Biogenic Manganese Oxides Facilitate Iodide Oxidation at pH ≤ 5

Radioactive ¹²⁹I, a byproduct of nuclear power generation, can pose risks to human health if released into the environment, where its mobility is highly dependent on speciation. Based on thermodynamic principles, ¹²⁹I should exist primarily as iodide (I^?) in most terrestrial environments; however, organo-¹²⁹I and ¹²⁹iodate are also commonly detected in contaminated soils and groundwater. To investigate the capability of biogenic manganese oxides to influence iodide speciation, 17 manganese-oxidizing bacterial strains, representing six genera, were isolated from soils of the Savannah River Site, South Carolina. The isolates produced between 2.6 and 67.1 nmole Mn oxides (ml^?1 media after 25 days, pH 6.5). Results from inhibitor assays targeting extracellular enzymes and reactive oxygen species indicated that both play a role in microbe-induced Mn(II) oxidation among the strains examined. Iodide oxidation was not observed in cultures of the most active Mn-oxidizing bacteria, Chryseobacterium sp. strain SRS1 and Chromobacterium sp. strain SRS8, or the fungus, Acremonium strictum strain KR21–2. While substantial amounts of Mn(III/IV) oxides were only generated in cultures at ≥pH 6, iodide oxidation was only observed in the presence of Mn(III/IV) oxides when the pH was ≤5. Iodide oxidation was promoted to a greater extent by synthetic Mn(IV)O₂ than biogenic Mn(III/IV) oxides under these low pH conditions (≤pH 5). These results indicate that the influence of biogenic manganese oxides on iodide oxidation and immobilization is primarily limited to low pH environments.     

Recovery of plankton from hurricane impacts in a large shallow lake

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Long-term trends in seasonal plankton dynamics in Lake Mead (Nevada-Arizona,USA) and implications for climate change

Where biodiversity conservation and environmental preservation are significant concerns, rapid assessment and monitoring of the colonization and spread of non-native species are essential for timely decision-making and response. We developed and evaluated the adequacy of a rapid assessment protocol (RAP) for detecting non-native fish species in 74 Eastern Brazilian lakes. The RAP consists of a single field day employing two surveyors to conduct interviews with local sport fishers, visual surveys of fish, angling with lures, and gillnetting. We compared our results with those from separate, intense, large sampling effort (LSE) field surveys. Despite requiring less than 1/100th of the field effort, the RAP was able to detect the presence of most non-native fish species that were reported in the same lakes by LSE surveys. Information from local sport fishers was invaluable, particularly for detecting species that were in low abundance, but was not available for lakes within a forest preserve area. Non-native introductions commonly lead to rapid and widespread invasion and adverse effects on native biota. Our results strongly suggest that the RAP could function as a cost-effective tool for efficiently assessing the presence of non-native fishes in lakes and monitoring their colonization and spread over large geographic areas.     

Exposure to Pre- and Perinatal Risk Factors Partially Explains Mean Differences in Self-Regulation between Races

Objectives

To examine whether differential exposure to pre- and perinatal risk factors explained differences in levels of self-regulation between children of different races (White, Black, Hispanic, Asian, and Other).

Methods

Multiple regression models based on data from the Early Childhood Longitudinal Study, Birth Cohort (n ≈ 9,850) were used to analyze the impact of pre- and perinatal risk factors on the development of self-regulation at age 2 years.

Results

Racial differences in levels of self-regulation were observed. Racial differences were also observed for 9 of the 12 pre-/perinatal risk factors. Multiple regression analyses revealed that a portion of the racial differences in self-regulation was explained by differential exposure to several of the pre-/perinatal risk factors. Specifically, maternal age at childbirth, gestational timing, and the family’s socioeconomic status were significantly related to the child’s level of self-regulation. These factors accounted for a statistically significant portion of the racial differences observed in self-regulation.

Conclusions

The findings indicate racial differences in self-regulation may be, at least partially, explained by racial differences in exposure to pre- and perinatal risk factors.     

