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1. Properties of anion permeation through the membrane of skeletal muscle fibres of the stingray, Taeniura lymma, were studied with intracellular recording and polarization techniques. 2. The Cl conductance of the resting membrane in the normal stingray saline at pH 7·7 is 8–10 times greater than the K conductance. 3. The Cl conductance decreases with decreasing external pH, with an apparent pK of 5·3, whereas the K conductance is independent of pH between 4 and 9. 4. The Q10 of the Cl conductance is about 2·0, compared with a value of 1·2–1·4 for the K conductance. 5. The Cl conductance is proportional to the external Cl concentration when observed after the fibre is equilibrated in the test solution. 6. The permeability sequence obtained by potential measurement is SCN > NO3 > Cl = Br > I > ClO3 and the permeability ratio is independent of the mole fraction of anions. 7. The conductance sequence determined by total replacement of the external Cl with other anion species differs from the permeability sequence and the conductance observed for partial replacement deviates significantly from that expected from the independence principle. 8. Possible mechanisms of anion permeation are discussed.

The nitrate reductase of E. coli is an inducible membrane protein with a molecular weight of about 800,000. The enzyme consists of four subunits of 60,000 molecular weight, four subunits of 142,000 molecular weight, four molecules of molybdenum, and nonheme iron. The enzyme may be solubilized by heat extraction, which results from limited digestion by a membrane-bound protease, or by Triton X-1 00. When the enzyme is isolated from Triton-solubilized cytoplasmic membrane by immune precipitation, it contains a third protein of 20,000 molecular weight which may be a cytochrome. Chlorate resistant (chl) mutants of E. coli lack functional nitrate reductase. Mutants of the classes (chl)and chlB have all of the enzyme polypeptides present in the membrane JI intact form, while in classes chlC and chlE the membrane contains degraded fragments of the polypeptides, suggesting proteolysis of a defective enzyme. Reconstitution of nitrate reductase activity occurs when soluble extracts of various classes of mutants are mixed and incubated at 32°C. This reconstitution requires three things: (a) intact enzyme polypeptides in the form of small soluble lipoprotein fragments resulting from fragmentation of the cytoplasmic membrane during cell breakage; (b) a molybdenum factor which is present in the wild-type membrane and which accumulates in the cytoplasm of chlB mutants in soluble form; and (c) a soluble factor or enzyme, presumably the chlB gene product, which adds the molybdenum factor to the enzyme Two conclusions may be drawn from these observations. First, the enzyme is bound t o the membrane by small, hydrophobic regions on one or more of the subunits. Second, the process of reconstitution from mutant extracts is different from the process involved in de novo synthesis of the enzyme in wild-type E. coli.

Measurements of extra oxygen consumption, 45 Ca 2+ uptake, and the osmotic expansion of the matrix compartment show that not all permeant anions are capable of supporting and accompanying the energy-dependent transport of Ca 2+ from the medium into the matrix in respiring rat-liver mitochondria. Phosphate, arsenate, acetate, butyrate, β-hydroxybutyrate, lactate, and bicarbonate + CO 2 supported Ca 2+ uptake, whereas the permeant anions, nitrate, thiocyanate, chlorate, and perchlorate, did not. The active anions share a common denominator, the potential ability to donate a proton to the mitochondrial matrix; the inactive anions lack this capacity. Phosphate and the other active permeant anions move into the matrix in response to the alkaline-inside electrochemical gradient of protons generated across the mitochondrial membrane by electron transport, thus forming a negative-inside anion gradient. It is postulated that the latter gradient is the immediate “pulling” force for the influx of Ca 2+ on the electrogenic Ca 2+ carrier in respiring mitochondria under intracellular conditions. Since mitochondria in the cell are normally exposed to an excess of phosphate (and the bicarbonate-CO 2 system), particularly in state 4, inward transport of these proton-yielding anions probably precedes and is necessary for inward transport of Ca 2+ and other cations under biological conditions. These observations indicate that a negative-inside gradient of phosphate generated by electron transport is a common step and provides the immediate motive power not only for ( a ) the inward transport of dicarboxylates and tricarboxylates and ( b ) the energy-dependent exchange of external ADP 3- for internal ATP 4- during oxidative phosphorylation, as has already been established, but also for ( c ) the inward transport of Ca 2+ , K + , and other cations.

