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1.
Relationships Between Fire Response, Morphology, Root Anatomy and Starch Distribution in South-west Australian Epacridaceae 总被引:3,自引:4,他引:3
Selected epacrids (92 species in 15 genera) were examined withrespect to fire response type, morphology, root anatomy andstarch storage. Seeders, 75% of the species investigated, possesseda single main stem and a small root system with lateral rootswhich in most cases did not spread beyond the shoot canopy.Resprouter species were generally multi-stemmed with large lignotuberousroot stocks. Certain seeder and resprouter species were intermediatein form and showed small root systems and basally branched mainstems. Amounts of starch in roots of seeders (1.9±0.5mgstarch gd.wt per root) were much less than in resprouters (14.1±3.3)whereas amounts in shoots were similar (1.9±0.5 and 1.6±0.6mgstarch gd.wt per shoot, respectively). Starch storage in rootswas mostly confined to rays of xylem parenchyma and inter-rayxylem parenchyma and the greater storage capacity of resprouterswas generally due to broader rays. Growth zones in root xylemranged from clear, verifiable annual rings, as in many seederspecies, to indistinct growth zones, typical of many resprouterspecies. Shoot:root dry weight ratios were higher in seedersthan resprouters. The study suggests that speciation withinthe Epacridaceae into seeder and resprouter forms involved divergentdifferentiation in terms of morphology, shoot:root dry weightratio root storage of starch. Seeder; starch storage; growth rings; growth zones; south-west Australia; resprouter; Epacridaceae 相似文献
2.
ZmCPK1, a calcium‐independent kinase member of the Zea mays CDPK gene family,functions as a negative regulator in cold stress signalling
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Calcium‐dependent protein kinases (CDPKs) have been shown to play important roles in plant environmental stress signal transduction. We report on the identification of ZmCPK1 as a member of the maize (Zea mays) CDPK gene family involved in the regulation of the maize cold stress response. Based upon in silico analysis of the Z. mays cv. B73 genome, we identified that the maize CDPK gene family consists of 39 members. Two CDPK members were selected whose gene expression was either increased (Zmcpk1) or decreased (Zmcpk25) in response to cold exposure. Biochemical analysis demonstrated that ZmCPK1 displays calcium‐independent protein kinase activity. The C‐terminal calcium‐binding domain of ZmCPK1 was sufficient to mediate calcium independency of a previously calcium‐dependent enzyme in chimeric ZmCPK25‐CPK1 proteins. Furthermore, co‐transfection of maize mesophyll protoplasts with active full‐length ZmCPK1 suppressed the expression of a cold‐induced marker gene, Zmerf3 (ZmCOI6.21). In accordance, heterologous overexpression of ZmCPK1 in Arabidopsis thaliana yielded plants with altered acclimation‐induced frost tolerance. Our results identify ZmCPK1 as a negative regulator of cold stress signalling in maize. 相似文献
3.
Geographical and seasonal gradients in hatching failure in Eastern Bluebirds Sialia sialis reinforce clutch size trends 总被引:1,自引:0,他引:1
Eggs untended during the laying phase can lose viability if exposed to high temperatures, such as those common at lower latitudes and late in the nesting season. The egg‐viability hypothesis states that constraints on viability during the laying phase could account for latitudinal and seasonal gradients in clutch size. We used 7 years’ worth of data collected by volunteers (The Birdhouse Network, co‐ordinated by the Cornell Laboratory of Ornithology) to look simultaneously at populations across the temperate breeding range of Eastern Bluebirds Sialia sialis in order to test three predictions of the egg‐viability hypothesis: the probability of hatching failure decreases at higher latitude and increases later in the season, and that these trends are strongest among large clutches. The overall average number of unhatched eggs relative to the total number of eggs laid was similar to that found by other studies (7.8%; range 6.8–8.9% annually; n = 32 567 eggs from 7231 nests from 530 study sites). Using generalized linear mixed models that controlled for the non‐independence of eggs within a clutch, we found that the ‘per‐egg’ probability of hatching failure was highest late in the season, highest at lower latitudes, and highest for both small (three‐egg) and large (six‐egg) clutches. The seasonal and geographical gradients in egg hatching failure reinforce documented seasonal and geographical trends in clutch size. Loss of egg viability prior to incubation currently provides the most parsimonious and consistent explanation of the observed patterns of hatching failure. However, alternative explanations for large‐scale patterns, particularly those not consistent with the egg‐viability hypothesis, warrant further research into other causes of hatching failure, such as microbes and infertility (related to extra‐pair mating). Our results demonstrate that investigating causes of variation in demography among local populations across a geographical gradient provides a potential means of identifying selection pressures on life‐history traits. 相似文献
4.
