TRIPLE‐PHASE HELICAL COMPUTED TOMOGRAPHY IN DOGS WITH HEPATIC MASSES

The purpose of this study was to determine the utility of triple‐phase helical computed tomography (CT) for differentiating canine hepatic masses. Seventy dogs with hepatic masses underwent triple‐phase CT followed by surgical removal of the hepatic masses. Triple‐phase helical CT scans for each dog included precontrast, arterial phase, portal venous phase, and delayed phase studies. The removed hepatic masses were histopathologically classified as hepatocellular carcinoma (n = 47), nodular hyperplasia (n = 14), and hepatic metastatic tumors (n = 9) in dogs. Of the 47 hepatocellular carcinomas, the most common CT findings included a heterogeneous pattern with hyper‐, iso‐, and hypoenhancement in both the arterial and portal venous phases (40/47, 85.1%). Of the 14 nodular hyperplasias, the most common CT findings were a homogeneous pattern with hyper‐ and isoenhancement in both the portal venous and delayed phases (13/14, 92.9%). Of nine hepatic metastatic tumors, the most common CT findings included a homogeneous hypoenhancement pattern in both the arterial and portal venous phases (8/9, 88.9%). In addition, 5 (55.6%) showed homogeneous hypoenhancement patterns in the delayed phase. Findings from our study indicated that triple‐phase CT is a useful tool for preoperative differentiation of hepatocellular carcinoma, nodular hyperplasia, and hepatic metastatic tumors in dogs.     

Effects of a breeding scheme combined by genomic pre‐selection and progeny testing on annual genetic gain in a dairy cattle population

The effectiveness of the incorporation of genomic pre‐selection into dairy cattle progeny testing (GS‐PT) was compared with that of progeny testing (PT) where the fraction of dam to breed bull (DB) selected was 0.01. When the fraction of sires to breed bulls (SB) selected without being progeny tested to produce young bulls (YB) in the next generation was 0.2, the annual genetic gain from GS‐PT was 13% to 43% greater when h² = 0.3 and 16% to 53% greater when h² = 0.1 compared with that from PT. Given h² = 0.3, a selection accuracy of 0.8 for both YB and DB, and selected fractions of 0.117 for YB and 0.04 for DB, GS‐PT produced 40% to 43% greater annual genetic gain than PT. Given h² = 0.1, a selection accuracy of 0.6 for both YB and DB, and selected fractions of 0.117 for YB and 0.04 for DB, annual genetic gain from GS‐PT was 48% to 53% greater than that from PT. When h² = 0.3, progeny testing capacity had little effect on annual genetic gain from GS‐PT. However, when h² = 0.1, annual genetic gain from GS‐PT increased with increasing progeny testing capacity.     

Challenges of breeding potato cultivars to grow in various environments and to meet different demands

The potato (Solanum tuberosum L.) is cultivated all year round in Japan by using four types of cropping: summer and winter croppings, and double cropping in spring and fall. In each cropping season, growth conditions such as temperature, day length, and growing period, differ drastically; thus, different cultivars adapted to each environment are required. Breeding stations are located in both summer cropping areas and double cropping areas, and cultivars suitable for each cropping system are developed. The required cultivars differ according to cropping type and according to use such as table use, food processing, and starch production. The qualities necessary for each purpose differ and are therefore evaluated accordingly. Improvements in pest and disease resistance and in yield abilities are important as common breeding targets for all purposes. To develop potato cultivars that meet different needs, breeders have continued efforts to improve these traits. In this review, we introduce our approaches to developing new potato cultivars. We also discuss problems predicted in the future and introduce our efforts on broadening genetic diversity.     

Quantitative trait loci for rice blast resistance detected in a local rice breeding population by genome-wide association mapping

Plant breeding programs aim to develop cultivars with high adaptability to the specific conditions in a local region. As a result, unique genes and gene combinations have been accumulated in local elite breeding populations during the long history of plant breeding. Genetic analyses on such genes and combinations may be useful for developing new cultivars with more-desirable agronomic traits. Here, we attempted to detect quantitative trait loci (QTL) for rice blast resistance (BR) using a local breeding rice population from Hokkaido, Japan. Using genotyping data on single nucleotide polymorphisms and simple sequence repeat markers distributed throughout the whole genomic region, we detected genetic regions associated with phenotypic variation in BR by a genome-wide association mapping study (GWAS). An additional association analysis using other breeding cultivars verified the effect and inheritance of the associated region. Furthermore, the existence of a gene for BR in the associated region was confirmed by QTL mapping. The results from these studies enabled us to estimate potential of the Hokkaido rice population as a gene pool for improving BR. The results of this study could be useful for developing novel cultivars with vigorous BR in rice breeding programs.     

