bluuebunny/crossref_metadata_2025 huggingface dataset:
The small GTPase Rho4 is involved in controlling cell morphology and septation in fission yeast
Authors: Nakano Kentaro , Mutoh Tadashi , Arai Ritsuko , Mabuchi Issei
Published: December 2004

Background:Rho family small GTPases have been shown to be involved in various cellular activities, including the organization of actin cytoskeleton in eukaryotic cells. There are sixrhogenes in the fission yeastSchizosaccharomyces pombe. Cdc42 is known to control the polarity of the cell. Rho1, Rho2 and Rho3 play important roles in controlling cell shape and septation. On the other hand, Rho4 and Rho5 have not yet been characterized. Here we report the function ofrho4+in fission yeast.

Results:Gene disruption revealed thatrho4+is not essential for cell growth. However,rho4‐null cells were abnormally elongated and had multiple septa of irregular shape at 37 °C. In these cells, F‐actin patches were randomly localized all over the cell periphery, and cytoplasmic microtubules (MTs) were misoriented. On the other hand, the exogenous expression of a constitutively active Rho4‐G23V or Rho4‐Q74L in wild‐type cells induced depolarization of F‐actin patches and cytoplasmic MTs. Rho4 was localized to the cell periphery during interphase and septum during mitosis. Both the binding of GTP and isoprenylation of its C‐terminus were necessary for the localization. Furthermore, the localization of Rho4 was likely to be controlled by Rho GAP and Rho GDI.

Conclusion:Rho4 may control cell morphogenesis and septation by regulating both the actin cytoskeleton and cytoplasmic MTs.
Keap1 regulates both cytoplasmic‐nuclear shuttling and degradation of Nrf2 in response to electrophiles
Authors: Itoh Ken , Wakabayashi Nobunao , Katoh Yasutake , Ishii Tetsuro , O'Connor Tania , Yamamoto Masayuki
Published: December 2004

Background: Transcription factor Nrf2 regulates the expression of a set of detoxifying and anti‐oxidant enzyme genes. Several lines of evidence suggest that electrophiles and reactive oxygen species liberate Nrf2 from its cytoplasmic repressor Keap1 and provoke the accumulation of Nrf2 in the nucleus. To elucidate the molecular mechanisms as to how Nrf2 is activated by inducers, we examined the cytoplasmic‐nuclear shuttling and turnover of Nrf2.

Results: We found that Nrf2 is rapidly degraded through the proteasome pathway, while electrophiles cause Nrf2 nuclear translocation with concomitant stabilization. Crucial to the inducible accumulation of Nrf2 is the enfeebling of the Nrf2–Keap1 interaction by electrophiles. Exploiting mice which have the LacZ reporter gene knocked into the nrf2 locus, we revealed that the inducible accumulation of Nrf2 protein by electrophiles in macrophages and intestinal epithelia could be recapitulated by the Nrf2 N‐terminal region in combination with a nuclear localization signal. We also found constitutive Nrf2 nuclear accumulation in Keap1‐deficient mouse macrophages.

Conclusions: Our results highlight the fact that Nrf2 protein turnover is regulated by Keap1 mediated subcellular compartmentalization.
Caffeine mimics adenine and 2′‐deoxyadenosine, both of which inhibit the guanine‐nucleotide exchange activity of RCC1 and the kinase activity of ATR
Authors: Nishijima Hitoshi , Nishitani Hideo , Saito Noriko , Nishimoto Takeharu
Published: December 2004

Background: Both caffeine and the inactivation of RCC1, the guanine‐nucleotide exchange factor (GEF) of Ran, induce premature chromatin condensation (PCC) in hamster BHK21 cells arrested in the S‐phase, suggesting that RCC1 is a target for caffeine.

Results: Caffeine inhibited the Ran‐GEF activity of RCC1 by preventing the binary complex formation of Ran‐RCC1. Inhibition of the Ran‐GEF activity of RCC1 by caffeine and its derivatives was correlated with their ability to induce PCC. Since caffeine is a derivative of xanthine, the bases and nucleosides were screened for their ability to inhibit RCC1. Adenine, adenosine, and all of the 2′‐deoxynucleosides inhibited the Ran‐GEF activity of RCC1; however, only adenine and 2′‐deoxyadenosine (2′‐dA) induced PCC. A factor(s) other than RCC1, should therefore be involved in PCC‐induction. We found that both adenine and 2′‐dA, but none of the other 2′‐deoxynucleosides, inhibited the kinase activity of ATR, similar to that of caffeine. The ATR pathway was also abrogated by the inactivation of RCC1 in tsBN2 cells.

Conclusion: The effect of caffeine on cell‐cycle control mimics the biological effect of adenine and 2′‐dA, both of which inhibit ATR. dATP, a final metabolite of adenine and 2′‐dA, is suggested to inhibit ATR, resulting in PCC.
Budding yeastmcm10/dna43mutant requires a novel repair pathway for viability
Authors: Araki Yoshio , Kawasaki Yasuo , Sasanuma Hiroyuki , Tye Bik K. , Sugino Akio
Published: December 2004

Background:MCM10is essential for the initiation of chromosomal DNA replication inSaccharomyces cerevisiae. Mcm10p functionally interacts with components of the pre‐replicative complex (Mcm2‐Mcm7 complex and origin recognition complex) as well as the pre‐initiation complex component (Cdc45p) suggesting that it may be a component of the pre‐RC as well as the pre‐IC. Two‐dimensional gel electrophoresis analysis showed that Mcm10p is required not only for the initiation of DNA synthesis at replication origins but also for the smooth passage of replication forks at origins. Genetic analysis showed thatMCM10interacts with components of the elongation machinery such as Polδ and Polɛ, suggesting that it may play a role in elongation replication.

