bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of Three Interferon-Inducible Cellular Enzymes That Inhibit the Replication of Hepatitis C Virus
Authors: Jiang Dong , Guo Haitao , Xu Chunxiao , Chang Jinhong , Gu Baohua , Wang Lijuan , Block Timothy M. , Guo Ju-Tao
Published: December 2007

Hepatitis C virus (HCV) infection is a common cause of chronic hepatitis and is currently treated with alpha interferon (IFN-α)-based therapies. However, the underlying mechanism of IFN-α therapy remains to be elucidated. To identify the cellular proteins that mediate the antiviral effects of IFN-α, we created a HEK293-based cell culture system to inducibly express individual interferon-stimulated genes (ISGs) and determined their antiviral effects against HCV. By screening 29 ISGs that are induced in Huh7 cells by IFN-α and/or up-regulated in HCV-infected livers, we discovered that viperin, ISG20, and double-stranded RNA-dependent protein kinase (PKR) noncytolytically inhibited the replication of HCV replicons. Mechanistically, inhibition of HCV replication by ISG20 and PKR depends on their 3′-5′ exonuclease and protein kinase activities, respectively. Moreover, our work, for the first time, provides strong evidence suggesting that viperin is a putative radicalS-adenosyl-l-methionine (SAM) enzyme. In addition to demonstrating that the antiviral activity of viperin depends on its radical SAM domain, which contains conserved motifs to coordinate [4Fe-4S] cluster and cofactor SAM and is essential for its enzymatic activity, mutagenesis studies also revealed that viperin requires an aromatic amino acid residue at its C terminus for proper antiviral function. Furthermore, although the N-terminal 70 amino acid residues of viperin are not absolutely required, deletion of this region significantly compromises its antiviral activity against HCV. Our findings suggest that viperin represents a novel antiviral pathway that works together with other antiviral proteins, such as ISG20 and PKR, to mediate the IFN response against HCV infection.
CCL3 and Viral Chemokine-Binding Protein gG Modulate Pulmonary Inflammation and Virus Replication during Equine Herpesvirus 1 Infection
Authors: Van de Walle Gerlinde R. , Sakamoto Kaori , Osterrieder Nikolaus
Published: December 2007

CCL3 is a proinflammatory chemokine that mediates many of the cellular changes occurring in pulmonary disease. Here, CCL3−/−mice were used to investigate the role of this chemokine during respiratory herpesvirus infection. Compared to wild-type mice, CCL3−/−mice infected with the alphaherpesvirus equine herpesvirus 1 (EHV-1) displayed reduced body weight loss but had higher pulmonary viral loads. Lungs from infected CCL3−/−mice suffered a milder interstitial pneumonia, and fewer immune cells were recovered from the pulmonary airways after infection. We could also demonstrate that herpesvirus-encoded chemokine-binding glycoprotein G (gG) was capable of inhibiting the chemotactic functions of CCL3. This CCL3-mediated chemotaxis, however, was restored in the presence of gG-specific antibodies, which puts into question the advertised use of gG deletion mutants as marker vaccines. In summary, we concluded that CCL3 is a major player in controlling herpesvirus replication in the target organ, the lung, and does so by evoking a strong inflammatory response. The immunomodulatory activity of CCL3 is balanced by the expression of viral gG, whose chemokine-binding activity is mitigated in secondary infections by the production of anti-gG antibodies.
Autorepression of Epstein-Barr Virus Nuclear Antigen 1 Expression by Inhibition of Pre-mRNA Processing
Authors: Yoshioka Mikio , Crum Michelle M. , Sample Jeffery T.
Published: December 2007

Epstein-Barr virus (EBV) latent infection, and its associated oncogenic potential, is dependent on genome maintenance functions of EBV nuclear antigen 1 (EBNA-1), one of six EBNAs expressed from a common promoter (Wp and then Cp) upon infection of naive B cells. Subsequent host-mediated silencing, however, necessitates the expression of EBNA-1 from the EBNA-1-specific promoter Qp to ensure against genome loss during cell division, including EBV-associated malignancy. Here we addressed the mechanism by which EBNA-1 represses Qp through binding downstream of the transcription start site and the role of this autoregulatory function in EBV latency. Our results revealed that EBNA-1 does not inhibit transcription from Qp, as previously predicted, but acts post- or cotranscriptionally to block the processing of primary transcripts. This does not, however, require the RGG motifs responsible for strong but nonspecific RNA binding by EBNA-1. Within isogenic B-cell lines using either Cp/Wp or Qp, EBNA-1 occupancy of Qp is equivalent, suggesting that autoregulation occurs, albeit to different degrees, during full and restricted EBV latency programs. Finally, in cell lines using Cp or Wp for EBNA expression, unprocessed transcripts from Qp are detectable in the absence of corresponding mRNAs, providing further evidence that this novel mechanism of EBNA-1 action functions during latency. This posttranscriptional mechanism of regulation would provide an efficient means to monitor and regulate EBNA-1 expression from Qp, ensuring levels adequate for genome maintenance but, perhaps more importantly, below an immunogenic threshold above which latently infected cells may be at risk for elimination by EBNA-1-specific cytotoxic T cells.
Antigenic Profile of Avian H5N1 Viruses in Asia from 2002 to 2007
Authors: Wu Wai Lan , Chen Yixin , Wang Pui , Song Wenjun , Lau Siu-Ying , Rayner Jane M. , Smith Gavin J. D. , Webster Robert G. , Peiris J. S. Malik , Lin Tianwei , Xia Ningshao , Guan Yi , Chen Honglin
Published: December 2007

