Hydroclimatology, modes of climatic variability and stream flow, lake and groundwater level variability

Hydroclimatology is an expansive discipline largely concerned with understanding the workings of the hydrological cycle in a climate context. Acknowledging this, and given the burgeoning interest in the relation between climate and water in the context of working towards an improved understanding of the impacts of climatic variability on water resources, this progress report turns its attention to the connection between large-scale modes of climatic variability and hydrological variability in streams, lakes and groundwater. A survey of the recent literature finds that a plethora of teleconnection indices have been employed in the analysis of hydrological variability. Indices representing modes of climatic variability such as El Niño Southern Oscillation, the North Atlantic Oscillation, the Pacific North America pattern, the Pacific Decadal Oscillation and Atlantic Meridional Oscillation dominate the literature on climatic and hydrological variability. While examples of discernible signals of modes of climatic variability in stream flow and lake and groundwater level time series abound, the associations between periodic to quasi-period oscillations in atmospheric/ocean circulation patterns and variability within the terrestrial branch of the hydrological are far from simple, being both monotonic (linear and non-linear) and non-monotonic and also conditional on period of analysis, season and geographic region. While there has been considerable progress over the last five years in revealing the climate mechanisms that underlie the links between climatic and hydrological variability, a bothering feature of the literature is how climatic and hydrological variability is often viewed through a purely statistical lens with little attention given to diagnosing the relationship in terms of atmosphere and ocean physics and dynamics. Consequently, significant progress remains to be made in obtaining a satisfactory hydroclimatological understanding of stream flow, lake and groundwater variability, especially if hydroclimatological knowledge is to be fully integrated into water resource management and planning

A baseline appraisal of water-dependant ecosystem services, the roles they play within desakota livelihood systems and their potential sensitivity to climate change

This report forms part of a larger research programme on 'Reinterpreting the Urban-Rural Continuum', which conceptualises and investigates current knowledge and research gaps concerning 'the role that ecosystems services play in the livelihoods of the poor in regions undergoing rapid change'. The report aims to conduct a baseline appraisal of water-dependant ecosystem services, the roles they play within desakota livelihood systems and their potential sensitivity to climate change. The appraisal is conducted at three spatial scales: global, regional (four consortia areas), and meso scale (case studies within the four regions). At all three scales of analysis water resources form the interweaving theme because water provides a vital provisioning service for people, supports all other ecosystem processes and because water resources are forecast to be severely affected under climate change scenarios. This report, combined with an Endnote library of over 1100 scientific papers, provides an annotated bibliography of water-dependant ecosystem services, the roles they play within desakota livelihood systems and their potential sensitivity to climate change. After an introductory, section, Section 2 of the report defines water-related ecosystem services and how these are affected by human activities. Current knowledge and research gaps are then explored in relation to global scale climate and related hydrological changes (e.g. floods, droughts, flow regimes) (section 3). The report then discusses the impacts of climate changes on the ESPA regions, emphasising potential responses of biomes to the combined effects of climate change and human activities (particularly land use and management), and how these effects coupled with water store and flow regime manipulation by humans may affect the functioning of catchments and their ecosystem services (section 4). Finally, at the meso-scale, case studies are presented from within the ESPA regions to illustrate the close coupling of human activities and catchment performance in the context of environmental change (section 5). At the end of each section, research needs are identified and justified. These research needs are then amalgamated in section 6

Translesion Synthesis Polymerases in the Prevention and Promotion of Carcinogenesis

A critical step in the transformation of cells to the malignant state of cancer is the induction of mutations in the DNA of cells damaged by genotoxic agents. Translesion DNA synthesis (TLS) is the process by which cells copy DNA containing unrepaired damage that blocks progression of the replication fork. The DNA polymerases that catalyze TLS in mammals have been the topic of intense investigation over the last decade. DNA polymerase η (Pol η) is best understood and is active in error-free bypass of UV-induced DNA damage. The other TLS polymerases (Pol ι, Pol κ, REV1, and Pol ζ) have been studied extensively in vitro, but their in vivo role is only now being investigated using knockout mouse models of carcinogenesis. This paper will focus on the studies of mice and humans with altered expression of TLS polymerases and the effects on cancer induced by environmental agents

