Generalized avian dispersal syndrome contributes to Chinese tallow tree (Sapium sebiferum, Euphorbiaceae) invasiveness

Abstract. Plants possessing generalized dispersal syndromes are likely to be more invasive than those relying on specialist dispersal agents. To address this issue on a local and regional scale, avian seed dispersal of the invasive alien Chinese tallow tree (Sapium sebiferum (L.) Roxb.) was assessed in forests and spoil areas of South Carolina and along forest edges in Louisiana during the 1997–99 fruiting seasons. Tallow trees in these floristically distinct habitats had a few common and many casual visitors, and considerable species overlap among habitats was found. However, bird species differed in the importance of dispersing and dropping seeds among habitats. Important dispersal agents common to forests and spoil areas of South Carolina included Northern Flicker, American Robin and Red‐winged Blackbird, whereas Red‐bellied Woodpecker and European Starling were important in the former and latter habitat, respectively. In Louisiana, Red‐bellied Woodpecker, American Robin, Northern Cardinal and Eastern Bluebird dispersed many seeds. Nearly all species foraging on seeds were winter residents. Estimated numbers of seeds dispersed and dropped were higher in spoil areas of South Carolina than in Louisiana because of higher numbers of individuals per visit, higher seed consumption and seed dropping rates, and longer foraging durations. Within South Carolina, more seeds were dispersed and dropped in spoil areas than in forests because of higher numbers of birds per visit. These findings show that among habitats, tallow tree attracts diverse but variable coteries of dispersal agents that are qualitatively similar in seed usage patterns. We suggest that its generalized dispersal syndrome contributes to effective seed dispersal by many bird species throughout its range. Effects of differential avian use among locales may include changes in local bird communities, and differing tallow tree demographics and invasion patterns.     

Hydraulic responses to height growth in maritime pine trees

As trees grow taller, decreased xylem path conductance imposes a major constraint on plant water and carbon balance, and is thus a key factor underlying forest productivity decline with age. The responses of stomatal conductance, leaf area: sapwood area ratio (A_L : A_S) and soil–leaf water potential gradient (ΔΨ_S–L) to height growth were investigated in maritime pine trees. Extensive measurements of in situ sap flow, stomatal conductance and (non‐gravitational) needle water potential (_L = Ψ_L ? ρ_wgh) were made during 2 years in a chronosequence of four even‐aged stands, under both wet and dry soil conditions. Under wet soil conditions, _L was systematically lower in taller trees on account of differences in gravitational potential. In contrast, under dry soil conditions, our measurements clearly showed that _L was maintained above a minimum threshold value of ?2.0 MPa independently of tree height, thus limiting the range of compensatory change in ΔΨ_S–L. Although a decrease in the A_L : A_S ratio occurred with tree height, this compensation was not sufficient to prevent a decline in leaf‐specific hydraulic conductance, K_L (50% lower in 30 m trees than in 10 m trees). An associated decline in stomatal conductance with tree height thus occurred to maintain a balance between water supply and demand. Both the increased investment in non‐productive versus productive tissues (A_S : A_L) and stomatal closure may have contributed to the observed decrease in tree growth efficiency with increasing tree height (by a factor of three from smallest to tallest trees), although other growth‐limiting responses (e.g. soil nutrient sequestration, increased respiratory costs) cannot be excluded.     

