Influence of ashing techniques on the analysis of trace elements in biological samples

Dry ashing and wet ashing are two commonly used methods for the preparation of biological materials for trace element analysis by atomic absorption spectrophotometry. In this paper, National Bureau of Standards (NBS) bovine liver was dry ashed at 450°C for 24 h in silica glass (Vycor) or procelain crucibles; the resulting ash was dissolved in either concentrated nitric or hydrochloric acid. Dry ashing efficiency was evaluated by comparing iron, copper, zinc, and manganese concentrations of the samples with the values certified by NBS. Highest recoveries were obtained by dry ashing in silica glass (Vycor) crucibles. Dissolving the resultant ash in either hydrochloric or nitric acids did not significantly alter the results. A comparison between dry and wet ashing shows the latter method to be superior for the preparation of biological tissues for analysis of iron, copper, zinc, and manganese.     

Isolation,characterization and localization of bovine adrenal medullary myosin

Summary Myosin was isolated in high purity from the bovine adrenal medulla by gel filtration and ion exchange chromatography. The purified myosin was analyzed by electrophoresis in gels containing SDS and found to contain a 200,000 molecular weight heavy chain and major light chains of molecular weights 20,000 and 17,000 in a 111 molar ratio. At high ionic strength the myosin had high Ca-ATPase and K-EDTA-ATPase activities and low Mg-ATPase activity. At low ionic strength, the Mg-ATPase was activated to a low level by rabbit muscle actin. The myosin was found to decorate F-actin in the absence, but not the presence of ATP. In low ionic strength solutions, the myosin assembled into characteristic bipolar filaments.The distribution of this myosin in the adrenal medulla and of cross-reacting myosin in several other bovine tissues was determined with the use of antimedullary myosin immunoglobulin G as a specific stain that was detected by direct and indirect immunofluorescence. In the medulla strong staining was seen between the chords of chromaffin cells indicating the presence of a highly muscular vasculature that may perform functions analogous to those of the myoepithelium of exocrine glands. The chromaffin cells showed weak positive staining around the nuclei and in a pattern radiating toward adjacent blood vessels. Cells of the inner zone of the adrenal cortex showed strong staining in the peripheral cytoplasm while cells in the intermediate and outer zones did not stain. In a blood smear, platelets and the cytoplasm of leukocytes stained strongly while erythrocytes did not stain. In striated muscle and the gray and white matter of the cerebrum only the capillaries and larger vessels stained. In the liver the phagocytic cells bordering vascular sinuses stained strongly while the hepatocytes were separated from one another by a 2 micron trilaminar band possibly representing the microfilament web surrounding the bile canaliculi and associated with junctional complexes.The results suggest that myosin is present in several highly differentiated, non-motile tissue cells where it may play a role in secretion or other specialized functions.The author gratefully acknowledges the support and encouragement received from Francis D. Carlson (Johns Hopkins University) and Harvey B. Pollard (National Institutes of Health) in whose laboratories the majority of this work was performed, as well as additional advice and assistance from John Cebra, Richard Cone, William F. Harrington, Shin Lin, Robert Wyllie and the members of their laboratories     

Microbial Activities in Undecompressed and Decompressed Deep-Seawater Samples

Microbial transformations of ¹⁴C-labeled substrates (sodium glutamate, Casamino Acids, glucose, and sodium acetate) were measured in undecompressed seawater samples collected from depths of 1,800 to 6,000 m, during 14- to 21-day incubation periods at in situ temperature (3°C). Each substrate was tested at two concentrations (ca. 0.5 and 5.0 μg/ml) and two in situ pressures. The data were compared to 1-atmosphere (ca. 1.013 × 10² kPa) controls. The rates of ¹⁴C incorporation and ¹⁴CO₂ production as well as the amounts of total substrate utilization were generally lower at pressure than in the decompressed controls but were significantly different for each of the four substrates used. The utilization of acetate was the least affected by pressure; rates were similar to those measured at 1 atmosphere in two out of four experiments. In contrast, transformation rates of the amino acids at pressure averaged to only 38% of those in the controls. A single but reproducible “barophilic” response was observed with glucose as a substrate in samples collected from a depth of 4,500 m at a specific area in the northwestern Atlantic Ocean. Except for this latter set of experiments, the transformation of all substrates showed an increased lag period at pressure as compared to the 1-atmosphere controls.     

