Graph-Theoretical Analysis of Cleavage Pattern: Graph Developmental System and Its Application to Cleavage Pattern of Ascidian Egg

The skeletal structure of the embryo is represented by the graph. In the graph, the cells and the connectivities between the cells are reduced to the nodes and edges, respectively. Along cleavage history, the series of graphs is obtained. In this paper I propose a new graph developmental system(GDS) which develops the series of graphs. And I represent and analyze the cleavage pattern of the ascidian egg by GDS. In order to represent it by GDS, at first, the connectivities between the cells are labeled according to the developments of the connectivities at the next time step, and next the cells are labeled. But there are two ways of labeling the cells, then two types of GDS are defined: (1) to label according to the pattern of the connectivities of their descendant cells after two time steps (G-GDS), (2) to label according to the cell fates (C-GDS). The C-GDS of the ascidian egg produces 16 cleavage patterns at 64-cell stage non-deterministically. If some labels are distinguished at 16-cell stage, the C-GDS becomes deterministic at 64-cell stage.
GDS will be useful to simulate morphogenesis by the computer graphics.     

喜马拉雅灰包菇──相传是“喜马拉雅雪人”的一种食物

喜马拉雅灰包菇ＳｅｃｏｔｉｕｍｈｉｍａｌａｉｃｕｍＺａｎｇｅｔＤｏｉ,由Ｄｒ．ＴｅｉｚｏＯｇａｗａ采于尼泊尔境内的喜马拉雅山带,据当地居民云：该菌为喜马拉雅雪人的一种食物。所谓雪人可能是高山雪线一带的动物。本文对该菌的分类特征和雪人的有关讨论作了介绍。原模式存日本国立科学博物馆。     

Food plants and life cycle of Lymantria bantaizana Matsumura (Lepidoptera: Lymantriidae) in northern Honshu, Japan

The food plants and life cycle of Lymantria bantaizana were investigated in Iwate Prefecture, northern Honshu, Japan from 2000 to 2002. Eggs laid in July hatched approximately 10 days after oviposition. Hatched larvae fed only on Juglandaceae, Juglans mandshurica var. sachaliensis, J. regia var. orientalis and Pterocarya rhoifolia when reared in the laboratory. In field rearing, the plants of Juglans enabled the moth to complete its life cycle. Differing from all other known Lymantria species in Japan, the moth overwintered not in the egg stage but in the fifth or sixth instar larval stage. Lymantria bantaizana had eight larval instars in both sexes. Moth emergence occurred mostly in July at a field‐trapping site in Iwate Prefecture.     

Genetic diversity increases regional variation in phenological dates in response to climate change

Climate change is inducing changes in the phenological timings of organisms. Genetic diversity could influence phenological responses to climate change, but empirical evidence is very limited. We estimated the regional variation across Japan in flowering and leaf budburst dates of plants based on a dataset of phenological timings from 1953 to 2005. The observed plants' genetic diversities varied according to human cultivation. The within-species variations of phenological response to temperature as well as regional variations were less in the plant populations with lower genetic diversity. Thus, genetic diversity influences the variation in phenological responses of plant populations. Under increased temperatures, low variation in phenological responses may allow drastic changes in the phenology of plant populations with synchronized phenological timings. Our findings indicate that we should pay attention to maintaining genetic diversity of populations to alleviate changes in phenology due to future climate change.     

Effects of light, temperature and water stress on germination of Artemisia sphaerocephala

Artemisia sphaerocephala is widely used for vegetation rehabilitation, but its germination is very low after air seeding of achenes. We explored effects of light, temperature and water stress on germination. Results show that both final percent germination and germination rate were increased by temperature increment, with the highest values occurring at 15: 25°C (night: day) in dark and 20: 30°C under light. Light inhibited germination, especially at lower alternating temperatures (5: 15°C and 10: 20°C). The alternating temperature window for germination was slightly narrower under light than in dark, and germination was slower under light than in dark across the temperature range. Achenes incubated in the dark and at constant temperatures had over 80% germination at 10 to 25°C, with an optimum at 20°C. Under dark and 25μmol m^‐2 s^‐1 light flux density at 10: 20°C, final percent germination was over 94%, but if the light flux density was increased to 100 and 400 μmol m^‐2 s^‐1, final percent germination was significantly lower (64% and 38% respectively). However, achenes could keep their germination capacity for a long time (over 50 days) and germinate well after going back to the dark. Germination was also lower under water stress and few achenes germinated at ‐1.4 MPa. This was more pronounced at high and low temperatures. Given these findings and the prevailing climatic characteristics, the most suitable time for air seeding of achenes may be mid‐May.