bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Sexually Transmitted Disease (STD) Coinfections on Performance of Three Commercially Available Immunosorbent Assays Used for Detection of Herpes Simplex Virus Type 2-Specific Antibody in Men Attending Baltimore, Maryland, STD Clinics
Authors: Summerton Jean , Riedesel Melissa , Laeyendecker Oliver , Gaydos Charlotte , Maldeis Nancy E. , Hardick Andrew , Morrow Rhoda Ashley , Quinn Thomas C.
Published: October 2007

Two hundred seventy-nine serum samples from men attending sexually transmitted disease (STD) clinics in Baltimore, Maryland, were tested for herpes simplex virus type 2 (HSV-2)-specific antibody by three immunosorbent glycoprotein G-2-based assays (the Kalon, Focus, and Biokit assays). The results for all samples with positive results were confirmed by Western blotting (91/279; 32.6% HSV-2 seroprevalence). All patients were also tested for
Chlamydia trachomatis
,
Neisseria gonorrhoeae
,
Trichomonas vaginalis
,
Mycoplasma genitalium
, human immunodeficiency virus type 1, and hepatitis C virus. The Kalon assay performed very well with samples from this population (90.8% sensitive, 99.4% specific), whereas the Focus assay had a sensitivity (82.6%) much lower than that shown previously. For 19.7% of the samples, the Biokit assay gave an indeterminate result. It was found that the odds of a sample having a Biokit assay indeterminate result compared to that of having a definitive positive or negative results were 3.88 times greater for subjects concurrently infected with
N. gonorrhoeae
, after the effects of other STDs were controlled for (
P =
0.001; 95% confidence interval, 1.78, 8.45). Unfortunately, we were unable to control for HSV-1 infection status in the regression model, which, on the basis of χ
2
analysis, might also affect the clarity of the Biokit test. The recommended index cutoff value of 1.1 for the Focus and Kalon assays was found to be optimal for this population.
Haemophilus ducreyi
Partially Activates Human Myeloid Dendritic Cells
Authors: Banks Keith E. , Humphreys Tricia L. , Li Wei , Katz Barry P. , Wilkes David S. , Spinola Stanley M.
Published: October 2007

Dendritic cells (DC) orchestrate innate and adaptive immune responses to bacteria. How
Haemophilus ducreyi
, which causes genital ulcers and regional lymphadenitis, interacts with DC is unknown.
H. ducreyi
evades uptake by polymorphonuclear leukocyte and macrophage-like cell lines by secreting LspA1 and LspA2. Many
H. ducreyi
strains express cytolethal distending toxin (CDT), and recombinant CDT causes apoptosis of DC in vitro. Here, we examined interactions between DC and
H. ducreyi
35000HP, which produces LspA1, LspA2, and CDT. In human volunteers infected with 35000HP, the ratio of myeloid DC to plasmacytoid DC was 2.8:1 in lesions, compared to a ratio of 1:1 in peripheral blood. Using myeloid DC derived from monocytes as surrogates for lesional DC, we found that DC infected with 35000HP remained as viable as uninfected DC for up to 48 h. Gentamicin protection and confocal microscopy assays demonstrated that DC ingested and killed 35000HP, but killing was incomplete at 48 h. The expression of LspA1 and LspA2 did not inhibit the uptake of
H. ducreyi
, despite inactivating Src kinases. Infection of DC with live 35000HP caused less cell surface marker activation than infection with heat-killed 35000HP and lipopolysaccharide (LPS) and inhibited maturation by LPS. However, infection of DC with live bacteria caused the secretion of significantly higher levels of interleukin-6 and tumor necrosis factor alpha than infection with heat-killed bacteria and LPS. The survival of
H. ducreyi
in DC may provide a mechanism by which the organism traffics to lymph nodes. Partial activation of DC may abrogate the establishment of a full Th1 response and an environment that promotes phagocytosis.
Human Apolipoprotein E Is Required for Infectivity and Production of Hepatitis C Virus in Cell Culture
Authors: Chang Kyung-Soo , Jiang Jieyun , Cai Zhaohui , Luo Guangxiang
Published: October 2007

Recent advances in reverse genetics of hepatitis C virus (HCV) made it possible to determine the properties and biochemical compositions of HCV virions. Sedimentation analysis and characterization of HCV RNA-containing particles produced in the cultured cells revealed that HCV virions cover a large range of heterogeneous densities in sucrose gradient. The fractions of low densities are infectious, while the higher-density fractions containing the majority of HCV virion RNA are not. HCV core protein and apolipoprotein B and apolipoprotein E (apoE) were detected in the infectious HCV virions. The level of apoE correlates very well with HCV infectivity. Both apoE- and HCV E2-specific monoclonal antibodies precipitated HCV, demonstrating that HCV virions contain apoE and E2 proteins. apoE-specific monoclonal antibodies efficiently neutralized HCV infectivity in a dose-dependent manner, resulting in a reduction of infectious HCV by nearly 4 orders of magnitude. The knockdown of apoE expression by specific small interfering RNAs (siRNAs) remarkably reduced the levels of intracellular as well as secreted HCV virions. The apoE siRNA suppressed HCV production by more than 100-fold at 50 nM. These findings demonstrate that apoE is required for HCV virion infectivity and production, suggesting that HCV virions are assembled as apoE-enriched lipoprotein particles. Our findings also identified apoE as a novel target for discovery and development of antiviral drugs and monoclonal antibodies to suppress HCV virion formation and infection.
NSm Protein of Rift Valley Fever Virus Suppresses Virus-Induced Apoptosis
Authors: Won Sungyong , Ikegami Tetsuro , Peters C. J. , Makino Shinji
Published: October 2007

