Hydrogen peroxide-induced apoptosis in HL-60 cells requires caspase-3 activation

Apoptosis has been associated with oxidative stress in biological systems. Caspases have been considered to play a pivotal role in the execution phase of apoptosis. However, which caspases function as executioners in reactive oxygen species (ROS)-induced apoptosis is not known. The present study was performed to identify the major caspases acting in ROS-induced apoptosis. Treatment of HL-60 cells with 50 microM hydrogen peroxide (H2O2) for 4 h induced the morphological changes such as condensed and/or fragmented nuclei, increase in caspase-3 subfamily protease activities, reduction of the procaspase-3 and a DNA fragmentation. To determine the role of caspases in H2O2-induced apoptosis, caspase inhibitors, acetyl-Tyr-Val-Ala-Asp-chloromethyl ketone (Ac-YVAD-cmk), acetyl-Asp-Glu-Val-Asp-aldehyde (Ac-DEVD-CHO) and acetyl-Val-Glu-Ile-Asp-aldehyde (Ac-VEID-CHO), selective for caspase-1 subfamily, caspase-3 subfamily and caspase-6, respectively, were loaded into the cells using an osmotic lysis of pinosomes method. Of these caspase inhibitors, only Ac-DEVD-CHO completely blocked morphological changes, caspase-3 subfamily protease activation and DNA ladder formation in H2O2-treated HL-60 cells. This inhibitory effect was dose-dependent. These results suggest that caspase-3, but not caspase-1 is required for commitment to ROS-triggered apoptosis.

Fluorescence derivatizing procedure for 5-hydroxytryptamine and 5-hydroxyindoleacetic acid using 1,2-diphenylethylenediamine reagent and their sensitive liquid chromatographic determination

A pre-column derivatization method using a fluorogenic reagent, 1,2-diphenylethylenediamine (DPE) was studied for the sensitive HPLC determination of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA), which are biosubstances used in the diagnosis of several diseases. For the quantitative determination, the biogenic indole compounds were converted to their corresponding fluorescent derivatives with DPE in the presence of potassium hexacyanoferrate (III) at room temperature, and then the derivatives were separated by reversed-phase liquid chromatography with fluorescence detection. The chromatographic detection limits of the fluorescent peaks at a signal-to-noise ratio of 3 were 0.3 fmol for 5-HT and 0.2 fmol for 5-HIAA. The proposed method permits the simultaneous quantification of 5-HT and 5-HIAA at concentrations higher than 2.4 nM in human urine without a clean-up procedure.

The possible role of interleukin (IL)-12 and interferon-gamma-inducing factor/IL-18 in protection against experimental Mycobacterium leprae infection in mice

Cell-mediated immunity participates in host defense against mycobacterial infection. Both interleukin 12 (IL-12) and interferon-gamma-inducing factor (IGIF/IL-18), produced mainly by macrophages, play a critical role in expression of cell-mediated immunity. To investigate the role of IL-12 and IGIF/IL-18 in vivo, we examined cytokine profile, bacterial growth, and the potential benefit of cytokine therapy in susceptible and resistant mice infected with Mycobacterium leprae. The early expression of IL-12 p40 and IGIF/IL-18 at the site of inoculation was found in resistant mice 3-72 h after the infection, but not in susceptible mice. Both strains of mice did not show expression of IFN-gamma and IL-4. IL-12 administration resulted in a significant reduction of bacterial counts in mice with established M. leprae infection. The results imply that susceptible mice exhibit decreased expression of type 1 helper T (Th1) response without reciprocal increased Th2 response and show responsiveness to exogenous IL-12. IL-12 therapy may be a possible rationale for treatment of M. leprae infection.

Peripheral blood levels of matrix metalloproteases-2 and -9 are elevated in patients with acute coronary syndromes

OBJECTIVES

This study was sought to investigate whether peripheral blood levels of matrix metalloproteases (MMPs) are affected in patients with acute coronary syndromes (ACS).

