OSCILLATOR: A system for analysis of diurnal leaf growth using infrared photography combined with wavelet transformation

ABSTRACT: BACKGROUND: Quantification of leaf movement is an important tool for characterising the effects of environmental signals and the circadian clock on plant development. Analysis of leaf movement is currently restricted by the attachment of sensors to the plant or depended on visible light for time-lapse photography. The study of leaf growth movement rhythms in mature plants under biological relevant conditions, e.g. diurnal light and dark conditions, is therefore problematic. RESULTS: Here we present OSCILLATOR, an affordable system for the analysis of rhythmic leaf growth movement in mature plants. The system contains three modules: (1) Infrared time-lapse imaging of growing mature plants (2) measurement of projected distances between leaf tip and plant apex (leaf tip tracking growth-curves) and (3) extraction of phase, period and amplitude of leaf growth oscillations using wavelet analysis. A proof-of-principle is provided by characterising parameters of rhythmic leaf growth movement of different Arabidopsis thaliana accessions as well as of Petunia hybrida and Solanum lycopersicum plants under diurnal conditions. The amplitude of leaf oscillations correlated to published data on leaf angles, while amplitude and leaf length did not correlate, suggesting a distinct leaf growth profile for each accession. Arabidopsis mutant accession Landsberg erecta displayed a late phase (timing of peak oscillation) compared to other accessions and this trait appears unrelated to the ERECTA locus. CONCLUSIONS: OSCILLATOR is a low cost and easy to implement system that can accurately and reproducibly quantify rhythmic growth of mature plants for different species under diurnal light/dark cycling.     

Impacts of earthworms and arbuscular mycorrhizal fungi (Glomus intraradices) on plant performance are not interrelated

Earthworms and arbuscular mycorrhizal fungi (AMF) might interactively impact plant productivity; however, previous studies reported inconsistent results. We set up a three-factorial greenhouse experiment to study the effects of earthworms (Aporrectodea caliginosa Savigny and Lumbricus terrestris L.) and AMF (Glomus intraradices N.C. Schenck & G.S. Sm.) on the performance (productivity and shoot nutrient content) of plant species (Lolium perenne L., Trifolium pratense L. and Plantago lanceolata L.) belonging to the three functional groups grasses, legumes and herbs, respectively. Further, we investigated earthworm performance and plant root mycorrhization as affected by the treatments. Our results accentuate the importance of root derived resources for earthworm performance since earthworm weight (A. caliginosa and L. terrestris) and survival (L. terrestris) were significantly lower in microcosms containing P. lanceolata than in those containing T. pratense. However, earthworm performance was not affected by AMF, and plant root mycorrhization was not modified by earthworms. Although AMF effectively competed with T. pratense for soil N (as indicated by δ¹⁵N analysis), AMF enhanced the productivity of T. pratense considerably by improving P availability. Remarkably, we found no evidence for interactive effects of earthworms and AMF on the performance of the plant species studied. This suggests that interactions between earthworms and AMF likely are of minor importance.     

Evapotranspiration from understory vegetation in an eastern Siberian boreal larch forest

We measured evapotranspiration in an eastern Siberian boreal forest, in which the understory was cowberry and the overstory was larch, during the entire growing seasons of 2005 and 2006. We compared evapotranspiration from the understory vegetation above the forest floor E_U with evapotranspiration from the whole ecosystem above the overstory canopy E_O. The E_U/E_O ratio had a seasonal trend with a flat-bottomed U-shape during the growing season (4 May–30 September). High-E_U/E_O ratios at the beginning and end of the growing season were observed because larch, one of the two sources of E_O, was a deciduous tree, while the understory was the evergreen cowberry. The mean daily E_U values during the foliated period of larch (1 June–31 August) were 0.8 and 0.9 mm day^?1, or 51.4 and 51.8% of E_O in 2005 and 2006, respectively. The understory vegetation was one of the most important components of the hydrologic cycle in this forest. A significant amount of E_U was caused by plant physiological control, due to the aerodynamic conductance, which was much larger than the surface conductance, leading to a smaller decoupling coefficient. We found that 71% of E_U was caused by the vapour pressure deficit above the forest floor.     