MOHSEN EMADEDIN NARGES LABIBZADEH MAEDE GHORBANI LIASTANI ALIASGHAR KARIMI NEDA JAROUGHI TINA BOLURIEH SEYYEDEH-ESMAT HOSSEINI HOSSEIN BAHARVAND NASSER AGHDAMI 《Cytotherapy》2018,20(10):1238-1246
Background
The intra-articular implantation of mesenchymal stromal cells (MSCs) as a treatment for knee osteoarthritis (OA) is an emerging new therapy. In this study, patients with knee OA received intra-articular implantations of autologous bone marrow–derived MSCs. We sought to assess the safety and efficacy of this implantation.Materials and Methods
This was a phase 1/2 single-center, triple-blind, randomized controlled trial (RCT) with a placebo control. The subjects consisted of patients with knee OA randomly assigned to either an intra-articular implantation of MSCs (40?×?106 cells) or 5 mL normal saline (placebo). Patients were followed up for 6 months after the implantations. The pain level and function improvements for patient-reported outcomes were assessed based on a visual analog scale (VAS), Western Ontario and McMaster Universities Arthritis Index (WOMAC) and its subscales, walking distance, painless walking distance, standing time and knee flexion compared with the placebo group at 3 and 6 months following the implantations.Results
Overall, 43 patients (Kellgren-Lawrence grades 2, 3 and 4) were assigned to either the MSCs (n?=?19) or placebo (n?=?24) group. Patients who received MSCs experienced significantly greater improvements in WOMAC total score, WOMAC pain and physical function subscales and painless walking distance compared with patients who received placebo. There were no major adverse events attributed to the MSC therapy.Conclusion
This randomized, triple-blind, placebo-controlled RCT demonstrated the safety and efficacy of a single intra-articular implantation of 40?×?106 autologous MSCs in patients with knee OA. Intra-articular implantation of MSCs provided significant and clinically relevant pain relief over 6 months versus placebo and could be considered a promising novel treatment for knee OA. We propose that further investigations should be conducted over an extended assessment period and with a larger cohort. 相似文献5.
TINA YERKES KEITH A. HOBSON LEONARD I. WASSENAAR ROBB MACLEOD JOHN M. COLUCCY 《The Journal of wildlife management》2008,72(3):715-725
Abstract: Information on spring migration routes, geographic linkages among winter, spring, and breeding locations, and potential geographic effects on arrival body condition of northern pintails (Anas acuta) are currently unknown. Through a combination of stable-isotope measurements of tissues representing different periods of dietary integration and body composition analyses, we examined these linkages for pintails breeding in Alaska, USA. We collected 77 females at 4 locations upon spring arrival. We performed carbon (δ13C), nitrogen (δ15N), and hydrogen (δD) isotope measurements on flight feathers, breast feathers, and whole blood, and we conducted body composition analyses. Inference based on stable-isotope values in pintail tissues suggests that philopatry to Alaska was strong, as most of the collected females had stable-isotope values consistent with the boreal forest of Canada or western Alaska and most spring migrating females had whole-blood values indicating use of a food web in the boreal forest before collection. These patterns highlight the importance of the boreal forest for production and staging of pintails. Breast feather isotope values grown during prealternate molt were variable and covered the currently documented distribution of wintering pintails. Our results indicate associations among specific geographic areas, habitat use, and arrival condition of female pintails settling in Alaska. Females that wintered or staged in coastal habitat (as indicated by elevated δ13C values) arrived with less body fat compared to those that we inferred to have wintered or staged on inland freshwater habitat. Those females we inferred to use coastal areas appeared to rely more heavily on agricultural fields for nutrient acquisition (as indicated by elevated δ15N but low δ13C values). Our results provide the first link between low-condition females and inferred use of specific geographic areas before arrival. Conservation on wintering grounds should focus on restoration and protection of wetland complexes that provide adequate natural food resources in proximity to coastal systems that are heavily used by wintering pintails. Conservation efforts should also focus on the boreal forest, not only for pintail, but for other boreal-dependent species such as lesser scaup (Aythya affinis) (JOURNAL OF WILDLIFE MANAGEMENT 72(3):715–725; 2008) 相似文献
6.