Rapid leaf decay and nutrient release in a chinese tallow forest

Summary The Chinese tallow tree, Sapium sebiferum, was introduced to the Texas Gulf Coast in the early 1900's and has spread into coastal prairie habitats. Since coastal prairie contains few deciduous trees, we studied leaf fall dynamics, rate of decomposition, and the quantity and rate of nutrient input from decomposing tallow leaves. Among-year leaf fall averaged 382.6 g·m^-2·yr^-1, similar to other south temperat deciduous forests and about as predicted by Meentemeyer et al.'s (1982) AE-lignin model. Decay of tallow leaves (k=-4.33) was much more rapid than native black willow (k=-0.35) and than other temperate deciduous trees (k=-0.77). The ratio of lignin to initial nitrogen concentration, highly correlated with rate of decomposition for hardwood trees, was low for Chinese tallow and may contribute to rapid leaf decay. Taking AE and lignin content into account, Meentemeyer's (1984) model predicted k=-1.39 for Chinese tallow and k=-0.88 for black willow. Decay of tallow was much faster but decay of willow was slower than predicted, suggesting that decay on the coastal prairie may be controlled by factors other than lignin content and climate. N, P, and K characteristically accumulate as leaves decay. However, these elements did not accumulate as tallow leaves decayed, possibly because high densities of Armadillidium vulgare, a detritivore, reduced immobilization of elements by microbes. This would result in increased turnover of these elements. Accumulation of Al, Fe, Zn, and S in decaying tallow litter may be related to flood-drain cycles on coastel prairie clay soils. Ca, N, K, Mg, and S were added to forest soil in greatest amounts from decaying tallow leaves. Concentrations of P, K, NO₃–N, Zn, Mn, and Fe were significantly higher and Mg and Na were significantly lower in forest than in prairie soil, raising the possibility that Chinese tallow trees altered the distribution of nutrients in the soil profile. We conclude that the Chinese tallow tree may enhance productivity in ecosystems to which it has been introduced by addition of nutrients from rapid decay of leaves.     

Declining old‐forest species as a legacy of large trees lost

Aim

Global declines in large old trees from selective logging have degraded old‐forest ecosystems, which could lead to delayed declines or losses of old‐forest‐associated wildlife populations (i.e., extinction debt). We applied the declining population paradigm and explored potential evidence for extinction debt in an old‐forest dependent species across landscapes with different histories of large tree logging.

Location

Montane forests of the Sierra Nevada, California, USA.

Methods

We tested hypotheses about the influence of forest structure on territory extinction dynamics of the spotted owl (Strix occidentalis) using detection/non‐detection data from 1993 to 2011 across two land tenures: national forests, which experienced extensive large tree logging over the past century, and national parks, which did not.

Results

Large tree/high canopy cover forest was the best predictor of extinction rates and explained 26%–77% of model deviance. Owl territories with more large tree/high canopy cover forest had lower extinction rates, and this forest type was ~4 times more prevalent within owl territories in national parks ( = 19% of territory) than national forests ( = 4% of territory). As such, predicted extinction probability for an average owl territory was ~2.5 times greater in national forests than national parks, where occupancy was declining () and stable (), respectively. Large tree/high canopy cover forest remained consistently low, but did not decline, during the study period on national forests while owl declines were ongoing—an observation consistent with an extinction debt.

Main conclusions

In identifying a linkage between large trees and spotted owl dynamics at a regional scale, we provide evidence suggesting past logging of large old trees may have contributed to contemporary declines in an old‐forest species. Strengthening protections for remaining large old trees and promoting their recruitment in the future will be critical for biodiversity conservation in the world's forests.

     

Woody biomass potential of the Chinese tallow tree

The Chinese tallow tree (Sapium sebiferum Roxb.) is a rapid-growing species that has become naturalized along the Gulf and southern Atlantic coasts. The tree is particularly well adapted to poorly-drained and saline soils. Chinese tallow seedlings planted at 2’×2’ spacing produced over 5 dry tons of biomass/acre at the end of the second growing season while the biomass accumulation on coppiced plots was more than 7 dry tons /acre at the end of the second year. The Chinese tallow tree has considerable promise as a woody biomass species in the southern coastal regions of the United States.     

Effects of flooding and salinity on photosynthesis and water relations of four Southeastern Coastal Plain forest species

The influence of flooding and salinity on photosynthesis and water relations was examined for four common coastal tree species [green ash (Fraxinus pennsylvanica Marshall), water tupelo (Nyssa aquatica L.). Chinese tallow (Sapium sebiferum (L.) Roxb.), and baldcypress (Taxodium distichum (L.) Richard)]. Both chronic (as might be associated with sea level rise) and acute (similar to hurricane storm surges) exposures to these stresses were examined. Chronic freshwater flooding of green ash, water tupelo, and Chinese tallow seedlings reduced photosynthesis (A) relative to that of watered seedlings, while baldcypress was unaffected. Chinese tallow A declined with increasing length of flooding. A salinity increase of the floodwater to 2 ppt decreased A of baldcypress and water tupelo, but not A of green ash and Chinese tallow, which was already severely reduced by freshwater flooding. All seedlings of the four species died within 2 to 6 weeks when flooded with 10 ppt saltwater. Photosynthesis of all four species did not differ between 0 and 2 ppt watering. Watering with 10 ppt salinity initially reduced A of all four species, but the seedlings recovered over time. Photosynthesis was severely decreased for all species when flooded with 21 ppt salinity for 48 hours. Reduced A continued following the treatment. Photosynthesis of only green ash and water tupelo was reduced by watering with 21 ppt salinity for 48 hours. Flooding of low-lying areas with increased salinity would lead to shifts in species composition of coastal forests due to these differential tolerances.     

