Lack of Dosage Compensation for an Autosomal Gene Relocated to the X Chromosome in DROSOPHILA MELANOGASTER

Aldehyde oxidase activity has been measured in flies with the structural gene for this enzyme translocated to the X chromosome. These measurements are presented as experimental evidence that, in Drosophila melanogaster, an autosomal gene relocated to the X chromosome is not dosage compensated.     

A Comparison of Sampling Techniques for Quantifying Abundance of the Florida Apple Snail (Pomacea Paludosa Say)

Despite the long recognized importance of apple snails (Pomaceapaludosa Say) in Florida wetland food webs, surprisingly littleis known about their life history and ecology. The paucity ofinformation is due, in part, to the lack of a validated samplingtechnique. In this study, we compared the effectiveness of adip net, bar seine, and suction dredge in extracting apple snailsfrom 1-m² throw traps. We also evaluated the reliability ofegg cluster counts as an index of snail abundance. The bar seine was eliminated as a suitable extraction methodbased on poor performance in densely vegetated habitats. Thesuction dredge appeared slightly less sensitive than the dipnet to habitat differences with regards to both marked snailrecovery and higher yield of free-ranging (unmarked, not previouslyextracted) snails. Our results indicate that the probabilityof recovering snails from throw traps can be considerably lessthan 1.0, and that recovery probabilities vary among sites andhabitats. Therefore, without reliable estimates for the fraction ofanimals recovered, density estimates, especially comparisonsamong sites and habitats, are not reliable. We found no relationship between egg cluster counts and estimatesof snail density. The high degree of temporal and spatial variabilityin egg production precludes the use of egg clusters as a reliableindex of apple snail abundance. (Received 15 April 1998; accepted 30 June 1998)     

The North Inlet marsh — estuarine ecosystem: A conceptual approach

The North Inlet marsh — estuarine ecosystem (located at South Carolina, USA) is described via three sub-models: intertidal, benthic-subtidal and water column. The principal storage compartments and fluxes of energy are defined for each submodel. A detailed example of the intertidal oyster subsystem of the intertidal submodel is described. The biological components of the intertidal oyster subsystem of the intertidal submodel is described. The biological components of the oyster community are shown to be stable and a linear systems model of the oyster community is developed. A 1% sensitivity analysis of the intertidal oyster model affords some order in which aspects of the oyster community should be studied.