RBEs of Thermal Neutron Capture Therapy and 10B(n,α)7 Li Reaction on Melanoma-Bearing Hamsters

Using Greene's melanoma transplanted into Syrian (golden) hamsters, we determined the relative biological effectiveness (RBE) of thermal neutron capture therapy (TNCT) using ¹⁰B-paraboronophenylalanine (¹⁰B-BPA) in comparison with a 9-MeV electron beam. We also obtained the RBE of the ¹⁰B(n,α)⁷Li reaction by calculation based on summed dose data from TNCT. Throughout this study, the Kyoto University Research Reactor was used as the source for thermal neutrons; the reactor was specially altered to attain a low contamination level both for gamma-rays and fast neutrons. ¹⁰B-BPA was administered 8 hours before thermal neutron irradiation to the hamsters with melanoma. The tumor was then irradiated at 5 MW for 90 minutes. The absorbed dose from this TNCT was calculated by the method of Fairchild and Goodman (Phys. Med. Biol. 1966; 2:15–30). The RBEs of the TNCT and the ¹⁰B(n,α)⁷Li reaction obtained by the tumor growth delay time (TGDT) method were 2.22 and 2.51, respectively, at 10.5 days of TGDT. These RBE values varied with TGDT and the absorbed dose. The RBE value of TNCT had a peak at 7.0 days of TGDT; that of the ¹⁰B(n,α)⁷Li reaction was higher at a low absorbed dose level and lower at a high absorbed dose level.     

Chromosome evolution in Himalayan Impatiens (Balsaminaceae)

AKIYAMA, S., WAKABAYASHI, M. & OHBA, H., 1992. Chromosome evolution in Himalayan Impatiens (Balsaminaceae). Chromosome numbers and karyotypes have been investigated in species of Himalayan Impatiens . In addition to confirming previous chromosome counts, the presence of a tetraploid taxon ( I. exilis) is revealed. In central and east Nepal species with x = 9 are more common than those with other basic numbers and this number is shown to be one of the most frequent numbers in the genus. Most species with x = 9 have a bimodal karyotype. The species relationships are discussed.     

The robustness of geometric morphometrics in testing the morphological equivalence hypothesis among cichlid species from East African Great Lakes

As part of an ongoing broader investigation into whether similar morphologies among cichlid species from East African Great Lakes are due to common ancestry or convergent evolution, we used geometric morphometrics to quantitatively test the hyphothesis that Lake Tanganyika's Tropheus spp. is morphologically similar to Lake Malawi's Pseudotropheus spp. and Labeotropheus fuelleborni . Landmark-based techniques were used to investigate body shape variation and the results revealed highly significant differences among these genera with the exception of L. fuelleborni vs. Pseudotropheus ( Tropheops ) spp. An ordination of all specimens along the first two canonical variate (CV) axes indicated clear interlake separation, especially along the CV I axis, whereby Tropheus moori showed a dorsoventral expansion of the mid body section with a steeper forehead relative to Lake Malawi species. Pseudotropheus ( Maylandia ) zebra was discriminated from the rest primarily on the basis of its terminally positioned gape, which differed from the inferior subterminal gape that was prevalent in the other species. Thus, the present study reveals a pattern of parallel evolution between L. fuelleborni and Pseudotropheus ( Tropheops ) spp., but does not support an interlake convergent evolution hypothesis. Contrary to previous researchers' assertions, these results emphasize the robustness of geometric morphometrics when testing morphological equivalence hypothesis among cichlid species.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 1–9.     

Larvicidal toxicity of Japanese Bacillus thuringiensis against the mosquito Anopheles stephensi

Japanese isolates of Bacillus thuringiensis were screened for larvicidal activity against the mosquito Anopheles stephensi , the urban malaria vector of the Indian subcontinent. Among more than 30 strains identified, larvicidal activity causing >80% mortality in 72 h was demonstrated for 41/1449 (2.8%) isolates. The majority of strains and isolates (97.2%) exhibited little or no larvicidal activity. Anopheles -active strains belonged to more than 12 H serotypes, especially H3ade (serovar fukuokaensis ) and H44 (serovar higo ). SDS-PAGE profiles of inclusion proteins showed 4 distinct types among 6 active strains examined. The most active Japanese isolates were H20 strain 89-T-34-14 (LC₅₀ 4.4 μg/ml) and H44 serovar higo strain 74-E-45-24 (LC₅₀ 7.6 μg/ml), respectively, 13-fold and 23-fold less active than the international standard H14 serovar israelensis (LC₅₀ 0.33 μg/ml).     