Results:We show that themcm10mutation causes replication fork pausing not only at potentially active origins but also at silent origins. We screened for mutations that are lethal in combination withmcm10‐1and obtained seven mutants namedslm1‐slm6forsyntheticallylethal withmcm10. These mutants comprised six complementation groups that can be divided into three classes. Class 1 includes genes that encode components of the pre‐RC and pre‐IC and are represented bySLM3,4and5which are allelic toMCM7,MCM2andCDC45, respectively. Class 2 includes genes involved in the processing of Okazaki fragments in lagging strand synthesis and is represented bySLM1, which is allelic toDNA2. Class 3 includes novel DNA repair genes represented bySLM2andSLM6.

Conclusions:The viability of themcm10‐1mutant is dependent on a novel repair pathway that may participate either in resolving accumulated replication intermediates or the damage caused by blocked replication forks. These results are consistent with the hypothesis that Mcm10p is required for the passage of replication forks through obstacles such as those created by pre‐RCs assembled at active or inactive replication origins.
Cloning and characterization of mCRIP2, a mouse LIM‐only protein that interacts with PDZ domain IV of PTP‐BL
Authors: Van Ham Marco , Croes Huib , Schepens Jan , Fransen Jack , Wieringa Bé , Hendriks Wiljan
Published: December 2004

Abstract Background: In the mouse submembranous protein tyrosine phosphatase PTP‐BL five PDZ domains are present in between the N‐terminal FERM domain, which directs the protein to the cell cortex, and the C‐terminal catalytic phosphatase domain. To understand more on the physical role of PTP‐BL in this microenvironment, we started to search for PTP‐BL PDZ domain‐interacting proteins.

Results: Yeast two‐hybrid screening for PTP‐BL targets resulted in the identification of a novel mouse LIM‐only protein termed CRIP2 that is highly homologous to rat ESP1 and human CRP2 sequences. Mouse CRIP2 has a predicted molecular weight of 23 kD and consists of two LIM domains spaced by 68 amino acids. The fourth PDZ domain of PTP‐BL is responsible for the binding of CRIP2 protein. Both PTP‐BL and CRIP2 mRNAs display a wide, overlapping tissue distribution. Western blot analysis revealed a more restricted expression pattern for CRIP2 with high expression in lung, heart and brain. CRIP2 protein is localized at cell cortical, actin‐rich structures, which is concurrent with the subcellular localization of PTP‐BL.

Conclusions: The observed characteristics of the LIM domain‐containing adaptor protein CRIP2 are consistent with a potential role of PTP‐BL in the dynamics of the cortical actin cytoskeleton.
Antioxidant function of a novel selenoprotein in Drosophila melanogaster
Authors: Morozova Nadya , Forry Erin P. , Shahid Elena , Zavacki Ann Marie , Harney John W. , Kraytsberg Yevgenya , Berry Marla J.
Published: December 2004

Background:  Insects appear to have diverged from both higher and lower organisms in their defense mechanisms against oxidative damage. They do not encode glutathione peroxidases or glutathione reductases, and their thioredoxin reductases exhibit distinct properties from those of higher and lower species. Nonetheless, appropriate balance of anti‐oxidants and pro‐oxidants, and protection from damaging reactive oxygen species are clearly crucial in insects for viability, normal functioning of signalling pathways and morphogenesis, and have been implicated in studies on longevity in flies and other organisms.

Results:  Two novel selenoproteins, dselH and dselK, were recently identified in Drosophila melanogaster. We have used RNAi in D. melanogaster embryos and in Schneider S2 cells to inhibit expression of these proteins. We report that inhibition of either dselH or dselK expression significantly reduces viability in embryos. We further show that dselH silencing decreases total anti‐oxidant capacity in embryos and Schneider cells, and increases lipid peroxidation in cells. Conversely, transient expression of dselH in the cell line decreases lipid peroxidation, and reverses the toxic effects of a glutathione‐depleting drug. The latter correlates with sparing of glutathione levels.

Conclusions:  These studies suggest that the well‐known role of selenoproteins in vertebrate anti‐oxidant defenses also extends to include invertebrates.
Characterization of dipping fractures in a transverselyisotropic background
Authors: Grechka V. , Tsvankin I.
Published: December 2004

Although it is believed that natural fracture sets predominantly have near‐vertical orientation, oblique stresses and some other mechanisms may tilt fractures away from the vertical. Here, we examine an effective medium produced by a single system of obliquely dipping rotationally invariant fractures embedded in a transversely isotropic with a vertical symmetry axis (VTI) background rock. This model is monoclinic with a vertical symmetry plane that coincides with the dip plane of the fractures.

Multicomponent seismic data acquired over such a medium possess several distinct features that make it possible to estimate the fracture orientation. For example, the vertically propagating fast shear wave (and the fast converted PS‐wave) is typically polarized in the direction of the fracture strike. The normal‐moveout (NMO) ellipses of horizontal reflection events are co‐orientated with the dip and strike directions of the fractures, which provides an independent estimate of the fracture azimuth. However, the polarization vector of the slow shear wave at vertical incidence does not lie in the horizontal plane – an unusual phenomenon that can be used to evaluate fracture dip. Also, for oblique fractures the shear‐wave splitting coefficient at vertical incidence becomes dependent on fracture infill (saturation).

