Relationship between intestinal motility, tone, water absorption and lymph flow in the rat

The relations between motility, tone, water absorption rate (Jv) and lymph flow (J1), were studied in an exteriorized upper jejunal preparation in vivo, with its serosal side bathed in Krebs-Ringer or other solutions. Neither Jv nor J1 was correlated with motility. When the luminal fluid consisted of an isotonic solution of MgSO4, glucose or LiCl, motility was greatly increased with no increase in J1. When the serosal fluid consisted of an isotonic solution of mannitol, glucose or MgSO4, motility was depressed with a large decrease in tone, and Jv was increased by 51-83% with a decrease in J1. When the serosal fluid consisted of an isotonic solution of NaCl, Na2SO4, LiCl or KCl, motility was decreased with either no change or an increase in tone, and both Jv and J1 were much decreased. When isotonic choline Cl solution was employed as the serosal fluid, motility increased with an increase in tone, Jv became negative (fluid secretion), and J1 decreased to 0. Acetylcholine depressed motility but increased tone with a decrease in Jv and J1. Eserine increased both tone and motility with a decrease in Jv and J1. Serotonin caused no change in motility but increased tone with a decrease in Jv and J1. Noradrenaline and adrenaline depressed motility and reduced tone with an increase in Jv and J1. Isoprenaline abolished motility and reduced tone with a large increase in Jv but no change in J1. Pentobarbitone depressed motility and reduced tone with an increase in Jv but a decrease in J1. It is concluded that the intestine responds to various stimuli with a change in motility, or tone, or both. Intestinal motility per se does not produce lymph. Since an increase or decrease in tone always results in a decrease or increase in Jv, respectively, regardless of the nature of the conditions, a relaxation of the intestinal musculature appears to be associated with an increase in water absorption.

Gravity-Induced Polar Transport of Calcium across Root Tips of Maize

Calcium movement across primary roots of maize (Zea mays, L.) was determined by application of (45)Ca(2+) to one side of the root and collection of radioactivity in an agar receiver block on the opposite side. Ca movement across the root tip was found to be at least 20 times greater than movement across the elongation zone. The rapid movement of Ca across the tip was severely inhibited in roots from which the root cap had been removed. Ca movement across the tip was also strongly retarded in roots pretreated with 2,4-dinitrophenol or potassium cyanide. Orientation of roots horizontally had no effect on Ca movement across the elongation zone but caused a strong asymmetry in the pattern of Ca movement across the tip. In gravistimulated roots, the movement of Ca from top to bottom increased while movement from bottom to top decreased. The data indicate that gravistimulation induces polar movement of Ca toward the lower side of the root cap. An earlier report (Lee, Mulkey, Evans 1983 Science 220: 1375-1376) from this laboratory showed that artificial establishment of calcium gradients at the root tip can cause gravitropic-like curvature. Together, the two studies indicate that Ca plays a key role in linking gravistimulation to the gravitropic growth response in roots.

Molecular analysis of the HLA-D region genes

Analysis of the amino acid sequence of the HLA-DR alpha chain and the structure of the gene encoding it have shown strong homologies to membrane proximal domains of the DR beta chain and HLA-ABC, as well as to beta 2-microglobulin. Weaker, but nevertheless apparent homologies to C kappa and C lambda immunoglobulin domains support the interpretation that these genes diverged in evolution from a primordial immunoglobulin-like domain. Cosmid clones containing sequences related to the DR alpha chain have been isolated. These sequences probably represent the SB and DC alpha genes. In addition to the alpha "genes," some of the cosmids also contain sequences related to the DR beta chain suggesting that the human HLA-D region alpha and beta genes are interspersed.

