Regulation of Release and Mode of Action of Crustacean Chromatophorotropins

Pigment movements in crustacean chromatophores are regulatedby pigment-concentrating and pigment-dispersing neurosecretoryhormones. The release of these hormones from the neurosecretorysystem is thought to be controlled by neural signals. Althoughthe exact cellular sources of chromatophorotropins and the natureof synaptic input to the neurosecretory system remain unresolved,recent pharmacological studies on fiddler crabs indicate thatcertain biogenic amines contribute to the release of some ofthe chromatophorotropins. The current evidence suggests that:5-hydroxytryptamine stimulates the release of RPDH (red pigmentdispersing hormone), dopamine triggers the release of RPCH (redpigment concentrating hormone), and norepinephrine stimulatesthe release of BPDH/MDH (black pigment/melanin dispersing hormone).Nothing is known of the regulation of release of leucophorotropinsand xanthophorotropins. Like most other peptide hormones, crustacean chromatophorotropinsare thought to exert their effect by first binding to receptorson the cell surface and then triggering a series of events leadingto cellular responses, but the details are far from clear. Recentwork suggests that hormone-induced pigment movements may bemodulated/mediated by alterations in cyclic nucleotide levelsand/or by changes in Ca²⁺ distribution or flux. Both cyclicnucleotides and Ca²⁺ may modulate motility by regulating theintegrity and/or function of cytoskeletal elements, but thedetails of this mechanism and the precise roles of cytoskeletalelements in the pigment-translocating process remain unresolved.     

Chemical Properties and the Physiological and Pharmacological Actions of Urophysial Peptides

Recent advances in urophysial research are reported and currentresearch in this laboratory on the urophysial peptides (urotensinI, urotensin II) of Catostomxts commersoni is summarized. UrotensinI has been purified by gel filtration, electrofocussing, ultrafiltrationand ion exchange chromatography. Three similar utotensin I peptideswere found. The main peptide was shown to be a straight chainpeptide with about 36 amino acid residues. Pressor-diureticeffects in fish have been observed. The peptide produces a long-lastinglowering of mammalian blood pressure by peripheral vasodilatation.Urotensin II has been isolated and purified. It appears to contain23 amino acids including two disulphidebridges. It is a potentpressor-diuretic-smooth muscle contracting agent in the fish,without any known pharmacological actions in mammals. UrotensinIII: the existence of this activity as a separate chemical entityhas not been established, but urophysectomy was shown to lowerblood Na⁺ without an increase in renal excretion. UrotensinIV has been shown to be similar to, or identical with, argininevasotocin. Urotensin IV could not be found in the urophysisof Catostomus (gel filtration, bioassays, immunohistochemistry).Similarities and differences between the hypothalamic and caudalneurosecretory systems and their active principles are analysed.     

Crustacean Neurosecretory Hormones and Physiological Specificity

Physiological effects of neurosecretory factors from crustaceansare examined for their hormonal specificity. Hyperglycemic hormone(HGH) from the eyestalk is a polypeptide, molecular weight about7,000; it may activate phosphorylase and inhibit glycogen synthetase. Four pigmentary effectors (distal retinal pigment, melanophores,erythrophores and leucophores) respond to a peptide hormone(DRPH) having a molecular weight of 2,000. An earlier suggestion(Kleinholz, 1970) that light-adaptation of the distal retinalpigment and dispersion of pigment granules in chromatophoresmay be regulated by the same hormonal molecule is confirmedby test with synthetic hormone. Concentrators oferythrophore(ECH) and leucophore (LCH) pigments are peptides with respectivemolecular weights of 1,000 and about 1,500 daltons. Three factors which affect succinate oxidation by mitochondriaappear in the three chromatographic zones eluted from G-25 Sephadexwhich contain DRPH, LCH and ECH, and therefore presumably areof about the same molecular size as the pigment hormones. Thesecond and third of these factors have been shown to be distinctlydifferent from the hormones with which they are initially eluted. Factors influencing hydromineral regulation, molt- and gonad-inhibition,cardiac activity, respiratory rates and lipid metabolism arereviewed.     

甲壳动物高血糖激素家族生理功能研究进展

甲壳动物高血糖激素家族是甲壳动物特有的神经多肽激素家族,主要由眼柄的X-器窦腺复合体(XO-SG)合成与分泌,包括高血糖激素(CHH)、蜕皮抑制激素(MIH)、性腺抑制激素(GIH)和大颚器抑制激素(MOIH),协同调控着甲壳动物的生长、繁殖与蜕皮等生理生化过程.本文就目前CHH家族神经肽的功能研究,包括功能研究的方法、各个激素的功能以及分泌调控等研究进展作一综述.     

Physical,Chemical and Physiological Properties of S-CM Subunits of Ricin D

Some physical, chemical and physiological properties of two S-CM subunits (S-CM Ile and S-CM Ala chain) of ricin D were studied. Physical properties of subunits are summerized in Table I. The S-CM subunits consisted of 244 (S-CM Ile chain) and 254 (S-CM Ala chain) amino acid residues. By the specific cleavage of the single intermolecular disulfide bond of ricin D, no remarkable change in conformation of polypeptide chains of ricin D was detected, but the toxicity was markedly decreased. The toxicity of ricin D is due to the quaternary structure of the ricin D molecule.     

Physiological Actions of Brassinosteroids: An Update

In general, this overview covers literature from 1999 until early 2003. Topics covered include aspects of the biosynthesis and transport of brassinosteroids, their effects on cell division, expansion, and differentiation, and their effects on whole plants, including source-sink relations and other endogenous interactions. Some interactions with environmental signals are discussed, as well as results that may promise applications in future. Topics that warrant further investigation of the roles of BRs include phenotypic variability, reproductive physiology, senescence, branching, and apical dominance, whereas topics in which possible roles for BRs are relatively unexplored include lignification, phototropism, photoperiodism, and endogenous rhythms.     

