bluuebunny/crossref_metadata_2025 huggingface dataset:
Universal constant for heat production in protists
Authors: Johnson Matthew D. , Völker Jens , Moeller Holly V. , Laws Edward , Breslauer Kenneth J. , Falkowski Paul G.
Published: April 2009

Using a high sensitivity differential scanning calorimeter in isothermal mode, we directly measured heat production in eukaryotic protists from 5 phyla spanning over 5 orders of magnitude in carbon biomass and 8 orders of magnitude in cell volume. Our results reveal that metabolic heat production normalized to cell mass is virtually constant in these organisms, with a median of 0.037 pW pg C
−1
(95% confidence interval = 0.022–0.061 pW pg C
−1
) at 5 °C. Contrary to allometric models, the relationship between heat production and cell carbon content or surface area is isometric (scaling exponents, 1.056 and 1.057, respectively). That heat production per unit cell surface area is constant suggests that heat flux through the cell surface is effectively instantaneous, and hence that cells are isothermal with their environment. The results further suggest that allometric models of metabolism based on metazoans are not applicable to protists, and that the underlying metabolic processes in the latter polyphyletic group are highly constrained by evolutionary selection. We propose that the evolutionary constraint leading to a universally constant heat production in single-celled eukaryotes is related to cytoplasmic packaging of organelles and surface area to volume relationships controlling diffusion of resources to these organelles.
H2-K
b
and H2-D
b
regulate cerebellar long-term depression and limit motor learning
Authors: McConnell Michael J. , Huang Yanhua H. , Datwani Akash , Shatz Carla J.
Published: April 2009

There are more than 50 class I MHC (MHCI) molecules in the mouse genome, some of which are now known to be expressed in neurons; however, the role of classical MHCI molecules in synaptic plasticity is unknown. We report that the classical MHCI molecules, H2-K
b
and H2-D
b
, are co-expressed by Purkinje cells (PCs). In the cerebellum of mice deficient for both H2-K
b
and H2-D
b
(K
b
D
b−/−
), there is a lower threshold for induction of long-term depression (LTD) at parallel fiber to PC synapses. This change may be a result of additional glutamate release observed at K
b
D
b−/−
CF to PC synapses, which are thought to “train” the cerebellar circuit. A behavioral correlate of cerebellar LTD is motor learning; acquisition and retention of a Rotarod behavioral task is significantly better in K
b
D
b−/−
mice than in WT cohorts. These physiological and behavioral phenotypes in K
b
D
b−/−
mice reveal a surprising role for classical MHCI molecules in synaptic plasticity and motor learning.
Suzanne Pfeffer: Sorting through membrane trafficking
Authors: Sedwick Caitlin
Published: April 2009

Pfeffer is writing the rulebook for membrane trafficking and protein sorting.
hPOC5 is a centrin-binding protein required for assembly of full-length centrioles
Authors: Azimzadeh Juliette , Hergert Polla , Delouvée Annie , Euteneuer Ursula , Formstecher Etienne , Khodjakov Alexey , Bornens Michel
Published: April 2009

Centrin has been shown to be involved in centrosome biogenesis in a variety of eukaryotes. In this study, we characterize hPOC5, a conserved centrin-binding protein that contains Sfi1p-like repeats. hPOC5 is localized, like centrin, in the distal portion of human centrioles. hPOC5 recruitment to procentrioles occurs during G2/M, a process that continues up to the full maturation of the centriole during the next cell cycle and is correlated with hyperphosphorylation of the protein. In the absence of hPOC5, RPE1 cells arrest in G1 phase, whereas HeLa cells show an extended S phase followed by cell death. We show that hPOC5 is not required for the initiation of procentriole assembly but is essential for building the distal half of centrioles. Interestingly, the hPOC5 family reveals an evolutionary divergence between vertebrates and organisms like Drosophila melanogaster or Caenorhabditis elegans, in which the loss of hPOC5 may correlate with the conspicuous differences in centriolar structure.
Canonical Wnts function as potent regulators of osteogenesis by human mesenchymal stem cells
Authors: Liu Guizhong , Vijayakumar Sapna , Grumolato Luca , Arroyave Randy , Qiao HuiFang , Akiri Gal , Aaronson Stuart A.
Published: April 2009

Genetic evidence indicates that Wnt signaling is critically involved in bone homeostasis. In this study, we investigated the functions of canonical Wnts on differentiation of adult multipotent human mesenchymal stem cells (hMSCs) in vitro and in vivo. We observe differential sensitivities of hMSCs to Wnt inhibition of osteogenesis versus adipogenesis, which favors osteoblastic commitment under binary in vitro differentiation conditions. Wnt inhibition of osteogenesis is associated with decreased expression of osteoblastic transcription factors and inhibition of c-Jun N-terminal kinase and p38 mitogen-activated protein kinase activation, which are involved in osteogenic differentiation. An hMSC subpopulation exhibits high endogenous Wnt signaling, the inhibition of which enhances osteogenic and adipogenic differentiation in vitro. In an in vivo bone formation model, high levels of Wnt signaling inhibit de novo bone formation by hMSCs. However, hMSCs with exogenous expression of Wnt1 but not stabilized β-catenin markedly stimulate bone formation by naive hMSCs, arguing for an important role of a canonical Wnt gradient in hMSC osteogenesis in vivo.
Transcription, chromatin condensation, and gene migration
Authors: McNally James G.
Published: April 2009

The binding of fluorescently tagged proteins to tandem DNA arrays has been instrumental in understanding nuclear organization and function. Through the use of more natural tandem DNA arrays, Hu et al. (Hu, Y., I. Kireev, M. Plutz, N. Ashourian, and A.S. Belmont. 2009. J. Cell Biol. 185:87–100) gain new insights into chromatin organization and dynamics, and into the association of splicing factors with active genes.
ELISA-BASE: an integrated bioinformatics tool for analyzing and tracking ELISA microarray data
Authors: White Amanda M. , Collett James R. , Seurynck-Servoss Shannon L. , Daly Don S. , Zangar Richard C.
Published: April 2009

Summary:ELISA-BASE is an open source database for capturing, organizing and analyzing enzyme-linked immunosorbent assay (ELISA) microarray data. ELISA-BASE is an extension of the BioArray Software Environment (BASE) database system.

