Effects of human atrial natriuretic polypeptide on pancreatic exocrine secretion in the dog

We examined the effects of atrial natriuretic polypeptide (hANP) on exocrine function in the isolated and blood-perfused dog pancreas in situ. Intra-arterial injection of hANP (1-10 micrograms) resulted in the dose-dependent increases of the pancreatic juice secretion. The secretory activity of 3 micrograms of hANP was approximately equal to one third of the secretory activity of 0.1 units of secretin. The use of hANP increased the concentration of bicarbonate but not that of sodium and protein in the pancreatic juice as compared with the basal values. These secretory responses to hANP were not inhibited by treatment with haloperidol, sulpiride, phentolamine, propranolol, atropine, cimetidine or ethacrynic acid. These results suggest that hANP acts directly on the pancreatic exocrine gland to stimulate pancreatic secretion; without, however, increasing sodium excretion. The mechanism of this effect remains to be elucidated.     

High-performance liquid chromatographic analysis of methylation changes of CCGG sequence in brain and liver DNA of mice during pre- and postnatal development

The change of the methylation of CpG in the CCGG sequence of brain and liver DNAs of mice during late fetal and suckling periods was determined by high-performance liquid chromatography using a reversed-phase column and 0.1 M phosphate buffer (pH 6.0) as the mobile phase. The tissue DNA was digested with the restriction enzyme, MspI, and was labeled at the 5′-end with [γ-³²P]ATP. The cpm% of deoxycytidine 5′-monophosphate (5mdCMP) in total CpG dinucleotides was calculated from the equation 5mdCMP/total CCGG (cpm%) = (5mdCMP)_MspI,cpm/{(5mdCMP)_MspI,cpm + (dCMP)_MspI,cpm} × 100. The brain DNA exhibited a significant decrease in CpG methylation at prenatal day 18 but little change after birth. This marked decline of 5mdCMP in the CCGG sequence may be associated with the increase of enzymes before birth. The liver DNA showed considerable change during the late prenatal period. The observed changes of CpG methylation in liver DNA are indicative of the corresponding alterations of enzymes, multinucleate cells and hepatocytes. The results obtained indicate that both brain and liver cells have the development-associated changes in the conformation and transition of DNA around the time of birth.     

Leclercia adecarboxylata Gen. Nov., Comb. Nov., formerly known asEscherichia adecarboxylata.

The nameLeclercia adecarboxylata is proposed for a group of the family Enterobacteriacae previously known asEscherichia adecarboxylata. Leclercia adecarboxylata can be phenotypically differentiated from all other species of Enterobacteriaceae. The members of this species are positive for motility, indole production, methyl red, growth in the presence of KCN, malonate, beta-galactosidase, beta-xylosidase, esculin hydrolysis, gas production fromd-glucose, and acid production fromd-cellobiose,d-lactose, melibiose,l-rhamnose, adonitol,d-arabitol, dulcitol, and salicin; the strains were negative for Voges-Proskauer, citrate (Simmons), H₂S (Kligler), lysine and ornithine decarboxylases, arginine dihydrolase, phenylalanine deaminase, gelatinase, DNase, Tween-80 hydrolysis, and acid production from myoinositol and alpha-methyl-d-glucoside. Fermentation ofd-raffinose,d-sucrose, andd-sorbitol is variable with strains. DNA relatedness of 11 strains ofL. adecarboxylata to three strains including the type strain of this species averaged 80% in reactions at 65°C. DNA relatedness to other species in Enterobacteriaceae was 2%–32%, indicating that this species was placed in a new genusLeclercia gen. nov. The type strain ofL. adecarboxylata is ATCC 23216.     

Reconstituted HDL containing human apolipoprotein A-1 reduces VCAM-1 expression and neointima formation following periadventitial cuff-induced carotid injury in apoE null mice.

Arterial injury triggers an inflammatory response in part mediated by induction of adhesion molecules such as vascular cell adhesion molecule-1 (VCAM-1) and is implicated in neointimal thickening. Since HDL is known to reduce cytokine-activated VCAM-1 expression, we tested the hypothesis that VCAM-1 expression and neontimal thickening following arterial injury are inhibited by reconstituted human HDL containing plasma-derived apoA-1 (rHDL). We used the carotid cuff injury in apoE (-/-) mice fed high cholesterol. Mice received rHDL (40 mg/kg) intravenously every other day for 3 weeks. Compared to control, rHDL treatment inhibited neointima formation (0. 008 +/- 0.004 mm(2) vs. 0.037 +/- 0.019 mm(2); P < 0.01) 21 days after injury, reduced VCAM-1 expression, and decreased monocyte/macrophage infiltration as assessed by histomorphometric analysis within the first week after injury. These changes occurred without any effect on plasma total and HDL cholesterol levels as well as the arterial tissue cholesterol levels. rHDL treatment also reduced the formation of modified lipoprotein in the arterial wall compared to control within the first week after injury. This finding suggests an antioxidant effect of rHDL associated with reduced VCAM-1 expression and neointimal formation after arterial injury.     