Chromosomal arrangement of leghemoglobin genes in soybean

A cluster of four different leghemoglobin (Lb) genes was isolated from AluI-HaeIII and EcoRI genomic libraries of soybean in a set of overlapping clones which together include 45 kilobases (kb) of contiguous DNA. These four genes, including a pseudogene, are present in the same orientation and are arranged in the order: 5'-Lba-Lbc1-Lb psi-Lbc3-3'. The intergenic regions average 2.5 kb. In addition to this main Lb locus, there are other Lb genes which do not appear to be contiguous to this locus. A sequence probably common to the 3' region of Lb loci was found flanking the Lbc3 gene. The 3' flanking region of the main Lb locus also contains a sequence that appears to be expressed more abundantly in root tissue. Another sequence which is primarily expressed in root and leaf is found 5' to two Lb loci. Overall, the main leghemoglobin locus is similar in structure to the mammalian globin gene loci.

The complete nucleotide sequence of the I-E alpha d immune response gene

We have isolated and sequenced the complete murine I-E alpha immune response gene of the H-2db haplotype. The I-E alpha d gene consists of 5300 basepairs and is organized into five or possibly six exons that correspond to different domains of the alpha chain. The amino acid sequence deduced from the I-E alpha gene shows 75% homology to its human counterpart, the HLA-DR alpha chain. The absence of I-E antigen in H-2 mice is due to lack of E alpha chain synthesis. We show here that this defect is caused by a deletion in the 5' end of the I-E alpha b gene.

Characterization of monoclonal antibodies specific for isopentenyl adenosine derivatives occurring in transfer RNA

A family of isopentenyl adenosine derivatives are naturally occurring components of transfer RNA and are involved in several different functional roles in the cell. To facilitate the study of the biochemistry of these modified nucleosides we have raised monoclonal antibodies to N6-(delta 2-isopentenyl)adenosine and N6-(4-hydroxy-3-methyl-but-2-enyl)adenosine. The antibodies show considerable specificity and three characteristic types are distinguishable. The first type have the hydroxylated derivative as the preferred antigen, the second type have isopentenyl adenosine as the preferred antigen and a third type show a specificity for all isopentenyl-containing derivatives.

Intestinal transudation, secretion, and lymph flow during volume expansion in the rat

The effect of volume expansion by intravenous infusion of saline on the rate of intestinal lymph flow (JL), serosal surface transudation (JT), and secretion (JS) from upper jejunum was determined. During saline infusion there was a large increase in JS and JT but a small increase in JL due to increased capillary filtration. About 20% of JL from the main intestinal lymph duct originated from the intestine and the rest from the mesenteric pedicle. JL (corrected for pedicle lymph flow), JT, and JS were estimated to account for 10, 30, and 60% of capillary filtrate from the intestine, respectively. Neither lymph nor secretion contained measurable protein, but transudation had a high protein concentration about half of that in the plasma. From these findings it is inferred that probably both JL and JS were derived from the capillary filtrate of mucosa and submucosa vascular beds and JT from that of muscular vascular bed and that capillaries and venules in the mucosa restricted the passage of protein molecules while those of the intestinal muscular tissue were highly permeable to protein.

Intravenous access: a comparison of two methods

The reliability in providing a continued venous route to the circulation is compared between a winged needle (Abbott "Butterfly--23 INT") and a plastic catheter (Jelco Teflon "Catheter Placement Unit", 22 gauge). The catheter remained within the vein in all cases and had a much lower incidence of total obstruction during the study period. Where an intravenous infusion is not in place, a plastic catheter provides a more reliable access route to the circulation than does a winged needle.

Effects of stretching and stirring on water and glucose absorption by canine mucosal membrane

A 'mini' canine mucosal membrane preparation permitting simultaneous determination of water (Jv) and glucose (Jg) absorption rates, microscopic examination or micropuncture of the villi was used in this study. The small membranes were more stretched than the large ones, with more than a one-fold increase in both Jv and Jg, apparently due to a change in architectural orientation between the villi and subvillous supporting tissue so as to facilitate water transport via the lymphatic system. During stirring of the bathing solution, the villi in the small membranes were widely separated from each other with more to-and-fro swaying movements than in the large ones. Stirring was seen to cause up-and-down movements of the loosely suspended large membranes but not the small ones. In the small membranes stirring caused no change in Jv but an increase in Jg due to the increase in glucose concentration in the absorbate, while in the large membranes both Jv and Jg were greatly increased. It is thus considered that the increase in absorption in the large membranes caused by stirring is mainly due to the increased membrane movements promoting lymph flow.

