Regulation of prostaglandin endoperoxide synthase-2 and IL-6 expression in mouse bone marrow-derived mast cells by exogenous but not endogenous prostanoids.

Mouse bone marrow-derived mast cells (BMMC), stimulated with stem cell factor, IL-1beta, and IL-10, secrete IL-6 and demonstrate a delayed phase of PGD(2) generation that is dependent upon the induced expression of PG endoperoxide synthase (PGHS)-2. We have examined the potential for exogenous prostanoids, acting in a paracrine fashion, and endogenous prostanoids, acting in an autocrine fashion, to regulate PGHS-2 induction and IL-6 secretion in mouse BMMC. Exogenous PGE(2), which acts through G protein-coupled receptors, and 15-deoxy-Delta(12,14)-PGJ(2), which is a ligand for peroxisome proliferator-activated receptor (PPAR)gamma, elicited a 2- to 3-fold amplification of PGHS-2 induction, delayed-phase PGD(2) generation, and IL-6 secretion in response to stem cell factor, IL-1beta, and IL-10. The effect of PGE(2) was reproduced by the E prostanoid (EP)1 receptor agonist 17-trinor-PGE(2), and the EP1/EP3 agonist, sulprostone, but not the EP2 receptor agonist, butaprost. Although BMMC express PPARgamma, the effects of 15-deoxy-Delta(12,14)-PGJ(2) were not reproduced by the PPARgamma agonists, troglitazone and ciglitazone. PGHS-2 induction, but not IL-6 secretion, was impaired in cPLA(2)-deficient BMMC. However, there was no impairment of PGHS-2 induction in BMMC deficient in hematopoietic PGD synthase or PGHS-1 in the presence or absence of the PGHS-2 inhibitor, NS-398. Thus, although exogenous prostanoids may contribute to amplification of the inflammatory response by augmenting PGD(2) generation and IL-6 secretion from mast cells, endogenous prostanoids do not play a role.     

Meiosis-reinitiation-inducing factor of Tetrahymena functions upstream of M-phase-promoting factor.

Reinitiation of meiosis (maturation) of amphibian Bufo and Xenopus oocytes can be induced if Tetrahymena extract is injected into them. The activity differed from M-phase-promoting factor, because action of the former factor on the induction of maturation was inhibited by treatment of the oocytes with cycloheximide. Activity of M-phase-promoting factor was not detected in Tetrahymena extract regardless of the presence of cdc2 homologues in the extract. However, cycloheximide-resistant-maturation-inducing activity appeared in the recipients, when the maturation was induced by injection of Tetrahymena extract. Immunoblots using antibodies against cdc2 showed that injection of Tetrahymena extract induced fast mobility of the recipient cdc2 in the presence of the recipient protein synthesis. The same mobility shift of the cdc2 was also induced when M-phase-promoting factor containing Xenopus oocyte extract was injected into immature oocytes or when the immature oocyte extract was treated with alkaline phosphatase. These results indicate that meiosis-reinitiation-inducing factor of Tetrahymena functions upstream of M-phase-promoting factor to induce dephosphorylation of the recipient cdc2. Tetrahymena cdc2 homologues also showed fast mobility when the Tetrahymena extract was treated with alkaline phosphatase. Preliminary experiments showed that the meiosis-reinitiation-inducing factor of Tetrahymena was a soluble protein.     

Sexual Conflict over the Maintenance of Sex: Effects of Sexually Antagonistic Coevolution for Reproductive Isolation of Parthenogenesis

Sexual reproduction involves many costs. Therefore, females acquiring a capacity for parthenogenetic (or asexual) reproduction will gain a reproductive advantage over obligately sexual females. In contrast, for males, any trait coercing parthenogens into sexual reproduction (male coercion) increases their fitness and should be under positive selection because parthenogenesis deprives them of their genetic contribution to future generations. Surprisingly, although such sexual conflict is a possible outcome whenever reproductive isolation is incomplete between parthenogens and the sexual ancestors, it has not been given much attention in the studies of the maintenance of sex. Using two mathematical models, I show here that the evolution of male coercion substantially favours the maintenance of sex even though a female barrier against the coercion can evolve. First, the model based on adaptive-dynamics theory demonstrates that the resultant antagonistic coevolution between male coercion and a female barrier fundamentally ends in either the prevalence of sex or the co-occurrence of two reproductive modes. This is because the coevolution between the two traits additionally involves sex-ratio selection, that is, an increase in parthenogenetic reproduction leads to a female-biased population sex ratio, which will enhance reproductive success of more coercive males and directly promotes the evolution of the coercion among males. Therefore, as shown by the individual-based model, the establishment of obligate parthenogenesis in the population requires the simultaneous evolution of strong reproductive isolation between males and parthenogens. These findings should shed light on the interspecific diversity of reproductive modes as well as help to explain the prevalence of sexual reproduction.     

Isotopic Determination and Optimum Reaction Conditions of Pantothenic Acid Synthetase

When yeast protoplasts that were producing repressible acid phosphatase (r-APase) were treated with tunicamycin (TM), three specific proteins of 59k, 57k, and 55k daltons were accumulated in the membrane fraction in addition to the usual membrane proteins and these proteins were not detected in the secreted fraction. These proteins were immunoprecipitated with anti r-APase antiserum. Their molecular sizes were almost the same as those endo-H treated r-APase. Therefore these proteins were considered to be nonglycosylated forms of r-APase proteins. These results proved that nonglycosylated forms of r-APase produced by TM-treatment were not secreted by yeast protoplasts.     

