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121.
The i locus of the medaka fish, Oryzias latipes, is responsible for tyrosinase expression, and several mutant alleles have been identified. The genotype i1/i1 exhibits a complete albino phenotype, having pale orange-red skin and red eyes. This mutant lacks in vivo tyrosinase activity. The genotype i4/i4, on the other hand, shows a quasi-albino phenotype with skin as bright as that of i1/i1 but with red-wine-colored eyes. At the light microscope level, reduced pigmentation is observed both in the skin and eyes of this mutant. The tyrosinase genes for the i1 and the i4 alleles were cloned and sequenced, and compared with that of the wild-type tyrosinase gene. The i1 allele was found to contain a 1.9-kb transposable element in the 1st exon, and the i4 allele was found to contain a 4.7-kb transposable element in the 5th exon. Both i1 and i4 are alleles that were found in a commercial breeding population. The insertion of a transposable element thus appears to constitute a natural cause of mutations that cause albinism in this organism. 相似文献
122.
Compartmental Analysis of the Partitioning of Photo-assimilated Carbon in Nodulated Soybean Plants during the Light Period 总被引:1,自引:0,他引:1
KOUCHI HIROSHI; YONEYAMA TADAKATSU; AKAO SHOICHIRO 《Journal of experimental botany》1986,37(7):994-1005
Kouchi, H., Yoneyama, T. and Akao, S. 1986. Compartmental analysisof the partitioning of photo-assimilated carbon in nodulatedsoybean plants during the light period.J. exp. Bot. 37:9941005. Dynamics of the partitioning of photo-assimilated carbon invegetative nodulated soybean (Glycine max L.) plants in thelight period was investigated by compartmental analysis basedon data from steady-state 13CO2 assimilation experiments. Themodel assumes a total of 18 compartments consisting of activeand temporary storage pools for soluble materials, starch andstructural materials in leaves, stems plus petioles, roots andnodules together with respired carbon from the roots and nodules.Carbon flow between compartments was described by 22 rate parameters.The rate parameters were evaluated by a non-linear least squaresearch method to optimize the fitness of the simulated resultswith the experimental tracer distribution. The compartment model was well applicable to interpret the carbonpartitioning in whole plants. The analysis showed that: (I)The largest carbon flux during the light period was to storagematerials (starch and temporary storage soluble pools) in theabove-ground parts. The total flux to storage pools was considerablylarger than the transporting flux to below-ground parts. (2)The main carbon flux to the nodules was via direct phloem pathwaysfrom the shoot and not via the compartment of root soluble materials.This flux was 72% of the total carbon flux from the shoot tothe nodulated root system. (3) A large amount of carbon wasreturned to the shoot from below-ground parts. The total returnof carbon flux to the shoot (85% from nodules) was equivalentto 54% of the total influx of carbon to below-ground parts.Direct carbon transfers between roots and nodules were relativelysmall. Key words: Compartmental analysis, carbon partitioning, root nodules, Glycine max L., 13CO2, assimilation 相似文献
123.
ABSTRACT. 1. Daily trap catches of the rice planthoppers, N.lugens Stal and S.furcifera Horvath, and associated synoptic weather patterns were analysed in Kyushu, south-west Japan, in the autumns of 1980–85.
2. Certain weather patterns which seemed to favour overseas immigration, were reflected in trap catches: of eighteen occasions in which back-tracks on 850 mbar wind fields reached central China, marked mass catches in a light trap occurred on six occasions, and peaks in catch curves were found on another seven occasions.
3. These results strongly imply overseas immigration of the planthoppers from China to Kyushu in autumn, identical to invasions by the same species in early summer. However, such autumn migration is apparently non-adaptive because migrants or their progeny are soon killed by cold weather. 相似文献
2. Certain weather patterns which seemed to favour overseas immigration, were reflected in trap catches: of eighteen occasions in which back-tracks on 850 mbar wind fields reached central China, marked mass catches in a light trap occurred on six occasions, and peaks in catch curves were found on another seven occasions.
3. These results strongly imply overseas immigration of the planthoppers from China to Kyushu in autumn, identical to invasions by the same species in early summer. However, such autumn migration is apparently non-adaptive because migrants or their progeny are soon killed by cold weather. 相似文献
124.
