Geographical distribution and cytological variation ofLemna paucicostata Hegelm. in Japan

More than 100 strains ofLemna paucicostata Hegelm. collected from various localities in Japan were classified into 4 types according to the criterion of Yukawa and Takimoto (1976). N-1 type strains are widely distributed in Hokkaido, Honshu, Shikoku and Kyushu, N-2 type strains only in the area on the Japan Sea side of north Japan, K type strain only at the campus of Kyoto University, and S type strains in southern Japan. Numbers of chromosomes in somatic cells of N-1, N-2, K and S type strains were 2n=66–84, 40, 50 and 40, respectively. In N-2 and S type strains, all chromosomes (20 bivalent chromosomes) were lined up on the equatorial plate at metaphase of the first meiotic division (MI). However, in N-1 type strains, several chromosomes, and in the K type strain, more chromosomes were away from the equatorial plate at MI. Pollen fertility was 60–70%, higher than 90%, 0% and higher than 90%, in N-1, N-2, K and S type strains, respectively.     

Flowering response oflemna paucicostata in japan

Twenty-two strains ofLemna paucicostata collected from various districts in Japan are classified into 4 types having different morphological features and photoperiodic behaviors. (I) The “N-1” type, widely distributed in north and middle Japan, consists of many short-day strains with similar morphological characteristics. The strain of northern origin, however, has a shorter critical dark period than that of southern origin, and most of the strains flower in response to a single short day though some from middle Japan require 2 short days. (2) The “N-2” type, found in a limited area of northern Japan, is also a short-day type, but has very long critical dark periods and requires 3–5 short-day cycles for flowering. (3) The “S” type, distributed in southern Japan, never flowered in any photoperiod or culture conditions tested. (4) The “K” type, strain 351, collected at the experimental farm of Kyoto University, is a day-neutral type and flowers independently of photoperiod. Application of some SH inhibitors, tungstate or EDTA, or exposure to blue, far-red or low-intensity light caused daylength-independent flowering in short-day strain 6746 (California origin), but none of these treatments caused flowering in any short-day strain collected in Japan.     

Further studies on the flowering ofLemna paucicostata in Japan

Flowering behavior of 22 strains ofLemna paucicostata collected in Japan by Yukawa and Takimoto (1976) was re-examined. The critical dark periods of the short-day strains (N-1 and N-2 types) were shorter than those determined by Yukawa and Takimoto except for that of one strain. Particularly in strains 391, 381 and 321, the differences were as large as 2.25, 1.75 and 1.5 hr, respectively. Such differences were found to be due at least partly to the difference in night temperature; 25 C for the light and 23 C for the dark periods in the present experiment, and 25 C throughout the light and dark periods in the previous experiment. The S type strains did not flower under our experimental conditions (fluorescent light of 6,000 lux at 25 C) at any photoperiod tested, but flowered as a quantitative long-day plant under natural daylight or high-intensity light (12,000 lux). Addition of sucrose or ammonium ion to the medium suppressed the flowering of these strains under high-intensity light. Addition of benzoic acid (1–5 μM) to 0.5 strength NH₄ ⁺-free Hutner's medium caused daylength-independent flowering in some N-1 type strains and in all N-2 type strains tested. S type strains cultured under fluorescent light of 6,000 lux also flowered rapidly in response to benzoic acid.     

Myrmecochorous adaptations ofCorydalis species (Papaveraceae) in southern Japan

Dispersal morphology based on the myrmecochorous adaptations for predator avoidance of sevenCorydalis species including two varieties are investigated in southern Japan. Three types of myrmecochory were distinguished: myrmecochory with autochory (diplochory), the explosive ejection of seeds followed by ant transportation; myrmecochory with vegetative reproduction, seed-transportation by ants and reproduction by tuber; and pure myrmecochory, seed-transporting by ants only. Diplochory occurs in one winter annual plant, which has explosive capsules, a smooth seed surface, a small elaiosome, long pedicels and large bracts. Myrmecochory with vegetative reproduction occurs in two perennials that reproduce by tuber, although they also produce a small number of seeds with a medium-sized elaiosome. the pedicels and bracts are medium in size. Pure myrmecochory occurs in five annuals or biennials that are characterized by a rough seed surface with a large elaiosome, comparatively high seed production, short pedicels and only small bracts. Diplochory is exhibited by only one species distributed widely throughout Japan. Myrmecochory with vegetative reproduction is exhibited by species mainly distributed in cool-temperate northern Japan, while true myrmecochory is exhibited by the majority ofCorydalis species in warm-temperate Japan.     

