Retention forestry as a climate solution: Assessing biomass, soil carbon and albedo impacts in a northern temperate coniferous forest.

Forest management pathways for nature-based climate solutions, such as variable retention harvesting (VRH), have been gaining traction in recent years; however, their net biochemical and biophysical impacts remain unknown. Here, we use a combination of close-range and satellite remote sensing, eddy covariance technique, and ground-based biometric measurements to investigate forest thinning density and aggregation that maintain ecosystem nutrients, enhance tree growth and provide a negative feedback to the local climate in a northern temperate coniferous forest stand in Ontario, Canada. Our results showed that soil carbon (C) and nitrogen (N) in VRH plots were significantly lower (p < 0.05) for all VRH treatments compared to unharvested plots. On average, soil C was reduced by -0.64 ± 0.22 Δ% C and N by -0.023 ± 0.008 Δ% N in VRH plots. We also observed the largest loss of soil C and N in open areas of aggregate plots. Furthermore, the changes in albedo resulting from VRH treatment were equivalent to removing a large amount of C from the atmosphere, ranging from 1.3 ± 0.2 kg C yr-1 m-2 in aggregate 33 % crown retention plots to 3.4 ± 0.5 kg C yr-1 m-2 in dispersed 33 % crown retention plots. Our findings indicate that spatially dispersed VRH resulted in minimal loss of soil C and N and the highest understory growth and C uptake, while enhanced tree growth and local cooling through increased albedo were observed in dispersed VRH plots with the fewest residual trees. These findings suggest that using the harvested trees from VRH in a way that avoids releasing C into the atmosphere makes dispersed VRH the preferred forest management pathway for nature-based climate solutions.

Seasonal variation in the relationship between leaf chlorophyll content and photosynthetic capacity.

Accurate estimation of photosynthesis is crucial for ecosystem carbon cycle modelling. Previous studies have established an empirical relationship between photosynthetic capacity (maximum carboxylation rate, Vcmax; maximum electron transport rate, Jmax) and leaf chlorophyll (Chl) content to infer global photosynthetic capacity. However, the basis for the Chl-Vcmax relationship remains unclear, which is further evidenced by the temporal variations in the Chl-Vcmax relationship. Using multiple years of observations of four deciduous tree species, we found that Vcmax and Jmax acclimate to photosynthetically active radiation faster (4-8 weeks) than Chl (10-12 weeks). This mismatch in temporal scales causes seasonality in the Vcmax-Chl relationship. To account for the mismatch, we used a Chl fluorescence parameter (quantum yield of Photosystem II, Φ(II)) to tighten the relationship and found Φ(II) × Chl correlated with Vcmax and Jmax (r2 = 0.74 and 0.72 respectively) better than only Chl (r2 = 0.7 and 0.6 respectively). It indicates that Φ(II) accounts for the short-term adjustment of leaf photosynthetic capacity to light, which was not captured by Chl. Our study advances our understanding of the ecophysiological basis for the empirical Vcmax-Chl relationship and how to better infer Vcmax from Chl and fluorescence, which guides large-scale photosynthesis simulations using remote sensing.

Diverse photosynthetic capacity of global ecosystems mapped by satellite chlorophyll fluorescence measurements.

Photosynthetic capacity is often quantified by the Rubisco-limited photosynthetic capacity (i.e. maximum carboxylation rate, Vcmax). It is a key plant functional trait that is widely used in Earth System Models for simulation of the global carbon and water cycles. Measuring Vcmax is time-consuming and laborious; therefore, the spatiotemporal distribution of Vcmax is still poorly understood due to limited measurements of Vcmax. In this study, we used a data assimilation approach to map the spatial variation of Vcmax for global terrestrial ecosystems from a 11-year-long satellite-observed solar-induced chlorophyll fluorescence (SIF) record. In this SIF-derived Vcmax map, the mean Vcmax value for each plant function type (PFT) is found to be comparable to a widely used N-derived Vcmax dataset by Kattge et al. (2009). The gradient of Vcmax along PFTs is clearly revealed even without land cover information as an input. Large seasonal and spatial variations of Vcmax are found within each PFT, especially for diverse crop rotation systems. The distribution of major crop belts, characterized with high Vcmax values, is highlighted in this Vcmax map. Legume plants are characterized with high Vcmax values. This Vcmax map also clearly illustrates the emerging soybean revolution in South America where Vcmax is the highest among the world. The gradient of Vcmax in Amazon is found to follow the transition of soil types with different soil N and P contents. This study suggests that satellite-observed SIF is powerful in deriving the important plant functional trait, i.e. Vcmax, for global climate change studies.

