scholarly journals Digestive Constraints and Nutrient Hydrolysis in Nestlings of Two Flamingo Species

The Condor ◽  
2001 ◽  
Vol 103 (2) ◽  
pp. 396-399 ◽  
Author(s):  
Pablo Sabat ◽  
F. Fernando Novoa ◽  
Mario Parada
Keyword(s):  
Small Intestine ◽  
Chemical Composition ◽  
Enzymatic Activity ◽  
Aminopeptidase N ◽  
Dietary Composition ◽  
Activity Levels ◽  
Growth And Survival ◽  
Maltase Activity ◽  
Low Activity

Abstract In vertebrates, enzymatic activity levels in the small intestine are correlated with dietary composition. We examined enzymatic activity levels in juvenile specimens of two flamingo species, Phoenicoparrus andinus and Phoenicoparrus jamesi. Both species feed their chicks with esophageal secretions. Based on the chemical composition of these secretions in flamingoes, we predicted low activity levels of disaccharidases and higher activities of aminopeptidase-N and esterase. As predicted, sucrase was absent in P. andinus, and its activity was low in P. jamesi. Esterase and aminopeptidase-N activities were relatively high. Low maltase activity suggested the presence of carbohydrates in esophageal secretions. Digestive features can have consequences on the growth and survival of chicks. Hence the data presented here may be relevant to the maintenance and reproduction of wild and captive endangered flamingoes.

scholarly journals Telomerase RNA Template Mutations Reveal Sequence-Specific Requirements for the Activation and Repression of Telomerase Action at Telomeres

2000 ◽  
Vol 20 (8) ◽  
pp. 2941-2948 ◽  
Author(s):  
John C. Prescott ◽  
Elizabeth H. Blackburn
Keyword(s):  
Enzymatic Activity ◽  
Activity Levels ◽  
Telomeric Dna ◽  
Telomere Shortening ◽  
Telomere Elongation ◽  
Telomere Binding Protein ◽  
Telomere Function ◽  
Double Base ◽  
Telomere Lengthening

ABSTRACT Telomeric DNA is maintained within a length range characteristic of an organism or cell type. Significant deviations outside this range are associated with altered telomere function. The yeast telomere-binding protein Rap1p negatively regulates telomere length. Telomere elongation is responsive to both the number of Rap1p molecules bound to a telomere and the Rap1p-centered DNA-protein complex at the extreme telomeric end. Previously, we showed that a specific trinucleotide substitution in the Saccharomyces cerevisiae telomerase gene (TLC1) RNA template abolished the enzymatic activity of telomerase, causing the same cell senescence and telomere shortening phenotypes as a complete tlc1 deletion. Here we analyze effects of six single- and double-base changes within these same three positions. All six mutant telomerases had in vitro enzymatic activity levels similar to the wild-type levels. The base changes predicted from the mutations all disrupted Rap1p binding in vitro to the corresponding duplex DNAs. However, they caused two classes of effects on telomere homeostasis: (i) rapid, RAD52-independent telomere lengthening and poor length regulation, whose severity correlated with the decrease in in vitro Rap1p binding affinity (this is consistent with loss of negative regulation of telomerase action at these telomeres; and (ii) telomere shortening that, depending on the template mutation, either established a new short telomere set length with normal cell growth or was progressive and led to cellular senescence. Hence, disrupting Rap1p binding at the telomeric terminus is not sufficient to deregulate telomere elongation. This provides further evidence that both positive and negativecis-acting regulators of telomerase act at telomeres.

scholarly journals Structural Elucidation and Cytotoxicity of a New 17-Membered Ring Lactone from Algerian Eryngium campestre

Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3250 ◽  
Author(s):  
Ali Medbouhi ◽  
Aura Tintaru ◽  
Claire Beaufay ◽  
Jean-Valère Naubron ◽  
Nassim Djabou ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Trypanosoma Brucei ◽  
Crude Extract ◽  
Membered Ring ◽  
Leishmania Mexicana ◽  
Similar Concentration ◽  
Trypanosoma Brucei Brucei ◽  
Aerial Parts ◽  
Germacrene D ◽  
Low Activity

