The fission yeast cut1+ gene regulates spindle pole body duplication and has homology to the budding yeast ESP1 gene

Mutations in the fission yeast cut1+, cut2+, and cut10+ genes uncouple normally coordinated mitotic events and deregulate, rather than arrest, mitosis. DNA synthesis continues, making polyploid nuclei with several spindles. Multiple, aberrant spindle pole bodies (SPBs) are produced in cut1 mutant cells. The cut1+ and cut2+ genes are cloned by transformation. High gene dosage of cut1+ also complements cut2 and cut10 mutants. The cut2+ gene, however, complements only cut2. The 210 kd cut1+ gene product contains putative ATP binding and helical coil regions followed by a COOH-terminal domain homologous to the S. cerevisiae gene ESP1. Mutations in the ESP1 gene also result in many SPBs. The cut1+ product is shown by anti-cut1 antibody to be a rare component of the insoluble nuclear fraction. It may play a key role in coupling chromosome disjunction with other cell cycle events and is potentially a component, regulator, or motor for the SPB and/or kinetochores.     

Failure to Reject an Allografted Tumor after Elimination of Macrophages in Mice

After an i.p. transplantation of an allogeneic tumor (Meth A) to C57BL/6 mice, a macrophage (MΦ)-rich, non-T, non-NK cell population is induced as the major infiltrate and cytotoxic cells. We here evaluated the role of the MΦs in the rejection of allografted Meth A cells and characterized the MΦs in comparison with other well-known MΦs. At all time intervals after transplantation, the highest cytotoxic activities against Meth A tumor were obtained with the MΦ-rich population. In addition, the lymphocyte-rich population had a significant but low cytotoxic activity, whereas two other population types, granulocytes and large granular cells, were inactive. When the MΦ-rich or the T cell-depleted MΦ-rich population was i.p. transplanted simultaneously with Meth A cells into untreated C57BL/6 mice, the tumor cells were rejected without growth. After specific elimination of MΦs by in vivo application of dichloromethylene diphosphonate-containing liposomes, the cytotoxic activity against Meth A cells was hardly induced at the transplantation site of Meth A cells and the allografted Meth A tumor continued to grow, indicating that a type of MΦ is the effector cell essential for the rejection. In contrast to other well-known MΦs, the cytotoxic activity against Meth A cells was cell-to-cell contact dependent and soluble factor (e.g., NO and TNF-α) independent. Moreover, the cytotoxic activity of the MΦs (H-2^b) against ⁵¹Cr-labeled Meth A (H-2^d) cells was inhibited by the addition of unlabeled H-2^d, but not H-2^a, H-2^k or H-2^b, lymphoblasts as well as Meth A cells, implying the specific interaction of the MΦs with H-2^d cells.     

Effects of 1,1-dimethyl-4-(phenylsulfonyl)semicarbazide (DPSS) on carnation flower longevity

The effects of a novel preservative for cut carnation flowers, 1,1-dimethyl-4-(phenylsulfonyl)semicarbazide (DPSS), were investigated. DPSS extended the vase life of cut carnation flowers not only by continuous treatment but pulse treatment as well. This inhibition of senescence by DPSS appeared to depend on that of ethylene production in carnation flowers. DPSS provided no protection from the action of ethylene nor did it inhibit 1-aminocyclopropane-1-carboxylic acid (ACC) synthase. It did inhibit ACC-dependent ethylene production in carnation petal discs, suggesting possible potential for inhibiting ACC oxidase.     

Dis3, implicated in mitotic control, binds directly to Ran and enhances the GEF activity of RCC1.

Using the two-hybrid method, we isolated a Saccharomyces cerevisiae cDNA encoding a protein homologous to Schizosaccharomyces pombe protein Dis3sp, using as bait, human GTPase Ran. The DIS3 gene is essential for viability and complements S.pombe mutant dis3-54 which is defective in mitosis. Although Dis3sc has no homology to RanBP1, it bound directly to Ran and the S.cerevisiae Ran homologue Cnr1, but not to the S.cerevisiae RCC1 homologue Srm1. Upon binding to Ran with a 1:1 molar ratio, Dis3sc enhanced a nucleotide-releasing activity of RCC1 on Ran. In the presence of Dis3sc, the K(m) of RCC1 on Ran decreased by half, while the kcat was unchanged. In vivo, Dis3sp was present as oligomers of M(r) 670-200 kDa as previously reported, and the 200 kDa oligomer of Dis3sp was found to include Spi1 and Pim1, the S.pombe homologues of Ran and RCC1, respectively. Although the biological function of the heterotrimeric oligomer consisting of Dis3, Spi1 and Pim1 is unknown, our results indicate that Dis3 is a component of the RCC1-Ran pathway.     

