bluuebunny/crossref_metadata_2025 huggingface dataset:
Fatal attraction: carnivorous plants roll out the red carpet to lure insects
Authors: Schaefer H. Martin , Ruxton Graeme D
Published: January 2008

We provide the first experimental test of the hypothesis that the coloration of carnivorous plants can act as a signal to lure insects and thus enhance capture rates. An experimental approach was needed to separate effects of the visual appearance of plants from those of traits that may correlate with appearance and also affect capture rates. We compared insect capture rates of pitcher plants with artificially coloured red and green pitchers in a paired design, and found that plants with red pitchers captured significantly more flying insects. Thus, we present the first experimental evidence of visual signalling in carnivorous plants. Further, it has previously been suggested that carnivorous plants use contrasting stripes or UV marks on their pitchers to lure insects; our results emphasize that insect traps do not need to sport contrasting colours to be attractive; it might be sufficient to be different from the background.
Microgravity/microscale double-helical fluid containment
Authors: May Heather-Jean , Lowry Brian J
Published: January 2008

Double-helical containment is a novel approach to open containment in microgravity (or at microscale). In contrast to axisymmetric containers, there is no length restriction on properly designed double-helical containers. Use of a double helix permits drainage to zero volume, an uncommon feature in microgravity; near-complete drainage is a key feature for any practically useful container. The fact that double-helical containers are open and tubular makes possible a broad range of applications that rely on accessible fluids.

The double-helical fluid containment and the stability of such volumes are examined in detail. Helical supports permit filamentary containers of infinite extent, but only double-helical containers are stable down to zero volume. The base case of symmetric supports (separation angle 180°) is considered in terms of symmetric volumes as well as asymmetric helicatenoid volumes. The distinct symmetric and asymmetric cases are then related by perturbing the angle of separation between the supports. The helicatenoid volumes may combine to form a dual helicatenoid volume. The dual helicatenoid is interesting in that it permits multiphase tube-like geometries.

Double-helical behaviours such as drainability are found to vanish at a critical separation angle 246.48°. With larger separation angles, double-helical containers behave like single-helical containers (360°), due to the dominance of the longer-span interface. A second shift in behaviour occurs at the limit angle 209.12°, where the regions of stability including the cylinder and the helicatenoids become more connected. The common structures of DNA appear to coincide with the limiting geometry at 209.12°. The most robust double-helical containers are therefore those with separation angles between approximately 210° and 240°. Experimental results roughly verify the volume maximum for near-symmetry, and more importantly verify stability to zero volume.
Free and forced motion in an asymmetric liquid-column oscillator
Authors: Smith M.J , Kobine J.J , Davidson F.A
Published: January 2008

The results of a combined theoretical, numerical and experimental study of liquid oscillations in an asymmetric U-tube are presented. The configuration under investigation is analogous to that of the tuned liquid-column damper used to suppress oscillatory motion in large semi-supported structures. The liquid motion is described by a second-order ordinary differential equation that is nonlinear when the widths of the two vertical columns are unequal. It is shown that this asymmetry can be used as a tuning parameter to determine the natural frequency of free oscillations in the system, in addition to the known tuning effect of the connecting chamber height. The effects of viscous damping and periodic forcing are considered, leading to a description of probable initial and long-term resonance behaviour in a practical asymmetric device.
A quantitative test of the relationship between parasite dose and infection probability across different host–parasite combinations
Authors: Ben-Ami Frida , Regoes Roland R , Ebert Dieter
Published: January 2008

Epidemiological models generally assume that the number of susceptible individuals that become infected within a unit of time depends on the density of the hosts and the concentration of parasites (i.e. mass-action principle). However, empirical studies have found significant deviations from this assumption due to biotic and abiotic factors, such as seasonality, the spatial structure of the host population and host heterogeneity with respect to immunity and susceptibility. In this paper, we examine the effect of the dose level of the bacterial endoparasite
Pasteuria ramosa
on the infection rate of its host, the water flea
Daphnia magna
. Using seven host clones and two parasite isolates, we measure the fraction of infected hosts after exposure to eight different parasite doses to determine whether there is variation in the infection process across different host clone–parasite isolate combinations. In five combinations, a pronounced dose-dependent infection pattern was found. Using a likelihood approach, we compare the infection data of these five combinations to the fit of three mathematical models: a mass-action model, a parasite antagonism model (i.e. an increase in the parasite dose leads to an under-proportionate increase in the infection rate per host) and a heterogeneous host model. We found that the host heterogeneity model, in which we assumed the existence of non-inherited phenotypic differences in host susceptibilities to the parasite, provides the best fit. Our analysis suggests that among 5 out of the 14 host clone–parasite isolate combinations that resulted in appreciable infections, non-genetic host heterogeneity plays an important role.
Implications of activity-dependent neurotransmitter–receptor matching
Authors: Spitzer Nicholas C , Borodinsky Laura N
Published: January 2008

Electrical activity has numerous roles in early neuronal development. Calcium transients generated at low frequencies regulate neural induction and neuronal proliferation, migration and differentiation. Recent work demonstrates that these signals participate in specification of the transmitters expressed in different classes of neurons. Matching of postsynaptic receptor expression with the novel expression of transmitters ensues. These findings have intriguing implications for development, mature function and evolution of the nervous system.
The elk PRNP codon 132 polymorphism controls cervid and scrapie prion propagation
Authors: Green Kristi M. , Browning Shawn R. , Seward Tanya S. , Jewell Jean E. , Ross Dana L. , Green Michael A. , Williams Elizabeth S. , Hoover Edward A. , Telling Glenn C.
Published: January 2008

