Importance of carbon dioxide physiological forcing to future climate change

An increase in atmospheric carbon dioxide (CO2) concentration influences climate both directly through its radiative effect (i.e., trapping longwave radiation) and indirectly through its physiological effect (i.e., reducing transpiration of land plants). Here we compare the climate response to radiative and physiological effects of increased CO2 using the National Center for Atmospheric Research (NCAR) coupled Community Land and Community Atmosphere Model. In response to a doubling of CO2, the radiative effect of CO2 causes mean surface air temperature over land to increase by 2.86 ± 0.02 K (± 1 standard error), whereas the physiological effects of CO2 on land plants alone causes air temperature over land to increase by 0.42 ± 0.02 K. Combined, these two effects cause a land surface warming of 3.33 ± 0.03 K. The radiative effect of doubling CO2 increases global runoff by 5.2 ± 0.6%, primarily by increasing precipitation over the continents. The physiological effect increases runoff by 8.4 ± 0.6%, primarily by diminishing evapotranspiration from the continents. Combined, these two effects cause a 14.9 ± 0.7% increase in runoff. Relative humidity remains roughly constant in response to CO2-radiative forcing, whereas relative humidity over land decreases in response to CO2-physiological forcing as a result of reduced plant transpiration. Our study points to an emerging consensus that the physiological effects of increasing atmospheric CO2 on land plants will increase global warming beyond that caused by the radiative effects of CO2.

Climate response to physiological forcing of carbon dioxide simulated by the coupled Community Atmosphere Model (CAM3.1) and Community Land Model (CLM3.0)

Increasing concentrations of atmospheric CO2 decrease stomatal conductance of plants and thus suppress canopy transpiration. The climate response to this CO2-physiological forcing is investigated using the Community Atmosphere Model version 3.1 coupled to Community Land Model version 3.0. In response to the physiological effect of doubling CO2, simulations show a decrease in canopy transpiration of 8%, a mean warming of 0.1K over the land surface, and negligible changes in the hydrological cycle. These climate responses are much smaller than what were found in previous modeling studies. This is largely a result of unrealistic partitioning of evapotranspiration in our model control simulation with a greatly underestimated contribution from canopy transpiration and overestimated contributions from canopy and soil evaporation. This study highlights the importance of a realistic simulation of the hydrological cycle, especially the individual components of evapotranspiration, in reducing the uncertainty in our estimation of climatic response to CO2-physiological forcing. Citation: Cao, L., G. Bala, K. Caldeira, R. Nemani, and G.Ban-Weiss (2009), Climate response to physiological forcing of carbon dioxide simulated by the coupled Community Atmosphere Model (CAM3.1) and Community Land Model (CLM3.0).

Influence of land use changes in river basins on diversity and distribution of amphibians

Land-use changes influence local biodiversity directly, and also cumulatively, contribute to regional and global changes in natural systems and quality of life. Consequent to these, direct impacts on the natural resources that support the health and integrity of living beings are evident in recent times. The Western Ghats being one of the global biodiversity hotspots, is reeling under a tremendous pressure from human induced changes in terms of developmental projects like hydel or thermal power plants, big dams, mining activities, unplanned agricultural practices,monoculture plantations, illegal timber logging, etc. This has led to the once contiguous forest habitats to be fragmented in patches, which in turn has led to the shrinkage of original habitat for the wildlife, change in the hydrological regime of the catchment, decreased inflow in streams,human-animal conflicts, etc. Under such circumstances, a proper management practice is called for requiring suitable biological indicators to show the impact of these changes, set priority regions and in developing models for conservation planning. Amphibians are regarded as one of the best biological indicators due to their sensitivity to even the slightest changes in the environment and hence they could be used as surrogates in conservation and management practices. They are the predominating vertebrates with a high degree of endemism (78%) in Western Ghats. The present study is an attempt to bring in the impacts of various land-uses on anuran distribution in three river basins. Sampling was carried out for amphibians during all seasons of 2003-2006 in basins of Sharavathi, Aghanashini and Bedthi. There are as many as 46 species in the region, one of which is new to science and nearly 59% of them are endemic to the Western Ghats. They belong to nine families, Dicroglossidae being represented by 14 species,followed by Rhacophoridae (9 species) and Ranidae (5 species). Species richness is high in Sharavathi river basin, with 36 species, followed by Bedthi 33 and Aghanashini 27. The impact of land-use changes, was investigated in the upper catchment of Sharavathi river basin. Species diversity indices, relative abundance values, percentage endemics gave clear indication of differences in each sub-catchment. Karl Pearson’s correlation coefficient (r) was calculated between species richness, endemics, environmental descriptors, land-use classes and fragmentation metrics. Principal component analysis was performed to depict the influence of these variables. Results show that sub-catchments with lesser percentage of forest, low canopy cover, higher amount of agricultural area, low rainfall have low species richness, less endemic species and abundant non-endemic species, whereas endemism, species richness and abundance of endemic species are more in the sub-catchments with high tree density, endemic trees, canopy cover, rainfall and lower amount of agriculture fields. This analysis aided in prioritising regions in the Sharavathi river basin for further conservation measures.

