Effect of the temperature-humidity index on body temperature and conception rate of lactating dairy cows in southwestern Japan

In the present study, we investigated the relationship between the temperature-humidity index (THI) and the conception rate of lactating dairy cows in southwestern Japan, one of the hottest areas of the country. We also investigated the relationship between measurement of the vaginal temperature of lactating dairy cows as their core body temperature at one-hour intervals for 25 consecutive days in hot (August-September, n=6) and cool (January-February, n=5) periods and their THI. Furthermore, we discussed the above relationship using these vaginal temperatures, the conception rates and the THI. As a result, when the conception rates from day 2 to 0 before AI were classified into day 2, 1 and 0 groups by the six maximum THI values in each group (mTHI; <61, 61-65, 66-70, 71-75, 76-80, >80), only the conception rate for the mTHI over 80 at 1 day before AI group was significantly lower (P<0.05) than the other groups. The conception rate for days 15 to 17, but not days 19 to 22 and 30 to 35, after AI in the cows that experienced average mTHI over 80 (amTHI>80) was significantly lower (P<0.05) than that of the cows that did not experience amTHI>80. There was a significant positive correlation (P<0.01) between the mTHI and the mean daily vaginal temperature, but not during the cool period. When the mTHI reached 69, the vaginal temperature started to increase. As for the relationship between the conception rates and vaginal temperatures for all mTHI classes, in the mTHI>80 at 1 day before AI group, the vaginal temperature increased by 0.6 C from 38.7 C, resulting in a reduction of 11.6% in the conception rate from 40.5%. In conclusion, these results suggest that one of the causes of the fall in conception rate of lactating dairy cows during the summer season in southwestern Japan may be an increase in their core body temperature with a higher mTHI than the critical mTHI of 69 at 1 day before AI.     

Induction of a Th-1-biased IgG subclass response against equine herpesvirus type 1 in horses previously infected with type 4 virus

An immunoglobulin G (IgG) subclass response against equine herpesvirus type 1 (EHV-1) infection was investigated in horses that were na?ve to EHV-1/4 and those that had previously been exposed to EHV-4. The IgG subclass response was determined by an ELISA using EHV-1-specific recombinant gG protein as an antigen. In most horses na?ve to EHV-1/4, IgGa, IgGb, and IgG(T) were induced after experimental infection with EHV-1. In contrast, a subclass response dominated by IgGa and IgGb, with no apparent increase in IgG(T), was observed after EHV-1 infection in horses previously infected with EHV-4. Horses naturally infected with EHV-1 in the field showed similar responses. These results indicated that pre-infection with EHV-4 induced a Th-1-biased IgG subclass response against subsequent EHV-1 infection.     

Hydrophobic silicone elastomer chamber for recording trajectories of motile porcine sperms without adsorption

Motile porcine sperms adhere to hydrophilic materials such as glass and plastics. The adsorption of sperms to a hydrophobic poly(dimethylsiloxane) (PDMS) membrane is less compared with that to glass. We investigated the linear velocity (LV) and amplitude of lateral head displacement (ALHD) of motile porcine sperm on glass and PDMS preparations using computer-assisted sperm analysis (CASA). Significant decreases were observed in the 15-min LV (P<0.05) and ALHD (P<0.05) in motile porcine sperm on glass preparations compared with those on PDMS preparations. These differences were due to adsorption of the head and/or neck to hydrophilic substrates. Because of the elasticity of PDMS, we propose that a PDMS membrane should be used for CASA. To investigate the dynamics of motile porcine sperms with microfluidics, we do not recommend plasma treatment to bond PDMS and glass in the microchannel preparation; instead, we suggest that a PDMS molding process without plasma treatment be used for preparation of microfluidic channels.     

Development and application of a chemically defined medium for the in vitro production of porcine embryos

Recent advances in systems for in vitro production (IVP) of porcine embryos, including in vitro oocyte maturation, fertilization and embryo culture, have enabled us to generate viable embryos that can develop to full term after transfer into recipients. This technology is being applied now to developments in gamete/embryo biology and agriculture, as well as in producing cloned and genetically modified pigs. Chemically defined media for IVP of embryos are useful for a precise analysis of the physical action of substances on gametogenesis and early embryogenesis, because they eliminate undefined factors present in biological materials, such as serum or serum albumin. Use of a chemically defined medium also improves the reliability of media formulations, yields a higher reproducibility of results and ensures biosafety of culture media by eliminating protein preparations, which may be contaminated with pathogens. Therefore, it has certain advantages for research and for commercial purposes. We have recently developed a defined IVP system for porcine embryos using a single basic medium based on the composition of porcine oviductal fluid. This paper discusses the developmental ability and normality of porcine IVP embryos, and limitations and advancements in this system.     

