First report of leaf sheath rot of Welsh onion caused by nine taxa of <Emphasis Type="Italic">Rhizoctonia</Emphasis> spp. and characteristics of the pathogens

From 2007 to 2013, a disease of Welsh onion, causing leaf sheath rot and concomitant death of outer leaves was found in 20 fields in Hokkaido, Japan. We obtained 20 Rhizoctonia isolates from diseased tissues and identified them based on the number of nuclei, hyphal fusion reactions, and molecular techniques using specific PCR primers and sequence of the rDNA-ITS region. The 20 isolates consisted of 16 multinucleate and four binucleate isolates. Of the multinucleate isolates, five were found to be so far unknown and designated here as Rhizoctonia solani AG-4 hybrid subgroup between HG-I and HG-II. Others were identified as AG-1 IB (three isolates), AG-2-2 IIIB (two isolates), AG-4 HG-I (two isolates), AG-1 IC (one isolate), AG-2-1 (one isolate), AG-4 HG-II (one isolate) and AG-5 (one isolate). All four binucleate isolates were binucleate Rhizoctonia AG-U. Original symptoms were reproduced on all plants inoculated with these isolates. Thus, we revealed that as many as nine taxa of Rhizoctonia spp. were associated with the disease. This is the first report of leaf sheath rot of Welsh onion caused by Rhizoctonia spp.     

Changes in neurosteroid biosynthesis during sexual maturation of lacustrine sockeye salmon

It was demonstrated that pregnenolone (P5) and 17α-hydroxypregnenolone (17α-OH-P5) were identified as cholesterol metabolites in the brain and pituitary gland of lacustrine sockeye salmon (Oncorhynchus nerka) during sexual maturation. Moreover, 17α-OH-P5 was determined as the major cholesterol metabolite. The conversion of P5 to 17α-OH-P5 in the brain and pituitary gland showed a clear regional difference, and their productivity were dramatically changed during sexual maturation. From these data, it was suggested that steroid converting enzyme in the brain and pituitary gland of lacustrine sockeye salmon might be involved in brain region-dependent roles on sexual maturation.     

Structure and mechanism of the lactose permease of Escherichia coli

Membrane transport proteins that transduce free energy stored in electrochemical ion gradients into a concentration gradient are a major class of membrane proteins. We report the crystal structure at 3.5 angstroms of the Escherichia coli lactose permease, an intensively studied member of the major facilitator superfamily of transporters. The molecule is composed of N- and C-terminal domains, each with six transmembrane helices, symmetrically positioned within the permease. A large internal hydrophilic cavity open to the cytoplasmic side represents the inward-facing conformation of the transporter. The structure with a bound lactose homolog, beta-D-galactopyranosyl-1-thio-beta-D-galactopyranoside, reveals the sugar-binding site in the cavity, and residues that play major roles in substrate recognition and proton translocation are identified. We propose a possible mechanism for lactose/proton symport (co-transport) consistent with both the structure and a large body of experimental data.     

Effect of Carbohydrates on the Ability of Bull Sperm to Bind to Bovine Oviduct Epithelial Cells

In the present study, we investigated the effect of various carbohydrates on the ability of bovine spermatozoa to bind to the bovine oviduct epithelial cells (OECs). We also examined the fertilization competence and motility of spermatozoa that bind to OECs in the presence of carbohydrates. Frozen-thawed spermatozoa were incubated with OECs, with and without various carbohydrates. The sperms were then divided into two fractions: OEC-binding sperms (B-sperm) and non-OEC binding sperms (NB-sperm). The fertilization rate, ability to bind the zona pellucida, and membrane integrity of the spermatozoa as determined using a hypo-osmotic-swelling test (HOST) were lower in NB-sperm than in the unseparated spermatozoa (control). The motility of the B-sperm was maintained for a longer time than that of the control spermatozoa. The addition of N -acetyl- d -glucosamine (GlcNAc, 5 m m ) to the sperm-OEC mixture increased the number of B-sperm. D -mannose (5 m m ) and D -fucose (5 m m ) had no effect on the number of B-sperm. The motility of B-sperm, which bound to OECs in the presence of GlcNAc, however, was not maintained. When either OECs or the spermatozoa were treated with GlcNAc prior to sperm-OEC co-incubation, only sperm-side treatment enhanced sperm-OEC binding, but B-sperm motility was not maintained. The motility of spermatozoa incubated with GlcNAc was lower than that of controls. These results indicate that GlcNAc enhances sperm binding to OECs, probably via sperm surface modification, but does not promote increased sperm survival.     

Paternity determination of captive bottlenose dolphins (Tursiops truncatus) using microsatellite DNA analysis

We applied previously published PCR primer pairs to amplify alleles at three polymorphic microsatellite loci to determine the genetic relationship of 6 bottlenose dolphins (Tursiops truncatus) that were living together in a Japanese aquarium. The three microsatellite loci were sufficient to determine the haplotype relationships of the six dolphins, which represented three different generations. It was confirmed that this genotyping method is simple and economical for assessing, establishing and maintaining genetic diversity in captive populations and will become a very effective technique for ex situ conservation in aquariums and zoos.     

Impact of a 5-year winter cover crop rotational system on the molecular diversity of arbuscular mycorrhizal fungi colonizing roots of subsequent soybean

The impact of winter cover crops, specifically wheat (Triticum aestivum L.), red clover (Trifolium pratense L.), and rapeseed (Brassica napus L.) or winter fallow, on community composition of arbuscular mycorrhizal fungi (AMF) in subsequent soybean roots was investigated in a 5-year field trial on andosolic soils in Japan. Soybean roots were sampled at full-flowering and analyzed for AMF communities using a partial LSU rDNA region. Phylogenetic analysis detected 22 AMF phylotypes, including eight Glomus, three Gigaspora, two Scutellospora, three Acaulospora, two Rhizophagus, and one of Funneliformis, Diversispora, Paraglomus, and an unknown glomeromycete in the roots. The 5-year rotation of different winter cover crops or winter fallow did not impact the molecular diversity of AMF communities colonizing the roots of subsequent soybean. In all of the rotations, Glomus and Gigaspora phylotypes were common to soybean roots over the 5-year period. Redundancy analysis (RDA) demonstrated that AMF communities in the roots of subsequent soybean were not significantly different among winter cover crop rotations or fallow. However, AMF communities in soybean roots were clearly influenced by rotation year suggesting that climate or other environmental factors were more important than winter cover cropping system management.     

Characterization of new photosynthesis-inhibiting imidazolidine derivatives. 2. Interpretation of pre-emergence herbicidal performance from photosyghesis-inhibiting activity and soil adsorption coefficient

Ruling factors governing pre-emergence herbicidal activity were analysed for 16 photosynthesis-inhibiting 5-hydroxy-3-methyl-2–oxo-imidazolidine-1-carboxamide derivatives. Herbicidal performance was quantified by the reduction in area of experimental weed vegetation, measured by a computer-aided image analysis system. A system for fluorometric estimation of photosynthesis inhibitor concentration in aqueous solution greatly facilitated determination of the soil adsorption coefficients (K_d). Maximum herbicidal performance was found for N-sec-butyl-5-hydroxy-3-methyl-2-oxo-imidazolidine-1-carboxamide, a compound with the second lowest soil adsorptivity and average photosynthesis-inhibiting activity. A multiple regression analysis suggested that herbicidal performance of the soil-applied imidazolidine derivatives was determined by a balance between K_d and photosynthesis-inhibiting activity. In the present experimental system, however, the main influence was attributed to K_d.