Allelopathic effects of goldenrod and aster on young sugar maple

1978 ◽  
Vol 8 (1) ◽  
pp. 1-9 ◽  
Author(s):  
R. F. Fisher ◽  
R. A. Woods ◽  
M. R. Glavicic
Keyword(s):  
Sugar Maple ◽  
Water Soluble ◽  
Plant Residues ◽  
Laboratory Studies ◽  
Phosphorus Fertilizer ◽  
Old Field ◽  
Natural Plant ◽  
Allelopathic Effects ◽  
Germination And Growth

A series of field, greenhouse, and laboratory studies were undertaken to elucidate the role of allelopathy in old-field sugar maple stands. Old-field weed residue inhibited germination and growth of maple even in the absence of competing vegetation. Goldenrod and aster were important producers of water soluble compounds that inhibited germination, nutrient uptake, and growth. These allelopathic chemicals were most readily extracted from putrefied plant residues, but they appeared to be natural plant products rather than microbial breakdown products. The deleterious effects of goldenrod on nutrition and growth of maple were overcome by large additions of soluble phosphorus fertilizer.

Influence of Rye (Secale cereale) Plant Residues on Germination and Growth of Three Triazine-Resistant and Susceptible Weeds

1994 ◽  
Vol 8 (4) ◽  
pp. 744-747 ◽  
Author(s):  
T. Przepiorkowski ◽  
Stanley F. Gorski
Keyword(s):  
Seed Germination ◽  
Growth Inhibition ◽  
Secale Cereale ◽  
Plant Residues ◽  
Aqueous Extracts ◽  
Laboratory Studies ◽  
Weed Species ◽  
Shoot Tissue ◽  
Germination And Growth ◽  
Significant Growth Inhibition

Greenhouse and laboratory studies were conducted to evaluate the effects of rye residues on germination and growth of three triazine-resistant weed species, barnyardgrass, willowherb, and horseweed. Soil containing rye roots was used to determine rye residue influence on seed germination. Willowherb and horseweed germination was inhibited up to 50% with the highest rate of rye, but there was no inhibition of barnyardgrass germination. Aqueous extracts of rye shoot tissue inhibited incubator germination of horseweed and willowherb, but did not significantly influence barnyardgrass germination. Although there were no germination differences between the susceptible and resistant biotypes, both were totally inhibited when a 5% w/v solution was used. Growth inhibition of the selected weeds was evaluated using rye root residues in soil. All combinations of biotypes, species, and rye seeding rates showed significant growth inhibition.

scholarly journals Did Cyclic Metaphosphates Have a Role in the Origin of Life?

2021 ◽  
Author(s):  
Thomas Glonek
Keyword(s):  
Organic Molecules ◽  
Water Soluble ◽  
Holliday Junction ◽  
Additional Energy ◽  
Condensed Phosphate ◽  
Geological Processes ◽  
The Origin Of Life ◽  
Complex Forms ◽  
Self Replication

AbstractHow life began still eludes science life, the initial progenote in the context presented herein, being a chemical aggregate of primordial inorganic and organic molecules capable of self-replication and evolution into ever increasingly complex forms and functions.Presented is a hypothesis that a mineral scaffold generated by geological processes and containing polymerized phosphate units was present in primordial seas that provided the initiating factor responsible for the sequestration and organization of primordial life’s constituents. Unlike previous hypotheses proposing phosphates as the essential initiating factor, the key phosphate described here is not a polynucleotide or just any condensed phosphate but a large (in the range of at least 1 kilo-phosphate subunits), water soluble, cyclic metaphosphate, which is a closed loop chain of polymerized inorganic phosphate residues containing only phosphate middle groups. The chain forms an intrinsic 4-phosphate helix analogous to its structure in Na Kurrol’s salt, and as with DNA, very large metaphosphates may fold into hairpin structures. Using a Holliday-junction-like scrambling mechanism, also analogous to DNA, rings may be manipulated (increased, decreased, exchanged) easily with little to no need for additional energy, the reaction being essentially an isomerization.A literature review is presented describing findings that support the above hypothesis. Reviewed is condensed phosphate inorganic chemistry including its geological origins, biological occurrence, enzymes and their genetics through eukaryotes, polyphosphate functions, circular polynucleotides and the role of the Holliday junction, previous biogenesis hypotheses, and an Eoarchean Era timeline.