Effects of transgenic American chestnut leaf litter on growth and survival of wood frog larvae

Biotechnology offers a new approach for the restoration of tree species affected by exotic pathogens; however, nontarget impacts of this novel strategy on other organisms have not been comprehensively assessed. We evaluated the effect of transgenic American chestnut (Castanea dentata) leaf litter on the growth and survival of larval wood frogs (Lithobates sylvaticus), a forest‐dwelling amphibian species widely sympatric with American chestnut, that forage almost entirely on periphyton and litter detritus that accumulate in temporary vernal pools in forests. We reared wood frog larvae on Castanea leaf litter (American chestnut genetically engineered for blight tolerance, nontransgenic American chestnut, Chinese chestnut [Castanea mollissima], and an American–Chinese chestnut hybrid) and litter from two non‐Castanea, nontransgenic “control” tree species, coupled with two levels of supplementary food. We observed no differences in growth or survival of wood frog larvae reared on transgenic versus nontransgenic American chestnut leaves. Without supplementary food, wood frog larvae provided leaves from American chestnut (both types) developed faster and grew larger than those exposed to other leaf litter treatments. Results of this study provide preliminary evidence that (1) American chestnut may have formerly been an important source of food for forest‐dwelling amphibians and (2) transgenic American chestnut litter generated as part of chestnut restoration efforts is unlikely to present direct novel risks to developing amphibian larvae in the forest environment.     

The role of a cytosolic superoxide dismutase in barley–pathogen interactions

Reactive oxygen species (ROS), including superoxide ( / ) and hydrogen peroxide (H₂O₂), are differentially produced during resistance responses to biotrophic pathogens and during susceptible responses to necrotrophic and hemi‐biotrophic pathogens. Superoxide dismutase (SOD) is responsible for the catalysis of the dismutation of / to H₂O₂, regulating the redox status of plant cells. Increased SOD activity has been correlated previously with resistance in barley to the hemi‐biotrophic pathogen Pyrenophora teres f. teres (Ptt, the causal agent of the net form of net blotch disease), but the role of individual isoforms of SOD has not been studied. A cytosolic CuZnSOD, HvCSD1, was isolated from barley and characterized as being expressed in tissue from different developmental stages. HvCSD1 was up‐regulated during the interaction with Ptt and to a greater extent during the resistance response. Net blotch disease symptoms and fungal growth were not as pronounced in transgenic HvCSD1 knockdown lines in a susceptible background (cv. Golden Promise), when compared with wild‐type plants, suggesting that cytosolic / contributes to the signalling required to induce a defence response to Ptt. There was no effect of HvCSD1 knockdown on infection by the hemi‐biotrophic rice blast pathogen Magnaporthe oryzae or the biotrophic powdery mildew pathogen Blumeria graminis f. sp. hordei, but HvCSD1 also played a role in the regulation of lesion development by methyl viologen. Together, these results suggest that HvCSD1 could be important in the maintenance of the cytosolic redox status and in the differential regulation of responses to pathogens with different lifestyles.     

