bluuebunny/crossref_metadata_2025 huggingface dataset:
Rolle der IAO‐Normen bei der Umsetzung des Rechts auf soziale Sicherheit heute und in Zukunft
Authors: Kulke Ursula
Published: September 2007

Das Recht auf soziale Sicherheit wird in der Allgemeinen Erklärung der Menschenrechte und im Internationalen Pakt über wirtschaftliche, soziale und kulturelle Rechte anerkannt. Trotzdem schweigen sich internationale Menschenrechtsinstrumente und Überwachungs‐mechanismen meist über seine Definition aus. Innerhalb des UNO‐Systems blieb es dem IAA überlassen, diesem Recht im Rahmen des IAO‐Übereinkommens Nr. 102 Substanz zu verleihen. Trotz internationaler Anerkennung des positiven Einflusses dieses Übereinkommens als Mechanismus, der hilft, die allmähliche Entwicklung der sozialen Sicherheit zu steuern, kann es keine Mindestanforderungen für soziale Grundleistungen durchsetzen. Der vorliegende Artikel untersucht, ob die bestehenden IAO‐Normen Staaten helfen können, das universelle Recht zumindest auf ein Grundversor‐gungspaket zu verwirklichen, und kommt zu dem Schluss, dass die IAO neue ergänzende Mechanismen entwickeln muss, die auch zum Erfüllen der Millenniums‐Entwicklungsziele und zur weltweiten Armutsreduktion beitragen würden.
Für eine dynamische soziale Sicherheit: Ein Konzept für den Wandel und die Ausdehnung der Deckung
Authors: McKinnon Roddy
Published: September 2007

Die Institutionen der sozialen Sicherheit entwickeln sich üblicherweise Schritt für Schritt, aber unablässig, um ihre institutionelle Leistungsfähigkeit zu verbessern und die gewünschten Ergebnisse für das System der sozialen Sicherheit zu erzielen. Im Zeichen des mit einer alternden Gesellschaft und der Globalisierung einhergehenden Wandels verstärkt sich der Druck zu weiterer und schnellerer Anpassung. In diesem Sinn schlagen wir hier ein Rahmenkonzept zur Vereinheitlichung vor, das allen Institutionen der sozialen Sicherheit helfen soll, ihre Leistungsfähigkeit zu verbessern und die gewünschten Ergebnisse zu erreichen. Das vorgelegte Rahmenkonzept bezeichnen wir als “dynamische soziale Sicherheit”. Indem wir die Ziele der Institutionen der sozialen Sicherheit und ihre Aktivitäten enger und in positivem Sinne mit jenen von Wirtschaft und Gesellschaft verknüpfen, zielen wir darauf ab, allen Menschen wenigstens ein Mindestmaß an sozialer Sicherheit zu gewähren.
Änderung eines Paradigmas der Entwicklungspolitik: Investitionen in Mindeststandards der sozialen Sicherheit für alle
Authors: Cichon Michael , Hagemejer Krzysztof
Published: September 2007

Der vorliegende Beitrag prüft kurz die Errungenschaften der sozialen Sicherheit weltweit und fasst die wirtschaftlichen und sozialen Vorteile eines staatlichen Systems der sozialen Sicherheit zusammen. Dann wird dargelegt, dass Systeme der sozialen Sicherheit notwendiger Teil des institutionellen Rahmens einer wirksamen Marktwirtschaft sind, da sie — unter anderem — den gesellschaftlichen Zusammenhalt schaffen, den eine langfristige Wirtschaftsentwicklung erfordert. Wir vertreten die Auffassung, dass die Einführung einer Grundsicherung durch Sozialsysteme in Entwicklungs‐ländern eine wünschenswerte und bezahlbare Investition in deren Sozial‐ und Wirtschaftsentwicklung ist. Wir schätzen die globalen Mindestinvestitionskosten für eine Grund‐sicherung durch die soziale Sicherheit und schlagen schließlich internationale Instrumente zur Einführung weltweiter sozialer Mindeststandards vor.
La seguridad social en un mundo en proceso de globalización
Authors: Kannan K. P.
Published: September 2007

El principal objetivo del artículo es presentar argumentos para ampliar tanto el concepto como la cobertura de la seguridad social, en particular en los países en desarrollo, con el fin de abordar el doble problema de la «carencia» y la «adversidad». Las dos partes de este concepto ampliado de seguridad social son la Seguridad Social Básica (SSB) y la Seguridad Social Contingente (SSC). Para reforzar este argumento, se han destacado ejemplos de la experiencia histórica de los países occidentales, en los que el Estado desempeñó un papel dirigente. Después de defender la extensión de la SSB, el artículo también examina la extensión de la SSC. La mejor manera de hacerlo es a través de la economía informal que emplea a una gran mayoría de trabajadores en los países en desarrollo. El artículo, además de destacar la supremacía del Estado, desarrolla una tipología de los distintos modelos de seguridad social que podrían ser utilizados para estudiar y comprender los programas existentes, así como las posibilidades de la extensión de la cobertura.
Extender la cobertura de la seguridad social: conceptos, tendencias globales y cuestiones políticas
Authors: Van Ginneken Wouter
Published: September 2007