A complete medium‐characterization procedure includes estimating the fracture compliances and orientation (dip and azimuth), as well as the Thomsen parameters of the VTI background. We demonstrate that both the fracture and background parameters can be obtained from multicomponent wide‐azimuth data using the vertical velocities and NMO ellipses of PP‐waves and two split SS‐waves (or the traveltimes of PS‐waves) reflected from horizontal interfaces. Numerical tests corroborate the accuracy and stability of the inversion algorithm based on the exact expressions for the vertical and NMO velocities.
Azimuth moveout correction for transversely isotropic media
Authors: Alkhalifah Tariq
Published: December 2004

The azimuth moveout (AMO) operator in homogeneous transversely isotropic media with a vertical symmetry axis (VTI), as in isotropic media, has an overall skewed saddle shape. However, the AMO operator in anisotropic media is complicated; it includes, among other things, triplications at low angles. Even in weaker anisotropies, with the anisotropy parameter η= 0.1 (10% anisotropy), the AMO operator is considerably different from the isotropic operator, although free of triplications. The structure of the operator in VTI media (positive η) is stretched (has a wider aperture) compared with operators in isotropic media, with the amount of stretch being dependent on the strength of anisotropy. If the medium is both vertically inhomogeneous, i.e. the vertical velocity is a function of depth (v(z)), and anisotropic, which is a common combination in practical problems, the shape of the operator again differs from that for isotropic media. However, the difference in the AMO operator between the homogeneous and the v(z) cases, even for anisotropic media, is small. Stated simply, anisotropy influences the shape and aperture of the AMO operator far more than vertical inhomogeneity does.
2.5D modelling, inversion and angle migration in anisotropic elastic media
Authors: Foss Stig‐Kyrre , Ursin Bjørn
Published: December 2004

2.5D modelling approximates 3D wave propagation in the dip‐direction of a 2D geological model. Attention is restricted to raypaths for waves propagating in a plane. In this way, fast inversion or migration can be performed. For velocity analysis, this reduction of the problem is particularly useful.

We review 2.5D modelling for Born volume scattering and Born–Helmholtz surface scattering. The amplitudes are corrected for 3D wave propagation, taking into account both in‐plane and out‐of‐plane geometrical spreading. We also derive some new inversion/migration results. An AVA‐compensated migration routine is presented that is simplified compared with earlier results. This formula can be used to create common‐image gathers for use in velocity analysis by studying the residual moveout. We also give a migration formula for the energy‐flux‐normalized plane‐wave reflection coefficient that models large contrast in the medium parameters not treated by the Born and the Born–Helmholtz equation results. All results are derived using the generalized Radon transform (GRT) directly in the natural coordinate system characterized by scattering angle and migration dip. Consequently, no Jacobians are needed in their calculation.

Inversion and migration in an orthorhombic medium or a transversely isotropic (TI) medium with tilted symmetry axis are the lowest symmetries for practical purposes (symmetry axis is in the plane). We give an analysis, using derived methods, of the parameters for these two types of media used in velocity analysis, inversion and migration. The kinematics of the two media involve the same parameters, hence there is no distinction when carrying out velocity analysis. The in‐plane scattering coefficient, used in the inversion and migration, also depends on the same parameters for both media. The out‐of‐plane geometrical spreading, necessary for amplitude‐preserving computations, for the TI medium is dependent on the same parameters that govern in‐plane kinematics. For orthorhombic media, information on additional parameters is required that is not needed for in‐plane kinematics and the scattering coefficients.

Resolution analysis of the scattering coefficient suggests that direct inversion by GRT yields unreliable parameter estimates. A more practical approach to inversion is amplitude‐preserving migration followed by AVA analysis.

SYMBOLS AND NOTATION

A list of symbols and notation is given in Appendix D.
The importance of low atmospheric CO2 and fire in promoting the spread of grasslands and savannas
Authors: BOND W. J. , MIDGLEY G. F. , WOODWARD F. I.
Published: December 2004

