Color change in exercising crabs: evidence for a hormone

Summary Three species of crabs exercised to fatigue showed a blanching and/or reddening of the body and legs. InUca pugilator this effect was due to white and red pigment dispersion in the leucophores and erythrophores, respectively, and a black pigment concentration in the melanophores. The pigment movements were induced by factor(s) present in the blood of exercisingUca; blood (hemolymph) removed from an exercised crab and injected into the isolated leg segment of another individual cause pigment movements similar to those seen in intact fatigued crabs. The blood of exercisedUca also caused similar chromatophore changes in isolated leg segments of the crabSesarma cinereum. The evidence suggests that blood-borne factor(s) related or identical to chromatophorotropins are released during vigorous exercise in crabs. We speculate that the effects of these exercise factor(s) are secondary to possible effects on carbohydrate and lipid metabolism associated with exercise.     

The effects of owl predation on the foraging behavior of heteromyid rodents

Summary Researchers have documented microhabitat partitioning among the heteromyid rodents of the deserts of North America that may result from microhabitat specific predation rates; large/bipedal species predominate in the open/risky microhabitat and small/quadrupedal species predominate in the bush/safer microhabitat. Here, we provide direct experimental evidence on the role of predatory risk in affecting the foraging behavior of three species of heteromyid rodents: Arizona pocket mouse (Perognathus amplus; small/quadrupedal), Bailey's pocket mouse (P. baileyi; large/quadrupedal), and Merriam's kangaroo rat (Dipodomys merriami; large/bipedal). Both kangaroo rats and pocket mice are behaviorally flexible and able to adjust their foraging behavior to nightly changes in predatory risk. Under low levels of perceived predatory risk the kangaroo rat foraged relatively more in the open microhabitat than the two pocket mouse species. In response to the presence of barn owls, however, all three species shifted their habitat use towards the bush microhabitat. In response to direct measures of predatory risk, i.e. the actual presence of owls, all three species reduced foraging and left resource patches at higher giving up densities of seeds. In response to indirect indicators of predatory risk, i.e. illumination, there was a tendency for all three species to reduce foraging. The differences in morphology between pocket mice and kangaroo rats do appear to influence their behavioral responses to predatory risk.     

Colonization of potato fields in eastern North Carolina by Colorado potato beetle

Rotated and non-rotated commercial potato fields were sampled intensively to follow Colorado potato beetle,Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), colonization and subsequent oviposition patterns in the spring of 1990 and 1991. Maximum densities of colonizing adults ranged from 0 to 14,891/ha and maximum egg mass densities ranged from 0 to 48,451/ha. Crop rotation generally resulted in lower potato beetle populations. Regardless of crop rotation management practices, colonization of fields planted in potatoes began at field edges and progressed inward in all fields for both years. Management of potato beetles is discussed in light of these findings.     

Evaluation of the Auxotab Enteric 1 System for Identification of Enterobacteriaceae

An evaluation of the accuracy and convenience of the Auxotab Enteric 1 System for identification of Enterobacteriaceae was performed with 160 bacteria. Identification at the species level was correct in 134 (83.8%) instances and at the generic level in 144 (90%) instances. Sixty strains failed to achieve the minimal concentration of organisms required to complete the identification process within 7 hr. The system was judged to be laborious and to present a potential hazard to those working with it.     

Therapeutic drug monitoring of antifungal agents

Despite a dramatic increase in the number of commercially available agents to treat invasive fungal infections, they remain a common and devastating problem in a variety of patients. The impact of these infections has furthered interest in optimizing antifungal therapy. Therapeutic drug monitoring has emerged as a potentially important area allowing the efficacy of select antifungals to be optimized. This article reviews emerging data examining the utility and rationale for voriconazole and posaconazole therapeutic drug monitoring.     

Development of a sequential injection analysis system for monitoring of trehalose concentrations

A sequential injection analysis (SIA) system was developed to on-line monitor the concentrations of trehalose in biological processes. The system is based on the enzymatic reaction of trehalose to glucose in an immobilized trehalase reactor and the subsequent reaction of glucose in the presence of glucose oxidase. The peroxide produced is detected using horseradish peroxidase with a redox indicator (ABTS, 2,2′-azino-di(3-ethylbezthiazoli-sulfonic acid-6)) and a spectrophotometer set at 435 nm. The SIA was fully automated using software written in the LabVIEW^TM development environment. A number of system variablese.g. flow rate of the carrier buffer solution and volume ratio of sample to reagents, were evaluated to increase the sensitivity and performance of the SIA system. The performance of the trehalose-SIA system was linear under partially optimized operating conditions in the concentration range of 0.3 to 2.0 g/L (R²=0.999) with a sample frequency of 6 1/h. The SIA system was successfully employed to on-line monitor the concentrations of trehalose in a continuously stirred tank reactor. The on-line monitored data were in good agreement with the off-line data measured by a HPLC with a refractive index detector (n=14, R²=0.9865).