BACKGROUND

Synthesis of MMPs has been reported in coronary atherosclerotic lesions in patients with unstable angina (UA), suggesting a pathogenic role of MMPs in the development of ACS.

METHODS

Using sandwich enzyme immunoassay, serum MMP-2 and plasma MMP-9 were measured in 33 patients with ACS (22 with acute myocardial infarction [AMI], 11 with UA), 17 with stable effort angina (EA) and 17 normal control subjects.

RESULTS

Serum MMP-2 in patients with UA and AMI on day 0 was two times greater than that in control subjects, and patients with EA showed higher MMP-2 levels than those in control subjects. Plasma MMP-9 in patients with UA and AMI on day 0 was elevated by threefold and twofold versus that in control subjects, respectively. In patients with UA and AMI who underwent medical treatment (n = 11 and 13, respectively), MMP-2 elevation was sustained until day 7. In patients with UA, MMP-9 elevation on day 0 was followed by a gradual decrease toward the control range up to day 7. Some patients with AMI showed a transient MMP-9 elevation with a peak on day 3, whereas in others, MMP-9 levels were significantly elevated on day 0 and remained higher than those in control subjects up to day 3.

CONCLUSIONS

Serial changes in serum MMP-2 and plasma MMP-9 were documented in patients with ACS. These findings provide an insight into the molecular mechanism of plaque destabilization.

Overexpression of S-adenosylmethionine decarboxylase (SAMDC) in early Xenopus embryos induces cell dissociation and inhibits transition from the blastula to gastrula stage

Xenopus early embryos contain relatively low levels of S-adenosyl-methionine decarboxylase (SAMDC) and its mRNA. When SAMDC mRNA was injected into Xenopus embryos, it was preserved until the blastula stage and induced a large increase in SAMDC activity. The SAMDC-overexpressed embryos developed normally until the blastula stage but at the early gastrula stage cells which received the mRNA, dissociated autonomously and stopped synthesizing protein. In a hypotonic medium, the dissociated cells, and hence whole embryos, autolyzed. However, in isotonic media dissociated cells did not autolyze, although they did not divide and their DNA and RNA synthesis activity was greatly inhibited. The effects of SAMDC overexpression were abolished by coinjection of ethylglyoxal-bis(guanylhydrazone) (EGBG), a specific inhibitor of SAMDC. In SAMDC-overexpressed embryos the level of putrescine decreased and that of spermidine increased, though to limited extents, resulting in a considerable decrease in the putrescine/spermidine ratio. However, direct injection of spermidine did not mimic the effect of SAMDC overexpression, and putrescine coinjected with SAMDC mRNA to maintain the normal putrescine/spermidine ratio did not rescue the embryos. Conversely, the level of S-adenosylmethionine (SAM) greatly decreased and coinjection of SAM, which restored the level of SAM, rescued the embryos. We concluded that in SAMDC-overexpressed embryos a SAM-deficient state was induced and this caused cell dissociation and inhibition of transition from the blastula to gastrula stage. We suggest that the SAM-deficient embryos obtained in the present study provide a unique system for studying the cellular control mechanism underlying the blastula-gastrula transition.

Genomic organization and mapping of the human activin receptor type IIB (hActR-IIB) gene

Activins, members of a family of proteins that includes transforming growth factor-beta (TGF-beta), are gonadal polypeptide hormones that stimulate secretion of follicle-stimulating hormone (FSH). During large-scale sequencing analysis of a 1.2-Mb fragment of human genomic DNA on 3p22-p21.3, we found the gene encoding activin receptor type IIB (hActR-IIB). Comparison of its reported cDNA sequence with this genomic sequence showed that the hActR-IIB gene consists of 11 exons and spans about 30 kb of genomic DNA.

