Phloem of Primitive Angiosperms. II. P-Protein in Selected Species of the Ranalean Complex

A survey of the phloem-protein (P-protein) in species of primitive angiosperms was undertaken to provide possible evidence for P-protein function from a phylogenetic point of view. The ontogeny and substructure of P-protein in Liriodendron tulipifera and Magnolia soulangeana are similar to that of more advanced dicot species. In the light of this information the time of P-protein evolution seems to coincide with the development of the angiosperms themselves

Phloem of Primitive Angiosperms. III. Phloem of Petioles of Drimys granadensis (Winteraceae)

Drimys granadensis (Winteraceae) was chosen for study because of its primitive evolutionary position among angiosperms. Mature sieve elements of the primary phloem of petioles are enucleate and have what we interpret as crystalline P-protein in addition to the more common tubular and fibrillar forms. Companion cells associated with sieve elements retain normal-appearing nuclei and possess bodies of flocculent material within the cytoplasm. The pores connecting mature adjacent sieve elements are of much smaller diameter than those typically encountered in angiosperms. The possession of P-protein and companion cells in Drimys argues for the early evolution of these traits in angiosperm phloem

Crystals Associated with the Intertracheid Pit Membrane of the Woody Fern Botrychium multifidum

Volume: 92Start Page: 10End Page: 1

Pit membranes in tracheary elements of Rosaceae and related families : new records of tori and pseudotori

The micromorphology of pits in tracheary elements was examined in 35 species representing 29 genera of Rosaceae and related families to evaluate the assumption that angiosperm pits are largely invariant. In most Rosaceae, pit membranes between fibers and tracheids frequently appear to have amorphous thickenings with an irregular distribution. Although these structures are torus-like under the light microscope, observations by electron microscopy illustrate that they represent "pseudotori" or plasmodesmata-associated thickenings. These thickenings frequently extend from the periphery of the pit membrane and form a cap-like, hollow structure. Pseudotori are occasionally found in few Elaeagnaceae and Rhamnaceae and appear to be related to species with fiber-tracheids and/or tracheids. True tori are strongly associated with round to oval pit apertures and are consistently present in narrow tracheary elements of Cercocarpus (Rosaceae), Planera (Ulmaceae), and ring-porous species of Ulmus and Zelkova (Ulmaceae). Vestured pits with homogenous pit membranes are reported for Hemiptelea (Ulmaceae). The homoplastic nature of pit membrane characteristics may be related to functional adaptations in terms of safety and efficiency of water transport or may reflect different developmental processes of xylem elements. These observations illustrate that there is more variation in angiosperm pits than previously thought

A Human case of Otoacariasis involving a histiostomatid mite (Acari: histiostomatidae)

Corresponding Author: Mr.Gary R. Mullen, Department of Entomology and Plant Pathology, 301 Funchess Hall, Auburn University, Auburn, AL 36849-5413. E-mail: [email protected] 31-year-old Saudi man was seen at an ear, nose, and throat clinic at Riyadh, Saudi Arabia, with bilateral itching in the external auditory canal. On otoscopic examination, the skin lining the ear canal was thickened with whitish sheets of sloughed cells and thick discharge. Large numbers of mites of an undescribed species closely related to members of the genus Loxanoetus (Histiostomatidae) were present. The patient underwent successive washings of the ear canal with saline and 70% ethanol at intervals of 2–3 months and was treated with antibiotics. Treatment with Eurax (crotamiton) ear drops for one week cleared the mite infestation. This represents the first reported case of human otoacariasis involving a histiostomatid mite. Based on the known biology of histiostomatid mites and the associated hosts of Loxanoetus and related genera, there is reason to speculate that the patient acquired the infestation while swimming in a lake or pond where this mite was present

Pit membranes of Ephedra resemble gymnosperms more than angiosperms

Bordered pit pairs of Ephedra species were characterized using different types of microscopy. Pit membranes contained tori that did not stain for lignin. SEM and AFM views of the torus surface showed no plasmodesmatal openings, but branched, secondary plasmodesmata were occasionally noted using TEM in conjunction with ultrathin sections. The margo consisted of radial microfibrils as well as finer diameter tangential fibrils. The former formed fascicles of fibrils that merged into even thicker buttresses during the act of pit membrane aspiration. AFM showed a discontinuous layer of non-microfibrillar material on the surface of both torus and margo. It is hypothesized that this material is responsible for adhesion of the pit membrane to the surface of the pit border during the process of aspiration. Taken as a whole, intervascular pit membranes of Ephedra more closely resemble those of conifers than those of torus-bearing pit membranes of angiosperms

Influence of Elevated CO\u3csub\u3e2\u3c/sub\u3e, Nitrogen, and \u3ci\u3ePinus elliottii\u3c/i\u3e Genotypes on Performance of the Redheaded Pine Sawfly, \u3ci\u3eNeodiprion lecontei\u3c/i\u3e

Slash pine (Pinus elliottii Engelm. var. elliottii) seedlings were grown in open-top chambers receiving ambient or elevated atmospheric CO2 (-365 or -720 μL.L-1). Seedlings received low or high soil nitrogen treatments (0.02 or 0.2 mg N.g-1) and represented three families varying in resistance to fusiform rust (Cronartium quercuum (Berk.) Miyabe ex Shirai f. sp. fusiforme (Hedgc. & N. Hunt) Burdsall & G. Snow). Following 18 months of exposure to treatment conditions, current-year needles were fed to larvae of the redheaded pine sawfly (Neodiprion lecontei (Fitch)). Needle N concentration and water content were lower in elevated-CO2 and in low-N treatments. Total phenolics increased under high-CO2 and low-N conditions and were highest in the resistant family. Condensed tannins did not vary on the basis of CO2 or N but were higher in needles from the resistant family. Alterations in needle chemistry were associated with variations in sawfly growth and development. Larvae performed most poorly on the family most resistant to fusiform rust, suggesting that the mechanism for resistance was similar in both cases. Relative consumption rates increased with CO2-enriched needle diets but were depressed for resistant needles, suggesting deterrence from the higher total phenolics in this family. Diets using CO2-enriched needles or resistant needles or needles from low-N fertilization treatments resulted in lower relative growth rates for the larvae. Days to pupation increased for larvae fed CO2-enriched and low-N needles. These results suggest that the redheaded pine sawfly could suffer as the level of atmospheric CO2 continues to rise