Cytogenetic studies on an intergeneric hybrid betweenAgropyron tsukushiense andElymus mollis

Elymus mollis is distributed widely from Korea to Japan, Kamchatka and Alaska, the northern part of U.S.S.R., and Northern and Eastern Canada, Greenland and Iceland. This species is tetraploid (2n=28). A strain of this species collected in Hokkaido was crossed withAgropyron tsukushiense var.transiens collected in Mishima. From this cross, 22 F₁ plants were produced. Crossability calculated from the number of hybrid plants produced and the number of floret pollinated was 30.6%. The shape of the F₁ spikes was of theAgropyron type but the glumes were hairy as were those of theElymus parent. One of the characteristics distinguishingElymus fromAgropyron is the production of two spikelets at almost all nodes of the rachis. This character was not expressed in the F₁ plants. All pollen grains of the F₁ plants were completely abortive. The average chromosome pairing at the MI of the PMCs of the F₁ amounted to 2.03 bivalents and 30.95 univalents. Almost all bivalents ranging from one to seven were rod-shaped connected with interstitial or terminal chiasma. These results indicate a lack of genomic homology between the three genomes ofA. tsukushiense and the two genomes ofE. mollis. Contribution No. 37 from the Plant Germ-plasm Institute, Faculty of Agriculture, Kyoto University, Kyoto, Japan.     

Dormancy inDioscorea: Differences of temperature responses in seed germination among six Japanese species

Effects on seed germination of temperatures ranging from −2 C to +29 C were tested inDioscorea nipponica, D. tokoro, D. japonica, D. tenuipes, D. septemloba andD. quinqueloba which orginate in the temperate zone; they are distributed from northern cold areas to southern warm areas approximately in this order in Japan. After water imbibition of these seeds, chilling induced full germination, and high temperatures over 23 C induced a secondary dormancy, but sensitivities to the chilling and to the high temperatures differed with species. Cold-climate species germinated rapidly at higher temperatures after a short-term chilling or even without chilling, whereas warm-climate species required chilling of a rather long period for germination; thus, among 6 species tested, favourable temperatures for germination and climatic temperatures of distribution area were conversely correlated. Seeds ofD. tokoro andD. japonica collected from several populations grown in different climates were also tested for germination at 11 to 29 C; seeds from warm climates germinated rather slowly compared to seeds from cold climates. These inte- and intra-specific adaptation manners in the temperature members of the genusDioscorea are entirely different from those of many other plant genera reported by some workers.     

Life history characteristics ofPolystichum tripteron with special reference to its leaf venation

An intra-species comparison of the life history of various populations ofPolystichum tripteron was undertaken in Hokkaido and Honshu in Japan with respect to some leaf-size characters and fertility during sporophyte development. The developmental process of sporophytes was quantitatively estimated by counting the number of venation (NV: number of midrib branches of the leaf). The mean NV of the fertile leaves decreased slightly with increasing altitude on Mt. Teine near Sapporo and with increasing latitudes from Honshu to Hokkaido. The blade length was longer at any NV in Hokkaido populations than in those of southern Honshu. Longer blade (BL) and pinna length (PL) and lesser number of pinnules of the lowest pinna (NPLP) versus NV were observed in leaf populations from Hokkaido than in those from southern Honshu. The maximum values of lowest pinna length (LPL), NV, number of costa branches (NVLP) and number of pinnule (NPLP) were larger in southern Honshu than in Hokkaido. In the course of leaf-shape formation represented by the ratio of PL to BL versus NV, the Kyoto population seemed to be more differentiated into long-lanceolate fronds than did the Hokkaido population. Initiation of fertility in the sporophyte development and the maximum NV seemed to decrease with increasing altitudes and latitudes in Japan. Contribution No. 2885 from the Institute of Low Temperature Science, Hokkaido University.     

