The response ofAzolla pinnata R. Brown to the split application of phosphorus and the transfer of assimilated phosphorus to flooded rice plants

A field experiment was conducted at the Bangladesh Rice Research Institute, Joydebpur, Dhaka during the late wet season. Basal application of P at both 5 and 10 kg ha⁻¹ significantly increased total biomass production and nitrogen fixation byAzolla pinnata R. Brown (local strain). Addition of both 5 and 10 kg P ha⁻¹ in equal splits at inoculation and at six day intervals thereafter during growth periods of 12, 24 and 36 days increased biomass production and nitrogen fixation by Azolla over that attained with the basal application. Biomass and nitrogen fixation using a split application of 5 kg P ha⁻¹ exceeded that attained with basal application of 10 kg P ha⁻¹ and split application of 10 kg P ha⁻¹ resulted in 0.58, 11.2, and 18.3 t ha⁻¹ more biomass, and 0.47, 18.9, and 18.3 more kg fixed N ha⁻¹ at 12, 24 and 36 days, respectively, than the same amount applied as a basal application. Analyses indicated that the critical level of dry weight P in Azolla for sustained growth was in the range of 0.15–0.17%. Compared with the control, where no P was added, and additional 30 and 36 kg N ha⁻¹ were fixed after 24 and 36 days, respectively, when P was provided at 10 kg ha⁻¹ using a split application. A separate field study showed that flooded rice plants received P from incorporated Azolla with about 28% of the P present in the supplied Azolla being incorporated into the rice plants.     

Algesia and local responses induced by neurokinin A and substance P in human skin and temporal muscle

Neurokinin A (NKA), substance P (SP) and the two peptides combined (SP + NKA) were injected intracutaneously on the forearm and into the temporal muscle of healthy volunteers. Pain intensity, cutaneous wheal and flare responses and tenderness of the temporal muscle were quantitated. SP but not NKA induced cutaneous pain. This relates the algesic effect of SP to the specific N-terminal amino acid sequence of the peptide, not shared by NKA. NKA, however, potentiated the algesic effect of SP as SP + NKA induced a significantly prolonged cutaneous pain sensation. Both peptides induced wheals, but only SP induced flare. These results confirm previous studies relating wheal formation to the identical C-terminal amino acid sequence of the two peptides and flare reaction to the N-terminal part of SP. Injections into the temporal muscle did not cause pain or tenderness.     

Neuromedin U-immunoreactivity in the nervous system of the small intestine of the pig and its coexistence with substance P and CGRP

Summary In the small intestine of the pig, neuromedin U (NMU)-immunoreactivity was mainly confined to the nerve plexus of the inner submucosal and mucosal regions. After colchicine treatment, a high number of immunoreactive nerve cell bodies was observed in the plexus submucosus internus (Meissner), whereas only a low number was found in the plexus submucosus externus (Schabadasch). The plexus myentericus as well as the aganglionic nerve meshworks in the circular and longitudinal smooth muscle layers almost completely lacked NMU-immunoreactivity. Double-labeling experiments demonstrated the occurrence of distinct NMU-containing neuron populations in the plexus submucosus internus: (1) relatively large type-II neurons revealing immunoreactivity for NMU and calcitonin gene-related peptide (CGRP) and/or substance P (SP); (2) a group of small NMU- and SP-immunoreactive neurons; (3) a relatively low number of small neurons displaying immunoreactivity for NMU but not for SP. Based on its distributional pattern, it is concluded that NMU plays an important role in the regulation and control of mucosal functions.     

The occurrence and distribution of certain polypeptides within the human carotid body

Summary Both carotid bodies from 26 patients coming to necropsy were fixed in 10% neutral buffered formalin and sections 4 m thick were stained for various peptides by use of the immunogold technique. The results show that the human carotid body contains met- and leu-enkephalin, substance P, vasoactive intestinal peptide (VIP), neurotensin and bombesin. The distribution of these six peptides within the carotid body differs. Thus met- and leu-enkephalin are both present predominantly within glomic chief cells but with a marked tendency to favour the dark variant of these cells. Substance P and VIP both show a weak immunoreactivity in comparison to the enkephalins and are present in all three variants of chief cell. Neurotensin shows the weakest immunoreactivity of all and is restricted to a few glomic chief cells in a minority of cases. Bombesin also shows a weak immunoreactivity in glomic chief cells but a strong reaction in glomic arteries and arterioles. In these vessels bombesin appears to be confined to smooth muscle cells in the media but we cannot say whether it is secreted by them or merely bound to receptor sites on their membranes. These findings are related to quantitative data on the concentration of peptides in the human carotid body from a previous paper with which we were associated.     

