The cytotaxonomy ofEmilia spp. (Asteraceae: Senecioneae) occurring in Brazil

Analysis of several populations in a large part of the distribution area of the genusEmilia in Brazil has revealed only two species: the diploidE. sonchifolia and the tetraploidE. fosbergii. The more widely reportedE. coccinea was not found. They show a karyotype constancy in morphology and chromosome number (2n = 10 and 2n = 20, respectively), C-banding pattern and number of secondary constrictions. Some indications were found thatE. fosbergii may be an allopolyploid and that its ancestors had different genome sizes.     

Sensitivity of the cell cycle to TGFβ1 does not correlate with transformation of a rat liver epithelial cell line

The effects of TGF1 on cell cycle events in a rat liver derived epithelial cell line (BL9) and in two in vitro transformants of this line were studied by flow cytometry. Using either ethidium bromide staining or the incorporation of bromodeoxyuridine to evaluate DNA synthesis it was shown that TGF1 prevented the entry of G0/G1 phase BL9 cells into S phase. TGF1 did not exert its inhibitory effect(s) on DNA synthesis by the modulation of early events in the cell cycle. The tumorigenic transformed BL9 cell lines gave contrasting responses to the effects of TGF1. DNA synthesis in a BL9 cell line derived by transfection with an active N-ras oncogene was unaffected by TFG1 and thus appeared refractory to its growth controlling effects. On the other hand cells from a BL9 cell line derived by in vitro transformation with activated aflatoxin B₁ retained their sensitivity to the effects of TGF1. Thus the loss of the inhibitory effect of TGF1 on DNA synthesis is not obligatory for the malignant transformation of rat liver epithelial cells.Abbreviations TGF1 transforming growth factor 1 - BSA bovine serum albumin - FBS foetal bovine serum - BrdUrd bromodeoxyuridine - PI propidium iodide - PBS phosphate buffered saline     

Purification and characterization of immunoglobulin production stimulating factor derived from human B lymphoblastoid HO-323 cells

An immunoglobulin (Ig) production stimulating factor (IPSF) for hybridomas was found in spent medium of the human B lymphoblastoid cell line, HO-323. The IPSF was purified by serial use of DEAE chromatography, ultrafiltration, gel filtration and HPLC-DEAE chromatography. Purified IPSF was estimated to be a 410 k macro molecule by gel filtration, and contained three types of isomers which were separated from each other by native polyacrylamide gel electrophoresis. All of the isomers were, however, assumed to have the same protein components by SDS polyacrylamide gel electrophoresis.The IPSF was effective for human-human and mouse-mouse hybridomas producing IgM, but not for IgG producers in the experimental condition used here. Human-human hybridoma HF10B4, cultured in IPSF-containing medium, produced 20 times more IgM than in IPSF-free medium under serum-free conditions. The IPSF showed very little proliferation stimulating activity on HF10B4 cells.     

大麦染色体银带的研究

本文以六棱、四棱和二棱大麦为材料,用去壁低渗火焰干燥法制备染色体标本,标本在60℃恒温下经70—80％AgNO_3水溶液处理12—14小时,可在核仁组成区、着丝粒和端粒出现黑色银染区。细胞化学反应说明这些不同区域的银染物质具有相同的性质。银染带型与C带型和N带型迥然不同,3种大麦的银染带型也有差别。试验还证明染色体标本制备技术对银染效果影响极大,只有合适的酶解和火焰干燥处理才能促使着丝粒和端粒显示出银染正反应。     

Restriction endonuclease resistant chromatin in human chromosomes

Summary The recent addition of restriction endonucleases in obtaining selective bands in the human genome has added a new dimension to molecular genetics. However, a considerable discrepancy exists in banding patterns produced by AluI in chromosomes 19 and 20, by MboI in chromosomes 4, 5, 8, 21 and 22 and by RsaI in chromosomes 12, 21 and 22. The principal causes of these differences are highlighted.     

Ultrastructural aspects of the hyphal tip ofSclerotium rolfsii preserved by freeze substitution

Summary The hyphal tip ofSclerotium rolfsii was examined after fixation by freeze substitution. The Spitzenkörper consisted of a dense mass of apical vesicles and microvesicles surrounding a vesicle-free zone. Linear arrangements of microvesicles were occasionally observed within the Spitzenkörper. Abundant microfilaments were seen within the Spitzenkörper region, often in close association with apical vesicles and microvesicles. Microtubules passed through the Spitzenkörper and terminated at the plasmalemma at the extreme hyphal apex. Filasomes were mostly observed within the apical region and were in close proximity to the plasmalemma. Rough ER, mitochondria, microtubules, and vacuoles were abundant in the subapical region and were usually oriented parallel to the long axis of the hypha. Ribosomes were aligned on the outer surfaces of mitochondria. Golgi body equivalents were observed throughout the subapical region and appeared as inflated cisternae of varying shapes and electron opacities. Relationships to other basidiomycetous hyphal tip cells are discussed.Abbreviations AV apical vesicle - C Celsius - diam diameter - f filasome - G Golgi body equivalent - h hour - nm nanometer - M mitochondria - ME membranous elements; min minute - MV microvesicle - MVB multivesicular body - N nucleus - OsO₄ osmium tetroxide - R ribosome - ER endoplasmic reticulum - S Spitzenkörper - Va vacuole - m micrometer     

