bluuebunny/crossref_metadata_2025 huggingface dataset:
Human Immunodeficiency Virus Type 1 Gag Engages the Bro1 Domain of ALIX/AIP1 through the Nucleocapsid
Authors: Popov Sergei , Popova Elena , Inoue Michio , Göttlinger Heinrich G.
Published: November 2007

Human immunodeficiency virus type 1 (HIV-1) and other retroviruses harbor short peptide motifs in Gag that promote the release of infectious virions. These motifs, known as late assembly (L) domains, recruit a cellular budding machinery that is required for the formation of multivesicular bodies (MVBs). The primary L domain of HIV-1 maps to a PTAP motif in the p6 region of Gag and engages the MVB pathway by binding to Tsg101. Additionally, HIV-1 p6 harbors an auxiliary L domain that binds to the V domain of ALIX, another component of the MVB pathway. We now show that ALIX also binds to the nucleocapsid (NC) domain of HIV-1 Gag and that ALIX and its isolated Bro1 domain can be specifically packaged into viral particles via NC. The interaction with ALIX depended on the zinc fingers of NC, which mediate the specific packaging of genomic viral RNA, but was not disrupted by nuclease treatment. We also observed that HIV-1 zinc finger mutants were defective for particle production and exhibited a similar defect in Gag processing as a PTAP deletion mutant. The effects of the zinc finger and PTAP mutations were not additive, suggesting a functional relationship between NC and p6. However, in contrast to the PTAP deletion mutant, the double mutants could not be rescued by overexpressing ALIX, further supporting the notion that NC plays a role in virus release.
Endogenous Cytotoxic T-Cell Response Contributes to the Long-Term Antiretroviral Protection Induced by a Short Period of Antibody-Based Immunotherapy of Neonatally Infected Mice
Authors: Gros Laurent , Pelegrin Mireia , Michaud Henri-Alexandre , Bianco Stéphanie , Hernandez Javier , Jacquet Chantal , Piechaczyk Marc
Published: November 2007

Neutralizing monoclonal antibodies (MAbs) are increasingly being considered for blunting human viral infections. However, whether they can also exert indirect effects on endogenous antiviral immune responses has been essentially overlooked. We have recently shown that a short (several-day) period of immunotherapy with the neutralizing 667 MAb of mouse neonates shortly after infection with the lethal FrCasEretrovirus not only has an immediate effect on the viral load but also permits an endogenous antiviral immunity to emerge. Even though passive immunotherapy was administered during the particular period of immunocompetence acquisition, the endogenous response eventually arising was protective and persisted long (>1 year) after the MAb has disappeared. As very high levels of anti-FrCasEantibodies, predominantly of the immunoglobulin G2a (IgG2a) isotype and showing strong neutralization activity, were found in the sera of MAb-treated mice, it was necessary to address whether this humoral immunity was sufficient on its own to confer full protection against FrCasEor whether a cytotoxic T-lymphocyte (CTL) response was also necessary. Using a variety of in vivo assays in young and adult animals previously infected by FrCasEand treated by 667, we show here that transient 667 immunotherapy is associated with the emergence of a CTL response against virus-infected cells. This cytotoxic activity is indispensable for long-term antiviral protective immunity, as high neutralizing antibody titers, even enhanced in in vivo CD8+cell depletion experiments, cannot prevent the FrCasE-induced death of infected/treated mice. Our work may have important therapeutic consequences, as it indicates that a short period of MAb-based immunotherapy conducted at a stage where the immune system is still developing can be associated with the mounting of a functional Th1-type immune response characterized by both CTL and IgG2a-type humoral contributions, the cooperation of which is known to be essential for the containment of chronic infections by a variety of viruses.
Role of Intergenic Sequences in Newcastle Disease Virus RNA Transcription and Pathogenesis
Authors: Yan Yongqi , Samal Siba K.
Published: November 2007

Newcastle disease virus (NDV), a member of the family
Paramyxoviridae
, has a nonsegmented negative-sense RNA genome consisting of six genes (3′-NP-P-M-F-HN-L-5′). The first three 3′-end intergenic sequences (IGSs) are single nucleotides (nt), whereas the F-HN and HN-L IGSs are 31 and 47 nt, respectively. To investigate the role of IGS length in NDV transcription and pathogenesis, we recovered viable viruses containing deletions or additions in the IGSs between the F and HN and the HN and L genes. The IGS of F-HN was modified to contain an additional 96 nt or more or a deletion of 30 nt. Similarly, the IGS of HN-L was modified to contain an additional 96 nt or more or a deletion of 42 nt. The level of transcription of each mRNA species (NP, F, HN, and L) was examined by Northern blot analysis. Our results showed that NDV can tolerate an IGS length of at least 365 nt. The extended lengths of IGSs down-regulated the transcription of the downstream gene and suggested that 31 nt in the F-HN IGS and 47 nt in the HN-L IGS are required for efficient transcription of the downstream gene. The effect of IGS length on pathogenicity of mutant viruses was evaluated in embryonated chicken eggs, 1-day-old chicks, and 6-week-old chickens. Our results showed that all IGS mutants were attenuated in chickens. The level of attenuation increased as the length of the IGS increased. Interestingly, decreased IGS length also attenuated the viruses. These findings can have significant applications in NDV vaccine development.
Engineered Disulfide Bonds in Herpes Simplex Virus Type 1 gD Separate Receptor Binding from Fusion Initiation and Viral Entry
Authors: Lazear Eric , Carfi Andrea , Whitbeck J. Charles , Cairns Tina M. , Krummenacher Claude , Cohen Gary H. , Eisenberg Roselyn J.
Published: November 2007