Ecological effects of sex differ with trophic positions in a simple food web

Sexual differences in parental investment, predation pressure, and foraging efforts are common in nature and affect the trophic flow in food webs. Specifically, the sexual differences in predator and prey behavior change in trophic inflow and outflow, respectively, while those in parental investment alter the reproductive allocation of acquired resources in the population. Consequently, these factors may play an important role in determining the system structure and persistence. However, few studies have examined how sexual differences in trophic flow affect food web dynamics. In this study, I show the ecological role of sex by explicitly incorporating sexual differences in trophic flow into a three‐species food web model. The results demonstrated that the ecological waste of males, that is, the amount of trophic inflow into males with less parental investment, plays an important role in system persistence and structure. In particular, the synergy between sexual differences in parental investment and trophic inflows and outflows is important in determining web persistence: Significant impacts of male‐biased trophic flows require the condition of anisogamy. In addition, the dynamic effects of the ecological waste of males differ with trophic level: The coexistence of a food web occurs more frequently with biased inflows into predator males, but occurs less frequently with biased inflows into consumer males. The model analysis indicates that investigating the pattern of sexual differences among trophic positions can enrich our understanding of food web persistence and structure in the real world.     

Direct In Vivo Reprogramming with Sendai Virus Vectors Improves Cardiac Function after Myocardial Infarction

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Immunization of A4galt-deficient mice with glycosphingolipids from renal cell cancers resulted in the generation of anti-sulfoglycolipid monoclonal antibodies

In this study, we immunized Gb3/CD77 synthase gene (A4galt) knockout (KO) mice with glycosphingolipids (GSLs) extracted from 3 renal cell cancer (RCC) cell lines to raise monoclonal antibodies (mAbs) reactive with globo-series GSLs specifically expressed in RCCs. Although a number of mAbs reactive with globo-series GSLs were generated, they reacted with both RCC cell lines and normal kidney cells. When we analyzed recognized antigens by mAbs that were specifically reactive with RCC, but not with normal kidney cells at least on the cell surface, many of them turned out to be reactive with sulfoglycolipids. Eight out of 11 RCC-specific mAbs were reactive with SM2 alone, and the other 3 mAbs were more broadly reactive with sulfated glycolipids, i.e. SM3 and SM4 as well as SM2. In the immunohistochemistry, these anti-sulfoglycolipids mAbs showed RCC-specific reaction, with no or minimal reaction with adjacent normal tissues. Thus, immunization of A4galt KO mice with RCC-derived GSLs resulted in the generation of anti sulfated GSL mAbs, and these mAbs may be applicable for the therapeutics for RCC patients.     

Rho-kinase modulates the function of STEF, a Rac GEF, through its phosphorylation

Rho family GTPases are key regulators of various physiological processes. Several recent studies indicated that the antagonistic relationship between Rho and Rac is essential for cell polarity and that the Rac activity is negatively regulated by Rho. In this study, we found that Rho-kinase, an effector of Rho, counteracted the Rac GEF STEF-induced Rac1 activation in COS7 cells. Rho-kinase phosphorylated STEF at Thr1662 in vitro, and Y-27632, a Rho-kinase inhibitor, suppressed lysophosphatidic acid-induced phosphorylation of STEF in PC12D cells. STEF interacted with specific molecules such as microtubule-associated protein 1B, and the phosphorylation of STEF by Rho-kinase diminished its interaction with these molecules. STEF promoted nerve growth factor-induced neurite outgrowth in PC12D cells, while the phosphomimic mutant of STEF had a weakened ability to enhance neurite outgrowth. Taken together, these results suggest that the phosphorylation of STEF by Rho-kinase exerts the inhibitory effect on the function of STEF.     

Airway epithelial versus immune cell Stat1 function for innate defense against respiratory viral infection

The epithelial surface is often proposed to actively participate in host defense, but evidence that this is the case remains circumstantial. Similarly, respiratory paramyxoviral infections are a leading cause of serious respiratory disease, but the basis for host defense against severe illness is uncertain. Here we use a common mouse paramyxovirus (Sendai virus) to show that a prominent early event in respiratory paramyxoviral infection is activation of the IFN-signaling protein Stat1 in airway epithelial cells. Furthermore, Stat1-/- mice developed illness that resembled severe paramyxoviral respiratory infection in humans and was characterized by increased viral replication and neutrophilic inflammation in concert with overproduction of TNF-alpha and neutrophil chemokine CXCL2. Poor control of viral replication as well as TNF-alpha and CXCL2 overproduction were both mimicked by infection of Stat1-/- airway epithelial cells in culture. TNF-alpha drives the CXCL2 response, because it can be reversed by TNF-alpha blockade in vitro and in vivo. These findings pointed to an epithelial defect in Stat1-/- mice. Indeed, we next demonstrated that Stat1-/- mice that were reconstituted with wild-type bone marrow were still susceptible to infection with Sendai virus, whereas wild-type mice that received Stat1-/- bone marrow retained resistance to infection. The susceptible epithelial Stat1-/- chimeric mice also exhibited increased viral replication as well as excessive neutrophils, CXCL2, and TNF-alpha in the airspace. These findings provide some of the most definitive evidence to date for the critical role of barrier epithelial cells in innate immunity to common pathogens, particularly in controlling viral replication.