Isolation and sequence analysis of the promoter and an allelic sequence of the iron-sulfur protein subunit gene from the white-rot fungusPleurotus ostreatus

We have isolated a structural gene ofsdil, which encodes the iron-sulfur protein (Ip) subunit of succinate dehydrogenase (EC 1.3.99.1), from a white-rot basidiomycete,Pleurotus ostreatus. Here we report isolation of the promoter region ofsdil and an allelic sequence encoding the second-type cDNA fragment isolated in the former experiments. The nucleotide sequence analysis of the promoter region revealed the existence of putative CAAT and TATA boxes, which permits us to develop an expression system in this species. The Southern blot analysis and the restriction fragment length polymorphism assay using monokaryotic strains demonstrated that no family genes tosdil exist in the haploid genome ofP. ostreatus. Moreover, a genetic analysis to detect a linkage between thesdil genotypes and flutolanil resistance in the mutantP. ostreatus strains was also developed.     

Relationship between distribution patterns of shoots and light conditions on population floor in <Emphasis Type="Italic">Zostera marina</Emphasis> population

ABSTRACT:   This study was designed to identify a sustainable Zostera marina population based on the relationships between the distributional patterns of shoots and light conditions in the population. Population structures and light conditions on 22 April 2003 (season of reducing shoot density), 27 September 2003 (season of the annual minimum density and biomass) and 9 April 2004 (season of the annual maximum density and biomass) were examined. On 22 April 2003, the frequency distribution in shoot length was almost even. The spatial pattern is characterized by small clumps within 2–5 cm radius. On 27 September 2003, the lengths of all shoots were less than 40 cm, and the distributional patterns were similar to 22 April. On 9 April 2004, the spatial pattern is characterized by larger clumps within 25 cm radius. The reproductive shoots had a regular distribution. The relative light intensities on the population floor of the sea surface on 27 September and 9 April were 53.3 and 10.2%, respectively. The light intensity on 9 April 2004 was not sufficient for growth. The results suggest that the competition for harvesting solar radiation is caused by the shoot length and the spatial pattern among shoots in the population.     

Effects of irradiance of various wavelengths from light-emitting diodes on the growth of the harmful dinoflagellate <Emphasis Type="Italic">Heterocapsa circularisquama</Emphasis> and the diatom <Emphasis Type="Italic">Skeletonema costatum</Emphasis>

ABSTRACT:   We investigated the effects of specific light wavelengths from light-emitting diodes (LEDs) on the growth of the dinoflagellate Heterocapsa circularisquama , which kills bivalves, and the diatom Skeletonema costatum , which is an important food source for bivalves. Growth of H. circularisquama was obviously inhibited at 590 nm and a photon flux density less than 75 μmol quanta/m²/s. However, growth of S. costatum was not suppressed by irradiance from any LEDs tested from near-ultraviolet to near-infrared wavelengths at 75 μmol quanta/m²/s. The growth rate of H. circularisquama in an experimental treatment group with irradiance provided by both cool-white fluorescent lamps (12:12 h L : D cycle) and a 590-nm LED (continuous irradiance) was 0.43/day. In the control group with irradiance provided only by cool-white fluorescent lamps (12:12 h L : D cycle), the growth rate was 0.63/day, indicating that growth of H. circularisquama was suppressed by 590 nm (less than 75 μmol quanta/m²/s) irradiance from the LED and the continuous irradiance. The use of 590-nm LEDs in bivalve culture at irradiance levels less than 75 μmol quanta/m²/s might encourage the growth of the useful diatom S. costatum without stimulating growth of the harmful dinoflagellate H. circularisquama .     

Changes in the expression of pituitary gonadotropin subunits during reproductive cycle of multiple spawning female chub mackerel Scomber japonicus

The endocrine regulation of reproduction in a multiple spawning fish with an asynchronous-type ovary remains largely unknown. The objectives of this study were to monitor changes in the mRNA expression of three gonadotropin (GtH) subunits (GPα, FSHβ, and LHβ) during the reproductive cycle of the female chub mackerel Scomber japonicus. Cloning and subsequent sequence analysis revealed that the cDNAs of chub mackerel GPα, FSHβ, and LHβ were 658, 535, and 599 nucleotides in length and encoded 117, 115, and 147 amino acids, respectively. We applied a quantitative real-time PCR assay to quantify the mRNA expression levels of these GtH subunits. During the seasonal reproductive cycle, FSHβ mRNA levels remained high during the vitellogenic stages, while GPα and LHβ mRNA levels peaked at the end of vitellogenesis. The expression of all three GtH subunits decreased during the post-spawning period. These results suggest that follicle-stimulating hormone (FSH) is involved in vitellogenesis, while luteinizing hormone (LH) functions during final oocyte maturation (FOM). Both GPα and FSHβ mRNA levels remained high during the FOM stages of the spawning cycle and increased further just after spawning. Thus, FSH synthesis may be strongly activated just after spawning to accelerate vitellogenesis in preparation for the next spawning. Alternatively, LHβ mRNA levels declined during hydration and then increased after ovulation. This study demonstrates that chub mackerel are a good model for investigating GtH functions in multiple spawning fish.     