Genetic variation and phylogenetic relationships in East and South Asian melons, Cucumis melo L., based on the analysis of five isozymes

Genetic structure and phylogenetic relationships in East and South Asian melons were analyzed, based on the geographical variation of five isozymes. The analysis of Indian melon accessions showed a continuous variation in seed length, ranging from 4 to 13 mm. Most of the East Asian melons, vars. makuwa and conomon, were classified as the small seed type with seed length shorter than 9 mm. The frequency of the small seed type increased from the west to the east in India. Allelic variation was detected at a total of nine loci of five isozymes among 114 melon accessions. Gene diversity calculated for the nine loci indicated that Indian melon was rich in genetic variation, which decreased from India towards the east. Clear geographical variation was detected in two enzymes, APS and6-PGDH. Pgd-1 ¹ and Ap-3 ¹ were frequent in India and Myanmar, while most of the melons in Laos, China, Korea and Japan carried Pgd-1 ³ and Ap-3 ³, except var. inodorusin China. Among the latter two alleles, the frequency of Ap-3 ³ was more than 50% in the small seed type in north and east India, indicating that vars. makuwa and conomon were related to the small seed type in these areas. It was also suggested that the small seed type with wet tolerance originated in central India and was selected under wet condition in the east. This revised version was published online in August 2006 with corrections to the Cover Date.     

DNA polymorphisms in Oryza sativa L. and Lactuca sativa L. amplified by arbitrary primed PCR

Summary Thirty-five rice (Oryza sativa L.) varieties, including 18 japonica, 5 javanica and 12 indica subspecies and 12 lettuce (Lactuca sativa L.) varieties were identified taxonomically, using PCR with originally designed 21 RAPD (Random Amplified Polymorphic DNA) primers and 8 sequence-specific primers, used for amplifying four specific DNA fragments. Use of these primers revealed polymorphisms among varieties in rice and lettuce and facilitates DNA fingerprinting. Dendrograms of both species based on polymorphisms were constructed and genetical relationships were established. In rice, half the number of amplified bands were polymorphic and almost all varieties differentiated. However, differentiation of minor genetic alterations among somaclonal variants or mutants and their mother varieties was not feasible. In L. sativa, 47% of the amplified fragments were polymorphic and all 12 varieties were differentiated. Some of the PCR fragments were variety or type specific, which could be used for indicators for type-selection. The dendrogram obtained showed differentiated clusters of crisphead, leaf and butterhead type, findings in good accord with the classification based on the genetic background.     

Mitochondrial DNA variation in foxtail millet, Setaria italica (L.) P. Beauv.

Mitochondrial DNA (mtDNA) wascharacterized by RFLPs in 94 strains offoxtail millet, Setaria italica (L.)P. Beauv. Three RFLP patterns wereobserved by using rice atp6 as aprobe, and were designated as types I-III. Difference between types I and II seems tobe attributed to recombination between twoatp6 genes. In East and SoutheastAsia and Afghanistan, both of types I andII were found, while type I was predominantin India, Central Asia and Europe. InChina, type III was also found. Chinesestrains showed higher gene diversity thanthose from other regions. This resultcoincided the previous studies on isozymesand nuclear RFLPs.     

Anti-Thy-1 Antibody-mediated Complement-dependent Cytotoxicity is Regulated by the Distribution of Antigen,Antibody and Membrane Complement Regulatory Proteins in Rats

Some therapeutic antibodies as anticancer agents exert their effects through the host immune system, but the factors that predict their cytotoxicity, including complement-dependent cytotoxicity (CDC), are unclear. In the present study, we attempted to elucidate some of these factors in a preclinical model. CDC-related mesangiolysis caused by administration of the anti-Thy-1.1 antibody can be studied in the rat anti-Thy-1 glomerulonephritis model, so the model was used in this study. Three animals each were sacrificed at 0.5, 1, 8, 24 and 48 hours after i.v. administration of the anti-Thy-1.1 antibody at 1mg/kg. The distribution of the Thy-1.1 antigen and 2 membrane complement regulatory proteins (mCRPs), Crry and CD55, in three non-treated animals and the distribution of the injected antibody and C3 in the model was studied by immunohistochemistry. In the mesangial cells of the kidney, both expression of the antigen and distribution of the antibody with C3 deposition were observed with weak expression of mCRPs. There was also antigen and antibody distribution in the medullary cells of the adrenal gland and in the lymphocytes of the thymus but no C3 deposition, which was thought to be related to high expression of mCRPs. The antigen was observed in several other organs and tissues without distribution of the antibody. Cell death was only observed in the mesangial cells. These results clearly demonstrate that activation of CDC is regulated by several factors, such as distribution of the target molecule, antibody distribution and the balance among the molecules of the CDC cascade and mCRPs.     

Identification of food-derived elastin peptide, prolyl-glycine (Pro-Gly), in human blood after ingestion of elastin hydrolysate

Elastin hydrolysate has apparent beneficial effects, and the food-derived peptide prolyl-glycine (Pro-Gly) is present in human blood after oral ingestion. Following ingestion of elastin hydrolysate (10 g/60 kg body weight) by healthy human volunteers, peripheral blood was used to prepare plasma samples from which peptides were extracted by solid phase extraction and fractionated by size-exclusion chromatography (SEC). Peptides in the SEC fractions were derivatized with phenyl isothiocyanate (PITC) and resolved by reversed phase (RP)-HPLC. Pro-Gly was the major food-derived elastin peptide, reaching a maximum (18 μM) at 30 min after ingestion, and decreasing to approximately 20% at 4 h after ingestion. Finally, in cell culture, levels of Pro-Gly in the medium above 0.1 μg/mL significantly enhanced elastin synthesis of normal human dermal fibroblasts (NHDF) without affecting the rate of cell proliferation.