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141.
dos Santos Silva Edinaldo N. Kakkassery Francy K. Maas Sibylle Dumont Henri J. 《Hydrobiologia》1994,288(2):119-128
Calanoid copepods, belonging to the new genus and species Keraladiaptomus rangareddyi, were collected from temporary ponds in Kerala State, India. The new genus belongs to the family Diaptomidae, subfamily Diaptominae. It is described in detail and its affinity to the related genera, Arctodiaptomus Kiefer, 1932 and Eodiaptomus Kiefer, 1932, discussed. 相似文献
142.
Reis M. F. Machado A. A. S. C. Abdulla M. Canário J. Silva J. C. 《Biological trace element research》1994,43(1):585-596
Biological Trace Element Research - To make the best use of time and facilities, a neutron activation system, fully automatic, including spectrum and data processing, to be used with short-lived... 相似文献
143.
Summary Direct measurements of membrane fluidity by fluorescence anisotropy of protoplasts fromKloeckera apiculata andSaccharomyces cerevisiae, a low and a high ethanol tolerant strain respectively, are presented. The comparison of the behaviour of the two strains
grown with or without ethanol enabled us to demonstrate the existing relationship between ethanol tolerance and membrane fluidity. 相似文献
144.
Nostoc sp. was cultivated in an air-lift reactor with continuous recirculation of the head gas phase that aerated and agitated the cyanobacterial suspension at regulated flow rates. The supply of inorganic carbon for growth was coupled with pH control, in the range of 7.7 to 8.1, by intermittent sparging of CO2-head gas mixtures. The formation of irregular bubbles with swirling motion at the photostage of the reactor promoted efficient CO2 transference in dense populations of Nostoc sp. (1.1 g/l) when bubbling at flow rates of 10 l/min. Biomass productivity was almost six-fold higher in the photoreactor (16.4 mg/l.h) than in a conventional system (2.8 mg/l.h). The exponential growth phase of cultures in the photoreactor amounted to 60% of the total growth period.The authors are with the Laboratorio de Alimentos, Area Microbiologia, Facultad de Quimica Bioquimica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, 5700 San Luis, Argentina 相似文献
145.
146.
Zampronio AR Melo MC Silva CA Pelá IR Hopkins SJ Souza GE 《Mediators of inflammation》1994,3(5):365-373
The aim of this study was to investigate the pyrogenic activity of factor(s) released by rat peritoneal macrophages following a brief stimulation with LPS. The effect of this factor on the number of circulating leukocytes and serum Fe, Cu and Zn levels, was also evaluated. The possibility that the content of interleukin (IL)-1beta, IL-6 and tumour necrosis factor (TNF) in the supernatant could explain the observations was investigated. Supernatant produced over a period of 1 h by peritoneal macrophages, following a 30 min incubation with LPS at 37 degrees C, was ultrafiltered through a 10 000 MW cut-off Amicon membrane, sterilized, and concentrated 2.5, 5, 10 and 20 times. The intravenous (i.v.) injection of this supernatant induced a concentration-dependent fever in rats with a maximal response at 2 h. The pyrogenic activity was produced by macrophages elicited with thioglycollate and by resident cells. The supernatants also induced neutrophilia and reduction in Fe and Zn 6 h after the injection. Absence of activity in boiled supernatants, or supernatants from macrophages incubated at 4 degrees C with LPS, indicates that LPS was not responsible for the activity. In vitro treatment with indomethacin (Indo), dexamethasone (Dex), or cycloheximide (Chx) did not modify the release of pyrogenic activity into the supernatant or its effects on the reduction in serum metal levels. Although Chx abolished the production of mediator(s) inducing neutrophilia, and Dex reduced the induction of IL-1beta, TNF and IL-6, injection of the highest concentration of these cytokines detected in the supernatants did not induce fever. In vivo treatment with Dex, but not Indo, abolished the fever induced by the supernatant. These results suggest that macrophages contain pre-formed pyrogenic mediator(s), not related to IL-1beta, IL-6 or TNF, that acts indirectly and independently of prostaglandtn. It also seems likely that the pyrogenic activity is related to the factor responsible for the reduction of serum Fe and Zn levels, but not the neutrophilia. 相似文献
147.
