Stabilizing effect of Ca<Superscript>2+</Superscript> on myosin and myofibrils of squid mantle muscle as affected by heating conditions

The suppressive effects of Ca²⁺ on the thermal denaturation of myosin and myofibrils of squid mantle muscle were compared. The stabilization effect on myosin was smaller than that on myofibrils and was not affected by KCl concentration. The stabilizing effect of Ca²⁺ on myosin decreased as the heating temperature dropped, showing no stabilization at 20°C, while the effect on myofibrils was the same at all temperatures tested. The stabilizing effect of Ca²⁺ on myosin disappeared even at 30°C in the presence of sorbitol, where a small inactivation rate was found, while the effect of Ca²⁺ on myofibrils was equally detected irrespective of the reduction in inactivation rate in the presence of sorbitol. Stabilization of myosin by Ca²⁺ again appeared even in the presence of sorbitol when the heating temperature was raised to 38°C. It was suggested that Ca²⁺ confers stabilization on myosin only when myosin is under unstable conditions. The stabilization effect of Ca²⁺ on myosin was enhanced upon F-actin binding: Ca²⁺-bound myosin was more significantly stabilized by F-actin binding, and the effect was no longer affected by the conditions for heating.     

AKD-2023: A novel miticide. Biological activity and mode of action

AKD-2023, 3-dodecyl-1,4-dihydro-1,4-dioxo-2-naphthyl acetate (proposed common name acequinocyl) is a novel miticide now under commercial development. It has outstanding miticidal activity against economically important spider mites with the new mode of action of inhibition of mitochondrial electron transfer at complex III.     

Correction to: Development of an efficient bioreactor system for delivering foreign proteins secreted from liver into eggs with a vitellogenin signal in medaka Oryzias latipes

Fisheries Science - The article "Development of an efficient bioreactor system for delivering foreign proteins secreted from liver into eggs with a vitellogenin signal in medaka Oryzias...     

No evidence of horizontal infection in horses kept in close contact with dogs experimentally infected with canine influenza A virus (H3N8)

Background

Since equine influenza A virus (H3N8) was transmitted to dogs in the United States in 2004, the causative virus, which is called canine influenza A virus (CIV), has become widespread in dogs. To date, it has remained unclear whether or not CIV-infected dogs could transmit CIV to horses. To address this, we tested whether or not close contact between horses and dogs experimentally infected with CIV would result in its interspecies transmission.

Methods

Three pairs of animals consisting of a dog inoculated with CIV (10^8.3 egg infectious dose₅₀/dog) and a healthy horse were kept together in individual stalls for 15 consecutive days. During the study, all the dogs and horses were clinically observed. Virus titres in nasal swab extracts and serological responses were also evaluated. In addition, all the animals were subjected to a gross pathological examination after euthanasia.

Results

All three dogs inoculated with CIV exhibited clinical signs including, pyrexia, cough, nasal discharge, virus shedding and seroconversion. Gross pathology revealed lung consolidations in all the dogs, and Streptococcus equi subsp. zooepidemicus was isolated from the lesions. Meanwhile, none of the paired horses showed any clinical signs, virus shedding or seroconversion. Moreover, gross pathology revealed no lesions in the respiratory tracts including the lungs of the horses.

Conclusions

These findings may indicate that a single dog infected with CIV is not sufficient to constitute a source of CIV infection in horses.     

Acute lipoprivation suppresses pulsatile luteinizing hormone secretion without affecting food intake in female rats

