The ontogeny of the platycopid Keijcyoidea infralittoralis (Ostracoda: Podocopa)

Platycopid ostracods such as the genus Keijcyoidea Malz, 1981 (Family Cytherellidae) have a unique body plan and are regarded as a phylogenetically ancient lineage. Their ontogeny, which is important in considering phylogenetical relationships, is very poorly known except for the growth of the carapace; there are nine instars including the adult, as in other podocopan groups. All appendages in all immature instars (A-8 to A-1) of Keijcyoidea infralittoralis Tsukagoshi, Okada & Horne, 2006 are described and illustrated here. The anlagen of the copulatory organs and the sexual dimorphism of carapace size appear in the sixth (A-3) instar, whereas sexual dimorphism in both the fifth and the sixth limbs, a distinctive feature of adults, is not clearly evident until the eighth (A-1) instar. Appendages are added at the moults between the second (A-7) and third (A-6), and between the fifth (A-4) and sixth (A-3) instars. The seventh limb, which platycopid ostracods have lost in the adult stage, is observed as an anlage in the sixth (A-3) and seventh (A-2) instars. During the other moults, there are no significant changes to the body plan. The ontogeny of the Platycopida is compared with that of the Podocopida, and strongly suggests that the phylogenetic position of the Platycopida is as an end-member of the Podocopa. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society , 2008, 153 , 213–237.     

Photoperiodic and temperature control of nymphal development and induction of reproductive diapause in two predatory Orius bugs: interspecific and geographic differences

Abstract The effects of day‐length and temperature on pre‐adult growth and induction of reproductive diapause are studied in Orius sauteri and Orius minutus (Heteroptera: Anthocoridae) from northern (43.0°N, 141.4°E) and central (36.1°N, 140.1°E) Japan. In the north, at 20 °C, pre‐adult growth is slower under an LD 14 : 10 h photoperiod than under shorter or longer photophases. At 24 and 28 °C, the longer photophases result in shorter pre‐adult periods. Acceleration of nymphal growth by short days in autumn appears to be adaptive. In the central region, this response is less pronounced, suggesting that timing of adult emergence is less critical than in the north. Day length also influences the thermal requirements for pre‐adult development. The slope of the regression line representing temperature dependence of pre‐adult development is significantly smaller and the lower development threshold (LDT) is significantly lower under an LD 12 : 12 h photoperiod than under long‐day conditions. The weaker dependence of nymphal growth on temperature and the lower LDT in autumn might be adaptive. In the north, increased temperature shifts the critical day length of diapause induction and suppresses the photoperiodic response in O. sauteri but not in O. minutus. Further south, the incidence of diapause in both species is low even under short‐day conditions but the same interspecific difference is observed (i.e. increase of temperature affects the response in O. sauteri but not in O. minutus). This suggests seasonally earlier diapause induction with weaker temperature dependence in O. minutus than in O. sauteri.     

Genetic structure of Japanese populations of an ambrosia beetle,Xylosandrus germanus (Curculionidae: Scolytinae)

We examined the genetic structures of 13 Japanese populations of an ambrosia beetle, Xylosandrus germanus (Curculionidae: Scolytinae), to understand the effects of geographical barriers on the colonization dynamics of this species. The genetic structure was studied using portions of the mitochondrial cytochrome oxidase I (COI) gene. A phylogenetic analysis revealed three distinct lineages (clades A, B and C) within X. germanus. Clade A contained 21 haplotypes from all 13 populations; whereas clade B contained eight haplotypes from Hokkaido (Sapporo and Furano), Iwate and Nagano populations; and clade C contained only a single a haplotype from the Hokkaido (Furano) population. In the analysis of molecular variance (amova ), the greatest amount of genetic variation was detected between populations in Hokkaido and those in Honshu and other southern islands. Between these two groups of populations, all the values of the coefficient of gene differentiation were significantly larger than zero, except for the Hokkaido (Sapporo) versus Nagano comparison. Our results confirm that for X. germanus, gene flow has been interrupted between Hokkaido and Honshu since the last glacial maximum.     

