Distinctive properties of fucosyl glycopeptides on human teratoma cells

Fucose-labeled glycopeptides from four human teratoma cell lines of independent origin show similar elution profiles on Sephadex G-50 column chromatography. The fucosyl glycopeptides elute in two major regions: one near the void volume, the other in fractions corresponding to a molecular weight of 2500-3000. These elution profiles are very different from those obtained with the other human cell lines examined which included 3 lymphomas, 2 colon carcinomas, and HeLa. The elution profiles of the human teratomas, however, show remarkable similarities to those obtained with murine embryonal carcinoma cell culture and early mouse embryos. These results suggest that the excluded G-50 fraction may well contain glycopeptides playing a role in mammalian embryogenesis.     

Studies on a strain of Fusarium solani (Mart.) Sacc. Isolated from a case of mycotic keratitis

A strain of Fusarium solani (Mart.) Sacc. (IMI-216517), isolated from a patient of mycotic keratitis, produced experimental keratomycosis in albino rabbit cornea and survived in internal tissues of albino mice for varying periods. Alantolactone, isolated from the plant — Inula racemosa Hook. f. exhibited marked in vitro fungistatic activity against this strain of F. solani at 100–200 g/ml concentrations. The strain was less sensitive to amphotericin B and showed more acid than alkaline proteinase and phosphatase activities.Communication No. 2526.     

Behavioural displays to gustatory stimuli in newborn rabbit pups

Motor displays in the face and head regions of 33 neonate rabbits(less than 24 hrs post partum) in response to taste stimulationwere examined. A droplet of taste solution was placed mediallyon the pup's lips and the ensuing behavioral repertoire wastallied over a 60 sec period in a double blind situation. Tastantsincluded 2 concentrations each of sucrose, saccharin, citricacid and quinine. Distilled water was used as a stimulant andfor intertrial rinses. Response characteristics to the varioustaste stimuli were differentiable, specific and reproduciblewithin and across animals. Certain response features were moreoften associated with one stimulus than with another. Quinineoften produced mouth opening (gaping) and head movements, whereassucrose was associated with a quiet animal licking and makingcharacteristic mouth movements. Sour reactions often resembledthose to sweet, but other features helped distinguish thoseresponses. Reactions proved to be concentration-dependent anddifferent from those to water. Quality and hedonic value wereusually accurately judged and corresponded to adult preferencebehaviors. It was inferred that rabbits at this early age arealready equipped with a functioning taste system up to the brainstemlevel. Cross-species comparisons of stereotyped reactions werediscussed.     

Relaxation of solvent protons by cobalt bovine carbonic anhydrase.

In a recent report, Bertini et al. (Biochem. Biophys. Res. Comm.78, 158–160 (1977)) argued that the low-pH form of Co²⁺-substituted bovine carbonic anhydrase contains a rapidly exchanging water molecule at the cobalt site. The basis for this was the observation of a pH-independent contribution to the solvent water proton relaxation rate; it was suggested that the result was unobserved by previous workers because of the presence of sulfate in the sample buffer. We have repeated the experiments of Bertini et al. and find that the results can be attributed to an ionic strength-induced shift of the pK of the group responsible for the relaxation enhancement. The amount of high-pH form of the enzyme present (determined spectrophotometrically) at every pH correlates with the relaxation rate, whereas the fraction of high-pH form present at a given pH depends on ionic strength. These results are in agreement with earlier data indicating that the low-pH form of the enzyme does not contribute to solvent water proton relaxation.     

Magnetic cross-relaxation among protons in protein solutions.

The magnetic spin-lattice relaxation rates of solvent water nuclei are known to increase upon addition of diamagnetic solute protein. This enhancement of the relaxation rate is a function of magnetic field, and the orientational relaxation time of the protein molecules can be deduced from analysis of the field-dependent relaxation rates. Although the nature of the interactions that convey information about the dynamics of protein motion to the solvent molecules is not established, it is known that there is a contribution to the relaxation rates of solvent protons that plays no role in the relaxation of solvent deuterons and 17O nuclei. We show here that the additional interaction arises from a cross-relaxation process between solvent and solute protons. We introduce a heuristic three-parameter model in which protein protons and solvent protons are considered as two separate thermodynamic systems that interact across the protein-solvent interface. The three parameters are the intrinsic relaxation rates of each system and a cross-relaxation term. The sign of the latter term must always be positive, for all values of magnetic field, in order for magnetization energy to flow from the hotter to the cooler system. We find that the magnetic field-dependence of the cross-relaxation contribution is much like that of the remaining solvent proton relaxation, i.e., about the same as the deuteron relaxation field dependence. This finding is not compatible with the predictions of expressions for the cross-relaxation that have been used by other authors, but not applied to data over a wide range of magnetic field strength. The model predicts that the relaxation behavior of both the protein protons and the solvent protons is the sum of two exponentials, the relative contributions of which would vary with protein concentration and solvent isotopic composition in a fashion suggestive of the presence of two classes of protein protons, when there is in reality only one. This finding has immediate implications for the interpretation of published proton relaxation rates in complex systems such as tissues; these data should be reexamined with cross-relaxation taken into account.     

