Effect of cytokines on the proliferation/differentiation of stroma-initiating cells

A culture system that identifies the precursor of murine bone marrow fibroblastic stromal cells (stroma-initiating cells, SIC) has been developed. In this system, mature fibroblasts are depleted by adherence to plastic dishes and the nonadherent cells are seeded at a low density, which results in the formation of colonies composed of fibroblastic cells. Macrophage colony-stimulating factor (M-CSF) has been shown to accelerate the colony formation in the system. In this study, we examined the stroma-inducing activity of a number of cytokines. Neither granulocyte-CSF, stem cell factor, interleukin (IL)-1, IL-6, transforming growth factor, epidermal growth factor, insulin-like growth factor, platelet-derived growth factor, nor fibroblast growth factor showed the activity. Similarly, tumor necrosis factor (TNF) did not show any stroma-inducing activity, but the factor inhibited the stromal colony formation induced by M-CSF. In this study, we found that granulocyte/macrophage-CSF (GM-CSF) and IL-3, as well as M-CSF had the stroma-inducing activity. Neither an additive nor synergistic effect was observed when the three factors were assayed in various combinations. The stroma-inducing activity of M-CSF, GM-CSF and IL-3 was observed even if lineage-negative bone marrow cells were used as target cells, suggesting that mature hematopoietic cells such as macrophages and granulocytes were not involved in the induction of stromal colony formation by these factors. Our results raise the possibility that GM-CSF and IL-3 as well as M-CSF stimulate the proliferation or differentiation of the precursor of bone marrow fibroblastic stromal cells.     

Searching clusters of community composition along multiple spatial scales: a case study on aquatic invertebrate communities in bamboo stumps in West Timor

We examined spatial heterogeneity at multiple scales in composition of the aquatic invertebrate communities in bamboo stumps in a mountainous area of West Timor. We partitioned the study area (ca. 15,000 m²) at five levels of patchiness: two sites, four sub-sites, eight super-clumps, 14 clumps, and 84 stumps. Similarity of community composition between stumps varied more than expected from independent occurrence of each taxon in comparisons within any levels of patches. Negative association was frequently detected among taxa. These results indicate heterogeneity in community composition at a stump level. At higher levels, similarity among stumps within each site was greater than expected from null models which assumed no spatial heterogeneity, and similarities among super-clumps, sub-sites and between sites in a whole area were lower than expected from the null models. The observed patterns in similarities among subsets of the community and distribution of each taxon were mostly consistent with the models which assumed site-level heterogeneity. Therefore, we conclude that the community in this area was spatially heterogeneous at stump and site levels. The relationship between mean intra- and inter-specific crowding suggested that the site level habitat heterogeneity might reduce the chance of encounters between two predators, the larvae of the Toxorhynchites mosquito and the Brachyceran fly.     

Cell adhesive sequences in mouse laminin beta1 chain

Laminin-1, a major component of the basement membrane, consists of three different chains, alpha1, beta1, and gamma1. We sought to identify cell adhesive sequences from the mouse laminin beta1 chain by testing HT-1080 fibrosarcoma and B16-F10 melanoma cells for binding to 187 overlapping synthetic peptides which covered the entire chain. Fourteen peptides showed cell adhesive activities with either peptide-conjugated Sepharose beads or peptide-coated plates or both. Additional cells, including neuronal, endothelial, and salivary gland cells, showed biological responses in a cell type-specific manner. B-7, B-133, and B-160 showed the most potent cell attachment. Cell binding on three peptides (B-34, B-133, and B-160) was inhibited by EDTA. Cell adhesion to 11 of the 12 active peptides was inhibited to varying degrees by heparin. Of the 17 active peptides identified in the laminin beta1 chain in this and other studies, 8 are clustered on the amino terminal globular domain, suggesting a possible important role in cell binding for this domain that may be multifunctional. These data demonstrate that the laminin beta1 chain has multiple active sites for cell adhesion, some of which are cell-type specific.     

Molecular characterization of the SCAR markers tightly linked to the Tm-2 locus of the genus Lycopersicon

The Tm-2 gene and its alleles conferring tomato mosaic virus resistance in tomato originate from Lycopersicon peruvianum, a wild relative of tomato. DNA fragments of several RAPD markers tightly linked with the Tm-2 locus in tomato were successfully cloned and sequenced. Subsequently, the 24-mer oligonucleotide primer pairs of the SCAR markers corresponding to the RAPD markers were designed based on the 5’-endmost sequences. A fragment of the same size as that of a SCAR marker was amplified in the ToMV-susceptible tomato line with no Tm-2, but the digests of the PCR fragments by AccI exhibited polymorphism in fragment length between the two lines. We chose three SCAR markers and three RAPD markers tightly linked with the Tm-2 locus, and examined whether the same-sized fragments corresponding to these markers were also present in three other lines carrying Tm-2a or one of the other Tm-2 alleles. The fragments corresponding to the three SCAR markers were present in all of the three lines, but the other markers (three RAPDs ) were absent in one or two lines, suggesting that the three SCAR markers are closer to Tm-2 than the other markers. Comparison of the nucleotide sequences of these fragments revealed that they are all homologous to the corresponding SCAR markers. Received: 8 November 1999 / Accepted: 15 November 1999     

