Root oxygen loss from Raphia taedigera palms mediates greenhouse gas emissions in lowland neotropical peatlands

Plant and Soil - Little is known about the influence of vegetation on the timing and quantities of greenhouse gas fluxes from lowland Neotropical peatlands to the atmosphere. To address this...     

CH4 and N2O emissions from smallholder agricultural systems on tropical peatlands in Southeast Asia

There are limited data for greenhouse gas (GHG) emissions from smallholder agricultural systems in tropical peatlands, with data for non-CO₂ emissions from human-influenced tropical peatlands particularly scarce. The aim of this study was to quantify soil CH₄ and N₂O fluxes from smallholder agricultural systems on tropical peatlands in Southeast Asia and assess their environmental controls. The study was carried out in four regions in Malaysia and Indonesia. CH₄ and N₂O fluxes and environmental parameters were measured in cropland, oil palm plantation, tree plantation and forest. Annual CH₄ emissions (in kg CH₄ ha⁻¹ year⁻¹) were: 70.7 ± 29.5, 2.1 ± 1.2, 2.1 ± 0.6 and 6.2 ± 1.9 at the forest, tree plantation, oil palm and cropland land-use classes, respectively. Annual N₂O emissions (in kg N₂O ha⁻¹ year⁻¹) were: 6.5 ± 2.8, 3.2 ± 1.2, 21.9 ± 11.4 and 33.6 ± 7.3 in the same order as above, respectively. Annual CH₄ emissions were strongly determined by water table depth (WTD) and increased exponentially when annual WTD was above −25 cm. In contrast, annual N₂O emissions were strongly correlated with mean total dissolved nitrogen (TDN) in soil water, following a sigmoidal relationship, up to an apparent threshold of 10 mg N L⁻¹ beyond which TDN seemingly ceased to be limiting for N₂O production. The new emissions data for CH₄ and N₂O presented here should help to develop more robust country level ‘emission factors’ for the quantification of national GHG inventory reporting. The impact of TDN on N₂O emissions suggests that soil nutrient status strongly impacts emissions, and therefore, policies which reduce N-fertilisation inputs might contribute to emissions mitigation from agricultural peat landscapes. However, the most important policy intervention for reducing emissions is one that reduces the conversion of peat swamp forest to agriculture on peatlands in the first place.     

Innervation of skin glands in the frog

Summary A comparative study was undertaken on the innervation of mucous and granular glands in frog skin. Results obtained by the Falck-Hillarp fluorescence technique and cholinesterase staining indicated that both types of glands receive exclusively adrenergic innervation. Electron microscopy was used to investigate the innervation pattern at the ultrastructural level. The distribution of nerve terminals was found to differ in the two types of glands. In the mucous gland, terminals were found at a distance of about 0.5 m from the basement membrane but never within the gland parenchyma. In the granular gland, the terminals were located between smooth muscle cells and also in direct contact with the secretory epithelium but never outside the basement membrane.This work was carried out in part at King Gustaf V:s Forskningsinstitut, Stockholm, and was supported by a grant from Karolinska Institutet     

Deuterium transfer from [1,1-2-H] ethanol during metabolism of bile acids and cyclohexanone in the isolated perfused rat liver.

Deuterium transfer from [1,1-2-H]ethanol (95 atoms % excess) to reducible substrates was studied in the isolated perfused rat liver. The dueterium excess in cyclohexanol formed from cyclohexanone was somewhat lower (49 atoms%) than found under conditions in vivo, and this was also true of the deuterium excess in lithocholic acid formed from 3-oxo-5beta-cholanoic acid. These results may reflect a slower rate of ethanol oxidation in the isolated organ than in vivo. Cycloserine decreased the dueterium transfer to both substrates, whereas addition of lactate and malate resulted in an increased deuterium excess in cyclohexanol and a decreased deuterium excess in lithocholic acid. Addition of heavy water to the perfusion fluid resulted in labelling at C-3 of lithocholic acid formed from 3-oxo-5beta-cholanoic acid, and at C-3, C-4 and C-5 of 3alpha-hydroxy-5alpha-cholanoic acid formed from 3-oxo-4-cholenoic acid. The deuterium excess of hydrogens derived from NADPH (at C-3 and C-5) was approximately the same as that of hydrogen derived directly from water (at C-4). Thus, the hydrogen of NADPH is extensively exchanged with protons of water, which explains the dilution of deuterium with protium during the transfer from [1,1-2-H]ethanol via NADPH to the bile acids. The labelling at C-5 in the reduction of the 4,5-double bond indicates that different pools of NADPH are used for reduction of this double bond and the 3-oxo group, since in a previous study it was shown that deuterium is transferred from [1,1-2-H]ethanol only in the latter reaction.     