Relationship between Floret Elongation and Pigment Synthesis in the Flowers of Carthamus tinctorius

Floret elongation and levels of precarthamin were investigatedin freshly collected flowers of Carthamus tinctorius. Accumulationof precarthamin was found to be induced at the early stagesof floret elongation. [U-¹⁴C]Acetate and [U-¹⁴C]phenylalaninewere incorporated into precarthamin in the detached floretsfrom the flower bud. The results suggest that precarthamin issynthesized via the acetate-shikimate pathway. Carthamus tinctorius L, floret elongation, pigment synthesis, precarthamin     

PHYTOCHROME ACTION IN ORYZA SATIVA L. III. THE SEPARATION OF PHOTOPERCEPTIVE SITE AND GROWING ZONE IN COLEOPTILES, AND AUXIN TRANSPORT AS EFFECTOR SYSTEM

• 1 In 4-day-old etiolated rice seedlings, 3 mm of the coleoptile tip did mainly perceive the photostimulus to cause the phytochrome-dependent inhibition of coleoptile elongation. At this age, cell elongation occurred most in the middle portion of coleoptiles in the dark, and was reversibly controlled by a brief exposure of the tip to red and far-red light. Thus, the photoperceptive site was evidently separated from the growing zone in intact rice coleoptiles.
• 2 The red-light-induced inhibition of coleoptile elongation was nullified by the removal of tip followed by the exogenous application of IAA. The sensitivity of thus treated coleoptiles to IAA was gradually lost during intervening darkness between the irradiation and the decapitation, and a 50% loss was obtained at ca. 6th hour at 26°C.
• 3 Polar auxin transport from coleoptile tips was remarkably prevented at the period between, at least, 2nd and 4th hour after red irradiation, and it recovered to the level of dark control by the 6th hour. Far-red light given immediately after red irradiation reversed the yield of diffusible auxin up to that of far-red control.

     

Modelling the effects of dams on freshwater fish distributions in Hokkaido, Japan

1. We examined the effects of habitat fragmentation caused by dams on freshwater fish species using a database of 7848 fish presence/absence surveys, conducted between 1953–2003 in Hokkaido, Japan. 2. A series of generalised linear models showed that for 11 of 41 taxa examined, the probability of occurrence had been influenced either negatively (eight taxa) or positively (three taxa) by the presence of a dam downstream from their habitat. 3. Maps of modelled predictions revealed that dams had had widespread negative impacts on certain taxa, while for other taxa the impact was limited to specific basins. Two of the three taxa whose probability of occurrence was increased in areas above dams have long been transplanted into reservoirs in Japan. 4. For four of the eight taxa whose probability of occurrence was reduced above dams and all three taxa whose probability of occurrence increased above dams, the temporal length of habitat isolation (i.e. the number of years between dam construction and sampling) was also a significant predictor of the probability of occurrence. This pattern indicates that these taxa experienced a gradual rather than an instantaneous population impact as a result of dam construction. 5. The eight taxa whose probability of occurrence was reduced as a consequence of dams all exhibit migratory life cycles. Although migratory taxa are probably more susceptible to the negative effect of dams, we could not detect significant relationships between migration life histories and the effect of fragmentation by dams. 6. These analyses enable stream and fisheries managers to quantify the impacts of habitat fragmentation because of dams for individual species. The spatially explicit nature of our analyses also enables identification of the areas of the impact at broad geographical scales. Using our results, managers can take effective conservation and restoration measures to predict, mitigate or remove the impact of dams. For example, our results can be used to prioritise dams for removal or to predict losses of biodiversity and ecosystem services in advance of dam construction.     

Spatial heterogeneity of trophic pathways in the invertebrate community of a temperate bog

Summary 1. To examine spatial heterogeneity of trophic pathways on a small scale (<5 m diameter), we conducted dual stable isotope (δ¹³C and δ¹⁵N) analyses of invertebrate communities and their potential food sources in three patchy habitats [sphagnum lawn (SL), vascular‐plant carpet (VC) and sphagnum carpet] within a temperate bog (Mizorogaike Pond, Kyoto, Japan). 2. In total, 19 invertebrate taxa were collected from the three habitats, most of which were stenotopic, i.e. collected from a single habitat. Amongst the habitats, significant variation was observed in the isotopic signatures of dominant plant tissues and their detrital matter [benthic particulate organic matter (BPOM)], both of which were potential organic food sources for invertebrates. Site‐specific isotopic variation amongst detritivores was found in δ¹³C but not in δ¹⁵N, reflecting site‐specificity in the isotopic signatures of basal foods. The eurytopic hydrophilid beetle Helochares striatus was found in all habitats, but showed clear site variation in its isotopic signatures, suggesting that it strongly relies on foods within its own habitat. 3. The most promising potential foods for detritivores were the dead leaf stalks of a dominant plant in the VC and BPOM in the SL and carpet. An isotopic mixing model (IsoSource version 1.3.1) estimated that aquatic predators rely on unknown trophic sources with higher δ¹³C than detritus, whereas terrestrial predators forage on allochthonous as well as autochthonous prey, suggesting that the latter predators might play key roles in coupling between habitats. 4. Our stable isotope approach revealed that immobile detritivores are confined to their small patchy habitats but that heterogeneous trophic pathways can be coupled by mobile predators, stressing the importance of habitat heterogeneity and predator coupling in characterising food webs in bog ecosystems.