Allelopathic Effects of <Emphasis Type="Italic">Myriophyllum aquaticum</Emphasis> on Two Cyanobacteria of <Emphasis Type="Italic">Anabaena flos-aquae</Emphasis> and <Emphasis Type="Italic">Microcystis aeruginosa</Emphasis>

Allelopathy has been proposed as a sustainable means to control undesired algal growth and to reduce blooms threatening freshwater systems worldwide. In this study, the allelopathic effects of Myriophyllum aquaticum and its exudate on two typical bloom-forming cyanobacteria, Microcystis aeruginosa and Anabaena flos-aquae, were investigated under laboratory conditions. The growth of the cyanobacteria was strongly inhibited by live M. aquaticum while the primary addition of M. Aquaticum exudates had a significant inhibitory effect on the growth of M. aeruginosa but not A. flos-aquae. The results suggested that the persistent release of allelochemicals from live M. aquaticum was needed to effectively constrain the growth of A. flos-aquae. Analysis of cyanobacterial physiological indexes indicated that M. aquaticum produced an inhibitory effect on SOD enzyme activity of A. flos-aquae, while it affected membrane lipid peroxidation in M. aeruginosa. The results show the potential of M. aquaticum to mitigate cyanobacterial blooms in coexistence systems.     

Copper-Based Aquatic Algaecide Adsorption and Accumulation Kinetics: Influence of Exposure Concentration and Duration for Controlling the Cyanobacterium <Emphasis Type="Italic">Lyngbya wollei</Emphasis>

Filamentous mat-forming cyanobacteria are increasingly impairing uses of freshwater resources. To effectively manage, a better understanding of control measures is needed. Copper (Cu)-based algaecide formulations are often applied to reactively control nuisance cyanobacterial blooms. This laboratory research assessed typical field exposure scenarios for the ability of Cu to partition to, and accumulate in Lyngbya wollei. Exposure factors (Cu concentration?×?duration) of 4, 8, 16, 24, 32 h were tested across three aqueous Cu concentrations (1, 2, 4 ppm). Results indicated that internally accumulated copper correlated with control of L. wollei, independent of adsorbed copper. L. wollei control was determined by filament viability and chlorophyll a concentrations. Similar exposure factors elicited similar internalized copper levels and consequent responses of L. wollei. Ultimately, a “concentration-exposure-time” (CET) model was created to assist water resource managers in selecting an appropriate treatment regime for a specific in-water infestation. By assessing the exposure concentration and duration required to achieve the internal threshold of copper (i.e., critical burden) that elicits control, water management objectives can be achieved while simultaneously decreasing the environmental loading of copper and potential for non-target species risks.     

The Effects of an Herbicide and Antibiotic Mixture on Aquatic Primary Producers and Grazers

Widespread use of agrochemicals increases their likelihood of entering aquatic systems in mixture. Despite different modes of action, atrazine (herbicide) and tetracycline (antibiotic) adversely affect non-target photosynthetic organisms individually, but the effects of simultaneous exposure to both contaminants are untested. We created microcosms containing microalgae (Chlorella sp.), floating macrophytes (Lemna minor), and a zooplankton grazer (Daphnia magna). Microcosms were exposed to environmentally relevant concentrations of atrazine and tetracycline, alone and together, for 10 days. Atrazine decreased Chlorella sp. abundance, but not enough to reduce food availability to D. magna whose reproduction and mortality were unaffected. In contrast, tetracycline and atrazine appeared to have additive effects on L. minor abundance and growth inhibition. These additive adverse effects suggest increased potential for L. minor population decline over the long term, and potential for altered species interactions in aquatic systems receiving agricultural runoff.     

Centers for Oceans and Human Health: a unified approach to the challenge of harmful algal blooms

Background

Harmful algal blooms (HABs) are one focus of the national research initiatives on Oceans and Human Health (OHH) at NIEHS, NOAA and NSF. All of the OHH Centers, from the east coast to Hawaii, include one or more research projects devoted to studying HAB problems and their relationship to human health. The research shares common goals for understanding, monitoring and predicting HAB events to protect and improve human health: understanding the basic biology of the organisms; identifying how chemistry, hydrography and genetic diversity influence blooms; developing analytical methods and sensors for cells and toxins; understanding health effects of toxin exposure; and developing conceptual, empirical and numerical models of bloom dynamics.

