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Melone  Giulio  Ricci  Claudia 《Hydrobiologia》1995,(1):91-98
All Bdelloid Rotifers have the same body plan: elongated body, ciliated apical region (rotatory apparatus or corona), telescopically retractable foot and head with pseudosegments, paired gonads, single dorsal antenna, apical rostrum, ramate mastax. Bdelloids use the rotatory apparatus for both locomotion and collecting food and therefore the shape of the corona and arrangement of the cilia, both related to the animal's life style, probably are important for the fitness of the rotifers. We have analyzed the fine morphology of the corona and the rostrum from species belonging to the four families, Habrotrochidae, Philodinidae, Adinetidae and Philodinavidae, each with its own form of feeding and locomotion. In the rostrum one can distinguish a sensorial area and a ciliated area. The former is common to all bdelloids, while the latter is lacking in the Adinetidae. Three models of corona can be recognized: 1) a simple ciliated field of undifferentiated cilia (Adinetidae), 2) a well developed ciliated field with specialized cilia forming the paired trochi on the disks and the cingulum (Habrotrochidae and Philodinidae), and 3) a ciliated field with a single trochus encompassing rudimentary pedicels and cingulum (Abrochtha). We propose (1) to no longer use Digononta as a taxon, (2) to assign the class rank to Bdelloidea, (3) to distinguish three orders, grouping Philodinidae and Habrotrochidae under a single order and (4) to retain the current families.  相似文献   

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Microbial (enzymatic) hydrolysis of (±)-O-acetyl allethrolone gave (?)-(R)-allethrolone with (+)-(S)-O-acetyl allethrolone. And microbial hydrolysis of (±)-cis and trans-2-allylcyclopentyl acetates gave the low optically active cis and trans-2-allylcyclopentanols with the acetates of their antipodes. Also, the acetates of (±)-primary alcohols with cyclopropane and cyclohexene rings: (±)-chrysanthemyl alcohol, α-cyclogeraniol, were hydrolyzed by microorganisms to give the optically active alcohols in low optical purities Further, synthesis and microbial resolution of racemic hydroxy-trimethylcyclohexanones, useful intermediate for synthesis of compounds related to carotenoids, were tried.  相似文献   

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In order to clarify the postprandial glucose suppression via α-glucosidase (AGH) inhibitory action by natural compounds, flavonoids were examined in this study. Among the flavonoids (luteolin, kaempferol, chrysin, and galangin), luteolin showed the potent maltase inhibitory activity with the IC50 of 2.3 mM, while less inhibitions were observed against sucrase. In addition, the effects of maltase inhibition by flavonoids were observed in the descending order of potency of luteolin>kaempferol>chrysin>galangin. Apparently, the AGH inhibition power greatly increased with the replacement of hydroxyl groups at 3′ and 4′-position of the B-ring. However, the inhibitory power of luteolin was poorer than a therapeutic drug (acarbose: IC50; 430 nM). As a result of a single oral administration of maltose or sucrose (2 g/kg) in SD rats, no significant change in blood glucose level with the doses of 100 and 200 mg/kg of luteolin was observed. These findings strongly suggested that luteolin given at less than 200 mg/kg did not possess the ability to suppress the glucose production from carbohydrates through the inhibition of AGH action in the gut.  相似文献   

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Some physicochemical properties of the acid-stable α-amylase and the acid-unstable α-amylase, produced by Asp. niger simultaneously, were investigated comparing with each other. The molecular weights of the acid-stable α-amylase and the acid-unstable α-amylase were computed from sedimentation equilibrium as 58,000 and 61,000, respectively. And the molecular shapes were investigated by measuring sedimentation coefficient and intrinsic viscosity. The results indicated that these two α-amylases were similar in hydrodynamic properties and that they were prolate ellipsoids and poor hydrated proteins. But high frictional ratio of the acid-stable α-amylase suggested a certain degree of molecular asymmetry. Isoelectric points of the acid-stable α-amylase and the acid-unstable α-amylase were determined as pH 3.44 and 3.70, respectively.  相似文献   

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The least squares calculation of the best values of the parameters of the Moffitt equation and of the Drude equation is examined. It is proved that the least squares evaluation of all three parameters of the Moffitt equation becomes indeterminate as the bo term approaches zero. Estimates of low helical content based on the Moffitt relationship are therefore also indeterminate and of dubious value. Both the size of bo and the range of wavelengths chosen affect the standard deviations of the parameters. The magnitude of the effects is illustrated by selected examples. The computer program OPTROT is available for evaluating the extent to which data may be correlated by the equations.  相似文献   

