Effect of polyamines on in vitro reconstitution of ribosomal subunits

The effect of polyamines on in vitro reconstitution of Escherichia coli 30S and 50S ribosomal subunits has been studied. Spermidine stimulated the reconstitution of 30S particles from 16S rRNA lacking the methyl groups on two neighboring adenines and total proteins of 30S subunits at least 1.6-fold. The reconstitution of 30S particles from normal 16S rRNA and total proteins of 30S subunits exhibited only slight spermidine stimulation. However, the optimal Mg2+ concentration of the reconstitution was decreased from 20 mM to 16 mM in the presence of 3 mM spermidine. In the absence of spermidine the assembly of 30S particles from normal 16S rRNA was more rapid than the assembly from 16S rRNA lacking the methyl groups on two neighboring adenines. The reconstitution of 50S particles from 23S and 5S rRNA and total proteins of 50S subunits was not influenced greatly by spermidine. Gel electrophoresis results, from reconstitution experiments of 30S particles from 16S rRNA lacking the methyl groups on two neighboring adenines and total proteins of 30S subunits, showed that the assembly of S1 and S9 proteins to 23S core particles was stimulated by spermidine during reconstitution. The relationship of polyamine effects on in vitro ribosome assembly from its constituents to in vivo ribosome assembly is discussed. The reconstitution of Bacillus subtilis 30S particles from 16S rRNA and total proteins of 30S subunits was also stimulated approximately 1.3-fold by 3 mM spermidine.     

Histological and Transcriptomic Analysis of Adult Japanese Medaka Sampled Onboard the International Space Station

To understand how humans adapt to the space environment, many experiments can be conducted on astronauts as they work aboard the Space Shuttle or the International Space Station (ISS). We also need animal experiments that can apply to human models and help prevent or solve the health issues we face in space travel. The Japanese medaka (Oryzias latipes) is a suitable model fish for studying space adaptation as evidenced by adults of the species having mated successfully in space during 15 days of flight during the second International Microgravity Laboratory mission in 1994. The eggs laid by the fish developed normally and hatched as juveniles in space. In 2012, another space experiment (“Medaka Osteoclast”) was conducted. Six-week-old male and female Japanese medaka (Cab strain osteoblast transgenic fish) were maintained in the Aquatic Habitat system for two months in the ISS. Fish of the same strain and age were used as the ground controls. Six fish were fixed with paraformaldehyde or kept in RNA stabilization reagent (n = 4) and dissected for tissue sampling after being returned to the ground, so that several principal investigators working on the project could share samples. Histology indicated no significant changes except in the ovary. However, the RNA-seq analysis of 5345 genes from six tissues revealed highly tissue-specific space responsiveness after a two-month stay in the ISS. Similar responsiveness was observed among the brain and eye, ovary and testis, and the liver and intestine. Among these six tissues, the intestine showed the highest space response with 10 genes categorized as oxidation–reduction processes (gene ontogeny term GO:0055114), and the expression levels of choriogenin precursor genes were suppressed in the ovary. Eleven genes including klf9, klf13, odc1, hsp70 and hif3a were upregulated in more than four of the tissues examined, thus suggesting common immunoregulatory and stress responses during space adaptation.     

A game theoretical model of deforestation in human-environment relationships

We studied a two-person game regarding deforestation in human-environment relationships. Each landowner manages a single land parcel where the state of land-use is forested, agricultural, or abandoned. The landowner has two strategies available: forest conservation and deforestation. The choice of deforestation provides a high return to the landowner, but it degrades the forest ecosystem services produced on a neighboring land parcel managed by a different landowner. Given spatial interactions between the two landowners, each landowner decides which strategy to choose by comparing the expected discounted utility of each strategy. Expected discounted utility is determined by taking into account the current and future utilities to be received, according to the state transition on the two land parcels. The state transition is described by a Markov chain that incorporates a landowner's choice about whether to deforest and the dynamics of agricultural abandonment and forest regeneration. By considering a stationary distribution of the Markov chain for land-use transitions, we derive explicit conditions for Nash equilibrium. We found that a slow regeneration of forests favors mutual cooperation (forest conservation). As the forest regenerates faster, mutual cooperation transforms to double Nash equilibria (mutual cooperation and mutual defection), and finally mutual defection (deforestation) leads to a unique Nash equilibrium. Two different types of social dilemma emerge in our deforestation game. The stag-hunt dilemma is most likely to occur under an unsustainable resource supply, where forest regenerates extremely slowly but agricultural abandonment happens quite rapidly. In contrast, the prisoner's dilemma is likely under a persistent or circulating supply of resources, where forest regenerates rapidly and agricultural abandonment occurs slowly or rapidly. These results show how humans and the environment mutually shape the dilemma structure in forest management, implying that solutions to dilemmas depend on environmental properties.     

