On the Encystment of Leptomonas sp. (Kinetoplastida: Trypanosomatidae), a Parasite of the Silkworm, Bombyx mori Linnaeus

SYNOPSIS. Promastigotes of Leptomonas sp., a flagellate parasite of the silkworm, Bombyx mori , multiplied by binary fission with the following sequence of events: duplication of the flagellum; division of the kinetoplast and the nucleus; spatial separation of the kinetoplast: and cytokinesis resulting in the formation of 2 daughter promastigotes. In the early stages of encystment, promastigotes aggregated in a rosette and assumed a stumpy form. The nucleus and kinetoplast of the stumpy promastigotes were double, suggesting a possibility of fusion of the organism in the rosette. When most of the promastigotes in the cluster became stumpy, each individual was isolated from the cluster and acquired a thick coat with an acidophilic substance, thus forming a cyst.     

PHOTOCHEMICAL INTERCONVERSION BETWEEN PRECURSORS OF PHYCOBILIN CHROMOPROTEIDS IN TOLYPOTHRIX TENUIS

1. The photochemical conversion between the precursors of phycocyaninand phycoerythrin in Tolypothrix tenuis was investigated.
2. Itwas found that the conversion of phycocyanin-precursor intophycoerythrin-precursor was induced by green light, and thereverse reaction by red light. These reactions proceeded exponentially, indicating that the photochemical process was acceleratedautocatalytically by the reaction-product.
3. The rates of thesephotochemical reactions were found to beunaltered by varyingthe incubation temperature (0? to 35?)and the composition ofthe gas atmosphere (presence or absenceof CO₂ and of O₂ orby an inhibitor of photosynthesis, p-chlorophenyldimethylurea.
4. The action spectra of the photochemical interconversions betweenprecursors of phycobilin chromoproteids were found to be distinctlydifferent from the absorption spectra of chlorophyll and carotenoids.The most effective wavelength for inducing the conversion ofphycocyanin- into phycoerythrin-precursor (541 mµ) isnear the absorption maximum of phycoerythrin (565 mµ),and that of the reverse reaction (641 mµ) is near theabsorption maximum of phycocyanin (620 mµ). Additionaldata, indicating that the phycobilin chromoproteids themselvesdo not participate in these processes as light absorber, werealso presented.
5. On the basis of these results, a possiblemechanism of the photochemicalinterconversion between the precursorsof phycobilin chromoproteidsis proposed.

(Received March 13, 1962; )     

FORMATION OF PHYCOERYTHRIN IN PRE-ILLUMINATED CELLS OF TOLYPOTHRIX TENUIS WITH SPECIAL REFERENCE TO NITROGEN METABOLISM

1. The formation, in the dark, of phycoerythrin in the preilluminatedcells of a blue-green alga, Tolypothrix tenuis, was investigatedwith special reference to its nitrogen metabolism.
2. On incubatingthe pre-illuminated algal cells under a darkaerobiccondition,and with nitrate as N-source, the formation of phycoerythrinoccurs after an induction period of about 5 hours. No time-lagis observed in the nitrate-uptake by the organism. Similar resultsare obtained with nitrite, ammonia, urea and arginine as N-sources.
3. The above stated formation of phycoerythrin is suppressedbysubstances such as chloramphenicol and p-fluorophenylalanine,substances known to be potent inhibitors of protein-synthesis.
4. On the basis of these findings, it was inferred that therearetwo consecutive processes involved in the dark-formationofphycoerythrin in the pre-illuminated cells: (i) uptake andconversionof exogenous nitrogen sources into some intermediarynitrogenouscell substances, and (ii) synthesis of the pigment-proteinfromthese substances.

(Received June 27, 1960; )     

EFFECT OF CHROMATIC LIGHTS ON PHYCOBILIN FORMATION IN A BLUE-GREEN ALGA, TOLYPOTHRIX TENUIS

1. The formation of phycobilin pigments in a blue-green alga Tolypothrixtenuis was investigated with special reference to the effectsof preillumination with colored lights.
2. It was discoveredthat the algal cells are capable of formingphycobilin pigmentsin the dark, if they have been previouslyilluminated for severalhours in the presence of CO₂.
3. The color of light applied inthe later period of preillumination(chromatic illumination)was found to affect the ratio of phycoerythrinto phycocyaninformed in the subsequent dark period. A greenlight acceleratesthe dark-formation of phycoerythrin, a redlight that of phycocyanin,and the two lights counteractingwith each other in their effects.
4. These directive effects of the "chromatic illumination" canbe accomplished within a very short period, for instance, in3 minutes if it is preceded by sufficient "preillumination"with an incandescent or day light fluorescent light. The reactionsoccurring during the period of chromatic illumination does notrequire the presence of CO₂ and the aerobic condition.
5. Thealga can be grown heterotrophically when supplied with casaminoacids and glucose. Under such a condition the alga forms phycocyanintogether with chlorophyll and carotenoids, but not phycoerythrin.
6. On the basis of the results obtained, a tentative scheme forthe biosynthesis of phycobilin pigments in the alga was proposed,assuming the light-induced formation of unknown precursors whichare converted into phycocyanin and phycoerythrin in the subsequentdark period.

