Level of protein kinase C activity correlates directly with resistance to adriamycin in murine fibrosarcoma cells

In this report, we demonstrate a direct correlation between protein kinase C (PKC) activity and adriamycin (ADR) resistance in mouse fibrosarcoma cells. PKC activity was measured in four murine UV-2237M fibrosarcoma cell lines that differed in the degrees to which they expressed resistance to ADR, which is an inhibitor of PKC. A comparison of the four cell lines revealed a positive correlation between the level of PKC activity and resistance to ADR. Incubation of the cells with the PKC inhibitor H-7 produced a partial reversal of ADR resistance. Taken together, these results suggest a role for PKC in the mechanism of ADR resistance.     

Exon-intron organization, expression, and chromosomal localization of the human motilin gene

The human motilin gene has been isolated and characterized. The gene spans about 9 kilobase pairs (kb) and the 0.7 kb motilin mRNA is encoded by five exons. The 22-amino-acid motilin sequence is encoded by exons 2 and 3. The human motilin gene was mapped to the p21.2----p21.3 region of chromosome 6 by hybridization of the cloned cDNA to DNAs from a panel of reduced human-mouse somatic cell hybrids and by in situ hybridization to human prometaphase chromosomes. RNA blotting using RNA prepared from various regions of the human gastrointestinal tract revealed high levels of motilin mRNA in duodenum and lower levels in the antrum of the stomach; motilin mRNA could not be detected by this procedure in the esophagus, cardia of the stomach, descending colon or gallbladder.     

小麦间期集缩染色质的超微结构研究

本文以普通小麦(Triticum aestivum L.)根端分生组织为材料,在透射电镜下对间期细胞核内的集缩染色质的高层次结构进行了研究。在其中观察到直径约为20—25nm、50nm及110—120nm 的不同等级染色线,并且发现直径110—120nm 的染色线是由50nm 的染色线组成的,而直径约50nm 的染色线是由20—25nm 的染色线组成的。对这三个层次染色质结构之间的集缩方式进行了讨论。     

Macrophage precursors as natural killer cells against tumor cells and microorganisms

Macrophage precursors cells have been isolated from spleen and liver of mice and have characterized using F4/80 antibody, their proliferative response to CSF-1 and their maturation to macrophages. These nonadherent and nonphagocytic cells exert strong killing of Yac-1 tumor cells and of various microorganisms. Transplantation of these macrophage precursors into lethally irradiated allogenic hosts restores natural killer (NK) activity within 14 days. Macrophage precursors show enhanced NK activity when activated with interleukin 2. FACS analysis of F 4/80 presorted macrophage precursors reveals about 30% of the cells coexpressing NK 1.1. and F 4/80. These data support the assumption that at least a part of the NK cell compartment is derived from the myeloid lineage.     

Production and characterization of a monoclonal antibody cross-reactive with most group A trichothecenes

A monoclonal antibody cross-reactive with most group A trichothecenes was produced by fusion of P3/NS-1/1-AG4-1 myeloma cells with spleen cells isolated from a BALB/c mouse that had been immunized with 3-acetyl-neosolaniol-hemisuccinate conjugated to bovine serum albumin. One stable clone, H159B1D5, which produced monoclonal antibody that bound with both T-2 toxin and diacetoxyscirpenol (DAS) was obtained after subcloning. Enzyme-linked immunosorbent assay (ELISA) revealed that the antibody belongs to the immunoglobulin G1 (kappa chain) isotype and had binding constants of 2.81 x 10(9), 1.05 x 10(9), and 1.57 x 10(8) liters per mole for T-2 tetraol tetraacetate, T-2 toxin, and DAS, respectively. The relative cross-reactivities of the antibody with T-2 tetraol tetraacetate, T-2 toxin, and DAS were 200, 100, and 20, respectively, with tritiated T-2 toxin as the marker ligand. The relative cross-reactivities for the above toxins were 667, 100, and 73, respectively, with tritiated DAS as the marker ligand. No cross-reaction with HT-2 and deoxynivalenol triacetate was observed in either system. By using this monoclonal antibody, an indirect ELISA for analysis of T-2 toxin was also developed. The linear portion of the standard curve for analysis of T-2 toxin in each analysis by radioimmunoassay and ELISA was in the range of 0.1 to 2 ng and 0.05 to 1.0 ng, respectively.     