The biological activity of glucagon–phospholipid complexes

1983 ◽  
Vol 61 (7) ◽  
pp. 688-691 ◽  
Author(s):  
J. J. Liepnieks ◽  
P. Stoskopf ◽  
E. A. Carrey ◽  
C. Prosser ◽  
R. M. Epand
Keyword(s):  
Biological Activity ◽  
Adenylate Cyclase ◽  
Plasma Membranes ◽  
Bovine Brain ◽  
Water Soluble ◽  
Dipalmitoyl Phosphatidylcholine ◽  
Dimyristoyl Phosphatidylcholine ◽  
Lipoprotein Complex ◽  
Stimulation Of

Glucagon can form water-soluble complexes with phospholipids. The incorporation of glucagon into these lipoprotein particles reduces the biological activity of the hormone. The effect is observed only at temperatures below the phase transition temperature of the phospholipid and results in a decreased stimulation of the adenylate cyclase of rat liver plasma membranes by the lipoprotein complex as compared with the hormone in free solution. Two- to five-fold higher concentrations of glucagon are required for half-maximal stimulation of adenylate cyclase when the hormone is complexed with dimyristoyl phosphatidylcholine, dipalmitoyl phosphatidylcholine, or bovine brain sphingomyelin. A possible role of lipoprotein-associated hormones in the development of insulin resistance is discussed.

INHIBITION OF RESPIRATION, GERMINATION, AND GROWTH BY SUBSTANCES ARISING DURING THE DECOMPOSITION OF CERTAIN PLANT RESIDUES IN THE SOIL

1958 ◽  
Vol 36 (5) ◽  
pp. 621-647 ◽  
Author(s):  
Z. A. Patrick ◽  
L. W. Koch
Keyword(s):  
Plant Residues ◽  
Toxic Substances ◽  
Root Cells ◽  
Toxic Activity ◽  
Root Rots ◽  
High Soil Moisture ◽  
Heat Stable ◽  
Tobacco Seedlings ◽  
Ph Range ◽  
Germination And Growth

Substances capable of markedly inhibiting the respiration, germination, and growth of tobacco seedlings were obtained after residues from timothy, corn, rye, or tobacco plants had been allowed to decompose under appropriate conditions in the soil. Bio-assay tests, based on manometric methods, made it possible to determine some of the conditions under which the decomposition gave rise to phytotoxic by-products and to obtain rapidly an accurate measure of the degree of their toxicity. Among the factors influencing the production of the toxic products, the species and stage of maturity of plant material added, the water content and pH of the soil, and length of decomposition period seemed most important. Substances capable of reducing the respiration of tobacco seedlings by 50 to 90% were consistently obtained when any of the abovementioned plant residues had been decomposing for 15 to 25 days under conditions of high soil moisture and when the pH of the soil solution was below 5.5 throughout this period. Timothy gave rise to substances possessing the highest toxic activity, followed by corn, then rye, and finally tobacco. Aqueous extracts of unamended soil or of macerated plant tissues prepared either before decomposition had taken place or when decomposition was inhibited by autoclaving the soil were not toxic.The toxic substances, obtained by water extraction, exhibited an inhibiting effect on respiration of tobacco seedlings after an exposure of less than one hour and also induced darkening and necrosis of root cells. Some extracts affected the cells of the apical meristem most severely while others affected only the cells of the elongation region.While the toxic substances have not been identified, they were relatively nonspecific in their action, affecting tobacco, timothy, and barley in approximately the same manner and in many instances possessed also antifungal activity. They were soluble in water, insoluble in petroleum ether, stable in acid, and most active in the pH range 4.5 to 5.8. They were precipitated by alkali and the activity was markedly reduced when readjusted to the acid range. They were also heat stable and did not lose their activity in storage at 1°–3 °C. provided they were covered by a layer of toluene.Because of their rapid production and the marked injurious effects exerted on various plants it is believed that these toxins may perform a significant role in the field as the primary cause of some root rots and in predisposing plants to attack by organisms not normally regarded as pathogenic.

