Induction of inflammatory arthropathy resembling rheumatoid arthritis in mice transgenic for HTLV-I

Human T cell leukemia virus type-I (HTLV-I) is the etiologic agent of adult T cell leukemia and has also been suggested to be involved in other diseases such as chronic arthritis or myelopathy. To elucidate pathological roles of the virus in disease, transgenic mice were produced that carry the HTLV-I genome. At 2 to 3 months of age, many of the mice developed chronic arthritis resembling rheumatoid arthritis. Synovial and periarticular inflammation with articular erosion caused by invasion of granulation tissues were marked. These observations suggest a possibility that HTLV-I is one of the etiologic agents of chronic arthritis in humans.     

Responses of leaf photosynthesis and plant growth to altered source–sink balance in a Japanese and a Dutch tomato cultivar

We investigated the effects of altered source/sink ratio by leaf or fruit pruning on leaf photosynthetic characteristics and whole-plant growth of ‘Momotaro York’, a Japanese cultivar, and ‘Dundee’, a Dutch cultivar and verified a hypothesis for sink-limitation of plant growth proposed by Tanaka and Fujita (1974). Plants were grown hydroponically with a high-wire system in a greenhouse for 11 weeks. Light-saturated photosynthesis of young, fully expanded leaves measured at atmospheric CO₂ partial pressure of 37 Pa and at an intercellular CO₂ partial pressure of 20 Pa was not influenced by alteration of source/sink ratio for either cultivar. Although soluble sugars were accumulated in leaves under high source/sink conditions, the amount of ribulose-1,5-bisphosphate carboxylase/oxygenase, a rate-limiting factor for CO₂-limited photosynthesis, was not affected by the altered source–sink balance. Net assimilation rate of a whole plant increased with decreasing source/sink ratio, but this can be accounted for by the changes in light interception per unit leaf area, without taking the source–sink relationship into consideration. It was concluded that the altered source/sink ratio did not change leaf photosynthetic capacity and the sink-limitation hypothesis cannot be applied to either cultivar under the conditions of the present study.     

Growth characteristic and sink strength of fruit at different CO2 concentrations in a Japanese and a Dutch tomato cultivar

The aim of the present study was to elucidate how fruit growth was limited by the source and sink capacities in a Japanese (‘Momotaro York’) and a Dutch (‘Dundee’) tomato cultivar. The two cultivars were grown hydroponically with a high-wire system in greenhouses for 25 weeks, and the growth characteristics and sink strength of fruit were determined. Fruits were pruned to four (4F) or one (1F) per truss. The latter were used to determine potential fruit growth, an indicator of fruit sink strength. Growth was also determined under normal (LC) and enriched (HC, 700 μmol mol⁻¹) CO₂ concentrations to examine the effect of source enhancement on fruit production. In both cultivars under normal CO₂, the growth rate of fruit pruned to 4F per truss was lower than that in 1F, indicating that maximum potential fruit growth was not achieved. Under HC conditions, fruit growth rate of ‘Dundee’ achieved in 4F trusses was lower than that in 1F. In ‘Momotaro York’ in HC, fruit growth in 4F trusses was close to potential. This implies that fruit growth was source-limited irrespective of CO₂ concentrations in ‘Dundee’ cultivar while fruit growth in ‘Momotaro York’ under normal and enriched CO₂ conditions was limited by source and sink strengths, respectively. Adjustments of cultural practices including increasing fruit number per truss and/or genetic approaches to enhancing fruit sink strength by breeding may improve fruit yields of Japanese cultivars under high source/sink conditions.     

Green-odour compounds have antifungal activity against the rice blast fungus <Emphasis Type="Italic">Magnaporthe oryzae</Emphasis>

Four green-odour compounds—trans-2-hexenal, cis-3-hexenol, n-hexanal, and cis-3-hexenal—were applied (0.85 μg ml⁻¹ as vapour) to rice plants in laboratory conditions to observe their biological activity against the phytopathogenic fungus Maganporthe oryzae, which causes rice blast disease worldwide. Two compounds, trans-2-hexenal and cis-3-hexenal, showed remarkable disease suppression efficacy (99.7% and 100% suppression, respectively), while n-hexanal had moderate (86.5%) and cis-3-hexenol had weak (20.8%) disease-suppressing effects. Pre-application and post-application of trans-2-hexenal or cis-3-hexenal had slight effects on blast incidence, suggesting that these compounds had direct effects to suppress M. oryzae infection. In fact, trans-2-hexenal and cis-3-hexenal exhibited a growth suppression effect on M. oryzae. Interestingly, these two compounds inhibited appressorium formation at lower concentrations than the growth suppression. Studies on the hypersensitive response (HR)-like reaction and plant β-1,3-glucanase activity in rice plant confirmed that induced resistance was not the major factor involved in the disease suppression mechanism. Results of this study conclusively showed that trans-2-hexenal and cis-3-hexenal possess potent inhibitory activities against the growth and the appressorium formation of M. oryzae and could be used as antifungal agents to significantly reduce M. oryzae infections in rice.     