GEOGRAPHIC DIFFERENCES IN THE SEED GERMINATION OF PAPER BIRCH (BETULA PAPYRIFERA)

The effects of light and temperature on germination of paper birch (Betula papyrifera Marsh.) were examined in seeds from different geographic locations. Under continuous light at 14–18 C northern seed sources germinated more rapidly and achieved higher germination percentages than southern ones. Seed source influenced the range of temperatures over which germination occurred. Northern seeds had a wider temperature range than southern ones due to depression of the low temperature limit in northern seeds. At 15 C, seeds exhibited a photoperiodic-like response with progressive increases in germination as daily photoperiod was increased. This was not a true photoperiodic effect because seeds responded to the total amount of light rather than to the relative length of light and dark periods. It is suggested that at temperatures near 15 C, this response may be important in preventing fall germination. Prechilling at 3 C promoted subsequent dark germination in most seed sources tested, and northern seeds were much more sensitive to the treatments than southern seeds. In some seeds the prechilling stimulus was lost with protracted storage at 3 C; this was observed in both northern and southern seeds. Prechilling enhanced the seeds’ sensitivity to subsequent light. Although acquisition of the prechilling stimulus does not serve to measure the length of winter in these seeds, the high light sensitivity induced by prechilling probably accelerates spring germination. Northern seeds typically had thinner, more translucent pericarps than their southern counterparts.     

Adaptation of red clover rhizobia to low temperatures

Summary Red clover Rhizobium strains, isolated from different locations between latitudes 60° and 63°30′ N in Finland, were tested for their adaptation to low temperatures. 31 strains were tested for growth at 5°C, 10°C, 15°C and 18°C in pure culture. No strain grew at 5°C. At the other temperatures there were differences between the strains, but the same strains grew fast at all temperatures. Ten strains were investigated for nodulation and acetylene reduction in phytotrons in two different climates, one simulating the growing season in southern and the other in northern Finland. There were differences between the strains in their ability to nodulate their host plant, and northern strains showed higher nitrogenase activity than southern strains in the cold climate.     

Genetic Variation in Wild and Hatchery Stocks of Suminoe Oyster (Crassostrea ariakensis) Assessed by PCR-RFLP and Microsatellite Markers

Genetic variation in wild Asian populations and U.S. hatchery stocks of Crassostrea ariakensis was examined using polymerase chain reactions with restriction fragment length polymorphism (PCR-RFLP) analysis of both the mitochondrial COI gene and the nuclear internal transcribed spacer (ITS) 1 region and using 3 microsatellite markers. Hierarchical analysis of molecular variance and pairwise comparisons revealed significant differentiation (P < 0.05) between samples from the northern region, represented by collections from China and Japan, and 2 of 3 samples from southern China. PCR-RFLP patterns were identified that were diagnostic for the northern (N-type) and southern (S-type) groups. Microsatellite marker profiles were used to assign each oyster to one of the two northern or two southern populations. Results for more than 97% of the oysters were consistent with the PCR-RFLP patterns observed for each individual in that oysters with N-type patterns were assigned to one of the northern populations and those with S-type patterns to one of the southern populations. At one site of the Beihai (B) region in southern China a mix of individuals with either the N-type or S-type PCR-RFLP genotypes was found. No heterozygotes at the nuclear ITS-1 locus were found in the sample, possibly indicating reproductive isolation in sympatry. Microsatellite assignment test results of the B individuals were also consistent with identifications as either the N-type or S-type based on PCR-RFLP patterns. The parental population for one hatchery stock was this B sample, which initially was composed of almost equal numbers of northern and southern genetic types. After hatchery spawns, however, more than 97% of the progeny fell into the northern genetic group by PCR-RFLP and microsatellite assignment test analyses, indicating that the individuals with the southern genotype contributed little to the spawn, owing to gametic incompatibility, differential larval survival, or a difference in timing of sexual maturity. Overall, results suggested that oysters collected as C. ariakensis in this study, and likely in other studies as well, include two different sympatric species with some degree of reproductive isolation.     

