gB-gD, gB-gH/gL, or gD-gH/gL interactions and that one function of virus neutralization is to prevent interactions between these glycoproteins.
Characterization of the New World Monkey Homologues of Human Poliovirus Receptor CD155
Authors: Khan Shaukat , Peng Xiaozhong , Yin Jiang , Zhang Ping , Wimmer Eckard
Published: May 2008

In contrast to Old World monkeys, most New World monkeys (NWMs) are not susceptible to poliovirus (PV), regardless of the route of infection. We have investigated the molecular basis of restricted PV pathogenesis of NWMs with two kidney cell lines of NWMs, TMX (tamarin) and NZP-60 (marmoset), and characterized their PV receptor homologues. TMX cells were susceptible to infection by PV1 (Mahoney) and PV3 (Leon) but not by PV2 (Lansing). Binding studies to TMX cells indicated that the formation of PV/receptor complexes increased when measured first at 4°C and then at 25°C, whereas PV2 did not significantly bind to TMX cells at either temperature. On the other hand, NZP-60 cells were not susceptible to infection by any of the PV serotypes. However, a low amount of PV1 bound to NZP-60 cells at 4°C, but there was no increase of binding at 25°C. In contrast, both NWM cell lines supported genome replication and virion formation when transfected with viral RNAs of either serotype, an observation indicating that infection was blocked in receptor-virus interaction. To overcome the receptor block, we substituted 3 amino acids in the marmoset receptor (nCD155), H80Q, N85S, and P87S, found in the human PV receptor, hCD155. Cells expressing the mutant receptor (L-nCD155mt) were now susceptible to infection with PV1, which correlated with an increase in PV1-bound receptor complexes from 4°C to 25°C. L-nCD155mt cells were, however, still resistant to PV2 and PV3. These data show that an increase in the formation of PV/receptor complexes, when measured at 4°C and at 25°C, correlates with and is an indicator of successful infection at 37°C, suggesting that the complex formed at 25°C may be an intermediate in PV uptake.
A Tetravalent Dengue Vaccine Based on a Complex Adenovirus Vector Provides Significant Protection in Rhesus Monkeys against All Four Serotypes of Dengue Virus
Authors: Raviprakash Kanakatte , Wang Danher , Ewing Dan , Holman David H. , Block Karla , Woraratanadharm Jan , Chen Lan , Hayes Curtis , Dong John Y. , Porter Kevin
Published: May 2008

Nearly a third of the human population is at risk of infection with the four serotypes of dengue viruses, and it is estimated that more than 100 million infections occur each year. A licensed vaccine for dengue viruses has become a global health priority. A major challenge to developing a dengue vaccine is the necessity to produce fairly uniform protective immune responses to all four dengue virus serotypes. We have developed two bivalent dengue virus vaccines, using a complex adenovirus vector, by incorporating the genes expressing premembrane (prM) and envelope (E) proteins of dengue virus types 1 and 2 (dengue-1 and -2, respectively) (CAdVax-Den12) or dengue-3 and -4 (CAdVax-Den34). Rhesus macaques were vaccinated by intramuscular inoculation of a tetravalent dengue vaccine formulated by combining the two bivalent vaccine constructs. Vaccinated animals produced high-titer antibodies that neutralized all four serotypes of dengue viruses in vitro. The ability of the vaccine to induce rapid, as well as sustained, protective immune responses was examined with two separate live-virus challenges administered at 4 and 24 weeks after the final vaccination. For both of these virus challenge studies, significant protection from viremia was demonstrated for all four dengue virus serotypes in vaccinated animals. Viremia from dengue-1 and dengue-3 challenges was completely blocked, whereas viremia from dengue-2 and dengue-4 was significantly reduced, as well as delayed, compared to that of control-vaccinated animals. These results demonstrate that the tetravalent dengue vaccine formulation provides significant protection in rhesus macaques against challenge with all four dengue virus serotypes.
Chromosome numbers of selected Alaskan vascular plants
Authors: Dawe Janice C. , Murray David F.
Published: May 2008

