An NDVI analysis of vegetation trends in an Andean watershed

We performed a Landsat 5-TM derived normalized difference vegetation index (NDVI) analysis in a semi-arid watershed (2700 km²) in the Andes of southern Peru from 1985 to 2010. There, pastoralists rely on wetlands (bofedales) particularly during dry season months and in drought. We calculated annual dry season NDVI for 20 of the 26 years from 1985 to 2010 and used the mean to delineate wetlands in the watershed. To investigate the trends in NDVI, a multiple regression model with the covariates precipitation, temperature, Julian day, and year of image acquisition was performed on each cell (three million individual regressions). Results indicate there is a modest increase in NDVI for the majority of cells (81 %) in the watershed. Approximately 30 % of wetland areas display a decrease in NDVI. Dry season NDVI is moderately correlated with wet season precipitation (R ² = 0.56, p < 0.05) but absent a trend in precipitation, NDVI trends are not explained by this variable. Changes in land management may result in more intensive use of wetlands, causing the decreasing vegetation trends in some locations.     

Entamoeba Clone‐Recognition Experiments: Morphometrics,Aggregative Behavior,and Cell‐Signaling Characterization

Studies on clone‐ and kin‐discrimination in protists have proliferated during the past decade. We report clone‐recognition experiments in seven Entamoeba lineages (E. invadens IP‐1, E. invadens VK‐1:NS, E. terrapinae, E. moshkovskii Laredo, E. moshkovskii Snake, E. histolytica HM‐1:IMSS and E. dispar). First, we characterized morphometrically each clone (length, width, and cell‐surface area) and documented how they differed statistically from one another (as per single‐variable or canonical‐discriminant analyses). Second, we demonstrated that amebas themselves could discriminate self (clone) from different (themselves vs. other clones). In mix‐cell‐line cultures between closely‐related (E. invadens IP‐1 vs. E. invadens VK‐1:NS) or distant‐phylogenetic clones (E. terrapinae vs. E. moshkovskii Laredo), amebas consistently aggregated with same‐clone members. Third, we identified six putative cell‐signals secreted by the amebas (RasGap/Ankyrin, coronin‐WD40, actin, protein kinases, heat shock 70, and ubiquitin) and which known functions in Entamoeba spp. included: cell proliferation, cell adhesion, cell movement, and stress‐induced encystation. To our knowledge, this is the first multi‐clone characterization of Entamoeba spp. morphometrics, aggregative behavior, and cell‐signaling secretion in the context of clone‐recognition. Protists allow us to study cell–cell recognition from ecological and evolutionary perspectives. Modern protistan lineages can be central to studies about the origins and evolution of multicellularity.     

Indoor moulds in asthmatic patients homes

Summary A study was conducted in 29 households with asthmatic patients in order to analyse the indoor mould concentration; an important contamination was found in both the air and the dust. Although it is known that the outdoor mould concentration in the air decreases during winter, we found that the indoor one did not vary throughout the year. Moreover, the indoor mould concentration increased during the winter in recently built houses, probably because of the poor ventilation. The immunological study showed a lack of correlation between the moulds collected and the patients sensitization.     

Segmental duplication implicated in the genesis of inversion 2Rj of Anopheles gambiae

The malaria vector Anopheles gambiae maintains high levels of inversion polymorphism that facilitate its exploitation of diverse ecological settings across tropical Africa. Molecular characterization of inversion breakpoints is a first step toward understanding the processes that generate and maintain inversions. Here we focused on inversion 2Rj because of its association with the assortatively mating Bamako chromosomal form of An. gambiae, whose distinctive breeding sites are rock pools beside the Niger River in Mali and Guinea. Sequence and computational analysis of 2Rj revealed the same 14.6 kb insertion between both breakpoints, which occurred near but not within predicted genes. Each insertion consists of 5.3 kb terminal inverted repeat arms separated by a 4 kb spacer. The insertions lack coding capacity, and are comprised of degraded remnants of repetitive sequences including class I and II transposable elements. Because of their large size and patchwork composition, and as no other instances of these insertions were identified in the An. gambiae genome, they do not appear to be transposable elements. The 14.6 kb modules inserted at both 2Rj breakpoint junctions represent low copy repeats (LCRs, also called segmental duplications) that are strongly implicated in the recent (approximately 0.4N(e) generations) origin of 2Rj. The LCRs contribute to further genome instability, as demonstrated by an imprecise excision event at the proximal breakpoint of 2Rj in field isolates.     