TAKEUCHI NORIKAZU; TANIMOTO SHIZUFUMI; HARADA HIROSHI 《Journal of experimental botany》1985,36(5):841-847
In in vitro cultured stem segments of Torenia fournieri Lind.,the formation of adventitious buds can be induced when the culturemedium contains cytokinin. When long stem segments (2.0 cm ormore) were cultured with cytokinin, a large number of buds wereformed in the marginal regions, namely, within the limits of0.5 cm from the cut ends of explants, while only a few budswere initiated in the middle part of the explants. If a slightinjury was made transversely with a scalpel in the central partof an explant, a significant increase in the number of budswas noted within the limits of 0.5 cm from the wound site. Whena wounding treatment was given lengthwise to an explant, a largenumber of adventitious buds were formed over the entire surfaceof the explant compared to the control. Excision itself of explantsfrom mother plants and the additional wounding given to theexplants seemed to trigger the induction of adventitious buddifferentiation in Torenia stem segments. These wounding treatmentsdid not affect the uptake into explants and/or the distributionpattern of radioactive benzyladenine applied to the culturemedium. Key words: Torenia fournieri, Adventitious bud formation, Cytokinin, Wounding 相似文献
125.
HIROSHI INUI OSAMU OHYA YUJI ISEGAWA SHOZABURO KITAOKA KAZUTAKA MIYATAKE YOSHIHISA NAKANO 《The Journal of eukaryotic microbiology》1996,43(3):177-180
Euglena gracilis requires cobalamin (Cbl) as an essential growth factor. Phosphatidylcholine (PC) synthesis was greatly reduced by Cbl deficiency. Rapid cell division occurred after Cbl was replenished, and PC was actively synthesized during the cell divisions. When the deficient cells were given methionine (a precursor for the choline moiety), active synthesis of PC occurred even without the Cbl supplement, although cell division was not induced. As methionine synthase in Euglena requires methylcobalamin as a coenzyme, decrease in methionine synthesis may account for reduced PC synthesis under Cbl-deficient conditions. Phosphatidyleth-anolamine and phosphatidylserine synthesis were also suppressed, commensurate with decrease of PC synthesis, under Cbl deficiency, even though Cbl is not thought to participate in their synthesis. In contrast, a lot of triglyceride and wax ester accumulated in Cbl-deficient cells. Moreover, Cbl depletion altered fatty acid composition, notably due to increased proportion of odd-numbered fatty acids 相似文献
126.
KOJIMA MINEO; MINAMIKAWA TAKAO; HYODO HIROSHI; URITANI IKUZO 《Plant & cell physiology》1969,10(2):471-474
t-Cinnamic acid-2-14C, p-coumaric acid-2-14C and caffeic acid-2-14Cwere administered to discs of sweet potato roots and incorporationof each radioactive compound into chlorogenic acid was compared.The data suggest that chlorogenic acid is synthesized througheither or both of two major pathways, phenylalanine t-cinnamate t-cinnamoyl derivative p-coumaroyl derivative chlorogenicacid and phenylalanine t-cinnamate p-coumarate p-coumaroylderivative chlorogenic acid.
1Part 75 of the phytopathological chemistry of sweet potatowith black rot and injury.
2Present address : Department of Biology, Tokyo MetropolitanUniversity, Setagaya-ku, Tokyo. (Received December 23, 1968; ) 相似文献
127.
HIROSHI IMOH 《Development, growth & differentiation》1984,26(2):167-176
The occurrence of the dorsal yolk-free cytoplasm in the fertilized egg of Xenopus was re-examined, and the appearance and the distribution of RNA-rich cytoplasms in Xenopus embryos during early development were examined with their paraffin sections. The results show that the dorsal yolk-free cytoplasm does not occur solely in the dorsal part of the embryo but is continuous to similar cytoplasmic mass in the central and the ventral part. The whole mass of this continuous cytoplasm is denoted here as the mesoplasm. The locations of the mesoplasm in the embryo can be traced by its high RNA content during cleavage and blastulation. The cells endowed with the mesoplasm constitute a broad band about the equator of the blastula. At the lower edge of this band, the blastopore lip is formed during gastrulation. Another mass of yolk-poor and RNA-rich cytoplasm becomes distinct around every nucleus in the stage 4 embryo and is denoted here as the nucleophilic plasm. This plasm is diminished at every nuclear division and disappears in the stage 10 embryo. Origins and roles of the mesoplasm and the nucleophilic plasm were discussed and a mechanism of blastulation was suggested. 相似文献
128.
Fertilized uncleaved eggs of Xenopus laevis were divided into nucleate and non-nucleate egg fragments. Both fragments, together with the whole egg of the same batch, were observed by time-lapse cinematography.
Two kinds of cyclic surface changes, (1) rounding-up and relaxing movements and (2) surface contraction waves, accompanying each cleavage in the whole eggs and the nucleate fragments, were also observed even in the non-nucleate fragments although they do not cleave.
