2,359 research outputs found

    Invasion is Contingent on Species Assemblage and Invasive Species Identity inExperimental Rehabilitation Plots

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    Ecological studies often suggest that diverse communities are most resistant to invasion by exotic plants, but relatively few local species may be available to a rehabilitation practitioner. We examine the ability of monocultures and diverse assemblages to resist invasion by an exotic annual grass (cheatgrass) and an exotic biennial forb (dyer’s woad) in experimental rehabilitation plots. We constructed seven assemblages that included three monocultures of grass, forb, or shrub; three four-species mixtures of grasses, forbs, or shrubs; and a three-species mixture of one species from each growth form in an experimental field setting to test resistance to invasion. Assemblages were seeded with cheatgrass and dyer’s woad for two consecutive years and quantified as biomass and density of individuals from each exotic species. Soil NO3 and leaf-area index were examined as predictors of invasive plant abundance. Cheatgrass invasion was greatest in forb and shrub assemblages, and least in mixed grass or grass monoculture; dyer’s woad invasion was greatest into mixed grass or grass monoculture, but least into monoculture or mixedspecies assemblages composed of forbs or shrubs. The community composed of grasses, forbs, and shrubs suppressed invasion by both species. Consequently, assemblages were most resistant to invasion by species of the same growth form. Moreover, these monocultures and mixtures were generally similar in conferring resistance to invasion, but a monoculture of big sagebrush was more resistant than a mixture of shrubs. Soil NO3 was correlated with invasion by cheatgrass, whereas LAI was correlated with invasion by dyer’s woad, suggesting these species were more limited by belowground and aboveground resources, respectively. Overall, increasing diversity with limited species did not necessarily enhance resistance to invasion

    Inclusion of a dithiadiazolyl radical in a seemingly non-porous solid

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    Inclusion of the dithiadiazolyl radical PhCNSSN• into the dynamically porous metallocycle [Cu2(L1)2Cl4], where L1 is the bidentate ligand 1,3-bis(imidazol-1-ylmethyl)-2,4,6- trimethylbenzene, has been achieved by gas phase diffusion. Single crystal X-ray diffraction, powder X-ray diffraction, UV-visible spectroscopy, EPR and SQUID magnetometry studies confirm inclusion of the radical into this seemingly non-porous material, and illustrate the presence of antiferromagnetic coupling between the paramagnetic host and guest species. The radical guest is readily released by heating or by the addition of solvent (CH2Cl2)

    Development of a Forage Evaluation System for Perennial Ryegrass Cultivar and Endophyte Combinations in New Zealand Dairy Systems

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    An economic index for perennial ryegrass (Lolium perenne L.) cultivars is a relatively new concept, although recently introduced in Ireland (McEvoy et al. 2011). By contrast, in dairy cattle breeding, the concept of an economic index rating animals and economic values underlying that index is well entrenched (Philipson et al. 1994; Veerkamp, 1998). Historically, forage evaluation data for individual cultivars were either displayed using absolute numbers for seasonal dry matter production within a season or across all seasons with a notation to indicate statistical differences, or percentage values where a reference cultivar is 100. The adoption of an economic index and routine evaluation approach for perennial ryegrass provides a method to identify traits of economic importance to focus plant breeding efforts better and to provide clarity for farmers around predicting cultivars that will maximise farm profit. It also allows for routine tracking of genetic gain of individual traits and the economic index. In this paper, the economic based forage evaluation techniques now used in New Zealand for perennial ryegrass cultivar/endophyte combinations are presented

    Discovery and Development of Human Monoclonal Antibodies to Block RhD Alloimmunization During Pregnancy

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    Exposure of an Rh negative mother to red blood cells (RBCs) of an Rh positive fetus results in alloimmunization and development of anti-RhD antibodies. The anti-RhD antibodies cause hemolytic disease of the new born babies during subsequent pregnancies. Current prophylactic treatment involves polyclonal anti-RhD IgG purified from plasma of humans and is administered in approximately 20% of pregnancies. While the current prophylaxis is effective, it involves the use of human plasma and non-RhD specific antibodies, thus posing a risk of transmitting infections and undesired antibody reactions. Moreover, there is a serious scarcity of plasma donors to meet the requirement of anti-RhD antibodies. In this study we propose to discover and develop anti-RhD monoclonal human antibodies to replace the current polyclonal prophylaxis. We are using humanized BLT mice (fetal CD34+ stem cells, liver and thymus) reconstituted with RhD negative donor material and were immunized by using adenovirus containing RhD transgene. Serum samples were collected after 4-6 weeks of immunization. Our results show that the RhD immunized mice had considerably higher titer of IgG and IgA antibodies in the serum compared to the control, suggesting an immune response developed upon immunization. Splenocytes from antibody producing mice will be fused with a human fusion partner for the isolation of hybridomas producing human monoclonal antibodies. The immunoreactivity and functional activity of these antibodies will be discussed