Potassium Sorbate Inhibition of Microorganisms Isolated from Seafood 1

Microorganisms isolated from seafood showed various degrees of sensitivity toward potassium sorbate (PS). At pH 7.0, PS concentration of 0.53% completely inhibited growth of Moraxella sp., while 2.73% was needed to inhibit Arthrobacter sp. Pseudomonas I sp., which was relatively resistant to PS (inhibitory concentration = 1.62%), was not affected by 0.3% PS after freeze-thaw treatment (-78°C for 8 min and 20°C for 20 min), but showed a delay in onset of logarithmic growth for up to 20 h after heating at 50°C for 5 min. The inhibitory effect of PS on sub-lethally injured Pseudomonas I was greater in basal medium (Minimum Broth, Davis) than in a rich medium (tryptone-peptone-extract, TPE). Alteromonas putrefaciens , which was sensitive to PS (inhibitory concentration = 0.74%), was also sensitive to freeze-thaw and mild heat. The lag period for quick-frozen cells was extended by 14 h in the presence of 0.05% PS. Heating at 45°C for 10 sec was sufficient to cause complete inhibition of growth by 0.05% PS in MBD, and 8 h delay in the onset of logarithmic growth in TPE. Selective and inhibitory effects of PS, therefore, could be further enhanced in frozen or heat-treated seafood.

Novel aspects of the structure of the Escherichia coli nucleoid investigated by a rapid sedimentation assay

The Escherichia coli nucleoid is maintained in its folded highly condensed state by constraints which involve RNA and protein. We have developed a rapid sedimentation assay to determine the state of folding of the membrane-free nucleoid. An approximate measure of the stability of the nucleoids under various conditions can then be estimated by measuring the temperature at which the nucleoids unfold. Using ethidium and gamma irradiation (which removes the negative supercoiling of the native nucleoid) as probes, it can be shown that there are two types of constraint involved in the condensation of the nucleoid. One of these constraints is destabilized by ethidium but stabilized by negative supercoiling; the second constraint is unaffected by both ethidium and negative supercoiling. Several models can be proposed: (i) a DNA . RNA duplex, (ii) a double-strand DNA (dsDNA) . RNA triplex, (iii) DNA-protein interactions, (iv) a topological knot with RNA, and (v) a DNA tetraplex. The topological knot model is not consistent with the data and many combinations of the others can be excluded. If RNA is involved in both constraints then RNA . DNA duplexes and dsDNA . RNA triplexes are involved in stabilizing the nucleoid.

Specificity of autoimmune monoclonal Fab fragments binding to single-stranded deoxyribonucleic acid

Fab fragments from hybridoma HEd 10 [Lee, J. S., Lewis, J.R., Morgan, A.R., Mosmann, T.R., & Singh, B. (1981) Nucleic Acids Res. 9, 1707-1721] were prepared in large amounts by papain digestion of the immunoglobulin G (IgG) fraction from ascites fluid. Binding data were generated by a fluorescence quenching technique, and binding constants [K(0)] were estimated from Scatchard plots. The Fab fragments bound tightly to poly(dT) [K(0) = 12.7 X 10(6) M-1], and analysis of binding constants for the series p(dT)2 to p(dT)17 showed that the recognition sequence consisted of four consecutive residues. The effect of ionic strength on the interaction suggested that only two phosphates were involved. Binding constants for poly(dU), poly[d(brU)], poly[d(brC)], and poly(rU) were 1.0 X 10(6) M-1, 18.8 X 10(6) M-1, 0.5 X 10(6) M-1, and less than 0.5 X 10(6) M-1, respectively, implicating the involvement of the 3, 4, and 5 positions of the pyrimidine ring as well as the deoxyribose sugar in the recognition process. At high ionic strength (0.5 M) K(0) for whole IgG binding to poly(dT) was 75 X 10(6) M-1 compared to a value of 1.1 X 10(6) M-1 for the Fab fragment. These results may have implications for the tissue damage caused by DNA-containing immune complexes in systemic lupus erythematosus.

