Robust ecological drought projections for drylands in the 21st century

Dryland ecosystems may be especially vulnerable to expected 21st century increases in temperature and aridity because they are tightly controlled by moisture availability. However, climate impact assessments in drylands are difficult because ecological dynamics are dictated by drought conditions that are difficult to define and complex to estimate from climate conditions alone. In addition, precipitation projections vary substantially among climate models, enhancing variation in overall trajectories for aridity. Here, we constrain this uncertainty by utilizing an ecosystem water balance model to quantify drought conditions with recognized ecological importance, and by identifying changes in ecological drought conditions that are robust among climate models, defined here as when >90% of models agree in the direction of change. Despite limited evidence for robust changes in precipitation, changes in ecological drought are robust over large portions of drylands in the United States and Canada. Our results suggest strong regional differences in long‐term drought trajectories, epitomized by chronic drought increases in southern areas, notably the Upper Gila Mountains and South‐Central Semi‐arid Prairies, and decreases in the north, particularly portions of the Temperate and West‐Central Semi‐arid Prairies. However, we also found that exposure to hot‐dry stress is increasing faster than mean annual temperature over most of these drylands, and those increases are greatest in northern areas. Robust shifts in seasonal drought are most apparent during the cool season; when soil water availability is projected to increase in northern regions and decrease in southern regions. The implications of these robust drought trajectories for ecosystems will vary geographically, and these results provide useful insights about the impact of climate change on these dryland ecosystems. More broadly, this approach of identifying robust changes in ecological drought may be useful for other assessments of climate impacts in drylands and provide a more rigorous foundation for making long‐term strategic resource management decisions.     

Systematics of a widely distributed western North American springsnail,Pyrgulopsis?micrococcus (Caenogastropoda,Hydrobiidae), with descriptions?of?three new congeners

We describe three new species of springsnails (genus Pyrgulopsis) from the Amargosa River basin, California and Nevada (P. licina sp. n., P. perforata sp. n., P. sanchezi sp. n.), each of which was previously considered to be part of P. micrococcus. We also restrict P. micrococcus to its type locality area (Oasis Valley) and redefine a regional congener, P. turbatrix, to include populations from the central Death Valley region and San Bernardino Mountains that had been previously identified as P. micrococcus. The five species treated herein form genetically distinct lineages that differ from each other by 4.2–12.6% for mtCOI and 5.2–13.6% for mtNDI (based on previously published and newly obtained data), and are diagnosable by shell and/or penial characters. The new molecular data presented herein confirm sympatry of P. licina and P. sanchezi in Ash Meadows (consistent with morphological evidence) and delineate an additional lineage of P. micrococcus (in the broad sense) that we do not treat taxonomically owing to the paucity of morphological material. Conservation measures are needed to ensure the long term persistence of populations of P. micrococcus and a genetically differentiated lineage of P. sanchezi which live in disturbed habitats on private lands.     

TNFα Altered Inflammatory Responses,Impaired Health and Productivity,but Did Not Affect Glucose or Lipid Metabolism in Early-Lactation Dairy Cows

Inflammation may be a major contributing factor to peripartum metabolic disorders in dairy cattle. We tested whether administering an inflammatory cytokine, recombinant bovine tumor necrosis factor-α (rbTNFα), affects milk production, metabolism, and health during this period. Thirty-three Holstein cows (9 primiparous and 24 multiparous) were randomly assigned to 1 of 3 treatments at parturition. Treatments were 0 (Control), 1.5, or 3.0 µg/kg body weight rbTNFα, which were administered once daily by subcutaneous injection for the first 7 days of lactation. Statistical contrasts were used to evaluate the treatment and dose effects of rbTNFα administration. Plasma TNFα concentrations at 16 h post-administration tended to be increased (P<0.10) by rbTNFα administration, but no dose effect (P>0.10) was detected; rbTNFα treatments increased (P<0.01) concentrations of plasma haptoglobin. Most plasma eicosanoids were not affected (P>0.10) by rbTNFα administration, but 6 out of 16 measured eicosanoids changed (P<0.05) over the first week of lactation, reflecting elevated inflammatory mediators in the days immediately following parturition. Dry matter and water intake, milk yield, and milk fat and protein yields were all decreased (P<0.05) by rbTNFα treatments by 15 to 18%. Concentrations of plasma glucose, insulin, β-hydroxybutyrate, non-esterified fatty acids, triglyceride, 3-methylhistidine, and liver triglyceride were unaffected (P>0.10) by rbTNFα treatment. Glucose turnover rate was unaffected (P = 0.18) by rbTNFα administration. The higher dose of rbTNFα tended to increase the risk of cows developing one or more health disorders (P = 0.08). Taken together, these results indicate that administration of rbTNFα daily for the first 7 days of lactation altered inflammatory responses, impaired milk production and health, but did not significantly affect liver triglyceride accumulation or nutrient metabolism in dairy cows.     

