HISTOLOGY AND INHERITANCE OF THE CLOSED FLOWER IN CARTHAMUS TINCTORIUS (COMPOSITAE)

Three different closed flower types were identified in safflower and were classified as arrowhead, bar, and cage. Histological observations revealed that the closed flower condition is caused by a differentiation of epidermal cells into papillae that become interdigited. The primary difference between the three types is the length of the fused edge along the petal lobe. The papillae are pointed and have thickened walls of cutin. Reduced seed set results from changes in the internal environment during microsporogenesis. The expression of each closed flower type is governed by a single gene; the arrowhead, bar, and cage types have, respectively, the genotypes arar, baba, and coca.     

Dangerous dive cycles and the proverbial ostrich

Data rarely are available to address the level of predation risk faced by diving animals in different parts of the water column. Consequently, most published research on diving behaviour implicitly assumes – like the proverbial ostrich – that 'unseen' predators are functionally unimportant. We argue that failure to consider diving in a predation risk framework may have precluded many insights into the ecology of aquatic foragers that breathe air. Using existing literature and a simple model, we suggest that fear from submerged predators in several systems might be influencing patch residence time, and therefore the duration of other dive cycle components. These analyses, along with an earlier model of predation risk faced by diving animals at the surface, suggest that dive cycle organisation can be modified to increase safety from predators, but only at the cost of reduced energy gain. Theoretical arguments presented here can seed hypotheses on factors contributing to population declines of diving species. For instance, adjustments to the dive cycle that reduce predation risk might be unaffordable if resources are scarce. Thus, if animals are to avoid imminent starvation or substantial loss of reproductive potential, resource declines might indirectly increase predation rates by limiting the extent to which dive cycles can deviate from those that would maximize energy gain. We hope that ideas presented in this paper stimulate other researchers to further develop theory and test predictions on how predation risk might influence diving behaviour and its ecological consequences.     

The nuclear DNA-dependent ribonucleic acid polymerases of the dermatophytic fungus Microsporum gypseum.

The DNA-dependent RNA polymerases of the dermatophytic fungus Microsporum gypseum were partially characterized. Nuclear extracts prepared from vegetative mycelia were fractionated by DEAE-Sephadex chromatography into three enzyme species which resembled in most of their characteristics those of other eukaryotic organisms.     

Volume and composition of hand sweat of white and black men and women in desert walks

Many investigators have sought, but failed to find, ethnic differences in the number and regional distribution of active sweat glands. In this study measurements have been made of sweat secreted on one hand and also on the whole body of Whites and Blacks walking in desert heat. Whites numbered 31 men and 27 women, ages 30 to 88 years; there were 21 Black men and 31 Black women, ages 16 to 61 years. Each walked on three occasions for 1 hour at a rate that required an oxygen consumption of about 40% of aerobic capacity. Ambient temperature ranged from 32 to 44°C in 1979 and 1980; means were 38.4°C in 1979 and 36.7°C in 1980. There was no sweat in the gloves of many Blacks; this was true of only a few Whites. Volume of body sweat increased in both races with rate of walking; volume of hand sweat increased more in Whites than in Blacks. The Mann-Whitney test revealed that volumes of hand sweat were significantly greater for Whites than for Blacks. It was concluded that in desert walks most Whites and few Blacks sweat freely on their hands. In samples of hand sweat, Na⁺, K⁺, and Cl^? were determined. Concentrations of each ion varied widely in both races, and were unrelated to race. Concentrations of Na⁺ and Cl^? generally are somewhat higher in hand sweat than in body sweat; concentrations of K⁺ are much higher. It follows that the values for concentration of Na⁺ and Cl^? reported in Table 3 probably are somewhat higher than would have been found in body sweat, and concentrations of K⁺ are probably much higher.     

Decisions in force field development: an alternative to those described by Roterman et al. (J. Biomol. Struct. Dyn. 7, 421 (1989))

We attempt to give an alternate point of view of the analysis by Roterman et al. (J. Biolmol. Struct. Dyn. 7,415 (1989]. In particular, we argue for the use of flexible geometry and explicit inclusion of solvent effects in analyzing phi, psi maps of peptides.