The elk prion protein gene (PRNP) encodes either methionine (M) or leucine (L) at codon 132, the L132 allele apparently affording protection against chronic wasting disease (CWD). The corresponding human codon 129 polymorphism influences the host range of bovine spongiform encephalopathy (BSE) prions. To fully address the influence of this cervid polymorphism on CWD pathogenesis, we created transgenic (Tg) mice expressing cervid PrPC with L at residue 132, referred to as CerPrPC-L132, and compared the transmissibility of CWD prions from elk of defined PRNP genotypes, namely homozygous M/M or L/L or heterozygous M/L, in these Tg mice with previously described Tg mice expressing CerPrPC-M132, referred to as Tg(CerPrP) mice. While Tg(CerPrP) mice were consistently susceptible to CWD prions from elk of all three genotypes, Tg(CerPrP-L132) mice uniformly failed to develop disease following challenge with CWD prions. In contrast, SSBP/1 sheep scrapie prions transmitted efficiently to both Tg(CerPrP) and Tg(CerPrP-L132) mice. Our findings suggest that the elk 132 polymorphism controls prion susceptibility at the level of prion strain selection and that cervid PrP L132 severely restricts propagation of CWD prions. We speculate that the L132 polymorphism results in less efficient conversion of CerPrPC-L132 by CWD prions, an effect that is overcome by the SSBP/1 strain. Our studies show the accumulation of subclinical levels of CerPrPSc in aged asymptomatic CWD-inoculated Tg(CerPrP-L132) mice and also suggests the establishment of a latent infection state in apparently healthy elk expressing this seemingly protective allele.
Deletion of the SH gene from avian metapneumovirus has a greater impact on virus production and immunogenicity in turkeys than deletion of the G gene or M2-2 open reading frame
Authors: Ling Roger , Sinkovic Sabrina , Toquin Didier , Guionie Olivier , Eterradossi Nicolas , Easton Andrew J.
Published: January 2008

Subgroup A avian metapneumoviruses lacking either the SH or G gene or the M2-2 open reading frame were generated by using a reverse-genetics approach. The growth properties of these viruses were studied in vitro and in vivo in their natural host. Deletion of the SH gene alone resulted in the generation of a syncytial-plaque phenotype and this was reversed by the introduction of the SH gene from a subgroup B, but not a subgroup C, virus. Infected turkeys were assessed for antibody production and the presence of viral genomic RNA in tracheal swabs. The virus with a deleted SH gene also showed the greatest impairment of replication both in cell culture and in infected turkeys. This contrasts with the situation with other pneumoviruses in culture and in model animals, where deletion of the SH gene results in little effect upon viral yield and a good antibody response. Replication of the G- and M2-2-deleted viruses was impaired more severely in turkeys than in cell culture, with only some animals showing evidence of virus growth and antibody production. There was no correlation between virus replication and antibody response, suggesting that replication sites other than the trachea may be important for induction of antibody responses.
GP64 of group I nucleopolyhedroviruses cannot readily rescue infectivity of group II f-null nucleopolyhedroviruses
Authors: Westenberg Marcel , Vlak Just M.
Published: January 2008

The genus Nucleopolyhedrovirus (NPV) of the family Baculoviridae can be subdivided phylogenetically into two groups. The same division can be made on the basis of their budded virus (BV) envelope fusion protein. Group I NPVs are characterized by the presence of a GP64-like major envelope fusion protein, which is involved in viral attachment and the fusion of virus and cell membrane, and is required for budding of progeny nucleocapsids. Group II NPVs have an envelope fusion protein unrelated to GP64, named F. In contrast to GP64, F proteins are found in all baculoviruses, but they are not functional as envelope fusion proteins in group I NPVs. Autographa californica multiple NPV (AcMNPV) lacking GP64 can be pseudotyped by the F protein of Spodoptera exigua multiple NPV (SeMNPV), suggesting that F proteins are functionally analogous to GP64. GP64 homologues are thought to have been acquired by group I NPVs during evolution, thereby giving these viruses a selective advantage and obviating the need for a functional F protein. To address this supposition experimentally, attempts were made to pseudotype a group II NPV, SeMNPV, with GP64. Transfection of an f-null SeMNPV bacmid into Se301 cells did not result in the production of infectious BVs. This defect was rescued by insertion of SeMNPV f, but not by insertion of AcMNPV gp64. This suggests that the functional analogy between GP64 and F is not readily reciprocal and that F proteins from group II NPVs may provide additional functions in BV formation that are lacking in the GP64 type of fusion protein.
Comparison of the genome sequences of non-pathogenic and pathogenic African swine fever virus isolates
Authors: Chapman David A. G. , Tcherepanov Vasily , Upton Chris , Dixon Linda K.
Published: January 2008