Chromosome numbers and taxonomic notes are presented for 33 Alaskan vascular taxa. First counts are reported for Aquilegia brevistyla Hooker, Draba murrayi Mulligan, Erysimum angustatum Rydberg, Smelowskia calycina ssp. media Drury & Rollins, Thlaspi arcticum Porsild, Oxytropis kobukensis Welsh, Cryptantha shackletteana Higgins, Mertensia drummondii (Lehmann) G. Don, and Erigeron muirii Gray. New ploidy levels are noted for Draba lactea Adams, Oxytropis campestris ssp. varions (Rydberg) Barneby, Oxytropis viscida Nuttall, Oxytropis scammaniana Hultén, Mertensia paniculata (Aiton) G. Don, Castilleja caudata (Pennell) Rebrecht, Artemisia senjavinensis Besser, Erigeron caespitosus Nuttall, and Erigeron grandiflorus Hooker. Infraspecific ploidy is discussed for Luzula arcuata (Wahlenberg) Swartz, Lloydia serotina (L.) Rchb., Rumex arcticus Trautvetter, Claytonia sibirica L., Papaver nudicaule L., Oxytropis campestris (L.) DC. complex, Epilobium latifolium L., and Artemisia tilesii Ledebour.
Developmental aspects of flavonoid patterns in Brassica campestris var. oleifera: a preliminary study
Authors: Classen D. , Nozzolillo C.
Published: May 2008

Field-grown plants of Brassica campestris L. var. oleifera (summer turnip rapeseed) were harvested at various growth stages from seedling through to maturity. Cotyledons, roots, hypocotyls, leaves, stems, and flowers were sampled as available and freeze-dried prior to extraction. Chlorophyll-free, unhydrolysed alcoholic extracts were subjected to two-dimensional chromatography on polyamide thin layers to establish flavonoid patterns. Major aglycones of compounds were tentatively identified on the basis of mobility, colour reactions with a diphenylboric acid ethanolamine spray, and co-chromatography with standards. Each organ was found to have a pattern characteristic to itself which changed little with age. The greatest variety of compounds was present in leaf tissues. Only two compounds, presumably highly glycosylated derivatives of quercetin, were common to all tissues.
The taxonomy of Bryum oblongum and B. blindii
Authors: Shaw A. Jonathan
Published: May 2008

Plants agreeing with the type specimen of Bryum oblongum Lindb. were found in northern British Columbia, the Yukon Territory, and Alaska. Bryum oblongum is otherwise known from central Europe, Fennoscandia, and northern Asia. Some authors have considered B. oblongum to be a variety or subspecies of B. blindii B.S.G., with which it shares a number of structural features. Shared and presumed apomorphous (derived) character-states indicate that B. oblongum and B. blindii are closely related, but quantitative evidence shows that the two can be distinguished by at least four structural characters. Propagula were found on about 20% of the total specimens of B. blindii examined, but no propagula were observed on B. oblongum. Ecological data from collection information indicate that B. blindii occurs primarily on calcareous silts and clays, while B. oblongum is more frequent on mildly acidic to neutral substrates. Bryum oblongum is considered a distinct species, and both taxa are described and illustrated.
Protoplast isolation and fusion in three Ulmus species
Authors: Redenbaugh Keith , Karnosky David F. , Westfall Robert D.
Published: May 2008

Protoplasts were isolated from cotyledons, callus, and suspension cultures of Ulmus americana L. and U. pumula L. and from cotyledons and callus of U. parvifolia Jacq. using various enzyme solutions. Isolation frequencies (percent protoplasts in a solution containing both protoplasts and broken or damaged protoplasts, but very few intact cells) were usually about 10%; however, for U. pumila cotyledons, protoplast frequencies reached 100%. In a limited number of cases, cell wall regeneration occurred after 4–21 days and cell division after 9–21 days. Finally, U. pumila protoplasts were fused using a PEG–calcium solution.
Morphological variation and isozymes of North American Phyllospadix (Potamogetonaceae)
Authors: McMillan Calvin , Phillips Ronald C.
Published: May 2008

