Rp Type Research Articles

Efficacy of artificial humic acid as a selective nutrient in HV agar used for the isolation of soil actinomycetes

The efficacies of various kinds of humic acid, as the source of carbon and nitrogen in HV agar reported in the previous paper, were compared to the selective isolation of soil actinomycetes. The 4 types of natural humic acid, A, B, P and Rp were prepared from different soils, and 3 kinds of artificial humic acid were made from carbohydrates and urea in our laboratory. Among the natural humic acids, type Rp, which has been reported to be associated with an initial state of humification in natural conditions, showed the greatest efficacy. However, one of the artificial humic acids, which was prepared from glucose and urea, was considered to be superior to the Rp natural humic acid: 1) The HV agar containing this artificial humic acid (HV-glucose HA agar) produced the same large number of actinomycete colonies on the plate as that of the HV agar with type Rp soil humic acid (HV- Rp agar). 2) The HV-glucose HA agar restricted the number of bacterial colonies on the plates to one-half of that on HV- Rp agar plates. 3) The quality of natural himic acids varies, whereas artificial ones are more constant and can be made in any laboratory.

Changes in Soil Organic Matter and Nitrogen Fertility during the Slash-and-Burn and Cropping Phases in Experimental Shifting Cultivation

At the experimental field for the study of shifting cultivation set up in the forest of Iriomote Island in Okinawa, changes in pH, organic matter, and nitrogen fertility of soils after forest clearing by burning and during crop cultivation were investigated. The soils were sampled at six periods, I (before forest clearing), II (immediately before burning), III (immediately after burning), IV, V, and VI (10, 20, and 30 months after burning). Tilled and nontilled and other treatment plots were laid out, and cassava was grown twice. Soil pHs rose from periods I to III or IV, and then decreased. Carbon and nitrogen contents, the amounts of mineralizable nitrogen and nitrogen mineralization percentages decreased during cultivation. The amounts of humic and fulvic acids increased from periods I to II and decreased afterwards. The increase in NH4−N due to the soil-burning effect was observed. The changes in the above-mentioned parameters during the cultivation period were greater for the first layer (0–5 cm) than for the second layer (5–10 cm), and for the tilled plots than for the non-tilled plots. The nitrification percentages which were originally very low, tended to increase with the rise of soil pH, and became very high after period III. Out of 11 soil samples taken at period III, two samples at the reburnt spots showed remarkable differences in carbon and nitrogen contents, nitrogen fertility, and humus composition compared with the others. Rp type humic acid was transformed into B or A type by reburning.

An x-ray diffraction study of humic acids

A, Rp and P type humic acids and certain related materials were subjected to X-ray diffraction analysis. In general, the soil humic acids exhibited y- and (002)-bands. A and Rp type humic acids showed (002)- and y-bands, respectively. P type humic acid exhibited y- and (002)-bands, with the former predominating with regard to the latter. The (002)-band of A type humic acids was further analyzed using the Fourier transformation method. The number of layers stacked parallel to each other was 9 on the average. The most commonly found stacking units consisted of 2 and 3 layers. The average maximum number of layers per stack was 2.66. The weight percent of stack per humic acid was up to 32. In the case of Sochicken-1 humic acid (A type) extracted from Kuroboku soil, the presence of layer stacking was confirmed by transmission electron microscopy. Based on these results, the structure of humic acids is discussed.

Chemical studies on soil humic acids

The relationship between the ultraviolet and visible absorbance and the pH value of solution of each 3 samples of A, B, and Rp type humic acids and the Pg fraction of a P type humic acid was invest...

Chemical studies on soil humic acids

Abstract The pH-dependent nature of the ultraviolet and visible absorption spectra of 39 humic acids (HAs) was investigated. Two kinds of difference absorbance, △E(pH 12.4-7) and JE(pH 7-3.5), were compared for these HAs and related substances, and their characteristics are discussed. The wavelengths at the peaks of △E(pH 12.4-7) were common to Rp type HAs and the milled wood lignin of rice straw, but not to A type HAs. The △E(pH 12.4-7) values of HAs at 600 run had no linear correlation with the phenol contents but these were approximately proportional to the absorbance of HAs at 600 run. This result suggests that the △E(pH 12.4-7) of HAs at 600 run does not depend on the phenolic content but on the amount of conjugate systems in HAs. The 4E(pH 7-3.5) of HAs at 285 and 360 nm increased linearly with increasinll absorbance at 285 and 360 nm. The chemical structures in HAs responsible for the change in absorbance with change in pH from 3.5 to 7 was presumed to increase with increasing degree of humification.