(Received July 4, 1960; )     

PHOTOCHEMICAL ACTIVITIES OF SONICATED LAMELLAE OF SPINACH CHLOROPLASTS WITH SPECIAL REFERENCE TO THE ACTION OF CRS (CYTOCHROME C REDUCING SUBSTANCE)

The photooxidation of reduced DPIP with NADP and O₂ as finalelectron acceptors was studied with sonicated lamellae of spinachchloroplasts, with special reference to the possible role ofCRS, a newly discovered factor of photochemical system I. Acorrelation between inactivation of NADP-photoreduction anddissolution of CRS was observed on treatment of the lamellaewith various organic solvents. The treatment also suppressedthe O₂-linked photooxidation of reduced DPIP, although the suppressionwas not so marked as in the former reaction. The suppressedphotooxidation of reduced DPIP (with O₂ and NADP as electronacceptors) was partially restored on addition of dyes of negativeredox potential, such as methyl viologen. The experimental resultsindicate that a factor participates in the reactions of photochemicalsystem I, probably functioning as an electron carrier couplingthe photooxidation of P700 with the reduction of ferredoxinor O₂. The finding that the above mentioned activity of thefactor is destroyed by treatments which are effective in solubilizingCRS from the chloroplasts suggests the identity of the factorwith CRS. ¹ Present address: Nomura Research Institute of Technology andEconomics, Kamakura, Kanagawa.     

Studies on the Hill reaction of membrane fragments of blue-green algae I. Stabilizing effect of various media on the 2,6-dichlorophenol indophenol-Hill activity of membrane fragments obtained from Anabaena cylindrica and Anabaena variabilis

The stability of DPIP-Hill activity of membrane fragments fromblue-green algae was investigated in various suspension media.Two blue-green algae, Anabaena cylindrica and A. variabiliswere used. Activities for the DPIP-Hill reaction were stable in the twoalgal preparations only when preparations were suspended ina medium containing high concentrations of carbohydrates orPEG. Required concentrations of carbohydrates or PEG differedgready in die two preparations; 1.5 M sucrose or 20% PEG forA. cylindrica and 0.3 M sucrose or 6% PEG for A. variabiliswere minimal for maintaining full activity in 2 hr incubationat 0°C, respectively. Below these concentrations, activitiesdecreased rapidly. In both preparations, stabilizing effects,on a molar basis, varied in different kinds of solutes. However,a simple relation was found between the effects and water concentrationsof media. In A. cylindrica, a 50% decay in activity occurredin 2 hr incubation at 0°G in a medium with 43.8 M water,and, in A. variabilis, the water concentration was 53.4 M. In media free of carbohydrate or PEG, Mg++ ion had a moderatestabilizing ability. EDTA acted antagonistically to Mg++. Effectiveconcentrations were the same in two preparations. However, inthe medium containing carbohydrate or PEG, their actions wereinsignificant. Results suggest that the molecular organization in membranesnecessary for Hill reaction is easily destroyed under high waterconcentrations, and that added solutes stabilize the activityby reducing water concentrations. (Received February 13, 1971; )     

Ascorbate photo-oxidation by a photochemically active chromoprotein isolated from the blue-green alga Anabaena cylindrica: the effect of monochromatic illumination

Ascorbate photo-oxidation by a photochemically active chromoproteinisolated from the blue-green alga Anabaena cylindrica was studiedunder monochromatic illumination. Results indicate that die chromoprotein consists of at leasttwo pigments, both of which act as light-energy receptors forascorbate photo-oxidation. (Received May 11, 1971; )     

A comparative study on insemination dependency of circadian activity pattern in mosquitoes

Abstract. Two forms of mosquitoes in the Culex pipiens complex, C.p.pallens and C.p.molestus , were compared for the insemination-dependency of entrained female circadian activity in LD 16:8h. When virgin, Pallens is nocturnal and molestus is, in addition, diurnal. Insemination and injection of extracts of the male accessory gland affects virgin activity in that nocturnality is strengthened in both mosquitoes, and the diurnal activity of molestus is depressed. This was so whether the treatments were intra- or interspecific. These findings are compared with those already published for other mosquitoes. A coherent view is proposed that the mosquito, nocturnal/crepuscular, nocturnal and diurnal, or diurnal, has potentially a similar entrained waveform which is affected by insemination in a common way, and by lighting conditions in species specific ways.     

Effects of optic lobe ablation on circadian activity in the mosquito, Culex pipiens pallens

ABSTRACT. Surgical manipulation was used to show that in the mosquito, Culex pipiens pallens , the circadian pacemaker is probably not located in the optic lobes. Mosquitoes deprived of the greater part of their optic lobes still maintained a circadian activity rhythm: in DD with τ= c . 20–23 h, in LL with τ= c . 14–15 h. The operated mosquitoes showed diphasic activity which entrained to LD 16:8 h (at 200 lux), implying the existence of an extraocular photoreceptive pathway.     

COMPARATIVE STUDIES OF PHOTOCHEMICAL OXIDATION-REDUCTION REACTIONS IN LAMELLAR FRAGMENTS OF VARIOUS ALGAE AND SPINACH

The activity of various electron carriers, including DPIP, spinachplastocyanin, mammalian cytochrome c, and Anabaena cytochrome553, as donor in the reaction induced by the photochemical systemI was examined with lamellar fragments of various algae andspinach. Reduced DPIP was an effective electron donor irrespective ofthe organisms, when it was supplied at a high concentration(10^–3 M). Spinach plastocyanin was effective in the reactionswith the lamellae of green algae, Euglena, diatom Phaeodactyrumand red algae Porphyra yezoensis and Porphyra sp. Yamamoto II,whereas it was inactive in the lamellae of blue-green algae.Horse-heart cytochrome c and Anabaena cytochrome 553 were activein the reaction with the lamellae of bluegreen algae. The formercytochrome was also active in the reactions in Porphyridiumand Cyanidium. The cytochromes were less active in the reactionsin which spinach plastocyanin acted as effective electron donor. The data were interpreted as that the photochemical system Iin bluegreen algae differs from that of other photosyntheticorganisms with respect to the properties of the site of theelectron-input. ¹ Present address: Nomura Research Institute for Technologyand Economics, Kamakura, Kanagawa. ² Present address: Ocean Research Institute, University of Tokyo,Nakano, Tokyo.