Soil Temperature Influences on Root Resistance of Pinus contorta Seedlings

The influence of low temperature in the root zone on water uptake in lodgepole pine (Pinus contorta Dougl. ex Loud.) was studied under laboratory conditions. To remove soil hydraulic influences, two-year-old seedlings were transferred to solution cultures and maintained in temperature controlled water baths. Short term measurements of leaf conductance, leaf water potential and tritiated water movement were taken at root temperatures from 22 C down to 0 C. Root resistance was calculated to be 67% of total plant resistance at 7 C and 93% at 0 C. In addition an Arrhenius break was found in a plant resistance versus temperature plot, suggesting a significant change with temperature in the membrane pathway in the root water uptake system.     

The histochemistry of colonic mucins.

This presentation could perhaps better be titled the histochemistry of colonic mucins, as based upon PAS reactivity, since it mainly concerns development of methods for the identification of the various patterns of o-acylation of sialic acid as measured by alteration in PAS staining.     

Degradation of the endosperm cell walls of Lactuca sativa L., cv. grand rapids in relation to the mobilisation of proteins and the production of hydrolytic enzymes in the axis,cotyledons and endosperm

The timing of changes in total nitrogen and soluble amino nitrogen content, and in the activities of proteinase (pH 7.0), isocitrate lyase, catalase, phytase, phosphatase (pH 5.0), -galactosidase and -mannosidase were studied in extracts from the cotyledons, axis and endosperms of germinating and germinated light-promoted lettuce seeds. The largest amount of total nitrogen (2.7% seed dry weight) occurs within the cotyledons, as storage protein. As this decreases the total nitrogen content of the axis increases and the soluble amino nitrogen in the cotyledons and axis increases. Proteinase activity in the cotyledons increases coincidentally with the depletion of total nitrogen therein. Enzymes for phytate mobilisation and for gluconeogenesis of hydrolysed lipids increase in activity in the cotyledons as the appropriate stored reserves decline. Beta-mannosidase, an enzyme involved in the hydrolysis of oligo-mannans released by the action of endo--mannase on mannan reserves in the endosperm, arises within the cotyledons. This indicates that complete hydrolysis of mannans to the monomer does not occur within the endosperm. Mobilisation of all cotyledon reserves occurs after the endosperm has been degraded, providing further evidence that the endosperm is an early source of food reserves for the growing embryo.Abbreviations HEPES N-2-hydroxyethylpiperazine-N-2-ethanesulphonic acid - EDTA ethylenediamine tetraacetic acid disodium salt - TCA trichloroacetic acid Part 2 of a series, of which the first was published in Planta 139, 1–8 (1978)     

Autoradiographic studies with 3H 1,25 (OH)2 vitamin D3 and 3H 25 (OH) vitamin D3 in rat parathyroid glands

Summary After injection of radiolabeled 1,25 (OH)₂ vitamin D₃, nuclear concentration of radioactivity is observed in parenchymal cells of the parathyroid gland in pregnant, adult male, and 10-day male neonatal rats. In competition studies with unlabeled 1,25 (OH)₂ vitamin D₃, but not with 25 (OH) vitamin D₃, nuclear uptake is prevented. Experiments with ³H 25 (OH) vitamin D₃, in contrast to ³H 1,25 (OH)₂ vitamin D₃, do not show nuclear concentration in cells of the parathyroid. The results of the autoradiographic studies suggest the presence of receptors for a direct effect of 1,25 (OH)₂ vitamin D₃ on the parathyroid gland for modulation of parathyroid hormone secretion.     

Inhibition of glycoconjugate secretion by colchicine and cytochalasin B

Summary The effects have been analyzed of cytochalasin B and colchicine on the secretion of glycoconjugates by human bronchial expiants labeled in vitro with radioactive glucosamine. Both cytochalasin B and colchicine had no effect on baseline ¹⁴C-labeled glycoconjugate release but caused a dose-dependent (10^–7–10^–4 M) inhibition of ¹⁴C-glycoconjugate release and discharge of labeled macromolecules from mucous and serous cells induced by 5 · 10^–5 M methacholine.Quantitative autoradiographic analyses showed that neither cytochalasin B nor colchicine inhibited ³H-threonine or ³H-glucosamine incorporation into mucous and serous cells of the submucosal glands or goblet cells of the airway epithelium. Colchicine (10^–5 M) but not cytochalasin B significantly reduced the rate at which labeled macromolecules were transported through mucous, serous and goblet cells but this effect was not observed until 4 h after the addition of colchicine. Neither cytochalasin B nor colchicine affected the basal rate of labeled-macromolecule discharge from mucous, serous or goblet cells. At a concentration of 10^–5 M, both agents completely inhibited the increase in labeled-macromolecule discharge induced in mucous and serous cells by methacholine.Our results suggest that in the submucosal gland of human airways microtubules and microfilaments may be important in secretagogue-induced but not in baseline cellular glycoconjugate discharge, implying that the mechanisms of the two processes differ significantly. Furthermore, a role for microtubules is suggested in the transport of secretory granules through mucous, serous and goblet cells.Supported by National Institutes of Health Research Grant 5R01HL22444. The authors gratefully acknowledge the technical assistance of Mr. Tudor Williams, Mr. Eduardo Quintanilla and Ms. Maureen Hayes     

