Biochar-Induced Changes in Soil Hydraulic Conductivity and Dissolved Nutrient Fluxes Constrained by Laboratory Experiments

The addition of charcoal (or biochar) to soil has significant carbon sequestration and agronomic potential, making it important to determine how this potentially large anthropogenic carbon influx will alter ecosystem functions. We used column experiments to quantify how hydrologic and nutrient-retention characteristics of three soil materials differed with biochar amendment. We compared three homogeneous soil materials (sand, organic-rich topsoil, and clay-rich Hapludert) to provide a basic understanding of biochar-soil-water interactions. On average, biochar amendment decreased saturated hydraulic conductivity (K) by 92% in sand and 67% in organic soil, but increased K by 328% in clay-rich soil. The change in K for sand was not predicted by the accompanying physical changes to the soil mixture; the sand-biochar mixture was less dense and more porous than sand without biochar. We propose two hydrologic pathways that are potential drivers for this behavior: one through the interstitial biochar-sand space and a second through pores within the biochar grains themselves. This second pathway adds to the porosity of the soil mixture; however, it likely does not add to the effective soil K due to its tortuosity and smaller pore size. Therefore, the addition of biochar can increase or decrease soil drainage, and suggests that any potential improvement of water delivery to plants is dependent on soil type, biochar amendment rate, and biochar properties. Changes in dissolved carbon (C) and nitrogen (N) fluxes also differed; with biochar increasing the C flux from organic-poor sand, decreasing it from organic-rich soils, and retaining small amounts of soil-derived N. The aromaticity of C lost from sand and clay increased, suggesting lost C was biochar-derived; though the loss accounts for only 0.05% of added biochar-C. Thus, the direction and magnitude of hydraulic, C, and N changes associated with biochar amendments are soil type (composition and particle size) dependent.     

A Pathogenic Mosaic TP53 Mutation in Two Germ Layers Detected by Next Generation Sequencing

Background

Li-Fraumeni syndrome is caused by germline TP53 mutations and is clinically characterized by a predisposition to a range of cancers, most commonly sarcoma, brain tumours and leukemia. Pathogenic mosaic TP53 mutations have only rarely been described.

Methods and Findings

We describe a 2 years old child presenting with three separate cancers over a 6 month period; two soft tissue mesenchymal tumors and an aggressive metastatic neuroblastoma. As conventional testing of blood DNA by Sanger sequencing for mutations in TP53, ALK, and SDH was negative, whole exome sequencing of the blood DNA of the patient and both parents was performed to screen more widely for cancer predisposing mutations. In the patient''s but not the parents'' DNA we found a c.743 G>A, p.Arg248Gln (CCDS11118.1) TP53 mutation in 3–20% of sequencing reads, a level that would not generally be detectable by Sanger sequencing. Homozygosity for this mutation was detected in all tumor samples analyzed, and germline mosaicism was demonstrated by analysis of the child''s newborn blood spot DNA. The occurrence of separate tumors derived from different germ layers suggests that this de novo mutation occurred early in embryogenesis, prior to gastrulation.

Conclusion

The case demonstrates pathogenic mosaicim, detected by next generation deep sequencing, that arose in the early stages of embryogenesis.     

Development of a transformation system in the swainsonine producing, slow growing endophytic fungus, Undifilum oxytropis

Undifilum oxytropis (Phylum: Ascomycota; Family: Pleosporaceae) is a slow growing endophytic fungus that produces a toxic alkaloid, swainsonine. This endophyte resides in locoweeds, which are perennial flowering legumes. Consumption of this fungus by grazing animals induces a neurological disorder called locoism. The alkaloid swainsonine, an α-mannosidase inhibitor, is responsible for the field toxicity related to locoism. Little is known about the biosynthetic pathway of swainsonine in endophytic fungi. Genetic manipulation of endophytic fungi is important to better understand biochemical pathways involved in alkaloid synthesis, but no transformation system has been available for studying such enzymes in Undifilum. In this study we report the development of protoplast and transformation system for U. oxytropis. Fungal mycelia required for generating protoplasts were grown in liquid culture, then harvested and processed with various enzymes. Protoplasts were transformed with a fungal specific vector driving the expression of Enhanced Green Florescent Protein (EGFP). The quality of transformed protoplasts and transformation efficiency were monitored during the process. In all cases, resistance to antibiotic hygromycin B was maintained. Such manipulation will open avenues for future research to decipher fungal metabolic pathways.     

Masters of miniaturization: Convergent evolution among interstitial eukaryotes

Marine interstitial environments are teeming with an extraordinary diversity of coexisting microeukaryotic lineages collectively called “meiofauna.” Interstitial habitats are broadly distributed across the planet, and the complex physical features of these environments have persisted, much like they exist today, throughout the history of eukaryotes, if not longer. Although our general understanding of the biological diversity in these environments is relatively poor, compelling examples of developmental heterochrony (e.g., pedomorphosis) and convergent evolution appear to be widespread among meiofauna. Therefore, an improved understanding of meiofaunal biodiversity is expected to provide some of the deepest insights into the following themes in evolutionary biology: (i) the origins of novel body plans, (ii) macroevolutionary patterns of miniaturization, and (iii) the intersection of evolution and community assembly – e.g., “community convergence” involving distantly related lineages that span the tree of eukaryotes.     