Proteomics in atherothrombosis: a future perspective

Atherothrombosis is the primary cause of death in Western countries. The cellular and molecular mechanisms underlying atherosclerosis remain widely unknown. The complex nature of atherosclerotic cardiovascular diseases demands the development of novel technologies that enable discovery of new biomarkers for early disease detection and risk stratification, which may predict clinical outcome. In this review, we outline potential sources and recent proteomic approaches that could be applied in the search of novel biomarkers of cardiovascular risk. In addition, we describe some issues raised in relation to the application of proteomics to blood samples, as well as two novel emerging concepts, such as peptidomics and population proteomics. In the future, the use of high-throughput techniques (proteomic, genomics and metabolomics) will potentially identify novel patterns of biomarkers, which, along with traditional risk factors and imaging techniques, could help to target vulnerable patients and monitor the beneficial effects of pharmacological agents.     

Z-Phe-Ala-diazomethylketone (PADK) disrupts and remodels early oligomer states of the Alzheimer disease Aβ42 protein

The oligomerization of the amyloid-β protein (Aβ) is an important event in Alzheimer disease (AD) pathology. Developing small molecules that disrupt formation of early oligomeric states of Aβ and thereby reduce the effective amount of toxic oligomers is a promising therapeutic strategy for AD. Here, mass spectrometry and ion mobility spectrometry were used to investigate the effects of a small molecule, Z-Phe-Ala-diazomethylketone (PADK), on the Aβ42 form of the protein. The mass spectrum of a mixture of PADK and Aβ42 clearly shows that PADK binds directly to Aβ42 monomers and small oligomers. Ion mobility results indicate that PADK not only inhibits the formation of Aβ42 dodecamers, but also removes preformed Aβ42 dodecamers from the solution. Electron microscopy images show that PADK inhibits Aβ42 fibril formation in the solution. These results are consistent with a previous study that found that PADK has protective effects in an AD transgenic mouse model. The study of PADK and Aβ42 provides an example of small molecule therapeutic development for AD and other amyloid diseases.     

Nitrogen fixation in annual and perennial legume-grass mixtures across a fertility gradient

Background and aims

The selection of legume species and species mixtures influences agroecosystem nitrogen (N) and carbon cycling. We utilized a fertility gradient to investigate the effects of plant species interactions on biological N fixation of an annual and perennial legume in response to shifting soil resource availability.

Methods

Legume N fixation of annual field pea (Pisum sativum) and perennial red clover (Trifolium pratense) grown in monoculture and mixtures with oats (Avena sativa) or orchardgrass (Dactylis glomerata) was estimated using the ¹⁵N natural abundance method across 15 farm fields and we measured six soil N pools ranging from labile to more recalcitrant.

Results

Evidence of complementary and facilitative species interactions was stronger for the perennial red clover-orchardgrass mixture than for the annual field pea-oat mixture (N Land Equivalency Ratios were 1.6 and 1.2, respectively). We estimated that the transfer of fixed N from red clover to orchardgrass increased aboveground N fixation estimates by 15% from 33 to 38?kg?N ha^?1. Despite a more than 2-fold range in soil organic matter levels and more than 3-fold range in labile soil N pools across field sites, the N fertility gradient was not a strong predictor of N fixation. While grass N assimilation was positively correlated with soil N pools, we found only weak, inverse correlations between legume N fixation and soil N availability. In grass-legume mixtures, soil N availability indirectly influenced N fixation through plant competition.

Conclusions

These results suggest that increasing diversity of cropping systems, particularly through the incorporation of perennial mixtures into rotations, could improve overall agroecosystem N cycling efficiency.     