Molecular mechanisms of binding and single-strand scission of deoxyribonucleic acid by the antitumor antibiotics saframycins A and C

The quinone antitumor antibiotics saframycins A and C bind to duplex DNA and G,C containing complementary oligodeoxyribonucleotides at pHs below 5.5 via selective protonation of the antibiotics at the N-12 positions in an equilibrium process. This binding shows minor groove specificity to T4 DNA for both antibiotics. Saframycin A exhibits an additional mode of covalent binding to DNA, which is reversible by heating, via an animal linkage with the NH2 group of guanine. Covalent binding of saframycin A is enhanced by prior reduction of the quinone moiety via a different mechanism with concomitant elimination of the nitrile group and plausibly involves an intermediate quinone methide. Both saframycin A and saframycin C when reduced in situ with NADPH or sodium borohydride cause single-strand breaks, but not double-strand breaks, in PM2 covalently closer circular DNA. This latter reaction proceeds via intermediate semiquinones, the identity and conformation of which are established by EPR. The DNA scission process which requires oxygen is mediated by the generation of O2-., H2O2 and OH., the latter of which species was identified by spin trapping. The strand scission of DNA is pH dependent and, unlike the binding of the antibiotics, is strongly inhibited by Mg2+ and Zn2+ ions.

Evidence for an internal promoter preceding tufA in the str operon of Escherichia coli

We constructed plasmids carrying tufA from which the major promoter for the rpsL-rpsG-fus-tufA operon (also called the str operon) had been removed. These plasmids continued to express tufA, as judged by the ability to complement mocimycin resistance and by electrophoretic analysis of synthesized proteins. Tn5 transpositions into fus, the gene for elongation factor G, which lies immediately on the 5' side of tufA, failed to obstruct the expression of tufA. The subcloning of a 2,000-base-pair PstI-SmaI DNA fragment (containing the intercistronic region between tufA and fus, the distal portion of fus, and the proximal portion of tufA) next to promoterless tetracycline resistance genes (tet) yielded a plasmid that was capable of bestowing resistance to 12 microgram of tetracycline per ml. The removal of an EcoRI fragment that lies within fus destroyed the ability of the 2,000-base-pair PstI-SmaI fragment to promote the transcription of tet. These data indicate that, in addition to the operon's major promoter rpsLp, there is an internal promoter, tufAp, which can be used for the transcription of tufA, tufAp probably lies within fus, about 50 base pairs upstream from its 3' end and 120 base pairs from the start codon of tufA. The relative activities of tufB and of tufA-from-tufAp were estimated by a comparison of beta-galactosidase activities of almost identical EF-Tu-beta-galactosidase protein fusions; they were approximately equal.

Immunoelectron microscopic identification of Langerhans cells using a new antigenic marker

The specificity of a monoclonal antibody (OKT6) for epidermal Langerhans cells was examined by immunoelectron microscopy. Peroxidase-labeled OKT6 bound to 1-5% of suspended human epidermal cells, as determined by light microscopy. Electron microscopic examination of peroxidase-labeled cells revealed that all Birbeck granule-containing Langerhans cells bound OKT6. In addition, a small population of indeterminate cells, lacking the Birbeck granule, was also labeled with OKT6. The ultrastructural studies confirm the specificity of OKT6 for Langerhans cells and suggest that the indeterminate cell represents a related cell population.