Phylogenetic diversity of indigenous cowpea bradyrhizobia from soils in Japan based on sequence analysis of the 16S-23S rRNA internal transcribed spacer (ITS) region

Cowpea [Vigna unguiculata (L.) Walp.] is an important legume crop and yet its rhizobia have not been well characterized in many areas. In the present study, sequence analysis of the bacterial 16S-23S rRNA internal transcribed spacer (ITS) region was performed to characterize genetically 76 indigenous cowpea rhizobia from five different geographic regions (Okinawa, Miyazaki, Kyoto, Fukushima and Hokkaido) of Japan. The sequence analysis clustered all isolates in the genus Bradyrhizobium. They were conspecific with B. japonicum, B. yuanmingense, B. elkanii and Bradyrhizobium sp., although none of them grouped with B. liaoningense, B. canariense, B. betae or B. iriomotense. B. yuanmingense was only isolated from the southern region (Okinawa) where it achieved the highest frequency of 69%. B. japonicum was predominant at Miyazaki, Fukushima and Hokkaido with more than 60% of the isolates. B. elkanii was mainly recorded in the southern (Okinawa: 31%, Miyazaki: 33%) and middle (Kyoto: 33%) regions. This species was present at a very low frequency in Fukushima and absent in Hokkaido in the northern area. Bradyrhizobium sp. like-strains were absent in the southern part (Okinawa, Miyazaki) but were concentrated either in the middle regions with 67% of Kyoto isolates and 28% of Fukushima isolates, and in the northern region with 40% of the Hokkaido isolates. This study revealed a geographical distribution of cowpea bradyrhizobia which seemed to be related to the differences in the environmental characteristics (soil type and soil pH, temperature, climate, moisture) of the different regions in Japan.     

Geographical distribution and genetic analysis of phenol color reaction in foxtail millet,Setaria italica (L.) P. Beauv.

Summary Phenol color reaction was examined in a total of 376 strains of foxtail millet, Setaria italica (L.) P. Beauv., collected from different areas throughout Eurasia. Positive and negative phenotypes, and no intermediate type could be recognized by the phenol color reaction. Of 376 strains examined, 50 were positive, 319 were negative, five were mixtures of both phenotypes, and the coloration in two strains with blackish lemmata and paleae could not be distinguished. The strains that showed the positive phenotype of phenol color reaction were found in rather limited regions, while those with the negative phenotype occurred in almost all the regions. The positive phenotype occurred more frequently in the lower latitudinal regions of Asia. Genetic analysis of the F₁ and F₂ generations between the two phenotypes showed that the phenol color reaction is controlled by a single gene, and that the positive phenotype is dominant.Contribution No. 28 from the Plant Germ-plasm Institute, Faculty of Agriculture, Kyoto University, Kyoto (Japan)     

Electrophoretic evidence for the origins of tetraploids and hybrids ofSphenomeris chinensis sensu lato (Lindsaeaceae) in Japan

Hypotheses for the origins of tetraploids and hybrids ofSphenomeris chinensis sensu lato in Japan were tested using electrophoretic analysis of isozymes. Comparison of banding patterns supported the hypothesis that plants having abortive spores had resulted following hybridization between diploidS. chinensis var.chinensis andS. biflora and between diploid var.chinensis andS. gracilis. Results from isozymic analyses also revealed thatS. intermedia probably originated through allotetraploid speciation following hybridization between var.chinensis andS. biflora. There were two electrophoretic variants among tetraploids ofS. chinensis. One variant, restricted to the southern Ryukyu Islands, is probably an allotetraploid of hybrid origin between diploidS. chinensis andS. gracilis. It has been described as a new species,S. yaeyamensis Lin, Kato & K. Iwatsuki. The other variant, morphologically corresponding to var.chinensis, is distributed at least throughout southern Japan and also in northern Thailand. Its origin is uncertain, but one of the parents is probably diploidS. chinensis. Sphenomeris intermedia andS. yaeyamensis occur inland, whereas the parentalS. biflora andS. gracilis are halophilous and rheophllous, respectively.     

