scholarly journals D-aspartic acid is implicated in the control of testosterone production by the vertebrate gonad. Studies on the female green frog, Rana esculenta

1998 ◽  
Vol 157 (2) ◽  
pp. 199-207 ◽  
Author(s):  
MM Di Fiore ◽  
L Assisi ◽  
V Botte ◽  
A D'Aniello
Keyword(s):  
Amino Acid ◽  
Aspartic Acid ◽  
Rana Esculenta ◽  
Ovarian Follicles ◽  
Sexual Cycle ◽  
Green Frog ◽  
Amphibian Species ◽  
Testosterone Production ◽  
Androgen Synthesis

In the present study we report the occurrence of D-aspartic acid (D-Asp) in the ovary of the green frog Rana esculenta and its putative involvement in testosterone production by the gonad. In the ovary, D-Asp concentrations undergo significant variations during the main phases of the sexual cycle. In spawning females (March), its concentration was low (2.5 +/- 1.1 nmol/g ovary) and during the post-reproductive period (June) it increased and reached its peak level (58.0 +/- 10.1 nmol/g) in October. In that month, vitellogenesis occurs in a new set of ovarian follicles and continues until the next spring. The concentrations of D-Asp in the ovary and of testosterone in the ovary and in the plasma were inversely correlated during the reproductive cycle: when endogenous D-Asp was low (March), testosterone was high (36.9 +/- 4.8 ng/g ovary; 23.1 +/- 2.76 ng/ml plasma) and, in contrast, when the D-Asp concentration was high (October), the testosterone concentration was low (0.86 +/- 0.21 ng/g ovary and 5.0 +/- 1.3 ng/ml plasma). In vivo experiments, consisting of injection of D-Asp (2.0 mumol/g body weight) into the dorsal lymphatic sac of adult female frogs, demonstrated that this amino acid accumulates significantly in the ovary. After 3 h, moreover, it caused a decrease in testosterone level in the plasma of about 80%. This inhibition was reversible: within 18 h after the amino acid injection, as the D-Asp concentration in the ovary decreased, the testosterone titre was restored in both ovary and plasma. In vitro experiments, conducted in isolated ovarian follicles, confirmed this phenomenon and identified these gonadal components as the putative D-Asp targets. Other amino acids (L-Asp, D-Glu, L-Glu, D-Ala and L-Ala) used instead of D-Asp were ineffective. These findings indicate that D-Asp is involved in the control of androgen secretion by the ovary in this amphibian species, revealing a more complex system for control of this androgen synthesis than was previously believed to exist.

scholarly journals Testicular endocrine activity is upregulated by D-aspartic acid in the green frog, Rana esculenta

2004 ◽  
Vol 182 (2) ◽  
pp. 365-376 ◽  
Author(s):  
F Raucci ◽  
L Assisi ◽  
S D'Aniello ◽  
P Spinelli ◽  
V Botte ◽  
...  
Keyword(s):  
Amino Acid ◽  
Aspartic Acid ◽  
Reproductive Cycle ◽  
Rana Esculenta ◽  
Reproductive Period ◽  
Nuclear Antigen ◽  
Green Frog ◽  
Endocrine Activity ◽  
Testosterone Levels ◽  
Stimulation Of