Scleral melanocytoma

An 81-year-old black woman with severe rheumatoid arthritis presented with an enlarging black lesion on the medial sclera of the left eye. Scleromalacia perforans was suspected. At surgical exploration, a deeply pigmented tumor was encountered, with extension into the orbit, along the medial rectus muscle. Biopsy revealed a benign melanocytoma.

A method for the specific inhibition of poly[d(A-T)] synthesis using the A-T specific quinoxaline antibiotic TANDEM

A serious problem in the replication of repeating-sequence DNa polymers using Escherichia coli DNA polymerase I arises from the fact that this polymerase has a very strong preference for the replication of poly[d(A-T)]. Thus reactions primed with DNA containing small amounts of contaminating poly[d(A-T)] will eventually result in complete domination of the synthesis by poly[d(A-T)]. This problem can be overcome by the addition to the reaction mixture of the synthetic quinoxaline antibiotic TANDEM which binds specifically to poly[d(A-T)] completely inhibiting its replication. Using thermal denaturation experiments it can be shown that TANDEM does not bind to most other synthetic DNA polymers (e.g., poly(dA) . poly(dT) and poly[d(A-T-C)] . poly[d(G-A-T)] and therefore their replication is not inhibited. The only exception we have encountered is poly[d(T-A-C)] . poly[d(G-T-A)] which does bind TANDEM and therefore the drug cannot be used during the synthesis of this polymer. The fact that poly[d(T-A-C)] . poly[d(G-T-A)] does bind TANDEM while poly[d(A-T-C)] . poly[d(G-A-T)] does not, suggests that the drug recognizes T-A rather than A-T sequences.

Inhibition of Escherichia coli Trimethylamine-N-oxide Reductase by Food Preservatives 1

Trimethylamine-N-oxide (TMA-O) reductase activity of resting cells of Escherichia coli was inhibited by tetrasodium ethylenediaminetetraacetate (Na₄EDTA), benzoic acid (BA and methylparaben (MP). The 50% inhibitory concentrations of Na₄EDTA, BA and MP were 20.2, 1.2 and 32.4 mM, respectively. BA at pH 6.5 or below most effectively inhibited the TMA-O reductase. Sorbic acid (SA), up to 0.70 mM, had no effect on TMA-O reductase activity, but SA inhibited the growth and subsequent TMA production in E. coli at or above 0.3S mM.

A rapid, simple and reliable test for the routine identification of urease producing gram-negative bacteria

The present investigation was prompted by the need to find a simple, rapid, reliable and low-cost method for the routine identification of urease producing bacteria. This method uses Nessler's reagent as an indicator of the presence of volatile ammonia produced by organisms which possess urease. The proposed method is comparable to the conventional Christensen's agar method, but is simpler and more rapid to perform.

cDNA clones coding for the heavy chain of human HLA-DR antigen

Two cDNA clones, pDRH1 and pDRH2, containing sequences specific for human HLA-DR antigens were isolated from a bank of cDNA clones made from partially purified HLA-DR mRNA from the human lymphoblastoid cell line Maja. The clones were specific for the Mr 34,000 HLA-DR antigen glycoprotein chain. The identity of these clones was established by (i) their ability to hybridize specifically to HLA-DR mRNA in a positive selection assay; (ii) mRNA species hybridizing to the cDNA clones were expressed in B-cell but not in T-cell or fibroblast cell cultures; and (iii) a nucleotide sequence in the longer clone, pDRH2, could be translated into an amino acid sequence that is identical to the limited NH2-terminal amino acid sequence available for the purified HLA-DR antigen Mr 34,000 chain. Analysis of DNA from human, mouse, and human--mouse somatic cell hybrid lines by Southern transfer of restriction endonuclease digests indicated that the HLA-DR heavy chain is encoded in chromosome 6. This finding is compatible with the location of at least one of the HLA-D/DR heavy chain genes within the HLA region. In addition, the sequences coding for HLA-DR heavy chain appear to be present in only one or a few copies in the genome and to be relatively simple in structure.