Effect of Clostridium perfringens Beta Toxin on Blood Pressure of Rats

Guanethidine treatment or adrenal medullectomy significantly inhibited the elevation in blood pressure induced by Clostridium perfringens beta toxin, and the combination of the two drastically reduced the pressure rise, to less than 19% of that in control rats. When rats were pretreated with tetrodotoxin or hexamethonium, the toxin-evoked rise was significantly inhibited. Elevation in blood pressure induced by the toxin in spinal rats tended to be less than that in control rats. When investigated by a microscopical technique, arteriolar constriction in the mesenteric vasculature was observed after the blood pressure elevation induced by the toxin reached a maximum. Blood flow in the skin decreased with an increase in blood pressure following intravenous injection of the toxin. It is concluded that beta toxin acts on the autonomic nervous system and produces arterial constriction.     

Ring chromosome 15 in a mother and her children

Summary A case of ring chromosome 15 passed on to the index patient's two children is reported, and possible reasons for the infrequent records of inheritance of ring chromosome are suggested.     

Morphology and Hormone Levels of Tobacco and Carrot Tissues Transformed by Agrobacterium tumefaciens I. Auxin and Cytokinin Contents of Cultured Tissues Transformed with Wild-Type and Mutant Ti Plasmids

Carrot and tobacco plants were transformed with Agrobacteriumtumefaciens harboring wild-type, aux^– or cyt^– Tiplasmids. In tobacco, these wild and mutant Ti plasmids inducedthe formation of non-morphogenic galls, galls with shoots, andgalls with roots, respectively. In carrot, however, transformationwith any of these plasmids resulted in only the formation ofamorphous tumors. Determination of IAA and cytokinin contentsshowed that in tobacco, significantly high amounts of cytokininsor IAA are present in the cells transformed with Ti plasmidspossessing cytokinin or IAA biosynthetic genes, respectively.In carrot, cytokinin contents were also high in the cells transformedwith Ti plasmids having cytokinin biosynthetic genes, whereasIAA contents of the cells were similar regardless of the plasmidsused for transformation. These results suggest that the mechanism regulating IAA metabolismmay be different in tobacco and carrot. (Received June 25, 1987; Accepted February 1, 1988)     

A novel MHC class I-related molecule expressed on mouse thymic stroma cells and mature lymphocytes

A monoclonal antibody (mAb) TP-3 has been established by immunizing rats with the BALB/c mouse thymic epithelial cell line TEL-2. The TP-3 antigen is expressed on stroma cells of thymus, spleen, and lymph node in syngeneic BALB/c mice (H-2 ^d ). This antigen is also expressed at a low level on the cell surface of immature thymocytes, and at a high level on mature T and B cells. In allogeneic mice such as C57BL/6 (H-2 ^b ) or C3H (H-2 ^k ), no cells expressed the TP-3 antigen. Using H-2 congenic mice, reactivity with mAb TP-3 was found to map to a region of H-2D ^d L ^d or between D ^d and Qa, suggesting that TP-3 is a major histocompatibility complex (MHC) class I antigen. However, immunoprecipitation analysis indicated that this antigen is not identical to the classical mouse class I molecules in terms of molecular size, antigenicity, and tissue distribution.     

Mode of antitumor action of recombinant human tumor necrosis factor on the sarcoma Meth A transplanted in the mouse

The mode of antitumor action of rHu-TNF was elucidated in BALB/c mice bearing Meth A fibrosarcoma 7 days after transplantation with respect to time course, dose-response relationships and selectivity of the effects. The maximal cytotoxic effect on tumor cells revealed by inhibition of DNA synthesis and maximal lesional effect on tumor vasculature revealed by change in blood pool-size in the tissue were detected at 30 min and I h after administration of rHu-TNF, respectively. The dose-response relationship between cytotoxic and tumoricidal effects of rHu-TNF was irrespective of administration route. ED₅₀s of these antitumor effects afteri.v. administration of rHu-TNF were about 50 times as high as ED₅₀s afteri.t. administration. ED₅₀ ofi.t. given rHu-TNF for vascular effect was about 20 times as high as that for cytotoxicity while ED₅₀ ofi.v. rHu-TNF for vascular effect was only 2–3 times as high as that for cytotoxicity. The whole body autoradiographies with [¹²⁵I] HSA giveni.v. to see the blood influx into tumor tissue and [¹⁴C]thymidine given i.v. to see DNA synthesis in the whole body after administration of rHu-TNF revealed that the distribution of radioactivity was markedly changed in the tumor alone without any detectable change in other whole body tissues.In conclusion, thein vivo antitumor effect of rHu-TNF giveni.t. ori.v., appears to be exerted through the direct action on Meth A sarcoma rather than indirectly on tumor vasculature. Under present conditions, the effect of rHu-TNF in the whole body tissues seems rather selective on cells and vasculature of the tumor.     

Identification of a common molecular basis for combined 17α-hydroxylase/17,20-lyase deficiency in two Mennonite families

Summary During the course of studies to characterize mutations of the CYP17 gene that cause the 17-hydroxylase-deficient form of congenital adrenal hyperplasia we have discovered two ostensibly unrelated Mennonite families in which affected individuals are homozygous for the same mutation. The defect is a four-base duplication in exon 8 of the CYP17 gene, which alters the reading frame encoding the C-terminal 26 animo acids of cytochrome P450₁₇.     