Este artículo revisa la experiencia de algunos países clave con bajos, medios y elevados ingresos que han extendido con éxito la cobertura de la seguridad social o que lo están haciendo. Demuestra que el primer requisito para extender la seguridad social es la existencia de un Estado sólido y competente. También examina diversos indicadores de la cobertura que pueden ayudar a los responsables políticos nacionales e internacionales a centrar sus esfuerzos en la extensión de la seguridad social. Por último, documenta la utilización creciente de pensiones sociales financiadas fiscalmente y discute algunas cuestiones políticas relacionadas con el vínculo entre los sistemas de seguridad social financiados fiscalmente y los sistemas de seguridad social contributivos.
Consecuencias económicas del Estado de bienestar
Authors: Mares Isabela
Published: September 2007

¿Cuáles son las consecuencias de los programas de seguro social más amplios?¿Desvían los Estados de bienestar más importantes recursos de la actividad económica y distorsionan las decisiones de las empresas en materia de inversions? Analizo en el presente artículo la investigación teórica y empírica en torno a las consecuencias económicas del Estado de bienestar. Esta revisión muestra que las predicciones de una relación negativa entre niveles más elevados de protección social y de crecimiento no han sido corroboradas por los datos. Tanto los programas del seguro como otras políticas que aumentan la inversión en capital humano o la productividad general de los trabajadores, originan importantes externalidades económicas que tienen mayor peso que los efectos potencialmente distorsionadores de impuestos más elevados. Tampoco los estudios empíricos han puesto de manifiesto una relación negativa consistente entre unos Estados de bienestar más importantes y el nivel de empleo. Las consecuencias del Estado de bienestar en el empleo son paliadas por las instituciones y las políticas vigentes —como el nivel de descentralización del sistema de negociación de los salarios— que afectan a la redistribución de los gastos en unos impuestos más elevados entre los trabajadores y las empresas. Por consiguiente, las consecuencias en el empleo de los Estados de bienestar más importantes, no son lineales.
Extender la cobertura conjunta de los riesgos para la salud en los países en desarrollo: desafíos que entraña la transición hacia una financiación fiscal general
Authors: Baeza Cristian C. , Packard Truman G.
Published: September 2007

Aumentar la afiliación a programas eficaces de cobertura conjunta de los riesgos en los países en desarrollo es un elemento fundamental del paquete de políticas diseñadas para proteger a las familias vulnerables de las consecuencias empobrecedoras de las crisis de salud. Las personas que son pobres, las que tienen un elevado riesgo y los trabajadores autónomos o del sector informal son los tres grupos que plantean cuestiones particulares en la formulación de la política de cobertura conjunta de los riesgos de salud. En este artículo se discuten las opciones políticas para extender la cobertura conjunta de los riesgos en los países en desarrollo, prestando particular atención a los méritos y desventajas de superar las carencias del seguro financiado con impuestos sobre la nómina mediante un papel más importante de los ingresos fiscales generales en el sector de la salud.
El papel de la seguridad social financiada fiscalmente
Authors: Barrientos Armando
Published: September 2007

Este artículo reevalúa el papel que desempeña la seguridad social financiada fiscalmente. Destaca las tendencias relevantes que se están manifestando en los países desarrollados y en desarrollo, y examina los cambios cualitativos que se están produciendo en el enfoque y el papel que desempeña la seguridad social financiada fiscalmente. Luego evalúa las modalidades emergentes de seguridad social financiada fiscalmente en los países en desarrollo. En particular analiza sus prioridades, ámbito de aplicación, diseño y dinámica. Concluye que la seguridad social financiada fiscalmente emergente en los países en desarrollo cumple la promesa de tener un impacto en la pobreza y la vulnerabilidad global, y el principal desafío es garantizar que así se contribuye a desarrollar sistemas de seguridad social completos.
Cometido presente y futuro de las normas de la OIT en la materialización del derecho a la seguridad social
Authors: Kulke Ursula
Published: September 2007

El derecho a la seguridad social está contemplado en la Declaración Universal de los Derechos Humanos y en el Pacto Internacional de Derechos Económicos, Sociales y Culturales. No obstante, los instrumentos internacionales de derechos humanos y los mecanismos de control no se han pronunciado, en su mayoría, en cuanto a su definición. Dentro de la familia de las Naciones Unidas, se ha delegado en la OIT el dotar de sustancia a este derecho a través del Convenio internacional del trabajo no 102. A pesar del reconocimiento internacional de la influencia positiva del Convenio como mecanismo que contribuye a pilotar el desarrollo progresivo de la seguridad social, no se ha conseguido la obligatoriedad de requisitos mínimos para una base social. Al examinar si las normas vigentes de la OIT pueden ayudar a que los Estados hagan realidad el derecho universal a al menos un paquete básico de seguridad social, el artículo sugiere la necesidad de que la OIT desarrolle nuevos mecanismos complementarios, que podrían también contribuir a la consecución de los Objetivos de Desarrollo del Milenio y a la reducción global de la pobreza.
Seguridad social dinámica: un marco para liderar el cambio y extender la cobertura
Authors: McKinnon Roddy
Published: September 2007