Chemical studies on soil humic acids

The levels of amino acids, phenolic substances, sugars, and total hydrolysable organic matter of 37 humic acids obtained from various types of soils were determined after acid-hydrolysis. The levels of amino acids, hydrolysable phenols and hydrolysable organic matter increased from Rp(2) type to RP(l) type, and decreased with increasing RF values among Rp(l), Po. B, and A type humic acids. Very significant positive linear correlations were found among the levels of these acid hydrolysates. Hexose an duronic acid contents decreased with increasing RF values. The linear correlations between the hexose and uronic acid contents and RF values were very high for calcareous soil humic acids but low for the humic acids from other soils. Amino acids, phenols, and sugars were the main constituents in the acid hydrolysable fraction in humic acids. It was found that absorbance at 210 nm of the acidic supernatant of the hydrolysate was useful for determining the total organic matter content.

Chemical studies on soil humic acids

The levels of alcoholic and phenolic hydroxyl, methoxyl, carboxyl, and carbonyl groups of 33 to 38 humic acids obtained from various types of soils were determined to analyze the relationships between the amounts of these functional groups and the degree of humification or the types of soils. The amounts of various oxygen-containing functional groups examined were all proven to be significantly different among the various types of humic acids by analyses of variance. During humification. generally, the carboxyl and carbonyl groups increased while alcoholic and phenolic hydroxyl and methoxyl groups decreased. Linear and logarithmic regression analyses of carboxyl group contents on RF values (optical density of the alkaline solution of humic acids at 600 nm) gave very significant positive correlations. The carboxyl group contents of Rp type humic acids and humic acids from calcareous soils were largely distributed in the upper side of the regression curve. The carbonyl group contents showed a very ...

Chemical studies on soil humic acids

Abstract Relationships between elementary compositions and types of humic acids or the "degrees of humification were studied statistically using 39 humic acids prepared from various types of soils. Mean values of C%. H%. N%, 0%, H/C, N/C, and O/C of the different types of humic acids (A. B. Rp(l), Rp(2). and Po) were compared. The elementary compositions of various types of humic acids were proven by variance analyses to be significantly distinct. Linear regression analyses of C%, H%, N%. 0%, H/C, N/C, or O/C on RF or AlogK values were also carried out on 35 humic acids excluding the P+~+++ type humic acids. The linear associations were found to be significant between C%-RF (5% level), H%-RF, H%-▵logK, H/C-RF and HIC-▵logK (0.1% level), N/C-RF(O.1% level). N%-RF(l% level), N%-▵logK N/C-▵logK(5% level), and ▵logK (1% level), while no significant relationship was found with regard to C%;-▵logK, 0%-▵logK (both 5% level) and O/C-RF and O/C-▵logK (l0% level). Carbon and oxygen contents of humic acids may be apt to reflect the different conditions of soils. The deeper the visible light absorption of humic acids and so the higher the degrees of humification, the lower the hydrogen contents of humic acids were. Though nitrogen content showed a trend similar to the trend of hydrogen content against RF values as a whole. the nitrogen content of less humified humic acids (Rp type) varied from very low to very high values. suggesting the enrichment of nitrogen into humic acid molecules in the early stage of humification. In the H/C versus O/C diagram, humic acids occupied an area reserved for the oxydation products of lignins. The area was fairly wide and “J”-shaped, that is, in the early to the middle stage of humification humic acids were arranged in the direction of dehydrogenation or demethanation, and in the later stage they were arranged in the direction of dehydration.

Studies on the humus forms of forest soils

Abstract Samples described in the previous paper were analyzed for humus composition by the method of Kumada el al,, elementary composition of humic acids, nitrogen distribution among humic acid, fulvic acid, and humin, and organic matter composition by the modified Waksman method. The samples obtained by physical fractionation from each horizon of Higashiyama soil were as follows: f1 and f2 from the L layer, f1, f2 and f3 from the F layer, f1 f2, sand, silt, and clay fractions from the H-A and A horizons. With the progress of decomposition, the following tendencies were rather clearly observed. The extraction ratio of soluble humus, amounts of humic acid and fulvic acid, and PQ, value tended to increase with some exceptions. The degree of humification of humic acid proceeded. Most humic acids belonged to the Rp type, but those of the clay fractions belonged to the B type. As for the elementary composition of humic acid, transitional changes from the Lf1 to the clay fraction of the A horizon were observed...

