Rapid and sensitive detection of an intracellular pathogen in human peripheral leukocytes with hybridizing magnetic relaxation nanosensors

Bacterial infections are still a major global healthcare problem. The quick and sensitive detection of pathogens responsible for these infections would facilitate correct diagnosis of the disease and expedite treatment. Of major importance are intracellular slow-growing pathogens that reside within peripheral leukocytes, evading recognition by the immune system and detection by traditional culture methods. Herein, we report the use of hybridizing magnetic nanosensors (hMRS) for the detection of an intracellular pathogen, Mycobacterium avium spp. paratuberculosis (MAP). The hMRS are designed to bind to a unique genomic sequence found in the MAP genome, causing significant changes in the sample's magnetic resonance signal. Clinically relevant samples, including tissue and blood, were screened with hMRS and results were compared with traditional PCR analysis. Within less than an hour, the hMRS identified MAP-positive samples in a library of laboratory cultures, clinical isolates, blood and homogenized tissues. Comparison of the hMRS with culture methods in terms of prediction of disease state revealed that the hMRS outperformed established culture methods, while being significantly faster (1 hour vs 12 weeks). Additionally, using a single instrument and one nanoparticle preparation we were able to detect the intracellular bacterial target in clinical samples at the genomic and epitope levels. Overall, since the nanoparticles are robust in diverse environmental settings and substantially more affordable than PCR enzymes, the potential clinical and field-based use of hMRS in the multiplexed identification of microbial pathogens and other disease-related biomarkers via a single, deployable instrument in clinical and complex environmental samples is foreseen.     

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.     

Comparison of spatial scale variability of shoot density and epiphytic leaf assemblages of Halophila stipulacea and Cymodocea nodosa on the Eastern Coast of Tunisia

Abstract

A study was undertaken to compare the patterns of spatial variability, epiphytic percentage cover, and distribution of epiphytic fauna and flora between the two adjacent seagrasses Cymodocea nodosa and the invasive species Halophila stipulucea. Samples were taken at six stations separated by 600?m and exposed to different current conditions. The stations G2 and G5 were affected by a high current tide, while G4 was directly exposed to the northern marine currents. The station G3 was situated in the middle of a Posidonia oceanica bed and was less exposed to hydrodynamism, whereas the other stations were relatively protected. Results indicate that for both H. stipulacea and C. nodosa, shoot density and epiphytic cover biomass decreased when exposed to high levels of hydrodynamic activity. In terms of epiphytic leaf assemblages, our results showed significant differences for the two host plants in their mean cover and for the six stations at the largest and smallest spatial scale. Our observations highlight the dominance of Rhodophyta and the low number of epiphytic species and the epiphytic cover on H. stipulacea compared to C. nodosa. In addition, results indicate the absence of two taxa Hydrozoans and Annelida in the epiphytic assemblage of H. stipulacea leaves.     

Nonsuicidal Self-Injury and Suicidal Behavior: A Latent Class Analysis among Young Adults

Although there is a general consensus among researchers that engagement in nonsuicidal self-injury (NSSI) is associated with increased risk for suicidal behavior, little attention has been given to whether suicidal risk varies among individuals engaging in NSSI. To identify individuals with a history of NSSI who are most at risk for suicidal behavior, we examined individual variability in both NSSI and suicidal behavior among a sample of young adults with a history of NSSI (N = 439, Mage = 19.1). Participants completed self-report measures assessing NSSI, suicidal behavior, and psychosocial adjustment (e.g., depressive symptoms, daily hassles). We conducted a latent class analysis using several characteristics of NSSI and suicidal behaviors as class indicators. Three subgroups of individuals were identified: 1) an infrequent NSSI/not high risk for suicidal behavior group, 2) a frequent NSSI/not high risk for suicidal behavior group, and 3) a frequent NSSI/high risk for suicidal behavior group. Follow-up analyses indicated that individuals in the ‘frequent NSSI/high risk for suicidal behavior’ group met the clinical-cut off score for high suicidal risk and reported significantly greater levels of suicidal ideation, attempts, and risk for future suicidal behavior as compared to the other two classes. Thus, this study is the first to identity variability in suicidal risk among individuals engaging in frequent and multiple methods of NSSI. Class 3 was also differentiated by higher levels of psychosocial impairment relative to the other two classes, as well as a comparison group of non-injuring young adults. Results underscore the importance of assessing individual differences in NSSI characteristics, as well as psychosocial impairment, when assessing risk for suicidal behavior.     

Diversity of waterbirds wintering in Douz wetlands (south Tunisia): factors affecting wetland occupancy and species richness

Understanding the environmental factors shaping wetland attractiveness for waterbirds is an important question in wetland ecology and for conservation purposes. However, detailed data from numerous North African wetlands, notably those situated in inland areas, are still lacking. Thus, the aim of this study was to identify the factors influencing wetland use by waterbirds wintering in one of such poorly known habitat systems, namely the Saharan wetland complex of Douz, in south-western Tunisia. Thirty-four waterbird species (20 wading birds and 14 waterfowl species) were found to winter in this area. Using discriminant function analyses, we found that wetland size was the unique variable discriminating between occupied and unoccupied sites for total waterbirds and wading birds, while waterfowl distribution was related to both wetland size and water depth. Wetland size also provided the strongest predictor of species richness of wading birds, waterfowl and total waterbirds. Overall, our findings highlight the importance of wetland size as a key factor determining the attractiveness of wetlands for waterbirds wintering in the Saharan wetland complex of Douz. The possible explanations of this wetland size effect are discussed.     

Improving vanadium stress tolerance of watermelon by grafting onto bottle gourd and pumpkin rootstock

Vanadium (V) is a transition metal found in the Earth crust. V adversely affects plant growth and development. Besides several other management practices, grafting of scion cultivars onto appropriate rootstock provides a suitable solution. Grafting is an important agro-technical procedure utilized to enhance the capacity of plants to tolerate biotic and abiotic stresses. In this study, watermelon was grafted onto bottle gourd and pumpkin rootstock, and self-grafted watermelon plants were utilized as a control. V was applied at the rate of 50 mg/L under hydroponic conditions. The result showed that V application substantially reduces the growth of watermelon plants, however, grafting of watermelon onto bottle gourd and pumpkin rootstock improves V stress tolerance of watermelon by reducing the V concentration in leaf tissues, improving the relative chlorophyll content (SPAD index) and photosynthetic assimilation, up-regulating the expression of SOD (Cla008698, Cla0012125, Cla009820 and Cla001158), glutathione S-transferase (Cla013224) and glutathione peroxidase (Cla021039) genes in the leaves, and enhancing the activities of antioxidant enzymes (SOD, CAT). The scanning electron microscopy (SEM) of the root tips showed that minimal damage of roots was observed for pumpkin roots compared with the roots of watermelon and bottle gourd under V stress conditions. So far as we know, these results are the first evidence that grafting mitigates V stress in plants.