This study investigated the involvement of D-aspartic acid (D-Asp) in testicular steroidogenesis of the green frog Rana esculenta and its effect on stimulation of thumb pad morphology and glandular activity, a typical testosterone-dependent secondary sexual characteristic in this amphibian species. In the testis, D-Asp concentrations vary significantly during the reproductive cycle: they are low in pre- and post-reproductive periods, but reach peak levels in the reproductive period (140-236 nmol/g wet tissue). Moreover, the concentrations of D-Asp in the testis through the sexual cycle positively match the testosterone levels in the gonad and the plasma. The racemase activity evaluated during the cycle expresses its peak when D-Asp and testosterone levels are highest, that is, during the reproductive period, confirming the synthesis of D-Asp from L-Asp by an aspartate racemase. Short-term in vivo experiments consisting of a single injection of D-Asp (2.0 micro mol/g body weight) demonstrated that this amino acid accumulates significantly in the testis, and after 3 h its uptake is coupled with a testosterone increase in both testis and plasma. Moreover, within 18 h of amino acid administration, the D-Asp concentration in the testis decreased along with the testosterone titer to prestimulation levels. Other amino acids (L-Asp, D-Glu and L-Glu) used instead of D-Asp were ineffective, confirming that the significant increase in testicular testosterone was a specific feature of this amino acid. In long-term experiments, D-Asp had been administered chronically to frogs caught during the three phases of the reproductive cycle, inducing testosterone increase and 17beta-estradiol decrease in the gonad during the pre- and post-reproductive period, and vice versa during the reproductive period. The stimulatory effect of D-Asp on testosterone production by the testis is consistent with the stimulation of spermatogenesis and the maturation of thumb pads occurring in D-Asp-treated frogs. In these last animals, there was an increase of seminiferous ampoule area and a higher number of spermatids and sperm. Moreover, in spermatogonia I and II and in spermatocytes, a proliferating cell nuclear antigen (PCNA) intense immunopositivity was observed. In addition, the thumb pads of D-Asp-treated frogs compared with controls showed a significantly thicker epithelial lining, a wider area of their glands with taller secretion cells, and more numerous, PAS-positive-rich secretions. Finally, these results provide functional evidence for a biologic role of D-Asp in amphibian male steroidogenesis; therefore, this unusual amino acid could be considered a modulatory agent for reproductive processes.

Stimulatory effect of a GnRH agonist (buserelin) in in vitro and in vivo testosterone production by the frog (Rana esculenta) testis

1984 ◽  
Vol 38 (2-3) ◽  
pp. 215-219 ◽  
Author(s):  
R. Pierantoni ◽  
S. Fasano ◽  
L. Di Matteo ◽  
S. Minucci ◽  
B. Varriale ◽  
...  
Keyword(s):  
Gnrh Agonist ◽  
Rana Esculenta ◽  
Testosterone Production

Synthesis of aspartic acid derivatives useful for the preparation of misacylated transfer RNAs

2000 ◽  
Vol 78 (6) ◽  
pp. 884-891 ◽  
Author(s):  
Michiel Lodder ◽  
Curtis F Crasto ◽  
Andrei L Laikhter ◽  
Haoyun An ◽  
Tuncer Arslan ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Aspartic Acid ◽  
Side Chain ◽  
Transfer Rnas ◽  
Rna Ligase ◽  
T4 Rna Ligase ◽  
In Vitro Transcripts ◽  
Derivatives Of

Several derivatives of aspartic acid were protected on Nα as their NVOC derivatives, and on the side chain carboxylates as nitroveratryl esters. Following activation as the cyanomethyl esters, these fully protected aspartate derivatives were converted to the respective pdCpA esters. The protected aspartyl-pdCpA esters were then utilized as substrates for T4 RNA ligase in the presence of in vitro transcripts of tRNA lacking the pCpA dinucleotide normally found at the 3'-end. In this fashion, several misacylated tRNAs were prepared; following photolytic deprotection, these were employed successfully for incorporation into proteins at predetermined positions.Key words: aminoacylated nucleotides, amino acid protection, protein synthesis, tRNA activation.

scholarly journals Resistance to microtubule-stabilising agents following point mutation of human βI-tubulin

2021 ◽  
Author(s):  
◽  
Matthew R. Rowe
Keyword(s):  
Amino Acid ◽  
Point Mutation ◽  
Aspartic Acid ◽  
Mammalian Cells ◽  
Marine Sponges ◽  
Multi Drug Resistance ◽  
Peloruside A ◽  
Characteristic Mode ◽  
Β Tubulin

