bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy management on a nectar diet: can sunbirds meet the challenges of low temperature and dilute food?
Authors: Köhler Angela , Verburgt Luke , McWhorter Todd J. , Nicolson Susan W.
Published: May 2010

1. Animals commonly experience variation in both food quality and metabolic requirements, and must regulate their food intake to maintain energy balance.

2. We exposed captive whitebellied (Cinnyris talatala) and amethyst (Chalcomitra amethystina) sunbirds (Nectariniidae) to different nectar sugar concentrations (0·25, 0·5 and 1 m sucrose), i.e. food qualities, and ambient temperatures (5, 15 and 25 °C), i.e. energy requirements, to examine the effects on food intake, feeding patterns and body mass of the birds.

3. Both species compensated for decreased dietary sugar concentration by increasing food intake. While whitebellied sunbirds showed a constant sugar intake over the range of diet concentrations, amethyst sunbirds ingested less sugar on 0·25 m than on 0·5 m sucrose. During acute short‐term exposure to 5 °C, birds increased food and thus sugar intake on all diet concentrations by almost 27%, compared to the similar intake at 15 and 25 °C. Despite increased food consumption, all birds lost more body mass at 5 and 15 °C than at 25 °C.

4. Adjustment of food intake in both species took place via changes in feeding frequency, with the duration of feeding events unchanged.

5. Apparent sugar assimilation in whitebellied sunbirds was >99%, irrespective of diet concentration and temperature. A chemical reactor model of digestive capacity based on measurements of intestinal hydrolytic capacity mostly underestimated the maximal food intake of whitebellied sunbirds in the cold, but predicted higher maximal intake for amethyst sunbirds than observed on most diet concentrations.

6. We conclude that physiological constraints impose upper limits on compensatory feeding in sunbirds. These constraints are mainly digestive at low temperature and osmoregulatory on dilute diets, while the combination of both stresses leads to additional metabolic costs.

7. The moderate mass loss of both species when exposed to these energy challenges suggests that behavioural changes and/or hypothermia may be used to reduce energy expenditure.
Dynamic intracellular distribution of Notch during activation and asymmetric cell division revealed by functional fluorescent fusion proteins
Authors: Kawahashi Koji , Hayashi Shigeo
Published: May 2010

Notch signaling mediates intercellular communication required for cell fate specification. Because the majority of Notch proteins exist as an intracellular pool, information on intracellular trafficking of Notch is essential for understanding its regulation. To observe trafficking of Notch protein in vivo, we constructed a Notch protein with green fluorescent protein (GFP) inserted into the intracellular domain. This construct rescued the neurogenic phenotype of Notch mutant embryos and caused the typical Notch gain‐of‐function phenotype when over‐expressed in the wing imaginal disc. Using this and similarly constructed Notch‐mCherry fusion, we showed rapid spatio‐temporal dynamics of Notch in endosomes. Kinetic analysis revealed that activation of Notch‐GFP by ectodomain shedding causes fast and unrestricted nuclear translocation of Notch intracellular domain. During asymmetric cell division of sensory organ precursor cells, distribution of Notch‐GFP showed transient asymmetry at the interface of daughter cells, confirming a possible site of regulation that biases Notch signaling level among daughter cells.
Changing clinicopathological practice in parathyroid disease
Authors: Johnson Sarah J
Published: May 2010

Johnson S J (2010)Histopathology 56,835–851 Changing clinicopathological practice in parathyroid disease

Parathyroid glands are received for histological examination during treatment of hyperparathyroidism. There are a small number of likely diagnoses available to the histopathologist, but distinction between these can be difficult due to overlap of morphological features. Recent developments in surgical approaches and preoperative imaging techniques have led to increased use of focused surgical approaches after preoperative localization of any abnormal parathyroid glands, thereby reducing the number of glands received for histological examination. Pathologists need to be aware of these clinical developments and the possible impact on their diagnostic practice. The pathogenesis of hyperparathyroidism is also reviewed, as is the rare but important diagnosis of parathyroid carcinoma.
Expression of key hypoxia sensing prolyl‐hydroxylases PHD1, ‐2 and ‐3 in pancreaticobiliary cancer
Authors: Gossage Lucy , Zaitoun Abed , Fareed Khaleel R , Turley Helen , Aloysius Mark , Lobo Dileep N , Harris Adrian L , Madhusudan Srinivasan
Published: May 2010

Gossage L, Zaitoun A, Fareed K R, Turley H, Aloysius M, Lobo D N, Harris A L & Madhusudan S (2010) Histopathology 56, 908–920 Expression of key hypoxia sensing prolyl‐hydroxylases PHD1, ‐2 and ‐3 in pancreaticobiliary cancer

Aims:  Tumour hypoxia is associated with an aggressive phenotype and resistance to chemotherapy and radiotherapy. The aim was to investigate whether key hypoxia sensing prolyl hydroxylases PHD1, PHD2 and PHD3 are dysregulated in pancreaticobiliary cancers, and to evaluate their potential clinical significance.