In 8 of 10 enzyme systems, isozymes for Phyllospadix serrulatus Rupr. ex Aschers. from Washington and Oregon were different from those of P. scouleri Hook, and P. torreyi S. Wats, from Washington, Oregon, and California. Plants of P. serrulatus continued to produce the widest leaves in laboratory cultures. Plants of P. scouleri and P. torreyi that differed in leaf width, leaf-tip characteristics, and (or) inflorescences at each collection site continued to show morphological differences in culture but had similar isozyme features in 8 of 10 systems and only slight differences in isozymes of peroxidase and alcohol dehydrogenase. Plants with single-spathe inflorescences, characteristic of P. scouleri, vary widely with broad leaves and rounded leaf tips in the northern part of the distribution and with narrow leaves and notched leaf tips at the southern part of the distribution. Plants with multiple-spathe inflorescences, characteristic of P. torreyi, usually have narrow leaves with notched leaf tips throughout the distribution on the West Coast. Some plants from the Monterey Peninsula continued to produce wide leaves, notched leaf tips, and multiple-spathe inflorescences in culture but had isozyme patterns that were more similar to those of P. scouleri, suggesting possible hybridization in the southern part of the range.
The interaction of divalent cations with pectic substances and their influence on acid-induced cell wall loosening
Authors: Tepfer Mark , Taylor Iain E. P.
Published: May 2008

Certain divalent cations are potent inhibitors of acid-induced cell wall loosening in both higher plants and green algae. It has been proposed that this inhibition involves the formation of pectic gels in the cell wall. To test this hypothesis, we have looked for a relationship between the ability of various ions to inhibit growth and (i) their ability to cause gelation of isolated pectins, (ii) their binding affinity for isolated cell walls, and (iii) their binding affinity for purified pectin. There is good correspondence between the effectiveness of an ion as a growth inhibitor and its binding affinity for the cell wall. There is very poor correspondence between growth inhibition and the ability to induce the gelation of pectin. Our results indicate that pectic gel formation is not involved in cation-induced growth inhibition, but that the major cation binding site in the cell wall may be involved in a nongel-forming capacity.
Étude de la végétation des zones riveraines de l'archipel des Cent-îles du fleuve Saint-Laurent, Québec
Authors: Tessier Claude , Maire Alain , Aubin Antoine
Published: May 2008

The riparian vegetation of about 30 islands located upstream of lake Saint-Pierre has been analysed. Eleven natural vegetation units were identified, described and defined along with five units of human origin and six agricultural types. The aquatic habitat is characterized by a Vallisneria americana plant community-type. In the semiaquatic floodland habitats, four community-types were present: a Sagittaria latifolia, a Sparganium eurycarpum, a Phalaris arundinacea, and a Scirpus pedicellatus type. The wetlands were characterized by an Acer saccharinum – Ulmus americana – Fraxinus pennsylvanica forest. Both vegetational analysis and fluctuations of the superficial water table pointed to the existence of four variants in this last type of riparian forest. Those are respectively a Matteuccia struthiopteris, a Laportea canadensis, an Onoclea sensibilis, and a Rorippa amphibia variant. Granulometric and pedologie analyses of typical soil samples are also presented and discussed.
Flora and vegetation of an old field community at Erindale, southern Ontario
Authors: Maycock Paul F. , Guzikowa Malgorzata
Published: May 2008

A stable old field 5.4 ha in extent and undisturbed for at least 50 years is described qualitatively and in quantitative terms. Despite relative physiognomic uniformity, seven homogeneous areas were studied using presence and frequency and estimated cover in randomly distributed 1-m2 quadrats. Of the rich total flora of 118 species, 99 were found in the communities and only 61 had measurable cover. Agropyron repens, Vicia cracca, and Poa pratensis were major dominants followed by Solidago altissima, Phleum pratense, and Hieracium pratense. Although native (52%) outnumber introduced species (48%) in the field as a whole, in terms of cover, exotic plants may exceed indigenous species by at least 2:1 and perhaps as high as 4:1, depending on the designation of species of controversial origin. Solidago species seem to be the only native plants clearly capable of coping with the competition provided by exotics. Species respond to small differences in site moisture and to different stages of succession toward forest which appear to vary mainly with position in the field.
Digitosarcinella caseariae n. gen., n. sp. and Questieriella synanamorphs of the so-called Amazonia caseariae
Authors: Hughes S. J.
Published: May 2008

Digitosarcinella caseariae n. gen., n. sp., which produces cheiroid conidia on hyphae with sessile hyphopodia, and its Questieriella synanamorph (Q. caseariae comb. nov. ≡ Amazonia caseariae) are illustrated and described. The status of the name Amazonia caseariae is discussed.
Schiffnerulaceous fungi on Compositae from the Americas
Authors: Hughes S. J.
Published: May 2008

