Crystal structure of human PACRG in complex with MEIG1 reveals roles in axoneme formation and tubulin binding

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Antagonistic actions of Pythium oligandrum and Trichoderma harzianum against phytopathogenic fungi (Fusarium oxysporum and Pythium ultimum var. ultimum)

Abstract

The possible biological control of damping-off fungi, Fusarium oxysporum and Pythium ultimum by Pythium oligandrum or Trichoderma harzianum was in vitro investigated. Results of comparing the antagonistic activity of P. oligandrum and T. harzianum in dual plates against the tested phytopathogens indicated different degrees of antagonism. After 12 days of incubation colony of the phytopathogenic fungus was completely overgrown by the antagonist, except for the interaction between T. harzianum and F. oxysporum which showed no overgrowth or any hyphal penetration by the antagonist. However, growth and proliferation of F. oxysporum colony was repressed. T. harzianum and P. oligandrum produced chitinase and β-1,3-glucanase when they were grown on liquid culture medium supplemented with chitin or fungal dried mycelium as a sole carbon source, and enzyme production was higher by T. harzianum comparing with P. oligandrum under the same condition. Fungal dried mycelium of F. oxysporum was the most selective carbon source for enzyme production, on the other hand, chitinase production was significant locked when P. ultimum dried mycelium was used as a carbon source. Production of volatile compounds by P. oligandrum or T. harzianum against F. oxysporum and P. ultimum was examined using the inverted plates method. F. oxysporum was inhibited by the antagonist volatile compounds and it is inhibited 100% by increasing the amount of inoculum size. Production of potential biocontrol agents provided with economically features and working under field conditions are recommended.     

Ultrastructural changes in the muscles,midgut, hemopoietic organ,imaginal discs and Malpighian tubules of the mosquito Aedes aegypti larvae infected by the fungus Coelomomyces stegomyiae

Fungi belonging to the genus Coelomomyces can infect mosquito larvae and develop within the larval hemocoel. To examine fungal development, Aedesaegypti larvae infected with Coelomomyces stegomyiae Keilin were fixed, embedded and sectioned for both light and electron microscopy. While fungal hyphae of C. stegomyiae did not invade cells other than the cuticular epithelial cells, they did penetrate a number of tissues including muscles, midgut, hemopoietic organ, imaginal discs, and Malpighian tubules. This revised version was published online in July 2006 with corrections to the Cover Date.     

Indicator microbes correlate with pathogenic bacteria, yeasts and helminthes in sand at a subtropical recreational beach site

Aims: Research into the relationship between pathogens, faecal indicator microbes and environmental factors in beach sand has been limited, yet vital to the understanding of the microbial relationship between sand and the water column and to the improvement of criteria for better human health protection at beaches. The objectives of this study were to evaluate the presence and distribution of pathogens in various zones of beach sand (subtidal, intertidal and supratidal) and to assess their relationship with environmental parameters and indicator microbes at a non‐point source subtropical marine beach. Methods and Results: In this exploratory study in subtropical Miami (Florida, USA), beach sand samples were collected and analysed over the course of 6 days for several pathogens, microbial source tracking markers and indicator microbes. An inverse correlation between moisture content and most indicator microbes was found. Significant associations were identified between some indicator microbes and pathogens (such as nematode larvae and yeasts in the genus Candida), which are from classes of microbes that are rarely evaluated in the context of recreational beach use. Conclusions: Results indicate that indicator microbes may predict the presence of some of the pathogens, in particular helminthes, yeasts and the bacterial pathogen Staphylococcus aureus including methicillin‐resistant forms. Indicator microbes may thus be useful for monitoring beach sand and water quality at non‐point source beaches. Significance and Impact of the Study: The presence of both indicator microbes and pathogens in beach sand provides one possible explanation for human health effects reported at non‐point sources beaches.     

Recent environmental change in North African wetland lakes: diatom and other stratigraphic evidence from nine sites in the CASSARINA Project

All nine wetland lakes in the CASSARINA North African suite of sample sites have been disturbed strongly by human activity during the 20th century. Dated lake sediment core were used to provide evidence of the extent of recent environmental change at each site. Sedimentary diatoms at seven sites were useful for inferring salinity change trends during the last century. At two sites preservation problems severely degraded the sedimentary diatom record. Sediment core integrity was otherwise established.Lithostratigraphic measurements indicated some site specific changes in soil erosion and sediment composition but, for the Egyptian Delta lakes, no physical signal synchronous with Aswan High Dam construction was found. Sedimentary diatom assemblages were generally site characteristic and halophilous taxa were common. At two sites planktonic diatoms indicated some recent eutrophication but generally the assemblages were more indicative of salinity changes. Diatom-inferred salinity trends for the seven sites typically indicated that reductions in water salinity occurred sometime during the early or mid 20th century.Rather than climate, hydrological modification of water resources is implicated as the primary driver of salinity changes during most of the 20th century. In the western North African region these modifications were mainly local land drainage and water diversion programmes to alleviate winter flooding and/or promote summer water availability. In the Delta region, the Nile has been intensively exploited since antiquity and intensively so from the late 19th century to release more fresh water for agriculture. Here, diatom records indicate that freshening began well before the Aswan High Dam but salinity fluctuations have tended to diminish during the latter part of the 20th century. A small reversal in the water freshening trend in the 1980/90s was possibly a response to land subsidence/sea-level change or to reduced freshwater supply.Freshwater supply to the sites is generally diminishing as former freshwater surpluses switch to deficit. One site (Merja Bokka, Morocco) became completely dry in 1998 as agriculture encroached and Megene Chitane, the only acid lake in Tunisia, is currently affected by excessive inflow abstraction. At the beginning of the 21st century, eight of the nine CASSARINA sites persist as viable but modified aquatic ecosystems. They nevertheless continue to support valuable aquatic biodiversity, especially in the Delta sites and in Chitane. The modern diatom communities are clearly tolerant of considerable environmental change but the remaining sites are increasingly threatened by major hydrological disturbance. Base-line floristic data for the late 20th century are given but continuous biomonitoring combined with effective management is needed urgently to help conserve North Africa's diminishing natural wetland lake resources.     

