Anatomical variation of arterial supply to the rabbit spleen

The rabbit, which is widely used as an experimental animal and is also popular as a companion animal, has a flat and elongated spleen with the longitudinal hilus running along its visceral surface. The spleen receives via the hilus an arterial supply that is essential for splenic nutrition and normal functioning. However, the distribution and variation of the arteries to the spleen have not been studied in detail. This study investigated anatomical variations of splenic arterial supply in 33 New Zealand White rabbits with a colored latex injection into arteries. We also examined whether the length of the spleen correlated with the number of the splenic branches of the splenic artery. The splenic artery always arose as the first independent branch of the celiac artery and ran along the splenic hilus to usually provide 6 (range, 3 to 10) splenic branches to the spleen. There was a moderate correlation (R=0.6) between the number of splenic branches and the longitudinal length of the spleen. The splenic branches often arose as a trunk or trunks in common with short gastric arteries. The number of common trunk(s) was usually 1 (range, 0 to 4). The data showed that the pattern and number of arterial branches to the spleen varied according to the individual animal, suggesting that such variations should be considered when performing experimental and veterinary surgical treatments in rabbits.     

Cellularity of developing subcutaneous adipose tissue in Landrace and Meishan pigs: Adipocyte size differences between two breeds

Experiments were designed to compare the adipocyte cellularity of subcutaneous adipose tissue between growing Landrace (low backfat) and Meishan (high backfat) pigs at 1 week, 3 weeks, 6 weeks, 3 months and 5 months of age. As pigs aged, body weight and backfat thickness of both breeds significantly increased. When compared at equal ages, backfat thickness adjusted to equal body weight was greater for Meishan pigs. The mean diameter of fat cell size also increased with age, and by 6 weeks adipocytes from both outer and inner layers of subcutaneous adipose tissue were larger in Meishan pigs. At 5 months, approximately 80% of the adipose tissue mass in Meishan pigs was attributable to adipocytes measuring 95–165 µm in diameter, whereas adipocytes of 75–145 µm comprised most of the tissue mass in the Landrace. Although the contribution of smaller adipocytes (25–45 µm) to the tissue volume was negligible, both breeds showed a biphasic diameter distribution at all ages, suggesting that adipocyte hyperplasia is still active. Our results demonstrate that cellularity differences exist between the subcutaneous adipose tissues of Landrace and Meishan pigs, and adipocyte hypertrophy is the most overwhelming contributor to the greater backfat deposition for Meishan pigs.     

Regulation of muscular glutamate metabolism by high‐protein diet in broiler chicks

The major taste active component, glutamate (Glu), improves the taste of meat. In this study, we investigated the effect of a short‐term high‐protein (HCP) diet on the intramuscular free Glu content to improve the taste of meat. Furthermore, we elucidated how the muscle free Glu content was controlled by the HCP diet. Chicks (14 days old) were fed the control diet or HCP diet for 10 days. Plasma and muscle free amino acid concentrations, and activity and messenger RNA (mRNA) expression of muscle enzymes related to Glu metabolism were determined. Muscle free Glu content was increased (P < 0.01) by 51%. Activity and mRNA expression of glutaminase (GA), which is one of the major Glu‐related enzymes, were significantly decreased (P < 0.05) in the HCP group because of feedback inhibition. The mRNA expression of lysine α‐ketoglutarate reductase (LKR), which is the enzyme involved in lysine (Lys) degradation and Glu production, was significantly increased (P < 0.001) in the HCP group. These results suggest that short‐term dietary HCP feeding is an effective treatment for improving the taste of meat. Furthermore, our results suggest that the free Glu content in muscle is regulated by GA and LKR.     

