Metabolic Bypass of the Tricarboxylic Acid Cycle during Lipid Mobilization in Germinating Oilseeds1 : Regulation of NAD+-Dependent Isocitrate Dehydrogenase Versus Fumarase

Biosynthesis of sucrose from triacylglycerol requires the bypass of the CO2-evolving reactions of the tricarboxylic acid (TCA) cycle. The regulation of the TCA cycle bypass during lipid mobilization was examined. Lipid mobilization in Brassica napus was initiated shortly after imbibition of the seed and proceeded until 2 d postimbibition, as measured by in vivo [1-14C]acetate feeding to whole seedlings. The activity of NAD+-isocitrate dehydrogenase (a decarboxylative enzyme) was not detected until 2 d postimbibition. RNA-blot analysis of B. napus seedlings demonstrated that the mRNA for NAD+-isocitrate dehydrogenase was present in dry seeds and that its level increased through the 4 d of the experiment. This suggested that NAD+-isocitrate dehydrogenase activity was regulated by posttranscriptional mechanisms during early seedling development but was controlled by mRNA level after the 2nd or 3rd d. The activity of fumarase (a component of the nonbypassed section of the TCA cycle) was low but detectable in B. napus seedlings at 12 h postimbibition, coincident with germination, and increased for the next 4 d. RNA-blot analysis suggested that fumarase activity was regulated primarily by the level of its mRNA during germination and early seedling development. It is concluded that posttranscriptional regulation of NAD+-isocitrate dehydrogenase activity is one mechanism of restricting carbon flux through the decarboxylative section of the TCA cycle during lipid mobilization in germinating oilseeds.

Accuracy of lesion bypass by yeast and human DNA polymerase η

DNA polymerase η (Polη) functions in the error-free bypass of UV-induced DNA lesions, and a defect in Polη in humans causes the cancer-prone syndrome, the variant form of xeroderma pigmentosum. Both yeast and human Polη replicate through a cis-syn thymine-thymine dimer (TT dimer) by inserting two As opposite the two Ts of the dimer. Polη, however, is a low-fidelity enzyme, and it misinserts nucleotides with a frequency of ≈ 10−2 to 10−3 opposite the two Ts of the TT dimer as well as opposite the undamaged template bases. This low fidelity of nucleotide insertion seems to conflict with the role of Polη in the error-free bypass of UV lesions. To resolve this issue, we have examined the ability of human and yeast Polη to extend from paired and mispaired primer termini opposite a TT dimer by using steady-state kinetic assays. We find that Polη extends from mispaired primer termini on damaged and undamaged DNAs with a frequency of ≈ 10−2 to 10−3 relative to paired primer termini. Thus, after the incorporation of an incorrect nucleotide, Polη would dissociate from the DNA rather than extend from the mispair. The resulting primer-terminal mispair then could be subject to proofreading by a 3′→5′ exonuclease. Replication through a TT dimer by Polη then would be more accurate than that predicted from the fidelity of nucleotide incorporation alone.

Urea-inducible Egr-1 transcription in renal inner medullary collecting duct (mIMCD3) cells is mediated by extracellular signal-regulated kinase activation.

Urea (200-400 milliosmolar) activates transcription, translation of, and trans-activation by the immediate-early gene transcription factor Egr-1 in a renal epithelial cell-specific fashion. The effect at the transcriptional level has been attributed to multiple serum response elements and their adjacent Ets motifs located within the Egr-1 promoter. Elk-1, a principal ternary complex factor and Ets domain-containing protein, is a substrate of the extracellular signal-regulated kinase (ERK) mitogen-activated protein kinases. In the renal medullary mIMCD3 cell line, urea (200-400 milliosmolar) activated both ERK1 and ERK2 as determined by in-gel kinase assay and immune-complex kinase assay of epitope-tagged] ERK1 and ERK2. Importantly, urea did not affect abundance of either ERK. Urea-inducible Egr-1 transcription was a consequence of ERK activation because the ERK-specific inhibitor, PD98059, abrogated transcription from the murine Egr-1 promoter in a luciferase reported gene assay. In addition, activators of protein kinase A, including forskolin and 8-Br-cAMP, which are known to inhibit ERK-mediated events, also inhibited urea-inducible Egr-1 transcription. Furthermore, urea-inducible activation of the physiological ERK substrate and transcription factor, Elk-1, was demonstrated through transient cotransfection of a chimeric Elk-1/GAL4 expression plasmid and a GAL4-driven luciferase reporter plasmid. Taken together, these data indicate that, in mIMCD3 cells, urea activates ERKs and the ERK substrate, Elk-1, and that ERK inhibition abrogates urea-inducible Egr-1 transcription. These data are consistent with a model of urea-inducible renal medullary gene expression wherein sequential activation of ERKs and Elk-1 results in increased transcription of Egr-1 through serum response element/Ets motifs.

Hypertonicity activates nonselective cation channels in mouse cortical collecting duct cells.

We investigated the effect of cell shrinkage on whole-cell currents of M-1 mouse cortical collecting duct cells. Addition of 100 mM sucrose to an isotonic NaCl bath solution induced cell shrinkage and increased whole-cell currents within 5-10 min by approximately 12-fold. The effect was reversible upon return to isotonic solution and could also be elicited by adding 100 mM urea or 50 mM NaCl. Replacement of bath Na+ by K+, Cs+, Li+, or Rb+ did not significantly affect the stimulated inward current, but replacement by N-methyl-D-glucamine reduced it by 88.1 +/- 1.3% (n = 34); this demonstrates that hypertonicity activates a nonselective alkali cation conductance. The activation was independent of extra- and intracellular Ca2+, but 1 or 10 mM ATP in the pipette suppressed it in a concentration-dependent manner, indicating that intracellular ATP levels may modulate the degree of channel activation. Flufenamic acid (0.1 mM) and gadolinium (0.1 mM) inhibited the stimulated current by 68.7 +/- 5.9% (n = 9) and 32.4 +/- 11.7% (n = 6), respectively, whereas 0.1 mM amiloride had no significant effect. During the early phase of hypertonic stimulation single-channel transitions could be detected in whole-cell current recordings, and a gradual activation of 30 and more individual channels with a single-channel conductance of 26.7 +/- 0.4 pS (n = 29) could be resolved. Thus, we identified the nonselective cation channel underlying the shrinkage-induced whole-cell conductance that may play a role in volume regulation.