Effects of traces of rare earth elements on the protozoanBlepherisma and on mice

The growth of the protozoanBlepherisma is stimulated by Lanthanum (La) at concentrations as low as 0.32 ppm. In mice Yttrium (Y) and Ytterbium (Yb) are absorbed, accumulated, and metabolized. Both rare earth elements (RE) exhibit a high affinity for teeth and bones, accumulation occurs and metabolism is slow. In the livers of RE-exposed mice, concentrations are variable. The liver is apparently capable of absorbing and discharging RE in a manner depending on metabolic activity. The main route of discharge for ingested REs is the alimentary canal. Exposure of pregnant mice to RE leads to rapid placental transfer of RE; 14.1% of the total amount of RE administered was detected in newborn mice. Young, developing organisms appear to be especially susceptible to RE accumulation.     

Biochemical Mapping of Peptidyl-Glycine α-Amidation Activity in the Rat CNS

Peptidyl-glycine alpha-amidation enzyme activity has been measured in 36 nuclei or areas in the rat CNS and pituitary using D-Tyr-Phe-Gly as the substrate. The distribution of this enzyme is highly uneven, with highest activity levels (greater than 30 pmol/mg of protein/h) in hypothalamic nuclei, substantia grisea centralis, and nucleus ruber; moderate activity levels (10-30 pmol/mg of protein/h) in globus pallidus, septum, midbrain, pons, medulla oblongata, and cervical spinal cord; and low activity levels (1-10 pmol/mg of protein/h) in other telencephalic and thalamic structures. Almost no alpha-amidation activity (less than 0.5 pmol/mg of protein/h) was detected in cerebellar cortex. The Km values in several brain regions are of the same order.     

Characterization of lymphoid tumors induced by a recombinant murine retrovirus carrying the avian v-myc oncogene. Identification of novel (B-lymphoid) tumors in the thymus

Lymphoid tumors induced by a recombinant murine retrovirus carrying the v-myc oncogene of avian MC29 virus were characterized. The Moloney murine leukemia virus myc oncogene (M-MuLV (myc], carried by an amphotropic MuLV helper, induced tumors in NIH Swiss and NFS/N mice after a relatively long latency (8 to 24 wk). Tumor masses appeared in the thymus, spleen, and lymph nodes. Flow cytometry of the tumor cells indicated that approximately 50% were positive for Thy 1.2. Most of these tumors also expressed one or more other cell surface markers of thymocytes and mature T cells (CD4, CD8). Southern blot hybridization revealed genomic rearrangements for the TCR beta genes. The TCR beta analysis suggested that the M-MuLV(myc)-induced Thy 1.2+ tumors were derived from somewhat less mature cells than tumors induced by M-MuLV, which is a classical non-acute retrovirus lacking an oncogene. The remainder of the M-MuLV(myc)-induced tumors were Thy 1.2-, but they were positive for Ly-5 (B220) and also for MAC-2. The Thy 1.2- tumors were characteristically located in the thymus. However, they were negative for TCR beta gene rearrangements. Some, but not all, of the Thy 1.2- tumors contained rearrangements for Ig genes. Additionally, they typically expressed mRNA specific for B but not for T cells. Thus, these thymic tumors had characteristics of the B cell lineage. Tumor transplantation experiments demonstrated that the Thy 1.2- tumor cells could reestablish in the thymus and spleen of irradiated hosts, and low level expression of the Thy 1 molecule was observed in the thymus but not the spleen on the first passage. After serial passage, one Thy 1- tumor altered its cell surface phenotype to Thy 1low B220-.     

Genetic organization and nucleotide sequence of the stability locus of IncFII plasmid NR1

The stability (stb) locus of IncFII plasmid NR1 was mapped to a 1700 base-pair NaeI-TaqI restriction fragment. A series of unstable plasmids that contained insertion, deletion, and point mutations that inactivated the stability function was isolated. The unstable point mutants examined were all stabilized (complemented) in trans by a copy of the wild-type stb locus, suggesting that the mutations had inactivated diffusible gene products. The nucleotide sequence of the stb locus contained two tandem open reading frames, designated stbA and stbB, that encoded essential trans-acting protein products with predicted sizes of 36,000 Mr and 13,000 Mr, respectively. A third open reading frame, stbC, that could encode a peptide of 8000 Mr was contained within stbB in the complementary DNA strand. Plasmid-encoded proteins of 36,000 Mr and 13,000 Mr were identified in minicell experiments as the products of stbA and stbB, respectively. Unstable deletion mutants that retained the promoter proximal region of the stb locus upstream from stbA but had deleted both stbA and stbB were stabilized in trans by plasmids that could supply StbA and StbB. In contrast, deletion mutants that had lost the stbAB promoter region were not complemented in trans, indicating that this region contained an essential cis-acting site (or sites). Unlike some other loci that mediate stable plasmid inheritance, cloned copies of the wild-type stb locus of NR1 did not exert strong incompatibility (i.e. trans destabilization) against other stb+ derivatives of plasmid NR1 present in the same cell.