Glycoprotein D (gD) is the receptor binding protein of herpes simplex virus (HSV) and binds to at least two distinct protein receptors, herpesvirus entry mediator (HVEM) and nectin-1. While both receptor binding regions are found within the first 234 amino acids, a crystal structure shows that the C terminus of the gD ectodomain normally occludes the receptor binding sites. Receptor binding must therefore displace the C terminus, and this conformational change is postulated to be required for inducing fusion via gB and gH/gL. When cysteine residues are introduced at positions 37 and 302 of gD, a disulfide bond is formed that stabilizes the C terminus and prevents binding to either receptor. We speculated that if disulfide bonds were engineered further upstream, receptor binding might be separated from the induction of fusion. To test this, we made five additional double cysteine mutants, each potentially introducing a disulfide bond between the ectodomain C terminus and the core of the gD ectodomain. The two mutants predicted to impose the greatest constraint were unable to bind receptors or mediate cell-cell fusion. However, the three mutants with the most flexible C terminus bound well to both HVEM and nectin-1. Two of these mutants were impaired in cell-cell fusion and null-virus complementation. Importantly, a third mutant in this group was nonfunctional in both assays. This mutant clearly separates the role of gD in triggering fusion from its role in receptor binding. Based upon the properties of the panel of mutants we conclude that fusion requires greater flexibility of the gD ectodomain C terminus than does receptor binding.
Frequent and long-term absence as a risk factor for work disability and job termination among employees in the private sector
Authors: Koopmans P C , Roelen C A M , Groothoff J W
Published: November 2007

Objectives:

Frequent and long-term absentees were monitored over 5 years with regard to the risk of work disability and job termination.

Methods:

A prospective longitudinal cohort study in 53 990 employees of Dutch postal and telecommunications companies. In the first year of the study, employees who were absent four times or more (frequent absentees; n = 4126), for 6 weeks or more (long-term absentees; n = 3585), and combined frequent and long-term absentees (n  =  979) were distinguished, together with a reference population consisting of 45 300 employees. The disability rate (defined as the number of employees who were absent for >1 year per 100 employee-years) and the risk of job termination were determined over a period of 4 years.

Results:

In the reference population, women had a higher disability rate (2.2 per 100 employee-years) than men (0.8 per 100 employee-years). Frequent absentees had a disability rate amounting to 2.5 per 100 employee-years in men and 4.2 per 100 employee-years in women. Long-term absentees had a disability rate of 6.7 per 100 employee-years in men and 9.1 per 100 employee-years in women. Combined frequent and long-term absentees had an even higher disability rate. The risk of employment being terminated (involuntarily) was higher in prior absentees as compared with the reference population (RR = 1.2–2.1 for job termination and RR = 1.5–2.5 for involuntary job termination). In men, absences due to neoplasms, mental disorders and respiratory disorders were associated with an increased disability risk as compared with musculoskeletal disorders. Neoplasms and mental disorders were also associated with a higher risk of job termination in men, whereas infectious and neurological diseases were associated with a higher risk of job termination in women.

Conclusions:

Prior frequent and/or long-term absentees show high work disability in a 4-year follow-up period. Moreover, they are at higher risk of (involuntary) job termination.
Airborne particulate matter exposure and urinary albumin excretion: the Multi-Ethnic Study of Atherosclerosis
Authors: O’Neill M S , Diez-Roux A V , Auchincloss A H , Franklin T G , Jacobs D R , Astor B C , Dvonch J T , Kaufman J
Published: November 2007

Objectives:

Understanding mechanistic pathways linking airborne particle exposure to cardiovascular health is important for causal inference and setting environmental standards. We evaluated whether urinary albumin excretion, a subclinical marker of microvascular function which predicts cardiovascular events, was associated with ambient particle exposure.

Methods:

Urinary albumin and creatinine were measured among members of the Multi-Ethnic Study of Atherosclerosis at three visits during 2000–2004. Exposure to PM2.5and PM10(μg/m3) was estimated from ambient monitors for 1 month, 2 months and two decades before visit one. We regressed recent and chronic (20 year) particulate matter (PM) exposure on urinary albumin/creatinine ratio (UACR, mg/g) and microalbuminuria at first examination, controlling for age, race/ethnicity, sex, smoking, second-hand smoke exposure, body mass index and dietary protein (n = 3901). We also evaluated UACR changes and development of microalbuminuria between the first, and second and third visits which took place at 1.5- to 2-year intervals in relation to chronic PM exposure prior to baseline using mixed models.

Results:

Chronic and recent particle exposures were not associated with current UACR or microalbuminuria (per 10 μg/m3increment of chronic PM10exposure, mean difference in log UACR = −0.02 (95% CI −0.07 to 0.03) and relative probability of having microalbuminuria = 0.92 (95% CI 0.77 to 1.08)) We found only weak evidence that albuminuria was accelerated among those chronically exposed to particles: each 10 μg/m3increment in chronic PM10exposure was associated with a 1.14 relative probability of developing microalbuminuria over 3–4 years, although 95% confidence intervals included the null (95% CI 0.96 to 1.36).

