Ultrastructural studies of fossil plant cuticles: Ticoa harrisii from the early Cretaceous of Argentina

ARCHANGELSKY, S., TAYLOR, T. N. & KURMANN, M. H., 1985. Ultrastructural studies of fossil plant cuticles: Ticoa harrisii from the early Cretaceous of Argentina. The fine structure of fossil plant cuticles of Cretaceous age demonstrates well preserved layers that are topographically equivalent to those in some extant plants. Cuticle stratification on specialized structures (stomatal apparatus and trichomes) is presented, together with an account of the fine structure of both the upper and lower cuticular membrane. Levels of cuticle stratification are compared with those of extant plants.     

THE INFLUENCE OF TASTANTS ON ORAL IRRITATION BY CAPSAICIN

Single-point intensity scaling and time-intensity methods were used to record oral irritation from solutions of 2 ppm capsaicin, capsaicin with added sucrose (0.04M), NaCl (0.3M), citric acid (0.01M) or xanthan gum (0.2%). Only sucrose depressed mouth-burn, both in magnitude and duration. The viscosity imparted by xanthan retarded perception of mouth-burn but did not effect its duration. While single-point scaling averaged perceived intensity across time, time-intensity provided much more information by displaying perception from onset to decay. Eaters and non-eaters of chili peppers did not differ in their perception of mouth-burn.     

Differentiation of metallicolous and non‐metallicolous Salix caprea populations based on phenotypic characteristics and nuclear microsatellite (SSR) markers

The Salicaceae family comprises a large number of high‐biomass species with remarkable genetic variability and adaptation to ecological niches. Salix caprea survives in heavy metal contaminated areas, translocates and accumulates Zn/Cd in leaves. To reveal potential selective effects of long‐term heavy metal contaminations on the genetic structure and Zn/Cd accumulation capacity, 170 S. caprea isolates of four metal‐contaminated and three non‐contaminated middle European sites were analysed with microsatellite markers using Wright's F statistics. The differentiation of populations North of the Alps are more pronounced compared to the Southern ones. By grouping the isolates based on their contamination status, a weak but significant differentiation was calculated between Northern metallicolous and non‐metallicolous populations. To quantify if the contamination and genetic status of the populations correlate with Zn/Cd tolerance and the accumulation capacity, the S. caprea isolates were exposed to elevated Cd/Zn concentrations in perlite‐based cultures. Consistent with the genetic data nested anova analyses for the physiological traits find a significant difference in the Cd accumulation capacity between the Northern and Southern populations. Our data suggest that natural populations are a profitable source to uncover genetic mechanisms of heavy metal accumulation and biomass production, traits that are essential for improving phytoextraction strategies.     

Microsatellite markers in Carica papaya L.: isolation,characterization and transferability to Vasconcellea species

A dinucleotide microsatellite‐enriched genomic library was obtained from Carica papaya L. Sixty‐nine microsatellites were evaluated on three genotypes of C. papaya and seven species of the neighbour genus Vasconcellea. Among them, 45 markers were characterized on a sample of 29 accessions of C. papaya from the Caribbean region and 11 accessions of Vasconcellea from the Andes of Colombia and Ecuador. Twenty‐four gave polymorphism in C. papaya and only four among the seven species of Vasconcellea, confirming the divergence between both genera.     

Exploring a key synapomorphy: correlations between structure and function in the sternum V glands of Trichoptera and Lepidoptera (Insecta)

The sternum V glands are a key synapomorphy that unites Trichoptera with Lepidoptera, but their functional aspects have not been analysed from an evolutionary perspective. We examine phylogenetic trends and correlations between chemical and morphological features of these glands. The most likely ancestral gland compounds are heptan‐2‐ol, 4‐hepten‐2‐one and ‐ol, nonan‐2‐one, and 6‐nonen‐2‐one and ‐ol, making pheromone production a plausible ancestral function. The most widespread gland compounds (heptan‐2‐one and ‐ol and nonan‐2‐one and ‐ol) are not known from Apataniidae + Limnephilidae (Trichoptera), which in turn uniquely produce a number of methylated 3‐ketones and their corresponding alcohols, probably functioning as pheromones. We propose a functional connection between perforated patches on sternum IV in females and a scaly/dome‐covered area around the gland openings, as well as between perforated patches and lack of Trichoptera‐type opening muscles. We also propose a functional connection between the shape of the gland reservoirs and the presence of gland reservoir musculature. The perforated patches were significantly correlated with several gland compounds that had double bonds between carbon atoms: the double bonds may lower the viscosity of the compounds, facilitating secretion through the tiny pores of the perforated patches. The production of defensive substances in Pycnopsyche (Trichoptera: Limnephilidae) is probably connected to the presence of large, compartmentalized gland reservoirs. Large glands in male Hydropsyche (Trichoptera: Hydropsychidae) are probably linked to male aggregation pheromone production. The relative sizes of sternum V gland reservoirs and fenestral gland reservoirs in female philopotamids (Trichoptera) suggest a complementary function of the two structures. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 106 , 561–579.