Antigenic profiles of post-2002 H5N1 viruses representing major genetic clades and various geographic sources were investigated using a panel of 17 monoclonal antibodies raised from five H5N1 strains. Four antigenic groups from seven clades of H5N1 virus were distinguished and characterized based on their cross-reactivity to the monoclonal antibodies in hemagglutination inhibition and cell-based neutralization assays. Genetic polymorphisms associated with the variation of antigenicity of H5N1 strains were identified and further verified in antigenic analysis with recombinant H5N1 viruses carrying specific mutations in the hemagglutinin protein. Modification of some of these genetic variations produced marked improvement to the immunogenicity and cross-reactivity of H5N1 strains in assays utilizing monoclonal antibodies and ferret antisera raised against clade 1 and 2 H5N1 viruses, suggesting that these sites represent antigenically significant amino acids. These results provide a comprehensive antigenic profile for H5N1 virus strains circulating in recent years and will facilitate the recognition of emerging antigenic variants of H5N1 virus and aid in the selection of vaccine strains.
SIAH-1 Interacts with the Kaposi's Sarcoma-Associated Herpesvirus-Encoded ORF45 Protein and Promotes Its Ubiquitylation and Proteasomal Degradation
Authors: Abada Rinat , Dreyfuss-Grossman Tsofia , Herman-Bachinsky Yifat , Geva Haim , Masa Shiri-Rivka , Sarid Ronit
Published: December 2007

Kaposi's sarcoma-associated herpesvirus (KSHV), also referred to as human herpesvirus 8, is a potentially tumorigenic virus implicated in the etiology of Kaposi's sarcoma, primary effusion lymphoma, and some forms of multicentric Castleman's disease. The open reading frame 45 (ORF45) protein, encoded by the KSHV genome, is capable of inhibiting virus-dependent interferon induction and appears to be essential for both early and late stages of infection. In the present study, we show, both in yeast two-hybrid assays and in mammalian cells, that the ORF45 protein interacts with the cellular ubiquitin E3 ligase family designated seven in absentia homologue (SIAH). We provide evidence that SIAH-1 promotes the degradation of KSHV ORF45 through a RING domain-dependent mechanism and via the ubiquitin-proteasome system. Furthermore, our data indicate the involvement of SIAH-1 in the regulation of the expression of ORF45 in KSHV-infected cells. Since the availability of KSHV ORF45 is expected to influence the course of KSHV infection, our findings identify a novel biological role for SIAH proteins as modulators of virus infection.
Expression of Murine Leukemia Virus Envelope Protein Is Sufficient for the Induction of Apoptosis
Authors: Zhao Xiaoqing , Yoshimura Fayth K.
Published: December 2007

The generation of cytopathic effects by murine leukemia viruses (MLVs) in different cell types correlates with the ability of the virus to induce thymic lymphoma. We showed that the induction of apoptosis in mink epithelial cells by mink cell focus-forming (MCF) MLV infection results in the accumulation of high levels of both unintegrated viral DNA and the envelope precursor polyprotein (gPr80

env

). Comparisons of envelope protein expression levels of plasmid clones of the
env
gene of the MCF13 and noncytopathic NZB-9 MLV strains demonstrated that the accumulation of MCF13 gPr80

env

results in endoplasmic reticulum stress and is sufficient for the induction of apoptosis.
Genomic aberrations and immunohistochemical markers as prognostic indicators in multiple myeloma
Authors: Yeung J , Chang H
Published: December 2007

As patients with multiple myeloma (MM) have a variable clinical course, predictive markers would help determine the appropriate treatment strategy. Clinical staging is commonly used to predict outcome, but tumour marker expression and the underlying genetic changes are increasingly used to assess the biological aggressiveness of the disease. Recent studies have demonstrated the utility of immunohistochemistry in detecting prognostic markers, including fibroblast growth factor receptor 3, cyclin D1, c-maf and p53, which have been associated with various genetic aberrations, including t(4;14), t(11;14), t(14;16) and del(17p). While t(4;14), t(14;16) and del (17p) have been documented to confer a poor prognosis, t(11;14) appears to be a neutral or even favourable factor in some studies. CD56, CD33, CD20 and CXCR4 are promising surface markers due to their roles in MM progression, but further studies of larger cohorts are necessary to assess their prognostic relevance. In this review, the biological function and clinical relevance of the main prognostic markers in MM is discussed, and also the role of immunohistochemistry in the stratification of patients into appropriate risk categories.
Factors affecting seed set in Douglas-fir (Pseudotsuga menziesii)
Authors: Owens John N. , Colangeli Anna M. , Morris Sheila J.
Published: December 2007

Cone and seed development in Douglas-fir were studied from pollination until seed release in 1986. Cone abortion at, and shortly after, pollination was high, resulting from a combination of low temperatures and possibly high moisture and populations of microorganisms on cones. Seed potential averaged about 75 seeds per cone with 31 filled seed per cone, giving an average seed efficiency of 39%. The major loss of seed resulted from insufficient pollen in the ovules. Other causes were ovule and embryo abortion at various stages of development. The effects of prezygotic and postzygotic events on seed set are discussed with respect to the reproductive success of Douglas-fir. Key words: Douglas-fir, seed set, cone, ovule, development, abortion.
Nuclear DNA content and isozyme variation in relation to morphogenic potential of strawberry (Fragaria × ananassa) callus cultures
Authors: Nehra Narender S. , Kartha Kutty K. , Stushnoff Cecil
Published: December 2007

