Overwintering success in adults of the Japanese common grass yellow Eurema mandarina

The evolution of reproductive diapause is controversial in males as compared to females that must overwinter to leave offspring, because late‐autumn males can obtain offspring by pre‐overwintering copulation. The Japanese common grass yellow Eurema mandarina is suitable to examine the evolution of male reproductive diapause, because direct comparisons are possible between males that do and do not exhibit reproductive diapause. Approximately one‐half of males are insensitive to diapause‐inducing conditions, and emerge as non‐diapause summer‐form. Most autumn‐form females mate with summer‐form males in late autumn. Females that have overwintered re‐mate with autumn‐form males before the onset of oviposition. Because last‐male‐precedence is general in sperm competition in Lepidoptera, it is unclear why half of males emerge as summer‐form in late autumn. A potential adaptive benefit for emerging as summer‐form is increased sperm overwintering success, if autumn‐form females have a higher overwintering success than autumn‐form males. In the present study, overwintering success was estimated for both sexes of autumn‐form adults by rearing under seminatural conditions and a mark–release–recapture technique. Both approaches estimated an overwintering success of approximately 5% for both sexes. The absence of difference in overwintering success between the sexes suggests that pre‐overwintering copulation does not increase sperm overwintering success. However, a considerably low overwintering success may explain, at least partly, the presence of summer‐form males in late autumn. The degree of overwintering success might be more important than the sexual differences of overwintering success in the evolution of male reproductive diapause.     

Mating Triggers Queen Elimination by Workers of Japanese Harvester Ant (<Emphasis Type="Italic">Messor aciculatus</Emphasis>)

During reproduction, ant colonies produce winged queens. These new queens usually leave the nest to mate and can then establish a new nest. If the new nest is close to an existing colony, it will be in competition with the existing colony. Therefore, workers will kill any mated queens they find outside the colony during the reproductive season. In this study, factors that might determine whether workers eliminate queens were investigated. Mating status (mated or unmated), colony origin (same or different to tested workers) and mating partners (inbred or outbred) of the queens of Japanese harvester ants (Messor aciculatus) were manipulated and the workers’ behavior towards the queens was observed. Mated queens were always attacked by workers, though this was not affected by either colony origin or mating partners. These results suggest that mating status triggers elimination of queens by workers, and that the colony origin and mating partner are unlikely to be important roles in elimination of queens.     

Novel reporter and deleter mouse strains generated using VCre/VloxP and SCre/SloxP systems,and their system specificity in mice

DNA site-specific recombination by Cre/loxP is a powerful tool for gene manipulation in experimental animals. VCre/VloxP and SCre/SloxP are novel site-specific recombination systems, consisting of a recombinase and its specific recognition sequences, which function in a manner similar to Cre/loxP. Previous reports using Escherichia coli and Oryzias latipes demonstrated the existence of stringent specificity between each recombinase and its target sites; VCre/VloxP, SCre/SloxP, and Cre/loxP have no cross-reactivity with each other. In this study, we established four novel knock-in (KI) mouse strains in which VloxP-EGFP, SloxP-tdTomato, CAG-VCre, and CAG-SCre genes were inserted into the ROSA26 locus. VloxP-EGFP and SloxP-tdTomato KI mice were reporter mice carrying EGFP or tdTomato genes posterior to the stop codon, which was floxed by VloxP or SloxP fragments, respectively. CAG-VCre and CAG-SCre KI mice carried VCre or SCre genes that were expressed ubiquitously. These two reporter mice were crossed with three different deleter mice, CAG-VCre KI, CAG-SCre KI, and Cre-expressing transgenic mice. Through these matings, we found that VCre/VloxP and SCre/SloxP systems were functional in mice similar to Cre/loxP, and that the recombinases showed tight specificity for their recognition sequences. Our results suggest that these novel recombination systems allow highly sophisticated genome manipulations and will be useful for tracing the fates of multiple cell lineages or elucidating complex spatiotemporal regulations of gene expression.     

Preferential release of newly synthesized [3H]GABA from striatal slices to preloaded [3H]GABA

The release of [³H]GABA which is newly synthesized from [³H]l-glutamic acid (GLU) has been examined using striatal slices obtained from the rat brain. It was found that 8–10% of [³H]GLU transported was converted to [³H]GABA during the incubation of striatal slices in the presence of nipecotic acid (5 × 10^?5 M). Nipecotic acid was added to the medium in order to prevent possible reuptake of [³H]GABA released during its synthesis, and it was found to have no significant effect on the formation of [³H]GABA from [³H]GLU as well as on the uptake of [³H]GLU. The application of high potassium (60 mM) stimulation exhibited a significant enhancement of the release of this newly synthesized [³H]GABA in a Ca²⁺ dependent manner. Kinetic analysis revealed that the evoked release of newly synthesized [³H]GABA was approximately two times greater than that of previously-loaded [³H]GABA, whereas no significant difference was observed in the spontaneous release. An immobilization stress in water failed to affect the release of newly synthesized [³H]GABA from striatal slices despite the occurrence of a significant enhancement of GABA formation in this structure.These results suggest that newly synthesized GABA may be preferentially released from its nerve terminals in response to the excitation of neurons at least in the striatum as compared with previously accumulated GABA.     