Snow avalanche phenomena on the eastern side of the Craigieburn Range, New Zealand

The role of terrain, meteorological and snowpack factors contributing to snow avalanche occurrence were investigated on the eastern side of the Craigieburn Range. Data on which this analysis was based were collected in the winters of 1979 to 1981. The majority of slab avalanching occurred on lee slopes with large bowl shaped starting zones of 33 to 36 degrees inclination while frequency of avalanching was related to path size factors. Theoretical models adequately predicted avalanche runout distance on the majority of paths. However, these models proved only partially satisfactory for valley side paths with steep vegetated runout zones. An empirical model developed for predicting avalanche runout based on measured terrain characteristics performed well. Threshold values for avalanching were established for precipitation, temperature and wind related variables. A discriminant analysis model for distinguishing dry, wet and non-avalanche days was established using maximum six hour precipitation intensity, variation in wind direction, total global radiation and two hour mean temperature. An independent test of this model produced acceptable results. Synoptic weather types dominated by vorticity advection processes and characterised by cyclonic circulation were the most frequent storm types producing snowfall in the study period. However, systems typified by a mixture of warm advection and vorticity advection processes with well developed troughs, associated fronts, high rates of thermal advection and combinations of stability and instability produced the greatest amounts of snow and snow avalanching. A three phase snowpack development model was proposed and considered in relation to snow avalanching. The magnitude of positive and negative snowpack temperature gradients exceed those generally required for recrystallisation processes. Temperature gradient snow crystals were observed at the base and mid to upper parts of the snowpack. Fracture line profile, shovel test and shear frame analyses revealed that partially metamorphosed new snow undergoing equitemperature metamorphism, especially clusters of rimed needles, and snow in the early stages of temperature gradient metamorphism, were characteristically weak in shear. Three categories of potential sliding layers for avalanche release are presented. Consideration of snowpack and meteorological information indicates that the Craigieburn Range snow avalanche climate approximates most closely that of one transitional between a maritime and continental situation

Snow avalanche phenomena on the eastern side of the Craigieburn Range, New Zealand

The role of terrain, meteorological and snowpack factors contributing to snow avalanche occurrence were investigated on the eastern side of the Craigieburn Range. Data on which this analysis was based were collected in the winters of 1979 to 1981. The majority of slab avalanching occurred on lee slopes with large bowl shaped starting zones of 33 to 36 degrees inclination while frequency of avalanching was related to path size factors. Theoretical models adequately predicted avalanche runout distance on the majority of paths. However, these models proved only partially satisfactory for valley side paths with steep vegetated runout zones. An empirical model developed for predicting avalanche runout based on measured terrain characteristics performed well. Threshold values for avalanching were established for precipitation, temperature and wind related variables. A discriminant analysis model for distinguishing dry, wet and non-avalanche days was established using maximum six hour precipitation intensity, variation in wind direction, total global radiation and two hour mean temperature. An independent test of this model produced acceptable results. Synoptic weather types dominated by vorticity advection processes and characterised by cyclonic circulation were the most frequent storm types producing snowfall in the study period. However, systems typified by a mixture of warm advection and vorticity advection processes with well developed troughs, associated fronts, high rates of thermal advection and combinations of stability and instability produced the greatest amounts of snow and snow avalanching. A three phase snowpack development model was proposed and considered in relation to snow avalanching. The magnitude of positive and negative snowpack temperature gradients exceed those generally required for recrystallisation processes. Temperature gradient snow crystals were observed at the base and mid to upper parts of the snowpack. Fracture line profile, shovel test and shear frame analyses revealed that partially metamorphosed new snow undergoing equitemperature metamorphism, especially clusters of rimed needles, and snow in the early stages of temperature gradient metamorphism, were characteristically weak in shear. Three categories of potential sliding layers for avalanche release are presented. Consideration of snowpack and meteorological information indicates that the Craigieburn Range snow avalanche climate approximates most closely that of one transitional between a maritime and continental situation

Projected impacts on heat-related mortality from changes in the mean and variability of temperature with climate change

