Cross-sectional Area-corrected Compression Modulus of Food Gel

The linearity of the stress-strain relationship for food gel is limited to a very narrow range of the strain (usually less than 0.1 as a Cauchy measure). The reason is thought due to the change in cross-sectional area of the gel upon deformation. In this report, the cross-sectional area was approximately corrected of the compressed gel on the assumption that the gel expanded uniformly without changing its volume upon compression. In cases when the initial Young’s modulus was calculated from the thus-corrected area for some food gels, the linearity was increased for a wider range of strain.     

Cancer Cell Analyses at the Single Cell-Level Using Electroactive Microwell Array Device

Circulating tumor cells (CTCs), shed from primary tumors and disseminated into peripheral blood, are playing a major role in metastasis. Even after isolation of CTCs from blood, the target cells are mixed with a population of other cell types. Here, we propose a new method for analyses of cell mixture at the single-cell level using a microfluidic device that contains arrayed electroactive microwells. Dielectrophoretic (DEP) force, induced by the electrodes patterned on the bottom surface of the microwells, allows efficient trapping and stable positioning of single cells for high-throughput biochemical analyses. We demonstrated that various on-chip analyses including immunostaining, viability/apoptosis assay and fluorescent in situ hybridization (FISH) at the single-cell level could be conducted just by applying specific reagents for each assay. Our simple method should greatly help discrimination and analysis of rare cancer cells among a population of blood cells.     

NdhO,a Subunit of NADPH Dehydrogenase,Destabilizes Medium Size Complex of the Enzyme in Synechocystis sp. Strain PCC 6803

Two mutants that grew faster than the wild-type (WT) strain under high light conditions were isolated from Synechocystis sp. strain PCC 6803 transformed with a transposon-bearing library. Both mutants had a tag in ssl1690 encoding NdhO. Deletion of ndhO increased the activity of NADPH dehydrogenase (NDH-1)-dependent cyclic electron transport around photosystem I (NDH-CET), while overexpression decreased the activity. Although deletion and overexpression of ndhO did not have significant effects on the amount of other subunits such as NdhH, NdhI, NdhK, and NdhM in the cells, the amount of these subunits in the medium size NDH-1 (NDH-1M) complex was higher in the ndhO-deletion mutant and much lower in the overexpression strain than in the WT. NdhO strongly interacts with NdhI and NdhK but not with other subunits. NdhI interacts with NdhK and the interaction was blocked by NdhO. The blocking may destabilize the NDH-1M complex and repress the NDH-CET activity. When cells were transferred from growth light to high light, the amounts of NdhI and NdhK increased without significant change in the amount of NdhO, thus decreasing the relative amount of NdhO. This might have decreased the blocking, thereby stabilizing the NDH-1M complex and increasing the NDH-CET activity under high light conditions.     

Electrical Characteristics of the Tonoplast of Cham corallincr. A Study Using Permeabilised Cells

Use of permeabilised cells of Chara corallina provides a uniqueopportunity to study the electrical characteristics of the tonoplastwhilst being able to control ionic conditions on the outsideof the membrane. Current-voltage (I/V) analysis over wide voltagespans, and admittance measurements at 5 Hz showed that manypermeabilised cells had a similar conductance and capacitanceto the tonoplast of intact cells. Cells developed two regionsof negative-slope conductance upon addition of external Cl^–,which suggests the existence of potential-dependent Cl^–channels in the Chara tonoplast. With Cl^– concentrationssimilar to those expected in vivo, the resting potential wasmore sensitive to changes in external K⁺ than Cl^–; however,a decrease in external K⁺ did not significantly alter the shapeof the I/V relation. ¹Present address: Biopysics Laboratory, School of BiologicalSciences, A12, University of Sydney, Sydney, N.S.W., 2006, Australia ²Permanent address: Department of botany, Faculty of Science,University of Tokyo, Hongo, Tokyo 113, Japan (Received May 6, 1987; Accepted September 21, 1987)     

Analysis of human terminal deoxynucleotidyl transferase cDNA expressible in mammalian cells

Human Molt3 cDNA library was constructed using pcD vector system which permits the expression of cDNA inserts in mammalian cells. Nearly full-length human terminal deoxynucleotidyltransferase (TdT) cDNA was cloned using a fragment of bovine TdT cDNA as a probe. The human TdT cDNA contains an open reading frame of 1,557 bp coding for 519 amino acids, including 31 bp and 341 bp from 5' and 3' untranslated regions, respectively. The TdT cDNA was transfected into COS7 monkey fibroblasts directed the synthesis of enzymatically active protein of Mr 59,495. The cloned TdT cDNA hybridized with poly A+ RNAs of 2,100 b and 3,300 b from stable T-cell leukemia Molt3 and Molt4 cells.     