Availability:  http://www.pnl.gov/statistics/ProMAT/ELISA-BASE.stm.

Contact:  amanda.white@pnl.gov
DnaSP v5: a software for comprehensive analysis of DNA polymorphism data
Authors: Librado P. , Rozas J.
Published: April 2009

Motivation: DnaSP is a software package for a comprehensive analysis of DNA polymorphism data. Version 5 implements a number of new features and analytical methods allowing extensive DNA polymorphism analyses on large datasets. Among other features, the newly implemented methods allow for: (i) analyses on multiple data files; (ii) haplotype phasing; (iii) analyses on insertion/deletion polymorphism data; (iv) visualizing sliding window results integrated with available genome annotations in the UCSC browser.

Availability: Freely available to academic users from: http://www.ub.edu/dnasp

Contact:  jrozas@ub.edu
Functional diversity in a marine fish community
Authors: Gifford Dian J. , Collie Jeremy S. , Steele John H.
Published: April 2009

Gifford, D. J., Collie, J. S., and Steele, J. H. 2009. Functional diversity in a marine fish community. – ICES Journal of Marine Science, 66: 791–796. Calculations of fluxes in an end-to-end foodweb linear steady-state budget model are used to estimate constraints on the Georges Bank fish community that operate through decade-scale changes in nutrient input and fishing effort. The effects of these constraints are described in terms of fish functional groups and species diversity, and compensatory responses in fish community structure are considered. It is concluded that the overall fish community, rather than individual species, is resilient to external stresses imposed by combined fishing pressure and food limitation.
The average three-dimensional target strength of fish by spheroid model for sonar surveys
Authors: Tang Yong , Nishimori Yasushi , Furusawa Masahiko
Published: April 2009

Tang, Y., Nishimori, Y., and Furusawa, M. 2009. The average three-dimensional target strength of fish by spheroid model for sonar surveys. – ICES Journal of Marine Science, 66: 1176–1183. When surveying fish schools by sonar, the fish are insonified from various directions. Because the fish target strength (TS) has three-dimensional directivity, according to its orientation relative to the sonar beam, the TS must be appropriately averaged. By connecting the geometries of the sonar beam and the fish body, the relationship between the apparent orientation of fish, as viewed by the sonar, and the actual orientation in space is derived. Using this relationship, equations for calculating the three-dimensional-averaged TS (3D) are presented. A prolate-spheroid, modal-series, scattering model is then used to determine the characteristics of 3D against various parameters, such as fish attitudes, fish length, sonar frequency, and method of beam scanning. The model is evaluated with two boundary conditions at the spheroid surface: a gas-fluid boundary relevant to fish with a swimbladder, and a fluid-fluid boundary relevant to fish without a swimbladder. The results reveal that 3D varies greatly with the horizontal aspect (yaw angle), but only slightly with the vertical aspect (pitch angle) of the fish. The difference in 3D between the side-on aspect and the end-on (head or tail) aspect increases with the ratio of the fish length to the acoustic wavelength.
Analysis of Temperature Modulation of Plant Defense Against Biotrophic Microbes
Authors: Wang Yi , Bao Zhilong , Zhu Ying , Hua Jian
Published: April 2009

Plant-pathogen interactions are known to be affected by environmental factors including temperature; however, the temperature effects have not been systematically studied in plant disease resistance. Here, we characterized the effects of a moderate increase in temperature on resistance to bacterial pathogen Pseudomonas syringae and two viral elicitors in Arabidopsis thaliana and Nicotiana benthamiana. Both the basal and the resistance (R) gene–mediated defense responses to Pseudomonas syringae are found to be inhibited by a moderately high temperature, and hypersensitive responses induced by R genes against two viruses are also reduced by an increase of temperature. These indicate that temperature modulation of defense responses to biotrophic and hemibiotrophic pathogens might be a general phenomenon. We further investigated the roles of two small signaling molecules, salicylic acid and jasmonic acid, as well as two defense regulators, EDS1 and PAD4, in this temperature modulation. These components, though modulated by temperature or involved in temperature regulation or both, are not themselves determinants of temperature sensitivity in the defense responses analyzed. The inhibition of plant defense response by a moderately high temperature may thus be mediated by other defense signaling components or a combination of multiple factors.
Two Type III Secretion System Effectors from Ralstonia solanacearum GMI1000 Determine Host-Range Specificity on Tobacco
Authors: Poueymiro Marie , Cunnac Sébastien , Barberis Patrick , Deslandes Laurent , Peeters Nemo , Cazale-Noel Anne-Claire , Boucher Christian , Genin Stéphane
Published: April 2009

