Cultivares e sistemas de cultivo de cebola no verão.

O presente trabalho foi realizado em São José do Rio Pardo. com o objetivo de avaliar o comportamento de cultivares de cebola Alfa Tropical, Alfa São Francisco e Mercedes em quatro sistemas de cultivo no verão. O experimento foi conduzido no delineamento de blocos casualizados, com quatro repetições e arranjo em parcelas subdivididas. Muda's de cebola produzidas em canteiros ou em bandejas de 200 células foram transplantadas em sistema convencional e direto na palha. A interação entre sistemas de cultivo e ,cultivares foi significativa na produtividade e incidência do mal-das-sete-voltas. A produtividade total variou entre 0.7 e 55.1 t ha-1. sendo as mais baixas produtividades obtidas com a cultivar Mercedes em todos os sistemas de cultivo. Foi observado que a produtividade e a precocidade de colheita foram maiores ou a incidência do mal-das-sete-voltas menor com as mudas de bandejas/ Em geral, a produtividade ou a precocidade de colheita tenderam a aumentar com a redução do preparo do solo. O transplantio direto na palha de mudas de bandejas é uma opção viável para a produção de cebola com sustentabilidade ambiental no verão.Suplemento. Edição dos resumos expandidos do 46. Congresso Brasileiro de Olericultura, Goiânia, ago. 2006

Methods for detecting PER2::LUCIFERASE bioluminescence rhythms in freely moving mice [preprint]

Circadian rhythms are driven by daily oscillations of gene expression. An important tool for studying cellular and tissue rhythms is the use of a gene reporter, such as bioluminescence from the reporter gene luciferase controlled by a rhythmically expressed gene of interest. Here we describe methods that allow measurement of bioluminescence from a freely-moving mouse housed in a standard cage. Using a LumiCycle In Vivo (Actimetrics), we determined conditions that allow detection of circadian rhythms of bioluminescence from the PER2 reporter, PER2::LUC, in freely behaving mice. We tested delivery of D-luciferin via a subcutaneous minipump and in the drinking water. Further, we demonstrate that a synthetic luciferase substrate, CycLuc1, can support circadian rhythms of bioluminescence, even when delivered at a lower concentration than D-luciferin. We share our analysis scripts and suggestions for further improvements in this method. This approach will be straightforward to apply to mice with tissue-specific reporters, allowing insights into responses of specific peripheral clocks to perturbations such as environmental or pharmacological manipulations

Continuous and non-invasive thermography of mouse skin accurately describes core body temperature patterns, but not absolute core temperature

Body temperature is an important physiological parameter in many studies of laboratory mice. Continuous assessment of body temperature has traditionally required surgical implantation of a telemeter, but this invasive procedure adversely impacts animal welfare. Near-infrared thermography provides a non-invasive alternative by continuously measuring the highest temperature on the outside of the body (Tskin), but the reliability of these recordings as a proxy for continuous core body temperature (Tcore) measurements has not been assessed. Here, Tcore (30 s resolution) and Tskin (1 s resolution) were continuously measured for three days in mice exposed to ad libitum and restricted feeding conditions. We subsequently developed an algorithm that optimised the reliability of a Tskin-derived estimate of Tcore. This identified the average of the maximum Tskin per minute over a 30-min interval as the optimal way to estimate Tcore. Subsequent validation analyses did however demonstrate that this Tskin-derived proxy did not provide a reliable estimate of the absolute Tcore due to the high between-animal variability in the relationship between Tskin and Tcore. Conversely, validation showed that Tskin-derived estimates of Tcore reliably describe temporal patterns in physiologically-relevant Tcore changes and provide an excellent measure to perform within-animal comparisons of relative changes in Tcore

Modelling mammalian energetics: the heterothermy problem

Global climate change is expected to have strong effects on the world’s flora and fauna. As a result, there has been a recent increase in the number of meta-analyses and mechanistic models that attempt to predict potential responses of mammals to changing climates. Many models that seek to explain the effects of environmental temperatures on mammalian energetics and survival assume a constant body temperature. However, despite generally being regarded as strict homeotherms, mammals demonstrate a large degree of daily variability in body temperature, as well as the ability to reduce metabolic costs either by entering torpor, or by increasing body temperatures at high ambient temperatures. Often, changes in body temperature variability are unpredictable, and happen in response to immediate changes in resource abundance or temperature. In this review we provide an overview of variability and unpredictability found in body temperatures of extant mammals, identify potential blind spots in the current literature, and discuss options for incorporating variability into predictive mechanistic models

De trage verbreiding van de auto in Nederland 1896-1939. De invloed van ondernemers, gebruikers en overheid

Contains fulltext : 44030.pdf (Publisher’s version ) (Open Access)Radboud Universiteit Nijmegen, 26 juni 2007Promotor : Klep, P.M.M. Co-promotor : Bots, A.C.A.M.480 p

Flexible clock systems: adjusting the temporal program

Under natural conditions, many aspects of the abiotic and biotic environment vary with time of day, season or even era, whilst these conditions are typically kept constant in laboratory settings. The timing information contained within the environment serve as critical timing cues for the internal biological timing system, but how this system drives daily rhythms in behaviour and physiology may also depend on the internal state of the animal. The disparity between timing of these cues in natural and laboratory conditions can result in substantial differences in the scheduling of behaviour and physiology under these conditions. In nature, temporal coordination of biological processes is critical to maximise fitness because they optimise the balance between reproduction, foraging, and predation risk. Here we focus on the role of peripheral circadian clocks, and the rhythms that they drive, in enabling adaptive phenotypes. We discuss how reproduction, endocrine activity and metabolism interact with peripheral clocks, and outline the complex phenotypes arising from changes in this system. We conclude that peripheral timing is critical to adaptive plasticity of circadian organisation in the field, and that we must abandon standard laboratory conditions to understand the mechanisms that underlie this plasticity which maximises fitness under natural conditions