scholarly journals A plant class V chitinase from a cycad (Cycas revoluta): Biochemical characterization, cDNA isolation, and posttranslational modification

Glycobiology ◽  
2009 ◽  
Vol 19 (12) ◽  
pp. 1452-1461 ◽  
Author(s):  
Toki Taira ◽  
Hiroko Hayashi ◽  
Yoshiko Tajiri ◽  
Shoko Onaga ◽  
Gen-ichiro Uechi ◽  
...  
2019 ◽  
Vol 73 (1) ◽  
pp. 111-132 ◽  
Author(s):  
Chelsey M. VanDrisse ◽  
Jorge C. Escalante-Semerena

Acetylation is a posttranslational modification conserved in all domains of life that is carried out by N-acetyltransferases. While acetylation can occur on Nα-amino groups, this review will focus on Nε-acetylation of lysyl residues and how the posttranslational modification changes the cellular physiology of bacteria. Up until the late 1990s, acetylation was studied in eukaryotes in the context of chromatin maintenance and gene expression. At present, bacterial protein acetylation plays a prominent role in central and secondary metabolism, virulence, transcription, and translation. Given the diversity of niches in the microbial world, it is not surprising that the targets of bacterial protein acetyltransferases are very diverse, making their biochemical characterization challenging. The paradigm for acetylation in bacteria involves the acetylation of acetyl-CoA synthetase, whose activity must be tightly regulated to maintain energy charge homeostasis. While this paradigm has provided much mechanistic detail for acetylation and deacetylation, in this review we discuss advances in the field that are changing our understanding of the physiological role of protein acetylation in bacteria.


Author(s):  
P. Dayanandan ◽  
P. B. Kaufman

A three dimensional appreciation of the guard cell morphology coupled with ultrastjuctural studies should lead to a better understanding of their still obscure dynamics of movement. We have found the SEM of great value not only in studies of the surface details of stomata but also in resolving the structures and relationships that exist between the guard and subsidiary cells. We now report the isolation and SEM studies of guard cells from nine genera of plants.Guard cells were isolated from the following plants: Psilotum nudum, four species of Equisetum, Cycas revoluta, Ceratozamia sp., Pinus sylvestris, Ephedra cochuma, Welwitschia mirabilis, Euphorbia tirucalli and Allium cepa.


Author(s):  
J. Metuzals

It has been demonstrated that the neurofibrillary tangles in biopsies of Alzheimer patients, composed of typical paired helical filaments (PHF), consist also of typical neurofilaments (NF) and 15nm wide filaments. Close structural relationships, and even continuity between NF and PHF, have been observed. In this paper, such relationships are investigated from the standpoint that the PHF are formed through posttranslational modifications of NF. To investigate the validity of the posttranslational modification hypothesis of PHF formation, we have identified in thin sections from frontal lobe biopsies of Alzheimer patients all existing conformations of NF and PHF and ordered these conformations in a hypothetical sequence. However, only experiments with animal model preparations will prove or disprove the validity of the interpretations of static structural observations made on patients. For this purpose, the results of in vitro experiments with the squid giant axon preparations are compared with those obtained from human patients. This approach is essential in discovering etiological factors of Alzheimer's disease and its early diagnosis.


Author(s):  
J. H. Resau ◽  
N. Howell ◽  
S. H. Chang

Spinach grown in Texas developed “yellow spotting” on the peripheral portions of the leaves. The exact cause of the discoloration could not be determined as there was no evidence of viral or parasitic infestation of the plants and biochemical characterization of the plants did not indicate any significant differences between the yellow and green leaf portions of the spinach. The present study was undertaken using electron microscopy (EM) to determine if a micro-nutrient deficiency was the cause for the discoloration.Green leaf spinach was collected from the field and sent by express mail to the EM laboratory. The yellow and equivalent green portions of the leaves were isolated and dried in a Denton evaporator at 10-5 Torr for 24 hrs. The leaf specimens were then examined using a JEOL 100 CX analytical microscope. TEM specimens were prepared according to the methods of Trump et al.


Author(s):  
Jason R. Swedlow ◽  
Neil Osheroff ◽  
Tim Karr ◽  
John W. Sedat ◽  
David A. Agard

DNA topoisomerase II is an ATP-dependent double-stranded DNA strand-passing enzyme that is necessary for full condensation of chromosomes and for complete segregation of sister chromatids at mitosis in vivo and in vitro. Biochemical characterization of chromosomes or nuclei after extraction with high-salt or detergents and DNAse treatment showed that topoisomerase II was a major component of this remnant, termed the chromosome scaffold. The scaffold has been hypothesized to be the structural backbone of the chromosome, so the localization of topoisomerase II to die scaffold suggested that the enzyme might play a structural role in the chromosome. However, topoisomerase II has not been studied in nuclei or chromosomes in vivo. We have monitored the chromosomal distribution of topoisomerase II in vivo during mitosis in the Drosophila embryo. This embryo forms a multi-nucleated syncytial blastoderm early in its developmental cycle. During this time, the embryonic nuclei synchronously progress through 13 mitotic cycles, so this is an ideal system to follow nuclear and chromosomal dynamics.


2017 ◽  
Vol 6 (1) ◽  
pp. 296
Author(s):  
Rosmida Rosmida

The background of this study is the lack of IPS students' learning outcomes, from 22 students only 36.36% or 8 students who managed to achieve a minimum completeness criteria (KKM) established school with a class average value of 61.75. Based on this the researchers conducted a classroom action research with the aim to improve learning outcomes IPS students through the application of methods of discussion. This research is a class act, who performed a total of two cycles consisting of two meetings, the data of this study focuses on the data increase learning outcomes and increase student mastery learning outcomes IPS. The study states that the results of social studies students has increased in each cycle, the initial data is the number of students who completed 8 students (36.36%) with an average of learning outcomes at 61.75. In the first cycle has increased the number of students who completed up to 16 students (72.73%) with an average of learning outcomes at 73.90, and the second cycle the number of students who pass the increase to 22 students (100.00%) with a mean -rata learning outcomes at 87.75. Based on these results it can be concluded that the application of the method of discussion to improve learning outcomes IPS students of class V A SD Negeri 004 Tembilahan Kecamatan Tembilahan.


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