Regional assignment of the gene for diphtheria toxin sensitivity using subchromosomal fragments in microcell hybrids

Human x mouse microcell hybrids resistant to G418 were constructed between mouse hepatoma cells and human x mouse whole cell hybrids containing only intact human chromosome 5 and 22 with an integrated neo ^r-gene. Among these, microcell hybrid BG15 produced four subclones, BG15-4, BG15-6, BG15-7 and BG15-9, which contained variously sized complements of human chromosome 5. BG15-6 contained an intact human chromosome 5, BG15-7 a deleted human chromosome 5 (5pter-q22) and BG15-4 and BG15-9 a translocation between parts of human chromosome 5 (pter-qter? and pter-q23, respectively) and a mouse chromosome. Southern DNA blot analysis showed that the human dihydrofolate reductase (DHFR) gene was present in all four subclones, whereas the human homolog of the v-fms gene was present in BG15-4 and 15-6, but absent from BG15-7 and 15-9. BG15-4, 15-6 and 15-9 were sensitive to diphtheria toxin, and only BG15-7 was resistant to the toxin. We used these microcell hybrids to restrict further the regional location of the gene for diphtheria toxin sensitivity to the q23 region of human chromosome 5.     

Regional assignment of five genes on human chromosome 19

A human-mouse hybrid segregant HM76Dd40-6 with new characteristics was derived from the hybrid cell line HM76Dd containing human chromosome 19 as the only human chromosome. Three virus sensitivities located on human chromosome 19 (PVS, E11S and RDRC) were lost in HM76Dd40-6, while six other genes (C3, LDLR, EF2, GPI, PEPD and MANB) were retained. Cytogenetic analysis and in situ hybridization using human or mouse repeated sequences as probes showed that the region q13.1-qter of human chromosome 19 had been replaced by a fragment of mouse chromosome. Our results permit further regional assignment for the following five genes on human chromosome 19: GPI in the region cen-q12, MANB in p13.2-q12, E11S and RDRC in q13.1-qter, and EF2 in pter-q12.     

Role in translation of a triple tandemly repeated sequence in the 5''-untranslated region of human thymidylate synthase mRNA.

A triple tandem repeat (TTR) consisting of 90 nucleotides exists immediately upstream of the ATG initiator codon in human thymidylate synthase (TS) cDNA (pcHTS-1). To investigate the role of the TTR in the expression of the TS cDNA, we used pcHTS-1 to construct mutant cDNA clones in which part of the TTR was deleted or an additional element was inserted. The mutant cDNA plasmid was introduced into murine TS-negative mutant cells and the relative translation efficiencies of the mutant cDNAs were determined by measuring the transient expression of TS activity and the amount of TS mRNA transcribed. The translation efficiency in transient expression of the mutants was increased by deletions covering all the first two repeated elements, and the part of the third closest to the ATG initiator codon, but was not affected by deletions of only parts of the first two repeated elements at the 5' end. The translation efficiency was also not affected by insertion of an additional repeated element into the TTR. These results suggest that the first two repeated elements at the 5' end both have inhibitory effects on translation of the TS mRNA, probably due to the unique structural feature of this element.     

Inhibition of tumor metastasis of lewis lung carcinoma in C57BL/6 mice by intrapleural administration of Lactobacillus casei

Summary The antimetastatic effect of Lactobacillus casei YIT9018 (LC 9018) against Lewis lung carcinoma (3LL) in C57BL/6 mice was determined. Intrapleural (i.pl.) administration of LC 9018 was effective in inhibiting pulmonary metastasis after s.c. inoculation of 3LL tumors into C57BL/6 mice. The combination of i.pl. and intralesional or i.v. injections of LC 9018 also markedly inhibited pulmonary metastasis in 3LL-bearing mice. The i.pl. administration of LC 9018 into mice induced an increase in the number of thoracic exudate cells (TEC) and the cell population in the TEC was mainly polymorphonuclear leukocytes in the early stage, while macrophages were dominant in the late stage. In addition, in vitro cytolytic activity against 3LL cells and natural killer cell activity of TEC were augmented by the i.pl. administration of LC 9018. Furthermore, i.pl. administration of LC 9018 into the mice rendered their lung macrophages tumoricidal for 3LL cells in vitro. These results show that TEC induced by i.pl. administration of LC 9018 played a key role in the inhibtion of metastasis in 3LL-bearing mice.