En general, la trayectoria de desarrollo seguida por las organizaciones de la seguridad social ha sido la de una adaptación creciente pero continua encaminada a mejorar el rendimiento de las organizaciones y a obtener los resultados previstos en los programas de seguridad social. En el contexto evolutivo del envejecimiento de la sociedad y de la globalización, cada vez es más urgente que la adaptación continúe y que sea más rápida. A estos efectos, este artículo propone unificar el marco de acción para ayudar a todas las organizaciones de la seguridad social a obtener mejores rendimientos y los resultados previstos en los programas. Este marco de acción propuesto se llama «seguridad social dinámica». Con una asociación más estrecha y positiva de las aspiraciones y medidas llevadas a cabo por las organizaciones de la seguridad social y de las aspiraciones y actividades del sector económico y la sociedad, el objetivo perseguido es respaldar una mejor realización, como mínimo, de un nivel básico de seguridad social para todos.
Cambios en el paradigma de las políticas de desarrollo: inversión en una seguridad social mínima para todos
Authors: Cichon Michael , Hagemejer Krzysztof
Published: September 2007

En el presente artículo se analiza brevemente la cobertura de seguridad social que el mundo ha alcanzado y se resumen las ventajas económicas y sociales de los regímenes nacionales de seguridad social. Más adelante, se argumenta que los regímenes de seguridad social son una parte necesaria del marco institucional de cualquier economía de mercado eficiente, dado que crean, entre otras cosas, la cohesión social necesaria para un desarrollo económico a largo plazo. Luego, se argumenta que la introducción de una protección social básica en los países en desarrollo es deseable y constituye una inversión abordable en su desarrollo socioeconómico. Por último, se estima el costo mínimo de inversión mundial en la entrega de una seguridad social básica y se sugieren instrumentos internacionales para introducir una seguridad social mínima en todo el mundo.
Combined intra‐arterial 5‐fluorouracil and subcutaneous interferon‐alpha therapy for highly advanced hepatocellular carcinoma
Authors: Damdinsuren Bazarragchaa , Nagano Hiroaki , Monden Morito
Published: September 2007

Because of the difficulties of low sensitivity for anticancer agents and giving sufficient dose because of poor liver function, chemotherapy may not play a central role for treatment of hepatocellular carcinoma (HCC) patients, especially those with liver cirrhosis. However, chemotherapy must be one of the important possibilities of multimodal treatment for advanced HCC, for which hepatic resection, percutaneous ablation, transcatheter arterial embolization and other general therapies would not be effective or even possible. Also, intra‐arterial perfusion chemotherapy is a common therapy for HCC and it is not difficult to maintain; but the effective rate is not sufficient. Recently, the combination therapy of s.c. interferon (IFN)‐α and intra‐arterial 5‐fluorouracil (5‐FU) showed an outstandingly effective rate for intractable HCC (with portal vein thrombosis). In addition,recent preclinical and clinical studies have revealed that the mechanism of combination therapy may concern direct antitumor effects (through cell‐cycle arrest and induction of apoptosis) and indirect actions (through immunocompetent cells and anti‐angiogenic effect). For the further advance of HCC treatment and prognosis, this therapy might be a promising treatment modality and is expected to develop. In this review, we summarize recent clinical and preclinical data regarding IFN‐α and 5‐FU combination therapy and discuss the further prospects of this therapy.
Top‐down and bottom‐up effects on the spatiotemporal dynamics of cereal aphids: testing scaling theory for local density
Authors: Hambäck Peter A. , Vogt Majbritt , Tscharntke Teja , Thies Carsten , Englund Göran
Published: September 2007

The relationship between density and area depends on local growth rates and the area‐dependence of migration rates. These rates vary among taxa due to dispersal behaviour, plot productivity and natural enemy impact. Previous studies in aphids suggest that aphid densities are highest in patches of intermediate sizes, and lower in small and large patches. The suggested mechanism causing these patterns is that the dispersal behaviour in aphids creates a mixture of area‐ and perimeter‐dependent migration rates. In this paper, we used these predictions to examine the additional consequences of nutrient availability and natural enemies on the density‐area relationship. The derived predictions were compared to data from a system with three aphid species, a set of aphid parasitoids and generalist natural enemies, and at two levels of plant nutrient availability. We find that predictions from the model based only on dispersal and local growth agree with the temporal dynamics of density‐area relationships for aphids in high nutrient patches. In patches with low nutrients, high parasitism rates appeared to cause a negative density‐area relationship for aphids, thereby deviating from predictions driven by the aphids' dispersal behavior. Hence, the dispersal model with scale‐dependent migration rates can provide a useful tool for understanding insect distribution in patch size gradients, but the relative importance of top‐down effects can completely change with plot productivity.
Host‐parasite population dynamics under combined frequency‐ and density‐dependent transmission
Authors: Ryder Jonathan J. , Miller Martin R. , White Andy , Knell Robert J. , Boots Michael
Published: September 2007

Many host‐parasite models assume that transmission increases linearly with host population density (‘density‐dependent transmission’), but various alternative transmission functions have been proposed in an effort to capture the complexity of real biological systems. The most common alternative (usually applied to sexually transmitted parasites) assumes instead that the rate at which hosts contact one another is independent of population density, leading to ‘frequency‐dependent’ transmission. This straight‐forward distinction generates fundamentally different dynamics (e.g. deterministic, parasite‐driven extinction with frequency‐ but not density‐dependence). Here, we consider the situation where transmission occurs through two different types of contact, one of which is density‐dependent (e.g. social contacts), the other density‐independent (e.g. sexual contacts). Drawing on a range of biological examples, we propose that this type of contact structure may be widespread in natural populations. When our model is characterized mainly by density‐dependent transmission, we find that allowing even small amounts of transmission to occur through density‐independent contacts leads to the possibility of deterministic, parasite‐driven extinction (and lowers the threshold for parasite persistence). Contrastingly, allowing some density‐dependent transmission to occur in a model characterized mainly by density‐independent contacts (i.e. by frequency‐dependent transmission) does not affect the extinction threshold, but does increase the likelihood of parasite persistence.