Some observations on the age and growth of thin-lipped grey mullet, Liza ramada Risso, 1826 (Pisces, Mugilidae) in three North African wetland lakes: Merja Zerga (Morocco), Garâat Ichkeul (Tunisia) and Edku Lake (Egypt)

Age and growth characteristics of the thin-lipped Grey Mullet (Liza ramada) were investigated in three North African wetland lakes: Merja Zerga (Morocco), Garâat Ichkeul (Tunisia) and Edku Lake (Egypt). Age structure of the mullet populations was very similar in all three study lakes. Small differences in growth were indicated, especially for the Moroccan population, where growth tended to be slower than for the other two populations. The fastest growth was observed in the Edku population while the best condition was observed in the Ichkeul population. Compared with some European populations, the sampled North African populations have faster growth and better condition factors.     

Isolation of Pythium oligandrum from Egyptian soil and its mycoparasitic effect on Pythium ultimum var. ultimum the damping-off organism of wheat

Pythium oligandrum Drechsler bearing spherical sporangia with complex subglobose elements was isolated for the first time in Egypt from agricultural field soil cultivated with alfalfa (Trifolium alexandrinum) in El-Minia, Egypt. This fungus was found to be an active bio-control agent against P. ultimum var. ultimum, the damping-off organism of wheat. In agar plates, P. oligandrum parasitized P. ultimum var. ultimum hyphae with the aid of thin haustorial branches or infection pegs, eventually leading to host destruction. Incorporation of P. oligandrum into carboxymethylcellulose seed coating successfully eliminated pre-emergence damping-off of wheat caused by P. ultimum var. ultimum, whereas Post-emergence damping-off was prevented by adding inocula of P. oligandrum to the soil. This revised version was published online in June 2006 with corrections to the Cover Date.     

Social Network and Vulnerability: A Clear Link in Bedouin Society (Egypt)

In the last 60 years, the livelihoods of agro-pastoral and pastoral families in the arid and semi-arid zones in North Africa and the Middle East have undergone major changes caused by significant incentives to adopt a sedentary lifestyle and the increasing intensity of drought events. Such changes have also been influenced by land reclamation projects accompanied by the construction of reservoirs and dikes in the dry lands as well as the extension of irrigation canals in the desert in the Coastal Zone of the Western Desert, Egypt. To understand the changes in the traditional social organization of this desert society, and how these social changes have affected families’ ability to adapt to external shocks such as the recent 15-year drought, we developed a typological approach to investigate the link between family livelihoods and social capital in Bedouin society. We showed a clear link between physical assets (mainly land and animals), the nature and intensity of social links within the traditional society, and level of education. The analysis revealed also some new wealth accumulation processes in link with the socio-political influence of urban zones and the increasing level of education in the zone.     

Presence of Pathogens and Indicator Microbes at a Non-Point Source Subtropical Recreational Marine Beach

