Artificial seeding of the green seaweed Monostroma for cultivation

In Japan, the green seaweed Monostroma is an important source of humanfood. Monostroma nitidum Wittrock (Japanese name: hitoegusa) is cultivated in brackish waters and estuaries of central to southern Japan. The green seaweed Monostroma grows in the brackish water area in the upper part of the intertidal zone in the warm waters. Artificial seed culture began with the collection of many gametes in April. The resultant zygotes were allowed to adhere to plastic settlement boards (20 cm long and 10 cm wide). The zygoteboards were then cultured in tanks (1 ×2 ×0.5 m) with fertiliser in a controlled growth room (10–87 μmol photon m^-2s^-1). The cultivated zygotes on the board in the indoor tanks gradually increased in size from 10 to 40 μm in diameter during May to early August. Zygote growth became slowed at the end of August. The zygotesmatured in early September, and the plates were transferred into culture tanks in a dark room for dark treatment. Maturation of the zygote was promoted by providing dark conditions for two weeks. The production of a concentrated zoospore solution from the mature blades was achieved by adding fresh water at temperature 2–3 °C above that of the seeding vats. Zoospores were released in large numbers when exposed to strong irradiance of 100 μmol photon m^-2 s^-1 for 30 min. The zygotes produced flat unicellular fronds at the germling stage. The technology of artificial seed culture and zoospore release from the zygotes is based mainly on these experiments. This revised version was published online in August 2006 with corrections to the Cover Date.     

Volume regulation by flounder red blood cells in anisotonic media

The nucleated high K, low Na red blood cells of the winter flounder demonstrated a volume regulatory response subsequent to osmotic swelling or shrinkage. During volume regulation the net water flow was secondary to net inorganic cation flux. Volume regulation the net water flow was secondary to net inorganic cation flux. Volume regulation after osmotic swelling is referred to as regulatory volume decrease (RVD) and was characterized by net K and water loss. Since the electrochemical gradient for K is directed out of the cell there is no need to invoke active processes to explain RVD. When osmotically shrunken, the flounder erythrocyte demonstrated a regulatory volume increase (RVI) back toward control cell volume. The water movements characteristic of RVI were a consequence of net cellular NaCl and KCl uptake with Na accounting for 75 percent of the increase in intracellular cation content. Since the Na electrochemical gradient is directed into the cell, net Na uptake was the result of Na flux via dissipative pathways. The addition of 10(-4)M ouabain to suspensions of flounder erythrocytes was without effect upon net water movements during volume regulation. The presence of ouabain did however lead to a decreased ration of intracellular K:Na. Analysis of net Na and K fluxes in the presence and absence of ouabain led to the conclusion that Na and K fluxes via both conservative and dissipative pathways are increased in response to osmotic swelling or shrinkage. In addition, the Na and K flux rate through both pump and leak pathways decreased in a parallel fashion as cell volume was regulated. Taken as a whole, the Na and K movements through the flounder erythrocyte membrane demonstrated a functional dependence during volume regulation.     

Cognitive and socio-emotional deficits in platelet-derived growth factor receptor-β gene knockout mice

Platelet-derived growth factor (PDGF) is a potent mitogen. Extensive in vivo studies of PDGF and its receptor (PDGFR) genes have reported that PDGF plays an important role in embryogenesis and development of the central nervous system (CNS). Furthermore, PDGF and the β subunit of the PDGF receptor (PDGFR-β) have been reported to be associated with schizophrenia and autism. However, no study has reported on the effects of PDGF deletion on mice behavior. Here we generated novel mutant mice (PDGFR-β KO) in which PDGFR-β was conditionally deleted in CNS neurons using the Cre/loxP system. Mice without the Cre transgene but with floxed PDGFR-β were used as controls. Both groups of mice reached adulthood without any apparent anatomical defects. These mice were further examined by conducting several behavioral tests for spatial memory, social interaction, conditioning, prepulse inhibition, and forced swimming. The test results indicated that the PDGFR-β KO mice show deficits in all of these areas. Furthermore, an immunohistochemical study of the PDGFR-β KO mice brain indicated that the number of parvalbumin (calcium-binding protein)-positive (i.e., putatively γ-aminobutyric acid-ergic) neurons was low in the amygdala, hippocampus, and medial prefrontal cortex. Neurophysiological studies indicated that sensory-evoked gamma oscillation was low in the PDGFR-β KO mice, consistent with the observed reduction in the number of parvalbumin-positive neurons. These results suggest that PDGFR-β plays an important role in cognitive and socioemotional functions, and that deficits in this receptor may partly underlie the cognitive and socioemotional deficits observed in schizophrenic and autistic patients.     

