Atomic force microscopy examination of the topography of a hydrated bacterial biofilm on a copper surface

A bacterium, designated CCI#8, that was isolated from a corroded copper coupon colonized both polished and unpolished copper surfaces under batch culture conditions. Atomic Force Microscopy (AFM) images revealed that the biofilm was heterogeneous in nature, both in depth and in cell distribution. Bacterial cells were shown to be associated with pits on the surface of the unpolished copper coupons. These observations support previous studies that CCI#8 is associated with the pitting corrosion of copper.     

Gibberellic Acid Sensitivity Determines the Length of the Extension Zone in Wheat Leaves

To test the hypothesis that gibberellic acid (GA) sensitivityaffects the length of the extension zone (LEZ) of leaf No. 1of wheat seedlings, we performed a gene dosage experiment usingRht dwarfing genes that condition GA insensitivity. We utilizednearly isogenic lines, at Rht-dosage levels of 0, 2 and 4 alleles.Anatomical markers (distances between successive stomates) wereused to infer the distribution of growth along the axis of theleaf. Interstomatal distance (ISD) and LEZ were inverse linearfunctions of Rht-dosage. The number of stomates matured perhour was independent of Rht-dosage. The relationship betweenISD and distance along the axis within the extension zone (EZ)was indistinguishable from linear. Rht-dosage did not affectthe slope of the regression of ISD against distance along theEZ. A-REST (AR; ancymidol, a potent GA synthesis inhibitor)reduced LEZ. Wild type was more sensitive to AR than doubledwarf. AR affected growth of leaf No. 1 more than length ofthe coleoptile, regardless of Rht-dosage. AR-dosage affectedcell division, whereas Rht-dosage did not. Extension zone, elongation, gibberellic acid, Rht, wheat, Triticum aesiivum L.     

Cold shock and heat shock: a comparison of the protection generated by brief pretreatment at less severe temperatures

Abstract Brief exposure to low (0^oC) or high (40^oC) temperature elicits a protective response that prevents injury when the flesh fly, Sarcophaga crassipalpis Macquart, is subjected to more severe cold (-10^oC) or heat (45^oC). Both the low and high temperature responses were found in all developmental stages of the fly, but were most pronounced in the pupal and pharate adult stages. The protective responses generated by brief exposure to 0 or 40^oC appear similar in that both result in a rapid acquisition of cold or heat tolerance and a loss of protection after the flies are returned to 25^oC. The protection generated by chilling is obvious within 10 min of exposure to 0^oC while a 30 min exposure to 40^oC is required to induce the high temperature protection. High temperature protects against cold shock injury within a narrow range (around 36^oC) but we have no evidence that low temperature can protect against heat injury. We previously demonstrated that the rapid increase in cold tolerance correlates with concomitant increases in glycerol concentration, but in this study we found no significant elevation in glycerol in heat-shocked flies. Thus the physiological and biochemical bases for the rapid responses to cold and heat appear to be different.     

Insulin and fructose regulate malic enzyme activity by different processes

A comparison of the regulatory processes controlling hepatic malic enzyme activity following treatment of diabetic rats with insulin or with a high fructose diet demonstrated several important differences. Insulin treatment caused a 50-fold increase in activity, due to a 12-fold increase in enzyme quantity and a 4-fold increase in specific activity(units/nmol). Dietary fructose caused a 3-fold increase in enzyme activity, due to a 3-fold increase in enzyme quantity, with no change in the specific activity of the enzyme. Thus, while fructose initiated a minor increase in malic enzyme activity, insulin was more effective, causing a substantially greater increase in enzyme activity and activating a hormone specific alteration in the catalytic activity of each enzyme molecule.     