The possible host range of schiffnerulaceous species is briefly discussed. Six species of Schiffnerula and one of Sarcinella, which occur on Compositae in the Americas, are illustrated and redescribed from their type collections. Schiffnerula spectabilis, S. secunda, S. compositarum, and 5. oyedaeae produce a Questieriella anamorph, but S. concinna does not. Sarcinella milleriae produces a Questieriella synanamorph. Schiffnerula barnadesiae (synanamorphs: Questieriella + Mitteriella) and Sarcinella vernoniae (synanamorph: Questieriella), also described from the Americas on Compositae, are briefly mentioned.
Microspectrophotometric evaluation of rosmarinic acid accumulation in single cultured plant cells
Authors: Chaprin N. , Ellis B. E.
Published: May 2008

By use of microspectrophotometry in the ultraviolet region, rosmarinic acid was confirmed to be largely accumulated in the vacuoles of suspension cultured cells of Anchusa officinalis and Coleus blumei. The relative internal concentration of this metabolite in living cells can also be estimated with this technique. A comparison of the rosmarinic acid production and nuclear DNA content of individual cells suggests that the culture-related genome expansion may depress rosmarinic acid accumulation.
A physiological study of Panicum maximum infected by Phyllachora paspalicola
Authors: Rey M. E. C. , Garnett H. M.
Published: May 2008

Detailed morphological studies of the leaf pathogen Phyllachora paspalicola (tarspot) on its host Panicum maximum Jacq. have been previously described. This research reports physiological changes in leaf tissue infected by P. paspalicola. Aspects of photosynthetic and nitrogen metabolism were studied in healthy and tarspot-infected leaf tissue. Concentrations of glucose, fructose, and sucrose in infected and noninfected leaves were also measured. Gross and net photosynthetic rates declined significantly in tarspot-infected leaves at high disease intensities (>25%). Chlorophyll content declined in leaves exhibiting >25% infection. Transmission electron microscopy revealed disruption of lamellae and formation of large lipid bodies in infected mesophyll and bundle sheath cells. Significant changes in some C4 enzymes, such as NADP malate dehydrogenase, aspartate aminotransferase, ribulose-1,5-bisphosphate carboxylase, phosphoenolpyruvate carboxylase, were noted in tarspot-infected leaves. Small differences in the activities of NADP–malate enzyme and alanine aminotransferase were also observed. Activity of the respiratory enzyme succinate dehydrogenase was also stimulated in intensely infected leaves. An increase in nitrate levels was measured as ascopore sporogenesis occurred. At sporulation and during postsporulation, total nitrogen declined in leaves exhibiting intense infection (>25%). A small increase in glucose and fructose content occurred in leaves exhibiting mature fruiting bodies, whereas a significant (p = 0.05) increase in sucrose content was observed in infected leaves.
A laboratory culture system for pathological and physiological studies of rooted aquatic plants
Authors: Hoffmann J. P. , Colman J. A. , Kutchera K. M. , Nordheim E. V. , Andrews J. H.
Published: May 2008

A biphasic system was designed for growing rooted Eurasian water milfoil, Myriophyllum spicatum L., to avoid artificial characteristics of flask culture. Aquaria (21 L) containing undergravel filters, air-lift pumps, 50-W heaters, and Plexiglas lids were sterilized in 70% ethanol and assembled aseptically. Plant shoots were rooted separately in polypropylene cups containing 60 g of artificial sediment approximating natural marl. The sediment provided over 90% of the nitrogen and phosphorus in the plants after 22 days growth. Plants were immersed in a mineral-salts medium with levels of nitrogen and phosphorus comparable with lake concentrations. Aeration was at 0.15 L ∙ min−1 and ranges of temperature and light intensity were from 17 to 32 °C and 30 to 250 μE ∙ m−2 ∙ s−1, respectively. The peak photosynthetic rate was 14 mg O2 ∙ g dry weight−1 ∙ h−1. The maximum specific growth rate, 0.14 mg ∙ mg−1 ∙ day−1, occurred at 27 °C and 250 μE ∙ m−2 ∙ s−1 and lasted for about 3 weeks before light became limiting. Bacterial density, ammonium nitrogen, soluble reactive phosphorus, and total phosphorus exhibited rapid changes during the first 12 days of the growth period, after which fluctuations diminished. The between-aquaria variance in shoot growth rate was insignificant (P > 0.70). When inorganic carbon in the liquid medium and phosphorus in the sediment were lowered from 2.86 to 1.14 mmol C ∙ L−1 and from 0.7 to 0.2 mg P ∙ g dry weight−1, milfoil growth was reduced by 47 and 74%, respectively. Control of the physiochemical environment, small variability, and high reproducibility make this a sensitive system for discerning various treatment effects, including those of pathogens.
Fossil remains of the mycorrhizal fungal Glomus fasciculatum complex in postglacial lake sediments from Maine
Authors: Anderson R. Scott , Homola Richard L. , Davis Ronald B. , Jacobson Jr. George L.
Published: May 2008