Conclusions:

UACR is not a strong mechanistic marker for the possible influence of air pollution on cardiovascular health in this sample.
Lichen substances of transplanted thallus segments of Parmelia cumberlandia
Authors: Fahselt Dianne
Published: November 2007

Three large thalli of the saxicolous lichen Parmelia cumberlandia (Gyeln.) Hale were subdivided. Portions were relocated to new sites within southern Ontario where they were left for a period of 1 year. At the end of the transplant period lichen substances in young tissue at the transplant sites were compared quantitatively with those produced at the original collection site. Changes were observed with respect to one minor unknown substance, but the depsidones and usnic acid were unaffected either qualitatively or quantitatively. Environmental differences of the magnitude tested were insufficient to cause major changes in lichen chemistry.
Ultrastructure of the pycnial and aecial stages of Puccinia recondita
Authors: Gold R. E. , Littlefield L. J. , Statler G. D.
Published: November 2007

The haploid stage of Puccinia recondita in Thalictrum speciosissimum was established by basidiospore infection. Haploid hyphae were inter- and intra-cellular. Intracellular structures arose from intercellular hyphae without prior formation of specialized mother cells. They gained entrance into host cells via wide-diameter penetration sites; they were hyphal-like and formed abundantly in both mesophyll and epidermal cells. Commonly, they exited host cells to become intercellular hyphae or intracellular hyphae in adjacent host cells. Numerous, globose pycnia were borne in wart-like humps on the leaf tissue. Paraphyses and flexuous hyphae extended through the ostiole, initially aggregated into a column, but later become radiate. Globose to oblong aecia developed one to three cells below the lower epidermis of humped leaf tissue. Aeciospore initials arose from a stroma of sporogenous tissue at the base of the aecia. Successive divisions of aeciosporophores produced catenulate aeciospores separated by intercalary cells. The first appearance of aeciospore wall ornaments (verrucae) was associated with the division of aeciospore initials into aeciospores and intercalary cells. The electron-lucent verrucae were contiguous with the spore plasmalemma and enlarged to full size (ca. 0.5 × 0.3 μm) in the primary cell wall. During maturation aeciospores underwent a two- to three-fold increase in diameter and the intercalary cells disintegrated. Simultaneously, the primary wall of the aeciospores broke down, exposing the verrucae. The secondary wall formed centripetal to the disintegrating primary wall to provide the major portion of the mature spore wall. The verrucose, mature aeciospores were globose to elliptical (ca. 16.5 × 19 μm). Germ pores were locally thickened areas within the secondary cell wall and contained small electron-lucent interspersions. The peridial cells which delimit the aecia were differentially thickened. The thick outer cell wall contained dagger-shaped, electron-lucent processes and the relatively thin inner wall was ornamented with smooth, knob-like, electron-lucent clavae.
La placentation axillaire chez Ochna atropurpurea
Authors: Pauzé Fernand , Sattler Rolf
Published: November 2007

In Ochna atropurpurea DC., five to seven crescent-shaped gynoecial primordia are formed. They become continuous with each other soon after their inception and thus form a syncarpous gynoecium whose final appearance is pseudoapocarpous (ecological apocarpy). There are as many ovules as gynoecial primordia. Each ovule arises from the biseriate tunica and the corpus on the periphery of the floral apex in the axil of a gynoecial primordium. The presence of across zone (Querzone) could not be clearly demonstrated. Since the position of ovule inception is equivalent (homotopous) to that of axillary branches, we propose to term this configuration axillary placentation. If it is agreed upon that axillary branches arise from the stem (caulome), then the axillary placentation of this species is also of cauline origin. It then follows as a logical consequence that the gynoecium is acarpellate. Whether this acarpellate condition is primitive or derived from a carpellate organization remains unresolved. In the case of a derivation from a carpellate gynoecium, one would have to postulate a phylogenetic shifting of ovule inception and (or) the reduction of the adaxial portion of a carpel whose margins were confluent and thus formed a more or less cylindrical primordium. Congenital or phylogenetic fusion of the cross zone of a peltate carpel with the floral apex is not even a theoretically possible hypothesis since it is not in agreement with any conceivable ontogenetic and phylogenetic processes.
The effect of Tordon 101 herbicide on soil organic matter balance
Authors: Suffling Roger , Smith David W.
Published: November 2007

Forest clearance followed by brush control using Tordon 101 (a mixture of picloram and 2,4-dichlorophenoxyacetic acid), caused a decreased thickness of surface organic matter on power line rights-of-way in northern Ontario. The resultant exposure of mineral soil encourages recolonization by tree seedlings. Surface organic matter loss must therefore be controlled to avoid brush-control problems from seeded-in tree species. Erosion is unimportant in removing litter, but decreased net aerial primary production and hastened organic matter decay following spraying are crucial. Organic matter decomposition is increased because soil temperatures rise when the shading plant canopy is killed by the herbicide. The rise in soil temperature is insufficient, however, to entirely account for the hastened decomposition observed. A low-growing, herbicide-resistant, shade-producing, decay-resistant plant canopy is the ideal as a natural or artificial cover crop for transmission corridors. We conclude that Tordon's capacity to push succession back to an early stage is not related solely to its selective toxicity but also to changes in community metabolism.
Embryogeny of Phaseolus coccineus: the ultrastructure and development of the suspensor
Authors: Yeung Edward C. , Clutter Mary E.
Published: November 2007

