Is proteolysis dependent on phosphorus in fresh water?

Abstract HPA proteolytic assay was used to study the dependence of proteolysis on phosphorus in fresh water. Inorganic phosphate (P_i) stimulated the growth of bacteria producing proteases in water when P was limiting factor, but did not affect the biochemical activity of enzymes which were P-in-dependent. In proteolytic assays, bacteria utilised nitrogen and carbon from HPA. Therefore, during long incubations, significant increases in microbial biomass were observed. The original HPA procedure [12] gives artificial and non-realistic values of proteolytic rates in aquatic habitats due to accelerated and uncontrolled bacterial growth and enzyme production during the assay. The use of toluene to prevent microbial growth in HPA assays is recommended [10].     

Control of phosphorus loading and flushing as restoration methods for Lake Veluwe,The Netherlands

As a result of high nutrient loading Lake Veluwe suffered from an almost permanent bloom of the blue-green algaOscillatoria agardhii Gomont. In 1979, the phosphorus loading of the lake was reduced from approx. 3 to 1 g P.m^–2.a^–1. Moreover, since then the lake has been flushed during winter periods with water low in phosphorus. This measure aimed primarily at interrupting the continuous algal bloom. The results of these measures show a sharp decline of total-phosphorus values from 0.40–0.60 mg P.l^–1 (before 1980) to 0.10–0.20 mg P.l^–1 (after 1980). Summer values for chlorophylla dropped from 200–400 mg.m^–3 to 50–150 mg.m^–3.The increase in transparency of the lake water was relatively small, from summer values of 15–25 cm before the implementation of the measures to 25–45 cm afterwards. The disappointing transparency values may be explained by the decreasing chlorophylla and phosphorus content of the algae per unit biovolume. Blue-green algae are gradually loosing ground. In the summer of 1985 green algae and diatoms dominated the phytoplankton for the first time since almost 20 years. To achieve the ultimate water quality objectives (transparency values of more than 100 cm in summer), the phosphorus loading has to be reduced further.     

Origin and production of phosphatases in the acid Lake Gårdsjön

The activity of acid phosphatases was followed for one year in Lake Gårdsjön as well as in the inlet and the outlet of the lake. A budget of the phosphatases was calculated, including an estimation of the production of phosphatases. The phosphatase activity was also measured in two basins upstream of L. Gårdsjön: the north basin and the south basin of L. Stora Hästevatten.The acid phosphatase activity was very high compared with reported alkaline phosphatase activities in other lakes. About 95% of the phosphatases in L. Gårdsjön was produced in the lake, and the production was highest in early summer.Small Chrysophyceae (< 10 µm) probably produced the majority of the acid phosphatases in the investigated lakes, and accordingly could be favoured in environments with low phosphorus supply due to their ability to produce large amounts of phosphatases.     

Schistosoma mansoni: Characterization of two circulating polysaccharide antigens and the immunological response to these antigens in mouse,hamster, and human infections

In this study the nature and occurrence of two circulating polysaccharide antigens of Schistosoma mansoni, circulating anodic antigen (CAA) and circulating cathodic antigen (CCA), and the immunological response to these antigens in mouse, hamster, and human infections were investigated. Both CAA and CCA showed a large molecular weight range, less than 50,000 to over 300,000 for CAA and 50,000 to over 300,000 for CCA, possibly representing monomers and polymers. CAA and CCA could be purified from the trichloroacetic acid-soluble fraction of adult worm antigen (AWA-TCA) by means of DEAE ion exchange chromatography. The presence of at least two other components in AWA-TCA was shown. Both CAA and CCA were found to be gut associated, and could be demonstrated in the vomitus and in the excretory and secretory antigens of adult worms. Both antigens were present in the kidney eluates of infected hamsters, while CCA could normally be detected in the urine of these hamsters and CAA only occasionally. CAA was demonstrated in the Kupffer cells of the livers of infected mice and hamsters. Antibodies against CAA and CCA were shown in mouse, hamster, and human infections. In human infections specific IgM titers against these antigens were especially elevated in children and in recent infections of adults.     

