Identification of a novel gene (Apq1) from the indica rice cultivar ‘Habataki’ that improves the quality of grains produced under high temperature stress

The appearance of brown rice grown under high temperature conditions is an important characteristic for improvement in Japanese rice breeding programs. We performed a QTL analysis of the appearance quality of brown rice using chromosome segment substitution lines of the indica cultivar ‘Habataki’ in the ‘Koshihikari’ genetic background. A line carrying a ‘Habataki’ segment on chromosome 7 showed a high percentage of perfect grains produced under high temperature conditions during the ripening period. To verify the role of this segment, and to narrow down the region containing the useful allele, substitution mapping was performed using multiple paired lines. As a result, the chromosomal location of a gene that we named Appearance quality of brown rice 1 (Apq1) was delimited to a 48-kb region. In addition, we developed an Apq1-near isogenic line (NIL) to evaluate the effect of Apq1 on various agronomic traits. Under high temperature conditions during the ripening period, the Apq1-NIL produced significantly higher percentages of perfect grains than ‘Koshihikari’. Other agronomic traits, including yield and palatability, were similar between the Apq1-NIL and ‘Koshihikari’. Therefore, the ‘Habataki’ allele of Apq1 will be useful in breeding programs aimed at improving the quality of grains ripened under high temperature conditions.     

Comparison of prevalence of Felis catus papillomavirus type 2 in squamous cell carcinomas in cats between Taiwan and Japan

Felis catus papillomavirus (FcaPV), especially type 2 (FcaPV2) is considered as one of the causative agents in squamous cell carcinoma (SCC) in cats. However, our previous study detected FcaPV3 and FcaPV4, but not FcaPV2 in feline SCCs collected in Japan, suggesting that the prevalence of FcaPV2 in SCC may vary depending on geographic locations. To evaluate this hypothesis, two conventional PCR reactions targeting E1 and E7 genes were performed to detect FcaPV2 in feline SCC samples collected in Taiwan and Japan. While 46.9% (23/49) of feline SCC cases from Taiwan were PCR positive for FcaPV2, only 8.6% (3/35) cases from Japan were positive. Our result suggests that the prevalence of FcaPV2 in feline SCCs may depend on the region.     

Histological analysis of implanted embryos in large Japanese field mouse (Apodemus speciosus) and estimation of developmental stage

The large Japanese field mouse (Apodemus speciosus) is a small rodent species endemic to Japan. The genetic characteristics of A. speciosus include different chromosome numbers within the same species. Furthermore, A. speciosus has been used in radiation and genetic research. In the present study, a pregnant A. speciosus was obtained, and histochemical analysis of the implanted embryos was performed and compared with the developmental stages of the mouse (Mus musculus). Although there were some differences, the structures of the implanted embryos, including the primitive streak and placenta of A. speciosus were similar to those of mouse. Our study will be important for the construction of a developmental atlas of A. speciosus.     

Seasonal variations in the cooling effect of urban green areas on surrounding urban areas

We measured air temperature in an urban green area that includes forest and grassland and in the surrounding urban area for a full year in Nagoya, central Japan, to elucidate seasonal variations of the difference in air temperature between urban and green areas. We determined the range of the “cool-island” effect as well as the relationship between vegetation cover and air temperature throughout the year. The temperature difference between urban and green areas was large in summer and small in winter. The maximum air temperature difference was 1.9 °C in July 2007, and the minimum was ?0.3 °C in March 2004. The difference was larger during the day than during the night in summer, whereas in winter the opposite relationship was true. However, winter diurnal variation was not particularly noticeable, a behaviour thought to be related to reduced shading by deciduous trees in the green area. During the night, the cooling effect of the green area reached 200–300  m into the urban area. During the day, the cooling effect between August and October 2006 exceeded 300 m and varied widely, although there was no correlation beyond 500 m. The correlation between air temperature and forest-cover ratio within a radius of 200 m from each measurement site was significant from 16:00 to 19:00. There was also a correlation during the night; this correlation was weakest in the early morning. The effect of the forest-cover ratio on air temperature was most pronounced in August 2006 and June 2007.     

Relationship of Cell Proliferating Marker Expressions with PGE(2) Receptors in Regenerating Rat Renal Tubules after Cisplatin Injection

Cisplatin, an anticancer drug, is well known to have nephrotoxicity as an adverse effect. We investigated the expressions of cell cycle markers and prostaglandin E(2) (PGE(2)) receptors (EP) in the affected renal tubules in rats injected with a single dose (6 mg/kg body weight) of cisplatin. On days 1-3 after dosing, the affected renal epithelial cells were almost desquamated, showing necrosis. On day 5 onwards, the renal tubules were rimmed by flattened or cuboidal epithelial cells with basophilic cytoplasm; BrdU-immunopositive cells began to significantly increase, indicating regeneration. Simultaneously, TUNEL-positive apoptotic cells were also seen. On days 1-5, cyclin D1-immunopositive cells were decreased with an increased expression in p21 mRNA, indicating G(1) arrest in the cell cycle. The affected renal epithelial cells began to react to EP4 receptor, but not to EP2 receptor. Some EP4 receptor-reacting epithelial cells gave a positive reaction to BrdU or cyclin D1. Collectively, the affected renal tubules underwent various alterations such as necrosis, apoptosis, regeneration and G(1) arrest; the aspects might be influenced by endogenous PGE(2) through EP4 receptor.     