Structural specializations occur in the suspensor at the proembryo stage with the formation of wall ingrowths. Soon after the appearance of the ingrowths, mitochondria, plastids, polysomes, and smooth endoplasmic reticulum greatly increase in their abundance within the suspensor cells. By the late globular stage, wall ingrowths are extremely well developed and the cells within the suspensor are packed with cellular organelles. The nucleus of the suspensor cell at the heart stage also takes on an active appearance. The nucleus becomes highly lobed in shape and micronucleoli can also be found. There is little change in the overall ultrastructural pattern of the cell till the cotyledon stage. At this stage, wall thickening occurs in all suspensor cells and the outlines of most of the ingrowths become less obvious. The mitochondria, plastids, and polysomes become less abundant and a change in the configuration of the smooth endospermic reticulum is also observed. The ontogenetic changes of the cellular organelles suggest that the suspensor plays a role during early embryo development, i.e., globular to early cotyledon stage.
Some aspects of carbon relations in the barley – Helminthosporium teres complex. I. The effects of infection upon carboxylation in vivo and in vitro
Authors: Rowe Janet , Reid J.
Published: November 2007

First leaves of seedlings of the barley varieties Parkland (susceptible) and C.I. 5791 (resistant) were inoculated with the net blotch organism Helminthosporium teres. In Parkland, over the 7-day infection cycle (inoculation to sporulation), (1) ribulosediphosphate (RuDP) carboxylase activity, chlorophyll levels, and carbon fixation in the light all fell to ca. 50% of control levels and (2) the activities of phosphoenolpyruvate (PEP) carboxylase and the malic enzyme, and carbon fixation in the dark (which was 0.5% that in the light in healthy tissue), rose 200–400%, peaking just before sporulation of the pathogen. Quantitative analytical studies of the early products of 14CO2 fixation in the light indicated that carbon entered metabolism predominantly via the Calvin cycle in healthy and infected plants. However, β-carboxylation, which in all samples was higher in the light than in the dark, showed a significant increase in susceptible tissues upon H. teres infection. In C.I. 5791 (hypersensitive reaction), the metabolic changes were similar to those in Parkland, with the magnitude of the metabolic response being related to the extent of fungal development; the effect persisted until the growth of the pathogen was inhibited. The changes induced in carbon fixation in situ in response to infection could be reproduced to a limited extent by physical damage, but the response to pathogenesis, especially in susceptible tissues, was probably more specific. The possible significance of this response is discussed.
Studies in the Alismataceae. VIII. Experimental modification of organogenesis in Ranalisma humile
Authors: Charlton W. A.
Published: November 2007

Treatments of the submerged form of Ranalisma humile with growth-active substances produces rather erratic modifications of organogenesis in the pseudostolons (submerged and essentially sterilized inflorescences). Gibbereliic acid tends to increase the frequency of precocious bud development while (2-chloroethyl)trimethylammonium chloride (CCC) depresses it. Both kinetin and gibbereliic acid may modify the normal determination pattern of meristems. Kinetin may induce gross disturbances of pattern. The significance of the modifications is discussed in relation to the normal developmental morphology of R. humile and related plants.
Etude des composés terpéniques au cours de la croissance des aiguilles du Pin maritime : comparaison de données biochimiques et ultrastructurales
Authors: Bernard-Dagan C. , Carde J. P. , Gleizes M.
Published: November 2007

In maritime pine needles, comparisons of infrastructural and biochemical results show that a preferential site of synthesis for the monoterpene hydrocarbons (C10) is located in the epithelial cells of the resin ducts, the basal part of the needles having a higher content of monoterpenes than the upper parts. The incorporation of 14C in the monoterpenes at the base is respectively 16 and 66 times more important than at the medium and upper parts. An electron microscopic study of the evolution of the epithelial cells of the resin ducts shows a temporary activity of these cells and this activity is very intense only at the base of the needles.In contrast, the sesquiterpenes (C15) are synthesized in the whole needle according to a permanent process. The three parts of the needles present a progressive and continuous accumulation, and a significant incorporation of 14CO2 in sesquiterpenes. The electron microscopy reveals an irreversible degenerating process of the epithelial cells of the ducts in the upper parts. Therefore, the sesquiterpene synthesis is not only related to the activity of the ducts but is also present in the secretory structures presenting a permanent activity and located in cells devoid of specialized secretory functions.
Fibulobasidium: a new genus in the Sirobasidiaceae
Authors: Bandoni R. J.
Published: November 2007

A new genus and species, Fibulobasidium inconspicuum, is described in the Sirobasidiaceae. The basidia of the species are terminally single or develop in clusters through expansion of successive clamp loops. The incompatibility system is similar to that of Tremella and Sirobasidium species that have been studied.
Gametophytic distinctions of Zygodon (Orthotrichaceae) and Anoectangium and Leptodontium (Pottiaceae) and the status of Anoectangium rubrigemmium of Hawaii
Authors: Zander Richard H. , Vitt Dale H.
Published: November 2007

Phyletically, Zygodon (Orthotrichaceae) and Anoectangium and Leptodontium (Pottiaceae) are only distantly related; however, gametophytically, they are sometimes very similar. In the absence of sporophytic characters, these three genera can best be distinguished by stem anatomy, costal anatomy, and areolation and papillae of the upper leaf lamina. A key is provided for the five Hawaiian species of these genera and Anoectangium rubrigemmium Hoe & Crum is considered a member of the genus Zygodon, Z. rubrigemmius (Hoe & Crum) Zander & Vitt comb. nova.
The cytogeography of Aster lanceolatus (synonyms A. simplex and A. paniculatus) in Ontario with additional counts from populations in the United States
Authors: Semple John C.
Published: November 2007