Methods and results:  Formalin‐fixed human pancreatic tissue from 120 consecutive patients undergoing pancreatic resections between June 2001 and June 2006 was constructed into tissue microarrays. Expression of PHD1, PHD2 and PHD3 was analysed using immunohistochemistry and correlated with clinicopathological variables and disease‐specific overall survival. PHD1, PHD2 and PHD3 were significantly overexpressed in pancreaticobiliary tumours compared with normal pancreatic ductal tissues (P = 0.03, P < 0.0001 and P < 0.0001, respectively). PHD3 expression in tumour tissue was associated with a trend towards worse overall disease‐specific survival in ampullary adenocarcinomas (P = 0.035) and pancreatic adenocarcinomas (P = 0.084). Absence of PHD1 expression was significantly associated with perineural invasion in pancreatic adenocarcinomas (P = 0.02) and a trend towards significance was also seen for absence of PHD2 expression in pancreatic adenocarcinomas (P = 0.04).

Conclusions:  Our results provide the first clinical evidence that PHD1, PHD2 and PHD3 may be involved in pancreaticobiliary tumorigenesis.
Innate immune responses to human rotavirus in the neonatal gnotobiotic piglet disease model
Authors: González Ana M. , Azevedo Marli S. P. , Jung Kwonil , Vlasova Anastasia , Zhang Wei , Saif Linda J.
Published: May 2010

Intestinal and systemic dendritic cell (DC) frequencies, serum and small intestinal content cytokines and uptake/binding of human rotavirus (HRV) virus‐like particles (VLP) were studied in HRV acutely infected or mock‐inoculated neonatal gnotobiotic piglets. Intestinal, mesenteric lymph node (MLN) and splenic plasmacytoid DCs (pDCs), conventional DCs (cDCs) and macrophages/monocytes were assessed by flow cytometry. In infected pigs, serum and small intestinal content interferon‐α (IFN‐α) were highest, interleukin‐12 (IL‐12) was lower and IL‐10, tumour necrosis factor‐α and IL‐6 were minimal. Compared with mock‐inoculated piglets, frequencies of total intestinal DCs were higher; splenic and MLN DC frequencies were lower. Most intestinal pDCs, but few cDCs, were IFN‐α+ and intestinal macrophages/monocytes were negative for IFN‐α. Serum IFN‐α levels and IFN‐α+ intestinal pDCs were highly correlated, suggesting IFN‐α production in vivo by intestinal pDCs (r = 0·8; P < 0·01). The intestinal pDCs and cDCs, but not intestinal macrophages/monocytes, of HRV‐infected piglets showed significantly lower VLP uptake/binding compared with mock‐inoculated piglets, suggesting higher activation of pDCs and cDCs in infected piglets. Both intestinal pDCs and cDCs were activated (IFN‐α+ and lower VLP binding) after HRV infection, suggesting their role in induction of HRV‐specific immunity. Dose‐effects of HRV on serum IFN‐α and IFN‐α+ DCs were studied by infecting piglets with 100‐fold higher HRV dose. A high dose increased parameters associated with inflammation (diarrhoea, intestinal pathology) but serum IFN‐α and IFN‐α+ DCs were similar between both groups. The pDCs have both anti‐ and pro‐inflammatory functions. Stimulation of the anti‐inflammatory effects of pDCs after the high dose, without increasing their pro‐inflammatory impacts, may be critical to reduce further immunopathology during HRV infection.
Human and mouse perforin are processed in part through cleavage by the lysosomal cysteine proteinase cathepsin L
Authors: Konjar Špela , Sutton Vivien R. , Hoves Sabine , Repnik Urška , Yagita Hideo , Reinheckel Thomas , Peters Christoph , Turk Vito , Turk Boris , Trapani Joseph A. , Kopitar‐Jerala Nataša
Published: May 2010

The pore‐forming protein perforin is synthesized as an inactive precursor in natural killer (NK) cells and cytotoxic T lymphocytes (CTLs), and becomes active when a short C‐terminal peptide is cleaved within acidic lysosome‐like cytotoxic granules. Although it was shown more than a decade ago that this cleavage is pH dependent and can be inhibited by the generic cysteine cathepsin inhibitor E‐64d, no protease capable of processing the perforin C terminus has been identified. Neither is it known whether a single protease is responsible or the processing has inbuilt redundancy. Here, we show that incubation of human NK cells and primary antigen‐restricted mouse CTLs with the cathepsin L (CatL) inhibitor L1 resulted in a marked inhibition of perforin‐dependent target cell death and reduced perforin processing. In vitro, CatL preferentially cleaved a site on full‐length recombinant perforin close to its C terminus. The NK cells of mice deficient in CatL showed a reduction but not a complete absence of processed perforin, indicating that cysteine proteases other than CatL are also able to process perforin. We conclude that granule‐bound cathepsins are essential for processing perforin to its active form, and that CatL is an important, but not exclusive, participant in this process.
Stronger inducible defences enhance persistence of intraguild prey
Authors: Kratina Pavel , Hammill Edd , Anholt Bradley R.
Published: May 2010

1. Intraguild predation is widespread in nature despite its potentially destabilizing effect on food web dynamics.

2. Anti‐predator inducible defences affect both birth and death rates of populations and have the potential to substantially modify food web dynamics and possibly increase persistence of intaguild prey.

3. In a chemostat experiment, we investigated the long‐term effects of inducible defences on the dynamics of aquatic microbial food webs consisting of an intraguild predator, intraguild prey, and a basal resource. We controlled environmental conditions and selected strains of intraguild prey that varied in the strength of expressed inducible defences.

