On the dynamics of the adenylate energy system: homeorhesis vs homeostasis.

Biochemical energy is the fundamental element that maintains both the adequate turnover of the biomolecular structures and the functional metabolic viability of unicellular organisms. The levels of ATP, ADP and AMP reflect roughly the energetic status of the cell, and a precise ratio relating them was proposed by Atkinson as the adenylate energy charge (AEC). Under growth-phase conditions, cells maintain the AEC within narrow physiological values, despite extremely large fluctuations in the adenine nucleotides concentration. Intensive experimental studies have shown that these AEC values are preserved in a wide variety of organisms, both eukaryotes and prokaryotes. Here, to understand some of the functional elements involved in the cellular energy status, we present a computational model conformed by some key essential parts of the adenylate energy system. Specifically, we have considered (I) the main synthesis process of ATP from ADP, (II) the main catalyzed phosphotransfer reaction for interconversion of ATP, ADP and AMP, (III) the enzymatic hydrolysis of ATP yielding ADP, and (IV) the enzymatic hydrolysis of ATP providing AMP. This leads to a dynamic metabolic model (with the form of a delayed differential system) in which the enzymatic rate equations and all the physiological kinetic parameters have been explicitly considered and experimentally tested in vitro. Our central hypothesis is that cells are characterized by changing energy dynamics (homeorhesis). The results show that the AEC presents stable transitions between steady states and periodic oscillations and, in agreement with experimental data these oscillations range within the narrow AEC window. Furthermore, the model shows sustained oscillations in the Gibbs free energy and in the total nucleotide pool. The present study provides a step forward towards the understanding of the fundamental principles and quantitative laws governing the adenylate energy system, which is a fundamental element for unveiling the dynamics of cellular life

Kinder-Umwelt-Survey (KUS) im Rahmen des Kinder- und Jugendgesundheitssurveys (KiGGS) : Erste Ergebnisse

Der Kinder-Umwelt-Survey (KUS) ist das Umwelt-Modul des Kinder- und Jugendgesundheitssurveys (KiGGS) des Robert Koch-Institutes und der vierte Umwelt-Survey des Umweltbundesamtes. Das Hauptziel des KUS ist die Erfassung, Bereitstellung, Aktualisierung und Bewertung repräsentativer Daten über die Exposition von Kindern in Deutschland mit Umweltschadstoffen und -noxen auf nationaler Ebene. Von 2003–2006 wurde bei 1790 Kindern im Alter von 3–14 Jahren aus 150 Orten die umfangreiche Datenbasis des KUS erhoben. Dazu wurden Blut-, Urin-, Trinkwasser-, Hausstaub- und Innenraumluftproben untersucht sowie Screening-Hörtests, Schallpegelmessungen und Befragungen zu expositionsbeeinflussenden Faktoren durchgeführt. Die ersten Ergebnisse weisen einen deutlichen Rückgang der inneren Arsen-, Blei- und Quecksilberbelastung der Kinder in Deutschland nach. Die Belastung der Kinder durch Passivrauchen wird anhand der Cotiningehalte im Urin verifiziert. Im Bereich der Belastung des häuslichen Trinkwassers liegen auch für 2003–2006 Hinweise vor, dass die Grenzwerte der Trinkwasserverordnung (TrinkwV) in einigen Haushalten überschritten sein könnten. Dies gilt vor allem für die Elemente Nickel, Kupfer und Blei, die unter anderem durch das Material der Hausinstallation in das Trinkwasser gelangen können. Schlüsselwörter Gesundheitssurvey - Kinder - Jugendliche - KUS - Umwelt - Human-Biomonitoring - Trinkwasser --------------------------------------------------------------------------------The German Environmental Survey for Children (GerES IV) is the environment-related module of the German Health Interview and Examination Survey for Children and Adolescents (KiGGS) of the Robert Koch Institute and the fourth GerES of the Federal Environment Agency. The main objective of GerESs is to analyse and document the extent, distribution and determinants of exposure to environmental pollutants of the German general population. GerES IV was performed from 2003 to 2006. A total of 1.790 children aged 3–14 years from 150 sampling locations participated in GerES IV. Samples of blood, urine, tap water, house dust and indoor air were analysed. Hearing tests, measurements of traffic noise and interviews to get exposure-related information were conducted. First results indicate a clear decrease of the exposure to arsenic, lead and mercury. Cotinine concentrations in urine can be used to classify the exposure of children to environmental tobacco smoke. The examination of the tap water used in the subjects' households indicates that in some households the guideline values of the German Drinking Water Ordinance were not always met. This is the case for nickel, copper and lead which are used as pipe material for domestic plumbing

The Family Rhodobacteraceae

The family Rhodobacteraceae can be considered a paradigm of modern taxonomy of prokaryotes. Taking into account the number of species and genera that conforms the family, together with the knowledge about their abundance and vast global distribution, it surprises that most of them have been described relatively recent to our days. Two notable exceptions are Rhodonostoc capsulatum (Molisch, Die purpurbakterien nach neuen untersuchungen, vols i–vii. G. Fischer, Jena, pp 1–95, 1907) and Micrococcus denitrificans Beijerinck and Minkman (Zentbl Bakteriol, Parasitenkd, Infektionskr Hyg. Abt II 25:30–63, 1910), early basonyms of Rhodobacter capsulatus and Paracoccus denitrificans, respectively. The fact that so many descriptions within this family are recent means that some studies have been concomitant and pose a challenge not only for pure taxonomic studies but also for interpreting other studies in which a rapidly evolving nomenclature had to be used anyway. The metabolic and ecological diversity of the group adds further complexity. In spite of all these difficulties, the picture is far from being a chaos and it can be considered an exciting and important bacterial group to study. Rhodobacteraceae are, fundamentally, aquatic bacteria that frequently thrive in marine environments. They comprise mainly aerobic photo- and chemoheterotrophs but also purple non-sulfur bacteria which perform photosynthesis in anaerobic environments. They are deeply involved in sulfur and carbon biogeochemical cycling and symbiosis with aquatic micro- and macroorganisms. One hundred genera are currently recognized as members of the family although the Stappia group, Ahrensia, Agaricicola, and Rhodothalassium do not belong, phylogenetically, to the family. The 90 other genera are distributed in 5 phylogenetic groups (the Rhodobacter, the Paracoccus, the Rhodovulum, the Amaricoccus, and the Roseobacter clades) that might be considered a family on its own