Swimming in ocean water, including ocean water at beaches not impacted by known point sources of pollution, is an increasing health concern. This study was an initial evaluation of the presence of indicator microbes and pathogens and the association among the indicator microbes, pathogens, and environmental conditions at a subtropical, recreational marine beach in south Florida impacted by non-point sources of pollution. Twelve water and eight sand samples were collected during four sampling events at high or low tide under elevated or reduced solar insolation conditions. The analyses performed included analyses of fecal indicator bacteria (FIB) (fecal coliforms, Escherichia coli, enterococci, and Clostridium perfringens), human-associated microbial source tracking (MST) markers (human polyomaviruses [HPyVs] and Enterococcus faecium esp gene), and pathogens (Vibrio vulnificus, Staphylococcus aureus, enterovirus, norovirus, hepatitis A virus, Cryptosporidium spp., and Giardia spp.). The enterococcus concentrations in water and sand determined by quantitative PCR were greater than the concentrations determined by membrane filtration measurement. The FIB concentrations in water were below the recreational water quality standards for three of the four sampling events, when pathogens and MST markers were also generally undetectable. The FIB levels exceeded regulatory guidelines during one event, and this was accompanied by detection of HPyVs and pathogens, including detection of the autochthonous bacterium V. vulnificus in sand and water, detection of the allochthonous protozoans Giardia spp. in water, and detection of Cryptosporidium spp. in sand samples. The elevated microbial levels were detected at high tide and under low-solar-insolation conditions. Additional sampling should be conducted to further explore the relationships between tidal and solar insolation conditions and between indicator microbes and pathogens in subtropical recreational marine waters impacted by non-point source pollution.Global estimates indicate that each year more than 120 million cases of gastrointestinal disease and 50 million cases of severe respiratory diseases are caused by swimming and bathing in wastewater-polluted coastal waters (42). Swimming-related illness is attributed predominantly to exposure to microbial pathogens, which enter the water through point sources, such as sewage outfalls. Water quality at beaches may also be impacted by non-point sources, such as storm water runoff, sand resuspension, animal fecal inputs, and human bather shedding (8, 12, 22, 47, 59).The concentration of indicator microorganisms in a body of recreational water is used to estimate the health risk to bathers. These microbes serve as surrogates for microbial pathogens. Studies show that the U.S. Environmental Protection Agency (EPA)-recommended indicator microbe for marine beaches, enterococci, shows a significant correlation with illness in marine beaches impacted by point source pollution (38, 54). However, a similar correlation has not been identified at beaches impacted by non-point source pollution or subtropical marine beaches (17, 29, 38, 54).The failure to consistently demonstrate an association between enterococci and illness at non-point source beaches calls into question the ability of indicator microbes to predict the presence of pathogens. Studies conducted on the west coast of the United States have shown that indicators are often not correlated with measured pathogens at non-point source beaches (31, 32, 33, 37). Additional studies conducted in a subtropical environment, such as that of South Florida, where this study was conducted, have repeatedly shown the limited accuracy of indicator microbe standards for determining the presence of pathogens (27, 35). This lack of correlation is understandable since an indicator microbe, such as enterococci, may come from relatively low-risk sources of fecal pollution and therefore may not be related to human or other high-risk sources of fecal pollution and pathogens (9). It has also been shown in both subtropical and temperate climates that indicator bacteria can multiply in the environment, resulting in a false impression of increased microbial pollution and pathogen presence (4, 7, 19, 24, 41, 45, 57, 58). Environmental factors, such as tide, rain, and solar insolation, can also have significant and varying effects on the levels of indicator and pathogenic microbes (21, 24, 33).The lack of correlation between pathogens and indicator microbes at non-point source beaches can result in two problematic scenarios. If indicator microbes are absent and pathogens are present (false-negative scenario), regulatory monitoring may fail to identify the potential adverse health effects on bathers due to the pathogens. This problem is likely to occur since indicator bacteria are less resistant to environmental stresses and disinfection at wastewater treatment plants than certain pathogens (6, 15). However, if indicator microbes are present and pathogens are absent (false-positive scenario), there can be unnecessary economic losses due to recreational beach advisories and/or closures. A 4-month closure of Huntington Beach in 1999 due to microbial standard violations resulted in the loss of millions of dollars in tourism income to the business community and almost 2 million dollars in beach closure investigation fees (55; for a review, see reference 27).Given these two possible scenarios, the relationship between indicator microbes and pathogens under different environmental conditions at non-point source beaches representing different geographic and climatic settings should be assessed further. Investigation of this relationship would require a large sample size in order to establish possible significant associations between the various factors and targets. The objective of this study was to conduct a preliminary evaluation of the presence of indicator microbes and pathogens and the possible association between indicator microbes, pathogen measurements, and environmental conditions at a subtropical recreational marine beach in South Florida. Because of cost limitations when multiple targets, including pathogens, are screened, this study was not intended to establish a conclusive relationship between the various factors and targets but was intended to provide insight into both the presence of organisms and possible associations which should be investigated further. Such information would be useful for understanding the potential health risks to bathers from non-point sources of microbes and would also contribute to determining the appropriateness of using indicator microbes to monitor the water quality at non-point source beaches. Although previous studies have assessed the presence of either viral, protozoan, or bacterial pathogens along with indicator microbes in point or non-point source recreational beach waters (27, 33, 37, 47), to our knowledge, this is the first study to assess the presence of all three classes of pathogens (viral, protozoan, and bacterial) as well as indicator microbes at a non-point source recreational beach. This study is also the first study to sample for all these microbes in both water and sand at a non-point source recreational beach. Through analysis of the various microbes under different targeted environmental conditions, this study also included a preliminary evaluation of the sources of microbial contaminants and pathogens and the effectiveness of various analytical methods for microbe detection. The latter part of the study included a comparison of three different methods for enterococcus enumeration, as well as an innovative method for simultaneously concentrating protozoans and viruses from water samples.     

A technique for isolating bacteria-freePythium spp. from pond water

A special technique for isolating aquaticPythium spp. that are free from bacteria is presented and discussed by citing the disadvantages of the previous studies.