Chromosome numbers of one to four individuals from 115 populations (primarily Ontario) of Aster lanceolatus were determined from either pollen mother cell meiosis or root tip cell mitosis of transplanted rootstocks. Hexaploids (2n = 48) were found throughout the range sampled. Tetraploids (2n = 32), pentaploids (2n = 40), septaploids (2n = 56), and octoploids (2n = 64) were found scattered in a wide zone running roughly along the Niagara Escarpment. The zone is underlain by Silurian sedimentary limestone. While hexaploids were found most frequently in the southern two-thirds of this zone, octoploids were found most frequently on Manitoulin Island at the northern end of the zone.
Inhibition of fungal growth by plant growth retardants
Authors: Ali A. , Hall R. , Fletcher R. A.
Published: November 2007

Ancymidol, Amitrole, and Phosphon-D, three plant growth retardants known to interfere with isoprenoid synthesis in plants, were found to be fungitoxic. Of nine fungi tested, five were highly sensitive to ancymidol (concentration required to cause 50% inhibition of mycelial growth (ED50) less than 50 mg/L) and a different set of five was highly sensitive to Amitrole. Ancymidol was more toxic than Captan to Fiisarium graminearum and at a concentration of 100 mg/L prevented growth of Bipolaris sorokiniana from infected barley seed. Phosphon-D inhibited growth of seven fungi by 50% at concentrations less than 300 mg/L. Since the isoprenoid pathway occurs in a wide range of organisms and generates many metabolically important compounds it is suggested that commercially available chemicals which inhibit this pathway, whether they be used as herbicides, plant growth regulators, insecticides, fungicides, etc., may be broad-spectrum biocides.
Glomus epigaeus sp.nov., a useful fungus for vesicular–arbuscular mycorrhizal research
Authors: Daniels Barbara A. , Trappe James M.
Published: November 2007

A new endomycorrhizal species, Glomus epigaeus, produces abundant chlamydospores in sporocarps on the soil surface. This species has been maintained for more than 1 year in pot culture on various hosts and produces 8–15 sporocarps monthly from each pot. A simple technique of shaking sporocarps in water with broken glass chips is described for the separation of spores from sporocarps.The epigeous habit, narrow, thin-walled, inserted hyphal attachment, and bright yellow to yellow–brown wall color in transmitted light separate G. epigaeus from Glomus macrocarpus, which normally does not fruit epigeously and has a much broader, thick-walled, noninserted hyphal attachment and brown wall color in transmitted light.
The influence of pH on kinetic parameters of coleoptile phosphoenolpyruvate carboxylase. Relationship to auxin-stimulated dark fixation
Authors: Smith Ceredwyn , Doo Ahmed , Bown Alan W.
Published: November 2007

In vitro phosphoenolpyruvate (PEP) carboxylase activity from Avena coleoptile tissue was investigated over a range of pH values which include cytosol pH values. Increasing the pH from 7.0 to 7.5 increased optimal PEP carboxylase activity (Vmax) by over 100%. In the presence of rate-limiting 0.07 mM PEP, noncompetitive inhibition by 0.1 mM malate decreased from 80% at pH 7.1 to 50% at pH 7.5. The Km for PEP was not influenced by malate, but as the pH was increased from 7.1 to 7.5, the Km decreased from 0.16 to 0.08 mM. Over the same pH rise, the KI for malate inhibition increased from 0.04 mM to 0.09 mM. Fusicoccin had no detectable influence on enzymic activity. These results are discussed in relation to the stimulation of H+ excretion and dark CO2 fixation by indoleacetic acid and fusicoccin. The data indicate that any increase in cytosol pH, resulting from H+ excretion, would stimulate PEP carboxylase activity by promoting catalytic efficiency and binding affinity for PEP and by reducing the binding affinity for the inhibitor malate.
A new species of Spiniferomonas (Chrysophyceae) from an Alberta lake
Authors: Green Roderick B.
Published: November 2007

Spiniferomonas andersonii sp.nov. (Chrysophyceae) is described from Marjorie Lake, Alberta, Canada. The cell is distinguished by the number, position, and basal characteristics of the spines. The present distribution of Spiniferomonas based on electron microscope observations is also given.
Activités physiologiques de l'ochracine, synthétisée par Septoria nodorum, sur la croissance de plantules de riz et sur la synthèse ‘de novo’ des alpha-amylases par les couches à aleurone du caryopse de blé. Interaction avec l'acide gibbérellique
Authors: Touraud G. , Bousquet J. F.
Published: November 2007

Ochracine was isolated from culture filtrates of Septoria nodorum Berk. (Berk.), a pathogenic fungus of wheat. At concentrations ranging from 25 μg/mL it inhibited the growth of wheat and rice seedlings and the 'de novo' synthesis of α-amylases by the aleurone layers of wheat. These effects were not reversed by increased concentrations of gibberellic acid.Between 2.5 and 10 μg/mL, ochracine exhibited a synergistic effect with exogenous gibberellic acid on the same physiological phenomena. For these last concentrations, the results suggest an increased sensitivity of rice seedlings and wheat aleurone layers to exogenous gibberellic acid as a result of changes in tissue permeability.
Eutypella parasitica: ascospore germination and mycelial growth
Authors: Johnson David W. , Kuntz James E.
Published: November 2007