4. We found that intraguild prey with a stronger tendency to induce an anti‐predator morphology persist for significantly longer periods of time. In addition, model selection analysis implied that flexibility in defensive phenotype (inducibility itself) is most likely the factor responsible for the enhanced persistence.

5. As patterns at the community level often emerge as a result of the life‐history traits of individuals, we propose that inducible defences increase the persistence of populations and may contribute to the widespread occurrence of theoretically unstable intraguild predation systems in nature.
Understanding properly the `potential natural vegetation' concept
Authors: Loidi Javier , del Arco Marcelino , Pérez de Paz Pedro Luis , Asensi Alfredo , Díez Garretas Blanca , Costa Manuel , Díaz González Tomás , Fernández‐González Federico , Izco Jesús , Penas Ángel , Rivas‐Martínez Salvador , Sánchez‐Mata Daniel
Published: May 2010

This is a response to critical comments concerning the inappropriate use of the potential natural vegetation (PNV) concept made in a recent contribution to the Commentary section of this journal. We consider that the PNV concept has been misinterpreted. PNV has been used extensively in several European countries since the mid‐1950s and was never intended to be used to make a prediction of what vegetation would dominate in an area if human influence were removed. PNV maps express hypothetical assumptions of what corresponds to dominant or natural vegetation in each area. Remnants of the vegetation of the past provided by palaeopalynology and other disciplines provide valuable information for interpreting modern vegetation, but natural changes and anthropogenic influences operating over the last millennia have to be taken into account. Annex I of the Habitats Directive provides a balanced list of habitat types for implementing conservation policies within the European Union.
Fine‐scale determinants of butterfly species richness and composition in a mountain region
Authors: Illán Javier Gutiérrez , Gutiérrez David , Wilson Robert J.
Published: May 2010

Aim  Global patterns of species richness are often considered to depend primarily on climate. We aimed to determine how topography and land cover affect species richness and composition at finer scales.

Location  Sierra de Guadarrama (central Iberian Peninsula).

Methods  We sampled the butterfly fauna of 180 locations (89 in 2004, 91 in 2005) at 600–2300 m elevation in a region of 10800 km2. We recorded environmental variables at 100‐m resolution using GIS, and derived generalized linear models for species density (number of species per unit area) and expected richness (number of species standardized to number of individuals) based on variables of topoclimate (elevation and insolation) or land cover (vegetation type, geology and hydrology), or both (combined). We evaluated the models against independent data from the alternative study year. We also tested for differences in species composition among sites and years using constrained ordination (canonical correspondence analysis), and used variation partitioning analyses to quantify the independent and combined roles of topoclimate and land cover.

Results  Topoclimatic, land cover and combined models were significantly related to observed species density and expected richness. Topoclimatic and combined models outperformed models based on land cover variables, showing a humped elevational diversity gradient. Both topoclimate and land cover made significant contributions to models of species composition.

Main conclusions  Topoclimatic factors may dominate species richness patterns in regions with pronounced elevational gradients, as long as large areas of natural habitat remain. In contrast, both topoclimate and land cover may have important effects on species composition. Biodiversity conservation in mountainous regions therefore requires protection and management of natural habitats over a wide range of topoclimatic conditions, which may assist in facilitating range shifts and alleviating declines in species richness related to climate change.
Effects of sampling protocol on the shapes of species richness curves
Authors: Dengler Jürgen , Oldeland Jens
Published: May 2010

Aim  Scheiner (Journal of Biogeography, 2009, 36, 2005–2008) criticized several issues regarding the typology and analysis of species richness curves that were brought forward by Dengler (Journal of Biogeography, 2009, 36, 728–744). In order to test these two sets of views in greater detail, we used a simulation model of ecological communities to demonstrate the effects of different sampling schemes on the shapes of species richness curves and their extrapolation capability.

Methods  We simulated five random communities with 100 species on a 64 × 64 grid using random fields. Then we sampled species–area relationships (SARs, contiguous plots) as well as species–sampling relationships (SSRs, non‐contiguous plots) from these communities, both for the full extent and the central quarter of the grid. Finally, we fitted different functions (power, quadratic power, logarithmic, Michaelis–Menten, Lomolino) to the obtained data and assessed their goodness‐of‐fit (Akaike weights) and their extrapolation capability (deviation of the predicted value from the true value).

Results  We found that power functions gave the best fit for SARs, while for SSRs saturation functions performed better. Curves constructed from data of 322 grid cells gave reasonable extrapolations for 642 grid cells for SARs, irrespective of whether samples were gathered from the full extent or the centre only. By contrast, SSRs worked well for extrapolation only in the latter case.

Main conclusions  SARs and SSRs have fundamentally different curve shapes. Both sampling strategies can be used for extrapolation of species richness to a target area, but only SARs allow for extrapolation to a larger area than that sampled. These results confirm a fundamental difference between SARs and area‐based SSRs and thus support their typological differentiation.
Functional composition controls invasion success in a California serpentine grassland
Authors: Hooper David U. , Dukes Jeffrey S.
Published: May 2010

1.Recent debates about the role of biotic resistance in controlling invasion success have focused on effects of species richness. However, functional composition could be a stronger control: species already in the community with similar functional traits to those of the invaders should have the greatest competitive effect on invaders. Still, experiments assessing effects of functional similarity have found contradictory results.