The genomic coding sequences, apart from the inverted terminal repeats and cross-links, have been determined for two African swine fever virus (ASFV) isolates from the same virus genotype, a non-pathogenic isolate from Portugal, OURT88/3, and a highly pathogenic isolate from West Africa, Benin 97/1. These genome sequences were annotated and compared with that of a tissue culture-adapted isolate, BA71V. The genomes range in length between 170 and 182 kbp and encode between 151 and 157 open reading frames (ORFs). Compared to the Benin 97/1 isolate, the OURT88/3 and BA71V isolates have deletions of 8–10 kbp that encode six copies of the multigene family (MGF) 360 and either one MGF 505/530 copy in the BA71V or two copies in the OURT88/3 isolate. The BA71V isolate has a deletion, close to the right end of the genome, of 3 kbp compared with the other isolates. The five ORFs in this region include an additional copy of an ORF similar to that encoding the p22 virus structural protein. The OURT88/3 isolate has interruptions in ORFs that encode a CD2-like and a C-type lectin protein. Variation between the genomes is observed in the number of copies of five different MGFs. The 109 non-duplicated ORFs conserved in the three genomes encode proteins involved in virus replication, virus assembly and modulation of the host's defences. These results provide information concerning the genetic variability of African swine fever virus isolates that differ in pathogenicity.
Increased blood–brain barrier permeability is not a primary determinant for lethality of West Nile virus infection in rodents
Authors: Morrey John D. , Olsen Aaron L. , Siddharthan Venkatraman , Motter Neil E. , Wang Hong , Taro Brandon S. , Chen Dong , Ruffner Duane , Hall Jeffery O.
Published: January 2008

Blood–brain barrier (BBB) permeability was evaluated in mice and hamsters infected with West Nile virus (WNV, flavivirus) as compared to those infected with Semliki Forest (alphavirus) and Banzi (flavivirus) viruses. BBB permeability was determined by measurement of fluorescence in brain homogenates or cerebrospinal fluid (CSF) after intraperitoneal (i.p.) injection of sodium fluorescein, by macroscopic examination of brains after i.p. injection of Evans blue, or by measurement of total protein in CSF compared to serum. Lethal infection of BALB/c mice with Semliki Forest virus and Banzi virus caused the brain : serum fluorescence ratios to increase from a baseline of 2–4 % to as high as 11 and 15 %, respectively. Lethal infection of BALB/c mice with WNV did not increase BBB permeability. When C57BL/6 mice were used, BBB permeability was increased in some, but not all, of the WNV-infected animals. A procedure was developed to measure BBB permeability in live WNV-infected hamsters by comparing the fluorescence in the CSF, aspirated from the cisterna magnum, with the fluorescence in the serum. Despite a time-dependent tendency towards increased BBB permeability in some WNV-infected hamsters, the highest BBB permeability values did not correlate with mortality. These data indicated that a measurable increase in BBB permeability was not a primary determinant for lethality of WNV infection in rodents. The lack of a consistent increase in BBB permeability in WNV-infected rodents has implications for the understanding of viral entry, viral pathogenesis and accessibility of the CNS of rodents to drugs or effector molecules.
Immune-response profiles induced by human immunodeficiency virus type 1 vaccine DNA, protein or mixed-modality immunization: increased protection from pathogenic simian–human immunodeficiency virus viraemia with protein/DNA combination
Authors: Koopman Gerrit , Mortier Daniella , Hofman Sam , Mathy Nathalie , Koutsoukos Marguerite , Ertl Peter , Overend Phil , van Wely Cathy , Thomsen Lindy L. , Wahren Britta , Voss Gerald , Heeney Jonathan L.
Published: January 2008

Current data suggest that prophylactic human immunodeficiency virus type 1 (HIV) vaccines will be most efficacious if they elicit a combination of adaptive humoral and T-cell responses. Here, we explored the use of different vaccine strategies in heterologous prime–boost regimes and evaluated the breadth and nature of immune responses in rhesus monkeys induced by epidermally delivered plasmid DNA or recombinant HIV proteins formulated in the AS02A adjuvant system. These immunogens were administered alone or as either prime or boost in mixed-modality regimes. DNA immunization alone induced cell-mediated immune (CMI) responses, with a strong bias towards Th1-type cytokines, and no detectable antibodies to the vaccine antigens. Whenever adjuvanted protein was used as a vaccine, either alone or in a regime combined with DNA, high-titre antibody responses to all vaccine antigens were detected in addition to strong Th1- and Th2-type CMI responses. As the vaccine antigens included HIV-1 Env, Nef and Tat, as well as simian immunodeficiency virus (SIV)mac239 Nef, the animals were subsequently exposed to a heterologous, pathogenic simian–human immunodeficiency virus (SHIV)89.6p challenge. Protection against sustained high virus load was observed to some degree in all vaccinated groups. Suppression of virus replication to levels below detection was observed most frequently in the group immunized with protein followed by DNA immunization, and similarly in the group immunized with DNA alone. Interestingly, control of virus replication was associated with increased SIV Nef- and Gag-specific gamma interferon responses observed immediately following challenge.
Expression of heterologous genes in oncolytic adenoviruses using picornaviral 2A sequences that trigger ribosome skipping
Authors: Funston Garth M. , Kallioinen Susanna E. , de Felipe Pablo , Ryan Martin D. , Iggo Richard D.
Published: January 2008

Insertion of picornaviral 2A sequences into mRNAs causes ribosomes to skip formation of a peptide bond at the junction of the 2A and downstream sequences, leading to the production of two proteins from a single open reading frame. Adenoviral protein IX is a minor capsid protein that has been used to display foreign peptides on the surface of the capsid. We have used 2A sequences from the foot-and-mouth disease virus (FMDV) and porcine teschovirus 1 (PTV-1) to express protein IX (pIX) and green fluorescent protein (GFP) from pIX–2A–GFP fusion genes in an oncolytic virus derived from human adenovirus 5. GFP was efficiently expressed by constructs containing either 2A sequence. Peptide bond skipping was more efficient with the 58 aa FMDV sequence than with the 22 aa PTV-1 2A sequence, but the virus with the FMDV 2A sequence showed a reduction in plaque size, cytopathic effect, viral burst size and capsid stability. We conclude that ribosome skipping induced by 2A sequences is an effective strategy to express heterologous genes in adenoviruses; however, careful selection or optimization of the 2A sequence may be required if protein IX is used as the fusion partner.
In situ hybridization to detect bandicoot papillomatosis carcinomatosis virus type 1 in biopsies from endangered western barred bandicoots (Perameles bougainville)
Authors: Bennett Mark D. , Woolford Lucy , O'Hara Amanda J. , Warren Kristin S. , Nicholls Philip K.
Published: January 2008

