A set of near-isogenic lines for blast resistance genes with an Indica-type rainfed lowland elite rice (Oryza sativa L.) genetic background

A set of near-isogenic lines for blast resistance genes was developed by using an Indica-type elite rice variety, IR49830-7-1-2-2, suitable for the rainfed lowland conditions in the tropics, as a genetic background. Initially, we revealed that IR49830-7-1-2-2 harbors five blast resistance genes - Pia, Pib, Pik-s, Pita, and Pi11(t) - by using a differential system involving 19 selected standard blast isolates from the Philippines. Based on this result, we developed nine near-isogenic lines (NILs) targeting eight resistance genes - Pik, Pi7(t), Pi3, Pi5, Pita-2, Piz-5, Pish, and Pi9 - by recurrent backcrossing. The introgression of each resistance gene in the NILs was confirmed by reaction patterns to the blast isolates, allelism tests, and DNA marker analysis. In addition, a genome-wide DNA marker survey revealed that most of the chromosome regions in each NIL were of the IR49830-7-1-2-2 type. The agricultural characteristics of most of the developed NILs were almost the same as those of IR49830-7-1-2-2. Moreover, with one exception, they showed submergence tolerance similar to IR49830-7-1-2-2. The developed NILs could be used as a multiline variety suitable for the rainfed lowland in the tropics.     

Genetic analyses of agronomic traits in Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.)

The consumption of products made from Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) has increased in recent years in Japan. Increased consumer demand has led to recognition of the need for early varieties of this crop with high and stable yields. In order to accomplish this, more information is needed on the genetic mechanisms affecting earliness and yield. We conducted genetic analysis of 3 agronomic traits (days to flowering, plant height and total seed weight per plant) to segregate F₂ and F₃ populations derived from a cross between Tartary buckwheat cultivars ‘Hokuriku No. 4’ and ‘Ishisoba’. Broad-sense heritability estimates for days to flowering, plant height and total seed weight were 0.70, 0.62 and 0.75, respectively, in F₃ population. Narrow-sense heritability for total seed weight (0.51) was highest, followed by heritability for days to flowering (0.37), with heritability for plant height (0.26) lowest. Later flowering was associated with increased plant height and higher yields. From the F₄ generation, we identified twelve candidate plants with earlier maturity and reduced plant height compared to ‘Hokuriku No. 4’, but almost the same total seed weight. These results suggest that hybridization breeding using the single seed descent (SSD) method is an effective approach for improving agronomic characteristics of Tartary buckwheat.     

Artificially induced tetraploid masu salmon have the ability to form primordial germ cells

Diploid gametes generated with tetraploid animals are a stepping stone to improving chromosome manipulation techniques. However, artificially induced tetraploid individuals generally die soon after hatching. Diploid gametes could be induced by in vivo cultures of tetraploid primordial germ cells (PGCs) through germ-line chimera. In the present study, characteristics of PGCs were studied in inviable tetraploid masu salmon, Oncorhynchus masou. Histological observation of tetraploid embryos revealed that the same or smaller numbers of PGCs were observed and they migrate into the genital ridges as did diploid PGCs during gonadogenesis. By whole-mount in situ hybridization using vasa messenger RNA (mRNA), 4–35 vasa-positive signals were detected in a pair of genital ridges of tetraploids. By cytological observation of genital ridge cell suspensions, several large round cells were observed, some of which extended pseudopodia. They also contained large nuclei and round granules in their cytoplasm, characteristics of PGCs. As the results suggest that inviable artificial tetraploids have PGCs, we expect to achieve diploid gamete production through surrogate propagation and tetraploid fish production.     

Species-specific B-cell epitope on the C-terminal region of the alpha antigen from Mycobacterium intracellulare in mice

The alpha antigen, which is an immunodominant antigen, is a 30 kDa protein secreted by mycobacterial species. The C-terminal regions of alpha antigens are quite divergent. We investigated the question of whether the C-terminal regions of Mycobacterium avium alpha antigen (A-alpha), M. intracellulare alpha antigen (I-alpha) and M. bovis BCG alpha antigen (B-alpha) contained species-specific B-cell epitopes. We investigated the reactions of these peptides with anti-A-alpha, anti-I-alpha and anti-B-alpha sera prepared from BALB/c in a Western blot assay and ELISA. The C-terminal regions of I-alpha reacted exclusively with anti-I-alpha serum. The results of the inhibition assay of antibodies binding to I-alpha by peptides of C-A-alpha, C-I-alpha, and C-B-alpha are that only C-I-alpha inhibited the binding of antibodies to C-I-alpha. We found that the C-terminal region was B-cell epitope-specific to I-alpha in BALB/c mice.     

