Interannual variations in abundance and body size in Neocalanus copepods in the central North Pacific

As the integral components of zooplankton in the subarctic NorthPacific, the three Neocalanus species (N. cristatus, N. plumchrusand N. flemingeri) are characterized by an annual life cycleand rapid development in the surface layer during spring–summer.Patterns of interannual variation of abundance and body sizeof these Neocalanus species were analyzed using the time-seriesdata collected during the summers of 1979–1998 (20 years)at stations along the longitudinal transect line in the centralNorth Pacific, crossing five sub-areas (Alaska Current System,Subarctic Current System, Northern Transition Domain, SouthernTransition Domain and Subtropical Current System). In the southernsub-areas, quasi-decadal oscillation was observed for the 3-yearrunning mean of abundance and prosome length for copepoditestage 5 (C5) of the three Neocalanus species. Although the oscillationsignal diminished towards northern waters, it showed a positivephase during the early 1980s and 1990s and a negative phaseduring the late 1980s. In the northern waters, a biennial patternwas pronounced for anomalies of C5 prosome length for N. plumchrusand N. flemingeri, which was large in odd years and small ineven years. Significantly positive covariations among the threespecies were found for both abundance and prosome length aroundmid-latitude, where they were abundant. In the correlation analysis,these observed yearly patterns showed a statistically insignificantcorrelation with most environmental (integrated mean temperaturein surface waters, water column stability and chlorophyll aconcentration) or climatological (North Pacific Index and SouthernOscillation Index) variables. The regional difference of theoscillation signal and the synchronized covariation among thesespecies suggest that interannual variations of their abundanceand body size are mediated by common environmental force(s)with some spatial and temporal scales in the subarctic NorthPacific.     

Bayesian association mapping of multiple quantitative trait loci and its application to the analysis of genetic variation among <Emphasis Type="Italic">Oryza sativa</Emphasis> L. germplasms

One way to use a crop germplasm collection directly to map QTLs without using line-crossing experiments is the whole genome association mapping. A major problem with association mapping is the presence of population structure, which can lead to both false positives and failure to detect genuine associations (i.e., false negatives). Particularly in highly selfing species such as Asian cultivated rice, high levels of population structure are expected and therefore the efficiency of association mapping remains almost unknown. Here, we propose an approach that combines a Bayesian method for mapping multiple QTLs with a regression method that directly incorporates estimates of population structure. That is, the effects due to both multiple QTLs and population structure were included in our statistical model. We evaluated the efficiency of our approach in simulated- and real-trait analyses of a rice germplasm collection. Simulation analyses based on real marker data showed that our model could suppress both false-positive and false-negative rates and the error of estimation of genetic effects over single QTL models, indicating that our model has statistically desirable attributes over single QTL models. As real traits, we analyzed the size and shape of milled rice grains and found significant markers that may be linked to QTLs reported previously. Association mapping should have good prospects in highly selfing species such as rice if proper methods are adopted. Our approach will be useful for the whole genome association mapping of various selfing crop species.     

Pathogen recognition by Toll-like receptor 2 activates Weibel-Palade body exocytosis in human aortic endothelial cells

The endothelial cell-specific granule Weibel-Palade body releases vasoactive substances capable of modulating vascular inflammation. Although innate recognition of pathogens by Toll-like receptors (TLRs) is thought to play a crucial role in promotion of inflammatory responses, the molecular basis for early-phase responses of endothelial cells to bacterial pathogens has not fully been understood. We here report that human aortic endothelial cells respond to bacterial lipoteichoic acid (LTA) and synthetic bacterial lipopeptides, but not lipopolysaccharide or peptidoglycan, to induce Weibel-Palade body exocytosis, accompanied by release or externalization of the storage components von Willebrand factor and P-selectin. LTA could activate rapid Weibel-Palade body exocytosis through a TLR2- and MyD88-dependent mechanism without de novo protein synthesis. This process was at least mediated through MyD88-dependent phosphorylation and activation of phospholipase Cgamma. Moreover, LTA activated interleukin-1 receptor-associated kinase-1-dependent delayed exocytosis with de novo protein synthesis and phospholipase Cgamma-dependent activation of the NF-kappaB pathway. Increased TLR2 expression by transfection or interferon-gamma treatment increased TLR2-mediated Weibel-Palade body exocytosis, whereas reduced TLR2 expression under laminar flow decreased the response. Thus, we propose a novel role for TLR2 in induction of a primary proinflammatory event in aortic endothelial cells through Weibel-Palade body exocytosis, which may be an important step for linking innate recognition of bacterial pathogens to vascular inflammation.     

Disassembly of actin filaments by botulinum C2 toxin and actin-filament-disrupting agents induces assembly of microtubules in human leukaemia cell lines

BACKGROUND INFORMATION: C(2) toxin produced by Clostridium botulinum types C and D ADP-ribosylates actin monomers and inactivates their polymerization activities. The disassembly of actin filaments by C(2) toxin induces a polarization of cultured human leukaemia cell lines. RESULTS: The polarization induced by C(2) toxin was temperature dependent and was prevented by nocodazole, a microtubule-disrupting agent, whereas it was promoted by paclitaxel, a microtubule-stabilizing agent. The fluorescence staining of polarized cells indicated an increase in microtubule assembly accompanying disassembly of actin filaments. Furthermore, several actin-filament-disrupting agents, other than C(2) toxin, also induced microtubule assembly and cell polarization, irrespective of their different mechanisms of action. The effects induced by some of the agents, which have lower binding affinities for actin, were reversible in response to the re-assembly of actin filaments. CONCLUSIONS: Thus the disassembly of actin filaments by C(2) toxin and actin-filament-disrupting agents induces assembly of microtubules followed by polarization of human leukaemia cell lines, indicating that the assembly/disassembly equilibrium of actin filaments influences the dynamics of microtubules, which control cell morphology and, in turn, diverse cellular processes.     