2.We used experimental communities in a serpentine grassland in California, USA, to assess the extent to which functional composition and functional diversity influenced success of two different types of invading plants: early season annuals (E) and late‐season annuals (L) that have been previously shown to differ in patterns of resource acquisition.

3.We seeded known quantities of seed of six different species (three in each functional group) into experimental plots containing established communities differing in functional composition and functional diversity. The experimental communities contained different combinations of E, L, perennial bunchgrass (P) and nitrogen‐fixer (N) functional groups, with functional diversity ranging from 0 to 4 groups. Each invading species was seeded into a separate quadrat within each plot to minimize competitive effects of invaders on each other. We measured both seedling and adult success of invaders for two full growing seasons to further understand mechanisms underlying biotic resistance.

4.More functionally diverse communities were less invaded overall, as measured by the average success of individual invaders. However, assessment of invaders by functional groups was more informative: Es in the extant community suppressed E invaders the most, and Ls in the extant community suppressed L invaders the most.

5.We observed a variety of interactions among extant functional groups in reducing invader success, including synergism, complementarity and ‘basement’ effects, where two or more groups negatively affected invaders, but combinations of groups were no more suppressive than single groups. The extant community influenced invaders more strongly through suppression of adult plant growth than through effects on seedling establishment.

6.Synthesis.Contrary to predictions from neutral theory, these results indicate that niche overlap was an important component of biotic resistance in these experimental plant communities and summed up to significant effects of species richness.
Nitrogen uptake by Carex aquatilis during the winter–spring transition in a low Arctic wet meadow
Authors: Edwards Kate A. , Jefferies Robert L.
Published: May 2010

1. Processes of decomposition occur year‐round in tundra ecosystems and respond quickly to seasonal changes. Characterizing the phenology of plant nutrient uptake in relation to these processes is essential to understanding the current and future productivity of Arctic ecosystems.

2. In wet sedge meadows located near Churchill, Manitoba, Canada, soil microbial biomass as well as inorganic and organic nutrient pools fluctuate seasonally, with late‐winter peaks followed by declines of these variables during the early stages of soil thaw; however, it is unknown if the dominant plant in this community takes up nitrogen when levels of this nutrient are high but soil temperatures are 0 °C or below.

3. Stable isotope tracing was utilized by injecting 15NH4Cl into soil cores and incubating for 1 or 8 days during spring thaw to determine the short‐term capacity for uptake and transport of inorganic nitrogen into Carex aquatilis (roots, shoots and rhizomes), moss and soil micro‐organisms during this transitional time of year.

4. During three 8‐day experimental trials in April and May 2007, C. aquatilis roots accumulated a substantial amount of the added nitrogen (33.5% increasing to 63.4%), when inorganic nitrogen was readily available in the soil, but declining. A smaller proportion of injected nitrogen was recovered from soil microbes (30% decreasing to 7%), and only trace amounts of injected 15N were measured in plant shoots, shoot bases, rhizomes and mosses (2% or less).

5. Synthesis. Shifting seasonal patterns in northern ecosystems resulting from climate change are likely to alter the progression of events that lead up to the summer growing season. A substantial pool of inorganic nitrogen resides temporarily in the soil at the end of winter, and we have shown here that plants are able to take up nitrogen at this time. Increases in the frequency and temperature highs of late‐winter warming events are likely to trigger early episodes of soil thaw, potentially reducing the capacity of plants to take up this large ephemeral supply of nitrogen in early spring.
Digital stain separation for histological images
Authors: TADROUS P.J.
Published: May 2010

It is often desirable to perform digital image analyses on sections prepared for human interpretation, e.g. nuclear chromatin texture analysis or three‐dimensional reconstructions using sections requiring human delineation of structures of interest. Unfortunately such analyses are often more effective using stains with less complex contrast. Here an automated selective ‘de‐staining’ method for digital images is presented. The method separates an image into its red, green and blue and hue, saturation and intensity components. A mask of stained tissue is prepared by automatic percentile thresholding. A single weighted inverted colour channel is then added to each of the three primary colour channels separately by an iterative algorithm that adjusts the weights to give minimum variance within the mask. The modified red, green and blue channels are then recombined. This method is automatic requiring no pre‐definition of stain colours or special hardware. The method is demonstrated to ‘de‐stain’ nuclei in haematoxylin and eosin (H&E) sections (and a separate haematoxylin image can be derived from this). An image of isolated brown reaction product is produced with immunoperoxidase preparations counterstained with haematoxylin. Furthermore trichrome (haematoxylin van Gieson, picrosirius red) and other common stains may be separated into their components with modifications of the same algorithm. Although other methods for colour separation do exist (e.g. spectral pathology and colour deconvolution) these require special apparatus or precise calibration and foreknowledge of pure dye colour spectra. The present method of digital stain separation is fully automatic with no such prerequisites.
3D structural analysis: sensitivity of Minkowski functionals
Authors: ARNS C.H. , KNACKSTEDT M.A. , MECKE K.
Published: May 2010