The chemical composition of a hexanic extract of Eryngium campestre, obtained from its aerial parts, was investigated by GC-FID, GC/MS, HRMS, NMR and VCD analyses. The main compounds were germacrene D (23.6%), eudesma-4(15)-7-dien-1-β-ol (8.2%) and falcarindiol (9.4%), which are associated with a new uncommon and naturally found 17-membered ring lactone. This 17-membered ring features conjugated acetylenic bonds, named campestrolide (23.0%). The crude extract showed moderate antitrypanosomal (Trypanosoma brucei brucei), antileishmanial (Leishmania mexicana mexicana) and anticancer (cancerous macrophage-like murine cells) activities, and also displayed cytotoxicity, (human normal fibroblasts) in similar concentration ranges (IC50 = 3.0, 3.9, 4.0 and 4.4 µg/mL respectively). Likewise, campestrolide displayed low activity on all tested cells (IC50: 12.5–19.5 µM) except on Trypanosoma, on which it was very active and moderately selective (IC50 = 2.2 µM. SI= 8.9). In conclusion, the new compound that has been described, displaying a singular structure, possesses interesting antitrypanosomal activity that should be further investigated and improved.

scholarly journals Functional cross-talk between allosteric effects of activating and inhibiting ligands underlies PKM2 regulation

2018 ◽  
Author(s):  
Jamie A. Macpherson ◽  
Alina Theisen ◽  
Laura Masino ◽  
Louise Fets ◽  
Paul C. Driscoll ◽  
...  
Keyword(s):  
Enzymatic Activity ◽  
High Activity ◽  
Pyruvate Kinase ◽  
Cross Talk ◽  
Glycolytic Enzyme ◽  
Computational Framework ◽  
Allosteric Inhibitor ◽  
Fructose 1,6 Bisphosphate ◽  
Low Activity

ABSTRACTAllosteric regulation is central to the role of the glycolytic enzyme pyruvate kinase M2 (PKM2) in cellular metabolism. Multiple activating and inhibitory allosteric ligands regulate PKM2 activity by controlling the equilibrium between high activity tetramers and low activity dimers and monomers. However, it remains elusive how allosteric inputs upon simultaneous binding of different ligands are integrated to regulate PKM2 activity. Here, we show that, in the presence of the allosteric inhibitor L-phenylalanine (Phe), the activator fructose 1,6-bisphosphate (FBP) can induce PKM2 tetramerisation, but fails to maximally increase enzymatic activity. Guided by a new computational framework we developed to identify residues that mediate FBP-induced allostery, we generated two PKM2 mutants, A327S and C358A, in which activation by FBP remains intact but cannot be attenuated by Phe. Our findings demonstrate a role for residues involved in FBP-induced allostery in enabling the integration of allosteric input from Phe and reveal a mechanism that underlies the co-ordinate regulation of PKM2 activity by multiple allosteric ligands.

Effects of Hypoxia on the Development of Intestinal Enzymes in Neonatal and Juvenile Rats

2003 ◽  
Vol 228 (6) ◽  
pp. 717-723 ◽  
Author(s):  
Ping C. Lee ◽  
Mark Struve ◽  
Hershel Raff
Keyword(s):  
Body Weight ◽  
Small Intestine ◽  
Hypoxic Exposure ◽  
Neonatal Rats ◽  
Juvenile Rats ◽  
Intestinal Enzymes ◽  
Jejunal Segment ◽  
Maltase Activity ◽  
Small Intestinal ◽  
Delayed Maturation