Attentional modulation of temporal contrast sensitivity in human vision

Recent psychophysical studies have shown that attention can alter contrast sensitivities for temporally broadband stimuli such as flashed gratings. The present study examined the effect of attention on the contrast sensitivity for temporally narrowband stimuli with various temporal frequencies. Observers were asked to detect a drifting grating of 0-40 Hz presented gradually in the peripheral visual field with or without a concurrent letter identification task in the fovea. We found that removal of attention by the concurrent task reduced the contrast sensitivity for gratings with low temporal frequencies much more profoundly than for gratings with high temporal frequencies and for flashed gratings. The analysis revealed that the temporal contrast sensitivity function had a more band-pass shape with poor attention. Additional experiments showed that this was also true when the target was presented in various levels of luminance noise. These results suggest that regardless of the presence of external noise, attention extensively modulates visual sensitivity for sustained retinal inputs.     

An antibody to the lutheran glycoprotein (Lu) recognizing the LU4 blood type variant inhibits cell adhesion to laminin α5

Background

The Lutheran blood group glycoprotein (Lu), an Ig superfamily (IgSF) transmembrane receptor, is also known as basal cell adhesion molecule (B-CAM). Lu/B-CAM is a specific receptor for laminin α5, a major component of basement membranes in various tissues. Previous reports have shown that Lu/B-CAM binding to laminin α5 contributes to sickle cell vaso-occlusion. However, as there are no useful tools such as function-blocking antibodies or drugs, it is unclear how epithelial and sickled red blood cells adhere to laminin α5 via Lu/B-CAM.

Methodology/Principal Findings

In this study, we discovered a function-blocking antibody that inhibits Lu binding to laminin α5 using a unique binding assay on tissue sections. To characterize the function-blocking antibody, we identified the site on Lu/B-CAM recognized by this antibody. The extracellular domain of Lu/B-CAM contains five IgSF domains, D1-D2-D3-D4-D5. The antibody epitope was localized to D2, but not to the D3 domain containing the major part of the laminin α5 binding site. Furthermore, mutagenesis studies showed that Arg¹⁷⁵, the LU4 blood group antigenic site, was crucial for forming the epitope and the antibody bound sufficiently close to sterically hinder the interaction with α5. Cell adhesion assay using the antibody also showed that Lu/B-CAM serves as a secondary receptor for the adhesion of carcinoma cells to laminin α5.

Conclusion/Significance

This function-blocking antibody against Lu/B-CAM should be useful for not only investigating cell adhesion to laminin α5 but also for developing drugs to inhibit sickle cell vaso-occlusion.     

Function of the High Concentration Alcohol-producing Factor

By use of the chemically defined synthetic medium, the formation of high concentration of alcohol, reaching 20–21 percent, was accomplished by Saccharomyces sake, at 20°C within 20 days, under a gradual addition of sucrose. Unsaturated fatty acid-containing phospholipid- macromolecule (albumin or methylcellulose) complex was the essential structure for the high concentration alcohol-producing factor. Unsaturated fatty acids, especially linoleic acid, incorporated to the yeast cells grown anaerobically in the statical fermentation test from the koji mold phosphatidylcholine-methylcellulose complex. These data show that the formation of a high concentration of alcohol in sake mash is related to the lipid metabolism of the yeasts.     

Formation of Phage-Induced γ-Polyglutamic Acid Depolymerase in Lysogenic Strain of Bacillus natto

The influence of tea catechins on the absorption of starch or sucrose was investigated in vivo. Tea catechins were administered orally to rats before soluble starch or sucrose administration. Saccharide-dosed rats were killed and the blood and the contents of the intestine were collected at intervals over two hours. Catechins of certain concentrations suppressed the increase of plasma glucose levels, thus concurrently suppressing insulin activity. Increased activity of intestinal α-amylase by starch dosing was inhibited markedly in the catechin-administered rats. Sucrase on the brush border membrane was also inhibited by prior catechin administration. From these results it was assumed that orally administered catechins will inhibit intestinal α-amylase or sucrase, thereby deterring the digestion of certain amounts of starch or sucrose and eventually reducing the plasma glucose levels.