The western barred bandicoot (Perameles bougainville) is an endangered Australian marsupial species in which a papillomatosis and carcinomatosis syndrome occurs. Bandicoot papillomatosis carcinomatosis virus type 1 (BPCV1) is associated with the lesions of this progressively debilitating syndrome. Five digoxigenin-labelled DNA probes were generated for in situ hybridization (ISH) and the technique was optimized and performed on formalin-fixed paraffin-embedded (FFPE) biopsies. Staining of keratinocyte and sebocyte nuclei within lesions was achieved with all five probes. The sensitivity of ISH (76.9 %) surpassed that of PCR (30.8 %) for FFPE samples. The sensitivity of ISH varied from 81 % (papillomas) and 70 % (carcinoma in situ) to 29 % (squamous cell carcinomas). The specificity of the test was confirmed using an irrelevant probe and papillomas from other species. These results strengthen the association between BPCV1 and the western barred bandicoot papillomatosis and carcinomatosis syndrome and give insight into the biology of the virus–host interaction.
Complete genomes of three subtype 6t isolates and analysis of many novel hepatitis C virus variants within genotype 6
Authors: Lu Ling , Murphy Donald , Li Chunhua , Liu Shuanghu , Xia Xueshan , Pham Phiet Hoang , Jin Yuhuai , Hagedorn Curt H. , Abe Kenji
Published: January 2008

In this study, the complete genomic sequence was determined for three hepatitis C virus variants (VT21, TV241 and TV249) of genotype 6 that do not classify within the established subtypes. All three genomes were isolated from patients in Vietnam and sequenced using 100 μl of serum. They showed 91.4–93.6 % nucleotide similarities to each other but only 71.7–79.4 % similarities to 17 reference sequences representing subtypes 6a–6q and to isolates km41 and gz52557. VT21, TV241 and TV249 displayed genome lengths of 9407, 9460 and 9445 nt, respectively. All three isolates contained a single open reading frame of 9051 nt while the 5′UTRs and 3′UTRs were 324–338 nt and 32–71 nt, respectively. They shared common sizes with QC227/6o and QC216/6p isolates in all ten protein regions. Phylogenetic analyses demonstrated that VT21, TV241 and TV249 clustered independently and were assigned subtype 6t, following the recent designations of 6r and 6s. Analysis of partial genomic sequences available for genotype 6 variants revealed five additional subtype 6t isolates, all originating from Vietnam. This analysis revealed two additional groups of isolates, and at least seven novel variants analogous to km41 and gz52557 that group independently and do not classify within the subtypes 6a–6t. This suggests the existence of at least 11 additional subtypes for genotype 6. In addition, the existence of isolates showing genetic distances greater than those within subtypes, but lesser than those between subtypes, raises interesting questions regarding the classification of HCV.
Analysis of gene content in sweet potato chlorotic stunt virus RNA1 reveals the presence of the p22 RNA silencing suppressor in only a few isolates: implications for viral evolution and synergism
Authors: Cuellar Wilmer J. , Tairo Fred , Kreuze Jan F. , Valkonen Jari P. T.
Published: January 2008

Sweet potato chlorotic stunt virus (genus Crinivirus) belongs to the family Closteroviridae, members of which have a conserved overall genomic organization but are variable in gene content. In the bipartite criniviruses, heterogeneity is pronounced in the 3′-proximal region of RNA1, which in sweet potato chlorotic stuat virus (SPCSV) encodes two novel proteins, RNase3 (RNase III endonuclease) and p22 (RNA silencing suppressor). This study showed that two Ugandan SPCSV isolates contained the p22 gene, in contrast to three isolates of the East African strain from Tanzania and Peru and an isolate of the West African strain from Israel, which were missing a 767 nt fragment of RNA1 that included the p22 gene. Regardless of the presence of p22, all tested SPCSV isolates acted synergistically with potyvirus sweet potato feathery mottle virus (SPFMV; genus Potyvirus, family Potyviridae) in co-infected sweetpotato plants (Ipomoea batatas), which greatly enhanced SPFMV titres and caused severe sweetpotato virus disease (SPVD). Therefore, the results indicate that any efforts to engineer pathogen-derived RNA silencing-based resistance to SPCSV and SPVD in sweetpotato should not rely on p22 as the transgene. The data from this study demonstrate that isolates of this virus species can vary in the genes encoding RNA silencing suppressor proteins. This study also provides the first example of intraspecific variability in gene content of the family Closteroviridae and may be a new example of the recombination-mediated gene gain that is characteristic of virus evolution in this virus family.
Comparison of methods to identify significant proteinuria in pregnancy in the outpatient setting
Authors: Kyle PM , Fielder JN , Pullar B , Horwood LJ , Moore MP
Published: January 2008