Rift Valley fever virus (RVFV) is a member of the genus
Phlebovirus
within the family
Bunyaviridae
. It can cause severe epidemics among ruminants and fever, myalgia, a hemorrhagic syndrome, and/or encephalitis in humans. The RVFV M segment encodes the NSm and 78-kDa proteins and two major envelope proteins, Gn and Gc. The biological functions of the NSm and 78-kDa proteins are unknown; both proteins are dispensable for viral replication in cell cultures. To determine the biological functions of the NSm and 78-kDa proteins, we generated the mutant virus arMP-12-del21/384, carrying a large deletion in the pre-Gn region of the M segment. Neither NSm nor the 78-kDa protein was synthesized in arMP-12-del21/384-infected cells. Although arMP-12-del21/384 and its parental virus, arMP-12, showed similar growth kinetics and viral RNA and protein accumulation in infected cells, arMP-12-del21/384-infected cells induced extensive cell death and produced larger plaques than did arMP-12-infected cells. arMP-12-del21/384 replication triggered apoptosis, including the cleavage of caspase-3, the cleavage of its downstream substrate, poly(ADP-ribose) polymerase, and activation of the initiator caspases, caspase-8 and -9, earlier in infection than arMP-12. NSm expression in arMP-12-del21/384-infected cells suppressed the severity of caspase-3 activation. Further, NSm protein expression inhibited the staurosporine-induced activation of caspase-8 and -9, demonstrating that other viral proteins were dispensable for NSm's function in inhibiting apoptosis. RVFV NSm protein is the first identified
Phlebovirus
protein that has an antiapoptotic function.
TRAIL Is a Novel Antiviral Protein against Dengue Virus
Authors: Warke Rajas V. , Martin Katherine J. , Giaya Kris , Shaw Sunil K. , Rothman Alan L. , Bosch Irene
Published: October 2007

Dengue fever is an important tropical illness for which there is currently no virus-specific treatment. To shed light on mechanisms involved in the cellular response to dengue virus (DV), we assessed gene expression changes, using Affymetrix GeneChips (HG-U133A), of infected primary human cells and identified changes common to all cells. The common response genes included a set of 23 genes significantly induced upon DV infection of human umbilical vein endothelial cells (HUVECs), dendritic cells (DCs), monocytes, and B cells (analysis of variance,P< 0.05). Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), one of the common response genes, was identified as a key link between type I and type II interferon response genes. We found that DV induces TRAIL expression in immune cells and HUVECs at the mRNA and protein levels. The induction of TRAIL expression by DV was found to be dependent on an intact type I interferon signaling pathway. A significant increase in DV RNA accumulation was observed in anti-TRAIL antibody-treated monocytes, B cells, and HUVECs, and, conversely, a decrease in DV RNA was seen in recombinant TRAIL-treated monocytes. Furthermore, recombinant TRAIL inhibited DV titers in DV-infected DCs by an apoptosis-independent mechanism. These data suggest that TRAIL plays an important role in the antiviral response to DV infection and is a candidate for antiviral interventions against DV.
Cytological and histological changes induced by cold temperature in the young shoots of Marquillo × Kenya Farmer wheat dwarf 1
Authors: Mahon J. D. , Canvin D. T.
Published: October 2007

The growth of Marquillo × Kenya Farmer 1 heat plants has been shown to be irreversibly terminated if they are exposed to a 16° temperature when 10 days old and it has been proposed that this low temperature sensitivity proceeds through a rapid inactivation of the shoot apical meristem. Histological and microautoradiographic techniques were used to study the effects of 16° treatment on the morphology and meristematic activity of the young shoots of both Marquillo × Kenya Farmer 1 and normal Marquillo plants.Within 12 h of the beginning of 16° treatment, damaged cells were visible in the young developing leaf and stem tissues and such cells became numerous after longer periods at 16°. The cells most rapidly destroyed were those surrounding the vascular bundles in both leaf primordia and stem tissues and the extent of damage in a tissue was closely related to the stage of vascular differentiation in the adjacent bundles.Cell division in the apical meristem of the main shoot was inhibited even more rapidly. The proportion of cells dividing and the incorporation of 3H-thymidine into the nuclei of meristem cells decreased rapidly at 16° and the reversibility of these effects was similar to that of the whole plant effects.It is suggested that the cessation of growth in Mql × KF 1 exposed to 16° is due to the lack of cell division and that the permanence of this effect is due to the extensive cell destruction that occurs in the meristematic regions.
The effect of light and temperature on the sporulation of different isolates of Alternaria solani
Authors: Douglas Dexter R.
Published: October 2007

The sporulation of Alternaria solani was significantly affected by both fluorescent illumination and temperature. As temperature was reduced light became less of a factor. At 10C there was no significant difference between the effect of 16 h of light plus 8 h of darkness and of 8 h of light plus 16 h of darkness, on sporulation. At 25C, the greatest amount of sporulation occurred under continuous light. However, cultures of A. solani grown at 20C with 16 h of light plus 8 h of darkness produced the greatest number of spores. Isolates of A. solani obtained from Idaho and Maine responded to subjected treatments in a common manner.
Formes d'inclusions osmiophiles dans les cellules de Ceratocystis ulmi
Authors: Chamberland Hélène , Ouellette G. B.
Published: October 2007