In vitro biosynthesis of ether-type glycolipids in the methanoarchaeon Methanothermobacter thermautotrophicus

The biosynthesis of archaeal ether-type glycolipids was investigated in vitro using Methanothermobacter thermautotrophicus cell-free homogenates. The sole sugar moiety of glycolipids and phosphoglycolipids of the organism is the beta-D-glucosyl-(1-->6)-D-glucosyl (gentiobiosyl) unit. The enzyme activities of archaeol:UDP-glucose beta-glucosyltransferase (monoglucosylarchaeol [MGA] synthase) and MGA:UDP-glucose beta-1,6-glucosyltransferase (diglucosylarchaeol [DGA] synthase) were found in the methanoarchaeon. The synthesis of DGA is probably a two-step glucosylation: (i) archaeol + UDP-glucose --> MGA + UDP, and (ii) MGA + UDP-glucose --> DGA + UDP. Both enzymes required the addition of K(+) ions and archaetidylinositol for their activities. DGA synthase was stimulated by 10 mM MgCl(2), in contrast to MGA synthase, which did not require Mg(2+). It was likely that the activities of MGA synthesis and DGA synthesis were carried out by different proteins because of the Mg(2+) requirement and their cellular localization. MGA synthase and DGA synthase can be distinguished in cell extracts greatly enriched for each activity by demonstrating the differing Mg(2+) requirements of each enzyme. MGA synthase preferred a lipid substrate with the sn-2,3 stereostructure of the glycerol backbone on which two saturated isoprenoid chains are bound at the sn-2 and sn-3 positions. A lipid substrate with unsaturated isoprenoid chains or sn-1,2-dialkylglycerol configuration exhibited low activity. Tetraether-type caldarchaetidylinositol was also actively glucosylated by the homogenates to form monoglucosyl caldarchaetidylinositol and a small amount of diglucosyl caldarchaetidylinositol. The addition of Mg(2+) increased the formation of diglucosyl caldarchaetidylinositol. This suggested that the same enzyme set synthesized the sole sugar moiety of diether-type glycolipids and tetraether-type phosphoglycolipids.     

Parasporin-2Ab,a Newly Isolated Cytotoxic Crystal Protein from <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis>

A novel crystal protein that exhibited potent cytotoxicity against human leukemic T-cells was cloned from the Bacillus thuringiensis TK-E6 strain. The protein, designated as parasporin-2Ab (PS2Ab), was a polypeptide of 304 amino acid residues with a predicted molecular weight of 33,017. The deduced amino acid sequence of PS2Ab showed significant homology (84% identitiy) to parasporin-2Aa (PS2Aa) from the B. thuringiensis A1547 strain. Upon processing of PS2Ab with proteinase K, the active form of 29 kDa was produced. The activated PS2Ab showed potent cytotoxicity against MOLT-4 and Jurkat cells and the EC₅₀ values were estimated as 0.545 and 0.745 ng/mL, respectively. The cytotoxicity of PS2Ab was significantly higher than that of PS2Aa reported elsewhere. Although both cytotoxins were structurally related, it was thought that the minor differences found were responsible for the different cytotoxicities of PS2Ab and PS2Aa.     

Antimalarial activity of 1-aryl-3,3-dialkyltriazenes

The antimalarial activity of 1-aryl-3,3-dialkyltriazenes to Plasmodium berghei NK-65 in infected mice was evaluated at an intraperitoneal dose of 100mg/kgbw. Some of these compounds were found to possess potent antimalarial activity.     

Hypermetabolism of fat in V1a vasopressin receptor knockout mice

[Arg8]Vasopressin (AVP) has an antilipolytic action on adipocytes, but little is known about the mechanisms involved. Here, we examined the involvement of the V1a receptor in the antilipolytic effect of AVP using V1a receptor-deficient (V1aR-/-) mice. The levels of blood glycerol were increased in V1aR-/- mice. The levels of ketone bodies, such as acetoacetic acid and 3-hydroxybutyric acid, the products of the lipid metabolism, were increased in V1aR-/- mice under a fasting condition. Triacylglyceride and free fatty acid levels in blood were decreased in V1aR-/- mice. Furthermore, measurements with tandem mass spectrometry determined that carnitine and acylcarnitines in serum, the products of beta-oxidation, were increased in V1aR-/- mice. Most acylcarnitines were increased in V1aR-/- mice, especially in the case of 2-carbon (C2), C10:1, C10, C14:1, C16, C18:1, and hydroxy-18:1-carbon (OH-C18:1)-acylcarnitines under feeding rather than under fasting conditions. The analysis of tissue C2-acylcarnitine level showed that beta-oxidation was promoted in muscle under the feeding condition and in liver under the fasting condition. An in vitro assay using brown adipocytes showed that the cells of V1aR-/- mice were more sensitive to isoproterenol for lipolysis. These results suggest that the lipid metabolism is enhanced in V1aR-/- mice. The cAMP level was enhanced in V1aR-/- mice in response to isoproterenol. The phosphorylation of Akt by insulin stimulation was reduced in V1aR-/- mice. These results suggest that insulin signaling is suppressed in V1aR-/- mice. In addition, the total bile acid, taurine, and cholesterol levels in blood were increased, and an enlargement of the cholecyst was observed in V1aR-/- mice. These results indicated that the production of bile acid was enhanced by the increased level of cholesterol and taurine. Therefore, these results indicated that AVP could modulate the lipid metabolism by the antilipolytic action and the synthesis of bile acid via the V1a receptor.