scholarly journals An Essential Role of the CAAT/Enhancer Binding Protein-α in the Vitamin D-Induced Expression of the Human Steroid/Bile Acid-Sulfotransferase (SULT2A1)

2006 ◽  
Vol 20 (4) ◽  
pp. 795-808 ◽  
Author(s):  
Chung S. Song ◽  
Ibtissam Echchgadda ◽  
Young-Kyo Seo ◽  
Taesung Oh ◽  
Soyoung Kim ◽  
...  
Keyword(s):  
Vitamin D ◽  
Binding Site ◽  
Essential Role ◽  
Binding Protein ◽  
Water Soluble ◽  
Induced Expression ◽  
Composite Element ◽  
Deoxyribonuclease I ◽  
Enhancer Binding Protein

Abstract The vitamin D receptor (VDR) regulates steroid and drug metabolism by inducing the genes encoding phase I and phase II enzymes. SULT2A1 is a liver- and intestine-expressed sulfo-conjugating enzyme that converts the alcohol-OH of neutral steroids, bile acids, and drugs to water-soluble sulfated metabolites. 1α,25-Dihydroxyvitamin D3 [1,25-(OH)2D3] induces SULT2A1 gene transcription after the recruitment of VDR to the vitamin D-responsive chromatin region of SULT2A1. A composite element in human SULT2A1 directs the 1,25-(OH)2D3-mediated induction of natural and heterologous promoters. This element combines a VDR/retinoid X receptor-α-binding site [vitamin D response element (VDRE)], which is an imperfect inverted repeat 2 of AGCTCA, and a CAAT/enhancer binding protein (C/EBP)-binding site located 9 bp downstream to VDRE. The binding sites were identified by EMSA, antibody supershift, and deoxyribonuclease I footprinting. C/EBP-α at the composite element plays an essential role in the VDR regulation of SULT2A1, because 1) induction was lost for promoters with inactivating mutations at the VDRE or C/EBP element; 2) SULT2A1 induction by 1,25-(OH)2D3 in C/EBP-α-deficient cells required the expression of cotransfected C/EBP-α; and 3) C/EBP-β did not substitute for C/EBP-α in this regulation. VDR and C/EBP-α were recruited concurrently to the composite element along with the coactivators p300, steroid receptor coactivator 1 (SRC-1), and SRC-2, but not SRC-3. VDR and C/EBP-α associated endogenously as a DNA-dependent, coimmunoprecipitable complex, which was detected at a markedly higher level in 1,25-(OH)2D3-treated cells. These results provide the first example of the essential role of the interaction in cis between C/EBP-α and VDR in directing 1,25-(OH)2D3-induced expression of a VDR target gene.

The Emerging Role of Nanosuspensions for Drug Delivery and Stability

2021 ◽  
Vol 12 ◽  
Author(s):  
Hitesh Kumar Dewangan
Keyword(s):  
Water Solubility ◽  
Size Range ◽  
Aqueous Solubility ◽  
Active Surface ◽  
Water Soluble ◽  
Active Surface Area ◽  
Specific Interest ◽  
Advanced Therapies ◽  
Processing Techniques

: Poor solubility of some medicinal compounds is a serious challenge that can be addressed by using a nano-suspension for improved delivery. The nanoparticles enhance the bioavailability along with the aqueous solubility of the drug, which is accomplished by increasing the active surface area of the drug. The gained attention of the nanosuspension is due to its stabilization facility, which is achieved by polymers, such as polyethylene glycol (PEG), having a particular size range of 10 - 100 nm. Hence, these nanoparticles have the capacity of binding to the targeted with very low damage to the healthy tissues. These are prepared by various methods, such as milling, high-pressure homogenization, and emulsification, along with melt emulsification. Moreover, surface modification and solidification have been used to add specific properties to the advanced therapies as post-processing techniques. For many decades, it has been known that water solubility hampers the bioavailability and not all drugs are water-soluble. In order to combat this obstacle, nanotechnology has been found to be of specific interest. For elevating the bioavailability by increasing the dissolution rate, the methodology of reduction of the associated drug particles into their subsequent submicron range is incorporated. For oral and non-oral administration, these nanosuspension formulations are used for the delivery of drugs.

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