Osmiophilic inclusions were frequently observed in cells of Ceratocystis ulmi (Buism.) C. Moreau in its hosts and in culture. These inclusions vary in shape, size, or their degree of compactness and are composed of fibrillar material and dense granules that are generally 150 Å in diameter. The inclusions are present in vacuolar areas which often appear to be completely or partially devoid of a membrane. Vacuolar areas may also contain aggregates of a similar texture, which often appear to have connections with nearby cytoplasm. Inclusions and (or) aggregates are often adjoining layers of membranes next to or extending within the vacuole. After thymidine labeling, radioautographic grains were observed over these bodies, thus suggesting the presence of DNA. The possible origin of these inclusions from transforming fungal cytoplasm and their importance in the infection process of Dutch elm disease are discussed. A mimeographed English version of the paper is available from the junior author.
New occurrences of trimerophytes from the Devonian of eastern Canada
Authors: Doran Jeffrey B. , Gensel Patricia G. , Andrews Henry N.
Published: October 2007

Pertica dalhousii n.sp. is described from the late Lower or early Middle Devonian of New Brunswick. The plant is known from a central axis with spirally arranged, mostly dichotomous lateral branches. Some lateral branches terminate in erect clusters of 32–128 fusiform sporangia. Spores are circular, trilete, with a detachable outer sculptured layer, and resemble the dispersed spore genus Apiculiretusispora Streel. A trimerophyte from Gaspé is described and provisionally designated as cf. Pertica sp.; the specimens are too incompletely preserved to be assigned to any established species, but they add further information about morphologic variation in the genus Pertica.With the addition of new plant types referable to the trimerophytes, distinctions between genera and species are becoming less readily apparent, supporting the suggestion that the trimerophytes are a group of closely related plants in which considerable evolution was occurring in late Lower and Middle Devonian times. Additionally, these plants appear to represent an early stage in the differentiation of a distinct main axis – lateral branch type of organizaiton that probably led to the later evolution of megaphyllous leaves.
Asci of the Pezizales. VI. The apical apparatus of Morchella esculenta, Helvella crispa, and Rhizina undulata. General discussion
Authors: Samuelson Don A.
Published: October 2007

Morphological, developmental, and cytochemical examinations were made with light and electron microscopy on the apical apparatuses of Morchella esculenta, Helvella crispa, and Rhizina undulata, all species with large, stipitate apothecia. Ascus tips in R. undulata were markedly thinner walled than the rest of the ascus, while those in M. esculenta and H. crispa were slightly thinner than the rest of the ascus wall. Lipid bodies were detected in developing asci of H. crispa and M. esculenta. Their unique occurrence in asci of members of the Morchellaceae and Helvellaceae may have taxonomic significance. With the electron microscope, opercula were distinguished cytochemically in all three species. In H. crispa and M. esculenta dehiscent zones were found to be restricted in the inner layer of the ascal wall. Characters of the apical apparatuses of H. crispa and M. esculenta suggest greater taxonomic relatedness between these species than with any other operculate group. The apical apparatus of R. undulata differed notably from the other species.The present series of studies has demonstrated distinct variability of the operculate ascus and its apical apparatus in morphology, cytochemistry, and development. Several major forms of the apical structures were observed. These examinations support the chemotaxonomic and cytological investigations on representatives of the Pezizales made previously by Arpin and Berthet. Outside of the Thelebolaceae, members of the Pezizales are chiefly characterized by the operculate dehiscence of their asci. Members of the Thelebolaceae eject their spores through a variety of dehiscent mechanisms. Present examinations of those representatives of the Thelebolaceae with functionally operculate apparatuses, i.e., Lasiobolus and Coprotus, support their transferrance to the Pyronemaceae. Taxa which form nonoperative opercula, i.e.,Ascozonus and Trichobolus, also show closer affinities with the Pyronemaceae than with the nonoperculate representatives of the Thelebolaceae. The nonoperculate members of the Thelebolaceae apparently do not belong in the operculate Discomycetes. The operculate ascus wall is structurally compared with the pored and bitunicate ascus walls. The terms 'bitunicate' and 'unitunicate' are redefined.
Scanning electron microscopy of three types of ectomycorrhizae formed on Eucalyptus nova-anglica in the southeastern United States
Authors: Rose Jr. R. W. , Dyke C. Gerald Van , Davey C. B.
Published: October 2007

Three different types of ectomycorrhizae found in the Southeastern United States on Eucalyptus nova-anglica and identified as being formed by Cenococcum geophilum, Pisolithus tinctorius, and Scleroderma geaster were examined with a scanning electron microscope (SEM). In overall appearance the three types of mycorrhizae could be distinguished easily from each other, particularly C. geophilum, which had a relatively smooth, undulate surface in comparison with the other two types. Detailed descriptions and comparisons of these ectomycorrhizae are given and the value of SEM in characterizing ectomycorrhizae is discussed
The relative competitiveness of atrazine susceptible and resistant populations of Chenopodium album and C. strictum
Authors: Warwick S. I. , Black L.
Published: October 2007