Results

In the past several years, there has been significant progress toward all of the common goals. Several studies have elucidated the effects of environmental conditions and genetic heterogeneity on bloom dynamics. New methods have been developed or implemented for the detection of HAB cells and toxins, including genetic assays for Pseudo-nitzschia and Microcystis, and a biosensor for domoic acid. There have been advances in predictive models of blooms, most notably for the toxic dinoflagellates Alexandrium and Karenia. Other work is focused on the future, studying the ways in which climate change may affect HAB incidence, and assessing the threat from emerging HABs and toxins, such as the cyanobacterial neurotoxin β-N-methylamino-L-alanine.

Conclusion

Along the way, many challenges have been encountered that are common to the OHH Centers and also echo those of the wider HAB community. Long-term field data and basic biological information are needed to develop accurate models. Sensor development is hindered by the lack of simple and rapid assays for algal cells and especially toxins. It is also critical to adequately understand the human health effects of HAB toxins. Currently, we understand best the effects of acute toxicity, but almost nothing is known about the effects of chronic, subacute toxin exposure. The OHH initiatives have brought scientists together to work collectively on HAB issues, within and across regions. The successes that have been achieved highlight the value of collaboration and cooperation across disciplines, if we are to continue to advance our understanding of HABs and their relationship to human health.

     

Bioaugmentation-Assisted Phytostabilisation of Abandoned Mine Sites in South West Sardinia

Bioaugmentation-assisted phytoremediation implies the administration of selected plant growth promoting bacteria, which significantly improve plant growth and sequestration of heavy metals. In this work, 184 bacterial strains associated with roots of Pistacia lentiscus were isolated from plants spontaneously growing in the abandoned Sardinian mining areas (SW Sardinia, Italy) and phylogenetically characterised. Twenty-one bacterial isolates were assayed for properties relevant for plant growth promotion and metal tolerance. Five different strains, belonging to the genera Novosphingobium, Variovorax, Streptomyces, Amycolatopsis, Pseudomonas, were selected based on their properties for the greenhouse phytoremediation tests. Among the tested inocula, the strain Variovorax sp. RA128A, able to produce ACC deaminase and siderophore, was able to significantly enhance germination and increase length and weight of shoots and roots. Irrespective of the applied treatment, mastic shrub was able to accumulate Cd, Pb and Zn especially in roots.     

Variations in the structure of airborne bacterial communities in Tsogt-Ovoo of Gobi desert area during dust events

Asian dust events transport the airborne bacteria in Chinese desert regions as well as mineral particles and influence downwind area varying biological ecosystems and climate changes. However, the airborne bacterial dynamics were rarely investigated in the Gobi desert area, where dust events are highly frequent. In this study, air samplings were sequentially performed at a 2-m high above the ground at the sampling site located in desert area (Tsogt-Ovoo of Gobi desert; Mongolia 44.2304°N, 105.1700°E). During the dust event days, the bacterial cells and mineral particles increased to more than tenfold of concentrations. MiSeq sequencing targeting 16S ribosomal DNA revealed that the airborne bacteria in desert area mainly belonged to the classes Acidobacteria, Actinobacteria, Bacteroidetes, Chloroflexi, Bacilli, Alpha-proteobacteria, Beta-proteobacteria, and Gamma-proteobacteria. The bacterial community structures were different between dust events and non-dust events. The air samples collected at the dust events indicated high abundance rates of Alpha-proteobacteria, which were reported to dominate on the leaf surfaces of plants or in the saline lake environments. After the dust events, the members of Firmicutes (Bacilli) and Bacteroidetes, which are known to form endospore and attach with coarse particles, respectively, increased their relative abundances in the air samples. Presumably, the bacterial compositions and diversities in atmosphere significantly vary during dust events, which carry some particles from grassland (phyllo-sphere), dry lake, and sand surfaces, as well as some bacterial populations such as Firmicutes and Bacteroidetes maintain in the atmosphere for longer time.     

