Studies on plant tissue cultures I. Relationship between inocula sizes and growth of calluses in liquid culture

1. 1. It was observed that lag of growth was longer in small inoculathan in large inocula using tobacco callus in liquid culture.
2. 2. These different growth responses between small and largeinocula were dependent on the ratio of inoculum to culture medium.
3. 3. The same result was obtained in a strain of carrot rootcallus.But the growth lag was very short in the carrot callus,whichwas subcultured for the shortest period among the 4 strainsused, even in small inocula. On the other hand, both small andlarge inocula of the strain, which were subcultured for thelongest period among the 4 strains, did not grow at all duringthe culture period; the longer the period of subculturing, thelonger the lag of growth.
4. 4. The longer lag of small inoculain tobacco callus was recoveredby gibberellin A₃ in the presenceof the acidic fraction ofcarrot root extract or vitamins suchas pyridoxine and thiamine.

(Received December 11, 1967; )     

The morphology and evolution of the ventral gill arch skeleton in batoid fishes (Chondrichthyes: Batoidea)

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.     

Hysteresis of Contraction-Extension Cycle of Glycerinated Vorticella

SYNOPSIS. The helical coiling state of a glycerinated stalk in the family Vorticellidae had been regarded, without any evidence, as a reversible and completely equilibrated mechano-chemical system regulated by the external free Ca²⁺ concentration. Our present detailed observations of many individual stalks of glycerinated Vorticella convallaria revealed that the contraction-extension cycle of the helical stalks caused by increasing and decreasing free Ca²⁺ concentrations in the medium represents a kind of hysteresis. This phenomenon was observed in extensively glycerinated Vorticella in a medium of very low or physiological ionic strength, as well as in briefly glycerinated ciliates. With regard to the configurational change in various parts of a glycerinated stalk during the contraction-extension cycle, it was found that the initial bending of the stalk caused by increasing free Ca²⁺ concentration begins to take place near the zooid (head) while the initial reextension of the stalk with decreasing free Ca²⁺ concentration begins to take place near the zooid (head) while the initial reextension of the stalk with decreasing free Ca²⁺ concentration takes place simultaneously throughout the entire stalk. The Ca²⁺ threshold for complete reextension of the part of the stalk near the rootlet was found to be much higher than that near the zooid.     

外源硅对花期高温胁迫下杂交水稻授粉结实特性的影响

以杂交中熟籼稻品种金优63、汕优63为供试材料,采用盆栽试验,在水稻生长前期连续喷施3次硅酸钠(Na₂SiO₃·9H₂O),于人工气候箱内在水稻开花期进行常温(日均温26.6 ℃,日最高温度29.4 ℃)和高温(日均温33.2 ℃,日最高温度40.1 ℃)处理5 d,研究施硅在花期高温胁迫下对杂交水稻剑叶叶绿素含量、光合性能、抗氧化酶活性、丙二醛(MDA)含量、花粉活力、花药酸性转化酶活性、柱头授粉性能和结实率等的影响.结果表明: 与对照相比,施硅可显著提高高温胁迫下水稻剑叶叶绿素含量,提高净光合速率和气孔导度,减少胞间CO₂浓度,增强叶片光合作用,减少MDA含量,提高超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性;提高花药中可溶性酸性转化酶活性和花粉活力,增加花粉囊基部裂口宽度,提高水稻每柱头上授粉总数、萌发数、花粉萌发率和萌发数大于10粒者所占的比例,降低花粉总数小于20粒者所占的比例;使金优63、汕优63结实率的降低分别减轻13.4%、14.1%.因此,在水稻生长前期喷施外源硅,可减轻水稻在开花期结实率的降低,提高杂交水稻的抗热性.     

STUDIES ON CHLOROPHYLLASE OF CHLORELLA PROTOTHECOIDESI. ENZYMATIC PHYTYLATION OF METHYL CHLOROPHYLLIDE

1. The relation between chlorophyll content and the hydrolyticactivity of chlorophyllase in Chlorella protothecoides was examined.An increase in the activity was parallel to that in chlorophyllcontent during the development of green colouration, or greeningcourse, in the bleached cells. The activity sharply declinedand a parallel disappearance of chlorophyll was also found duringbleaching of the green cells.
2. A partially purified water-solublepreparation of chlorophyllasewas obtained by n-butanol treatmentand fractionation with coldacetone. It showed high activityand hydrolyzed 2 mg chlorophylla per hr per mg protein.
3. Forseparation and identification of the pigments concernedin thechlorophyllase reaction, a new solvent system of paperchromatographywas introduced.
4. When methyl chlorophyllide a and phytol wereincubated withthe enzyme, two products were formed. By comparisonwith theRf values of isolated pure substances, one was identifiedaschorophyll a and the other as chlorophyllide a. This enzymedid not catalyze the phytylation of free chlorophyllide a, butit had the ability to attach phytol to methyl chlorophyllidea. The final step in the biosynthesis of chlorophyll a is brieflydiscussed.