The model pathogen Ralstonia solanacearum GMI1000 is the causal agent of the bacterial wilt disease that attacks many solanaceous plants and other hosts but not tobacco (Nicotiana spp.). We found that two type III secretion system effector genes, avrA and popP1, are limiting the host range of strain GMI1000 on at least three tobacco species (N. tabacum, N. benthamiana, and N. glutinosa). Both effectors elicit the hypersensitive response (HR) on these tobacco species, although in different manners; AvrA is the major determinant recognized by N. tabacum and N. benthamiana, while PopP1 appears to be the major HR elicitor on N. glutinosa. Only the double inactivation of the avrA and popP1 genes allowed GMI1000 to wilt tobacco plants, thus showing that GMI1000 intrinsically possesses the functions necessary to wilt tobacco plants. A focused analysis on AvrA revealed that the first 58 N-terminal amino acids are sufficient to direct its injection into plant cells. We identified a hypervariable region in avrA, which contains variable numbers of tandem repeats (VNTR), each composed of 12 base pairs. We show that an 18–amino acid region in which the VNTR insertion occurs is an important domain involved in HR elicitation on N. benthamiana. avrA appears to be the target of various DNA insertions or mobile elements that probably allow R. solanacearum to evade the recognition and defense responses of tobacco.
Effects of Temperature on Events in the Infection Cycle of Two Clonal Lineages of Phytophthora infestans Causing Late Blight on Tomato and Potato in Brazil
Authors: Maziero José Marcelo N. , Maffia Luiz A. , Mizubuti Eduardo S. G.
Published: April 2009

In Brazil, US-1 and BR-1 clonal lineages of Phytophthora infestans are widely distributed throughout the major growing areas of tomato and potato, respectively. Quantitative information regarding the effects of temperature (10, 15, 22, and 27°C) on direct and indirect sporangia germination, incubation period (IP), latent period (LP), lesion area (LA), and sporulation (SP), as well as combined temperature and leaf wetness duration periods (6, 12, 18, and 24 h) on the number of lesions (NL) was obtained under controlled conditions on either detached leaflets or whole plants. The percentage of indirect germination was higher for BR-1 isolates than for US-1. The percentage of direct germination was higher for US-1 than for BR-1. The shortest IP and LP were recorded at 22°C for both lineages: 69.3 h and 93.3 h for US-1 isolates on detached tomato leaflets, and 44.0 h and 68 h for BR-1 isolates on detached potato leaflets, respectively. US-1 isolates did not sporulate at 10°C, and BR-1 isolates did not sporulate at 27°C. Isolates of both lineages induced the largest LA at 22°C. The NL was highest at 15°C for US-1 isolates on whole tomato plants, and at 10°C for BR-1 isolates on whole potato plants. The differential effects of temperature on US-1 and BR-1 suggest that current decision support systems initially developed for controlling US-1 in Brazil may now be inaccurate for controlling BR-1, and management strategies should be properly validated before being used.
A New Tospovirus sp. in Cucurbit Crops in Mexico
Authors: Ciuffo M. , Kurowski C. , Vivoda E. , Copes B. , Masenga V. , Falk B. W. , Turina M.
Published: April 2009

During the 2007 growing season, melon (Cucumis melo) samples from the state of Guerrero in Mexico showing mosaic and other virus-like symptoms were collected for analysis. Electron microscopic examination of negatively stained leaf-dip extracts revealed the presence of abundant virus-like particles with features characteristic of the family Bunyaviridae. No other viral particles were observed in these preparations. However, enzyme-linked immunosorbent assays (ELISAs) specific for the most common Tospovirus spp. gave negative results. Antibodies raised against purified nucleocapsids reacted specifically with the infected leaf extracts in Western blots and double-antibody sandwich ELISA. The viral RNA was used as a template for a cDNA library, and nucleotide sequence analysis identified cloned cDNAs representing sequences corresponding to the three Tospovirus genome segments. Sequence comparisons showed that the new virus had the highest similarity to Chrysanthemum stem necrosis virus (CSNV). Phylogenetic analysis of two genome regions confirmed that this virus, provisionally named Melon severe mosaic virus (MeSMV), is a previously undescribed Tospovirus sp. belonging to the “new world” clade of Tospovirus spp. An initial survey of various cucurbit crops in various states of Mexico confirmed the widespread occurrence of this virus.
Effect of Culture Conditions on Conidia Formation by Elsinoë ampelina, the Causal Organism of Grapevine Anthracnose
Authors: Kono Atsushi , Nakaune Ryoji , Yamada Masahiko , Nakano Masaaki , Mitani Nobuhito , Ueno Toshihito
Published: April 2009

Elsinoë ampelina, the causal organism of grapevine anthracnose, can be easily grown in culture, yet its sporulation is poor and unstable in culture. In this study, we sought the optimum conditions for a simple method to stably generate conidia. We first examined the optimum period of incubation for young colonies grown on potato dextrose agar (PDA) in water. The resultant number of conidia showed a logarithmic increase, which slowed at about 8 to 10 h. This suggests that 8 to 10 h of preculture would provide a sufficient number of conidia under the culture conditions used. A high negative correlation between colony density on PDA and the number of resultant conidia existed: colonies grown at >2.5 colonies per cm2 produced few or no conidia, whereas those grown at <1.0 colony per cm2 stably produced as many as 2.9 × 106 conidia. The optimum condition for preculture was to incubate colonies grown for 6 days on PDA at a density of <1.0 colony per cm2. The conidia obtained by our method were pathogenic on the grape cultivar Rizamat.
Action Thresholds for Summer Fungicide Sprays and Sequential Classification of Apple Scab Incidence
Authors: Carisse Odile , Meloche Catherine , Boivin Guy , Jobin Tristan
Published: April 2009