Microcystin Bioaccumulation in Freshwater Fish at Different Trophic Levels from the Eutrophic Lake Chaohu,China

The spatial and temporal variations of microcystins (MCs) in fishes with different trophic levels were studied monthly in Lake Chaohu in 2014. MCs content in muscle was highest in phytoplanktivorous Hypophthalmichthys molitrix (H. molitrix), followed by omnivorous Carassius auratus (C. auratus), and was lowest in herbivorous Parabramis pekinensis (P. pekinensis) and carnivorous Coilia ectenes (C. ectenes). MCs concentration in liver was highest in C. auratus, followed by H. molitrix, and was lowest in P. pekinensis and C. ectene. The main uptake routes of MCs for C. auratus and H. molitrix were via the diet. The mechanism to counteract MCs had not been well developed in C. ectenes. H. molitrix and C. auratus from the western region as they had higher mean concentrations of MCs than fishes from the eastern region. The estimated daily intakes of MCs in 45.4% of muscle samples were higher than the provisional tolerable daily intake set by WHO.     

Arbuscular Mycorrhizal Fungi Favor the Initial Growth of <Emphasis Type="Italic">Acacia mangium,Sorghum bicolor</Emphasis>, and <Emphasis Type="Italic">Urochloa brizantha</Emphasis> in Soil Contaminated with Zn,Cu, Pb,and Cd

This study evaluated the effect of inoculation with a mixture of spores of arbuscular mycorrhizal fungi (AMF) (Glomus macrocarpum, Paraglomus occultum, and Glomus sp.) on the initial establishment of Acacia mangium, Sorghum bicolor, and Urochloa brizantha in soil contaminated with heavy metals. The experiment was conducted in a greenhouse, in plastic pots containing 1.8 kg of soil, which presented 7200, 1140, 480, and 72 mg of Zn, Cu, Pb, and Cd, respectively. The chlorophyll content (SPAD index) of inoculated plants of A. mangium and U. brizantha was higher than those of non-inoculated plants (p?<?0.05). No differences were detected for the concentration of heavy metals in plant shoots, whether the plant was inoculated or not. However, inoculated plants had greater root length (S. bicolor and U. brizantha) (p?<?0.05) and greater plant height (A. mangium) (p?<?0.05). The present results demonstrate that the beneficial effects of AMF on plant growth and the alleviation of contaminants are imperative factors for the rehabilitation of soils contaminated with heavy metals.     

Effects of <Emphasis Type="Italic">Dracontomelon duperreanum</Emphasis> Leaf Litter on the Growth and Photosynthesis of <Emphasis Type="Italic">Microcystis aeruginosa</Emphasis>

This study investigated the use of Dracontomelon duperreanum leaf litter extract (DDLLE) in inhibiting the growth and photosynthesis of the algae Microcystis aeruginosa. The goal of the study was to evaluate a potential solution for cyanobacterial bloom prevention. M. aeruginosa was exposed to extract concentrations from 0.4 to 2.0 g L^?1. Chlorophyll-a (Chl-a) content and photosynthesis levels were assessed using pulse amplitude modulated fluorimetry phytoplankton analyzer. Results suggested that the extract could efficiently suppress M. aeruginosa growth. The content of Chl-a was only 19.0 µg L^?1 and achieved 96.0% inhibition rate when exposed to 2.0 g L^?1 on day 15. Growth rate in response to different extract concentrations were consistent with changes in the photosynthesis efficiency (alpha), maximal relative electron transport rate and maximal photochemical efficiency of photosystem II (F _v /F _m ). Furthermore, several kinds of volatile chemicals and their concentrations in DDLLE had been identified by GC–MS, which of them play major role to suppress the growth of M. aeruginosa should be further studied.     

Prevalence of childhood diarrhea and associated risk factors in Dire Dawa,eastern Ethiopia

Aim

Childhood diarrhea caused by enteric bacteria remains an important public health problem in the developing countries. Therefore, this study aimed to determine the prevalence of childhood diarrhea, etiological agents, antibiotic susceptibility patterns and associated risk factors in Eastern Ethiopia.

Subjects and methods

A total of 196 children under the age of 5 years with diarrhea were chosen for the study. Stool specimens were collected for the isolation of bacterial agents and their antibiotic susceptibility pattern using standard methods. Analysis of data was done using SPSS version 16.

