bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cellular Pathways Regulating Responses to Compatible and Self-Incompatible Pollen inBrassicaandArabidopsisStigmas Intersect at Exo70A1, a Putative Component of the Exocyst Complex
Authors: Samuel Marcus A. , Chong Yolanda T. , Haasen Katrina E. , Aldea-Brydges May Grace , Stone Sophia L. , Goring Daphne R. 
Published: September 2009

AbstractIn the Brassicaceae, compatible pollen–pistil interactions result in pollen adhesion to the stigma, while pollen grains from unrelated plant species are largely ignored. There can also be an additional layer of recognition to prevent self-fertilization, the self-incompatibility response, whereby self pollen grains are distinguished from nonself pollen grains and rejected. This pathway is activated in the stigma and involves the ARM repeat–containing 1 (ARC1) protein, an E3 ubiquitin ligase. In a screen for ARC1-interacting proteins, we have identified Brassica napus Exo70A1, a putative component of the exocyst complex that is known to regulate polarized secretion. We show through transgenic studies that loss of Exo70A1 in Brassica and Arabidopsis thaliana stigmas leads to the rejection of compatible pollen at the same stage as the self-incompatibility response. A red fluorescent protein:Exo70A1 fusion rescues this stigmatic defect in Arabidopsis and is found to be mobilized to the plasma membrane concomitant with flowers opening. By contrast, increased expression of Exo70A1 in self-incompatible Brassica partially overcomes the self pollen rejection response. Thus, our data show that the Exo70A1 protein functions at the intersection of two cellular pathways, where it is required in the stigma for the acceptance of compatible pollen in both Brassica and Arabidopsis and is negatively regulated by Brassica self-incompatibility.
Postdispersal seed predation and seed viability in forest soils: implications for the regeneration of tree species in Ethiopian church forests
Authors: Wassie Alemayehu , Bekele Tesfaye , Sterck Frank , Teketay Demel , Bongers Frans 
Published: September 2009

AbstractAlmost all dry Afromontane forests of Northern Ethiopia have been converted to agricultural, grazing or scrub lands except for small fragments left around churches (‘Church forests’). Species regeneration in these forests is limited. We investigated (i) how intense postdispersal seed predation was in church forest, and if this seed predation varied with species and/or habitat, and (ii) for how long tree seeds maintained their viability while buried in forest soil. In the seed predation experiment, we monitored seeds of six tree species in four habitats for a period of 14 weeks (the peak seeding season). In the seed viability experiment, we assessed seed viability of five species in four habitats after being buried 6, 12, or 18 months. Ninety‐two percent of the tree seeds were predated within 3.5 months. Predation was mainly dependent on species whereas habitat had a weaker effect. Seed viability decreased sharply with burial time in soil for all species except for Juniperus. To minimize seed availability limitation for regeneration of such species in the forest, the standing vegetation needs to be persistently managed and conserved for a continuous seed rain supply. Additional seed sowing, and seed and seedling protection (by e.g. animal exclosures) may increase successful regeneration of important species in these forests.
Spatial variations in the composition and abundance of zooplankton in the Bahir Dar Gulf of Lake Tana, Ethiopia
Authors: Imoobe Tunde Ohiokhioya Thadeus , Christopher Akoma Osondu 
Published: September 2009

AbstractThe zooplankton in the littoral and open water zones of Bahir Dar Gulf, Lake Tana, collected in June and July 2007, were investigated using basic statistical measurement of diversity indices and one way analysis of variance to characterize the zooplankton fauna, with respect to its composition, abundance and spatial distribution patterns. The zooplankton composition was typical of a tropical freshwater lake, with a total of 44 species made up of sixteen rotifers, sixteen c1adocerans and twelve copepods and their developing stages in the following order of dominance; Rotifera > Cladocera > Cylopoida > Calanoida. Variation in spatial distribution was noticeable, the abundance of zooplankton was significantly higher (P < 0.05) at the littoral zone (Stations 2 and 3) than the open water (Station 1) as a result of the preponderance of the small‐bodied nauplii stages, small rotifers and c1adocerans particularly Bosmina longirostris. Species richness, evenness, and diversity also increased as abundance increased in the littoral zones of the lake. The rotifers, particularly the brachionids Keratella and Brachionus spp., which are considered good indicators of lake trophic status constituted the dominant zooplankton group in terms of abundance and diversity, thus indicating that the lake has a high fisheries potential.
Acoustic estimation of wildlife abundance: methodology for vocal mammals in forested habitats
Authors: Thompson Mya E. , Schwager Steven J. , Payne Katharine B. , Turkalo Andrea K. 
Published: September 2009

