Close relationships between polar auxin transport and graviresponse in plants

Gravitational force on Earth is one of the major environmental factors affecting plant growth and development. Spacecraft and the International Space Station (ISS), and a three-dimensional (3-D) clinostat have been available to clarify the effects of gravistimulation on plant growth and development in space and on ground conditions, respectively. Under a stimulus-free environment such as space conditions, plants show a growth and developmental habit designated as 'automorphosis' or 'automorphogenesis'. Recent studies in hormonal physiology, together with space and molecular biology, have demonstrated the close relationships between automorphosis and polar auxin transport. Reduced polar auxin transport in space conditions, or induced by the application of polar auxin transport inhibitors, substantially induced automorphosis or automorphosis-like growth and development, indicating that polar auxin transport is responsible for graviresponse in plants. This concise review covers graviresponse in plants and automorphosis observed in space conditions, and polar auxin transport related to graviresponse in etiolated Alaska and ageotropum pea seedlings. Molecular aspects of polar auxin transport clarified in recent studies are also described.

Apoptosis induced by high-LET radiations is not affected by cellular p53 gene status

To learn more about the biological effects of high-linear energy transfer (LET) radiations, we examined radiation-induced apoptosis in response to high-LET radiations in cells with wild-type, mutated and null p53 gene. Three human lung cancer cell lines were used. These lines had identical genotypes, except for the p53 gene. Cells were exposed to X-rays or high-LET radiations (13 - 200 keV microm(-1)) using different nuclei ion beams. Cellular radiation sensitivities were determined with the use of colony-forming assays. Apoptosis was detected and quantified using Hoechst 33342 staining with fluorescence microscopy. It was found that (1) there was no significant difference in cellular sensitivity to high-LET radiation (>85 keV microm(-1)), although the sensitivity of wild-type p53 cells to X-rays was higher than that of mutated p53 or p53-null cells; (2) X-ray-induced apoptosis at higher frequencies in wild-type p53 cells when compared with mutated p53 and p53-null cells; and (3) Fe beams (200 keV microm(-1)) induced apoptosis in a p53-independent manner. The results indicate that high-LET radiations induces apoptosis in human lung cancer cells in a manner that does not seem to depend on the p53 gene status of the cells.

Chronomics of heart rate variability on earth and in space

Chronomes are time structures consisting of multifrequency rhythms, elements of chaos, and trends in chaotic and rhythmic endpoints. Chronomics maps the dynamics of organisms' broad interactions with the environment near and far, rather than merely the daily routines. We introduced the chronomics of heart rate variability (HRV), characterized by a broad time structure, that includes the prominent circadians and also ultradian (notably about 8h and about 12h) and infradian (notably about-weekly, about-yearly, and about 10-yearly) changes, in addition to undergoing trends with aging. Alterations in these HRV chronomes are known to predict the presence of disease in the near future. Thus, for the health and safety of astronauts, HRV chronomes should be assessed before, during and after the mission in the International Space Station to check for any alteration. Future work should focus on how phenomena in the cosmos, including helio- and geomagnetics, can affect physiological chronomes, those of the HRV in particular.

Description of International Caenorhabditis elegans Experiment first flight (ICE-FIRST)

Traveling, living and working in space is now a reality. The number of people and length of time in space is increasing. With new horizons for exploration it becomes more important to fully understand and provide countermeasures to the effects of the space environment on the human body. In addition, space provides a unique laboratory to study how life and physiologic functions adapt from the cellular level to that of the entire organism. Caenorhabditis elegans is a genetic model organism used to study physiology on Earth. Here we provide a description of the rationale, design, methods, and space culture validation of the ICE-FIRST payload, which engaged C. elegans researchers from four nations. Here we also show C. elegans growth and development proceeds essentially normally in a chemically defined liquid medium on board the International Space Station (10.9 day round trip). By setting flight constraints first and bringing together established C. elegans researchers second, we were able to use minimal stowage space to successfully return a total of 53 independent samples, each containing more than a hundred individual animals, to investigators within one year of experiment concept. We believe that in the future, bringing together individuals with knowledge of flight experiment operations, flight hardware, space biology, and genetic model organisms should yield similarly successful payloads.

Comparison of Cell Body Size and Oxidative Enzyme Activity in Motoneurons between the Cervical and Lumbar Segments in the Rat Spinal Cord after Spaceflight and Recovery

The cell body sizes and succinate dehydrogenase (SDH) activities of motoneurons in the dorsolateral region of the ventral horn at the cervical and lumbar segments in the rat spinal cord were determined following 9 days of spaceflight with or without 10 days of recovery on Earth. The motoneurons were divided into three types based on their cell body sizes; small-, medium-, and large-sized motoneurons. In control rats, there was no difference in the cell body size or SDH activity of small- and large-sized motoneurons between the cervical and lumbar segments. The SDH activity of medium-sized motoneurons in control rats was higher in the lumbar segment than in the cervical segment, while the cell body sizes of medium-sized motoneurons were identical. The SDH activity of medium-sized motoneurons in the lumbar segment decreased to a level similar to that in the cervical segment of control rats following spaceflight. In addition, the decreased SDH activity of medium-sized motoneurons persisted for at least 10 days of recovery on Earth. It is concluded that spaceflight selectively affects the SDH activity of medium-sized motoneurons in the lumbar segment of the spinal cord, which presumably innervate skeletal muscles having an antigravity function.

Checkpoint and physiological apoptosis in germ cells proceeds normally in spaceflown Caenorhabditis elegans

It is important for human life in space to study the effects of environmental factors during spaceflight on a number of physiological phenomena. Apoptosis plays important roles in development and tissue homeostasis in metazoans. In this study, we have analyzed apoptotic activity in germ cells of the nematode C. elegans, following spaceflight. Comparison of the number of cell corpses in wild type or ced-1 mutants, grown under either ground or spaceflight conditions, showed that both pachytene-checkpoint apoptosis and physiological apoptosis in germ cells occurred normally under spaceflight conditions. In addition, the expression levels of the checkpoint and apoptosis related genes are comparable between spaceflight and ground conditions. This is the first report documenting the occurrence of checkpoint apoptosis in the space environment and suggests that metazoans, including humans, would be able to eliminate cells that have failed to repair DNA lesions introduced by cosmic radiation during spaceflight.