A tripartite standards regime analysis of the contested development of a sustainable agriculture standard

As concerns over the negative social and environmental impacts of industrial agriculture become more widespread, efforts to define and regulate sustainable agriculture have proliferated in the US. Whereas the USDA spearheaded previous efforts, today such efforts have largely shifted to Tripartite Standards Regimes (TSRs). Using a case study of the Leonardo Academy’s initiative to develop a US sustainable agriculture standard, this paper examines the standards-development process and efforts by agribusiness to influence the process. Specifically, we analyze how politics operate in seemingly “depoliticized” TSRs, and how agribusiness and the USDA use “framing practices” and procedural complaints to influence the standard-development process. We contend that although governance mechanisms are a potentially powerful tool for advocates of alternative agrifood, their efficacy may be constrained by science-based requirements, an agribusiness countermovement, and a captured state.     

Rubisco small subunits of C4 plants,Napier grass and guinea grass confer C4-like catalytic properties on Rubisco in rice

ABSTRACT

Overexpression of Rubisco small subunit (RbcS) of C₄ plant, sorghum (sorghum bicolor) was shown to enhance the catalytic turnover rate (k _cat) of Rubisco in rice (Oryza sativa). In this study, the effects of other Rubisco small subunits of C₄ plants, Napier grass (Pennisetum purpureum) and guinea grass (Megathyrsus maximus) on kinetic properties of Rubisco in rice were studied. The expression levels of Napier grass RbcS (NgRbcS) and guinea grass RbcS (GgRbcS) proteins accounted for 41% and 45% of total RbcS, respectively in homozygous overexpression lines. The k _cat and K _m for CO₂ (Kc) of Rubisco were increased in all transgenic lines. Interestingly, the k _cat was markedly higher in NgRbcS homozygous line, whereas K _c was notably higher in GgRbcS homozygous line. Although its effects depend on species, these results suggest that the introduction of C₄ RbcS are effective approaches to alter the catalytic properties of Rubisco in rice.     

A morphological study off a thyroid carcinoma in a medaka, Oryzias latipes (Temminck & Schlegel)

A large mass protruding beyond the left operculum was found in an adult male medaka, Oryzias latipes (Temminck & Schlegel). Histologically, the mass was mainly composed of thyroid follicles measuring up to 292 μm in diameter. The follicular epithelium consisted of cuboidal or squamous cells. The follicles lacked colloidal material in the lumen. The thyroid tissue infiltrated into the kidney. Electron microscopically, the tumour cells were characterized by dilation and vesiculation of rough endoplasmic reticulum, which extended throughout the cytoplasm, and an irregular outline of the nucleus. Mitotic figures and partly degenerate cells were frequently observed. Based on the above features, the tumour was diagnosed as a follicular carcinoma of the thyroid, the first reported case in the medaka.     

Possible application of mibolerone for induced sex inversion of grouper Epinephelus coioides

SUMMARY: Thirty immature juvenile grouper Epinephelus coioides (19–168 g bodyweight, BW) were randomly stocked in four units 6 t tanks to determine if mibolerone can be used to induce sex inversion in groupers. After acclimatization and weaning to artificial feed, the feed given daily (4% BW/day) was supplemented with 0, 50, 100, and 200 μg mibolerone/kg feed for about 18 weeks. Thereafter, the hormone treatment was withdrawn and the experiment was terminated at Week 24. Ten fish were killed for gonad histology at stocking to serve as an initial control while about three to five fish were killed every 8 weeks. In general, ovaries of initial controls showed the presence of moderate stromal cells and gonia and few primary oocytes. At Weeks 8 and 16, ovaries of the control fish (0 μg/kg) were similar to that of the initial control except that primary oocytes increased at Week 24. Gonads of fish fed diets containing 100 and 200 μg/kg had none to moderate spermatocytes and few spermatids at Week 8 and 16, although spermatozoa were not observed, indicating that the fish were undergoing spermatogenesis. Spermatogenesis at 50 μg/kg was not as advanced since only few spermatocytes occurred at Weeks 8 followed by moderate gonia and no spermatocytes and spermatids at Week 16. However, the presence of few primary oocytes was observed when mibolerone was withdrawn suggesting that sex-inversed fish reverted back to a female condition. These results show that sex inversion in juvenile grouper can be induced by oral administration of mibolerone and may have possible application on mature females to produce functional males.