Occurrence, types and distribution of calcium oxalate crystals in leaves and stems of some species of poisonous plants.

BACKGROUND: Calcium oxalate crystals, which are found in many organs of plants, have different morphological forms: as druses, prism, styloids, raphides and crystal sand. In this study, the distribution, type and specific location of calcium oxalate crystals in the leaves and stems of the eight species of poisonous plants and one species of nonpoisonous plant were investigated with light microscopy. During study special attention was given to the possible correlation between the presence and types of calcium oxalate crystals and toxic plant organs. The plants examined in this study were Hedera helix L. (Araliaceae), Aristolochia clematitis L. (Aristolochiaceae), Humulus lupulus L. (Cannabaceae), Saponaria officinalis L. (Caryophyllaceae), Chelidonium majus L. (Papaveraceae), Hypericum perforatum L. (Hypericaceae), Tribulus terrestris L. (Zygophyllaceae), Cynanchum acutum L. (Asclepiadaceae), and Nerium oleander L. (Apocynaceae). RESULTS: Three types of crystals: druses, prismatic crystals and crystal sands were observed. Druses were identified in the leaves and stems of six species of studied plants. In contrast to druses, crystal sands and prismatic crystals were rare. Prismatic crystals were observed in the leaf mesophlly cells of both Nerium oleander and Cynanchum acutum. However, crystal sands were observed only in the pith tissue of Humulus lupulus. On the other hand, leaves and stems of Chelidonium majus, Aristolochia clematitis and Hypericum perforatum were devoid of crystals. CONCLUSION: There is no absolute correlation between the presence and type of calcium oxalate crystals and toxic plant organs. However druse crystals may function as main irritant in toxic organs of the plants.

Ultrastructure of central cell in female gametophyte of Castilleja wightii Elmer (Scrophulariaceae).

Embryo sac cells are highly differentiated in plants. The central cell is one of the most important cells of the embryo sac. It forms endosperm by fusion with a sperm cell. Ultrastructure of the central cell in the mature embryo sac of Castilleja wightii was investigated in this study. Nucleolus which had a lot of vacuole in a large secondary nucleus and numerous dictyosomes, vesicles, mitochondria, amyloplasts in cytoplasm were seen in this cell. Also free ribosomes in the form of polysomes and large lipid bodies were detected in the cytoplasm. Numerous vacuoles of different size were observed and some of them had autophagic function. Both smooth and rough endoplasmic reticulums were seen. Although invaginations were seen in the plasmalemma of the central cell to the inside of the embryo sac, a thick cuticular layer was observed outer side on the cell wall. The aim of this study was to contribute studies about the ultrastructure of embryo sacs.

Ultrastructural studies on the sporogenous tissue and anther wall of Leucojum aestivum (amaryllidaceae) in different developmental stages.

In this study, ultrastructures of anther wall and sporogenous tissue of Leucojum aestivum were investigated during different developmental stages. Cytomictic channels were seen between pollen mother cells during prophase I. Polar distribution was described in the organelle content of pollen mother cells and microspores in early phases of microsporogenesis and also in pollen mitosis. Active secretion was observed in tapetal cells. Previous reports about developmental stages of male gametophyte were compared with the results of this study.

Effect of nickel on root growth and the kinetics of metal ions transport in onion (Allium cepa) root.

The effect of different concentrations of nickel nitrate (0.25, 0.50, 1.00 and 2.00 mM) uptake by the roots, on root growth of onion (Allium cepa) and the transport of Ni2+, Fe2+, Mn2+, Zn2+, K+, Na+ and H+ ions were investigated spectrophotometrically. The uptake of Ni2+, Fe+, Mn2+ and Zn2+ was monitored by flame atomic absorption spectrometry with a 24-h period for 7 days and the amounts of K+ and Na+ were determined in solutions by flame photometer. The mineral content of the solution, instead of the root material was measured. Ni2+ ions showed inhibitory effect on the root growth at all concentrations during the entire treatment. The ECso (effective concentration that reduced root growth by 50%) was found at 0.25 mM Ni2+. No significant change in inhibitory effect was observed after at 0.50 mM Ni2+ concentrations. A large amount of Ni2+ was translocated into the roots. The kinetics of metal ion transport followed a pseudo-first order reaction in all metal ion concentrations. Ni2+, Zn2+ Fe2+ Mn2+ and H+ ions transferred together into plant, but Na+ and K+ ions transferred to the solution from the plant. The amount of H+ in the solution decreased at all Ni2+ concentrations.

Ultrastructural features of Mimulus aurantiacus (Scrophulariaceae) pollen tubes in vivo.