Development and Characterization of a Mouse Model for Marburg Hemorrhagic Fever

The lack of a mouse model has hampered an understanding of the pathogenesis and immunity of Marburg hemorrhagic fever (MHF), the disease caused by marburgvirus (MARV), and has created a bottleneck in the development of antiviral therapeutics. Primary isolates of the filoviruses, i.e., ebolavirus (EBOV) and MARV, are not lethal to immunocompetent adult mice. Previously, pathological, virologic, and immunologic evaluation of a mouse-adapted EBOV, developed by sequential passages in suckling mice, identified many similarities between this model and EBOV infections in nonhuman primates. We recently demonstrated that serially passaging virus recovered from the liver homogenates of MARV-infected immunodeficient (SCID) mice was highly successful in reducing the time to death in these mice from 50 to 70 days to 7 to 10 days after challenge with the isolate MARV-Ci67, -Musoke, or -Ravn. In this study, we extended our findings to show that further sequential passages of MARV-Ravn in immunocompetent mice caused the MARV to kill BALB/c mice. Serial sampling studies to characterize the pathology of mouse-adapted MARV-Ravn revealed that this model is similar to the guinea pig and nonhuman primate MHF models. Infection of BALB/c mice with mouse-adapted MARV-Ravn caused uncontrolled viremia and high viral titers in the liver, spleen, lymph node, and other organs; profound lymphopenia; destruction of lymphocytes within the spleen and lymph nodes; and marked liver damage and thrombocytopenia. Sequencing the mouse-adapted MARV-Ravn strain revealed differences in 16 predicted amino acids from the progenitor virus, although the exact changes required for adaptation are unclear at this time. This mouse-adapted MARV strain can now be used to develop and evaluate novel vaccines and therapeutics and may also help to provide a better understanding of the virulence factors associated with MARV.The filoviruses, Marburgvirus and Ebolavirus (MARV and EBOV), cause severe hemorrhagic fevers in humans and nonhuman primates (27). The incubation time is estimated to be 3 to 21 days, with human case fatality rates reaching 90% in some outbreaks. Filoviral hemorrhagic fevers are characterized by a nonspecific viral prodrome in the early stage of infection, including fever, headaches, and myalgia (27). This is followed by a hemorrhagic phase that can include development of a maculopapular rash, petechiae, and bleeding from the gums, intestines, and other mucosal surfaces. Death usually occurs within a week of initial symptoms and is thought to be due to uncontrolled viral replication, hypotension-induced shock caused by increased vascular permeability, and multiorgan failure, likely caused by disseminated intravascular coagulation and extensive necroses in the liver, spleen, intestine, and many other major organ systems (27).Human-derived MARVs (isolates Angola, Musoke, Ravn, and Ci67) do not kill immunocompetent adult mice (23). Furthermore, there are no published reports of any lethal mouse-adapted MARV. The current mouse-adapted EBOV, strain Zaire (ZEBOV), was developed by performing nine sequential passages of ZEBOV 1976 virus in suckling mice, followed by two sequential plaque picks. The resulting virus was uniformly lethal to mice inoculated intraperitoneally (i.p.). Pathological evaluation of infected mice identified many similarities and only a few differences between this model (7, 22) and infections in nonhuman primates (21).In a previous study, we took a slightly different approach to mouse adaptation of MARV and found that serially passaging virus recovered from the liver homogenates of MARV-Ravn-infected adult mice with severe combined immunodeficiency (SCID mice) resulted in the generation of SCID-adapted MARV-Ravn (scid-MARV) that rapidly killed SCID mice but did not kill adult immunocompetent mice (51). In this study, we used scid-MARV as starting material for the first round of infection of adult immunocompetent BALB/c mice and serially passaged virus recovered from the liver homogenates of the BALB/c mice. MARV-Ravn was chosen over SCID-adapted MARV-Ci67 or -Musoke because it adapted more rapidly to SCID mice than the other isolates did. This produced a mouse-adapted MARV-Ravn strain (ma-MARV) that could kill adult BALB/c mice. Serial sampling studies to characterize the pathogenesis of ma-MARV revealed that this model was very similar to the guinea pig and nonhuman primate Marburg hemorrhagic fever (MHF) models, including rapid viremia, induction of D-dimers (fibrin degradation products), thrombocytopenia, profound loss of circulating and tissue lymphocytes, and marked liver damage. Additionally, we compared the immunological responses of mice after infection with either nonadapted wild-type MARV-Ravn (wt-MARV) or ma-MARV. This mouse model of MARV infection not only should advance our understanding of MARV pathogenesis and immunity but also may play a critical role in discovery of therapeutics for MARV infection.