The objectives of this study were to establish scab incidence thresholds at which summer fungicide sprays should be initiated and to develop sequential sampling for classification plans to facilitate decision making. The relationship between proportion of scabbed leaves per shoot and percent scabbed fruits at harvest was established based on data collected in both experimental and commercial orchards. Action threshold at which fungicide spray program should be initiated in order to maintain fruit scab at harvest below 2% was established at 0.006 scabbed leaves per shoot; hence incidence thresholds of 0.005 and 0.01 scabbed leaves per shoot were evaluated. Sequential sampling for classification procedures (SSCP), using the Wald's sequential probability ratio test (SPRT), were developed based on a beta-binomial distribution and using parameter estimates of the binary power law. Monte Carlo simulations were used to establish the probability of classifying mean scab incidence as less than the action thresholds (pth = 0.005 and pth = 0.01). Operating characteristic (OC) and average sample number (ASN) curves were established for eight combinations of stop lines and error levels (α and β). Based on the results of the Monte Carlo simulations, four sets of stop lines (two for each pth threshold) were selected for further evaluation. Bootstrap simulations of 50 data sets indicated that both the OC and ASN curves for each of the four pairs of stop lines were similar to OC and ASN values determined by Monte Carlo simulation. When validated with data not used to construct the models, the SSCPs provided the appropriate classification in 98 and 95% of the simulations for the pth = 0.005 and pth = 0.01 (α = 0.05 and β = 0.10), respectively. The sequential sampling plans developed in this study should allow for rapid and accurate classification of the incidence of apple scab on leaves, and aid in sampling for summer scab management decision making.
Reproduction of Soybean Cyst Nematode on Dry Bean Cultivars Adapted to North Dakota and Northern Minnesota
Authors: Poromarto Susilo H. , Nelson Berlin D.
Published: April 2009

Dry bean (Phaseolus vulgaris) is a host of the soybean cyst nematode (SCN; Heterodera glycines). Twenty-four cultivars of dry bean representing pinto, navy, black, and kidney bean classes were evaluated for host suitability for SCN HG type 0 in the greenhouse. Females of SCN developed normally on all dry bean cultivars in 30 days. Eggs collected from roots of dry bean plants were as effective as inoculum for soybean as eggs collected from roots of soybean. Averaged over experiments, the number of SCN females per plant was significantly lower (P ≤ 0.001) on pinto, navy, and black bean than on the susceptible soybean Lee 74. There was no difference in the number of females between kidney bean and soybean. Numbers of females per plant differed (P ≤ 0.001) among navy cultivars but not among cultivars in the other three bean classes. A female index (FI = the average number of females on the test plant divided by the average number of females on the susceptible soybean Lee 74 × 100) was calculated for each cultivar to evaluate resistance to SCN. FIs varied from 5 to 117, indicating a range of susceptibility in the crop. Kidney bean averaged the highest FI at 110, followed by navy, pinto, and black at FI = 41, 39, and 16, respectively. SCN is a potential threat to dry bean in the northern production area of North Dakota and northern Minnesota.
Effects of Copper-Based Fungicides on Foliar Gas Exchange in Tart Cherry
Authors: Gruber B. R. , Davies L. R. R. , Kruger E. L. , McManus P. S.
Published: April 2009

In the Great Lakes region of the United States, cherry growers are poised to re-adopt copper-based fungicides to manage cherry leaf spot disease (CLS), caused by Blumeriella jaapii. However, application of copper is often associated with leaf bronzing. In growth chamber experiments, bronzing was observed on foliage of tart cherry (Prunus cerasus ‘Montmorency’) seedlings 1 week following application of a copper-based fungicide, only when leaves were also exposed to nightly dew. In potted, 1-year-old trees outdoors, light-saturated rates of net CO2assimilation (A) and stomatal conductance (gs) were not affected by treatment with copper sulfate, chlorothalonil, tebuconazole, or trifloxystrobin compared to a nonsprayed control. In 2005 and 2006, A and gswere measured during late summer on leaves of mature trees in an orchard subjected to the following fungicide programs: synthetic fungicides only; synthetic fungicides integrated with copper-based fungicides; or not sprayed. Bronzing symptoms were observed on trees sprayed with copper. Regression analysis revealed that neither A nor gsdecreased as leaf surface area affected by bronzing increased (R2= 0.004, P = 0.80 and R2= 0.006, P = 0.74, respectively). Leaf bronzing associated with application of copper-based fungicides may therefore be inconsequential to foliar gas exchange in tart cherry during late summer.
Comparison of Crop Rotation for Verticillium Wilt Management and Effect on Pythium Species in Conventional and Organic Strawberry Production
Authors: Njoroge Samuel M. C. , Kabir Zahangir , Martin Frank N. , Koike Steven T. , Subbarao Krishna V.
Published: April 2009