Two methods suitable for the estimation of Biligrafin and Biligram in plasma are described. One is a simple, direct, ultraviolet spectrophotometric method and the other could be regarded as a reference method because it depends on chemical determination of iodine after digestion.

A racemic mixture of the molecularly dissymmetric compound 1,1′-binaphthyl will spontaneously develop optical activity when melted, cooled, and allowed to crystallize. The distribution of optical rotations in individual samples shows that the resolutions occur in a truly spontaneous manner (i.e., without the influence of any external chiral agent). However, addition of small amounts of certain chiral compounds promotes the generation of one enantiomeric form of binaphthyl. The results are often not completely consistent and this suggests that the nucleation of binaphthyl is sensitive to very low concentrations of unknown chiral agents.

The posterior potential of frog lens has been studied with a microelectrode technique. The lens potential behaved predominantly as a K-electrode, and the slope of the potential for a tenfold change in [K]o, as the product [K]o · [Cl]o was kept constant, was in good agreement with 58 mV predicted from the Nernst equation at high [K]o. The permselectivity of lens membrane towards 90 m m monovalent cations was in the order K + > Rb + > Cs + > NH 4 + . The lens membrane was permeable not only to Cl − but also Br − , I − , NO 3 − , N 3 − , SCN − , ClO 3 − , BrO 3 − , and formate, but not to acetate, propionate, and aspartate. Na + was a much less contributive ion as compared with either K + or Cl − on the lens potential.

Acid-treated extracts of Escherichia coli were tested for their ability to restore reduced nicotinamide adenine dinucleotide phosphate-nitrate reductase activity to an extract of a Neurospora nit-1 mutant which produces a defective enzyme. With wild-type E. coli this complementation activity was more readily detected in the cytoplasmic fraction, although the nitrate reductase activity was found primarily in the particulate fraction. chlB mutants of E. coli appeared to have more complementation activity in the cytoplasm than was observed in the wild type, but no activity in the particulate fraction. The other chl mutants had little or no activity in either fraction. These results suggest that chlB mutants can produce a component or cofactor which is missing in the other mutants and in the Neurospora mutant, but cannot transfer it to the nitrate reductase enzyme.

Infection of Escherichia coli with bacteriophage Mu leads to an increase in the mutation frequency in a wide variety of genes. Taylor (1963) has proposed that these mutations are caused by the integration of the Mu prophage into the gene. The experiments reported in this paper show that the Mu prophage is genetically located at or near the site of the Mu-induced mutation in accord with Taylor's proposal. A Mu-induced chl-D mutation between the λ prophage attachment site and the gal operon prevents λ from transducing gal genes. It is possible to isolate λ-transducing particles from lysates of this strain which carry portions of the Mu prophage. These particles are packaged in λ capsids. Further aspects of Mu mutagenesis are discussed.

Polyvalent cations (such as Ca+2, La+3, and Th+4) and low pH shift the permeability of some biological membranes from preferentially cation-permeable towards preferentially anion-permeable. The action of Th+4 on permselectivity, and the anion permeation mechanism it produces, have been studied in rabbit gallbladder epithelium. The effect involves both a suppression of cation conductance and an increase of anion conductance. Most residual cation conductance is in a free-solution shunt. The anion permeability sequence, SCN−>ClO 4 − >NO 3 − >I−>Br−≧ClO 3 − >Cl−>BrO 3 − , is neither the lyotropic series nor a radius sequence but is in accord with considerations of equilibrium selectivity. Conductance increases linearly with bathing-solution salt concentrations from 10mm up to at least 400mm. The cation-to-anion permeability ratio shows little change with concentration up to at least 300mm. The current-voltage relation is linear in symmetrical solutions and in the presence of a single-salt concentration gradient up to at least 570 mV. Dilution potentials and biionic potentials yield similar permeability ratios among anions. These permeability properties resemble (surprisingly) those of a membrane with fixed neutral sites rather than those of a classical ion-exchanger.

