The influence of host plant variation and intraspecific competition on oviposition preference and offspring performance in the host races of Eurosta solidaginis

1. A series of experiments was conducted to measure the impact of plant genotype, plant growth rate, and intraspecific competition on the oviposition preference and offspring performance of the host races of Eurosta solidaginis (Diptera: Tephritidae), a fly that forms galls on Solidago altissima and Solidago gigantea (Asteraceae). Previous research has shown that both host races prefer to oviposit on their own host plant where survival is much higher than on the alternate host plant. In this study, neither host race showed any relationship between oviposition preference and offspring performance in choosing among plants of their natal host species. 2. The larval survival of both host races differed among plant genotypes when each host race oviposited on its natal host species. In one experiment, altissima host race females showed a preference among plant genotypes that was not correlated with offspring performance on those genotypes. In all other experiments, neither the altissima nor gigantea host race demonstrated a preference for specific host plant genotypes. 3. Eurosta solidaginis had a preference for ovipositing on rapidly growing ramets in all experiments, however larval survival was not correlated with ramet growth rate at the time of oviposition. 4. Eurosta solidaginis suffered high mortality from intraspecific competition in the early larval stage. There was little evidence, however, that females avoided ovipositing on ramets that had been attacked previously. This led to an aggregated distribution of eggs among ramets and strong intraspecific competition. 5. There was no interaction among plant genotype, plant growth rate, or intraspecific competition in determining oviposition preference or offspring performance.     

Nucleoside and nucleotide transport through a model liquid membrane. Periodic-catastrophic transport of a novel amantadine phosphoramidate conjugate of 5'-AMP

Adenosine 5'-phosphor(adamantyl)amidate (5), an analog derived by linking the antiviral drug amantadine to 5'-AMP is transported through a model membrane system in a discontinuous periodic-catastrophic fashion. The system was composed of a glass cell containing two aqueous buffer phases separated by a chloroform layer. A more lipophilic, but structurally related derivative, adenosine 5'-phosphor(n-decyl)amidate (3) showed linear transport in the same system. Less lipophilic substances, including 5'-AMP and adenosine 5'-phosphor(morpholidyl)amidate (2), did not show transport. It is hypothesized that the periodic-catastrophic transport is a result of the collective activity of amidate 5 at the interface between the first aqueous interface and the chloroform layer. The time between catastrophic events is thought to be a reflection of the time necessary for molecular organization at the interface. The phenomenon is a new example of molecular organization in a system far from equilibrium leading to a repetitive dynamic process.     

Temporal variation in herbivore host-plant preference and performance: constraints on host-plant adaptation

Temporal variation in the acceptability or suitability of plant genotypes to an herbivore has seldom been considered as a possible constraint limiting the adaptation of herbivores to particular plant genotypes, or the occurrence of a positive correlation between host-plant preference and offspring performance. In this study, we used data spanning 12 yr from the same 20 clones of goldenrod ( Solidago altissima ) to examine the temporal variation in oviposition preference and offspring performance of a stem-galling fly, Eurosta solidaginis . We found that the stem galler's preference for, or performance on, the different clones was uncorrelated between years of this study. Furthermore, we found that the relative rankings of clones changed by an average of 31% between successive years. We suggest that these consistently high year-to-year fluctuations in preference and performance by E. solidaginis are likely due to environmental factors (e.g., water and nutrient levels, or abundance of interspecific herbivores) that fluctuate over time and are known to differentially affect the acceptability and suitability of clones to herbivores; i.e., genotype×environment interactions. These results are significant because temporal fluctuations in host-plant preference and performance are likely to favor a more generalized diet by herbivorous insects.     

Demonstration of sequence variations in the promoter region of the human cystatin C gene.

Four point mutations in the promoter region of the human cystatin C gene have been detected by direct sequencing of polymerase chain reaction (PCR) amplified DNA. The four base changes are all localized within a short segment of 85 base pairs. Three cystatin C gene alleles could be defined with respect to these promoter mutations; one with the sequence previously published, one carrying three of the mutations and one with all four base substitutions. Two of the observed mutations are involved in a novel Sst II polymorphism and another generates a new Dde I restriction site. A PCR-based assay for analysis of these Sst II and Dde I sites was designed and used to demonstrate Mendelian inheritance of the polymorphisms as well as to determine the frequencies of the cystatin C gene alleles in the population.