A compact UHV X-ray diffractometer for studying surfaces and interfaces

A compact ultra-high-vacuum (UHV) X-ray diffractometer for surface glancing X-ray scattering has been constructed. All the equipment, including a rotating-anode source of 18 kW and a UHV specimen chamber, is arranged on one optical table of dimensions 70 x 90 cm. The specimen chamber is 14 cm in diameter and 20 cm high and can be evacuated up to 3 x 10(-8) Pa. It is equipped with two Be windows of thicknesses 0.2 and 0.4 mm. Specimen orientation in the vacuum is controlled from the outside. The specimen can be heated up to 773 K. The chamber has two evaporation cells and can be used for in situ observations of growing crystal surfaces. Using this instrument, we observed a mechanically polished Ag surface and successfully made an in situ observation of the layer-by-layer growth of a PbSe(111) surface. The instrument will be useful for preliminary experiments using laboratory sources, prior to final measurements at synchrotron radiation facilities.

[Geographical distribution of Mycobacterium avium complex in environment and serovars of Mycobacterium avium complex isolates from patients with and without AIDS]

Mycobacterium avium complex (MAC) organisms have been isolated from water and soil. It is now generally accepted that environmental sources, especially natural waters, are the reservoirs for most human infections caused by MAC. Previously, we reported that M. avium and M. intracellular were distributed predominantly in the eastern and western part of Japan, respectively. To clarify the factor(s) of the difference, the following experiment was undertaken. MAC was isolated from soil samples collected in Tokai, Kinki and Chugoku districts, by the method of Ichiyama et al. MAC isolates were identified by AccuProbe Confirmation and Identification tests, together with some conventional tests. Seven (11.7%) of 60 isolates were identified as M. avium, twenty (33%) as M. intracellulaer and 33 (55%) as MAC-like organisms. Therefore, it was not found that the difference in the geographical distribution between soil MAC and disease-associated MAC. MAC-like strains possess MAC-specific alpha antigen, and biological and biochemical features of MAC. They reacted with the AccuProbe MAC but not with the AccuProbe M. avium and M. intracellulare. Sequencing analysis of 16s RNA gene implies that MAC-like strains show an intermediate sequence pattern of M. avium and M. intracellulare. HPLC patterns of these strains were compatible with those of MAC. It is known that the major serovars of MAC isolates from patients with or without AIDS are different. Serological aspects in this respect are not yet elucidated well in Japan. The major serovars of MAC from patients with AIDS are 4 and 8 in the USA and Australia, 6 and 4 in Sweden, and 8/21 and 8 in Germany. On the other hand, the major serovars of MAC from patients without AIDS are 8 and 16 (15) in the USA and 6 and 1 in Sweden. According to out recent study the major serovars of MAC from non-AIDS patients are 1 and 8 in the eastern part and 16 and 14 in the western part of Japan. In the present study, 38 MAC isolates from sputum, stool and blood and AIDS patients were identified. All of the isolates were identified as M. avium. Serovars of 15 strains were 4 (4 strains), 8 (3 strains), 9 (3 strains), 3 (2 strains), Darkin (2 strains) and 1 (1 strain). Therefore, it seems that the major serovars of the Japanese MAC strains from AIDS patients are similar to those of the American MAC strains from such patients.

A new Drosophila ultraviolet light-damaged DNA recognition endonuclease that selectively nicks a (6-4) photoproduct site

We have previously described the purification of an ultraviolet light (UV) damage-specific DNA-binding protein from Drosophila melanogaster, designated D-DDB P1 [Nucleic Acids Res., 23 (1995) 2600-2607]. Here, we obtained highly purified D-DDB P1 from Drosophila Kc cells, and we found that D-DDB P1 is also a nuclease. D-DDB P1 can selectively bind to pyrimidine (6-4) pyrimidone photoproducts, and in the presence of Mg++, D-DDB P1 can catalyze an incision immediately on the 3' and 5' sides of the (6-4) photoproduct site.

