Population genetic variation in rare and endangered Iliamna (Malvaceae) in Virginia

Random amplified polymorphic DNA (RAPD) markers were used as input for an analysis of molecular variance (AMOVA), homogeneity of molecular variance analysis (HOMOVA), and cluster analysis to describe the population genetic structure of Iliamna corei, a federally endangered plant located only in Virginia, and I. remota , a rare plant in Virginia, Indiana, and Illinois. The analysis was performed to help clarify the taxonomic relationship between the two closely related species. We analysed four clones in the only known population of I. corei , breeding stock derived from seeds originating from the population site, and three I. remota populations in Virginia. Eighty-five percent of screened primers revealed DNA polymorphisms in Iliamna. Ninety-nine informative markers were generated using seven primers. No significant statistical differences (at P = 0.05) in RAPD variation was found between species (24% of variance) using the AMOVA procedure. However, within species/among populations (31 % of the variance) and within populations (45% of the variance) there were significant differences (P < 0.002). An unweighted paired group method using arithmetic averages (UPGMA) cluster analysis showed the federally endangered I. corei population to be genetically distinct from the apparently recently introduced (in Virginia: ∼ 100 ybp) I. remota. The lack of significant differences from the AMOVA and the high number shared bands between I. corei and I. remota suggest that I. corei may be more appropriately classified as a subspecies of I. remota. Iliamna corei plants in the natural population were genetically similar to one another while the I. corei breeding stock plants and I. remota plants were genetically relatively diverse.     

Oviposition Site Choice and Life History Evolution

SYNOPSIS. Studies of life history evolution, as well as muchof life history theory, have typically focused on "hard" componentsof life histories; phenotypic characteristics that can be readilyobserved, quantified, and ultimately, connected rather directlyto fitness. Typical of these are propagule size, propagule number,and age and size at maturity. What is largely missing from thestudy of life history evolution is consideration of the roleof behavior, principally female oviposition site choice, inthe evolution of life histories. For oviparous organisms, naturalselection cannot produce locally optimized "hard" componentsof life history phenotypes without a consistent environmentalcontext (whether invariant orvariable); in a variable environment,that consistent environmental context can be most effectivelyprovided by interactive oviposition site choice. I present amodel of selection on oviposition site choice in the contextof the evolution of "hard" components of life history phenotypes,along with some experimental data illustrating oviposition sitechoice in response to predators. The model and data are thenrelated to the overall question of the role of oviposition sitechoice in life history evolution. The conclusion is that ovipositionsite choice must be under equally strong selection with eggsize, egg number and the other hard components of life historiesin order to generate and optimize locally adapted or ecologicallyspecialized life history phenotypes, and must therefore, playa significant role in the evolution of life histories.     

The Importance of Body Stiffness in Undulatory Propulsion

During steady swimming in fish, the dynamic form taken by theaxial undulatory wave may depend on the bending stiffness ofthe body. Previous studies have suggested the hypothesis thatfish use their muscles to modulate body stiffness. In orderto expand the theoretical and experimental tools available fortesting this hypothesis, we explored the relationship betweenbody stiffness, muscle activity, and undulatory waveform inthe mechanical context of dynamically bending beams. We proposethat fish minimize the mechanical cost of bending by increasingtheir body stiffness, which would allow them to tune their body'snatural frequency to match the tailbeat frequency at a givenswimming speed. A review of the literature reveals that theform of the undulatory wave, as measured by propulsive wavelength,is highly variable within species, a result which calls intoquestion the use of propulsive wavelength as a species-specificindicator of swimming mode. At the same time, the smallest wavelengthwithin a species is inversely proportional to the number ofvertebrae across taxa (r² = 0.21). In order to determine ifintact fish bodies are capable of increasing bending stiffness,we introduce a method for stimulating muscle in the body ofa dead fish while it is being cyclically bent at physiologicalfrequencies. The bending moment (N m) and angular displacement(radians) are measured during dynamic bending with and withoutmuscle stimulation. Initial results from these whole body workloops demonstrate that largemouth bass possess the capabilityto increase body stiffness by using their muscles to generatenegative mechanical work.     

Organization of calcium pump protein dimers in the isolated sarcoplasmic reticulum membrane.

