Carbohydrates of influenza virus. Structure of the oligosaccharides linked to asparagines 406 and 478 in the hemagglutinin of fowl plague virus,strain dutch

Fowl plague virus, strain Dutch, was metabolically labeled withd-[2-³H]mannose, or withd-[6-³H]glucosamine, and the small subunit (HA₂; 0.8 mg in total) of the viral hemagglutinin was isolated by preparative sodium dodecylsulfate-polyacrylamide gel electrophoresis. After proteolytic digestion, the radioactive oligosaccharides were sequentially liberated from the glycopeptides by treatment with different endo--N-acetylglucosaminidases and with peptide:N-glycosidase or, finally, by hydrazinolysis. In this manner, four groups of glycans could be obtained by consecutive gel filtrations and were subfractionated by HPLC. The structures of the individual oligosaccharides were analyzed by micromethylation, by acetolysis or by digestion with exoglycosidases. The major species amongst the high mannose glycans at Ans-406 of the viral glycopolypeptide were found to be Man1-2Man1-3(Man1-2Man1-6)Man1-6(Man1-2Man1-2Man1-3)Man1-4GlcNac1-4GlcNAc and Man1-3(Man1-2Man1-6)Man1-6(Man1-2Man1-2Man1-3)Man1-4GlcNAc1-4GlcNAc, while the complex glycans at Asn-478 are predominantly GlcNAc1-2Man1-3(GlcNAc1-2Man1-6)Man1-4GlcNAc1-4GlcNAc (lacking, in part, one of the outerN-acetylglucosamine residues) and GlcNAc1-2Man1-3(Gal1-4GlcNAc1-2Man1-6)Man1-4GlcNAc1-4GlcNAc.Abbreviation BSA bovine serum albumin - endo D (F,H) endo--N-acetyl-d-glucosaminidase D (F,H) - HA hemagglutinin (HA₁, large subunit of HA - HA₂ small subunit - FPV fowl plague virus - PNGase F peptide:N-glycosidase F - SDS sodium dodecylsulfate     

On the Phospholipid Metabolism of Glial Cell Primary Cultures.

Abstract: Primary cultures were prepared from newborn rat brain. After 16-18 days, they consisted mainly of mature and immature astrocytes and oligodendrocytes, as judged by immunohistochemistry. To study the metabolism of ethanolamine glycerophospholipids, the cells were incubated with 1-[1-³H]alkyl- sn -glycero-3-phosphoethanolamine (1-alkyl-GPE), for 1–20 h. Five main products were formed: 1-alkyl-2-acyl-GPE; 1-alkyl-2-acyksn-glycero-3-phosphocholine (1-alkyl-2-acyl-GPC); 1-alkenyl-2-acyl-GPE (ethanolamine plasmalogen); 1-alkenyl-2-acyl-GPC (choline plasmalogen); and 1-alkyl-glycerol. Acylation of the substrate was the main reaction during the first 3 h of incubation, whereas desaturation to plasmaiogen reached a maximum after 12 h. Greater amounts of radioactivity were observed in the phosphatidylcholine fraction after longer incubation times. Only small amounts of choline plasmalogen were observed. The phosphatidylethanolamine fraction consisted of 26.5% diacyl-, 27.5% alkyl-acyl-, and 46.0% alkenyl-acyl- compounds, whereas the corresponding data for the phosphatidylcholine fraction were 78.5, 16.4, and 5.1%, respectively, after 20 h of incubation. Hydrolysis of the substrate to 1-alkyl-glycerol was a minor reaction.     

Mechanisms of cell differentiation: Affinity of a morphogenetic factor to DNA

Summary A morphogenetic factor which induces inTriturus gastrula ectoderm tissues which are derived from mesoderm and endoderm has been extracted from chicken and amphibian embryos. The factor which is protein in nature has been obtained from chicken embryos in a highly purified state.The biological activity of the chicken factor is partially inhibited when the factor is combined with chicken DNA or sonicated chicken DNA.When the 3H-labelled factor is combined with sonicated DNA and then centrifuged on a sucrose gradient the factor migrates in part with the DNA. This indicates that the factor is bound to DNA.The inferences from these results are discussed with regard to the possible mechanism of action of the factor and the molecular mechanism of differentiation.     

Biosynthetic pathways of Vibrio succinogenes growing with fumarate as terminal electron acceptor and sole carbon source

1. With fumarate as the terminal electron acceptor and either H₂ or formate as donor, Vibrio succinogenes could grow anaerobically in a mineral medium using fumarate as the sole carbon source. Both the growth rate and the cell yield were increased when glutamate was also present in the medium.
2. Glutamate was incorporated only into the amino acids of the glutamate family (glutamate, glutamine, proline and arginine) of the protein. The residual cell constituents were synthesized from fumarate.
3. Pyruvate and phosphoenolpyruvate, as the central intermediates of most of the cell constituents, were formed through the action of malic enzyme and phosphoenolpyruvate synthetase. Fructose-1,6-bisphosphate aldolase was present in the bacterium suggesting that this enzyme is involved in carbohydrate synthesis.
4. In the absence of added glutamate the amino acids of the glutamate family were synthesized from fumarate via citrate. The enzymes involved in glutamate synthesis were present.
5. During growth in the presence of glutamate, net reducing equivalents were needed for cell synthesis. Glutamate and not H₂ or formate was used as the source of these reducing equivalents. For this purpose part of the glutamate was oxidized to yield succinate and CO₂.
6. The α-ketoglutarate dehydrogenase involved in this reaction was found to use ferredoxin as the electron acceptor. The ferredoxin of the bacterium was reoxidized by means of a NADP-ferredoxin oxidoreductase. Enzymes catalyzing the reduction of NAD, NADP or ferredoxin by H₂ or formate were not detected in the bacterium.