Effects of muscle type on beef taste‐traits assessed by an electric sensing system

To assess the role of muscle fiber type in beef taste‐traits, we analyzed cooked meats from bovine masseter, diaphragm, psoas major, longissimus thoracis, and semitendinosus muscles with an electric taste sensing system (INSENT SA402B). The system is composed of five taste sensors of polymer membranes fixing different lipids. The sensors, CT0, CA0, AAE, C00 and AE1 are designed to respond to the individual tastes of salty, sour, umami, bitter and astringent, respectively. The system found significant differences in the converted outputs of CA0 (cvCA0), C00 (cvC00) and AE1 (cvAE1) among the bovine muscles. The slow‐type muscles (masseter and diaphragm) showed lower cvCA0, higher cvC00, and higher cvAE1 than did the fast‐type muscles (psoas major, longissimus thoracis, and semitendinosus). Lactic acid content was different among muscle types and was highly related to the cvCA0 output and pH. carbonyl compounds and free fatty acids were higher in the slow‐type muscles. Free fatty acids were major components causing the difference in the C00 output among the muscle types. Iron content was also different among the muscle types and related to the cvC00 and cvAE1 outputs. These results suggested that the muscle fiber type affects the beef taste characteristics.     

Identification of a bacterium isolated from galls on carrot and weeds

In 2004, bacterial galls were found on the roots of carrots in Shizuoka Prefecture, Japan. Galls were about 0.1–2 cm in diameter, light brown in color and had rough surfaces. In 2005, similar galls were found on the roots of three weeds: henbit (Lamium amplexicaule L.), Persian speedwell (Veronica persica Poir.) and leaf mustard (Brassica juncea L.). A bacterium that forms white, rough colonies was isolated from the carrot and weeds galls. The bacterial isolates had properties identical with Rhizobacter dauci Goto and Kuwata. Phylogenetic analysis based on 16S rDNA sequences showed that the carrot isolate had the highest homology (similarity of 100%) with that of the type strain of R. dauci. Rep-PCR genomic fingerprinting using BOX A1R primer showed that the carrot and weeds isolates were nearly identical. Pathogenicity of the isolates was confirmed by inoculating the roots of carrots and the weeds. After 2–5 weeks, they formed galls on the roots of the original host species and on other plant species tested. The galls were indistinguishable from those formed naturally, and the inoculated bacterium was reisolated. Thus, the causal bacterium of carrot and weeds gall was identified as R. dauci, and the bacterium was found to have a wider host range than previously known. These weed hosts may serve as inoculum sources for carrot bacterial gall disease.     

Anther culture in rice proportionally rescues microspores according to gametophytic gene effect and enhances genetic study of hybrid sterility

Background

To investigate plant hybrid sterility, we studied interspecific hybrids of two cultivated rice species, Asian rice (Oryza sativa) and African rice (O. glaberrima). Male gametes of these hybrids display complete sterility owing to a dozen of hybrid sterility loci, termed HS loci, but this complicated genetic system remains poorly understood.

Results

Microspores from these interspecific hybrids form sterile pollen but are viable at the immature stage. Application of the anther culture (AC) method caused these immature microspores to induce callus. The segregation distortion of 11 among 13 known HS loci was assessed in the callus population. Using many individual calli, fine mapping of the HS loci was attempted based on heterozygotes produced from chromosome segment substitution lines (CSSLs). Transmission ratio distortion (TRD) from microspores was detected at 6 of 11 HS loci in the callus population. The fine mapping of S₁ and S₁₉ loci using CSSLs revealed precise distances of markers from the positions of HS loci exhibiting excessive TRD.

Conclusions

We demonstrated that AC to generate callus populations derived from immature microspores is a useful methodology for genetic study. The callus population facilitated detection of TRD at multiple HS loci and dramatically shortened the process for mapping hybrid sterility genes.

     

Effects of salt stress on plant growth characteristics and mineral content in diverse rice genotypes