Electrophoretic and immunological charactorization of rat neurophysin

1. The electrophoretic properties of rat posterior pituitary proteins have been compared on starch gel with those of bovine and porcine neurophysins. 2. [(35)S]-Cysteine was injected into the supraoptic nucleus of male rats and 16-24h later the distribution of labelled neural-lobe protein in starch and polyacrylamide gels was determined. In both systems a single major protein component was found to contain more than 80% of the total recovered radioactivity. Between 5 and 10% of the radioactivity was found in a minor component in polyacrylamide gel. 3. In agar, microimmuno-diffusion and -electrophoresis of the rat neural-lobe proteins gave a single arc with neurophysin antiserum, and after starch-gel electrophoresis this arc was shown to be due to the major labelled component. 4. The molecular weights of the rat neural-lobe proteins were estimated by polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate. The molecular weight of the major labelled component was found to be 12000. 5. It is concluded that the rat neurophysin consists of one major and possibly one minor component.     

Some quantitative aspects of the labelling of proteins with 125I by the iodine monochloride method

The labelling of proteins by the iodine monochloride method was studied by using a mathematical model. The equations used were primarily derived from the mass law equation of the isotopic exchange reaction between [¹²⁵I]iodide and iodine monochloride. For convenient application, all equations were programmed into a computing desk-top calculator. To support the validity of the theoretical model, a series of iodinations of insulin were performed under various labelling conditions. The results of these experiments compare well with the theoretically derived values. Deviations from the theoretical values occurring at molar ratios of [¹²⁵I]iodide to iodine monochloride < 0.1 and > 4.0 are explained and suggestions made about how to prevent them. The mathematical model was used to simulate the isotopic exchange, and the iodination reaction under various conditions, to study (a) the influence of the amount of [¹²⁵I]iodide on the amount of [¹²⁵I]iodine monochloride formed, (b) the influence of the specific radioactivity of [¹²⁵I]iodide on the amount of [¹²⁵I]iodine monochloride formed, and (c) the influence of the specific radioactivity of [¹²⁵I]iodide on the number of millicuries needed for labelling to a desired extent.     

Histochemical and chemical studies on pre- and postnatal development of the different systems of “short” and “long” adrenergic neurons in peripheral organs of the rat

Summary The adrenergic innervation in the submaxillary gland, heart, kidney, small intestine, and accessory male genital organs and the development of the adrenal chromaffin cells and the sympathetic ganglia were studied in the rat from 15 days post coitum to 16 days post partum using the fluorescence histochemical method of Falck and Hillarp. The postnatal development of the noradrenaline concentrations in the heart and vas deferens was followed by fluorometric determinations.At about 15 days post coitum, the anlagen of the sympathetic chains were well visible in the form of two dorsal segmented columns of small branching sympathicoblasts exhibiting an intense catecholamine fluorescence. In the midline, ventrally to these two anlagen, another column of sympathicoblasts developed; this seemed to give rise to the prevertebral ganglia and to the short adrenergic neurons supplying the internal genital organs. At the level of the adrenal anlagen, small intensely fluorescent chromaffin cells were collected in two bilateral groups which became enclosed by adreno-cortical cells. This enclosure was, however, not complete even at two weeks post partum.Bundles of growing sympathetic nerves were visible in the periphery of the various organs studied at 19–21 days post coitum. A terminal innervation of the organs suggestive of a functional transmitter mechanism did not start to establish until at or immediately after birth. The final pattern of innervation was usually reached at about one week post partum, and the following development proceeded largely in the form of a quantitative increase in the number of nerves participating in the innervation apparatus. The adult level of noradrenaline in the heart and vas deferens was reached three to five weeks after birth. The small intestine was an exception in that the final pattern of innervation in the wall was attained immediately after birth.There was no overt difference in the rate of development of the terminal sympathetic innervation in organs supplied by short adrenergic neurons (accessory male genital organs) compared to the innervation of the submaxillary gland, heart and kidney, which receive classical long adrenergic neurons.The work was supported by a grant from the Association for the Aid of Crippled Children, New York, and was carried out within a research organization sponsored by the Swedish Medical Research Council (grants No. B71-14X-56-07A and B71-14X-712-06A).     

Effect of colchicine on axonal transport and morphology of retinal ganglion cells

Summary Intraocular injection of colchicine in doses which do not affect the protein synthesis in the retina has profound effects on the axonal transport of protein in the retinal ganglion cells of the rabbit. Rapid axonal transport in these cells is completely inhibited after treatment with relatively low amounts of colchicine. In contrast to this, a certain fraction of the slow axonal transport is resistant to colchicine treatment. Colchicine in doses which completely inhibits fast axonal transport caused discrete morphological changes in the perikaryon and in the axon of the retinal ganglion cell. No disappearance of microtubules and no general proliferation of neurofilaments was observed in the perikaryon of the retinal ganglion cells. There was a slight or moderate increase in the number of filaments in the intra-retinal part of the axons of the retinal ganglion cells.This work has been supported by grants from the Swedish Medical Research Council (B71-12X-2543-03, B71-13X-2226-05A) and the Swedish National Cancer Society (265-B70-02X).