Comparison of Stevia plants grown from seeds,cuttings and stem-tip cultures for growth and sweet diterpene glucosides

The growth and sweet diterpene glucosides of Stevia plants propagated by stem-tip cultures were compared with those of the control plants propagated by seeds. There was no significant difference between the two groups both in growth and in chemical composition. As for the contents of sweet diterpene glucosides, however, the clonal plants showed significantly smaller variations than the sexually propagated plants; they were almost as homogeneous as the plants propagated by cuttings. These results suggest that the clonal propagation by stem-tip culture is an effective method of obtaining a population of uniform plants for the production of sweet diterpene glucosides.     

X-ray crystal structure of maltitol (4-O-α-d-glucopyranosyl-d-glucitol

Maltitol, crystallised from aqueous solution, has m.p. 146.5–147°, [α]_d + 106.5° (water), and is orthorhombic with the space group P2₁2₁2₁ and Z = 4, and with cell dimensions a = 8.166(5), b = 12.721(9), and c = 13.629(6) Å. The molecule shows a fully extended conformation with no intramolecular hydrogen-bonds. All nine hydroxyl groups are involved in intermolecular hydrogen-bond networks and in bifurcated, finite chains. The d-glucopyranosyl moiety has the ⁴C₁ conformation, and the conformation about the C-5–C-6 bond is gauche-gauche. The d-glucitol residue has the bent [ap, Psc, Psc (APP)] conformation. The empirical formula for the solubility in water is C = 119.1 + 1.204 T + 4.137 × 10^?2 T² ? 7.137 × 10^?4 T³ + 7.978 × 10^?6 T⁴. The thermal properties are as follows: ΔH_f = 13.5 kcal.mol^?1, and Q = ?5.57 kcal.mol^?1.     

Quantitative relationship between two reaction centersin the photosynthetic system of blue-green algae

The quantitative relationship between reaction centers I andII was studied with blue-green algae Anabaena cylindrica, Anabaenavariabilis and Anacystis nidulans grown under different lightconditions. The number of reaction centers I was estimated fromthe P700 content and that of reaction centers II, from the O₂yield of repetitive short flashes. Supplementary determinationswere done with three other blue-green algae and one red alga.The maximum number of reaction centers II counted from the O₂yield of repetitive short flashes was markedly smaller thanthe total number of P700 in all algae tested when the algaewere grown under weak light; in the extreme case (Anabaena cylindrica),the ratio was only 0.258?0.015. This ratio became larger andclose to unity when the algae were grown under stronger light.Variation in the number of reaction centers in a single cellsuggested that reaction center I was a variable component. Ourresults indicate that the proportion of the two reaction centersmay markedly vary in blue-green algae depending on the growthconditions (Received November 13, 1978; )     

Microspectrofluorometry of the autofluorescent flagellum in phototactic brown algal zoids

Summary Posterior flagella of zoids ofScytosiphon lomemaria andChorda filum (Phaeophyceae, Chromophyta) were isolated and subjected to microspectrofluorometry using a high sensitivity microspectrofluorometer in order to characterize the flagellar autofluorescent substances. Vigorous agitation in a Hypertonic medium yielded preparations of largely intact flagella retaining detectable green flagellar autofluorescence. Under 380–425 nm excitation light, maximum emission of flagellar autofluorescence was observed at 495 nm, whereas under 400–440 nm excitation light fluorescence shifted to around 510 nm. Comparison of these spectra with the fluorescence spectra of 4,5-cyclic FMN isolated from fertile thalli ofS. lomentaria, and of 6-carboxypterin suggested that two (or more) different fluorescent substances (presumably a flavin and a pterin) are present in the flagella.Abbreviations DTT dithiothreitol - FMN flavin mononucleotide - HEPES N-[2-hydroxyethyl]piperazine-N-[2-ethanesulfonic acid]) - PEG polyethylene glycol - PFB paraflagellar body - Tris tris(hydroxymethyl) aminomethane. Dedicated to Professors Masakazu Tatewaki and Tadao Yoshida on the occasion of their academic retirement