NASDA next generation Aquatic Habitat for Space Shuttle and ISS

The National Space Development Agency of Japan (NASDA) has more than 20 years of experience developing aquatic animal experiment facilities. We are now studying the next-generation aquatic animal experiment facility or the Aquatic Habitat (AQH) for both Space Shuttle and International Space Station use. A prototype breeding system was designed and tested. Medaka adult fish were able to mate and spawn in this closed circulatory breeding system, and the larvae grew to adult fish and spawned on the 45th day after hatching. The water quality-control system using nitrifying bacteria worked well throughout the medaka breeding test. For amphibians, we also conducted the African clawed toad (Xenopus laevis) breeding test with the same specimen chambers, although a part of circulation loop was opened to air. Xenopus larvae grew and completed metamorphosis successfully in the small specimen chamber. The first metamorphic climax started on the 30th day and was completed on the 38th day.

Space environment, electromagnetic fields, and circadian rhythm

Human space activity began in 1961. About 400 persons have gone to space since then, and about 70 of them have stayed more than 1 month. Circadian rhythm and sleep in space have been investigated several times, though the effect of longer stays in space has not been adequately clarified. Electromagnetic fields are different in the space environment, especially in deeper space missions, such as the Moon or Mars, but their effects on human health have rarely been studied. In this article, we summarize the current status of the International Space Station project, study circadian rhythm and sleep in space, investigate electromagnetic fields, and state the necessity for investigating this research field.

Cell body size and succinate dehydrogenase activity of spinal motoneurons innervating the soleus muscle in mice, rats, and cats

The cell body sizes and succinate dehydrogenase (SDH) activities of motoneurons in the retrodorsolateral region of the ventral horn in the spinal cord innervating the soleus muscle in mice, rats, and cats were compared using quantitative enzyme histochemistry. There was an inverse relationship between cell body size and SDH activity of motoneurons in the three species. The mean cell body sizes of both gamma and alpha motoneuron pools were in the rank order of mice < rats < cats, while the mean SDH activities of both gamma and alpha motoneuron pools were in the rank order of mice > rats > cats. It is concluded that smaller motoneurons innervating the soleus muscle have higher SDH activities than larger motoneurons, irrespective of the species, and that motoneuron pools innervating the soleus muscle in smaller animals have smaller mean cell body sizes and higher mean SDH activities than those in larger animals.

Is compensatory vasoconstrictor tone in the hindquarter vascular region induced by hemorrhage in conscious spontaneously hypertensive rats?

We investigated whether a compensatory vasoconstrictor action would be induced by a hypotensive intervention in the hindquarter vascular region of conscious spontaneously hypertensive rats (SHRs). Mean arterial pressure and hindquarter blood flow were recorded. After hemorrhage (withdrawing blood, 0.3 ml/100 g body weight), hindquarter resistance (HQR) was increased significantly. The decrease in HQR induced by the administration of a ganglionic blocker (C6; 25 mg/kg, i.v.) was significantly greater in SHRs with hemorrhage than in those without hemorrhage. The present results suggest that a detectable hindquarter compensator tone occurs due to hemorrhage in SHRs, although an abnormal substantial vasoconstrictor tone already exists in the hindquarters.

Growth regulation mechanisms in higher plants under microgravity conditions - changes in cell wall metabolism

During Space Shuttle STS-95 mission, we cultivated seedlings of rice (Oryza sativa L. cv. Koshihikari and cv. Tan-ginbozu) and Arabidopsis (Arabidopsis thaliana L. cv. Columbia and cv. etr1-1) for 68.5, 91.5, and 136 hr on board, and then analyzed changes in the nature of their cell walls, growth, and morphogenesis under microgravity conditions. In space, elongation growth of both rice coleoptiles and Arabidopsis hypocotyls was stimulated. Also, the increase in the cell wall extensibility, especially that in the irreversible extensibility, was observed for such materials. The analyses of the amounts, the structure, and the physicochemical properties of the cell wall constituents indicated that the decreases in levels and molecular masses of cell wall polysaccharides were induced under microgravity conditions, which appeared to contribute to the increase in the wall extensibility. The activity of certain wall enzymes responsible for the metabolic turnover of the wall polysaccharides was increased in space. By the space flight, we also confirmed the occurrence of automorphogenesis of both seedlings under microgravity conditions; rice coleoptiles showed an adaxial bending, whereas Arabidopsis hypocotyls elongated in random directions. Furthermore, it was shown that spontaneous curvatures of rice coleoptiles in space were brought about uneven modifications of cell wall properties between the convex and the concave sides.

STS-95 space experiment for plant growth and development, and auxin polar transport

The principal objective of the space experiment, BRIC-AUX on STS-95, was the integrated analysis of the growth and development of etiolated pea and maize seedlings in space, and the effect of microgravity conditions in space on auxin polar transport in the segments. Microgravity conditions in space strongly affected the growth and development of etiolated pea and maize seedlings. Etiolated pea and maize seedlings were leaned and curved during space flight, respectively. Finally the growth inhibition of these seedlings was also observed. Roots of some pea seedlings grew toward the aerial space of Plant Growth Chamber. Extensibilities of cell walls of the third internode of etiolated pea epicotyls and the top region of etiolated maize coleoptiles which were germinated and grown under microgravity conditions in space were significantly low. Activities of auxin polar transport in the second internode segments of etiolated pea seedlings and coleoptile segments of etiolated maize seedlings were significantly inhibited and extremely promoted, respectively, under microgravity conditions in space. These results strongly suggest that auxin polar transport as well as the growth and development of plants is controlled under gravity on the earth.