In smears of hair-root cells of male human subjects, the fluorescing Y-body is found frequently to be split in two. Photometric determinations of the relative DNA content of Feulgen-stained cell nuclei revealed no correlation between a particular stage of the cell cycle and the occurrence of the split fluorescent body. All nuclei assessed belonged to the G1 phase of the cell cycle. The varying frequency of occurrence of the double structure of the fluorescent body in different sorts of cells may be due entirely to preparative causes, such as drying, fixing and means of obtaining smears.

SUMMARY: From Bacillus licheniformis s244, 45 chl deletion mutants have been isolated which belong to six groups. In four groups the identity of the auxotrophic markers deleted has been established: his-2, ura-I, arg-3 and trp-I. Furthermore, a leu and a glu marker were found in the two other groups of deletion mutants. From B. licheniformis S1026, derived from strain ATCC9945A, 36 single site mutants were obtained and classified into eight groups, chl A to H, by transformation and phage SP 15-mediated transduction. The glu deletion comprises the mutations chl A and B. In total, 13 chl mutations have been found and there may be up to 13 chl genes. Of the single-site chl mutations, only chl E is linked with a known reference marker, ura-I. All chl mutants are unable to form nitrate reductase under conditions of oxygen shortage. This nitrate reductase is mainly associated with the cytoplasmic membrane. Most mutations have pleiotropic effects: (i) retarded growth under anaerobic conditions; (ii) an increased sensitivity to penicillin and related antibiotics; (iii) completely altered membrane protein patterns on acrylamide-SDS gels. In the wild-types, II membrane protein bands are observed. There are only small, quantitative differences between membrane protein patterns of cells cultivated aerobically or anaerobically. Membrane protein patterns of the chl mutants are most different from those of the wild-types after anaerobic cultivation. Differences include appearance of a new protein band, disappearances, decreases, doublings and often large increases of other protein bands. Aerobically, the mutants have membrane protein patterns less different from those of the wild-types. Differences include appearance of a new protein band, decrease and disappearance of protein bands. An explanation for all these changes may be a wholesale disorganization of protoplasmic membrane biosynthesis.

The activity of pepsin on small substrates, as well as its autodigestibility, fluorescence and circular dichroism were unaffected by the presence of “disordering” anions. Pepsin activity on hemoglobin and bovine serum albumin was inhibited by the same anions, while the hydrolysis of lysozyme was enhanced. The anions also altered the fluorescence and circular dichroism spectra of bovine serum albumin. These findings are discussed in relation to conformational changes induced by disordering ions at acid pH.

When rats were treated with [ 14 C]dimethylnitrosamine and the liver DNA hydrolysed with HClO 4 and the free bases analysed by column chromatography on Dowex-50, the thymine fraction was found to be labelled. The radioactive component is not 3-methylthymine, and evidence suggests that it is not a product formed by methylation of the nucleic acid. The radioactive compound is probably formed from the labelled formaldehyde arising from dimethylnitrosamine, but the radioactivity is not in thymine, deoxyribose, or in any amino acid tested. It probably represents an uncharged metabolite of formaldehyde which becomes bound more extensively to DNA than to RNA.

A reversible intramolecular and co-operative isomerization of double-stranded, oligomeric and poly(dG-dC) · poly(dG-dC) takes place in aqueous solution when the salt concentration at 25 °C and neutral pH is increased to 2.5 m-NaCl, 1.8 m-NaClO4 or 0.7 m-MgCl2. This conformational transition between two different double helical forms is accompanied by changes of optical rotatory dispersion, circular dichroism and ultraviolet absorption. Preliminary X-ray diffraction data are compatible with the existence of two salt-dependent structures. The enthalpy change of the transition is close to zero. The first-order kinetics are in the time range of 102 to 103 seconds and are followed after appropriate shifts in the salt concentration. The activation energy for both over-all rate constants is + 22 ± 2 kcal./mole and is nearly independent of the chain length. In chloride solutions the over-all rate constant for the transition from the high salt L-form to the low salt R-form decreases strongly with increasing salt concentrations. A detailed mechanism is proposed involving for the nucleation of the other helical form the opening or unstacking of a certain number of base pairs at the end of an oligomer. Analytical expressions for the chain length dependence of the degree of transition and the relaxation time are derived, assuming steady-state conditions for intermediates. The experiments show that an isomerization of DNA with a certain base sequence is possible in solution and the proposed model suggests a plausible mechanism. Some biological implications of such conformational transitions in DNA are briefly discussed.

