UNC-52/perlecan affects gonadal leader cell migrations in C. elegans hermaphrodites through alterations in growth factor signaling

The unc-52 gene of Claenorhabditis elegans encodes a homologue of the basement membrane heparan sulfate proteoglycan perlecan. Viable alleles reduce the abundance of UNC-52 in late larval stages and increase the frequency of distal tip cell (DTC) migration defects caused by mutations disrupting the UNC-6/netrin guidance system. These unc-52 alleles do not cause circumferential DTC migration defects in an otherwise wild-type genetic background. The effects of unc-52 mutations on DTC migrations are distinct from effects on myofilament organization and can be partially suppressed by mutations in several genes encoding growth factor-like molecules, including EGL-17/FGF, UNC-129/TGF-beta, DBL-1/TGF-beta, and EGL-20/WNT. We propose that UNC-52 serves dual roles in C. elegans larval development in the maintenance of muscle structure and the regulation of growth factor-like signaling pathways.     

Diurnal changes in needle gas exchange in alpine Pinus pumila during snow-melting and summer seasons

Pinus pumila (Pallas) Regel. is a dominant dwarf tree in alpine regions of Japan. The possible factors limiting the net photosynthetic rate (P_n) of the needles of P. pumila were examined in the snow-melting (May) and the summer (August) seasons. In August, in situ maximum P_n was 20 mol kg^–1 needle s^–1 in the current-year needles and 25 mol kg^–1 needle s^–1 in the 1-year-old needles. Diurnal trends of P_n in August were positively related to fluctuations in photosynthetic photon flux density (PPFD) and no midday depression of P_n was found, indicating that a decrease in PPFD rather than an increase in needle-to-air vapor pressure deficit (W) might cause the reduction of P_n. Both stomatal conductance (g_s) and P_n were lower in May than in August. In May, P_n and g_s were almost zero in the morning, but gradually increased with decreasing W, reaching maximum P_n values (4 mol kg^–1 needle s^–1) and g_s (60 mmol kg^–1 needle s^–1) at 16.00 hours. The daytime P_n in May was positively related to g_s. Relative water content in the exposed needles above the snow in May was 83%, which was far above the lethal level. This indicates that the water flow from stems or soils to needles was enough to compensate for a small amount of water loss due to the low g_s in May, although the water supplied to needles would be impeded by the low temperatures. Thus, the reduced g_s in May would be important for avoiding needle desiccation, and would result in a reduced P_n.     

Determination of the absolute configuration of (+)-2,7(14),10-bisabolatrien-1-ol-4-one from Japanese cedar,Cryptomeria japonica

The absolute configuration of (+)-2,7(14),10-bisabolatrien-1-ol-4-one, a peculiar sesquiterpenol in the Japanese cedar, Cryptomeria japonica, was determined as (1S,6R)-2,7(14),10-bisabolatrien-1-ol-4-one by comparing the specific rotation values of cryptomeriones respectively converted from (+)-2,7(14),10-bisabolatrien-1-ol-4-one and synthesized from (R)-(-)-carvone.     

Preparation of chiral 4-benzyloxymethyldihydrofuran-2-one using lipase-catalyzed kinetic resolution: synthesis of (-)-virginiae butanolide C (VB C)

Lipase-catalyzed kinetic resolution of the N,N-dialkyl-3-benzyloxymethyl-4-hydroxybutanamide 10a,b afforded the acetate 11a,b with (R) configuration, whereas the N-monoalkyl-3-benzyloxymethyl-4-hydroxybutanamide 10c-e gave the acetate 11c-e with (S) configuration. The butanamide 10 smoothly cyclized to give chiral 4-benzyloxymethyldihydrofuran-2-one 9 without racemization, which was effectively transformed into highly stereocontrolled virginiae butanolide C (VB C).     

iNOS enhances rat intestinal apoptosis after ischemia-reperfusion

The aim of this study was to demonstrate (i) the role of iNOS (inducible nitric oxide synthase) on apoptosis in the rat intestinal mucosa after ischemia-reperfusion, and (ii) the effect of iNOS on the release of cytochrome c from mitochondria. The superior mesenteric artery was occluded for 60 min and was followed by a 60 min reperfusion. Rats were pretreated with an intraperitoneal injection of the following iNOS inhibitors: N-nitro-L-arginine methyl ester, aminoguanidine, and (1S,5S,6R,7R)-7- chloro-3-imino-5-methyl-2-azabicyclo [4. 1. 0] heptane hydrochloride (ONO-1714). Apoptosis was evaluated and NO(X) in the portal vein was assayed. The amount of iNOS, caspase-3, and cytochrome c were determined by a Western blot analysis. Intestinal mucosal epithelial mitochondrial dehydrogenase activity was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoilium bromide. Ischemia-reperfusion increased intestinal mucosal apoptosis, NO(X) production in the portal vein, the amount of iNOS protein, and the release of cytochrome c, but not caspase-3. Inhibitors of iNOS significantly attenuated the induction of apoptosis, increased NO(X) production, and release of cytochrome c. Mitochondrial dysfunction was induced by ischemia-reperfusion, which was ameliorated by iNOS inhibitors. Our results indicate that iNOS is related to increased mucosal apoptosis in the rat small intestine after ischemia-reperfusion, which is partly explained by the release of cytochrome c from mitochondria to cytosols following mitochondrial dysfunction.     

