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Myosin associated with the male germ cells of angiosperms interacts with actin, promoting transport of the non-motile generative
and later sperm cells in the pollen tube. Myosin localizing on the sperm cell plasma membrane seems negligible in Plumbago, as reflected by the absence of: (i) anti-myosin labeling using immunoelectron microscopy, (ii) sperm motility on actin matrices,
and (iii) electrophoretic movement changes after addition of antibody. Sperm cells injected directly into actively streaming
Nitella internodal cells, however, follow actin bundles and their movement is sensitive to ATP and Mg2+. This may be based on simple charge binding since negatively charged latex beads also migrate on actin, whereas neutral or
positively-charged latex beads do not. Sperm cells are negatively charged according to capillary microelectrophoresis, whereas
killed sperm cells, which are positively charged do not migrate. The sperm cell that normally fertilizes the egg has a higher
calculated charge (8.277 × 103 esu/cm2) compared with the sperm cell that fuses with the central cell (6.120 × 103 esu/cm2).
Received: 15 December 1998 / Accepted: 21 January 1999 相似文献
4.
Immuno-gold labelling using a monoclonal antibody (PCBC3) with a primary specificity for -L-arabinofuranosyl residues was used to locate these residues in pollen tubes of Nicotiana alata grown in vivo. The antibody bound to the outer fibrillar layer of the pollen-tube wall: the inner, non-fibrillar wall layer was not labelled. Cytoplasmic vesicles (0.2 m diameter) were also labelled. The antibody may bind to an arabinan in the pollen-tube wall. 相似文献
5.
Summary The cyst walls of the ciliatesBlepharisma undulans andPseudomicrothorax dubius were examined ultrastructurally and by postembedding labeling with wheat germ agglutinin (WGA)-gold conjugate. Different methods of fixation and embedding were performed. In all procedures, WGA-gold binds selectively to material of the cyst wall. Pretreatment of the sections with chitinase inhibits labeling. The cyst walls of both species contain 3 nm fibrils, which are supposed to be of chitinous nature. In the cyst wall ofB. undulans, several thin layers of WGA-binding fibrils are interspaced with thick layers of other material. InP. dubius, WGA-binding sites are mainly concentrated in the mesocyst, where the microfibrils appear to represent the major component. These results obtained from two phylogenetically distant species confirm that chitin synthesis is an ancestral feature of ciliated protozoa. The amount and distribution of the chitin fibrils may play an important role in the properties and functions of the wall of the resting cyst. 相似文献
6.
Danuta Dus Maciej Ugorski Wojciech Gorczyca Czeslaw Radzikowski 《Glycoconjugate journal》1989,6(3):355-365
125I-Wheat germ agglutinin (WGA) binding parameters of human urothelial cell lines of different grades of transformation (TGrll and TGrlll) were compared. The values of association constant (Ka) and the number of binding sites/cell for HCV29 (TGrll) cell line were about 3×106M–1 and over 4×107, respectively. Two TGrlll cell lines, HCV29T and Hu549 revealed lower values for Ka, and considerably higher numbers of binding sites/cell (about 3×108 and 2×108, respectively). Binding of125I-WGA to total cellular proteins resolved by SDS-PAGE and transferred to nitrocellulose showed multiple diffused bands in the range of 58–180 kDa. Some of these bands were characteristic for TGrll cells (124 kDa) or TGrlll cells (135 and 148 kDa).Abbreviations TGr
transformation grade
- WGA
wheat germ agglutinin
- sWGA
succinylated wheat germ agglutinin
- GlcNAc
N-acetyl-d-glucosamine
- BSA
bovine serum albumin
- SDS-PAGE
sodium dodecyl sulphate polyacrylamide gel electrophoresis 相似文献
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Summary Cytological changes associated with the final maturation, and dehiscence of the 16-grain compound pollen (polyads) have been followed in anthers at female and male phase of flowering. InAcacia retinodes, the transition from female to male phase takes approximately 24 h. The spherical generative cell at female phase is connected with the vegetative cell plasma membrane by a junction zone. This is sited adjacent to a germinal aperture, comprising wall ingrowths and membrane labyrinths. By male phase, the generative cell has elongated into a spindle-shape, and its surface is characteristically scalloped. The membrane labyrinths, especially those at the apertures, now contain masses of coated vesicles, implicated in the transport and secretion of proteins. Two-dimensional projections indicate that the generative cell and vegetative nucleus are closely associated forming a male germ unit. 相似文献
9.
An inflatable minirhizotron system for root observations with improved soil/tube contact 总被引:3,自引:1,他引:2
Commonly used minirhizotrons consisting of a transparent tube inserted into the soil seldom attain good contact between the tube and the soil, which leads to root growth occurring in a gap rather than in the soil. A new system is described involving an inflatable flexible rubber wall, made from a modified motorcycle tube. Pressure ensures a proper tube/soil contact so that the environmental circumstances for root growth along the tube more closely correspond to those in the undisturbed soil. Before the endoscope slide is introduced into the minirhizotron for taking pictures, the inflatable tube is removed, so that there is no-often opaque-wall between the endoscope and the roots. This improves the picture quality and facilitates the analysis of root images. 相似文献
10.
Summary
Agapanthus umbelatus pollen tubes (PTs) display a number of different growth patterns when germinated in an electric field of 750 mV· mm–1. When pollen is germinated near the cathode (82.44% of orientation to the cathode side) or near the anode (55.35% of orientation to the anode), growth is oriented parallel to the applied field but when germinated at an intermediate position, there is random growth. An increase and decrease in the orientation rates as well as reversion of the polarized growth were observed when the growth conditions were systematically altered. These findings reflect the influence of different ionic currents present in the germination medium. These ionic currents induce the formation of ionic gradients, which were monitored by ion-HPLC. The individual omission of Ca2+, K+, Mg2+ and Cl– suppresses or alters the oriented growth pattern. The presence of ionic gradients is not by itself suficient to trigger the polarization of tube growth as the presence of an electric field which drives the ionic currents is essential for this to occur.Abbreviations PT
Pollen tube
- DNS
3,5-dinitro salycilic acid;
- TP
transient polarization
- HPLC
high precision liquid chroma tography
- DC
direct current 相似文献