Abalone myoglobins evolved from indoleamine dioxygenase: The cDNA-derived amino acid sequence of myoglobin fromNordotis madaka

The cDNA for the unusual 41 kD myoglobin of the abaloneNordotis madaka was amplified by polymerase chain reaction (PCR), and the cDNA-derived amino acid sequence of 378 residues was determined. As with the myoglobin of the related abaloneSulculus diversicolor (Suzuki and Takagi,J. Mol. Biol. 228, 698–700, 1992), the sequence ofNordotis myoglobin showed no significant homology with any other globins, but showed high homology (35% identity) with vertebrate indoleamine 2,3-dioxygenase, a tryptophan degrading enzyme containing heme. The amino acid sequence homology betweenNordotis andSulculus myoglobins was 87%. These results support our previous idea that the abalone myoglobins evolved from a gene for indoleamine dioxygenase, but not from a globin gene, and therefore all of the hemoglobins and myoglobins are not homologous. Thus, abalone myoglobins appear to be a typical case of convergent evolution.     

Regional changes in muscle mass and strength following 20 days of bed rest, and the effects on orthostatic tolerance capacity in young subjects

To this day, many studies have suggested that prolonged bed rest (BR) affects on muscle mass and strength not only in gravity muscles but also in ungravity muscles. However, it is still unclear whether the decrease in regional muscle strength after BR is due to the alterations in the corresponding muscle mass, or not. On the other hand, if BR decreases the mass of antigravity muscles (UGM) as well as muscle strength and then increases tissue compliance of the antigravity muscles, orthostatic tolerance capacity will be decreased by the reduction in cardiac output (CO) in spite of the increase in myocardial contractility because the more decrease in venous return due to the more increase in blood pooling within the compliant tissues of the lower body. However, this is also unclear. To make these questions clear, the present study investigated the regional muscle mass and strength and orthostatic tolerance capacity before and after 20 days of bed rest in young subjects.     

Capillary filtration rate, venous compliance, and blood flow in arms and legs do not change during bed rest for 20 days

It has been generally accepted that pooling of the blood in the legs is one reason for the orthostatic intolerance experienced after space flights. This is also the reasoning behind the application of anti-G suits during reentry after space flights. Fighter pilots also use the anti-G suit, the hypothesis being that this prevents the pooling of blood in the legs. In order to investigate if immobilization during bed rest would induce peripheral cardiovascular deconditioning we measured capillary filtration rate, venous compliance, and blood flow in arms and legs during bed rest.     

Timing of insemination in terms of age of new reproductive females of a temperate-zone polistine wasp,Polistes snelleni (Hymenoptera: Vespidae)

Summary The present study investigated the age at which insemination takes place in Polistes snelleni, a species in which mating begins while new reproductives are still emerging from the nest. Insemination of new reproductive females began as early as 5 days of age, and most females were inseminated by 10 days of age.     

Escherichia coli K-12 can utilize an exogenous gamma-glutamyl peptide as an amino acid source, for which gamma-glutamyltranspeptidase is essential.

Escherichia coli K-12 can utilize a gamma-glutamyl peptide as an amino acid source, for which gamma-glutamyltranspeptidase (EC 2.3.2.2) is essential. We suggest that the gamma-glutamyl linkage of a gamma-glutamyl peptide is hydrolyzed by gamma-glutamyltranspeptidase located in the periplasmic space, and the released amino acid is taken up and utilized by E. coli.     

Further Evidence for Multiple Forms of an N-Methyl-d-Aspartate Recognition Domain in Rat Brain Using Membrane Binding Techniques