Renal interstitial Ca(2+)

Renal interstitial fluid Ca(2+) concentration ([Ca(2+)](isf)) was measured in anesthetized Wistar rats by using in situ microdialysis. During perfusion of 20 cm of the proximal small intestine with Ca(2+)-free buffer, renal [Ca(2+)](isf) was 1.63 +/- 0.19 mmol/l in the cortex (n = 6) and 1.93 +/- 0.12 mmol/l in the medulla (n = 5, P = 0.223). When Ca(2+) in the intestinal lumen was increased to 3 mmol/l, no change was seen in total or ionized serum Ca(2+) (S(Ca)), urinary Ca(2+) excretion (U(Ca)), or Ca(2+) in a microdialysate of the kidney cortex. Increasing intestinal Ca(2+) further, to 6 mmol/l, was without effect on S(Ca) but significantly increased U(Ca) by 38% and microdialysate Ca(2+) by 36% (1.25 +/- 0.0.09 vs. 1.70 +/- 0. 14 mmol/l, n = 4, P < 0.05). Intravenous infusion of 28 ng. kg(-1). min(-1) of parathyroid hormone for 1 h during perfusion of the intestinal lumen with 1 mmol/ Ca(2+)caused a 7-10% rise in S(Ca), a 40% fall in U(Ca), and a 32% increase in microdialysate Ca(2+) (1.32 +/- 0.13 vs. 1.74 +/- 0.13 mmol/l, n = 6, P < 0.05). Interlobar arteries with a mean diameter of 120 microm were studied by using a wire myograph to determine whether changes in extracellular Ca(2+) affect muscle tone. When precontracted with 5 micromol/l serotonin, the arteries relaxed in response to cumulative addition of Ca(2+) (1-5 mmol/l) with an ED(50) value for Ca(2+) of 3.30 +/- 0.08 mmol/l, n = 3. These data demonstrate that [Ca(2+)](isf) changes dynamically during manipulation of whole-animal Ca(2+) homeostasis and that intrarenal arteries relax in response to extracellular Ca(2+) varied over the range measured in vivo.

A role for N-arachidonylethanolamine (anandamide) as the mediator of sensory nerve-dependent Ca2+-induced relaxation

We tested the hypothesis that an endogenous cannabinoid (CB) receptor agonist, such as N-arachidonylethanolamine (anandamide), is the transmitter that mediates perivascular sensory nerve-dependent Ca2+-induced relaxation. Rat mesenteric branch arteries were studied using wire myography; relaxation was determined after inducing contraction with norepinephrine. Cumulative addition of Ca2+ caused dose-dependent relaxation (ED50 = 2.2 +/- 0.09 mM). The relaxation was inhibited by 10 mM TEA and 100 nM iberiotoxin, a blocker of large conductance Ca2+-activated K+ channels, but not by 5 microM glibenclamide, 1 mM 4-aminopyridine, or 30 nM apamin. Ca2+-induced relaxation was also blocked by the selective CB receptor antagonist SR141716A and was enhanced by pretreatment with 4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride (pefabloc; 30 microM), an inhibitor of anandamide metabolism. Anandamide also caused dose-dependent relaxation (ED50 =.72 +/- 0.3 microM). The relaxation was not inhibited by endothelial denudation, 10 microM indomethacin, or 1 microM miconazole, but was blocked by 3 microM SR141716A, 10 mM TEA, precontraction with 100 mM K+, and 100 nM iberiotoxin, and was enhanced by treatment with 30 microM pefabloc. Mesenteric branch arteries were 200-fold more sensitive to the relaxing action of anandamide than arachidonic acid (ED50 = 160 +/- 7 microM). These data show that: 1) Ca2+ and anandamide cause hyperpolarization-mediated relaxation of mesenteric branch arteries, which is dependent on an iberiotoxin-sensitive Ca2+-activated K+ channel, 2) relaxation induced by both Ca2+ and anandamide is inhibited by CB receptor blockade, and 3) relaxation induced by anandamide is not dependent on its breakdown to arachidonic acid and subsequent metabolism. These findings support the hypothesis that anandamide, or a similar cannabinoid receptor agonist, mediates nerve-dependent Ca2+-induced relaxation in the rat.

Interstitial Ca2+ undergoes dynamic changes sufficient to stimulate nerve-dependent Ca2+-induced relaxation

We recently described a perivascular sensory nerve-linked dilator system that can be activated by interstitial Ca2+ (Ca2+isf). The present study tested the hypothesis that Ca2+isf in the rat duodenal submucosa varies through a range that is sufficient to activate this pathway. An in situ microdialysis method was used to estimate Ca2+isf. When the duodenal lumen was perfused with Ca2+-free buffer, Ca2+isf was 1.0 +/- 0.13 mmol/l. Ca2+isf increased to 1.52 +/- 0.04, 1.78 +/- 0.10, and 1.89 +/- 0.1 when the lumen was perfused with buffer containing 3, 6, and 10 mmol/l Ca2+, respectively (P < 0.05). Ca2+isf was 1.1 +/- 0.06 mmol/l in fasted animals and increased to 1. 4 +/- 0.06 mmol/l in free-feeding rats (P < 0.05). Wire myography was used to study isometric tension responses of isolated mesenteric resistance arteries. Cumulative addition of extracellular Ca2+-relaxed serotonin- and methoxamine-precontracted arteries with half-maximal effective doses of 1.54 +/- 0.05 and 1.67 +/- 0.08 mmol/l, respectively (n = 5). These data show that duodenal Ca2+isf undergoes dynamic changes over a range that activates the sensory nerve-linked dilator system and indicate that this system can link changes in local Ca2+ transport with alterations in regional resistance and organ blood flow.