The total aboveground biomass and reproductive dry weight of one atrazine resistant and one susceptible population from southern Ontario of each of two species of Chenopodium, C. album and C. strictum, were compared. The comparison was made between plants grown under both noncompetitive and competitive conditions. Results from a spaced noncompetitive trial provided evidence for: (1) greater total and reproductive biomass production and earlier flowering of resistant and susceptible populations of C. album as compared with both populations of C. strictum, (2) greater aboveground total and reproductive biomass production of the susceptible population of C. album as compared with the resistant population, and (3) greater total aboveground biomass production (but similar reproductive biomass) of the susceptible population of C. strictum as compared with the resistant population. Results from the competition trials (i.e., plants grown in a de Wit replacement series), provided evidence for inter- and intra-specific differences in competitive ability: (1) the susceptible population of C. album was found to be more competitive than the susceptible population of C. strictum, (2) the susceptible population of C. album was a superior competitor to the resistant population, and (3) the resistant and susceptible populations of C. strictum appeared to be equally competitive.
Quantifying dinitrogen (N2) fixation in soybeans by 15N isotope dilution: the question of the nonfixing control plant
Authors: Rennie R. J.
Published: October 2007

The stable isotope 15N was used to trace the contribution of soil, fertilizer, and atmospheric N to the plant N of soybeans (Glycine max L. Merrill). 15N isotope dilution is the best technique to quantify N2 fixation (percent nitrogen derived from the atmosphere, % Ndfa) but requires reference to an appropriate nonfixing control plant so that the contribution of soil and (or) fertilizer N to the N yield of the fixing plant may be determined. The nodulating soybean line in nonfixing mode, i.e., uninoculated or inoculated with an ineffective strain of Rhizobium japonicum, was shown to be the best nonfixing control plant. The nonnodulating isoline, even when near isogenic, overestimated the % Ndfa and was judged to be an improper control. Of three nonlegumes tested only Hordeum vulgare was useful as a nonfixing control plant. In two lysimeter studies in a growth room the % Ndfa of Glycine max cv. Harosoy was 59% while that of cv. X005 was 38%. The average % Ndfa of cv. Chippewa soybeans under field conditions was 17%. The precision of the isotopic dilution technique, as measured by the coefficient of variation, was as good as 1.3% in one lysimeter study but averaged 6.2% in growth room lysimeters or in the field.
Early revegetation of clear-cut and burned jack pine sites in northern lower Michigan
Authors: Abrams Marc D. , Dickmann Donald I.
Published: October 2007

Revegetation of clear-cut and (or) burned jack pine (Pinus banksiana Lamb.) sites in northern lower Michigan was characterized during the first 5 years following treatment. Burning promoted the establishment of a large variety of species not typical of unburned areas. A total of 89 species was recorded on burned sites, of which 40 were exclusive, compared with 51 species on unburned sites, of which only 2 species were exclusive. Burned sites consistently showed greater species richness compared with unburned sites of the same age. Low species diversity on the older unburned clear-cuts (years 3 to 6) and certain burned sites was directly influenced by the dominance of the sedge Carex pensylvanica. The total domination of Carex (up to 86% relative cover) on many of these sites appears to be unique to northern lower Michigan. It is hypothesized that Carex, acting as an opportunistic species, monopolizes the space and soil resources liberated following disturbances and suppresses or excludes other species.
Histochemical, spectroscopic, and X-ray diffraction identifications of the two hydration forms of calcium oxalate crystals in three legumes and Begonia
Authors: Horner Harry T. , Zindler-Frank Elisabeth
Published: October 2007

Crystals from species of Rhynchosia, Phaseolus, Canavalia, and Begonia were observed in cleared leaves and their specific locations were noted. Crystals were isolated from leaves, purified, verified for shape with scanning electron microscopy, and characterized as calcium monohydrate (whewellite; Rhynchosia, Phaseolus, and Canavalia) or dihydrate (weddellite; Begonia) by X-ray powder diffraction and infrared spectroscopy. A histochemical technique for calcium oxalate localization was applied to the cleared leaves to complement the physical identifications of the crystals. This histochemical localization (using silver nitrate and rubeanic acid) is specific and represents a simple method for in situ identification of calcium oxalate.
Biomass allocation in hermaphrodite flowers
Authors: Doust Jon Lovett , Cavers Paul B.
Published: October 2007

Patterns of dry matter distribution to male and female organs and to ancillary floral organs were examined in five angiosperm species with hermaphrodite flowers (Lilium superbum, Hibiscus trionum, Podophyllum peltatum, Trillium grandiflorum, and Erythronium albidum). Facultatively self-fertilizing species had higher ratios of female:male allocation while the obligate outbreeder L. superbum had higher male:female patterns. About half the floral dry matter (44–66%) was found in perianth parts as opposed to sporophylls in all species. These preliminary results and others drawn from the literature support the hypothesis that outbreeding species show relatively greater expenditure on male function than self-fertilizing species.
Ultrastructural association of the chromatin-containing lacunar spaces with the vacuolar component of the interphase nucleolus in Allium cepa
Authors: Chouinard L. A.
Published: October 2007