The Minkowski functionals, a family of statistical measures based on the Euler–Poincaré characteristic of n‐dimensional space, are the complete set of additive morphological measures and can be simply calculated from local contributions. As such, they have found a wide range of applications. We consider the effects of distortions (drift, noise and blurring) on the morphological properties of complex random models, representative of a wide range of structure. Such distortions arise experimentally in imaging techniques due to diffraction, absorption and sample drift. The question is asked, how critically these distortions effect image quality as measured by the Minkowski functionals. Defining a length scale based on the two‐point correlation function, we consider how distortion at different scales can lead to quantitative errors in morphological measures.
Characterization of dentine structure in three dimensions using FIB‐SEM
Authors: EARL J.S. , LEARY R.K. , PERRIN J.S. , BRYDSON R. , HARRINGTON J.P. , MARKOWITZ K. , MILNE S.J.
Published: May 2010

All biological tissues are three dimensional and contain structures that span a range of length scales from nanometres through to hundreds of millimetres. These are not ideally suited to current three‐dimensional characterization techniques such as X‐ray or transmission electron tomography. Such detailed morphological analysis is critical to understanding the structural features relevant to tissue function and designing therapeutic strategies intended to address structural deficiencies encountered in pathological states. We show that use of focused ion beam milling combined with scanning electron microscopy can provide three‐dimensional information at nanometre resolution from biologically relevant volumes of material, in this case dentine.
LR White sections as slot grid support films for transmission electron microscopy
Authors: VON RUHLAND C.J. , HOBOT J.A.
Published: May 2010

The utility of LR White sections as slot grid support films for the examination of thin resin‐embedded tissue sections by transmission electron microscopy was investigated and compared with traditional formvar‐carbon films. Throughout a variety of staining procedures, which involved the use of organic solvent, oxidizing agents, strong acid and prolonged incubation, LR White support films remained intact and the attached tissue sections remained adherent. By contrast, complete loss of formvar‐carbon support films occurred in 25% of preparations during routine staining with aqueous reagents. This loss increased to 62% following staining with either alcoholic or oxidizing and acidic stains, and to 66% following prolonged (immunohistochemical) staining. Tissue contrast, ultrastructural detail and immunohistochemical staining intensity were comparable between sections on the two types of support film. The use of LR White sections as support films for slot grids represents a quick, cheap, simple and robust alternative to traditional support films and, furthermore, requires no carbon coating
Redefining the Gonadotrophin‐Releasing Hormone Neurone Dendrite
Authors: Campbell R. E. , Suter K. J.
Published: May 2010

Gonadotrophin‐releasing hormone (GnRH) neurones are the final output neurones of the complex synaptic network responsible for the central control of fertility. This scattered population of neurones has been shown to have remarkably long dendritic processes by cell‐filling of GnRH neurones in situ with low‐molecular weight dyes. This review focuses on how the functional significance of these long dendritic extensions is being explored through dual somatic–dendritic electrophysiological recordings, computational modelling, immunolabelling for specific channels and multiple modes of microscopy and imaging. Remarkably, recent work has discovered that GnRH neurone dendrites not only actively propagate action potentials, but also comprise the primary site of action potential initiation. These findings, along with the discovery of regionalised expression of active conductances, highlight dendrites of single GnRH neurones as being central sites of signal integration. Moreover, imaging studies have shown that the long dendrites of GnRH neurones intertwine and bundle with one another. The presence of shared synaptic input to bundling dendrites, coupled with their active properties and the increased potency of distally placed synaptic inputs, is suggestive of a novel mechanism of GnRH neurone synchronisation, a feature critical for mammalian reproduction. Together, these discoveries of the GnRH neurone dendrite structure and function are changing the way that we view the central regulation of fertility.
Gonadotrophin‐Releasing Hormone Nerve Terminals, Tanycytes and Neurohaemal Junction Remodelling in the Adult Median Eminence: Functional Consequences for Reproduction and Dynamic Role of Vascular Endothelial Cells
Authors: Prevot V. , Bellefontaine N. , Baroncini M. , Sharif A. , Hanchate N. K. , Parkash J. , Campagne C. , De Seranno S.
Published: May 2010

Although coordinated actions of several areas within the hypothalamus are involved in the secretion of gonadotrophin‐releasing hormone (GnRH), the median eminence of the hypothalamus, where the nerve terminals are located, plays a particularly critical role in the release of GnRH. In adult females, prior to the preovulatory surge of GnRH, the retraction of specialised ependymoglial cells lining the floor of the third ventricle named tanycytes allows for the juxtaposition of GnRH nerve terminals with the adjacent pericapillary space of the pituitary portal vasculature, thus forming direct neurohaemal junctions. These morphological changes occur within a few hours and are reversible. Such remodelling may promote physiological conditions to enhance the central release of GnRH and potentiate oestrogen‐activated GnRH release. This plasticity involves dynamic cell interactions that bring into play tanycytes, astrocytes, vascular endothelial cells and GnRH neurones themselves. The underlying signalling pathways responsible for these structural changes are comprised of highly diffusible gaseous molecules, such as endothelial nitric oxide, and paracrine communication processes involving receptors of the erbB tyrosine kinase family, transforming growth factor beta 1 and eicosanoids, such as prostagladin E2. Some of these molecules, as a result of their ability to diffuse within the median eminence, may also serve as synchronising cues allowing for the occurrence of functionally meaningful episodes of GnRH secretion by coordinating GnRH release from the GnRH neuroendocrine terminals.
Photosynthetic responses of two eucalypts to industrial‐age changes in atmospheric [CO2] and temperature
Authors: GHANNOUM OULA , PHILLIPS NATHAN G. , SEARS MARIE A. , LOGAN BARRY A. , LEWIS JAMES D. , CONROY JANN P. , TISSUE DAVID T.
Published: May 2010

