Diel changes in vertical distribution of Oithona similis (Cyclopoida) and Oncaea curvata (Poecilostomatoida) under sea ice in mid-summer near Syowa Station, Antarctica

The diel vertical distributions of two small copepods, Oithona similis and Oncaea curvata, were investigated at 4-h intervals over a 24-h period under fast ice near Syowa Station during continuous daylight conditions in the Antarctic mid-summer, December 1993. Oithona similis and O. curvata exhibited small-scale diel vertical migrations during the study period, in a way opposite to what is expected, i.e., remaining mostly in the upper layer during the day and moving into deeper layers at night. The nighttime descent of both species coincided with the time of disappearance of a high algal concentration at the ice–water interface during the day and an increase of the algal concentration in the mid-water layer at night. This suggests the migration behavior of the copepods was responsible for the change of food availability. The daily grazing impact of these copepods was estimated to remove one-third of the algae daily released from ice during mid-summer at Syowa Station.     

Short daytime naps in a car seat to counteract daytime sleepiness: The effect of backrest angle

Sleep and Biological Rhythms - A short nap of less than 30 min is an effective countermeasure to prevent afternoon sleepiness and resulting sleep-related accidents. This study was designed to...     

Induction of apoptosis in Epstein-Barr virus-infected B-lymphocytes by the NF-kappaB inhibitor DHMEQ

Epstein-Barr virus (EBV) causes EBV-associated lymphoproliferative diseases in patients with profound immune suppression. Most of these diseases are life-threatening and the prognosis of AIDS-associated lymphomas is extremely unfavorable. Polyclonal expansion of virus infected B-cell predisposes them to transformation. We investigated the possibility of nuclear factor kappa B (NF-kappaB) inhibition by dehydroxymethylepoxyquinomicin (DHMEQ) for the treatment and prevention of EBV-associated lymphoproliferative diseases. We examined the effect of DHMEQ on apoptosis induction in four EBV-transformed lymphoblastoid cell lines as well as peripheral blood mononuclear cells infected with EBV under immunosuppressed condition. DHMEQ inhibits NF-kappaB activation in EBV-transformed lymphoblastoid cell lines and induces apoptosis by activation of mitochondrial and membranous pathways. Using an in vivo NOD/SCIDgammac mouse model, we showed that DHMEQ has a potent inhibitory effect on the growth of lymphoblastoid cells. In addition, DHMEQ selectively purges EBV-infected cells expressing latent membrane protein (LMP) 1 from peripheral blood mononuclear cells and inhibits the outgrowth of lymphoblastoid cells. These results suggest that NF-kappaB is a molecular target for the treatment and prevention of EBV-associated lymphoproliferative diseases. As a potent NF-kappaB inhibitor, DHMEQ is a potential compound for applying this strategy in clinical medicine.     

Disassembly of lignin and chemical recovery in supercritical water and p-cresol mixture. Studies on lignin model compounds

The aim of the study was to gain insight into the role of the each unit of lignin in the formation of products. Glycerol, guaiacol, the mixture of glycerol and guaiacol (Gly&Gua), and guaiacylglycerol-beta-guaiacyl ether (GGGE) were used as lignin model compounds to study fragmentation of lignin in an excess of water and p-cresol at 400 degrees C. The products have been analyzed employing gas chromatography (GC)-mass spectrometer (MS) and gas chromatography-frame ionization detector for qualitative and quantitative analysis. GC-MS analysis indicated that phenol, o-cresol, methyl-anisole, di-methyl-phenol, ethyl-methyl-phenol, 2-(hydroxy-benzyl)-4-methyl-phenol (BMP) and 2-(2-hydroxy-5-methyl-benzyl)-4-methyl-phenol were formed. The products were similar to the products by the fragmentation of lignin. The products, except o-cresol, were primarily derived from glycerol and/or guaiacol. We also found that the amount of BMP derived from GGGE, which has glycerol unit and guaiacol unit in its structure, is much more than that derived from Gly&Gua. The increase of the BMP yield by reaction with GGGE compared with (glycerol and/or guaiacol) indicates that guaiacylglycerol unit with linkage of Gly&Gua plays an important role in the formation of BMP and also it is suggested that the BMP formation from GGGE has pathways other than that from Gly&Gua.     

Cleavage-mediated activation of Chk1 during apoptosis

The Chk1 kinase is highly conserved from yeast to humans and is well known to function in the cell cycle checkpoint induced by genotoxic or replication stress. The activation of Chk1 is achieved by ATR-dependent phosphorylation with the aid of additional factors. Robust genotoxic insults induce apoptosis instead of the cell cycle checkpoint, and some of the components in the ATR-Chk1 pathway are cleaved by active caspases, although it has been unclear whether the attenuation of the ATR-Chk1 pathway has some role in apoptosis induction. Here we show that Chk1 is activated by caspase-dependent cleavage when the cells undergo apoptosis. Treatment of chicken DT40 cells with various genotoxic agents, UV light, etoposide, or camptothecin induced Chk1 cleavage, which was inhibited by a pan-caspase inhibitor, benzyloxycarbonyl-VAD-fluoromethyl ketone. The cleavage of Chk1 was similarly observed in human Jurkat cells treated with a non-genotoxic apoptosis inducer, staurosporine. We have determined the cleavage site(s), Asp-299 in chicken and Asp-299 and Asp-351 in human cells. We further show that a truncated form of human Chk1 mimicking the N-terminal cleavage fragment (residues 1-299) possesses strikingly elevated kinase activity. Moreover, the ectopic expression of Chk1-(1-299) in human U2OS cells induces abnormal nuclear morphology with localized chromatin condensation and phosphorylation of histone H2AX. These results suggest that Chk1 is activated by caspase-mediated cleavage during apoptosis and might be implicated in enhancing apoptotic reactions rather than attenuating the ATR-Chk1 pathway.     