The effects of broccoli and lettuce rotations on population densities of Verticillium dahliae and Pythium spp. in soil and on strawberry (Fragaria × ananassa) growth, yield, and Verticillium wilt were evaluated in conventional and organic production systems in California for 2 years. Under both management systems, strawberry was planted after two successive crops of broccoli or lettuce. The control treatment in the conventional field was strawberry planted in soils fumigated with methyl bromide + chloropicrin. Preplant densities of V. dahliae and Pythium sp. did not differ in these fields. At the end of the second broccoli crop, V. dahliae densities in conventional plots had declined by 44% in both years. In contrast, after the second broccoli crop, densities in organic fields decreased 47% in 2000 and 25% in 2001. In general, there were no differences in V. dahliae inoculum densities in organic and conventional plots following lettuce rotations. After the second vegetable production cycle, population densities of V. dahliae in broccoli rotated organic (24 CFU/g of soil in 2000 and 27 CFU/g of soil in 2001) or conventional (23 CFU/g of soil in 2000 and 19 CFU/g of soil in 2001) fields were significantly lower than those in lettuce rotated organic (40 CFU/g of soil in 2000 and 42 CFU/g of soil in 2001) or conventional (39 CFU/g of soil in 2000 and 35 CFU/g of soil in 2001) fields. However, crop rotation treatments had no consistent effect on the inoculum densities of Pythium spp. Canopy diameters of strawberry plants grown in rotation with broccoli were not different from those in fumigated control plots, whereas those from lettuce plots were 10% smaller. Strawberry plant nutrient analysis showed that fertilizer inputs into organic or conventional production were not responsible for the observed differences in plant size. Increases in strawberry yields were not consistent between years. Verticillium wilt incidence on strawberry was 12 to 24% lower in fields rotated with broccoli compared with fields rotated with lettuce. Wilt severity on strawberry was 22 to 36% lower in fields rotated with broccoli compared with those rotated with lettuce. The strategy of using broccoli rotation coupled with postharvest incorporation of broccoli residue continues to show promise as a tool in the management of Verticillium wilt in both conventional and organic strawberry production systems.
First Report of Stem Blight on Perilla (Perilla frutescens) Caused by Corynespora cassiicola in Korea
Authors: Lee H. B. , Kim C. J. , Mun H. Y.
Published: April 2009

Perilla or kkaennip (Perilla frutescens (L.) Britton), an annual herb of the mint family, Lamiaceae, is used in salads and kimchi and for wrapping sliced raw fish. In September 2007, a disease occurred on greenhouse-produced perilla (cv. Manchu) in Gwangyang and Jeonnam provinces, Korea. Symptoms included leaf blight and irregularly shaped stem lesions approximately 1 to 3 cm long. Plants eventually died. In some greenhouses, 10 to 30%, and occasionally as much as 70%, of the plants were affected. Isolations on potato dextrose agar yielded a fungus with single conidiophores (439 to 656 [average 524] μm long × 6.2 to 11.6 [average 9.2] μm wide) with three to eight septa. Conidia were fusiform, obclavate to subcylindrical, straight or curved, and 30.4 to 180.1 (average 98.2) μm long × 6.7 to 18.1 (average 10.5) μm wide with 5 to 16 (commonly 13) distosepta. On the basis of morphological data and ITS rDNA sequences, the fungus was identified as Corynespora cassiicola (Berk. & Curt.) Wei. (1,2). Sequences of one isolate, EML-COR1, were more than 99% identical to sequences of C. cassiicola ATCC64204 (GenBank Accession No. AY238606) and C. cassiicola (GenBank Accession No. EF490450). In pathogenicity tests, the stems and leaves of two 2-month-old wounded and nonwounded potted plants (cv. Manchu) were sprayed until runoff with a conidial suspension of 5 × 104 conidia per ml. The plants were maintained for 48 h in a humid chamber and then moved to a greenhouse. Symptoms similar to those observed in the commercial greenhouse developed on wounded stems within 10 days. On nonwounded plants, symptoms developed 3 to 4 weeks after inoculation. C. cassiicola was reisolated from these lesions. Control plants (sprayed with distilled water) remained symptomless. The experiment was repeated with similar results. Although C. cassiicola causes blight of cucumber (Cucumis sativus L.), sesame (Sesamum indicum L.), and other crops, to our knowledge, this is the first report of C. cassiicola on perilla.

References: (1) M. B. Ellis. Page 372 in: Dematiaceous Hyphomycetes. 1971. (2) J. L. D. Silva et al. Plant Pathol. 55:580, 2006.
Detection and Molecular Characterization of a ‘Candidatus Phytoplasma asteris’-Related Strain Infecting Sasa fortunei in China
Authors: Zhang C. P. , Min H. , Zheng X. , Yu X. Q. , Zhang H. , Wu Y. F.
Published: April 2009

Bamboos are ecologically and economically valuable plants. Young shoots of almost all species are edible, either raw or cooked, and are major components of Asian cuisine while culms are used for furniture or handicrafts as well as fuel wood. Symptoms indicative of phytoplasma disease were observed on Sasa fortunei (van Houtte) Fiori during a survey in Yangling, Shaanxi Province, China during 2007. Symptoms included internode shortening, a mosaic pattern on leaves of diminished size, stunted growth, and death of entire plants. Total nucleic acids were extracted from leaf veins of 10 diseased plants and 6 symptomless plants with a modified cetyltrimethylammoniumbromide (CTAB) method (1). Phytoplasma infection of plants was demonstrated by a nested PCR assay employing primer pair R16mF2/R16mR1 followed by R16F2n/R16R2 (2), which generated a 16S rDNA product of approximately 1.2 kb from all symptomatic plants only. Restriction fragment length polymorphism analysis by digestion of nested PCR products with restriction enzymes AluI and MseI indicated that S. fortunei plants contained group 16SrI (aster yellows), subgroup B phytoplasmas. Sequencing and phylogenetic analysis of phytoplasma 16S rDNA from S. fortunei (GenBank Accession No. FJ501958) revealed this strain to be very similar (99.7 and 99.6%, respectively) to phytoplasmas previously associated with Henon bamboo (Phyllostachys nigra) witches'-broom (GenBank Accession No. AB242433) (4) and sasa (S. borealis) witches'-broom (GenBank Accession No. AB293421) in Korea but less so (98.6%) to bamboo (Phyllostachys spp.) witches'-broom (GenBank Accession No. AY635145) disease in China (3). To our knowledge, this is the first report of a ‘Ca. Phytoplasma asteris’-related strain infecting S. fortunei in China.

