Publications by authors named "B Knuiman"

7 Publications

Expression and localization of calreticulin in tobacco anthers and pollen tubes.

Planta 2006 May 1;223(6):1263-71. Epub 2005 Dec 1.

Department of Plant Cell Biology, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands.

The developmental expression pattern and localization of calreticulin were studied in Nicotiana tabacum L. anthers, pollen and pollen tubes. High transcript and protein levels were detected throughout anther development. Immunolocalization of calreticulin in the anthers showed particular dense label in tapetum and pollen at developmental stage 2, when the tapetum is highly active and the pollen tetrads are formed. Much lower transcript and protein levels were detected in dry and hydrated pollen and in pollen tubes. Immunofluorescence labeling of both chemically fixed and cryo-fixed and freeze-substituted pollen tubes showed the presence of calreticulin in Golgi apparatus and endoplasmic reticulum (ER). Calreticulin was seen throughout the stacks in the Golgi apparatus and in the areas with coated-Golgi vesicles but much less so in the ER. Calreticulin was not found in the secretory vesicles. A relatively intense label was occasionally seen adjacent to the wall of the tube. No significant label was observed in mitochondria, vacuoles, generative cells, cell wall or callose plugs. The present results are consistent with a role of calreticulin in Ca2+-dependent folding of secreted glycoproteins in tapetum, pollen and pollen tubes.
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http://dx.doi.org/10.1007/s00425-005-0175-yDOI Listing
May 2006

KINKY POLLEN encodes a SABRE-like protein required for tip growth in Arabidopsis and conserved among eukaryotes.

Plant J 2003 Dec;36(6):894-904

INRA, Station de Génétique et d'Amélioration des Plantes, Centre de Versailles-Grignon, 78026 Versailles Cedex, France.

In higher plants, pollen tubes and root hairs share an ancient growth process named tip growth. We have isolated three allelic Arabidopsis mutant lines showing kinky-shaped pollen tubes and, when homozygous, showing shorter and thicker root hairs. The ultrastructure of pollen tubes in these kinky pollen (kip) mutants is similar to that of the wild type; however, time-lapse studies suggest that aberrant pollen tube shape is caused by periodic growth arrests alternated with phases of tube axis reorientation. The KIP gene encodes a protein of 2587 amino acids that is predicted to be targeted to the secretory pathway. KIP mRNA was detected in all organs investigated but was most abundant in pollen and roots. KIP has putative homologues in many eukaryotes, including mammals and yeast, and is similar to the Arabidopsis SABRE gene, whose mutation causes a dwarf phenotype. The phenotype of the kip/sab double mutant suggests related functions for both genes, however, the KIP protein is mostly required for tip-growth.
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http://dx.doi.org/10.1046/j.1365-313x.2003.01933.xDOI Listing
December 2003

Characterization and localization of the transmitting tissue-specific PELPIII proteins of Nicotiana tabacum.

J Exp Bot 2003 Jan;54(380):55-63

Department of Experimental Botany, Graduate School of Experimental Plant Science, University of Nijmegen, Toernooiveld 1, 6525 ED, Nijmegen, The Netherlands.

The class III pistil-specific PELP proteins (PELPIII) of Nicotiana tabacum includes at least two members of highly soluble glycoproteins containing glucan modules that are characteristic for arabinogalactan proteins (AGPs). PELPIII accumulates in the style transmitting tissue (TT) during pistil development and, at flower anthesis, is present in the intercellular matrix (IM) of non-pollinated pistils. After pollination, PELPIII appears to be directly and completely translocated from the IM into the pollen tube callose walls, no significant accumulation was observed in the primary wall in the tip. In the spent parts of the pollen tubes these proteins become detectable against the remnants of the tube cell membrane and in the callose plugs. Different protein extraction procedures of PELPIII from pollinated tobacco pistils showed that these proteins remain in the highly soluble protein fraction and are not modified by the growing pollen tubes. These data concur with a role in IM development and pollen tube growth. In addition, the data show that the PELPIII are able to reach the cell membrane, facilitated by an already present or induced high porosity of the tube wall and an additional, yet unknown, mechanism. The differences in behaviour between the three related classes of style IM glycoproteins of Nicotiana, namely, PELPII, TTS and the 120 kDa glycoprotein, are proposed to connect more to their differences in glycosylation than to major differences in amino acid sequence.
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http://dx.doi.org/10.1093/jxb/erg002DOI Listing
January 2003

Brefeldin A effects on tobacco pollen tubes.

Eur J Cell Biol 1993 Aug;61(2):247-55

Department of Experimental Botany, University of Nijmegen, The Netherlands.

Pollen germination and pollen tube growth were clearly affected by the drug brefeldin A: both processes could be stopped completely. Notable thickening of the cell wall was not observed in non-growing pollen tubes, and plasma streaming remained vigorous in the presence of brefeldin A. Over time, the tip region became filled with a dense cytoplasm that lacked large organelles. Ultrastructural observation showed the rapid dissociation and disappearance of Golgi bodies. The concomitant appearance of vesicle-like structures attached to the endoplasmic reticulum (ER) suggests a fusion of the Golgi with the ER similar to that which happens in animal cells. Secretory vesicles disappeared from drug-treated tubes, and the tip region became filled with tubular ER. As the actions of the drug seemed to be reversible, brefeldin A may contribute substantially to research on Golgi dynamics and tip growth in pollen tubes.
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August 1993

Exocytosis in non-plasmolyzed and plasmolyzed tobacco pollen tubes : A freeze-fracture study.

Authors:
M Kroh B Knuiman

Planta 1985 Nov;166(3):287-99

Department of Botany, University of Nijmegen, Toernooiveld, NL-6525 ED, Nijmegen, The Netherlands.

Exocytosis occurring during deposition of secondary wall material was studied by freeze-fracturing ultrarapidly frozen non-plasmolyzed and plasmolyzed tobacco pollen tubes. The secondary wall of tobacco pollen tubes shows a random orientation of microfibrils. This was observed directly on fractures through the tube wall and indirectly as imprints of microfibrils on fracture faces of the plasma membrane of non-plasmolyzed tubes. About half of the plasmatic fracture faces from non-plasmolyzed and plasmolyzed pollen tubes carried hexagonal arrays of intramembraneous particles in between randomly distributed particles. Deposition of secondary wall material was often accompanied by an undulated plasma membrane and the presence of membrane-bound vesicles in invaginations of the plasma membrane, between the plasma membrane and secondary wall and-especially in plasmolyzed tubes-within the secondary wall of tube flanks and wall cap. The findings are discussed in connection with published schemes of membrane behaviour during exocytosis.
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http://dx.doi.org/10.1007/BF00401164DOI Listing
November 1985
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