A physiological framework to explain genetic and environmental regulation of tillering in sorghum

Tillering determines the plant size of sorghum (Sorghum bicolor) and an understanding of its regulation is important to match genotypes to prevalent growing conditions in target production environments. The aim of this study was to determine the physiological and environmental regulation of variability in tillering among sorghum genotypes, and to develop a framework for this regulation. * Diverse sorghum genotypes were grown in three experiments with contrasting temperature, radiation and plant density to create variation in tillering. Data on phenology, tillering, and leaf and plant size were collected. A carbohydrate supply/demand (S/D) index that incorporated environmental and genotypic parameters was developed to represent the effects of assimilate availability on tillering. Genotypic differences in tillering not explained by this index were defined as propensity to tiller (PTT) and probably represented hormonal effects. * Genotypic variation in tillering was associated with differences in leaf width, stem diameter and PTT. The S/D index captured most of the environmental effects on tillering and PTT most of the genotypic effects. * A framework that captures genetic and environmental regulation of tillering through assimilate availability and PTT was developed, and provides a basis for the development of a model that connects genetic control of tillering to its phenotypic consequences.

Social and environmental regulation of signal plasticity and signal reliability in the electric fish Brachyhypopomus gauderio

The balance between the costs and benefits of conspicuous signals ensures that the expression of those signals is related to the quality of the bearer. Plastic signals could enable males to maximize conspicuous traits to impress mates and competitors, but reduce the expression of those traits to minimize signaling costs, potentially compromising the information conveyed by the signals. ^ I investigated the effect of signal enhancement on the information coded by the biphasic electric signal pulse of the gymnotiform fish Brachyhypopomus gauderio. Increases in population density drive males to enhance the amplitude of their signals. I found that signal amplitude enhancement improves the information about the signaler's size. Furthermore, I found that the elongation of the signal's second phase conveys information about androgen levels in both sexes, gonad size in males and estrogen levels in females. Androgens link the duration of the signal's second phase to other androgen-mediated traits making the signal an honest indicator of reproductive state and aggressive motivation. ^ Signal amplitude enhancement facilitates the assessment of the signaler's resource holding potential, important for male-male interactions, while signal duration provides information about aggressive motivation to same-sex competitors and reproductive state to the opposite sex. Moreover, I found that female signals also change in accordance to the social environment. Females also increase the amplitude of their signal when population density increases and elongate the duration of their signal's second phase when the sex ratio becomes female-biased. Indicating that some degree of sexual selection operates in females. ^ I studied whether male B. gauderio use signal plasticity to reduce the cost of reproductive signaling when energy is limited. Surprisingly, I found that food limitation promotes the investment in reproduction manifested as signal enhancement and elevated androgen levels. The short lifespan and single breeding season of B. gauderio diminishes the advantage of energy savings and gives priority to sustaining reproduction. I conclude that the electric signal of B. gauderio provides reliable information about the signaler, the quality of this information is reinforced rather than degraded with signal enhancement.^

El fin de la operación minera: implicaciones jurídicas desde lo ambiental y social

Algunos de los efectos ambientales y sociales que se pueden apreciar luego del cierre de una mina son la desaparición de acuíferos, la existencia de aguas superficiales contaminadas con sustancias químicas y la afectación a la salud de las personas que viven cerca de minas abandonadas. Esta investigación busca analizar los principales aspectos jurídicos relacionados con la terminación y cierre definitivo de la operación minera desde el punto de vista social y ambiental. Para ello, se presentan los principales efectos ambientales y sociales de ésta terminación; se mencionan los aspectos jurídicos más relevantes del contrato de concesión minera y de la licencia ambiental; se exponen las obligaciones jurídicas que están a cargo tanto del concesionario minero como de las autoridades competentes respecto del cierre de la mina y el papel que asumen los entes de control frente a la terminación y cierre de la mina. Así mismo, se hace un breve análisis de derecho comparado de la regulación en España y Estados Unidos sobre éste tema. Finalmente, se presentan los resultados de la revisión de los expedientes administrativos que fueron proporcionados por la Agencia Nacional de Minería, en los cuales se determina la aplicación y cumplimiento en la práctica de estas obligaciones jurídicas del concesionario minero al término del contrato. Con base a los resultados obtenidos, se puede concluir, en primer lugar, que las obligaciones a cargo de los concesionarios mineros no están claras por parte de la regulación minera y ambiental; en segundo lugar, que la regulación en cuanto al cierre de minas en España y Estados Unidos es más ordenada, completa y específica y; en tercer lugar, en relación con los expedientes analizados, se puede observar que los concesionarios y las autoridades competentes no están cumpliendo sus respectivas obligaciones.