Ecosystem-Service Tradeoffs Associated with Switching from Annual to Perennial Energy Crops in Riparian Zones of the US Midwest

Integration of energy crops into agricultural landscapes could promote sustainability if they are placed in ways that foster multiple ecosystem services and mitigate ecosystem disservices from existing crops. We conducted a modeling study to investigate how replacing annual energy crops with perennial energy crops along Wisconsin waterways could affect a variety of provisioning and regulating ecosystem services. We found that a switch from continuous corn production to perennial-grass production decreased annual income provisioning by 75%, although it increased annual energy provisioning by 33%, decreased annual phosphorous loading to surface water by 29%, increased below-ground carbon sequestration by 30%, decreased annual nitrous oxide emissions by 84%, increased an index of pollinator abundance by an average of 11%, and increased an index of biocontrol potential by an average of 6%. We expressed the tradeoffs between income provisioning and other ecosystem services as benefit-cost ratios. Benefit-cost ratios averaged 12.06 GJ of additional net energy, 0.84 kg of avoided phosphorus pollution, 18.97 Mg of sequestered carbon, and 1.99 kg of avoided nitrous oxide emissions for every $1,000 reduction in income. These ratios varied spatially, from 2- to 70-fold depending on the ecosystem service. Benefit-cost ratios for different ecosystem services were generally correlated within watersheds, suggesting the presence of hotspots – watersheds where increases in multiple ecosystem services would come at lower-than-average opportunity costs. When assessing the monetary value of ecosystem services relative to existing conservation programs and environmental markets, the overall value of enhanced services associated with adoption of perennial energy crops was far lower than the opportunity cost. However, when we monitized services using estimates for the social costs of pollution, the value of enhanced services far exceeded the opportunity cost. This disparity between recoverable costs and social value represents a fundamental challenge to expansion of perennial energy crops and sustainable agricultural landscapes.     

Placental Syncytium Forms a Biophysical Barrier against Pathogen Invasion

Fetal syncytiotrophoblasts form a unique fused multinuclear surface that is bathed in maternal blood, and constitutes the main interface between fetus and mother. Syncytiotrophoblasts are exposed to pathogens circulating in maternal blood, and appear to have unique resistance mechanisms against microbial invasion. These are due in part to the lack of intercellular junctions and their receptors, the Achilles heel of polarized mononuclear epithelia. However, the syncytium is immune to receptor-independent invasion as well, suggesting additional general defense mechanisms against infection. The difficulty of maintaining and manipulating primary human syncytiotrophoblasts in culture makes it challenging to investigate the cellular and molecular basis of host defenses in this unique tissue. Here we present a novel system to study placental pathogenesis using murine trophoblast stem cells (mTSC) that can be differentiated into syncytiotrophoblasts and recapitulate human placental syncytium. Consistent with previous results in primary human organ cultures, murine syncytiotrophoblasts were found to be resistant to infection with Listeria monocytogenes via direct invasion and cell-to-cell spread. Atomic force microscopy of murine syncytiotrophoblasts demonstrated that these cells have a greater elastic modulus than mononuclear trophoblasts. Disruption of the unusually dense actin structure – a diffuse meshwork of microfilaments - with Cytochalasin D led to a decrease in its elastic modulus by 25%. This correlated with a small but significant increase in invasion of L. monocytogenes into murine and human syncytium. These results suggest that the syncytial actin cytoskeleton may form a general barrier against pathogen entry in humans and mice. Moreover, murine TSCs are a genetically tractable model system for the investigation of specific pathways in syncytial host defenses.     

Method for Quantitative Study of Airway Functional Microanatomy Using Micro-Optical Coherence Tomography

We demonstrate the use of a high resolution form of optical coherence tomography, termed micro-OCT (μOCT), for investigating the functional microanatomy of airway epithelia. μOCT captures several key parameters governing the function of the airway surface (airway surface liquid depth, periciliary liquid depth, ciliary function including beat frequency, and mucociliary transport rate) from the same series of images and without exogenous particles or labels, enabling non-invasive study of dynamic phenomena. Additionally, the high resolution of μOCT reveals distinguishable phases of the ciliary stroke pattern and glandular extrusion. Images and functional measurements from primary human bronchial epithelial cell cultures and excised tissue are presented and compared with measurements using existing gold standard methods. Active secretion from mucus glands in tissue, a key parameter of epithelial function, was also observed and quantified.     

Inhibition of mTOR Reduces Anal Carcinogenesis in Transgenic Mouse Model

The molecular mechanism of human anal squamous cell carcinoma (ASCC) is unclear, and the accumulating evidence indicate association of ASCC with the activation of the Akt/mTOR pathway. Here we describe a mouse model with spontaneous anal squamous cell cancer, wherein a combined deletion of Tgfbr1 and Pten in stratified squamous epithelia was induced using inducible K14-Cre. Histopathologic analyses confirmed that 33.3% of the mice showed increased susceptibility to ASCC and precancerous lesions. Biomarker analyses demonstrated that the activation of the Akt pathway in ASCC of the Tgfbr1 and Pten double knockout (2cKO) mouse was similar to that observed in human anal cancer. Chemopreventive experiments using mTOR inhibitor-rapamycin treatment significantly delayed the onset of the ASCC tumors and reduced the tumor burden in 2cKO mice by decreasing the phosphorylation of Akt and S6. This is the first conditional knockout mouse model used for investigating the contributions of viral and cellular factors in anal carcinogenesis without carcinogen-mediated induction, and it would provide a platform for assessing new therapeutic modalities for treating and/or preventing this type of cancer.     