Demographic Analysis of Breeding Structure in Japanese Thoroughbred Population

To investigate the breeding structure in the Japanese Thoroughbred population, we applied a demographic analysis to the populations of foals produced from 1978 to 2005. The migration rate estimated from the proportion of foals produced by imported breeding horses was around 40% over the investigated period. After early 1990s, the migration rate through stallions imported from USA sharply increased. The average generation interval was within range of 10.5–11.5 years. The longer generation interval of Thoroughbred was considered to be a reflection of the fact that Thoroughbred horses begin breeding only after completing their performance in races. After the peak of 729 in 1993, the number of sires of foals progressively declined to 358 in 2005. Although the coefficient of variation of the progeny number of sires was within range of 1.0–1.2 until early 1990s, it gradually increased and reached the value of 1.6–1.7 in recent years. The effective number of sires consistently decreased after the peak of 302.6 in 1992, and reached 120–130 in recent years, which is 25–30% of the actual number of sires. In parallel, the demographic estimate of the effective population size declined after early 1990s. The main cause of the observed change in the breeding structure was inferred to be the intensive use of a limited number of stallions for breeding.     

Promotion of initial swim bladder inflation and effect of initial inflation failure on skeletal malformation in cultured seven‐band grouper Hyporthodus septemfasciatus (Thunberg)

The effects of the removal of the oily surface film on initial swim bladder inflation and survival in cultured seven‐band grouper Hyporthodus septemfasciatus were investigated during the larval stage. Additionally, the relationship between swim bladder inflation failure and malformations in later stages was examined. To explore promotion conditions for inflation, duplicate experiments were conducted under three different water surface conditions: removal of the oily surface film (ROF group), covering the water surface with an oil film (COF group), and sealing the water surface with liquid paraffin (SLP group). Larval swim bladder inflation was first observed 14 days after hatching (DAH) in the ROF group; thereafter, swim bladder inflation rates increased to 11.1% and 38.7% until the end of the experiments. This indicates that initial swim bladder inflation occurs at the pre‐flexion stage in larval development. Conversely, bladder inflation was rarely observed in the COF or SLP groups, indicating the promotional effect of surface film removal on larval swim bladder inflation and suggesting that gulping atmospheric air is necessary for initial inflation. Although larval water surface death occurred frequently in the ROF group, no significant difference existed in any group between the survival rates at 10 DAH and at the end of the experiment. The incidence rate of spinal curvature and deformation of the centra was significantly higher in individuals without initial swim bladder inflation, and these malformations mainly occurred in the caudal vertebra. Therefore, the removal of the oily surface film promotes initial swim bladder inflation and reduces larval malformations.     

Spectrophotometric assay of a wood preservative, didecyldimethylammonium chloride (DDAC), in aqueous solution

A spectrophotometric assay based on the color reaction between didecyldimethylammonium chloride (DDAC) and 4-[4-(dipropylamino)phenylazo]-benzenesulfonic acid (propyl orange) was used for the determination of DDAC as a wood preservative. The assay was carried out using a propyl orange solution at pH 2.9. The visible absorbance spectrum of propyl orange showed an absorbance maximum at 510 nm, which decreased continuously with increasing DDAC concentration from 0 to 20 ppm. A linear correlation was observed at a DDAC concentration lower than 8 ppm. To apply this assay method to determine DDAC retention in treated wood, the influence of wood extractives on the assay was investigated. Wood extractives from sapwood and heartwood of Japanese cedar, Hinoki cypress, Japanese larch, and Western hemlock showed no influence on DDAC determination except in the case of heartwood from Japanese cedar and Hinoki cypress, which gave apparent DDAC concentrations higher than the actual values. However, it was also found that absorbance measurement at 477 nm solved this overestimation and gave precise values. It was concluded that this assay is a viable alternative to the current methods for DDAC determination.     

First report of plum pox virus infecting Japanese apricot (<Emphasis Type="Italic">Prunus mume</Emphasis> Sieb. et Zucc.) in Japan

For the first time, plum pox virus (PPV) has been detected in commercial Japanese apricot (Prunus mume) trees in Tokyo, Japan. These trees had ringspot or mottle on leaves, color breaking of petals and, occasionally, mild ringspots and malformation on fruits. The virus was identified based on the morphology of virus particles, serology, and RT-PCR. The amplified nucleotide fragment shared 100% identity with a partial coat protein gene of PPV-D isolates.