AbstractHabitat loss and hunting pressure threaten mammal populations worldwide, generating critical time constraints on trend assessment. This study introduces a new survey method that samples continuously and non‐invasively over long time periods, obtaining estimates of abundance from vocalization rates. We present feasibility assessment methods for acoustic surveys and develop equations for estimating population size. As an illustration, we demonstrate the feasibility of acoustic surveys for African forest elephants (Loxodonta africana cyclotis). Visual surveys and vocalizations from a forest clearing in the Central African Republic were used to establish that low‐frequency elephant calling rate is a useful index of elephant numbers (linear regressionP < 0.001,radj.2 = 0.58). The effective sampling area was 3.22 km2per acoustic sensor, a dramatic increase in coverage over dung survey transects. These results support the use of acoustic surveys for estimating elephant abundance over large remote areas and in diverse habitats, using a distributed network of acoustic sensors. The abundance estimation methods presented can be applied in surveys of any species for which an acoustic abundance index and detection function have been established. This acoustic survey technique provides an opportunity to improve management and conservation of many acoustically‐active taxa whose populations are currently under‐monitored.
Preliminary investigations into a potential ant invader in Kruger National Park, South Africa
Authors: Sithole Hendrik , Smit Izak P.J. , Parr Catherine L. 
Published: September 2009

AbstractThe super‐abundance of Lepisiota incisa (Forel) in settlement areas of Kruger National Park, South Africa has raised concerns that it might be exotic and could negatively impact on natural ecosystems. We documented the current distribution of this ant species around the main settlement in Kruger, assessed how ant diversity varies across habitats, and investigated potential mechanisms facilitating dominance by L. incisa. Around the main camp of Skukuza, pitfall traps were set in five habitats differing in anthropogenic influence. Baiting trails were conducted to determine whether L. incisa and native ants differed in numerical and behavioural dominance. Aggression assays were performed on L. incisa to provide information on colony structure. Although L. incisa was found in all habitats, it had a significantly higher abundance in gardens and appears confined to human‐disturbed areas. It was numerically dominant recruiting more workers to food baits than all other ant species combined. Aggression levels were low between most nests of L. incisa indicating a potential supercolony structure. More information is urgently needed on the genetics, physiology and origins of L. incisa, and monitoring of its current distribution is recommended. This species warrants attention because there may be significant potential for overseas invasion.
Plant species richness–environment relationships across the Subantarctic–Patagonian transition zone
Authors: Speziale Karina Lilian , Ruggiero Adriana , Ezcurra Cecilia 
Published: September 2009