Beatriz Ernestina Cabilio Guth Eliana Gonalves Aguiar Patricia Marie Griffin Sonia Regina Testa da Silva Ramos Tnia Aparecida Tardelli Gomes 《Microbiology and immunology》1994,38(9):695-701
Fifty-eight enterotoxigenic Escherichia coli (ETEC) strains, isolated from children with and without diarrhea in Sao Paulo, were examined for the presence of colonization factor antigens (CFAs) and their ability to adhere to HeLa cells. Antisera to CFA/I, the coli surface (CS) antigens CS1CS3, CS2CS3, and CS2 of CFA/II, CFA/III, and CS5CS6 and CS6 of CFA/IV were used. CFAs were identified in 43% of the ETEC strains: 40% of the strains with CFAs harbored CFA/I, 24% carried CFA/II (CS1CS3), 24% carried CFA/IV (CS6), and 12% carried CFA/IV (CS5CS6). CFAs occurred mainly among ETEC strains producing only heat-stable (ST-I) enterotoxin and in strains also producing heat-labile toxin (LT-I). No ETEC strains tested expressed CFA/III. A marked change in serotypes of ST-I-producing strains was found in Sao Paulo between 1979 and 1990. Adherence to HeLa cells was detected in 14% of the ETEC strains. All of them had a diffuse adherence pattern and produced only ST-I, and 88% carried CS6 antigen. 相似文献
148.
149.
Hydraulic properties of sphagnum peat moss and tuff (scoria) and their potential effects on water availability 总被引:2,自引:0,他引:2
The importance of macrostructure to root growth of ryegrass (L. perenne) seedlings sown on the soil surface was studied in two soils in which the macrostructure had resulted mainly from root growth
and macro-faunal activity. Sets of paired soil cores were used, one of each pair undisturbed and the other ground and repacked
to the field bulk density.
Undisturbed and repacked soils were first compared at equal water potentials in the range −1.9 to −300 kPa. At equal water
potential, the undisturbed soil always had the greater strength (penetration resistance), and root growth was always greater
in the repacked soil with no macrostructure than it was in the soil with macrostructure intact. At equal high strength (low
water potentials) it appeared that root growth was better when soils were structured. When strength was low (high water potentials),
root growth was better in the unstructured soil.
Soils were then compared during drying cycles over 21 days. The average rate at which roots grew to a depth of 60 mm, and
also the final percentage of plants with a root reaching 60 mm depth, was greatest in repacked soils without macrostructure.
The species of vegetation growing in the soil before the experiment affected root growth in undisturbed soil; growth was slower
where annual grasses and white clover had grown compared with soil which had supported a perennial grass.
It appears that relatively few roots locate and grow in the macrostructure. Other roots grow in the matrix, if it is soft
enough to be deformed by roots. Roots in the matrix of a structured soil grow more slowly than roots in structureless soil
of equal bulk density and water potential. The development of macrostructure in an otherwise structureless soil, of the type
studied, is of no advantage to most roots. However, once a macrostructure has developed, the few roots locating suitable macropores
are able to grow at low water potential when soil strength is high. The importance of macrostructure to establishing seedlings
in the field lies in rapid penetration of at least a few roots to a depth that escapes surface drying during seasonal drought.
ei]{gnB E}{fnClothier} 相似文献
150.
L. M. Freitas dos Santos A. G. Livingston 《Applied microbiology and biotechnology》1993,40(1):151-157
The biological treatment of waste-waters containing 1,2-dichloroethane (DCE) in conventional bioreactors results in air-stripping of DCE. In the present work, a novel bioreactor system intended to overcome this problem has been developed for the treatment of a synthetically concocted DCE-containing waste-water (1000 mg DCE l–1). The operation of a conventional air-lift bioreactor at a waste-water flow rate of 0.24 l h–1 led to 33% of the DCE supplied to the reactor being lost to the exit gas stream. The use of the novel enclosed system, operated with a recycling O2 sparge instead of air, resulted in negligible air-stripping at the same waste-water flow rate. A control system was implemented to add O2 as required to maintain the pressure of the recycle gas stream, and a scrubber removed the CO2 produced. Over 99% of DCE supplied was biodegraded during operation of this system, and virtually all carbon entering the system was evolved as CO2.
Correspondence to: A. G. Livingston
Correspondence to: A. G. Livingston 相似文献