The unabated rise in atmospheric [CO2] is associated with increased air temperature. Yet, few CO2‐enrichment studies have considered pre‐industrial [CO2] or warming. Consequently, we quantified the interactive effects of growth [CO2] and temperature on photosynthesis of faster‐growing Eucalyptus saligna and slower‐growing E. sideroxylon. Well‐watered and ‐fertilized tree seedlings were grown in a glasshouse at three atmospheric [CO2] (290, 400, and 650 µL L−1), and ambient (26/18 °C, day/night) and high (ambient + 4 °C) air temperature. Despite differences in growth rate, both eucalypts responded similarly to [CO2] and temperature treatments with few interactive effects. Light‐saturated photosynthesis (Asat) and light‐ and [CO2]‐saturated photosynthesis (Amax) increased by ∼50% and ∼10%, respectively, with each step‐increase in growth [CO2], underpinned by a corresponding 6–11% up‐regulation of maximal electron transport rate (Jmax). Maximal carboxylation rate (Vcmax) was not affected by growth [CO2]. Thermal photosynthetic acclimation occurred such that Asat and Amax were similar in ambient‐ and high‐temperature‐grown plants. At high temperature, the thermal optimum of Asat increased by 2–7 °C across [CO2] treatments. These results are the first to suggest that photosynthesis of well‐watered and ‐fertilized eucalypt seedlings will remain strongly responsive to increasing atmospheric [CO2] in a future, warmer climate.
Arabidopsis eIF5A3 influences growth and the response to osmotic and nutrient stress
Authors: MA FENGSHAN , LIU ZHONGDA , WANG TZANN‐WEI , HOPKINS MARIANNE T. , PETERSON CAROL A. , THOMPSON JOHN E.
Published: May 2010

AteIF5A3, one of three genes encoding eukaryotic translation initiation factor 5A (eIF5A) inArabidopsis thaliana, and corresponding genesPdeIF5A3fromPopulus deltoides(eastern cottonwood) andSleIF5A4fromSolanum lycopersicum(tomato) were constitutively over‐expressed inA. thaliana.The resultant transgenic plants exhibited enhanced vegetative and reproductive growth. Indeed, the increase in seed yield relative to empty vector controls for thePdeIF5A3over‐expressing plants ranged from 50% to 300% depending on the line. ThePdeIF5A3over‐expressing plants also exhibited enhanced fitness when exposed to osmotic and nutrient (N, P and K) stress. The spatial localization ofAteIF5A3 was visualized by confocal microscopy using transgenic plants expressingPAteIF5A3:GFP‐AteIF5A3. GFP fluorescence reflecting expression ofAteIF5A3 was detectable in the phloem, particularly companion cells, of roots, stems and leaves, in the epidermal cells of the root tip, in the columella cells of the root cap and in the chalazal tissue of fertilized ovules, which all play a pivotal role in nutrient or hormone translocation. Thus,AteIF5A3 appears to be involved in supporting growth and to play a regulatory role in the response of plants to sub‐lethal osmotic and nutrient stress.
The sucrose transporter HbSUT3 plays an active role in sucrose loading to laticifer and rubber productivity in exploited trees of Hevea brasiliensis (para rubber tree)
Authors: TANG CHAORONG , HUANG DEBAO , YANG JIANGHUA , LIU SHUJIN , SAKR SOULAÏMAN , LI HEPING , ZHOU YIHUA , QIN YUNXIA
Published: May 2010

Efficient sucrose loading in rubber‐producing cells (laticifer cells) is essential for retaining rubber productivity in Hevea brasiliensis, but the molecular mechanisms underlying the regulation of this process remain unknown. Here, we functionally characterized a putative Hevea SUT member, HbSUT3, mainly in samples from regularly exploited trees. When expressed in yeast, HbSUT3 encodes a functional sucrose transporter that exhibits high sucrose affinity with a Km value of 1.24 mm at pH 4.0, and possesses features typical of sucrose/H+ symporters. In planta, when compared to the expression of other Hevea SUT genes, HbSUT3 was found to be the predominant member expressed in the rubber‐containing cytoplasm (latex) of laticifers. The comparison of HbSUT3 expression among twelve Hevea tissues demonstrates a relatively tissue‐specific pattern, i.e. expression primarily in the latex and in female flowers. HbSUT3 expression is induced by the latex stimulator Ethrel (an ethylene generator), and relates to its yield‐stimulating effect. Tapping (the act of rubber harvesting) markedly increased the expression of HbSUT3, whereas wounding alone had little effect. Moreover, the expression of HbSUT3 was found to be positively correlated with latex yield. Taken together, our results provide evidence favouring the involvement of HbSUT3 in sucrose loading into laticifers and in rubber productivity.
Inhibition of Botrytis cinerea growth and suppression of botrytis bunch rot in grapes using chitosan
Authors: Reglinski T. , Elmer P. A. G. , Taylor J. T. , Wood P. N. , Hoyte S. M.
Published: May 2010