Chlorate-resistant mutants corresponding to each known genetic locus ( chlA, chlB, chlC, chlD, chlE ) were isolated from Escherichia coli K-12. All these mutants showed decreased amounts of membrane-bound nitrate reductase, cytochrome b , and formic dehydrogenase, but all had normal succinic dehydrogenase activity. Proteins from the cytoplasmic membranes of these mutants were compared to those of the wild type-on polyacrylamide gels. The addition of nitrate to wild-type anaerobic cultures caused increased formation of three membrane proteins. These same proteins, along with one other, were missing in varying patterns in mutants altered at the different genetic loci. One of the missing proteins was found to be the enzyme nitrate reductase, although this protein was present in some mutants lacking nitrate reductase activity. None of the others has been identified.

Male and female rats of varying ages were placad on a low iodine diet (LID) plus KClO4 or 6-propyl-2-thiouracil (PTU) or on the same diet supplemented with I (control rats). Goitrogenesis was also induced with LID plus PTU in gonadectomized animals of both sexes. The weight of the control and goitrogen treated animals, and the weight and iodine content of their thyroids were determined, as well as the plasma PBI, TSH, insulin and glucose levels. The pituitary GH-like protein content was assessed by disc electrophoresis on polyacrylamide gels. If goitrogenesis was induced in young rats of both sexes starting with rats of the same age, body weight (B.W.) and pituitary growth hormone (GH) content, it was found that both the males and females developed goitres of the same size. On the contrary, when goitrogenesis was induced in adult animals, it was found that male rats, that had larger B.W. and pituitary GH content than age-paired females, developed larger goitres. However, both male and female rats were in a hypothyroid condition of comparable degree as judged by the thyroidal iodine content and the plasma PBI and TSH levels. When all the data on the PTU or KClO4-treated male and female rats of varying age and B.W. were considered together, it was observed that the weights of the thyroids increased proportionally to B.W. However, a difference in the slope of the regression of the thyroid weight over B.W. was found between male and female rats, due to the fact that adult male rats develop larger goitres than female animals. In addition, in the male rats treated with PTU, gonadectomy decreased the B.W., pituitary content of GH-like protein and, concomitantly, the size of the goitre decreased; an opposite effect was induced by ovariectomy on the female animals. However, when goitrogenesis was induced in weight-paired adult rats of both sexes, the male animals still developed larger goitres than the females. Among all the parameters studied here, the only ones which appeared to bear a consistent relationship with the size of the goitres in rats of different sexes, treated with a given goitrogen, were the rate of body growth and the amount of a pituitary GH-like protein found before the onset of the goitrogen treatment. Moreover, though the pituitary content of the GH-like protein decreased as a consequence of goitrogen treatment, it was still somewhat higher in male that in female animals. The present results suggest that GH may somehow be involved in the mechanism by which male and female rats on goitrogens develop goitres of different sizes, despite equally high plasma TSH levels.

Massive traumatic anorectal and perianal hemorrhage postoperatively is rare. Six cases of massive bleeding, four postoperative and two traumatic, have been discussed. None of these patients had a systemic bleeding disorder. The bleeding may be external, internal, or both. It is treated by immediate restoration of blood volume and by stopping the bleeding by ligature or by packing with hypochlorite-soaked gauze (Eusol) and local cooling.

SummaryA method is described for determination of serum total and organic bound phosphorus using chloric acid digestion and subsequent formation and reduction of a phosphomolybdate complex with p-semidine. The advantages of the method are ease of digestion and color development and stability of color-complex. This method compares well with the Fiske-Subbarow method.

Murder by the intermittent administration of sodium chlorate (weed killer) in beer is reported. Symptomatology, autopsy findings and toxicological analysis are described.