Callus cultures of strawberry cv. Redcoat (2n = 8x = 56) initiated from greenhouse and in vitro leaf explants were examined at various culture periods for morphogenic response, changes in nuclear DNA content, and isozyme banding patterns of four enzymes. The flow cytometric analysis of nuclear DNA content revealed the occurrence of polyploid and aneuploid changes as a function of ageing of callus cultures. The calli initiated from in vitro leaf explants were more prone to such changes than those initiated from greenhouse leaf explants. The in vitro morphogenic ability of callus cultures was affected by the ploidy changes, but the latter were not the only cause for loss in regeneration potential of long-term callus cultures. The isozyme phenotypes of esterase, phosphoglucomutase, phosphoglucoisomerase, and leucine aminopeptidase did not change with the chromosomal variation in callus cultures. Key words: strawberry, Fragaria × ananassa, callus culture, flow cytometry, nuclear DNA content, isozyme.
Roegneria: its generic limits and justification for its recognition
Authors: Baum Bernard R. , Yen Chi , Yang Jun-Liang
Published: December 2007

We document diagnostic characteristics of Roegneria by which it differs from genera with which it has often been confused. Characteristics of Roegneria are the absence of underground runners; slightly curved and elongated rachis with long internodes, each rachis node bearing one spikelet only and often adhering to the internode, and inflorescence appearing more or less one sided because of the disposition of the spikelets; spikelet functionally disarticulating below the glumes; glume symmetric with nerves tapering in the apex; lemma with nerves tapering in the apex; and palea generally shorter than the lemma, and if equal to the lemma then the tip obtuse, truncate, or retuse. Genera difficult to separate from Roegneria are Agropyron, Elymus, and Elytrigia; these share one or more characteristics but none have them in the same combination. We also stress the merit of recognizing Roegneria for germ-plasm utilization. Key words: Roegneria, Triticeae, generic limits, Elymus, Agropyron, Elytrigia.
The role of endoplasmic reticulum during gametogenesis in the aquatic fungus Allomyces macrogynus
Authors: Sewall Tommy C. , Pommerville Jeffrey C.
Published: December 2007

The Chytridiomycete Allomyces macrogynus generates new membranes for cleavage furrow and nuclear-cap formation during gametogenesis and zoosporogenesis. Transmission electron microscopy after impregnation with a mixture of zinc iodide and osmium tetroxide clearly demonstrated changes in the endoplasmic reticulum. Endoplasmic reticulum was intensely stained but did not appear to contribute to the formation of the unstained flagellar membranes or cleavage furrows. However, the relative cytoplasmic volume of endoplasmic reticulum decreased as positively stained nuclear-cap membrane formed. These observations are consistent with the hypothesis that flagellar membranes and cleavage furrows are derived from trans-Golgi equivalents, whereas the nuclear-cap membrane is derived from the endoplasmic reticulum. Key words: Allomyces macrogynus, Chytridiomycetes, endoplasmic reticulum, gametogenesis, zoosporogenesis.
Leghemoglobin variability in the genus Phaseolus
Authors: Lülsdorf M. M. , Holl F. B.
Published: December 2007

Leghemoglobins are oxygen-binding proteins in the legume root nodule that generally show structural heterogeneity. Fifty accessions of the genus Phaseolus were screened for leghemoglobin electrophoretic variation. Heterogeneity was observed in two of the six Phaseolus species investigated; the single leghemoglobin components found in samples of Phaseolus vulgaris and Phaseolus acutifolius nodule extracts, as well as in other Phaseolus species, appear to be the exception among nitrogen-fixing plants that have been evaluated for leghemoglobin profiles. Interspecific hybrids were produced to transfer existing leghemoglobin variability into the P. vulgaris background. Leghemoglobins were also shown to be inherited codominantly in interspecific hybrids. The amino terminal amino acid sequence of leghemoglobin II of a P. vulgaris × Phaseolus filiformis hybrid and leghemoglobins I and II from Phaseolus lunatus nodules were determined. The 37 amino terminal amino acids of these components were identical to the published sequence for P. vulgaris. Key words: nitrogen fixation, interspecific hybrids, electrophoresis.
Effects of Hebeloma arenosa and phosphorus fertility on root acid phosphatase activity of red pine (Pinus resinosa) seedlings
Authors: MacFall Janet , Slack Steven A. , Iyer Jaya
Published: December 2007

The ectomycorrhizal fungus Hebeloma arenosa Burdsall, MacFall & Albers was assayed for surface-accessible acid phosphatase activity in vitro on roots of red pine (Pinus resinosa Ait.) seedlings. Hebeloma arenosa was grown in defined liquid media containing 0, 17, 34, 68, or 136 mg/L phosphorus for 4 weeks. When assayed for acid phosphatase activity with p-nitrophenyl phosphate, 7.3 μmol of orthophosphate were released per gram dry weight of fungal tissue. There was no effect of added P on enzyme activity, excluding the treatment with no added P in which there was negligible fungal growth. Red pine seedlings were grown in Sparta loamy fine sand amended with 0, 17, 34, 68, or 136 mg/kg P as superphosphate, with and without H. arenosa inoculum. Mycorrhizal roots had greater enzyme activity than nonmycorrhizal roots of seedlings grown in similarly P-amended soil. This was determined by the following three assays: orthophosphate release from two salts of myoinosital hexaphosphate (Na and KMg) and from p-nitrophenyl phosphate. It is suggested that greater acid phosphatase activity by roots mycorrhizal with H. arenosa is one mechanism for improved P nutrition through the formation of a pool of P released from sources unavailable for direct intake.
Spatial and temporal patterns of postdispersal seed predation
Authors: Whelan Christopher J. , Willson Mary F. , Tuma Charles A. , Souza-Pinto Isabel
Published: December 2007

