Blooms of tunicates Oikopleura spp. and Dolioletta gegenbauri in the Seto Inland Sea, Japan, during summer

The ecological importance of appendicularians Oikopleura dioica and O. longicauda, and a doliolid Dolioletta gegenbauri as metazoan secondary producers was assessed in summer 1997 in the Seto Inland Sea, Japan. Blooms by the appendicularians occurred twice within a month following peaks of pico-/nanoplankton biomass. The biomass of Oikopleura spp. averaged over the water column (<B> ranged 0.1 to 8.0 μgC l-¹ and temporal average of <B> over the survey period ( ) was 3.2 μgC l-¹, 70% of for calanoid copepods. Furthermore, the temporal average of the production for Oikopleura spp. was 2.4 times higher than that for calanoids, reflecting the extraordinary high growth rates of the appendicularians. D. gegenbauri developed its population following a diatom bloom and <B> reached to 37 μgC l-¹ at the peak time. Although individuals of D. gegenbauri were seldom observed during the first half of the survey, for the doliolid (8.4 μgC l-¹) nearly doubled that for calanoids. These results indicate that the gelatinous tunicates Oikopleura spp. and D. gegenbauri play important roles as metazoan secondary producers in the Seto Inland Sea during summer. This revised version was published online in September 2006 with corrections to the Cover Date.     

Synthesis,in vitro and in vivo studies of Gd-DTPA-XDA-D1-Glc(OH) complex as a new potential MRI contrast agent

A new type of dendritic molecules Gd-DTPA-XDA-D1-Glc(OH), which work as a functionalized ligand coordinating gadolinium(III) ion at the center of their frameworks with two glucose moieties on the molecular surfaces, were readily synthesized with high yield. The structures were established by IR, ¹H, ¹³C NMR, and mass spectral studies. Its bio-distribution patterns were evaluated on rats.     

The Large Isoform of Myelin-Associated Glycoprotein Is Scarcely Expressed in the Quaking Mouse Brain

Two polypeptide isoforms of myelin-associated glycoprotein (MAG) with molecular masses of 72 and 67 kDa are produced by alternative splicing of the exon 12 portion. Our previous work has demonstrated that in the quaking mouse brain this alternative splicing is lacking and that the mRNA coding the large MAG isoform (L-MAG) is scarcely expressed, whereas that of small MAG isoform (S-MAG) is overexpressed. In the present study, we prepared antisera specific to the S-MAG and L-MAG amino acid residues, respectively. Immunoblots showed that the L-MAG band was scarcely detectable in the quaking mouse brain, whereas the S-MAG band had an apparently higher molecular mass than in the normal control. Our immunohistochemical study also showed that L-MAG was scarcely stained in the quaking mouse brain. These results seemed to reflect a reduction in content of L-MAG mRNA and abnormal glycosylation in the quaking mouse brain.     

Estimating hominid life history: the critical interbirth interval

Unlike any great apes, humans have expanded into a wide variety of habitats during the course of evolution, beginning with the transition by australopithecines from forest to savanna habitation. Novel environments are likely to have imposed hominids a demographic challenge due to such factors as higher predation risk and scarcer food resources. In fact, recent studies have found a paucity of older relative to younger adults in hominid fossil remains, indicating considerably high adult mortality in australopithecines, early Homo, and Neanderthals. It is not clear to date why only human ancestors among all hominoid species could survive in these harsh environments. In this paper, we explore the possibility that hominids had shorter interbirth intervals to enhance fertility than the extant apes. To infer interbirth intervals in fossil hominids, we introduce the notion of the critical interbirth interval, or the threshold length of birth spacing above which a population is expected to go to extinction. We develop a new method to obtain the critical interbirth intervals of hominids based on the observed ratios of older adults to all adults in fossil samples. Our analysis suggests that the critical interbirth intervals of australopithecines, early Homo, and Neanderthals are significantly shorter than the observed interbirth intervals of extant great apes. We also discuss possible factors that may have caused the evolutionary divergence of hominid life history traits from those of great apes.     