References: (1) E. Angelini et al. Vitis 40:79, 2001. (2) D. E. Gundersen and I.-M. Lee. Phytopathol. Mediterr. 35:144, 1996. (3) C. Hong et al. Plant Prot. 31:39, 2005. (4) H. Jung et al. J. Gen. Plant Pathol. 72:261, 2006.
Embryonic and fetal limb myogenic cells are derived from developmentally distinct progenitors and have different requirements for β-catenin
Authors: Hutcheson David A. , Zhao Jia , Merrell Allyson , Haldar Malay , Kardon Gabrielle
Published: April 2009

Vertebrate muscle arises sequentially from embryonic, fetal, and adult myoblasts. Although functionally distinct, it is unclear whether these myoblast classes develop from common or different progenitors. Pax3 and Pax7 are expressed by somitic myogenic progenitors and are critical myogenic determinants. To test the developmental origin of embryonic and fetal myogenic cells in the limb, we genetically labeled and ablated Pax3+ and Pax7+ cells. Pax3+Pax7− cells contribute to muscle and endothelium, establish and are required for embryonic myogenesis, and give rise to Pax7+ cells. Subsequently, Pax7+ cells give rise to and are required for fetal myogenesis. Thus, Pax3+ and Pax7+ cells contribute differentially to embryonic and fetal limb myogenesis. To investigate whether embryonic and fetal limb myogenic cells have different genetic requirements we conditionally inactivated or activated β-catenin, an important regulator of myogenesis, in Pax3- or Pax7-derived cells. β-Catenin is necessary within the somite for dermomyotome and myotome formation and delamination of limb myogenic progenitors. In the limb, β-catenin is not required for embryonic myoblast specification or myofiber differentiation but is critical for determining fetal progenitor number and myofiber number and type. Together, these studies demonstrate that limb embryonic and fetal myogenic cells develop from distinct, but related progenitors and have different cell-autonomous requirements for β-catenin.
Polyubiquitination of the demethylase Jhd2 controls histone methylation and gene expression
Authors: Mersman Douglas P. , Du Hai-Ning , Fingerman Ian M. , South Paul F. , Briggs Scott D.
Published: April 2009

The identification of histone methyltransferases and demethylases has uncovered a dynamic methylation system needed to modulate appropriate levels of gene expression. Gene expression levels of various histone demethylases, such as the JARID1 family, show distinct patterns of embryonic and adult expression and respond to different environmental cues, suggesting that histone demethylase protein levels must be tightly regulated for proper development. In our study, we show that the protein level of the yeast histone H3 Lys 4 (H3 K4) demethylase Jhd2/Kdm5 is modulated through polyubiquitination by the E3 ubiquitin ligase Not4 and turnover by the proteasome. We determine that polyubiquitin-mediated degradation of Jhd2 controls in vivo H3 K4 trimethylation and gene expression levels. Finally, we show that human NOT4 can polyubiquitinate human JARID1C/SMCX, a homolog of Jhd2, suggesting that this is likely a conserved mechanism. We propose that Not4 is an E3 ubiquitin ligase that monitors and controls a precise amount of Jhd2 protein so that the proper balance between histone demethylase and histone methyltransferase activities occur in the cell, ensuring appropriate levels of H3 K4 trimethylation and gene expression.
Multilevel Analysis of Primary Metabolism Provides New Insights into the Role of Potassium Nutrition for Glycolysis and Nitrogen Assimilation in Arabidopsis Roots
Authors: Armengaud Patrick , Sulpice Ronan , Miller Anthony J. , Stitt Mark , Amtmann Anna , Gibon Yves
Published: April 2009

Potassium (K) is required in large quantities by growing crops, but faced with high fertilizer prices, farmers often neglect K application in favor of nitrogen and phosphorus. As a result, large areas of farmland are now depleted of K. K deficiency affects the metabolite content of crops with negative consequences for nutritional quality, mechanical stability, and pathogen/pest resistance. Known functions of K in solute transport, protein synthesis, and enzyme activation point to a close relationship between K and metabolism, but it is unclear which of these are the most critical ones and should be targeted in biotechnological efforts to improve K usage efficiency. To identify metabolic targets and signaling components of K stress, we adopted a multilevel approach combining transcript profiles with enzyme activities and metabolite profiles of Arabidopsis (Arabidopsis thaliana) plants subjected to low K and K resupply. Roots and shoots were analyzed separately. Our results show that regulation of enzymes at the level of transcripts and proteins is likely to play an important role in plant adaptation to K deficiency by (1) maintaining carbon flux into amino acids and proteins, (2) decreasing negative metabolic charge, and (3) increasing the nitrogen-carbon ratio in amino acids. However, changes in transcripts and enzyme activities do not explain the strong and reversible depletion of pyruvate and accumulation of sugars observed in the roots of low-K plants. We propose that the primary cause of metabolic disorders in low-K plants resides in the direct inhibition of pyruvate kinase activity by low cytoplasmic K in root cells.
Exploring the Ultrastructural Localization and Biosynthesis of β(1,4)-Galactan in Pinus radiata Compression Wood
Authors: Mast Steven W. , Donaldson Lloyd , Torr Kirk , Phillips Lorelle , Flint Heather , West Mark , Strabala Timothy J. , Wagner Armin
Published: April 2009