We experimentally examined spatial and temporal patterns of postdispersal seed predation of vertebrate-dispersed plant species in temperate woodland and old-field habitats. Rodents were the principal predators. Rates of seed loss varied with microhabitat (near logs, tree trunks, and open forest floor), macrohabitat (old field, forest), plant species, year, and time of dispersal within a year. Levels of final mortality (= mortality at final census) did not vary with microhabitat or time of dispersal but did vary between macrohabitats, plant species, and years. The variability of our results (i) indicates the importance of dispersing many seeds into many different types of micro- and macro-habitats, (ii) supports the view of a diffuse mutualism between plants and their vertebrate dispersers, and (iii) suggests that to detect important trends in patterns of postdispersal seed predation, and ultimately plant recruitment, longer term studies are imperative. Key words: community structure, seed predation, rodents, plant populations, plant recruitment, vertebrate seed dispersal.
Discrete proteins associated with overwintering of interior spruce and Douglas-fir seedlings
Authors: Roberts Dane R. , Toivonen Peter , McInnis Stephanie M.
Published: December 2007

Seasonal protein changes were followed in seedlings of interior spruce (a mixture of Picea glauca and P. englemannii) and Douglas-fir (Pseudostuga menziesii) by sodium dodecylsulfate – polyacrylimide gel electrophoresis. A 30-kDa protein in seedlings of Douglas-fir and a 30- and 27-kDa protein in interior spruce that were not detected in the late summer accumulated in seedling tissues during the fall. These proteins remained present throughout the winter but declined rapidly in seedlings during the initial flush of spring growth. There was an increase in the total protein content of interior spruce seedling tissues during the fall; however, the accumulation of the 30- and 27-kDa protein was tissue specific, since it increased in the apical bud, shoot, and root tissue but not in the leaves. By late fall these proteins represented approximately 15% of the total seedling protein. Measurements of variable chlorophyll fluorescence indicated that the accumulation of these overwintering proteins was associated with the seasonal decline in photosynthetic capacity. These results suggest that conifer seedlings may utilize these proteins as a storage reserve during overwintering. Key words: conifers, electrophoresis, overwintering, proteins, seasonal, seedlings.
Size-dependent reproductive output in agricultural weeds
Authors: Thompson B. K. , Weiner J. , Warwick S. I.
Published: December 2007

Data on reproductive and vegetative weights of individuals from five species of agricultural weeds (Apera spica-venti L., Datura stramonium L., Abutilon theophrasti Medic., Sorghum halepense (L.) Pers., and Panicum miliaceum L.) were used to test Weiner's (1988) model of linear size-dependent reproductive output in plants. In general, the populations showed strong evidence (P < 0.001) of linear relationships between reproductive and vegetative weight. Linearity was most pronounced in cases where size differences were primarily due to competition. Generally, the linear relationships were consistent from population to population within a species. Many of the populations also showed positive x-intercepts, indicating a threshold size for reproduction. However, there were a number of populations with no apparent relationship between reproductive and vegetative weight, with departures from linearity, or with positive y-intercepts (negative x-intercepts). Key words: reproductive weight, vegetative weight, agricultural weeds, size-dependent reproduction.
Stomatal ontogeny and morphology in Phaseolus vulgaris in relation to infection structure initiation by Uromyces appendiculatus
Authors: Terhune B. T. , Allen E. A. , Hoch H. C. , Wergin W. P. , Erbe E. F.
Published: December 2007

The development and morphology of the stomatal complex in Phaseolus vulgaris was examined by light microscopy, scanning electron microscopy, and transmission electron microscopy (TEM). The outer aperture formed between the stomatal guard cells was bordered by cuticular ledges, 1.2–5.3 μm wide. These were composed of a matrix of electron-dense fibrils supporting an autofluorescent amorphous outer layer, homologous to the cuticle. This layer of cuticle lined the ventral walls of the guard cells and extended into the substomatal chamber. During stomatal development, as the guard cells separated, the outer cuticular layer covering the incipient aperture stretched and split, forming stomatal lips. These lips, 0.2–1.4 μm wide, were oriented horizontally, upright, and folded back from the ledge in TEM thin sections. In cryopreserved stomata, the lips were generally oriented upright regardless of whether the outer aperture was open or closed. Previous studies have implicated that stomatal lips may function to signal appressorium formation in urediniospore germlings of Uromyces appendiculatus. This study indicated that dimensions of the lips were within the parameters required to induce appressorium formation on artificial membranes. Other components of the stomatal architecture may also be involved in the induction of appressorium formation. Key words: Uromyces appendiculatus, Phaseolus vulgaris, stomata, cuticle, appressoria.
A morphometric and taxonomic reevaluation of Haenianthus (Oleaceae)
Authors: Zona Scott
Published: December 2007

Leaf size and shape, long used to differentiate taxa in Haenianthus, were found to be less useful than previously believed. Nevertheless, two species can be recognized on the basis of leaf shape, H. incrassatus and H. salicifolius. The former species has long petioles, attenuate leaf bases, and thin laminas and is endemic to cloud forests of Jamaica. The latter species, with short petioles, acute to acuminate leaf bases, and thick laminas, has two varieties, H. salicifolius var. salicifolius of Cuba and Haiti, and H. salicifolius var. obovatus of Cuba, Hispaniola, and Puerto Rico. Key words: Caribbean, Haenianthus, morphometric analysis, Oleaceae.
A new genus of the Hyphomycetes endoparasitic in bdelloid rotifers with conidia that lodge in the mastax
Authors: Barron G. L.
Published: December 2007

