Action Spectra for Step-Up Photophobic Response in Blepharisma

ABSTRACT The cells of Blepharisma which possess red pigment (blepharismin) show step-up photophobic response (temporal ciliary reversal induced by a sudden increase in light intensity). Bleaching of the cells by cold shock raised a threshold light intensity for the response, Oxidation of red pigment that produced blue pigment did not raise the threshold for the response. The action spectrum for the step-up photophobic response of the cells which possess normal red pigment had peaks at about 580, 540 and 490 nm, a value which coincided with peaks of an absorption spectrum of the red pigment. The absorption spectrum of oxidized pigment (blue pigment) shifted 20 nm toward infrared light. The action spectrum for the response of the cells which possess blue pigment also shifted 20 nm toward infrared light. Results suggest that red pigment might be involved in the step-up photophobic response. Key words. Blepharismin, ciliary reversal, photoreceptors, photoresponse.     

Involvement of 14-nm Filament-Forming Protein and Tubulin in Gametic Pronuclear Behavior during Conjugation in Tetrahymena

We have studied in detail the immunofluorescence localizations of Tetrahymena 14-nm filament-forming protein (49-kDa protein) in relation to tubulin in conjugating wild-type Tetrahymena thermophila (B strain) pairs and in pairs between B strain and star strains with defective micronuclei. The results suggest that germ nuclear behavior during conjugation may involve the following cytoskeletal structures: (1) during meiosis, microtubule structures are involved in micronuclear elongation and meiotic division; (2) at the postmeiotic stage, 49-kDa protein network structures that are formed independently of the existence of pronuclei are involved in the selection and the survival of one of four meiotic products; (3) during the third prezygotic division, gametic pronuclear transfer, and zygote formation, a cytoskeletal structure in which the 49-kDa protein colocalizes with microtubules and which is dependent on the existence of a normal gametic pronucleus is involved in gametic pronuclear behavior, and (4) during the postzygotic divisions, the microtubules are involved in nuclear behavior.     

STRUCTURE AND FORMATION OF THE COLLAR IN CHOANOCYTES OF TETILLA SERICA (LEBWOHL), DEMOSPONGE

There are two types of collar in the choanocytes of adult Tetilla serica : one type is a continuous cytoplasmic tube and the other consists of discontinuous microvilli. The former is found in the small flagellated chamber and is considered to belong to a young choanocyte in the process of differertiation. To confirm this idea, very young choanocytes which are about to differentiate the collar were examined during embryogenesis.
The youngest choanocytes are noticed forming aggregations of small cells in 3-day larvae. Around the flagellum in each choanocyte, there is a depression which will become wider. At first, the collar is observed as a ring of cytoplasm; next this extends outward and becomes thinner, and finally it divides into microvilli. The microvillous collar is formed by the opening of vesicles and fusion of their membranes. These vesicles are considered to be derived from the Golgi complex. The process of collar formation through fusion of vesicles is discussed.     

Isotachophoretic Analysis of Ions in Guard Cells of Vicia faba

Isotachophoretic analysis of ions was performed on guard cells of Vicia faba cv. Ryosai Issun with either open or closed stomata. In guard cells of open stomata, K⁺ and malic acid concentrations were 5–7 and 5–10 times higher, respectively, than in guard cells of closed stomata. The content of citric acid (plus isocitric acid) also increased during stomatal opening, but the increment was smaller than that of malic acid. Sodium ions, phosphoric and glyceric acids were present in low concentrations but did not increase during the opening. Other cations and anions could not be measured because of low concentrations. Malic acid provided 68–79% of the counter anions for the potassium taken up by guard cells during stomatal opening.     

Accumulation of glycinebetaine during cold acclimation and freezing tolerance in leaves of winter and spring barley plants

A study was performed to examine whether or not betaine (glycinebetaine), a compatible solute, is accumulated in response to cold stress and is involved in mechanisms that protect plants from freezing injury. For this purpose, we used near-isogenic lines of barley, with each line differing only in a single gene for the spring type of growth habit; the various lines were produced by back-crosses to a recurrent cultivar of the winter type. The winter type of growth habit requires a low temperature for triggering of flower development (vernalization), whereas the spring type does not. Betaine was accumulated to five times the basal level over the course of 3 weeks at low temperature (5 °C) in the winter-type cultivar and in a spring-sh line having the sh gene for the spring-type growth habit, but the level was only doubled in the spring-Sh3 line, which carried the Sh₃ gene for the spring-type growth habit. Among near-isogenic lines of the same cultivar, the levels of betaine accumulated in leaves at low temperature were well correlated with the percentages (on a dry weight basis) of green leaves that survived freezing injury (-5 °C). This observation indicates the possibility, separate from the recognized role of betaine in the response to salinity and/or drought, that betaine accumulates in response to cold stress and that the accumulation of betaine during cold acclimation is associated to some extent with freezing tolerance in leaves of barley plants.     

