The impact of flooding on aquatic ecosystem services

Flooding is a major disturbance that impacts aquatic ecosystems and the ecosystem services that they provide. Predicted increases in global flood risk due to land use change and water cycle intensification will likely only increase the frequency and severity of these impacts. Extreme flooding events can cause loss of life and significant destruction to property and infrastructure, effects that are easily recognized and frequently reported in the media. However, flooding also has many other effects on people through freshwater aquatic ecosystem services, which often go unrecognized because they are less evident and can be difficult to evaluate. Here, we identify the effects that small magnitude frequently occurring floods (<?10-year recurrence interval) and extreme floods (>?100-year recurrence interval) have on ten aquatic ecosystem services through a systematic literature review. We focused on ecosystem services considered by the Millennium Ecosystem Assessment including: (1) supporting services (primary production, soil formation), (2) regulating services (water regulation, water quality, disease regulation, climate regulation), (3) provisioning services (drinking water, food supply), and (4) cultural services (aesthetic value, recreation and tourism). The literature search resulted in 117 studies and each of the ten ecosystem services was represented by an average of 12?±?4 studies. Extreme floods resulted in losses in almost every ecosystem service considered in this study. However, small floods had neutral or positive effects on half of the ecosystem services we considered. For example, small floods led to increases in primary production, water regulation, and recreation and tourism. Decision-making that preserves small floods while reducing the impacts of extreme floods can increase ecosystem service provision and minimize losses.     

Watershed ‘chemical cocktails’: forming novel elemental combinations in Anthropocene fresh waters

In the Anthropocene, watershed chemical transport is increasingly dominated by novel combinations of elements, which are hydrologically linked together as ‘chemical cocktails.’ Chemical cocktails are novel because human activities greatly enhance elemental concentrations and their probability for biogeochemical interactions and shared transport along hydrologic flowpaths. A new chemical cocktail approach advances our ability to: trace contaminant mixtures in watersheds, develop chemical proxies with high-resolution sensor data, and manage multiple water quality problems. We explore the following questions: (1) Can we classify elemental transport in watersheds as chemical cocktails using a new approach? (2) What is the role of climate and land use in enhancing the formation and transport of chemical cocktails in watersheds? To address these questions, we first analyze trends in concentrations of carbon, nutrients, metals, and salts in fresh waters over 100 years. Next, we explore how climate and land use enhance the probability of formation of chemical cocktails of carbon, nutrients, metals, and salts. Ultimately, we classify transport of chemical cocktails based on solubility, mobility, reactivity, and dominant phases: (1) sieved chemical cocktails (e.g., particulate forms of nutrients, metals and organic matter); (2) filtered chemical cocktails (e.g., dissolved organic matter and associated metal complexes); (3) chromatographic chemical cocktails (e.g., ions eluted from soil exchange sites); and (4) reactive chemical cocktails (e.g., limiting nutrients and redox sensitive elements). Typically, contaminants are regulated and managed one element at a time, even though combinations of elements interact to influence many water quality problems such as toxicity to life, eutrophication, infrastructure corrosion, and water treatment. A chemical cocktail approach significantly expands evaluations of water quality signatures and impacts beyond single elements to mixtures. High-frequency sensor data (pH, specific conductance, turbidity, etc.) can serve as proxies for chemical cocktails and improve real-time analyses of water quality violations, identify regulatory needs, and track water quality recovery following storms and extreme climate events. Ultimately, a watershed chemical cocktail approach is necessary for effectively co-managing groups of contaminants and provides a more holistic approach for studying, monitoring, and managing water quality in the Anthropocene.     

Transformation by integration in Podospora anserina. III. Replacement of a chromosome segment by a two-step process

Summary We have developed in Podospora anserina a two-step procedure for DNA sequence replacement through transformation which might be applicable to other filamentous fungi. Targeting of transforming DNAs to their homologous locus is achieved provided a cosmid vector is used. Southern blot analysis of genomic DNAs from a set of transformants is presented. The data confirm that cosmids integrate into the chromosome through mostly homologous recombination which leads to a duplicated sequence separated by the vector. This event was found to be unstable in crosses. We show that this instability is due to the frequent excision of the vector together with the selective marker and one copy of the duplication, either the resident or foreign sequence. The two sequences can be distinguished because they exhibit restriction fragment length polymorphism. Therefore, Podospora anserina treats duplications occurring through transformation in a way differing from that exhibited by Neurospora crassa and Ascobolus immersus.     

Properties of an Escherichia coli rhodanese

A rhodanese enzyme of less than 20,000 molecular weight has been purified from Escherichia coli. The enzyme is accessible to substrates upon addition of whole cells to standard assay mixtures. This rhodanese has a Stokes radius of 17 A which for a globular protein corresponds to a molecular weight close to 14,000. It undergoes autoxidation to a polymeric form which is probably an inert dimer. Enzyme inactivated by oxidation can be reactivated by millimolar concentrations of cysteine. Steady-state initial velocity measurements indicate that the enzyme catalyzes the transfer of sulfane sulfur by way of a double displacement mechanism with formation of a covalent enzyme-sulfur intermediate. The turnover number for the enzyme-catalyzed reaction, with thiosulfate as donor substrate and cyanide ion as the sulfur acceptor, is 260 s-1. This value corresponds to a catalytic efficiency 60% of that measured for a previously characterized bovine liver enzyme of more than twice the molecular weight. Furthermore, KmCN is 24 mM which is 2 orders of magnitude higher than the value observed previously for the bovine enzyme. Evidence from chemical inactivation studies implicates an essential sulfhydryl group in the enzyme activity. It is proposed that this group is the site of substrate-sulfur binding in the obligatory enzyme-sulfur intermediate. Furthermore, a cationic site important for binding of the donor thiosulfate is tentatively identified from anion inhibition studies. Tests of alternate acceptor substrates indicate that the physiological dithiol, dihydrolipoate, is a more efficient acceptor than cyanide ion for the enzyme-bound sulfur. Of possibly greater physiological significance, it has been found that the enzyme catalyzes the formation of iron-sulfur centers. Other work indicates the E. coli rhodanese is subject to catabolite repression and suggests a physiological role for the enzyme in aerobic energy metabolism.     

