Promotive Effect of C18-Unsaturated Fatty Acids on the Abscission of Bean Petiole Explants

The abscission-promoting effects of C₁₈-unsaturated fatty acidswere studied in bean (Phaseolus vulgaris L. cv. Masterpiece)petiole explants with the junction between the petiole and thepulvinus in the primary leaves in the light. Linolenic, linoleicand oleic acids promoted the abscission of the explants in thelight. Linolenic acid was the most effective among the compoundstested and its promotive effect was evident without any accompanyingincrease in the production of ethylene from the explants, ascompared with non-treated explants. Linolenic acid is easilyconverted to its hydroperoxide during the incubation with explants,as indicated by the formation of the conjugated diene and thegeneration of ethane. The production of ethylene from the explantstreated with linolenic acid was completely inhibited by theaddition of aminoethoxyvi-nylglycine (AVG), but large amountsof ethane were still generated. The promotive effect of linolenicacid was almost eliminated by the addition of scavengers offree radicals. Hydrogen peroxide and tert-butyl hydroperoxidepromoted abscission in the light. From these results, we concludedthat the abscission-promoting effect of linolenic acid are notmediated by the effect of ethylene but by the effect of itshydroperoxide, while the well-established pathway for the biosynthesisof ethylene from S-adenosylmethionine to ethylene, via 1-aminocyclopropane-l-carboxylicacid (ACC), was apparently operative. (Received May 1, 1991; Accepted July 10, 1991)     

Osteoclasts adapt to physioxia perturbation through DNA demethylation

Oxygen plays an important role in diverse biological processes. However, since quantitation of the partial pressure of cellular oxygen in vivo is challenging, the extent of oxygen perturbation in situ and its cellular response remains underexplored. Using two‐photon phosphorescence lifetime imaging microscopy, we determine the physiological range of oxygen tension in osteoclasts of live mice. We find that oxygen tension ranges from 17.4 to 36.4 mmHg, under hypoxic and normoxic conditions, respectively. Physiological normoxia thus corresponds to 5% and hypoxia to 2% oxygen in osteoclasts. Hypoxia in this range severely limits osteoclastogenesis, independent of energy metabolism and hypoxia‐inducible factor activity. We observe that hypoxia decreases ten‐eleven translocation (TET) activity. Tet2/3 cooperatively induces Prdm1 expression via oxygen‐dependent DNA demethylation, which in turn activates NFATc1 required for osteoclastogenesis. Taken together, our results reveal that TET enzymes, acting as functional oxygen sensors, regulate osteoclastogenesis within the physiological range of oxygen tension, thus opening new avenues for research on in vivo response to oxygen perturbation.     

Protracted Administration of L-Asparaginase in Maintenance Phase Is the Risk Factor for Hyperglycemia in Older Patients with Pediatric Acute Lymphoblastic Leukemia

Although L-asparaginase related hyperglycemia is well known adverse event, it is not studied whether the profile of this adverse event is affected by intensification of L-asparaginase administration. Here, we analyzed the profile of L-asparaginase related hyperglycemia in a 1,176 patients with pediatric acute lymphoblastic leukemia treated according to the Japan Association of Childhood Leukemia Study ALL-02 protocol using protracted L-asparaginase administration in maintenance phase. We determined that a total of 75 L-asparaginase related hyperglycemia events occurred in 69 patients. Although 17 events (17/1176, 1.4%) developed in induction phase, which was lower incidence than those (10–15%) in previous reports, 45 events developed during the maintenance phase with protracted L-asparaginase administration. Multivariate analysis showed that older age at onset (≥10 years) was a sole independent risk factor for L-asparaginase-related hyperglycemia (P<0.01), especially in maintenance phase. Contrary to the previous reports, obesity was not associated with L-asparaginase-related hyperglycemia. These findings suggest that protracted administration of L-asparaginase is the risk factor for hyperglycemia when treating adolescent and young adult acute lymphoblastic leukemia patients.     

Pseudodactylogyrus kamegaii sp. n. (Monogenea: Pseudodactylogyridae) from wild Japanese eel,Anguilla japonica

The monogenean Pseudodactylogyrus kamegaii sp. n. is described, based on specimens collected from the gills of wild Japanese eel Anguilla japonica caught in Chiba Prefecture, Japan. This species is the most similar to P. anguillae (Yin and Sproston, 1948), but different in the shape and measurements of the male copulatory organ, vagina and marginal hook. This new species was collected from the eel in brackish waters, while P. anguillae and P. bini, the other known pseudodactylogyrids of Japanese eel, have been recorded only in fresh waters.     

