Carbon flux from decomposing wood and its dependency on temperature,wood N2 fixation rate,moisture and fungal composition in a Norway spruce forest

Globally 40–70 Pg of carbon (C) are stored in coarse woody debris on the forest floor. Climate change may reduce the function of this stock as a C sink in the future due to increasing temperature. However, current knowledge on the drivers of wood decomposition is inadequate for detailed predictions. To define the factors that control wood respiration rate of Norway spruce and to produce a model that adequately describes the decomposition process of this species as a function of time, we used an unprecedentedly diverse analytical approach, which included measurements of respiration, fungal community sequencing, N₂ fixation rate, nifH copy number, ¹⁴C‐dating as well as N%, δ¹³C and C% values of wood. Our results suggest that climate change will accelerate C flux from deadwood in boreal conditions, due to the observed strong temperature dependency of deadwood respiration. At the research site, the annual C flux from deadwood would increase by 27% from the current 117 g C/kg wood with the projected climate warming (RCP4.5). The second most important control on respiration rate was the stage of wood decomposition; at early stages of decomposition low nitrogen content and low wood moisture limited fungal activity while reduced wood resource quality decreased the respiration rate at the final stages of decomposition. Wood decomposition process was best described by a Sigmoidal model, where after 116 years of wood decomposition mass loss of 95% was reached. Our results on deadwood decomposition are important for C budget calculations in ecosystem and climate change models. We observed for the first time that the temperature dependency of N₂ fixation, which has a major role at providing N for wood‐inhabiting fungi, was not constant but varied between wood density classes due to source supply and wood quality. This has significant consequences on projecting N₂ fixation rates for deadwood in changing climate.     

Snx14 Regulates Neuronal Excitability,Promotes Synaptic Transmission,and Is Imprinted in the Brain of Mice

Genomic imprinting describes an epigenetic process through which genes can be expressed in a parent-of-origin-specific manner. The monoallelic expression of imprinted genes renders them particularly susceptible to disease causing mutations. A large proportion of imprinted genes are expressed in the brain, but little is known about their functions. Indeed, it has proven difficult to identify cell type-specific imprinted genes due to the heterogeneity of cell types within the brain. Here we used laser capture microdissection of visual cortical neurons and found evidence that sorting nexin 14 (Snx14) is a neuronally imprinted gene in mice. SNX14 protein levels are high in the brain and progressively increase during neuronal development and maturation. Snx14 knockdown reduces intrinsic excitability and severely impairs both excitatory and inhibitory synaptic transmission. These data reveal a role for monoallelic Snx14 expression in maintaining normal neuronal excitability and synaptic transmission.     

The Effect of Therapy Dogs on Exam Stress and Memory

Therapy dogs have been shown in many different situations to reduce stress and improve outcomes, but their effects on academic performance are unknown. I hypothesized that interaction with therapy dogs prior to exams would reduce stress in students and improve exam scores. In study 1, participants who chose to interact with the therapy dogs showed a significantly larger stress decrease and scored 5.5 points higher on their final exam than those who did not interact. In study 2, investigating memory retrieval, participants assigned to interact with therapy dogs immediately prior to their final exam showed a marginally larger stress reduction, but no difference in exam score, compared with those who watched a movie about dogs. To investigate memory consolidation, in study 3, participants were assigned to interact with therapy dogs or watch a movie immediately after learning some material. A significant interaction between condition and exam question type suggests that, compared with those who watched a movie about dogs, interacting with therapy dogs impaired memory for material learned just prior to the manipulation, but enhanced memory for material encountered at other times. Overall, interaction with therapy dogs appears to reduce stress, but had no effect on memory retrieval in study 2, and differentially affected memory consolidation of associated material in study 3.     

Fire effects on the vital rates and stochastic population growth rate of the rare shrub Lindera subcoriacea Wofford

Plant Ecology - Understanding demographic vital rates and the factors that affect those rates are key components of successful conservation strategies for many threatened and endangered rare plant...     