Aromatic constituents of humic acids released by na-amalgam reductive cleavage, koh fusion and zinc dust fusion

Abstract Eight humic acids showing different degree of humification were treated with HCI (1:1). The hydrolyzed humic acids were subjected to reductive cleavage with Na-amalgam, KOH fusion and zinc dust fusion. The yields of degradation products were determined by colorimetry gas chromatography. The perimental results Were summarized as follows: l. The amounts of ether-soluble substances obtained by reductive cleavage with Naamlagan ranged from 21.6% for Kuragari (A type) to 7.8% for Kisokoma B2 (Rp type). The yields of phenolic substances expressed in terms of vanillic acid content ranged from 3.0% for Kuragari (A type) to 1.8% for Kisokoma B2 (Rp type). Resorcinol. p.hydroxybenzoic acid, vanillic acid, protocatechuic acid and syringic acid were detected in the gas chromatograms of the ethe-soluble substances and their total yield comprised less than 0.6% of the Kisokoma F (Rp type). 2. The KOH fusion of humic acid yielded a larger amount of degradation products as compared to reductive cleavage. The amo...

Fractional determination of functional groups of humic acids by conductometric titration

The conductometric replacement titration proposed in a previous report disclosed that the functional groups of humic acids are fractionated into three clusters of different dissociation constants, designated as VW, W and S clusters. In this paper, the method was examined to ascertain the relationship between the concentration of a sample and the amounts of fractionated clusters. The total amounts of fractionated clusters as well as the amount of the S cluster were directly proportional to the concentration of the sample, whereas the amount of the VW cluster decreased a little as concentration increased. The same method, applied to various types of humic acids in Japan, showed that the sums of the functional groups and the ratios of the S cluster to the sums likewise decreased in the order of A type > B and P types > Rp type. The total acidities determined by conductometry were nearly equal to the sums of carboxyl determined by Blom's method and phenolic hydroxyl determined by Folin's method.

Studies on the humus forms of forest soils

Abstract The results of humus composition analysis of each fraction separated physically from each horizon of the five forest soils used in the last paper (3) were presented. Regular changes in humus composition were observed with the gradation of horizons and With the decrease in particle size. Most of the humic acids from plant residual fractions belonged to the Rp type; hurnic acids from the L layers showed a tannin-like character which disappeared with the progress of decomposition, and humic acids from the smaller particle fractions of the layers contained a Pg fraction. As for humic acids from the A horizon, they all belonged to the P or B type and contained a Pg fraction. In addition, it was concluded that the humification process in the mineral layer Was clearly different from that in the organic layer.

Methods for estimating Pg content in P type humic acid and for calculating ΔlogKof its Pb fraction

Abstract Based on the assumption that P type humic acid is composed of green fraction (Pg) and brown fraction (Pb),. methods for estimating Pg content and calculatlng Δlog K of Pb by analyzing the absorption curve of P type humic acid were presented. A green fraction of P type humic acid obtained from an alpine meadow soil by gel filtration was used as the Pg standard (λmax 450, 575, and 615 nm, E 1% 290, 126, and 168). Alkaline solutions of standard Pg obeyed the Beer-Lambert law within the concentration range of 1.6 to 31 ppm. To verify the methods, Pg content in the mixed solutions of Pg and A, B, or Rp type humic acid was estimated. It was found that the recovery of Pg would be 95±14 (2S) per cent with a probability of 0.99. Also, the calculation of Δlog K of humic acid in the mixed solutions gave satisfactory results. It was distinctly shown that the shape of absorption spectra of P type humic acid did not only depend on Pg content, but also on Δlog K of Pb.

Sephadex gel fractionation of humic acids

Abstract Using Sephadex G 50 gel filtration, three soil humic acids were separated into two to four fractions, which differed more or less in their spectrophotometric properties. The distribution of a humic acid fraction on an RF-Δlog K diagram was classified into two cases; in the first case, the RF increased and Δlog K decreased with the elution order, and in the second case, humic acid fractions distributed clockwise around the original humic acid. A small amount of B type humic acid was separated by gel filtration from newly formed Rp type humic acid obtained from the mixtures of grass and soil materials incubated for four months under alternate field and air-dry conditions.

Several properties of Rp type humic acid

Abstract Kumada (1) has proposed that humic acid can be grouped into four major types: A, B, Rp, and P types. Rp type is defined in his classification diagram of humic acid as the one located in the region where the value Δlog k is larger than 0.7 and RF is smaller than 40. This type of humic acid represents the main humic fraction of the following soils : Ao horizon of various forest soils, red-yellow soils and peat soils. Also, the humic fraction of farmyard manures (Kyuhi) and composts (Taihi) belongs to this type. It is presumed that Rp type humic acids are formed in the rotting processes of plant residues, and that this type of humic acid constitutes the initial stage of humification. This stage is labile and it undergoes further decomposition in soils, leading to the formation of other types of humic acid. It is therefore valuable to get information on the nature and properties of Rp type humic acid in relation to their role in soil formation and plant growth.

Analogy of electronic pacemaker and ventricular parasystole with observations on refractory period, supernormal phase, and synchronization.

