Differences in longitudinal distribution patterns along a Honshu stream of brown trout <Emphasis Type="Italic">Salmo trutta</Emphasis>, white-spotted charr <Emphasis Type="Italic">Salvelinus leucomaenis</Emphasis> and masu salmon <Emphasis Type="Italic">Oncorhynchus masou</Emphasis>

Brown trout Salmo trutta were first introduced into Japan in 1892, and they currently naturally reproduce in several rivers in Honshu and Hokkaido, Japan. Although negative impacts of brown trout introductions on native salmonid fishes have been documented in some Hokkaido rivers, studies of ecological interactions between brown trout and native salmonid fishes on Honshu are limited. In this study, we describe the longitudinal distribution patterns of introduced brown trout, white-spotted charr Salvelinus leucomaenis and masu salmon Oncorhynchus masou in a 4 km stretch of a stream in central Honshu. Underwater observations were conducted in all pools within upstream, middle and downstream sections (190–400 m in length) of this stretch in order to estimate the densities of these species. Only white-spotted charr was observed in the upstream section, while brown trout and masu salmon were observed in the middle and downstream sections. Masu salmon densities, however, were much lower than brown trout densities. In the downstream section, white-spotted charr was absent. These results are consistent with results from previous studies of Hokkaido rivers, where it was found that white-spotted charr in low-gradient areas tend to be displaced by brown trout.     

QTL analysis for brown spot resistance in American rice cultivar ‘Dawn’

Rice brown spot (BS), caused by Bipolaris oryzae, causes yield loss and deterioration of grain quality. Using single-nucleotide polymorphism (SNP) markers, we conducted quantitative trait locus (QTL) analysis of BS resistance in backcross inbred lines (BILs) from a cross between an American rice cultivar, ‘Dawn’ (resistant), and ‘Koshihikari’ (susceptible). Four QTLs for BS resistance were detected in a three-year field evaluation, and ‘Dawn’ contributed the resistance alleles at all QTLs. The QTL with the greatest effect, qBSR6-kd, explained 15.1% to 20.3% of the total phenotypic variation. Although disease score and days to heading (DTH) were negatively correlated in all three years, qBSR6-kd was located near a QTL for DTH at which the ‘Dawn’ allele promoted heading. Another BS resistance QTL (qBSR3.1-kd) was unlinked to the QTLs for DTH. Therefore, these two QTLs are likely to be useful for breeding BS-resistant varieties without delaying heading. The other two BS resistance QTLs (qBSR3.2-kd and qBSR7-kd) were located near DTH QTLs at which the ‘Dawn’ alleles delayed heading. The QTLs reported here will be good candidates for developing BS-resistant cultivars.     

Breeding and characterization of the world’s first practical rice variety with resistance to brown spot (Bipolaris oryzae) bred using marker-assisted selection

Brown spot (BS) caused by Bipolaris oryzae is a serious disease of rice and decreases grain yield. Breeding for BS resistance is an economical solution but has not hitherto been achieved. To develop a practical BS-resistant variety, we introduced a chromosomal segment including a quantitative trait locus (QTL) for BS resistance, qBSfR11, derived from the BS-resistant local resource ‘Tadukan’, into the genetic background of the high-yielding but susceptible ‘Mienoyume’. Resistance is controlled by a single recessive gene in a 1.3-Mbp region. We named this gene bsr1 (brown spot resistance 1). The near-isogenic line bsr1-NIL had a greater yield with larger grain width than Mienoyume but similar other agronomic traits in fields where BS was mild; it had a significantly lower BS disease score and a 28.8% higher yield in fields where BS was more severe, and it showed resistance to multiple isolates of BS fungus. It showed stable resistance to BS and had excellent agricultural traits in the presence of BS. We developed the bsr1-NIL with resistance to BS and applied it for variety registration to Ministry of Agriculture, Forestry and Fisheries in Japan as ‘Mienoyume BSL’. This is the first report for the BS resistant rice variety bred using marker-assisted selection.     