Effects of forest fragmentation on species richness and composition of ground beetles (Coleoptera: Carabidae and Brachinidae) in urban landscapes

To clarify the effects of forest fragmentation in urban landscapes on the abundance, species richness, dominance, and species composition of ground beetles (Coleoptera: Carabidae and Brachinidae), we compared the beetles collected in 12 pitfall traps from April to July and from September to November between three continuous suburban forests and eight isolated urban forests (0.06–1.02 ha), most of which were in the precincts of shrines and temples in Hanshin District, Honshu, Japan. A total of 28 species and 4178 individuals of ground beetles were collected. Segregation of urban forests from continuous suburban forests has changed the species composition and resulted in the loss of some large‐sized forest species and the addition of some non‐forest species. Simpson's index of dominance (λ) also increased in the urban forests. The richness of forest species markedly decreased with the reduction in forest area but not with the distance from continuous forests, although the species richness of non‐forest species did not change with them. Also, species composition changed only with forest area. These findings indicate that continuous forests do not necessary serve as a “mainland” for urban forest species and that every urban habitat, however small in size, acts as a temporary reservoir of species. In comparison with populations of small‐sized species, populations of large‐sized forest species appeared to decline more readily during forest fragmentation.     

Chemical Analysis of Melanin Pigments in Feather Germs of Japanese Quail Bh (Black at Hatch) Mutants

Bh (black at hatch) is a mutation of Japanese quails which causes darkening or lightening of the plumage in heterozygotes or homozygotes, respectively. We chemically analyzed melanin pigments in feather germs of Bh mutant embryos and in feathers of adult animals. Dark brown dorsal feathers of wild-type adult animals had white barrings, but heterozygous ones lacked clear barrings. The feathers of wild-type and heterozygote animals contained both eumelanins and pheomelanins, the latter being more pheomelanic. On the dorsal skin of 10-day old wild-type embryos, longitudinal stripes from black and yellow rows of feather germs developed; two or three longitudinal rows of black feather germs and then two or three rows of yellow feather germs next to the short central feather germs. Heterozygous embryos appeared black in plumage pigmentation, due to the presence of‘gray’feather germs in rows of dorsal feather germs that corresponded to yellow rows in wild-type embryos. Homozygous dorsal feather germs did not develop the black and yellow longitudinal stripes, but were brown. Chemical analysis showed that embryos of each genotype contained both eumelanins and pheomelanins in the feather germs; however, the eumelanin content in ho-mozygous feather germs was very low. These results suggest that the Bh mutation causes pheomelanic changes in feathers of quails.     

Regulatory mechanisms in phenotypic plasticity of diapause and nondiapause pupal colouration of the swallowtail butterfly Papilio machaon

Nondiapause pupae of Papilio machaon L. exhibit pupal colour diphenism comprising green–yellow and brown–white types. To understand the regulatory mechanism underlying the control of pupal colouration in P. machaon, the effect of environmental cues on diapause and nondiapause pupal colouration is investigated. When larvae reared under short‐day and long‐day conditions are allowed to pupate in sites with a smooth surface and a yellow background colour, all diapause pupae exhibit a brown–white type and 89.5% of nondiapause pupae exhibit a green–yellow type, respectively. With rough‐surface pupation sites, all diapause pupae exhibit brown–white and intermediate types, whereas a large proportion of nondiapause pupae exhibit brown–white and intermediate types, although some exhibit a green–yellow type. When extracts prepared from the head‐thoracic and thoracic‐abdominal regions of larval central nervous systems are injected into the ligated abdomens of P. machaon short‐day pharate pupae, all recipients exhibit a brown–white colouration. Furthermore, when each extract is injected into the ligated abdomen of Papilio xuthus L. short‐day pharate pupae with orange‐pupa‐inducing factor activity, recipients injected with the head‐thoracic extract exhibit the brown type, whereas those injected with the thoracic‐abdominal extract exhibit an orange colour. The results indicate that the response to the environmental cues of pupation site in P. machaon changes according to the photoperiodic conditions experienced during larval stages, and that at least two hormonal factors producing brown–white pupae are located in the larval central nervous system, with the secretion of these factors being regulated by the recognition of environmental cues in long‐day larvae.     

