Some properties of shikimate: NADP oxidoreductase produced in sweet potato root tissue after slicing

The activity of shikimate: NADP oxidoreductase [EC 1. 1. 1.25] in sweet potato root tissue increased soon after slicing.Enzyme preparations obtained from both sliced tissue and fromfresh tissue probably contained a single enzyme component, andthey showed identical chromatographical behaviour. K_m values of the enzyme for NADP and shikimate were 1.0x10^–4Mand 1.3 x 10^–3M, respectively. Enzyme activity was potentlyinhibited by SH-inhibitors such as p-chloromercuribenzoate andoxidized glutathione. Enzyme activity was affected neither by mononucleotides suchas ATP, ADP and AMP, divalent cations, Mg⁺⁺, Ca⁺⁺ and Mn⁺⁺,nor by metabolites such as tryptophan, phenylalanine, tyrosineand t-cinnamic acid which are involved in aromatic compoundsyntheses. The enzyme rapidly lost its activity. This inactivation reactionshowed a time course consisting of two steps of the first-orderreaction. The inactivated enzyme preparation was not reactivatedby thiol compounds such as cysteine, 2-mercaptoethanol and glutathione,although these reagents, to a certain extent, protected theenzyme from inactivation. The results suggest that denaturationof the enzyme protein was involved in inactivation of the enzyme. ¹Part 74 of the phytopathological chemistry of sweet potatowith black rot and injury. ²Present address: Department of Biology, Faculty of Science,Tokyo Metropolitan University, Setagaya-ku, Tokyo. (Received August 5, 1968; )     

INTRACELLULAR LOCALIZATION OF NATIVE AUXIN IN AVENA COLEOPTILE

Intracellular localization of the native auxin in the Avenacole-optile tip was investigated by separating cellular fractionsby differential centrifugation. Each fraction was extractedwith ether and the auxin activity was measured by the sensitizedAvena curvature test. After the removal of the native free auxin,each fraction was alkaline-hydrolyied, and from these hydrolyzatesthe bound auxin was extracted with ether and its activity wasmeasured. Both the native free auxin and the native bound auxinin these extracts were identified as IAA by paper chromatography.The results show that the native free auxin occurs only in thesupernatant soluble cytoplasm, and that the native bound auxinlocalizes also in the supernatant. The distribution of the externallyapplied IAA was also investigated. (Received February 27, 1962; )     

The Prosencephalon Has the Capacity to Differentiate into the Optic Tectum: Analysis by Chick-Specific Monoclonal Antibodies in Quail-Chick-Chimeric Brains

The alar plate of the prosencephalon of the quail embryo was heterotopically transplanted into the alar plate of the mesencephalon of the chick embryo at the 7–10 somite stage. Chick and quail cells in chimeric brains were distinguished after Feulgen-Rossenbeck staining and/or immunohistochemical staining with a species specific monoclonal antibody MAb-37F5 which recognized cytoplasmic components of chick brain cells. Neural connections between the transplant and the host were studied by monoclonal antibodies, MAb39-B11, which recognizes a species specific antigen on chick nerve fibers, and MAb-29B8, which reacts to 160 kD neurofilaments of both chick and quail.
When the transplant was completely integrated into the host mesencephalon, the transplant developed a laminar morphology closely resembling that of the optic tectum. Immunohistochemical staining with MAb-39B11 showed that the host optic nerve fibers innervated both the host tectum and the tectum-like transplant. However, optic nerve fibers did not invade transplants that failed to develope a laminar structure characteristic of the tectum. These findings suggest that the prosencephalon has a capacity to differentiate into the optic tectum at the 7–10 somite stage.     

Herbivory in canopy gaps created by a typhoon varies by understory plant leaf phenology

1. Availabilities of light and soil nitrogen for understory plants vary by extent of canopy gap formation through typhoon disturbance. We predicted that variation in resource availability and herbivore abundance in canopy gaps would affect herbivory through variation in leaf traits among plant species. We studied six understory species that expand their leaves before or after canopy closure in deciduous forests. We measured the availabilities of light, soil nitrogen, soil water content, and herbivore abundance in 20 canopy gaps (28.3–607.6 m²) formed by a typhoon and in four undisturbed stands. We also measured leaf traits and herbivory on understory plants. 2. The availabilities of light and soil nitrogen increased with increasing gap size. However, soil water content did not. The abundance of herbivorous insects (such as Lepidoptera and Orthoptera) increased with increasing gap size. 3. Concentrations of condensed tannins, total phenolics, and nitrogen in leaves and the leaf mass per area increased in late leaf expansion species with increasing gap size, whereas none of the leaf traits varied by gap size in early leaf expansion species. 4. Herbivory increased on early leaf expansion species with increasing gap size, but decreased on late leaf expansion species. In these late leaf expansion species, total phenolics and C : N ratio had negative relationships with herbivory. 5. These results suggested that after typhoon disturbance, increased herbivory on early leaf expansion species can be explained by increased herbivore abundance, whereas decreased herbivory on late leaf expansion species can be explained by variation in leaf traits.     

