Improving Germination Rate of Coastal Glehnia by Cold Stratification and Pericarp Removal

The medicinal plant, coastal glehnia (Glehnia littoralis F. Schmidt ex Miq.), belongs to the Apiaceae, which is known to exhibit morpho-physiological seed dormancy (MPD). In this study, we aimed to determine the dormancy type of this plant, along with the conditions for breaking dormancy, and how to increase its germination rate for mass production. Initially, the seeds of coastal glehnia had undeveloped embryos, which gradually developed following cold (5 °C) stratification over eight weeks. The embryo to seed (E:S) ratio increased to 66.7%, confirming that the seeds had the MPD type. Coastal glehnia seeds with pericarp did not show inhibited water uptake, and the germination inhibitory chemicals were not detected. However, removal of the pericarp improved the final germination percentage, germination speed, and T50 of coastal glehnia seeds compared with those of seeds with pericarp at 20 °C, which showed the highest value compared with other temperature treatments. Thus, cold stratification at 5 °C for eight weeks and removing the pericarp of germinating seeds maintained at 20 °C is efficient ways to break dormancy and improve the germination rate for the mass production of coastal glehnia.

Pressure Activated Sealant to Restore Tubing Integrity – Case Study of Well Tn-X in Mahakam

Pressure activated sealant is used to repair tubing leak and restore tubing integrity without the need to install downhole devices which yield additional restriction inside tubing and reduce tubing ID. Leak on tubing was detected in early production phase from the continuous increase of A annulus pressure. The leak point was indicated from Production Logging Tool (PLT) at 183 m suspected from tubing thread connection, with annulus pressure buildup rate 435 psi/24 hrs. Pressure activated sealant was selected as the means to cure the leak. Retrievable plug was set below the leak point and sealant was pumped on top of plug, followed by inhibited water. Then pressure was applied at surface to squeeze and activate the sealant. The remaining fluid inside tubing remained liquid, allowing the plug to be retrieved. A total of 59 L sealant mixture and 750 L of inhibited water was pumped to the well. Hesitation pressure was performed to activate the sealant, and got indication of chemical sealing at 1000 psi. The tubing was then pressure tested to 5000 psi and pressure was holding in 1 hour, indicating positive isolation has been established between tubing-annulus. From continuous annulus pressure monitoring, pressure in A annulus has been stable at ~40 psi for the last 8 months after sealant injection has been performed. Pressure activated sealant is proven as a reliable method to cure small leak in tubing. Since the sealant will only be hardened inside the leaking point, there will be no additional restriction in the tubing, thus Internal Diameter (ID) reduction will not be a concern for future well intervention operations. Pressure activated sealant could become one of the alternatives to cure tubing leaks, especially in the cases where tubing ID reduction is not favored.

Phytotoxicity of graphene oxide on rice plants is concentration-dependent

Graphene significantly affects seeds germination and seedling growth of food plants. Phytotoxicity tests by seeds germination and seedling growth are important means to detect toxicity of graphene oxide. We in this study assessed the effect of graphene oxide on rice plants at low concentration. Graphene oxide significantly inhibited water absorption during 3–6 h soaking, postponed seeds germination, but significantly decreased seeds germination rate under 10 μg/mL treatment. Graphene oxide showed most destructive effect on root than upper ground part, and severely restrained root development and increased chlorophyll content. Moreover, graphene oxide enhanced superoxide dismutase, catalase and peroxidase activities, and the change could alleviate oxygen damage. All these results indicate graphene oxide has some concentration-dependent phytotoxicity on seeds germination and seedling development, but also decreases damage by improving activities of antioxidant enzymes.

Water absorption and dormancy-breaking requirements of physically dormant seeds of Schizolobium parahyba (Fabaceae – Caesalpinioideae)

Physical dormancy refers to seeds that are water impermeable. Within the Fabaceae, the structure associated with the breaking of dormancy is usually the lens. This study verified the role of the lens in physical dormancy of seeds of Schizolobium parahyba, a gap species of Fabaceae from the Atlantic Forest of Brazil. The lens in S. parahyba seeds appeared as a subtle depression near the hilum and opposite the micropyle. After treatment of the seeds with hot water, the lens detached from the coat. Blocking water from contacting the lens inhibited water absorption in hot-water-treated seeds. High constant (30°C) and alternating (20/30°C) temperatures promoted the breaking of physical dormancy and germination in non-scarified seeds. Maximum percentage of germination occurred earlier for seeds incubated at 20/30°C than for those incubated at 30°C. Seeds with a blocked lens did not germinate at alternating or high temperatures. This study suggests that alternating temperatures are probably the cause of physical dormancy break of seeds of S. parahyba in gaps in the forest.