JOHN M. COLUCCY TINA YERKES REBECCA SIMPSON JOHN W. SIMPSON LLWELLYN ARMSTRONG JONAS DAVIS 《The Journal of wildlife management》2008,72(5):1181-1187
Abstract: Mallard (Anas platyrhynchos) populations in the United States portion of the Great Lakes region increased through the 1990s but have since declined. To promote sustainable growth of this population, managers need to understand how perturbation of vital rates will affect annual population growth rate (Λ). We developed a stage-based model representing the female mallard population in the Great Lakes using vital rates generated from a landscape-level study documenting reproductive parameters from 2001 to 2003. We conducted perturbation analyses (i.e., sensitivity analyses) to identify vital rates that most influence Λ and variance decomposition analyses to determine the proportion of variation in Λ explained by variation in each vital rate. Perturbation analyses indicated that Λ was most sensitive to changes in nonbreeding survival, duckling survival, and nest success. Therefore, changes in these vital rates would be expected to result in the greatest ΔΛ. Process variation in breeding season parameters accounted for 63% of variation in Λ. Breeding season parameters explaining the most variation were duckling survival (32%) and nest success (16%). Survival of adult females outside the breeding season accounted for 36% of variation in Λ. Harvest derivation, high harvest, and high sensitivity of Λ to nonbreeding survival for Great Lakes female mallards suggests there is a strong potential for managing the Great Lakes mallard population via harvest management. Because Λ was highly sensitive to changes in duckling survival, we suggest programs that emphasize wetland protection, enhancement, and restoration as a management strategy to improve population growth for breeding mallards. 相似文献
7.
We examined microclimatic conditions and soil nitrogen (N) dynamics of different alpine plant community types on the Bogong High Plains in Victoria, Australia. Three community types are predominant in the High Plains region, namely grassland, heathland and woodland and together they form so‐called inverted treelines, with grassland in valley floors below the treeline. Outdoor temperature loggers were deployed in the three vegetation types to establish differences among microclimatic conditions. We incubated soils to determine rates of N production and collected additional soil samples for analysis of soil properties and soluble N. Temperature data showed that only grassland communities experienced sub‐zero temperatures in winter. Temperature and soil moisture influenced indices of N mineralization and N nitrification in this alpine ecosystem. Rates of N mineralization were significantly faster than nitrification that only produced consequential amounts of nitrate in summer. This information, together with considerably lower pools of nitrate than ammonium and organic N in the soil, implies that ammonium is the dominant form of soluble N in the ecosystem whereas nitrate most likely only has minor importance for plant nutrition. The results of this study provide insight into ecological processes of this alpine ecosystem and demonstrate the vulnerability of the system to altered climatic and edaphic conditions in the course of climate change. 相似文献
8.