NCI-H716 cells as a model for endocrine differentiation in colorectal cancer

In colonic neoplasms, endocrine differentiation is encountered not only in carcinoid tumors but also in adenocarcinomas, where endocrine cells may represent a distinct line of differentiation in the tumor. The significance of endocrine differentiation in colorectal cancer is not well established, partly because of the paucity of tumor cell lines which can serve as a model for studying endocrine differentiation. In this report we describe the properties of NCI-H716 cells, a cell line derived from a poorly differentiated adenocarcinoma of the caecum, under various in vitro conditions and as xenografts in athymic mice. Phenotypical properties were immunohistochemically assessed using a panel of differentiation related antibodies, and also by Northern blot analysis and by electron microscopy. Receptors for biogenic amines and peptide hormones were analyzed by ligand binding assay. These studies show that:

Modification of blood group A antigen expression in a pancreatic cancer cell line (PC-1) by inhibitors of N-glycan processing.

Pancreatic adenocarcinomas induced in Syrian hamsters by treatment with N-nitrosobis(2-oxopropyl) amine express blood group A antigen, which is absent in normal pancreatic cells. On membrane glycoproteins purified from tumors, blood group A antigen has been found to be expressed on multiantennary Asn-linked complex glycans. In this study, we investigated the effect of inhibitors of Asn-glycan processing on blood group A antigen bearing glycan structures in a cell line (PC-1) established from a primary induced pancreatic cancer. Expression of blood group A antigen on cells and in membrane preparations was blocked by treatment with 1-deoxymannojirimycin, an inhibitor of mannosidase I, but was retained after treatment with swainsonine, an inhibitor of mannosidase II. However, swainsonine treatment altered the glycan structure associated with blood group A antigen from an endoglycosidase H resistant type to a sensitive type, indicating that the blood group A structure might shift from a complex type to a hybrid type glycan by this treatment. These results demonstrate that Asn-linked glycans carry the major blood group A antigens in PC-1 cells.     

Cytogeographical study of four aneuploids ofCarex oxyandra Kudo in Japan

Chromosome numbers were determined for 342 clones ofCarex oxyandra collected from 35 localities in Hokkaido, Honshu, Shikoku and Kyushu, Japan. Four intraspecific aneuploids, 2n=18, 20, 24 and 26, were found. In meiotic division, only bivalent chromosomes were observed in all clones at metaphases I and II, suggesting that the aneuploids are established gamodemes. In the mitotic metaphase chromosomes, trimodal variation in chromosome length was observed. The 2n=26 clones found on Mt. Hiko had two particularly small chromosomes. The cytodemes with higher number of chromosomes are distributed in more southern areas of Japan.Carex oxyandra, therefore, accompanied with chromosome fragmentations, might spread the geographical distribution to the southern parts. The morphological characters of leaves, spikes, scales, perigynia and nuts were similar among the four cytodemes, except for the small leaves on plants from Yaku Island.     

Chromosome aberrations (CA), sister-chromatid exchanges (SCE) and mitogen-induced blastogenesis in cultured peripheral lymphocytes from 48 control individuals sampled 8 times over 2 years

Confidence in the measurement of positive effects determined by monitoring of environmentally or occupationally exposed individuals can be enhanced by a knowledge of the normal variability in these endpoints in the general population. Confounding effects can be determined and study interpretation improved by correlation of this variability with various lifestyle factors such as sex and age of donor, smoking and drinking habits, viral infections, exposure to diagnostic X-rays, etc.

8 blood samples were taken from each of 24 male and 24 female volunteers over a period of 2 years. Questionnaires pertaining to lifestyle were completed at the time of each sampling. Whole blood was cultured and slides prepared for CA or SCE analysis. Separated mononuclear cells were cultured with a range of phytohaemagglutinin concentrations and the maximum level of mitogen-induced blastogenesis was determined by measurement of [³H]thymidine uptake.

There was a significant effect of both year and season of sampling for all 3 endpoints. No significant effects in any of the 3 endpoints were found with respect to sex or age of donor nor any of the other lifestyle factors, although SCE frequency and mitogen-induced blastogenesis were nearly always higher in females than males. These results point to the need for concurrent sampling of controls with exposed populations.