Softwood species such as pines react to gravitropic stimuli by producing compression wood, which unlike normal wood contains significant amounts of β(1,4)-galactan. Currently, little is known regarding the biosynthesis or physiological function of this polymer or the regulation of its deposition. The subcellular location of β(1,4)-galactan in developing tracheids was investigated in Pinus radiata D. Don using anti-β(1,4)-galactan antibodies to gain insight into its possible physiological role in compression wood. β(1,4)-Galactan was prominent and evenly distributed throughout the S2 layer of developing tracheid cell walls in P. radiata compression wood. In contrast, β(1,4)-galactan was not detected in normal wood. Greatly reduced antibody labeling was observed in fully lignified compression wood tracheids, implying that lignification results in masking of the epitope. To begin to understand the biosynthesis of galactan and its regulation, an assay was developed to monitor the enzyme that elongates the β(1,4)-galactan backbone in pine. A β(1,4)-galactosyltransferase (GalT) activity capable of extending 2-aminopyridine-labeled galacto-oligosaccharides was found to be associated with microsomes. Digestion of the enzymatic products using a β(1,4)-specific endogalactanase confirmed the production of β(1,4)-galactan by this enzyme. This GalT activity was substantially higher in compression wood relative to normal wood. Characterization of the identified pine GalT enzyme activity revealed pH and temperature optima of 7.0 and 20°C, respectively. The β(1,4)-galactan produced by the pine GalT had a higher degree of polymerization than most pectic galactans found in angiosperms. This observation is consistent with the high degree of polymerization of the naturally occurring β(1,4)-galactan in pine.
Timing and Biosynthetic Potential for Carotenoid Accumulation in Genetically Diverse Germplasm of Maize
Authors: Vallabhaneni Ratnakar , Wurtzel Eleanore T.
Published: April 2009

Enhancement of the carotenoid biosynthetic pathway in food crops benefits human health and adds commercial value of natural food colorants. However, predictable metabolic engineering or breeding is limited by the incomplete understanding of endogenous pathway regulation, including rate-controlling steps and timing of expression in carotenogenic tissues. The grass family (Poaceae) contains major crop staples, including maize (Zea mays), wheat (Triticum aestivum), rice (Oryza sativa), sorghum (Sorghum bicolor), and millet (Pennisetum glaucum). Maize carotenogenesis was investigated using a novel approach to discover genes encoding limiting biosynthetic steps in the nutritionally targeted seed endosperm. A combination of bioinformatics and cloning were first used to identify and map gene families encoding enzymes in maize and other grasses. These enzymes represented upstream pathways for isopentenyl diphosphate and geranylgeranyl diphosphate synthesis and the downstream carotenoid biosynthetic pathway, including conversion to abscisic acid. A maize germplasm collection was used for statistical testing of the correlation between carotenoid content and candidate gene transcript levels. Multiple pathway bottlenecks for isoprenoid biosynthesis and carotenoid biosynthesis were discovered in specific temporal windows of endosperm development. Transcript levels of paralogs encoding isoprenoid isopentenyl diphosphate and geranylgeranyl diphosphate-producing enzymes, DXS3, DXR, HDR, and GGPPS1, were found to positively correlate with endosperm carotenoid content. For carotenoid pathway enzymes, transcript levels for CrtISO inversely correlated with seed carotenoid content, as compared with positive correlation of PSY1 transcripts. Since zeaxanthin epoxidase (ZEP) depletes the carotenoid pool in subsequent conversion to abscisic acid, ZEP transcripts were examined. Carotenoid accumulation was found to be inversely associated with ZEP1 and ZEP2 transcript levels. Extension of the maize results using phylogenetic analysis identified orthologs in other grass species that may serve as potential metabolic engineering targets.
Two-Step Regulation ofLAX PANICLE1Protein Accumulation in Axillary Meristem Formation in Rice
Authors: Oikawa Tetsuo , Kyozuka Junko
Published: April 2009

Axillary meristem (AM) formation is an important determinant of plant architecture. In rice (Oryza sativa), LAX PANICLE1 (LAX1) function is required for the generation of AM throughout the plant's lifespan. Here, we show a close relationship between AM initiation and leaf development; specifically, the plastochron 4 (P4) stage of leaf development is crucial for the proliferation of meristematic cells. Coincident with this, LAX1 expression starts in the axils of leaves at P4 stage. LAX1 mRNA accumulates in two to three layers of cells in the boundary region between the initiating AM and the shoot apical meristem. In lax1 mutants, the proliferation of meristematic cells is initiated but fails to progress into the formation of AM. The difference in sites of LAX1 mRNA expression and its action suggests non-cell-autonomous characteristics of LAX1 function. We found that LAX1 protein is trafficked to AM in a stage- and direction-specific manner. Furthermore, we present evidence that LAX1 protein movement is required for the full function of LAX1. Thus, we propose that LAX1 protein accumulates transiently in the initiating AM at P4 stage by a strict regulation of mRNA expression and a subsequent control of protein trafficking. This two-step regulation is crucial to the establishment of the new AM.
Controlled Enlargement of the Glycoprotein Vesicle Surrounding aVolvoxEmbryo Requires the InvB Nucleotide-Sugar Transporter and Is Required for Normal Morphogenesis
Authors: Ueki Noriko , Nishii Ichiro
Published: April 2009

