The Regulation of Homopolar Doublets to Singlets in Glaucoma

ABSTRACT. In the ciliate Glaucoma scintillans , the process of transformation of unbalanced homopolar doublets to singlets was investigated. Cells were fixed 1–3 days after inoculation and impregnated with silver according to the Chatton-Lwoff technique. The two oral apparatuses (OAs) approached each other partly due to a loss of ciliary rows in one of the two components (semicells) consisting of a doublet. The contractile vacuole pore (CVP) in the narrow semicell (sc1) was lost at an early stage of regulation, while the position of CVP in the broad semicell (sc2) shifted toward the right after the loss of sc1. The sc1 of 20 row-intervals in breadth was a transition point above which the sc1 was able to persist for awhile, and beneath which it was actively lost. There was no evidence for an independent effect of sc2 on the transformation of doublets to singlets. In cell division, an additional reversed oral primordium (sOP) was formed in unbalanced doublets, usually within a narrow sc1 of 11–20 row-intervals. The position of the sOP was generally 4–6 row-intervals distant from the right side of the oral meridian (OM1) with the cell's left OA. Most of the doublets with an sOP lacked an oral primordium in the OM1. No mature triplet with 2 normal OAs and an abnormal OA was found in these preparations. The pathway of regulation, the movement of the CVP, and the formation of an sOP are discussed.     

CHANGES IN ACTIVITY OF DGLUCOSE-6-PHOSPHATE: NADP AND 6-PHOSPHO-D-GLUCONATE: NADP OXIDOREDUCTASES IN RELATION TO LIGNIFICATION OF BAMBOO

D-Glucose-6-phosphate: NADP oxidoreductase (glucose-6-phosphatedehydrogenase; EC 1.1.1.49 [EC] ) and 6-phospho-D-gluconate: NADPoxidoreductase (6-phosphogluconate dehydrogenase; EC 1.1.1.44 [EC] )were found to be present in immature bamboo. Optimal pHs ofthe glucose-6-phosphate- and 6-phosphogluconate dehydrogenaseswere found to be 8.0 and 8.5, respectively. Both enzymes were demonstrated to be NADP-specific and NADPcould not be replaced by NAD. Fructose-6-phosphate was indirectlyutilized after convrsion to glucose-6-phosphate by glucose-6-phosphateisomerase coexisting in the enzyme preparation. Pattern of enzyme activity and of respiratory breakdown of glucose-1-¹⁴Cand glucose-6-¹⁴C were investigated in connection with lignificationof bamboo and discussed in comparison with sugar metabolismof fungi-infected plant tissues. As for the changes in the enzymeactivity with growth of bamboo, it was recognized that therewas a tendency that the activity of both enzymes increased andwas maintained at a certain level even in the aged tissues.In addition there was a drop of the C₆/C₁ ratio toward the tissuesof lower parts containing considerable amount of lignin andthis phenomenon was the same as that observed in pentose phosphatemetabolism of fungi-infected plant tissues. (Received September 5, 1966; )     

Pattern Formation in Mirror-Image Doublets of the Ciliate Stylonychia pustulata

ABSTRACT. Mirror-image symmetry doublets of the ciliate Stylonychia pustulata were obtained from the progenies of dividing cells in which cell division was inhibited by heat-shocks. In two components consisting of the doublet, the left (cell's) component possessed ciliary organelles arranged in almost the same pattern as in normal singlets, while the right one had surface organelles located in a mirror-image symmetry of those of the left component. In cell division of the doublet, two sets of ciliary primordia that were arranged in a mirror-image symmetry developed synchronously in both components. In about 80% of oral primordia (OP) of the right components, the arrangement of the membranellar bands became abnormal. In some cases, OP of the right component were occasionally separated into two longitudinal halves, each consisting of normal membranelles and inverted membranelles. A set of primordia of the paroral membranelles and fronto-ventro-transverse cirri was rarely derived from the basal bodies of the right half with a band of normal membranelles. As a result, a third component with the ciliary organelles normally arranged emerged on the right side of the original right component. The differentiation of membranelles and segmentation of the primordial streaks into cim proceeded from anterior to posterior. A cytoplasmic bulge with multiple right marginal cirral rows was frequently formed at the right margin of the doublet. The behavior in the separation of third and fourth streaks from a primordial streak of dorsal cirri was not mirror-image symmetrical in each component.     

CHANGES IN ACTIVITY OF SHIKIMATE : NADP OXIDOREDUCTASE IN RELATION TO LIGNIFICATION OF BAMBOO

Shikimate : NADP oxidoreductase (5-dehydroshikimate reductase;EC 1.1.1.25 [EC] ) was extracted from immature bamboo and partiallypurified. The optimal pH of the enzyme was found to be 11.0.The enzyme was demonstrated to be NADP specific. Michaelis constants (Km) for NADP and shikimic acid as substratewere found to be 1.4 10^–4M and 2.0 10^–4M, respectively,at pH 8.0. No metal requirement could be demonstrated sincelittle change in enzyme activity was observed on addition ofethylenediamine-tetraacetic acid (EDTA). On the other hand,the enzyme was potently inhibited by p-chloromercuribenzoicacid (PCMB). 5-Dehydroshikimate reductase was demonstrated to be widely distributedin woody plants such as bamboo, udo (Aralia cordata), asparagus(Asparagus officinalis) and tulip tree (Liriodendron tulipifera)as well as other higher plants. Shikimic acid content was comparatively low at the top, butafter reaching maximal content in the part just below the top,it began to decrease toward lower parts of bamboo. The enzymeactivity at the top was the highest and seemed to decrease towardthe tissues of lower parts. However the fact that the activitywas still maintained at a certain level even in the aged tissuessuggests that 5-dehydroshikimate reductase might play a significantrole for biosynthesis of lignin. (Received September 5, 1966; )     