Fundamental study on the flow speed distribution around small traps

ABSTRACT:   This study measured the flow speed distribution using actual small traps to investigate the effects of their materials and shapes by analyzing the characteristics of the water flow patterns around them. Five types of trap (netted semi-cylinder shaped, wire semi-cylinder shaped, heart shaped, box shaped, and a cylinder shaped traps) constructed from different materials were used in the experiment. The flow speed distribution around each trap was measured in a flume tank. Flow speeds in the flume tank were 0.1, 0.2, 0.3, and 0.4 m/s. The webbing of the traps was different in shape and had various diameters of twine. The diameters of twine ranged from 0.55 to 1.00 mm. The relationship between the solidity ratio of the twine and flow distribution of the traps was also analyzed. For the netted semi-cylinder shaped and cylinder shaped traps, the area of reduced flow speed extended along the downstream area and its width slightly increased with distance from the trap's entrance. The heart shaped trap is shown to have the largest solidity ratio and this resulted in a high reduction of the flow speed downstream from the trap.     

Infectivity of porcine circovirus 1 and circovirus 2 in primary porcine hepatocyte and kidney cell cultures

Infectivity of porcine circovirus (PCV) 1 and PCV2 was examined in primary porcine hepatocyte culture by comparing that of PCV in primary kidney cell culture. The virus titer of PCV2-infected hepatocyte cultures was higher than that of the PCV1-infected hepatocyte cultures and the PCV-infected kidney cell cultures. The number of virus-positive cells was most abundant in PCV2-infected hepatocyte cultures as determined by immunohistochemistry and/or in situ hybridization. The results of our data suggest that PCV2 preferably infects cultured hepatocytes as observed in the liver of pigs with postweaning multisystemic wasting syndrome.     

Measurement for canine IgE using canine recombinant high affinity IgE receptor α chain (FcεRIα)

To detect allergen-specific IgE in dogs with allergic diseases, we developed a recombinant canine high affinity IgE receptor α chain (FcεRIα)-based IgE detection system. Using the recombinant protein of canine FcεRIα expressed by an Escherichia coli expression system, we could detect house dust mite (Dermatophagoides farinae) allergen-specific IgE in sera from dogs naturally and experimentally sensitized to this allergen with ELISA and western blotting. The IgE binding activity of recombinant canine FcεRIα on ELISA was impaired by heat treatment of these sera. The specificity of this recombinant canine FcεRIα-based IgE detection system was confirmed by inhibition assays with canine IgE. The recombinant canine FcεRIα-based IgE detection system established in this study offers an alternative tool to measure allergen-specific IgE in dogs.     

Rediscovery of a diploid cytotype of Dasypyrum breviaristatum in Morocco

The chromosome numbers of a total of 273 Dasypyrumbreviaristatum plants sampled from 20 Moroccan and one Greek naturalpopulations were examined. 270 plants from all of the populations weretetraploids. Among them, 223 were eu-tetraploids with 28 chromosomes and 47 wereaneuploids with 25, 27 and 29 chromosomes. Besides, three plants were found tobe diploids among 16 plants from a population in the Moyen Atlas Mountains ofMorocco. This is the second report of a diploid cytotype ofD. breviaristatum since the firstcommunication in 1957. Morphologically, the diploids were similar to but smallerthan the tetraploids in plant height, spike length, spikelet number and leafepidermis cell size. However, it was not possible to distinguish between the twocytotypes based on those morphological characteristics alone. A distinctdifference was found between the two cytotypes only in the number of trichomeson the leaf surfaces. The karyotype of the diploid cytotype consisted of a pairof SAT-chromosomes, five pairs of metacentric and a pair of submetacentricchromosomes. Based on the similarity in karyotype and in plant morphologybetween the two cytotypes of D.breviaristatum, we suggest that the diploid cytotype is themost probable candidate for the ancestral form of the tetraploid cytotype.     

Lignans ofLinum flavum var.compactum

A new dibenzylbutyrolactone lignan 7.6-dihydroxybursehernin, together with six known lignans (pinoresinol, lariciresinol, secoisolariciresinol,-peltatin,-peltatin, 5-methoxypodophyllotoxin) were isolated from the methanol extracts ofLinum flavum var.compactum. The enantiomeric analysis of pinoresinol and lariciresinol isolated from the species, which are upstream lignans in the lignan biosynthetic pathway, indicated that they are not optically pure, which is in accordance with our recent findings on lignans occurring in other plant species.Parts of this report were presented at the 42nd Lignin Symposium, Sapporo, October 1997; and the 43rd Lignin Symposium, Fuchu, October 1998