Critical role for the AIM2 inflammasome during acute CNS bacterial infection

Interleukin‐1β (IL‐1β) is essential for eliciting protective immunity during the acute phase of Staphylococcus aureus (S. aureus) infection in the central nervous system (CNS). We previously demonstrated that microglial IL‐1β production in response to live S. aureus is mediated through the Nod‐like receptor protein 3 (NLRP3) inflammasome, including the adapter protein ASC (apoptosis‐associated speck‐like protein containing a caspase‐1 recruitment domain), and pro‐caspase 1. Here, we utilized NLRP3, ASC, and caspase 1/11 knockout (KO) mice to demonstrate the functional significance of inflammasome activity during CNS S. aureus infection. ASC and caspase 1/11 KO animals were exquisitely sensitive, with approximately 50% of mice succumbing to infection within 24 h. Unexpectedly, the survival of NLRP3 KO mice was similar to wild‐type animals, suggesting the involvement of an alternative upstream sensor, which was later identified as absent in melanoma 2 (AIM2) based on the similar disease patterns between AIM2 and ASC KO mice. Besides IL‐1β, other key inflammatory mediators, including IL‐6, CXCL1, CXCL10, and CCL2 were significantly reduced in the CNS of AIM2 and ASC KO mice, implicating autocrine/paracrine actions of IL‐1β, as these mediators do not require inflammasome processing for secretion. These studies demonstrate a novel role for the AIM2 inflammasome as a critical molecular platform for regulating IL‐1β release and survival during acute CNS S. aureus infection.

     

Tree size frequency distributions, plant density, age and community disturbance

We show that explicit mathematical and biological relationships exist among the scaling exponents and the allometric constants (α and β, respectively) of log–log linear tree‐community size frequency distributions, plant density N_T, and minimum, maximum and average stem diameters (D_min, D_max, and , respectively). As individuals grow in size and D_max increases, N_T is predicted to decrease as reflected by a decrease in the numerical value of α and an increase in the value of β. Our derivations further show that N_T decreases as increases even if D_min or D_max remain unchanged. Because D_max and the age of the largest individuals in a community are correlated, albeit weakly, we argue that the interdependent relationships among the numerical values of α, β, N_T, and shed light on the extent to which communities have experienced recent global disturbance. These predicted relationships receive strong statistical support using two large datasets spanning a broad spectrum of tree‐dominated communities.     

Protective and toxic roles of dopamine in Parkinson's disease

The molecular mechanisms causing the loss of dopaminergic neurons containing neuromelanin in the substantia nigra and responsible for motor symptoms of Parkinson's disease are still unknown. The discovery of genes associated with Parkinson's disease (such as alpha synuclein (SNCA), E3 ubiquitin protein ligase (parkin), DJ‐1 (PARK7), ubiquitin carboxyl‐terminal hydrolase isozyme L1 (UCHL‐1), serine/threonine‐protein kinase (PINK‐1), leucine‐rich repeat kinase 2 (LRRK2), cation‐transporting ATPase 13A1 (ATP13A), etc.) contributed enormously to basic research towards understanding the role of these proteins in the sporadic form of the disease. However, it is generally accepted by the scientific community that mitochondria dysfunction, alpha synuclein aggregation, dysfunction of protein degradation, oxidative stress and neuroinflammation are involved in neurodegeneration. Dopamine oxidation seems to be a complex pathway in which dopamine o‐quinone, aminochrome and 5,6‐indolequinone are formed. However, both dopamine o‐quinone and 5,6‐indolequinone are so unstable that is difficult to study and separate their roles in the degenerative process occurring in Parkinson's disease. Dopamine oxidation to dopamine o‐quinone, aminochrome and 5,6‐indolequinone seems to play an important role in the neurodegenerative processes of Parkinson's disease as aminochrome induces: (i) mitochondria dysfunction, (ii) formation and stabilization of neurotoxic protofibrils of alpha synuclein, (iii) protein degradation dysfunction of both proteasomal and lysosomal systems and (iv) oxidative stress. The neurotoxic effects of aminochrome in dopaminergic neurons can be inhibited by: (i) preventing dopamine oxidation of the transporter that takes up dopamine into monoaminergic vesicles with low pH and dopamine oxidative deamination catalyzed by monoamino oxidase (ii) dopamine o‐quinone, aminochrome and 5,6‐indolequinone polymerization to neuromelanin and (iii) two‐electron reduction of aminochrome catalyzed by DT‐diaphorase. Furthermore, dopamine conversion to NM seems to have a dual role, protective and toxic, depending mostly on the cellular context.

