Purification of Protein Body-I of Rice Seed and its Polypeptide Composition

Protein body type one (PB-I) was isolated and purified fromdeveloping rice grain by a combination of sucrose density gradientcentrifugation and treatment with pepsin. SDS-PAGE analysisshowed that isolated PB-I contains several polypeptide groups,the largest having an apparent molecular size of 13 kDa andtwo smaller ones of 10 kDa and 16 kDa. The 13-kDa group wasfound to be composed of two polypeptides of slightly differentmolecular sizes, 13a (larger component) and 13b (smaller component).Most of the 13a and 13b polypeptides were shown to be largelyprolamins, although there were also some salt- and alcohol-insolublepolypeptides with an apparent molecular size of 13 kDa. It wasconcluded that PB-I is the accumulation site of rice prolamin.It was further estimated that the protein amount in PB-I accountedfor about 20% of the total protein of rice endosperm. (Received March 20, 1987; Accepted September 8, 1987)     

Modification in Cell Shape Unrelated to Cellulose Microfibril Orientation in Growing Thallus Cells of Chaetomorpha moniligera

Cellulose microfibril orientation patterns in thallus cellsof Chaetomorpha moniligera were studied, and the relationshipbetween the microfibril and the peripheral microtubule arrangementsduring cell-shape modification by colchicine was examined. Inthe cuttings from growing thalli, linearly arranged cylindricalcells developed into cask-shaped cells during 4–6 daysof culture at 27?C. In the cylindrical cells, microfibrils formingthe innermost portion of the wall were arranged alternatelyin longitudinal and transverse directions, but peripheral microtubuleswere always arranged only in a longitudinal direction. Thesefeatures were also noted in the cask-shaped cells. Colchicineat 10^–3M and 3?10^–3M accelerated both cell expansionand wall thickening with matrix deposition, but the directionsin which both microfibrils and microtubules were arranged werethe same as those of the cylindrical cells. These results indicatethat (1) the microfibril and microtubule arrangements of Chaetomorphaare not necessarily correlated, (2) changes in cell shape ofChaetomorpha are not necessarily accompanied by changes in thearrangement of cell-wall microfibrils, and (3) colchicine playsa role in the loosening and thickening of cell walls by enhancingmatrix deposition. (Received June 2, 1986; Accepted February 13, 1987)     

Di(2-ethylhexyl)phthalate enhances hepatic phospholipid synthesis in rats

The effects of di(2-ethylhexyl)phthalate, a typical peroxisomal proliferator, on the activities of key enzymes in the glycerophospholipid synthetic pathway and the incorporation of lipid precursors into liver lipids in vitro were studied periodically in rats. When di(2-ethylhexyl)phthalate was fed at the 1% level to rats, glycerol-3-phosphate acyltransferase activity increased 2-3-fold in liver homogenates and microsomes in 2-4 days. The specific activity of microsomal CTP:phosphocholine cytidylyltransferase increased by 1.5-fold, whereas the cytosolic activity was depressed. The microsomal CDPcholine:diacylglycerol cholinephosphotransferase specific activity decreased, whereas the activity in the homogenates increased, suggesting the proliferation of the hepatic endoplasmic reticulum in di(2-ethylhexyl)phthalate-treated rats. The incorporation of [1(3)-3H]glycerol or [1-14C]acetate into liver phospholipids in vitro increased in 2 days and stayed at a high level up to 12 days. The present study confirmed that di(2-ethylhexyl)phthalate induced an enhancement of phospholipid synthesis in the liver. The increase in hepatic phospholipid synthesis by this drug is presumably linked to the proliferation of peroxisomes and other intracellular membranes.     