Release of erythrocytes from the spleen during exercise and splenic constriction by adrenaline infusion in the rainbow trout

Erythrocyte-supplying function of the spleen was examined in the rainbow troutSalmo gairdneri under exercise. The spleen showed remarkable reduction, about 70% in weight and about 85% in hemoglobin content, after forced exercise of 15 min. The amount of erythrocytes released from the spleen was 2.33 ml/kg body, and this amount corresponds to about 20% of the total volume of circulating erythrocytes in resting condition. No damage was observed at the spleen, splenic artery and splenic vein after the exercise. Examination of the vascular system by a corrosion casting method showed that no place other than the venous circulation exists for the erythrocytes released from the contracted spleen. The spleen was strongly constricted by infusion of adrenaline into the organ. These facts imply that the fish spleen supplies stored hemoglobin into the circulating blood in response to an increased demand of oxygen during exercise, under the control of the sympathetic nervous system.     

Interaction between a negative regulator (Msa2/Nrd1) and a positive regulator (Cpc2) of sexual differentiation in Schizosaccharomyces pombe

The sexual differentiation of Schizosaccharomyces pombe is controlled by many cellular components which have not been fully characterized. We isolated a gene called msa2 as a multi-copy suppressor of a sporulation abnormal mutant (sam1). Msa2p is identical with Nrd1p which has been characterized as a factor that blocks the onset of sexual differentiation. The yeast two-hybrid system was used to identify Cpc2p, a fission yeast homolog of the RACK1 protein, that interacted with Msa2p/Nrd1p. We confirmed that Msa2p/Nrd1p interacted with Cpc2p in S. pombe cells. An epistatic analysis of msa2/nrd1 and cpc2 suggests that Msa2p/Nrd1p was an upstream regulator for Cpc2p. A localization analysis of Cpc2p and Msa2p/Nrd1p indicates that both proteins were predominantly localized in the cytoplasm. The interaction of negative regulator Msa2p/Nrd1p with positive regulator Cpc2p suggests a new regulatory circuit in the sexual differentiation of S. pombe.     

Recovery of phosphorous from swine wastewater through crystallization

All the phosphate rock Japan needs must be presently imported from abroad because the country has no subterranean phosphorous resources. Therefore, there is a need to accelerate the development of and establish the technologies for phosphorous recovery from waste and wastewater. Swine wastewater has a high potential for phosphorous recovery in Japan. A reactor for removing and recovering phosphorous from swine wastewater was designed with dual functions, crystallization through aeration and separation of formed struvite by settling. However, a dehydration, composting and characterization process was first needed before using sediment sludge, including struvite, on farmland, since the struvite will settle along with huge amounts of other suspended solids (organic matter). For the recovery of pure struvite, an accumulation device was designed and its efficiency examined. The device has a struvite-accumulation face made of stainless steel wire mesh (1 mm in diameter, 1 cm(2) square) to reduce its total weight. During submergence in the aeration column of the demonstration reactor, struvite cross-bridged and accumulated on the face of the device. The struvite could be scraped off easily with only a light brushing, and was found to be approximately 95% pure. Because this device is a very simple structure, it is thought to be acceptable to swine farmers.     

Lipoplex size determines lipofection efficiency with or without serum

In order to identify factors affecting cationic Iiposome-mediated gene transfer, the relationships were examined among cationic liposome/DNA complex (lipoplex)-cell interactions, lipoplex size and lipoplex-mediated transfection (lipofection) efficiency. It was found that lipofection efficiency was determined mainly by lipoplex size, but not by the extent of lipoplex-cell interactions including binding, uptake or fusion. In addition, it was found that serum affected mainly lipoplex size, but not lipoplex-cell interactions, which effect was the major reason behind the inhibitory effect of serum on lipofection efficiency. It was concluded that, in the presence or absence of serum, lipoplex size is a major factor determining Iipofection efficiency. Moreover, in the presence or absence of serum, lipoplex size was found to affect lipofection efficiency by controlling the size of the intracellular vesicles containing lipoplexes after internalization, but not by affecting lipoplex-cell interactions. In addition, large lipoplex particles showed, in general, higher lipofection efficiency than small particles. These results imply that, by controlling lipoplex size, an efficient lipid delivery system may be achieved for in vitro and in vivo gene therapy.