At the ultrastructural level, some of the chromatin-containing lacunar spaces of the interphase nucleolus in root meristematic cells of Allium cepa are seen to be walled off, on one side, by dense-fibrillar material and to be contiguous, on the other side, to electron-transparent areas, of variable sizes and shapes, bordered by dense-granular material continuous with and indistinguishable from the dense-granular component of the nucleolar mass. These electron-transparent areas associated with the lacunar spaces are equated with nucleolar vacuoles since they contain scattered preribosomal-like granules and fibrils and are rimmed by dense-granular material. The relevant observational evidence would be consistent with the view that loops of transcriptionnally active chromatin emanating from the nucleolar organizing region project radially into either only the dense-fibrillar or both the dense-fibrillar and the interior of the electron-transparent vacuolar areas seen to be contiguous to the lacunar spaces in question. In relation to this problem, it is of interest to note that the vacuolar spaces of the interphase nucleolus in Allium cepa occasionally display within their confines discrete masses of fibrillar material, possibly chromatinic in character, and in various states of condensation and configuration.
Effects of nickel and copper on Acer rubrum, Cornus stolonifera, Lonicera tatarica, and Pinus resinosa
Authors: Heale E. L. , Ormrod D. P.
Published: October 2007

Red maple (Acer rubrum), yellow-stem dogwood (Cornus stolonifera 'Flaviramea'), and tartarian honeysuckle (Lonicera tatarica) cuttings and red pine (Pinus resinosa) seedlings were grown in a controlled environment in aerated liquid culture with 2 or 10 mg∙L−1 Ni2+ or 4 or 20 mg∙L−1 Cu2+ singly or in combination (2 and 4 mg∙L−1 or 10 and 20 mg∙L−1). Injury symptoms included marginal and interveinal chlorosis, alteration of leaf pigmentation, severe leaf drop, and abnormally small leaves. With increasing metal levels, root tissues became severely discoloured, lateral roots were few in number, stunted, and thickened, and bulbous root tips developed. Growth and development of plants were retarded in most metal treatments compared with control plants. Tissue accumulation of metals generally increased with increasing Ni and Cu concentrations in the nutrient solutions, but tissue concentrations varied according to species, metal, and tissue analyzed. Pine needles did not accumulate added Cu, while roots of all species contained very high concentrations of Cu. In the combination treatments, the presence of elevated levels of Cu reduced Ni accumulation in the root tissues of all four species and pine stems and leaves and stems of dogwood, compared with the single Ni treatments. In contrast, honeysuckle stems and pine needles had greater Ni accumulation from a combined Ni and Cu treatment than from the corresponding single treatment.
Factors influencing understory seedling establishment of Engelmann spruce (Picea engelmannii) and subalpine fir (Abies lasiocarpa) in southeast Wyoming
Authors: Knapp Alan K. , Smith William K.
Published: October 2007

Although seedlings of Abies lasiocarpa are generally more abundant than those of Picea engelmannii in the understory of mature spruce–fir forests throughout the central and northern Rocky Mountains, little information exists concerning environmental or plant factors that may influence the establishment of these two conifers. Field measurements in the Medicine Bow Mountains of southeast Wyoming showed that seedlings of A. lasiocarpa had greater photosynthetic rates at low understory light levels and required lower levels of incident radiation for saturation of photosynthesis compared with those of P. engelmannii. However, both conifers occurred in understory locations where total daily solar radiation was equally low (<2 MJ∙m−2∙day−1) and thus, a lack of light did not appear to be responsible for the low number of P. engelmannii seedlings in the understory. In contrast, seedlings of P. engelmannii were substantially more abundant at locations with thinner litter layers compared with those of A. lasiocarpa. Also, laboratory studies showed that the smaller seeds of P. engelmannii germinated more rapidly and at lower temperatures than seeds of A. lasiocarpa although growth of tap roots on A. lasiocarpa seedlings was greater initially ([Formula: see text] longer in 2-week-old seedlings) as well as for 10-week-old seedlings (50% longer). The deeper penetrating tap root of A. lasiocarpa seedlings may enable this conifer to establish more abundantly on thick, rapidly drying litter layers that are characteristic of mature spruce–fir forests. In contrast, establishment of P. engelmannii seedlings may be limited to microsites without a thick litter layer such as disturbed areas or decomposing wood, where surface drying may occur more gradually throughout the summer. These results are discussed in terms of the potential effects of seedling establishment on the observed patterns in climax vegetation of central and northern Rocky Mountain subalpine forests.
Population variation in Plantago major from southern Ontario
Authors: Warwick S. I. , McNeill J.
Published: October 2007

The morphological variation and growth and flowering responses in 15 populations of Plantago major collected from different climatic regions and habitat types in southern Ontario were examined. Both within- and between-population differences were assessed using canonical variates analyses. These were carried out on data obtained from field-collected specimens, and from plants grown from seed for a 2-year period in a standard garden trial. Four groupings of the 15 population samples were recognized in the field data. These included the two lawn populations, 8 and 15; population 14, collected from a cultivated field; population 9, originating from a nonmown wasteground site; and the remaining populations collected from a range of trampled roadside – waste ground sites. Analyses of the garden trial data indicated similar groupings. Population 14 remained a distinct group containing individuals characterized by long narrow leaves, a semiprostrate growth form, earlier flowering, greater reproductive effort, reduced rosette production, a larger number of seeds per capsule, and smaller seeds. These individuals would appear to correspond to ssp. pleiosperma. The remaining population samples were characterized by a smaller number of seeds per capsule, larger seeds, a smaller reproductive effort, and later flowering and they would appear to be referable to ssp. major. The two lawn populations, 8 and 15, contained the largest number of prostrate individuals, which were smaller in size and produced less biomass than individuals in the remaining populations. The latter group consisted of large erect plants which produced considerable floral and vegetative growth. There was no evidence for clinal patterns of variation in flowering behaviour and growth features in relation to the climatic gradients in southern Ontario among the 15 populations of P. major.
Teliospore germination in Entorrhiza casparyana (Ustilaginales)
Authors: Fineran Judith M.
Published: October 2007