Haptospora is described as a new genus of the Hyphomycetes endoparasitic in rotifers. The genus is distinguished by conidia that have a doughnut-shaped modification at the base. This structure appears to have a function in lodging the conidium in the mastax of the host. The conidiogenous cells are phialides, each with a membranous collarette. Two species of Hyphomycetes, described previously as Phialophora endoparasitica and P. tribrachispora, are transferred to Haptospora, and a third species, Haptospora appendiculata, is described as new. Key words: Phialophora, Haptospora, endoparasite, rotifer.
Phenology of tree seedlings in relation to seed size
Authors: Seiwa Kenji , Kikuzawa Kihachiro
Published: December 2007

Vertical growth patterns and leaf dynamics of seedlings of 31 deciduous broad-leaved tree species with different seed sizes were examined under either open or shaded conditions. Seed size positively affected initial seedling height and leaf longevity, and negatively affected duration of leaf emergence and leaf-turnover rate. Large-seeded species completed shoot elongation and almost all of their annual leaf production in a short period, irrespective of shading. Small-seeded species attained maximum heights similar to those of large-seeded species under open conditions by having a longer duration of leaf emergence, higher resource allocation to leaf production, and rapid leaf turnover. However, leaf-production and leaf-turnover rates were reduced by shading for small-seeded species, a trait that resulted in lower final seedling heights for small- versus large-seeded species. In small-seeded species, maximum seedling growth was attained only under open conditions through changes in the phenology of leaf dynamics. In contrast, growth of large-seeded species was independent of the effect of light limitation. The importance of seed size in determining seedling establishment success depends on the relationships between seasonal change of environmental light conditions and characteristics of seedling phenology, which are related to seed size. Key words: seed size, tree seedlings, leaf dynamics, phenology, establishment strategies.
Spatial genetic substructure within natural populations of jack pine (Pinus banksiana)
Authors: Xie Chang Yi , Knowles Peggy
Published: December 2007

Spatial autocorrelation analysis was used to investigate the geographic distribution of allozyme genotypes within three natural populations of jack pine (Pinus banksiana Lamb.). Results indicate that genetic substructuring within these populations is very weak and the extent differs among populations. These results are in good agreement with those inferred from mating-system studies. Factors such as the species' predominantly outbreeding system, high mortality of selfs and inbreds prior to reproduction, long-distance pollen dispersal, and the absence of strong microhabitat selection may be responsible for the observed weak genetic substructuring. Key words: jack pine, Pinus banksiana, genetic substructure, allozyme, spatial autocorrelation analysis.
Massarina walkeri n.sp., the teleomorph of Acrocalymma medicaginis from Medicago sativa contrasted with Leptosphaeria pratensis, L. weimeri n.sp., and L. viridella
Authors: Shoemaker R. A. , Babcock C. E. , Irwin J. A. G.
Published: December 2007

The teleomorph of Acrocalymma medicaginis Alcorn & Irwin was formed in pure culture. It is described as a new species, Massarina walkeri. It is contrasted with three somewhat similar species that parasitize legumes: Leptosphaeria pratensis Saccardo & Briard in Briard, Leptosphaeria weimeri n.sp. (anamorph Stagonospora meliloti (Lasch) Petrak), and L. viridella (Peck) Saccardo.
The diatom genus Cocconeis from an intertidal mud flat of North Brittany: source and diversity
Authors: Riaux-Gobin Catherine
Published: December 2007

A 1 -year survey of an epipelic diatom assemblage from a North Brittany marine mud flat revealed the presence of 23 species of Cocconeis. About 10 of these species were common, and the remaining ones were rare. These species of Cocconeis for the most part have small dimensions (nannophytobenthos). The species collected from the intertidal sediment, the specific richness, and seasonal occurrences are compared with those of an epiphytic assemblage on Zostera marina L. from the same region. Key words: benthic diatoms, Cocconeis, North Brittany, mud flat.
Genera coelomycetum XXVIII. Zelosatchmopsis anam.-gen.nov.
Authors: Saikawa Masatoshi , Ruiz Rafael F. Castaneda , Kendrick Bryce , Raj T. R. Nag
Published: December 2007

A new anamorph-genus is proposed to accommodate Satchmopsis sacciformis Castañeda described from Cuba. Key words: Zelosatchmopsis, Zelosatchmopsis sacciformis, Satchmopsis, Satchmopsis sacciformis, Guazuma ulmifolia.
Root morphological characteristics of host species having distinct mycorrhizal dependency
Authors: Manjunath A. , Habte M.
Published: December 2007

Greenhouse and growth chamber investigations were undertaken using selected Leucaena and Sesbania species to determine the extent to which root morphological characteristics and rhizosphere acid production could explain differences in mycorrhizal dependency of host plants. Compared with the moderately to very highly mycorrhizal-dependent Leucaena species, the marginally to moderately dependent Sesbania species were characterized by higher root mass, higher root density, higher root surface area, higher root length, smaller root diameter, higher percentage of root hair incidence, higher shoot to root ratio, and higher total P uptake. The two groups of species were not consistently different from each other with respect to mycorrhizal colonization level, root hair diameter, root hair length, P uptake per unit root surface area, and acid production in agar media. A stepwise regression model in which mycorrhizal dependency (MD) was used as the dependent variable and root characteristics as independent variables suggested that root mass, root hair length, root diameter, root density, and root hair incidence were important determinants of MD, with root mass accounting for 65.5% of the variability. The results suggest that differences in the mycorrhizal dependency of host species can be largely predicted from root characteristics data. Key words: Brassica, Leucaena, Sesbania, P uptake, root hair, root mass.
Inoculation of Euphorbia lathyris with cotton strings infested with Macrophomina phaseolina, causal agent of charcoal rot disease
Authors: Himmel Phyllis T.
Published: December 2007