The idea that directly transmitted parasites exploit different types of host contact is not new, but here we show that the impact on dynamics can be fundamental even in the simplest cases. For example, in systems where density‐dependent transmission is normally assumed de facto, we show that parasite‐driven extinction can occur if a small amount of transmission occurs through density‐independent contacts. Many empirical studies are still guided by the traditional density/frequency dichotomy, but our combined transmission function may provide a better model for systems in which both types of transmission occur.
Species‐specific limitation of vole population growth by least weasel predation: facilitation of coexistence?
Authors: Koivisto Elina , Huitu Otso , Sundell Janne , Korpimäki Erkki
Published: September 2007

Interspecific competition is usually understood as different species competing directly with each other for limited resources. However, predators can alter such competitive interactions substantially. Predation can promote the coexistence of species in a situation where it would otherwise be impossible, for example if a tradeoff between the competitive abilities and predation resistance of the prey species exists. The field vole Microtus agrestis and the sibling vole M. rossiaemeridionalis are sympatric grassland species, which compete for the same resources. At the population level sibling voles are suggested to be superior competitors to field voles, yet more vulnerable to predation. We tested the effects of predation on the two species in 0.5 ha outdoor enclosures by exposing vole populations to radio‐collared freely‐hunting least weasels Mustela nivalis nivalis for three weeks. Lethal and non‐lethal impacts of predation limited population densities of both species during and after the experimental period, but the effect was more pronounced in sibling voles in which population densities decreased markedly during the treatment period and even after that. Field vole population densities remained stable under weasel predation, while densities increased in controls. Survival in both species was lower in treatment populations compared to controls, but the effect tended to be more pronounced in sibling voles and in females of both species. The average mass of adults in both species declined in the treatment populations. These results suggest that predation by least weasels can limit vole populations locally, even during favourable summer conditions, and have extended negative effects on the dynamics of vole populations. In addition, predation alleviated interspecific competition between the vole species and is, therefore, a potential factor enabling the coexistence of them.
Winter commingling of populations of migratory species can cause breeding range underpopulation
Authors: Mills Alexander M. , Weir Colin J.
Published: September 2007

We build a model with large‐scale demographic consequences for migratory species. The model operates where four elements co‐occur, and we rely on empirical research using migratory birds to demonstrate them. First, breeding ranges have internal structure flowing from natal philopatry. Second, fecundity varies geographically. Third, populations of different breeding provenances commingle during winter. And fourth, a population‐limiting carrying capacity operates during winter. In the absence of breeding season population‐limitation, only the breeding population with maximum fecundity persists. Consequently, some potential breeding areas that offer suitable and productive habitat are bereft of breeding birds because of the interplay between the geographical fecundity gradient and the shared winter quarters. Where breeding season population‐limitation also plays a role for at least one population, one (or more) breeding population becomes permanently depressed, resulting in a density well below the carrying capacity of the productive breeding habitat that is occupied. In either case, not all populations fare equally well, despite net positive breeding season productivity. Changes in winter carrying capacity, for example habitat degradation in winter quarters, can lead to uneven effects on geographically defined breeding populations, even though there has been no change in the circumstances of the breeding range.
Drought induces lagged tree mortality in a subalpine forest in the Rocky Mountains
Authors: Bigler Christof , Gavin Daniel G. , Gunning Charles , Veblen Thomas T.
Published: September 2007

Extreme climatic events are key factors in initiating gradual or sudden changes in forest ecosystems through the promotion of severe, tree‐killing disturbances such as fire, blowdown, and widespread insect outbreaks. In contrast to these climatically‐incited disturbances, little is known about the more direct effect of drought on tree mortality, especially in high‐elevation forests. Therefore projections of drought‐induced mortality under future climatic conditions remain uncertain. For a subalpine forest landscape in the Rocky Mountains of northern Colorado (USA), we quantified lag effects of drought on mortality of Engelmann spruce Picea engelmannii, subalpine fir Abies lasiocarpa, and lodgepole pine Pinus contorta. For the period 1910–2004, we related death dates of 164 crossdated dead trees to early‐season and late‐season droughts. Following early‐season droughts, spruce mortality increased over five years and fir mortality increased sharply over 11 years. Following late‐season droughts, spruce showed a small increase in mortality within one year, whereas fir showed a consistent period of increased mortality over two years. Pine mortality was not affected by drought. Low pre‐drought radial growth rates predisposed spruce and fir to drought‐related mortality. Spruce and fir trees that died during a recent drought (2000–2004) had significantly lower pre‐drought growth rates than live neighbour trees. Overall, we found large interspecific differences in drought‐related mortality with fir showing the strongest effect followed by spruce and pine. This direct influence of climatic variability on differential tree mortality has the potential for driving large‐scale changes in subalpine forests of the Rocky Mountains.
Tolerance to apical and foliar damage: costs and mechanisms in Raphanus raphanistrum
Authors: Boalt Elin , Lehtilä Kari
Published: September 2007

