Adaptation as organism design

The problem of adaptation is to explain the apparent design of organisms. Darwin solved this problem with the theory of natural selection. However, population geneticists, whose responsibility it is to formalize evolutionary theory, have long neglected the link between natural selection and organismal design. Here, I review the major historical developments in theory of organismal adaptation, clarifying what adaptation is and what it is not, and I point out future avenues for research.     

A carbohydrate-rich diet increases social immunity in ants

Increased potential for disease transmission among nest-mates means living in groups has inherent costs. This increased potential is predicted to select for disease resistance mechanisms that are enhanced by cooperative exchanges among group members, a phenomenon known as social immunity. One potential mediator of social immunity is diet nutritional balance because traits underlying immunity can require different nutritional mixtures. Here, we show how dietary protein–carbohydrate balance affects social immunity in ants. When challenged with a parasitic fungus Metarhizium anisopliae, workers reared on a high-carbohydrate diet survived approximately 2.8× longer in worker groups than in solitary conditions, whereas workers reared on an isocaloric, high-protein diet survived only approximately 1.3× longer in worker groups versus solitary conditions. Nutrition had little effect on social grooming, a potential mechanism for social immunity. However, experimentally blocking metapleural glands, which secrete antibiotics, completely eliminated effects of social grouping and nutrition on immunity, suggesting a causal role for secretion exchange. A carbohydrate-rich diet also reduced worker mortality rates when whole colonies were challenged with Metarhizium. These results provide a novel mechanism by which carbohydrate exploitation could contribute to the ecological dominance of ants and other social groups.     

A database of microsatellite genotypes for <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis>

A system for genotyping Saccharomyces cerevisiae is described based on a multiplex of ten microsatellite loci and the MAT locus. A database of genotypes has been developed for 246 yeast strains, including a large set of commercial wine yeasts, as well as 35 sequenced natural isolates currently being sequenced. The latter allow us, for the first time, to make direct comparisons of the relationship between DNA sequence data and microsatellite-based genotypes. The genotyping system provides a rapid and valuable system for strain identification as well as studying population genetics of S. cerevisiae.     

Detection of mRNA degradation intermediates in tissues using the 3'-end poly(A)-tailing polymerase chain reaction method

It has become increasingly clear that mRNA stability is an important determinant of mRNA abundance in virtually all organisms. Although our understanding of prokaryotic lower eukaryotic mRNA stability mechanisms has progressed considerably, little is known about mammalian mRNA stability mechanisms, particularly at the tissue and animal levels. This is due largely to the lack of suitable methods to approach the problem. In this study, we have developed and refined the 3'-end poly(A)-tailing polymerase chain reaction (PCR) method to detect degradation intermediates in vivo. Using an in vitro transcribed RNA as a template, we found that the method could be used to detect a homogeneous pool of RNA down to 0.1 ng. The addition of 10 microg of total RNA from tissues decreased the sensitivity limit to 4 ng. Detection limits of the technique were determined precisely by varying the concentrations of in vitro transcribed RNA in a constant amount of total RNA and varying the concentration of total RNA while maintaining a constant amount of in vitro transcribed RNA. Our overall results showed that the poly(A)-tailing PCR method could be used to detect specific RNA species of approximately 1000 nt in a pool of heterogeneous RNA in the range of 1 in 2500 to 1 in 10,000. To our knowledge, this is the most sensitive method to date for identifying mRNA degradation intermediates. Employing sense strand gene-specific primers in this method, we have discovered the class II and class III P-glycoprotein (Pgp) mRNA degradation intermediates in normal rat tissues. This method should serve as an additional tool to help us understand mRNA decay mechanisms in tissues and at animal levels.     

Acute toxicology to an estuarine teleost of mixtures of cadmium, copper and zinc salts

Effects of mixtures of chloride salts of cadmium, copper and zinc on survival, whole body residues, and histopathology of mummichog, Fundulus heteroclitus (L.), were investigated in synthetic sea water at 20‰ salinity and 20°C. Mixtures of Cu²⁺ and Zn²⁺ as indicated by 96 h bioassay studies produced more deaths than expected on the basis of toxicities of individual components. Concentrations of Cd²⁺ not ordinarily lethal exerted a negative effect on survival of fish intoxicated by salts of copper, zinc, or both.
Atomic absorption determinations of Cd, Cu, and Zn residues in mummichog which survived 96 h exposures to each of these toxicants provided useful indices of total body burdens for these metals. Residues from survivors held in mixtures, especially Cd²⁺ and Zn²⁺ mixtures, did not conform to patterns observed for single elements. Whole body aggregates of Cd, Cu, and Zn from dead mummichogs were of limited worth owing to possible accumulation of these metals from the medium after death.
Renal and lateral line canal lesions were noted in all fish subjected to copper concentrations of 1 mg/1 and higher. Renal lesions observed in fish immersed in mixtures of Cu²⁺ and Cd²⁺ assumed a damage pattern characteristic of Cd²⁺; with mixtures of Cu²⁺ and Zn²⁺, lesion were typical of Cu²⁺-induced damage. Lesions induced in lateral line epithelium by Cu²⁺ were not affected by either Cd²⁺ or Zn²⁺. Epithelia lining the oral cavity were necrotized by the caustic action of high levels of Zn²⁺ (60 mg/1) and of Cu²⁺ (8 mg/1).     

Isolation and Characterization of Twelve Microsatellite Loci for Rockfish (Sebastes)

We describe the first microsatellites for rockfishes in the diverse genus Sebastes. Clones containing microsatellites were isolated from the genomic library of a quillback rockfish, Sebastes maliger. Twelve microsatellites are characterized; six of these are polymorphic in quillback rockfish, and eight are polymorphic in at least one rockfish species on which they were tested. The number of alleles per variable locus ranged from 4 to 15 and averaged 6.8. The expected heterozygosities ranged from 0.38 to 0.79 and averaged 0.60 in these loci. These loci should prove valuable in studies examining species identification, population genetics, hybridization, paternity, kinship, and microsatellite evolution. Received September 8, 1998; accepted November 23, 1998.     

Kinetics of nitrogen and phosphorus release in varying food supplies byDaphnia magna

Rates of nitrogen and phosphorus release from individualDaphnia magna were determined by measuring ammonia and soluble reactive phosphorus in successive 10-min incubations in small (0.05 ml) vessels after the animals were removed from their food. Release rates of both nutrients were generally highest initially and decreased with time after removal. The ratio of nitrogen to phosphorus released increased with time after animals were removed from an artificial detritus/bacterial food; ratios were lower and changed with time less for animals fed algae. These data suggest errors may be introduced by assumptions of constant stoichiometry for nutrient release in varying environments.GLERL Contribution No. 268     

Advanced psychometric testing on a clinical screening tool to evaluate insomnia: sleep condition indicator in patients with advanced cancer

Sleep and Biological Rhythms - To examine the psychometric properties of the Sleep Condition Indicator (SCI) using different psychometric approaches [including classical test theory, Rasch models,...     

Detection of Peptide-Based Nanoparticles in Blood Plasma by ELISA

AimsThe aim of the current study was to develop a method to detect peptide-linked nanoparticles in blood plasma.ResultsThe ELISA based method for the detection of FITC labeled peptides had a detection limit of 1 ng/mL. We were able to accurately measure peptides bound to pentafluorophenyl methacrylate nanoparticles in blood plasma of rats, and similar results were obtained by LC/MS.ConclusionsWe detected FITC-labeled peptides on pentafluorophenyl methacrylate nanoparticles after injection in vivo. This method can be extended to detect nanoparticles with different chemical compositions.