Native primary parasitoids and hyperparasitoids attacking an invasive aphid Uroleucon nigrotuberculatum in Japan

Since the invasion of Uroleucon nigrotuberculatum from North America we searched for parasitoids of this aphid on Solidago altissima in Japan to determine what species of native parasitoids attack the newly invasive aphid. We found three primary parasitoid species: Ephedrus plagiator and Praon yomenae (Braconidae, Aphidiinae) and Aphelinus albipodus (Aphelinidae). We also found eight hyperparasitoid species: Syrphophagus sp. (Encyrtidae), Dendrocerus carpenteri (Megaspilidae), Asaphes suspensus (Pteromalidae) and Pachyneuron aphidis (Pteromalidae) through both E. plagiator and A. albipodus; Phaenoglyphis villosa (Figitidae, Charipinae), Aprostocetus sp. (Eulophidae, Tetrastichinae) and D. laticeps through E. plagiator, and Alloxysta sp. nr brevis (Figitidae, Charipinae) through A. albipodus. Uroleucon nigrotuberculatum is usually attacked by rather polyphagous primary parasitoids, E. plagiator and A. albipodus, in Japan, where an oligophagous parasitoid specialized to allied aphid species is probably absent. The hyperparasitoid community of U. nigrotuberculatum is common to those of the aphids occurring in open field‐type habitats in Japan.     

Foraging ecology of a local wild bee community in an abandoned Satoyama system in Kanazawa, Central Japan

Satoyama is a traditional land management system in Japan that emphasizes the importance of a harmonious relationship between humans and their environment. It has been in a state of abandonment and destruction since the late 1960s. In 2000, the Japanese government initiated a new environment policy encouraging the use of Satoyama in biodiversity reservation areas. Before the initiation of active restoration works, an assessment of the potential of the Satoyama system is needed. To assess this potential, a study that focused on the foraging ecology of wild bees in a small abandoned Satoyama terraced paddy was carried out from June to October 2003. A total of 372 foraging bees belonging to 35 species in nine families was collected: two species of social bee ( Apis cerana and Bombus diversus ) and two of solitary bee ( Lasioglossum japonicum and Lasioglossum ohei ) dominated. The foraging activities of wild bees were highly influenced by the requirement of food for the colony and the active time of solitary bees. In the study, most wild bees showed a strong preference for abundant flowering plant species that produced a large number of flowers ( Achyranthes japonica and Polygonum thunbergii ). The results showed that an abandoned Satoyama system was an agricultural system that benefited pollinating bees. Careful and planned restoration practices to increase the diversity of foraging resources, microenvironment diversity and potential nesting areas for wild bees are needed to improve the ability of the Satoyama system to support more diverse and abundant wild bee populations.     

Weak parasitoid-mediated apparent competition between two Phyllonorycter (Lepidoptera: Gracillariidae) leaf miner species on a deciduous oak Quercus dentata

Parasitoid assemblages and the rates of parasitism on tissue-feeding larvae of two Phyllonorycter leaf miner species, P. persimilis and P. leucocorona , were studied from the autumn generation in 2002 to the summer generation in 2005 to understand whether parasitoids mediate interactions between the two leaf miner species. Fourteen species of parasitoids emerged from P. persimilis and 11 emerged from P. leucocorona . The parasitism rate was high: 24.1–92.6% in P. persimilis and 58.9–81.7% in P. leucocorona . Thus, parasitism was a major mortality factor in the present Phyllonorycter species. The parasitoid composition was distinctly different between the two host species, although most parasitoids were able to parasitize both leaf miner species. The analysis based on the quantitative parasitoid overlap revealed that the present parasitoids could mediate interactions between the present leaf miner species, but their effects would be weak. This is attributable to parasitoid's preferential uses of either of the leaf miners as a host.     

Content of Adenosine Phosphate Compounds in a Long-Day Duckweed, Lemna gibba G3, under Different Light and Nutritional Conditions

The levels of ATP ADP and AMP as well as the energy charge were examined in the long-day duckweed. Lemna gibba G3, under different light and nutritional conditions. ATP and ADP content, but not AMP, decreased slightly when the plant was cultured with a medium depleted of sucrose or was exposed to continuous darkness. The energy charge was not affected either by changes in the light conditions or by the depletion of sucrose from the medium, although increase of fresh weight changed drastically under these conditions. The levels of ADP and AMP and the value of the energy charge remained nearly constant throughout a 1-day period when the plant was exposed to short-day, continuous light and continuous dark. ATP content decreased gradually during the light period of the short day and thereafter remained constant during the dark period. When the plant was exposed to continuous light. ATP content decreased until the 8th hour after beginning of the continuous light, only to recover rapidly to its original level during the phase coinciding with the preceding dark period of the short day. Under continuous dark conditions the ATP content remained constant throughout the day. It was concluded that the diurnal rhythm of physiological activities previously reported cannot be related to the energy charge.     

The earliest stages of adaptation in an experimental plant population: strong selection on QTLS for seed dormancy

Colonizing species may often encounter strong selection during the initial stages of adaptation to novel environments. Such selection is particularly likely to act on traits expressed early in development since early survival is necessary for the expression of adaptive phenotypes later in life. Genetic studies of fitness under field conditions, however, seldom include the earliest developmental stages. Using a new set of recombinant inbred lines, we present a study of the genetic basis of fitness variation in Arabidopsis thaliana in which genotypes, environments, and geographic location were manipulated to study total lifetime fitness, beginning with the seed stage. Large‐effect quantitative trait loci (QTLs) for fitness changed allele frequency and closely approached 90% in some treatments within a single generation. These QTLs colocated with QTLs for germination phenology when seeds were dispersed following a schedule of a typical winter annual, and they were detected in two geographic locations at different latitudes. Epistatically interacting loci affected both fitness and germination in many cases. QTLs for field germination phenology colocated with known QTLs for primary dormancy induction as assessed in laboratory tests, including the candidate genes DOG1 and DOG6. Therefore fitness, germination phenology, and primary dormancy are genetically associated at the level of specific chromosomal regions and candidate loci. Genes associated with the ability to arrest development at early life stages and assess environmental conditions are thereby likely targets of intense natural selection early in the colonization process.