ABSTRACT

When rice is grown under moderate salinity (6?dS m^?1), yields are reduced by up to 50%. The development of salt-tolerant varieties is a key strategy for increasing yields. We conducted an experiment using a hydroponic system with ion components similar to seawater to determine useful parameters for assessing salt tolerance. Two-week-old seedlings were grown for 7 days on Yoshida hydroponic solution. The treatment group then additionally received an artificial seawater solution (electrical conductivity, 12 dS m^?1). After a 2-week period of salt stress, standard evaluation scores (SES) of visual salt injuries were assessed. The K, Na, Mg, and Ca contents were then determined in the roots, sheaths, and leaves of each plant. Following the SES results, we divided the 37 genotypes into four groups: salt-tolerant groups (STGs), moderately salt-tolerant groups, salt-sensitive groups (HSSGs), and highly salt-sensitive groups (HSSGs). In the control, STGs had the highest sheath K content (30.1 mg g^?1 dried weight [DW]), whereas HSSGs had the lowest (21.4 mg g^?1 DW). Sheath K was also highly and negatively correlated with SES. This suggests that sheath K may be useful for identifying salt-tolerant varieties under non-saline conditions. Plant growth was significantly affected under salt stress, but STGs had the smallest decrease in sheath DW. SES was significantly correlated with sheath and leaf Na, sheath K and Mg, and sheath and leaf Na/K and Na/Mg ratios. The results suggested that sheath K, Na/K, and Na/Mg may be useful indicators for genetic analyses of salt-tolerant varieties under salt-stress conditions. The salt-tolerant cultivars, KCR20, KCR124, and KCR136, are possible candidates for such studies because they had high sheath K content (31.19, 31.21, 29.44 mg g^?1 DW, respectively) under non-saline conditions and low SES (3.3, 3.6, 3.9, respectively), and low sheath Na/K (0.64, 0.52, 0.92, respectively) and Na/Mg ratios (2.96, 2.27, 3.03, respectively) under salt-stress conditions.     

Two novel QTLs regulate internode elongation in deepwater rice during the early vegetative stage

Deepwater rice possesses internode elongation ability to avoid drowning under deepwater conditions. Previous studies identified three QTLs regulating internode elongation ability on chromosomes 1, 3 and 12 using different populations. However, these QTLs only induce internode elongation in response to deepwater conditions from the 7-leaf stage and not during the early leaf stage. In this study, we detected two novel QTLs, qTIL2 and qTIL4 regulating deepwater response at the early leaf stage using an F₂ population derived from the cross between NIL1-3-12 carrying the three QTLs regulating deepwater response in T65 (O. sativa ssp. japonica) genetic background and C9285 (O. sativa ssp. indica, deepwater rice). Plants of the BC₂F₂ population derived from NIL1-3-12/C9285 and the RILs of T65/Bhadua (O. sativa ssp. indica, deepwater rice) possessing these QTLs as well as the three QTLs previously identified also showed internode elongation during the early leaf stage. These results indicate that qTIL2 and qTIL4 regulate early internode elongation and function in coordination with the three major QTLs under deepwater conditions. The results presented here would not only help define the mechanism of deepwater response in rice but also contribute in the breeding of deepwater tolerant rice that is adapted to various water depths.     

Factors affecting methane production and mitigation in ruminants

Methane (CH₄) is the second most important greenhouse gas (GHG) and that emitted from enteric fermentation in livestock is the single largest source of emissions in Japan. Many factors influence ruminant CH₄ production, including level of intake, type and quality of feeds and environmental temperature. The objectives of this review are to identify the factors affecting CH₄ production in ruminants, to examine technologies for the mitigation of CH₄ emissions from ruminants, and to identify areas requiring further research. The following equation for CH₄ prediction was formulated using only dry matter intake (DMI) and has been adopted in Japan to estimate emissions from ruminant livestock for the National GHG Inventory Report: Y = −17.766 + 42.793X − 0.849X², where Y is CH₄ production (L/day) and X is DMI (kg/day). Technologies for the mitigation of CH₄ emissions from ruminants include increasing productivity by improving nutritional management, the manipulation of ruminal fermentation by changing feed composition, the addition of CH₄ inhibitors, and defaunation. Considering the importance of ruminant livestock, it is essential to establish economically feasible ways of reducing ruminant CH₄ production while improving productivity; it is therefore critical to conduct a full system analysis to select the best combination of approaches or new technologies to be applied under long-term field conditions.     

Monoaminergic Innervation of the Caudal Neurosecretory System of the Carp, Cyprinus carpio

Monoamine fluorescence was studied in the caudal neurosecretory system of eighty-four adult carp, Cyprinus carpio, of either sex. Some neurosecretory cells were surrounded with monoaminergic fluorescent varicosities, while others were not. The varicosities werc: also found adjacent to nerve terminals or capillaries in the urophysis. Noradrenaline, but not adrenaline or dopamine, was detected memically in the urophysis and the spinal cord. These results suggest that noradrenergic neurons seem to regulate both the synthesis and the release of neurosecretory material in the carp caudal neurosecretory system.