Staphylococcus pseudintermedius exfoliative toxin EXI selectively digests canine desmoglein 1 and causes subcorneal clefts in canine epidermis

Staphylococcal exfoliative toxins are known to digest desmoglein (Dsg) 1, a desmosomal cell–cell adhesion molecule, thus causing intraepidermal splitting in human bullous impetigo, staphylococcal scalded skin syndrome and swine exudative epidermitis. Recently, a novel exfoliative toxin gene (exi), whose sequence shares significant homology with previously identified exfoliative toxins, was isolated from Staphylococcus pseudintermedius. Little is known about the pathogenic involvement of this toxin in canine pustular diseases such as impetigo. The aim of this study was to determine whether EXI, the product of the exi gene, digests canine Dsg1 and causes intraepidermal splitting in canine skin. An exi gene was isolated from chromosomal DNA of an S. pseudintermedius strain obtained from a pustule of a dog with impetigo, and was used to produce a recombinant EXI by Escherichia coli expression. When purified recombinant EXI was injected intradermally into normal dogs, it caused the development of vesicles or erosions with superficial epidermal splitting. In addition, the EXI abolished immunofluorescence for Dsg1, but not for Dsg3, at the injection sites. Moreover, the EXI directly degraded baculovirus‐secreted recombinant extracellular domains of canine Dsg1, but not that of canine Dsg3, in vitro. The EXI also degraded mouse Dsg1α and swine Dsg1, but not human Dsg1, mouse Dsg1β and Dsg1γ. Conversely, recombinant SIET, previously designated as S. intermedius exfoliative toxin, did not cause intraepidermal splitting or degradation of any Dsgs. These findings indicate that EXI has a proteolytic activity that digests canine Dsg1, and this characteristic might be involved in the pathogenesis of intraepidermal splitting in canine impetigo.     

Simple method for isolation of glyceraldehyde 3‐phosphate dehydrogenase and the improvement of myofibril gel properties

Porcine glycoliytic enzyme, glyceraldehyde 3‐phosphate dehydrogenase (G3PD) was prepared effectively by a combination of ethylene diamine tetra‐acetate (EDTA) pretreatment and affinity purification. After salting out of porcine sarcoplasmic proteins (SP) with ammonium sulfate at 75% saturation, the obtained supernatant (SP‐f3) was treated with EDTA, leaving G3PD in the supernatant (G3PD‐E) and most other SPs in the precipitate. At that time, the separation of G3PD‐E required more than 20 mmol/L EDTA. G3PD‐E was then subjected to affinity purification by batchwise method using blue‐sepharose CL‐6B, and purified G3PD (G3PD‐AP) was obtained using 2 mol/L potassium chloride (KCl) as an eluent. Texture analysis showed that the hardness, adhesiveness and gumminess of the myofibril gel at 0.2‐mol/L NaCl increased with the addition of G3PD‐AP. Scanning electron microscopy revealed that the G3PD‐AP reinforced the gel network of the myofibril. However, scanning electron micrograph analysis showed that the network‐structure of the gel by the addition of G3PD‐AP developed in a different manner from that by adding 0.6 mol/L NaCl. These results showed that glycolytic enzyme, G3PD, contributes to the improvement of the rheological properties of meat products.     

Histochemical detection of Blueberry latent virus in highbush blueberry plant

Blueberry latent virus (BBLV) was detected in 27 of 95 asymptomatic highbush blueberry trees in a blueberry field in Japan. In situ hybridization showed that the viral RNAs were detected in the palisade mesophyll, spongy mesophyll and vascular bundle of leaves. In western blot analysis, an antibody to the viral protein encoded by open reading frame 1 (ORF1) reacted with a 48-kDa protein specific for blueberry trees in which BBLV was detected. Immunogold electron microscopy revealed that amorphous bodies in the cytoplasm of blueberry cells were labeled with antibodies to the ORF1 protein.     

Combined use of a synthetic trail pheromone and insecticidal bait provides effective control of an invasive ant

BACKGROUND: Except for sex pheromones, use of pheromones in pest management has been largely unexplored. A high concentration of trail pheromone disrupts ant trail following and foraging, and thus synthetic trail pheromone can be a novel control agent for pest ants. In this study, a year‐long treatment of small areas (100 m² plots of urban house gardens) with synthetic trail pheromone, insecticidal bait or both was conducted to develop a novel control method of the invasive Argentine ant Linepithema humile (Mayr). RESULTS: The ant population could be maintained lower than or similar to the initial level only by combined treatment with synthetic trail pheromone and insecticidal bait. Actually, the ant population was nearly always lowest in combination treatment plots. Throughout the study period, the ant population in plots treated with either one of synthetic trail pheromone or insecticidal bait remained similar to no‐treatment plots. CONCLUSIONS: Combination treatment may be a more effective and environmentally friendly method for controlling invasive ants than conventional methods. Extermination of ants by insecticidal bait and inhibition of re‐infestation by pheromone may be the mechanism of the combination effect. This is the first study to show a significant effect of synthetic trail pheromone on ant population. Copyright © 2011 Society of Chemical Industry