Monte Carlo simulation of DNA strand-break induction in supercoiled plasmid pBR322 DNA from indirect effects

We present a new Monte Carlo simulation code system (DBREAK) of the detailed events that occur when ionizing radiation interacts with water and DNA molecules. The model treats the initial energy deposition by radiation, the formation of chemically active species, subsequent diffusion-controlled chemical reactions, and induction of DNA strand breaks. DBREAK assumes one-hit single-strand break (SSB) and two-hit double-strand break (DSB) mechanisms. A high-resolution model of plasmid DNA structure has been introduced. The calculated results are compared with the results of previously performed experiments of the same type. Under aerobic conditions, 89.4% of the DNA damage was attributed to OH-radical and 10.5% and 0.1% to eaq- and H, respectively. We also compared the differences between liquid-water track structure and gas-phase-water track structure. The calculated yield of SSBs by liquid-water track structure exceeded that of gas-phase-water track structure by a factor of 1.2.

A structure-specific endonuclease from cauliflower (Brassica oleracea var. botrytis) inflorescence

A protein with structure-specific endonuclease activity has been purified to near homogeneity from cauliflower ( Brassica oleracea var. botrytis) inflorescence through five successive column chromatographies. The protein is a single polypeptide with a molecular mass of 40 kDa. Using three different branched DNA structures (flap, pseudo-Y and stem-loop) we found that the enzyme, a cauliflower structure-specific endonuclease, cleaved the single-stranded tail in the 5'-flap and 5'-pseudo-Y structures, whereas it could not incise the 3'-flap and 3'-pseudo-Y structures. The incision points occur around the single strand-duplex junction in these DNA substrates and the enzyme leaves 5'-PO4 and 3'-OH termini on DNA. The protein also endonucleolytically cleaves on the 3'-side of the single-stranded region at the junction of unpaired and duplex DNA in the stem-loop structure. The structure-specific endonuclease activity is stimulated by Mg2+ and by Mn2+, but not by Ca2+. Like mammalian FEN-1, the protein has weak 5'-->3' double-stranded DNA-specific exonuclease activity. These results indicate that the cauliflower protein is a plant structure-specific endonuclease like mammalian FEN-1 or may be the plant alternative.

Chromosome aberrations in bone marrow cells of C3H/He mice at an early stage after whole-body irradiation

Murine acute myeloid leukemia is characterized by chromosome 2 aberrations, and genesis of the marker chromosome 2 by radiation is suspected to be an initiating event of radiation leukemogenesis. A detailed analysis of the type and frequency of chromosome 2 aberrations in murine bone marrow cells at an early stage after irradiation is provided here. A total of 40 male C3H/He mice was exposed to 137Cs gamma-ray at a dose of 1, 2 or 3 Gy, and sacrificed 24 hours after irradiation. Metaphase samples prepared from bone marrow cells were Q-banded for karyotyping or painted with DNA probes specific to chromosome 2. In 5 mice analyzed by karyotyping, one mouse showed high frequency of the marker aberrations as well as other chromosome 2 aberrations. Chromosome painting analysis for the rest of the mice also detected 3 animals showing significantly high frequencies of chromosome 2 aberrations. Dose-dependence of the frequencies was observed even among those mice that tended to be sensitive. The results indicated that there was a subgroup of mice carrying hypersensitive chromosome 2. The subgroup could be leukemia-sensitive if radiation-induced chromosome aberrations are responsible for an early change in myeloid leukemogenesis.