P2Y12 antagonist attenuates eosinophilic inflammation and airway hyperresponsiveness in a mouse model of asthma

Leukotriene E4 (LTE4) that plays a key role in airway inflammation is expressed on platelets and eosinophils. We investigated whether blocking of the P2Y12 receptor can suppress eosinophilic inflammation in a mouse model of asthma because platelets and eosinophils share this receptor to be activated. BALB/c mice were sensitized by intraperitoneal injection of ovalbumin (OVA), followed by OVA nebulization. On each challenge day, clopidogrel, a P2Y12 antagonist was administered 30 min. before each challenge. Forty‐eight hours after the last OVA challenge, mice were assessed for airway hyperresponsiveness (AHR), cell composition and cytokine levels, including chemokine ligand 5 (CCL5), in bronchoalveolar lavage (BAL) fluid. EOL cells were treated with LTE4, with or without clopidogrel treatment, and intracellular and extracellular eosinophil cationic protein (ECP) expressions were measured to find the inhibiting function of P2Y12 antagonist on eosinophilic activation. The levels of P2Y12 expression were increased markedly in the lung homogenates of OVA‐sensitized and ‐challenged mice after platelet depletion. Administration of clopidogrel decreased AHR and the number of airway inflammatory cells, including eosinophils, in BAL fluid following OVA challenge. These results were associated with decreased levels of Th2 cytokines and CCL5. Histological examination showed that inflammatory cells as well as mucus‐containing goblet cells were reduced in clopidogrel‐administered mice compared to vehicle‐treated mice. Clopidogrel inhibited extracellular ECP secretion after LTE4 stimulation in EOL‐1 cells. Clopidogrel could prevent development of AHR and airway inflammation in a mouse model of asthma. P2Y12 can be a novel therapeutic target to the suppression of eosinophils in asthma.     

Broad-spectrum antioxidant peptides derived from His residue-containing sequences present in human paraoxonase 1

Hydroxyl or peroxyl radicals and hypochlorous acid (HOCl) are known to cause the oxidation of lipoproteins. Here, we examined Cu²⁺-binding property of paraoxonase 1 (PON1), and antioxidant actions of peptides, resembling His residue-containing sequences in PON1, against oxidations by Cu²⁺, peroxyl radicals or HOCl. When Cu²⁺-binding property of PON1 was examined spectrophotometrically, the maximal Cu²⁺ binding was achieved at 1:1 molar ratio of PON1: Cu²⁺. Additionally, Cu²⁺-catalyzed oxidative inactivation of PON1 was prevented by Ca²⁺-depleted PON1 at 1:1 ratio, but not diethylpyrocarbonate (DEPC)-modified PON1, suggesting the participation of His residue in Cu²⁺-binding. When His-containing peptides were examined for antioxidant actions, those with either His residue at N-terminal position 2 or 3, or His-Pro sequence at C-terminal remarkably prevented Cu²⁺-mediated low density lipoprotein (LDL) oxidation and PON1 inactivation. Especially, FHKALY, FHKY or NHP efficiently prevented Cu²⁺-induced LDL oxidation (24 h), indicating a tight binding of Cu²⁺ by peptides. In support of this, the peptide/Cu²⁺ complexes exhibited a superoxide-scavenging activity. Separately, in oxidations by 2,2'-azobis-2-amidinopropane hydrochloride or HOCl, the presence of Tyrosine (Tyr) or Cysteine (Cys) residue markedly enhanced antioxidant action of His-containing peptides. These results indicate that His-containing peptides with Tys or Cys residues correspond to broad spectrum antioxidants in oxidation models employing Cu²⁺, 2,2'-azobis-2-amidinopropane hydrochloride (AAPH) or HOCl.     