Soluble and membrane-bound ferrisiderophore reductases of Escherichia coli K-12

After uptake of microbial ferrisiderophores, iron is assumed to be released by reduction. Two ferrisiderophore-reductase activities were identified in Escherichia coli K-12. They differed in cellular location, susceptibility to amytal, and competition between oxygen and ferrichrome-iron(III) reduction. The ferrisiderophore reductase associated with the 40,000×g sediment (membrane-bound enzyme) was inhibited by 10 mM amytal in contrast to the ferrisiderophore reductase present in the 100,000×g supernatant (soluble enzyme). Reduction by the membrane-bound enzyme followed sigmoid kinetics, but was biphasic in the case of the soluble enzyme. The soluble reductase could be assigned to a protein consisting of a single polypeptide of M _r 26000. Reduction of iron(III) by the purified enzyme depended on the addition of NADH or NADPH which were equally active reductants. The cofactor FMN and to a lesser degree FAD stimulated the reaction. Substrate specificity of the soluble reductase was low. In addition to the hydroxamate siderophores arthrobactin, schizokinen, fusigen, aerobactin, ferrichrome, ferrioxamine B, coprogen, and ferrichrome A, the iron(III) complexes of synthetic catecholates, dihydroxy benzoic acid, and dicitrate, as well as carrier-free iron(III) were accepted as substrates. Both ferrisiderophore reductases were not controlled by the fur regulatory system and were not suppressed by anaerobic growth.Abbreviations DHB dihydroxybenzoic acid - MECAM 1,3,5-N,N,N-tris-(2,3-dihydroxybenzoyl)-triamino-methylbenzene - MECAMS 2,3-dihydroxy-5-sulfonyl-derivative of MECAM     

辣椒素引起脊髓P物质释放及其对血压的影响

为进一步研究脊髓 P 物质(SP)在调节心血管活动中的作用,在大鼠脊髓蛛网膜下腔注射(ith)辣淑素(cap),以刺激脊髓 SP 能神经末梢释放 SP,结果引起血浆去甲肾上腺素(NA)和肾上腺素(AD)含量增高,及具有剂量依赖性的动脉血压上升,心率升高。ith 具有高度特异性的 SP 受体拮抗剂或 SP 抗血清均可阻断 cap 引起的升压效应,免疫组化测定也观察到注入的cap 剂量越大,脊髓胸段 SP 样免疫阳性反应物的致密度越低,这些观察结果支持 cap 可以引起脊髓内 SP 的释放的说法。在第一颈段(C_1)横断脊髓后 ith cap 所引起的升压效应与完整动物 ith cap 的升压效应无显著差异。以上结果提示脊髓 SP 能神经末梢释放的 SP 可以通过交感肾上腺髓质系统引起心血管兴奋效应,SP 可能是引起交感节前神经元兴奋的神经递质。     

Cystatins from bovine brain: Purification,some properties,and action on substance P degrading activity

Two cystatins were purified from tissue extract of bovine brain by alkaline treatment, acetone fractionation, gel chromatography on Sephadex G-75, and affinity chromatography on S-carboxymethyl-papain-Sepharose. One of the inhibitors had a relatively high molecular mass, 25 kDa (HMM-cystatin) with pI 4.7, and the other, 11 kDa (LMM-cystatin) with pI 5.23. Both inhibitors showed considerable stability at pH 2 and 80°C. The cystatins inhibited papain, ficin, and cathepsins B and H, but not trypsin, chymotrypsin, thermolysin, nagarse, and cathepsin D. K_i values for the complexes of papain and the inhibitors were estimated to be 2.8×10^–10 M for HMM-cystatin and 1.3×10^–9 M for LMM-cystatin. Both purified cystatins prevented degradation of substance P by soluble fraction and lysosomal extract obtained from synaptosomes, but did not suppress the cleavage of the peptide by synaptosomal plasma membranes.Abbreviations HMM-cystatin high molecular mass inhibitor - LMM-cystatin low molecular mass inhibitor - SP substance P - SPM synaptosomal plasma membranes - p-CMB 4-chloromercuribenzoic acid - BK bradykinin - Bz-Arg-Nap N-benzoyl-dl-arginine--naphthylamide - Arg-Nap dl-arginine--naphthylamide - P-Pxy-Hb hemoglobin initially coupled with pyridoxal-5-phosphate     

Occurrence of rye (Secale cereale) 350-family DNA sequences inAgropyron and otherTriticeae

Evidence is presented that in the R and P genomes (Secale cereale andAgropyron cristatum, respectively) of theTriticeae there exist closely related 350-family DNA sequences in the terminal heterochromatin. This observation is compared to the relationships between these two genomes derived from a comparison of theNor and5 S DNA loci as well as the available data on morphological characters, chromosome pairing, and isozyme studies. It is concluded that the R and P genomes are not closely related and that the common presence of very similar 350-family DNA sequences reflects the parallel amplification of this family of DNA sequences.