The artificial pacemaker has been compared to a physiologic ventricular parasystolic focus. In hearts being driven by a pacemaker, in the absence of atrioventricular (AV) block, capture (interference) phenomena are constantly seen. While variations in QRS complexes have been observed when the external pacemaker stimulus occurs early in the T-wave period of a sinus conducted beat, no sequence of aberrant beats has been observed. One patient showed occasional sinus beats interpolated between ventricular beats arising from the artificial pacemaker, and these occurred at a very narrow time band suggesting that AV conduction was permitted by phenomenon of a supernormal phase. At a later date this patient showed also retrograde conduction believed related to a supernormal phase during recovery of junctional tissue penetrated by an impulse entering from above, though the impulse itself was blocked. Records of two patients are used to illustrate grossly aberrant QRS complexes produced by the stimulus of the electric pacemaker when this fell in the semirefractory period. Noteworthy was the presence of a latent period before potentials of the propagated impulse were recorded, there being evident stimulus-to-QRS delays. The situation wherein the rhythm is most chaotic is that where AV block is absent, the sinus rate is fast, and the electric pacemaker rate is relatively slow. In two patients, retrograde activation of the atria occurred as a stable mechanism. In one patient, nodal rhythm of the RP type occurred, and sequences of the records suggested that the AV node might have become synchronized with the extrinsic pacemaker cycle. In this last instance three independent centers of effective impulse formation coexisted, the sinus node, AV node, and stimulating electrodes of the electronic pacemaker. A marked increase in the refractory period of the ventricle, as measured by its response to the set stimulus of the electric pacemaker delivered at varying instants with respect to the sinus mechanism, occurred in one case within a few days. The possibility that reserpine therapy contributed to this change is possible but has not been established, for the effective refractory period, as measured, later remained constant over a period of many weeks.

Origin of repeats in Drosophila chromosomes

From the point of view of evolution, repeats (Rp) are the most important category of structural changes, and are assumed to provide a mechanism for the evolution of genes with new functions. An estimation of the frequency with which Rp's occur and an attempt at an understanding of the mechanism by which they originate are therefore undertaken. Rp, a type of duplication where a segment of one chromatid is inserted next to its homologous segment in the sister chromatid, are induced by x rays at a very low frequency and some chemical mutagens are capable of inducing Rp's with a high frequency. Attempts were made to deduce the mechanism responsible for the origin of Rp's from a cytological study of different types of Rp and their relative frequencies, based on x-ray and formaldehyde-induced Rp's in Drosophila melanogaster. Four types of Rp were found during cytological analysis of the effects of formaldehyde food, and all can be explained by a mechanism which requires two breaks in a still undivided chromosome; after splitting of the chromosome, these breaks result in two pairs of isochromatid breaks. Depending on the type and the number of new rejoinings, different types of Rp are formed. Allmore » of them are accompanied by the same complementary deficiencies (Df). In order to result in a Rp with complementary Df, the breaks have to fulfill special conditions. They have to be available for reunion at a time when sister chromatids are closely apposed to each other, and they must affect both chromatids at the same level. For the latter condition to arise from hits'' on the already separated chromatids would require a highly improbable coincidence, especially for a chemical mutagen. On the other hand, it would follow automatically from a previous hit on the still unsplit chromosome, if the broken ends remained available until chromatid separation. Observations on x-irradiated chromosomes show that such a delay in reunion is rare, at least for x-ray-induced breaks. Although breaks induced in spermatozoa of Drosophila remain available until after fertilization, they then rejoin quickly and ususlly before chromosome splitting, as shown by the rarity of chromatid changes, in particular of Rp's. This applies equally well to x-ray-induced breaks in premeiotic chromosomes, which hardly ever persist long enough to give Rp's a meiotic prophase. The frequency with which Rp's rise de novo without treatment is not known. In Drosophila, it is very low, but Rp's are detected only when accompanied by a dominant visible effect, e.g., duplication Bar in D. melanogaster. X rays are capable of producing Rp's but with a very low frequency (2-6.5% of all changes) compared with other structural changes induced simultaneously by the same treatment. Chemical mutagens, on the other hand, produce Rp's with a much higher frequency than other kinds of structural change. The relative frequencies of formaldehyde-induced types of change are as follows: Rp's 35.3%, Df's 25.0%, translocations 17.7%, inversions 17.7%, other changes 4.3% of all changes. It is concluded that most or all repeats arise from actual chromosome breaks, which subsequently give rise to sister chromatid breakage followed by new rejoinings. A proposed model for the origin of repeats suggests that these may arise most readily from chromosome breaks which remain latent (potential) until separation into sister chromatids. This is in excellent agreement with the fact that formaldehyde, which produces mainly potential breaks, yields a high frequency of Rp's, while x rays yield very few. (BBB)« less