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1.
The formation of new root apices from small groups of cells with different cellular patterns has been simulated using an existing model based on growth tensors. To generate an apex, a steady growth field was used. The pattern of cells evolved to approach the steady state. Two extreme types of progressions have been obtained : one leading to an apex with a single or a few apical cells, and the other to an apex with a quiescent centre. The change of structure while applying a steady growth tensor indicates that development may involve a succession of discrete growth tensors. 相似文献
2.
Keiko Oku 《Journal of Ethology》2009,27(2):279-283
In the Kanzawa spider mite, Tetranychus kanzawai (Acari: Tetranychidae), adult males guard pre-reproductive quiescent females. I experimentally examined the effects of density
experience during development and/or after adult emergence on precopulatory mate guarding behavior by T. kanzawai males. Mate guarding behavior was modified by density experience after adult emergence. When males had previously experienced
high density after adult emergence (n = 71), 73.2% of them engaged in precopulatory mate guarding. In contrast, when males had previously experienced low density
after adult emergence (n = 82), 61.0% of them did not guard females. Mate guarding with physical contact occurred more frequently when males had previously
experienced a high density of potential rivals than when they had not, but the difference in behavior between the two groups
of males was marginally not significant. Nevertheless, these results suggest overall that T. kanzawai males change mate guarding behavior in response to previously experienced density. 相似文献
3.
Usually the presence of the quiescent centre in roots is demonstrated by the absence of labelled nuclei following treatment of the root with appropriate radioactive markers. By modification of the pulselabelling technique, a negative image of the quiescent center, showing more intense labelling from [3H]thymidine than the surrounding area, was obtained in regenerating root apices of Zea mays L. 相似文献
4.
Some species of Cactaceae from the Sonoran Desert are characterized by a determinate growth pattern of the primary root, which is important for rapid lateral-root formation and seedling establishment. An analysis of the determinate root growth can be helpful for understanding the mechanism of meristem maintenance in plants in general. Stenocereus gummosus (Engelm.) Gibson & Horak and Pachycereus pringlei (S. Watson) Britton & Rose are characterized by an open type of root apical meristem. Immunohistochemical analysis of 5-bromo-2-deoxyuridine incorporation into S. gummosus showed that the percentage of cells passing through the S-phase in a 24-h period is the same within the zone where a population of relatively slowly proliferating cells could be established and above this zone in the meristem. This indicated the absence of the quiescent center (QC) in S. gummosus. During the second and the third days of growth, in the distal meristem portion of P. pringlei roots, a compact group of cells that had a cell cycle longer than in the proximal meristem was found, indicating the presence of the QC. However, later in development, the QC could not be detected in this species. These data suggest that during post-germination the absence of the establishment of the QC within the apical meristem and limited proliferative activity of initial cells are the main components of a determinate developmental program and that establishment of the QC is required for maintenance of the meristem and indeterminate root growth in plants.Abbreviations QC quiescent center - RCP root cap-protoderm - BrdU 5-bromo-2-deoxyuridine - FITC fluorescein isothiocyanate - DAPI 4,6-diamidino-2-phenylindole 相似文献
5.
Coordinated synthesis of the nuclear protein cyclin and DNA in serum-stimulated quiescent 3T3 cells 总被引:7,自引:0,他引:7
R Bravo 《FEBS letters》1984,169(2):185-188
Quantitative two-dimensional gel electrophoretic analysis (IEF) of the nuclear polypeptide cyclin together with autoradiographic studies have revealed a coordinate synthesis of cyclin and DNA after serum stimulation of quiescent 3T3 cells. These results strengthen the notion that cyclin may be a central component of the pathway(s) that regulate cell proliferation. 相似文献
6.
用~3H-胸腺嘧啶核苷标记的自显影方法测定了大豆根尖的静止中心。结果表明在萌发后24小时产生,其高度为最大值,随着天数增加静止中心的高度逐渐减小。静止中心的高度与根的直径显著相关(r=0.94,p=0.01)。用显微光度计测定了静止中心细胞核的DNA 含量,大部分细胞在2c 水平,处在 G_1期。大豆根尖的静止中心与维管组织分化水平不相关,静止中心不直接控制维管组织的分化。 相似文献
7.
Lewis J. Feldman 《Planta》1979,145(4):315-321
Removal of the quiescent center (QC) from the root apex of maize (Zea mays L., cv. Kelvedon 33) initiates a set of events which culiminate in the regeneration of an intact apex with a newly formed QC. Concomitant with the formation of a new QC is a marked reduction in extractable cytokinins in the tissue of the proximal meristem. Replacing the excised QC with a Dowex (acidic cation-exchange resin) bead affects both root growth and QC regeneration. Root growth is inhibited by plain Dowex beads and Dowex beads treated with zeatin; this inhibition is reversed if the beads have been treated with CaCl2 (±zeatin). Dowex beads treated with zeatin delay the formation of a new QC; this effect is the same whether or not the beads also contain CaCl2. The results of this investigation support the notions that cytokinin biosynthesis in roots is a result of activities of both the QC and the proximal meristem, and that cytokinins, at least if supplied exogenously, can play a role in root morphogenesis by delaying the regeneration of the QC.Abbreviations used throughout the text PM
proximal meristem
- QC
quiescent center
- RC
root cap 相似文献
8.
9.
Three maize root-specific genes are not correctly expressed in regenerated caps in the absence of the quiescent center 总被引:6,自引:0,他引:6
The quiescent center is viewed as an architectural template in the root apical meristem of all angiosperm and gymnosperm
root tips. In roots of Arabidopsis thaliana (L.) Heynh., the quiescent center inhibits differentiation of contacting initial cells and maintains the surrounding initial
cells as stem cells. Here, the role of the quiescent center in the development of the maize (Zea mays L.) root cap has been further explored. Three maize root-specific genes were identified. Two of these were exclusively expressed
in the root cap and one of them encoded a GDP-mannose-4,6-dehydratase. Most likely these two genes are structural, tissue-specific
markers of the cap. The third gene, a putative glycine-rich cell wall protein, was expressed in the cap and in the root epidermis
and, conceivably is a positional marker of the cap. Microsurgical and molecular data indicate that the quiescent center and
cap initials may regulate the positional and structural expression of these genes in the cap and thereby control root cap
development.
Received: 22 September 1999 / Accepted: 9 November 1999 相似文献
10.