The critical need for animal disaster response plans.

In the tragic aftermath of disasters over the past 30+ years, people have learned that disaster planning for individuals, for communities and for many businesses must include animals. This paper discusses why emergency planning for animals is a necessity for individuals and animal-focused businesses, as well as being a critical element in community disaster response strategies. Communication between affected groups and integration of disaster plans provide for a better response, which allows for a quicker recovery. Ensuring that animals are included in disaster mitigation/preparedness/response/ recovery plans increases resilience. It will provide a framework to manage personal and business preparedness and to launch animal disaster preparedness initiatives in communities.

Orphan G protein-coupled receptor GPR56 plays a role in cell transformation and tumorigenesis involving the cell adhesion pathway.

GPR56 is an orphan G protein - coupled receptor, mutations of which have recently been associated with bilateral frontoparietal polymicrogyria, a rare neurologic disease that has implications in brain development. However, no phenotype beyond central nervous system has yet been described for the GPR56-null mutations despite abundant GPR56 expression in many non - central nervous system adult tissues. In the present study, we show that higher GPR56 expression is correlated with the cellular transformation phenotypes of several cancer tissues compared with their normal counterparts, implying a potential oncogenic function. RNA interference-mediated GPR56 silencing results in apoptosis induction and reduced anchorage-independent growth of cancer cells via increased anoikis, whereas cDNA overexpression resulted in increased foci formation in mouse fibroblast NIH3T3 cell line. When GPR56 silencing was induced in vivo in several xenograft tumor models, significant tumor responses (including regression) were observed, suggesting the potential of targeting GPR56 in the development of tumor therapies. The expression profiling of GPR56-silenced A2058 melanoma cell line revealed several genes whose expression was affected by GPR56 silencing, particularly those in the integrin-mediated signaling and cell adhesion pathways. The potential role of GPR56 in cancer cell adhesion was further confirmed by the observation that GPR56 silencing also reduced cell adhesion to the extracellular matrix, which is consistent with the observed increase in anoikis and reduction in anchorage-independent growth phenotypes. The oncogenic potential and apparent absence of physiologic defects in adult human tissues lacking GPR56, as well as the targetable nature of G protein - coupled receptor by small molecule or antibody, make GPR56 an attractive drug target for the development of cancer therapies.

Sensitivity to isolated and concurrent intensity and fundamental frequency increments by cochlear implant users under natural listening conditions.

Sensitivity to acoustic cues in cochlear implant (CI) listening under natural conditions is a potentially complex interaction between a number of simultaneous factors, and may be difficult to predict. In the present study, sensitivity was measured under conditions that approximate those of natural listening. Synthesized words having increases in intensity or fundamental frequency (F0) in a middle stressed syllable were presented in soundfield to normal-hearing listeners and to CI listeners using their everyday speech processors and programming. In contrast to the extremely fine sensitivity to electrical current observed when direct stimulation of single electrodes is employed, difference limens (DLs) for intensity were larger for the CI listeners by a factor of 2.4. In accord with previous work, F0 DLs were larger by almost one order of magnitude. In a second experiment, it was found that the presence of concurrent intensity and F0 increments reduced the mean DL to half that of either cue alone for both groups of subjects, indicating that both groups combine concurrent cues with equal success. Although sensitivity to either cue in isolation was not related to word recognition in CI users, the listeners having lower combined-cue thresholds produced better word recognition scores.