Optical birefringence of phosphatidylcholine liposomes in gel phases

A simple and rapid method for studying optical anisotropic properties of liposomes was proposed. Intensities of transmitted light through one spherical liposome of dipalmitoylphosphatidylcholine placed between two polarizers were measured at various wavelengths by a microscopic spectrophotometer. Large increases in the intensities were observed at the prephase-transition temperature, which were caused by an increase in the birefringence of the multilayer of the liposome. The birefringence values obtained from the intensity data were about 0.020 below the pretransition temperature and 0.028 above that temperature. These values are in good agreement with the results reported for the plane samples in which lipid bilayers are stacked. The obtained values of the birefringence were far lower than the values estimated from polarizabilities. This lower birefringence is attributed to disordering of the tilt direction in the multilayer. The degree of order of the liposome multilayers calculated from the birefringence increased by 38% at the pretransition. This simple method is applicable to the study of the multilayer structure of liposomes in water.     

Cell- and tissue-specific monoclonal antibodies in eggs and embryos of the ascidian Halocynthia roretzi

To obtain specific immunological probes for studying molecular mechanisms involved in the early embryonic development of ascidians, we have produced monoclonal antibodies directed against a homogenate of larvae of the ascidian Halocynthia roretzi. Among these, we have screened monoclonal antibodies that specifically recognize cells and/or tissues of the embryo. Characterization of six epidermis-specific monoclonal antibodies (including larval tunic-specific and larval fin-specific), three muscle-specific antibodies, two endoderm-specific antibodies, one notochord-specific antibody and two monoclonal antibodies that specifically recognize trunk-lateral cells suggests that these monoclonal antibodies may be useful as markers for analysing molecular mechanisms involved in specification of these cells. Seven monoclonal antibodies characteristically stain intercellular materials of the developing embryo and may therefore be valid for studying cellular construction of the embryo. Furthermore, monoclonal antibodies that recognize components of follicle cells, perivitelline space and sperm have also been established.     

Differences in growth of transplantable ascites hepatoma among various lines of Donryu rat

A total of 48 Donryu rats from 8 colonies of 5 lines were inoculated intravenously with 10(7) cells of the ascites hepatoma strain AH 66. All the conventional rats of the lines D-1 and D-2 died between 9 and 15 days after inoculation with a good growth of implanted tumor cells. On the other hand, SPF rats of the lines A-1, B-1, C and E survived for 60 days showing complete rejection of the implanted tumor cells. A 50% of conventionalized ex-SPF rats of the lines A-2 and B-2, which had been once established as SPF colonies, and thereafter had been "re-conventionalized", rejected the tumor cells. The present observations indicate that the microbial conditions of the animal, e.g. whether the animal is SPF or not, might play an important role in the growth of the implanted ascites hepatoma.     

Determination and regulation in the pigment cell lineage of the ascidian embryo

The brain of the ascidian larva comprises two pigment cells, termed the ocellus melanocyte and the otolith melanocyte. Cell lineage analysis has shown that the two bilateral pigment lineage cells (a-line blastomeres) in the animal hemisphere give rise to these melanocytes in a complementary manner. The results of the present investigation suggest that the specification of the fate of pigment cells proceeds in two distinct steps. First, the determination of pigment lineage cells requires an inductive interaction from the vegetal blastomeres of the A-line. Cell dissociation experiments demonstrated that the inductive interaction is completed by the midgastrula stage. However, the two bilaterally positioned cells destined to become the pigment cells in the first step are still equipotent at this stage in that they can give rise to either the ocellus or otolith. Thus, they constitute what is termed an "equivalence group." In the second step, the individual fates of the two cells that compose the equivalence group are determined. Namely, one cell develops into an ocellus and the other cell develops into an otolith. Photoablation of one of the pigment precursor cells at various stages indicated that the second step of determination occurs at the midtailbud stage. It is suggested that the cue to choose one of the alternative developmental pathways may be positional information that exists along the anteroposterior axis. The second step of determination is thought to be mediated by a hierarchical interaction. In the absence of this interaction, melanocyte specification proceeds along the dominant pathway that results in the differentiation of an ocellus.