The efficacy of the albumin/creatinine ratio (ACR) measurement in detection of significant proteinuria when performed in a high‐risk antenatal clinic was compared with automated dipstick, protein/creatinine ratio (PCR), and 24‐hour urine protein measurements. Both the ACR (DCA 2000) and PCR were strongly predictive for the presence or absence of significant proteinuria, with positive likelihood ratios (LRs) of 27.4 and 31.6 and negative LRs of 0.0 and 0.1, respectively. Both the ACR (DCA 2000) and PCR are effective tests for both identifying and excluding significant proteinuria in the outpatient setting. The ACR (DCA 2000) has the advantage of providing an immediate result.
Propagation and storage of vesicular–arbuscular mycorrhizal fungi isolated from Saskatchewan agricultural soils
Authors: Talukdar Narayan C. , Germida James J.
Published: January 2008

Factors affecting the propagation of vesicular–arbuscular mycorrhizal fungi (VAMF) Glomus clarum, Glomus mosseae, and Glomus versiforme isolated from Saskatchewan soils were assessed in growth-chamber studies. Initially, lentil (Lens esculenta L.), maize (Zea mays L.), and a sorghum (Sorghum bicolor (L.) Moench) and sudangrass (Sorghum sudanense (Piper) Hitch.) hybrid were inoculated with G. clarum and grown in 2 or 6 kg of soil–sand (1:1) substrate until maturity. All three crops supported growth and spore production by G. clarum, but the maize plant yielded the largest number of spores. The ability of G. clarum to produce large numbers of spores reflects either an inherent ability of this VAMF strain to sporulate or a favorable interaction (related to spore production) with a maize host crop. Twice as many G. clarum spores per gram of soil–sand substrate were obtained from 2-kg pots compared with 6-kg pots. Enhanced spore production in the smaller pots was related to poor plant growth and, apparently, nutrient stress. Plants grown in 2-kg pots were stunted, yielded less biomass, and exhibited severe symptoms of P and N deficiency. Monospecific cultures of G. clarum, G mosseae, and G. versiforme were produced using maize plants grown in 2-kg pots. Under these conditions the level of spore production was G. clarum > G. versiforme > G. mosseae. Storage of the VAMF inoculants at 7 °C, compared with 25 °C, enhanced spore viability. This was evident from a reduction in VAMF colonization and spore production in wheat (Triticum aestivum L.) and the sorghum–sudangrass hybrid plants inoculated with G. mosseae spores stored at 25 °C. Osmotic stress exerted on G. mosseae spores during density-gradient centrifugation had no effect on their viability. Key words: vesicular–arbuscular mycorrhizal fungi, Glomus spp., host crops, substrate mass, nutrient stress.
Genetics of mine invasions by Deschampsia cespitosa (Poaceae)
Authors: Bush Elizabeth J. , Barrett Spencer C. H.
Published: January 2008

Deschampsia cespitosa is a self-incompatible, tussock-forming, perennial grass with a scattered distribution in Ontario, primarily along the shores of the Great Lakes. In recent decades, D. cespitosa has colonized metal-contaminated sites in the mining regions of Sudbury and Cobalt. Isozyme variation in populations from contaminated and uncontaminated sites were compared to investigate the genetic consequences of mine invasion. Central Ontario populations are diploid (2n = 26); however, the complexity of electrophoretic patterns suggested that D. cespitosa is a diploidized tetraploid with considerable gene duplication. Innovative approaches were therefore required for quantitative assessment of isozyme variability within and among populations. Eighteen populations of D. cespitosa were assayed for variation at nine enzyme systems, representing 19 putative isozyme loci. Populations included eight from various uncontaminated habitats, five from mine sites around Sudbury, and five from Cobalt. Lower levels of diversity were evident in both Sudbury and Cobalt populations relative to uncontaminated populations. The results corroborated the prediction that colonization of contaminated habitats reduces levels of genetic variability, particularly where populations are recently established. Strong selection on mine sites will also compound stochastic loss of genetic diversity associated with colonization. The distribution of isozyme variation among populations of D. cespitosa was also used to infer colonization history. Cobalt and Sudbury populations were clearly differentiated by unique alleles at a number of enzyme systems, providing evidence for the independent origin of metal-tolerant populations in the two mining regions. Estimates of outcrossing frequency revealed no significant difference between a mine and an uncontaminated population; both populations exhibited high levels of outcrossing. Key words: colonization, mine invasion, genetic variation, Deschampsia cespitosa.
Diamines, guanidinoamines, and their hydroxy derivatives in seeds and seedlings of leguminous plants
Authors: Hamana Koei , Matsuzaki Shigeru
Published: January 2008

Two unusual amines corresponding to γ(3)-hydroxyagmatine and 2-hydroxyputrescine were detected in the mature seeds of vetch Vicia sativa, pea Pisum sativum, wisteria Wisteria floribunda, and red clover Trifolium pratense. These two amines were resistant to both acid hydrolysis and reduction with palladium – barium sulfate but were cleaved by periodate oxidation. The latter amine assigned as 2-hydroxyputrescine was produced by alkaline hydrolysis of the former amine, γ-hydroxyagmatine. This was metabolized by agmatine oxidase. Putrescine, cadaverine, and (or) agmatine levels increased, but the levels of the two hydroxyamines as well as methylagmatine remained unchanged during germination of 23 leguminous seeds. Key words: legume, seed, polyamine, hydroxy agmatine, hydroxyputrescine.
Le Phragmites australis au Québec: distribution géographique, nombres chromosomiques et reproduction
Authors: Gervais C. , Trahan R. , Moreno D. , Drolet A.-M.
Published: January 2008