A novel RNAi library based on partially randomized consensus sequences of nuclear receptors: identifying the receptors involved in amyloid beta degradation.

Combinatorial gene inactivation using an RNAi library is a powerful approach to discovering novel functional genes. However, generation of a comprehensive RNAi library remains technically challenging. In this report, we describe a simple and novel approach to designing gene-family-specific RNAi libraries by targeting conserved motifs using degenerate oligonucleotides. We created an siRNA library in the pHUMU vector using partially randomized sequences targeting the consensus region in the ZnF_C4 signature motif of the nuclear hormone receptors and thus against the entire receptor superfamily. For proof of principle, we adapted a reporter assay to screen this library for receptors that might be involved in reducing amyloid beta peptide accumulation. We modified a previously described luciferase reporter assay to measure the amyloid beta precursor cleavages occurring only between beta- and gamma-secretase cleavage sites, thus excluding the major gamma-secretase activities that could generate neurotoxic Abeta peptides. Our screen using this assay identified siRNA vectors that specifically increase the Abeta40/42 cleavage and pointed to a potential receptor target, ROR-gamma. SiRNAs targeting other regions of ROR-gamma not only confirmed the observed reporter activity but also reduced the level of the toxic Abeta peptides. The results demonstrated a general principle for the creation and application of this RNAi library approach for functional gene discovery within a predefined protein family. The discovered negative effect of ROR-gamma on the degradation of the toxic Abeta peptides may also provide a potential drug target or targetable pathway for intervention of Alzheimer disease.

Trans-synaptic Eph receptor-ephrin signaling in hippocampal mossy fiber LTP.

The site of induction of long-term potentiation (LTP) at mossy fiber-CA3 synapses in the hippocampus is unresolved, with data supporting both pre- and postsynaptic mechanisms. Here we report that mossy fiber LTP was reduced by perfusion of postsynaptic neurons with peptides and antibodies that interfere with binding of EphB receptor tyrosine kinases (EphRs) to the PDZ protein GRIP. Mossy fiber LTP was also reduced by extracellular application of soluble forms of B-ephrins, which are normally membrane-anchored presynaptic ligands for the EphB receptors. The application of soluble ligands for presynaptic ephrins increased basal excitatory transmission and occluded both tetanus and forskolin-induced synaptic potentiation. These findings suggest that PDZ interactions in the postsynaptic neuron and trans-synaptic interactions between postsynaptic EphB receptors and presynaptic B-ephrins are necessary for the induction of mossy fiber LTP.

NMDA receptors formed by NR1 in Xenopus laevis oocytes do not contain the endogenous subunit XenU1.

Activation of N-methyl-D-aspartate-selective ionotropic glutamate receptors (NMDA receptors) requires two agonists, glutamate and glycine. These ligands are thought to bind to the NR2 and NR1 subunits, respectively, apparently ruling out the formation of functional homomeric receptors. However, NMDA-mediated currents are observed when the mammalian NR1 subunit is expressed alone in Xenopus laevis oocytes. These currents have been generally ascribed to a functional association between NR1 and the endogenous glutamate receptor subunit XenU1. To determine whether such a functional association does in fact occur, we have isolated cDNAs for both XenU1 and XenU1a, a presumed nonallelic counterpart. We investigated whether the coexpression of either XenU1 or XenU1a with NR1 in either X. laevis oocytes and human embryonic kidney (HEK) 293 cells had any effect on the observed NMDA receptor responses. In oocytes, coinjection of XenU1 with NR1 did not increase the observed currents compared with injection of NR1 alone; similarly, in HEK 293 cells, coexpression of XenU1 and NR1 did not result in the formation of functional channels. We also found no pharmacological or biochemical evidence for interaction between the two subunits. We conclude, therefore, that XenU1 does not associate with the NR1 subunit and that an alternative explanation must be sought for the channels observed when NR1 is expressed alone in oocytes.