AbstractAim  To evaluate the relative importance of climate, productivity, environmental heterogeneity, biotic associations and habitat use by cattle to account for the species richness of trees, shrubs and herbs across the Subantarctic–Patagonian transition.Location  An area of c. 150 × 150 km, within the transition zone between the Subantarctic and Patagonian subregions on the eastern slope of the Andes (c. 39–42° S, 70–72° W).Methods  All vascular plants found at each one of 50 (10 × 10 m) sampling plots were counted to estimate the local tree, shrub and herb species richness. Path analysis was used to evaluate the relationship between the richness of the three life‐forms and plant cover, dried litter biomass, mean annual temperature, annual precipitation, daily temperature range, substrate heterogeneity and number of faecal pats. Principal coordinates of neighbour matrices was used to model the spatial autocorrelation of the data.Results  Total plant species richness showed a unimodal pattern of spatial variation across the transition. Richness responded positively to indirect effects of precipitation mediated through plant cover, but there was a negative overall effect of precipitation on richness towards the west of the transition, most strongly for trees. An increase in substrate heterogeneity promoted a local increase in herb and shrub richness; the richness of trees increased in sites with steeper slopes. Canopy closure had a direct negative impact on herb richness; it also increased the local accumulation of litter, which negatively affected shrub and herb richness. The impact of habitat use by cattle negatively affected herb richness in areas to the east of the biogeographical transition.Main conclusions  We suggest that the importance of indirect climatic effects mediated by vegetation cover can account for species richness patterns across this transition, most strongly for woody species, which supports the productivity hypothesis. The southern temperate forests towards the west may represent a deviation from the predictions of the water–energy dynamics hypothesis. Dissimilar spatial patterns of variation in the richness of woody and herbaceous species, and their different responses to climatic and heterogeneity variables across the transition, suggest that plant life‐form influences the plant species richness–environment relationships.
Immigration history of amphidromous species on a Greater Antillean island
Authors: Cook Benjamin D. , Pringle Catherine M. , Hughes Jane M. 
Published: September 2009

AbstractAim  To use molecular data to test for dispersal structuring in the immigration history of an amphidromous community on an island.Location  The Caribbean island of Puerto Rico.Methods  Mitochondrial DNA sequences were obtained from 11 amphidromous species, including shrimps, fish and a gastropod, sampled from throughout the island. The timing of population expansion (TE) in each species was calculated using nucleotide variation and molecular clock dating methods. The order of species accumulation was then reconstructed (oldest to most recent estimate for TE), and groups of species with non‐overlapping estimates for TE were identified. The temporal span and average immigration rate for each group were calculated and compared with expectations of two previously published models of island immigration [the ‘dispersal‐structured model of island recolonization’ (Whittaker & Jones, Oikos, 1994, 69, 524–529), which predicts short phases of rapid immigration followed by extended phases with relatively slow immigration rates; and the ‘colonization window hypothesis’ (Carine, Taxon, 2005, 54, 895–903), which suggests that opportunities for island colonization are temporally constrained to discrete waves of colonization].Results  The molecular data indicated the immigration history of Puerto Rican amphidromous fauna from the late Pleistocene through the Holocene and identified two groups of species with non‐overlapping estimates for TE and one group that overlapped with the other two groups. The temporal span, average immigration rate and lack of discreteness between all three groups indicated a continuum of immigration rather than distinct phases of species arrivals.Main conclusions  This study did not support the expectations of the immigration models and suggested that amphidromous species from Puerto Rico comprise a single class of marine‐based dispersers. The immigration sequence we report probably reflects a recolonization chronology in this community, in keeping with the notion of species turnover through time. Four areas of future research into the immigration history of amphidromous species on islands are identified, and indicated the possibility that equilibrium processes govern long‐term community change in amphidromous biota on islands.
Renal function assessed by two different formulas and incidence of myocardial infarction and death in middle‐aged men and women
Authors: Holzmann M. J. , Ivert T. , Jungner I. , Nordqvist T. , Walldius G. , Östergren J. , Hammar N. 
Published: September 2009

