Structural analysis of a developmentally regulated 25-kDa protein gene of Sarcophaga peregrina

In the previous paper, we described the identification of two abundant mRNAs of Sarcophaga peregrina (flesh-fly) which are selectively expressed in the fat body of middle third instar larvae. One of these mRNAs was found to encode a protein with a molecular mass of about 25,000 (25-kDa protein) when translated in vitro (Tamura, H., et al. (1983) Dev. Biol. 99, 145-151). Present paper reports the nucleotide sequence of a 2.3 kb DNA containing the entire gene for the 25-kDa protein. This gene consisted of four exons and contained an open reading frame for 184 amino acids. A CAT box and a TATA box were found in the 5'-flanking sequence. A poly A addition signal of AATAAA was assigned to the non-coding region in the fourth exon. A sequence having 75% homology with SV40 enhancer core sequence was identified in the non-coding region of the first exon.     

A new type of blood group B active glycosphingolipid in rat bone marrow cells. Occurrence of the glycolipid in rat immunocytes and ascites hepatoma

A major glycosphingolipid in rat bone marrow cells was purified, and its structure was studied. The glycolipid was found to exhibit blood group B activity by the hemagglutination inhibition test. The structure was determined to be (formula; see text) by studies of nuclear magnetic resonance, sequential hydrolysis by exoglycosidases, linkage analysis of methylated sugars by gas chromatography-mass spectrometry, and immunological tests. The blood group B active glycolipid was detected not only in the bone marrow cells but also in spleen, thymus, and rat ascites hepatoma AH 7974F cells. Besides the glycolipid, gangliotriaosylceramide, gangliotetraosylceramide, and fucogangliotetraosylceramide were commonly detected in these cells. The similarity between the glycolipid species on the cell surfaces of the immunocytes and the tumor cells is discussed with the respect to an escape mechanism of the tumor cells from the immunosurveillance system.     

Purification and characterization of an antibacterial factor from snail mucus

The antibacterial factor from the body surface of the African giant snail, Achatina fulica Férussac, was isolated by DEAE-Toyopearl 650M ion exchange chromatography. The isolated preparation exhibited highly positive antibacterial activity both for the Gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus and for the Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa, but it lost such activity when heated at 75 degrees C for 5 min. The antibacterial factor of the snail mucus was a glycoprotein whose molecular weight (MW) was about 160,000. It was composed of two subunits of MW 70,000-80,000.     

Glycolipid composition of ascitic fluids from patients with cancer

The glycolipid composition of ascitic fluids from nine patients with cancer and one pleural effusion from a hepatoma patient was studied. Glucosylceramide, lactosylceramide, globotriaosylceramide, and globotetraosylceramide were found in all samples and also in normal human serum. These glycolipids accounted for more than 90% of the neutral glycolipid fraction and the composition in ascitic fluids was similar to that in normal human serum. From ascitic fluids, several minor glycolipids, which could not be detected in normal human serum, were isolated and characterized by exoglycosidase treatment. Lactoneotetraosylceramide was found in eight samples of ascitic fluids, and globopentaosylceramide was detected in two samples from hepatoma and one from pancreatic cancer. A fucolipid which was converted to lactoneotetraosylceramide by alpha-L-fucosidase treatment was recognized in two samples from hepatoma patients. In the ganglioside fraction, GM3 was the predominant component both in normal human serum and in ascitic fluid. The GM2 content in ascitic fluids was much higher than that in normal human serum. From these results, lactoneotetraosylceramide and GM2 are possible candidates as cancer markers, because they seemed to be derived from cancer tissues by shedding.     

The alpha-form of S-adenosylmethionine synthetase isozymes from liver is principally functional

Treatment of rats with an ethionine plus adenine or a methionine diet leads not only to a marked increase of the alpha-form isozyme of S-adenosylmethionine synthetase in liver, but also to the accumulation of comparable amounts of S-adenosylethionine and S-adenosylmethionine in liver. Transplantation of ascites tumor cells into mice leads to a marked increase only of the beta-form isozyme in the host liver, but the levels of S-adenosylmethionine do not significantly change in liver.     

Incorporation of sialoglycoprotein containing lacto-series oligosaccharides into chicken asialoerythrocyte membranes and restoration of receptor activity toward hemagglutinating virus of Japan (Sendai virus)

Bovine erythrocyte sialoglycoprotein (GP-2) (1) containing lactoseries oligosaccharide chains, which showed highly specific inhibition of hemagglutination by HVJ (Hemagglutinating virus of Japan, Sendai virus), was incorporated into neuraminidase-treated chicken erythrocytes which had lost their biological responsiveness to the virus. The GP-2-incorporated erythrocytes were agglutinated and lyzed again by the virus. Incorporation of 1,900 molecules of GP-2 per asialoerythrocyte restored fairly well the susceptibility of the cells to HVJ-mediated agglutination and hemolysis. Treatment of the erythrocytes with neuraminidase again resulted in the complete abolishment of the response to HVJ. The above observations are consistent with the view that exogenous sialoglycoprotein, GP-2, can be functionally integrated into the surface membrane of asialoerythrocytes and serve as the receptor for HVJ during the initial adsorption-fusion phase of the virus infection of the target cells.     

Periodic and non-periodic responses of a periodically forced Hodgkin-Huxley oscillator

Membrane potential responses of a Hodgkin-Huxley oscillator to an externally-applied sinusoidal current were numerically calculated with relation to bifurcation parameters of the amplitude and the frequency of the stimulating current. The Hodgkin-Huxley oscillator, or the Hodgkin-Huxley axon in the state of self-sustained oscillation of action potentials, was realized by immersing the axon in calcium-deficient sea water. The forced oscillations were analysed by the stroboscopic plots and/or the Lorenz plots. The results show that the periodically forced Hodgkin-Huxley oscillator exhibits not only periodic motions (harmonic or sub-harmonic synchronization) but also non-periodic motions (quasi-periodic or chaotic oscillation), that the motions were determined by the amplitude and the frequency of the stimulating current, and that the characteristic motions obtained in the present study were in reasonable agreement with those of our previous results, found experimentally in squid giant axons. Also, two kinds of routes to the chaotic oscillations were found; successive period-doubling bifurcations and formation of the intermittently chaotic oscillation from sub-harmonic synchronization.     

Identification of calmodulin in new-born rat calvaria

The extract of new-born rat calvaria was chromatographed on DEAE-cellulose. Calmodulin activity was eluted at 0.3 and 0.4 M NaCl and markedly inhibited by trifluoperazine and W-7, calmodulin antagonists. The fractions with calmodulin activity contained a protein the electrophoretic migration of which on sodium dodecyl sulfate-polyacrylamide gel was accelerated by Ca2+. Its apparent molecular weight was about 18 or 20K in the presence or absence of Ca2+, respectively. With 45Ca-autoradiography, the protein was shown to have a high affinity for Ca2+. Thus calmodulin could be readily identified in new-born rat calvaria.