Changes in floodplain hydrology following serial damming of the Tocantins River in the eastern Amazon.

Riparian forests are ecotones that link aquatic and terrestrial habitats, providing ecosystem services including sediment control and nutrient regulation. Riparian forest function is intimately linked to river hydrology and floodplain dynamics, which can be severely altered by dams. The Tocantins River in the eastern Amazon has six mega-dams along its course. To understand the large-scale and cumulative impacts of multiple dams on the Tocantins floodplain, we quantified landscape-scale changes in floodplain extent, hydroperiod, and flood timing on a 145-km stretch of the river downstream of five dams. We used water level data from 1985 to 2019 to compare daily floodplain inundation dynamics before and after damming. We also developed models to examine the impacts of climate and land use change on hydrology of the Tocantins River. After installation of the first dam in 1998, an average of 82.3 km2 (63%) of the floodplain no longer flooded, overall average hydroperiod decreased by 15 days (11%), and flooding started an average of five days earlier. After all five dams were installed, 72% of the average pre-dam flooded area no longer flooded, average hydroperiod had decreased by 35%, and average inundation onset occurred 12 days later. These changes in floodplain hydrology appeared to be driven primarily by dam operations as we found no significant changes in precipitation over the study period. Increasing loss of natural vegetation in the watershed may play a role in changed hydrology but cannot explain the abrupt loss of floodplain extent after the first dam was installed. This is one of few studies to quantify dam-induced floodplain alteration at a landscape scale and to investigate impacts of multiple dams on a landscape. Our results indicate that the Tocantins River floodplain is undergoing drastic hydrologic alteration. The impacts of multiple dams are cumulative and non-linear, especially for hydroperiod and flood timing.

A 'dynamic' landscape of fear: prey responses to spatiotemporal variations in predation risk across the lunar cycle.

Ambiguous empirical support for 'landscapes of fear' in natural systems may stem from failure to consider dynamic temporal changes in predation risk. The lunar cycle dramatically alters night-time visibility, with low luminosity increasing hunting success of African lions. We used camera-trap data from Serengeti National Park to examine nocturnal anti-predator behaviours of four herbivore species. Interactions between predictable fluctuations in night-time luminosity and the underlying risk-resource landscape shaped herbivore distribution, herding propensity and the incidence of 'relaxed' behaviours. Buffalo responded least to temporal risk cues and minimised risk primarily through spatial redistribution. Gazelle and zebra made decisions based on current light levels and lunar phase, and wildebeest responded to lunar phase alone. These three species avoided areas where likelihood of encountering lions was high and changed their behaviours in risky areas to minimise predation threat. These patterns support the hypothesis that fear landscapes vary heterogeneously in both space and time.

The use of ultrasound to assess fetal growth in a guinea pig model of fetal growth restriction.

Fetal growth restriction (FGR) is a common and potentially severe pregnancy complication. Currently there is no treatment available. The guinea pig is an attractive model of human pregnancy as placentation is morphologically very similar between the species. Nutrient restriction of the dam creates growth-restricted fetuses while leaving an intact uteroplacental circulation, vital for evaluating novel therapies for FGR. Growth-restricted fetuses were generated by feeding Dunkin Hartley guinea pig dams 70% of ad libitum intake from four weeks before and throughout pregnancy. The effect of maternal nutrient restriction (MNR) on dams and fetuses was carefully monitored, and ultrasound measurements of pups collected. There was no difference in maternal weight at conception, however by five weeks post conception MNR dams were significantly lighter ( P < 0.05). MNR resulted in significantly smaller pup size from 0.6-0.66 gestation. Ultrasound is a powerful non-invasive tool for assessing the effect of therapeutic interventions on fetal growth, allowing longitudinal measurement of fetuses. This model and method yield data applicable to the human condition without the need for animal sacrifice and will be useful in the translation of therapies for FGR into the clinic.

Pre-packing of cost effective antibiotic cement beads for the treatment of traumatic osteomyelitis in the developing world - an in-vitro study based in Cambodia.

The developing world often lacks the resources to effectively treat the most serious injuries including osteomyelitis following open fractures or surgical fracture treatment. Antibiotic cement beads are a widely accepted method of delivering antibiotics locally to the infected area following trauma. This study is based in Cambodia, a low income country struggling to recover from a recent genocide. The study aims to test the effectiveness of locally made antibiotic beads and analyse their effectiveness after being gas sterilised, packaged and kept in storage Different antibiotic beads were manufactured locally using bone cement and tested against MRSA bacteria grown from a case of osteomyelitis. Each antibiotic was tested before and after a process of gas sterilisation as well as later being tested after storage in packaging up to 42 days. The gentamicin, vancomycin, amikacin and ceftriaxone beads all inhibited growth of the MRSA on the TSB and agar plates, both before and after gas sterilisation. All four antibiotics continued to show similar zones of inhibition after 42 days of storage. The results show significant promise to produce beads with locally obtainable ingredients in an austere environment and improve cost effectiveness by storing them in a sterilised condition.

