Genetic diversity in Chihuahuan Desert populations of creosotebush (Zygophyllaceae: Larrea tridentata).

We examined isozyme variation in the dominant Chihuahuan Desert shrub, Larrea tridentata (creosotebush), to determine the genetic variation within and among populations, the biogeographic relationships of populations, and the potential inbreeding in the species. We surveyed 17 populations consisting of 20 to 50 individuals per population along a 1600-km north-south transect across the Chihuahuan Desert. The southernmost population was near Villa Hidalgo, Mexico, and the northernmost near Isleta Pueblo, New Mexico.

Effects of lincomycin on PSII efficiency, non-photochemical quenching, D1 protein and xanthophyll cycle during photoinhibition and recovery.

Leaves of Parthenocissus quinquefolia (L.) Planch. (Virginia creeper) were treated with lincomycin (an inhibitor of chloroplast-encoded protein synthesis), subjected to a high-light treatment and allowed to recover in low light.

Are melanized feather barbs stronger?

Melanin has been associated with increased resistance to abrasion, decreased wear and lowered barb breakage in feathers. But, this association was inferred without considering barb position along the rachis as a potentially confounding variable. We examined the cross-sectional area, breaking force, breaking stress, breaking strain and toughness of melanized and unmelanized barbs along the entire rachis of a primary feather from an osprey (Pandion haliaetus).

Evolution of insect abdominal appendages: are prolegs homologous or convergent traits?

Many insects possess abdominal prolegs, raising the question of whether these prolegs are homologous or convergent structures. One way to address this issue is to compare mechanisms controlling the development of prolegs in different insects. Segmental morphologies along the insect body are controlled by the regulatory activities of the Hox proteins, and one well-studied regulatory target is the Distal-less (Dll) gene, which is required for the development of distal limb structures in arthropods.