Novel Inducers and Inhibitors of Differentiation of Friend Erythroleukemia Cells: Application of an Opal Glass Transmission Method to Study of Erythroid Differentiation

The potencies of poly(ADP-ribosylation)-inhibitors in inducing erythroid differentiation of Friend erythroleukemia cells were surveyed. Picolinamide and m-aminobenzamide were newly found to be inducers, whereas compounds related caffeine did not induce differentiation. In other series of experiments some bile acids suspected of being tumor promoters were found to inhibit the differentiation like typical tumor promoters such as phorbol esters. These modifications of erythroid differentiation were detected by an opal glass transmission method. This method is simpler than any previously reported methods, and is sufficiently reliable to use in determining hemoglobin in living cells as a quantitative marker of erythroid differentiation.     

Feeding and Mating Reactivity in Paramecium multimicronucleatum

SYNOPSIS. Paramecium multimicronucleatum produced abnormal (L- and Δ-shaped) cells when cultivated in the presence of 3 mM adenine. These abnormal cells were unable to form food vacuoles in the presence of bacteria in the culture. In bacteria-rich culture, mating reactivity was not expressed in normal Paramecium ; however, it was expressed in the adenine-treated abnormal cells even in the presence of excess bacteria. The expression of mating reactivity in Paramecium was not affected by ingestion of polystyrene latex particles. These results show that the inhibition of mating reactivity in bacterized culture medium is caused by absorption of nutrients from bacteria digested in food vacuoles.     

Consequences of forest fragmentation in an understory plant community: extensive range expansion of native dwarf bamboo

Understory bamboo species are important and influential components of temperate forests in at least several parts of the world. Here we report a study testing the effect of forest fragmentation on the dynamics of the dwarf bamboo Sasa chartacea and on forest herb communities in the Tokachi plain of Hokkaido, Japan. We studied 16 forest fragments of different sizes and small plots established in these fragments to examine the relationship between the abundance of S. chartacea, landscape and environmental conditions, and forest herb communities. Sasa chartacea was more abundant near forest edges and in smaller fragments, suggesting that the species has expanded its local range and increased its abundance in response to forest fragmentation. Edge‐related changes in light and soil moisture might have facilitated this range expansion. The species richness of forest herbs was strongly negatively related to the density of S. chartacea. Because much larger variation in species richness was explained by S. chartacea density than distance to the nearest forest edge, the expansion of S. chartacea has likely excluded other understory species by competition. In addition, the density of S. chartacea significantly explained variation in the species composition of forest herbs across plots. Taken together, our results emphasize the key roles of dwarf bamboos in changing plant communities following forest fragmentation.     

Temperature-Dependent Sex Determination in Gekko japonicus (Gekkonidae, Reptilia)

The effects of temperature on sexual differentiation in early development of the gekkonid lizard, Gekko japonicus were studied. The eggs were collected within 24 hr after the oviposition and were incubated at 20, 24, 28 and 32°C. The number of eggs hatched was 14 at 24°C, 20 at 28°C and 21 at 32°C. Hatching never occurred at 20°C. The hatched lizards without Müllerian ducts were judged as males. The sex of all lizards with Müllerian ducts were identified histologically. The sex ratios, male/(male+female), were 0.07 at 24°C, 0.75 at 28°C and 0.24 at 32°C. The disparities of the sex ratio from 1/2 were statistically significant and differences in the sex ratio with various incubation temperatures were also significant. These sex ratios can probably be best interpreted by a temperature-dependent sex determination. The different sex ratios do not seem to be related to a predetermination of sex with a differential mortality.     

Pluripotency of Homozygous-Diploid Mouse Embryos in Chimeras

Pluripotency of mouse uniparental cells (complete homozygous-diploid gynogenetic) produced by embryo manipulation was examined in aggregation chimeras with normally fertilized embryos. A male pronucleus was removed from fertilized eggs by micromanipulation and eggs were diploidized with cytochalasin B. Uniparental cells that developed to 4-cell or more advanced stages were aggregated with normally fertilized 8-cell embryos and transferred to the pseudopregnant female uteri to develop to term. Among the pups, 1 female and 3 males were identified as overt chimeras by their coat color and pigmentation of the retina. Using electophoretic analysis of the isozymes, the contribution of uniparental cells in these chimeras was confirmed by findings in the major organs such as liver, brain, small intestine, kidney, spleen, heart and testis. The female chimera produced offspring derived from oocytes of uniparental origin. Our experiments verified the pluripotency of microsurgically produced mouse uniparental cells.     