Effect of the lateral growth rate on wood properties in fast-growing hardwood species

We investigated the feasibility of using several fast-growing tropical or subtropical hardwood species for timber production by measuring key wood qualities in relationship to the high rates of lateral growth. The trees tested were sampled from even-aged plantations of Acacia mangium, A. auriculiformis, hybrid Acacia (A. mangium × A. auriculiformis), Eucalyptus grandis, E. globulus, and Paraserianthes falcataria (Solomon and Java origin) that had already reached commercial harvesting age. The released strain of the surface growth stress (RS), xylem density (XD), microfibril angle (MFA), and fiber length (FL) were measured at the outermost part of the xylem at breast height in each tree. Results were then compared to the lateral growth rate (radius/age) at breast height, which provides a relative indicator of the amount of tree growth per year. Our findings indicated that RS was constant, regardless of lateral growth rate in each species. Similar results were observed for XD, MFA, and FL, with a few exceptions, suggesting that high growth rates do not intrinsically affect the wood properties of fast-growing tropical or subtropical species that have reached harvesting age. However, special attention must be paid to patterns of xylem maturation when developing plantations of such species.     

Effects of the lateral growth rate on wood quality parameters of Eucalyptus grandis from different latitudes in Brazil and Argentina

Climate change resulting from increased atmospheric carbon dioxide (CO₂) and shortages of fossil fuels such as petroleum are major problems worldwide. Under these conditions, demand for woody biomass resources is increasing. We investigated the feasibility of using fast-growing Eucalyptus grandis for material production. Samples of E. grandis were collected from four plantations in different latitude divisions, including tropical and subtropical Brazil and subtropical Argentina. Various xylem qualities were measured and related to the lateral growth rate. Lateral growth rate did not significantly affect the longitudinal released strain of the surface growth stresses or the xylem density at any of the sampling sites. Higher lateral growth rate, higher values of xylem density, and lower absolute values of the released strain were observed in plantations closer to the equator. Higher growth rates in tropical climate promote longer fiber length. In subtropical plantations, smaller diameter trees will produce tension wood with smaller microfibril angles. Planting E. grandis closer to the equator thus produces higher quality wood than in plantations at lower latitudes.     

Biological roles of monoterpene volatiles derived from rough lemon (<Emphasis Type="Italic">Citrus jambhiri</Emphasis> Lush) in citrus defense

Volatile compounds of plants, including monoterpenes, are a possible source of signal molecules that induce defense systems to protect plants from tissue damage. Volatile compounds from rough lemon leaves were trapped by solid-phase microextraction fibers in sealed vials, and subsequent gas chromatography–mass spectrometry and gas chromatography analyses identified the profile of the major components, mainly various monoterpenes. Among several monoterpenes examined, citral, citronellal, and linalool significantly inhibited the spore germination and hyphal growth of Alternaria alternata. The effect of linalool was fungistatic, while the effects of citral and citronellal were partially fungicidal. Wounding of rough lemon leaves induced a significant increase in release of monoterpenes. The release of linalool was the most abundant and was 14.5 times that of unwounded rough lemon leaves. Unlike the wounding treatment, microbe attack did not significantly change monoterpene releases, and there was statistically no difference found in the peak areas from microbe-treated and untreated leaves. Linalool, limonene, and β-pinene also had insect-repellant effects on wild-type Drosophila melanogaster. Expression patterns of defense-related genes in rough lemon and rice significantly changed after treatment with vapors of monoterpene volatiles. Taking these results together, monoterpene volatiles are likely to play roles in the defense of rough lemon against microbe and insect pathogens.     

Effect of recombinant bovine tumor necrosis factor-α on hormone release in lactating cows

Tumor necrosis factor (TNF)‐α is a powerful macrophage cytokine released during infection, circulating in the blood to produce diverse effects in the organism. We examined the effect of recombinant bovine TNF‐α (rbTNF‐α) administration on hormone release in dairy cows during early lactation. Twelve non‐pregnant Holstein cows were treated subcutaneously with rbTNF‐α (2.5 µg/kg) or saline twice (at 11.00 and 23.00 hours). At 11.00 hours the next day, the cows were given growth hormone‐releasing hormone (GHRH, 0.25 µg/kg), thyrotrophin‐releasing hormone (TRH, 1.0 µg/kg), thyroid‐stimulating hormone (TSH, 10 µg/kg) or adrenocorticotropic hormone (500 µg/head) via the jugular vein. In the growth hormone‐releasing hormone challenge, the plasma growth hormone concentration was lower in the rbTNF‐α group than in the control (saline) group. The growth hormone and TSH responses to TRH were also smaller in the rbTNF‐α group than in the control. The plasma prolactin response to TRH was not affected by the rbTNF‐α treatment. In the TSH challenge, the rbTNF‐α‐treated cows had lower responses, as measured by plasma triiodothyronine and thyroxine, than the control cows. The rbTNF‐α treatment produced an increase in the basal plasma cortisol level, but the cortisol response to adrenocorticotropic hormone was the same level in both groups. The plasma concentrations of TNF‐α and interleukin‐1β in the cows were elevated by the rbTNF‐α treatment. The milk yield was reduced by the rbTNF‐α administration during 4 days. These data demonstrate that TNF‐α alters the secretion of pituitary and thyroid hormones in lactating cows. This effect may contribute to the suppression of the lactogenic function of the mammary gland observed in cases of coliform mastitis with high circulating TNF‐α levels.     

