Selective Inhibition of Cleavage in Different Regions of the Frog Egg by Sulphydryl Inhibitors

Development ◽  
1956 ◽  
Vol 4 (1) ◽  
pp. 73-92
Author(s):  
Lucena J. Barth
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Total Nitrogen ◽  
Selective Inhibition ◽  
Inorganic Materials ◽  
Crescent Formation ◽  
Animal Pole ◽  
Grey Crescent ◽  
Histochemical Methods ◽  
Small Spot

That the materials for protein synthesis in the frog egg must come from yolk is indicated by the constancy of total nitrogen during development (Gregg & Ballentine, 1946) and the fact that the egg can develop with no outside source of organic or inorganic materials. When and where in the developing egg new proteins arise, and what are the mechanisms which control the rate and direct the specificity of such syntheses, are problems which are beginning to occupy increasing numbers investigators using several methods of attack—immunological, enzymological, electrophoretic, and incorporation of labelled amino acids, for example. Brachet (1940), using histochemical methods, described a change in the distribution of sulphydryl proteins coincident with grey crescent formation. In the newly-laid egg of Triton or Pleurodeles Brachet found the sulphydryl proteins to be restricted to a small spot centred about the maturation figure near the animal pole. This picture changed during the first few hours after fertilization.

Heat-shock-induced grey crescent formation in axolotl eggs and oocytes: the role of gravity

Development ◽  
1987 ◽  
Vol 100 (4) ◽  
pp. 599-609
Author(s):  
J.-C. Beetschen ◽  
J. Gautier
Keyword(s):  
Protein Synthesis ◽  
Heat Shock ◽  
Synergistic Action ◽  
Nuclear Factor ◽  
Crescent Formation ◽  
Animal Pole ◽  
Grey Crescent ◽  
Cytoskeletal Structure

Axolotl eggs were heat shocked (36.8°C, 10min) inside their jelly layers. Heat shock (HS) was shown to induce the precocious appearance of a grey crescent (GC) in a number of eggs immediately after fertilization (Benford & Namenwirth, 1974). It was also demonstrated that this phenomenon occurs in fertilized or artificially activated eggs only when they are shocked within 11/2h after spawning. The GC forms still later in heated unfertilized, nonactivated eggs. The role of the jelly layers is considered to be mechanical: a proportion of eggs is maintained in a tilted position until the egg is able to orient animal pole upwards under the influence of gravity as a late consequence of activation. The jelly layers are not essential if the eggs are artificially tilted or rotated during HS. GC formation can also be induced in in vitro maturing oocytes, provided they are tilted during HS. Gravity thus plays an essential role in the cytoplasmic rearrangements leading to HS-induced GC formation. Our results indicate a synergistic action between heat and gravity in this process. The cytological appearance of the GC formed in those experiments is that of a ‘Born's crescent’ with a conspicuous ‘vitelline wall’ (Pasteels, 1964). When oocytes are enucleated before maturation, HS has no effect on GC formation. A nuclear factor is therefore essential, as has been demonstrated in early GC formation induced by inhibitors of protein synthesis. Finally, incorporation of amino acids into oocyte proteins appears to be rapidly inhibited by HS (from 5 min). However, we cannot conclude that GC formation is in fact triggered by inhibition of protein synthesis. It is also likely that HS disrupts cytoskeletal structure, hence facilitating cytoplasmic rearrangements. Nevertheless, these results are in agreement with the scheme we recently proposed for GC formation in the rotated axolotl oocyte (Gautier & Beetschen, 1985).

scholarly journals The inhibition of bacterial growth by hypochlorous acid. Possible role in the bactericidal activity of phagocytes

1988 ◽  
Vol 254 (3) ◽  
pp. 685-692 ◽  
Author(s):  
S M McKenna ◽  
K J A Davies
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Cell Division ◽  
Protein Degradation ◽  
Bacterial Growth ◽  
Colony Formation ◽  
Hypochlorous Acid ◽  
Selective Inhibition ◽  
Membrane Disruption ◽  
Bacterial Membrane

