Seasonal Changes in Nitrogen Fractions of Coptis japonica, a Temperate Forest Evergreen Chamaephyte, and their Ecological Implications

Seasonal changes in several forms of nitrogen were investigatedin Coptis japonica, an evergreen rosette hemicryptophyte intemperate deciduous forest. The concentration of total nitrogenin rhizomes and roots decreased during the period of new shootgrowth from winter to spring. In the rhizomes, total solubleprotein stored by early summer decreased gradually until winter,coupled with an increase in free amino acids. Nitrogen was largelystored in free amino acids in the roots, especially during summer.The total soluble protein in current-year leaves decreased fromspring to summer and then increased during winter. The seasonalchanges in nitrogen components were coincident with the changein light-saturated photosynthetic rates recorded in a previousstudy. The ratio of total soluble protein to total nitrogendecreased from spring to summer and then increased from latesummer to winter in the current-year leaves. In contrast, chlorophyllcontent and the ratio of chlorophyll to total nitrogen werehigher in summer than in other seasons. The results indicatethat nitrogen was used in a manner that better utilizes thevery weak light in summer and the higher light intensities inother seasons. The major component of the free amino acid poolwas asparagine, in every organ throughout the season, exceptfor the senescent leaves. Since asparagine has a high N:C ratio,we suppose that the asparagine-dominated amino acid pool isadvantageous in the carbon-limited environment of the forestfloor.Copyright 1994, 1999 Academic Press Free amino acid composition, total nitrogen, total soluble protein, photosynthesis, evergreen hemicryptophyte     

Continuous activation of primitive hematopoietic cells in long-term human marrow cultures containing irradiated tumor cells.

Human hematopoietic cells can be maintained in vitro for many weeks in the absence of exogenously provided hematopoietic growth factors if an adequate stromal cell containing adherent layer is present. We have now extended the use of this type of long-term culture (LTC) system to create a model of perturbed hematopoiesis in which human tumor cells that constitutively produce a variety of factors are co-cultured together with normal human marrow cells. In the present study, we used the human bladder carcinoma cell line (5637) because these cells were known to produce not only a variety of factors active directly on hematopoietic cells but also factors that can stimulate hematopoietic growth factor production by human marrow stromal cells. Analysis of mRNA extracted from the adherent layer and measurement of growth factor bioactivity in the medium of established LTC of human marrow containing irradiated 5637 cells, showed increased levels of interleukin-1 and -6, as well as granulocyte and granulocyte-macrophage colony-stimulating factor production by comparison to control cultures. As in normal cultures, high proliferative potential clonogenic hematopoietic cells were found almost exclusively in the adherent layer of these co-cultures, but these primitive cells were maintained in a state of continuous turnover, in contrast to control cultures where the same cell types showed the expected oscillation between a quiescent and a proliferating state following each weekly change of the medium. A similar perturbation of primitive progenitor cycling was achieved by adding medium conditioned by 5637 cells twice a week to otherwise normal LTC. The presence of irradiated 5637 cells in the LTC or the addition of 5637 conditioned medium also resulted in modest (2- to 3-fold) but sustained increases in the total hematopoietic progenitor population, as well as in the final output of terminally differentiated granulocytes and macrophages. These findings indicate that primitive hematopoietic cells in LTC can be kept in a state of continuous activation for many weeks by appropriate endogenous or exogenous hematopoietic growth factor provision and that this does not necessarily lead either to their rapid exhaustion or to a large amplification in output of mature progeny.     

Ability of various alkylating agents to induce adaptive and SOS responses: a study with lacZ fusion

We used alkA'-lacZ' and umuC'-lacZ' fused genes and determined the ability of various alkylating agents to induce adaptive and SOS responses. The degree of induction of expression of these genes was quantitatively measured by a simple colorimetric assay of beta-galactosidase activity. SN1 type methylating agents, such as N-methyl-N'-nitro-N-nitrosoguanidine and N-methyl-N-nitrosourea, were more effective inducers for the alkA than for the umuC system, while SN1 type ethylating agents, such as N-ethyl-N'-nitro-N-nitrosoguanidine and N-ethyl-N-nitrosourea, were more potent inducers for the umuC than for the alkA system. Similar but less striking effects on the two systems were obtained with SN2 type alkylating agents.     