Inhibition of recombinant dipeptidyl peptidase III by synthetic hemorphin-like peptides

In order to find the most effective antagonist for dipeptidyl peptidase III degrading enkephalin, we synthesized hemorphin-like pentapeptides with aliphatic or aromatic amino acids at the N-termini, such as VVYPW, LVYPW, IVYPW, YVYPW, FVYPW and WVYPW. Among those pentapeptides, IVYPW and WVYPW showed the strongest inhibitory activity toward rDPP III. The K(i) values of IVYPW and WVYPW were 0.100+/-0.011 and 0.126+/-0.015 microM (mean+/-S.E.), respectively. The order of K(i) values was Ile> or =Trp>Phe> or =Tyr>Leu>Ala>Val>Ser>Gly. rDPP III activity is inhibited in a non-competitive manner by these peptides. The peptide VYPW did not inhibit rDPP III activity, but the sequence is essential for the expression of inhibitory activity.     

Acetabularia: A Unicellular Model for Understanding Subcellular Localization and Morphogenesis during Development

Acetabularia acetabulum is the organism that provided the first compelling experimental evidence both for the role of an organelle whose function was unknown, the nucleus, and for the existence of "morphogenetic substances," the behavior of which presaged the discovery of mRNA in other organisms. This giant unicell holds special appeal as a model system, because the contribution of its diploid nucleus to cellular processes can be assessed using simple amputation and grafting experiments and because it lends itself to a wide range of methods in cell, molecular, and developmental biology. It remains an excellent model system for understanding how body regions are functionally and structurally distinguished from each other without cellular compartmentation. Advances in genetics (that is, mutant selection and analysis, large-scale transformation) will greatly increase the power of this system to address fundamental questions in development and morphogenesis. We discuss strengths and weaknesses of the system and outline the body of knowledge that would make the system more powerful and broadly appealing.     

Correlation between genetic and cytogenetic maps of the rat

To correlate rat genetic linkage maps with cytogenetic maps, we localized 25 new cosmid-derived simple sequence length polymorphism (SSLP) markers and 14 existing genetic markers on cytogenetic bands of chromosomes, using fluorescence in situ hybridization (FISH). Next, a total of 58 anchor loci, consisting of the 39 new and 19 previously reported ones, were integrated into the genetic linkage maps. Since most of the new anchor loci were developed to be localized near the terminals of the genetic or cytogenetic maps for each chromosome, the orientation and coverage of the whole genetic linkage maps were determined or confirmed with respect to the cytogenetic maps. Thus, we provide here a new base for rat genetic maps. Received: 9 September 1997 / Accepted: 11 November 1997     

A Marked Increase in Free Copper Levels in the Plasma and Liver of LEC Rats: An Animal Model for Wilson Disease and Liver Cancer

Most of copper present in rat plasma and liver binds to caeruloplasmin and metallothionein, respectively, and is not redox active. However, free forms of copper including loosely bound forms to other molecules are redox active. We assessed the free copper in Long-Evans rats with a cinnamon-like coat color (LEC rats), an animal model of Wilson disease and liver cancer. Compared to those of control rats, the liver and plasma of LEC rats showed a marked elevation of free copper, especially at the stage of acute hepatitis, in parallel with an increase of total copper levels in the livers and a decrease of plasma caeruloplasmin (ferroxidase I) activity. At the onset of jaundice, the total copper levels, however, decreased in liver, but increased in plasma, while free copper levels in both liver and plasma remained higher. Free iron levels in both liver and plasma were also determined and did not change significantly, except for the case of plasma in jaundiced rats. The data are consistent with a proposal in which increased levels of redox active free copper in the liver of LEC rats catalyze Fenton-type reactions, producing a large flux of hydroxyl radicals that would play an important role in the observed liver dysfunction, leading to acute hepatitis, and, finally, hepatocarcinoma. This is the first demonstration that the free copper may participate in the pathophysiology of the LEC rats and Wilson disease.     

Selective excretion of anti-inflammatory cytokine Interleukin-10 in a superantigen-inducing neonatal infectious disease

Neonatal toxic shock syndrome (TSS)-like exanthematous disease (NTED) is an emerging neonatal infectious disease caused by TSS toxin-1 (TSST-1). Although NTED and TSS are caused by the same superantigenic exotoxin, NTED is less severe than TSS. The mechanism of this reduced severity in NTED has not been elucidated. Thirteen patients with NTED were enrolled in the study. We investigated serum cytokine profile using a cytometric bead array system with a cytokine panel. Expression of Vβ2 and CD45RO in CD4⁺ T cells was investigated in mononuclear cells by using flowcytometry. Ten patients with other bacterial infections and eight patients without any infections were also enrolled as control groups. The mean serum level of IL-10 was 1209.9 pg/mL in patients with NTED at the time of admission into the study. The other inhibitory cytokine, IL-4, exhibited a minimum level. The high level of IL-10 rapidly decreased within 3–9 days of the onset of NTED. The cytokine profile of NTED, with its high IL-10 level, was clearly different from that of the other bacterial infections. The increased level of IL-10 seems to be related to the reduced severity of NTED. Th2 shift is not thought to be the cause of this IL-10 excretion.