    Correlations between Hippocampal Neurogenesis and Metabolic Indices in Adult Nonhuman Primates

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    Increased neurogenesis in feeding centers of the murine hypothalamus is associated with weight loss in diet-induced obese rodents (Kokoeva et al., 2005 and Matrisciano et al., 2010), but this relationship has not been examined in other species. Postmortem hippocampal neurogenesis rates and premortem metabolic parameters were statistically analyzed in 8 chow-fed colony-reared adult bonnet macaques. Dentate gyrus neurogenesis, reflected by the immature neuronal marker, doublecortin (DCX), and expression of the antiapoptotic gene factor, B-cell lymphoma 2 (BCL-2), but not the precursor proliferation mitotic marker, Ki67, was inversely correlated with body weight and crown-rump length. DCX and BCL-2 each correlated positively with blood glucose level and lipid ratio (total cholesterol/high-density lipoprotein). This study demonstrates that markers of dentate gyrus neuroplasticity correlate with metabolic parameters in primates

    Humanized Mice for the Generation of HIV-1 Human Monoclonal Antibodies

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    Background: Despite the length of time HIV has been wreaking havoc on its victims, improvements in the prevention and treatment of HIV are needed. Anti-retroviral therapy can be effective but is expensive and not entirely accessible for people infected in third world countries. Several promising broadly neutralizing antibodies have been isolated from infected individuals; we propose that generating antigen specific human monoclonal antibodies using humanized mice further represents a promising approach to engineer prophylactic antibodies to reduce spread and infection of HIV. Methods: Immunodeficient mice were engrafted with fetal liver and thymus (BLT) prior to infection with different HIV isolates. HIV infection of the mice was monitored by viral load and antibody response followed by ELISA using gp120, gp41 or gp120/CD4 complex as antigens. Approximately 8-12 weeks post infection, spleens were harvested and splenocytes fused with human fusion partner HMMA 2.5 to isolate antibody-expressing hybridomas. Lead clones were scaled and purified for testing in functional assays such as TZM-bl neutralization assays as well as ADCVI to determine neutralizing and cytotoxic ability of the antibodies. Antibody sequences were also determined for analysis. Results: A robust, specific antibody response, of both IgG and IgA isotypes, was generated in response to HIV infection. Over 60 hybridomas were created that were not only immunoreactive with env antigens, but also had neutralization activity. Moreover, variable family usage was not limited and somatic mutation was clearly evident. Conclusions: These findings suggest that humanized BLT mice are a novel source for well-characterized, stable human monoclonal antibodies to HIV

    Respiratory Measures in Amyotrophic Lateral Sclerosis

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    Objective: Amyotrophic lateral sclerosis (ALS) is a progressive neuromuscular disease that causes skeletal muscle weakness, including muscles involved with respiration. Death often results from respiratory failure within 3€“5 years. Monitoring respiratory status is therefore critical to ALS management, as respiratory/pulmonary function tests (PFTs) are used to make decisions including when to initiate noninvasive ventilation. Understanding the different respiratory and PFTs as they relate to disease progression and survival may help determine which tests are most suitable. Methods: This review describes the tests used to assess respiratory muscle and pulmonary function in patients with ALS and the correlations between different respiratory measures and clinical outcomes measures. Results: The most commonly used measurement, forced vital capacity (VC), has been shown to correlate with clinical milestones including survival, but also requires good motor coordination and facial strength to form a tight seal around a mouthpiece. Other tests such as slow VC, sniff inspiratory pressure, or transdiaphragmatic pressure with magnetic stimulation are also associated with distinct advantages and disadvantages. Conclusions: Therefore, how and when to use different tests remains unclear. Understanding how each test relates to disease progression and survival may help determine which is best suited for specific clinical decisions

    An initial spatial conflict analysis for potential deep-sea mining of marine minerals in U.S. Federal Waters