Butyryl-CoA synthetase of pseudomonas aeruginosa —Purification and characterization

The preparation of highly purified medium chain acyl-CoA synthetase (Acid: CoA ligase, AMP-forming (EC 6.2.1.2)) from the cell extracts of $\text{Pseudomonas}\text{aeruginosa}$ is described. The enzyme is inducibly formed in the cells of the microorganism, when it is grown with butyrate as a major carbon source. The purified enzyme is homogeneous on disc gel electrophoresis. Its molecular weight is approximately 142,000, and it is possibly composed of 4 identical subunits of approximately 37,000 molecular weight and has isoelectric point of 4.3. The enzyme catalyzes the stoichiometric conversion of butyrate and CoA to butyryl-CoA in the presence of ATP and Mg²⁺. It also activates fatty acids with carbon chain lengths of 3 to 5 well, but is inactive toward fatty acids with carbon chain lengths of more than 6. The enzyme is sulfhydryl dependent and inactivated by silver and mercury compounds.     

Diurnal rhythm of uridine incorporation into RNA regulated by two light-perceiving systems in a long-day duckweed, Lemna gibba G3

A long-day duckweed, Lemna gibba G3, was found to be controlledby two lightperceiving systems; a system perceiving a prolonged,high-intensity white light and the phytochrome system, withrespect to the incorporation of radioactive uridine into RNA.When the duckweed was exposed to short or long days, the uridineincorporating activity into RNA changed diurnally reaching itshighest level at 18 hr and its lowest one at 6 hr after thebeginning of a light period. The level of maximum activity rosein proportion to an increase in the length of the light periodup to 12 hr or in light intensity up to 3000 ergs/cm²sec. Thefar-red light termination of the light period resulted in adecrease in uridine incorporation, the extent of which was constantirrespective of the length of the light period. The uridine incorporating activity changed diurnally when theduckweed was exposed to continuous light. The period lengthof the rhythm was circadian and was constant over a temperaturerange of 16° to 30°C. (Received September 1, 1975; )     

Role of virus inhibitory factor or interferon in the antitumoral effect of whole-body hyperthermia

The interferon inducing effect of hyperthermia was studied in normal and tumor-bearing mice. Circulating interferon was temporarily detected one day after subcutaneous transplantation of 1.6 X 10(6) Ehrlich's ascites tumor cells. Hyperthermia of 43.5 degrees C for 5 min did not induce the interferon formation in mice with or without subcutaneous tumor of the cells. These findings showed that the induction of interferon formation was not main cause of the hyperthermia-induced tumor inhibition.     

Fractionation of chromosomal proteins of pea seedlings using procedures which avoid denaturation

Chromatin was prepared from the buds and cotyledons of Alaskapea seedlings. The dissociated chromosomal components in thepresence of 2 M NaCl and 5 M urea were completely fractionatedinto DNA and proteins with a Bio-Gel A50 column. The proteinswere recovered by (NH₄)₂SO₄ and further fractionated into histonesand non-histone proteins using a Bio-Rex 70(Na⁺) column. Thedifference in the ratios of histones to non-histone proteinsbefore and after chromatography with the Bio-Rex 70 was lessthan 10%. The histones and non-histone proteins thus preparedshowed typical protein absorption spectra. Polyacrylamide gelelectrophoresis of histones showed that the histone compositionsin buds and cotyledon were similar, but the amount of HI histoneswas a little less in cotyledons than in buds. Unlike histones,non-histone proteins fractionated by SDS-polyacrylamide gelelectrophoresis indicated distinct differences between the twotissues. Buds had more heterogeneous non-histone proteins, atleast 13 polypeptides, than cotyledons did. On the other hand,non-histone proteins of cotyledons showed less heterogeneityand lacked proteins of high molecular weight which were foundin buds. (Received May 6, 1976; )