Cold acclimation increases cold tolerance independently of diapause programing in the bean bug, Riptortus pedestris.

The bean bug (Riptortus pedestris) is a pest of soybeans and other legumes in Japan and other Asian countries. It enters a facultative adult diapause on exposure to short days. While photoperiodism and diapause are well understood in R. pedestris, knowledge of cold tolerance is very limited, as is information on the effect of diapause on cold tolerance. We examined the effect of photoperiod, cold acclimation, and feeding status on cold tolerance in R. pedestris. We found that cold acclimation significantly increased survival at -10°C in both long- and short-day adult R. pedestris. Since the difference in cold survival between long- and short-day cold-acclimated groups was only marginal, we conclude that entering diapause is not crucial for R. pedestris to successfully pass through cold acclimation and become cold tolerant. We observed similar effects in 5th instar nymphs, with both long- and short-day cold-acclimated groups surviving longer cold exposures compared with non-acclimated groups. Starvation, which was tested only in adult bugs, had only a negligible and negative impact on cold survival. Although cold tolerance significantly increased with cold acclimation in adult bugs, supercooling capacity unexpectedly decreased. Our results suggest that changes in supercooling capacity as well as in water content are unrelated to cold tolerance in R. pedestris. An analysis of metabolites revealed differences between the treatments, and while several metabolites markedly increased with cold acclimation, their concentrations were too low to have a significant effect on cold tolerance.

Causal involvement of mammalian-type cryptochrome in the circadian cuticle deposition rhythm in the bean bug Riptortus pedestris.

Mammalian-type CRYPTOCHROME (CRY-m) is considered to be a core repressive component of the circadian clock in various insect species. However, this role is based only on the molecular function of CRY-m in cultured cells and it therefore remains unknown whether CRY-m is indispensable for governing physiological rhythms at the organismal level. In the present study, we show that RNA interference (RNAi) targeting of cry-m in the bean bug Riptortus pedestris disrupts the circadian clock governing the cuticle deposition rhythm and results in the generation of a single cuticle layer. Furthermore, period expression was induced in cry-m RNAi insects. These results verified that CRY-m functions as a negative regulator in the circadian clock that generates physiological rhythm at the organismal level.

A simple, heat-sterilizable artificial diet excluding animal-derived ingredients for adult blowfly, Lucilia sericata.

Artificial diets have been developed for Lucilia sericata (Meigen) blowfly larvae; however, diets for adults have not yet been developed. An adult diet that excludes animal tissues and animal-derived ingredients and promotes not only ovarian development, but also oviposition, would aid in basic research and maggot debridement therapy. We have successfully developed artificial diets that exclude animal tissues and animal-derived ingredients for L. sericata adults. The outcomes of the diets were comparable with those of a beef liver diet in terms of oviposition, adult survival and number of offspring.

Upregulation of genes belonging to the drosomycin family in diapausing adults of Drosophila triauraria.

Diapause-associated gene expression was studied in Drosophila triauraria using subtractive hybridization. Two genes that were shown to be upregulated in diapausing flies by Northern hybridization have similarity to genes encoding antifungal peptides of Drosophila melanogaster, members of the drosomycin family (drosomycin, CG10812, CG10813, CG10815 and CG11520). In addition, a signal peptide and Knot 1 domain are shared with them. The genes cloned from D. triauraria are tentatively named drosomycin-like. However, the similarities between drosomycin-like in D. triauraria and the members of the drosomycin family in D. melanogaster are quite lower than those between other homologous genes in these species. In addition, neighbor-joining analysis revealed that drosomycin-like in D. triauraria is not closely related to known members of the family in D. melanogaster. Thus, it is most plausible that drosomycin-like is not a D. triauraria counterpart of known members of the family, but a novel member belonging to the family. The drosomycin-like gene is expected to have a few copies, because at least two sequences having unique 3'-ends were obtained in RACE, and multiple bands were observed in Southern hybridization. However, these sequences from RACE had the same ORF. Probes for genes encoding additional antimicrobial peptides were used to evaluate expression during diapause. Like drosomycin-like, drosomycin was upregulated during diapause, but defensin and drosocin were not.

Unidimensional versus multidimensional approaches to the assessment of acculturation for Asian American populations.

This study used generational status and the Suinn-Lew Asian Self-Identity Acculturation scale to examine unidimensional versus multidimensional approaches to the conceptualization and measurement of acculturation and their relationships to relevant cultural indicator variables, including measures of Individualism-Collectivism, Independent-Interdependent Self-Construal, Loss of Face, and Impression Management. Multivariate analyses of covariance and partial correlations were used to examine the relationship between the acculturation models and each set of cultural indicator variables while controlling for socioeconomic status. Given that acculturation differences are often cited as evidence for a culture effect between groups, the present findings of an uneven nature of these relationships as a function of the particular acculturation measurement strategy have important implications for research on Asian Americans.

A novel gene that is up-regulated during recovery from cold shock in Drosophila melanogaster.