Predicting impaired extinction of traumatic memory and elevated startle

Background

Emotionally traumatic experiences can lead to debilitating anxiety disorders, such as phobias and Post-Traumatic Stress Disorder (PTSD). Exposure to such experiences, however, is not sufficient to induce pathology, as only up to one quarter of people exposed to such events develop PTSD. These statistics, combined with findings that smaller hippocampal size prior to the trauma is associated with higher risk of developing PTSD, suggest that there are pre-disposing factors for such pathology. Because prospective studies in humans are limited and costly, investigating such pre-dispositions, and thus advancing understanding of the genesis of such pathologies, requires the use of animal models where predispositions are identified before the emotional trauma. Most existing animal models are retrospective: they classify subjects as those with or without a PTSD-like phenotype long after experiencing a traumatic event. Attempts to create prospective animal models have been largely unsuccessful.

Methodology/Principal Findings

Here we report that individual predispositions to a PTSD-like phenotype, consisting of impaired rate and magnitude of extinction of an emotionally traumatic event coupled with long-lasting elevation of acoustic startle responses, can be revealed following exposure to a mild stressor, but before experiencing emotional trauma. We compare, in rats, the utility of several classification criteria and report that a combination of criteria based on acoustic startle responses and behavior in an anxiogenic environment is a reliable predictor of a PTSD-like phenotype.

Conclusions/Significance

There are individual predispositions to developing impaired extinction and elevated acoustic startle that can be identified after exposure to a mildly stressful event, which by itself does not induce such a behavioral phenotype. The model presented here is a valuable tool for studying the etiology and pathophysiology of anxiety disorders and provides a platform for testing behavioral and pharmacological interventions that can reduce the probability of developing pathologic behaviors associated with such disorders.     

Recovery of time on limits of stability from functional fatigue in Division II collegiate athletes

Health and fitness professionals working with athletes could establish effective and safe practice and training programs if recovery time on dynamic balance from exertion was available. Research investigating the time needed to recover dynamic limits of stability (LOS) from exertion has not been reported. The purpose of this study was to determine the recovery timeline on LOS from functional fatigue in collegiate athletes. Eighteen athletes (11 men, 7 women) from Division II collegiate soccer team who passed prescreening tests to identify their fitness levels were randomly tested on 2 different days by condition (fatigue or nonfatigue). Functional fatigue was determined by using the Borg 15-point rating of perceived exertion (RPE) scale. Subjects were tested on LOS on the Biodex Balance System pre, post, 10, 15, and 20 minutes for each condition. The main effect for condition was not significant (F() = 0.004, p = 0.948), whereas the main effect for time was significant (F(4,64) = 6.167, p < 0.001). The RPE scoring revealed the significant main effect in FATIGUE (F(2.69, 45.73) = 234.8, p < 0.001). In conclusion, 20 minutes of functional activity will likely have a negative influence on dynamic balance, with balance recovery occurring within 10 minutes after the cessation of exercise in Division II collegiate soccer athletes. Moreover, the level of exertion measured by RPE would correspond to athletes' ability to control their center of mass.     

Are there indirect fitness benefits of female extra-pair reproduction? Lifetime reproductive success of within-pair and extra-pair offspring

The forces driving extra-pair reproduction by socially monogamous females, and the resulting genetic polyandry, remain unclear. A testable prediction of the hypothesis that extra-pair reproduction partly reflects indirect selection on females is that extra-pair young (EPY) will be fitter than their within-pair young (WPY) maternal half-siblings. This prediction has not been comprehensively tested in a wild population, requiring data on the lifetime reproductive success (LRS) of maternal half-sib EPY and WPY. We used 17 years of genetic parentage data from song sparrows, Melospiza melodia, to compare the LRS of hatched EPY and WPY maternal half-siblings measured as their lifetime number of hatched offspring, recruited offspring, and hatched grandoffspring. EPY hatchlings were not significantly fitter than WPY hatchlings for any of three measures of LRS. Furthermore, opposite to prediction, EPY hatchlings tended to have lower LRS than their maternal half-sibling WPY hatchlings on average. EPY also tended to be less likely to survive to hatch than their maternal half-sibling WPY. Taken together, these results fail to support one key hypothesis explaining the evolution of genetic polyandry by socially monogamous females and suggest there may be weak indirect selection against female extra-pair reproduction in song sparrows.     

HNF1B and endometrial cancer risk: results from the PAGE study

We examined the association between HNF1B variants identified in a recent genome-wide association study and endometrial cancer in two large case-control studies nested in prospective cohorts: the Multiethnic Cohort Study (MEC) and the Women's Health Initiative (WHI) as part of the Population Architecture using Genomics and Epidemiology (PAGE) study. A total of 1,357 incident cases of invasive endometrial cancer and 7,609 controls were included in the analysis (MEC: 426 cases/3,854 controls; WHI: 931 cases/3,755 controls). The majority of women in the WHI were European American, while the MEC included sizable numbers of African Americans, Japanese and Latinos. We estimated the odds ratios (ORs) per allele and 95% confidence intervals (CIs) of each SNP using unconditional logistic regression adjusting for age, body mass index, and four principal components of ancestry informative markers. The combined ORs were estimated using fixed effect models. Rs4430796 and rs7501939 were associated with endometrial cancer risk in MEC and WHI with no heterogeneity observed across racial/ethnic groups (P ≥ 0.21) or between studies (P ≥ 0.70). The OR(per allele) was 0.82 (95% CI: 0.75, 0.89; P = 5.63 × 10(-6)) for rs4430796 (G allele) and 0.79 (95% CI: 0.73, 0.87; P = 3.77 × 10(-7)) for rs7501939 (A allele). The associations with the risk of Type I and Type II tumors were similar (P ≥ 0.19). Adjustment for additional endometrial cancer risk factors such as parity, oral contraceptive use, menopausal hormone use, and smoking status had little effect on the results. In conclusion, HNF1B SNPs are associated with risk of endometrial cancer and that the associated relative risks are similar for Type I and Type II tumors.