Hypoxia in the neonate is known to alter the activity of hepatic and pancreatic enzymes involved in lipid and carbohydrate metabolism. The purpose of this study was to evaluate the effect of neonatal hypoxia on the activity of intestinal enzymes, and to determine whether the administration of glucocorticoids to neonates can mimic the effects of hypoxia. Hypoxia in neonatal rats (0–7 days) increased protein content, and lactase and maltase activity in the duodenal and the jejunal segments of the small intestine compared with normoxic controls. Hypoxia in juvenile rats (28–35 days) did not change these enzymes. Two weeks after returning hypoxic (0–7 days) pups to normoxia, their body weight remained lower than the age-matched controls. In the group recovering from hypoxia, sucrase, maltase, and leucine aminopeptidase activities were lower in the duodenal and the jejunal segment. Compared with controls, LDH activity was lower only in the jejunal intestine in the group recovering from hypoxia. All enzyme activities returned to control levels 3 weeks after recovery. Neonatal rats treated with dexamethasone had a decrease in body weight, but increases in sucrase and maltase activity in both the duodenal and the jejunal segment. Hypoxia in newborn rats caused a delayed maturation of small intestinal enzymes. Increases in serum glucocorticoids after hypoxic exposure probably do not play a major role in the delayed maturation of the disaccharidase activity in the small intestine.

scholarly journals High-Efficiency Production of Radiopharmaceuticals via Droplet Radiochemistry: A Review of Recent Progress

2020 ◽  
Vol 19 ◽  
pp. 153601212097309
Author(s):  
Jia Wang ◽  
R. Michael van Dam
Keyword(s):  
High Efficiency ◽  
State Of The Art ◽  
System Size ◽  
Scaling Up ◽  
Activity Levels ◽  
Synthesis Time ◽  
Molar Activity ◽  
Reagent Consumption ◽  
Prosthetic Groups ◽  
Low Activity

New platforms are enabling radiochemistry to be carried out in tiny, microliter-scale volumes, and this capability has enormous benefits for the production of radiopharmaceuticals. These droplet-based technologies can achieve comparable or better yields compared to conventional methods, but with vastly reduced reagent consumption, shorter synthesis time, higher molar activity (even for low activity batches), faster purification, and ultra-compact system size. We review here the state of the art of this emerging direction, summarize the radiotracers and prosthetic groups that have been synthesized in droplet format, describe recent achievements in scaling up activity levels, and discuss advantages and limitations and the future outlook of these innovative devices.

scholarly journals Ambulatory Physical Activity Performance in Youth With Cerebral Palsy and Youth Who Are Developing Typically

2007 ◽  
Vol 87 (3) ◽  
pp. 248-257 ◽  
Author(s):  
Kristie F Bjornson ◽  
Basia Belza ◽  
Deborah Kartin ◽  
Rebecca Logsdon ◽  
John F McLaughlin
Keyword(s):  
Cerebral Palsy ◽  
Activity Levels ◽  
Ambulatory Activity ◽  
Cross Sectional ◽  
Walking Activity ◽  
Activity Performance ◽  
Cross Sectional Design ◽  
Low Activity ◽  
Gmfcs Level ◽  
Daily Total

Background and Purpose Assessment of walking activity in youth with cerebral palsy (CP) has traditionally been “capacity-based.” The purpose of this study was to describe the day-to-day ambulatory activity “performance” of youth with CP compared with youth who were developing typically. Subjects Eighty-one youth with CP, aged 10 to 13 years, who were categorized as being in Gross Motor Function Classification System (GMFCS) levels I to III and 30 age-matched youth who were developing typically were recruited. Methods Using a cross-sectional design, participants wore the StepWatch monitor for 7 days while documenting average daily total step counts, percentage of time they were active, ratio of medium to low activity levels, and percentage of time at high activity levels. Results The youth with CP demonstrated significantly lower levels of all outcomes than the comparison group. Discussion and Conclusion Daily walking activity and variability decreased as functional walking level (GMFCS level) decreased. Ambulatory activity performance within the context of the daily life for youth with CP appears valid and feasible as an outcome for mobility interventions in CP.

At-motif binding factor 1-A (Atbfi-A) negatively regulates transcription of the sucrase-isomaltase (SI) and aminopeptidase N (APN) genes in the crypt-villus axis of small intestine

2000 ◽  
Vol 118 (4) ◽  
pp. A591
Author(s):  
Hiromi Kataoka ◽  
Takashi Joh ◽  
Yoshifumi Yokoyama ◽  
Yutaka Miura ◽  
Taiji Kato ◽  
...  
Keyword(s):  
Small Intestine ◽  
Aminopeptidase N ◽  
Binding Factor
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