A study was made of teliospores of Entorrhiza casparyana (Magn.) Lagerh. germinating in situ in degenerating root galls of Juncus articulatus and in galls stored in liquid media at 7 °C for 15 months. Teliospores germinating on agar were also examined. This is the first description of germination in this species. Teliospores germinated in situ and produced up to four aseptate promycelia each bearing up to four falcate sporidia, often distinctively looped or curved and in a terminal or subterminal position. On agar, teliospores germinated directly and formed septate branched hyphae but no sporidia. Karyokinesis occurred in the teliospores prior to germination. Division was presumed to be meiotic and to be followed by at least one mitosis. Cytokinesis followed, with up to four sectors being formed in a spore; this feature is described for the first time and appears to be unique to this genus. The mode of germination places Entorrhiza in the Tilletiaceae and also distinguishes it from Melanotaenium. The taxonomic position of the Ustilaginales is briefly discussed; the observations made so far on spore germination in E. casparyana support the retention of the Tilletiaceae in the Basidiomycetes.
The mechanism of plication inception in palm leaves: histogenetic observations on the pinnate leaf of Chrysalidocarpus lutescens
Authors: Dengler Nancy G. , Dengler Ronald E. , Kaplan Donald R.
Published: October 2007

The reduplicate, pinnately compound leaf of Chrysalidocarpus lutescens begins development as a hood-shaped primordium with a smooth lamina. By the time the leaf is 5.5 mm in length, 40–42 pleats consisting of alternating ridges and furrows have been formed in a submarginal position on each half of the lamina. Serial sections of plastic-embedded leaf primordia were studied to distinguish between two alternative mechanisms of plication inception proposed in the literature: differential growth or tissue separation. Counts of the number of cell layers in the lamina during the period of plication initiation support the concept of differential growth, i.e., an increase in the number of tissue layers is observed at the site of furrow formation rather than a decrease in cell layers which would be expected if tissue separation were occurring. Ridges appear first on the adaxial side of the lamina, accompanied by periclinal and oblique divisions in the middle lamina layers. Further growth is associated with zones of anticlinal divisions alternating with the ridges. This plate meristem growth increases the surface area of a portion of the lamina bounded by the leaf apex, the unplicate margin, the petiole, and the rachis, and therefore tends to be accommodated by a buckling of the lamina between adaxial ridges. Intercalary growth of the intercostal sector causes the adaxial and abaxial ridges to be displaced from each other, deepening the plications. Examination of early stages of leaf development with the transmission electron microscope corroborates these results; there is no indication of schizogenous separation of cells within the ground tissue of the lamina or between protodermal cells. The protoderm and its cuticle are continuous at all stages of plication initiation, supporting the concept of differential growth.
Les peptides de faible masse moléculaire dans la feuille et les gousses de soja
Authors: Serres Monique Naudy–de , Calmés Jean , Viala Guy
Published: October 2007

Peptides were studied at the seed-filling stage in field-grown soybean, Glycine max (L.) Merr cv. Amsoy 71. Separation of peptides was obtained by dialysis through a thin membrane (porosity, 10 000) and filtration on a Sephadex G-15 column. In the leaflet, peptides were more abundant than free amino acids and their composition was slightly different from that of proteins. After foliar 14CO2 incorporation, labelling showed that peptides were partly translocated towards the pods. In the petiole and pod walls, peptides were less abundant than in the leaflet and their lysine content was higher. In the seeds, the amount of peptides also increased and their percentage composition in histidine was greater, indicating high metabolic activity directed toward storage protein synthesis.
Surface-sediment chrysophytes from 35 Quebec lakes and their usefulness in reconstructing lake-water pH
Authors: Dixit Aruna S. , Dixit Sushil S.
Published: October 2007

Chrysophyte scales from surface sediment samples of 35 Quebec lakes were analyzed to examine their relationship with lake-water pH. The percent composition of common chrysophyte taxa were plotted against the measured lake-water pH. The distribution of many taxa was found to be closely associated with pH. The pH indicator status and abundance-weighted mean pH values of the majority of taxa of the studied region agreed with the published work. Chrysophyte counts were quantified to establish a predictive pH model using multiple regressions of pH indicator chrysophyte assemblages with lake-water pH. A strong relationship (r2 = 0.72) was observed between measured and inferred pH values. The pH predictive ability of chrysophytes was further corroborated by reconstructing the recent pH history of Lake Bonneville. Over the last 30 years, the inferred pH of this lake has declined ≈ 1 pH unit. The present study accentuates that stratigraphic analysis of chrysophytes will provide useful measurements of the extent of lake-water acidity in Quebec.
Antifungal, physicochemical, and insect-repelling activity of the essential oil of Ocimum basilicum
Authors: Dube S. , Upadhyay P. D. , Tripathi S. C.
Published: October 2007