Specimens of the vesicular–arbuscular mycorrhizal fungal Glomus fasciculatum complex have been identified from lake sediment cores from Gould Pond (central Maine) and Upper South Branch Pond (north central Maine). The fungus became established with tundra vegetation on newly developing soils soon after the melting of Wisconsin ice. This is the first record of such an occurrence for North America. The earliest specimens from Gould Pond were deposited in sediment dated at about 13 000 years old and those at Upper South Branch Pond between about 12 500 and 11 000 years old. This is at least 1000 years prior to the arrival of trees in those areas. Sedimentologic and biologic evidence indicates soil instability and relatively high soil erosion rates from the watersheds during the late-glacial period. Thus erosion probably accounts for the abundance of Glomus in late-glacial sediments. The reduced abundance of the fungus in Holocene sediments is attributed to a decrease in the rate of soil erosion after the establishment of trees.
Descriptions of Spiniferomonas silverensis sp. nov. and S. minuta sp. nov. and an assessment of form variation in their closest relative, S. trioralis (Chrysophyceae)
Authors: Nicholls Kenneth H.
Published: May 2008

Two new species of the planktonic noncolonial chrysophyte genus Spiniferomonas (S. silverensis sp. nov. and S. minuta sp. nov.) are described from several localities in Ontario, Canada. Scale structure is distinctive and does not integrate with scale structure of their closest relative, S. trioralis Tak. Spiniferomonas trioralis is very common in Ontario; its scale structure is relatively constant with the exception of spine-scale length, which in the Ontario specimens ranged from 4 to 24 μm. The highest observed ratio of longest to shortest spine scale on individual cells was 2.3:1. It is now apparent that the form f. cuspidata Balonov should be abandoned, since there are apparently no differences other than spine length separating this form from f. trioralis.
Polyacrylamide–agarose gel electrophoretic analysis of tobacco mosaic virus disassembly intermediates
Authors: Hogue Richard , Asselin Alain
Published: May 2008

The intermediates of disassembly of the U1, U4, U6, and U7 strains of tobacco mosaic virus (TMV) induced by alkali and urea were directly analysed by electrophoresis in composite polyacrylamide (2.0 to 2.5% (w/v)) – agarose (0.5% (w/v)) gels, using a discontinuous buffer system with Tris, borate, EDTA, and sodium chloride (pH 8.3). The results show no difference between the disassembly patterns of the four strains. In the case of alkaline stripping, two new major partially stripped virus (PSV) particles (PSV 5a and PSV 5c) and several minor intermediates were characterized. The overall results indicate that polyacrylamide–agarose gel electrophoresis is superior to agarose gel electrophoresis and to sucrose density gradient ccntrifugation for the analytical separation of PSVs. Polyacrylamide–agarose gel electrophoresis is thus a rather simple, rapid, and efficient method of studying in vitro disassembly of plant viruses.
Synthesis of Elaphomyces muricatus + Pinus sylvestris ectomycorrhizae
Authors: Miller Steven L. , Miller Jr. Orson K.
Published: May 2008