Prevalence of Antibody to Current Influenza Viruses and Effect of Vaccination on Antibody Response

The extent of antibody to the influenza virus A/Hong Kong/68 (H3N2) after four years of prevalence was investigated in Britain and in the U.S.A. The results indicated a high incidence in both populations. The prevalence of antibody to a variant A/England/42/72 (H3N2) which has been causing epidemics of influenza in the southern hemisphere during the middle months of 1972 was also investigated. The differences reflect the shift in antigenic content of this variant, and although the overall proportion of the sera with antibody at > 1/40 was 37%, some age groups had an incidence of only 20% or less with antibody at this level. A commercial inactivated A/Hong Kong/68 influenza vaccine was given to a group of volunteers in Britain to see how effective it might be in stimulating antibody to the variant A/England/42/72. The antibody responses were better than expected from earlier vaccine studies, and 63% of the vaccinees developed antibody to the A/England/42/72 to levels thought likely to be protective. This suggested that until a vaccine made with the variant A/England/42/72 becomes available the present A/Hong Kong/68 vaccine would be of use to protect those at special risk this winter.     

EFFECT OF COCAINE ON THE GROWTH OF LUPINUS ALBUS. A CONTRIBUTION TO THE COMPARATIVE PHARMACOLOGY OF ANIMAL AND PLANT PROTOPLASM

1. The effects of cocaine and its decomposition products were studied on the growth of the young roots of Lupinus albus. 2. The results obtained were compared with similar experiments on animal tissues. 3. It was found that, while cocaine is the most toxic of these compounds studied for animal tissues, it was of comparatively low toxicity in respect to its effect on the growth of roots. On the other hand, sodium benzoate, being practically non-toxic for animals, was the most toxic of the compounds studied for the plant roots.     

Analyse Durch ?thylurethan Bei Drosophila Induzierter Mutationen

Zusammenfassung Urethan hat bei Drosophila eine deutliche mutationsauslösende Wirkung. Die durch Urethan induzierten Mutationen waren entweder mit Chromosomenstückausfällen verbunden oder sie gehörten zur Klasse der sog. Punkt-Mutationen. Die vorwiegend zur letzteren Klasse gehörenden letalen und sichtbaren Mutationen traten in einem Zahlenverhältnis zueinander auf, das dem von anderen Autoren an bestrahltem oder unbehandeltem Material beobachteten Zahlenverhältnis entspricht. Ferner ergaben sich keine Anzeichen einer selektiven Wirkung des Urethans auf bestimmte Chromosomen-Loci. Die Loci, die nach Urethanbehandlung vorwiegend befallen wurden, sind die gleichen Loci, die eine erhöhte spontane Mutationsrate besitzen und zugleich eine erhöhte Empfindlichkeit gegenüber Röntgenstrahlen zeigen.Mit 5 Textabbildungen.     

Compartmental models for human iodine metabolism

Compartmental models for the various aspects of human iodine metabolism are reviewed, emphasizing the role of Mones Berman in the development of this field. The review first presents published submodels for the peripheral distribution of inorganic iodine, for the thyroidal iodide trapping function, and for the peripheral distribution and metabolism of the thyroid hormones. Approaches to improving understanding of the physiology of the thyroid gland itself through compartmental modeling techniques are then discussed in more detail. The three submodels described above are incorporated into overall models of thyroid iodine metabolism after being simplified to various degrees. Previously published models for thyroid-gland radioiodine metabolism, as well as current work in progress, are illustrated by attempting to fit the models to data from a single (previously unpublished) detailed prolonged ¹²⁵I feeding experiment in a normal human subject. Published thyroid gland models reviewed include: (1) the usual presentation, where the thyroid is a single homogeneous iodine compartment; (2) the model of DeGroot and colleagues, where thyroidal iodine is presented as MIT, DIT, T3, and T4, each with an active and linked storage compartment; (3) the thyroid model developed by Berman and colleagues, with less chemical subcategorization but incorporating a delay compartment, in which a fraction of the iodinated material in the thyroid is partially or completely inaccessible to secretion during the delay; and the later updating of Berman's model to include a thyroidal iodide recirculation pool. The experimental data presented fits most of these models for the first 1–2 weeks, but the fit could not be extended to longer data collection times. To overcome this shortcoming, a new thyroid gland model is introduced. It is based on the latest Berman model but describes thyroglobulin metabolism as incorporating multiple delay compartments of various time periods. The overall fit of the long term data is better with this model construct than with any of the published models. It appears that a complex thyroidal substructure, such as that of the multidelay model under development, will be required to account for overall thyroid iodine metabolism as isotopic equilibrium in man is approached.     

Calorimetric determination of the conformational transition of kappa carrageenan

This paper deals with measurements of the heat of the helix-coil transition by microcalorimetry for kappa carrageenans; data are given in the absence of gel in various solvents (H₂O, Me₂SO, and formamide) with two counterions (K⁺, Rb⁺). In water, the influence of gel formation on ΔH is pointed out and the influence of the time of ageing is demonstrated. The ΔH values measured in the absence of gel are interpreted in terms of the electrostatic model proposed by Manning; the agreement is quite good if a double helix is formed in water, but a monochain, ordered conformation is suggested for solutions in Me₂SO and formamide.