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Rotatory dispersion and circular dichroism of brain proteolipid protein   总被引:8,自引:4,他引:4  
Abstract— The proteolipid and its partially delipidated protein from brain tissue have been studied by optical rotatory dispersion and circular dichroism in various solvents. The protein exhibits a helix content of 60–70 per cent in chloroform-methanol and 2-chloroethanol and is dextrorotatory in the visible region. In 1,1,1-trinuoroethanol, a higher helix content of 90 per cent is observed but the protein is laevorotatory. The helix content decreases in water and methanol with a much greater negative specific rotation in methanol. No random coil form has been observed.  相似文献   

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T Imae  S Ikeda 《Biopolymers》1972,11(2):509-517
Rotatory dispersion and circular dichroism of low-molecular-weight poly-γ-benzyl-L -glutamate, which was prepared from the N-carboxyanhydride by n-hexylamine initiation at [A]/[I] 3, 4, and 8, have been measured in ethylene dichloride and dioxane at different concentrations. The rotatory properties of the polypeptides are all characterized by a trough at 233 mμ of a negative Cotton effect or by a negative circular dichroic band at 223 mμ. With increasing A/I value or concentration, dextrorotation increases and the negative dichroic band becomes deeper. Both the trough magnitude and the negative ellipticity are linearly dependent on the content of β-structure, and the rotatory parameters for the pure β-structure are estimated by extrapolation of the linear relations. Circular dichroism and infrared spectra of the polypeptides have also been measured in trifluoroethanol, and the effect of solvents on the polypeptide conformation is discussed.  相似文献   

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For the first time ORD measurements in the near-infrared region from 0.7 to 2.0 μ for well-known polypeptides, namely, poly(γ-benzyl L -glutamate), poly(L -glutamic acid), poly-L -lysine·HCl, poly-S-carbobenzoxymethyl-L -cysteine, and Bombyx mori silk fibroin, were carried out. It was found that the value of the optical activity infrared term, which is proportional to the sum of rotational strengths of vibrational transitions, depends on polypeptide conformation. The optical activity infrared term value is equal to zero for the random-coil conformation, it is small but exceeds the measurement error for the α-helical state, and finally, for the β conformation it is an order of magnitude higher than for the α-helical state. The obtained results permit one to hope that on the basis of ORD measurement in the near-infrared region it will be possible to suggest a method of determining the β-form content in polypeptides and proteins  相似文献   

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Vertebrate Paleontology in the Neotropics: The Miocene Fauna of La Venta, Colombia edited by R.F. Kay et al. Smithsonian Institution Press, 1997. £62.50 hbk (xvi +592 pages) ISBN 1 56098 4 18 X.  相似文献   

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Estimation of the constants a, b, and λ0 by means of the standard Moffitt-Yang plot is evaluated. It is found that the method is very insensitive as an estimation procedure and that large errors in b may be expected. Expressions for the maximum-likelihood estimates of the constants are derived.  相似文献   

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Blocked beds.     
In a cross-sectional survey of 325 surgical and orthopaedic beds 43 (16%) of the 265 occupied beds were filled by patients who had no medical need to be in an acute ward. They had been in hospital for a median time of 40 weeks up to the survey date. Of the 43 patients, 11 were awaiting transfer to a geriatric ward; 13 to community residential care; and seven to their homes. There was no plan for discharge or transfer for the remaining 12 (28%). Those "at risk" of becoming long-stay patients for social reasons on these wards were women, over 75, living alone or with one relative, who had been admitted to hospital in emergency with a fractured femur, head injury, or other trauma. Action necessary to reduce the number of social long-stay patients includes (a) changing attitudes to the solving of social case problems; (b) revising procedures of assessment and planning of future care; (c) improving teamwork and record keeping within the hospital and the community services; (d) providing a better balance of acute, medium and long-stay hospital beds; and (e) putting more resources into rehabilitation.  相似文献   

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Packed bed cultivation systems have potential for widespread application in solid-state cultivation (SSC), but they are poorly characterized. The effects of particle size and substrate loading on the growth of Rhizopus oligosporus on sago-beads in packed bed bioreactors were investigated. Pressure drop and protein were monitored as indicators of fungal growth in cultivations performed in a large column (4.9 cm internal diameter and 60 cm height) and a system of small columns (4.2 cm internal diameter and 5.2 cm height). The differential pressure drop increased to a maximum between 34 and 44 h and then decreased again. The maximum differential pressure drop attained was greatest for the smallest particle size and for the lower substrate loadings. However, since the protein content continued to increase throughout the cultivation, pressure drop could not be used to monitor growth directly.  相似文献   

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