Here, we report our analysis of a mutant of Volvox carteri, InvB, whose embryos fail to execute inversion, the process in which each Volvox embryo normally turns itself inside-out at the end of embryogenesis, thereby achieving the adult configuration. The invB gene encodes a nucleotide-sugar transporter that exhibits GDP-mannose transport activity when expressed in yeast. In wild-type embryos, the invB transcript is maximally abundant before and during inversion. A mannoside probe (fluorescent concanavalin A) stains the glycoprotein-rich gonidial vesicle (GV) surrounding wild-type embryos much more strongly than it stains the GV surrounding InvB embryos. Direct measurements revealed that throughout embryogenesis the GV surrounding a wild-type embryo increases in size much more than the GV surrounding an InvB embryo does, and the fully cleaved InvB embryo is much more tightly packed within its GV than a wild-type embryo is. To test the hypothesis that the restraint imposed by a smaller than normal GV directly causes the inversion defect in the mutant, we released InvB embryos from their GVs microsurgically. The resulting embryos inverted normally, demonstrating that controlled enlargement of the GV, by a process in which requires the InvB nucleotide-sugar transporter, is essential to provide the embryo sufficient space to complete inversion.
Seasonal stability and spatial variability of parasites in Brazilian sandperch Pinguipes brasilianus from the Northern Argentine Sea: evidence for stock discrimination
Authors: Timi J. T. , Lanfranchi A. L. , Etchegoin J. A.
Published: April 2009

The use of parasites as biological tags allowed the identification of two stocks of Brazilian sandperch Pinguipes brasilianus, in the Bonaerense region of the Argentine Sea. A total of 156 adult specimens of P. brasilianus were examined for parasites. Temporal variability in parasite burdens was assessed from fish caught seasonally in coastal waters of two zones, south Bonaerense (during autumn and winter) and north Bonaerense (during summer). Additional data from a previous study, comprising P. brasilianus caught during spring in these two zones, as well as in two populations from north Patagonian gulfs were used for comparative analyses of spatial variability. A total of 14 193 metazoan parasites belonging to 19 species were found. Comparisons of seasonal variability in pooled samples and within each locality showed that locality effects exceeded seasonal ones, suggesting the possible existence of two discrete stocks in the Bonaerense region. These findings were strongly supported by discriminant analyses and comparisons of prevalence and abundance between zones, after pooling seasonal samples within each zone. Further evidence of the discreteness of both stocks was assessed by inclusion of samples from Patagonian gulfs in the discriminant analysis, confirming that their differences were at a inter‐population level. The parasite species that contributed most to the separation of the samples were generally those identified as biological markers in previous studies. Differing oceanographic conditions are discussed as potential causes of inter‐population variation of parasite burdens.
Reproduction of the blue‐spotted maskray Neotrygon kuhlii (Myliobatoidei: Dasyatidae) in south‐east Queensland, Australia
Authors: Pierce S. J. , Pardo S. A. , Bennett M. B.
Published: April 2009

This study examined the reproduction and population structure of the blue‐spotted maskray Neotrygon kuhlii within Moreton Bay, a subtropical embayment in south‐east Queensland, Australia. Mean sizes at maturity were 314 mm disc width (WD) in females (n = 140, 115–465 mm WD) and 294 mm WD in males (n = 123, 129–381 mm WD). Female N. kuhlii had a synchronous annual reproductive cycle, with one litter of one to three pups (mean ±s.d. 1·67 ± 0·71) produced per year. Mating behaviours were observed in October and November, and ovulation occurred early in the Austral summer, overlapping with the start of embryonic development. Gestation took c. 4 months with parturition occurring in late February and March. Size at birth was 115–170 mm WD. The population showed a significant female bias, particularly in larger size classes. Tagging studies produced a total recapture rate of 16·1% and indicated that N. kuhlii were site resident for up to 1081 days.
Chronic illnesses in Canadian children: what is the effect of illness on academic achievement, and anxiety and emotional disorders?
Authors: Martinez Y. J. , Ercikan K.
Published: April 2009

Background  Survival rates of children with a chronic illness is at an all‐time high. Up to 98% of children suffering from a chronic illness, which may have been considered fatal in the past, now reach early adulthood. It is estimated that as many as 30% of school‐aged children are affected by a chronic illness. For this population of children, the prevalence of educational and psychological problems is nearly double in comparison with the general population.

Methods  This study investigated the educational and psychological effects of childhood chronic illness among 1512 Canadian children (ages 10–15 years). This was a retrospective analysis using data from the National Longitudinal Survey of Children and Youth, taking a cross‐sectional look at the relationships between childhood chronic illnesses, performance on a Mathematics Computation Exercise (MCE) and ratings on an Anxiety and Emotional Disorder (AED) scale.

Results  When AED ratings and educational handicaps were controlled for, children identified with chronic illnesses still had weaker performance on the MCE. Chronic illness did not appear to have a relationship with children's AED ratings. The regression analysis indicated that community type and illness were the strongest predictors of MCE scores.

Conclusions  The core research implications of this study concern measurement issues that need to be addressed in future large‐scale studies. Clinical implications of this research concern the need for co‐ordinated services between the home, hospital and school settings so that services and programmes focus on the ecology of the child who is ill.