     

Structural characterization and bioactivity evaluation of an acidic proteoglycan extract from Ganoderma lucidum fruiting bodies for PTP1B inhibition and anti‐diabetes

A water‐soluble PTP1B inhibitor, named FYGL‐a, was fractionated for structure investigation and bioactivity evaluation. FYGL‐a is an ingredient of a reported antihyperglycemia extract from Ganoderma Lucidum fruiting bodies. Composition analysis indicated that FYGL‐a was a 100.2 kDa acidic proteoglycan, consisting of 85 ± 2% heteropolysaccharide chain with rhamnose, galactose, glucose, and glucuronic acid residues in a mole ratio of 1.0:3.7:3.9:2.0, and the 15 ± 2% protein moiety of FYGL‐a was covalently bonded to the polysaccharide chain in O‐linkage type via threonine residues. The complete sequence of FYGL‐a was characterized systematically by periodate oxidation, Smith degradation, methylation analysis, ¹H & ¹³C 1D NMR, and 2D NMR (HSQC, HMBC, NOESY, COSY, & TOCSY). The chemical structure of FYGL‐a was determined as following, which may play special role in the competitive inhibition of PTP1B and antihyperglycemia potency. © 2013 Wiley Periodicals, Inc. Biopolymers 101: 613–623, 2014.

     

Screening the expression characteristics of several miRNAs in G93A‐SOD1 transgenic mouse: altered expression of miRNA‐124 is associated with astrocyte differentiation by targeting Sox2 and Sox9

MicroRNA s (miRNA s) are suspected to be a contributing factor in amyotrophic lateral sclerosis (ALS ). Here, we assess the altered expression of miRNA s and the effects of miR‐124 in astrocytic differentiation in neural stem cells of ALS transgenic mice. Differentially expressed miRNA ‐positive cells (including miR‐124, miR‐181a, miR‐22, miR‐26b, miR‐34a, miR‐146a, miR‐219, miR‐21, miR‐200a, and miR‐320) were detected by in situ hybridization and qRT ‐PCR in the spinal cord and the brainstem. Our results demonstrated that miR‐124 was down‐regulated in the spinal cord and brainstem. In vitro , miR‐124 was down‐regulated in neural stem cells and up‐regulated in differentiated neural stem cells in G93A‐ superoxide dismutase 1 (SOD 1 ) mice compared with WT mice by qRT ‐PCR . Meanwhile, Sox2 and Sox9 protein levels showed converse change with miR‐124 in vivo and vitro . After over‐expression or knockdown of miR‐124 in motor neuron‐like hybrid (NSC 34) cells of mouse, Sox2 and Sox9 proteins were noticeably down‐regulated or up‐regulated, whereas Sox2 and Sox9 mRNA s remained virtually unchanged. Moreover, immunofluorescence results indicated that the number of double‐positive cells of Sox2/glial fibrillary acidic protein (GFAP) and Sox9/glial fibrillary acidic protein (GFAP) was higher in G93A‐SOD 1 mice compared with WT mice. We also found that many Sox2‐ and Sox9‐positive cells were nestin positive in G93A‐SOD 1 mice, but not in WT mice. Furthermore, differentiated neural stem cells from G93A‐SOD 1 mice generated a greater proportion of astrocytes and lower proportion of neurons than those from WT mice. MiR‐124 may play an important role in astrocytic differentiation by targeting Sox2 and Sox9 in ALS transgenic mice.

Cover Image for this issue: doi: 10.1111/jnc.14171 .

     

PHYCOBILIPROTEIN COMPONENTS AND CHARACTERISTICS OF THE PHYCOBILISOME FROM A THERMOPHILIC CYANOBACTERIUM MYXOSARCINA CONCINNA1

A phycocyanin (PC) and three allophycocyanin (AP) components (designated PC, AP1, AP2, and AP3) were prepared from Myxosarcina concinna Printz phycobilisomes by the native gradient PAGE performed in a neutral buffer system combined with the ion exchange column chromatography on DEAE‐DE52 cellulose. PC contained one β subunit () and two α ones ( and ), and it carried two rod linkers ( and ) and one rod‐core linker (). AP1 and AP3 were characterized as peripheral core APs, whereas AP2 was an inner‐core one. AP2 and AP3 were demonstrated to function as the terminal emitters. Each of the three APs contained two β subunits ( and ), two α subunits ( and ) and an inner‐core linker (). AP2 and AP3 had another subunit of the allophycocyanin B (AP‐B) type () belonging to the β subunit group, and AP1 and AP3 carried their individual specific core linkers ( and ), respectively. No AP component was shown to associate with the core‐membrane linker L_CM. The functions of the linker polypeptides in the phycobilisome (PBS) construction are discussed.     