Results

The overall prevalence of enteric bacteria observed in this study was 21.9%. The bacterial isolates identified were Escherichia coli (12.8%), Shigella species (5.6%) and Salmonella species (3.6%). Children using an unprotected spring/well source for their water supply were more likely to be infected with diarrhea-causing bacteria (AOR = 4.74, 95% CI: 1.48,15.13). None of the bacterial isolates showed resistance to ceftriaxone, while resistance to amoxicillin was observed for Shigella (100%), Salmonella (85.7%) and E. coli (56%) isolates. Resistance to ampicillin was found to be 90.9%, 71.4% and 52% for Shigella, Salmonella and E. coli isolates. All Shigella isolates were found to be multidrug resistant.

Conclusion

Interventions aimed to improve safe drinking water access should be strengthened/considered in the study area.

     

Distribution of <Emphasis Type="Italic">Aeromonas</Emphasis> species in environmental water used in daily life in Okinawa Prefecture,Japan

Objectives

The genus Aeromonas is known to causes diseases such as food poisoning, sepsis, and wound infection. However, the mode of Aeromonas transmission from environment to humans is not clearly understood. To evaluate the health risks of Aeromonas spp. in environmental freshwater, the number, proportion and putative virulence factors of Aeromonas species were investigated in Okinawa Prefecture, Japan.

Methods

Environmental freshwater samples were collected from three dams, two springs and three private wells. Aeromonas strains were identified by the biochemical method and the viable count was calculated. The production of extracellular enzymes and the virulence genes were investigated for possessing putative virulence factors using representative isolates.

Results

At least seven species of already-known Aeromonas isolates as well as unidentified Aeromonas spp. with/without arginin dehydrolase (ADH) exist in water at these sites. Aeromonas spp. was found to exist at over 1000 CFU/100 ml in one spring and two wells. A. veronii biovar sobria and A. jandaei were the predominant species in dams, and A. hydrophila and/or A. eucrenophila were predominant in wells. Almost all the sampled Aeromonas species produced protease, gelatinase, lipase, esterase and DNase, but A. caviae, A. caviae-like bacteria, and A. eucrenophila had low hemolytic activity. Most sampled A. hydrophila strains possessed both aerolysin gene (aer) and hemolysin gene (hlyA), but A. caviae and A. eucrenophila strains did not possess either gene.

Conclusions

Since these results indicated that several Aeromonas species having potential pathogenicity exist in environmental water in Okinawa, surveys are recommended as a public health measure.

     

Intestinal Infections Among Febrile Hospitalized Patients in the Republic of Armenia: A Retrospective Chart Review

In the past, several enteric outbreaks in 1996, 1998, 1999, and 2003 caused by Salmonella typhi, a Gram-negative bacterium, have occurred in Armenia. This study describes the demographic, epidemiological, and clinical characteristics of febrile hospitalized patients with intestinal infections in Armenia. Using a chart review study design, medical data from adult patients who were hospitalized at the Nork hospital during 2010–2012 were reviewed. A total of 600 medical charts were reviewed. Of these, 51 % were diagnosed with intestinal infections. Among these patients, 59 % had an intestinal infection of known etiology, with three main pathogens identified: Salmonella sp. (32 %), Shigella sp. (32 %), and Staphylococcus aureus (18 %). After controlling for the calendar year, age in years, and gender, patients detected with Salmonella sp. were more likely to reported the presence of a family member with similar signs or symptoms [odds ratio (OR) 9.0; 95 % CI 2.4–33.7] and the lack of a water tap at home (OR 3.9; 95 % CI 1.7–9.5). Evidence indicates that Salmonella sp., Shigella sp., and S. aureus as the most common etiologies reported among febrile hospitalized patients. A high percentage of patients had intestinal infections of unknown etiology; thus, improvement in laboratory capacity (enabling more advanced tests, such as polymerase chain reaction) would increase the identification of the enteropathogens causing disease in Armenia.     