Ascospore germination of Eutypella parasitica Dav. and Lor. occurred over a temperature range of 12 to 38 °C. Over 90% of the spores which failed to germinate at lower temperatures germinated within 24 h when placed at 24 °C. Percent germination of ascospores varied in the presence of sugar maple and red maple tissue extracts. Germination was best in the presence of outer bark, sapwood, and leaf tissue of sugar maple and red maple and was poorest in the presence of fresh inner bark tissue excised from red maple. Germ-tube development also varied with type of tissue and treatment of tissue. Long, slender, branching germ tubes developed from spores in the presence of nonsterile leaf, bark, and sapwood, whereas short, thick germ tubes developed in the presence of sterilized leaf tissue and sterilized red maple bark. Age of wounded tissue also influenced percent germination of ascospores. Generally germination was higher when pH of these tissues was greater than 5.6. Mycelial growth was best at 29 °C. Growth rate was influenced by type of medium. Both sugar maple and red maple bark incorporated into agar media had a significant inhibitory effect on diameter growth of the fungus when compared with growth on nonamended media.
Sieve tube longevity in white ash (Fraxinus americana) studied with a new histochemical test for the identification of sugar
Authors: Zamski E. , Zimmermann M. H.
Published: November 2007

A histochemical test for functioning sieve tubes, based on the 5-diazouracil sugar reaction, has been used to identify functioning sieve tubes in Fraxinus americana L. The plant material was lyophilized, treated with the reagent, and sectioned in a cryostat. Before the resumption of cambial activity, when buds are still closed (late April – early May), starch grains of the storage tissues in bark and wood disappear and rays, cambrium, and phloem are loaded with sugars. In early spring, sugars begin to accumulate in last year's sieve tubes, especially in those which had not been fully differentiated in the previous active season and those which were functioning but had formed toward the end of the active season. Girdling experiments, carried out during May, showed that translocation in the phloem does occur, to some extent, during the period when the buds develop and the young leaves grow. The reactivated sieve tubes provide the channel of translocation to developing buds for sugars, formed of the dissolution of starch grains. The first early-phloem sieve tubes are formed at the end of May and loaded with sugars during June. There seems to be a short period of simultaneous import into young leaves via reactivated phloem and export via new phloem. After this, last year's sieve tubes are crushed. A noticeable pressure flow does not appear in the main stem until mid-June.
Mass transfer and 14C translocation in detached maize leaves
Authors: Keith B.
Published: November 2007

Translocation of photoassimilates was studied in detached maize leaves. When 14CO2 was pulse fed to either apical or basal halves of uniformly illuminated, freshly detached leaves, 14C translocation was strongly basipetal. If halves of leaves were predarkened and then 14CO2 supplied to the illuminated half, the darkened half acted as a sink and 14C photosynthate was translocated acropetally, although the amount was still considerably less than that translocated basipetally. Under these experimental conditions it took slightly less than 2 h of predarkening for the apical half to develop into a sink, whereas there was no such lag period for the basal half. Dry weight changes under steady-state photosynthetic conditions, however, indicate that there is no difference between the percent of dry matter translocated basipetally or acropetally, when either the apical or basal half of a leaf is illuminated and the other half darkened. This difference between translocation of 14C under nonsteady-state pulse feeding and transfer of dry matter under steady-state photosynthesis suggests that part of 14C supplied to freshly darkened leaves, though available for basipetal translocation, is not available for acropetal translocation. Translocation in uniformly darkened leaves is weakly basipetal.
Acid phosphatases of Ipomoea sp. cultured in vitro. 1. Influence of pH and inorganic phosphate on the formation of phosphatases
Authors: Zink M. W. , Veliky I. A.
Published: November 2007

The levels and the developmental patterns of the two acid phosphatases in Ipomoea sp. (morning glory) were influenced by the pH of the medium and whether the cultures were grown in fermentors or shake flasks. The two enzymes, which appeared in the culture medium, in the soluble fraction, and in the particulate fraction, were derepressed when suspension cultures were grown in a medium containing low concentrations of inorganic phosphate. The addition of up to 4 μmol of phosphate per millilitre to cells grown for 4 days on low phosphate did not repress the synthesis of the enzymes. However, the addition of excess phosphate resulted in a temporary cessation of phosphatase synthesis. Inorganic phosphate appeared to be only one of several factors controlling the levels of the enzymes.
Ramakrishnania, a new genus of Uredinales from southern India
Authors: Ramachar P. , Bhagyanarayana G.
Published: November 2007

Ramakrishnania is described as a new genus of rust fungi with R. ixorae n.sp as the type species. Distinct features of this genus are the indeterminate growth of the basal cell and the formation of two-celled puccinioid teliospores on septate simple pedicels bilaterally on the elongating basal cell.
Cyclical cell length changes in wood in relation to storied structure and interlocked grain
Authors: Krawczyszyn J. , Romberger J. A.
Published: November 2007

Interlocked grain can result from migration of a succession of left (S) and right (Z) orientational domains along the cambium. This grain pattern occurs both in species having nonstoried and those having storied cambium. In storied cambia, storey height being fixed, geometry requires that cambial fusiform initial cells undergo cyclical length changes in phase with cyclical inclination changes, e.g., a 4% length increase for a 16° inclination. We can expect the length changes to be detectable in wood if vessel member length reflects fusiform initial cell length and if the absolute amount of intrusive growth during differentiation of fibers is nearly invariant. Measurements of cells from maximum S, maximum Z, and axially aligned grain (I) sites along a radius in Entandrophragma cyclindricum and E. utile wood (storied) revealed clearly cyclical length changes in vessel members, parenchyma strands, and xylem fibers. Measurements in Nyssa sylvatica and Platanus acerifolia (nonstoried) revealed no such changes. Hence in species having storied cambium, cyclical changes in length of wood cells can accompany the slow endogenous rhythm manifested by interlocked grain. This is true because intrusive growth in these species, though extensive, does not obi iterate effects of small differences in cambial initial cell length.
Additional chromosome numbers and meiotic behaviour in tropical African grasses from western Zaïre
Authors: Dujardin Michel
Published: November 2007

