Genetic distance between Nasutitermes takasagoensis (Isoptera: Termitidae) populations in Taiwan and the Yaeyama Islands, analyzed by amplified fragment length polymorphism markers

Dispersal ability and degree of inbreeding in a population can indirectly be assessed using genetic markers. It has been suggested that winged termites are not able to fly distances greater than several hundred meters. Using the amplified fragment length polymorphism (AFLP) technique, we previously analyzed the population substructure of Nasutitermes takasagoensis in the Yaeyama Islands, southern Japan. We found that there is moderate subpopulation structure based on the AFLP data. Moreover, the relatively low G_st and genetic distances among insular populations suggest that there is a possibility that winged termites are able to fly over distances of several kilometers. To learn more about this, in the present study, we compared new samples collected from the Hengchuen Peninsula in southern Taiwan with samples previously collected from the Yaeyama Islands. Using the samples collected in Taiwan, genetic distance was calculated against samples from six of the Yaeyama Islands. Genetic diversity, average heterozygosity, percentage of polymorphic loci, G_st and gene flow (Nm) were calculated. A total of 155 AFLP fragments were obtained for three primer combinations used, with 8 (5%) polymorphic bands. Genetic distance between the populations of Taiwan and the rest of the islands was greater than the genetic distance among the Yaeyama Islands. Although previous studies showed that average Nm among the Yaeyama Islands was 2.47, all of the observed Nm between Taiwan and the Yaeyama Islands were below 1. These findings suggest that the geographic distance between Taiwan and the Yaeyama Islands is large enough to prevent gene flow between them.     

Light-induced formation of fruit-bodies in a basidiomycete, Favolus arcularius (FR.) AMES

fruit-bodies in Favolus arcularius. The effect of light lastedfor about one day after transfer to darkness. The mycelium became sensitive to light about 2.5 days afterinoculation; i.e., at the beginning of the rapid growth phase.The site of fruiting was 2–5 mm inside the edge of colony(actively dividing zone) at the start of illumination. Whenone half of the plate culture was illuminated, fruiting wasrestricted to the illuminated half of the colony ; i.e., theeffect of light was localized. These results suggest that thecells sensitive to light are the actively dividing cells. Under a fixed light intensity, the total irradiation time requiredfor the initiation of fruiting was nearly constant, irrespectiveof the durations of pre-incubation in darkness and the dailyillumination period. With increasing light intensities, up toabout 500 lux, fruiting was promoted, however, a further increasein light intensity was inhibitory. (Received March 27, 1968; )     

Cold‐induced organelle relocation in the liverwort Marchantia polymorpha L.

Organelles change their subcellular positions in response to various environmental conditions. Recently, we reported that cold treatments alter the intracellular position of chloroplasts and nuclei (cold positioning) in the fern Adiantum capillus‐veneris; chloroplasts and nuclei localized to the periclinal cell wall relocated to anticlinal cell wall after cold treatments. To further understand organelle positioning under cold conditions, we studied cold‐induced organelle relocation in the liverwort Marchantia polymorpha L. When sporelings and gemmmalings were treated under low temperature (5 °C), chloroplast cold positioning response was successfully induced both in the sporelings and the gemmmalings of M. polymorpha. Using a genetic transformation, nuclei, mitochondria or peroxisomes were visualized with a fluorescent protein, and the transgenic gemmmalings were incubated under the cold condition. Nuclei and peroxisomes, but not mitochondria, clearly relocated from the periclinal cell wall to the anticlinal cell wall after cold treatments. Our findings suggest that several organelles concurrently change their positions in the liverwort cell to cope with cold temperature.     