Endothelin-1 improves the impaired filterability of red blood cells through the activation of protein kinase C

We previously showed that the deformability of human red blood cells (RBCs) is affected by intracellular signaling pathways by examining the effects of Ca2+ influx and the intracellular cAMP level on mechanically-impaired RBC filterability. In the present study, we investigated whether protein kinase C (PKC) participates in the regulation of RBC deformability by affecting membrane properties. The filterability of mechanically-stressed RBCs showed a V-shaped curve depending on the extracellular Ca2+ concentration; the maximum decrease was achieved at 20-40 microM. The PKC activity, as measured in the membrane-rich fraction by an ELISA method using an antibody for the phosphorylated PKC substrate, maximally increased at the extracellular Ca2+ concentration where the filterability showed a marked improvement following the bottom of the V-shaped curve of the impaired filterability. At this Ca2+ concentration, the PKC activator endothelin-1 increased the PKC activity, and a PKC inhibitor (calphostin C) decreased it. Endothelin-1 improved and calphostin C worsened the impaired filterability. A specific type-B endothelin receptor agonist (IRL 1620) also improved the impaired filterability. A Western blot analysis revealed the presence of endothelin receptors in the RBC membrane. These results indicate that PKC improves the impaired filterability and that RBCs are the target of endothelin-1.

Production of prostaglandins E1 and E2 by adult human red blood cells

We showed that human adult red blood cells (RBCs) produce prostaglandin E1 (PGE1) and E2 (PGE2). RBCs that were mechanically stressed in the presence of extracellular Ca2+ by being injected rapidly through a fine needle produced PGE1 and PGE2 within 30 min after this mechanical stress. The amounts of PGE1 and PGE2 produced by 1 x 10(9) mechanically stressed RBCs were approximately 50 pg and 100 pg, respectively, which were determined in the cytosolic fraction from sonicated RBCs using a competitive enzyme immunoassay method. A Western blot analysis using anti-cyclooxygenase-2 antibody revealed a band at the 70-kDa position in the samples from RBCs producing PGE1 and PGE2. Treatment with 10 micrograms/mL indomethacin completely inhibited the productions of PGE1 and PGE2. The present results may indicate a new role of RBCs in microcirculation.

Single-column high-performance liquid chromatographic-fluorescence detection of immature, mature, and senescent cross-links of collagen

A high-performance liquid chromatographic-fluorescence detection method of reducible (immature) and nonreducible (mature and senescent) cross-links of collagen was established without the use of a radioisotope and preliminary fractionation step. This method used a gradient elution procedure of sodium citrate buffer containing 7% ethanol. The reducible cross-links (dihydroxylysinonorleucine, hydroxylysinonorleucine, and lysinonorleucine) and nonreducible cross-link (histidinohydroxylysinonorleucine) were detected by O-phthalaldehyde derivatization with the postcolumn method, whereas other nonreducible cross-links (pyridinoline, deoxypyridinoline, and pentosidine) were detected by natural fluorescence. The linear ranges of contents of the O-phthalaldehyde derivative cross-links and the natural fluorescent nonreducible cross-links were 20-600, 5-500 (pyridinoline, deoxypyridinoline), and 0.2-20 pmol (pentosidine), respectively. Tissue containing 1-2 mg dry wt of collagen was adequate for duplicate analyses of the reducible and nonreducible cross-links. An equivalent of 0.25 mg of hydrolyzed collagen could be analyzed by this HPLC system. Using this system, age-related changes in the cross-links of collagen from human connective tissues were also investigated.

Lack of effect of transmembrane gradient of magnesium and sodium on regulation of cytosolic free magnesium concentration in rat lymphocytes

The regulation of the intracellular concentration of Mg2+ ([Mg2+]i) is not fully understood. The level of Mg in lymphocytes is a good predictor of total body Mg status. We measured [Mg2+]i and total Mg in rat lymphocytes by using, respectively, the fluorescent Mg2+ indicator mag-fura-2 and atomic absorption spectrophotometry. The basal [Mg2+]i in rat lymphocytes was 328 +/- 23 micromol/l. An elevation to 5 mmol/l or the removal of extracellular Mg2+ did not affect [Mg2+]i. A reduction in extracellular Na+ did not influence [Mg2+]i for 60 min. The total Mg concentration in lymphocytes also remained stable. Results suggest that the permeability of the plasma membrane to Mg2+ is very low, and that Na+/Mg2+ exchange is not involved in the regulation of [Mg2+]i in rat lymphocytes.

Detection of a genetic variant, lysine-->glutamic acid at position 372 of human serum albumin, by capillary electrophoresis and structural identification

A genetic variant of human serum albumin (alloalbumin) is detected by capillary electrophoresis (CE). Two albumin peaks, which were in the ratio of approximately one, were clearly separated. One of the peaks had the same migration time as normal albumin (Alb A) and the other (Alb X) had a longer migration time. SDS-polyacrylamide gel electrophoresis of CNBr fragments (CB) of Alb X indicated that the amino acid substitution was localized in the CB5 fragment (residue 330-446) of the molecule, because of anomalous migration of CB5 in the gel. The CE mapping of the tryptic peptides from the variant CB5 revealed clearly the existence of a new peptide, and the lack of two normal peptides. The sequence analysis of the variant peptide collected by CE micropreparation showed that the N-terminus of the variant peptide corresponded to that of T49 in Alb A. The substitution site, lysine-->glutamic acid at the position 372, was revealed by sequence determination of the variant peptide purified by reversed-phase HPLC.

Stimulated rapid expression in vitro for early detection of in vivo T-cell receptor mutations induced by radiation exposure

The T-cell receptor (TCR) mutation assay for in vivo somatic mutations is a sensitive indicator of exposure to ionizing radiation. However, this assay cannot be immediately applied after radiation exposure because expression of a mutant phenotype may require as long as several months. In the present study, we eliminate this time lag by stimulating lymphocytes with a mitogen that can accelerate the turnover of TCR protein expression in T-cells. When lymphocytes obtained from healthy donors were irradiated with various doses of X-rays and cultured with human interleukin-2 after phytohemagglutinin (PHA) pulse stimulation, the mutant frequency (MF) of CD4+ T-cells increased dose dependently during the first 7 days, then decreased rapidly due to the growth disadvantage of mutant cells. This suggests that PHA stimulation can shorten the expression time of a mutant phenotype to within a week after radiation exposure. The relationship between radiation dose and TCR MF on the seventh day was best fitted by a linear-quadratic dose-response model. We applied this improved TCR mutation assay to gynecological cancer patients who received 5 days of localized radiotherapy, totaling about 10 Gy. The in vivo TCR MF in the patients did not change within a week after radiotherapy, whereas the in vitro TCR MF of PHA-stimulated lymphocytes from the same patients significantly increased 7 days after initiating culture. The estimated mean radiation dose to the peripheral blood lymphocytes of the cancer patients was about 0.9 Gy, based on the in vitro linear-quadratic dose-response curve. This estimated dose was close to that described in a previous report on unstable-type chromosome aberrations from cervical cancer patients after receiving the same course of radiotherapy. On the basis of these findings, we propose that the improved TCR mutation assay is a useful biological dosimeter for recent radiation exposure.