Effects of dimethyl sulphoxide and dexamethasone on mRNA expression of myogenesis- and muscle proteolytic system-related genes in mouse myoblastic C2C12 cells

We examined the time course of mRNA expression of myogenic cell differentiation- and muscle proteolytic system-related genes in cultures of C2C12 cells during differentiation from myoblasts to myotubes. Furthermore, we treated C2C12 myotubes with dimethyl sulphoxide (DMSO) and dexamethasone (Dex), and examined changes in these mRNA levels. Myogenin (Myog), Atrogin1, forkhead box O1 (Foxo1) and Capn1 mRNA levels increased in C2C12 cells differentiating from myoblasts to myotubes, whereas Myf5 mRNA levels decreased. Although genes such as MRF4, Foxo3a, UbB, Capn1 and MuRF1 mRNAs in the myotubes were affected by DMSO exposure, mRNA levels of other genes were not markedly affected by exposure to 0.02% or 0.5% DMSO. Myf5, MRF4, Atrogin1, Foxo3 and MuRF1 mRNA levels were elevated by Dex at all time points, Cbl and Capn1 mRNA levels were significantly elevated by Dex at 8 h, and Myog mRNA levels were significantly elevated by Dex at 24 h. However, CtsH mRNA levels decreased significantly with Dex at 24 h. This study provides a useful database of gene profiles that are differentially expressed throughout myogenic cell differentiation and the muscle proteolytic system.     

Smooth muscle myosin phosphorylated at single head shows sustained mechanical activity

Smooth muscle contraction is regulated by the phosphorylation of myosin. It is well known that tonic smooth muscles can maintain force with low energy consumption (latch state); however, the molecular mechanism underlying this phenomenon is unresolved. Here we show that single-head phosphorylated smooth myosin (SHPMII) exhibits fast ( approximately 24 s(-1)) and slow prolonged ( approximately 1 s(-1)) actin interactions, whereas double-head phosphorylated myosin (DHPMII) predominantly exhibits the fast ( approximately 29 s(-1)) interaction, suggesting that the phosphorylated head of SHPMII is mechanically as active as that of DHPMII. Both the fast and the slow actin interactions of SHPMII support the positive net mechanical displacement of actin. The actin translocating velocity of SHPMII was much slower than that of DHPMII, which is consistent with the slow actin interaction of SHPMII. We propose that the "latch state" can be explained by the motor characteristics of SHPMII that is present during the sustained phase of contraction.     

Human anti-gold antibodies: biofunctionalization of gold nanoparticles and surfaces with anti-gold antibodies

The interface molecules designed to exhibit molecular recognitions between different species have become attractive tools for the bottom-up fabrication and hybridization of nanostructured units. Here, we focus on antibodies with high binding ability and specificity to construct a novel biomolecule interface for recognizing an inorganic material. Careful selection from a phage-displayed library of variable region heavy and light Fv chains of human antibodies using enzyme-linked immunosorbent assay and surface plasmon resonance assay resulted in the identification of an antibody fragment, A14P-b2, with high affinity (KD = 1.7 nm) and specificity for gold materials. Our results indicated the potential usefulness of human antibody libraries and the effectiveness of the antibody framework for recognizing bulk material surfaces. Construction of bivalent and bispecific antibodies on the A14P-b2 platform with high affinity by means of fusion technology enabled the functionalization of gold nanoparticles and allowed selective protein accumulation on gold spots patterned on a silicon substrate. This type of antibody engineering is potentially applicable to bio-inspired materials and nanobiosensing.     

Gabapentin produces PKA-dependent pre-synaptic inhibition of GABAergic synaptic transmission in LC neurons following partial nerve injury in mice

We have previously demonstrated that gabapentin supraspinally activates the descending noradrenergic system to ameliorate pain hypersensitivity in mice with partial nerve ligation. To clarify the supraspinal mechanism of action of gabapentin, whole-cell patch-clamp recordings were performed on locus coeruleus (LC) neurons in brainstem slices prepared from mice after peripheral nerve injury or mice subjected to a sham-operation, and the effects of gabapentin in the modulation of synaptic transmission were studied. Bath application of gabapentin (10, 30 and 100 μM) in a concentration-dependent manner reduced the GABA_A receptor-mediated inhibitory post-synaptic currents (IPSCs) in slices prepared from partially nerve-ligated mice, whereas glutamate-mediated excitatory post-synaptic currents were hardly affected. By contrast, gabapentin did not reduce IPSCs in slices taken from mice given a sham operation. Although gabapentin altered neither the amplitude nor the frequency of miniature IPSCs, it reduced IPSCs together with an increase in the paired-pulse ratio, suggesting that gabapentin acts on the pre-synaptic GABAergic nerve terminals in the LC. As the protein kinase A (PKA) inhibitor H-89 but not the protein kinase C inhibitor chelerythrine abolished the inhibitory action of gabapentin on IPSCs, PKA-mediated phosphorylation seems to be important for supraspinal gabapentin responsiveness in neuropathic conditions. Together, gabapentin generates PKA-dependent pre-synaptic inhibition of GABAergic synaptic transmission, and thereby removes the inhibitory influence on LC neurons only under neuropathic pain states. These findings provide crucial evidence of how supraspinally acting gabapentin recruits the descending noradrenergic system.