Fission yeast cut3 and cut14, members of a ubiquitous protein family, are required for chromosome condensation and segregation in mitosis.

Fission yeast temperature-sensitive mutants cut3-477 and cut14-208 fail to condense chromosomes but small portions of the chromosomes can separate along the spindle during mitosis, producing phi-shaped chromosomes. Septation and cell division occur in the absence of normal nuclear division, causing the cut phenotype. Fluorescence in situ hybridization demonstrated that the contraction of the chromosome arm during mitosis was defective. Mutant chromosomes are apparently not rigid enough to be transported poleward by the spindle. Loss of the cut3 protein by gene disruption fails to maintain the nuclear chromatin architecture even in interphase. Both cut3 and cut14 proteins contain a putative nucleoside triphosphate (NTP)-binding domain and belong to the same ubiquitous protein family which includes the budding yeast Smc1 protein. The cut3 mutant was suppressed by an increase in the cut14+ gene dosage. The cut3 protein, having the highest similarity to the mouse protein, is localized in the nucleus throughout the cell cycle. Plasmids carrying the DNA topoisomerase I gene partly suppressed the temperature sensitive phenotype of cut3-477, suggesting that the cut3 protein might be involved in chromosome DNA topology.     

Cerebrospinal Fluid Nitrite/Nitrate Levels in Neurologic Diseases

Abstract: Nitric oxide has been proposed to mediate cytotoxic effects in inflammatory diseases. To investigate the possibility that overproduction of nitric oxide might play a role in the neuropathology of inflammatory and noninflammatory neurological diseases, we compared levels of the markers of nitric oxide, nitrite plus nitrate, in the CSF of controls with those in patients with various neurologic diseases, including Huntington's and Alzheimer's disease, amyotrophic lateral sclerosis, and HIV infection. We found that there were no significant increases in the CSF levels of these nitric oxide metabolites, even in patients infected with HIV or in monkeys infected with poliovirus, both of which have significantly elevated levels of the neurotoxin quinolinic acid and the marker of macrophage activation, neopterin. However, CSF quinolinic acid, neopterin, and nitrite/nitrate levels were significantly increased in a small group of patients with bacterial and viral meningitis.     

Enhanced Expression of an Endothelin ETA Receptor in Capillaries from Human Glioblastoma: A Quantitative Receptor Autoradiographic Analysis Using a Radioluminographic Imaging Plate System

Abstract: We identified and characterized ¹²⁵I-endothelin-1 (¹²⁵I-ET-1) binding sites in tumor capillaries isolated from human glioblastomas, using the quantitative receptor autoradiographic technique with pellet sections. Quantification was done using the computerized radioluminographic imaging plate system. High-affinity ET receptors were localized in capillaries from glioblastomas and the surrounding brain tissues (K_D = 4.7 ± 1.0 × 10^?10 and 1.6 ± 0.3 × 10^?10M, respectively; B_max = 161 ± 38 and 140 ± 37 fmol/mg, respectively; mean ± SEM, n = 5). BQ-123, a selective antagonist for the ET_A receptor, potently competed for ¹²⁵I-ET-1 binding to sections of the microvessels with IC₅₀ values of 5.1 ± 0.3 and 5.1 ± 1.5 nM, and 10^?6M BQ-123 displaced 84 and 58% of ET binding to capillaries from tumors and brains, respectively. In addition, competition curves obtained in the presence of increasing concentrations of ET-3 showed two components (IC₅₀ = 5.7 ± 2.5 × 10^?10 and 1.4 ± 0.2 × 10^?6M for tumor microvessels, 1.8 ± 0.6 × 10^?10 and 1.1 ± 0.3 × 10^?6M for brain microvessels, respectively). Our results indicate that (a) the method we used is simple and highly sensitive for detecting and characterizing various receptors in tumor capillaries, especially in the case of a sparse specimen, and (b) capillaries in glioblastomas express specific high-affinity ET binding sites, candidates for biologically active ET receptors, which predominantly belong to the ET_A subtype.     

Brassinolide-Induced Elongation of Inner Tissues of Segments of Squash (Cucurbita maxima Duch.) Hypocotyls

Brassinolide (BR) stimulated elongation of etiolated squashhypocotyl segments with outer tissues removed, as well as thatof unpeeled segments, while IAA has no effect on peeled segments.BR changed the mechanical properties of cell walls of the innertissue. The inner tissue is probably the target tissue in BR-inducedelongation. ¹Dr. Susumu Kuraishi died in 1993.