Analysis of the incidence of solid cancer among atomic bomb survivors using a two-stage model of carcinogenesis

A two-stage stochastic model for carcinogenesis was used to analyze the incidence of cancer of the lung, stomach and colon in the cohort of atomic bomb survivors. We fitted the model assuming that acute exposure to radiation results in the creation of initiated cells that are added to the pool of spontaneously initiated cells. In the cancers analyzed, with the exception of lung cancer in females, we found no evidence that radiation-induced initiation was dependent upon age at exposure. In contrast, we found that spontaneous initiation was dependent upon age at exposure in the cancers analyzed except stomach cancer among males. Because exposure to radiation in this cohort occurred at the same time for all members of the cohort, age at exposure is exactly correlated with birth cohort, and the dependence of spontaneous initiation on age at exposure is a reflection of the cohort effects seen in these cancers in Japan. Even without a dependence of radiation-induced initiation on age at exposure, the two-stage model can explain the temporal behavior of the excess relative risk with age at exposure and time since exposure. In particular, the model predicts that excess relative risk is highest among those exposed as children. Moreover, since radiation-induced initiation is not higher among those exposed as children, the excess relative risk in this group is not due to an inherently higher sensitivity to radiation. Our biologically based approach provides another perspective on the temporal behavior of risk after acute exposure to ionizing radiation.

Decreased expression of cytokines that induce type 1 helper T cell/interferon-gamma responses in genetically susceptible mice infected with Mycobacterium avium

Mycobacterium avium is an intracellular microorganism that infects and multiplies within macrophages. Cell-mediated immunity plays an important role in host defense. Two cytokines, interleukin 12 (IL-12) and interferon-gamma-inducing factor (IGIF), produced mainly by macrophages, are critical for the development of type 1 helper T (Th1) cell/interferon-gamma (IFN-gamma) responses and cell-mediated immunity. In this report, by using a mouse model of disseminated M. avium infection, we demonstrate that genetically susceptible BALB/c mice show decreased expression of IL-12 and IGIF in association with a diminished IFN-gamma/Th1 response. Conversely, resistant DBA/2 mice exhibited increased expression of IL-12, IGIF, and IFN-gamma. In both strains of infected mice, the level of IL-4/Th2 response was similar. These results suggest that decreased expression of IL-12 and IGIF leads to a diminished Th1 response without reciprocal enhanced Th2 responses in susceptible mice.

Cloning and characterization of two human isozymes of Mg2+-independent phosphatidic acid phosphatase

We obtained two human cDNA clones encoding phosphatidic acid phosphatase (PAP) isozymes named PAP-2a (Mr = 32,158) and -2b (Mr = 35, 119), both of which contained six putative transmembrane domains. Both enzymes were glycosylated and cleaved by N-glycanase and endo-beta-galactosidase, thus suggesting their post-Golgi localization. PAP-2a and -2b shared 47% identical sequence and were judged to be the human counterparts of the previously sequenced mouse 35-kDa PAP(83% identity) and rat Dri42 protein (94% identity), respectively. Furthermore, the sequences of both PAPs were 34-39% identical to that of Drosophila Wunen protein. In view of the functions ascribed to Wunen and Dri42 in germ cell migration and epithelial differentiation, respectively, these findings unexpectedly suggest critical roles of PAP isoforms in cell growth and differentiation. Although the two PAPs hydrolyzed lysophosphatidate and ceramide-1-phosphate in addition to phosphatidate, the hydrolysis of sphingosine-1-phosphate was detected only for PAP-2b. PAP-2b was expressed almost ubiquitously in all human tissues examined, whereas the expression of PAP-2a was relatively variable, being extremely low in the placenta and thymus. In HeLa cells, the transcription of PAP-2a was not affected by different stimuli, whereas PAP-2b was induced (up to 3-fold) by epidermal growth factor. These findings indicate that despite structural similarities, the two PAP isozymes may play distinct functions through their different patterns of substrate utilization and transcriptional regulation.

Phosphatidic acid phosphatase from mammalian tissues: discovery of channel-like proteins with unexpected functions

Phosphatidic acid phosphatase (PAP) has long been known as a key enzyme involved in both glycerolipid biosynthesis and cellular signal transduction. The cDNA cloning of a plasma membrane-bound type 2 PAP has revealed the existence of a novel glycoprotein with six transmembrane domains. The type 2 PAP now represents an enzyme family consisting of Drosophila Wunen and rat Dri 42, which participate in germ cell migration and epithelial differentiation, respectively. Such novel functions of the type 2 PAP suggest the unexpected importance of lipids and/or their metabolic enzymes.

