Scaling up the diversity–resilience relationship with trait databases and remote sensing data: the recovery of productivity after wildfire

Understanding the mechanisms underlying ecosystem resilience – why some systems have an irreversible response to disturbances while others recover – is critical for conserving biodiversity and ecosystem function in the face of global change. Despite the widespread acceptance of a positive relationship between biodiversity and resilience, empirical evidence for this relationship remains fairly limited in scope and localized in scale. Assessing resilience at the large landscape and regional scales most relevant to land management and conservation practices has been limited by the ability to measure both diversity and resilience over large spatial scales. Here, we combined tools used in large‐scale studies of biodiversity (remote sensing and trait databases) with theoretical advances developed from small‐scale experiments to ask whether the functional diversity within a range of woodland and forest ecosystems influences the recovery of productivity after wildfires across the four‐corner region of the United States. We additionally asked how environmental variation (topography, macroclimate) across this geographic region influences such resilience, either directly or indirectly via changes in functional diversity. Using path analysis, we found that functional diversity in regeneration traits (fire tolerance, fire resistance, resprout ability) was a stronger predictor of the recovery of productivity after wildfire than the functional diversity of seed mass or species richness. Moreover, slope, elevation, and aspect either directly or indirectly influenced the recovery of productivity, likely via their effect on microclimate, while macroclimate had no direct or indirect effects. Our study provides some of the first direct empirical evidence for functional diversity increasing resilience at large spatial scales. Our approach highlights the power of combining theory based on local‐scale studies with tools used in studies at large spatial scales and trait databases to understand pressing environmental issues.     

Water cytotoxicity and dioxins bioaccumulation in an Egyptian delta wetland ecosystem

Manzala Lake, as one of the main Egyptian wetland ecosystems, is facing risks of pollution. An in vitro cytotoxicity test using a mammalian cell line was employed to determine the toxicity of multiple pollutants in the water and Tilapia zillii fish sampled from the lake. The concentrations of seven polychlorinated dibenzo-p-dioxins and ten polychlorinated dibenzofurans were investigated in water and muscle of the fish in 2014. Cytotoxicity testing showed that the percentage inhibition of cell viability in the studied sites ranged between 56.16% and 83.22%. Dioxin analysis indicated that the average concentrations of 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin, 1,2,3,4,7,8-hexachlorodibenzofuran, 1,2,3,4,6,7,8-heptachlorodibenzofuran and 1,2,3,4,6,7,8,9-octachlorodibenzofuran were higher than the toxic equivalence quotients (TEQs) set by the World Health Organization (WHO) in all water and fish muscle samples; however, the average concentration of 2,3,7,8-tetrachlorodibenzofuran was higher only in fish muscle samples. The bioaccumulation factor (BAF) ranged dramatically between 2 and 58.5 for the detected dioxins. Adverse human health effects through the consumption of fish are not expected, because dioxin levels in fish muscle are deemed safe for human consumption. Implementation of a strategic multidisciplinary action plan is strongly recommended to sustain this delta wetland ecosystem.     

The spider communities on peat and upland grasslands In northern England

Between midsummer 1976 and November 1977 some 29000 spiders belonging to 168 species were caught in pitfalls on 42 peat and upland grassland sites covering an altitude range of 11–827 m in the north of England. The similarities between the spider faunas of each site have been assessed using a modified form of Sørensen's Index and the sites clustered according to their similarities. The sites divided into two major groups; (1) mineral soils where grasses are dominant or shallow peat soils where Juncus squarrosus is dominant and (2) peat soils where Eriophorum vaginatum and Calluna vulgaris are dominant. It is suggested that this major division is the result of the plant "architecture" rather than the species composition of the vegetation. Direct comparison between paired peat and grassland sites at the same altitudes shows no marked separation in the spider species composition on the two soil types but there are differences in abundance of individual species. The three peat site clusters form an altitudinal sequence which is not the result of the decline in numbers of non-linyphiid species with increase in altitude as the cluster formation is largely dependent on the linyphiid species which dominate the catches.
Twenty one common species have been used lo identify the communities. Many of these species are often found together and form associations. Typically, a number of associations contribute to each community. Only 19 species contribute more than 4% to the numbers of individuals caught in any one community.
Diversity declines with increase in altitude, as does the number of species caught. The decline in the number of species caught is the effect of a decrease in non-linyphiid species with increasing altitude. There is no significant decline in the numbers of species of linyphiids with increase in altitude.     