Characterization of the antibiotic resistance plasmid ERL1 from Streptococcus pyogenes

Summary The streptococcal plasmid ERL1 determining inducible resistance to erythromycin, lincomycin, and staphylomycin S was isolated by dye-buoyant density centrifugation and shown to have a molecular weight of about 17.5 Mdal, as revealed by sedimentation through neutral sucrose gradients. In SM60 cells entering the stationary phase its covalently closed circular form was present to the extent of 5 copies per chromosomal genome equivalent. ERL1 was subject to the DNA restriction and modification mechanism discovered in strain 56188. It did not apear to exercise restriction of phage DNA but mediated a partial release of the restricted growth of A25.     

Response of poly(adenylic acid) polymerase in rat liver nuclei and mitochondria to stravation and re-feeding with amino acids.

Poly(adenylic acid) polymerase was extracted from liver nuclei and mitochondria of rats either fed ad libitum, starved overnight or starved and then re-fed with a complete amino acid mixture for 1-3 h. The enzymes were partially purified and assayed by using exogenous primers. Starvation resulted in an 80% decrease in the total activity of the purified nuclear enzyme, and the mitochondrial enzyme activity diminished to almost zero after overnight starvation. Measurements of the protein content of whole nuclei or mitochondria and of the enzyme extracts from these organelles indicated that the decrease in enzyme activity on starvation was not caused by incomplete extraction of the enzyme from the starved animals. Re-feeding the animals with the complete amino acid mixture increased the total activity of poly(A) polymerase from the nuclei and mitochondria by 1.9-fold and 63-fold respectively. Under these conditions, the total protein content of the nuclei and mitochondria increased by only 13 and 32% respectively. These data indicate that poly(A) polymerase is one of the cellular proteins specifically regulated by amino acid supply.     

Tissue fixation and osmium black formation with nonvolatile octavalent osmium compounds

Summary Several compounds of osmium^VIII, including potassium osmiamate and coordination complexes of OsO₄ with ammonia and various heterocyclic nitrogen compounds, have been synthesized and characterized. They have also been evaluated as substitutes for OsO₄ in postfixation of biological specimens and in light and electron microscopic cytochemical methods resulting in osmium black formation.The most useful of these osmic compounds, a molecular addition complex of hexamethylenetetramine (methenamine) with OsO₄, has a negligible vapor pressure of OsO₄. It has the molecular formula C₆H₁₂N₄.2OsO₄ and has been designated osmeth. Although it has only limited solubility, aqueous solutions of the compound (or of OsO₄) can be rapidly prepared by dissolution in a minimal amount of dimethylformamide and subsequent dilution with distilled water or buffer. Although stable in the solid state, the complex in solution undergoes partial dissociation releasing OsO₄, and the odor of OsO₄ becomes apparent.Such solutions of osmeth are (0.25%) considerably less concentrated with respect to OsO₄ than solutions (1–2%) ordinarily employed for ultrastructural preservation or in cytochemical studies. Osmeth has limited value for postosmication after glutaraldehyde fixation because the generation (release) of OsO₄ appears to be slow. Adequate osmication of tissue blocks exists only at the surface, but effective osmication can be achieved throughout tissue sections. In cytochemical reactions resulting in the formation of osmium blacks, the osmeth solutions are as effective as OsO₄ solutions of equivalent concentrations. Our findings indicate that OsO₄ solutions of less than 1% may be satisfactorily utilized in many cytochemical studies.Osmeth is safer and more convenient to handle than OsO₄ because small amounts may be solubilized as needed. It should be considered as a substitute for OsO₄ in ultrastructural cytochemistry.This investigation was supported by NIH research grant number DE 02668 from the National Institute of Dental Research and by NIH grant number RR 05333 from the Division of Research Facilities and ResourcesVisiting Professor, Dental Research Center, University of North Carolina at Chapel Hill, Jan.-May, 1975. Supported in part by USPHS Grant HD 09209