<p>Marine environments represent a rich source of bioactive secondary metabolites that may be harnessed for use in a therapeutic context. Two novel compounds, peloruside A and laulimalide, isolated from the marine sponges Mycale hentsheli and Cacospongia mycofijiensis, respectively, both demonstrate useful pharmacological properties in mammalian cells. These compounds share major similarities with microtubule-stabilising agents. Like other agents in this class, peloruside A and laulimalide bind to the β-tubulin subunit of microtubules, the primary cytoskeletal element of eukaryotic cells. These compounds enhance polymerisation dynamics between ternary microtubule structures and severely hinder necessary cytoskeletal rearrangements within the cell.  Over the course of a patient’s treatment, cancerous cells may develop multi-drug resistance phenotypes. P-glycoprotein drug efflux pumps play a major role in the development of therapy resistance in many cancers, as the current generation microtubule-stabilising agents are easily removed from diseased cells by upregulated efflux mechanisms. Unlike agents already in clinical application, both peloruside A and laulimalide are poor substrates for removal by these mechanisms, making them and their synthetic derivatives interesting as potential treatments for drug-resistant tumours.  Peloruside A and laulimalide exhibit potent nanomolar anti-mitotic activities in vitro and arrest cell cycle progression in G₂/M phase, leading to cell death – a characteristic mode of action among microtubule-stabilising agents. Unlike all known agents in this class, peloruside A and laulimalide share a secondary, unique binding region in β-tubulin. In the past decade our understanding of this region has developed, revealing a second, unique mechanism for stabilisation of microtubules.  Using mammalian cells to model physiological tubulin, the present study investigates the predicted role of aspartic acid 297 of human βI-tubulin in the binding association of both peloruside A and laulimalide. This particular amino acid is predicted to hydrogen bond with both compounds, contributing to their activity as stabilisers.  It was revealed that the introduction of a point mutation in D297 resulted in a small but highly consistent resistance phenotype to both compounds, but not to microtubule-stabilising agents that bind to the traditional, taxoid site on β-tubulin. It was concluded that aspartic acid 297 is likely to be one of the amino acids directly involved in the binding association of peloruside A and laulimalide to β-tubulin, contributing partial compound stabilisation. The rational synthesis of future analogues may benefit from these findings in the design of molecules with enhanced interactions at this particular amino acid residue.</p>

scholarly journals Resistance to microtubule-stabilising agents following point mutation of human βI-tubulin

2021 ◽  
Author(s):  
◽  
Matthew R. Rowe
Keyword(s):  
Amino Acid ◽  
Point Mutation ◽  
Aspartic Acid ◽  
Mammalian Cells ◽  
Marine Sponges ◽  
Multi Drug Resistance ◽  
Peloruside A ◽  
Characteristic Mode ◽  
Β Tubulin

<p>Marine environments represent a rich source of bioactive secondary metabolites that may be harnessed for use in a therapeutic context. Two novel compounds, peloruside A and laulimalide, isolated from the marine sponges Mycale hentsheli and Cacospongia mycofijiensis, respectively, both demonstrate useful pharmacological properties in mammalian cells. These compounds share major similarities with microtubule-stabilising agents. Like other agents in this class, peloruside A and laulimalide bind to the β-tubulin subunit of microtubules, the primary cytoskeletal element of eukaryotic cells. These compounds enhance polymerisation dynamics between ternary microtubule structures and severely hinder necessary cytoskeletal rearrangements within the cell.  Over the course of a patient’s treatment, cancerous cells may develop multi-drug resistance phenotypes. P-glycoprotein drug efflux pumps play a major role in the development of therapy resistance in many cancers, as the current generation microtubule-stabilising agents are easily removed from diseased cells by upregulated efflux mechanisms. Unlike agents already in clinical application, both peloruside A and laulimalide are poor substrates for removal by these mechanisms, making them and their synthetic derivatives interesting as potential treatments for drug-resistant tumours.  Peloruside A and laulimalide exhibit potent nanomolar anti-mitotic activities in vitro and arrest cell cycle progression in G₂/M phase, leading to cell death – a characteristic mode of action among microtubule-stabilising agents. Unlike all known agents in this class, peloruside A and laulimalide share a secondary, unique binding region in β-tubulin. In the past decade our understanding of this region has developed, revealing a second, unique mechanism for stabilisation of microtubules.  Using mammalian cells to model physiological tubulin, the present study investigates the predicted role of aspartic acid 297 of human βI-tubulin in the binding association of both peloruside A and laulimalide. This particular amino acid is predicted to hydrogen bond with both compounds, contributing to their activity as stabilisers.  It was revealed that the introduction of a point mutation in D297 resulted in a small but highly consistent resistance phenotype to both compounds, but not to microtubule-stabilising agents that bind to the traditional, taxoid site on β-tubulin. It was concluded that aspartic acid 297 is likely to be one of the amino acids directly involved in the binding association of peloruside A and laulimalide to β-tubulin, contributing partial compound stabilisation. The rational synthesis of future analogues may benefit from these findings in the design of molecules with enhanced interactions at this particular amino acid residue.</p>