Species‐specific mitochondrial gene rearrangements in biting midges and vector species identification

Abstract Partial mitochondrial gene sequences of 16 Culicoides species were determined to elucidate phylogenetic relations among species and to develop a molecular identification method for important virus vector species. In addition, the analysis found mitochondrial gene rearrangement in several species. Sequences of the mitochondrial genome region, cox1–trnL2–cox2 (1940–3785 bp) of 16 Culicoides and additional sequences were determined in some species, including whole mitochondrial genome sequences of Culicoides arakawae. Nine species showed common organization in this region, with three genes cox1–trnL2–cox2 and a small or no intergenic region (0–30 bp) between them. The other seven species showed translocation of tRNA and protein‐coding genes and/or insertion of AT‐rich non‐coding sequences (65–1846 bp) between the genes. The varied gene rearrangements among species within a genus is very rare for mitochondrial genome organization. Phylogenetic analyses based on the sequences of cox1+cox2 suggest a few clades among Japanese Culicoides species. No relationships between phylogenetic closeness and mitochondrial gene rearrangements were observed. Sequence data were used to establish a polymerase chain reaction tool to distinguish three important vector species from other Culicoides species, for which classification during larval stages is not advanced and identification is difficult.     

Survivorship and growth in the larvae of Luehdorfia japonica feeding on old leaves of Asarum megacalyx

Although the papilionid butterfly Luehdorfia japonica, usually lays eggs on new leaves of the host plant (Asarum sp.; Aristolochiaceae), eggs of the butterfly were frequently found on old leaves of Asarum megacalyx in Suyama, Tokamachi, Niigata prefecture. Larvae hatched on new leaves and those hatched on old leaves did not show significant differences in their survival rate in the field. In laboratory breeding, about 90% of larvae that were fed old leaves survived and developed normally to the pupal stage. Their growth rate, however, was slightly lower than those that were fed new leaves. No nutritional differences were found between the old and new leaves. The reason why oviposition on the old leaves was so frequent and why larvae that hatched on old leaves could survive in the study area is discussed.     

Analysis In Vitro of Capacity of Fetal Fat Pad to Support Mammary Gland Embryogenesis

Fourteen-day fetal mammary fat pad precursor tissue (FP) has the capacity to support various fetal epithelia allowing them to accomplish their characteristic development in vivo , without their own mesenchyme (1). This capacity decreases with age of fetal fat pad and is lost postnatally. To analyse the molecular mechanism of such interaction, a method for in vitro duplication of organogenesis is necessary. In the present paper, a co-culture system of fetal epithelium with prospective mammary fat pad is described. The explanted mammary epithelium started budding, then grew out forming branched mammary ducts with end buds. Ultrastructurally, the developing ductal structures exhibited the typical mammary gland morphogenesis.
³H-Thymidine incorportion assessed by autoradiography showed that the mammary gland morphogenesis in vitro was due to the proliferation of epithelial cells, not merely to a change of the shape of the epithelium. This supportive capacity of 14-day FP also decreased with aging; explanted mammary epithelium did not grow into 17-day FP. When insoluble, non-living biomatrix was used in place of living FP the epithelium grew into the matrix but the resulting structures lacked characteristic morphology of epithelium on living fetal FP. The difference of capacity between 14-day and 17-day tissues was also lost.     

Newer Melanogenesis Control and Melanoma Eradication

Further advances leading to more sophisticated and effective suppression of melanogenesis and melanoma growth based on clarification and utilization of common vital factors involved in both processes are reviewed. Induction of depigmentation has been achieved by both glycosylation and its processing inhibitors, which have been found to be critical for the maturation and transport of tyrosinase from ribosomes through GERL-coated vesicles into premelanosomes. Kojic acid, a copper chelating melanogenic inhibitor, can induce inhibition of isolated tyrosinase activity as well as melanization in living pigment cells in in vitro and in vivo systems. This depigmenting effect was found to be due to a concurrent decrease in both eu- and pheomelanin formation. Malignant melanoma principally has accentuated melanosome genesis, which has been utilized to accumulate selectively ¹⁰B into melanoma cells using ¹⁰B-dopa analogue. Subsequent thermal neutron irradiation induces ¹⁰B(n, α)⁷Li reaction which releases high LET particles within a range of 10–14 μm thus erradicating selectively melanoma at the cellular level. This new therapy has been applied to a human melanoma lesion for the first time, and a successful therapeutic effect on melanoma has been obtained.     