The distribution and abundance of trees can be strongly affected by disturbance such as fire. In mixed tree/grass ecosystems, recurrent grass‐fuelled fires can strongly suppress tree saplings and therefore control tree dominance. We propose that changes in atmospheric [CO2] could influence tree cover in such metastable ecosystems by altering their postburn recovery rates relative to flammable herbaceous growth forms such as grasses. Slow sapling recovery rates at low [CO2] would favour the spread of grasses and a reduction of tree cover. To test the possible importance of [CO2]/fire interactions, we first used a Dynamic Global Vegetation Model (DGVM) to simulate biomass in grassy ecosystems in South Africa with and without fire. The results indicate that fire has a major effect under higher rainfall conditions suggesting an important role for fire/[CO2] interactions. We then used a demographic model of the effects of fire on mesic savanna trees to test the importance of grass/tree differences in postburn recovery rates. We adjusted grass and tree growth in the model according to the DGVM output of net primary production at different [CO2] relative to current conditions. The simulations predicted elimination of trees at [CO2] typical of the last glacial period (180 ppm) because tree growth rate is too slow (15 years) to grow to a fire‐proof size of ca. 3 m. Simulated grass growth would produce an adequate fuel load for a burn in only 2 years. Simulations of preindustrial [CO2] (270 ppm) predict occurrence of trees but at low densities. The greatest increase in trees occurs from preindustrial to current [CO2] (360 ppm). The simulations are consistent with palaeo‐records which indicate that trees disappeared from sites that are currently savannas in South Africa in the last glacial. Savanna trees reappeared in the Holocene. There has also been a large increase in trees over the last 50–100 years. We suggest that slow tree recovery after fire, rather than differential photosynthetic efficiencies in C3 and C4 plants, might have been the significant factor in the Late Tertiary spread of flammable grasslands under low [CO2] because open, high light environments would have been a prerequisite for the spread of C4 grasses. Our simulations suggest further that low [CO2] could have been a significant factor in the reduction of trees during glacial times, because of their slower regrowth after disturbance, with fire favouring the spread of grasses.
Microbial characteristics of soils on a latitudinal transect in Siberia
Authors: ŠANTRU˚CˇKOVÁ HANA , BIRD MICHAEL I. , KALASCHNIKOV YEVGENIY N. , GRUND MILAN , ELHOTTOVÁ DANA , ŠIMEK MILOSLAV , GRIGORYEV SERGEY , GLEIXNER GERD , ARNETH ALMUT , SCHULZE ERNST‐DETLEF , LLOYD JON
Published: December 2004

Soil microbial properties were studied from localities on a transect along the Yenisei River, Central Siberia. The 1000 km‐long transect, from 56°N to 68°N, passed through tundra, taiga and pine forest characteristic of Northern Russia. Soil microbial properties were characterized by dehydrogenase activity, microbial biomass, composition of microbial community (PLFAs), respiration rates, denitrification and N mineralization rates. Relationships between vegetation, latitude, soil quality (pH, texture), soil organic carbon (SOC) and the microbial properties were examined using multivariate analysis. In addition, the temperature responses of microbial growth (net growth rate) and activity (soil respiration rate) were tested by laboratory experiments. The major conclusions of the study are as follows:

1. Multivariate analysis of the data revealed significant differences in microbial activity. SOC clay content was positively related to clay content. Soil texture and SOC exhibited the dominant effect on soil microbial parameters, while the vegetation and climatic effects (expressed as a function of latitude) were weaker but still significant. The effect of vegetation cover is linked to SOC quality, which can control soil microbial activity.

2. When compared to fine‐textured soils, coarse‐textured soils have (i) proportionally more SOC bound in microbial biomass, which might result in higher susceptibility of SOC transformation to fluctuation of environmental factors, and (ii) low mineralization potential, but with a substantial part of the consumed C being transformed to microbial products.

3. The soil microbial community from the northernmost study region located within the permafrost zone appears to be adapted to cold conditions. As a result, microbial net growth rate became negative when temperature rose above 5 °C and C mineralization then exceeded C accumulation.
A new assessment of European forests carbon exchanges by eddy fluxes and artificial neural network spatialization
Authors: PAPALE DARIO , VALENTINI RICCARDO
Published: December 2004

Recently flux tower data have become available for a variety of ecosystems under different climatic and edaphic conditions. Although Flux tower data represent point measurements with a footprint of typically 1 km × 1 km they can be used to validate models and to spatialize biospheric fluxes at regional and continental scales. In this paper we present a study where biospheric flux data collected in the EUROFLUX project were used to train a neural network simulator to provide spatial (1 km × 1 km) and temporal (weekly) estimates of carbon fluxes of European forests at continental scale. The novelty of the approach is that flux data were used to constrain and parameterize the neural network structure using a limited number of input driving variables. The overall European carbon uptake from this analysis was 0.47 Gt C yr−1with distinctive differences between boreal and temperate regions. The length of the growing season is longer in the south of Europe (about 32 weeks), compared with north and central Europe, which have a similar length‐growing season (about 27 weeks). A peak in respiration was depicted in spring at continental scale as a coherent signal which parallel the construction respiration increase at the onset of the season as usually shown by leaf level measurements.
Effects of soil temperature on nitric oxide emission from a typical Chinese rice–wheat rotation during the non‐waterlogged period
Authors: ZHENG XUNHUA , HUANG YAO , WANG YUESI , WANG MINGXING , JIN JISHENG , LI LAOTU
Published: December 2004

Measurements of nitric oxide (NO) emission from a typical Chinese rice–wheat rotation are continuously made during the non‐waterlogged period by using an automatic system based on static chamber techniques. A positive correlation exists between NO emission and soil moisture content when surface soil temperature is > 20 °C. The diurnal variability in NO emission is characterized with day‐peak, night‐peak and irregular patterns, which are in close association with wheat growth. The diurnal NO emission under the day‐peak pattern is correlated with the simultaneously observed surface soil temperature, whereas that under the night‐peak and irregular pattern is dependent on surface soil temperature at 7 ± 2 and 3 ± 2 h before NO observation, respectively. The effect of soil temperature on NO emission is well described by F = α·eβ·T, where F is NO flux, T soil temperature, and α and b empirical coefficients. The parameter Q10; that is, the change in NO emission per 10 °C soil temperature, is correlated with the rates of fertilizer‐N application. An approach orientated from the Arrhenius equation, , is developed in order to predict diurnal NO emission, where TK is the daily average soil temperature, ΔTK the deviation of soil temperature from the daily average, Ea the apparent activation energy, R the gas constant, t a given time within the one‐day cycle, t delayed time for appearance of the diurnal NO emission peak, and k an empirical coefficient. Based on the results, the authors recommend that intermittent measurement of NO emission from a similar ecosystem would be best taken around 17:00. The molar ratio of NO/N2O over the non‐waterlogged period is > 1 when soil moisture content was less than the field capacity, suggesting that NO emission was mainly derived from nitrification under this condition.
Sex‐specific physiological and growth responses to elevated atmospheric CO2 in Silene latifolia Poiret
Authors: WANG XIANZHONG , GRIFFIN KEVIN L.
Published: December 2004