Amino acid content of rat renal cortex and the response to in vitro incubation

1979 ◽  
Vol 236 (4) ◽  
pp. F398-F404
Author(s):  
B. Blazer-Yost ◽  
R. Reynolds ◽  
S. Segal
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Glutamic Acid ◽  
Aspartic Acid ◽  
Room Temperature ◽  
Renal Cortex ◽  
Adult Tissue ◽  
Fresh Tissue ◽  
Cortical Slices

The concentration of aspartic acid, threonine, serine, glycine, and alanine is significantly higher in newborn rat renal cortex than in the adult tissue, while phenylalanine and histidine are higher in the adult. When adult cortical slices are placed in bicarbonate buffer at room temperature for 20 min there is a 30-60% decrease in the levels of all amino acids except for lysine, which is slightly higher, and methionine and serine, which do not change. Under the same conditions, newborn cortical slices reveal a similar decrease in only glycine, tyrosine, histidine, and the branched-chain amino acids. On subsequent in vitro incubation of the cortical slices at 37 degrees C for 120 min the concentrations in adult tissue remain at the lower values observed on removal from buffer at room temperature except that glutamic acid, glycine, and lysine levels decrease further and serine increases to the concentration found in fresh tissue. Newborn tissue when incubated at 37 degrees C for 120 min shows amino acid concentrations comparable to unincubated fresh tissue for all except aspartic acid, glutamic acid, serine, and phenylalanine, which reach levels higher than unincubated tissue. The ability of newborn tissue to maintain amino acid pools may play a role in the enhanced transport of some amino acids resulting from preincubation at 37 degrees C (Reynolds et al. Science 184: 68-69, 1974; Reynolds and Segal, Biochim. Biophys. Acta 406: 513-525, 1976).

Uptake of Dipeptides Containing Basic and Acidic Amino Acids by Rat Small Intestine in Vitro

1972 ◽  
Vol 43 (6) ◽  
pp. 823-837 ◽  
Author(s):  
D. Burston ◽  
Jill M. Addison ◽  
D. M. Matthews
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Glutamic Acid ◽  
Aspartic Acid ◽  
Free Amino Acids ◽  
Free Amino ◽  
Tissue Uptake ◽  
Acidic Amino Acids ◽  
Hydrolysis Of

1. The characteristics of transport and hydrolysis of twenty-two dipeptides containing basic and acidic amino acids by rat ileal rings were investigated in vitro. The peptides included combinations of basic and neutral, basic and basic, basic and acidic, acidic and acidic, and acidic and neutral amino acids. 2. All peptides studied were removed intact from the bulk phase of the incubation medium, though, in general, only free amino acids appeared in the tissue. Uptake of one or both constituent amino acids was greater from the peptide than from the equivalent amino acid or amino acid mixture in the case of at least one peptide from each group and in eighteen of the twenty-two peptides studied. In general, there was no relationship between the extent of uptake of amino acids from peptides and the extent of their hydrolysis by the system. The results support the hypothesis that there is more than one mode of uptake of amino acids from peptides. 3. Hydrolysis of γ-glutamyl-l-glutamic acid by intact intestine or intestinal homogenate was slight, and intact peptide was taken up by the tissue. Uptake of free glutamic acid from this peptide was poor. Comparison of γ-glutamyl-l-glutamic acid with three other slowly hydrolysed dipeptides, glycyl-d-valine, sarcosylglycine and glycylsarcosine, suggested that all four were transported into the mucosal cells and hydrolysed intracellularly. The results indicate that the presence of a γ-linkage or a d-amino acid, or methylation of the free amino group as in sarcosylglycine, impair both transport and hydrolysis of peptide, but that attachment of a methyl group to the N of the peptide bond, as in glycylsarcosine, impairs hydrolysis but has no effect on peptide transport. 4. l-Aspartic acid and l-glutamic acid were extensively transaminated by the intestine, whether presented as free amino acids or in peptides. Evidence was obtained suggesting that production of alanine from aspartic acid resulted from direct transamination of aspartic acid with pyruvic acid, rather than from a sequence of two reactions involving aspartate and alanine aminotransferases. 5. The results show that more rapid uptake of amino acids from peptides than from free amino acids is not confined to peptides made up of neutral amino acids, and probably occurs with many small peptides. Uptake of lysine and the dicarboxylic amino acids, which are particularly slowly absorbed from free solution, was much greater from several dipeptides than from the free amino acids. The results suggest the importance of mucosal peptide uptake in protein absorption.

Sign in / Sign up

Export Citation Format

Share Document