Ambrosiozyma kamigamensis sp. nov. and A. neoplatypodis sp. nov., two new ascomycetous yeasts from ambrosia beetle galleries

Two new yeast species of the genus Ambrosiozyma are described on the basis of comparison of nucleotide sequences of large subunit of ribosomal DNA D1/D2 region. Ambrosiozyma kamigamensis and Ambrosiozyma neoplatypodis differ from Ambrosiozyma ambrosiae by 17 nucleotides (3.0%) and 16 nucleotides (2.8%), respectively, out of 565. The two species differ from each other by 13 nucleotides. Ambrosiozyma kamigamensis was isolated from galleries of the ambrosia beetle, Platypus quercivorus, in specimens of Quercus laurifolia and Castanopsis cuspidata located in the southern part of Kyoto, Japan. Ambrosiozyma neoplatypodis was isolated from similar material, but only in Q. laurifolia. Ambrosiozyma kamigamensis can be distinguished from the other Ambrosiozyma species by the inability to assimilate erythritol, whereas A. neoplatypodis can be distinguished by the ability to assimilate both L: -arabinose and nitrate. The type strains of A. kamigamensis and A. neoplatypodis are JCM 14990(T) (=CBS 10899(T)) and JCM 14992(T) (=CBS 10900(T)), respectively. This is the first report of new Ambrosiozyma species since the genus was proposed.     

Environmental and behavioral conditions of bathing among elderly Japanese

This study investigated the bathing conditions of elderly Japanese, and sought to find factors relating to regional differences in death rates from bathtub accidents. A questionnaire survey was carried out in 11 areas of Japan. Questionnaires including questions regarding the length of time since houses had been built, types of facilities, and subjects' indoor thermal sensations and behavior while bathing were distributed to detached houses in each area twice, once in summer and once in winter. Completed questionnaires were collected from approximately 160 elderly people over 65 years old. Information regarding thermal sensations of rooms in winter revealed that a prefabricated bath and insulating window glass eased the cold in the bathroom. Unexpectedly, more subjects in the southern region than in the northern region reported being cold or a little cold while bathing in winter. In the present study, thermal sensations and behaviors while bathing seemed to be more affected by facilities and the location of houses than by the sex and age of the subjects.     

Further studies on the red cell glycolipids of various breeds of dogs. A possible assumption about the origin of Japanese dogs

Genetic polymorphism was observed in the sialic acid species constituting the terminal sugar residues of hematosides from dog erythrocytes. One was N-acetylneuraminic acid and the other phenotype was N-glycolylneuraminic acid, regulated by an autosomal dominant allele (Yasue, S., Handa, S., Miyagawa, S., Inoue, J., Hasegawa, A., & Yamakawa, T. (1978) J. Biochem. 83, 1101-1107). In this study we analyzed blood samples from 1,591 dogs of 36 breeds and demonstrated that the expression of N-glycolylneuraminic acid was limited to several breeds of oriental dogs in spite of its dominant nature. Moreover, the incidence of N-glycolylneuraminic acid was higher in native breeds of northern China, Korea and the southern part of Japan than in other oriental breeds. On the other hand, the Hokkaido-dog is unique in not expressing N-glycolylneuraminic acid. These results suggest that the native breeds in the southern part of Japan came from northern China via the Korean peninsula in contrast with indigenous breeds of the northern part of Japan.     

Frond elongation rates of shallow waterMacrocystis pyrifera (L.) Ag. In northern Baja California,Mexico

Macrocystis pyrifera (L.) Ag.frond elongation rates were measured during autumn-winter, spring and summer in a shallow water (7.5 m depth) kelp bed in Bahía Papalote, northern Baja California. Frond elongation was maximum during spring and minimum during winter. Frond growth was significantly correlated with solar radiation, and was highest in the smallest size fronds (0–2 m). Average frond elongation rate varied between 0.3–11% d^–1 during the study period. The relationship between average frond length and elongation rate followed an exponential curve with a negative slope during autumn-winter and summer, but was best described by a straight line during spring. Standard growth rates were obtained by a graphic method. Standard growth rates had intermediate values between those reported for southern California and southern Baja California.M. pyrifera growth cycle shows a different trend from what has been previously reported.     