Promotion of transferrin folding by cyclic interactions with calnexin and calreticulin

Calnexin, an abundant membrane protein, and its lumenal homolog calreticulin interact with nascent proteins in the endoplasmic reticulum. Because they have an affinity for monoglucosylated N-linked oligosaccharides which can be regenerated from the aglucosylated sugar, it has been speculated that this repeated oligosaccharide binding may play a role in nascent chain folding. To investigate the process, we have developed a novel assay system using microsomes freshly prepared from pulse labeled HepG2 cells. Unlike the previously described oxidative folding systems which required rabbit reticulocyte lysates, the oxidative folding of transferrin in isolated microsomes could be carried out in a defined solution. In this system, addition of a glucose donor, UDP-glucose, to the microsomes triggered glucosylation of transferrin and resulted in its cyclic interaction with calnexin and calreticulin. When the folding of transferrin in microsomes was analyzed, UDP-glucose enhanced the amount of folded transferrin and reduced the disulfide-linked aggregates. Analysis of transferrin folding in briefly heat-treated microsomes revealed that UDP-glucose was also effective in elimination of heat-induced misfolding. Incubation of the microsomes with an alpha-glucosidase inhibitor, castanospermine, prolonged the association of transferrin with the chaperones and prevented completion of folding and, importantly, aggregate formation, particularly in the calnexin complex. Accordingly, we demonstrate that repeated binding of the chaperones to the glucose of the transferrin sugar moiety prevents and corrects misfolding of the protein.

Measurement of erythrocyte volumes in splenectomized horses and sham-operated horses at rest and during maximal exercise

Erythrocyte volumes of thoroughbred horses were measured. The volumes of splenectomized horses and sham-operated horses 2 hr after injection of 50Cr-tagged erythrocytes (at rest) and during maximal exercise were measured using the non-radioactive isotope 50Cr. Because splenic erythrocytes are released into circulation during exercise, it was estimated that the erythrocyte volumes of the sham-operated horses during maximal exercise are larger than those of the horses at rest. However, the erythrocyte volumes of the sham-operated horses at rest were about equal to those during maximal exercise. In the splenectomized horses, furthermore, erythrocyte volumes at rest and those at exercise were nearly equal. From these results, blood stored in the equine spleen is gradually mixed with circulating blood, and it was clarified that the phenomenon was completed within 2 hr. Although it is basically impossible to measure the circulating erythrocyte volume at rest using the erythrocyte tagged method, we observed that it is possible to measure the total erythrocyte volume using the 50Cr method. Also, the plasma volumes of the splenectomized horses during maximal exercise were found to be slightly smaller than those at rest. On the other hand, in the sham-operated horses, the plasma was decreased by a large quantity after maximal exercise. Therefore, it was suggested that the spleen participates in the phenomenon involving the disappearance of plasma from circulation due to exercise.

Monte Carlo simulation of physicochemical processes of liquid water radiolysis. The effects of dissolved oxygen and OH scavenger

The paper describes developments of the physicochemical part of a computer code system that estimates DNA strand break induction on plasmid pBR322 DNA. In order to test the reliability of the model, we evaluated the dielectric function and the time-dependent yield of chemical species in the presence of OH radical scavenger or dissolved oxygen. Results agree with measurements on the radiolysis of liquid water. When a hybrid model of a liquid inelastic cross-section and a vapour elastic cross-section is used, energy deposition by vibrational excitations is estimated to be approximately 11% of total energy deposition.

