Sample size required for marker assisted selection in improving quantitative traits of self-fertilizing species

The efficiency of selection for desired trait genotypes in a molecular marker assisted selection for a quantitative trait in self-fertilizing crop is considered. The QTLs controlling the trait were assumed to be unlinked. It was supposed that the selection starts in F₂, derived from a cross between inbred lines, and this selection will terminate if one or more plants with the desired trait genotype is found. If no plant with the desired trait genotype is found in F₂ then the selection is continued in the F₃ progeny that is derived from a single selected F₂ plant. Which F₂ plant is to be selected was determined according to the rank which is related to the marker genotype of the F₂ plants. And this rank was based on the expected frequency of the desired trait genotype in the progeny. The plant with the top rank among all F₂ plants is then selected with the first priority. Additionally the number of F₃ plants in the progeny was set to be equal to the number of plants that are required for detecting one or more plants with the desired trait genotype with a given probability. The probability of getting at least one plant with the desired trait genotype is expressed as a function of the number of F₂ plants (N).The required value for N and the total number of plants (T) in F₂ and F₃ for detecting at least one plant with the desired trait genotype were calculated for different situations. T was always smaller for a single marker than for flanking markers. The minimum of T and monotonous decrease of N can be observed when the cumulative-expected-frequency of selected marker genotypes of F₂ plants increased. This revised version was published online in July 2006 with corrections to the Cover Date.     

Dietary supplementation with cellooligosaccharide improves growth performance in weanling pigs

Nondigestible oligosaccharides are not digested in the small intestine, but are fermented by bacteria colonizing in the large intestine. Physiological effects of non‐digestible oligosaccharides have been considered to be conferred by the fermentation of bacteria colonizing in the large intestine. Because cellooligosaccharide is a non‐digestible oligosaccharide, various physiological effects are expected. However, physiological functions of cellooligosaccharide are not well understood. This experiment was conducted to clarify the effect of dietary supplementation with cellooligosaccharide on the growth performance in weanling pigs. The result showed that average daily gain was significantly higher (P < 0.05) in pigs fed a diet supplemented with cellooligosaccharide than in pigs without cellooligosaccharide. There was a tendency to increasing average daily feed intake in pigs with cellooligosaccharide, though the significant difference was not detected (P = 0.18). Feed efficiency and nutrient digestibility of feces and ileum were not changed by feeding cellooligosaccharide. In addition, blood urea nitrogen was significantly higher (P < 0.05) in pigs fed the diet supplemented with cellooligosaccharide than in pigs without cellooligosaccharide. The concentrations of acetic and iso‐valeric acids in the cecum of pigs fed the diet with cellooligosaccharide tended to be higher (P < 0.10) than those without cellooligosaccharide. The results obtained in this study demonstrated that dietary supplementation with cellooligosaccharide improves growth performance in weanling pigs.     

Development of immune assay system for both CpG and non-CpG DNA from lactic acid bacteria using a transfectant of swine Toll-like receptor 9

Bacterial DNA is expected to be a potent immune stimulating agent to Toll‐like receptor (TLR) 9 expressed cells such as macrophages, monocytes, B lymphocytes, NK cells and dendritic cells. In the present study, we constructed a transfectant of swine TLR9 with mammalian cells. We demonstrated that the transfectant, recognizing both CpG and non‐CpG oligonucleotides from lactic acid bacteria, induced NF‐κB activation by gene reporter assay. These findings indicate that the swine TLR9 transfectant will be highly useful for the screening of immunostimulatory DNA from lactic acid bacteria.     

Traumatic resin-canal formation caused by inoculation withCistella japonica in secondary phloem ofChamaecyparis obtusa

In the resinous lesion development caused by the inoculation withCistella japonica onChamaecyparis obtusa stem, numerous traumatic resin-canals were formed at certain radial intervals in the secondary phloem. These formation started in the ring grown in the current or the previous year of inoculation and the resin-canals were subsequently formed in the newly grown rings. The resin-canals were arranged in tangential series in one to two lines in an annual-ring. Artificially induced resin-canal formation was similar to that in naturally infected resinous stem canker. The results from the present study reconfirmed thatCi. japonica is the causal agent of the disease.     