The structure and enzymic activities of the C1r and C1s subcomponents of C1, the first component of human serum complement.

The subcomponents C1r and C1s and their activated forms C-1r and C-1s were each found to have mol.wts. in dissociating solvents of about 83000. The amino acid compositions of each were similar, but there were significant differences in the monosaccharide analyses of subcomponents C1r and C1s, whether activated or not. Subcomponents C1r and C1s have only one polypeptide chain, but subcomponents C-1r and C-1s each contain two peptide chains of approx. mol.wts. 56000 ("a" chain) and 27000 ("b" chain). The amino acid analyses of the "a" chains from each activated subcomponent are similar, as are those of the "b" chains. The N-terminal amino acid sequence of 29 residues of the C-1s "a" chain was determined, but the C-1r "a" chain has blocked N-terminal amino acid. The 20 N-terminal residues of both "b" chains are similar, but not identical, and both show obvious homology with other serine proteinases. The difference in polysaccharide content of the subcomponents C-1r and C-1s is most marked in the 'b' chains. When tested on synthetic amino acid esters, subcomponent C-1r hydrolysed both lysine and tyrosine ester bonds, but subcomponent C-1r did not hydrolyse any amino acid esters tested nor any protein substrate except subcomponent C1s. The lysine esterase activity of subcomponent C1s provides a rapid and sensitive assay of the subcomponent.     

Inhibition of rosette formation by antithymocyte globulin

Summary The peripheral blood leukocytes from 29 patients with adenocarcinoma of the colon were studied sequentially for the T-cell level, the rosette-inhibition titer of antithymocyte globulin and the blastogenic response to PHA and Con A to evaluate the T-cell immunocompetence. The level of E-rosette-forming cells and the blastogenic response did not reflect the immunocompetence of the T-cell population. Fluctuations in the rosette-inhibition titer of antithymocyte globulin (ATG) were observed; an increased ATG titer indicated an unfavorable clinical course, while a decreased ATG titer was observed with patients who had a favorable clinical course. The rosette-inhibition titer with antithymocyte globulin was observed to be an important indicator of competent T cells in patients with colorectal cancer.Supported by the Physicians' Medical Education and Research Foundation and General Research Supports FundsAbbreviations used that are not spelled out in the text are: AET 2-aminoethylisothiouronium bromide; ATG Antithymocyte globulin; ALG Antilymphocyte globulin; E-RFC Erythrocyte rosette-forming cells; PHA Phytohemagglutinin; Con A Concanavalin A; E Sheep erythrocyte     

Apparent resistance to hypotensive effect of clonidine.

Clonidine failed to reduce the blood pressures of two patients with essential hypertension. On was given 5-4 mg/day and the other 6 mg/day, and their respective peak plasma clonidine concentrations were 26-2 ng/ml and 14-4 ng/ml. Several months after the end of clonidine treatment a single oral dose of 0-3 mg of clonidine produced maximum falls in blood pressure of 30/22 mm Hg and 88/41 mm Hg with peak plasma clonidine concentrations of 1-4 ng/ml and 0-9 ng/ml. Resistance to the hypotensive effect of high doses of clonidine may be due to stimulation of peripheral alpha-adrenoceptors causing vasoconstriction, which maintains a raised blood pressure.     

Renal insufficiency associated with excessive lead exposure.

Water lead concentrations were measured in 970 households throughout Scotland. Blood lead concentrations were measured in 283 people living in houses with water lead levels of over 0-48 mumol/l (100 mug/l). A highly significant correlation was found between lead concentrations in water and blood. Raised blood lead concentrations were associated with renal insufficiency, reflected in raised serum urea concentrations, and with hyperuricaemia, although there was no evidence of clinical disease in any of the affected people. This is further evidence that excessive lead in domestic water supplies has a harmful effect on the community''s health.