Formation of the Neural Plate and the Mesoderm in Normally Developing Embryos of Xenopus laevis

Normally developing embryos of Xenopus were fixed at various stages between the blastula and early tail bud stage, and their serial sections were examined. The marginal belt of the blastula was characterized by abundance of cells with RNA-rich peripheral cytoplasm called mesoplasm. At the early gastrula stage, the marginal belt was folded into two layers giving rise to mesodermal material and marginal ectoderm. During gastrulation, the mesodermal material, which consisted of RNA-rich cells, spread to enclose the blastocoel and the endoderm, and a large part of it was shifted to the dorsal side of the embryo. It gradually established the mesodermal layer. The notochord was formed on the dorsal lip of the blastopore by involution, separately from preformed mesodermal material. The RNA-rich cells in the marginal ectoderm became columnar, forming a broad belt in the marginal zone. This belt was deformed and shifted to the dorsal side during gastrulation, eventually establishing the neural plate showing quantitative differentiation along the head-tail axis. Possible mechanisms involved in the formation of the neural plate and mesoderm were discussed with reference to the organizer and the mesoplasm.     

Light Actions in the Germination of Cocklebur Seeds: III. EFFECTS OF PRE-TREATMENT TEMPERATURE ON GERMINATION RESPONSES TO FAR-RED LIGHT AND ON DARK GERMINATION IN THE RED LIGHT-REQUIRING UPPER SEEDS

Esashi, Y., Oota, H., Saitoh, H. and Kodama, H. 1985. Lightactions in the germination of cocklebur seeds. III. Effectsof pre-treatment temperature on germination responses to far-redlight and on dark germination in the red light-requiring upperseeds.—J. exp. Bot. 36: 1465-1477. Red light (R) responsiveness in R-requiring upper cocklebur(Xanthium pennsylvanicum Wallr.) seeds changed in differentpatterns during a soaking period at different temperatures.At temperatures above 23°C, the responsiveness increasedand then decreased. At lower temperatures (3–18°C),however, it continued to increase throughout an experimentalperiod. The lower temperatures caused germination in the subsequentdark at 33°C, regained the R responsiveness and acquiredthe dark germinability when subsequently exposed to 8°C,to an extent proportional to the duration of the chilling. Far-red (FR) was inhibitory to germination in an earlier soakingperiod at lower temperatures, but its effect gradually decresed,and finally turned promotive. The negative FR response was repeatedlycontrolled by the following R irradiation. However, the positiveFR response was enhanced by an immediate R irradiation, andFR/R reversibility occurred after the second FR. In contrastto the R responsiveness and dark germinability, the positivegermination response to FR was not induced by soaking at 3°C,in which the growth of the axial tissue as a photoreceptivesite did not occur at all. Similarly, it was not manifestedwhen the seeds soaked at 33°C were subsequently subjectedto 8°C. Key words: Cocklebur seeds, dark germination, far-red light, low temperature, red light, seed germination, Xanthium pennsylvanicum     

Purification of Acetylcholinesterase from Sea Urchin (Hemicentrotus pulcherrimus) Embryos by Affinity Chromatography

Only one form of acetylcholinesterase (AchE) was detected in Hemicentrotus pulcherrimus embryos. In H. pulcherrimus embryos as well as in the other sea urchin embryos, AchE activity begins to increase rapidly after gastrula stage.
Purification of AchE from plutei has been carried out by the procedure including affinity chromatography. Purified AchE had the activity 14,600 times higher than that of homogenate, and the final yield of AchE was 8%. The enzyme seems to be electrophoretically homogeneous, and has a molecular weight of 3 × 10⁵ as determined by Sepharose CL–6B column chromatography.     

Spiral Motion of Paramecium caudatum in a Small Capillary Glass Tube

SYNOPSIS. The behavior of Paramecium caudatum in small capillary glass tubes was investigated under various ionic conditions and at the various tube diameters. Along the inner walls of the tubes ciliates undergo regular spiral motion, which is completely different from natural spirallings or random walk-like movements observed usually in large vessels. The curvature calculated from the tracks of spiral motions was independent of the inner diameters of capillary tubes, but depend specifically on ionic conditions.
A plausible law governing such regular spiral motions of Paramecium caudatum is proposed. A definite part of the anterior end of a ciliate seems to contact the curved surface of the inner wall of a capillary tube during the motion so that the organism receives a constant tactile stimulus, and the direction of motive force keeps a certain angle against the surface.     

PROTEINS OF WHEAT EMBRYOS IN THE PERIOD OF VERNALIZATION

1. Soluble proteins prepared from non-vernalized and vernalizedwheat embryos were investigated by means of column chromatographyand disc electrophoresis. As vernalization proceeded, new proteinswere detectable as the fastest moving electrophoretic bandsor as the new peaks which were eluted with 0.025 M and 0.05M phosphate buffer (pH 7.0) from DEAE-cellulose. Plumule wasfound to be the part of embryo in which these proteins appear.After vernalization, protein pattern of winter wheat embryowas very similar to that of spring wheat embryo.
2. Histoneswere prepared from non-vernalized and vernalized wheatembryosand their chromatographic patterns were investigated.Winterwheat embryo showed more complicated pattern than didspringwheat embryo. Upon vernalization, histone pattern ofwinterwheat embryo became less complicated and similar to thatofspring wheat embryo.

