Age and growth of yellowstriped butterfish, <Emphasis Type="Italic">Labracoglossa argentiventris</Emphasis>, around Izu Oshima Island

ABSTRACT:   Age and growth of the yellowstriped butterfish, Labracoglossa argentiventris , around Izu Oshima Island were studied using a total of 1450 fish. Age was determined by counting the edge of the opaque zones as a ring mark on sectioned sagittal otoliths. Formation of the first ring was observed during spring or summer, corresponding to 1.5 years after hatching. Thereafter, one ring was formed each year in the same season as the previous year. The growth of the butterfish was rapid until 2 years of age. The maximum likelihood method was applied to the age and length data for estimating parameters in von Bertalanffy, Gompertz, and Logistic growth models. The selected model, based on the Akaike Information Criterion, was the von Bertalanffy growth model, which indicated differential asymptotic length and variance by sex.     

Flow cytometric analysis of bronchoalveolar lavage fluid immune dynamics in calves

Understanding the immune dynamics in the respiratory mucosa of calves is necessary for a good management of bovine respiratory disease. Immune dynamics in the respiratory mucosa in humans and experimental animals has been assessed by flow cytometric analysis of bronchoalveolar lavage fluid (BALF); however, few reports have addressed this subject in calves. The aim of this study was to establish a universal method to analyze bronchoalveolar lavage fluid (BALF) by flow cytometry and to obtain basic knowledge of bovine respiratory mucosal immune dynamics. We investigated the immune cell populations in BALF and evaluated the surface antigen expression of alveolar macrophages in calves using flow cytometer. To further analyze the surface antigen variation observed in alveolar macrophages in detail, stimulation assays were performed in vitro. BALF cells were separated into three distinct populations based on their light scatter plot, which were considered to be macrophages, lymphocytes, and neutrophils. In most individuals, most of the BALF immune cells were alveolar macrophages, but an increased proportion of lymphocytes and neutrophils was observed in some individuals. Analysis of each surface antigen expression in alveolar macrophages showed that CD21 and MHC class II expression changed in response to changes in the leukocyte population. Moreover, when alveolar macrophages were stimulated with interferon-γ in vitro, the expression of CD21 was drastically reduced and MHC class II was increased, suggesting that functional changes in alveolar macrophages themselves are involved in the immune dynamics.     

Urinary lipid production profile in canine patients with splenic mass

Polyunsaturated fatty acids (PUFAs), including arachidonic acid (AA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA), are metabolized to various lipid mediators. The profile of these lipid metabolites excreted into the urine reflects inflammatory state of the body and disease conditions. In this study, we quantified 156 types of lipids in urine samples of dogs with splenic mass, using liquid chromatography-tandem mass spectrometry. We found that metabolites of prostaglandin (PG) E₂, F_2α, and D₂, 8-iso-PGF_3α, lyso-platelet activating factor, and 14,15-leukotrien C₄ significantly increased in urine samples of dogs with splenic mass compared to that of healthy dogs. These observations may reflect general inflammatory responses and will help better understanding of the canine splenic mass.     

Identification of QTLs controlling harvest time and fruit skin color in Japanese pear (Pyrus pyrifolia Nakai)

Using an F₁ population from a cross between Japanese pear (Pyrus pyrifolia Nakai) cultivars ‘Akiakari’ and ‘Taihaku’, we performed quantitative trait locus (QTL) analysis of seven fruit traits (harvest time, fruit skin color, flesh firmness, fruit weight, acid content, total soluble solids content, and preharvest fruit drop). The constructed simple sequence repeat-based genetic linkage map of ‘Akiakari’ consisted of 208 loci and spanned 799 cM; that of ‘Taihaku’ consisted of 275 loci and spanned 1039 cM. Out of significant QTLs, two QTLs for harvest time, one for fruit skin color, and one for flesh firmness were stably detected in two successive years. The QTLs for harvest time were located at the bottom of linkage group (LG) Tai3 (nearest marker: BGA35) and at the top of LG Tai15 (nearest markers: PPACS2 and MEST050), in good accordance with results of genome-wide association study. The PPACS2 gene, a member of the ACC synthase gene family, may control harvest time, preharvest fruit drop, and fruit storage potential. One major QTL associated with fruit skin color was identified at the top of LG 8. QTLs identified in this study would be useful for marker-assisted selection in Japanese pear breeding programs.     

Effect of the number of tillages in fallow season and fertilizer type on greenhouse gas emission from a rice (Oryza sativa L.) paddy field in Ehime,southwestern Japan