[Evaluation of angiotensin I converting enzyme gene polymorphism in patients with essential hypertension and coronary artery disease]

We investigated the role of the insertion (I)/deletion(D) polymorphism in the angiotensin I converting enzyme (ACE) gene in the cardiovascular diseases. First, we studied 520 patients who had undergone coronary angiography: including 220 patients with acute myocardial infarction, 98 patients with effort angina pectoris (> 75% stenosis), 83 patients with vasospastic angina and 119 controls with normal coronary artery. There was no difference in the frequency of ACE gene I/D allele or genotype II, ID and DD among the four groups. Second, we studied the correlation between ACE gene I/D polymorphism and the clinical characteristics in patients with essential hypertension. The distribution of I/D allele and genotype were similar in 140 essential hypertensives and 83 normal controls. In patients with DD genotype, age at onset of hypertension was lower and left ventricular mass index was greater than those in patients with ID and II, although blood pressure levels and the severity of damage to other organs-were similar in the three groups. Further, 66 patients with essential hypertension were classified into 35 salt-sensitive and 31 salt-resistant patients according to changes in mean blood pressure during a week of low salt diet followed by a week of high salt diet. The frequency of I allele was significantly higher in the salt-sensitive group than in the salt-resistant group. In conclusion, ACE gene I/D polymorphism is not associated with coronary artery diseases. In patients with essential hypertension, the D allele was associated with early onset and left ventricular hypertrophy, while I allele was associated with salt sensitivity.

Relationship between insulin resistance and endothelium-dependent vascular relaxation in patients with essential hypertension

The infusion of L-arginine induces the production of nitric oxide and stimulates the immediate secretion of insulin. To examine the relationship between insulin resistance and endothelium-dependent vascular relaxation in patients with essential hypertension, we evaluated the renal and insulin responses to L-arginine, 500 mg/kg infused intravenously over 30 minutes, in 23 patients with mild essential hypertension who were neither obese nor diabetic and in 20 normotensive control subjects. We found no difference between the two groups in blood glucose or insulin in the fasting condition. The renovascular relaxation induced by L-arginine was significantly less in patients with essential hypertension than in normotensive control subjects. The increase in plasma cyclic GMP in response to L-arginine was lower in hypertensive patients than in normotensive subjects. Although the serum concentrations of glucose in response to L-arginine were similar in the two groups, the serum insulin response of the essential hypertensives was significantly higher than that of the normotensive subjects. In all subjects, the peak cyclic GMP response to L-arginine was significantly correlated with the peak delta glucose/ delta insulin ratio response to L-arginine (r = .69, P < .001). Findings suggested that an impairment of endothelium-dependent renal vascular relaxation and a reduced sensitivity to insulin are present in patients with essential hypertension. A link may be present between the abnormality of the L-arginine/nitric oxide/cyclic GMP pathway and insulin resistance in patients with essential hypertension.

Optical resolution of phenylthiohydantoin-amino acids by capillary electrophoresis and identification of the phenylthiohydantoin-D-amino acid residue of [D-Ala2]-methionine enkephalin

This is an initial report to propose a protein sequence analysis system with DL differentiation using capillary electrophoresis (CE). This system consists of a protein sequencer and a CE system. After fractionation of phenyl-thiohydantoin (PTH)-amino acids using a protein sequencer, optical resolution for each PTH-amino acid is performed by CE using some chiral selectors such as digitonin, beta-escin and others. As a model peptide, [D-Ala2]-methionine enkephalin (L-Tyr-D-Ala-Gly-L-Phe-L-Met), was used and the sequence with DL differentiation was determined, with the exception of the fourth amino acid, L-Phe, using our proposed system.

In vivo modification of GABAA receptor with a high dose of pyridoxal phosphate induces tonic-clonic convulsion in immature mice

The biologic cofactor, pyridoxal-5'-phosphate (PLP), is responsible for tonic-clonic convulsion in immature mice. The mechanisms underlying such convulsive fits induced by administration of a single high dose of PLP were studied. The administration of PLP resulted in a 13% increase of PLP in the P2 fraction compared to control P2, and the calculated data suggested that membrane bound PLP increased over 31% (approximately 1 microM). The P2 fraction of administered mice was treated with [3H]NaBH4 and analyzed by SDS-polyacrylamide gel electrophoresis. The radioactivity was mainly incorporated into a 52 kDa protein which corresponded to a GABAA receptor subunit. The addition of PLP in vitro competitively inhibited [3H]GABA binding as well as [3H]flunitrazepam binding to synaptic membranes in a concentration-dependent manner, and 50% inhibition was achieved with 1 mM PLP. The results obtained in the present study demonstrate that PLP was rapidly permeable into the brain through the immature blood-brain barrier and then bound directly to GABAA receptor. It is probable that specific amino groups of lysine residues on the GABAA receptor react in vivo with PLP to form Schiff bases, and that the in vivo modification of the receptor produces a degeneration of GABAergic neurotransmission leading to the onset of a convulsive fit.

A soluble neurite outgrowth molecule in bovine brain

A neurite outgrowth molecule was purified from soluble fraction of bovine brain by reversed-phase column HPLC following concanavalin A (Con A)-affinity chromatography. This molecule was a 74kDa (named sGP74) and clearly reacted with the monoclonal antibody HNK-1. The amino acid sequences of N-terminal portion and peptides derived from trypsin digests of sGP74 were nearly identical to those of rat brain ankyrin-binding protein (ABGP186) that is a member of immunoglobulin superfamily with adhesive function. Our results suggest that sGP74 preserves multiple immunoglobulin-like domains and is released from an extracellular site of ABGP186.