Regulation of hepatic malic enzyme by perfluorodecanoic acid

Perfluorodecanoic acid (PFDA) administration to adult male rats increased both the activity of hepatic malic enzyme and liver weight in a dose-dependent manner. Hepatomegaly and augmented activity of malic enzyme in liver were apparent within one day following PFDA administration and reached a plateau by three days posttreatment. Malic enzyme quantity per liver in PFDA-treated rats was elevated within one day following dosing and increased continually throughout five days posttreatment. Administration of PFDA to rats in the fed state also led to an increase in the specific activity of hepatic malic enzyme that peaked at three days following dosing. When compared to the fed condition, rats fasted for 48 hours had a decrease in both relative liver weight and the quantity of supernatant protein per liver. The total activity (U/liver) and specific activity of malic enzyme in the liver were also reduced in the fasted state. During the 24 hours after treatment in rats fasted for 48 hours, the body weight as well as the absolute and relative liver weight of animals receiving vehicle declined continuously in the absence of feed. Following the administration of PFDA to fasted rats, body weight was maintained until eight hours posttreatment but then declined at a rate similar to that found with the vehicle-treated group. Absolute and relative liver weight in PFDA-treated rats were increased significantly at eight hours posttreatment when compared to those receiving vehicle, and this increment was maintained throughout the rest of the 24 hours following dosing. While the activity and enzyme content of hepatic malic enzyme decreased in the vehicle-treated group, administration of PFDA to rats fasted for 48 hours prevented their decline. The specific activity of hepatic malic enzyme in 48 hours fasted rats receiving PFDA was also elevated significantly at 16 hours posttreatment. Thus, the administration of PFDA to the adult male rat in both the fed and fasted nutritional states was found to regulate hepatic malic enzyme by not only increasing enzyme quantity but also by augmenting the specific activity, (ie, catalytic state) of the enzyme.     

ESTIMATES OF CARRY-OVER EFFECTS IN TWO-PRODUCT HOME USAGE CONSUMER TESTS

In-house use consumer test data from four studies dealing with three pairs of household products and a pair of antiperspirant products were examined for significant carry-over (product usage order) effects, which would confound the analysis of treatment (product) effects. In each study, two products were compared using a two-period crossover design. One hundred twenty panelists participated in each study. A forced choice preference scale or a 9-point hedonic scale was used to obtain responses from various sensory attributes. In all studies, the estimates of carry-over effects were not significant at the 5% level. Transformation of hedonic scale data into preference dichotomy also gave estimates of carry-over effects which were not significant at the 5% level, but led to a loss of test sensitivity for detecting treatment differences. The authors recommend that all comparative crossover design studies in sensory evaluation be monitored for carry-over effects and that statistically determined sample size should be used to reduce the possibility of obtaining significant carry-over effects.     

The effect of counterions on melittin aggregation.

Melittin, a surface-active polypeptide from bee venom, has an overall hydrophobic N-terminus, with basic residues clustered at the C-terminus. In aqueous solution melittin exists as a mixture of monomer and tetramer, the monomer adopting a predominantly random-coil configuration, whereas the tetramer is rich in alpha-helix. The tendency of melittin to aggregate is dependent on the counter-anions present in solution, the effect being most marked with phosphate, decreasing in the order HPO4(2-) greater than SO4(2-) greater than ClO4- greater than Cl-.     

Ontogeny of the Behavior of Strombus maculatus (Gastropoda: Strombidae)

The ontogeny of strombid behavior was studied by observing thebehavior of Strombus maculatus veligers collected from the planktonand reared past metamorphosis to adults, and by observing juvenilestrombids collected in the field. Complete adult modal actionpatterns (MAP's) associated with locomotion, feeding, and rightingof overturned shells are performed by S. maculatus juvenilesimmediately after metamorphosis. There are changes in the frequencyof the use of certain MAP's which are associated with variationsin shell shape and size. The unique strombid escape response to molluscivorous gastropods(Conns spp.) is not released until juvenile S. maculatus arethree weeks past metamorphosis and two millimeters in shelllength. At that stage, the complete response is released uponthe first encounter with a predator. Experience with a predatordoes not seem to lower the age or size criteria. During ontogeny there is a trend toward an increasing complexityof behavior which is paralleled by an increasing complexityof neural structure and general morphology. There are majorsteps in the ontogeny of strombid behavior which probably coincidewith neural and morphological stages.