Constrained Linear Spectral Unmixing Technique for Regional Land Cover Mapping Using MODIS Data

Over the last few decades, there has been a significant land cover (LC) change across the globe due to the increasing demand of the burgeoning population and urban sprawl. In order to take account of the change, there is a need for accurate and up-to-date LC maps. Mapping and monitoring of LC in India is being carried out at national level using multi-temporal IRS AWiFS data. Multispectral data such as IKONOS, Landsat-TM/ETM+, IRS-ICID LISS-III/IV, AWiFS and SPOT-5, etc. have adequate spatial resolution (similar to 1m to 56m) for LC mapping to generate 1:50,000 maps. However, for developing countries and those with large geographical extent, seasonal LC mapping is prohibitive with data from commercial sensors of limited spatial coverage. Superspectral data from the MODIS sensor are freely available, have better temporal (8 day composites) and spectral information. MODIS pixels typically contain a mixture of various LC types (due to coarse spatial resolution of 250, 500 and 1000 in), especially in more fragmented landscapes. In this context, linear spectral unmixing would be useful for mapping patchy land covers, such as those that characterise much of the Indian subcontinent. This work evaluates the existing unmixing technique for LC mapping using MODIS data, using end-members that are extracted through Pixel Purity Index (PPI), Scatter plot and N-dimensional visualisation. The abundance maps were generated for agriculture, built up, forest, plantations, waste land/others and water bodies. The assessment of the results using ground truth and a LISS-III classified map shows 86% overall accuracy, suggesting the potential for broad-scale applicability of the technique with superspectral data for natural resource planning and inventory applications. Index Terms-Remote sensing, digital

On the measurement of the surface energy budget over a land surface during the summer monsoon

The measurement of surface energy balance over a land surface in an open area in Bangalore is reported. Measurements of all variables needed to calculate the surface energy balance on time scales longer than a week are made. Components of radiative fluxes are measured while sensible and latent heat fluxes are based on the bulk method using measurements made at two levels on a micrometeorological tower of 10 m height. The bulk flux formulation is verified by comparing its fluxes with direct fluxes using sonic anemometer data sampled at 10 Hz. Soil temperature is measured at 4 depths. Data have been continuously collected for over 6 months covering pre-monsoon and monsoon periods during the year 2006. The study first addresses the issue of getting the fluxes accurately. It is shown that water vapour measurements are the most crucial. A bias of 0.25% in relative humidity, which is well above the normal accuracy assumed the manufacturers but achievable in the field using a combination of laboratory calibration and field intercomparisons, results in about 20 W m(-2) change in the latent heat flux on the seasonal time scale. When seen on the seasonal time scale, the net longwave radiation is the largest energy loss term at the experimental site. The seasonal variation in the energy sink term is small compared to that in the energy source term.

Triploid plants from endosperm cultures of sandalwood by experimental embryogenesis

Embryogenesis has been induced from endosperm callus cultures of sandalwood (Santalum album L.). Viable plantlets developed from the embryoids on subculture to White's basal medium supplemented with 0.5 mg/l of indole acetic acid. Chromosomal analysis of the root tips showed the triploid number 3n = 30.

How Good is the Assumption About Visible Surface Reflectance in MODIS Aerosol Retrieval Over Land? A Comparison With Aircraft Measurements Over an Urban Site in India