The essential oil of Ocimum basilicum at a dose of 1.5 mL/L completely inhibited the mycelial growth of 22 species of fungi, including the mycotoxin-producing strains of Aspergillus flavus and Aspergillus parasiticus. It also proved to repel the insect Allacophora foveicollis. The toxic dose of the oil against the test fungi was much lower than that of some commercial fungicides and fumigants, and it remains unaffected by temperature treatment, storage, and increased inoculum.
Cytogéographie de l'Aster cordifolius (Asteraceae : Astereae) au Québec
Authors: Legault André , Brouillet Luc
Published: October 2007

The chromosome numbers of 209 individuals of Aster cordifolius L. from ca. 130 localities from the provinces of Quebec and New Brunswick were determined; 122 were diploid and 87, tetraploid. Four populations are mixed, but no triploid was found; experimental crosses beween the two cytotypes failed. Genic exchanges do not appear to exist between the two races, at least not via normal gametes. In Quebec, the two cytotypes are sympatric in the Richelieu valley; west of this area, only tetraploids are found, and east of it, only diploids. This distribution pattern continues the one observed in Ontario, New York State, and New England, where the contact zone is, however, wider. No obvious ecological differences were noted between the two chromosomal races. Postglacial migration on either side of the Appalachian–Adirondack axis, tetraploids to the west and diploids to the east, appears to explain the distribution of cytotypes of A. cordifolius in Quebec.
The distribution of scaled chrysophytes along a pH gradient
Authors: Siver Peter A.
Published: October 2007

Frequency distributions versus pH and weighted mean pH values are reported for 25 and 40 species of scaled chrysophytes, from water bodies in Connecticut and the Adirondacks, respectively, and are compared with those assembled from a survey of the literature. For most species, similar distributions with respect to a pH gradient and weighted mean pH values were found. However, in Connecticut and Adirondack lakes, Mallomonas punctifera and Synura spinosa were more restricted to slightly acidic conditions and M. hamata was more abundant in conditions below a pH of 5.5. Groups of taxa with similar distributions with respect to pH were clearly defined. One group, consisting of Mallomonas acaroides var. muskokana, M. paludosa, M. pugio, M. canina, M. hindonii, S. sphagnicola, and S. echinulata, was dominant in waters with a pH < 5.5. Another group, including M. acaroides var. acaroides, M. corymbosa, M. tonsurata, M. psuedocoronata, and M. alpina, was primarily restricted to pH values above 6.5. A third group, including M. punctifera, M. akrokomas, M. crassisquama, M. galeiformis, M. caudata, Spiniferomonas bourrellyi, Sp. serrata, S. spinosa, and Chrysosphaerella longispina, had a significant decline in occurrence as the pH lowered to the 5–5.5 interval. The importance of scaled chrysophytes as a group in the biomonitoring of acid deposition is discussed.
Lignification level and peroxidase activity during in vitro rooting of Prunus avium
Authors: Dalet Fabienne , Cornu Daniel
Published: October 2007

To improve the in vitro rooting of selected clones of wild cherry (Prunus avium), the search for a physiological marker for rhizogenesis was initiated. Peroxidase activity is considered as a good rooting marker for other Prunus species. Peroxidase activity was thus assayed by spectrophotometric measurement, and cationic and anionic isoperoxidases were separated by polyacrylamide gel electrophoresis. The measurement of peroxidase activity was made during the first 8 days of subculture on rooting medium with and without auxin (β-indolylbutyric acid). From a first set of experiments, there was no relationship between peroxidase activity and the rooting process. In a second series of experiments, before subculturing on the rooting medium with and without auxin, the explants were divided into three classes according to their lignification level: less, moderately, and more lignified cuttings. Level and changes in peroxidase activity were found to be correlated with the lignification level of the explants. However, there was no effect on final rooting rate. In each class of shoots, the relationship between peroxidase activity and rooting rate, with or without auxin, was highly variable.
Induction of conjugation in Mougeotia
Authors: Stabenau H. , Säftel W.
Published: October 2007

The alga Mougeotia, strain 164.80, from the algae collection of the University of Göttingen, can be stimulated into sexual reproduction by decreasing the concentration of nitrate in the growth medium from 10−2 to 10−3 M. This effect could not be observed at any other concentration. To initiate the sexual process, cultures were illuminated with an intensity of 550 foot candles. Aeration of the cultures was absolutely necessary. Conjugation started 6 or 9 days after limitation of the nitrogen supply, depending on the CO2 content in the aeration mixture. From the characteristics observed during conjugation, strain 164.80 was identified to be Mougeotia scalaris Hassall.
Photosynthesis and export during steady-state photosynthesis in bean leaves infected with the bacterium Xanthomonas campestris pv. phaseoli
Authors: Jiao Jirong , Grodzinski Bernard , Goodwin Paul
Published: October 2007

Export and distribution of 14C assimilates during a period of steady-state photosynthesis were studied in attached leaflets of the second trifoliate of Phaseolus vulgaris for 2 weeks following inoculation with Xanthomonas campestris pv. phaseoli. The control was the leaflet opposite the inoculated leaflet at the same node. On either a chlorophyll or leaf area basis, photosynthesis and export declined over time after inoculation compared with control tissue. By 14 days after inoculation, photosynthesis and export were 25 and 50% lower, respectively, in the infected leaflets, even though only 7–10% of the total area measured was necrotic. The reduced synthesis of sucrose was sufficient to account for the reduced export from the infected leaflets. Starch synthesis was reduced to a greater extent in infected leaflets than was sucrose synthesis. In leaf disks infiltrated with mannose or xanthan, an extracelluar bacterial polysaccharide containing mannose, photosynthesis was reduced by 20% and the partitioning of 14C photoassimilates into sucrose was reduced but was slightly increased into starch. This is consistent with an effect of xanthan at least in vitro on the triose phosphate/phosphate exchange at the chloroplast envelope. Keywords: photosynthesis, export, xanthan, Phaseolus vulgaris, Xanthomonas campestris pv. phaseoli.
Possible involvement of lipoxygenase in a defense response in aflatoxigenic Aspergillus – cotton plant interactions
Authors: Zeringue Jr. H. J.
Published: October 2007