¹ Contribution No. 158 from the Department of Biology, Facultyof Science, Kyushu University. Supported in part by a grant-in-aidfor Fundamental Scientific Research from the Ministry of Education.     

CHANGES IN HYDROGENASE ACTIVITY DURING THE SYNCHRONOUS GROWTH OF SCENEDESMUS OBLIQUUS D3

1. A fairly good synchronization of Scenedesmus cells was obtainedby transferring the cells grown in a medium containing a lowconcentration of iron into a medium containing relatively highconcentration of iron.
2. During the synchronous culture in themineral medium, a goodparallelism between the average cellvolume and hydrogenaseactivity was observed.
3. Effect of glucoseon the development of the hydrogenase activitywas variabledepending on the stage of algal growth.
4. Iron is essentialfor the development of the hydrogenase activityand glucosesupplementary.

¹On leave from Laboratory of Applied Botany, Faculty of Agriculture,Kyoto University, Kyoto.     

Inhibition of Photosystem II in the Green Alga Ankistrodesmus falcatus by Copper

Copper strongly inhibited 2,6-dichloroindophenol (DCIP) photoreduction in the broken cells of the green alga Ankistrodesmus falcatus (C303), and the activity lost could not be restored by adding 1,5-diphenylearbazide (DPC). Inactivation of the DCIP Hill reaction reached 45% after incubation with 10 μM cupric sulfate for 20 min. In the same time, copper (13 μg/mg chlorophyll) was bound to the broken cells. Addition of 10 mM KCl reduced copper binding by about 53%. Fluorescence intensity at room temperature decreased upon addition of cupric sulfate and was partially restored by adding 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), These results suggest that copper inactivates electron transport between the oxidizing side of the reaction center of photosystem II and the electron-donating site of DPC. Further, the effect of light intensity shows that copper mostly affected the reaction rate of the dark step and had less inhibitory effect on the quantum efficiency of the primary reaction of electron transport in photosystem II.     

Extensive genetic divergence in the East Asian natricine snake,Rhabdophis tigrinus (Serpentes: Colubridae), with special reference to prominent geographical differentiation of the mitochondrial cytochrome b gene in Japanese populations

We investigated intraspecific phylogenetic relationships in the natricine snake, Rhabdophis tigrinus. A partial sequence of mitochondrial cytochrome b gene (990 bp) was sequenced for 220 individuals from 112 populations. The phylogeny indicated monophyly of the Japanese populations against the continental and Taiwanese populations, sister relationships of the Japanese and continental populations, and monophyly of the whole species. The results strongly suggested substantial genetic divergences among population assemblages from those three regions. We thus consider both lateralis from the continent, which is often synonymized to R. tigrinus, and formosanus from Taiwan, which is usually regarded as a subspecies of the latter, as distinct full species based on the evolutionary species concept. In the Japanese populations, haplotypes were classified to in two major clades (I and II) that were parapatric to each other. Clade I consisted of three distinct subclades (I‐A, I‐B, and I‐C), of which the former two were parapatric with each other, whereas the latter was sympatric with each of the former two subclades. The geographical haplotype structure exhibited by the Japanese populations is likely to have resulted from a series of allopatric differentiations with rapid range extensions of resultant lineages, leading to secondary contact or further admixture of mitochondrial haplotype clades and subclades. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 395–408.     

NIRF对P53蛋白泛素化作用的研究

HEK293和HeLa细胞分别被Np95/ICBP90-likeRINGfingerprotein(NIRF)和P53转染后,细胞上清和免疫沉淀产物用SDS-聚丙烯酰胺凝胶电泳免疫印迹法分析;细菌合成GST-P53后,用GSTpull-down技术检测NIRF与P53相互作用;在GST-P53、E1、E2和NIRF体外泛素化反应系统中,检测NIRF对P53的体外泛素化.结果表明:NIRF能与P53相互作用,NIRF不仅能与P53特异性结合,而且还会将P53泛素化,这种相互作用在细胞内和细胞外均能发生.推测NIRF可能是P53的一个新的负调节蛋白.     

Accessibility of Calcium Ions to Anionic Sites of Lipid Monolayers

ALTHOUGH the calcium ion is believed to play a functional role in various membrane phenomena such as nervous excitation, muscular contraction and cell permeation by interacting with the reactive sites of the membrane, little is known about the binding characteristics of calcium with the anionic sites of the well specified lipid membrane^1,2.