Estimating the beginning day of Japanese cedar pollen release under global climate change

This study examined the effects of snowfall on the beginning day of Cryptomeria japonica pollen release and predicted it under global climate change. We used a statistical method in order to investigate when the pollen release would start and how much sooner it would be, by using data on predicted meteorological conditions under global warming in Yamagata City, Japan. Estimation accuracy was improved by multiple regression by using the mean air temperature from January to February and snowfall depth in February. Adding snowfall depth yielded more accurate estimates of the beginning day of pollen release than using air temperature alone. It is possible that the effects of heat insulation and cooling by snow delay the flowering day. Under the predicted global climate change, we expect the beginning day of pollen release to become earlier in Yamagata City. The date would be 8 February in approximately 100 years, compared with 20 February at the earliest now. Eighty years from now the date could be earlier than any date recorded so far.     

Divergent enhancer haplotype of ebony on inversion In(3R)Payne associated with pigmentation variation in a tropical population of Drosophila melanogaster

The pattern and intensity of pigmentation have direct impact on individual fitness through various ecological factors. In a Drosophila melanogaster population from southern Japan, thoracic trident pigmentation intensity of most of the strains could be classified into Dark or Light‐type. The expression level variation of the ebony gene correlated well with this phenotype and the allelic differences in expression indicated that the variation is partly due to cis‐regulatory changes. In the ～13 kb gene region, we identified 17 nucleotide sites and 2 indels that were in complete association with the thoracic trident pigmentation intensity. Interestingly, 11 out of 19 sites located within ～0.5 kb of the core epidermis enhancer. These sites had no obvious association with the abdominal pigmentation intensity in the previously analysed African populations from Uganda and Kenya, which suggested that multiple potential mutational pathways in the cis‐regulatory control region of a single gene could lead to similar phenotypic variation within this species. We also found that the Light‐type enhancer haplotype is strongly linked to a cosmopolitan inversion, In(3R)Payne, which is predominant in warmer climatic regions in both hemispheres. The sequence pattern suggested that the strong linkage may be due to selective forces related to thermal adaptation. The inferred selection for lighter pigmentation in the Japanese population is in the opposite direction of the previously reported case of selection for darker individuals in African populations. Nevertheless, both adaptive changes involved cis‐regulatory changes of ebony, which shows that this gene is likely to be a common target of natural selection.     

Comparison of genetic variation and differentiation using microsatellite markers among three rare threatened and one widespread toad lily species of Tricyrtis section Flavae (Convallariaceae) in Japan

Genetic diversities were examined using six microsatellite markers amplifiable in three rare and one widespread species of Tricyrtis section Flavae, which are endemic to Japan. Contrary to a general expectation, the three rare species, Tricyrtis flava, Tricyrtis ohsumiensis and Tricyrtis perfoliata, have comparable genetic variation at the species level to that of the widespread Tricyrtis nana. This is probably because T. nana has not sufficiently recovered genetic diversity from the bottleneck at speciation or because recent range contractions have occurred in the three rare species. Genetic diversity at the population level was smaller in the putative selfing species T. nana than in the other three outcrossing species. Compared with a preceding study using allozyme markers, the genetic diversity in microsatellite loci was considerably larger, probably resulting from higher mutation rates at the microsatellite loci. Owing to the high genetic diversity of the microsatellite markers, genetic differentiation among populations could be estimated even in T. nana with little allozyme polymorphism.     

ESTABLISHMENT OF A CELL LINE FROM EMBRYONIC TISSUES OF THE FLESHFLY, SARCOPHAGA PEREGRINA (INSECTA: DIPTERA)

A continuous cell line was established from embryonic tissues of the fleshfly, Sarcophaga peregrine , and was designated as NIH-SaPe-4. The primary culture was initiated in October, 1977, and the cell line was passed 68 times during the following year. The cells were heterogeneous in morphology. Most cells were diploid and their chromosomes consisted of 4 metacentric, 6 sub-metacentric and 2 micro chromosomes. The population doubling time of the cell line was about 30 hr. The cells grew faster in Mitsuhashi-Maramorosch's medium than in Schneider's medium. The cells were either stored in the usual medium at 5°C for about 3 months, or in a medium containing 10% glycerol at –80°C for a longer period. Cell growth was suppressed by 20-hydroxy-ecdysone when at a greater concentration than 0.01 μg/ml, whereas insulin showed no effects on cell growth at a strength of 0.4 and 0.04 IU/ml.     