Root infections caused by Macrophomina phaseolina were initiated under optimal conditions for the host, Euphorbia lathyris. Two-week-old Euphorbia lathyris seedlings were inoculated by tying roots with cotton strings infested with Macrophomina phaseolina. Ninety-three per cent of the inoculated roots developed infections after 2 weeks incubation in silica sand at 25 °C. By using infested strings, differences in the incidence of lesion development were detected when infected roots were subjected to differing temperature regimes. After approximately 6 weeks, there was a significantly [Formula: see text] greater incidence of lesion development at 34 °C than at 25 °C, whereas there was no difference in the incidence of infection. Aerial symptoms indicative of charcoal rot were not observed during the course of these studies. Key words: infested strings, charcoal rot.
The influence of aluminum on growth, carbohydrate, and organic acid content of an aluminum-tolerant and an aluminun-sensitive cultivar of wheat
Authors: Scott R. , Hoddinott J. , Taylor G. J. , Briggs K.
Published: December 2007

An aluminum-sensitive cultivar (Katepwa) and an aluminum-tolerant experimental line (PT741) of Triticum aestivum were grown in nutrient solutions containing 0–400 μM aluminum at pH 4.5. After 18 days of growth, plant fresh weight was reduced in the Al-sensitive and Al-tolerant germ plasm by as little as 100 and 200 μM Al, respectively, and a number of changes in carbon allocation were observed. Shoot to root ratios increased with Al concentration in the Al-sensitive 'Katepwa' and remained constant in the Al-tolerant PT741.In both 'Katepwa' and PT741, shoot carbon was increasingly deposited into starch and fructan pools with increasing Al concentration. However, fructan deposition was more marked in the Al-sensitive 'Katepwa', possibly reflecting a failure to export carbon to the roots. Differences between Al-tolerant and Al-sensitive germ plasm were also observed in some organic acid levels. Contrary to several previous reports, higher concentrations of organic acids were found in the roots of Al-sensitive 'Katepwa'. In shoots, higher concentrations of organic acid were found in the Al-tolerant PT741. These results suggest that allocation of carbon to specific pools is affected by the concentration of Al. However, synthesis of organic acids and subsequent chelation of intracellular Al does not appear to represent a tolerance strategy in wheat. Observed changes in metabolic levels more likely represent a broad array of toxic lesions, with the magnitude of changes being greater in the Al-sensitive 'Katepwa' than in the Al-tolerant PT741. Key words: stress, aluminum tolerance, aluminum sensitivity, fructans.
Distribution spatiale de la régénération après feu de l'épinette noire (Picea mariana) et du pin gris (Pinus banksiana) dans la forêt boréale, Réserve faunique Ashuapmushuan, Québec
Authors: St-Pierre Hélène , Gagnon Réjean , Bellefleur Pierre
Published: December 2007

Post-fire spatial distribution of black spruce (Picea mariana (Mill.) BSP) and jack pine (Pinus banksiana Lamb.) regenerations were studied in the Réserve faunique Ashuapmushuan, Quebec. The main factors analysed were (i) effects of organic matter thickness on growth and regneration, (ii) spatial distribution type of the regeneration, (iii) effects of burned stems on this distribution, and (iv) links between spatial distribution of the regeneration and the thickness of the post-fire residual organic matter. A strong correlation was observed between the presence of seedlings and the thickness of the post-fire residual organic matter. However, jack pine was much more efficient in getting established on microsites with thicker organic matter. Spatial distribution of the regeneration has a tendency to spread, following Blackman's dispersion coefficient, while adult individuals of the original population follow a more random pattern; this suggests that some seedling mortality, induced by seedling density, is to be expected. Regeneration shows a spatial link (point correlation coefficient) with trees of the original population, thus showing up the post-fire perpetuation of the individuals on the same microsites. Finally, the residual organic matter thickness on the ground seems without significant influence on the overall growth of jack pine and black spruce seedlings. Key words: Picea mariana, Pinus banksiana, spatial distribution, fire, regeneration. [Journal translation]
Studies in the lichen genus Ochrolechia. 2. Corticolous species of North America
Authors: Brodo Irwin M.
Published: December 2007

Ochrolechia, a widespread genus of crustose lichens, includes 19 species growing on bark in North America. These corticolous species and several non-North American taxa are treated in this paper. Six species and one variety are described as new: O. antillarum, O. gowardii, O. montana, O. juvenalis, O. pseudopallescens, O. subisidiata, and O. trochophora var. pruinirosella. Two species are reduced to synonymy (O. californica Vers, and O. sorediosa Howard); six species are excluded from the North American flora (O. alboflavescens (Wulf.) Zahlbr., O. apiculata Vers., O. pallescens (L.) Massal., O. parella (L.) Massal., O. rhamni-purshianae Senft, O. subviridis (Höeg) Erichsen, and O. turneri (Sm.) Hasselrot). Several synonymies mentioned in the literature are confirmed (O. trochophora (Vainio) Oshio including O. rosella (Tuck.) Vers. and O. orientalis Vainio; O. androgyna (Hoffm.) Arn. including O. pergranulosa (Räs.) Vers, and O. mahluensis Räs.; and O. yasudae Vainio including O. tuckermanii Vers, and O. pennsylvanica Vers.). A key for the determination of all the species treated is presented together with distribution maps and a summary of the chemistry of the group. 5-O-Methylhiascic and 4,5-di-O-methylhiascic acids are reported from Ochrolechia for the first time. Key words: Ochrolechia, Ascomycotina, Pertusariaceae.
Ectomycorrhizas and nutrient transfer in conifer – feather moss ecosystems
Authors: Carleton T. J. , Read D. J.
Published: December 2007