Variation in seed production schedule among individual trees of a deciduous oak species <Emphasis Type="Italic">Quercus serrata</Emphasis>: its relation to seed characteristics

Intraspecific variation in seed production schedule and its effects on seed characteristics were examined in the deciduous oak species Quercus serrata in Iwate Prefecture, northern Japan. Seed production schedule differed markedly among 31 individual trees. The median dates of seed production differed by over 1 month between the earliest and latest individuals. Relationships between seed production schedule and seed characteristics were investigated at two different scales: the among-tree scale and the within-tree scale. At the within-tree scale, analyses revealed that the seeds dispersed by a tree later in the season tended to be larger in size and lower in tannin concentration. Similarly, at the among-tree scale, analysis revealed that trees with a later seed production schedule produced on average larger acorns. However, no clear tendency was observed between seed production schedule and mean tannin concentration. The observed variation in seed production schedule is likely to affect seed fate per se, and also via changes in seed characteristics.     

Eotaxin-3/CC chemokine ligand 26 is a functional ligand for CX3CR1

Eotaxin-3/CCL26 is a functional ligand for CCR3 and abundantly produced by IL-4-/IL-13-stimulated vascular endothelial cells. CCL26 also functions as a natural antagonist for CCR1, CCR2, and CCR5. In this study, we report that CCL26 is yet a functional ligand for CX3CR1, the receptor for fractalkine/CX3CL1, which is expressed by CD16(+) NK cells, cytotoxic effector CD8(+) T cells, and CD14(low)CD16(high) monocytes. Albeit at relatively high concentrations, CCL26 induced calcium flux and chemotaxis in mouse L1.2 cells expressing human CX3CR1 but not mouse CX3CR1 and competed with CX3CL1 for binding to CX3CR1. In chemotaxis assays using human PBMCs, CCL26 attracted not only eosinophils but also CD16(+) NK cells, CD45RA(+)CD27(-)CD8(+) T cells, and CD14(low)CD16(high) monocytes. Intraperitoneal injection of CCL26 into mice rapidly recruited mouse eosinophils and intravenously transferred human CD16(+) NK cells into the peritoneal cavity. IL-4-stimulated HUVECs produced CCL26 and efficiently induced adhesion of cells expressing CX3CR1. Real-time PCR showed that skin lesions of psoriasis consistently contained CX3CL1 mRNA but not CCL26 mRNA, whereas those of atopic dermatitis contained CCL26 mRNA in all samples but CX3CL1 mRNA in only about half of the samples. Nevertheless, the skin lesions from both diseases consistently contained CX3CR1 mRNA at high levels. Thus, CCL26 may be partly responsible for the recruitment of cells expressing CX3CR1 in atopic dermatitis particularly when the expression of CX3CL1 is low. Collectively, CCL26 is another agonist for CX3CR1 and may play a dual role in allergic diseases by attracting eosinophils via CCR3 and killer lymphocytes and resident monocytes via CX3CR1.     

Phosphorylation of carnitine palmitoyltransferase and activation by glucagon in isolated rat hepatocytes

Effects of glucagon and forskolin on the phosphorylation and changes of activity of carnitine palmitoyltransferase (CPT) have been studied in isolated rat hepatocytes using anti-CPT immunoglobulin. When the activity was determined in lysed hepatocytes after glucagon or forskolin treatment, it was found to be stimulated 30-80% mainly through increased affinity for palmitoyl-CoA. By SDS electrophoresis of the immunoprecipitates, CPT subunit (Mr 69000) was noted to be phosphorylated 4-5-fold with glucagon (1.2 X 10(-7) M) and forskolin (0.1 mM) over control. These results indicate that hepatic ketogenesis is regulated with glucagon by phosphorylation of CPT through cAMP-dependent protein kinase.     

Annual and seasonal changes in foraging site and diving behavior in Adélie penguins

Foraging sites, diet, and diving behavior of chick-rearing Adélie penguins, Pygoscelis adeliae, in fast sea-ice areas were investigated during two consecutive seasons with contrasting sea-ice conditions. During 1995/1996, fast sea ice covered the foraging range of penguins during the whole breeding season. In contrast, during 1996/1997, sea ice covered the area in December 1996, but gradually thinned and finally broke up, so that open sea appeared along the coast during February 1997. Foraging sites were concentrated in a small area in 1995/1996 and spread over a wider area in 1996/1997 as more small open-water areas were available. In both seasons, parents traveled to more distant foraging sites as the season progressed and, consequently, the foraging-trip duration increased. In both years, Euphausia superba and Pagothenia borchgrevinki dominated the diet in the early part of the season, while later in the season penguins fed mainly on E. superba in 1995/1996 and Pagothenia borchgrevinki and E. crystallorophias in 1996/1997. In 1995/1996, penguins tended to dive deeper—albeit for a relatively shorter duration—when feeding mainly on krill compared to when feeding on fish. In 1996/1997, there was no difference in the dive depth and duration between krill- and fish-eating trips. Our results suggest that prey distribution changes annually and seasonally, probably according to sea-ice conditions, and that consequently penguins modify their foraging sites, diving patterns, and diet according to these changes.