The arrangement of the calcium pump protein in the isolated sarcoplasmic reticulum (SR) membrane was examined by optical diffraction of freeze-fracture electron micrographs. Several states of protein particle organization were observed: random, hexagonal and tetragonal packing, and a mixture of hexagonal and tetragonal packing. This suggests that the time-averaged positions of protein particles in the plane of the SR membrane are weakly defined. In addition, there appears to be a greater degree of local or short-range order compared to long-range order within the field of freeze-fracture particles. We utilized measurements from tetragonally or hexagonally packed arrays to determine a unit cell area occupied by each freeze-fracture particle and its associated lipid matrix. When these unit cell areas and the stereologically determined area per freeze-fracture particle were compared to the cross-sectional area occupied by a single calcium pump protein and its associated lipid, obtained by x-ray and neutron diffraction methods, we concluded that each freeze-fracture particle probably represents a dimer of pump protein molecules in the plane of the SR membrane.     

Functional evaluation of murine allogeneic T lymphoblasts separated by Vicia villosa lectin positivity

Mixed-lymphocyte culture-stimulated cells have been fractionated by their ability to bind the lectin Vicia villosa (Vv) and assessed for their cytolytic and suppressor activity in vitro. Vv positive and negative cells were separated either by cell affinity chromatography using Vv-Sepharose 6MB chromatography or by electronic cell sorting with FITC-Vv. Both populations expressed marked cytolytic and suppressor cell activity. Thus this lectin cannot be used to discriminate between these and other functional lymphoid cell population of blastoid cells binding the FITC-Vv appears following allogeneic stimulation; treatment with the immunosuppressive drug cyclosporin A, which affects cytotoxic cells preferentially, results in a considerable reduction of the Vv positive blastoid cells.     

Prevention of the luteolytic action of oxytocin in the goat by inhibition of prostaglandin synthesis

Oxytocin-induced luteolysis in goats was associated with significant increases in peripheral plasma concentrations of 13,14-dihydro-15-keto-prostaglandin F(2alpha) (PGFM). Oral administration of the prostaglandin (PG) synthetase inhibitor meclofenamic acid (lg/day) prevented both the luteolytic action of oxytocin and the increase in PGFM concentrations. These results confirm that the luteolytic effect of oxytocin is mediated via the production and release of PGF(2alpha).     

Derivatives of the red-violet cluster of copper and penicillamine prepared by mixed ligand formation reactions or direct additions

Mixed ligand clusters of the type Cu(I)₈Cu(II)₆L'_(n)L_(12?n)Cl are easily distinguished by zone electrophoresis if ligands L and L' differ in formal charge. Approximately random species distributions were observed when L was penicillamine and L' a related ligand lacking the negative charge of a carboxylate group, provided the L'/L molar ratio was less than $\text{1}\text{9}$ in the reaction mixture. Depending on the choice of L or L', it should be possible to prepare clusters with a variety of pendant groups. The cluster containing only penicillamine apparently forms addition products with carbodiimides and aziridines based on reactions involving the cluster's peripheral carboxylate groups.     

Fluidity and lipid composition of oat and rye shoot plasma membrane: effect of sterol perturbation by xenobiotics

Oat and rye plants were treated with either tetcyclacis (an experimental plant growth regulator), nuarimol (a fungicide) or gamma-ketotriazole (an experimental herbicide). These treatments reduced shoot growth and changed the lipid composition of the shoot plasma membranes. In oat, both tetcyclacis and nuarimol treatments increased plasma membrane cholesterol and increased the phosphatidylethanolamine/phosphatidylcholine (PE/PC) ratio, whereas gamma-ketotriazole treatment reduced cholesterol and the PE/PC ratio. In rye, all treatments reduced the PE/PC ratio. Generally, the sterol/phospholipid ratio was less in oat than in rye but the cholesterol/phospholipid ratio was greater. With all treatments in oat and rye, increases were observed in unsaturation of the phospholipid acyl chains. The fluidity of membranes was measured by steady-state fluorescence polarisation of the probe diphenylhexatriene; oat membranes were more fluid than rye. Membrane fluidity was greater in plasma membranes from plants treated with the xenobiotics than the controls. The results are discussed in the context of the effect of plasma membrane lipid composition on membrane fluidity, and it is concluded that there appears to be no overall simple relationship between membrane lipid composition and fluidity that holds for all treatments in both species.