The Effects of Light and Gravity on the Horizontal Curvature of Roots of Gravitropic and Agravitropic Arabidopsis thaliana L

In an attempt to study and distinguish the effects of light and gravity on the direction of horizontal root growth, wild-type and an agravitropic mutant of Arabidopsis thaliana L., aux-1 were examined. The mutant aux-1 seedling roots are agravitropic but do respond to light, thus allowing the effects of light and gravity on roots to be studied separately. It is shown that in addition to the recognized negative phototropic and positive gravitropic responses of the root, there are also horizontal curvatures (clockwise or counterclockwise) induced by both unilateral light and gravity. The effects of light and gravity in inducing the horizontal curvature of roots are synergistic when both act in the same direction, and are antagonistic when acting in opposite directions. The results indicate that light and gravity interact to determine the direction and magnitude of the horizontal curvature of roots.     

Alcohol and ischaemic heart disease in middle aged British men.

The relation between alcohol intake and ischaemic heart disease was examined in a large scale prospective study of middle aged men drawn from general practices in 24 British towns. After an average follow up of 6.2 years 335 of the 7729 men had experienced a myocardial infarction (fatal or non-fatal) or sudden cardiac death. No significant relation was found between reported alcohol intake and the incidence of such events. Though the group of light daily drinkers had the lowest incidence of ischaemic heart disease events, it also contained the lowest proportion of current smokers, had the lowest mean blood pressure, had the lowest mean body mass index, and contained the lowest proportion of manual workers. These characteristics are more likely to account for the apparent protective effect of alcohol against ischaemic heart disease than a direct effect of alcohol. Compared with the effects of established risk factors alcohol seems to be quite unimportant in the development of ischaemic heart disease.     

A major 62-kD intranuclear matrix polypeptide is a component of metaphase chromosomes

We have isolated and partially characterized a major intranuclear matrix polypeptide from rat liver. This polypeptide, which is reversibly stabilized into the intranuclear matrix under conditions which promote intermolecular disulfide bond formation, has a Mr of 62,000 and pI of 6.8-7.2 as determined by two-dimensional IEF/SDS-PAGE. A chicken polyclonal antiserum was raised against the polypeptide purified from two-dimensional polyacrylamide gels. Affinity-purified anti-62-kD IgG was prepared and used to immunolocalize this polypeptide in rat liver tissue hepatocytes. In interphase hepatocytes the 62-kD antigen is localized in small, discrete patches within the nucleus consistent with the distribution of chromatin. The staining is most prominent at the nuclear periphery and somewhat less dense in the nuclear interior. Nucleoli and cytoplasm are devoid of staining. During mitosis the 62-kD antigen localizes to the condensed chromosomes with no apparent staining of cytoplasmic areas. The chromosomal staining during mitosis is uniform with no suggestion of the patching seen in interphase nuclei. Fractionation and immunoblotting studies using rat hepatoma tissue culture cells blocked in metaphase with colcemid confirm the chromosomal localization of this 62-kD intranuclear protein during mitosis. The 62-kD polypeptide fractionates completely with metaphase chromosome scaffolds generated by sequential treatment of isolated chromosomes with DNAse I and 1.6 M NaCl, suggesting that this major 62-kD intranuclear protein may be involved in maintaining metaphase chromosomal architecture.     

Monoclonal antibodies to bovine UDP-galactosyltransferase. Characterization, cross-reactivity, and utilization as structural probes

A series of mouse monoclonal antibodies has been developed against a soluble form of bovine UDP-galactose:N-acetylglucosamine galactosyltransferase purified to apparent chemical homogeneity by a combination of affinity and immunoadsorption chromatography. The purified enzyme consists of two molecular mass variants of 42 and 48 kDa. Individual monoclonal antibodies were selected for by their ability to recognize immobilized affinity-purified galactosyltransferase and were not reactive against bovine alpha-lactalbumin and bovine immunoglobulins. Based on competitive binding assays and Western blot analysis with either galactosyltransferase or lactose synthetase (covalently cross-linked alpha-lactalbumin galactosyltransferase), these monoclonal antibodies can be subdivided into four groups. Group A (3 clones) recognize an epitope at or near the alpha-lactalbumin binding site. In addition, this group is cross-reactive with soluble galactosyltransferase from human milk and pleural effusion. Group B (6 clones) and D (1 clone) appear to recognize two different epitopes on the 6-kDa fragment which is released when the 48-kDa galactosyltransferase polypeptide is converted to the 42-kDa form, apparently by proteolysis. Groups A and C (1 clone) recognize epitopes found on both the 48- and 42-kDa polypeptide. Interestingly, immunofluorescence studies indicate that only two monoclonal antibody groups (C and D) are able to decorate membrane-bound galactosyltransferase (Golgi-associated) in formalin-fixed, methanol-, or detergent-permeabilized cells. Thus, these groups of monoclonal antibodies appear to identify four separate structural/functional domains on soluble galactosyltransferase, two of which are not readily accessible for binding in situ.     

