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     

Cooperation or cooptation: A southwest French wine cooperative

Conclusion Cooperatives, with respect to the history of wine production in the southwest of France, require that they be graced as the outcome of the transformation from the era of captitalist markets to the era where the capitalist mode of production became dominant—a transformation marked by the creation of a market in labor as predominant among winegrowers. As Marx showed through his many works on the development of capitalism, the translation of market exchanges into a quantifiable economic entity only serves to mask the social relations on which it is based. It was therefore my intent in the first part of this essay to highlight, if only suggestively, the process that led to expanded commercialization of wine in the Aquitaine and the deployment of a specific system of labor. Although wine proprietors and growers were divided by social class early on, the market in labor matured slowly, especially in the sector of the production of table wines. The market in labor among winegrowers followed from the appearance of the grand crus in the eighteenth and nineteenth centuries and from the social consequences that ensued from the phylloxera in the late nineteenth and early twentieth centuries. The grand crus ushered in new specialized labor while the phylloxera intensified this process by turning wealthy merchants and large proprietors towards the volume production of table wines, thus usurping the last vestige of the small independent producer.Markets were not left to follow their own telos as the state played a central mediative role in creating legislation that both encouraged and pressured small independent producers to collectivize their resources in vinification cooperatives. This was not a conspiracy of the state legislature against the excesses of production on the part of the small producers. Wine cooperative legislature was an attempt on the part of the state legislature to resolve the periodic crises in viticulture caused by overproduction and to implement a long overdo agricultural policy The problems faced by the Sigouls Cooperative today are largely a product of the past history of wine production in the southwest of France. Currently, seventy-five percent of the Cooperative's plantation is in white wines. The high plantation in white wines reflects northern European preferences that are traceable to the sixteenth century and earlier. More recently, in France and elsewhere, there has been a gradual shift in consumer preferences from white to red wines. Consumer preferences in part can be attributed to the vicissitudes of taste. However, one must not overlook concerted efforts through advertising to shape consumer taste. Recently, the best known example is the enthusiasm for Beaujolais Nouveau cultivated through clever advertising in major urban centers such as Paris and New York. Since wine cooperatives have not had sufficient capital to invest in advertising and promotion to establish trends, they have had to settle for keeping pace with new developments. Although Sigouls has exceeded its neighboring cooperative, Monbazillac, in keeping pace with the latest trend, it must be recognized that it requires at least five years for a red wine stock such as merlot to mature after plantation.Although wine cooperatives can be seen as assimilatory institution in that they have served the absorption of small independent producers of wine into the capitalist mode of production, it should be recognized equally that wine cooperatives have been the only means available to small producers for continuing the cultivation of their vineyards given the constraints of capitalist social relations. With this in mind, one must avoid the conclusion that wine cooperatives are simply an instrument of the capitalist mode of production, French legislature, the ruling class and nothing else. Although the political motives that led some of the Sigouls Cooperative's early members to pool their vinification and marketing resources have given way to pragmatics, or as my informants related la rentabilité (profitability), the Cooperative has preserved, albeit in a transformed medium, an ageold meaningful livelihood, a sense of local pride in the production of wine, and some sense of independence from the fate of wage labor.Robert Ulin is Professor of Sociology & Anthropology, Allegheny College, Meadville, Pa.

---

     

Inhibitors of Trichoderma reesei β-glucosidase activity derived from autohydrolysis-exploded Eucalyptus regnans

Summary Enzymic saccharification of Eucalyptus regnans pulps pretreated by autohydrolysis-steam explosion resulted in low cellulose conversions into glucose when using trichodermal cellulase preparations. The reduced levels of glucose were attributable to the production of compounds during enzymic hydrolysis which were inhibitory to -d-glucosidase of Trichoderma reesei C-30 and in Meicelase, but not to the cellulases. Aspergillus niger -glucosidase was not inhibited, nor were -d-xylosidase(s) and 1,4--d-xylanase(s). The inhibitory compound(s) could be extracted from the enzymic hydrolyzates with ethyl acetate. The ethyl acetate extractives inhibited -glucosidase in a competitive manner, and inhibitory action was not affected by pH. Addition of the inhibitory compound(s) to trichodermal cellulase digests of cellulose resulted in reduced glucose yields compared to a control. The inhibitory effects could be overcome when cellulase digests were supplemented with A. niger -glucosidase resulting in higher cellulose-to-glucose conversions. The inhibitory compound(s) were localized mainly in the heartwood of E. regnans. An inhibitor compound of this type has not hitherto been reported. The presence of inhibitory compound(s) in the autohydrolysis liquor fraction is also reported.     