The ‘respiratory burst’ of phagocytes such as neutrophils generates superoxide which forms H2O2 by dismutation. H2O2 and Cl- ions serve as substrates for the enzyme myeloperoxidase to generate hypochlorous acid (HOCl). HOCl is thought to play an important role in bacterial killing, but its mechanism of action is not well characterized. Furthermore, although many studies in vitro have shown HOCl to be a damaging oxidant with little or no specificity (particularly at high concentrations), bacteria which have been ingested by phagocytes appear to experience a rapid and selective inhibition of cell division. Bacterial membrane disruption, protein degradation, and inhibition of protein synthesis, do not seem to occur in the early phases of phagocyte action. We have now found that low concentrations of HOCl exert a rapid and selective inhibition of bacterial growth and cell division, which can be blocked by taurine or amino acids. Only 20 microM-HOCl was required for 50% inhibition of bacterial growth (5 x 10(8) Escherichia coli/ml), and 50 microM-HOCl completely inhibited cell division (colony formation). These effects were apparent within 5 min of HOCl exposure, and were not reversed by extensive washings. DNA synthesis (incorporation of [3H]-thymidine) was significantly affected by even a 1 min exposure to 50 microM-HOCl, and decreased by as much as 96% after 5 min. In contrast, bacterial membrane disruption and extensive protein degradation/fragmentation (release of acid-soluble counts from [3H]leucine-labelled cells) were not observed at concentrations below 5 mM-HOCl. Protein synthesis (incorporation of [3H]leucine) was only inhibited by 10-30% following 5 min exposure to 50 microM-HOCl, although longer exposure produced more marked reductions (80% after 30 min). Neutrophils deficient in myeloperoxidase cannot convert H2O2 to HOCl, yet can kill bacteria. We have found that H2O2 is only 6% as effective as HOCl in inhibiting E. coli growth and cell division (0.34 mM-H2O2 required for 50% inhibition of colony formation), and taurine or amino acids do not block this effect. Our results are consistent with a rapid and selective inhibition of bacterial cell division by HOCl in phagocytes. H2O2 may substitute for HOCl in myeloperoxidase deficiency, but by a different mechanism and at a greater metabolic cost.

Homochirality as the Signature of Extra-Terrestrial Life

1997 ◽  
Vol 161 ◽  
pp. 505-510
Author(s):  
Alexandra J. MacDermott ◽  
Laurence D. Barron ◽  
Andrè Brack ◽  
Thomas Buhse ◽  
John R. Cronin ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Optical Rotation ◽  
Physical Origin ◽  
Natural Choice ◽  
Rosetta Mission ◽  
Terrestrial Life ◽  
Subsurface Layers ◽  
Solar System Bodies ◽  
Origin Of Homochirality

AbstractThe most characteristic hallmark of life is its homochirality: all biomolecules are usually of one hand, e.g. on Earth life uses only L-amino acids for protein synthesis and not their D mirror images. We therefore suggest that a search for extra-terrestrial life can be approached as a Search for Extra- Terrestrial Homochirality (SETH). The natural choice for a SETH instrument is optical rotation, and we describe a novel miniaturized space polarimeter, called the SETH Cigar, which could be used to detect optical rotation as the homochiral signature of life on other planets. Moving parts are avoided by replacing the normal rotating polarizer by multiple fixed polarizers at different angles as in the eye of the bee. We believe that homochirality may be found in the subsurface layers on Mars as a relic of extinct life, and on other solar system bodies as a sign of advanced pre-biotic chemistry. We discuss the chiral GC-MS planned for the Roland lander of the Rosetta mission to a comet and conclude with theories of the physical origin of homochirality.

scholarly journals Destruxin A Interacts with Aminoacyl tRNA Synthases in Bombyx mori

2021 ◽  
Vol 7 (8) ◽  
pp. 593
Author(s):  
Jingjing Wang ◽  
Alexander Berestetskiy ◽  
Qiongbo Hu
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Bombyx Mori ◽  
Metarhizium Anisopliae ◽  
Free Amino ◽  
Molecular Target ◽  
Trna Synthetases ◽  
Interaction Mode ◽  
Aminoacyl Trna Synthetases ◽  
Wide Range

Destruxin A (DA), a hexa-cyclodepsipeptidic mycotoxin produced by the entomopathogenic fungus Metarhizium anisopliae, exhibits insecticidal activities in a wide range of pests and is known as an innate immunity inhibitor. However, its mechanism of action requires further investigation. In this research, the interactions of DA with the six aminoacyl tRNA synthetases (ARSs) of Bombyx mori, BmAlaRS, BmCysRS, BmMetRS, BmValRS, BmIleRS, and BmGluProRS, were analyzed. The six ARSs were expressed and purified. The BLI (biolayer interferometry) results indicated that DA binds these ARSs with the affinity indices (KD) of 10−4 to 10−5 M. The molecular docking suggested a similar interaction mode of DA with ARSs, whereby DA settled into a pocket through hydrogen bonds with Asn, Arg, His, Lys, and Tyr of ARSs. Furthermore, DA treatments decreased the contents of soluble protein and free amino acids in Bm12 cells, which suggested that DA impedes protein synthesis. Lastly, the ARSs in Bm12 cells were all downregulated by DA stress. This study sheds light on exploring and answering the molecular target of DA against target insects.

scholarly journals 146 Prematurity Blunts the Protein Synthetic Response of Skeletal Muscle to Insulin and Amino Acids