Selected Chemical and Physical Properties of Soils and Gut Physiological Processes that Influence Lead Bioavailability

Abstract

This paper considers selected field examples of physical and chemical properties of soil and some of the interactions with gut physiological processes that are related to lead bioavailability. The blood lead response to quantity of lead in mining and milling environments compared with urban and lead smelter conditions appears to be different. The emphasis of this paper is to understand the complexity of the urban environment.

Bioavailability appears to be related to physical and chemical qualities other than mere quantity of lead. Particle size is one physical quality that influences bioavailability. Compared to intact lead—based paint, small particle emissions from vehicles govern the general soil lead pattern in urban environments. Lead has accumulated in soils in proportion to city size, with the inner—city generally measuring the highest lead levels. The soil lead situation is further exacerbated by the chemical influence of other toxic substances such as zinc. In several cities, zinc levels of 1,500 ppm and higher, plus acid conditions (pH 5.4 and lower) have been observed. This condition is phytotoxic to plants and the deficiency of plant cover increases the likelihood for soil lead ingestion. After ingestion, nutritional status becomes an important factor with both iron and calcium deficiencies increasing lead bioavailability.

To complement the other discussions of the Gl tract and bioavailability in this volume, the following physiological responses of the gut that either increase or decrease soil lead bioavailability are described: (1) The role of the ‘normal’ microbial flora in altering baseline gut function, (2) effect of pH, (3) intestinal transit time, (4) role of mucus, and (5) barriers to lead transport. Physiologically there are nine physical and/or chemical barriers to soil lead absorption which tend to decrease bioavailability: any breakdown of or increased permeability in these barriers would have the opposite effect. The addition of a soil amendment, such as pathogen free processed sludge, would be expected to be a practical means for reducing soil lead bioavailability. The amendment should serve to bind lead and thus increase effective particle size. It would also have the benefit of improving plant growth as shown in the laboratory. Further study is needed to conduct toxicity testing and undertake field evaluation.     

苦荞麦的化学成分和药理作用

苦荞麦主要含黄酮类、有机酸类、氨基酸、多肽、蛋白质、微量元素等。具有防治心脑血管疾病、糖尿病、抗菌消炎、抗乙肝表面抗原等作用。     

大黄的化学成分及药理作用研究进展

大黄在我国传统医学中应用已久,是一味功效诸多,且药效显著的中药,临床应用十分广泛。现对大黄化学成分、结构及药理作用进行综述,并对大黄应用前景进行展望。     

沙苑子的化学成分和药理作用

沙苑子主要含有黄酮类、三萜类、有机酸类、氨基酸、多肽、蛋白质、鞣质、甾醇、微量元素等。具有改善血液流变学指标、降低血压、调节血脂、抑制血小板聚集、保护肝脏、增强免疫功能、抗炎、镇痛及调节中枢神经系统等作用。     

Biomechanical Properties of Multi-Swing and Single-Swing Rope Skipping Actions

Rope skipping is popular as it is easy to learn; thus, it has developed into a competitive sport. The research on the biomechanical properties of rope skipping can effectively improve training efficiency and reduce injury probability. This paper briefly introduced the characteristics of single-swing and multi-swing techniques in competitive rope skipping, selected ten second-grade athletes as the subjects to test the single-swing and triple-swing rope skipping, and tested the biomechanical properties in the process of rope skipping. The results showed that the variation range of the lower limb joint angle in the triple-swing rope skipping was larger than that in the single-swing rope skipping in the stage of thrusting against the ground and the hanging stage and smaller in the buffering stage. The maximum ground reaction force, the maximum vertical displacement, the vertical velocity at the moment of leaving the ground, and the vertical velocity at the moment of landing in triple-swing rope skipping were significantly higher than those in the process of single-swing rope skipping. In conclusion, to ensure the success of the triple-swing rope skipping, the lower limbs need to exert a larger acting force on the ground to obtain larger counter-acting force to extend the hanging time and ensure three circles.     

药用植物蛇足石杉的化学成分与药理活性研究进展

综述了蛇足石杉植物在化学成分、药理作用、临床应用等方面的研究进展。并对该植物的发展前景进行了展望。     

夏枯草的化学成分及药理作用研究进展

夏枯草主要含有三萜及其苷类、甾醇及其苷类、黄酮类、香豆素、苯丙素、有机酸、挥发油及糖类等成分,具有降压、降糖、抗茵、抗炎、抗过敏及抗病毒等作用,近年来由于其明确的抗病毒及抗癌作用受到研究者的重视。     

苜蓿属植物化学成分与药理作用研究进展

苜蓿属植物分布广泛,其中所含有的化学成分主要为皂苷类、黄酮类、香豆素类、多糖等.本属植物及其提取物具有降胆固醇、抗动脉粥样硬化、雌激素样作用等药理活性,深入研究后可开发为天然药物.     

Physical–Chemical Properties,Physiological Activity,and Usage of Alginates,the Polysaccharides of Brown Algae

This review summarizes data on alginates, polysaccharides isolated from brown algae. Their raw sources, chemical structure, and physical–chemical properties are discussed briefly. This paper is mainly focused on the physiological activity and usage of alginates in food and pharmaceutical industries. The data on alginate toxicity and necessary safety measures are also presented. The capability of alginates to bind and eliminate heavy metals and radionuclides from animal and human organisms is discussed. This paper also deals with the effects of alginates on the metabolism of lipids, carbohydrates, etc., and their usage in medicine, dietetics, and biotechnology.