Chemical Characterization of Melanins in Sheep Wool and Human Hair

The color of hair and wool in mammals and feathers in birds is mostly determined by the quantity and quality of melanins that are synthesized in follicular melanocytes and transferred to keratinocytes. There are two chemically distinct types of melanin pigments: the black to brown eumelanins and the yellow to reddish pheomelanins. Melanins in sheep wool and human hair of various colors were characterized by HPLC methods to estimate 5,6-dihydroxyindole-2-carboxylic acid (DHICA)-derived units in eumelanins and benzothiazine units in pheomelanins. Melanins were also characterized by spectrophotometric methods after differential solubilization in alkalies. It was demonstrated that 1) black wool in Asiatic sheep contains eumelanin with the DHICA content similar to black mouse melanin, while black to brown melanins from human hair contain much lower ratios of DHICA-derived units, comparable to the slaty mutation in mice, 2) dark brown to brown hair in human contains eumelanin whose chemical properties are indistinguishable from those of black hair, 3) dark red wool and red human hair contain pheomelanic pigments whose chemical properties are rather different from those of yellow pheomelanins in mice, and 4) light brown, blonde, and red hairs in human can be differentiated from each other with this methodology.     

Species Specificity of the Insect Prothoracicotropic Hormone (PITH): the Presence of Bombyx-and Samia-Specific PTTHs in the Brain of Bombyx mori

Crude extracts of Bombyx mori brains can provoke adult development when injected into brain-removed dormant pupae of Bombyx mori and Samia Cynthia ricini. From this fact the prothoracicotropic hormone (PTTH) of Bombyx has long been thought to be species-nonspecifically active on Samia. Chemical fractionation of Bombyx brain or head extracts by fractional precipitation with acetone, Sephadex G-50 gel-filtration, and DEAE-Sepharose CL-6B chromatography, however, separated the fractions which activated Bombyx brainless pupae from those which activated Samia. Those results reveal the existence of two species-specific PTTHs.     

Effects of Thioureas, Inhibitors of Melanogenesis, on Lens Transdifferentiation of Cultured Chicken Embryonic Retinal Pigment Cells

The effects of phenylthiourea (PTU) and its analogues on chick embryonic pigmented epithelial cells (PECs) in culture were studied to elucidate the correlation between inhibition of melanogenesis of PECs and enhancement of their transdifferentiation into lens cells.
Both 0.25–0.5 mM PTU and 0.1 mM alpha-naphthylthiourea (ANTU) effectively inhibited melanogenesis of PECs and stimulated their transdifferentiation into lens cells at the same time. Thiourea (TU) also inhibited melanogenesis at a much higher concentration (4 mM), but did not stimulate the lens transdifferentiation at all. Methylthiourea (MTU), on the other hand, did not inhibit melanogenesis, but stimulated the lens transdifferentiation. Testicular hyaluronidase effectively amplified the above-mentioned stimulating effects of thioureas without their altering optimum concentrations, although this enzyme itself never enhanced the lens transdifferentiation of PECs but suppressed their melanogenesis at a concentration of 100 U/ml medium, onward.
These results suggest that the suppression of melanogenesis of PECs by PTU or its analogues does not directly correlate with their transdifferentiation into lens cells. The possible mode of thiourea actions on the lens transdifferentiation of PECs cultured in vitro is discussed.     

Quantitative Analysis of Protein Synthesis Altered by Estrogen in Cultured Xenopus Liver Parenchymal Cell

Using the primary culture system of male Xenopus laevis hepatocytes consisting of more than 95% parenchymal cells, the effect of estradiol-17 β (10⁻⁶M) on protein synthesis was quantitatively analyzed by ³H-leucine incorporation kinetics and the estimation of specific radioactivity of newly synthesized secretory protein. The cells in a well defined culture revealed high plating efficiency and very low DNA synthetic activity. The cultured cells could synthesize several secretory proteins containing serum albumin. The pattern of secreted proteins in SDS-polyacrylamide gel electrophoresis (SDS-PAGE) did not alter with culture time but secretion rate of protein increased for 7 days, starting on the third day following inoculation. Estradiol added to the culture media extensively induced the synthesis of yolk precursor protein vitellogenin which accounted for 40–50% of the overall secretory protein synthesis and 20–30% of the total protein synthesis on day 7 of estradiol treatment. Ultimately, the total protein synthesis and secretory protein synthesis were stimulated 1.2–1.3 fold and 2.0–2.2 fold, respectively, over those of the control cells cultured in the absence of estradiol. These results indicated that the stimulation of protein synthesis was largely due to vitellogenin production. Such an estradiol-dependent stimulation of protein synthesis was also detected in the low molecular weight protein(s). On the other hand, albumin synthesis was evidently reduced by estradiol. Thus, estradiol had two different effects on protein synthesis.
The results obtained in this study will be discussed in relation to the findings o in vivo experiments.