Plasma concentrations of inhibin A in cattle with follicular cysts: relationships with turnover of follicular waves and plasma levels of gonadotropins and steroid hormones

We investigated the profiles of circulating levels of inhibin A and total inhibin in beef cows with follicular cysts in relation to the patterns of follicular development and circulating gonadotropins and steroid hormones. Turnover of follicular waves was monitored in five cows every 2 days for 70 days from 10 days after detection of estrus without ovulation. The mean interwave intervals were 19.6 ± 1.0 days (n = 18 waves with cysts from the five cows). Circulating levels of inhibin A were approximately 170 pg/ml before emergence of follicular waves with cysts and increased (P < 0.05) concomitantly with follicle emergence. High concentrations of inhibin A (greater than 300 pg/ml) were noted for 7 days during the growth phase of cystic follicles, but inhibin A levels decreased gradually when development of the cysts reached a plateau. This profile of inhibin A was similar to those of total inhibin and estradiol, but was inversely related to the changes in plasma FSH concentrations. LH pulse frequency and mean concentrations of LH in cows with cysts were higher than those observed in the luteal phase of normal cyclic cows. These results indicate that the capacity to secrete inhibin, as well as estradiol, is maintained in cystic follicles, the growth of which is extended by LH secretion at levels greater than those seen in the normal luteal phase. Inhibin A plays an important role in the extension of interwave intervals by suppressing recruitment of a new cohort of follicles.     

Thymoma in a dog with a part of granular cell proliferation and concurrent lymphoma cells

A 12-year-old male Shiba dog showed anemia and the swelling of systemic lymph nodes. X-ray and post mortal examinations revealed a anterior mediastinal mass. Histologically, the tumor mass consisted of four different elements; cord-like proliferation of cuboidal epithelial cells, tubular or cystic structures lined with ciliated epithelial cells, proliferation of large round-shaped epithelial cells with PAS-slightly positive granular cytoplasm, and diffuse proliferation of neoplastic lymphocytes. Epithelial cells in cord-like or cystic structures were strongly positive for cytokeratin. Granular or foamy cells were negative for all markers examined and had myelin-like bodies in the cytoplasm by electron microscopy. The neoplastic lymphocytes in the tumor mass were considered being derived from concurrent multicentric lymphoma. Based on these findings, the present case was diagnosed as thymoma with a part of granular cell proliferation and concurrent lymphoma cells.     

Molecular cloning and characterization of chicken tumor necrosis factor (TNF)-superfamily ligands, CD30L and TNF-related apoptosis inducing ligand (TRAIL)

CD30 ligand (CD30L) and tumor necrosis factor (TNF)-related apoptosis inducing ligand (TRAIL) are members of the TNF-superfamily that have many important biological activities in cell proliferation and apoptotic death. In this study, both genes in the chicken were cloned and their expression was analyzed. Complementary DNA fragments were obtained from a suppressive subtractive hybridization library with or without lipopolysaccharide (LPS)-stimulation. Chicken CD30L consists of 1,152 base pairs (bp) with an open reading frame (ORF) of 720 bp having 36.4% identity with human CD30L, whereas chicken TRAIL is 1,134 bp long with an ORF of 912 bp having 54.4% identity with human TRAIL. Chicken CD30L was expressed at high levels in the spleen, bursa of Fabricius and in the chicken monocytic leukemia cell line, IN24. Stimulation with LPS in the spleen, bursa of Fabricius and the IN24 cell line did not affect CD30L expression. The gene expression of chicken TRAIL was essentially to the same level in all tissues examined. The time course of expression was not significantly altered by LPS-stimulation in the spleen, thymus and bursa of Fabricius, but reached a maximal level 8 hr after stimulation in the IN24 cell line. The high level expression of both genes in lymphoid organs and IN24 cell line indicates that chicken CD30L and TRAIL may also play an important role in apoptotic signal transduction and the regulation of cell proliferation in the immune system.