Identification of Mutations in the Pigment Cell-Specific Gene Located at the Brown Locus in Mouse

The pigment cell-specific gene, located at the brown (b)-locus in mouse, encodes the protein that determines the type of melanin synthesized. This protein is known as tyrosinase-related protein, but here we tentatively term it b-locus protein to avoid confusions with the related sequence cross-hybridizing to the tyrosinase gene. In order to identify the mutation at the b-locus, we have cloned and characterized the b-locus protein gene of BALB/c mouse (b/b, c/c). The gene is about 18 kb long and organized into 8 exons and 7 introns. Sequence analysis of the b-locus protein gene reveals four base changes within the protein-coding regions: two missense mutations and two silent mutations. Two missense mutations result in the Cys to Tyr substitution at position 86 (codon 110) and the Arg to His substitution at position 302 (codon 326) of a b-locus protein molecule. Using allele-specific amplification, we confirmed that these missense mutations are actually present in the genomic DNA of two b-mutant strains examined, BALB/c and DBA/2 (b/b, C/C) mice, suggesting that these mutations are specific for the mutant mice at the b-locus. Moreover, we are able to show that the b-locus protein containing Tyr 86 is not reactive with the anti-b-locus protein monoclonal antibody, TMH-1, in transient expression assays.     

Parallel evolution in radiation ofOhomopterus ground beetles inferred from mitochondrial ND5 gene sequences

Molecular phylogenetic analyses using mitochondrial NADH dehydrogenase subunit 5 (ND5) gene sequences representing all 15 species and the majority of subspecies or races of theOhomopterus ground beetles from all over the Japanese archipelago have uncovered a remarkable evolutionary history. Clustering of the species in the molecular phylogenetic tree is linked to their geographic distribution and does not correlate with morphological characters. Taxonomically the same species or the members belonging to the same species-group fall out in more than two different places on the ND5 tree. Evidence has been presented against a possible participation of ancestral polymorphism and random lineage sorting or of hybrid individuals for the observed distribution of mitochondrial DNA haplotypes. The most plausible explanation of our results is that parallel evolution took place in different lineages. Most notably,O. dehaanii, O. yaconinus, andO. japonicus in a lineage reveal almost identical morphology with those of the same species (or subspecies) but belonging to the phylogenetically remote lineages.The nucleotide sequence data reported in this paper will appear in the DDBJ, EMBL, and GenBank nucleotide sequence databases with accession numbers D50711-DD-50733 and D87131-D87186.     

Characterization of novel mono-O-acetylated GM3s containing 9-O-acetyl sialic acid and 6-O-acetyl galactose in equine erythrocytes

Novel mono-O-acetylated GM3s, one containing 9-O-acetylN-glycolyl neuraminic acid and another containing 6-O-acetyl galactose, were isolated as a mixture from equine erythrocytes, and the structures were characterized by one- and two-dimensional proton nuclear magnetic resonance (NMR) and fast atom bombardment-mass spectrometry (FAB-MS). The position of theO-acetyl residue was identified by the downfield shift of the methylene protons at C-9 ofN-glycolyl neuraminic acid (9-O-Ac GM3) and C-6 of galactose (6-O-Ac GM3) in the NMR spectrum, in comparison to the respective non-acetylated counterparts. To confirm the presence of 6-O-Ac GM3, theO-acetylated GM3 mixture was desialylated withArthrobacter neuraminidase, giving 6-O-acetyl galactosyl glucosylceramide, the structure of which was estimated by NMR and FAB-MS, together with non-acetylated lactosylceramide with a ratio of 1:1. Abbreviations: Ac, acetyl; Gc, glycolyl; NeuGc,N-Gc neuraminic acid; GM3 (Gc), GM3 containing NeuGc (II³NeuGc-LacCer); 4-O-Ac GM3 (Gc), GM3 containing 4-O-Ac NeuGc; 9-O-Ac GM3 (Gc), GM3 containing 9-O-Ac NeuGc; 6-O-Ac GM3 (Gc), GM3 containing 6-O-Ac Gal; 1D-NMR, one-dimensional nuclear magnetic resonance spectrometry; 2D-COSY, two-dimensional chemical shift-correlated spectrometry; FAB-MS, fast atom bombardment-mass spectrometry; GLC, gas-layer chromatography; GC-MS, gas chromatography-mass spectrometry; TLC, thin-layer chromatography; Ggl, ganglioside; Cer, ceramide; CMH, monohexosylceramide; LacCer, lactosylceramide; 6-O-Ac LacCer, LacCer containing 6-O-Ac Gal; Me₂SO-d₆,²H₆-dimethylsufloxide; CMW, chloroform-methanol-water; Nomenclature and abbreviations of glycosphingolipids follow the system of Svennerholm (J Neurochem [1963]10: 613–23) and those recommended by the IUPAC-IUB Nomenclature Commission (Lipids [1977]12: 455–68).