Agricultural fields, including rice (Oryza sativa L.) paddy fields, constitute one of the major sources of atmospheric methane (CH₄) and nitrous oxide (N₂O). Organic matter application, such as straw and organic fertilizer, enhances CH₄ emission from paddy fields. In addition, rice straw management after harvest regulates CH₄ emissions in the growing season. The interaction of tillage times and organic fertilizer application on CH₄ and N₂O emissions is largely unknown. Therefore, we studied the effects of fallow-season tillage times and fertilizer types on CH₄ and N₂O emissions in paddy fields in Ehime, southwestern Japan. From November 2011 to October 2013, four treatments, two (autumn and spring) or one (spring) in the first year, or two (autumn and spring) or three (autumn, winter, and spring) in the second year times of tillage with chemical or organic fertilizer application, were established. Gas fluxes were measured by the closed-chamber method. Increasing the number of tillage times from one to two decreased succeeding CH₄ emission and the emission factor for CH₄ (EF_CH4) in the rice-growing season, suggesting that the substrate for CH₄ production was reduced by autumn and spring tillage in the fallow season. Higher EF_CH4 [1.8–2.0 kg carbon (C) ha^?1 d^?1] was observed when more straw was applied (6.9–7.2 Mg ha^?1) in the second year. Organic fertilizer application induced higher CH₄ emission just after the application as basal and supplemental fertilizers, especially at a lower straw application rate. This indicated that EF_CH4 in the organically managed fields should be determined individually. Organic fertilizer application with two tillage times induced N₂O efflux during the rice-growing season in the second year, but N₂O emissions were not affected by winter tillage. Although paddy fields can act as an N₂O sink because of reduced soil conditions when straw application was high, application of organic C and nitrogen as fertilizer can enhance N₂O production by the denitrification process during the growing season, especially in the ripening stage when soil anaerobic conditions became moderate. These results suggest that negative emission factors for N₂O (EF_N2O) can be applied, and EF_N2O of organic fertilizer should be considered during the estimation of N₂O emission in the paddy field.     

Genetic identification and morphology of naturally spawned eggs of the Japanese eel Anguilla japonica collected in the western North Pacific

Eggs of the Japanese eel Anguilla japonica collected in the western North Pacific were identified by onboard species-specific polymerase chain reaction (PCR) and DNA nucleotide sequencing after the cruise. Fish eggs of various species were collected by large plankton net tows at 12 stations along the southern part of the West Mariana Ridge on 19–25 May 2009. A total of 43 fish eggs were distinguished morphologically as possibly being of A. japonica. Thirty-one of those were analyzed by PCR, which included 15 eggs collected at 12°50–55′N, 141°15–20′E (in 5 tows) that showed positive results. The 16S ribosomal RNA (rRNA) gene sequences of eggs determined after the cruise indicated that 31 A. japonica eggs had been collected. The remaining eggs were of mesopelagic eel species (Serrivomeridae and Derichthyidae), or unidentified species. The morphological characteristics of the A. japonica eggs were consistent with those of artificially spawned eggs, except they had a slightly larger diameter. The egg diameter range did not overlap with those of mesopelagic eels of the Serrivomeridae, which often spawn in the same area as A. japonica. These results suggest that egg diameter and embryo shape can be used to morphologically identify naturally spawned A. japonica eggs.     

A single injection of periostin decreases cardiac voltage-gated Na+ channel in rat ventricles

Changes in electrophysiological properties, such as ion channel expression and activity, are closely related to arrhythmogenesis during heart failure (HF). However, a causative factor for the electrical remodeling in HF has not been determined. Periostin (POSTN), a matricellular protein, is increased in heart tissues of patients with HF. In the present study, we investigated whether a single injection of POSTN affects the electrophysiological properties in rat ventricles. After male Wistar rats were intravenously injected with recombinant rat POSTN (64 µg/kg, 24 hr), electrocardiogram (ECG) was recorded. Whole-cell patch clamp was performed to measure action potential (AP) and Na⁺ current (I_Na) in isolated ventricular myocytes. Protein expression of cardiac voltage-gated Na⁺ channel (Na_V1.5) in isolated ventricles was examined by Western blotting. In ECG, POSTN-injection significantly increased RS height. POSTN-injection significantly delayed time to peak in AP and decreased I_Na in the isolated ventricular myocytes. POSTN-injection decreased Na_V1.5 expression in the isolated ventricles. It was confirmed that POSTN (1 µg/ml, 24 hr) decreased I_Na and Na_V1.5 protein expression in neonatal rat ventricular myocytes. This study for the first time demonstrated that a single injection of POSTN in rats decreased I_Na by suppressing Na_V1.5 expression in the ventricular myocytes, which was accompanied by a prolongation of time to peak in AP and an increase of RS height in ECG.     

Development of an SSR marker set for efficient selection for resistance to black spot disease in pear breeding

Black spot disease, which is caused by Alternaria alternata (Fries) Keissler Japanese pear pathotype, is one of the most harmful diseases in Japanese pear cultivation. Because of the potential harm of fungicides to consumers and the environment, resistant cultivars are desired. In this study, to enable efficient marker-assisted selection in pear breeding, we conducted comprehensive inoculation tests and genotyping with 207 pear cultivars. We identified a marker set (Mdo.chr11.27 and Mdo.chr11.34) suitable for selection for black spot resistance. In most susceptible cultivars, Mdo.chr11.27 amplified a 220-bp band and Mdo.chr11.34 amplified a 259-bp band. The genotype of Mdo.chr11.34 corresponds perfectly to the estimated genotype of Japanese pears susceptible to black spot disease. Using linkage analysis, we identified the positions of the gene for susceptibility to black spot disease in Chinese pear. Mdo.chr11.27 and Mdo.chr11.34 were tightly linked to susceptibility in Chinese pear, and the susceptibility gene was mapped at the top of linkage group 11, similar to that in Japanese pear. This marker set and the accumulation of phenotypic data will enable efficient marker-assisted breeding for black spot resistance in pear breeding.