To study mechanisms underlying plant tolerance to herbivore damage, we used apical and foliar damage as experimental treatments to study whether there are similar tolerance mechanisms to different types of damage. We also studied whether tolerance to different types of damage are associated, and whether there is a cost involved in plant tolerance to different types of herbivore damage. Our greenhouse experiment involved 480 plants from 30 full‐sib families of an annual weed Raphanus raphanistrum, wild radish, which were subjected to control and two different simulated herbivore damage treatments, apex removal and foliar damage of 30% of leaf area. Apical damage significantly decreased seed production, whereas foliar damage had no effect. There was a significant genetic variation for tolerance to foliar, but not apical damage. No costs were observed in terms of negative correlation between tolerance to either damage type and fitness of undamaged plants. Tolerances to apical and foliar damage were not significantly correlated with each other. We observed a larger number of significant associations between tolerance and reproductive traits than between tolerance and vegetative traits. Plant height and leaf size of damaged plants interacted in their association to tolerance to foliar damage. Inflorescence number and pollen quantity per flower of damaged plants were positively associated with tolerance to apical damage. In late‐flowering genotypes, petal size of undamaged plants and pollen quantity of damaged plants were positively associated with tolerance to foliar damage. In summary, traits involved in floral display and male fitness were associated with plant tolerance to herbivore damage.
Spatial synchrony in red grouse population dynamics
Authors: Kerlin Douglas H. , Haydon Daniel T. , Miller David , Aebischer Nicholas J. , Adam Smith A. , Thirgood Simon J.
Published: September 2007

Red grouse Lagopus lagopus scoticus populations exhibit unstable dynamics that are often characterised by regular periodic fluctuations in abundance. Time‐series’ of grouse harvesting records collected from 287 management units (moors) across Scotland, England and Wales were analysed to investigate the broad scale patterns of synchrony in these fluctuations. Estimation of the spatial autocorrelation of grouse population dynamics across moors indicates relatively high levels of synchrony between populations on adjacent moors, but that this synchrony declines sharply with increasing inter‐moor distance. At distances of greater than 100 km, grouse population time‐series exhibit only weakly positive cross‐correlation coefficients. Twenty‐eight geographical, environmental and other candidate variables were examined to construct a general linear model to explain variation in local synchrony. Grouse moor productivity (average size of shooting bag), distance from the Atlantic coast moving in a north‐easterly direction, April and June temperatures, and June rainfall significantly increased the explanatory power of this model. An understanding of the processes underlying synchrony in red grouse population dynamics is a prerequisite to anticipating the effects of large‐scale environmental change on regional patterns of grouse distribution and abundance.
Testing acoustic versus physical marking: two complementary methods for individual‐based monitoring of elusive species
Authors: Laiolo Paola , Vögeli Matthias , Serrano David , Tella José L.
Published: September 2007

Individuals of some species differentiate each other on the basis of the acoustic features of their vocalizations, and this can be used in individual‐based population monitoring studies. No research has tested for the effectiveness of individual marking through voice recognition as compared to traditional monitoring methods relying on physical marks. We compared voice recognition and physical marking using the Dupont's lark Chersophilus duponti as a study species. This bird needs to be attracted with playback in order to be seen (or captured). We first demonstrated that the territorial calls from a sample of banded males were individually distinctive and constant over time by means of discriminant function analysis, which correctly classified 100% of marked males. Then, we applied similarity techniques on call spectrotemporal features to define a threshold value of similarity within banded individuals, to be combined with qualitative spectrogram inspection for the classification of all recorded birds. Eventually, we compared the voice and the capture samples, to test for differences in relation to re‐location rate, territory fidelity and dispersal movements both within and between years. Voice recognition was less time‐consuming than capture‐recapture method in the field, but it was useless for monitoring yearlings in call development stage. The two methods provided the same results in terms of territory fidelity and dispersal movements, but differed in re‐location rates, which were significantly greater in the case of voice recognition method. By means of physical captures we possibly trapped a large sample of young and silent floaters, with low probability of recapture or recording. This mismatch between methods could bias the estimates of annual survival, which strongly depend on re‐location rates. We suggest considering the two methods as complementary rather than alternatives for monitoring populations. Each technique offers unique information, and the two sources should be combined to provide correction factors that would eventually sharpen our knowledge on bird population ecology.
Geographic variation in calcium and clutch size
Authors: Patten Michael A.
Published: September 2007