Animal models of fetal growth restriction: Considerations for translational medicine.

Fetal growth restriction (FGR) is the failure of a fetus to reach its full genetic growth potential. It occurs in up to 8% of pregnancies, and after premature birth is the second leading cause of infant mortality and morbidity. There is no treatment currently available for FGR. Its primary cause, when not attributable to structural or genetic defects of the fetus, is 'placental insufficiency'. This broad definition covers the inability of the fetus to acquire sufficient nutrients and oxygen, and is influenced by a number of factors including altered maternal or fetal blood flow, reduced nutrient transport or changes in the placenta such as increased barrier thickness inhibiting nutrient transfer. For those researchers studying FGR and developing new therapies, choosing an animal model is a crucial consideration. It is vital to clearly frame the question being asked, as this will impact the factor influencing fetal nutrient delivery in the model, and will also affect the applicability of the results to the human condition. This review examines the range of in vivo models of FGR available for those engaged in translational research.

Semicircular canal morphogenesis in the zebrafish inner ear requires the function of gpr126 (lauscher), an adhesion class G protein-coupled receptor gene.

Morphogenesis of the semicircular canal ducts in the vertebrate inner ear is a dramatic example of epithelial remodelling in the embryo, and failure of normal canal development results in vestibular dysfunction. In zebrafish and Xenopus, semicircular canal ducts develop when projections of epithelium, driven by extracellular matrix production, push into the otic vesicle and fuse to form pillars. We show that in the zebrafish, extracellular matrix gene expression is high during projection outgrowth and then rapidly downregulated after fusion. Enzymatic disruption of hyaluronan in the projections leads to their collapse and a failure to form pillars: as a result, the ears swell. We have cloned a zebrafish mutant, lauscher (lau), identified by its swollen ear phenotype. The primary defect in the ear is abnormal projection outgrowth and a failure of fusion to form the semicircular canal pillars. Otic expression of extracellular matrix components is highly disrupted: several genes fail to become downregulated and remain expressed at abnormally high levels into late larval stages. The lau mutations disrupt gpr126, an adhesion class G protein-coupled receptor gene. Expression of gpr126 is similar to that of sox10, an ear and neural crest marker, and is partially dependent on sox10 activity. Fusion of canal projections and downregulation of otic versican expression in a hypomorphic lau allele can be restored by cAMP agonists. We propose that Gpr126 acts through a cAMP-mediated pathway to control the outgrowth and adhesion of canal projections in the zebrafish ear via the regulation of extracellular matrix gene expression.

The case for fencing remains intact.

Creel et al. argue against the conservation effectiveness of fencing based on a population measure that ignores the importance of top predators to ecosystem processes. Their statistical analyses consider, first, only a subset of fenced reserves and, second, an incomplete examination of 'costs per lion.' Our original conclusions remain unaltered.

Conserving large carnivores: dollars and fence.

Conservationists often advocate for landscape approaches to wildlife management while others argue for physical separation between protected species and human communities, but direct empirical comparisons of these alternatives are scarce. We relate African lion population densities and population trends to contrasting management practices across 42 sites in 11 countries. Lion populations in fenced reserves are significantly closer to their estimated carrying capacities than unfenced populations. Whereas fenced reserves can maintain lions at 80% of their potential densities on annual management budgets of $500 km(-2) , unfenced populations require budgets in excess of $2000 km(-2) to attain half their potential densities. Lions in fenced reserves are primarily limited by density dependence, but lions in unfenced reserves are highly sensitive to human population densities in surrounding communities, and unfenced populations are frequently subjected to density-independent factors. Nearly half the unfenced lion populations may decline to near extinction over the next 20-40 years.

Arc/Arg3.1 mRNA expression reveals a subcellular trace of prior sound exposure in adult primary auditory cortex.