Dioecy is found in nearly half of the angiosperm families, but little is known about how rising atmospheric CO2 concentration will affect male and female individuals of dioecious species. We examined gender‐specific physiological and growth responses of Silene latifolia Poiret, a widespread dioecious species, to a doubled atmospheric CO2 concentration in environmentally controlled growth chambers. Elevated CO2 significantly increased photosynthesis in both male and female plants and by a similar magnitude. Males and females did not differ in net photosynthetic rate, but females had significantly greater biomass production than males, regardless of CO2 concentrations. Vegetative mass increased by 39% in males and in females, whereas reproductive mass increased by 82% in males and 97% in females at elevated CO2. As a result, proportionately more carbon was allocated to reproduction in male and female plants at elevated CO2. Higher CO2 increased individual seed mass significantly, but had no effect on the number or mass of seeds per female plant. Our results demonstrated that rising atmospheric CO2 will alter the allocation patterns in both male and female S. latifolia Poiret plants by shifting proportionally more photosynthate to reproduction.
Assessing the eddy covariance technique for evaluating carbon dioxide exchange rates of ecosystems: past, present and future
Authors: BALDOCCHI DENNIS D.
Published: December 2004

The eddy covariance technique ascertains the exchange rate of CO2 across the interface between the atmosphere and a plant canopy by measuring the covariance between fluctuations in vertical wind velocity and CO2 mixing ratio. Two decades ago, the method was employed to study CO2 exchange of agricultural crops under ideal conditions during short field campaigns. During the past decade the eddy covariance method has emerged as an important tool for evaluating fluxes of carbon dioxide between terrestrial ecosystems and the atmosphere over the course of a year, and more. At present, the method is being applied in a nearly continuous mode to study carbon dioxide and water vapor exchange at over a hundred and eighty field sites, worldwide. The objective of this review is to assess the eddy covariance method as it is being applied by the global change community on increasingly longer time scales and over less than ideal surfaces.

The eddy covariance method is most accurate when the atmospheric conditions (wind, temperature, humidity, CO2) are steady, the underlying vegetation is homogeneous and it is situated on flat terrain for an extended distance upwind. When the eddy covariance method is applied over natural and complex landscapes or during atmospheric conditions that vary with time, the quantification of CO2 exchange between the biosphere and atmosphere must include measurements of atmospheric storage, flux divergence and advection.

Averaging CO2 flux measurements over long periods (days to year) reduces random sampling error to relatively small values. Unfortunately, data gaps are inevitable when constructing long data records. Data gaps are generally filled with values produced from statistical and empirical models to produce daily and annual sums of CO2 exchange. Filling data gaps with empirical estimates do not introduce significant bias errors because the empirical algorithms are derived from large statistical populations. On the other hand, flux measurement errors can be biased at night when winds are light and intermittent. Nighttime bias errors tend to produce an underestimate in the measurement of ecosystem respiration.

Despite the sources of errors associated with long‐term eddy flux measurements, many investigators are producing defensible estimates of annual carbon exchange. When measurements come from nearly ideal sites the error bound on the net annual exchange of CO2 is less than ±50 g C m−2 yr−1. Additional confidence in long‐term measurements is growing because investigators are producing values of net ecosystem productivity that are converging with independent values produced by measuring changes in biomass and soil carbon, as long as the biomass inventory studies are conducted over multiple years.
Carbon distribution of a well‐ and poorly‐drained black spruce fire chronosequence
Authors: WANG CHUANKUAN , BOND‐LAMBERTY BEN , GOWER STITH T.
Published: December 2004

The objective of this study was to quantify carbon (C) distribution for boreal black spruce (Picea mariana(Mill.) BSP) stands comprising a fire chronosequence in northern Manitoba, Canada. The experimental design included seven well‐drained (dry) and seven poorly‐drained (wet) stands that burned between 1998 and 1850. Vegetation C pools (above‐ground + below‐ground) steadily increased from 1.3 to 83.3 t C ha−1for the dry chronosequence, and from 0.6 to 37.4 t C ha−1for the wet chronosequence. The detritus C pools (woody debris + forest floor) varied from 10.3 to 96.0 t C ha−1and from 12.6 to 77.4 t C ha−1for the dry and wet chronosequence, respectively. Overstorey biomass, mean annual biomass increment (MAI), woody debris mass, and litterfall were significantly greater (α = 0.05) for the dry stands than for the wet stands, but the bryophyte, understorey, and forest floor C pools were significantly less for the dry than for the wet stands. The root mass ratio decreased with stand age until 37 years after fire, was fairly constant thereafter, and was not significantly affected by soil drainage. The C pools of the overstorey and bryophyte tended to increase with stand age. Foliage biomass, litterfall, and MAI (for the dry stands) peaked at 71 years after fire and declined in the oldest stands. The results from this study illustrate that the effects of disturbance and edaphic conditions must be accounted for in boreal forest C inventories and C models. The appropriateness of using chronosequences to examine effects of wildfire on ecosystem C distribution is discussed.
Estimation of nitrous oxide, nitric oxide and ammonia emissions from croplands in East, Southeast and South Asia
Authors: YAN XIAOYUAN , AKIMOTO HAJIME , OHARA TOSHIMASA
Published: December 2004