Gene expression during recovery at 25 degrees C (rearing temperature) after cold shock (0 degrees C) was studied in Drosophila melanogaster using a subtraction technique. A novel gene (Frost, abbreviated as Fst) was considerably up-regulated during recovery after cold shock. In addition, a prolongation of cold shock was more effective for induction. In contrast to cold shock, Fst gene did not respond to heat shock. This gene is apparently the same as the unidentified gene, CG9434. Fst has high internal repeats not only in nucleotide but also in amino acid sequences. In addition, FST protein has a proline-rich region. The deduced amino acid sequence revealed a modular structure; i.e., a signal peptide in the N-terminal region followed by a long hydrophilic region. Therefore, this protein is likely to be directed into ER and secreted into extracellular space.

Phylogenetic utility of mitochondrial COI and nuclear Gpdh genes in Drosophila.

Phylogenetic utility of the mitochondrial COI (cytochrome oxidase subunit I) and nuclear Gpdh (glycerol-3-phosphate dehydrogenase) genes was studied in the Drosophila melanogaster species group. The rate of substitution was higher in the COI gene than in the Gpdh gene. In addition, multiple substitutions, not only for transitional but also for transversional substitutions, occurred faster in the COI gene. None of the trees obtained using the COI gene supported the well-established monophyly of the ananassae subgroup. In addition, the incongruence length difference test, Templeton test, and partitioned Bremer support revealed that the trees based on the COI data are considerably different from those based on the Gpdh and the combined data set. Thus, the COI gene did not show good phylogenetic performance in the melanogaster group. The present analyses based on the Gpdh gene and the combined data set revealed that the ananassae subgroup branched off first in the melanogaster group followed by the montium subgroup and further by the melanogaster subgroup in contrast to the most recent phylogenetic hypothesis based on Amy multigenes.

Phylogenetic relationships and climatic adaptations in the Drosophila takahashii and montium species subgroups.

We analyze phylogenetic relationships among temperate, subtropical highland, and subtropical lowland species of the Drosophila takahashii and montium species subgroups based on sequence data of COI and Gpdh genes and discuss the evolution of temperate species in these subgroups with reference to their climatic adaptations. In the takahashii subgroup, D. lutescens (the temperate species) branched off first in the tree based on the combined data set, but D. prostipennis (the subtropical highland species) branched off first in the trees based on single genes. Thus, phylogenetic relationships in this subgroup are still ambiguous. In the montium subgroup, the cool-temperate species are phylogenetically close to the warm-temperate species, and these cool- and warm-temperate species form a cluster with the subtropical highland species. This suggests that perhaps the cool-temperate species derived from the warm-temperate species and the warm-temperate species derived from the subtropical highland species. In comparison with the subtropical lowland species, the subtropical highland species may be better able to colonize temperate areas since, as in the temperate species, they have an ability to develop their ovaries at moderately low temperature. However, the subtropical highland species, as well as the subtropical lowland species, were much less cold tolerant than the temperate species. Therefore, considerable genetic reformation would be required for both the subtropical highland and the subtropical lowland species to adapt to temperate climates.

Heat- and cold-shock responses and temperature adaptations in subtropical and temperate species of Drosophila.

Accumulation of Hsp70 mRNA was investigated with relation to heat and cold tolerance in adult males of three Drosophila species. The subtropical lowland species (D. watanabei) and the cool-temperate species (D. triauraria) were more tolerant to heat than the subtropical highland species (D. trapezifrons), and the cool-temperate species were much more tolerant to cold than the two subtropical species. Thus, heat and cold tolerance was related to temperature conditions in the habitats. The threshold temperatures for the induction of Hsp70 mRNA at heat and cold were higher in D. watanabei than in D. trapezifrons or D. triauraria, but were not different between the latter two species in spite of the difference in their heat and cold tolerance. In D. trapezifrons, exposures to 0 degrees C for 12h and 6 degrees C for 24h killed about 40% of individuals, but the former treatment induced Hsp70 mRNA while the latter one did not. Thus, the relation between the heat- and cold-shock responses and temperature tolerance was not rigid in the species studied. In D. triauraria, the threshold temperatures for the induction of Hsp70 mRNA at heat and cold were lower when reared at a lower temperature.

Accumulation of Hsp70 mRNA under environmental stresses in diapausing and nondiapausing adults of Drosophila triauraria.

Drosophila triauraria entered reproductive diapause in response to short daylengths and acquired tolerance to heat, cold and desiccation. In this species, the heat-shock response (accumulation of Hsp70 mRNA in response to heat) occurred at 27-41 degrees C, and the level of Hsp70 mRNA did not differ between diapausing and nondiapausing individuals. Hsp70 mRNA was also induced by exposure to -4 or -8 degrees C. However, it was scarcely detected just after the exposure to cold, but accumulated when flies were maintained at normal temperature following the exposure to cold. The level of Hsp70 mRNA was lower in diapausing individuals than in nondiapausing ones when exposed to -4 degrees C, but was not different between them when exposed to -8 degrees C. This species did not synthesize Hsp70 mRNA under desiccation stress irrespective of the diapause state. These results suggest that diapausing individuals of this species acquired tolerance to heat, cold and desiccation independent of the transcriptional regulation of the hsp70 gene