Acquiring the behavioral significance of sound has repeatedly been shown to correlate with long term changes in response properties of neurons in the adult primary auditory cortex. However, the molecular and cellular basis for such changes is still poorly understood. To address this, we have begun examining the auditory cortical expression of an activity-dependent effector immediate early gene (IEG) with documented roles in synaptic plasticity and memory consolidation in the hippocampus: Arc/Arg3.1. For initial characterization, we applied a repeated 10 min (24 h separation) sound exposure paradigm to determine the strength and consistency of sound-evoked Arc/Arg3.1 mRNA expression in the absence of explicit behavioral contingencies for the sound. We used 3D surface reconstruction methods in conjunction with fluorescent in situ hybridization (FISH) to assess the layer-specific subcellular compartmental expression of Arc/Arg3.1 mRNA. We unexpectedly found that both the intranuclear and cytoplasmic patterns of expression depended on the prior history of sound stimulation. Specifically, the percentage of neurons with expression only in the cytoplasm increased for repeated versus singular sound exposure, while intranuclear expression decreased. In contrast, the total cellular expression did not differ, consistent with prior IEG studies of primary auditory cortex. Our results were specific for cortical layers 3-6, as there was virtually no sound driven Arc/Arg3.1 mRNA in layers 1-2 immediately after stimulation. Our results are consistent with the kinetics and/or detectability of cortical subcellular Arc/Arg3.1 mRNA expression being altered by the initial exposure to the sound, suggesting exposure-induced modifications in the cytoplasmic Arc/Arg3.1 mRNA pool.

Bidirectional promoter interference between two widely used internal heterologous promoters in a late-generation lentiviral construct.

Gene transfer vectors encoding two or more genes are potentially powerful research tools and are poised to play an increasingly important role in gene therapy applications. Common strategies employed to express more than one transgene per vector include the use of multiple promoters, internal ribosome entry site (IRES) elements, splicing signals and fusion proteins. Of these, the IRES elements and multiple promoters have been most widely used. The use of multiple promoters, however, may be compromised by interference between promoters, promoter silencing and vector rearrangements or deletions. In this study, we demonstrate promoter interference between two internal heterologous promoters in the context of a late-generation lentiviral vector. The interference, involving the human cytomegalovirus-immediate-early promoter and human elongation-factor-1alpha promoter, occurred bidirectionally with both promoters markedly impairing expression of the adjacent transcription unit. The data presented not only highlight the potential for interference between these widely-used promoters, but also the value of a sequential approach to vector construction that allows such effects to be recognized.

Leaf Ests from Stevia rebaudiana: a resource for gene discovery in diterpene synthesis.

Expressed sequence tags (ESTs) are providing a new approach to gene discovery in plant secondary metabolism. Stevia rebaudiana Bert. leaves produce high concentrations of diterpene steviol glycosides and should be a rich source of transcripts involved in diterpene synthesis. In order to create a resource for gene discovery and increase our understanding of steviol glycoside biosynthesis, we sequenced 5,548 ESTs from a S. rebaudiana leaf cDNA library. The EST collection was fully annotated based on database search results. ESTs involved in diterpene synthesis were identified using published sequences as electronic probes, by keyword searches of search results, and by differential representation. A significant portion of the ESTs were specific for standard leaf metabolic pathways; energy and primary metabolism represented 17.6% and 13.1% of total transcripts respectively. Diterpene metabolism in S. rebaudiana represented 1.1% of total transcripts. This study identified candidate genes for 70% of the known steps in the steviol glycoside pathway. One candidate, kaurene oxidase, was the 8th most abundant EST in the collection. Identification of many candidate genes specific to the I -deoxyxylulose 5-phosphate pathway suggests that the primary source of isopentenyl diphosphate, a precursor of geranylgeranyl diphosphate, is via the non-mevalonic acid pathway. The use of ESTs has greatly facilitated the identification of candidate genes and increased our understanding of diterpene metabolism.

Analyzing and correcting spectrometer temperature sensitivity.

Stability and reproducibility of the spectrometer are fundamental to the success of many modern NMR experiments. Variation in room temperature is a particularly important source of instability, in part because it can cause coherent artifacts in NMR spectra. Small changes in room temperature lead to corresponding changes in the phases, amplitudes, and frequencies of NMR signals. These can lead in turn to apparently random spectral artifacts such as t(1)-noise in two-dimensional (2D) NMR and to the incomplete cancellation of signals in difference spectra, but also, importantly, to F(1) satellite signals in 2D spectra. These "parallel diagonals" arise from the use of air conditioning, which typically forces room temperature to oscillate within a fixed band. Work to identify, quantify, and suppress sources of temperature sensitivity in a modern 300-MHz spectrometer has led to a greater than 10-fold improvement in the signal-to-artifact ratio.

Description of the analysis of a wide range of volatile organic compounds in whole air samples collected during PEM-tropics A and B.