This study reports the pure culture isolation of Elaphomyces muricatus Fries for the first time and the subsequent formation of ectomycorrhizae with Pinus sylvestris (L.). Synthesized Elaphomyces muricatus ectomycorrhizae had a tightly appressed mantle of irregular syncnchyma and a well-developed Hartig net. Extramatrical hyphae were thick walled with minute asperulations. Synthesized E. muricatus ectomycorrhizae gradually accumulated darkly safranin staining material in epidermal and cortical cells. The synthesized ectomycorrhizae agreed in all respects with ectomycorrhizae associated with E. muricatus ascocarps. Elaphomyces muricatus in pure culture produced an anamorphic stage consisting of thick-walled asexual spores which aggregated into bulbil-like masses. Ectomycorrhizal morphology, mantle anatomy, and cultural characteristics of E. muricatus were also examined in view of the possible relationship to Cenococcum geophilum.
The relationship between the aboveground dry weight and diameter for a wide size range of erect land plants
Authors: Freedman B.
Published: May 2008

For 765 stems of plants that spanned eight orders of magnitude of aboveground dry weight (DWT) and three orders of magnitude of stem diameter (DIAM), a plot of log10DWT vs. log10DIAM was highly linear, with an r2 value of 0.997 and a slope of 2.6. The value of this slope may be related to the minimum diameters that are required by upright plants to withstand the horizontal forces of drag that arc exerted at high wind speeds. The multispecies biomass regression gave a similar estimate of the standing crop of a conifer stand to that computed using species- and site-specific tree regressions, indicating the possible general use of such equations in estimating the standing crops of terrestrial ecosystems.
Phosphore, calcium, silicium et fer dans des cristaux, extraits de graines sèches de Raphanus
Authors: Genevès Louis , Rutin Jacques , Halpern Sylvain
Published: May 2008

Samples were taken from dry seeds of radish and fixed in glutaraldehyde. Ultrathin sections were observed without contrasting treatment. From cotyledonary parenchyma, it was possible to obtain powders or prints, which were observed by transmission electron microscopy. They showed several types of crystals. In the ultrathin sections of parenchyma cells, the crystals are included in globoids. Electron probe microanalysis with a wavelength dispersive spectrometer (Camebax microprobe) showed that they were rich in P, Ca, and Mg. In the powders and the prints, several polymorphic crystals, of varied sizes, were observed; these were sensitive to the electron beam. Some have relatively high ratios in Ca, lower ratios of S, and other elements, such as Si. Others possessed high ratios of Si with other elements, such as Ca and Al. The latter were less dense, more stable under the beam and their average diameter was smaller. Other crystals were smaller (some tenths of a micrometre). They were electron dense and very stable. Some of these were rich in Fe and could contain other elements (among others Si, Ca and P).
A scanning electron microscope study of the development and surface features of floral organs of tomato (Lycopersicon esculentum)
Authors: Sekhar K. N. Chandra , Sawhney V. K.
Published: May 2008

The initiation and development and the surface features of floral organs of tomato (Lycopersicon esculentum Mill.) were examined using scanning electron microscopy. After the transformation of the vegetative apex into the floral apex, the floral organs appeared in the following sequence: sepals, petals, stamens, and carpels. The pattern of initiation was helical for the sepals and simultaneous for petals, stamens, and carpels. There was a progressive increase in the diameter of the apex associated with the initiation of each whorl of organs. Following initiation, the sepal and petal primordia fused at the basal region by "zonal growth," but the cohesion of anthers to form a staminal tube occurred later in development and was achieved by the interlocking of epidermal hairs produced on the lateral and adaxial surfaces of anthers. Carpel primordia were produced at the circumference of the remaining meristem and were fused laterally early in development. Epidermal hairs of different types and frequencies were observed on the adaxial and abaxial surfaces of sepals and petals and on the adaxial and lateral surfaces of the anthers. In the gynoecium, hairs were present only on the lower half of the style and were absent on the ovary. Stomata were observed on the sepals, petals, and style, but not on the anthers or ovary. Raised stomata were present only on young developing sepals and the style and were absent on mature organs. Cuticular thickenings were also observed on the abaxial surfaces of sepals, petals, and stamens, but not on the gynoecium.
Karyotypic analysis of Polymyxa graminis (Plasmodiophoromycetes) based on serial sections of synaptonemal complexes
Authors: Braselton James P.
Published: May 2008

Three pachytene nuclei of Polymyxa graminis Ledingham were reconstructed from serial thin sections. Thirty synaptonemal complexes (SCs) were counted, indicating the identical haploid number (30) that was reported for Polymyxa betae. SCs of P. graminis and P. betae were similar in structure, and nuclear volumes and total lengths of SCs per nucleus were not significantly different for the two species.