2020 ◽  
Vol 98 (Supplement_4) ◽  
pp. 118-119
Author(s):  
Teresa A Davis ◽  
Marko Rudar ◽  
Jane Naberhuis ◽  
Agus Suryawan ◽  
Marta Fiorotto
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Body Weight Gain ◽  
Human Infant ◽  
Long Term Effects ◽  
Plasma Insulin Concentration ◽  
Akt Phosphorylation ◽  
Relative Body Weight

Abstract Livestock animals are important dual-purpose models that benefit both agricultural and biomedical research. The neonatal pig is an appropriate model for the human infant to assess long-term effects of early life nutrition on growth and metabolic outcomes. Previously we have demonstrated that prematurity blunts the feeding-induced stimulation of translation initiation and protein synthesis in skeletal muscle of neonatal pigs. The objective of this study was to determine whether reduced sensitivity to insulin and/or amino acids drives this blunted response. Pigs were delivered by caesarean section at preterm (PT, 103 d gestation) or at term (T, 112 d gestation) and fed parenterally for 4 d. On day 4, pigs were subject to euinsulinemic-euaminoacidemic-euglycemic (FAST), hyperinsulinemic-euaminoacidemic-euglycemic (INS), or euinsulinemic-hyperaminoacidemic-euglycemic (AA) clamps for 120 min, yielding six treatments: PT-FAST (n = 7), PT-INS (n = 9), PT-AA (n = 9), T-FAST (n = 8), T-INS (n = 9), and T-AA (n = 9). A flooding dose of L-[4-3H]Phe was injected into pigs 30 min before euthanasia. Birth weight and relative body weight gain were lower in PT than T pigs (P < 0.001). Plasma insulin concentration was increased from ~3 to ~100 µU/mL in INS compared to FAST and AA pigs (P < 0.001); plasma BCAA concentration was increased from ~250 to ~1,000 µmol/L in AA compared to FAST and INS pigs (P < 0.001). Despite achieving similar insulin and amino acid levels, longissimus dorsi AKT phosphorylation, mechanistic target of rapamycin (mTOR)·Rheb abundance, mTOR activation, and protein synthesis were lower in PT-INS than T-INS pigs (Table 1). Although amino-acid induced dissociation of Sestrin2 from GATOR2 was not affected by prematurity, mTOR·RagA abundance, mTOR·RagC abundance, mTOR activation, and protein synthesis were lower in PT-AA than T-AA pigs. The impaired capacity of premature skeletal muscle to respond to insulin or amino acids and promote protein synthesis likely contributes to reduced lean mass accretion. Research was supported by NIH and USDA.

scholarly journals Effect of long-term refeeding on protein metabolism in patients with cirrhosis of the liver

1997 ◽  
Vol 77 (2) ◽  
pp. 197-212 ◽  
Author(s):  
Jens Kondrup ◽  
Klaus Nielsen ◽  
Anders Juul
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Protein Degradation ◽  
Protein Metabolism ◽  
Cirrhosis Of The Liver ◽  
N Balance ◽  
Whole Body ◽  
Protein Requirement ◽  
Protein Utilization ◽  
Igf I

Patients with cirrhosis of the liver require an increased amount of protein to achieve N balance. However, the utilization of protein with increased protein intake, i.e. the slope from regression analysis of N balance v. intake, is highly efficient (Nielsen et al. 1995). In the present study, protein requirement and protein utilization were investigated further by measuring protein synthesis and degradation. In two separate studies, five or six patients with cirrhosis of the liver were refed on a balanced diet for an average of 2 or 4 weeks. Protein and energy intakes were doubled in both studies. Initial and final whole-body protein metabolism was measured in the fed state by primed continous [15N]glycine infusion. Refeeding caused a statistically significant increase of about 30% in protein synthesis in both studies while protein degradation was only slightly affected. The increase in protein synthesis was associated with significant increases in plasma concentrations of total amino acids (25%), leucine (58%), isoleucine (82%), valine (72%), proline (48%) and triiodothyronine (27%) while insulin, growth hormone, insulin-like growth factor (IGF)-I and IGF-binding protein-3 were not changed significantly. The results indicate that the efficient protein utilization is due to increased protein synthesis, rather than decreased protein degradation, and suggest that increases in plasma amino acids may be responsible for the increased protein synthesis. A comparison of the patients who had a normal protein requirement with the patients who had an increased protein requirement suggests that the increased protein requirement is due to a primary increase in protein degradation. It is speculated that this is due to low levels of IGF-I secondary to impaired liver function, since initial plasma concentration of IGF-I was about 25% of control values and remained low during refeeding.

scholarly journals Exercise, Amino Acids, and Aging in the Control of Human Muscle Protein Synthesis

2011 ◽  
Vol 43 (12) ◽  
pp. 2249-2258 ◽  
Author(s):  
DILLON K. WALKER ◽  
JARED M. DICKINSON ◽  
KYLE L. TIMMERMAN ◽  
MICAH J. DRUMMOND ◽  
PAUL T. REIDY ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Human Muscle
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