Geographic structuring of chloroplast DNA genotypes inTiarella trifoliata (Saxifragaceae)

Tiarella trifoliata comprises varietieslaciniata, trifoliata, andunifoliata, and is distributed from southeastern Alaska to northern California. We analyzed restriction site variation of chloroplast DNA (cpDNA) using 23 endonucleases in 76 populations representing the entire geographic range of the species and the three recognized varieties. We also employed comparative restriction site mapping of PCR-amplified chloroplast DNA fragments using 16 restriction endonucleases. This species exhibits low cpDNA restriction site variation. No differentiation is evident among varieties of this species based on cpDNA data; some plants of each variety were characterized by each of the two major cpDNA types detected. The two major cpDNA clades, which differ by only a single restriction site mutation, are geographically structured. A northern clade comprises populations from Alaska to central Oregon; most populations analyzed from southern Oregon and California form a southern clade. Populations that possess the typical northern cpDNA type also occur disjunctly to the south at high elevations in the Siskiyou—Klamath Mountain area of southern Oregon and northern California. Conversely, the southern cpDNA type is found disjunctly to the north in the Olympic Peninsula of Washington. Both geographic areas characterized by disjunct cytoplasms are considered glacial refugia.Tiarella trifoliata joins two other species,Tolmiea menziesii andTellima grandiflora, in having well-demarcated northern and southern cpDNA lineages. All three species have similar life-history traits and geographic distributions. We suggest that glaciation may have played a major role in the formation of the cpDNA discontinuities present in these three taxa. The pronounced relationship between cpDNA variation and geographic distribution suggests the potential applicability of intraspecific phylogeography to plants via the analysis of intraspecific cpDNA variation. These three examples also join a rapidly growing data base which indicates that cytoplasms are often geographically structured within species and species complexes.     

Life history and population dynamics of the western mosquitofish: a comparison of natural and introduced populations

Life history and population dynamic patterns of Gambusia affinis in southeastern Louisiana varied spatially and temporally in 1990 and 1991, but were consistent with previous reports of this species in the southern regions of its natural range. Several differences exist among populations in different geographic regions within the United States, as reported in the literature, which do not follow a' native v . introduced' dichotomy: (1) brood size decreases and offspring size increases from north to south; (2) large overwintered females in northern areas produce more broods within a season than those in southern populations, while the reverse is true for young-of–year females; (3) minimum size at first reproduction follows a seasonal pattern within populations, but tends to be smaller in southern and larger in northern and Hawaiian populations; (4) synchronous reproduction early in the season is characteristic of northern populations, but does not occur in southern areas; and (5) mosquitofish reproduce year–round in Hawaii, while 'southern' populations within the continental U.S. cease reproduction during winter.     

Geographic Variations in Dorsal and Anal Ray Counts of Juvenile Japanese Flounder, Paralichthys olivaceus, in the Japan Sea

Meristic counts of early and late wild settled juveniles of Japanese flounder, Paralichthys olivaceus (Paralichthyidae), in Wakasa Bay, Japan, were compared, with specimens collected from 26 sites spread along ca. 1700km of coastline facing the Japan Sea. Mean dorsal and anal ray counts of the early settled group at Kyoto were significantly larger than those of the late settled group. A discontinuous geographic boundary in mean dorsal and anal ray counts was found around Wakasa Bay and the Noto Peninsula with both means significantly larger in the southern group than in the northern group. Mean ray counts of the early and late settlers at Kyoto were similar to those of the southern and northern groups, respectively. The effect of water temperature on meristic characters was tested on two groups of laboratory-reared juveniles. Mean dorsal and anal ray counts were larger in juveniles reared at higher water temperatures. The early and late settler groups were estimated to hatch in late February and late April, respectively, representing negative response of meristic characters to water temperatures if these two groups hatched out in Wakasa Bay. Differences in the dorsal and anal ray counts between the early and late settled groups at Kyoto can, therefore be attributed to genotypic, not phenotypic variation. This suggests the possibility of transport of larvae of the early group from areas further south to Wakasa Bay by the warm Tsushima Current, a branch of the Kuroshio, which flows northeastward along the coast of the Japan Sea, particularly when the temperature gradation between the south and north areas during these seasons is considered.