For over a half century numerous hypotheses have surfaced aimed at explaining a key life history trait, the evolution of clutch size in birds. A principal goal has been to explain why clutch size generally increases with latitude both within species and among closely related species. Most hypotheses have stressed food limitation, predation, or seasonality. I present a novel hypothesis to explain geographic variation: a limitation of calcium resulting from broad scale variation in this element. Because the storage capacity of avian medullary bone is limited or nonexistent, during egg formation, female birds must intake supplemental calcium. Yet calcium and other exchangeable bases are much rarer in tropical soils. I briefly review the abundant experimental and observational evidence supporting how calcium limitation affects clutch size and other life history traits, and I present a series of predictions (and apparent support for them), stemming from the calcium variation and limitation hypothesis. The balance of evidence suggests that variability in availability of environmental calcium plays a proximate and ultimate role in the evolution of clutch size. Although this hypothesis is not mutually exclusive with others, it highlights another factor that needs to be considered in studies of the geographic variation in clutch size.
Matters of the heart: the physiology of cardiac function and failure
Authors: Smith Godfrey
Published: September 2007

Heart failure as a result of a myocardial infarction (MI) is a common condition with a poor prognosis. The adaptive changes in the surviving myocardium appear to be insufficient in terms of both mechanical/contractile performance and electrical stability. The modification of the underlying myocardial physiology is complex, varying across the different layers within the wall of the ventricle and within one layer. Two therapeutic strategies are briefly discussed, as outlined here. (i) Enhancing contractility by alteration of the expression of a single protein (e.g. sarco‐endoplasmic reticulum Ca2+ ATPase, SERCA) could potentially reverse both mechanical and electrical abnormalities. However, experimental data involving the upregulation of SERCA suggest that the therapeutic range of this approach is narrow. (ii) The use of regular exercise training to improve cardiac performance in heart failure. This appears to act by normalizing a number of aspects of myocardial physiology.
Epoxygenases and peroxisome proliferator‐activated receptors in mammalian vascular biology
Authors: Wray Jessica , Bishop‐Bailey David
Published: September 2007

Epoxygenases, particularly of the CYP2C and CYP2J families, are important lipid‐metabolizing enzymes. Epoxygenases are found throughout the cardiovascular system where their lipid products, particularly the epoxyeicosatrienoic acids (EETs), which are arachidonic acid metabolites, have the potential to regulate vascular tone, cellular proliferation, migration, inflammation and cardiac function. The receptors for EETs are, however, poorly understood. The peroxisome proliferator‐activated receptors (PPARs) are a family of three (α, β/δ and γ) nuclear receptors that are activated by lipid metabolites. Activation of PPARα and PPARγ, similar to the longer term effects of EETs, causes the inhibition of vascular cell proliferation, migration and inflammation. Interestingly, EETs and their metabolites have recently been found to active both PPARα and PPARγ. The epoxygenase–EET–PPAR pathway may therefore represent a novel endogenous protective pathway by which short‐lived lipid mediators control vascular cell activation.
Neostigmine and pilocarpine attenuated tumour necrosis factor α expression and cardiac hypertrophy in the heart with pressure overload
Authors: Freeling Jessica , Wattier Kristina , LaCroix Carly , Li Yi‐Fan
Published: September 2007

The inflammatory cytokine tumour necrosis factor α (TNFα) is known to be a major factor contributing to cardiac remodelling and dysfunction. Parasympathetic nervous system cholinergic function can inhibit TNFα expression during systemic infection. In the present study, we tested the effects of a cholinesterase inhibitor, neostigmine, and a muscarinic cholinergic agonist, pilocarpine, on cardiac hypertrophy and TNFα levels during pressure overload. Rats with transverse aortic constriction exhibited elevated TNFα protein levels in the heart, increased heart weight to body weight ratios (an index of cardiac hypertrophy) and decreased left ventricular diastolic function. Two weeks of infusion with neostigmine (6 μg kg−1 day−1) or pilocarpine (0.3 mg kg−1 day−1) significantly reduced cardiac hypertrophy, reduced TNFα levels and elevated interleukin‐10 levels in heart tissues, and improved ventricular function in rats with transverse aortic constriction. Neither of these treatments significantly changed ventricular pressure load. Furthermore, in primary cultured neonatal cardiac cells, treatment with pilocarpine attenuated adrenergic agonist phenylephrine‐induced increased TNFα expression and [3H]leucine (a marker of protein synthesis) incorporation in the cells. Collectively, both cholinergic agents decreased TNFα levels and attenuated cardiac hypertrophy. Since both agents potentially enhanced cholinergic function, the anti‐inflammatory action may be involved in the cardioprotective effect of the treatments with these agents.
Climate and On-Farm Risk Factors Associated with
Giardia duodenalis
Cysts in Storm Runoff from California Coastal Dairies
Authors: Miller Woutrina A. , Lewis David J. , Lennox Michael , Pereira Maria G. C. , Tate Kenneth W. , Conrad Patricia A. , Atwill Edward R.
Published: September 2007

