Unique Pattern of Gene Expression in the Erythroid Precursor Cells

Erythroid cells were fractionated by preformed Percoll density gradient from livers of 12.5 day old mouse fetuses. With combination of lysing of mature erythroid cells, the CFU-E (colony forming unit of erythroid) was enriched as high as 30% pure. The mRNA levels of the rt-genes previously cloned as genes expressed in the reticulocytes are estimated in the fractionated erythroid cells. These rt-genes show a drastic change in expression during erythroid differentiation; Their expression was not detectable at the CFU-E cell stage. But it reached to maximum at the polychromatic erythroblast (stage I) and then decreases with maturation. The result suggests that mRNA synthesis of these rt-genes may be induced after the stimulation of erythropoietin.     

Tissue- and Stage-Specific Expression of Sericin Genes in the Middle Silk Gland of Bombyx mori

Sericin gene expression in the middle silk glands during Bombyx mori larval development was analyzed using probes from a genomic DNA clone for 10.5 kb sericin mRNA. The 10.5 kb mRNA, the most abundant in the fifth instar, is not detected in the third feeding, fourth feeding and fourth moulting stages. It becomes detectable at 2 days of the fifth instar, and accumulates rapidly. The second major mRNA in the late fifth instar, a 9.0 kb component having a similar sequence to the 10.5 kb mRNA, becomes detectable only at 6 and 7 days of the instar by use of the repetitious coding sequence probe of the sericin clone. Using the same probe about 20 kb RNAs with a fainter intensity than that of the major mRNAs are detected. They are present extremely faintly in the third and fourth feeding stages, disappear in the fourth moulting stage, and increase in the fifth instar. Two other faint poly(A)⁺ RNA components are detected by a DNA probe containing the 5' end sequence of the sericin clone. One is 4.3 kb, and appears in the third, fourth and fifth feeding stages but not in the fourth moulting stage. The other is 3.0 kb, and it becomes detectable after 1 day of the fifth instar.     

The relation between calcium and cell wall in growing rice leaf

The percentage of pectic substances in the cell wall of riceleaf decreased with the ageing of the leaf but other componentsin the cell wall changed little during leaf growth. Cell wallcomponents were not affected by a nutritional deficiency ofcalcium. At the beginning of the growth of rice leaf, calciumin the cell wall existed only in the pectic substance fractionboth in the calcium sufficient and deficient leaves. However,in the cell wall of the mature leaf, a considerable amount ofcalcium was found in the lignin fraction. The amount of calciumin this form was larger in calcium sufficient leaves than indeficient leaves. Calcium seems to occur in two forms in the cell wall, combinedwith pectic substances and with ligneous substances. This assumptionwas further supported by calcium distribution in enzymaticallydegradated fractions of the cell wall. Calcium seems to be combined with pectic substances by a strongerchemical bond than with the ligneous substances. ¹Present address: Tohoku Agricultural Experiment Station, Omagari,Akita.     

Effects of after-ripening and gibberellic acid on the thermoinduction of seed germination in Solarium melongena

Daily alternating temperatures or a short exposure to low orhigh temperatures were necessary for the germination of eggplantseeds at the initial stage of after-ripening. But requirementsbecame less strict with the progress of after-ripening, andafter 4 to 8 months of afterripening, germination occurred easilyboth at constant (20 and 25) and daily alternating temperatures(30 for 16hrs and then 20 for 8hrs). With further progress in after-ripening, however, daily alternatingtemperatures or a short exposure to low or high temperaturesbecame again indispensable for attaining a high percentage ofgermination. The progress of after-ripening was greatly influencedby the degree of seed ripening, that is, by the period beforethe seeds were sampled from fruits after anthesis (ripening). The effect of GA on the germination of egg plant seeds varieddepending on the concentration of GA, temperature and the degreeof maturity (ripening and after-ripening) of the seeds. (Received March 8, 1968; )     

Changes in Total Nitrogen and Free Amino Acids in Stem Cuttings of Mulberry (Morus alba L.)

Changes in total nitrogen and free amino acid contents in stemcuttings of Morus alba have been studied. The fresh and dryweights and total nitrogen amounts of the parent stems of cuttingsdecreased initially after cutting. Their increase follows theformation of main roots in cuttings, suggesting that, like carbohydrates,sugars and starch, stored nitrogenous substances are used forsprouting and rooting of cuttings. Amino acids found in stems,roots and shoots are those common in other higher plants withthe exception of pipecolic acid and 5-hydroxypipecolic acid.Significant changes in the levels of asparagine, proline, arginine,-aminobutyric acid and alanine in roots, bark and wood of parentstems were observed during cutting growth, whereas those ofother amino acids remained comparatively constant; the mostpredominant amino acid in the starting materials was proline.while that in the cuttings during growth was asparagine. Theresults suggest that, among free amino acids, asparagine, prolineand arginine play the major part in storage of nitrogen in mulberry.The importance of glut-amine and asparagine in nitrogen metabolismin mulberry has been discussed.     

Early oogenesis in the ascidian Ciona savignyi

Summary

Morphology of the germinal epithelium and the early follicular oocyte in the ascidian Ciona savignyi as examined by electron microscopy. The oogenetic part of the germinal epithelium contains oocytes at two different stages and the dark and clear cells. The smaller oocyte contains synaptonemal complexes. The larger oocyte in the initial phase of growth has a conspicuous nucleolus, electron-dense materials and some mitochondria close to the nuclear envelope. The nucleus of the larger oocyte is round and has the smooth contour. The dark cell contains a relatively large nucleus and is sometimes connected to each other by an intercellular bridge. Therefore, the dark cell, which has been suggested to be the progenitor cell of two kinds of accessory cells, may be also the oogonium. The early follicular oocyte just after migration from the germinal epithelium retains most of cytological features similar to those of the larger oocyte. However, the nuclear contour of the early follicular oocyte is uneven. This difference in the nuclear contour probably indicates that such a follicular oocyte is in the second phase of growth.     

Number and size of clutch in Ptomascopus morio (Coleoptera: Silphidae: Nicrophorinae), with comparisons to Nicrophorus

Ptomascopus morio displays simpler parental care than Nicrophorus species. The effects of carcass size and clutch number on clutch size in P. morio were examined. Clutch size was related to carcass size. There was a negative correlation between number of clutch and clutch size for most sizes of carcass. Longevity of females was shorter when the carcass size was larger, such that total lifetime fecundity did not differ among carcasses of different sizes. The clutch size of P. morio was larger than that of Nicrophorus quadripunctatus. The clutch size of P. morio declined rapidly with repeated clutch production, but that of N. quadripunctatus was rather constant. This indicates that N. quadripunctatus maintains a more constant clutch size than P. morio over several reproductive attempts, although the former displays more complex parental care.