Assay of vitamin B6 in human plasma with graphitic carbon column

A high performance liquid chromatographic (HPLC) procedure for measuring pyridoxal-5'-phosphate (PLP) and certain forms of B6 vitamers in plasma is presented here. This HPLC procedure consisted of a single graphitic carbon column with a fluorescence detector employing an isocratic eluent (15% acetonitrile: 1% perchloric acid: 0.05% sodium bisulfite). The graphitic carbon column is useful in acidic eluent without deteriorization. The relatively low fluorescent intensity of PLP under acidic conditions is improved by its derivatization with bisulfite in the eluent during chromatographic separation. Using this procedure, the detection limit of PLP is 50 fmol, and an aliquot of 5-50 microL of human plasma is required giving satisfactorily precise results within 5 min. We applied this method to the determination of PLP and certain B6 vitamers in human plasma after oral supplementation of pyridoxine.

Analysis of Con A-binding glycoproteins in synaptosomal membranes

Concanavalin A (Con A)-binding proteins obtained from solubilized synaptosomal membranes of bovine brain were analyzed by two-dimensional electrophoresis (2DE), and were identified by peroxidase conjugated Con A (Con A-peroxidase staining), after transfer from 2DE gel to nitrocellulose paper. The Con A-binding proteins were resolved up to 40 spots, ranging in isoelectric points (pI) from 4.5 to 8.0 and molecular weight (MW) from 10 kDa to 120 kDa. Most of the Con A-binding proteins were streaked across a pH gradient and/or exhibited as multiple spots, indicating broad charge and molecular weight heterogeneity. The presence of protein groups that showed high affinities for Con A were revealed. Most interesting group (named GP51), which consisted of seven spots separated horizontally in charge heterogeneity (pI5.85-7.5) with MW 51 kDa, was characterized by its binding to an immobilized protein A gel. This implies that GP51 is related to immunoglobulins and/or GP51 may be a new member of the immunoglobulin supergene family.

Detection of abnormal haemoglobin by capillary electrophoresis and structural identification

Haemoglobin obtained from a male adult Ghanian with retinopathy, which was probably caused by haemoglobinopathy was analysed by capillary electrophoresis (CE) for clinical diagnosis. Two major peaks, which were in the ratio of nearly one, were detected. The elution times of these peaks (HbXI and HbXII) were faster than that of normal haemoglobin (HbA). The existence of two different abnormal types of haemoglobin was clear in the patient blood. The following sequence analysis revealed that the first peak (HbXI) was HbC and the second (HbXII) was HbS on the electropherogram, and that the patient was a heterozygote of HbS and HbC (HbSC disease). One of the diagnostic processes in a haemoglobin disease was shown by the combined use of CE, HPLC and a protein sequencer.

Effects of superoxide anions on red cell deformability and membrane proteins

The effect of superoxide anions (O2-) on red blood cells (RBC) deformability and membrane proteins was investigated using hypoxanthine-xanthine oxidase system. Exposure of RBC to O2- caused a marked decrease in RBC deformability with a concomitant increase in cell volume and shape changes. The RBC exposed to O2- also displayed pronounced degradation of membrane proteins such as band 3 protein and spectrin; new bands of low molecular weight products appeared as the original membrane proteins tended to diminish, without the appearance of high molecular weight products. Since the membrane proteins are involved in processes regulating membrane properties such as permeability and viscoelasticity, the decreased deformability induced by O2- may be attributable to changes in membrane proteins. Interestingly, resealed ghosts exposed to O2- did not show any significant change in membrane proteins, which suggests the existence of further generation of O2- and subsequent production of other active oxygen species mediated by O2(-)-initiated autoxidation of hemoglobin in intact RBC. Furthermore, electrophoretic analysis suggested that active oxygens increased the endogenous proteolytic susceptibility of RBC. In conclusion, a close linkage was suggested between RBC deformability and the membrane proteins.

Analysis and separation of synaptosomal membrane proteins

Synaptosomal membrane proteins solubilized with 8% CHAPS-8 M urea were analyzed with two-dimensional electrophoresis (2DE). The membrane proteins were resolved up to 250 spots on a 2DE map, ranging in isoelectric points (pI) from 3.5 to 10.0 and molecular weights (MW) from 10 kDa to 200 kDa. Comparison of the mapped proteins of synaptosomal membranes with those of myelin and mitochondrial membranes revealed that synaptosomal membrane proteins were characteristic in the area of pI from 4.0 to 7.5 and MW from 20 kDa to 130 kDa, and that at least 30 spots were synaptosomal membrane-specific proteins. Most of these 30 proteins have not been previously described, named, and characterized. Serial numbers (from SY1 to SY30) were assigned to the proteins on the map in order to investigate them systematically. A preliminary attempt to separate synaptosomal membrane proteins was carried out using a reversed-phase HPLC system. Several proteins could either be isolated or enriched. SY10 (pI 4.6; MW 56 kDa) was one of these proteins, and was of particular interest for its unusual behavior on the reversed-phase column, and for its binding to an immobilized protein A-gel.

Point substitutions in Japanese alloalbumins

We have completed the structural study of five rare types of inherited albumin variants (alloalbumins) discovered in the Biochemical Genetics Study of 15,581 unrelated children in Hiroshima and Nagasaki. We have also identified the structural change in five other alloalbumin specimens detected during clinical electrophoresis of sera from Japanese living near Tokyo. Each of the five albumin variants from Nagasaki and Hiroshima has a single amino acid substitution. All of these substitutions differ, and none has been reported in non-Japanese populations. No instances of proalbumin variants or of albumin B (the most frequent alloalbumins in Caucasians) were detected in the children in Hiroshima and Nagasaki. However, one instance of a variant proalbumin and two examples of albumin B occurred in Japanese from the vicinity of Tokyo. In addition a previously unreported point substitution was found in albumin Tochigi, which is present in two unrelated persons from Tochigi prefecture. Four of the point mutations in the Japanese alloalbumins are in close proximity in a short segment of the polypeptide chain (residues 354-382) in which three additional point substitutions have been reported in diverse populations. These results, combined with earlier data, suggest that point substitutions are grouped in certain segments of the albumin molecule.