Climatic factors and on-farm management practices were evaluated for their association with the concentrations (cyst/liter) and instantaneous loads (cysts/second) of
Giardia duodenalis
in storm-based runoff from dairy lots and other high-cattle-use areas on five coastal California farms over two storm seasons. Direct fluorescent antibody analysis was used to quantitate cysts in 350 storm runoff samples.
G. duodenalis
was detected on all five dairy farms, with fluxes of 1 to 14,000 cysts/liter observed in 16% of samples. Cysts were detected in 41% of runoff samples collected near cattle less than 2 months old, compared to 10% of runoff samples collected near cattle over 6 months old. Furthermore, the concentrations and instantaneous loads of cysts were ≥65 and ≥79 times greater, respectively, in runoff from sites housing young calves than in sites housing other age classes of animals. Factors associated with environmental loading of
G. duodenalis
included cattle age, cattle stocking number, and precipitation but not lot area, land slope, or cattle density. Vegetated buffer strips were found to significantly reduce waterborne cysts in storm runoff: each additional meter of vegetated buffer placed below high-cattle-use areas was associated with reductions in the concentration and instantaneous load of cysts by factors of 0.86 and 0.79 (−0.07 and −0.10 log
10
/m), respectively. Straw mulch, seed application, scraping of manure, and cattle exclusion did not significantly affect the concentration or load of
G. duodenalis
cysts. The study findings suggest that vegetated buffer strips, especially when placed near dairy calf areas, should help reduce the environmental loading of these fecal protozoa discharging from dairy farms.
Influence of Native Microbiota on Survival of
Ralstonia solanacearum
Phylotype II in River Water Microcosms
Authors: Álvarez Belén , López María M. , Biosca Elena G.
Published: September 2007

Ralstonia solanacearum
phylotype II biovar 2 causes bacterial wilt in solanaceous hosts, producing severe economic losses worldwide. Waterways can be major dissemination routes of this pathogen, which is able to survive for long periods in sterilized water. However, little is known about its survival in natural water when other microorganisms, such as bacteriophages, other bacteria, and protozoa, are present. This study looks into the fate of a Spanish strain of
R. solanacearum
inoculated in water microcosms from a Spanish river, containing different microbiota fractions, at 24°C and 14°C, for a month. At both temperatures,
R. solanacearum
densities remained constant at the initial levels in control microcosms of sterile river water while, by contrast, declines in the populations of the introduced strain were observed in the nonsterile microcosms. These decreases were less marked at 14°C. Lytic bacteriophages present in this river water were involved in the declines of the pathogen populations, but indigenous protozoa and bacteria also contributed to the reduced persistence in water.
R. solanacearum
variants displaying resistance to phage infection were observed, but only in microcosms without protozoa and native bacteria. In water microcosms, the temperature of 14°C was more favorable for the survival of this pathogen than 24°C, since biotic interactions were slower at the lower temperature. Similar trends were observed in microcosms inoculated with a Dutch strain. This is the first study demonstrating the influence of different fractions of water microorganisms on the survival of
R. solanacearum
phylotype II released into river water microcosms.
Heterologous Production of Dihomo-γ-Linolenic Acid in
Saccharomyces cerevisiae
Authors: Yazawa Hisashi , Iwahashi Hitoshi , Kamisaka Yasushi , Kimura Kazuyoshi , Aki Tsunehiro , Ono Kazuhisa , Uemura Hiroshi
Published: September 2007

To make dihomo-γ-linolenic acid (DGLA) (20:3n-6) in
Saccharomyces cerevisiae
, we introduced
Kluyveromyces lactis
Δ12 fatty acid desaturase, rat Δ6 fatty acid desaturase, and rat elongase genes. Because Fad2p is able to convert the endogenous oleic acid to linoleic acid, this allowed DGLA biosynthesis without the need to supply exogenous fatty acids on the media. Medium composition, cultivation temperature, and incubation time were examined to improve the yield of DGLA. Fatty acid content was increased by changing the medium from a standard synthetic dropout medium to a nitrogen-limited minimal medium (NSD). Production of DGLA was higher in the cells grown at 15°C than in those grown at 20°C, and no DGLA production was observed in the cells grown at 30°C. In NSD at 15°C, fatty acid content increased up until day 7 and decreased after day 10. When the cells were grown in NSD for 7 days at 15°C, the yield of DGLA reached 2.19 μg/mg of cells (dry weight) and the composition of DGLA to total fatty acids was 2.74%. To our knowledge, this is the first report describing the production of polyunsaturated fatty acids in
S. cerevisiae
without supplying the exogenous fatty acids.
Sensitive and Specific Molecular Detection of
Burkholderia pseudomallei
, the Causative Agent of Melioidosis, in the Soil of Tropical Northern Australia
Authors: Kaestli Mirjam , Mayo Mark , Harrington Glenda , Watt Felicity , Hill Jason , Gal Daniel , Currie Bart J.
Published: September 2007

Burkholderia pseudomallei
, the cause of the severe disease melioidosis in humans and animals, is a gram-negative saprophyte living in soil and water of areas of endemicity such as tropical northern Australia and Southeast Asia. Infection occurs mainly by contact with wet contaminated soil. The environmental distribution of
B. pseudomallei
in northern Australia is still unclear. We developed and evaluated a direct soil
B. pseudomallei
DNA detection method based on the recently published real-time PCR targeting the
B. pseudomallei
type III secretion system. The method was evaluated by inoculating different soil types with
B. pseudomallei
dilution series and by comparing
B. pseudomallei
detection rate with culture-based detection rate for 104 randomly collected soil samples from the Darwin rural area in northern Australia. We found that direct soil
B. pseudomallei
DNA detection not only was substantially faster than culture but also proved to be more sensitive with no evident false-positive results. This assay provides a new tool to detect
B. pseudomallei
in soil samples in a fast and highly sensitive and specific manner and is applicable for large-scale
B. pseudomallei
environmental screening studies or in outbreak situations. Furthermore, analysis of the 104 collected soil samples revealed a significant association between
B. pseudomallei
-positive sites and the presence of animals at these locations and also with moist, reddish brown-to-reddish gray soils.
Metabolic Engineering ofLactobacillus plantarumfor Production ofl-Ribulose
Authors: Helanto M. , Kiviharju K. , Leisola M. , Nyyssölä A.
Published: September 2007

