Effect of Brefeldin A on cell-wall polysaccharide production in the red microalga Porphyridium sp. (Rhodophyta) through its effect on the Golgi apparatus

2009 ◽  
Vol 21 (6) ◽  
pp. 707-717 ◽  
Author(s):  
Marina Keidan ◽  
Michael Friedlander ◽  
Shoshana (Malis) Arad

1999 ◽  
Vol 37 (1) ◽  
pp. 33-40 ◽  
Author(s):  
Gabriella Piro ◽  
Anna Montefusco ◽  
Daniela Pacoda ◽  
Giuseppe Dalessandro


1998 ◽  
Vol 46 (2) ◽  
pp. 147-153 ◽  
Author(s):  
Arava(Katz) Cohen ◽  
Shoshana(Malis) Arad

This research forms part of our ongoing study to elucidate cell wall biosynthesis in red microalgae. Cell wall formation during the cell cycle of the red microalga Rhodella reticulata was followed in cultures synchronized by a regime of dark (12 h), light (12 h), and dilution of the culture thereafter to 1–1.5 × 106cells/ml. Under these conditions, cell number doubled after 24 h, DNA replication occurred between the 6th and 12th hours, and cell division took place between the 8th and 14th hours of the cycle. Cell wall constituents increased only during the light hours, peaking as follows: sulfur at the 2nd hour, protein at the 11th hour, and the various sugars (each at different times) between the 6th and 12th hours of the cycle. Since xylose predominated from the beginning of the cycle, it appears that this sugar was produced first and formed the basic polymer skeleton to which other sugars were attached. Two polymers were produced during the cycle, their sizes (as determined by gel filtration) being 0.5 × 106 and 1.15 × 106 daltons. It thus seems likely that the smaller 0.5 × 106 dalton polymers are produced inside the cells and then excreted into the medium, where they are further polymerized to produce the final-size polymers. The herbicide 2,6-dichlorobenzonitrile (DCB), an inhibitor of cellulose biosynthesis, was previously found to inhibit cell wall formation in red microalgae. When it was added to the cultures at the beginning or at the end of the cycle, no inhibition in cell division was detected, but when it was added at the 8th hour, cell division was significantly inhibited (38%), resulting in an increase in mean cell volume. Addition of DCB did not affect DNA replication or cell wall polysaccharide content or composition, as measured after 24 h of the cycle. It seems that DCB affects an inhibitory phase in cell division and that this inhibition is not necessarily coupled with its inhibition of formation of the sulfated polysaccharide.



Phycologia ◽  
1994 ◽  
Vol 33 (3) ◽  
pp. 158-162 ◽  
Author(s):  
S. (Malis) Arad ◽  
R. Kolani ◽  
B. Simon-Berkovitch ◽  
A. Sivan




1993 ◽  
Vol 2 (7) ◽  
pp. 1106-1113 ◽  
Author(s):  
D. R. Rose ◽  
M. Przybylska ◽  
R. J. To ◽  
C. S. Kayden ◽  
E. Vorberg ◽  
...  


2021 ◽  
Vol 22 (6) ◽  
pp. 3077
Author(s):  
Zhenzhen Hao ◽  
Xiaolu Wang ◽  
Haomeng Yang ◽  
Tao Tu ◽  
Jie Zhang ◽  
...  

Plant cell wall polysaccharides (PCWP) are abundantly present in the food of humans and feed of livestock. Mammalians by themselves cannot degrade PCWP but rather depend on microbes resident in the gut intestine for deconstruction. The dominant Bacteroidetes in the gut microbial community are such bacteria with PCWP-degrading ability. The polysaccharide utilization systems (PUL) responsible for PCWP degradation and utilization are a prominent feature of Bacteroidetes. In recent years, there have been tremendous efforts in elucidating how PULs assist Bacteroidetes to assimilate carbon and acquire energy from PCWP. Here, we will review the PUL-mediated plant cell wall polysaccharides utilization in the gut Bacteroidetes focusing on cellulose, xylan, mannan, and pectin utilization and discuss how the mechanisms can be exploited to modulate the gut microbiota.



2005 ◽  
Vol 391 (2) ◽  
pp. 409-415 ◽  
Author(s):  
Anna Kärkönen ◽  
Alain Murigneux ◽  
Jean-Pierre Martinant ◽  
Elodie Pepey ◽  
Christophe Tatout ◽  
...  

UDPGDH (UDP-D-glucose dehydrogenase) oxidizes UDP-Glc (UDP-D-glucose) to UDP-GlcA (UDP-D-glucuronate), the precursor of UDP-D-xylose and UDP-L-arabinose, major cell wall polysaccharide precursors. Maize (Zea mays L.) has at least two putative UDPGDH genes (A and B), according to sequence similarity to a soya bean UDPGDH gene. The predicted maize amino acid sequences have 95% similarity to that of soya bean. Maize mutants with a Mu-element insertion in UDPGDH-A or UDPGDH-B were isolated (udpgdh-A1 and udpgdh-B1 respectively) and studied for changes in wall polysaccharide biosynthesis. The udpgdh-A1 and udpgdh-B1 homozygotes showed no visible phenotype but exhibited 90 and 60–70% less UDPGDH activity respectively than wild-types in a radiochemical assay with 30 μM UDP-glucose. Ethanol dehydrogenase (ADH) activity varied independently of UDPGDH activity, supporting the hypothesis that ADH and UDPGDH activities are due to different enzymes in maize. When extracts from wild-types and udpgdh-A1 homozygotes were assayed with increasing concentrations of UDP-Glc, at least two isoforms of UDPGDH were detected, having Km values of approx. 380 and 950 μM for UDP-Glc. Leaf and stem non-cellulosic polysaccharides had lower Ara/Gal and Xyl/Gal ratios in udpgdh-A1 homozygotes than in wild-types, whereas udpgdh-B1 homozygotes exhibited more variability among individual plants, suggesting that UDPGDH-A activity has a more important role than UDPGDH-B in UDP-GlcA synthesis. The fact that mutation of a UDPGDH gene interferes with polysaccharide synthesis suggests a greater importance for the sugar nucleotide oxidation pathway than for the myo-inositol pathway in UDP-GlcA biosynthesis during post-germinative growth of maize.



2004 ◽  
Vol 286 (5) ◽  
pp. E704-E710 ◽  
Author(s):  
Hesham A. W. Tawfeek ◽  
Abdul B. Abou-Samra

Our previous studies demonstrated that a green fluorescent protein-tagged parathyroid hormone (PTH)/PTH-related peptide (PTHrP) receptor stably expressed in LLCPK-1 cells undergoes agonist-dependent internalization into clathrin-coated pits. The subcellular localization of the internalized PTH/PTHrP receptor is not known. In the present study, we explored the intracellular pathways of the internalized PTH/PTHrP receptor. Using immunofluorescence and confocal microscopy, we show that the internalized receptors localize at a juxtanuclear compartment identified as the Golgi apparatus. The receptors do not colocalize with lysosomes. Furthermore, whereas the internalized receptors exhibit rapid recycling, treatment with proton pump inhibitors (bafilomycin-A1 and concanamycin A) or brefeldin A, Golgi disrupting agents, reduces PTH/PTHrP receptor recycling. Together, these data indicate an important role for the vacuolar-type hydrogen-ATPase and the Golgi apparatus in postendocytic PTH/PTHrP receptor recovery.



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