Effects of stream restoration and management on plant communities in lowland streams 总被引:1,自引:0,他引:1
TINA CHARLOTTE MOUSTGAARD PEDERSEN ANNETTE BAATTRUP-PEDERSEN TOM VINDBÆK MADSEN 《Freshwater Biology》2006,51(1):161-179
1. We evaluated restoration success on macrophyte species diversity and composition in lowland streams using communities in 30 naturally meandering stream reaches in the western part of Jutland, Denmark, as reference target communities. Fuzzy set clustering was used to examine the floristic and environmental similarity among reaches, whereas fuzzy set ordination was used to relate floristic patterns to environmental variables. 2. Two major groups of streams were identified based on their floristic composition. One group consisted of reference and restored reaches and the other of the majority of channelised reaches. We found that management exerted a strong influence on the macrophyte communities and that the identified groups were related to differences in management intensity. 3. Our results also indicate that bank morphology and bed level affected macrophyte communities in the streams, particularly the richness and abundance of terrestrial species. The analyses performed suggest that shallow and wide banks allow for a larger migration of species from the stream banks into the streams, thereby enhancing species diversity within the stream channel. 4. The results of this study suggest that macrophyte communities in channelised lowland streams can recover following restorative interventions given that stream management (i.e. weed cutting and dredging) is minimised and that stream banks are reprofiled to improve the lateral connectivity between the stream and its valley. 相似文献
9.
TIMOTHY J. IANNUZZI TINA N. ARMSTRONG JOHN B. THELEN DAVID F. LUDWIG CLIFFORD E. FIRSTENBERG 《Soil & Sediment Contamination》2005,14(1):13-33
The lower six miles of the tidal portion of the Passaic River (Study Area) has been heavily industrialized since the mid-1800s. The objectives of this study were to: quantify the present extent and magnitude of chemical contamination in surface sediments from the Study Area; evaluate the contamination in the Study Area relative to a reference area and surrounding regional waterways; assess the potential for adverse effects to aquatic organisms; and identify spatial gradients in concentrations that may indicate potential point-sources of chemicals. Because existing ecological communities center primarily on intertidal mudflats in the Study Area, composite surface sediment was collected from 15 mudflats to generate a realistic assessment of fish and wildlife exposure to sediment contaminants. This study showed that present concentrations of organic contaminants are elevated throughout the Study Area and are generally higher than concentrations in the reference area and regional waterways. A screening-level analysis showed that there is potential for adverse effects to sediment-associated organisms from a number of chemicals. No spatial trends were apparent for most compounds evaluated, consistent with the presence of multiple sources of chemicals in the Study Area. The exception is semivolatile compounds, which appear to be localized to specific mudflats, indicating potential point-sources of contamination for these chemicals. 相似文献
10.
TINA N. ARMSTRONG TIMOTHY J. IANNUZZI JOHN B. THELEN DAVID F. LUDWIG CLIFFORD E. FIRSTENBERG 《Soil & Sediment Contamination》2005,14(1):35-52
The lower six miles of the tidal portion of the Passaic River (Study Area) has long been heavily industrialized. The objectives of this study were to: quantify the present extent and magnitude of metals contamination in surface sediments in the Study Area, evaluate the contamination in the Study Area relative to a reference area and surrounding regional waterways, assess the potential for adverse effects to aquatic organisms, and identify spatial gradients in concentrations that may indicate potential point-sources of metals. We also examined the role of natural sediment characteristics in metals concentration variability. Study Area sediments were generally enriched in barium, cadmium, chromium, copper, lead, manganese, mercury, silver, selenium, and zinc relative to the reference area. Compared to available sediment quality benchmarks, the only metals in the Study Area presently at average concentrations sufficiently high to warrant concern about potential aquatic toxicity are lead, mercury, and zinc. Compared to the rest of the NY/NJ Harbor Estuary, the Study Area generally contains elevated levels of lead, manganese, silver, and zinc. Variability in metals concentrations can not be accounted for by TOC or percent fines. However, a substantial proportion of the spatial variability in a number of metals can be explained by normalization to either aluminum or iron. 相似文献