The relationship between RNA catalytic processes

Proposals that an RNA-based genetic system preceeded DNA, stem from the ability of RNA to store genetic information and to promote simple catalysis. However, to be a valid basis for the RNA world, RNA catalysis must demonstrate or be related to intrinsic chemical properties which could have existed in primordial times. We analyze this question by first classifying RNA catalysis and related processes according to their mechanism. We define: (A) thedisjunct nucleophile class which leads to 5-phosphates. These include Group I and II intron splicing, nuclear mRNA splicing and RNase P reactions. Although Group I introns and its excision mechanism is likely to have existed in primordial times, present-day examples have arisen independently in different phyla much more recently. Comparative methodology indicates that RNase P catalysis originated before the divergence of the major kingdoms. In addition, alldisjunct nucleophile reactions can be interrelated by a proposed mechanism involving a distant 2-OH nucleophile. (B) theconjunct nucleophile class leading to 3-phosphates. This class is composed of self-cleaving RNAs found in plant viruses and the newt. We propose that tRNA splicing is related to this mechanism rather than the previous one. The presence of introns in tRNA genes of eukaryotes and archaebacteria supports the idea that tRNA splicing predates the divergence of these cell types.     

Characterization of the calcium sensitivity of differentiation in SCC-13 human squamous carcinoma cells

Summary The sensitivity to calcium of the human squamous carcinoma cell line, SCC-13, was demonstrated and characterized. Cultures grown to confluence in the presence of 0.2 to 2 mM calcium had approximately 10-fold higher levels of particulate transglutaminase activity and envelope competence than those grown in low calcium (0.025 to 0.05 mM) medium. Raising the calcium from 0.025 to 1.8 mM induced expression of this enzyme and of competence over the course of a week. Conversely, for cultures grown to confluence in 1.8 mM calcium, subsequent reduction of calcium to 0.025 mM resulted in a substantial decline in transglutaminase over a similar time period. Immunoprecipitable transglutaminase was clearly identifiable in cultures grown in 1.8 mM calcium-containing medium but not in those grown in low calcium medium or in the presence of retinoic acid, suggestive of regulation at the level of mRNA accumulation or translation rather than posttranslational modification. This research was supported by Public Health Service grant AR 27130 from the National Institute of Arthritis, Musculoskeletal and Skin Diseases, Bethesda, MD, and National Research Service postdoctoral fellowship ES 05336 from the National Institute of Environmental Health Sciences, Research Triangle Park, NC.     

Effect of elastin peptides on cell proliferation]

Elastin peptides were shown to act on a cell membrane receptor coupled to a G-protein, phospholipase C, and its activation increases IP3 and DAG and opens receptor-dependent Ca(++)-channels. As some growth factors also produce similar modifications in intracellular Ca++, we wanted to explore the effect of elastin peptides on cell proliferation using 3H-thymidine incorporation and cell counting. The concentration of peptides needed for the stimulation of cell proliferation varied between large limits (1 microgram/ml to 10 mg/ml) according to the origin of the cells and the nature of the peptides. The proliferation of CCL 39 chinese hamster lung fibroblasts was enhanced in a dose-dependent fashion in the concentration range of 3 to 10 mg/ml. The proliferation of human skin fibroblasts was enhanced in the concentration range of 0.5 to 3.3 mg/ml and inhibited at higher concentrations. This effect depended little on the average molecular weight (MW) of the peptide preparation, high MW peptides (average 75 kDa) and lower MW peptides (average MW 10 kDa) were both efficient approximately to the same extent. It appears probable that only a small fraction of these peptides possesses this growth promoting property; other sequences might have the opposite effect. The conformation of the peptides may also play an important role. Human sera contain circulating elastin peptides in the concentration range of 1.0 to 10 micrograms/ml, increasing in obstructive arteriopathies and in some hyperlipidemias. It appears therefore that the above findings may have physiopathological significance in the regulation of cell proliferation in normal and pathological conditions.