Polychlorinated Biphenyl Bioaccumulation Patterns Among Lake Erie Lower Trophic Level Consumers Reflect Species Ecologies

Polychlorinated biphenyl (PCB) concentrations were quantified in lower trophic level consumers of the Lake Erie western basin food web to assess the capacity of PCBs to discriminate among trophically similar species inhabiting different compartments of the same ecosystem. Zooplankton were characterized by higher proportions of less chlorinated and hydrophobic homologs relative to zebra mussel (Dreissena polymorpha), mayfly (Hexagenia limbata) and emerald shiner (Notropis atherinoides) samples. PCB biota-sediment accumulation factors (BSAF) differed significantly among species with zebra mussels and emerald shiners having the highest BSAFs. Principal components analysis of sample PCB profiles reflected the contrasting pelagic and benthic habitats occupied by filter-feeding zooplankton and zebra mussel samples. Benthic mayfly PCB profiles were characterized by increasingly hydrophobic (logK _OW?≥?6.9) congeners with more variable emerald shiner profiles reflecting the greater mobility and extent of spatial habitat integration achieved by this secondary consumer. These results contribute to growing evidence for the use of PCBs as ecological tracers in aquatic ecosystems.     

Analysis of fungal contamination in vehicle air filters and their impact as a bioaccumulator on indoor air quality

Studies on air quality within automotive vehicles are an emerging research area in Brazil, especially in the city of São Paulo, one of the most polluted cities in the world and with the largest fleet of vehicles in the country. Indoor air quality is an indicator of environmental health that takes into account, in addition to thermal comfort, factors that interfere in precarious air conditions, such as the presence of fungi, bacteria and carbon dioxide in indoor air-conditioned environments. The objective of the present study was to analyse the fungal contamination in air-conditioning filters collected from 21 automotive vehicles and the study found 17 fungal genera in all samples collected (100%), including toxigenic fungi such as Penicillium, Fusarim and Aspergillus, indicating that indoor air quality can compromise the health of a portion of the population, such as professional drivers. Among the Aspergillus genus, the results showed the presence of the A. flavus, A. niger, A. fumigatus, A. ochraceus and A. clavatus species, which cause severe allergic and pulmonary respiratory diseases. Air in artificially heated environments should provide comfort to its occupants but it may pose a risk to human health if the car filtration system is contaminated by pathogenic fungi.     

Evaluation of the Sensitivity of Freshwater Organisms Used in Toxicity Tests of Wastewater from Explosives Company

Explosives industries are a source of toxic discharge. The aim of this study was to compare organisms sensitivity (Daphnia similis, Danio rerio, Escherichia coli and Pseudomonas putida) in detecting acute toxicity in wastewater from two explosives, 2,4,6-TNT (TNT) and nitrocellulose. The samples were collected from an explosives company in the Paraiba Valley, São Paulo, Brazil. The effluents from TNT and nitrocellulose production were very toxic for tested organisms. Statistical tests indicated that D. similis and D. rerio were the most sensitive organisms for toxicity detection in effluents from 2,4,6-TNT and nitrocellulose production. The P. putida bacteria was the organism considered the least sensitive in indicating toxicity in effluents from nitrocellulose.     

The association between social network factors and mental health at different life stages

Objectives

Psychosocial factors are important determinants of an individual’s health. This study examines the association between health scores and social network factors on mental health across different life stages.

Methods

Data were drawn from the Household Income and Labour Dynamics in Australia survey for adolescents (n = 1739), adults (n = 10,309) and seniors (n = 2287). Hierarchical regression modelling was applied to examine effects within and across age groups. All the variables were derived from the self-completion questionnaire.

Results

The social network factors were statistically significant predictors of mental health outcomes for all three life stages. For adolescents, the three social network factors were statistically significant with social isolation having the largest impact (β = ?.284, p < .001), followed by social connection (β = .084, p < .001) and social trust having a similar effect (β = .073, p < .001). For adults social isolation had the highest impact (β = ?.203, p < .001), followed by social connection (β = .110, p < .001) and social trust (β = .087, p < .001).The results for seniors were social isolation (β = ?.188, p < .001), social connection (β = .147, p < .001) and social trust (β = .032, p < .05).