A study of Phragmites australis (Cav.) Trin. ex Steud., the common reed, was conducted in Quebec between 1985 and 1991. Its present and former geographical distributions (before and after 1950) were established, the chromosome numbers of 52 individuals were determined, and various observations on the reproduction of this species by seed were made. The geographical distribution was outlined after consultation of 21 north-eastern american herbaria and upon in situ observations along roadsides in most parts of inhabited Québec. Concurrently, 77 representative populations were selected and visited in the summer and fall of 1985, allowing the observation of the degree of flower development, the frequency of seed setting, and the presence of smut, Claviceps microcephala (Wallr.) Tul. The chromosome numbers show a high degree of aneuploidy and vary between 2n = 42 and 59. The nordic populations tend to have a lower chromosome number and a faster flower development. In fact, for a given geographical area and date of collection, the flowers of the individuals with higher chromosome numbers are usually less developed. There is however a persistent problem with the evaluation of the chromosome number of a stand because of internal variations. Seed production is generally very low, but some stations, even nordic, are quite productive (up to 59.2% of flowers with seeds). The seeds are able to germinate under laboratory conditions, but it is not known yet if the plant can reproduce in this manner in the field. The seedlings develop slowly and seem to have poor competitiveness. Key words: Phragmites australis, distribution, chromosome numbers, reproduction, Quebec, weed.
Effect of urea fertilization on ectomycorrhizae of 20-year-old Tsugaheterophylla
Authors: Kernaghan Gavin , Berch Shannon , Carter Reid
Published: January 2008

Granular urea (46% N) was applied at rates of 224 and 448 kg N/ha to 4 × 4 m plots within at 20-year-old stand composed almost exclusively of western hemlock (Tsugaheterophylla (Raf.) Sarg.), located in the Mount Seymour Demonstration Forest, North Vancouver, British Columbia. Changes in the abundance of 10 mycorrhizal types (Cenococcumgeophilum Fr., Lactariusscrobiculatus (Fr.) Fr., Myceliumradicisatrovirens Melin, Thelephoraterrestris Fr., three Russula morphotypes, two unidentified basidiomycetes, and a mantleless morphotype resembling E-strain) were assessed using random soil cores taken at 0, 1, 3, 6, and 11 months after fertilization. On both treated and control plots, total number of fine roots and number of basidiomycetous mycorrhizae remained constant, while C. geophilum mycorrhizae decreased slightly and those lacking mantles increased. The observed changes were independent of fertilizer levels and the shifts in pH brought about by urea hydrolysis.
Seed-cone and pollen-cone production models for young black spruce seedling seed orchards: a first approximation
Authors: Caron G.-É.
Published: January 2008

Seed orchard managers wanting to predict potential seed-cone (Sc) and pollen-cone (Pc) production 1 year in advance of seed release and pollen dissemination need predictive models. The present study proposes the use of cone-crop models based on tree age in young black spruce (Piceamariana (Mill.) B.S.P.) orchards. Sc and Pc production was monitored from 1987 to 1993 in each of five seedling seed orchards. Some trees began bearing Sc and Pc by tree age 6. The relationships of Sc and Pc production with tree age were each represented by three sigmoid equations: one for light crop years, one for heavy crop years, and one for light plus heavy crop years. The rate of cone increase for heavy and light crop years differed for both Sc and Pc. Sigmoid equations representing heavy Sc and Pc crop years in orchards had the highest r2 (0.8462 and 0.9381, respectively) and the lowest standard error. Sigmoid model of heavy crop years with plantation data also had the highest r2 value (0.8066) and the lowest standard error. The rate of Sc and Pc increase versus tree age was higher for orchards than for plantations. To select the best of three sigmoid models, one must take into account the early buildup phase of cone production in young trees, the yearly fluctuation in cone crops, previous-year cone production, and environmental factors that can affect cone crops.
Interaction of nutrient-loaded black spruce seedlings with neighbouring vegetation in greenhouse environments
Authors: Malik Vikram , Timmer Victor R.
Published: January 2008

The interaction of newly planted, nutrient-loaded black spruce (Piceamariana (Mill.) B.S.P.) seedlings with naturally occurring vegetation was investigated for one growing season under greenhouse conditions using bioassays retrieved from a boreal mixedwood site. Nutrient-loaded seedlings were similar in height and biomass to conventionally fertilized seedlings at planting, but contained 43, 76, and 33% more tissue N, P, and K content due to higher nursery fertilization, which induced luxury consumption. Nutrient-loaded seedlings outperformed conventionally fertilized seedlings in respective height and biomass growth by 35 and 28% in herbicide-treated plots, and by 44 and 37% in untreated plots, resulting in a 27% reduction in neighbouring vegetation biomass by the end of the season. The loading treatments stimulated nutrient uptake after planting, although the depletion of preplant nutrient reserves was greater. A significant negative correlation was observed between tree and weed biomass accumulation. Slope differences indicated that loaded trees were less sensitive to neighbouring vegetation than conventionally fertilized trees. The enhanced competitive ability of loaded seedlings against naturally occurring vegetation was probably due to the translocation of more nutrients to actively growing parts from reserves built up during the nursery preconditioning phase.
THERMOELECTRIC EFFECTS IN MESOSCOPIC SUPERCONDUCTOR/FERROMAGNETIC JUNCTIONS
Authors: AWAD ALLA ATTIA A. , PHILLIPS ADEL H.
Published: January 2008

Spin transport properties of a mesoscopic superconductor/ferromagnetic (S/F) junctions of a quantum device are investigated. The thermoelectric voltage as a function of magnetic field oscillations for different heater currents has been calculated. The dependence shows that by increasing the heater current, the oscillation first disappears, and then remarkably reappears inverted compared to low heater current. Also, the value of the thermo-power increases with increasing value of the barrier strength. Our result shows that the degree of spin polarization of the current can be unambiguously determined using Andreev reflection. Our result agrees qualitatively with those in the literature.
QUANTUM PHENOMENA VISUALIZED BY ELECTRON WAVES
Authors: TONOMURA AKIRA
Published: January 2008