A large number of hydrocarbons, halocarbons, and organic nitrates were quantified in whole air samples acquired for the NASA-sponsored GTE missions PEM-Tropics A and B. The samples were collected in electro-polished stainless steel canisters from two aircraft while flying over the Pacific Basin. Two nominally identical multicolumn multidetector gas chromatographic analytical systems were employed. Whole air samples were also used as working and calibrated standards and were collected specifically for this purpose. This paper describes the analytical procedure employed during PEM-Tropics B. Minor differences in the PEM-Tropics A system will also be discussed. More than 3,900 samples were analyzed for 34 gases during PEM-Tropics A, over 4,500 samples were analyzed for 58 gases during PEM-Tropics B. An overview is presented of the collection, analysis, and quantification of whole air samples during the PEM-Tropics missions, along with an analysis of the analytical precision achieved during these missions.

The Key Extended Entry Program (KEEP): a methadone treatment program for opiate-dependent inmates.

The Key Extended Entry Program (KEEP) is the only known methadone treatment program for incarcerated opiate-dependent inmates in the United States. Initiated in 1987, KEEP performs approximately 18,000 detoxifications and 4,000 admissions for methadone treatment per year. Of those methadone treatment patients discharged to the community, mostly to outpatient KEEP programs, 74-80% report to their designated program. Recidivism rates reveal that 79% of KEEP patients were incarcerated again only once or twice during a recent 11-year period. Finally, KEEP data point to the importance of dedicating slots in the community for released inmates and maintaining them on sufficient blocking doses to eliminate the craving for heroin. About 6% of KEEP patients, some with mental illness have a high incidence of recidivism.

Cutting edge: restoration of the ability to generate CTL in mice immune to adenovirus by delivery of virus in a collagen-based matrix.

Viruses are commonly used for the delivery of genes coding for tumor-associated Ags to elicit tumor-specific immune responses. The success of viral vectors has been limited in preclinical and clinical trials in part because of antiviral immunity. We investigated the ability of a collagen-based matrix (Gelfoam; Pharmacia and Upjohn, Kalamazoo, MI) to improve CTL activation by recombinant adenovirus. The data show that coinjection of Gelfoam with type 5 adenovirus recombinant for prostate-specific Ag (Ad5-PSA) enhanced CTL activation. Ad5-PSA priming in Gelfoam also abrogated the inhibitory effects of adenoviral immunity on CTL activation in mice naive to PSA but immune to adenovirus. Finally, Gelfoam enhanced immunization in a self-Ag model using type 5 adenovirus recombinant for membrane-bound OVA (Ad5-mOVA) in rat insulin promoter (RIP)-mOVA-transgenic mice. Thus, Gelfoam enhances CTL activation by recombinant viral vectors in a setting where preformed Ab to the virus is present and also in a tolerant self-Ag model.

Motivational interviewing and treatment adherence among psychiatric and dually diagnosed patients.

The effect of motivational interviewing on outpatient treatment adherence among psychiatric and dually diagnosed inpatients was investigated. Subjects were 121 psychiatric inpatients, 93 (77%) of whom had concomitant substance abuse/dependence disorders, who were randomly assigned to: a) standard treatment (ST), including pharmacotherapy, individual and group psychotherapy, activities therapy, milieu treatment, and discharge planning; or b) ST plus motivational interviewing (ST+MI), which involved 15 minutes of feedback on the results of a motivational assessment early in the hospitalization, and a 1-hour motivational interview just before discharge. Interviewers utilized motivational techniques described in Miller and Rollnick (1991), such as reflective listening, discussion of treatment obstacles, and elicitation of motivational statements. Results indicated that the proportion of patients who attended their first outpatient appointment was significantly higher for the ST+MI group (47%) than for the ST group (21%; chi2 = 8.87, df = 1, p<.01) overall, and for dually diagnosed patients (42% for ST+MI vs. 16% for ST only; chi2 = 7.68, df = 1, p<.01). Therefore, brief motivational interventions show promise in improving outpatient treatment adherence among psychiatric and dually diagnosed patients.

Randomized acquisition for the suppression of systematic F1 artifacts in two-dimensional NMR spectroscopy.

2D spectra, particularly for homonuclear correlation, can show a variety of artifactual signals in the F1 domain. Common sources include carry-over of signal modulation from one transient to the next ("rapid pulsing artifacts") and systematic variations in room temperature ("parallel diagonals"). In both cases there is one very simple expedient which can greatly reduce the impact of these sources of error. Multidimensional data sets are almost invariably recorded by simply incrementing or decrementing evolution periods, largely for reasons of convenience and historical precedent. If instead the sampling of the evolution periods is carried out in random order, the perturbations responsible for the sharp F1 signals in the conventional experiment manifest themselves as t1 noise. Since the randomized acquisition redistributes coherent artifactual signals randomly in F1, the maximum artifactual signal is substantially reduced in the randomized experiment and no longer appears in the form of misleading distinct peaks.