Comparison of coenzyme F420 from Methanobacterium bryantii with 7- and 8-hydroxy-10-methyl-5-deazaisoalloxazine

Syntheses of 7-hydroxy-10-methyl-5-deazaisoalloxazine (7-HMDI) and 8-hydroxy-10-methyl-5-deazaisoalloxazine (8-HMDI) are described. The physicochemical and biological properties of 8-HMDI, in contrast to those of 7-HMDI, are very analogous to those of F₄₂₀, a coenzyme found in methanogenic bacteria.     

cis-Platinum(II)diaminodichloride-induce mutagenesis in E. coli K12: crowding depression of mutagenesis

cis-Platinum(II)diamminodichloride (cis-PDD)-induced mutations to prototrophy were studied in Escherichia coli. Mutagenesis was not detected in a recA nor in a lexA mutant, but as greater in uvrA strain than in a repair-proficient strain, at a given treatment of cis-PDD. Increasing the plating density above 10⁵ cells per plate did not give an equivalent increase in revertants per plate [crowding depression of mutagenesis (Bockrath et al., 1980)]. Growth rates were similar at different plating densities and crowdign depression of mutagenesis was observed in both excision-proficient and excision-deficient strains.

A filtrate of a plate wash from crowded plates, of either treated or untreated cultuers, further reduced the mutation frequenciews over that due to crowding depression of mutagenesis.     

Hormonal effect on glycoproteins and glycosaminoglycans in rabbit uteri

The effect of the female hormones on glycoproteins and glycosaminoglycans in uteri has been studied.The uteri taken from the ovariectomized rabbits treated with estrogen, estrogen plus progesterone, and sham administration (control) were incubated in vitro with [U-¹⁴C]glucose. Subsequently, the tissues were digested extensively with pronase, yielding crude glycan fractions. The amount and radioactivity of the crude glycan fraction increased by the treatment with estrogen, but reduced to certain level with progesterone.Separation of glycoproteins and glycosaminoglycans was achieved by stepwise elution from Dowex 1 (X2, chloride form) with increasing concentration of NaCl. The yield and radioactivity, together with the results of chemical, enzymatic, and electrophoretic studies on the resulting fractions indicated that the metabolism of a slightly acidic glycoprotein, hyaluronic acid, sulfated glycoproteins, low-sulf ated chondroitin sulfate, heparan sulfate, chondroitin 4-sulfate, and dermatan sulf ate were stimulated remarkably with estrogen, but the stimulation was restored to certain level with progesterone. The degree of the change with these hormones was, however, found to be different from each other. It was noticed that sulfated glycoproteins were the most sensitive to the hormones. On the other hand, the estrogenic stimulation of the metabolism of a neutral glycoprotein and oversulfated chondroitin sulfates was not restored with progesterone.     

A review on the effects of nitrogen and phosphorus addition on tree growth and productivity in forest ecosystems

Nitrogen (N) and phosphorus (P) inputs induced by anthropogenic activities and atmospheric N and P deposition have largely increased the availability of soil N and P in terrestrial ecosystems, which have considerably affected terrestrial carbon cycling processes. Tree growth and productivity in forest ecosystems play an important role in global carbon cycling, and determine the magnitude and direction of terrestrial carbon sequestration. Currently, a large number of field manipulation experiments have been conducted to investigate the effects of N and/or P addition on tree growth and forest productivity, but the results from these studies were inconsistent. Such inconsistent results might be affected by multiple factors, including biological, environmental and experimental variables. Here, we reviewed the present research status of the effects of N and P addition on tree growth and forest productivity in forest ecosystems based on three aspects, including the number of publications and experiments with field N and P addition, and the global distributions of these experiments. Then, we summarized the methods for assessing tree growth and forest productivity at ecosystem level in forest ecosystems, including relative growth rate and absolute increment. According to the related results, we reviewed the regulating factors that affect tree growth and productivity, and the potential mechanisms for such factors, including climate, tree size and stand age, plant functional traits (including type of tree-associated mycorrhizal fungi, N-fixation property of trees, and conservative and acquisitive functional traits), plant-microbe interaction, ambient nutrient (i.e., N and P) deposition rate, and experimental variables. Finally, we summarized the current studies, and pointed out five aspects that are urgently needed to provide further insights in future studies, including the physiological mechanism of how tree growth responds to N and P addition, the tradeoff and allocation among growth of various parts of tree under N and P addition, the role of plant functional traits in regulating and predicting the responses of tree growth to N and P addition, how the competition among trees regulates the responses of tree growth to N and P addition, and conducting long-term and coordinated distributed field experiments investigating the effects of N and P addition on tree growth and forest productivity at the global scale.