Effect of initial soil properties on six‐year growth of 15 tree species in tropical restoration plantings

In restoration plantings in degraded pastures, initial soil nutrient status may lead to differential growth of tropical tree species with diverse life history attributes and capacity for N₂ fixation. In 2006, we planted 1,440 seedlings of 15 native tree species in 16 fenced plots (30 × 30 m) in a 60‐year‐old pasture in Los Tuxtlas, Veracruz, Mexico, in two planting combinations. In the first year, we evaluated bulk density, pH, the concentration of organic carbon (C), total nitrogen (N), ammonia (), nitrate (), and total phosphorus (P) in the upper soil profile (0–20 cm in depth) of all plots. The first two axes of two principal component analyses explained more than 60% of the variation in soil variables: The axes were related to increasing bulk density, , , total N concentration, and pH. Average relative growth rates in diameter at the stem base of the juvenile trees after 6 years were higher for pioneer (45.7%) and N₂‐fixing species (47.6%) than for nonpioneer (34.7%) and nonfixing species (36.2%). Most N₂‐fixing species and those with the slowest growth rates did not respond to soil attributes. Tree species benefited from higher pH levels and existing litter biomass. The pioneers Ficus yoponensis, Cecropia obtusifolia, and Heliocarpus appendiculatus, and the N₂‐fixing nonpioneers Cojoba arborea, Inga sinacae, and Platymiscium dimorphandrum were promising for forest restoration on our site, given their high growth rates.     

A highly efficient in vitro regeneration methodology for mature Chinese tallow tree (Sapium sebiferum Roxb.)

A highly efficientin vitro regeneration methodology for mature chutese tallow tree (Sapium sebiferum Roxb.) has been developed. Shoot segments cultured on MS medium supplemented with 7.5 µM NAA produced light green callus. Optimum shoot differentiation resulted when callus was transferred to MS medium with 1 µM BA and 0.25 µM NAA. Shoot forming ability of callus was higher on MS medium compared to B5, half-MS or WPM. A continuous shoot harvest system at four-week intervals was established. Shoot yield continued for six months without loss of vigour. Regenerated shoots were rooted by culturing on half strength agar-gelled MS medium containing 1 µM IBA. Rooted plantlets were transferred to 1:1 soil vermiculite mixture and acclimatized with 67 % survival rate. Fully acclimatized plants were planted in the field, and performance is being evaluated.Abbreviations 2, 4- D 2, 4-dichlorophenoxyacetic acid - NAA 1 - napthaleneacetic acid - BA benzyladenine - Kn kinetin - 2-ip 6 - (, -dimethylallylamino)-purine - IBA indole-3-butyric acid - WPM woody plant medium (1980) - MS Murashige and Skoog (1962) medium - B5 Gamborg et al's medium (1968)     

Adropin preserves the blood‐brain barrier through a Notch1/Hes1 pathway after intracerebral hemorrhage in mice

Adropin is expressed in the CNS and plays a crucial role in the development of stroke. However, little is currently known about the effects of adropin on the blood‐brain barrier (BBB) function after intracerebral hemorrhage (ICH). In this study, the role of adropin in collagenase‐induced ICH was investigated in mice. At 1‐h post‐ICH, mice were administered with recombinant human adropin by intranasal. Brain water +content, BBB permeability, and neurological function were measured at different time intervals. Proteins were quantified using western blot analysis, and the localizations of adropin and Notch1 were visualized via immunofluorescence staining. It is shown that adropin reduced brain water content and improved neurological functions. Adropin preserved the functionality of BBB by increasing N‐cadherin expression and reducing extravasation of albumin. Moreover, in vivo knockdown of Notch1 and Hes1 both abolished the protective effects of adropin. Taken together, our data demonstrate that adropin constitutes a potential treatment value for ICH by preserving BBB and improving functional outcomes through the Notch1 signaling pathway.