α-Melanocyte-stimulating hormone directly increases the plasma calcitonin level and involves calcium metabolism in goldfish

International Aquatic Research - The effects of α-melanocyte-stimulating hormone (α-MSH) on calcium metabolism were examined with goldfish. The scales on the left side of goldfish bodies...     

Cycloamylose (cyclodextrin) glucanotransferase degrades intact granules of potato raw starch

Cycloamylose (cyclodextrin) glucanotransferase (EC 2.4.1.19, CGTase) originated from Bacillus macerans degraded intact granules of potato raw starch and converted them into cyclodextrins (CDs). The degradation required sufficient stirring of starch-CGTase suspension. The morphology of the degraded starch granules was unique; that is, the inner part of the granules was observed by scanning electron microscope to be more susceptible to CGTase than the outer part. Effects of pH, temperature, starch concentration, and enzyme amount on CD production were studied.     

Organic acid excretion from roots: a plant mechanism for enhancing phosphorus acquisition,enhancing aluminum tolerance,and recruiting beneficial rhizobacteria

The beneficial effects of organic acids (OAs) excretion from plant roots were first proposed as being associated with the mechanism of superior phosphorus utilization by the cluster roots of white lupin (Lupinus albus L.), and these effects are now widely accepted as pleiotropic effects associated with stress tolerance of plants. Excreted OAs detoxify rhizotoxic aluminum, recruit beneficial bacterium for induced systemic resistance, and modify root architecture to enhance phosphorus starvation. OA excretion is probably optimized in the carbon economy and is coordinately regulated with other traits that additively confer each stress factor. Here we present an overview of the molecular physiology of OA excretion from roots, how plants activate OA excretion, and how this excretion can be managed as a specific response.     

Production and characterisation of monoclonal antibodies to cell wall components of the flax rust fungus

Monoclonal antibodies have been raised against an haustorium-enriched sample prepared from flax leaves infected with the biotrophic flax rust pathogen Melampsora lini. The monoclonal antibodies were produced following conventional and co-immunisation procedures and the range of antibody specificities was compared. The preparation used as immunogen for the conventional protocol was a crude isolate of haustoria consisting of approx. 65% fungal haustoria, the other components being mainly mesophyll cells or cell wall and chloroplast fragments. Following hybridoma production, 40% of positive cell lines produced antibodies that reacted with haustoria and other fungal cells, but 60% bound to plant cells in the infected leaves. For the co-immunisation protocol, the preparation used for immunisation consisted of the crude isolate of haustoria mixed with serum raised against an haustorium-depleted leaf homogenate. In two fusions, 92-94% of the antibodies reacted with fungal cells, including 3 cell lines that localised specifically to the cell wall of haustoria. Only 6-8% of the antibodies produced via co-immunisation reacted with plant cells. The antigens targeted by the three haustorium-specific monoclonal antibodies are incorporated into the wall at early stages of haustorium development, remain in the wall throughout haustorium maturation, and are present in both compatible and incompatible interactions. The epitopes recognised by the monoclonal antibodies are oligosaccharide in nature and the antigens are highly resistant to extraction from the wall. These results highlight the value of the co-immunisation protocol for the production of monoclonal antibodies to specific components in an impure preparation and provide direct evidence for molecular differentiation within the wall of the haustorium of M. lini.     

Sex change in coral reef fish

Gonadal differentiation can take many forms in fish, ranging from gonochorism, where individuals directly develop as male or female and finally possess only testis or ovaries at sexual maturation, to hermaphroditism where the same individuals can produce mature male and female gametes at some time in their lives. Hermaphrodite fish are, thus, an excellent model for studying the plasticity of sex determination and differentiation in vertebrates. We have shown that sex steroids play a principal role in sex differentiation and sex change in fish. Our laboratory implements several fish models that undergo sex change from female to male or male to female or in both directions. In this review, we will briefly discuss recent advances in our understanding of the mechanism of sex change in coral reef fish.     

Humeral Chondrosarcoma in a Hokkaido Brown Bear (Ursus arctos yesoensis)

Humeral chondrosarcoma was found in an 18-year-old male Hokkaido brown bear (Ursus arctos yesoensis). Necropsy revealed a large firm mass under the left superficial pectoral muscle at the axillary region. The mass involved the left shoulder joint and peripheral muscles, and connected to the head of the humerus with osteolysis. Histopathologically, the mass was composed of irregularly shaped myxomatous to cartilaginous tumor lobules. The tumor cell showed moderate nuclear atypia with a relatively high mitotic index, especially in the edges of the myxomatous lobules. The tumor cells were positively immunostained with vimentin and S-100 protein. Based on these findings, the tumors were diagnosed as chondrosarcoma. Metastases were found in the left axillary lymph node, lungs, liver and kidney.