In this paper, we discuss the measurements of spectral surface reflectance (rho(s)(lambda)) in the wavelength range 350-2500 nm measured using a spectroradiometer onboard a low-flying aircraft over Bangalore (12.95 degrees N, 77.65 degrees E), an urban site in southern India. The large discrepancies in the retrieval of aerosol propertiesover land by the Moderate-Resolution Imaging Spectroradiometer (MODIS), which could be attributed to the inaccurate estimation of surface reflectance at many sites in India and elsewhere, provided motivation for this paper. The aim of this paper was to verify the surface reflectance relationships assumed by the MODIS aerosol algorithm for the estimation of surface reflectance in the visible channels (470 and 660 nm) from the surface reflectance at 2100 nm for aerosol retrieval over land. The variety of surfaces observed in this paper includes green and dry vegetations, bare land, and urban surfaces. The measuredreflectance data were first corrected for the radiative effects of atmosphere lying between the ground and aircraft using the Second Simulation of Satellite Signal in the Solar Spectrum (6S) radiative transfer code. The corrected surface reflectance in the MODIS's blue (rho(s)(470)), red (rho(s)(660)), and shortwave-infrared (SWIR) channel (rho(s)(2100)) was linearly correlated. We found that the slope of reflectance relationship between 660 and 2100 nm derived from the forward scattering data was 0.53 with an intercept of 0.07, whereas the slope for the relationship between the reflectance at 470 and 660 nm was 0.85. These values are much higher than the slope (similar to 0.49) for either wavelengths assumed by the MODIS aerosol algorithm over this region. The reflectance relationship for the backward scattering data has a slope of 0.39, with an intercept of 0.08 for 660 nm, and 0.65, with an intercept of 0.08 for 470 nm. The large values of the intercept (which is very small in the MODIS reflectance relationships) result in larger values of absolute surface reflectance in the visible channels. The discrepancy between the measured and assumed surface reflectances could lead to error in the aerosol retrieval. The reflectance ratio (rho(s)(660)/rho(s)(2100)) showed a clear dependence on the N D V I-SWIR where the ratio increased from 0.5 to 1 with an increase in N V I-SWIR from 0 to 0.5. The high correlation between the reflectance at SWIR wavelengths (2100, 1640, and 1240 nm) indicated an opportunity to derive the surface reflectance and, possibly, aerosol properties at these wavelengths. We need more experiments to characterize the surface reflectance and associated inhomogeneity of land surfaces, which play a critical role in the remote sensing of aerosols over land.

Studies on nucleotidases in plants : Reversible denaturation of the crystalline mung bean nucleotide pyrophosphatase and the effect of adenylates on the native and renatured enzyme

The crystalline mung bean nucleotide pyrophosphatase was inhibited nonlinearly by AMP, one of the products of the reaction. The partially inactive enzyme was specifically reactivated by ADP, and V at maximal activation was the same as that of the native enzyme. ATP was a linear, noncompetitive inhibitor. The kinetic evidence suggested that ADP and ATP might not be reacting at the same site as AMP. The electrophoretic mobility of the enzyme was increased by AMP, whereas ADP and ATP were without effect. The enzyme was denatured on treatment with urea or guanidine hydrochloride. The renatured and the native enzyme had the same pH (9.4) and temperature (49 °C) optimum. The Km (0.2 mImage ) and V (3.2) of the native enzyme increased on renaturation to 1.8 mImage and 8.0, respectively. In addition, renaturation resulted in desensitization of the enzyme to inhibition by low concentrations of AMP. Renaturation did not affect the reactivation of the apoenzyme by Zn2+.

oxidation of catechol in plants iv. purification and properties of the 3,4,3',4'-tetrahydroxydiphenyl-forming enzyme system from tecoma leaves

Acetone powders prepared from leaf extracts of Tecoma stans L. were found to catalyze the oxidation of catechol to 3,4,3',4'-tetrahydroxydiphenyl. Fractionation of the acetone powders obtained from Tecoma leaves with acetone, negative adsorption of the acetone fraction with tricalcium phosphate gel, and chromatography of the gel supernatant on DEAE-Sephadex yielded a 68-fold purified enzyme with 66% recovery. The enzyme had an optimum pH around 7.2. It showed a temperature optimum of 30° and the Km for catechol was determined as 2 x 10-4 m. The purified enzyme moved as a single band on polyacrylamide gel electrophoresis. Its activity was found to be partially stimulated by Mg2+. The reaction was not inhibited by o-phenanthroline and agr,agr'-dipyridyl. The purified enzyme was highly insensitive to a range of copper-chelating agents. It was not affected appreciably by thiol inhibitors. The reaction was found to be suppressed to a considerable extent by reducing agents like GSH, cysteine, cysteamine, and ascorbic acid. The purified enzyme was remarkably specific for catechol. Catalase affected neither the enzyme activity nor the time course of the reaction. Hydrogen peroxide was not formed as a product of the reaction.