Conifer–feather moss ecosystems dominate large areas of the boreal forest regions of the world, but the interrelations between these two components of the system are poorly understood. Mycorrhizal roots of the trees grow in close association with the mosses. The possibility that nutrients can be transferred from moss shoots to trees through mycorrhizal fungi was investigated using the feather moss Pleurozium schreberi and mycorrhizal seedlings of Pinus contorta. Shoots of the moss were divided into three categories, viz. green, senescent, and dead, and nutrient contents of aqueous leachates from the segments were measured before and after drying. Significant quantities of nitrogen and phosphorus were released from moss shoots especially after drying. Senescing segments consistently released more N than those that were dead and generally released more than did the green segments. All categories of segments released some protein nitrogen, and drying induced leakage of glucose, fructose, and sucrose. Leachates of entire moss shoots were capable of supporting growth of three mycorrhizal fungi in pure culture. Moss shoots added to chambers containing mycorrhizal plants were colonized by the fungal associates of the plants, particularly intensive growth occurring in the senescent region of the moss shoots. Phosphate (32P) and carbon (14C), previously fed to the moss shoots, was absorbed by mycorrhizal mycelia and transferred over distances of centimetres to infected roots of pine plants and then to their shoots. The significance of these uptake and transfer processes for nutrient cycling in boreal forest ecosystems is discussed. Key words: leachate, nitrogen, phosphorus, sugars, protein, radioisotope.
Postglacial migration history of lodgepole pine near Yakutat, Alaska
Authors: Peteet Dorothy M.
Published: December 2007

Pollen stratigraphy from three peat sections near Yakutat, Alaska, suggests that lodgepole pine only recently arrived in southeastern Alaska. In contrast with this palynological interpretation, however, are lodgepole pine (Pinus contorta) macrofossils that are present throughout one entire peat core. 14C dating by accelerator mass spectrometry confirms the establishment of lodgepole pine in this region of Alaska about 10 000 BP. The surprising disparity between the pollen and macrofossil results has important implications for paleomigration research. These results imply that the use of assigned pollen percentages to indicate the presence of a species within a region may not be valid, particularly where a species is at the edge of its geographic range. Comparison of the timing of the first appearance of lodgepole pine pollen from a dozen sections along the north Pacific coast suggests either a late Wisconsin refugium for this pine in southeastern Alaska or extremely rapid late-glacial coastal migration northwestward following ice retreat. Key words: Alaska, pollen, macrofossils, lodgepole pine, phytogeography.
Ascochyta cypericola sp.nov. causing leaf blight of purple nutsedge (Cyperus rotundus)
Authors: Upadhyay Rajeev K. , Kenfield Doug , Strobel Gary A. , Hess Wilford M.
Published: December 2007

Ascochyta cypericola sp.nov., causing leaf blight of purple nutsedge in India, is described and illustrated. Key words: mycoherbicide, purple nutsedge, fungal pathogen.
Flower development in Amelanchier alnifolia (Maloideae)
Authors: Steeves Taylor A. , Steeves Margaret W. , Olson A. Randall
Published: December 2007

The development of the flower of Amelanchier alnifolia from initiation to the onset of anthesis is described. Sepals are formed sequentially, but interprimordial zonal growth results in the initiation of the hypanthium. Petals and stamens arise in whorls around the floral meristem as the hypanthium extends. They show neither coalescence nor adnation and do not appear to contribute to the development of the hypanthium. Gynoecial primordia arise individually, give rise to the styles and stigmas, and are joined basally by zonal growth to produce the roof of the ovary. The wall of the inferior ovary is interpreted as a gynoecial hypanthium. It is difficult to determine the extent to which the gynoecial primordia contribute to the development of the ovary. They do not give rise to most of its structure but may be responsible for the initiation of the ovules. There is evidence of postgenital fusion of the septal margins as they converge in the centre of the ovary. The timing of events in floral development is recorded for the locality of the study. The observations are discussed in relation to current theories concerning the nature of the inferior ovary. Key words: Amelanchier, flower, development, inferior ovary, hypanthium.
La morphogenèse florale chez le pétunia. III. Déviations dans le programme organogène chez un mutant femelle stérile
Authors: Turlier Marie-France , Alabouvette Josiane , Doulain-Douvier Diane
Published: December 2007

A monogenic mutant of Petunia hybrida R-n57 exhibits flowers with abnormal gynoecium: various malformations, such as the opening of the style and the nonprotection of ovules, or the masculinization with development of pollen sacs, anthers, and male gametophyte growing with or within ovules. The same type of abnormalities happens over and over along one inflorescential axis so that an ontogenic analysis can be conducted. Some assumptions are supported by the histocytological study: a few punctual modifications of the normal organogenesis program, recently established, and one new stage ending at the masculine or abnormal gynoecium, with homeotic members, are involved. Relations between the deflected development and female sterility are argued. Key words: flower, teratology, morphogenesis, mutant, Petunia.
Pollen evidence for Late Cretaceous differentiation of Proteaceae in southern polar forests
Authors: Dettmann Mary E. , Jarzen David M.
Published: December 2007