Chitosan inhibited growth of Botrytis cinerea in liquid culture and suppressed grey mould on detached grapevine leaves and bunch rot in commercial winegrapes. Germination of B. cinerea was completely inhibited in malt extract broth containing chitosan at concentrations greater than 0·125 g L−1. However, treated conidia were able to infect detached Chardonnay leaves and pathogenicity was not affected, even after incubation for 24 h in chitosan at 10 g L−1. When added after conidial germination, chitosan inhibited B. cinerea growth and induced morphological changes suggestive of possible curative activity. The effective concentration of chitosan that reduced mycelial growth by 50% (EC50) was 0·06 g L−1. As a foliar treatment, chitosan protected detached Chardonnay leaves against B. cinerea and reduced lesion diameter by up to 85% compared with untreated controls. Peroxidase and phenylalanine ammonia‐lyase activities were also induced in treated leaves. In vineyard studies, Chardonnay winegrapes exhibited 7·4% botrytis bunch rot severity at harvest in 2007 after treatment with an integrated programme that included chitosan sprays from bunch closure until 2 weeks preharvest, compared with 15·5% in untreated controls and 5·9% with fungicide treatment. In the following season, botrytis bunch rot severity was 44% in untreated Chardonnay at harvest and the integrated programme (21%) was less effective than fungicides (13·8%). However, in Sauvignon blanc winegrapes, the integrated and the fungicide programme each reduced botrytis bunch rot severity to 4% and were significantly different from the untreated control (11·5%). This study provides evidence that suppression of botrytis in winegrapes by chitosan involves direct and indirect modes of action.
Chert spheroids of the Monterey Formation, California (USA): early‐diagenetic structures of bedded siliceous deposits
Authors: BEHL RICHARD J.
Published: May 2010

Chert spheroids are distinctive, early‐diagenetic features that occur in bedded siliceous deposits spanning the Phanerozoic. These features are distinct in structure and genesis from similar, concentrically banded ‘wood‐grain’ or ‘onion‐skin’ chert nodules from carbonate successions. In the Miocene Monterey Formation of California (USA), chert spheroids are irregular, concentrically banded nodules, which formed by a unique version of brittle differential compaction that results from the contrasting physical properties of chert and diatomite. During shortening, there is brittle fracture of diatomite around, and horizontally away from, the convex surface of strain‐resistant chert nodules. Unlike most older siliceous deposits, the Monterey Formation still preserves all stages of silica diagenesis, thus retaining textural, mineralogical and geochemical features key to unravelling the origin of chert spheroids and other enigmatic chert structures. Chert spheroids found in opal‐A diatomite form individual nodules composed of alternating bands of impure opal‐CT chert and pure opal‐CT or chalcedony. With increased burial diagenesis, surrounding diatomite transforms to bedded porcelanite or chert, and spheroids no longer form discrete nodules, yet still display characteristic concentric bands of pure and impure microcrystalline quartz and chalcedony. Petrographic observations show that the purer silica bands are composed of void‐filling cement that precipitated in curved dilational fractures, and do not reflect geochemical growth‐banding in the manner of Liesegang phenomena invoked to explain concentrically banded chert nodules in limestone. Chertification of bedded siliceous sediment can occur more shallowly (< 100 m) and rapidly (< 1 Myr) than the bulk silica phase transitions forming porcelanite or siliceous shale in the Monterey Formation and other hemipelagic/pelagic siliceous deposits. Early diagenesis is indicated by physical properties, deformational style and oxygen‐isotopic composition of chert spheroids. Early‐formed cherts formed by pore‐filling impregnation of the purest primary diatomaceous beds, along permeable fractures and in calcareous–siliceous strata.
Otomycosis due to Aspergillus spp. in a dog: case report and literature review
Authors: Coyner Kimberly
Published: May 2010

This report describes the clinical findings, clinicopathology and treatment of otomycosis caused by Aspergillus spp. in an atopic dog affected by chronic unilateral purulent otitis externa unresponsive to topical and oral antibiotics and antifungal treatments. Cytology of otic exudate revealed neutrophils and septate fungal hyphae, and otic culture grew Aspergillus spp. and no bacteria. Treatments included allergen‐specific immunotherapy, topical and oral antifungal therapy and anti‐inflammatory steroid therapy. Final resolution occurred after treatment of the underlying hypersensitivity disorder, administration of topical ketoconazole and debridement of infectious ear exudate. Otomycosis due to filamentous fungi may, as in humans, occur in dogs with ear canals compromised by pre‐existing allergic or bacterial otitis, and possibly previous antibiotic therapy. Antifungal medications provided clinical improvement, but the key to successful treatment was the restoration of the normal physiology of the external auditory canal.
The standard of neutrality: still flapping in the breeze?
Authors: PROULX S. R. , ADLER F. R.
Published: May 2010

Neutrality plays an important role as a null model in evolutionary biology. Recent theoretical advances suggest that neutrality is not a unitary concept, and we identify three distinct forms of neutrality. Eu‐neutrality means that types do not differ in any measurable way and is thus the idealized form of neutrality. However, individuals or species that do differ in important ways can behave neutrally under some circumstances, both broadening and complicating the applicability of the concept of neutrality. Our second two types of neutrality address two quite different forms of context‐dependent neutrality. Circum‐neutrality means that two character states have the same direct effect on fitness but do not evolve neutrally because of differences in their circumstances. Iso‐neutrality means that two types are equivalent in some population or ecological contexts but not in others, producing an isocline. Confounding of these different definitions has created significant confusion about which models are truly neutral, why some models behave neutrally even when there are large differences in reproductive outputs, and what these different views of neutrality mean to practicing biologists. These complications call into question the acceptance of neutral models as null models and suggest that a better approach is to compare the predictions of models that differ in sources of stochasticity and degree of selection.
Nucleoside transport and associated metabolism*
Authors: Möhlmann T. , Bernard C. , Hach S. , Ekkehard Neuhaus H.
Published: May 2010