Triacylglycerol lipases of yeast and plants: more than just hydrolases

In the yeast, mobilization of triacylglycerols (TAG) is facilitated by TGL3, TGL4 and TGL5 gene products. Interestingly, experiments using [32P] orthophosphate as a precursor for complex glycerophospholipids revealed that tgl mutants had a lower steady-state level of these membrane lipids. To understand a possible link between TAG lipolysis and phospholipid metabolism, we performed overexpression studies with Tgl3p and Tgl5p which clearly demonstrated that these two enzymes enhanced the level of phospholipids. Domains and motifs search analyses indicated that yeast TAG hydrolases posses a GXSXG lipase motif but also a HX4D acyltransferase motif. Purified Tgl3p and Tgl5p did not only exhibit TAG lipase activity but also catalyzed acyl-CoA dependent acylation of lyso-phosphatidylethanolamine and lyso-phosphatidic acid (LPA), respectively. Search for lipase/hydrolase homologues in the Arabidopsis thaliana genome led to the identification of At4g24160 which possess three motifs that are conserved across the plant species such as GXSXG motif, a HX4D motif and a probable lipid binding motif V(X)3HGF. Characterization of At4g24160 expressed in bacteria revealed that the presence of an acyl-CoA dependent LPA acyltransferase activity. In addition, the purified recombinant At4g24160 protein hydrolyzed both TAG and phosphatidylcholine. We hypothesize that the plant enzyme may be involved in membrane repair. In summary, our results indicate that these TAG lipases play a dual role and thereby contribute to both anabolic and catabolic processes in yeast and plants.

Studies on nucleotidases in plants - Reversible denaturation of the crystalline mung bean nucleotide pyrophosphatase and the effect of adenylates on the native and renatured enzyme

The crystalline mung bean nucleotide pyrophosphatase was inhibited nonlinearly by AMP, one of the products of the reaction. The partially inactive enzyme was specifically reactivated by ADP, and V at maximal activation was the same as that of the native enzyme. ATP was a linear, noncompetitive inhibitor. The kinetic evidence suggested that ADP and ATP might not be reacting at the same site as AMP. The electrophoretic mobility of the enzyme was increased by AMP, whereas ADP and ATP were without effect. The enzyme was denatured on treatment with urea or guanidine hydrochloride. The renatured and the native enzyme had the same pH (9.4) and temperature (49 °C) optimum. The Km (0.2 m ) and V (3.2) of the native enzyme increased on renaturation to 1.8 m and 8.0, respectively. In addition, renaturation resulted in desensitization of the enzyme to inhibition by low concentrations of AMP. Renaturation did not affect the reactivation of the apoenzyme by Zn2+.

Studies on nucleotidases in plants Dimerization of the crystalline mung bean nucleotide pyrophosphatase by 5-adenosine monophosphate and the properties of the dimerized enzyme

The addition of AMP to the crystalline and homogeneous mung bean nucleotide pyrophosphatase [EC 3.6.1.9]altered its electrophoretic mobility. AMP was tightly bound to the enzyme and was not removed on passage through a column of Sephadex G-25 or on electrophoresis. The molecular weight of the native and AMP-modified enzymes were 65,000 and 136,000, respectively. The properties of the native enzyme such as the pH (9.4) and temperature (49 °C) optima, inhibition by EDTA, reversal of EDTA-inhibition by Zn2+ and Co2+, were not altered on dimerization by AMP. The AMP-modified enzyme had a linear time-course of reaction, unlike the native enzyme which exhibited a biphasic time-course of reaction. The AMP-modified enzyme was irreversibly denatured by urea. AMP concentrations larger than 100 μM inhibited linearly the activity of the AMP-modified enzyme. ADP and ATP inhibited the activity in a sigmoidal manner. Km and V of the native and AMP-modified enzymes were, 0.25 mImage and 0.58 mImage ; and 3.3 and 2.5, respectively.

An ethnobotanical study of traditional anti-inflammatory plants used by the Lohit community of Arunachal Pradesh, India

Aim of the study: Most people especially in rural areas depend on herbal medicines to treat many diseases including inflammation-related ailments such as rheumatism, muscle swelling, cut wound, accidental bone fracture, insect bites, pains and burn by fire and hot water. The objectives of this study were: to catalog ethno-medicinal plants of Lohit community, ecological status, indigenous folk medicinal uses, morphological parts used and to determine their reported pharmacological studies. Materials and methods: The ethnobotanical information on traditional medicinal plants exclusively used for management of inflammation-related ailments by the Khampti community of Arunachal Pradesh, India was based on first-hand field survey work through semi-structured interviews. Results and conclusion: A total of 34 species in 32 genera and 22 families were encountered during the field survey. Botanical families such as Asteraceae, Euphorbiaceae, Zingiberaceae and Lamiaceae were represented by the highest numbers of species reported in this study. Thirteen plant species, namely: Bombax ceiba, Canarium strictum, Chloranthus erectus, Xanthium indicum, Lycopodium clavatum, Coleus blumei, Batrachospermum atrum, Chlorella vulgaris, Marchantia palmata, Marchantia polymorpha, Eria pannea, Sterculia villosa and Alpinia galanga are reported for the first time for the treatment of inflammation-related diseases.