Quantum phenomena have become directly observable with the development of advanced techniques such as coherent field-emission electron beams, sensitive detectors, and microlithography. Examples are the single-electron build-up of an interference pattern, which contains, as R. Feynman describes in his textbook, the heart of quantum mechanics, and the Aharonov–Bohm (AB) effect, which indicates the physical significance of gauge fields. Using the AB effect, i.e., the fundamental principle behind the interaction of an electron wave with electromagnetic fields, new ways to directly observe previously unobservable microscopic quantum objects and phenomena were developed by detecting the phase of electrons.
Neoproterozoic igneous complex emplaced along major tectonic boundary in the Kaoko Belt (NW Namibia): ion probe and LA-ICP-MS dating of magmatic and metamorphic zircons
Authors: Konopásek Jiří , Košler Jan , Tajčmanová Lucie , Ulrich Stanislav , Kitt Shawn L.
Published: January 2008

Granitoid intrusions of the Boundary Igneous Complex separate segments with different ages of high-grade metamorphism in the Kaoko Belt, NW Namibia. Two granitoids of this complex were dated at 575 ± 10 Ma (secondary ionization mass spectrometry; SIMS) or 571 ± 9 Ma (laser ablation inductively coupled plasma mass spectrometry; LA-ICP-MS) and 562 ± 11 Ma (SIMS) or 572 ± 4 Ma (LA-ICP-MS), respectively. The age of granulite-facies metamorphism in the eastern part of the Western Kaoko Zone was established at 549 ± 5 Ma (SIMS) by analysing metamorphic overgrowths of older (
c
. 1850–1000 Ma) zircons from melt segregations in amphibolites. The coastal part of the Western Kaoko Zone consists of horizons of migmatitic metasedimentary rocks that are intercalated with fine-grained orthogneisses and amphibolites resembling metamorphosed sequences of bimodal volcanic rocks. Zircons from felsic members of two bimodal suites have SIMS ages of 805 ± 4 Ma and 810–840 Ma, respectively, that are interpreted as dating their respective igneous protoliths. Melt segregations in the mafic member of the lower bimodal suite contain two populations of zircon dated at 650 ± 5 Ma (SIMS) or 645 ± 5 Ma (LA-ICP-MS) and 629 ± 6 Ma (SIMS) or 630 ± 5 Ma (LA-ICP-MS), respectively. The later age is indistinguishable from the age of 630 ± 4 Ma (SIMS) or 625 ± 10 Ma (LA-ICP-MS) obtained from melt patches present in overlying metagreywackes. The available age data suggest that the Boundary Igneous Complex masks the suture between the Coastal Terrane and the rest of the Kaoko Belt. Ages of granitoid intrusions in this igneous complex are indicative of magmatic activity between 580 and 550 Ma.
Assessment of fat-specific protein 27 in the adipocyte lineage suggests a dual role for FSP27 in adipocyte metabolism and cell death
Authors: Kim Ji Young , Liu Kun , Zhou Shengli , Tillison Kristin , Wu Yu , Smas Cynthia M.
Published: January 2008

Fat-specific protein 27 (FSP27)/CIDEC was initially identified by its upregulation in TA1 adipogenesis and is one of three cell death-inducing DFF45-like effector (CIDE) family proapoptotic proteins. Ectopic expression of CIDEs promotes apoptosis of mammalian cells. On the other hand, FSP27 has very recently been illustrated to regulate lipid droplet size and promote lipid storage in adipocytes. Regulation of endogenous FSP27 expression is unknown. We assessed the FSP27 transcript level in the well-characterized 3T3-L1 in vitro adipocyte differentiation model and found its emergence parallels the adipocyte-enriched transcript adipocyte fatty acid binding protein and stearoyl Co-A desaturase 1. Furthermore, FSP27 is a differentiation-dependent transcript in adipogenesis of primary rodent and human preadipocytes and in brown adipogenesis. The FSP27 transcript is inversely regulated by TNF-α and insulin, consistent with an antilipolytic function. It is nearly abolished with a 4-h exposure of 3T3-L1 adipocytes to 10 ng/ml TNF-α, while treatment with 100 nM insulin increased the FSP27 transcript eightfold. In the latter case LY-294002 blocked this response, indicating involvement of phosphatidylinositol 3-kinase signals. Northern blot analysis of murine tissues indicated exclusive expression of FSP27 in white and brown adipose tissue; however, a dramatic upregulation occurred in the liver of ob/ob mice. Ectopic expression of murine FSP27 in 293T cells and in 3T3-L1 preadipocytes led to the appearance of key apoptotic hallmarks and cell death. However, despite the upregulation for FSP27 in adipogenesis, we failed to detect DNA laddering indicative of apoptosis in 3T3-L1 adipocytes. This suggests that adipogenesis is accompanied by decreased susceptibility to the proapoptotic effects of FSP27. Overall, our findings support roles for FSP27 in cell death and in adipocyte function.
Differential activation of ER stress and apoptosis in response to chronically elevated free fatty acids in pancreatic β-cells
Authors: Lai Elida , Bikopoulos George , Wheeler Michael B. , Rozakis-Adcock Maria , Volchuk Allen
Published: January 2008