Decoupling litter barrier and soil moisture influences on the establishment of an invasive grass

Background and aims

Through recruitment, plants establish in novel environments. Recruitment also is the stage where plants undergo the highest mortality. We investigate the recruitment niche for Microstegium vimineum, an annual grass from East Asia spreading throughout eastern North American forests.

Methods

Current observational and greenhouse research indicates that M. vimineum recruitment may be inhibited by leaf litter and promoted by soil moisture; we use field studies to experimentally test how these factors influence M. vimineum germination, seedling survival and reproduction. Specifically, we introduce M. vimineum seeds into forest microhabitats with experimentally varied levels of soil moisture and leaf litter.

Results

Soil moisture increases M. vimineum germination regardless of leaf litter thickness and ameliorates seedling mortality in deep leaf litter. Seed production per m² increases with watering, reflecting higher germination and survival, whereas per capita seed production increases with leaf litter thickness, reflecting density-dependent limits on seed production.

Conclusions

The interactive effects of varied levels of soil moisture and leaf litter thickness on key M. vimineum life history stages highlight the need to consider multiple drivers, such as rainfall and local forest disturbance, when assessing how soil properties influence the establishment of invasive plants.     

Transforming Growth Factor-β3 (TGF-β3) Knock-in Ameliorates Inflammation Due to TGF-β1 Deficiency While Promoting Glucose Tolerance

Three homologues of TGF-β exist in mammals as follows: TGF-β1, TGF-β2, and TGF-β3. All three proteins share high homology in their amino acid sequence, yet each TGF-β isoform has unique heterologous motifs that are highly conserved during evolution. Although these TGF-β proteins share similar properties in vitro, isoform-specific properties have been suggested through in vivo studies and by the unique phenotypes for each TGF-β knock-out mouse. To test our hypothesis that each of these homologues has nonredundant functions, and to identify such isoform-specific roles, we genetically exchanged the coding sequence of the mature TGF-β1 ligand with a sequence from TGF-β3 using targeted recombination to create chimeric TGF-β1/3 knock-in mice (TGF-β1^Lβ3/Lβ3). In the TGF-β1^Lβ3/Lβ3 mouse, localization and activation still occur through the TGF-β1 latent associated peptide, but cell signaling is triggered through the TGF-β3 ligand that binds to TGF-β receptors. Unlike TGF-β1^−/− mice, the TGF-β1^Lβ3/Lβ3 mice show neither embryonic lethality nor signs of multifocal inflammation, demonstrating that knock-in of the TGF-β3 ligand can prevent the vasculogenesis defects and autoimmunity associated with TGF-β1 deficiency. However, the TGF-β1^Lβ3/Lβ3 mice have a shortened life span and display tooth and bone defects, indicating that the TGF-β homologues are not completely interchangeable. Remarkably, the TGF-β1^Lβ3/Lβ3 mice display an improved metabolic phenotype with reduced body weight gain and enhanced glucose tolerance by induction of beneficial changes to the white adipose tissue compartment. These findings reveal both redundant and unique nonoverlapping functional diversity in TGF-β isoform signaling that has relevance to the design of therapeutics aimed at targeting the TGF-β pathway in human disease.     

Predicting the timing of maturational spurts in skeletal age

Measures of maturity provide windows into the timing and tempo of childhood growth and maturation. Delayed maturation in a single child, or systemically in a population, can result from either genetic or environmental factors. In terms of the skeleton, delayed maturation may result in short stature or indicate another underlying issue. Thus, prediction of the timing of a maturational spurt is often desirable in order to determine the likelihood that a child will catch up to their chronological age peers. Serial data from the Fels Longitudinal Study were used to predict future skeletal age conditional on current skeletal age and to predict the timing of maturational spurts. For children who were delayed relative to their chronological age peers, the likelihood of catch‐up maturation increased through the average age of onset of puberty and decreased prior to the average age of peak height velocity. For boys, the probability of an imminent maturational spurt was higher for those who were less mature. For girls aged 11 to 13 years, however, this probability was higher for those who were more mature, potentially indicating the presence of a skeletal maturation plateau between multiple spurts. The prediction model, available on the web, is most relevant to children of European ancestry living in the Midwestern US. Our model may also provide insight into the tempo of maturation for children in other populations, but must be applied with caution if those populations are known to have high burdens of environmental stressors not typical of the Midwestern US. Am J Phys Anthropol, 2013. © 2012 Wiley Periodicals, Inc.