"Cap" on the tip of Salmonella flagella

Flagellar filaments isolated intact from a Salmonella short-flagella mutant are unable to serve as nuclei for flagellin polymerization in vitro, whereas the filaments reconstructed in vitro from the mutant flagellin are able to do so. The inability of intact flagella to nucleate flagellin polymerization appears to be common to wild-type bacteria and thus suggests that the tip of intact flagella are generally inactivated or capped in vivo. Careful observations of the tips of intact flagella and reconstructed flagellar filaments of a wild-type species have revealed marked difference between them: the intact flagella usually have blunt ends, whereas reconstructed filaments have concave, "fish-tail" ends. Moreover, a thin structure is often observed attaching to the very end of the intact flagella. We suspect that this "capping" structure is essential to the elongation mechanism of flagellar filaments.     

Serum and tissue coenzyme Q9 in rats with thyroid dysfunctions

Serum and tissue CoQ9 levels were determined in hypothyroid, euthyroid and hyperthyroid rats. A significant negative correlation was demonstrated between serum FT4 or T3 and CoQ9 in rats with various states of thyroid functions. Liver CoQ9 was significantly increased in rats rendered mildly hyperthyroid. There was a significant positive correlation between serum FT4 or T3 and liver CoQ9. While liver CoQ9 did not significantly change in severely hyperthyroid animals, liver mitochondrial CoQ9 showed a significant positive correlation with serum T3. Kidney and heart CoQ9 levels did not significantly change in hyperthyroid rats, but those in hypothyroid rats showed a tendency to increase. It was suggested that the synthesis of CoQ9 was increased in the liver in hyperthyroidism.     

Regulation of sperm flagellar movement by protein phosphorylation and dephosphorylation

Flagellar motility of Triton models of sea urchin spermatozoa was reactivated by cyclic AMP-dependent protein kinase and a protein factor, termed motility activator, both of which were prepared from the detergent-extract of sea urchin spermatozoa. It was shown that phosphorylation of the motility activator by the protein kinase is necessary for the reactivation of flagellar motility [Ishiguro et al, J. Cell Biol. 92:777-782, 1982; Murofushi et al, in "Biological Functions of Microtubules and Related Structures," Academic Press, 1982]. Reactivating factor was also detected in a KCl-extract of the axoneme fraction devoid of the detergent-extractable materials. The activity of this factor was also cyclic AMP- and protein kinase-dependent. Furthermore, when freshly prepared Triton models were treated with phosphoprotein phosphatase prepared from bovine cardiac muscle, the flagellar motility was drastically suppressed. This inhibition of the motility was partially recovered by the addition of cyclic AMP and protein kinase to the phosphatase-treated models.     

Conformation of sequential polypeptides of (Lysi-Leuj), (Lysi-Serj), and (Lys-Gly) in sodium dodecyl sulfate solution

A series of sequential polypeptides (Lys_iR_j)_n (R is Leu, Ser, or Gly) and random copolypeptides, (Lys^x, Leu^y)_n, were synthesized. Their conformation in NaDodSO₄ solution was determined by CD. Only (Lys-Leu)_n, (Lys-Ser)_n, and (Lys₃-Ser)_n adopt a stable β-form in the surfactant solution; (Lys-Ser₂)_n, (Lys-Ser₃)_n, (Lys₂-Ser₂)_n, and (Lys₂-Ser)_n have an unstable β-form, which reverts to an unordered form in high NaDodSO₄ concentrations, even though both Ser and DodSO-bound Lys⁺ are β-formers. In contrast, (Lys-Gly)_n remains unordered in NaDodSO₄ solution. On the other hand, Lys-rich (Lys₂-Leu)_n forms an unstable helix and (Lys₂-Leu₂)_n a stable helix in NaDodSO₄ solution. In 25 mM NaDodSO₄ (Lys^x, Leu^y)_n also forms a helix up to x = 75 and reverts to the β-form at x = 90. This compares with the helical conformation of (Lys^x, Ala^y)_n up to x = 65 and its β-form at x = 90, suggesting that Leu is an even stronger helix-former than Ala. Our results may provide a plausible explanation for the increase in helicity and disruption of the β-form for many proteins in NaDodSO₄ solution, that is, the polypeptide chain of a protein usually favors a helical conformation over a β-form in the presence of excess surfactant.     