Estimation of the Number of Classes in a Population

The problem of estimating M, the number of classes in a population, is formulated as an occupancy problem in which N items are drawn from M urns. Under the assumption of a uniform distribution for the number of classes in the population, the sufficient statistic for M, which is the number of distinct classes observed, does not depend upon the number of repetitions in the sample. Point and interval estimates of M are developed using maximum likelihood and the method of moments. Both techniques give rise to the same basic equation which requires a simple iterative solution. These same techniques are used in the more general situation in which the classes can be further subdivided according to type.     

Taxonomic notes on the afrotropical genera Hapalogenius Hagedorn, Hylesinopsis Eggers, and Rhopalopselion Hagedorn (Coleoptera, Curculionidae, Scolytinae)

Taxonomic confusion among the afrotropical scolytine genera Hapalogenius Hagedorn, Hylesinopsis Eggers and Rhopalopselion Hagedorn, and their synonyms is discussed with especial reference to the catalogues of Wood and Bright (1992), and Alonso-Zarazaga and Lyal (2009). A key is given to separate the three genera recognised, and the species considered to be included in each genus are listed. Hylesinopsis is resurrected from synonymy with Hapalogenius, and shown not to be closely related to it. Chilodendron Schedl is considered to be a synonym of Hylesinopsis and not of Xylechinus Chapuis. The following new synonymy is proposed at specific level: Hapalogenius africanus (Eggers) (= Hapalogenius lesnei Eggers, = Metahylesinus brincki Schedl); Hapalogenius fuscipennis (Chapuis) (= Hapalogenius bimaculatus Eggers); Hapalogenius oblongus (Eggers) (= Metahylesinus striatus Schedl); Hylesinopsis fasciata (Hagedorn) (= Kissophagus punctatus Eggers); Phrixosoma niger Eggers (= Hapalogenius niger Schedl). The following species are returned to Hylesinopsis from Hapalogenius to which they were transferred by Alonso-Zarazaga and Lyal (2009): Hylesinopsis alluaudi (Lepesme), Hylesinopsis angolensis (Schedl), Hylesinopsis arabiae (Schedl), Hylesinopsis atra (Nunberg), Hylesinopsis confusa (Eggers), Hylesinopsis decellei (Nunberg), Hylesinopsis dubia Eggers, Hylesinopsis emarginata (Nunberg), Hylesinopsis fasciata (Hagedorn), Hylesinopsis ficus (Schedl), Hylesinopsis granulata (Lepesme), Hylesinopsis hirsuta (Schedl), Hylesinopsis joveri (Schedl), Hylesinopsis pauliani (Lepesme), Hylesinopsis punctata (Eggers), Hylesinopsis saudiarabiae (Schedl). The following new combination is given: Hylesinopsis leprosula (Browne) from Cryphalus Erichson. New distributional records are given for some species.     

Hyperpolarized 129Xe MR Imaging of Alveolar Gas Uptake in Humans

Background

One of the central physiological functions of the lungs is to transfer inhaled gases from the alveoli to pulmonary capillary blood. However, current measures of alveolar gas uptake provide only global information and thus lack the sensitivity and specificity needed to account for regional variations in gas exchange.

Methods and Principal Findings

Here we exploit the solubility, high magnetic resonance (MR) signal intensity, and large chemical shift of hyperpolarized (HP) ¹²⁹Xe to probe the regional uptake of alveolar gases by directly imaging HP ¹²⁹Xe dissolved in the gas exchange tissues and pulmonary capillary blood of human subjects. The resulting single breath-hold, three-dimensional MR images are optimized using millisecond repetition times and high flip angle radio-frequency pulses, because the dissolved HP ¹²⁹Xe magnetization is rapidly replenished by diffusive exchange with alveolar ¹²⁹Xe. The dissolved HP ¹²⁹Xe MR images display significant, directional heterogeneity, with increased signal intensity observed from the gravity-dependent portions of the lungs.

Conclusions

The features observed in dissolved-phase ¹²⁹Xe MR images are consistent with gravity-dependent lung deformation, which produces increased ventilation, reduced alveolar size (i.e., higher surface-to-volume ratios), higher tissue densities, and increased perfusion in the dependent portions of the lungs. Thus, these results suggest that dissolved HP ¹²⁹Xe imaging reports on pulmonary function at a fundamental level.