The aim of this study is to give information on ultrastructure of in vivo pollen tubes of Mimulus aurantiacus which were collected from the Botanical Garden of the University of California at Berkeley. Materials were prepared according to electron microscopy methods and examined under Zeiss electron microscope. Four zones were examined in the pollen tubes of Mimulus aurantiacus. Apical zone: Mitochondria, smooth endoplasmic reticulum, rough endoplasmic reticulum, dictyosomes and secretory vesicles were observed. Subapical zone: This area contained abundant rough endoplasmic reticulum and occasionally some smooth endoplasmic reticulum. The polysomes, mitochondria, proplastids that contain starch, small vacuoles and a few lipid bodies were detected. Nuclear zone: Both generative and vegetative cell nuclei lie in this zone. The vegetative cell nucleus was large and long. Rough endoplasmic reticulum, mitochondria, ribosomes, dictyosomes, and amyloplasts that are rich of starch were observed. Vacuolation and plug formation zone: Cytoplasm of the tubes was full of large vacuoles. Few organelles such as mitochondria, dictyosome and rough endoplasmic reticulum were detected along their periphery.

Ultrastructural features of Mimulus aurantiacus (Scrophulariaceae) pollen tubes in vivo

The aim of this study is to give information on ultrastructure of in vivo pollen tubes of Mimulus aurantiacus which were collected from the Botanical Garden of the University of California at Berkeley. Materials were prepared according to electron microscopy methods and examined under Zeiss electron microscope. Four zones were examined in the pollen tubes of Mimulus aurantiacus. APICAL ZONE: Mitochondria, smooth endoplasmic reticulum, rough endoplasmic reticulum, dictyosomes and secretory vesicles were observed. SUBAPICAL ZONE: This area contained abundant rough endoplasmic reticulum and occasionally some smooth endoplasmic reticulum. The polysomes, mitochondria, proplastids that contain starch, small vacuoles and a few lipid bodies were detected. NUCLEAR ZONE: Both generative and vegetative cell nuclei lie in this zone. The vegetative cell nucleus was large and long. Rough endoplasmic reticulum, mitochondria, ribosomes, dictyosomes, and amyloplasts that are rich of starch were observed. VACUOLATION AND PLUG FORMATION ZONE: Cytoplasm of the tubes was full of large vacuoles. Few organelles such as mitochondria, dictyosome and rough endoplasmic reticulum were detected along their periphery.

O objetivo deste estudo é informar sobre a ultraestrutura de tubos de pólen de Mimulus aurantiacus in vivo coletados no "Botanical Garden" da Universidade da Califórnia em Berkeley. O material foi preparado de acordo com os métodos de microscopia eletrônica e examinado em microscópio eletrônico Zeiss. Quatro zonas dos tubos de pólen de Mimulus aurantiacus foram examinadas. ZONA APICAL: foram observados mitocôndrias, retículo endoplasmático liso; retículo endoplasmático rugoso, dictiossomos e vesículas secretoras. ZONA SUBAPICAL: esta área continha retículo endoplasmático rugoso em abundância e, ocasionalmente, algum retículo endoplasmático liso. Foram detectados polissomos, mitocôndrias, proplastídeos que contêm amido, pequenos vacúolos e alguns corpos lipídicos. ZONA NUCLEAR: nesta área, existem tanto núcleos de células geradoras como vegetativas. O núcleo de célula vegetativa é grande e longo. Foram observados retículo endoplasmático rugoso, mitocôndria, ribossomos, dictiossomos e amiloplastos ricos em amido. ZONA DE VACUOLIZAÇÃO E DE FORMAÇÃO DE "PLUG": o citoplasma dos tubos estava cheio de grandes vacúolos. Algumas organelas como mitocôndria, dictiossomo e retículo endoplasmático rugoso foram detectadas em toda a periferia desta área.

Ultrastructure of endothelium in ovules of Penstemon gentianoides Poir. (Scrophulariaceae) at mature embryo sac phase.

In this study ultrastructural differences between endothelial cells of different location in Penstemon gentianoides have been examined with electron microscope at mature embryo sac phase. Embryo sac is of the Polygonum type and surrounded by endothelium except the micropylar region. The cuticle is located primarily around the chalazal three-fourths of the embryo sac. Endothelium cells around the chalaza and toward the micropylar region are rich in cytoplasmic organelles. The cytoplasm of endothelial cells near the central cell has large vacuoles and few organelles. There are also plasmodesmas on the anticlinal walls of endothelial cells. The endothelium and the micropylar integumentary cells play a role in transport of metabolites into the embryo sac.

Cytological and histological studies on reproductive system of hexaploid Bellevalia edirnensis Ozhatay & Mathew (hyacinthaceae).

In this study anther wall, meiosis, sporogenesis and the development of female gametophytes of Bellevalia edirnensis were examined cytologically and histologically. The young anther wall consists of an epidermis, a single layered fibrous endothecium, 1-2 middle layers which disappear early, and a single-layered tapetum. In the glandular tapetum; normal mitosis, the "sticky" type of division and secondary nucleus divisions were observed. In most microspore mother cells the course of meiosis is regular. In some cells irregularities were observed including chromosome bridges and univalents. Cytokinesis is of the successive type and the tetrads are isobilateral. The ovules are anatrapous, bitegmic and crassinucellate. The micropyle is formed by the inner integument. The female archesporium is unicelled and directly functions as the megaspore mother cell. The female gametophyte formed by the functioning chalazal megaspore is monosporic, of the Polygonum type.