Agricultural activities have greatly altered the global nitrogen (N) cycle and produced nitrogenous gases of environmental significance. More than half of all chemical N fertilizer produced globally is used in crop production in East, Southeast and South Asia, where rice is central to nutrition. Emissions of nitrous oxide (N2O), nitric oxide (NO) and ammonia (NH3) from croplands in this region were estimated by considering background emission and emissions resulting from N added to croplands, including chemical N, animal manure, biologically fixed N and N in crop residues returned to fields. Background emission fluxes of N2O and NO from croplands were estimated to be 1.22 and 0.57 kg N ha−1 yr−1, respectively. Separate fertilizer‐induced emission factors were estimated for upland fields and rice fields. Total N2O emission from croplands in the study region was estimated to be 1.19 Tg N yr−1, with 43% contributed by background emissions. The average fertilizer‐induced N2O emission, however, accounts for only 0.93% of the applied N, which is less than the default IPCC value of 1.25%, because of the low emission factor from paddy fields. Total NO emission was 591 Gg N yr−1 in the study region, with 40% from background emissions. The average fertilizer‐induced NO emission factor was 0.48%. Total NH3 emission was estimated to be 11.8 Tg N yr−1. The use of urea and ammonium bicarbonate and the cultivation of rice led to a high average NH3 loss rate from chemical N fertilizer in the study region. Emissions were displayed at a 0.5° × 0.5° resolution with the use of a global landuse database.
Cutting frequency and stubble height of reed canary grass (Phalaris arundinacea L.): influence on quality and quantity of biomass for biogas production
Authors: Geber U.
Published: December 2004

Abstract Reed canary grass (RCG) used for land treatment of waste water can serve as a substrate for biogas production. The aim of this experiment was to study the effects of two, three or four cuts per year to stubble heights of 5, 12·5 or 20 cm on the digestibility and yield of digestible organic matter (DOM) of RCG. Both dry‐matter yield and the yield of DOM decreased with more than two cuts per year. Height of cutting had no effect on the digestibility of the regrowth harvested from the different cutting regimes. Increased height of cutting resulted in increased dry‐matter production and therefore also of increased DOM yield in the regrowth harvested from the four‐cut regime. The total DOM yield from the four‐cut regime was, however, only 0·84 of the DOM yield from the two‐cut regime.
Effect of American bison (Bison bison L.) on the recovery and germinability of seeds of range forage species
Authors: Gökbulak F.
Published: December 2004

Abstract The effect of passage through the digestive tract of Bison bison on the recovery and germinability of undamaged passed seeds of Pseudoroegneria spicata, Elymus cinereus, Oryzopsis hymenoides, Stipa comata, Balsamorhiza sagittata and Sphaeralcea coccinea was tested. Recovery of undamaged passed seeds peaked 2 days after ingestion and then decreased to the lowest level on day 5 of sample collection for all species used, but the pattern of seed passage through time significantly differed among species. Recovery of passed seeds was greatest for round‐shaped, hard seed‐coated O. hymenoides and lowest for largest seed‐sized B. sagittata. The digestive tract of B. bison did not break seed dormancy of O. hymenoides, S. comata, S. coccinea or B. sagittata. Germination percentage of P. spicata and E. cinereus seeds decreased compared with unpassed seeds of the same species.
The growth of roots of perennial, Italian, hybrid and annual ryegrasses through a high‐strength root medium
Authors: Crush J. R. , Ouyang L. , Eerens J. P. J. , Stewart A. V.
Published: December 2004

Abstract A test for root penetration through a wax disc of known hardness was developed and used with twenty‐five cultivars and twenty‐one breeding lines of perennial, Italian, hybrid and annual ryegrasses. After 42 days, the number of roots reaching the wax disc and the number penetrating the disc were counted. Root diameters were measured using image analysis. The proportion of root penetrations ranged from 0·06 to 0·39 across the cultivars and breeding lines, with substantial variation between replicates and cultivars. Diploid perennial cultivars had the thinnest roots, and there were no consistent differences in root diameter between perennial breeding lines, hybrid ryegrasses and Italian ryegrasses. Roots that penetrated the wax disc increased in diameter, by 0·60 on average, a few millimetres above the wax, and through the wax disc. Diameters below the wax disc were the same as those above the zone of impeded root growth. The increase was caused by an increase in size of the parenchyma cells of the root cortex. An experiment with partially and completely impeded root growth showed that impedance did not change root diameter of new roots, or the distribution of root mass between impeded and unimpeded halves of a root system for plants up to 10 weeks old.
Protein degradation and fermentation characteristics of unwilted red clover and alfalfa silage harvested at various times during the day
Authors: Owens V. N. , Albrecht K. A. , Muck R. E.
Published: December 2004