Damage to the carpel surface of the developing cotton boll such as that caused by infection with aflatoxigenic Aspergillus spp. results in activation of the lipoxygenase pathway. Lipoxygenase pathway activation generates a series of diverse, antifungal, volatile aldehydes that affect the growth of Aspergillus flavus and indirectly has an effect on aflatoxin production. Analysis of the head space volatile aldehydes by gas chromatography – mass spectrometry trapped during a 1-h sampling period of carpel surfaces of 23- to 35-day developing cotton bolls treated with exogenous lipase resulted in the identifications of C5–C9 alkanals and alkenals including hexanal and trans-2-hexenal. Hexanal concentrations generated in lipase-treated bolls resulted in a two-fold increase of hexanal production. The effects of trans-2-hexenal on aflatoxin production were determined on intact 30-day-old developing cotton bolls treated with 2.2–8.6 μmol amounts of trans-2-hexenal and inoculated with aflatoxigenic Aspergillus in three different treatment systems. Trans-2-hexenal was placed on the developing cotton boll (i) 24 h before, (ii) 24 h after, or (iii) simultaneously with fungal inoculation. After a 3-week incubation on the intact cotton plants, bolls were harvested and aflatoxin determinations were conducted on cottonseeds from the bolls. The results suggest that pretreatment of the boll with trans-2-hexenal initiates a strong antagonism to aflatoxin formation due to the antifungal effects on the growth of the fungus in developing cotton bolls. These results also demonstrate a series of host-plant defense responses that suggest the possible involvement of the lipoxygenase pathway in interactions between aflatoxigenic Aspergillus and the cotton plant. Keywords: aflatoxin, Aspergillus flavus, cotton (Gossypium hirsutum), lipoxygenase (LOX) pathway, lipids.
Growth, physiological, and biochemical responses of three tropical legumes to enhanced UV-B radiation
Authors: Singh Anupa
Published: October 2007

Experiments were conducted under field conditions to assess selected growth, physiological, and biochemical responses of three leguminous plants (Vigna radiata L. (Wilczek) cv. PS-16, Phaseolus mungo L. (Hepper) cv. Mash-48, and Glycine max L. (Merr.) cv. Punjab 1) to enhanced UV-B radiation equivalent to 15% ozone depletion at 25°N latitude. Enhanced UV-B radiation adversely affected growth characteristics, chlorophyll and carotenoid contents, photosynthetic rate, ascorbic acid content, and catalase activity, whereas a reverse trend was found for phenol content and peroxidase activity in all three species. However, the magnitudes of increases or decreases were different among species, and there was no direct relationship between growth and biochemical responses across species. Keywords: chlorophyll, Glycine max, net photosynthesis, Phaseolus mungo, plant growth, Vigna radiata.
A NOTE ON LUENBERGER'S ZERO-MAXIMUM PRINCIPLE FOR CORE ALLOCATIONS
Authors: COURTAULT JEAN-MICHEL , CRETTEZ BERTRAND , HAYEK NAILA
Published: October 2007

In this note, we state a zero-maximum principle for core allocations, a result which was foreseen by Luenberger (1995). We prove a generalization of the first-zero maximum theorem of Luenberger. Roughly said, an allocation is in the core if for every coalition, the sum of individual benefit functions is non-positive. We also provide some partial converses which give a generalization of the second-zero maximum theorem of Luenberger.
Proliferation capacity of the renal proximal tubule involves the bulk of differentiated epithelial cells
Authors: Vogetseder Alexander , Picard Nicolas , Gaspert Ariana , Walch Michael , Kaissling Brigitte , Le Hir Michel
Published: October 2007

We investigated the proliferative capacity of renal proximal tubular cells in healthy rats. Previously, we observed that tubular cells originate from differentiated cells. We now found 1) by application of bromo-deoxyuridine (BrdU) for 14 days and costaining for BrdU, and the G1-phase marker cyclin D1 that the bulk of cells in the S3 segment of juvenile rats were involved in proliferation; 2) that although the proliferation rate was about 10-fold higher in juvenile rats compared with adult rats, roughly 40% of S3 cells were in G1 in both groups; 3) that after a strong mitotic stimulus (lead acetate), proliferation was similar in juveniles and adults; 4) that there was a high incidence of cyclin D1-positive cells also in the healthy human kidney; and 5) by labeling dividing cells with BrdU for 2 days before the application of lead acetate and subsequent costaining for BrdU and cell cycle markers, that, although a strong mitotic stimulus does not abolish the period of quiescence following division, it shortens it markedly. Thus the capacity of the proximal tubule to rapidly recruit cells into division relies on a large reserve pool of cells in G1 and on the shortening of the obligatory period of quiescence that follows division.