Expression of a C3 plant Rubisco SSU gene in regenerated C4 Flaveria plants

We report the successful transformation, via Agrobacterium tumefaciens infection, and regeneration of two species of the genus Flaveria: F. brownii and F. palmeri. We document the expression of a C₃ plant gene, an abundantly expressed ribulose 1,5-bisphosphate carboxylase/oxygenase small subunit gene isolated from petunia, in these C₄ plants. The organ-specific expression of this petunia gene in Flaveria brownii is qualitatively identical to its endogenous pattern of expression.     

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     

Inheritance and structure of foreign DNA in progenies of transgenic tobacco obtained by direct gene transfer

Summary One of the transformed tobacco plants obtained by direct DNA transformation possessed two marker genes, a chimeric aminoglycoside phosphotransferase and nopaline synthase genes. Selfed progenies of this plant (T3-d) showed stable inheritance of these two genes. The minimum size of foreign DNA integrated into tobacco genome was estimated to be 5.4 kbp. A deleted nopaline synthase gene co-existed with an intact gene. The linkage analysis indicated that two transformants, T1-b and T3-c, possessed foreign DNA inserted in different chromosomes or in different sites of the same chromosome that recombine freely.     

Transformation with SV40 virus prevents retinoic acid inhibition of plasma membrane NADH diferric transferrin reductase in rat liver cells

Retinoic acid inhibits the reduction of diferric transferrin through the transplasma membrane electron transport system on fetal rat liver cells infected with a temperature-sensitive SV40 virus when the cells are in the nontransformed state cultured at 40°C. When the cells are in the transformed state (grown at the permissive 33°C temperature), retinoic acid does not inhibit the diferric transferrin reduction. Inhibition of activity of nontransformed cells is specific for retinoic acid with only slight inhibition by retinol and retinyl acetate at higher concentrations. Isolated rat liver plasma membrane NADH diferric transferrin reductase is also inhibited by retinoic acid. The effect of transformation with SV40 virus to decrease susceptibility to retinoic acid inhibition stands in contrast to much greater adriamycin inhibition of diferric transferrin reduction in the transformed cells than in nontransformed cells.     

The stimulating effect of a cold, dark pretreatment on the etioplast/chloroplast transformation of angiosperms. I. The stimulating effect of cold predarkening on different stages of greening under white light

Schönbohm, E., Stute, U., Thienhaus, P. and Werner, U. 1988. The stimulating effect of a cold, dark pretreatment on the etioplast/chloroplast transformation of angiosperms I. The stimulating effect of cold predarkening on different stages of greening under white light. - Physiol. Plant. 72: 541–546.
The etioplast/chloroplast transformation in angiosperms is controlled by light; most of the processes are mediated by phytochrome. We have shown that in the primary leaves of etiolated seedlings of wheat ( Triticum aestivum L. cv. Kolibri), fire-bean ( Phaseolus multiflorus L. cv. Preisgewinner) and in the cotyledons of etiolated sun flower seedlings ( Helianthus annuus L. cv. macrocarpa) the chlorophyll accumulation in the phase after the end of the lag phase can be greatly stimulated by a cold predarkening period. This effect is not necessarily coupled with a red preirradiation. Furthermore the lag phase can be dramatically shortened by the cold, dark pretreatment, whereas the amount of photoconvertible protochlorophyll(ide) in the darkness remains unaffected by the cold, dark pretreatment. The stimulating effect of a cold, predarkening period on greening is fully reversible by a warm, dark phase that is placed between the cold period and the onset of the continuous white light phase. These findings cannot be generalized: We could demonstrate that in the tropical plant Momordica charantia greening under white light was not affected by different temperature pretreatments during predarkening. The stimulating effect of a cold, predarkening period on greening is assumed to have ecological relevance.     

Cell surface heparan sulfate proteoglycan and the neoplastic phenotype

Cell surface proteoglycans are strategically positioned to regulate interactions between cells and their surrounding environment. Such interactions play key roles in several biological processes, such as cell recognition, adhesion, migration, and growth. These biological functions are in turn necessary for the maintenance of differentiated phenotype and for normal and neoplastic development. There is ample evidence that a special type of proteoglycan bearing heparan sulfate side chains is localized at the cell surface in a variety of epithelial and mesenchymal cells. This molecule exhibits selective patterns of reactivity with various constituents of the extracellular matrix and plasma membrane, and can act as growth modulator or as a receptor. Certainly, during cell division, membrane constituents undergo profound rearrangement, and proteoglycans may be intimately involved in such processes. The present work will focus on recent advances in our understanding of these complex macromolecules and will attempt to elucidate the biosynthesis, the structural diversity, the modes of cell surface association, and the turnover of heparan sulfate proteoglycans in various cell systems. It will then review the multiple proposed roles of this molecule, with particular emphasis on the binding properties and the interactions with various intracellular and extracellular elements. Finally, it will focus on the alterations associated with the neoplastic phenotype and will discuss the possible consequences that heparan sulfate may have on the growth of normal and transformed cells.     

Transforming activities of sodium fluoride in cultured Syrian hamster embryo and BALB/3T3 cells

The transforming activity of sodium fluoride was studied in the SHE and the BALBl3T3 cell culture systems. Initiating and promoting activities were then investigated by means of the orthogonal methodology. Sodium fluoride was found to induce morphological transformation of SHE cells seeded on a feeder layer of X-irradiated cells at high concentrations (75–125 g/ ml). When the cells were seeded in the absence of a feeder-layer, the transformation frequencies increased in a dose-dependent manner with the concentrations of sodium fluoride ranging from 0 to the highly toxic concentration of 200 g/ml. In the BALBl3T3 cell system, sodium fluoride was negative in the standard Kakunaga procedure, while through the experiment designed by table L₈ (2⁷) of the orthogonal method, an initiating-like effect and a weak promoting activity were detected within the concentrations ranging from a 25 g/ ml to a 50 g/ ml concentration which is highly toxic for BALBl3T3 cells. From these results, it is suggested that, besides a genetic mode of action, sodium fluoride could possibly act through a non-genotoxic mechanism.Abbreviations CE cloning efficiency - NaF sodium fluoride - SHE Syrian hamster embryo - TF transformation frequency     

转化细胞及腹水癌细胞对生长调节因子敏感性的研究

 本文~3H-TdR参入细胞DNA为指标研究了EGF等生长调节因子对小鼠腹水癌细胞DNA合成的影响,发现不同癌细胞对EGF等生长因子的敏感性有所差异,考虑到这也许与肿瘤细胞自身特性如恶性度有关。为了进一步探讨恶性度与这一敏感性是否相关,我们观察并比较了C_3H10T1/2CL_8(一种来源于鼠胚的正常成纤维细胞,简称NC_3H_(10)及转化的C_3H_(10)T1/2CL_8(用~3H-TdR转化的上述细胞,简称TC_3H_(10))对EGF等生长因子的敏感性。实验证明,细胞恶性转化后,对EGF的敏感性明显降低,~3H-TdR参入率降至原先的1/4以下。用DBcAMP作用于NC_3H_(10)和TC_3H_(10)均能抑制~3H-TdR参入DNA并可抑制EGF诱导的~3H-TdR参入作用。因此,我们认为,有关物理的致癌因素如放射性同位素,像生物、化学的致癌因素一样,亦能引起其转化细胞对外源性生长调节因子敏感性的改变。