Zebrafish Polycomb group gene ph2alpha is required for epiboly and tailbud formation acting downstream of FGF signaling

We analyzed Polycomb group gene ph2alpha functionally in zebrafish embryos by a gene knock-down procedure using morpholino antisense oligos. Inhibition of ph2alpha message translation resulted in abnormal epibolic movements as well as a thick tailbud or incomplete covering of the yolk plug. At the 24hpf stage, morphants had short trunks and tails, phenotypes similar to those with disturbances in FGF signaling. Accordingly, we looked at the effects of ph2alpha expression upstream and downstream of the FGF pathway. Treatment with SU5402, an inhibitor of Fgfrs, or injection of dominant-negative Fgfr1 DNA markedly reduced ph2alpha expression in the tailbud. In addition, cells expressing mRNAs for no tail, spadetail, myoD, and papc, which are involved in FGF-related development of posterior mesoderm, were distributed abnormally. Collectively, the data argue that ph2alpha is required for epiboly and tailbud formation, acting downstream of the FGF signaling pathway.     

Enhancement of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) production in the transgenic Arabidopsis thaliana by the in vitro evolved highly active mutants of polyhydroxyalkanoate (PHA) synthase from Aeromonas caviae

In this study, the enhancement of photosynthetic PHA production was achieved using the highly active mutants of PHA synthase created by the in vitro evolutionally techniques. The wild-type and mutated PHA synthase genes from Aeromonas caviae were introduced into Arabidopsis thaliana together with the NADPH-dependent acetoacetyl-CoA reductase gene from Ralstonia eutropha. Expression of the highly active mutated PHA synthase genes, N149S and D171G, led to an 8-10-fold increase in PHA content in the T1 transgenic Arabidopsis, compared to plants harboring the wild-type PHA synthase gene. In homozygous T2 progenies, PHA content was further increased up to 6.1 mg/g cell dry weight. GC/MS analysis of the purified PHA from the transformants revealed that these PHAs were poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] copolymers consisting of 0.2-0.8 mol % 3HV. The monomer composition of the P(3HB-co-3HV) copolymers synthesized by the wild-type and mutated PHA synthases reflected the substrate specificities observed in Escherichia coli. These results indicate that in vitro evolved PHA synthases can enhance the productivity of PHA and regulate the monomer composition in transgenic plants.     

Characterization and sequence analysis of a developmentally regulated putative cell wall protein gene isolated from soybean

A cDNA clone, pTU04, which hybridizes to two different sizes of mRNA on Northern blots was isolated from soybean suspension culture cell poly(A) RNA. Northern analysis reveals that meristematic tissue produces a 1050-nucleotide mRNA while quiescent mature cells produce primarily a 1220-nucleotide mRNA homologous to pTU04. The cDNA and its corresponding genomic clone have been partially characterized. The nucleotide sequence of the gene predicts a proline-rich protein, designated SbPRP1, which contains a signal peptide sequence and 43 repeats of a sequence consisting primarily of Pro-Pro-Val-Tyr-Lys (CCA-CCA-GTT-TAC-AAG). From nuclease S1 and hybrid-select translation analyses, the cDNA clone pTU04 appears to represent the mRNA for the mature tissue 1220-nucleotide RNA observed on Northern blots. Although there is no direct proof that the encoded protein is a cell wall protein, it has the properties similar to previously isolated cell wall proteins: 1) it is very basic with a high content of Pro, Tyr, and Lys; 2) it has similar hydropathic properties; and 3) its repeating unit shares sequence homology with that of more highly characterized cell wall proteins, generally termed extensin (Chen, J., and Varner, J. E. (1985) EMBO J. 4, 2145-2151; Smith, J. J., Muldoon, E. P., Willard, J. J., and Lamport, D. T. A. (1986) Phytochemistry 25, 1021-1030.     

Calcium Antagonist Isradipine Reduces Metabolic Alterations in Acute Cerebral Ischemia in Spontaneously Hypertensive Rats

The present study was designed to examine the effect of a calcium antagonist isradipine (PN200-110: PN) on local cerebral blood flow and brain tissue metabolism after 1-hour supratentorial ischemia induced by bilateral carotid artery ligation (BCL) in spontaneously hypertensive rats (SHR). PN, dissolved in ethanol plus polyethylene glycol 400, diluted with saline to make the final concentration of 0.25mg/ml and 2.5mg/ml, was administered subcutaneously either 30 min prior to BCL or just after the induction of incomplete cerebral ischemia (n = 7 in each group). Vehicle injection was served as a control group (n = 7). Cerebral blood flow in the parietal cortex (CBF) and the cerebellar cortex (CeBF) was measured by hydrogen clearance technique, and the supra- and infratentorial metabolites of the brain frozen in situ were determined by the enzymatic method. Blood pressure was lowered, but CBF was increased by PN administration in pre-BCL treatment study. After 1 hour of BCL, CBF decreased to around 10% or less of the resting value, being insignificant among the groups. Brain adenosine triphosphate was better preserved in PN-administered groups. The increase in lactate level tended to reduce dose dependently by PN treatment. PN also reduced the metabolic alterations in brain tissue with significance, even when administered just after the induction of forebrain ischemia. It is considered that pre- as well as post-BCL administration of PN is beneficial to attenuate the metabolic alterations in incomplete forebrain ischemia in SHR.