Correlation of changes in seasonal distribution and catch of red sea bream Pagrus major with winter temperature in the eastern Seto Inland Sea,Japan (1972–2010)

Red sea bream Pagrus major is a commercially important fish in Japan. In eastern Seto Inland Sea (SIS), the catch has increased from 297 tons in 1972 to 2,039 tons in 2010. We examined the relationship, 1972–2010, between increase in catch and winter temperature, based on the catch in February and March and the lowest water temperature at 10 m depth. In 1972–1986, the lowest water temperatures in the inner SIS areas (Osaka Bay, Harima‐nada, and Bisan‐seto) were <8°C, which is physiologically unfavorable for red sea bream. However, in 1987–2010 temperatures were generally ≥8°C. In the inner areas, the catch during winter had been minimal until the early 1980s, presumably because most red sea breams moved to the Kuroshio‐influenced (warmer) Kii Channel area. However, the winter catch in the inner areas of SIS increased from the late 1980s with warm winters. In addition, the catch between April and June, the spawning season, increased in the inner areas from the 1990s, and the catch rate of the inner areas was more than twice higher in the 2000s than in the 1980s. The results suggest that expansion of the distribution area during winter due to warm winter and increase in egg production in the inner areas greatly contributes to the increasing in catch in the eastern SIS.     

Ontogenetic habitat and dietary shifts in Japanese turban snail <Emphasis Type="Italic">Turbo cornutus</Emphasis> at Nagai,Sagami Bay,Japan

A field survey and a laboratory experiment were conducted to examine ontogenetic shifts in habitat and diet of the turban snail Turbo cornutus. The main habitat of turban snail juveniles smaller than 10 mm shell height (SH) was turfs of articulated coralline algae, and that of adults larger than 50 mm SH was kelp beds of Ecklonia bicyclis and Ecklonia cava. However, the ontogenetic habitat shift during the juvenile stage of 20–50 mm SH was unclear. From the results of a long-term feeding experiment and stable isotope analysis, the gelidiacean alga Gelidium elegans was assumed to be more important as a food source for juvenile turban snail than E. cava in the field. However, the frequency of individuals inhabiting gelidiacean algal turfs was low in both juvenile and adult stages. Thus, the ontogenetic shifts in habitat and diet did not coincide and other factors, i.e., daytime refuge, are important. As the growth rate was higher in the juveniles fed on the two algal species than those fed on single algal species, co-occurrence of various algal habitats in rocky shore ecosystems as a coastal ecosystem complex may enhance growth of turban snail juveniles feeding on a combination of different algal species.     

First report of ‘<Emphasis Type="Italic">Candidatus</Emphasis> Phytoplasma malaysianum’ associated with <Emphasis Type="Italic">Elaeocarpus</Emphasis> yellows of <Emphasis Type="Italic">Elaeocarpus zollingeri</Emphasis>

“Elaeocarpus yellows” (ELY) is a widely reported phytoplasma disease of Elaeocarpus zollingeri trees in Japan. The phytoplasma associated with ELY (ELY phytoplasma) had not been identified at the species level because its 16S rRNA sequence had yet to be reported. Here, we report the results of a sequence analysis based on 16S rRNA and secA gene sequences, which showed that the ELY phytoplasma is related to ‘Candidatus Phytoplasma malaysianum’. To our knowledge, this is the first report showing the occurrence of ‘Ca. P. malaysianum’ outside Malaysia and the infection of E. zollingeri by the phytoplasma.     

A decision-making model for rice paddy cropping in an urbanizing area of the Lao PDR

In Southeast Asia, economic and population growth are expected in the near future. Rapid change is anticipated especially in the Lao PDR. Concern has been expressed that population growth will lead to an increased demand for food and economic growth to changes in the use of land. For food production to keep pace with the growth of population, it is very important to understand decision-making in rice paddy cultivation in urbanizing areas; for this reason, this study with the SEM model was conducted. The original data were collected by a questionnaire survey in some Lao villages; the survey included questions on various conditions, such as the availability of water in the dry season (irrigation), the access to a city, and job opportunities other than farming. The findings of the study demonstrate that the planting of a second rice crop was related to such factors as the productivity of rain-fed rice and cash crops and, most importantly, job opportunities other than farming.     