Abstract.  Holzmann MJ, Ivert T, Jungner I, Nordqvist T, Walldius G, Östergren J, Hammar N (Karolinska University Hospital, Institute of Environmental Medicine, King Gustaf V Research Institute, Karolinska Institutet; Stockholm; AstraZeneca Sverige AB, Södertälje; AstraZeneca Research & Development, Mölndal, Sweden). Renal function assessed by two different formulas and incidence of myocardial infarction and death in middle‐aged men and women. J Intern Med 2010; 267: 357–369.Background.  Chronic kidney disease predicts mortality in the general population, but less is known about the association with incidence of first myocardial infarction. We evaluated glomerular filtration rates (GFR) estimated by the Modification of Diet in Renal Disease study (GFR‐MDRD) equation and the Mayo formula (GFR‐Mayo) as predictors of myocardial infarction and death.Methods.  In 571 353 Swedish men and women, undergoing health controls, with mean age 45 years, and no previous myocardial infarction, hazard ratios were calculated to assess the association between renal function and incidence of myocardial infarction and all‐cause mortality, respectively. Glomerular filtration rate 60–90, 30–60 and <30 mL per minute per 1.73 m2, was defined as mildly, moderately and severely decreased GFR, respectively.Results.  There were 19 510 myocardial infarctions and 56 367 deaths during 11.6 years of follow‐up. Hazard ratios (and 95% confidence intervals) for myocardial infarction, using GFR‐Mayo were 1.11 (1.06–1.16) for mildly, 1.32 (1.18–1.48) for moderately and 2.54 (1.90–3.40) for severely decreased GFR. The corresponding figures for GFR‐MDRD were 1.01 (0.96–1.05), 1.23 (1.14–1.32) and 2.49 (1.85–3.35). Mortality was increased at all levels of reduced GFR‐Mayo and at moderately or severely decreased GFR‐MDRD.Conclusions.  Already mildly decreased GFR increase the risk of myocardial infarction and death in the general population. The association with adverse outcomes is stronger when GFR‐Mayo rather than GFR‐MDRD is used to assess renal function.
Immunization with Cry1Ac from Bacillus Thuringiensis Increases Intestinal IgG Response and Induces the Expression of FcRn in the Intestinal Epithelium of Adult Mice
Authors: Verdin‐Terán S. L. , Vilches‐Flores A. , Moreno‐Fierros L. 
Published: September 2009

AbstractWe have shown that Cry1Ac protoxin from Bacillus thuringiensis is a potent mucosal and systemic immunogen with adjuvant properties. Interestingly, we have observed that Cry1Ac preferentially induces high specific IgG responses in intestinal fluid when it is intraperitoneally administered to mice; therefore, in the present study, we used this protocol, as a model to address the influence of systemic immunization on the induction of the intestinal IgG response. The data shown indicate that upon intraperitoneal immunization with Cry1Ac, significant intestinal specific IgG cell responses were produced in the lamina propria, accompanied by an increased frequency of intestinal IgG+ lymphocytes and epithelial cells containing IgG. Considering that FcRn is the receptor responsible for the transport of IgG in neonatal intestinal epithelia, but it is developmentally downregulated in the rodent intestine, we analysed whether upon intestinal IgG induction, FcRn mRNA expression was induced in intestinal epithelial cells, of adult mice. Whereas in intestinal epithelia of unimmunized adult mice FcRn mRNA was not detected, in Cry1Ac immunized mice it was expressed, although the level was lower in comparison with that found in neonatal epithelia. Then using flow cytometry and immunofluorescence we confirmed that the expression of the protein FcRn was induced in the intestines of adult immunized mice especially in the large intestine. Finally, we found that Cry1Ac also increased FcRn expression in isolated intestinal epithelial cells stimulated in vitro. The outcomes suggest that the expression of FcRn in intestinal epithelium might be reactivated upon immunization, and possibly facilitate IgG transport.
Structural Difference in the Complement Activation Site of Human IgG1 and IgG3
Authors: Michaelsen T. E. , Sandlie I. , Bratlie D. B. , Sandin R. H. , Ihle O. 
Published: September 2009

AbstractThe C1q binding epicentre on IgG molecules involves residues Asp270, Lys322, Pro329 and Pro331 in the CH2 domain. IgG1 and IgG3 are usually the most efficient of the four human IgG subclasses in activating complement and they both share all these residues. To reveal possible differences in the structural requirement for complement activation, we created a number of NIP (5‐iodo‐4‐hydroxy‐3‐nitro‐phenacetyl) specific IgG1 and IgG3 antibodies with parallel mutations in or near the putative C1q binding site. The mutants were tested simultaneously for antibody induced, antibody‐dependent complement‐mediated lysis (ADCML) at high and low antigen concentration on the target cells using sera of human, rabbit and guinea pig as complement source. In addition, we tested the antibodies against target cells decorated with the NP hapten, which has 10‐fold lower affinity for the antibodies compared to the NIP hapten. We also used ELISA methods to measure complement activation. We observed a clear difference between IgG1 and IgG3 localized to residues Asp270, Leu334, Leu335. For all these residues, and especially for Asp270, IgG1 was heavily reduced in complement activation, while IgG3 was only moderated reduced, by alanine substitution. This difference was independent of the long hinge region of IgG3, demonstrated by hinge region truncation of this isotype such that it resembles that of IgG1. This report indicates the presence of structural differences between human IgG1 and IgG3 in the C1q binding site, and points to a specialization of the two isotypes with respect to complement activation.
The relationship between birth with a health professional and maternal mortality in observational studies: a review of the literature
Authors: Scott S. , Ronsmans C. 
Published: September 2009