Identical structural changes in inherited albumin variants from different populations

Alloalbuminemia is rare and has a cumulative frequency of only approximately 1 in 3,000 in Europeans and Japanese. The worldwide ethnic and geographic distribution of certain albumin genetic variants appears to be nonrandom. Moreover, we have found that structurally identical variants may occur at different frequencies in ethnically distinct populations, presumably owing to independent mutations. In this study, albumin B and two types of proalbumins, which as a group are the most common European albumin variants, have also been found in Asians. We have identified the amino acid substitution characteristic of albumin B (glutamic acid----lysine at position 570) in alloalbumins from six unrelated individuals of five different European descents and also in two Japanese and one Cambodian. The two types of proalbumins most common in Europe (Lille type, arginine----histidine at position -2; Christchurch type, arginine----glutamic acid at position -1) also occur in Japan. These results provide evidence for independent mutations at single sites in the albumin genome. The clustering of these and of several other amino acid exchanges in certain regions of the albumin molecule suggests two possibilities: that certain sites are hypermutable or that mutants involving certain sites are more subject to selection than mutants involving others.

The same substitution, glutamic acid----lysine at position 501, occurs in three alloalbumins of Asiatic origin: albumins Vancouver, Birmingham, and Adana

A strategy is described for identifying structural changes in genetic variants of human serum albumin (alloalbumins). By use of this strategy we have determined an amino acid substitution in three alloalbumins of Asiatic origin. The same amino acid exchange, glutamic acid----lysine at position 501, occurs in albumins Vancouver and Birmingham, both from families that migrated from northern India, and also in albumin Adana from Turkey. This exchange corresponds to a single base mutation in the codon GAG to AAG and accords with the slow mobility of the three albumins at pH 8.6. Each of the three alloalbumins had been reported to be a new variant, yet they have the same substitution. These results emphasize the need for structural study of genetic variants that have been differentiated only by nonspecific physical criteria such as dye binding and electrophoretic mobility. We know of no other description of the substitution involved in an alloalbumin originating from the Indian subcontinent. However, the same change of glutamic acid----lysine at position 501 may be present in several other named variants reported for populations in north India and the surrounding regions.

Analysis of the mechanism, rate, and sites of proteolytic cleavage of human immunoglobulin D by high-pressure liquid chromatography

The high susceptibility of human immunoglobulin D to proteolytic degradation affects its biological function, metabolism, and immunoassay. High-pressure liquid chromatography was used to investigate the mechanism and rate of limited proteolytic cleavage of IgD and also to identify, isolate, and quantify the reaction products. Within 1 to 5 min, tryptic digestion of native IgD almost quantitatively yields a labile Fab fragment, a stable Fc fragment, and a highly charged peptide derived from the hinge region. A galactosamine-rich glycopeptide from the hinge region increases inversely as the Fab is largely degraded to a series of peptides within 1 hr. In contrast, the Fc and the high-charge peptide resist proteolysis for more than 24 hr. The initial sites of cleavage of IgD occur in the hinge region at exposed secondary structures predicted to be beta-turns. Concomitant with removal of the galactosamine-rich glycopeptide at its carboxyl terminus, the Fd fragment is rapidly and rather randomly degraded, but the light chain is somewhat more resistant than the Fd section of the delta heavy chain. This study of the rapid rate of proteolysis of IgD explains the rarity with which intact IgD is found in human sera. It also raises questions about immunoassay of IgD, which is usually measured with antisera against Fc. In vivo, proteolytic cleavage initiates the catabolism of circulating IgD and also affects the role and fate of IgD as an antigen receptor on the B-cell membrane.

Application of an automated tandem high-performance liquid chromatographic system to peptide mapping of genetic variants of human serum albumin

An automated tandem high-performance liquid chromatographic system was developed for peptide mapping of very large proteins. The method was applied systematically to the peptide mapping analysis of four genetic variants of human serum albumin, and amino acid substitutions in three of them could be identified. In two variants the amino acid substitutions were identified in both homozygote and heterozygote specimens. By this peptide mapping method at least 80% of the total amino acid residues can be screened rapidly. The method is especially useful for establishing the molecular basis of genetic relationships among protein variants found in different populations.

Amino acid sequence of human plasma alpha 1B-glycoprotein: homology to the immunoglobulin supergene family

The complete amino acid sequence has been determined for alpha 1B-glycoprotein (alpha 1B), a protein of unknown function present in human plasma. This protein (Mr approximately equal to 63,000) consists of a single polypeptide chain N-linked to four glucosamine oligosaccharides. The polypeptide has five intrachain disulfide bonds and contains 474 amino acid residues. Analysis of the amino acid sequence by several computer programs shows that alpha 1B exhibits internal duplication and consists of five repeating structural domains, each containing about 95 amino acids and one disulfide bond. alpha 1B has a unique amino acid sequence. However, several domains of alpha 1B, especially the third, show statistically significant homology to variable regions of certain immunoglobulin light and heavy chains. alpha 1B also exhibits sequence similarity to other members of the immunoglobulin supergene family such as the receptor for transepithelial transport of IgA and IgM and the secretory component of human IgA. Because of its internal duplication and its sequence homology to immunoglobulin-like proteins, alpha 1B appears to have evolved from an ancestral gene similar to that of the immunoglobulin supergene family.