Extensive proteolysis during fermentation of high‐protein legumes reduces dietary N‐use efficiency in ruminants. Research has demonstrated that enhancing the level of fermentable carbohydrates in crops entering the silo may reduce protein degradation by increasing the rate of decline in pH. The objective was to evaluate whether delaying cutting time during the day, to allow accumulation of total non‐structural carbohydrates (TNC), would inhibit proteolysis in the silo. Red clover (Trifolium pratense L.) and alfalfa (Medicago sativa L.) were harvested at 06.00, 10.00, 14.00 and 18.00 hours in 1993, 1994 and 1995, and ensiled without wilting. TNC accumulated in fresh forage during the day, with starch accounting for more than 0·50 of the daily change in TNC in fresh herbage of both species, except in red clover in 1995. The level of TNC in fresh forage did not consistently affect the extent of protein degradation in either species and, in all instances, alfalfa underwent more extensive proteolysis than red clover. Silage pH typically decreased and starch concentration increased as cutting time was delayed from 06.00 to 18.00 hours. Although the extent of proteolysis was largely unaffected by inherent increases in TNC, harvesting in the afternoon did provide several benefits including increased dry‐matter content, lower silage pH and higher starch concentrations. Effluent production is a concern in any unwilted silage system; there was therefore an added advantage of lower moisture content from cutting in the afternoon.
Effects of the colour and thickness of polyethylene film on ensiling conditions and silage quality of chopped maize, as investigated under ambient conditions and in mini‐silos
Authors: Snell H. G. J. , Oberndorfer C. , Lücke W. , Van den Weghe H. F. A.
Published: December 2004

Abstract The influences of variations in thickness and colour of agricultural plastic film on silage preservation conditions and silage quality were investigated. Thirty cylindrical plastic containers (mini‐silos; 0·3 m3) were filled with chopped maize and covered with five different types of film (90 µm white, 150 µm transparent, 150 µm white, 150 µm black, 200 µm white). Four mini‐silos of each variant were placed in the open air, and two were housed and subjected to a test procedure. The maximum storage period of silages was 104 d. The surface temperature of the films was found to be strongly dependent on the type of sheet. The temperatures inside the mini‐silos directly under the film differed significantly, whereas this effect was not recorded in the centre of the mini‐silos. In all, the differences were quantitatively small. Results of the chemical analysis of silages did not reveal any significant influence of film type. This was also the case when restricting the analysis to the uppermost silage layer. These findings are discussed against the background of the relatively small temperature differences and likely effects on gas permeability. On the basis of the results presented, it is concluded that, under the conditions of the experiment, well‐preserved forage of high nutritive value can be produced with silo sheets of differing colour, as well as with those of reduced thickness. Adequate mechanical robustness has to be ensured, if there is a reduction in film thickness.
Acquired inhibitor to factor VIII: report of two unusual cases
Authors: PATHARE A. V. , GHAMANDE S. , FERNANDES S. , BHATIA S. , JIJINA F. , SHETTY S. , GHOSH K. , MOHANTY D.
Published: December 2004

Summary. The present report describes two unusual cases of bleeding due to development of inhibitor against factor VIII. One of the patients was known to have severe haemophilia B (factor IX < 1%) and the other, a healthy male of 46 years, spontaneously started to bleed and was found to have developed inhibitors to factor VIII:C along with other autoantibodies. Development of inhibitors to coagulation factors is a serious clinical problem in de‐veloped countries and is more so in developing countries where treatment options are often limited.
Factor X and its deficiency states
Authors: PERRY D. J.
Published: December 2004

Summary. Factor X is one of the vitamin‐K‐dependent serine proteases. As a result of its position at the convergence of the intrinsic and extrinsic pathways of the clotting cascade, it plays a crucial role in blood coagulation. Factor X interacts with components of both pathways of coagulation, leading to its activation and the formation of the prothrombinase complex.

The gene for factor X has been cloned and sequenced and maps to the long arm of chromosome 13, approximately 2.8 kb downstream of the factor VII gene. Each of the exons of factor X encodes a specific functional domain within the protein. In terms of its gene structure and amino acid sequence, factor X shows significant homology with other vitamin‐K‐dependent clotting factors, suggesting an origin in some common ancestral protein.

Factor X deficiency is one of the rarest of the inherited coagulation disorders. Such deficiencies are inherited in an autosomal recessive manner and are characterized by a variable bleeding tendency. In its homozygous form, factor X deficiency has an estimated prevalence of 1:500 000 but in its heterozygous form it has an estimated frequency of ∼1:500 although affected individuals are often clinically asymptomatic.

Acquired deficiencies of factor X are uncommon and in isolation are seen most frequently in patients with amyloidosis and in association with upper respiratory tract infections.

Treatment of the deficiency state involves factor X replacement with either fresh frozen plasma or prothrombin complex concentrates. However, the latter may be associated with an increased risk of thrombosis.
Does avascular necrosis cause collapse of the dome of the talus in severe haemophilia?
Authors: MACNICOL M. F. , LUDLAM C. A.
Published: December 2004

Arthropathy of the ankle joint is commonly observed in people with severe haemophilia. A review of the radiological appearance of ankle arthropathy provides evidence that the changes in the talar bone of the ankle joint are probably due to avascular necrosis. This may arise due to impairment to the arterial supply, as it enters the talar neck, secondary to the increased pressure at the time of haemarthroses.
Anaphylactic response to factor IX replacement therapy in haemophilia B patients: complete gene deletions confer the highest risk
Authors: THORLAND E. C. , DROST J. B. , LUSHER J. M. , WARRIER I. , SHAPIRO A. , KOERPER M. A. , DIMICHELE D. , WESTMAN J. , KEY N. S. , SOMMER S. S.
Published: December 2004