The aim of this paper is to demonstrate the importance of changing temperature variability with climate change in assessments of future heat-related mortality. Previous studies have only considered changes in the mean temperature. Here we present estimates of heat-related mortality resulting from climate change for six cities: Boston, Budapest, Dallas, Lisbon, London and Sydney. They are based on climate change scenarios for the 2080s (2070-2099) and the temperature-mortality (t-m) models constructed and validated in Gosling et al. (2007). We propose a novel methodology for assessing the impacts of climate change on heat-related mortality that considers both changes in the mean and variability of the temperature distribution

The schizophrenia susceptibility gene neuregulin 1 modulates tolerance to the effects of canabinoids

Cannabis increases the risk of schizophrenia in genetically vulnerable individuals. In this study we aim to show that the schizophrenia susceptibility gene neuregulin 1 (Nrg1) modulates the development of tolerance to cannabinoids in mice. Nrg1 heterozygous (HET) and wild-type (WT) mice were treated daily for 15 d with the synthetic analogue of D9-tetrahydrocannabinol, CP55,940 (0.4 mg/kg). We measured the impact of this exposure on locomotor activity, anxiety, prepulse inhibition (PPI), body temperature and FosB/DFosB immunohistochemistry. Tolerance to CP55,940-induced hypothermia and locomotor suppression developed more rapidly in Nrg1 HET mice than WT mice. Conversely in the light-dark test, while tolerance to the anxiogenic effect of CP55,940 developed in WT mice over days of testing, Nrg1 hypomorphs maintained marked anxiety even after 15 d of treatment. Repeated cannabinoid exposure selectively increased FosB/DFosB expression in the lateral septum, ventral part (LSV) of Nrg1 HET but not WT mice. On day 1 of exposure opposite effects of CP55,940 treatment were observed on PPI, i.e. it was facilitated in Nrg1 hypomorphs and impaired in WT mice, despite the drug significantly impairing the acoustic startle reflex equally in both genotypes. These effects of CP55,940 on PPI were not maintained as both genotypes became tolerant to cannabinoid action with repeated exposure. Our results highlight that Nrg1 modulates the development of cannabinoid tolerance dependent on the parameter being measured. Furthermore, these data reinforce the notion that the VLS is an important brain region involved in Nrg1–cannabinoid interactions

Inhibition of DNA replication fork progression and mutagenic potential of 1, N6-ethenoadenine and 8-oxoguanine in human cell extracts

Comparative mutagenesis of 1,N6-ethenoadenine (εA) and 8-oxoguanine (8-oxoG), two endogenous DNA lesions that are also formed by exogenous DNA damaging agents, have been evaluated in HeLa and xeroderma pigmentosum variant (XPV) cell extracts. Two-dimensional gel electrophoresis of the duplex M13mp2SV vector containing these lesions established that there was significant inhibition of replication fork movement past εA, whereas 8-oxoG caused only minor stalling of fork progression. In extracts of HeLa cells, εA was weakly mutagenic inducing all three base substitutions in approximately equal frequency, whereas 8-oxoG was 10-fold more mutagenic inducing primarily G→T transversions. These data suggest that 8-oxoG is a miscoding lesion that presents a minimal, if any, block to DNA replication in human cells. We hypothesized that bypass of εA proceeded principally by an error-free mechanism in which the undamaged strand was used as a template, since this lesion strongly blocked fork progression. To examine this, we determined the sequence of replication products derived from templates in which a G was placed across from the εA. Consistent with our hypothesis, 93% of the progeny were derived from replication of the undamaged strand. When translesion synthesis occurred, εA→T mutations increased 3-fold in products derived from the mismatched εA: G construct compared with those derived from the εA: T construct. More efficient repair of εA in the εA: T construct may have been responsible for lower mutation frequency. Primer extension studies with purified pol η have shown that this polymerase is highly error-prone when bypassing εA. To examine if pol η is the primary mutagenic translesion polymerase in human cells, we determined the lesion bypass characteristics of extracts derived from XPV cells, which lack this polymerase. The εA: T construct induced εA→G and εA→C mutant frequencies that were approximately the same as those observed using the HeLa extracts. However, εA→T events were increased 5-fold relative to HeLa extracts. These data support a model in which pol η-mediated translesion synthesis past this adduct is error-free in the context of semiconservative replication in the presence of fidelity factors such as PCNA