Why do policy decision-makers opt for command and control environmental regulation? An economic analysis with special reference to Sri Lanka

This chapter examines why policy decision-makers opt for command and control environmental regulation despite the availability of a plethora of market-based instruments which are more efficient and cost-effective. Interestingly, Sri Lanka has adopted a wholly command and control system, during both the pre and post liberalisation economic policies. This chapter first examines the merits and demerits of command and control and market-based approaches and then looks at Sri Lanka’s extensive environmental regulatory framework. The chapter then examines the likely reasons as to why the country has gone down the path of inflexible regulatory measures and has become entrenched in them. The various hypotheses are discussed and empirical evidence is provided. The chapter also discusses the consequences of an environmentally slack economy and policy implications stemming from adopting a wholly regulatory approach. The chapter concludes with a discussion of the main results.

Temporal trend of pesticide concentrations in the Chikugo River (Japan) with changes in environmental regulation and field infrastructure

Contamination of pesticides, which are applied to rice paddy fields, in river water has been a major problem in Japan for decades. A prolonged water holding period after pesticide application in paddy fields is expected to reduce the concentration of rice pesticides in river water. Therefore, a long monitoring campaign was conducted from 2004 to 2010 to measure the concentrations of pesticides in water samples collected from several points along the Chikugo River (Japan) including tributaries and the main stream to see if there was any reduction in the level of pesticide contamination after the extension of the water holding period (from 3–4 days to 7 days) was introduced in 2007 by the new water management regulation. No significant difference (p > 0.05) was found in pesticide concentrations between the periods before and after 2007 in all monitoring points, except in one tributary where the pesticide concentrations after 2007 were even higher than that of the previous period. A detailed study in one of the tributaries also revealed that the renovated infrastructure did not reduce the pesticide concentrations in the drainage canals. Neither the introduction of the new regulation nor the improved infrastructure had any significant effect on reducing the contamination of pesticides in water of the Chikugo River. It is probably because most farmers did not properly implement the new requirement of holding paddy water within the field for 7 days after the application of pesticides. Only tightening the regulation would not be sufficient and more actions should be taken to enforce/provide extension support for the new water management regulation in order to reduce the level of residual pesticides in river water in Japan.

An Imperial Legacy? An Exploration of the environmental impact of ancient metal mining and smelting in southern Jordan

Pyatt, B. Gilmore, G. Grattan, J. Hunt, C. McLaren, S. An imperial legacy? An exploration of the environmental impact of ancient metal mining and smelting in southern Jordan. Journal of Archaeological Science. 2000. 27 pp 771-778

Study of Perkinsus olseni infection mechanisms: identification and regulation of parasite genes differentially expressed in response to host and environmental stress

Tese dout., Biologia, Universidade do Algarve, 2008

The regulation of adult hippocampal neurogenesis by wheel running and environmental enrichment