Isolation and Characterization of High Molecular Weight Melanogenic Inhibitors Naturally Occurring in Melanoma Cells

Intrinsic melanogenic inhibitors with high molecular weights have been isolated from Greene's amelanotic hamster melanoma by DEAE ion-exchange and gel filtration chromatographies. The native molecular weights of two partially purified inhibitors have been determined to be 15 kDa (β-type) and 67 kDa (γ-type), respectively, using HPLC gel filtration. Both types of inhibitors, despite their inability to directly inhibit isolated tyrosinase, have been shown to markedly inhibit melanin formation in cultured B16 cells. In contrast to the β-type inhibitor, the γ-type inhibitor can induce depigmentation in B16 cells without abolishing their internal tyrosinase activity. Further, it has been determined that both inhibitors contain various amounts of unsaturated fatty acids, C15:1, C18:1, C18:2, C18:3, C20:3, and C20:4, which exhibit depigmentary activities on cultured B16 cells. C15:1 is low in the β-type, but high in the γ-type whereas C18:3 is high in the β-type but low in the γ-type. These results suggest that the differential action of these inhibitors is most likely due to the composition of the unsaturated fatty acids.     

Aspects of DNA, RNA and protein synthesis during somatic embryogenesis in a carrot cell suspension culture

Changes in DNA, RNA and protein content, incorporation of ³H-thymidine, ¹⁴C-uridine and ³H-leucine and template activity of chromatin were investigated in the early process of somatic embryogenesis in a carrot (Daucus carota L. cv. Kurodagosun) cell suspension culture using a synchronous system. An embryogenetic culture in a medium containing 10^-7M zeatin was compared with a non-embryogenetic culture in a medium containing 10^-7M zeatin and 5 x 10^-7M 2,4-D. DNA was synthesized very actively prior to and during the formation of globular embryos in the embryogenetic culture. The RNA and protein content per tube increased at an almost constant rate in both cultures, while the rate of incorporation of labelled precursors of RNA and protein rose much more prior to active DNA synthesis in the embryogenetic culture than in the non-embryogenetic culture. Template activity of chromatin was high in the early stage of embryogenesis in the embryogenetic culture. The results obtained here showed that synthesis and turnover of RNA and protein became active prior to active DNA synthesis in the early stage of embryogenesis, and that these changes at macromolecular levels may play important roles in embryogenesis.     

Fish Tumor Pigment Cells: Differentiation and Comparison to Their Normal Counterparts

The objectives of this paper are to describe 1) the developmentof new research systems for biochemical comparison of cellulartraits between normal and tumorous pigment cells of fish origin,2) the similarity and dissimilarity between these two categoriesof pigment cells with regard to growth, differentiation andpigment translocating activities and 3) the potentials of thesetumorous pigment cells to manifest multiple differentiation.The development of research systems has been achieved by theestablishment of 1) methods to obtain homogenous populationsof viable, cultivatable xanthophores (erythrophores) and melanophoresfrom goldfish skins, 2) permanent cell lines from goldfish erythrophoromas(tumors derived from erythrophores) and from Nibe croaker irido-melanophoromas(tumors composed of mixed populations of iridophore- and melanophore-likecells) and 3) procedures to induce differentiation in normaland tumorous stem cells (including the formation of pigmentsand ability to undergo pigment translocation in response tocAMP, to the neurotransmitter epinephrine and to the hormonesACTH and melatonin). Two kinds of tumorous pigment cell linesexamined herein have the ability to form, in addition to variouspigments, structures similar to dermal skeletons and lentoidbodies. These findings strongly suggest the possibility thatthese fish pigment cell tumors are neural crest stem cell tumorsin nature.