Cardiovascular hemodynamics with increasing exercise intensities in postmenopausal women.

We sought to determine the cardiovascular responses to increasing exercise intensities in postmenopausal women with different physical activity levels and hormone replacement therapy (HRT) status. Forty-four women (11 sedentary, 19 physically active, 14 master athletes; 24 not on HRT, 20 on HRT) completed treadmill exercise at 40, 60, 80, and 100% of maximal oxygen consumption. Oxygen consumption, heart rate, blood pressure, and cardiac output, determined via acetylene rebreathing, were measured at each exercise intensity. HRT did not affect cardiovascular hemodynamics. Stroke volume (SV) decreased significantly between 40 and 100% of maximal oxygen consumption in all groups, and the decrease did not differ among groups. The greater oxygen consumption of the athletes at each intensity was due to their significantly greater cardiac output, which was the result of a significantly greater SV, compared with both of the less active groups. The athletes had significantly lower total peripheral resistance at each exercise intensity than did the two less active groups. There were no consistent significant hemodynamic differences between the physically active and sedentary women. These results indicate that SV decreases in postmenopausal women as exercise intensity increases to maximum, regardless of their habitual physical activity levels or HRT status.     

The use of clip cages to restrain insects reduces leaf expansion systemically in Rumex obtusifolius

Abstract. 1. Clip cages have been used widely by experimental ecologists to contain insects on plants.
2. Under controlled conditions, the effect of applying clip cages alone and clip cages and the chrysomelid beetle Gastrophysa viridula on systemic leaf expansion of Rumex obtusifolius was investigated. Treatments were applied to the fully expanded fourth leaf and expansion of leaf 8 was measured over a period of 22 days.
3. The application of clip cages reduced the rate at which leaf area increased and led to reductions in final leaf areas.
4. Clip cages have systemic effects on plant development and these effects are sustained even after the clip cage is removed. Investigators should take this into account in designing experiments.     

Analysis of Escherichia coli K12 F factor transfer genes: traQ, trbA, and trbB

The genes that encode the transfer properties of plasmid F, the fertility factor of Escherichia coli K12, are known to be clustered over a large, 33.3-kb segment of F DNA. As the central segment of the transfer region has not previously been well characterized, we constructed a detailed restriction map of the large F EcoRI DNA fragment, fl, and isolated a series of plasmid derivatives that carry various overlapping segments of this F tra operon DNA. We also analyzed the protein products of those clones that carried DNA segments extending over the region between traF and traH. This region was known to include traQ, a gene required for efficient conversion of the direct product of traA to the 7000-Da pilin polypeptide. We identified the traQ product as a polypeptide that migrates as a 12,500-Da protein on sodium dodecyl sulfate-polyacrylamide gels. We also detected the products of two other new genes that we have named trbA and trbB. These polypeptides migrate with apparent molecular weights of 14,200 and 18,400, respectively. Analysis of plasmid deletion derivatives that we constructed in vitro shows that these genes map in the order traF trbA traQ trbB traH. The presence of a plasmid carrying a small 0.43-kb fragment that expressed only the 12,500 traQ product caused the traA product of a co-resident compatible plasmid to be converted to the 7000-Da pilin polypeptide, demonstrating that TraQ is the only tra operon product required for this step of F-pilin biosynthesis.     

Aluminum,Fe, Ca,Mg, K,Mn, Cu,Zn and P in above- and belowground biomass. I.Abies amabilis andTsuga mertensiana

In a mature mixed subalpine stand ofTsuga mertensiana andAbies amabilis, significantly higher Al levels were found in foliage, branch and root tissues ofT. mertensiana.Tsuga mertensiana had significant increases in Al, Ca and Mn levels with increasing foliage age. In current foliage,T. mertensiana had lower levels of Ca, similar levels of Mg and P, and higher levels of Mn thanA. amabilis. Both tree species had Cu and Fe present at higher levels in branch than foliage tissues. Fine roots had the highest concentrations of Al, Fe and Cu but the lowest Ca and Mn concentrations of all tissues analyzed. In the roots of both species, phloem tissues always had significantly higher Al levels than xylem. Fine roots (< 1 and 1–2 mm) ofT. mertensiana had higher Al levels than were found inA. amabilis. Roots greater than 2 mm in diameter exhibited no significant differences in Al levels in phloem or xylem tissue betweenA. amabilis andT. mertensiana. The two species show a clear difference in their ability to accumulate specific elements from the soil.