The embryonic and fetal effects in ICR mice irradiated in the various stages of the preimplantation period

Pregnant ICR mice were irradiated with 0.1-2.5 Gy 137Cs gamma rays at a dose rate of 0.2 Gy/min at 2, 48, 72 or 96 h postconception. In the mice irradiated during these stages of preimplantation, embryonic/fetal mortalities, incidence of external gross malformations, fetal body weight and sex ratio were observed at day 18 of gestation. There were significant increases in death in the preimplantation period compared to control levels after exposure to at least 0.25 Gy at 2 and 72 h postconception and 0.5 Gy at 96 h postconception. In contrast, a dose of 1.5 Gy was required at 48 h postconception. The frequency of embryonic death was analyzed using a logistic regression for comparing among stages. These analyses demonstrated that the regression slopes were significantly positive for groups in all stages and increased with decreasing time after conception. Furthermore, the regression analyses suggested that the most sensitive stage for preimplantation death and embryonic death was 2 h postconception, when embryos consisted of one cell. Many types of external gross malformations, such as exencephaly, cleft palate and anophthalmia, were observed even in the mice irradiated with 0.1 Gy at 2, 72 and 96 h postconception. In the same manner as embryonic mortality, the regression analyses suggested that the susceptibility of the mice irradiated at 2, 72 and 96 h postconception during preimplantation to external malformations was higher than that of the mice irradiated at 8 or 11 days of gestation, which is the period of organogenesis, and that the most sensitive stage for external malformations was 2 h postconception. However, no malformations were observed in the mice irradiated at 48 h postconception when the embryos were precompacted with four to eight cells.

Expression of C3 and C4 photosynthetic characteristics in the amphibious plant Eleocharis vivipara: structure and analysis of the expression of isogenes for pyruvate, orthophosphate dikinase

Eleocharis vivipara, a unique leafless amphibious sedge, adopts the C4 mode of photosynthesis under terrestrial conditions and the C3 mode under submerged aquatic conditions. To analyze the molecular basis of these responses to the contrasting environments, we isolated and characterized two full-length cDNAs for a key C4 enzyme, pyruvate, orthophosphate dikinase (PPDK; EC 2.7.9.1). The isogenes for PPDK, designated ppdk1 and ppdk2, were highly homologous to one another but not identical. The PPDK1 protein, deduced from the nucleotide sequence of the cDNA, contained an extra domain at the amino terminus which, presumably, serves as a chloroplast transit peptide, while PPDK2 lacked this extra domain. It seems likely, therefore, that the ppdk1 and ppdk2 genes encode a chloroplastic and a cytosolic PPDK, respectively. Genomic Southern blot analysis revealed the existence of a small family of genes for PPDK in the genome of E. vivipara. Northern blot analysis indicate that both chloroplastic and cytosolic genes for PPDK are expressed simultaneously in the culms, a photosynthetic organ, of E. vivipara and that the pattern of expression of these genes differs between the growth forms.

Comparison of stride characteristics in a cantering horse on a flat and inclined treadmill

The purpose of this study was to determine whether there was any difference in the stride characteristics between cantering on a flat or inclined treadmill. Five 2-year-old Thoroughbred horses were cantered on a treadmill at 3 different velocities and at 3 different slopes. The sequence of speeds at each slope was chosen at random and 16 mm cinefilms at 300 frames/s were taken from a lateral view at a distance of 15 m from the treadmill to record the linear and temporal data. On the slope, stride length, stride duration, stance duration and swing duration did not change. However, midstep length increased significantly and the airborne step length decreased significantly as slope increased from a 3% slope to a 8% slope at 12 m/s. The airborne duration increased significantly from a 0% slope to a 3% slope, and inversely decreased significantly from a 3% slope to a 8% slope. The advanced placement (AP) between trailing hindlimb and leading hindlimb (APTH-LH) and between trailing forelimb and leading forelimb (APTF-LF) and the overlap between LH and TF (LH-TF) tended to decrease and the AP between LH and TF (APLH-TF) and the overlap between TH and LH (TH-LH) inversely tended to increase as the slope increased, though these tendencies were not significant. These findings indicated that in slope locomotion, the stride length might be maintained by sacrificing the length of the airborne period as the workload became more intense.