l-Ribulose is a rare and expensive sugar that can be used as a precursor for the production of other rare sugars of high market value such asl-ribose. In this work we describe a production process forl-ribulose usingl-arabinose, a common component of polymers of lignocellulosic materials, as the starting material. A ribulokinase-deficient mutant of the heterofermentative lactic acid bacteriumLactobacillus plantarumNCIMB8826 was constructed. Expression ofaraA, which encodes the critical enzymel-arabinose isomerase, was repressed by high glucose concentrations in batch cultivations. A fed-batch cultivation strategy was therefore used to maximizel-arabinose isomerase production during growth. Resting cells of the ribulokinase-deficient mutant were used for the production ofl-ribulose. The isomerization ofl-arabinose tol-ribulose was very unfavorable forl-ribulose formation. However, highl-ribulose yields were obtained by complexing the producedl-ribulose with borate. The process forl-ribulose production in borate buffer by resting cells was optimized using central composite designs. The experiment design suggested that the process has an optimal operation point around anl-arabinose concentration of 100 g liter−1, a borate concentration of 500 mM, and a temperature of 48°C, where the statistical software predicted an initiall-ribulose production rate of 29.1 g liter−1h−1, a best-achievable process productivity of 14.8 g liter−1h−1, and a conversion ofl-arabinose tol-ribulose of 0.70 mol mol−1.
Impact of Zooplankton Grazing on the Excystation, Viability, and Infectivity of the Protozoan Pathogens
Cryptosporidium parvum
and
Giardia lamblia
Authors: Connelly S. J. , Wolyniak E. A. , Dieter K. L. , Williamson C. E. , Jellison K. L.
Published: September 2007

Very little is known about the ability of the zooplankton grazer
Daphnia pulicaria
to reduce populations of
Giardia lamblia
cysts and
Cryptosporidium parvum
oocysts in surface waters. The potential for
D. pulicaria
to act as a biological filter of
C. parvum
and
G. lamblia
was tested under three grazing pressures (one, two, or four
D. pulicaria
grazers per 66 ml). (Oo)cysts (1 × 10
4
per 66 ml) were added to each grazing bottle along with the algal food
Selenastrum capricornutum
(6.6 × 10
4
cells per 66 ml) to stimulate normal grazing. Bottles were rotated (2 rpm) to prevent settling of (oo)cysts and algae for 24 h (a light:dark cycle of 16 h:8 h) at 20°C. The impact of
D. pulicaria
grazing on (oo)cysts was assessed by (i) (oo)cyst clearance rates, (ii) (oo)cyst viability, (iii) (oo)cyst excystation, and (iv) oocyst infectivity in cell culture. Two
D. pulicaria
grazers significantly decreased the total number of
C. parvum
oocysts by 52% and
G. lamblia
cysts by 44%. Furthermore, two
D. pulicaria
grazers significantly decreased
C. parvum
excystation and infectivity by 5% and 87%, respectively. Two
D. pulicaria
grazers significantly decreased the viability of
G. lamblia
cysts by 52%, but analysis of
G. lamblia
excystation was confounded by observed mechanical disruption of the cysts after grazing. No mechanical disruption of the
C. parvum
oocysts was observed, presumably due to their smaller size. The data provide strong evidence that zooplankton grazers have the potential to substantially decrease the population of infectious
C. parvum
and
G. lamblia
in freshwater ecosystems.
Acanthamoeba
-
Campylobacter
Coculture as a Novel Method for Enrichment of
Campylobacter
Species
Authors: Axelsson-Olsson Diana , Ellström Patrik , Waldenström Jonas , Haemig Paul D. , Brudin Lars , Olsen Björn
Published: September 2007

In this study, we present a novel method to isolate and enrich low concentrations of
Campylobacter
pathogens. This method,
Acanthamoeba
-
Campylobacter
coculture (ACC), is based on the intracellular survival and multiplication of
Campylobacter
species in the free-living protozoan
Acanthamoeba polyphaga
. Four of the
Campylobacter
species relevant to humans and livestock,
Campylobacter jejuni
,
C. coli
,
C. lari
, and
C. hyointestinalis
, were effectively enriched by the coculture method, with growth rates comparable to those observed in other
Campylobacter
enrichment media. Studying six strains of
C. jejuni
isolated from different sources, we found that all of the strains could be enriched from an inoculum of fewer than 10 bacteria. The sensitivity of the ACC method was not negatively affected by the use of
Campylobacter
-selective antibiotics in the culture medium, but these were effective in suppressing the growth of seven different bacterial species added at a concentration of 10
4
CFU/ml of each species as deliberate contamination. The ACC method has advantages over other enrichment methods as it is not dependent on a microaerobic milieu and does not require the use of blood or other oxygen-quenching agents. Our study found the ACC method to be a promising tool for the enrichment of
Campylobacter
species, particularly from water samples with low bacterial concentrations.