Chromosome numbers are reported for 88 accessions of grasses from western Zaïre belonging to 31 genera and 65 species. First chromosome counts are reported for the genera Paratheria, Robynsiochloa, and Ystia and for the following species: Phragmites mauritianus, Sporobolus congoensis, Sporobolus sanguineus, Brachiaria kotschyana. Digitaria polybotrya, Entolasia oliracea, Panicum brazzavillense, Panicum spongiosum, Paratheria prostrata, Setaria thollonii, Andropogon brazzae, Andropogon patris, Robynsiochloa purpurascens, Schizachyrium platyphyllutn, Schizachyrium thollonii, and Ystia stagnina. Chromosome numbers that differ from previously reported records are given for Sporobolus festivus, Digitaria diagonalis var. hirsuta, Digitaria longiflora, Panicum griffonii, Panicum sadinii, and Rhynchelytrum repens.
The genus Elymus in Canada—Bowden's generic concept and key reappraised and relectotypification of E. canadensis
Authors: Baum Bernard R.
Published: November 2007

Bowden's (Bowden, W. M. 1964. Can. J. Bot. 42: 547–601) Elymus treatment for Canada has been emended on the following aspects: (1) Additional characters have been taken from micromorphology of the lodicules of species closely resembling each other to achieve better identification. (2) Some characters have been redefined and a new identification key has been constructed. (3) The species have been reclassified into several genera; these are Elymus, Leymus, × Elyleymus (new hybrid genus), Terrellia, × Terrelymus (new hybrid genus), Asperella, Aneurolepidium, and Psathyrostachys.
Metasequoia milleri n.sp., anatomically preserved pollen cones from the Middle Eocene (Allenby Formation) of British Columbia
Authors: Rothwell Gar W. , Basinger James F.
Published: November 2007

The discovery of well preserved, permineralized plant remains in Eocene sediments near Princeton, British Columbia, provides an opportunity to describe Metasequoia milleri, a new species of taxodiaceous pollen cone. Individual specimens are up to 3.0 mm long and 2.9 mm in diameter and are subtended by a vegetative zone of scale-like leaves. Approximately 30 microsporophylls are attached to the axis, and each bears three ovoid pollen sacs. The distal-most subtending leaves imbricate and enclose the fertile region. Pollen is ovoid to subspheroidal with an erect, protruding leptoma. Grains measure 19–27 μn in diameter and have verrucate exine ornamentation with numerous orbicules. These fossils show that pollen cones anatomically similar to those of extant Metasequoia glyptostroboides were present as early as Middle Eocene time.
Effets physiologiques de l'atrazine à doses sublétales sur Lemna minor L. IV. Influence sur la composition lipidique
Authors: Grenier G. , Marier J. P. , Beaumont G.
Published: November 2007

The lipids and the fatty acids of duck weed (Lemna minor L.), cultivated aseptically during 5, 10, or 15 days in mineral solution containing sublethal concentrations of atrazine (0.05 to 0.75 ppm), were analysed by thin-layer and gas–liquid chromatography. All concentrations of atrazine used, independently of age of plants, increased the total fatty acid content, except for 5-day plants at 0.50 and 0.75 ppm atrazine where a decrease in total fatty acids was observed. α-Linolenic acid content increased while linoleic acid content decreased. Sublethal concentrations of atrazine increased the percentage of monogalactosyldiacylglycerol compared with total phospholipids and total neutral lipids. Monogalactosyldiacylglycerol was the main lipid involved in the α-linolenic acid increase observed in the total fatty acids. The increase in α-linolenic acid and in monogalactosyldiacylglycerol in the presence of sublethal concentrations of atrazine is an indication that these treatments maintain intact and fully functional chloroplast membranes.
The root endodermis in Ranunculus acris. I. Structure and ontogeny
Authors: Scott M. G. , Peterson R. L.
Published: November 2007

The root endodermis in Ranunculus acris was investigated using light and transmission electron microscopy to obtain a more complete picture of endodermal development in a dicotyledonous species. Following the formation of a lateral bulge in anticlinal walls of proendodermal cells, portions of the plasma membrane became tenaciously associated with the primary wall material. The plasma membrane in the zone of the Casparian band appeared extremely electron dense and displayed a distinct tripartite organization. Cytoplasm of primary stage endodermal cells contained Golgi bodies with associated vesicles, lipid-like droplets, and multivesicular bodies containing membrane-enclosed vesicles. Cellulose microfibrils in the radial walls of endodermal cells became impregnated with an osmiophilic substance possibly through the incorporation of paramural bodies at a ledge-like invagination of the plasma membrane on either side of the Casparian strip. It is proposed that the intense organelle activity in the vicinity of the Casparian strip could signify an early stage of suberin lamellae synthesis. Between 8 and 10 suberin lamellae were laid down on radial and tangential walls of those endodermal cells which underwent secondary development, with the heaviest deposition occurring in the region of the Casparian strip. The parallel orientation of the suberin lamellae was frequently disrupted by electron-dense 'platelets' and small granules. A fibrillar suberin-like material was found in dilated cisternae of endoplasmic reticulum located adjacent to areas of deposition. Nuclei, membranous configurations, mitochondria, plastids, and other cytoplasmic organelles were found to persist in tertiary stage endodermal cells. Histochemistry and SEM showed that the mature endodermal wall complex of field-grown plants was comprised of alternating bands of cellulose, lignin, and possibly, suberin.
The root endodermis in Ranunculus acris. II. Histochemistry of the endodermis and the synthesis of phenolic compounds in roots
Authors: Scott M. G. , Peterson R. L.
Published: November 2007

