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Cytological Studies (cytological + studies)
Selected AbstractsUltrastructural and Immunocytochemical Studies on Effects of Barley Yellow Dwarf Virus , Infection on Fusarium Head Blight, Caused by Fusarium graminearum, in Wheat PlantsJOURNAL OF PHYTOPATHOLOGY, Issue 1 2006Y. Liu Abstract The interactions between barley yellow dwarf virus (BYDV) and Fusarium head blight (FHB), caused by Fusarium graminearum, were studied in the two winter wheat cultivars (cvs.), Agent (susceptible to FHB) and Petrus (moderately resistant to FHB), using ultrastructural and immunocytochemical methods. Infections of wheat plants of both cvs. by BYDV increased susceptibility to FHB. BYDV infection caused numerous cytological changes in lemma tissue of both cvs. such as formation of vesicles in the cytoplasm, degradation of fine structures of chloroplasts of both cvs. and accumulation of large starch grains in the chloroplasts. Electron microscopical studies showed that the development of F. graminearum on spike surfaces was not affected in BYDV-infected plants. After penetration and intercellular growth in lemma tissue, defence responses to Fusarium infections were markedly reduced in BYDV-diseased plants compared to the tissue of virus-free plants. At sites of contact of fungal cells with host tissue, depositions of cell wall material were distinctly less pronounced than in tissues of virus-free plants of cv. Petrus. Detection of , -1,3-glucanases and chitinases in lemma tissue of cv. Agent revealed no appreciably increased accumulation of both defence enzymes in F. graminearum -infected virus-free and BYDV-infected tissues compared to the non-infected control tissue. On the other hand, in cv. Petrus, infection with F. graminearum induced a markedly enhanced activity of both enzymes 3 days after inoculation. The increase of both enzyme activities was less pronounced in BYDV-infected plants than in tissue exclusively infected with F. graminearum. Cytological studies suggest that in contrast to the susceptible cv. Agent postinfectional defence responses may play still an important role in the resistance of the moderately resistant cv. Petrus to FHB. [source] Cytological studies on induced meiogynogenesis in Japanese flounder Paralichthys olivaceus (Temminck et Schlegel)AQUACULTURE RESEARCH, Issue 6 2009Jilun Hou Abstract The cytological process of induced gynogenetic development and subsequent chromosome duplication by a cold shock treatment was observed in Japanese flounder Paralichthys olivaceus (Temminck et Schlegel). Mature eggs were at the metaphase of the second meiosis when inseminated with ultraviolet (UV)-irradiated sperm of red sea bream Pagrus major. After the beginning of cold shock treatment, the previously visible spindle became invisible, probably due to the side effect caused by cold shock treatment. The chromosomes at the centre of the metaphase plate were condensed. This condition continued during the duration of the cold shock treatment and several minutes after it. The release of the second polar body was blocked and it developed into a female-like pronucleus. Then, it fused with the female pronucleus to generate a diploid zygotic nucleus, and the egg exhibited the first mitosis. Consequently, the haploid female chromosome set of the egg was doubled by the inhibition of the second polar body release. There was a significant delay in developmental time in the gynogenetic eggs when compared with that in the normal eggs. From the time of insemination to early cleavage, the UV-irradiated heterospecific sperm nucleus remained condensed. [source] Cytological studies on the eastern Asian family TrochodendraceaeBOTANICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2008XUE YANG The somatic chromosome numbers for Trochodendron and Tetracentron were determined as 2n = 38 from shoot tip cells, from cultivated plants introduced from three places in Japan and southwest China. This number is consistent with one of the only two previous studies on the two genera and adds support for their membership of a distinct family Trochodendraceae. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158, 332,335. [source] Surgical bone marrow aspiration in Aotus lemurinus griseimembraJOURNAL OF MEDICAL PRIMATOLOGY, Issue 3 2006Cesar Llanos Abstract Aotus lemurinus griseimembra are highly susceptible to infection by human malaria parasites and reproduce some of its clinical manifestations, including anemia. We developed a new surgical technique to obtain bone marrow samples from Aotus by surgical aspiration of the femur. First, we determined that the femur offered advantages over other bones, primarily due to lower fracture vulnerability. We tested a surgical technique using 20 G IV catheters in formaldehyde-preserved animals, then conducted the procedure on 27 live animals. This technique provided easy, quick surgical access to adequate volumes of bone marrow and was safe for almost all animals: only one died; another developed nervous impairment of the lower limb. Adequate cell samples were obtained in all animals and allowed cytological studies. This procedure offers a useful tool for bone marrow research in Aotus and helps overcome current limitations of such research in human where these studies are limited by ethical and technical issues. [source] Phylogenetics and biogeography of eastern Asian,North American disjunct genus Pachysandra (Buxaceae) inferred from nucleotide sequencesJOURNAL OF SYSTEMATICS EVOLUTION, Issue 3 2009Zhihua JIAO Abstract Pachysandra is an eastern Asian,North American disjunct genus with three species, two in eastern Asia (Pachysandra axillaris and Pachysandra terminalis) and one in eastern North America (Pachysandra procumbens). Although morphological and cytological studies suggest a close affinity of P. procumbens with P. axillaris, molecular data from nuclear and chloroplast DNA regions have provided conflicting signals. In this study, we tested previous phylogenetic hypotheses using sequences of nuclear ribosomal DNA internal transcribed spacers and chloroplast ndhF gene from multiple individuals of each of the three species. We also estimated the time of divergence between eastern Asia and eastern North America. Our results support the morphological and cytological conclusion that P. procumbens is more closely related to P. axillaris than to P. terminalis. The estimated time of divergence of P. axillaris and P. procumbens was 14.6±5.5 mya, consistent with estimates from many other eastern Asian,North American disjunct genera. The migration of Pachysandra populations from eastern Asia to North America might have occurred by way of the North Atlantic land bridge. [source] | ||||||||||