Proposed molten globule intermediates in fd phage penetration and assembly

The fd filamentous phage can be contracted to short rods called I-forms and to spheroidal particles called S-forms. The conversions from fd----I-forms----S-forms were previously suggested to mimic steps in fd penetration. The same conversions, in reverse order, were suggested to mimic steps in fd assembly. The I-forms and S-forms bind the hydrophobic probe, 1-anilino-napthalene-8-sulfonate (ANS); under the same conditions, fd binds this probe very poorly. Rigidly packed side chains in fd and nonrigidly packed side chains in I-forms and S-forms would explain the differences in ANS binding. A compilation of the properties of I-forms and S-forms indicate that: (i) they have compact structures; (ii) they have secondary structures of the same type as native phage; (iii) they have non-native morphologies; and (iv) they may have nonrigid side chain packing. These are the properties of molten globules.     

A model for fd phage penetration and assembly

Below 15 degrees C, chloroform causes fd phage to contract to I-forms, which are compact structures about 1/3 as long as the original phage. Above 15 degrees C, chloroform causes I-forms to contract to even more compact spheroidal S-forms. Here we show that the coat protein structure in I-forms is the same as the protein structure in the phage and the protein structure in S-forms is the same as the protein structure in bilayers. The conversions from fd----I-forms----S-forms are therefore suggested to mimic steps in fd penetration. The same conversions, in reverse order, are suggested to mimic steps in fd assembly.     

Tamoxifen fails to block estradiol accumulation, yet is weakly accumulated by the juvenile zebra finch anterior hypothalamus: an autoradiographic study.

In experiment 1, we used autoradiographic procedures to examine whether tamoxifen could displace 3H-estradiol labeling in the anterior hypothalamus and the caudal nucleus of the ventral hyperstriatum (HVc) of ovariectomized 20-day-old female zebra finches. There was no significant reduction in labeling of cells by 3H-estradiol in birds preinjected with unlabeled tamoxifen. In experiment 2, we found that injections of 3H-tamoxifen caused-weak labeling of cells in the anterior hypothalamus of 20-day-old male and female zebra finches. These results are compatible with the idea that tamoxifen does not block the action of estradiol in the brain of zebra finches, and suggest that the effects of early tamoxifen treatment on the morphology of the song system may reflect central actions of tamoxifen.     

Identification and molecular mapping of a single Arabidopsis thaliana locus determining resistance to a phytopathogenic Pseudomonas syringae isolate

We present a model pathosystem to dissect genetically the disease resistance response of plants against phytopathogenic bacteria. The interaction between Pseudomonas syringae pathovar maculicola (Psm) and Arabidopsis thaliana displays phenotypic varia-ion which depends on the genotype of both partners. Compatible interactions are defined by sustained in-planta bacterial growth and are normally accompanied of their appearance. For compatible interactions, resistance is defined by limited in-planta bacterial growth accompanied by a typical 'hypersensitive response' (HR). We show that at least parts of this system fit the paradigms of Flor's 'gene-for-gene' hypothesis. We identify functionally a putative bacterial avirulence gene (avrRpm 1) from a Psm isolate which conditions the HR on A. thaliana ecotypes Oy-0 abd Col- 0, but not Nd-0. We also demonstrate that resistance to the Psm strain from which avrRpm1 was isolated segregates as a single trait in the crosses Col-o x Nd-0 and Nd-0 x Oy-0. Furthermore, we map this locus (RPM1) molecularly in the Col-0 x Nd-0 cross to a relatively small interval defined by two RFLP markers on A. thliana chromosome 3. Resistance in the second cross also maps to this locus and co-segregates with resistance to avrRpm1.     

Society for Industrial Microbiology

Society for Industrial Microbiology