Results of histochemical tests performed on fresh root tissue of Ranunculus acris provide the following information on the chemical nature of the root endodermis: (i) the Casparian strip is impregnated with lipid and possibly lignin, (ii) the suberin lamellae stain positively for lipid and phenols with free hydroxyl groups, and (iii) the tertiary wall contains alternating bands of lignin and cellulose.At the ultrastructural level, phenolic 'globules' present in vacuoles of adjacent cortical cells increase in size by accretion of flocculent material and the addition of dispersed granular material through the apparent fusion of smaller vacuoles with the large central vacuole. Globules adhering to fragments of the tonoplast membrane are clearly seen with the SEM.The ferric chloride test for catechol-type phenols at the TEM level proved useful in categorizing phenolic compounds present in intercellular spaces, in walls and vacuoles of cortical cells, surrounding starch grains in amyloplasts, and in the cytoplasm of endodermal cells. Prominent plastids containing large deposits of lipid, osmiophilic material, thylakoid membranes, and starch are seen to be a major constituent of cytoplasm in endodermal and cortical cells.
Oxydation peroxydative de l'acide indolyl-1 acétique par une peroxydase de Raifort. Influence du pH
Authors: Chappet Annette , Deschamps-Mudry Martine , Job Dominique
Published: November 2007

Contrary to indole-3-acetic acid, indole-1-acetic acid (I1AA) may be destroyed by horseradish isoperoxydase ‘c’ (HRPc) only in the presence of hydrogen peroxide. This peroxidative reaction depends on the enzyme and H2O2 concentrations and on the medium acidity. By calculation of the binding equilibrium constant of the HRPc–I1AA complex for different pH, it appears that enzyme affinity for this substrate is higher for the more acidic tested pH.
Fine structure of megagametophyte development in Zea mays
Authors: Russell Scott D.
Published: November 2007

Polygonum-type embryo sac development was examined in Zea mays with light, fluorescence, and electron microscopy. Megasporocyte polarity is expressed in organelle distribution, aniline blue wall fluorescence, and chalazal location of plasmodesmata. In the meiotic cytoplasm concurrent with the sporophyte–gametophyte transition, ribosome concentrations are low, and membrane-bound organelles are simplified. The functional megaspore is the largest and most chalazal cell of the resultant triad or tetrad. Aniline blue fluorescence is intense in nonfunctional megaspore walls, whereas in the functional megaspore intensity decreases from the chalazal end to that in nucellar walls. Throughout functional megaspore and two-nucleate megagametophyte, ribosome concentrations, organelle numbers, and structural complexity increase. The transition from vegetative to reproductive gametophytic growth presumably follows this biosynthetic period. In the four-nucleate stage, a second phase of mitochondrial simplification coincides with the formation of an extensive lytic vacuole containing evidence of possible organelle and cytoplasmic membrane incorporation. Near the close of intensive lytic activity, compartmentalization of lytic areas contributes to creating a prominent vacuole in the central cell as synergids, egg, and antipodals differentiate.
High elevation vegetation of the Enchantment Lakes Basin, Washington
Authors: del Moral Roger
Published: November 2007

The vegetation of the Enchantment Lakes Basin, which is located at and above timberline on the slopes of Mount Stuart, Washington, was examined by classification and ordination methods. A vegetation map relates the 21 recognized community types to physiographic and topographic features. Vegetation was divided into plots with and without trees. The 11 forested communities include those dominated by Larix lyallii and Cassiope mertensiana on moist slopes, L. lyallii and Phyllodoce glanduliflora on steep north-facing slopes, Abies lasiocarpa and Vaccinium inyrtillus on low elevation, moist sites, and several communities dominated by Pinus albicaulis on dry, exposed slopes. The 10 alpine communities include dry fell-fields dominated by Lupinus lepidus with a variety of forbs, communities dominated by Cassiope mertensiana and Phyllodoce glanduliflora and by P. empetriformis, and lush and wet meadow communities dominated by Lupinus polyphyllus and Carex nigricans. These communities are related to those identified by other workers in the Pacific Northwest. Keys to the vegetation of this area are presented. Indirect gradient analysis using reciprocal averaging revealed both vegetation and species patterns. In the subalpine, moisture appears to be the dominant operational gradient, while inferred temperature is a secondary factor. In the alpine vegetation, a combined gradient of moisture and exposure is indicated by reciprocal averaging. Special ordinations derived from reciprocal averaging reflect these interpretations and identify indicator species for particular habitats in both subalpine and alpine. The patterns are summarized with a mosaic diagram. The use of multivariate methods provided means to summarize primary survey data quickly and efficiently. The pattterns thus revealed are comparable to other studies in the Pacific Northwest and thus engender confidence in the use of indirect gradient analysis as a valuable tool for primary survey in these ecosystems. A vegetation map, keys to vegetation types, community and species patterns, and the relationship between classifications and ordinations emerged from this study.