Nucleosides are intermediates of nucleotide metabolism. Nucleotide de novo synthesis generates the nucleoside monophosphates AMP and UMP, which are further processed to all purine and pyrimidine nucleotides involved in multiple cellular reactions, including the synthesis of nucleic acids. Catabolism of these substances results in the formation of nucleosides, which are further degraded by nucleoside hydrolase to nucleobases. Both nucleosides and nucleobases can be exchanged between cells and tissues through multiple isoforms of corresponding transport proteins. After uptake into a cell, nucleosides and nucleobases can undergo salvage reactions or catabolism. Whereas energy is preserved by salvage pathway reactions, catabolism liberates ammonia, which is then incorporated into amino acids. Keeping the balance between nitrogen consumption during nucleotide de novo synthesis and ammonia liberation by nucleotide catabolism is essential for correct plant development. Senescence and seed germination represent situations in plant development where marked fluctuations in nucleotide pools occur. Furthermore, extracellular nucleotide metabolism has become an immensely interesting research topic. In addition, selected aspects of nucleoside transport in yeast, protists and humans are discussed.
Roles of tandem‐pore K+ channels in plants – a puzzle still to be solved*
Authors: Voelker C. , Gomez‐Porras J. L. , Becker D. , Hamamoto S. , Uozumi N. , Gambale F. , Mueller‐Roeber B. , Czempinski K. , Dreyer I.
Published: May 2010

The group of voltage‐independent K+ channels in Arabidopsis thaliana consists of six members, five tandem‐pore channels (TPK1–TPK5) and a single Kir‐like channel (KCO3). All TPK/KCO channels are located at the vacuolar membrane except for TPK4, which was shown to be a plasma membrane channel in pollen. The vacuolar channels interact with 14‐3‐3 proteins (also called General Regulating Factors, GRFs), indicating regulation at the level of protein–protein interactions. Here we review current knowledge about these ion channels and their genes, and highlight open questions that need to be urgently addressed in future studies to fully appreciate the physiological functions of these ion channels.
Eavesdropping on Male Singing Interactions Leads to Differential Allocation in Eggs
Authors: Garcia‐Fernandez Violaine , Amy Mathieu , Lacroix André , Malacarne Giorgio , Leboucher Gérard
Published: May 2010

Females invest differently in their eggs depending on the quality of their mates. In oscines, female investment is influenced by the quality of male song. In domestic canariesSerinus canaria, as well as in black‐capped chickadeesPoecile atricapillus, females pay attention not only to the intrinsic quality of male song but can also gather information, by eavesdropping on male–male singing interactions, on the relative quality of males. During these interactions, overlapping the song of the rival is more threatening than alternating. Moreover eavesdropping female canaries have been shown to prefer the overlapping song rather than the overlapped song. The present study was designed to assess the effect of the information gathered by eavesdropping on female investment in eggs. First, we broadcasted overlapping interactions to female canaries. Then, we broadcasted to each female one of the two songs previously heard and collected eggs. Females exposed to overlapping songs laid eggs with greater yolk ratio than females exposed to overlapped songs. In contrast, yolk testosterone quantity and concentration were not affected by the treatment. Moreover, we found a variation between eggs with regard to the testosterone deposited in yolk: both quantity and concentration increased with laying order. Our results suggest that female canaries use information gathered by eavesdropping to differentially allocate resources into the eggs. They suggest that singing interactions could influence chick quality via female investment.
Parthenogenetic Activation of Pig Oocytes Using Pulsatile Treatment with a Nitric Oxide Donor
Authors: Petr J , Chmelíková E , Krejčová T , Řehák D , Novotná B , Jílek F
Published: May 2010

Contents

The nitric oxide donor (+)–S‐nitroso‐N‐acetylpenicillamine (SNAP) is capable of inducing parthenogenetic activation in pig oocytes matured in vitro. However, quite a long exposure to the nitric oxide donor, exceeding 10 h, is necessary for successful oocyte activation. Repeated short‐term treatment with 2 mm SNAP significantly increased the activation rates despite the fact that the overall exposure time to the nitric oxide donor did not exceed 4 h. With regard to the activation rate, 12 repeated treatments lasting 10 min each were found to be the most efficient regimen (63.3%). The continuous exposure to the nitric oxide donor for the same overall time induced parthenogenetic activation in 12.5% oocytes (2‐h continuous treatment with 2 mm SNAP). The development of parthenogenetic embryos increased after repeated short‐term treatment with SNAP. After continuous treatment with 2 mm SNAP for 10 h, only 6.7% of the oocytes cleaved, and none developed beyond the 4‐cell stage. Thirty‐minute treatment repeated four times with 2 mm SNAP induced cleavage in 37.5% of the oocytes, 18.3% developed to the morula stage, and 6.7% reached the blastocyst stage. Based on the results, it is concluded that pulsatile treatment can significantly improve parthenogenetic activation rate when compared with the continuous treatment using nitric oxide donors.