Cytosolic glutamine synthetase is present in the phloem sap of rice (Oryza sativa L.)

The presence of glutamine synthetase (GS) in the rice sieve tube was examined. Proteins in the rice phloem sap from leaf sheaths were separated by sodium dodecylsulfate–polyacrylamide gel electrophoresis, transferred to polyvinylidine difluoride membranes and immunoblotted with anti-GS1 antibody. A cross-reacting band, thought to be GS1, was detected in the phloem sap. Moreover, the phloem sap contained a significant amount of GS transferase activity. Previous studies have shown that the concentrations of substrates and cofactors in the rice phloem sap are sufficient for cytosolic GS reaction. These data suggest that physiologically active GS1 is present in rice phloem sap, which might convert glutamate to glutamine in vivo .     

Distribution and ecology of bigeye thresher Alopias superciliosus in the Pacific Ocean

We analyzed records of shark capture by tuna longline vessels during the period 1992–2006 to document the distribution and ecology of bigeye thresher in the Pacific Ocean. Catch per unit effort (CPUE) was highest in the area of 10–15°N in the north and 5–10°S in the south. Juveniles <150 cm were also distributed in this area. Seasonal changes in the distribution of abundance are thought to represent seasonal migrations in latitude. We observed an increase in the ratio of large individuals at high latitude, likely a result of their increased thermal capacity allowing them to migrate further. Males were captured more often than females, suggesting that there is segregation by sex. Pregnant females were observed from 0°N to 36°N in the north Pacific. Neonates were observed between 10–15°N/150–180°W, overlapping with the area in which large numbers of juveniles were captured. Thus, we hypothesize that this area represents the parturition and nursery grounds for bigeye thresher in this region.     

Involvement of NbNOA1 in NO production and defense responses in INF1-treated Nicotiana benthamiana

During defense responses, plant cells produce nitric oxide (NO), which may control many physiological processes. In a previous study, we reported that nitrate reductase (NR) is responsible in part for INF1 elicitor-induced NO production in Nicotiana benthamiana, but the possibility remains that other NO-generating system(s) contribute to NO production. In mammalian cells, NO production is catalyzed by NO synthase (NOS). However, NOS-like enzyme(s) have never been identified in plants, and only the gene for Arabidopsis thaliana nitric oxide-associated 1 (AtNOA1) has been identified as a putative regulator of NOS activity in plants. In this study, we cloned NbNOA1, a homolog of AtNOA1, from N. benthamiana and investigated its involvement in NO production induced by INF1. The NbNOA1 gene was silenced by a virus-induced gene-silencing (VIGS) technique. NbNOA1-silenced plants had yellowish leaves. Silencing NbNOA1 partially decreased INF1-induced NO production, while overexpressing NbNOA1 did not affect NO production. Silencing NbNOA1 suppressed INF1-induced PR1a gene expression and increased susceptibility to Colletotrichum lagenarium. These results suggest that NbNOA1 is involved in INF1-mediated NO production and is required for defense responses. The nucleotide sequence data reported are available in the DDBJ/EMBL/GenBank databases under accession number AB303300.     

Influence of single-nucleotide polymorphisms in the gene encoding granule-bound starch synthase I on amylose content in Vietnamese rice cultivars

Amylose content is one of the most important factors influencing the physical and chemical properties of starch in rice. Analysis of 352 Vietnamese rice cultivars revealed a wide range of variation in apparent amylose content and the expression level of granule-bound starch synthase. On the basis of single-nucleotide polymorphisms (SNP) at the splicing donor site of the first intron and in the coding region of the granule-bound starch synthase I gene, Waxy gene, alleles can be classified into seven groups that reflect differences in apparent amylose content. The very low and low apparent amylose content levels were tightly associated with a G to T in the first intron whereas intermediate and high amylose was associated with a T genotype at SNP in exon 10. The correlation between the combination of T genotype at SNP in the first intron, C in exon 6, or C in exon 10 was predominant among low amylose rice varieties. Our analysis confirmed the existence of Wx^op allele in Vietnamese rice germplasm. The results of this study suggest that the low amylose properties of Vietnamese local rice germplasm are attributable to spontaneous mutations at exons, and not at the splicing donor site.