Abstract— Pretreatment with sulfhydryl-reactive agents, such as N-ethylmaleimide and p-chloromercuriphenylsul-fonic acid, invariably resulted in marked inhibition of the binding of dl -(E)-2-amino-4-[³H]propyl-5-phosphono-3-pentenoic acid ([³H]CGP 39653), a competitive antagonist at an N-methyl-d -aspartate (NMDA)-sensitive subclass of central excitatory amino acid receptors, in brain synaptic membranes extensively washed and treated with Triton X-100, but did not significantly affect the binding of L-[³H]-glutamic acid ([³H]Glu), an endogenous agonist. The pre-treatment was effective in reducing the binding of [³H]-CGP 39653 at equilibrium, without altering the initial association rate, and decreased the affinity for the ligand. Pretreatment with sulfhydryl-reactive agents also enhanced the potencies of NMDA agonists to displace [³H]-CGP 39653 binding and attenuated those of NMDA antagonists, but had little effect on the potencies of the agonists and antagonists to displace [³H]Glu binding. The binding of both [³H]CGP 39653 and [³H]Glu was similarly sensitive to pretreatment with four different proteases in Tritontreated membranes, whereas pretreatment with phospho-lipase A₂ or C markedly inhibited [³H]CGP 39653 binding without altering [³H]Glu binding. Moreover, both phospho-lipases not only induced enhancement of the abilities of NMDA agonists to displace the binding of [³H]CGP 39653 and [³H]Glu, but also caused diminution of those of NMDA antagonists. These results suggest that both sulfhydryl-reactive agents and phospholipases may predominantly interfere with radiolabeling of the NMDA recognition domain in a state favorable to an antagonist by [³H]CGP 39653, with concomitant facilitation of that in an agonist-preferring form by [³H]Glu. The possible presence of multiple forms of the NMDA recognition domain is further supported by these data.     

Support for Radiolabeling of a Glycine Recognition Domain on the N-Methyl-d-Aspartate Receptor Ionophore Complex by 5,7-[3H]Dichlorokynurenate in Rat Brain

Abstract: Pretreatment with Triton X-100 more than doubled the binding of radiolabeled 5,7-dichlorokynurenic acid (DCKA), a proposed antagonist at a glycine (Gly) recognition domain on the N-methyl-d -aspartate (NMDA) receptor ionophore complex, in rat brain synaptic membranes. The binding exhibited an inverse temperature dependency, reversibility, and saturability, the binding sites consisting of a single component with a high affinity (27.5 nM) and a relatively low density (2.87 pmol/mg of protein). The binding of both [³H]DCKA and [³H]Gly was similarly displaced by numerous putative agonists and antagonists at the Gly domain in a concentration-dependent manner at a concentration range of 100 nM to 0.1 mM. Among the 24 putative ligands tested, DCKA was the second most potent displacer of the binding of both radioligands with no intrinsic affinity for the binding of [³H]kainic acid and α-amino-3-hydroxy-5-[³H]methylisoxazole-4-propionic acid (AMPA) to the non-NMDA receptors. In contrast, the other proposed potent Gly antagonist, 5,7-dinitroquinoxaline-2,3-dione, was active in displacing the binding of [³H]glutamic ([³H]Glu) and D,L-(E)-2-amino-4-[³H]propyl-5-phosphono-3-pentenoic acids to the NMDA recognition domain with a relatively high affinity for the non-NMDA receptors. In addition, the proposed antagonist at the AMPA-sensitive receptor, 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline, not only displaced weakly the binding of both [³H]- Gly and [³H]DCKA, but also inhibited the binding of (+)-5-[³H]methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine ([³H]MK-801) to an ion channel associated with the NMDA-sensitive receptor in the presence of added Glu alone in a manner sensitive to antagonism by further added Gly. Clear correlations were seen between potencies of the displacers to displace [³H]DCKA binding and [³H]Gly binding, in addition to between the potencies to displace [³H]-DCKA or [³H]Gly binding and to potentiate or inhibit [³H]MK-801 binding. All quinoxalines tested were invariably more potent displacers of [³H]DCKA binding than [³H]Gly binding, whereas kynurenines were similarly effective in displacing the binding of both [³H]Gly and [³H]-DCKA. These results undoubtedly give support to the proposal that [³H]DCKA is one useful radioligand available in terms of its high selectivity and affinity for the Gly domain in the brain. Possible multiplicity of the Gly domain is suggested by the differential pharmacological profiles between the binding of [³H]Gly and [³H]DCKA.