Chronic exposure to elevated saturated free fatty acid (FFA) levels has been shown to induce endoplasmic reticulum (ER) stress that may contribute to promoting pancreatic β-cell apoptosis. Here, we compared the effects of FFAs on apoptosis and ER stress in human islets and two pancreatic β-cell lines, rat INS-1 and mouse MIN6 cells. Isolated human islets cultured in vitro underwent apoptosis, and markers of ER stress pathways were elevated by chronic palmitate exposure. Palmitate also induced apoptosis in MIN6 and INS-1 cells, although the former were more resistant to both apoptosis and ER stress. MIN6 cells were found to express significantly higher levels of ER chaperone proteins than INS-1 cells, which likely accounts for the ER stress resistance. We attempted to determine the relative contribution that ER stress plays in palmitate-induced β-cell apoptosis. Although overexpressing GRP78 in INS-1 cells partially reduced susceptibility to thapsigargin, this failed to reduce palmitate-induced ER stress or apoptosis. In INS-1 cells, palmitate induced apoptosis at concentrations that did not result in significant ER stress. Finally, MIN6 cells depleted of GRP78 were more susceptible to tunicamycin-induced apoptosis but not to palmitate-induced apoptosis compared with control cells. These results suggest that ER stress is likely not the main mechanism involved in palmitate-induced apoptosis in β-cell lines. Human islets and MIN6 cells were found to express high levels of stearoyl-CoA desaturase-1 compared with INS-1 cells, which may account for the decreased susceptibility of these cells to the cytotoxic effects of palmitate.
Nocturnal reduction in circulating adiponectin concentrations related to hypoxic stress in severe obstructive sleep apnea-hypopnea syndrome
Authors: Nakagawa Yasuhiko , Kishida Ken , Kihara Shinji , Sonoda Mina , Hirata Ayumu , Yasui Atsutaka , Nishizawa Hitoshi , Nakamura Tadashi , Yoshida Ryoko , Shimomura Iichiro , Funahashi Tohru
Published: January 2008

Previous reports demonstrated that adiponectin has antiatherosclerotic properties. Obstructive sleep apnea-hypopnea syndrome (OSAHS) is reported to exacerbate atherosclerotic diseases. We investigated nocturnal alternation of serum adiponectin levels before sleep and after wake-up in OSAHS patients and the effect of sustained hypoxia on adiponectin in vivo and in vitro. We measured serum adiponectin concentrations in 75 OSAHS patients and 18 control subjects before sleep and after wake-up and examined the effect of one-night nasal continuous positive airway pressure (nCPAP) on adiponectin in 24 severe OSAHS patients. We investigated the effects of hypoxia on adiponectin in mice and cultured adipocytes with a sustained hypoxia model. Circulating adiponectin levels before sleep and after wake-up were lower in severe OSAHS patients than in control subjects [before sleep: 5.9 ± 2.9 vs. 8.8 ± 5.6 μg/ml ( P < 0.05); after wake-up: 5.2 ± 2.6 vs. 8.5 ± 5.5 μg/ml ( P < 0.01), respectively; means ± SD]. Serum adiponectin levels diminished significantly during sleep in severe OSAHS patients ( P < 0.0001), but one-night nCPAP improved the drop in serum adiponectin levels [−18.4 ± 13.4% vs. −10.4 ± 12.4% ( P < 0.05)]. In C57BL/6J mice and 3T3-L1 adipocytes, hypoxic exposure decreased adiponectin concentrations by inhibiting adiponectin regulatory mechanisms at secretion and transcriptional levels. The present study demonstrates nocturnal reduction in circulating adiponectin levels in severe OSAHS. Our experimental studies showed that hypoxic stress induced adiponectin dysregulation at transcriptional and posttranscriptional levels. Hypoxic stress is, at least partly, responsible for the reduction of serum adiponectin in severe OSAHS. Nocturnal reduction in adiponectin in severe OSAHS may be an important risk for cardiovascular events or other OSAHS-related diseases during sleep.
Differential Modulation of Spinal and Corticospinal Excitability During Drop Jumps
Authors: Taube Wolfgang , Leukel Christian , Schubert Martin , Gruber Markus , Rantalainen Timo , Gollhofer Albert
Published: January 2008

Previously it was shown that spinal excitability during hopping and drop jumping is high in the initial phase of ground contact when the muscle is stretched but decreases toward takeoff. To further understand motor control of stretch-shortening cycle, this study aimed to compare modulation of spinal and corticospinal excitability at distinct phases following ground contact in drop jump. Motor-evoked potentials (MEPs) induced by transcranial magnetic stimulation (TMS) and H-reflexes were elicited at the time of the short (SLR)-, medium (MLR)-, and long (LLR, LLR2)-latency responses of the soleus muscle (SOL) after jumps from 31 cm height. MEPs and H-reflexes were expressed relative to the background electromyographic (EMG) activity. H-reflexes were highly facilitated at SLR (172%) and then progressively decreased (MLR = 133%; LLR = 123%; LLR2 = 110%). TMS showed no effect at SLR, MLR, and LLR, whereas MEPs were significantly facilitated at the LLR2 (122%; P = 0.003). Background EMG was highest at LLR and lowest at LLR2. Strong H-reflex facilitation at the beginning of the stance phase indicated significant contribution of Ιa-afferent input to the α-motoneurons during this phase that then progressively declined toward takeoff. Conversely, corticospinal excitability was exclusively increased at the phase of push off (LLR2, ∼120 ms). It is argued that corticomotoneurons increased their excitability at LLR2. At LLR (∼90 ms), Ιa-afferent transmission as well as corticospinal excitability was low, whereas background EMG was high. Therefore it is speculated that other sources, presumably subcortical in origin, contributed to the EMG activity at LLR in drop jumps.