A novel opioid peptide, leumorphin, acts as an agonist at the kappa opiate receptor

The primary structure of the common precursor of porcine beta-neo-endorphin and dynorphin (preproenkephalin B) has shown the existence of a third leucine-enkephalin (leu-enkephalin) sequence with a C-terminal extension of 24 amino acids. This nonacosapeptide, named leumorphin, was approximately 70 times more potent than leu-enkephalin in inhibiting the contraction of the myenteric plexus-longitudinal muscle preparation of the guinea pig ileum. This action of leumorphin, like those of beta-neo-endorphin and dynorphin, was antagonized less effectively by naloxone than that of leu-enkephalin, but more effectively by Mr2266, an antagonist relatively specific for the kappa type opiate receptor. The inhibitory action of leumorphin or beta-neo-endorphin on the contraction of the guinea pig ileum muscle strip was reduced in a dose-dependent manner by pretreatment with dynorphin and vice versa. Leumorphin as well as beta-neo-endorphin and dynorphin inhibits the contraction of the rabbit vas deferens which is known to have only the kappa type opiate receptor. This action was also effectively antagonized by Mr2266. It is concluded that leumorphin has potent opioid activity and acts at the kappa receptor, like other opioid peptides derived from preproenkephalin B.     

Evidence for a presynaptic blockage of transmission in a temperature-sensitive mutant of Drosophila

In the temperature sensitive mutant of Drosophila, shibirets1 (shi), synaptic transmission in the dorsal longitudinal flight muscles (DLM) is normal at 19 degrees C, but is diminished progressively as the temperature is raised, and is blocked at 29 degrees C. The purpose of this paper is to determine whether this defect is located presynaptically, postsynaptically, or both. It is demonstrated here that the postsynaptic sensitivity to L-glutamate, the putative transmitter for this synapse, is not decreased at 29 degrees C. Furthermore, studies conducted with genetic mosaics of this mutant show that transmission is blocked when a mutant motor neuron synapses on a wild-type muscle fiber, but is not blocked when a wild-type motor neuron synapses on a mutant muscle fiber. Thus, the shi phenotype (temperature dependent transmission block) correlates with a shi motor neuron, not with a shi muscle fiber. The data, therefore, suggest that the defect is not postsynaptic, but presynaptic.     

Serologic dissection of HLA-D specificities by the use of monoclonal antibodies

To study the gene products of the HLA complex, we produced two monoclonal antibodies, termed HU-18 and HU-23. They were active in complement-dependent cytotoxicity and detected B-cell alloantigens encoded by a locus (or loci) linked to HLA. When three types of HLA-DR4 homozygous B-cell lines with different HLA-D specificities were tested for reactivity with HU-18 and HU-23, they displayed distinct reaction patterns depending on the HLA-D specificities they possessed: EBV-Wa (HLA-DYT homozygous), negative for both HU-18 and HU-23; KT2 and KOB (HLA-DKT2 homozygous), positive only for HU-18; and ER (HLA-Dw4 homozygous), positive for both. These differential reaction patterns were further confirmed by testing against a panel of 17 HLA-DR4-positive peripheral blood lymphocytes with known HLA-D specificities. Thus, these monoclonal antibodies allow us to identify HLA-DYT, HLA-DKT2, and HLA-Dw4 solely by serologic methods. This is the first clearcut serologic identification of these three HLA-DR4-associated HLA-D specificities, which have been indistinguishable by conventional serology and identified only by cellular techniques. It is hoped that immunochemical investigations using HU-18 and HU-23 will advance our understanding of the HLA-D region on a molecular level.     

Acid-base equilibrium in aerobic fermentations: influence of unutilizable acids and bases on acetic acid concentration in culture liquid

An investigation was made on the factors influencing the acetic acid concentration in the culture liquid of the aerobic fermentations where acetie acid was used as a carbon source. The acetic acid concentration in the culture liquid changed in proportion to the amount of unutilizable acid or base supplied. This was explained by the principle of conservation of electroneutrality. Another factor affecting the acetic acid concentration in the culture liquid was bicarbonate ions which were formed by the dissolution and dissociation of carbon dioxide in the gas phase of the fermentor. The increment in bicarbonate ion concentration was equal to the decrement in the acetie acid concentration in the culture liquid.