Haemophilia B is an X‐linked recessive coagulopathy due to mutations in the factor IX gene. Occasionally, patients receiving factor IX replacement therapy develop inhibiting antibodies to the factor IX protein, and it has been recently documented that a subset of these patients have had anaphylactic responses to factor IX replacement therapy in association with the development of inhibiting antibodies. To determine the relationship between mutation type and the risk of anaphylaxis, eight unrelated patients from families in whom anaphylaxis had occurred were genotyped. The mutations were compared to those in 550 haemophilia B patients and to those in 276 patients with clinically severe disease. Individuals with complete gene deletions were found to be at greatest risk for anaphylaxis, with an estimated risk of 26% or greater. Anaphylaxis was less likely to occur in patients with protein truncation mutations or partial gene deletions and least likely to occur with missense mutations. Genotypes can help physicians and patients anticipate the likelihood of anaphylaxis, a potentially life‐threatening complication of factor IX replacement therapy. The very high risk of anaphylaxis associated with a complete gene deletion suggests that the lack of expression of a partial protein product may predispose to anaphylaxis and/or that the absence of a closely linked, codeleted gene enhances the anaphylactic immune response.
Guidelines on the selection and use of therapeutic products to treat haemophilia and other hereditary bleeding disorders
Authors:   United Kingdom Haemophilia Centre Doctors’ Organisation (UKHCDO)
Published: December 2004

Summary. Evidence based guidelines are presented on the selection and use of therapeutic products to treat haemophilia. These guidelines offer advice based on the best published scientific and medical information. They will be reviewed regularly by UKHCDO Advisory Committee. Included are details of therapeutic products available in the UK to treat patients with haemophilia and other bleeding disorders and the background information on which the recommendations are based are presented.
Providing assisted reproductive care to male haemophiliacs infected with human immunodeficiency virus: preliminary experience
Authors: Peña J. E. , Klein J. , Thornton M. H. , Sauer M. V.
Published: December 2004

Summary.  Outlined is our experience with couples in whom the male was both human immunodeficiency virus (HIV) seropositive and a haemophiliac who underwent assisted reproductive technologies (ART) in order to attain family goals while minimizing the risk of HIV transmission. We report their demographics, attitudes towards assisted reproduction, and ART performance and outcomes. The study included HIV serodiscordant couples (n = 11) who underwent ART at a university‐based infertility practice from August 1997 to May 2002. Prior to treatment, couples prospectively completed a survey regarding their demographics and attitudes towards assisted reproduction. All couples underwent ART and pregnancy outcomes were analysed. The majority of the patients were fully employed, college‐educated, in good health, married and motivated to have a child while minimizing the risk of HIV transmission. Eleven couples underwent 25 cycles of ART [19 in vitro fertilization (IVF) cycles; five frozen embryo transfer cycles; and one oocyte donation cycle] resulting in nine successful pregnancies. The ongoing/delivered pregnancy rate per initiated IVF cycle was 42.1% per embryo transfer. Eight of 11 (72.7%) couples achieved a successful pregnancy. More than half (six of 11; 54.5%) the couples conceived during their initial attempt. Four of nine (44.4%) pregnancies were multiple gestations, including three sets of triplets. All female recipients tested seronegative for HIV at 3 and 6 months post‐embryo transfer. All delivered babies (n = 8) tested seronegative for HIV at birth and 3 months postpartum. Four pregnancies are currently ongoing. ART should be considered for HIV serodiscordant couples with haemophilia who desire to have children in order to minimize the risk of viral infection.
Prophylaxis in factor IX deficiency product and patient variation
Authors: Kisker C.T. , Eisberg A. , Schwartz B. ,   the Mononine Study Group
Published: December 2004

Summary.  To determine the dosing needed to maintain a prophylactic level of factor IX (FIX) ≥2%, 15 non‐inhibitor severe (≤1% FIX) deficient subjects participated in a double‐blind, two‐period crossover study to assess the pharmacokinetics of two FIX concentrates, Mononine (pd‐FIX), an ultra‐high‐purity plasma‐derived concentrate, and BeneFix (r‐FIX), a recombinant product. The median recovery in the pd‐FIX group was 1.67 IU dL−1 per IU kg−1±1.07 vs. 0.86 IU dL−1 per IU kg−1±0.32 in the r‐FIX group (P = 0.0002). The median half‐life for pd‐FIX was 12.9 ±1.7 h compared with 13.7 ± 2.9 h for r‐FIX (P = 0.016). Fitted dose activity curves were computer‐simulated to depict multiple‐dose activity curves for each patient with each product that would maintain prophylactic levels of ≥2%. Based on pharmacokinetic analysis the median amount of concentrate needed to maintain a prophylactic level ≥2% for 30 days when administered every third day is 677 IU kg−1 pd‐FIX (range 388–6005 IU kg−1 pd‐FIX) compared with 1168 IU kg−1 r‐FIX (range 268–13085 IU kg−1 r‐FIX). The median cost for 30 days of prophylaxis of an average 25‐kg 8‐year‐old child at the current University of Iowa Price ($0.87 Mononine/$0.86 BeneFix as of December 2002) if given every third day would be $19 972 and $34 456 for r‐FIX. However, because of wide inter‐patient variability in recovery and half‐life, pharmacokinetic evaluation of each patient is necessary to determine the appropriate dosing schedule and product best suited for prophylaxis.