scholarly journals Adaptive Responses and Ultrastructural Findings of Onobrychis germanicopolitana Hub.-Mor. & Simon (Fabaceae) Growing Naturally at Gypsum Habitats

Author(s):  
Ayşenur KAYABAŞ
Author(s):  
George Price ◽  
Lizardo Cerezo

Ultrastructural defects of ciliary structure have been known to cause recurrent sino-respiratory infection concurrent with Kartagener's syndrome. (1,2,3) These defects are also known to cause infertility in both males and females. (4) Overall, the defects are defined as the Immotile, or Dyskinetic Cilia Syndrome (DCS). Several ultrastructural findings have been described, including decreased number of cilia, multidirection orientation, fused and compound cilia, membrane blebs, excess matrix in the axoneme, missing outer tubular doublets, translocated doublets, defective radial spokes and dynein arms. A rare but noteworthy ultrastructural finding in DCS is the predominance of microvilli-like structures on the luminal surface of the respiratory epithelium. (5,6) These permanent surface modifications of the apical respiratory epithelium no longer resemble cilia but reflect the ultrastructure of stereocilia, similar to that found in the epidydimal epithelium. Like microvilli, stereocilia are devoid of microtubular ultrastructure in comparison with true cilia.


Author(s):  
S. F. Hayes ◽  
M. D. Corwin ◽  
T. G. Schwan ◽  
D. W. Dorward ◽  
W. Burgdorfer

Characterization of Borrelia burgdorferi strains by means of negative staining EM has become an integral part of many studies related to the biology of the Lyme disease organism. However, relying solely upon negative staining to compare new isolates with prototype B31 or other borreliae is often unsatisfactory. To obtain more satisfactory results, we have relied upon a correlative approach encompassing a variety EM techniques, i.e., scanning for topographical features and cryotomy, negative staining and thin sectioning to provide a more complete structural characterization of B. burgdorferi.For characterization, isolates of B. burgdorferi were cultured in BSK II media from which they were removed by low speed centrifugation. The sedimented borrelia were carefully resuspended in stabilizing buffer so as to preserve their features for scanning and negative staining. Alternatively, others were prepared for conventional thin sectioning and for cryotomy using modified procedures. For thin sectioning, the fixative described by Ito, et al.


Pathology ◽  
2001 ◽  
Vol 33 (3) ◽  
pp. 399-402 ◽  
Author(s):  
Leonardo D. Santos ◽  
Cyril S. K. C. Wong ◽  
Murray Killingsworth

2019 ◽  
Author(s):  
Joe Butler ◽  
Samuel Ngabo ◽  
Marcus Missal

Complex biological systems build up temporal expectations to facilitate adaptive responses to environmental events, in order to minimise costs associated with incorrect responses, and maximise the benefits of correct responses. In the lab, this is clearly demonstrated in tasks which show faster response times when the period between warning (S1) and target stimulus (S2) on the previous trial was short and slower when the previous trial foreperiod was long. The mechanisms driving such higher order effects in temporal preparation paradigms are still under debate, with key theories proposing that either i) the foreperiod leads to automatic modulation of the arousal system which influences responses on the subsequent trial, or ii) that exposure to a foreperiod results in the creation of a memory trace which is used to guide responses on the subsequent trial. Here we provide data which extends the evidence base for the memory accounts, by showing that previous foreperiod exposures are cumulative with reaction times shortening after repeated exposures; whilst also demonstrate that the higher order effects associated with a foreperiod remain active for several trials.


2011 ◽  
Vol 4 (2) ◽  
pp. 126-134 ◽  
Author(s):  
Hideki Matsumoto ◽  
Masanori Tomita ◽  
Kensuke Otsuka ◽  
Masanori Hatashita ◽  
Nobuyuki Hamada

2019 ◽  
Vol 12 (1) ◽  
pp. 27-49 ◽  
Author(s):  
Shahinda S.R. Alsayed ◽  
Chau C. Beh ◽  
Neil R. Foster ◽  
Alan D. Payne ◽  
Yu Yu ◽  
...  

Background:Mycolic acids (MAs) are the characteristic, integral building blocks for the mycomembrane belonging to the insidious bacterial pathogen Mycobacterium tuberculosis (M.tb). These C60-C90 long α-alkyl-β-hydroxylated fatty acids provide protection to the tubercle bacilli against the outside threats, thus allowing its survival, virulence and resistance to the current antibacterial agents. In the post-genomic era, progress has been made towards understanding the crucial enzymatic machineries involved in the biosynthesis of MAs in M.tb. However, gaps still remain in the exact role of the phosphorylation and dephosphorylation of regulatory mechanisms within these systems. To date, a total of 11 serine-threonine protein kinases (STPKs) are found in M.tb. Most enzymes implicated in the MAs synthesis were found to be phosphorylated in vitro and/or in vivo. For instance, phosphorylation of KasA, KasB, mtFabH, InhA, MabA, and FadD32 downregulated their enzymatic activity, while phosphorylation of VirS increased its enzymatic activity. These observations suggest that the kinases and phosphatases system could play a role in M.tb adaptive responses and survival mechanisms in the human host. As the mycobacterial STPKs do not share a high sequence homology to the human’s, there have been some early drug discovery efforts towards developing potent and selective inhibitors.Objective:Recent updates to the kinases and phosphatases involved in the regulation of MAs biosynthesis will be presented in this mini-review, including their known small molecule inhibitors.Conclusion:Mycobacterial kinases and phosphatases involved in the MAs regulation may serve as a useful avenue for antitubercular therapy.


Author(s):  
Néstor David Giraldo ◽  
Sandra Marcela Correa ◽  
Andrés Arbeláez ◽  
Felix L. Figueroa ◽  
Rigoberto Ríos-Estepa ◽  
...  

AbstractIn this study the metabolic responses of Botryococcus braunii were analyzed upon different inorganic carbon dosages and nutrient limitation conditions in terms of lipid and biomass productivity, as well as photosynthetic performance. The nutritional schemes evaluated included different levels of sodium bicarbonate and nitrogen and phosphorus starvation, which were contrasted against standard cultures fed with CO2. Bicarbonate was found to be an advantageous carbon source since high dosages caused a significant increase in biomass and lipid productivity, in addition to an enhanced photosynthetic quantum yield and neutral lipids abundance. This contrasts to the commonly used approach of microalgae nutrient limitation, which leads to high lipid accumulation at the expense of impaired cellular growth, causing a decline in overall lipid productivity. The lipidome analysis served to hypothesize about the influence of the nutritional context on B. braunii structural and storage lipid metabolism, besides the adaptive responses exhibited by cells that underwent nutrient stress.


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