Cleavage intervals of the whole egg and the nucleate fragment were nearly equal, but the rounding-up intervals of the non-nucleate fragment were slightly but definitely longer than the cleavage intervals of the nucleate fragment and the whole egg. 相似文献
Two kinds of cyclic surface changes, (1) rounding-up and relaxing movements and (2) surface contraction waves, accompanying each cleavage in the whole eggs and the nucleate fragments, were also observed even in the non-nucleate fragments although they do not cleave.
Cleavage intervals of the whole egg and the nucleate fragment were nearly equal, but the rounding-up intervals of the non-nucleate fragment were slightly but definitely longer than the cleavage intervals of the nucleate fragment and the whole egg. 相似文献
129.
The morphology and evolution of the ventral gill arch skeleton in batoid fishes (Chondrichthyes: Batoidea) 总被引:1,自引:0,他引:1
The ventral gill arch skeleton was examined in some representatives of batoid fishes. The homology of the components was elucidated by comparing similarities and differences among the components of the ventral gill arches in chondrichthyans, and attempts were made to justify the homology by giving causal mechanisms of chondrogenesis associated with the ventral gill arch skeleton. The ceratohyal is present in some batoid fishes, and its functional replacement, the pseudohyal, seems incomplete in most groups of batoid fishes, except in stingrays. The medial fusion of the pseudohyal with successive ceratobranchials occurs to varying degrees among stingray groups. The ankylosis between the last two ceratobranchials occurs uniquely in stingrays, and it serves as part of the insertion of the last pair of coracobranchialis muscles. The basihyal is possibly independently lost in electric rays, the stingray genus Urotrygon (except U. daviesi) and pelagic myiiobatoid stingrays. The first hypobranchial is oriented anteriorly or anteromedially, and it varies in shape and size among batoid fishes. It is represented by rami projecting posterolaterally from the basihyal in sawfishes, guitarfishes and skates. It consists of a small piece of cartilage which extends anteromedially from the medial end of the first ccratobranchial in electric rays. It is a large cartilaginous plate in most of stingrays. It is absent in pelagic myliobatoid stingrays. The remaining hypobranchial cartilages also vary in shape and size among batoid fishes. Torpedo and possibly the Jurassic Belemnobalis and Spathobatis possess the generalized or typical chondrichthyan ventral gill arch structure in which the hypobranchials form a Σ-shaped pattern. In the electric ray Hypnos and narkinidid and narcinidid electric rays, the hypobranchial components are oriented longitudinally along the mid-portion of the ventral gill arches. They form a single cartilaginous plate in the narkinidid electric rays, Narcine and Diplobatis. In guitarfishes and skates, the second hypobranchial is unspecialized, and in skates, it does not have a direct contact with the second ceratobranchial. In both groups, the third and fourth hypobranchials are composed of a small cartilage which forms a passage for the afferent branches of the ventral aorta and serve as part of the insertion of the coracobranchialis muscle. In sawfishes and stingrays, the hypobranchials appear to be included in the medial plate. In sawfishes, the second and third components separately chondrify in adults, but the fourth component appears to be fused with the middle medial plate. In stingrays, a large medial plate appears to include the second through to the last hypobranchial and most of the basibranchial copulae. The medial plate probably develops independently in sawfishes and stingrays. Because the last basibranchial copula appears to be a composite of one to two hypobranchials and at least two basibranchial copulae, the medial plate may be formed by several developmental processes of chondrogenesis. More detailed comparative anatomical and developmental studies are needed to unveil morphogenesis and patternings of the ventral gill arch skeleton in batoid fishes. 相似文献
130.
HIROSHI TOBE CHING-I PENG 《Botanical journal of the Linnean Society. Linnean Society of London》1990,103(2):139-152
TOBE, H. & PENG, C.-I, 1990. The embryology and taxonomic relationships of Bretschneidera (Bretschneideraceae). We present the first report on the embryology of Bretschneidera , the only genus of Bretschneideraceae (which are one of 15 glucosinolate-producing families), to clarify its relationships. Embryologically Bretschneidera is characterized by the following features: ovule campylotropous, bitegmic and crassinucellate; outer integument thick, multiplicative and vascularized; embryo sac formation of the Allium type; seed exalbuminous; seed coat 'exotestal' with a palisade of columellar, thick-walled exotestal cells; mesotesta thick with the inner half aerenchymatous. These features suggest that Bretschneidera is distinct from any of the taxonomically related families but resembles both Hippocastanaceae and Sapindaceae (Sapindales) more closely than Moringaceae or Capparaceae (Capparales) which have been considered alternative allies, supporting most of the modern taxonomic treatments that place Bretschneidera as a separate family in Sapindales. 相似文献