     

On the phospholipid metabolism of glial cell primary cultures

Primary cultures prepared from newborn rat brain, consisted after 16 or 17 days mainly of astrocytes and of oligodendrocytes. 1-Alkenyl-sn-glycero-3-phosphoethanolamine (lysoplasmalogen) was used as substrate for studies on the metabolism of ethanolamine-glycerophospholipids. After 3 hr incubation two main products were observed: a) 1-alkenyl-2-acyl-sn-glycero-3-phosphoethanolamine (=ethanolamine plasmalogen) and b) 1-alkenyl-2-acyl-sn-glycero-3-phosphocholine (=choline plasmalogen). The acylation rate reached saturation at about 10 nmol substrate/mg cell protein with aV _max of 30 nmol×mg cell protein^–1×3 hr^–1. This acylated compound amounted to almost 60% of all radioactivity internalized, whereas the second product, choline plasmalogen, came to 20%. Unchanged substrate was found within the cells only in small amounts, even at maximum substrate internalization. These results were discussed in comparison with those obtained with 1-alkyl-sn-glycero-3-phosphoethanolamine under the same conditions (25).     

Citric Acid Fermentation by Aspergillus niger on Low Sugar Concentrations and Cotton Waste

The possible use of cotton waste as a carbohydrate source of citric acid production by Aspergillus niger was examined. No citric acid was produced when A. niger was grown on cotton waste as a sole carbon source. In two-stage fermentations, however, mycelium obtained from surface cultures in cotton waste medium yielded more citric acid when transferred to sucrose-containing media than when directly inoculated to sucrose-containing media. It is concluded that cotton waste can be used for saving sucrose and for increasing yields of citric acid fermentation by A. niger.     

Formation of mesodermal pattern by secondary inducing interactions

Summary A highly purified vegetalizing factor induces endoderm preferentially in amphibian gastrula ectoderm. After combination of this factor with less pure fractions, a high percentage of trunks and tails with notochord and somites are induced. The induction of these mesodermal tissues depends on secondary factors which may act on plasma membrane receptors of the target cells. The secondary factors are probably proteins as they are inactivated by trypsin or cellulose-bound proteinase K. They are not inactivated by thioglycolic acid.The implication of these findings for tissue determination and differentiation in normal development in relation to the anlageplan for endoderm and mesodermal tissues is discussed.     

The activation by Ca of the ATPase of extracted muscle fibrils with variation of ionic strength, pH and concentration of MgATP

1. The alteration of the Ca²⁺ requirements of the ATPase activity of fibrils from rabbits and crabs at varying ionic strength, pH and concentration of MgATP (i.e. MgATP²⁻ + MgHATP⁻) was investigated.

2. Under physiological conditions, it was found that the ATPase activity of rabbit and crab fibrils after an initial increase decreased steeply when the Ca²⁺ concentration is raised above 1×10⁻⁴ M. This is a primary effect of the over-optimal Ca²⁺ concentration and not a secondary one caused by the influence of accompanying ions.

3. The Ca²⁺ requirements for ATP splitting by rabbit fibrils remain constant at an ionic strength from 0.1 to 0.2 and for a MgATP concentration in the range from 0.5 to 10 mM. At I = 0.05 it is about 5 times smaller than at 0.1. When the pH is decreased from 8 to 7, the Ca²⁺ requirements are increased some 10 times but only 3 times when the pH is varied between 7 and 6.

4. In crab fibrils, there is no alteration of the Ca²⁺ requirements when the ionic strength is varied between 0.05 and 0.2, but a reduction of the pH from 8.0 to 6.0 raises the Ca²⁺ requirements for half activation and for threshold by a factor of 10. Changing the MgATP concentration increases the Ca²⁺ requirements only in the range from 1 to 5 mM, while the concentration required in 0.5 mM is identical with that at 1 mM, and 10 mM corresponds to 5 mM.

5. It can be deduced from the experimental results that at a pH above 6.0 maximal activation is always obtained if the Ca²⁺ concentration is 5×10⁻⁵ M. By contrast, relaxation is only achieved when the Ca²⁺ concentration is below 1×10⁻⁷ M for pH 7.0 and I > 0.1 or below 1×10⁻⁸ for pH > 7.0 or I < 0.1.

6. To achieve complete relaxation, an ethyleneglycoldiaminotetraacetate (EGTA) concentration of 1 mM is sufficient, even when there is a large degree of contamination by Ca²⁺ as long as the pH stays above 6.5.