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    Demand for critical minerals is projected to double or even triple by 2030 as the global energy and transportation sectors transition away from fossil fuels toward renewable energy. This anticipated demand raises interest in new critical mineral resources, including marine minerals, to supplement future supplies. While the environmental benefits of transitioning to green energy are many, there are inherent environmental costs. In this study, we compiled broad-scale datasets of prominent environmental features and human uses within four deep ocean regions of the U.S. Exclusive Economic Zone where marine minerals are predicted to occur, called prospective regions: they are the Blake Plateau, the Hawaiian Islands, Offshore California, and the Gulf of Alaska. We generated a normalized metric to score regions based on the co-occurrence of either environmental or human use variables within hexagonal grid cells, allowing us to assess the occurrence intensity and spatial patterns of environmental and/or human use variables within each region. Driven by the presence of threatened species and total species richness, the Blake Plateau and the Hawaiian Islands have the highest environmental occurrence scores, followed by Offshore California and the Gulf of Alaska. Offshore California is the busiest shipping region, followed by the Blake Plateau, the Gulf of Alaska and Hawaiian Islands, and subsea cables are densest in Offshore California, followed by Gulf of Alaska and Hawaiian Islands. The Gulf of Alaska has the largest reported fisheries landings. The sensitivities of biota and human uses to mining are highest for benthic or sessile species and infrastructure on or near ferromanganese crusts or manganese nodules that would be directly and physically altered through crust extraction or nodule removal. This study illustrates the usefulness of comprehensive, spatially explicit risk assessments to inform deep sea mining management and minimize ecological harm and human use conflicts. We assert that the relatively straightforward GIS-based methodology tested here can be applied and iterated upon elsewhere

    Transcriptome Atlases of Mouse Brain Reveals Differential Expression Across Brain Regions and Genetic Backgrounds

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    Mouse models play a crucial role in the study of human behavioral traits and diseases. Variation of gene expression in brain may play a critical role in behavioral phenotypes, and thus it is of great importance to understand regulation of transcription in mouse brain. In this study, we analyzed the role of two important factors influencing steady-state transcriptional variation in mouse brain. First we considered the effect of assessing whole brain vs. discrete regions of the brain. Second, we investigated the genetic basis of strain effects on gene expression. We examined the transcriptome of three brain regions using Affymetrix expression arrays: whole brain, forebrain, and hindbrain in adult mice from two common inbred strains (C57BL/6J vs. NOD/ShiLtJ) with eight replicates for each brain region and strain combination. We observed significant differences between the transcriptomes of forebrain and hindbrain. In contrast, the transcriptomes of whole brain and forebrain were very similar. Using 4.3 million single-nucleotide polymorphisms identified through whole-genome sequencing of C57BL/6J and NOD/ShiLtJ strains, we investigated the relationship between strain effect in gene expression and DNA sequence similarity. We found that cis-regulatory effects play an important role in gene expression differences between strains and that the cis-regulatory elements are more often located in 5′ and/or 3′ transcript boundaries, with no apparent preference on either 5′ or 3′ ends

    Maternal hypothalamic-pituitary-adrenal axis response to foraging uncertainty: A model of individual vs. social allostasis and the Superorganism Hypothesis

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    Introduction: Food insecurity is a major global contributor to developmental origins of adult disease. The allostatic load of maternal food uncertainty from variable foraging demand (VFD) activates corticotropin-releasing factor (CRF) without eliciting hypothalamic-pituitary-adrenal (HPA) activation measured on a group level. Individual homeostatic adaptations of the HPA axis may subserve second-order homeostasis, a process we provisionally term “social allostasis.” We postulate that maternal food insecurity induces a “superorganism” state through coordination of individual HPA axis response. Methods: Twenty-four socially-housed bonnet macaque maternal-infant dyads were exposed to 16 weeks of alternating two-week epochs of low or high foraging demand shown to compromise normative maternal-infant rearing. Cerebrospinal fluid (CSF) CRF concentrations and plasma cortisol were measured pre- and post-VFD. Dyadic distance was measured, and blinded observers performed pre-VFD social ranking assessments. Results: Despite marked individual cortisol responses (mean change = 20%) there was an absence of maternal HPA axis group mean response to VFD (0%). Whereas individual CSF CRF concentrations change = 56%, group mean did increase 25% (p = 0.002). Our dyadic vulnerability index (low infant weight, low maternal weight, subordinate maternal social status and reduced dyadic distance) predicted maternal cortisol decreases (p \u3c 0.0001) whereas relatively “advantaged” dyads exhibited maternal cortisol increases in response to VFD exposure. Comment: In response to a chronic stressor, relative dyadic vulnerability plays a significant role in determining the directionality and magnitude of individual maternal HPA axis responses in the service of maintaining a “superorganism” version of HPA axis homeostasis, provisionally termed “social allostasis.
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