SummaryObjective  To examine the nature of the association between maternal mortality and birth with a health professional in observational studies.Methods  Review of ecological studies relating the overall proportion of births with a health professional with the maternal mortality ratio at national level, and studies exploring the relationship between the presence of a health professional at birth and the risk of dying at the individual level. We report methodological challenges, including data quality and sources and the analytical approaches used. For the individual studies, crude odds ratios and 95% confidence intervals were calculated.Results  The 10 ecological studies are largely descriptive, a causal inference is tentative and there is poor controlling of confounders. The 10 individual studies examining the risk of death with and without a health professional showed little evidence that giving birth with a health professional reduces a woman’s risk of dying, and in some settings it appears to be associated with an increased risk of death.Conclusions  None of these study designs are optimal in evaluating the impact of births with a health professional on reducing maternal mortality. Analytically, greater insights can be gained by examining ecological relationships within countries, and by complementing the individual analyses with information on the health status of women when they first reach the health professional and whether or not the women planned to have a health professional present during birth.
A direct‐fired steam weeder
Authors: MERFIELD C N , HAMPTON J G , WRATTEN S D 
Published: September 2009

SummaryFlame weeders are a valuable weed management tool for organic growers and potentially for non‐organic producers, if the number of registered herbicides continues to decrease. However, they have a number of problems including low‐energy efficiency, fire risk and reduced performance in windy conditions. Steam has been shown to be a superior means of heat transfer to weeds and therefore steam weeders should outperform flame weeders. However, producing sufficient quantities of steam on tractor‐mounted equipment has been problematic, because the standard designs of pressurised steam boilers are ill‐suited for agricultural use. The ‘direct‐fired steam’ weeder described here, is considered to resolve this problem, by spraying water as a fine mist directly into hot exhaust gases from a burner, causing it to evaporate quickly, thus negating the needs for a pressurised system. This design is diesel powered, but could also be run on renewable fuels such as vegetable oil, addressing concerns about the use of non‐renewable ‘fossil fuels’ for thermal weeding. This approach is considered both effective in terms of steam generation and sufficiently practical and low enough in inherent risk for agricultural use. Production of commercial steam weeders based on this concept has commenced in New Zealand.
Does the shade avoidance response contribute to the critical period for weed control in maize (Zea mays)?
Authors: PAGE E R , TOLLENAAR M , LEE E A , LUKENS L , SWANTON C J 
Published: September 2009

SummaryThe effect of early weed emergence on crop seedling development has not been analysed within the context of a critical period study. Experiments were conducted to quantify the influence of a low light quality environment (i.e., low ratio of reflected red to far‐red light (R/FR)) on maize seedling growth and development under non‐limiting resource conditions. Weed‐addition and ‐removal series were constructed, such that the effects of R/FR on seedling growth and development were isolated from those of direct competition. Maize seedlings responded to the presence of weeds within 24 h of addition by increasing plant height, which was followed by a subsequent reduction in the rate of leaf appearance. Seedling biomass and leaf area decreased linearly in the weed removal series with increasing duration of weed presence. Conversely, seedlings in the weed‐addition series were unaffected. These results demonstrate that early exposure to weeds reduced the rate of seedling growth and development and that this effect was most pronounced if it was initiated upon emergence. This suggests that the existence of a period of developmental sensitivity to R/FR precedes the defined critical period for weed control in maize. These early physiological changes triggered by the R/FR ratio may contribute to the onset of the critical time of weed removal.