Free radical damage to cultured porcine aortic endothelial cells and lung fibroblasts: Modulation by culture conditions

Summary Culture conditions modulating cell damage from xanthine plus xanthine oxidase-derived partially reduced oxygen species were studied. Porcine thoracic aorta endothelial cells and porcine lung fibroblasts were maintained in monolayer culture. Cells were prelabeled with⁵¹Cr before xanthine plus xanthine oxidase exposure. Endothelial cells showed 30 to 100% more lysis than fibroblasts and thus seemed more sensitive to this oxidant stress. The effect of cell culture age, as indicated by population doubling level (PDL), was examined. Response of low PDL endothelial cells and fibroblasts subjected to oxidant stress was compared with the response of PDL 15 cells. Both low PDL endothelial cells and fibroblasts responded differently to the lytic effect of xanthine oxidase-derived free radicals than did higher PDL cells. Specific activities of the antioxidant enzymes catalase, managanese superoxide dismutase, copper-zinc superoxide dismutase, glutathione peroxidase, and glucose-6-phosphate dehydrogenase were measured in both low and high PDL fibroblasts and endothelial cells. Antioxidant enzyme specific activities could only partially explain the differences in response to oxidant stress between fibroblasts and endothelial cells and between low and high PDL cells. Cell culture medium composition modulated the rate of production, and relative proportions of xanthine plus xanthine oxidase-derived partially reduced species of oxygen, i.e. superoxide, hydrogen peroxide, and hydroxyl radical. Serum content of medium was important in modulating free radical generation; superoxide production rates decreased 32%, H₂O₂ became undetectable, and hydroxyl radical generation decreased 54% in the presence of 10% serum. The medium protein and iron content also modulated free radical generation. The data suggest that cell culture media constituents, cell type, and cell culture age greatly affect in vitro response of cells subjected to oxidant stress. Research supported by American Lung Association Fellowship Training Grant and Research Training Grant, the R. J. Reynolds Corporation, and National Institutes of Health Grants HL29784 and 1 HL 23805.     

Concentrations of high density lipoprotein cholesterol,triglycerides, and total cholesterol in ischaemic heart disease.

OBJECTIVE--To assess the roles of serum concentrations of total cholesterol, high density lipoprotein cholesterol, and triglycerides in predicting major ischaemic heart disease. DESIGN--Men recruited for the British regional heart study followed up for a mean of 7.5 years. SETTING--General practices in 24 British towns. PATIENTS--7735 Middle aged men. END POINT--Predictive value of serum concentrations of lipids. MEASUREMENTS AND MAIN RESULTS--At initial screening serum concentrations of total cholesterol, high density lipoprotein cholesterol, and triglycerides were determined from non-fasting blood samples. Altogether 443 major ischaemic heart disease events (fatal and non-fatal) occurred during the study. Men in the highest fifth of the distribution of total cholesterol concentration (greater than or equal to 7.2 mmol/l) had 3.5 times the risk of ischaemic heart disease than did men in the lowest fifth (less than 5.5 mmol/l) after adjustment for high density lipoprotein cholesterol concentration and other risk factors. Men in the lowest fifth of high density lipoprotein cholesterol concentration (less than 0.93 mmol/l) had 2.0 times the risk of men in the highest fifth (greater than or equal to 1.33 mmol/l) after adjustment for total cholesterol concentration and other risk factors. Men in the highest fifth of triglyceride concentration (greater than or equal to 2.8 mmol/l) had only 1.3 times the risk of those in the lowest fifth (less than 1.08 mmol/l) after adjustment for total cholesterol concentration and other risk factors; additional adjustment for high density lipoprotein cholesterol concentration made the association with ischaemic heart disease disappear. CONCLUSIONS--Serum concentration of total cholesterol is the most important single blood lipid risk factor for ischaemic heart disease in men. High density lipoprotein cholesterol concentration is less important, and triglyceride concentrations do not have predictive importance once other risk factors have been taken into account.     

Simultaneous immunoelectron microscopic visualization of protein B23 and C23 distribution in the HeLa cell nucleolus

The intranucleolar distribution of phosphoproteins B23 and C23 was visualized simultaneously by post-embedding immunoelectron microscopy in HeLa cell nucleoli, using specific antibodies. The data show that proteins B23 and C23 co-localize to the same nucleolar compartments, i.e., the dense fibrillar component and the granular component. Neither of the two antibodies is significantly associated with the fibrillar centers in these cells, although the fibrillar centers appear positive after silver staining. These findings suggest that other unidentified components must be responsible for the silver staining observed in the fibrillar centers of interphase nucleoli. The results are discussed in the light of previously reported data obtained by preembedding immunolabeling techniques and by silver staining, which both suggested a localization of protein C23 inside the fibrillar centers.