Fish species richness in spring‐fed ponds: effects of habitat size versus isolation in temporally variable environments

1. Species richness in a habitat patch is determined by immigration (regional) and extinction (local) processes, and understanding their relative importance is crucial for conservation of biodiversity. In this study, we applied the Island Biogeography concept to spring ponds connected to a river in southwestern Japan to examine how immigration and extinction processes interact to determine fish species richness in temporally variable environments. 2. Fish censuses were conducted 15 times in 13 study ponds at 1–4 month intervals from August 1998 through October 2000. Effects of habitat size (pond area), isolation (distance from the river) and temporal environmental variability (water level fluctuation) on (i) species richness, (ii) immigration and extinction rates and (iii) population size and persistence of each fish species were assessed. 3. The results revealed predominant effects of distance on species richness, immigration/extinction rates and population size and persistence. Species richness decreased with increasing distance but was not related to either pond area or water level fluctuation. A negative effect of distance on immigration rate was detected, while neither pond area nor water level fluctuation had significant effects on extinction rate. Further, population size and persistence of four species increased with decreasing distance, suggesting that, in ponds close to the river, immigrants from the river reduce the probability of extinction (i.e. provide a rescue effect), contributing to the maintenance of high species richness. 4. Overall results emphasise the importance of immigration processes, rather than extinction, in shaping patterns of species richness in our system. The predominant importance of immigration was probably because of (i) high temporal variability that negates habitat‐size effects and (ii) continuous immigration that easily compensates for local extinctions. Our results suggest that consideration of regional factors (e.g. connectivity, locations of source populations and barriers to colonisation) is crucial for conservation and restoration of local habitats.     

Molecular evidence for phytosiderophore‐induced improvement of iron nutrition of peanut intercropped with maize in calcareous soil

Peanut/maize intercropping is a sustainable and effective agroecosystem that evidently enhances the Fe nutrition of peanuts in calcareous soils. So far, the mechanism involved in this process has not been elucidated. In this study, we unravel the effects of phytosiderophores in improving Fe nutrition of intercropped peanuts in peanut/maize intercropping. The maize ys3 mutant, which cannot release phytosiderophores, did not improve Fe nutrition of peanut, whereas the maize ys1 mutant, which can release phytosiderophores, prevented Fe deficiency, indicating an important role of phytosiderophores in improving the Fe nutrition of intercropped peanut. Hydroponic experiments were performed to simplify the intercropping system, which revealed that phytosiderophores released by Fe‐deficient wheat promoted Fe acquisition in nearby peanuts and thus improved their Fe nutrition. Moreover, the phytosiderophore deoxymugineic acid (DMA) was detected in the roots of intercropped peanuts. The yellow stripe1‐like (YSL) family of genes, which are homologous to maize yellow stripe 1 (ZmYS1), were identified in peanut roots. Further characterization indicated that among five AhYSL genes, AhYSL1, which was localized in the epidermis of peanut roots, transported Fe(III)–DMA. These results imply that in alkaline soil, Fe(III)–DMA dissolved by maize might be absorbed directly by neighbouring peanuts in the peanut/maize intercropping system.     

Transmission and Scanning Electron Microscopic Studies of the Micronemata of Trypanosoma gambiense1

The structure of micronemata arising from the surface of the bloodstream form of Trypanosoma gambiense was studied by electron microscopy. In order to produce micronemata, trypanosomes were incubated in either 1) phosphate buffered saline supplemented with glucose (PBSG), 2) immune mouse serum or 3) PBSG after passage through a DEAE-cellulose column. Electron microscopic examination of the parasite revealed the presence of thread-like micronemata arising from the anterior end and from the flagellar pocket regardless of the incubation conditions. Negative staining revealed a distinct peripheral fringe layer with nodular protrusions covering the entire surface of the micronema. The distribution and number of intramembrane particles (IMP) on the P and E faces of the micronema were similar to those of the flagellum of T. gambiense, indicating a close relationship between the membrane structure of the micronema and the flagellum. Micronemata became fragmented and adhered to each other after incubation of the parasite in the media for 12 h. Since micronemata tend to have the characteristics of adhesiveness and fragmentation, fragments of these structures might adhere to various host organs. Dispersal of potential antigenic material might be responsible, in part, for the induction of the host immune response.     

Reproducing Singlets with an Inverted Oral Apparatus in Glaucoma scintillans (Ciliophora,Hymenostomatida)1

A fragment with only an abnormal oral apparatus (OA) was obtained by operation from a doublet of Glaucoma scintillans possessing one normal and one abnormal OA. This singlet could reproduce and produced a cell line. Singlets frequently possessed an inverted OA, whose antero-posterior axis was rotated 180°. This inversion of the OA has been perpetuated through a considerable number of generations. Oral replacement commonly occurred in singlets with an abnormal OA regardless of growth phases of a culture. The position of the contractile vacuole pore, the direction of curvature of ciliary rows surrounding the OA, and the organization of postoral ciliary rows were mirror-images of those of a normal singlet.