Quantitative Analysis of Striped Coat-Color Patterns in Large White→Duroc Chimeric Pigs With Special Reference to the Genetic Control Mechanisms of the Dominant Black-Eyed White Phenotype

Coat colors of four chimeric pigs produced by the microinjection of dissociated blastomeres of (Landrace × Large White) blastocysts to the blastocyst cavity of (Duroc × Duroc) blastocysts (Kashiwazaki et al., 1992) exhibited characteristic horizontal stripe-patterns. We carried out quantitative analysis of those patterns in order to derive information concerning the genetic regulatory mechanisms of the dominant black-eyed white phenotypes in the pig. In the four chimeras, the theoretical mean widths of the single-clone stripe calculated from the estimated widths of minimal recognizable stripe (MRS) (Tachi, 1988) were 2.1 ± 0.1, 2.23 ± 0.15,1.89 ± 0.06, and 1.93 ± 0.28 cm respectively. The estimated number of single-clone stripes in the thoracico-lumbar region of those animals were 42.3, 40.7, 46.3, 44.2, and about twice the mean number of vertebrae in the same region (Duroc, 20 or 21; Large White, 21 or 22). Furthermore, the mean length of thoracico-lumbar vertebrate in two of the chimeric pigs, as measured on X-ray radiographs, was approximately twice the mean single-clone stripe width. It was concluded that the stripe-patterns of the chimeric pigs probably represented the dermatome patterns of epidermis; and in the pig, a single somite was likely to be derived from the clones of two primordial cells, as originally proposed by Gearhart & Mintz (1972) in the mouse. It was suggested, furthermore, that in the Large White→Duroc chimeric pigs, melanocytes that migrated into the region of skin formed by a Large White dermatome could not survive, thus creating a clearly demarcated white stripe. Possible involvement of KL or c-kit in the dominant black-eyed white phenotype of the pig is discussed.     

Evidence for divergent natural selection of a Lake Tanganyika cichlid inferred from repeated radiations in body size

Divergent natural selection is thought to play a vital role in speciation, but clear, measurable examples from nature are still few. Among the many possible sources of divergent natural selection, predation pressure may be important because predators are ubiquitous in food webs. Here, we show evidence for divergent natural selection in a Lake Tanganyika cichlid, Telmatochromis temporalis , which uses burrows under stones or empty snail shells as shelters. This species contains normal and dwarf morphs at several localities. The normal morph inhabits rocky shorelines, whereas the dwarf morph invariably inhabits shell beds, where empty snail shells densely cover the lake bottom. Genetic evidence suggested that the dwarf morph evolved independently from the normal morph at two areas, and morphological analysis and evaluation of habitat structure revealed that the body sizes of morphs closely matched the available shelter sizes in their habitats. These findings suggest that the two morphs repeatedly evolved through divergent natural selection associated with the strategy for sheltering from predators.     

Isolation and characterization of 10 microsatellite loci in the Ponerinae ant Pachycondyla luteipes (Hymenoptera; Formicidae)

We developed 10 polymorphic microsatellite loci for the Ponerinae ant Pachycondyla luteipes using the magnetic particle method. Nine of the 10 loci tested were highly polymorphic, having four to eight alleles in P. luteipes with expected heterozygosity of 0.38–0.73, and also appeared to be applicable to other related species such as Pachycondyla chinensis. These loci can be used to test the hypotheses on the population genetic structures, such as if this ant is unicolonial or not.