The present study examined the effect of acute lipoprivation on pulsatile luteinizing hormone (LH) secretion in both normal-fat diet, ad libitum-fed and fasted female rats. To produce an acute lipoprivic condition, mercaptoacetate (MA), an inhibitor of fatty acid oxidation, was administered intraperitoneally to ad libitum-fed or 24-h fasted ovariectomized (OVX) rats with or without an estradiol (E2) implant, that produces a negative feedback effect on LH pulses. The steroid treatment was performed to determine the effect of estrogen on lipoprivic changes in LH release, because estrogen enhances fasting- or glucoprivation-induced suppression of LH pulses. Pulsatile LH secretion was suppressed by MA administration in a dose-dependent manner in the ad libitum-fed OVX and OVX+E2 rats. LH pulses were more severely suppressed in the 24-h-fasted OVX and OVX+E2 rats compared to the ad libitum-fed rats. Estrogen slightly enhanced lipoprivic suppression but the effect was not significant. In the present study, increased plasma glucose and free-fatty acid concentrations may indicate a blockade of fatty acid metabolism by the MA treatment, but food intake was not affected by any of the MA doses. Acute vagotomy did not block lipoprivic suppression of LH pulses. Thus, the present study indicates that lipid metabolism is important for maintenance of normal reproductive function even in rats fed a normal-fat diet and lipoprivation may be more critical in fasted animals that probably rely more heavily on fatty acid oxidation to maintain appropriate metabolic fuel levels. In addition, failure of blockade of lipoprivic LH inhibition by vagotomy suggests that lipoprivic information resulting in LH suppression is not transmitted to the brain via the vagus nerve.     

A plant peptide encoded by CLV3 identified by in situ MALDI-TOF MS analysis

The Arabidopsis CLAVATA3 (CLV3) gene encodes a stem cell-specific protein presumed to be a precursor of a secreted peptide hormone. Matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS) applied to in situ Arabidopsis tissues determined the structure of a modified 12-amino acid peptide (MCLV3), which was derived from a conserved motif in the CLV3 sequence. Synthetic MCLV3 induced shoot and root meristem consumption as cells differentiated into other organs, displaying the typical phenotype of transgenic plants overexpressing CLV3. These results suggest that the functional peptide of CLV3 is MCLV3.     

Profiling of hepatic gene expression of mice fed with edible japanese mushrooms by DNA microarray analysis: comparison among Pleurotus ostreatus, Grifola frondosa, and Hypsizigus marmoreus

To compare and estimate the effects of dietary intake of three kinds of mushrooms (Pleurotus ostreatus, Grifola frondosa, and Hypsizigus marmoreus), mice were fed a diet containing 10-14% of each mushroom for 4 weeks. Triacylglycerol in the liver and plasma decreased and plasma cholesterol increased in the P. ostreatus-fed group compared with those in the control group. Cholesterol in the liver was lower in the G. frondosa-fed group than in the control group, but no changes were found in the H. marmoreus-fed group. DNA microarray analysis of the liver revealed differences of gene expression patterns among mushrooms. Ctp1a and Fabp families were upregulated in the P. ostreatus-fed group, which were considered to promote lipid transport and β-oxidation. In the G. frondosa-fed group, not only the gene involved in signal transduction of innate immunity via TLR3 and interferon but also virus resistance genes, such as Mx1, Rsad2, and Oas1, were upregulated.     

Development of an efficient bioreactor system for delivering foreign proteins secreted from liver into eggs with a vitellogenin signal in medaka Oryzias latipes

In this study, we developed a novel bioreactor system to deliver and accumulate foreign proteins in eggs using medaka fish Oryzias latipes with the aid of a partial sequence of vitellogenin (Vtg). In teleost fish, Vtg, the hepatically generated precursor of egg yolk proteins, is secreted into the bloodstream and then taken up into eggs. We predicted in silico a probable region (Vtg signal) of Vtg that mediates transportation of proteins from the liver into eggs. Then, we established two transgenic lines expressing the fused proteins including the Vtg signal and each reporter gene, enhanced green fluorescent protein (EGFP) or firefly luciferase (LUC)-fused EGFP, in the liver driven by a liver-specific choriogeninH (chgH) promoter. Each reporter signal was detected from the fertilized eggs spawned by the transgenic females, showing successful transportation of the proteins into the eggs with the Vtg signal. This is the first report demonstrating that the Vtg signal has capability to deliver exogenous proteins into eggs. Because Vtg is a highly conserved protein among most of oviparous organisms, our findings hold promise for establishing bioreactor systems viable in a wide range of organisms.