Amongst diverse and abundant fossil proteaceous pollen in southeastern Australian Late Cretaceous (Campanian–Maastrichtian) sediments are forms identical with pollen of extant taxa within subfamilies Proteoideae, Persoonioideae, Carnarvonioideae, and Grevilleoideae. Taxa identified now have disparate geographic ranges within Australasia. Sclerophyllous Adenanthos and Stirlingia (Proteoideae) are restricted to the southern Australian Mediterranean climatic region; Persoonia (Persoonioideae) ranges into higher rainfall areas of eastern and northern Australia. Grevillea exul – Grevillea robusta and Telopea (Grevilleoideae) and Carnarvonia (Carnarvonioideae) occur in or fringe rain forests in eastern Australasia, as do other members (Macadamia, Gevuina–Hicksbeachia, Knightia, and Beauprea) reported previously. Pollen evidence thereby confirms evolution of both rain forest and sclerophyll members by the Campanian–Maastrichtian. Turnover of proteaceous pollen taxa near the Cretaceous–Tertiary boundary may reflect contemporaneous modifications to the proteaceous communities. Associated with the Late Cretaceous Proteaceae were diverse conifers (Microcachrys, Lagarostrobus, Podocarpus, Dacrydium, Dacrycarpus, and Araucariaceae), Nothofagus, Ilex, Gunnera, Ascarina, Winteraceae, Trimeniaceae, and probable Epacridaceae. The vegetation, which fringed a narrow estuary separating Antarctica from southern Australia, implies a mosaic of rain forest and sclerophyll communities but has no modern analogue. Key words: Proteaceae, Late Cretaceous, Australia, Antarctica.
Evidence for the role of carboxysomes in the cyanobacterial CO2-concentrating mechanism
Authors: Price G. Dean , Badger Murray R.
Published: December 2007

In this paper we provide a brief summary of recent work that supports the notion that the carboxysome, a polyhedral body containing Rubisco, plays a pivotal role in the cyanobacterial CO2-concentrating mechanism. This work includes (i) experiments in which active human carbonic anhydrase II was expressed in the cytosol of the cyanobacterium Synechococcus PCC7942 resulting in a high CO2-requiring phenotype, and (iii) characterization of two types of high CO2 requiring mutants of Synechococcus that appear to be incapable of generating CO2 within the carboxysomes. Carboxysomes appear to serve as a microcompartment where CO2 can be generated and elevated at the site of carboxylation. We also report on the identification by complementation and sequence analysis of a 300 base pair open reading frame that is located upstream of rbcL and that is involved in the correct functioning of the carboxysome. Preliminary electron microscopy data is also considered on the biogenesis of carboxysomes in Anabaena variabilis M3. Key words: carboxysome, cyanobacteria, carbonic anhydrase, CO2-concentrating mechanism, genetic analysis, mutants.
Selection and analysis of mutants of the CO2-concentrating mechanism in cyanobacteria
Authors: Badger Murray R. , Price G. Dean , Yu Jian Wei
Published: December 2007

The selection and analysis of mutants of the CO2-concentrating mechanism in cyanobacteria have greatly advanced our understanding of the physiological and genetic components of this mechanism. This paper reviews the processes for the creation of mutants and the properties of mutants that have been produced so far. In addition to this, consideration is given to developing new mutant selection protocols, based on our current knowledge of the operation of the CO2-concentrating mechanism. As a result, new screens are suggested for the isolation of transport mutants that are defective in either HCO3− or CO2 transport activity, and putative carboxysomal mutants that have altered carbonic anhydrase activities. The procedures for physiological analysis of mutants are also reviewed, with a conclusion that there is a great need for the further development of in vitro assays, particularly for the inorganic carbon transport process and carboxysome function. Particular consideration is given to the in vitro carboxysome assay, and it is concluded that many of the properties of a carboxysomal Rubisco may be difficult to resolve owing to increases in carboxysomal leakiness during isolation and the higher ratio of [CO2] to [HCO3−] experienced during assays compared with the in vitro situation. Finally, consideration is given to the genetic analysis of cyanobacterial mutants and the progress that will need to be made in the future, discovering what are the functions of the proteins coded for by the genes that are isolated. Key words: cyanobacteria, mutants, photosynthesis, carboxysome, CO2-concentrating mechanism.
Active uptake of inorganic carbon by Chlamydomonas reinhardtii: evidence for simultaneous transport of HCO3− and CO2 and characterization of active CO2 transport
Authors: Sültemeyer Dieter F. , Fock Heinrich P. , Canvin David T.
Published: December 2007

Washed protoplasts of low CO2 grown cells of Chlamydomonas reinhardtii were used to further characterize the ability for active CO2 transport. The CO2 transport mechanism and the high affinity for dissolved inorganic carbon were completely induced within 4 h after transferring 5% CO2 grown cells to ambient air (0.035% CO2). Net O2 evolution and CO2 uptake were saturable processes showing saturation between 100 and 200 μM DIC (1.6–3.2 μM CO2) at pH 8.0. For both O2 evolution in whole cells and CO2 uptake in the protoplasts the concentration of dissolved inorganic carbon required for 50% of the maximal rates was about 12 μM (= 0.20 μM CO2). Studies with 3-(3,4-dichloro-phenyl)-1,1 dimethylurea, dibromo-thymoquinone, tetramethyl phenylenediamine and protoplasts of a cytochrome c oxidase deficient mutant of C. reinhardtii indicated the CO2 transport was driven by cyclic or pseudocyclic ATP formation and oxidative phosphorylation was not involved. These studies also show that CO2 transport and CO2 fixation are distinct mechanisms and that active CO2 uptake may occur in the absence of CO2 fixation. Key words: Chlamydomonas reinhardtii; CO2–HCO3− concentrating mechanism, CO2 transport, cyclic photophosphorylation, pseudocyclic photophosphorylation.