Giant eosinophil colonies from cultures of bone marrow cells

Summary To date, the small size and slow growth of eosinophil colonies in vitro has hampered study of cloned eosinophils. We found enhanced eosinophil colony size and numbers in methylcellulose cultures of bone marrow cells utilizing defined supplemented bovine calf serum (DSBCS) in combination with EL4 conditioned medium (EL4-CM). At days 9, 16 and 23 significantly more eosinophil colonies and more cells/colony were present in cultures incubated with DSBCS/EL4-CM than in cultures incubated with fetal calf serum/EL4-CM. The ability to generate large numbers of eosinophils in vitro should facilitate study of cloned eosinophils. Supported in part by a grant from the National Institutes of Health, AI 20416, and by the Mayo Foundation. Editor's statement Previous approaches to in vitro culture of eosinophils generally have achieved, at best, mixed cultures of colonies of these cells and granulocyte-macrophage colonies. The improved culture methods described in this report produce more homogeneous eosinophil cultures and larger colonies of these cells. The procedure employs EL4 murine thymoma-conditioned medium, which apparently contains eosinophil colony-stimulating activity in the absence of granulocyte-macrophage colony-stimulating activity. David W. Barnes     

études sur les phénomenes électrocapillaires

Sans résuméI. Analyse électrocapillaire des matières colorantes. Rev. gén. Mat. Col. 1926 Vol. 30 pp 34–45II. Phénomènes électrocapillaires et le problème du cancer. Arch. Med. Exper. 1926 Vol. I p 381III. Phénomènes électrocapillaires et l'antagonismes microbiens. Bol. Istituto Sier. Milano 1927 Vol. VI p 313.     

Spin-labeling studies of the conformation of the Ca(2+)-regulatory protein calmodulin in solution and bound to the membrane skeleton in erythrocyte ghosts: implications to transmembrane signaling.

Electron paramagnetic resonance (EPR) studies of the Ca(2+)-regulatory protein calmodulin (CaM) have been performed. The conformation of CaM in solution changes upon binding of Ca2+ allowing the protein to bind to target proteins existing in the red blood cell membrane. In this study a maleimide spin label, covalently attached to the single cysteine residue of CaM located in the first Ca(2+)-binding domain, was used to monitor allosteric conformational changes induced by interaction of CaM with Ca2+ and subsequently with the red blood cell membrane. The results show, relative to apo-CaM, a significant increase in the apparent rotational correlation time, tau, of the spin label when Ca2+ was present in solution (P less than 0.001). When apo-CaM exposed to red blood cell membrane ghosts in the absence of Ca2+, no significant difference in spin label motion was seen relative to solution, consistent with the idea that Ca2+ is required for CaM to bind to skeletal proteins. When Ca2+ was added to CaM which was then exposed to ghosts, a highly significant increase in tau (decrease in motion) (P less than 0.000001) relative to apo-CaM exposed to ghosts was found. This latter increase in tau is significantly greater than that produced by the addition of Ca2+ to CaM in solution (P less than 0.001). The major interaction sites of CaM were found by photoaffinity labeling and autoradiography on SDS-PAGE to be on the principal skeletal protein, spectrin. EPR was also used to investigate the biophysical correlates of transmembrane signaling. Spin-labeled CaM was bound to the membrane skeleton in the presence of Ca2+.(ABSTRACT TRUNCATED AT 250 WORDS)     

Increased dependence on blood glucose after acclimatization to 4,300 m

To evaluate the hypothesis that altitude exposure and acclimatization result in increased dependency on blood glucose as a fuel, seven healthy males (23 +/- 2 yr, 72.2 +/- 1.6 kg, mean +/- SE) on a controlled diet were studied in the postabsorptive condition at sea level (SL), on acute altitude exposure to 4,300 m (AA), and after 3 wk of chronic altitude exposure to 4,300 m (CA). Subjects received a primed continuous infusion of [6,6-2D]glucose and rested for a minimum of 90 min, followed immediately by 45 min of exercise at 101 +/- 3 W, which elicited 51.1 +/- 1% of the SL maximal O2 consumption (VO2 max; 65 +/- 2% of altitude VO2 max). At SL, resting arterial glucose concentration was 82.4 +/- 3.2 mg/dl and rose significantly to 91.2 +/- 3.2 mg/dl during exercise. Resting glucose appearance rate (Ra) was 1.79 +/- 0.02 mg.kg-1.min-1; this increased significantly during exercise at SL to 3.71 +/- 0.08 mg.kg-1.min-1. On AA, resting arterial glucose concentration (85.8 +/- 4.1 mg/dl) was not different from sea level, but Ra (2.11 +/- 0.14 mg.kg-1.min-1) rose significantly. During exercise on AA, glucose concentration rose to levels seen at SL (91.4 +/- 3.0 mg/dl), but Ra increased more than at SL (to 4.85 +/- 0.15 mg.kg-1.min-1; P less than 0.05). Resting arterial glucose was significantly depressed with CA (70.8 +/- 3.8 mg/dl), but resting Ra increased to 3.59 +/- 0.08 mg.kg-1.min-1, significantly exceeding SL and AA values.(ABSTRACT TRUNCATED AT 250 WORDS)