Automated tandem high-performance liquid chromatographic system for separation of extremely complex peptide mixtures

We have developed an automated tandem chromatography system, which consists of a combination of ion-exchange column chromatography and reversed-phase column chromatography. The system is composed of two independent high-performance liquid chromatography assemblies, in each of which programmed elution is carried out by a computer-assisted controller. A peptide mixture is applied to an ion-exchange column and is eluted in a stepwise manner. The eluent from the first column is introduced directly into the second, reversed-phase column, which is connected in tandem through a tee tube. After application of two column volumes of the eluent, reversed-phase chromatography is performed by linear gradient elution. Stepwise elution for ion-exchange chromatography and the gradient elution for reversed-phase chromatography are synchronized by a computer program. The resolving power and the reproducibility of the method were tested by using a tryptic digest of human ceruloplasmin [molecular weight 132 000 daltons (132 kDa)]. By this method, the digest was resolved reproducibly into several hundred peaks within 16 h. All of the four glycopeptides expected to be obtained by tryptic digestion were purified easily from the whole digest of the protein. Comparison of the peptide maps between a single-chain and a degraded form of ceruloplasmin facilitated the identification of two tryptic peptides, derived from the carboxyl-terminal regions of 67 kDa and 50 kDa fragments of the degraded form, which lack the carboxyl-terminal arginine and lysine residues, respectively. The method may be applicable to comparative peptide mapping of very large proteins exhibiting molecular microheterogeneity, such as carbohydrate or genetic variants; it also can be used complementarily for sequence support of DNA sequencing as well as for preparative purification of peptides as a strategy of protein sequencing of very large proteins.

Purification of glycopeptides of human plasma proteins by high-performance liquid chromatography

The combination of gel permeation chromatography and high-performance liquid chromatography proves to be very effective for the purification of high-molecular-weight glycopeptides containing a single glycan, that have been difficult to separate by other procedures. In order to facilitate comparison of the chromatographic properties of glycopeptides derived from a variety of proteins and having different structures, identical procedures were used for their purification. The method was applied to a series of human plasma proteins, including immunoglobulin D, ceruloplasmin, hemopexin, beta-2-glycoprotein I, 3.1S alpha-2-leucine-rich glycoprotein, and alpha-1-B-glycoprotein. All the purified glycopeptides were placed in the protein structure of these plasma proteins. In several cases the carbohydrate structure has been determined by collaborating groups. Immunoglobulin D is the first example of a glycoprotein whose entire primary structure has been defined by utilizing a a single protein source. Furthermore, hemopexin and 3.1S alpha-2-leucine-rich glycoprotein were both found to contain GalN oligosaccharide, which had not previously been identified in these proteins. The method was also used to identify the oligosaccharide that is missing in a carbohydrate variant of ceruloplasmin.

Large scale preparation and crystallization of neuron-specific enolase

A simple method has been developed for the large scale purification of neuron-specific enolase [EC 4.2.1.11]. The method consists of ammonium sulfate fractionation of brain extract, and two subsequent column chromatography steps on DEAE Sephadex A-50. The chromatography was performed on a short (25 cm height) and thick (8.5 cm inside diameter) column unit that was specially devised for the large scale preparation. The purified enolase was crystallized in 0.05 M imidazole-HCl buffer containing 1.6 M ammonium sulfate (pH 6.39), with a yield of 0.9 g/kg of bovine brain tissue.

A rapid separation of S100 subunits by high performance liquid chromatography: the subunit compositions of S100 proteins

The subunits of S100 protein were dissociated and separated from each other by high performance liquid chromatography on a macroreticular poly-styrene resin, using an acetonitrile-trifluoroacetic acid solvent system. The separation was completed within 80 min in monitoring the effluent at 210 and 280 nm, allowing a rapid and sensitive identification of each S100 protein in terms of subunit composition, and a simultaneous purification of subunits. The method enabled to estimate the subunit compositions of S100a, S100b, and S100a0 protein purified from bovine brain, and revealed a micro-heterogeneity of S100 subunits as applied to the mixtures of S100 protein prepared from bovine, human and rat brain.

Separation of extremely acidic proteins, S-100 proteins and calmodulin, in some bovine tissues and mammalian brains by two-dimensional electrophoresis in the absence of denaturing agents

Extremely acidic proteins in bovine brain extracts, including S-100 proteins and calmodulin, were separated by two-dimensional electrophoresis in the absence of denaturing agents. The pattern was compared with the patterns of other bovine tissue extracts and also with those of brain extracts of other species. S-100 proteins (S-100 a and S-100 b) were specifically abundant in nerve tissues. A small amount of S-100 proteins was detected in heart extract. Extracts of liver and kidney did not have S-100 proteins, but each showed the distribution pattern of acidic proteins characteristic to the tissue. Calmodulin seemed to be present in all tissue extracts examined. Comparisons of the patterns of acidic proteins in brain extracts of various animal species suggest that S-100 proteins are more "variable" in structure than calmodulin.

Structural relation of two S-100 proteins in bovine brain; subunit composition of S-100a protein

Dodecyl sulfate/urea/polyacrylamide gel electrophoresis of S-100a protein, one of the two major components of the brain-specific S-100 protein, indicated the presence of two different subunits in the protein. These subunits (alpha and beta subunits) were purified from the aminoethylated protein by column chromatography on Sephadex G-75, and the purified subunits were subjected to analyses. The results have shown that S-100a protein is a dimer of alpha and beta subunits, with each subunit having a molecular weight of approximately 10500. Structural comparison of these subunits with the subunit of S-100b protein, the other component of S-100 protein consisting of two identical subunits with known amino acid sequence, has revealed that the beta subunit and the subunit of S-100b protein are identical, so that S-100a protein is related to S-100b protein by sharing one of the subunits as a common structural constituent.

A new acidic protein in porcine brain

An extremely acidic protein has been isolated in a purified form from porcine rain extract, by (NH4)2SO4 fractionation followed by column chromatography on DEAE-Sephadex A-50 and on Sephadex G-75. The purified protein was tentatively named as glutamic acid-rich protein because it was characterized by its remarkably high content of glutamic acid which accounted for 49% of the total amino acid composition. The protein appeared to be a single polypeptide chain with a molecular weight of 56 000-58 000, and had an isoelectric point of 4.6. The N-terminal amino acid sequence was Asp-Glu-Pro-Pro-Ser-Glu-Gly. The immunochemical analysis using rabbit antiserum prepared to the porcine protein has suggested that it is present in the brain of human, cow, cat, dog and goat as well as in various goat organs including liver, kidney, heart, small intestine and spleen.