(Received October 4, 1966; )     

Isotricha jalaludinii N. Sp. Found from the Rumen of Lesser Mouse Deer, Tragulus javanicus, in Malaysia

Isotricha jalaludinii n. sp. found in the rumen of lesser mouse deer, Tragulus javanicus, in Malaysia was described and illustrated. This new species is characterized by the location and direction of the vestibulum, shape of the macronucleus, and absence of a dent at the vestibular opening. The presence of single peculiar isotrichid species in the rumen of mouse deer, which is recognized as one of the most primitive ruminants, suggests that the isotrichid ciliates similar to I. jalaludinii and Isotricha intestinalis were established at a fairly early period during the evolution of ruminants.     

On linking multiyear biometric measurements of tree growth with eddy covariance-based net ecosystem production

Annual measurements of the diameter growth and litter fall of trees began in 1998 using a 1.0 ha permanent plot beneath a flux tower at the Takayama flux site, central Japan. This opened up an opportunity for studies that compare the interannual variability in tree growth with eddy covariance-based net ecosystem production (NEP). A possible link between multiyear biometric-based net primary production (NPP) and eddy covariance-based NEP was investigated to determine the contribution of autotrophic production and heterotrophic respiration (HR) to the interannual variability of NEP in deciduous forest ecosystems. We also defined the NEP^* as the measurable organic matter stored in an ecosystem during the interval in which soil respiration (SR) measurements were taken. The difference of biometric-based NEP^* from eddy covariance-based NEP within a given year varied between 55% and 105%. Woody tissue NPP (stems and coarse roots) varied markedly from 0.88 to 1.96 Mg C ha⁻¹ yr⁻¹ during the 8-year study period (1999–2006). Annual woody tissue NPP was positively correlated with eddy covariance-based NEP ( r ²=0.52, P <0.05). However, neither foliage NPP ( r ²=0.03) nor HR ( r ²=0.06) were correlated with eddy covariance-based NEP. Therefore, it was hypothesized that interannual variability in the ecosystem carbon exchange was directly responsible for much of the interannual variation in autotrophic production, especially carbon accumulation in the woody components of the ecosystem. Moreover, similar interannual variations of biometric-based NEP^* and eddy covariance-based NEP with small variations in SR and foliage NPP suggest a constant net accumulation of carbon in nonliving pools at the Takayama site.     

Isolation and characterization of polymorphic microsatellite DNA markers in the Omono type of ninespine stickleback,genus Pungitius

We isolated and characterized 25 polymorphic microsatellite loci for the Omono type of ninespine stickleback, genus Pungitius, an endangered species in streams including agricultural canals in Japan. The number of observed alleles per locus ranged from two to 15 within 32 individuals each collected from three populations in the Omono River, and the values of observed and expected heterozygosities ranged from 0.031 to 0.906 and from 0.031 to 0.856, respectively. All loci conformed to the Hardy–Weinberg equilibrium. Genetic linkage disequilibrium analysis between all pairs of the loci showed no significant departure from the null hypothesis between any of the loci.     

β-Lactoglobulin Suppresses Melanogenesis in Cultured Human Melanocytes

The effects of whey proteins from bovine milk on melanogenesis in cultured human melanocytes were examined. Among the major protein components of milk whey including β-lactoglobulin (BLG), α-lactalbumin, serum albumin, and IgG, only BLG exhibited the depigmenting effect at a concentration of 1 mg/ml. Also, BLG suppressed the activity of tyrosinase in these cells. Retinol, to which BLG is known to bind, slightly increased the pigmentation of the cells at concentrations in the range of 1–100 nM, and retinoic acid, a metabolite of retinol, exhibited a strong pigmentation-promoting effect within the same concentration range. Treatment of the cells with 1 mg/ml BLG completely abrogated the pigmentation induced by these A vitamins. These results demonstrate a novel biological activity of BLG and suggest that this activity is dependent on its ability to bind retinol.     

Oculocutaneous Albinism in the i6 Mutant of the Medaka Fish is Associated with a Deletion in the Tyrosinase Gene

Three mutant alleles (i¹, i⁴, and i⁵) of the tyrosinase gene in the i locus of the medaka fish Oryzias latipes have hitherto been described, all being associated with transposable element insertion. We have recently identified another allele causing a complete albino phenotype in homozygous carriers and named it i⁶. Sequence comparison between the tyrosinase gene for the i⁶ allele (Tyr-i⁶) and the wild-type gene previously obtained (Tyr-i ⁺) revealed three deletions of 8, 44, and 245 bp. The first two deletions reside in an intron and are differences in the number of tandem tetranucleotide repeats that are polymorphic even among wild-type genes, and, thus, not likely to be responsible for the i⁶ albino phenotype. The largest deletion spans over the last 180 bp of the second intron and the first 65 bp of the third exon. Because of this deletion, the Tyr-i⁶ gene lacks the branch point sequence and the acceptor site for the second intron, both being considered to be necessary for normal RNA splicing. Therefore, the 245-bp deletion is likely to be responsible for the albino phenotype. With a mutant gene of this type, unlike ones bearing transposable element insertions, the possibility of reversion mutations to the wild-type would be negligible. Therefore, fish having the i^e/i⁶ genotype should serve as superior recipients for the tyrosinase gene in rescue experiments.