Earthworms enhance plant regrowth in a grassland plant diversity gradient

Knowledge of the role of decomposers in the plant diversity–productivity relationship is scarce. In the framework of the Jena Experiment, we observed regrowth of grassland plant communities varying in plant species and functional group richness three weeks after mowing. We investigated earthworm subplots and subplots with reduced earthworm density in order to explore if earthworms enhance plant regrowth and if earthworm effects depend on plant diversity. Earthworms significantly enhanced each of the plant regrowth parameters (plant coverage and maximum and average height of the vegetation) suggesting that particularly fast growing species, such as grasses, benefit from earthworm activity. However, the average height of the vegetation was not affected in 16-species mixtures suggesting compensation of the impact of earthworms on plant regrowth in complex plant communities.     

Element uptake in thalli of the lichen Physcia caesia from sandstone and calcareous substratum

Physcia caesia is a foliose, saxicolous lichen commonly found on weakly acidic to alkaline rock and artificial calcareous substrata. Uptake of iron and phosphate, which are known to be significant for governing the calcifuge‐calcicole behavior of lichens (as well as vascular plants), was studied in individuals of P. caesia deriving either from variegated sandstone or concrete. Samples from either substratum originated from walls erected at the same location, i.e., lichens were exposed to the same atmospheric element load and microclimate prior to the experiments. Element uptake was investigated after short‐term incubation in the laboratory involving solutions of FeCl₂, FeCl₃, and KH₂PO₄ at pH 3 and 8. Uptake of Fe²⁺ was significantly higher at either pH in the thalli from concrete than in those from sandstone, whereas Fe³⁺ uptake was not significantly different between the two groups of lichen thalli, though there was an insignificant trend for higher Fe³⁺ uptake at pH 8 in the samples from concrete. Phosphate uptake also was more efficient in thalli deriving from concrete than in those from sandstone, even though the initial P content was higher in the samples from sandstone. The results suggest that the ability of P. caesia to adapt Fe and P uptake to the pH‐dependent availabilities of these nutrients is responsible for the potential of the species to grow both on weakly acidic and alkaline substrata.     

The Effect of Melanocyte Stimulating Hormone and Hydroxyapatite on Osteogenesis in Pulp Stem Cells of Human Teeth Transferred into Polyester Scaffolds

Presently, tissue engineering is employed in the restoration and repair of tissue defects. Degradable scaffolds, stem cells and stimulating factors are employed in this method. In this study, the effect of melanocyte-stimulating hormone (MSH) and/or hydroxyapatite (HA) on proliferation, osteoblast differentiation, and mineralization of human dental pulp stem cells (hDPSCs) seeded on PLLA-PCL nanofibrous scaffolds was evaluated. For this aim, PLLA-PCL-HA nanofibrous scaffolds were fabricated using electrospinning method. FE-SEM images exhibited that all nanofibers had bead-free morphologies with average diameters ranging from 150–205 nm. Human DPSCs seeded into PLLA-PCL nanofibers were treated with MSH. Cell viability, proliferation, morphology, osteogenic potential, and the expression of tissue-specific genes were assessed by means of MTT assay, FE-SEM, alizarin red S staining, and RT-PCR analysis. hDPSCs exhibited improved adhesion and proliferation capacity on the PLLA-PCL-HA nanofibers treated with MSH compared to other groups (p<0.05). Additionally, PLLA-PCL-HA nanofibers treated with MSH exhibited significantly higher mineralization and alkaline phosphatase activity than other groups. RT-PCR results confirmed that PLLA-PCL-HA nanofibers enriched with MSH could significantly unregulated the gene expression of BMP2, osteocalcin, RUNX2 and DSPP that correlated to osteogenic differentiation (p<0.05). Based on results, incorporation of HA nanoparticles in PLLA-PCL nanofibers and addition of MSH in media exhibited synergistic effects on the adhesion, proliferation, and osteogenesis differentiation of hDPSCs, and therefore assumed to be a favorable scaffold for bone tissue engineering applications.     

Assessment of soil erosion rate trends in two agricultural regions of European Russia for the last 60 years

Purpose

Forest–steppe and the southern forest ecotones of European Russia (ER) are the most productive agricultural areas in Russia. Both climate and land use changes have occurred within the ER during last 30 years. These changes can lead to changes in the timing, magnitude, and spatial distribution of soil erosion rates on cultivated lands. The objective of this research was to assess the trends in soil erosion rates since the 1960s for two agricultural regions of ER.