Intraspecific competition as a selective pressure on the choice of oviposition site in a phytophagous insect

Our aim was to clarify the factors providing selective pressures on the choice of oviposition sites in phytophagous insects. To this end, we examined the spatial distribution of eggs of the sawfly leaf miner, Profenusa japonica . The study was conducted over five consecutive years on three subpopulations found in riverbeds in central Japan. Profenusa japonica lays eggs on leaflets of Rosa multiflora , and its larvae mine a single leaflet for the entire larval stage. The egg distribution among leaflets was uniform (regular) at all sites examined in each year. The distribution within leaflets was also uniform, and it appeared that females avoided ovipositing on areas of the leaf that already contained eggs. Few parasitoids were found in eggs or larval stages, despite intensive examination. Larval mortality increased, mainly as a result of exploitative competition, when there were two or three larvae per leaflet. Starvation caused by resource competition for leaflet tissues was an important mortality factor. Therefore, we suggest that P. japonica females avoided ovipositing on areas of the leaflet that already contained eggs to prevent exploitative competition among larvae sharing the same leaflet.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 92 , 641–650.     

Development of microsatellite markers for the red tide‐forming harmful species Chattonella antiqua,C. marina,and C. ovata (Raphidophyceae)

We have developed 11 microsatellite markers that are specific to Chattonella antiqua, C. marina, and C. ovata, the red tide‐forming harmful phytoplanktons. The 11 loci were amplified in the three species. The number of alleles per locus ranged from 5 to 16. The three species shared most microsatellite regions, although the genetic differences in specific loci were detected among them. These markers of the Chattonella species will be beneficial for biogeographical, detailed taxonomic, studies.     

饲养条件下非人灵长类的营养需求

非人灵长类的营养学研究越来越受到国际和国内社会的关注。我国是世界上实验灵长类动物的最大产出国。进一步了解和发展非人灵长类营养学将有利于提高我国非人灵长类的饲养水平和饲料资源的利用效率,推动整体产业的发展。为此本文介绍了近年来国际上非人灵长类营养学方面的研究进展和国家饲料配比的相关规定,阐述了各营养成分的作用、缺乏症状和改善案例。旨在丰富相关方面的科学信息,增加对非人灵长类营养
需求的理解。     

Possible Roles of Methyl Glucoside andMyo-inositol in the Opening of Cut Rose Flowers

Methyl glucoside andmyo-inositol are present in all organs ofrose (Rosa hybridaL.). To investigate the possible role of thesecarbohydrates in the opening of cut roses, flowers with a 10,20 or 40-cm-long stem and a single flower bud (about 1.5 cmin diameter) were placed in water and flower opening and changesin sugar content in flowers and stems examined for 7 d. Thelonger the stem of the cut flower, the larger was the flowerdiameter. In stems, the concentration of carbohydrates, includingmethyl glucoside andmyo-inositol markedly decreased before floweropening. In petals, contents of glucose, methyl glucoside andmyo-inositolalso decreased before flower opening, but those of fructose,sucrose and xylose did not. When glucose and methyl glucosidewere added to the vase water (4%) flower opening was clearlypromoted; this was accompanied by an increase in methyl glucosideand fructose concentrations in petals. On the contrary,myo-inositolinhibited flower opening, and this was accompanied by an increaseinmyo-inositol and xylose concentrations in petals. These resultssuggest that methyl glucoside and/or its metabolites are transportedinto the petal cells, thereby lowering the osmotic water potentialand promoting flower opening.Myo-inositol is not readily metabolized,and exogenousmyo-inositol given at a high concentration mayact as an extracellular osmolyte, which inhibits water uptakeand flower opening.Copyright 1999 Annals of Botany Company Cut flowers, methyl glucoside,myo-inositol,Rosa hybrida,soluble carbohydrate.