MicroRNA 224 Regulates Ion Transporter Expression in Ameloblasts To Coordinate Enamel Mineralization

Enamel mineralization is accompanied by the release of protons into the extracellular matrix, which is buffered to regulate the pH value in the local microenvironment. The present study aimed to investigate the role of microRNA 224 (miR-224) as a regulator of SLC4A4 and CFTR, encoding the key buffering ion transporters, in modulating enamel mineralization. miR-224 was significantly downregulated as ameloblasts differentiated, in parallel with upregulation of SLC4A4 and CFTR. Overexpression of miR-224 downregulated SLC4A4 and CFTR expression in cultured human epithelial cells. A microRNA luciferase assay confirmed the specific binding of miR-224 to the 3′ untranslated regions (UTRs) of SLC4A4 and CFTR mRNAs, thereby inhibiting protein translation. miR-224 agomir injection in mouse neonatal incisors resulted in normal enamel length and thickness, but with disturbed organization of the prism structure and deficient crystal growth. Moreover, the enamel Ca/P ratio and microhardness were markedly reduced after miR-224 agomir administration. These results demonstrate that miR-224 plays a pivotal role in fine tuning enamel mineralization by modulating SLC4A4 and CFTR to maintain pH homeostasis and support enamel mineralization.     

α-Poly-l-lysine functions as an adipogenic inducer in 3T3-L1 preadipocytes

α-Poly-l-lysine (PLL) has been used for various purposes such as cell attachment, immunization, and molecular delivery, and is known to be cytotoxic to several cell lines. Here, we studied the effect of PLL on the adipogenesis of 3T3-L1 cells and investigated the underlying mechanism. Differentiation media containing PLL with a molecular weight (MW) greater than 4 kDa enhanced lipid droplet formation and increased adipogenic marker levels, indicating an increase in adipocyte differentiation. PLL with a molecular weight between 30 and 70 kDa was more effective than PLL of other sizes in 3T3-L1 cell differentiation. Moreover, PLL induced 3T3-L1 adipogenesis in insulin-free adipocyte differentiation medium. Incubation with insulin and PLL exhibited greater adipogenesis than insulin treatment only even at a high concentration. PLL stimulated insulin signaling and augmented the signaling pathway when it was added with insulin. While PLL did not activate the glucocorticoid receptor, which is phosphorylated by dexamethasone (DEX), it showed a positive effect on the cAMP signal pathway when preadipocytes were treated with PLL and 3-isobutyl-1-methylxanthine (IBMX). Consistent with these results, incubation with PLL and DEX without IBMX induced adipocyte differentiation. We also observed that the mitotic clonal expansion phase was the critical stage in adipogenesis for inducing the effects of PLL. These results suggest that PLL functions as an adipogenic inducer in 3T3-L1 preadipocytes and PLL has a direct effect on insulin signaling, one of the main regulatory pathways.

     

Conservation genomics of desert dwelling California voles (<Emphasis Type="Italic">Microtus californicus</Emphasis>) and implications for management of endangered Amargosa voles (<Emphasis Type="Italic">Microtus californicus scirpensis</Emphasis>)

Understanding population genetic structure and levels of genetic variation is critical for the conservation and management of imperiled populations, especially when reintroductions are planned. We used restriction-site associated DNA (RAD) sequencing to study the genetic diversity and evolutionary relationships of the endangered Amargosa vole and other closely related desert-dwelling California voles. Specifically, we sought to determine how Amargosa voles are related to other California voles, how genetic variation is partitioned among subpopulations in wild Amargosa voles, and how much genetic variation is captured within a captive insurance colony of Amargosa voles. Our multilocus nuclear dataset provides strong evidence that Amargosa voles are part of a northern clade of California voles. Amargosa voles have highly reduced genetic variation relative to other California voles, but do exhibit some sub-structure among sampled marshes. Captive Amargosa voles capture approximately half of the total genetic variation present in the wild Amargosa vole populations. We discuss the management implications of our findings in light of reintroductions planned for Amargosa voles. Our study highlights the utility of reduced representation genomic approaches, like RADseq, to resolve relationships among small populations that are difficult to study with traditional markers due to low genetic variation and few individuals left in the wild.