Rapid genotyping with DNA micro-arrays for high-density linkage mapping and QTL mapping in common buckwheat (Fagopyrum esculentum Moench)

For genetic studies and genomics-assisted breeding, particularly of minor crops, a genotyping system that does not require a priori genomic information is preferable. Here, we demonstrated the potential of a novel array-based genotyping system for the rapid construction of high-density linkage map and quantitative trait loci (QTL) mapping. By using the system, we successfully constructed an accurate, high-density linkage map for common buckwheat (Fagopyrum esculentum Moench); the map was composed of 756 loci and included 8,884 markers. The number of linkage groups converged to eight, which is the basic number of chromosomes in common buckwheat. The sizes of the linkage groups of the P1 and P2 maps were 773.8 and 800.4 cM, respectively. The average interval between adjacent loci was 2.13 cM. The linkage map constructed here will be useful for the analysis of other common buckwheat populations. We also performed QTL mapping for main stem length and detected four QTL. It took 37 days to process 178 samples from DNA extraction to genotyping, indicating the system enables genotyping of genome-wide markers for a few hundred buckwheat plants before the plants mature. The novel system will be useful for genomics-assisted breeding in minor crops without a priori genomic information.     

Molecular cloning and expression profiling of procollagen α1 (I) of cultured Pacific bluefin tuna

Type I collagen is widely distributed in most organs in teleosts. It plays a role not only in intercellular adhesion, but also in molecular signaling. In this study, Pacific bluefin tuna (PBT) procollagen α1 (I) cDNA was cloned and characterized. The nine fragments of a procollagen α1 (I) chain cDNA clone were prepared and spliced together to create the complete coding region. The resulting amino acid sequence was homologous with that of other teleosts. The mRNA expression profile of PBT procollagen α1 (I) in various tissues and the phylogenetic analysis with other vertebrate procollagen α1 (I) chains suggest that PBT procollagen α1 (I) could be a precursor form of the PBT type I collagen α1 chain. In addition, its level of expression in PBT larvae and early juveniles gradually increased with somatic growth. This increase was related to the standard length, wet body weight, and protein content of each individual fish. Therefore, the expression profile of procollagen α1 (I) may be a useful indicator for somatic growth in fish larvae and juveniles.     

Teratogenic effects of isolated and combined short‐term hypercapnia and hypoxia on red sea bream (Pagrus major) embryos

Some vertebral anomalies in cultured fish arise from unusual environmental conditions during embryogenesis. We investigated the individual and combined teratogenic effects of short‐term hypercapnia and hypoxia on embryos of red sea bream (RSB), Pagrus major. Ten‐somite stage embryos were exposed to hypercapnia (60 and 120 mg/L dissolved carbon dioxide: DCD) and hypoxia (0%, 10%, 25%, 50%, and 75% dissolved oxygen: DO) independently and concomitantly for seven different periods (0, 30, 60, 90, 120, 150 and 180 min) to examine somitic disturbances at hatching, which are prodromal symptoms of centrum defects. Another experiment examined vertebral anomalies in juveniles raised from eggs exposed to hypercapnia (120 mg/L DCD) and hypoxia (10% DO) independently and concomitantly. Short‐time exposures (30–180 min) to hypercapnia (60 and 120 mg/L) and hypoxia (10% DO or less) independently and additively caused larval somitic disturbances and juvenile centrum defects. The results indicate that short‐term hypercapnia and hypoxia generally have the same teratogenic effect on embryos, although there were some differences in the locations of the somitic disturbances and centrum defects, with additive teratogenicity when the conditions were combined. These results suggest the necessity of maintaining appropriate DCD and DO concentrations during egg incubation and transport and during reproduction in recirculating aquaculture.