Materials and methods

Rates of soil erosion were estimated for two time windows (1963–1986 and 1986–2015) within the two agricultural regions. Both regions are characterized by a high proportion of cropland (>?60%), and within each region, one river basin and one 1st–3rd-order agricultural catchment were selected for a detailed assessment of soil erosion rates. Erosion models and visual interpretation of satellite images were used for the evaluation of the erosion rates for the river basins. Sediment budget assessments, ¹³⁷Cs dating, geomorphologic mapping, and erosion models were used for the evaluation of the sediment redistribution for the two time windows in agricultural catchments.

Results and discussion

At the river basin scale, the mean annual erosion rate did not change in the western part of forest–steppe ecotone; however, there was a weak negative trend in the mean annual erosion rate for the eastern part of the southern forest ecotone. A large negative trend in the erosion rate was found for both small agricultural catchments. In all cases, the reduction in the erosion rates was mainly associated with a decrease of surface runoff during snowmelt, as a result of an increase in both the air and soil temperatures during winter season. The soil loss reduction during snowmelt was counteracted by an equal increase in rainfall erosion due to increase of rainfall intensity in western part of forest–steppe ecotone.

Conclusions

Reduction of surface runoff during spring snowmelt was the main reason the erosion rates declined on cultivated lands within the forest–steppe and southern forest ecotones of ER. Evaluation of ephemeral gully erosion rate was not incorporated into State Hydrological Institute erosion model used for the evaluation of the soil losses during snowmelt. This has led to an underestimation of the total soil losses for the 1963–1986 time window for all study sites.

     

Auxin production by rhizobacteria was associated with improved yield of wheat (Triticum aestivum L.) under drought stress

Drought tolerant rhizobacteria of the genus Bacillus, Enterobacter, Moraxella and Pseudomonas colonizing the root system of Acacia arabica were isolated to mitigate the drought stress of wheat (Triticum aestivum L.). In vitro auxin production by rhizobacteria was quantified by Ultra High Performance Liquid Chromatography (UPLC). Analysis of the crude extracts detected the indole-3-acetic acid (IAA), indole-3-carboxylic acid (ICA) and indole-3-lactic acid (ILA). Highest IAA production of 25.9 µg ml^?1 was observed for Bacillus amyloliquefaciens S-134. Pot trials were conducted to evaluate the role of rhizobacteria to enhance the growth of wheat at different water regimes. At highest water stress i.e. 10% field capacity (FC), significant improvement of shoot length was observed with B. amyloliquefaciens S-134. For yield parameters, B. muralis D-5 and E. aerogenes S-10 recorded 34% and 1 fold increases for spike length and seed weight, over respective control at 10% FC. Mixed culture combinations of M-2 (B. thuringiensis S-26, D-2, B. amyloliquefaciens S-134, B. simplex D-11) and M-3 (M. pluranimalium S-29, B. simplex D-1, B. muralis D-5, P. stutzeri S-80) showed significant improvement for tillers and number of spikelets. In conclusion, application of the drought tolerant rhizobacteria can help to overcome productivity losses in drought prone areas.     

Measurement of intraocular pressure in healthy anesthetized horses during hoisting

Objective

To measure intraocular pressure (IOP) in horses during hoisting after induction of anesthesia.

Comparing population growth rates using weighted bootstrapping: Guiding the conservation management of Petrogale xanthopus xanthopus (yellow-footed rock-wallaby)

In this study we compare estimates of the long-term mean stochastic population growth rates, E[r] for Petrogale xanthopus xanthopus (yellow-footed rock-wallaby), a threatened Australian species. In fluctuating environments such as semi-arid areas, herbivore populations respond directly to changes in the biomass of food resources. Biomass is generally correlated with rainfall, so it is often useful to model annual population growth rates of herbivores directly with rainfall. Models of this nature are referred to as numerical response models. The factors that are thought to threaten this species include competition from introduced herbivores and predation from foxes. Annual aerial survey data collected from 1997 to 2004 over approximately 600 km of transect line were analyzed in seven zones within South Australia. Using the Ivlev numerical response model, the annual population growth rates were found to correlate best with the rain that fell in the seven-month period immediately prior to the surveys. Not surprisingly, positive growth rates were found to be associated with higher rainfalls in this period, while negative growth rates were associated with lower rainfalls. We also used weighted bootstrapping to calculate confidence intervals around our estimates of long-term mean stochastic population growth rates, E[r]. The findings suggest that the estimates of E[r] are positive in areas where there is fox and herbivore management. However, we found no evidence that this species will decline in the absence of these treatments.