Pattern and Time Course of Cleavages in Early Development of the Ovoviviparous Pond Snail, Sinotaia quadratus historica

The pattern and time course of cleavage during early development of the ovoviviparous pond snail, Sinotaia quadratus historica , in in vitro culture were investigated. The fertilized egg, 25–30 μm in diameter, underwent cleavage by repeated constriction and compaction as in blastocyst formation in mammalian embryos. The cleavage was slightly unequal and dextrally spiral, although a slight time lag in cleavages of blastomeres was observed after the 2nd cleavage. A small polar lobe was formed at the 1st cleavage, but not at the 2nd cleavage. Each cleavage proceeded very slowly under the experimental conditions, the 1st, 2nd, 3rd and 4th cleavages taking 22 hr or more, 9 hr and 10 hr, respectively. The cleavage pattern in in vitro cultures observed by light microscopy was confirmed by scanning electron microscopy.     

Transition from primary dormancy to secondary dormancy in cocklebur seeds

Abstract The transition from primary dormancy to secondary dormancy was examined using upper cocklebur (Xanthium pennsylvanicum Wallr.) seeds. The non-after-ripened seeds with primary dormancy responded to chilling, anoxia, KCN, and NaN₃ with an increase in germination. However, their maximal responses to these treatments only occurred after a period of water imbibition, probably a reflection of the increasing growth potential of the axial tissue which was accompanied by the increase in the capacities of respiration and ethylene production. On the other hand, the establishment of secondary dormancy was accompanied by a decrease in respiration and ethylene production of seeds, and in the growth potential of both axial and cotyledonary tissues. The decrease in growth potential of these tissues occurred regardless of whether they were excised from after-ripened seeds or non-after-ripened seeds. It is inferred that the primary dormancy of cocklebur seeds is a state maintained in un-germinated seeds for a long time through a spontaneous transition to secondary dormancy.     

INDUCTIVE CAPACITIES OF GLOMERULAR BASEMENT MEMBRANES AND DENTINE MATRIX

The inductive capacities of the basement membranes of calf kidney glomeruli and the dentine matrix of the incisors of 23-day rabbit fetuses were examined on the presumptive ectoderm of Triturus gastrulae. The basement membranes caused almost entirely neural induction and the dentine matrix caused mesodermal induction. These findings suggest that intercellular substances play an important role in the inductive effects of heterologous tissues.     

CELL CYCLE STUDY UP TO THE TIME OF HATCHING IN THE EMBRYOS OF THE SEA URCHIN,HEMICENTROTUS PULCHERRIMUS*

Cell cycles have been analyzed in 10 divisions up to the time of hatching in the embryos of the sea urchin, Hemicentrotus pulcherrimus. In the first 5 cleavages, division synchrony is very high. On the average, T_GC= 55.4 min, T_G1= 0 min, T_s= 12 min, T_G2=±0 min, T_M= 42 min. In the remaining 5 cleavages, T_GC becomes longer: 70 min for the 7th to 246 min for the 10th cleavage. G₁ and G₂ become definitely recognizable and become longer along with T_s. T_M stays more or less constant. Plots of the changing lengths of the four compartments (G₁, S, G₂, M) on the Y-axis against T_GC (X-axis) can be fitted to the following 4 regression equations; T_G1= 0.28T_GC - 19.7, T_s= 0.609T_GC - 15.2, T_G2= 0.104T_GC - 4.72 and T_M= 0.007T_GC+ 39.6.     

Phylogeny of Regulatory Regions of Vertebrate Tyrosinase Genes

Highly homologous DNA elements were found to be shared by the upstream regions of the mouse tyrosinase and tyrosinase related protein (TRP-1) genes. Several nuclear proteins were shown to bind to both of these upstream regions. Shared homologous DNA elements were also found in the 5’ flanking sequences of Japanese quail and snapping turtle tyrosinase genes. Shared homologous nucleotide sequences were found to be scattered like an archipelago in the 5’ upstream regions of mouse and human tyrosinase genes. Comparisons between Japanese quail and snapping turtle tyrosinase genes gave similar results. On the contrary, mammalian (mouse and human) and nonmammalian (quail and snapping turtle) tyrosinase genes did not show significant homology in their 5’ upstream regions. In contrast, coding sequences in the first exons of vertebrate tyrosinase genes and their deduced amino acid sequences were found to be highly conserved except for their putative leader sequence-coding regions.