Multidrug-resistant Salmonella enterica serovar paratyphi A harbors IncHI1 plasmids similar to those found in serovar typhi

Salmonella enterica serovars Typhi and Paratyphi A cause systemic infections in humans which are referred to as enteric fever. Multidrug-resistant (MDR) serovar Typhi isolates emerged in the 1980s, and in recent years MDR serovar Paratyphi A infections have become established as a significant problem across Asia. MDR in serovar Typhi is almost invariably associated with IncHI1 plasmids, but the genetic basis of MDR in serovar Paratyphi A has remained predominantly undefined. The DNA sequence of an IncHI1 plasmid, pAKU_1, encoding MDR in a serovar Paratyphi A strain has been determined. Significantly, this plasmid shares a common IncHI1-associated DNA backbone with the serovar Typhi plasmid pHCM1 and an S. enterica serovar Typhimurium plasmid pR27. Plasmids pAKU_1 and pHCM1 share 14 antibiotic resistance genes encoded within similar mobile elements, which appear to form a 24-kb composite transposon that has transferred as a single unit into different positions into their IncHI1 backbones. Thus, these plasmids have acquired similar antibiotic resistance genes independently via the horizontal transfer of mobile DNA elements. Furthermore, two IncHI1 plasmids from a Vietnamese isolate of serovar Typhi were found to contain features of the backbone sequence of pAKU_1 rather than pHCM1, with the composite transposon inserted in the same location as in the pAKU_1 sequence. Our data show that these serovar Typhi and Paratyphi A IncHI1 plasmids share highly conserved core DNA and have acquired similar mobile elements encoding antibiotic resistance genes in past decades.     

Preferable stimulation of PON1 arylesterase activity by phosphatidylcholines with unsaturated acyl chains or oxidized acyl chains at sn-2 position

To examine the effect of phospholipids on PON1 activities, purified PON1 was exposed to phospholipids prior to the determination of arylesterase and paraoxonase activities. Phosphatidylcholines with saturated acyl chains (C10-C16) showed a stimulation of both activities, chain length-dependent, with a greater stimulation of arylesterase activity, suggesting the implication of lipid bilayer in the stimulatory action. Such a preferable stimulation of arylesterase activity was more remarkable with phosphatidylcholines with polyunsaturated acyl chains or oxidized chains at sn-2 position, implying that the packing degree of acyl chain may be also important for the preferable stimulation of arylesterase activity. Separately, 1-palmitoyl-lysoPC also stimulated arylesterase activity preferably, indicating that the micellar formation of lipids around PON1 also contributes to the stimulatory action. Additionally, phosphatidylglycerols slightly enhanced arylesterase activity, but not paraoxonase activity. In contrast, phosphatidylserine and phosphatidic acid (≥0.1 mM) inhibited both activities Further, such a preferable stimulation of arylesterase activity by phosphatidylcholines was also reproduced with VLDL-bound PON1, although to a less extent. These data indicate that phosphatidylcholines with polyunsaturated acyl chains or oxidized chain, or lysophosphatidylcholine cause a preferable stimulation of arylesterase activity, thereby contributing to the decrease in the ratio of paraoxonase activity to arylesterase activity.     

Rational Design of Core@shell Structured CoSx@Cu2MoS4 Hybridized MoS2/N,S‐Codoped Graphene as Advanced Electrocatalyst for Water Splitting and Zn‐Air Battery

A novel hybrid of small core@shell structured CoS_x@Cu₂MoS₄ uniformly hybridizing with a molybdenum dichalcogenide/N,S‐codoped graphene hetero‐network (CoS_x@Cu₂MoS₄‐MoS₂/NSG) is prepared by a facile route. It shows excellent performance toward the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) in alkaline medium. The hybrid exhibits rapid kinetics for ORR with high electron transfer number of ≈3.97 and exciting durability superior to commercial Pt/C. It also demonstrates great potential with remarkable stability for HER and OER, requiring low overpotential of 118.1 and 351.4 mV, respectively, to reach a current density of 10 mA cm^?2. An electrolyzer based on CoS_x@Cu₂MoS₄‐MoS₂/NSG produces low cell voltage of 1.60 V and long‐term stability, surpassing a device of Pt/C + RuO₂/C. In addition, a Zn‐air battery using cathodic CoS_x@Cu₂MoS₄‐MoS₂/NSG catalyst delivers a high cell voltage of ≈1.44 V and a power density of 40 mW cm^?2 at 58 mA cm^?2, better than the state‐of‐the‐art Pt/C catalyst. These achievements are due to the rational combination of highly active core@shell CoS_x@Cu₂MoS₄ with large‐area and high‐porosity MoS₂/NSG to produce unique physicochemical properties with multi‐integrated active centers and synergistic effects. The outperformances of such catalyst suggest an advanced candidate for multielectrocatalysis applications in metal‐air batteries and hydrogen production.