Quantifying and monitoring functional photosystem II and the stoichiometry of the two photosystems in leaf segments: approaches and approximations

Given its unique function in light-induced water oxidation and its susceptibility to photoinactivation during photosynthesis, photosystem II (PS II) is often the focus of studies of photosynthetic structure and function, particularly in environmental stress conditions. Here we review four approaches for quantifying or monitoring PS II functionality or the stoichiometry of the two photosystems in leaf segments, scrutinizing the approximations in each approach. (1) Chlorophyll fluorescence parameters are convenient to derive, but the information-rich signal suffers from the localized nature of its detection in leaf tissue. (2) The gross O(2) yield per single-turnover flash in CO(2)-enriched air is a more direct measurement of the functional content, assuming that each functional PS II evolves one O(2) molecule after four flashes. However, the gross O(2) yield per single-turnover flash (multiplied by four) could over-estimate the content of functional PS II if mitochondrial respiration is lower in flash illumination than in darkness. (3) The cumulative delivery of electrons from PS II to P700(+) (oxidized primary donor in PS I) after a flash is added to steady background far-red light is a whole-tissue measurement, such that a single linear correlation with functional PS II applies to leaves of all plant species investigated so far. However, the magnitude obtained in a simple analysis (with the signal normalized to the maximum photo-oxidizable P700 signal), which should equal the ratio of PS II to PS I centers, was too small to match the independently-obtained photosystem stoichiometry. Further, an under-estimation of functional PS II content could occur if some electrons were intercepted before reaching PS I. (4) The electrochromic signal from leaf segments appears to reliably quantify the photosystem stoichiometry, either by progressively photoinactivating PS II or suppressing PS I via photo-oxidation of a known fraction of the P700 with steady far-red light. Together, these approaches have the potential for quantitatively probing PS II in vivo in leaf segments, with prospects for application of the latter two approaches in the field.     

Uncertainty in positioning ion chamber at reference depth for various water phantoms

Background

Uncertainty in the calibration of high-energy radiation sources is dependent on user and equipment type.

Las21 participates in extracellular/cell surface phenomena in Saccharomyces cerevisiae

Las21 (Yj1062W) is a member of the major facilitator super family, possessing multimembrane spanning domains. The LAS21 gene was identified as a responsible gene for a Saccharomyces cerevisiae mutan which shows sensitivity to a local anestheticum, tetracaine. The null las21 mutant (las21 delta) is viable but shows temperature sensitive growth. We found, in addition to this phenotype, that the las21 delta strain shows a number of defects; mating deficiency, calcofluor resistance, and formation of Zymolyase sensitive spores. Temperature sensitive growth of the las21 delta mutant was found to be suppressed by 0.1 M MgSO4. Two multicopy suppressors were obtained. They are ECM33 (YBR078W) and PIR2/HSP150 (YJR159W) both have some roles in an extracellular function. The common features of the suppressors, genetic and physiological, of the las21 delta mutation suggest that Las21 participates in a global activity of extracellular phenomena. The las 21 phenotypes are consistent with the idea that Las21/Gpi7 acts in metabolism of glycosylphosphatidylinositol.     

Methylmalonate-semialdehyde dehydrogenase is induced in auxin-stimulated and zinc-stimulated root formation in rice

Proteins induced in rice by auxin and zinc were determined by proteome analysis. Cultured suspension cells of rice were treated with 2,4-dichlorophenoxyacetic acid and ZnSO₄ and then proteins were separated by two-dimensional polyacrylamide gel electrophoresis; seven proteins were found to be induced by auxin and zinc. Of these seven, methylmalonate-semialdehyde dehydrogenase (MMSDH) was elevated by treatment with auxin alone. MMSDH was detected in cultured suspension cells, root and leaf sheath, but not in leaf blades. MMSDH responded to auxin and gibberellin, but did not respond to brassinolide and cytokinin. Furthermore, the amount of MMSDH in slr1, a constitutive gibberellin response mutant, was 2-fold that of wild type. MMSDH mRNA and protein were stimulated in root formation induced by auxin and/or zinc over a 4-week period. These results suggest that MMSDH may be necessary for root formation in rice induced by auxin and/or zinc.Abbreviations BA 6-Benzylaminopurine - BL Brassinolide - CBB Coomassie Brilliant Blue - 2,4-D 2,4-Dichlorophenoxyacetic acid - GA Gibberellic acid - IAA Indole-3-acetic acid - MALDI-TOF MS Matrix-assisted laser desorption-ionization time-of-flight mass spectrometry - MMSDH Methylmalonate-semialdehyde dehydrogenase - 2D-PAGE Two-dimensional polyacrylamide gel electrophoresis - PVDF Polyvinylidene difluoride     

Tetraborate concentration on Morgan-Elson reaction and an improved method for hexosamine determination.

Effect of tetraborate concentration on the determination of hexosamine by Morgan-Elson color reaction according to Levvy and McAllan [(1959) Biochem. J., 73, 127–232] was studied using the three different preparations of the tetraborate solution. The concentration of the previous report during the chromogen formation (0.29 m) was too high comparing to the optimum concentration of the present experiment (0.175 m). An improved method is now proposed which is excellent on the ground of convenience and reproducibility; same readings were obtained with the tetraborate solution from various preparations which were stable at least for two years. It showed same molar extinction coefficient as obtained before.