Plant inbreeding and prior herbivory influence the attraction of caterpillars (Manduca sexta) to odors of the host plant Solanum carolinense (Solanaceae).

PREMISE OF THIS STUDY: The mediation of plant-insect interactions by plant odors has been studied extensively, but most previous work has focused on documenting the role of constitutive and herbivore- or pathogen-induced plant volatiles as foraging cues for insect herbivores and their natural enemies. Relatively little work has explored genotypic variation in plant-odor profiles within species, and few studies have addressed the perception and use of olfactory cues by lepidopteran larvae or other herbivores during feeding. METHODS: We examined the effects of plant breeding (inbred vs. outbred individuals) and plant exposure to prior herbivory on the preferences of caterpillars (Manduca sexta) for odors of Solanum carolinense in leaf-disc and whole-plant choice assays. KEY RESULTS: Second- and third-instar larvae of M. sexta clearly and consistently preferred undamaged over herbivore-damaged plants of both breeding types and also consistently preferred inbred over outbred plants that had the same damage status. Similar preferences were observed even when plants were covered with bridal-veil cloth to mask visual cues, demonstrating that olfactory cues influence larval preferences. CONCLUSIONS: The observed preferences are consistent with our previous findings regarding the constitutive and induced volatile profiles of inbred and outbred horsenettle plants and their effects on plant-herbivore interactions. They furthermore correspond to differences in host-plant quality predicted by previous work and, thus, suggest that naive larvae of M. sexta can accurately assess aspects of host-plant quality via olfactory cues perceived at a distance.

Inbreeding depression in Solanum carolinense (Solanaceae) under field conditions and implications for mating system evolution.

The clonal weed Solanum carolinense exhibits plasticity in the strength of its self-incompatibility (SI) system and suffers low levels of inbreeding depression (δ) in the greenhouse. We planted one inbred and one outbred plant from each of eight maternal plants in a ring (replicated twice) and monitored clonal growth, herbivory, and reproduction over two years. Per ramet δ was estimated to be 0.63 in year one and 0.79 in year two, and outbred plants produced 2.5 times more ramets than inbred plants in the spring of year two. Inbred plants also suffered more herbivore damage than outbred plants in both fields, suggesting that inbreeding compromises herbivore resistance. Total per genet δ was 0.85 over the two years, indicating that S. carolinense is unlikely to become completely self-compatible, and suggesting that plasticity in the SI system is part of a stable mixed-mating system permitting self-fertilization when cross pollen limits seed production.

Identification of a beta-casein-like peptide in breast nipple aspirate fluid that is associated with breast cancer.

AIMS: Nipple aspirate fluid was collected prospectively from women scheduled for diagnostic breast surgery in order to determine protein masses associated with breast cancer, subsets of women with a unique proteomic profile and a breast cancer predictive model. MATERIALS & METHODS: Breast nipple aspirate fluid was collected preoperatively in 163 breasts from 125 women and analyzed for changes in cell morphology and by SELDI-TOF mass spectrometry over approximately a 44 kDa range (1.5-45 kDa) using IMAC30, CM10 and Q10 ProteinChips. RESULTS: Considering all samples, 16 protein masses were associated with the presence of cancer, the most discriminating being 3592, 6570/6580 and 15870 Da. Excluding women with pathologic nipple discharge or those with a papilloma identified an additional protein of 6383 Da. The best cancer detection models included Breast Imaging Reporting and Data System, age, and either the 4262 (best sensitivity: >87%) or 3592 (best specificity: >94%) peak. MALDI-TOF mass spectrometry demonstrated the 3592 peak, which was most discriminating in many of our cancer prediction models, to be a beta-casein-like peptide. CONCLUSION: Differential nipple aspirate fluid proteomic expression exists between women with/without breast cancer. The most discriminating protein identified is a beta-casein-like peptide not previously described. Combining proteomic and clinical information, which are available before surgery, optimizes the prediction of which women have breast cancer.

Altered expression of plant lysyl tRNA synthetase promotes tRNA misacylation and translational recoding of lysine.

The Arabidopsis thaliana lysyl tRNA synthetase (AtKRS) structurally and functionally resembles the well-characterized prokaryotic class IIb KRS, including the propensity to aminoacylate tRNA(Lys) with suboptimal identity elements, as well as non-cognate tRNAs. Transient expression of AtKRS in carrot cells promotes aminoacylation of such tRNAs in vivo and translational recoding of lysine at nonsense codons. Stable expression of AtKRS in Zea mays causes translational recoding of lysine into zeins, significantly enriching the lysine content of grain.