Introduction: Chez les mammifères, la naissance de nouveaux neurones se poursuit à l’âge adulte dans deux régions du cerveau: 1) l’hippocampe et 2) la zone sous-ventriculaire du prosencéphale. La neurogenèse adulte n’est pas un processus stable et peut être affectée par divers facteurs tels que l’âge et la maladie. De plus, les modifications de la neurogenèse peuvent être à l’origine des maladies de sorte que la régulation ainsi que le rétablissement de la neurogenèse adulte doivent être considérés comme d’importants objectifs thérapeutiques. Chez la souris saine ou malade, la neurogenèse hippocampale peut être fortement régulée par l’enrichissement environnemental ainsi que par l’activité physique. Cependant, lors même que l’activité physique et l’enrichissement environnemental pourraient contribuer au traitement de certaines maladies, très peu d’études porte sur les mécanismes moléculaires et physiologiques responsables des changements qui sont en lien avec ces stimuli. Objectifs et hypothèses: Les principaux objectifs de cette étude sont de caractériser les effets de stimuli externes sur la neurogenèse et, par le fait même, d’élucider les mécanismes sous-jacents aux changements observés. En utilisant le modèle d’activité physique volontaire sur roue, cette étude teste les deux hypothèses suivantes: tout d’abord 1) qu’une période prolongée d’activité physique peut influencer la neurogenèse adulte dans le prosencéphale et l’hippocampe, et 2) que l’activité volontaire sur roue peut favoriser la neurogenèse à travers des stimuli dépendants ou indépendants de la course. Méthodes: Afin de valider la première hypothèse, nous avons utilisé un paradigme incluant une activité physique volontaire prolongée sur une durée de six semaines, ainsi que des analyses immunohistochimiques permettant de caractériser l’activité de précurseurs neuronaux dans la zone sous-ventriculaire et l’hippocampe. Ensuite, pour valider la seconde hypothèse, nous avons utlisé une version modifiée du paradigme ci-dessous, en plaçant les animaux (souris) soit dans des cages traditionnelles, soit dans des cages munies d’une roue bloquée soit dans des cages munies d’une roue fonctionnelle. Résultats: En accord avec la première hypothèse, l’activité physique prolongée volontaire a augmenté la prolifération des précurseurs neuronaux ainsi que la neurogenèse dans le gyrus dentelé de l’hippocampe comparativement aux animaux témoins, confirmant les résultats d’études antérieures. Par ailleurs, dans ce paradigme, nous avons aussi observé de la prolifération acrue au sein de la zone sous-ventriculaire du prosencéphale. De plus, en accord avec la seconde hypothèse, les souris placées dans une cage à roue bloquée ont montré une augmentation de la prolifération des précurseurs neuronaux dans l’hippocampe comparable à celle observée chez les souris ayant accès à une roue fonctionnelle (coureurs). Cependant, seuls les animaux coureurs ont présenté une augmentation de la neurogenèse hippocampale. Conclusions: Ces résultats nous ont permis de tirer deux conclusions nouvelles concernant les effets de l’activité physique (course) sur la neurogenèse. Premièrement, en plus de la prolifération et de la neurogenèse dans le gyrus dentelé de l’hippocampe, la prolifération dans la zone sous-ventriculaire du prosencéphale peut être augmentée par l’activité physique sur roue. Deuxièmement, l’environnement dans lequel l’activité physique a lieu contient différents stimuli qui peuvent influencer certains aspects de la neurogenèse hippocampale en l’absence d’activité physique sur roue (course).

Environmental regulation and colonization attributes of the long polar fimbriae (LPF) of Escherichia coli O157:H7

The ability of Escherichia coli O157:H7 to colonize the intestinal epithelia is dependent on the expression of intimin and other adhesins. The chromosome of E. coli O157:H7 carries two loci encoding long polar fimbriae (LPF). These fimbriae mediate adherence to epithelial cells and are associated with colonization of the intestine. In order to increase our knowledge about the conditions controlling their expression and their role in colonization of an animal model, the environmental cues that promote expression of lpf genes and the role of E. coli O157:H7 LPF in intestinal colonization of lambs were investigated. We found that expression of lpf1 was regulated in response to growth phase, osmolarity, and pH; that lpf2 transcription was stimulated during late exponential growth and iron depletion; and that LPF impacts the ability of E. coli O157:H7 to persist in the intestine of infected 6-week-old lambs.

Environmental regulation, technology adoption and structural transformation: evidence from Brazilian sugarcane industry

We estimate the effects of the adoption of mechanized agriculture led by a new environmental regulation on structural change of local labor markets within a large emerging country, Brazil. In 2002, the state of S\~{a}o Paulo passed a law outlying the timeline to end sugarcane pre-harvest burning in the state. The environmental law led to the fast adoption of mechanized harvest. We investigate if the labor intensity of sugarcane production decreases; and, if so, if it leads to structural changes in the labor market. We use satellite data containing the type of sugarcane harvesting -- manual or mechanic harvest -- paired with official labor market data.%, also geomorphometric data base for our instrumental variable correction. We find suggestive evidence that mechanization of the field led to an increase in utilization of formal workers and a reduction in formal labor intensity in the sugarcane sector. This is partially compensated by an increase in the share of workers in other agricultural crops and in the construction and services sector. Although we find a reduction in employment in the manufacturing sector, the demand generated by the new agro-industries affected positively the all sectors via an increase in workers' wage.

Down-regulation of porin M35 in Moraxella catarrhalis by aminopenicillins and environmental factors and its potential contribution to the mechanism of resistance to aminopenicillins

The outer membrane protein M35 of Moraxella catarrhalis is an antigenically conserved porin. Knocking out M35 significantly increases the MICs of aminopenicillins. The aim of this study was to determine the biological mechanism of this potentially new antimicrobial resistance mechanism of M. catarrhalis and the behaviour of M35 in general stress situations.