Conclusions

After adding the social network factors, the models improved significantly with social isolation playing the most significant role across all life stages, whereas the other social network factors played a differentiated role depending upon the life stage. These findings have practical implications in the design of mental health interventions across different life stages.

     

Effects of Low-Frequency Ultrasound on <Emphasis Type="Italic">Microcystis aeruginosa</Emphasis> from Cell Inactivation to Disruption

Ultrasound can be used to induce cell resonance and cavitation to inhibit cyanobacterial growth, but it can also lead to increase in dissolved nutrients because of cell disruption. This study investigated the process from cell inactivation to disruption of Microcystis aeruginosa. Algal cells were sonicated (at 35 kHz) under various intensities and durations. Results showed that chlorophyll a content and F_v/F_m values decreased slightly within the first 5 min. Superoxide dismutase activity was stimulated and its peak value appeared at the fifth minute. After 20 min, considerable number of ruptured cells were observed and the concentrations of dissolved nitrogen and phosphorus increased rapidly. Finally, ammonia and nitrate merely composed a small portion of dissolved nitrogen. This study demonstrated that excessive ultrasound treatment can significantly rupture algal cells and lead to the release of cellular inclusions, which may cause ecological issues or public health problems. Based on our findings, ultrasonic intensity controlled at 0.035 W/mL and applied for a duration of 20 min delivers the optimal result in effectively inhibiting physiological activities of Microcystis aeruginosa without marked cell disruption. This will ultimately help to achieve algal control, while conserving energy and preserving the environment and human health.     

Lead and Arsenic Accumulation and Its Effects on Plasma Cortisol Levels in <Emphasis Type="Italic">Oreochromis</Emphasis> sp.

The accumulation, elimination and effect of heavy metals on plasma cortisol levels in Oreochromis sp. were studied in the exposure and recovery phases. In the exposure phase, the mean rate of accumulation in the tissues was in the order gill?>?liver?>?muscle for Pb exposure and muscle?>?liver?>?gill for As exposure. In the recovery phase, the order of elimination in the tissues was gill?>?liver?>?muscle for Pb and liver?>?gill?>?muscle for As. The amount of cortisol secreted by the Oreochromis sp. after Pb or As treatment was lower compared to Oreochromis sp. in the control group during the exposure phase. In the recovery phase, plasma cortisol levels in Oreochromis sp. increased in all Pb treatment groups while it continuously decreased in all As treatment groups. A fish affected by As has obvious difficulty recovering from the stress response. It was concluded that exposure to the tested concentrations of Pb and As over 20 days could be a potent endocrine disruptor, which may lead to adverse impacts on the health of the Oreochromis sp.     

Phylogenetic analysis of bacterial species compositions in sand dunes and dust aerosol in an Asian dust source area,the Taklimakan Desert

Airborne microorganisms (bioaerosol) from the China desert region, which are released into the atmosphere, disperse by the Asian dust event and affect ecosystems, human life, and atmospheric processes in downwind areas. However, the dynamics of airborne bacteria over the China desert regions have rarely been investigated. In this study, we analyzed bacterial communities in aerosols of the Asian dust source region (Taklimakan Desert) and compared them with the bacterial communities in sand dunes, for evaluating the mixtures from sand area to atmosphere. Air samples were collected at 10 m above the ground level from Dunhuang City during a dust event. The cell densities of airborne bacteria during a dust event were ten times more than that in non-dust periods. The 16S rDNA clone libraries from four air samples mainly belonged to two phyla, Firmicutes and Proteobacteria. During a dust event, the proportion of Proteobacteria clones decreased, whereas that of Firmicutes clones increased. Sand samples were collected from the sand dunes in four sampling sites of the Taklimakan Desert. The bacterial communities in sand samples comprised of the members of Firmicutes and Actinobacteria. The clones of Firmicutes in both air and sand samples included Bacillus species, constituting more than 10 % of total clones. Airborne bacterial communities would be carried by the dust events from sand dunes. Propionibacterium species from the class Actinobacteria that were dominant in sand samples were not detected in the air samples, suggesting that atmospheric stressors eliminate some bacterial species. Presumably, airborne bacterial communities in the Asian dust source region are composed of local environmental bacteria, and their dynamics depend on the occurrence of a dust event.