Pressure radiation from a perforated duct exit region

Acknowledgements The authors are grateful to the following bodies that provided financial support for the project: (i) China Scholarship Council, (ii) National Natural Science Foundation of China (Grant no. U1334201) and (iii) UK Engineering and Physical Sciences Research Council (Grant no. EP/G069441/1).

Natural Compounds from Saffron and Bear Bile Prevent Vision Loss and Retinal Degeneration

All retinal disorders, regardless of their aetiology, involve the activation of oxidative stress and apoptosis pathways. The administration of neuroprotective factors is crucial in all phases of the pathology, even when vision has been completely lost. The retina is one of the most susceptible tissues to reactive oxygen species damage. On the other hand, proper development and functioning of the retina requires a precise balance between the processes of proliferation, differentiation and programmed cell death. The life-or-death decision seems to be the result of a complex balance between pro- and anti-apoptotic signals. It has been recently shown the efficacy of natural products to slow retinal degenerative process through different pathways. In this review, we assess the neuroprotective effect of two compounds used in the ancient pharmacopoeia. On one hand, it has been demonstrated that administration of the saffron constituent safranal to P23H rats, an animal model of retinitis pigmentosa, preserves photoreceptor morphology and number, the capillary network and the visual response. On the other hand, it has been shown that systemic administration of tauroursodeoxycholic acid (TUDCA), the major component of bear bile, to P23H rats preserves cone and rod structure and function, together with their contact with postsynaptic neurons. The neuroprotective effects of safranal and TUDCA make these compounds potentially useful for therapeutic applications in retinal degenerative diseases.

Croatia and the structural funds – Doing without an Ottoman Empire bypass bridge. CEPS Commentary, 29 July 2013

In his latest commentary, Associate Senior Fellow Michael Emerson hails Croatia’s accession to the EU as a fine step forward towards the official goal of integration of the whole of the Balkans into the EU. At the same time, he warns of the folly underway of the serious attention being paid by the European Commission to the newest member state’s petition to construct a multi-million euro bridge over a 9-km stretch of Bosnian land (the ‘Neum corridor’) that inconveniently but temporarily interrupts a non-stop drive along Croatia’s Dalmatian coast.

Down the road to Dubrovnik – Doing without an Ottoman Empire bypass bridge. CEPS Commentary, 29 July 2013

As Europeans speed down the road to Dubrovnik, Croatia's treasured jewel of the Adriatic coast, Michael Emerson discusses in a seasonal commentary one topical issue: What to do now over the 9 km of Bosnian coastline that separates north and south Croatia? Several options are under consideration, one of which would mean a very expensive bridge and dubious use of EU structural funds.

Transport of dredged sediment placed in the nearshore zone--Currituck sand-bypass study (phase I) /

New dredge-disposal techniques may serve the dual role of aiding sand by-passing across coastal inlets, and beach nourishment, provided the dredged sediments placed seaward of the surf zone move shoreward into that zone. During the summer of 1976, 26,750 cubic meters of relatively coarse sediment was dredged from New River Inlet, North Carolina, moved down coast by a split-hull barge, and placed in a 215-meter coastal reach between the 2- and 4-meter depth contours. Bathymetric changes on the disposal piles and in the adjacent beach and nearshore area were studied for a 13-week period (August to November 1976) to determine the modification of the surrounding beach and nearshore profile, and the net transport direction of the disposal sediment. The sediment piles initially created a local shoal zone with minimum depths of 0.6 meter. Disposal sediment was coarser (Mn = 0.49 millimeter) than the native sand at the disposal site (Mn = 0.14 millimeter) and coarser than the composite mean grain size of the entire profile (Mn = 0.21 millimeter). Shoaling and breaking waves caused rapid erosion of the pile tops and a gradual coalescing of the piles to form a disposal bar located seaward (= 90 meters) of a naturally occurring surf zone bar. As the disposal bar relief was reduced, the disposal bar-associated breaker zone was restricted to low tide times or periods of high wave conditions.

Observations on the bile and its diseases and on the oeconomy of the liver : read at the Royal College of Physicians as the Gulstonian lecture of the year 1799 /

Mode of access: Internet.

NIH state-of-the-science statement on endoscopic retrograde cholangiopancreatography (ERCP) for diagnosis and therapy

"State-of-the Science Conference on Endoscopic Retrograde Cholangiopancreatography (ERCP) for Diagnosis and Therapy was convened on January 14-16, 2002"--P. 5.

The anatomy of the human bones, nerves and lacteal sac and duct .../

Mode of access: Internet.

Users guide for the TUNVEN and DUCT programs /

Mode of access: Internet.

Pi︠a︡tidesi︠a︡tili︠e︡tnīĭ i︠u︡bileĭ S.-Peterburgskago prakticheskago tekhnologicheskago instituta, 28-go noi︠a︡bri︠a︡ 1878.

Includes index of graduates for 1837-1878.

Clinical lectures on the gallbladder and bile ducts,

"Radiology of the gallbladder, by Ernest E. Smith": p. 84-104. "Diagnostic and therapeutic duodenal drainage, by Harry M. Eberhard": p. 105-136.