Obestatin inhibits vasopressin secretion: evidence for a physiological action in the control of fluid homeostasis

Obestatin, a product of post-translational processing of the ghrelin prohormone, has been reported to act in the brain to inhibit thirst. We extended our initial studies on water drinking by examining the effects of obestatin on hypovolemia-induced water and saline drinking and vasopressin release in male rats. Intracerebroventricular administration of obestatin significantly inhibited water, but not saline (0.3 M NaCl) drinking in response to a hypovolemic challenge. Obestatin also inhibited, in a dose-related fashion, dehydration-induced vasopressin secretion without affecting plasma oxytocin levels. Vasopressin release induced by central angiotensin II administration was attenuated significantly by prior administration of obestatin. Finally, central administration of an antiserum specific to obestatin resulted in an exaggerated basal vasopressin release and an increased vasopressin response to overnight water deprivation. Antiserum treatment also resulted in significantly increased ad libitum water drinking and drinking in response to dehydration. We conclude that this product of post-translational processing of the ghrelin prohormone may be an important contributor to the physiologic regulation of fluid and electrolyte homeostasis.

Vasopressin depolymerizes F-actin in toad bladder epithelial cells

Vasopressin (AVP) induces the rapid fusion of water channel-containing vesicles with the luminal membrane of its target cell. We have carried out a quantitative study of the F-actin content of toad bladder epithelial cells, using the rhodamine phalloidin binding assay. As early as 1 min after AVP stimulation, there is a significant 15% reduction of cellular F-actin, which remains reduced by 20-30% for the duration of action of AVP. Comparable reductions were seen following 8-bromoadenosine 3',5'-cyclic monophosphate, 1-desamino-8-D-arginine vasopressin, and forskolin. F-actin content rose to and then exceeded that of control bladders after AVP washout. Inhibition of prostaglandin synthesis enhanced both water flow and the decrease of F-actin. In the living cell, stabilization of F-actin with NBD-phallacidin selectively inhibited water flow. In view of the rapidity of the response, we conclude that AVP shifts the equilibrium between F-actin and G-actin monomers, and this depolymerization may be required for vesicle fusion.

Mercurial reagents inhibit flow through ADH-induced water channels in toad bladder

Mercurial reagents inhibit the water permeability of erythrocytes and proximal renal tubule. We examined the effect of two such agents on vasopressin-induced water transport across toad urinary bladder. Water flows were measured in unfixed tissues and in tissues fixed either with N-ethylmaleimide (NEM) or with glutaraldehyde. When added concurrently with 20 mU/ml vasopressin, 1 mM mucosal p-chloromercuribenzene-sulfonic acid (p-CMBS) inhibited water flow within 1 h. p-CMBS also inhibited flow in tissues that had been fixed with mucosal NEM after stimulation with vasopressin. However, p-CMBS did not affect flow in glutaraldehyde-fixed tissues. In contrast, HgCl2 inhibited water flow and urea permeability even in tissues that had been fixed with glutaraldehyde after stimulation with vasopressin. Inhibition was more pronounced when HgCl2 was added to the mucosal rather than the serosal bathing medium and was not reversed by dithiothreitol. HgCl2 did not diminish the frequency or area of luminal membrane aggregates observed by freeze-fracture electron microscopy. HgCl2 also did not affect amphotericin-induced water permeability in glutaraldehyde-treated tissues, suggesting that it did not diminish the permeability of cellular barriers to flow. Our results parallel closely those reported by other investigators for water flow across erythrocytes and proximal renal tubule and suggest that mercurial reagents can directly block the vasopressin-induced water channel. The water channel at the apical membrane of the toad bladder may prove to share structural similarity with that constantly present in erythrocytes and proximal renal tubule.

Alpha 2-agonists block ADH action in toad bladder and this inhibition is not modified by indomethacin

To identify the type of alpha-adrenoceptors involved in the inhibition of the hydrosmotic effect of antidiuretic hormone (ADH) on the toad bladder, we studied the effect of different alpha-adrenergic agonists and antagonists on ADH-induced water transport. Serosal addition of epinephrine (10(-6) M) and norepinephrine (10(-6) M) in the presence of 10(-4) M propranolol significantly inhibited the hydrosmotic effect of ADH (arginine vasopressin). This inhibitory effect of the catecholamines was completely reversed by 10(-5) M yohimbine but not by prazosin. Clonidine did not block ADH-induced water transport, but guanabenz, another alpha 2-agonist, inhibited water transport in response to ADH. In bladders pretreated with indomethacin to block prostaglandin synthesis, basal water permeability was increased, and even in this condition epinephrine inhibited ADH-induced water transport. These studies indicate that alpha 2-adrenergic receptors are involved in the inhibitory effect of catecholamines on ADH-mediated water permeability in the toad bladder. However, this effect was not mimicked by clonidine, as in the case of rabbit cortical collecting tubule. The inhibitory effect of epinephrine appears to be exerted independently of prostaglandin synthesis.