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91.
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93.
By using a large cage in the field and a system of marking, the flight activities of 36 females and 49 males of the European chafer were followed during June and July, 1954.It was found that the beetles made one to 11 flights during their life span with males averaging five flights and females 4.5. More males made eight to 11 flights than did females, and males made more flights on consecutive evenings. The average longevity of the males was found to be six days while the females lived on the average for 6.5 days.The main flight period of the European chafer lasts about one month though some beetles can be observed flying in the evenings for about two months after the main flight has ended. The populations observed in the field are composed of successive groups of beetles which emerge, fly for several days then die. These groups overlap each other so that high numbers of beetles are present in the trees each evening during the main flight period. Variations in the physical characteristics of the soil habitat could be responsible for the differences in the time of maturity of the larvae and the subsequent first-time emergence of the adults.
Zusammenfassung Im Juni und Juli 1954 wurde die Flugtätigkeit von 36 weiblichen und 49 männlichen Tieren von Amphimallon majalis (Razoumowsky) unter Zuhilfenahme eines grossen Käfigs im freien Felde und eines geeigneten Bezeichnungssystems der Tiere verfolgt.Es zeigte sich, dass die Käfer während ihrer Lebensdauer ein bis elf Flüge unternehmen und zwar betrug der Durchschnitt für männliche Tiere fünf, für weibliche 4,5 Flüge. Mehr Männchen als Weibchen flogen 8 bis 11 mal und die Männchen flogen häufiger an aufeinanderfolgenden Abenden. Für männliche Käfer war die durchschnittliche Lebensdauer 6 Tage, während die weiblichen einen Durchschnitt von 6,5 Tagen erreichten.Die Hauptflugperiode von Amphimallon majalis erstreckt sich über etwa einen Monat, obwohl man auch 2 Monate lang nach der Hauptflugzeit des abends noch einige Käfer fliegen sehen kann. Die Gesamtzahl der im Versuchsfeld beobachteten Insekten setzt sich aus auf einander folgenden Gruppen von Käfern zusammen, die nach einander ausschlüpfen, mehrere Tage fliegen und dann sterben. Diese Gruppen überschneiden sich, so dass während der Hauptflugzeit abends eine grosse Anzahl von Käfern in den Bäumen zu finden ist. Es ist sehr wohl möglich, dass Unterschiede in der physikalischen Beschaffenheit des Bodens für die Länge der Reifezeit der Larven verantwortlich sind und somit auch für den Zeitpunkt des Erstfluges der entwickelten Käfer.相似文献
94.
Strangers Abroad Series: Sir Walter Baldwin Spencer (1860–1929), Fieldwork; Franz Boas (1858–1952), The Shackles of Tradition; William Rivers (1864–1922), Everything Is Relatives; Bron-islaw Malinowski (1884–1942), Off the Verandah; Margaret Mead (1901–1978), Coming of Age; Sir Edward Evans-Pritchard (1902–1973), Strange Beliefs. 相似文献
95.
96.
Taffet George E.; Michael Lloyd A.; Tate Charlotte A. 《Journal of applied physiology》1996,81(4):1488-1494
Taffet, George E., Lloyd A. Michael, and Charlotte A. Tate.Exercise training improves lusitropy by isoproterenol in papillarymuscles from aged rats. J. Appl.Physiol. 81(4): 1488-1494, 1996.Aging isassociated with a decreased cardiac responsiveness to -adrenergicstimulation. We examined the effect of endurance exercise training ofold Fischer 344 male rats on -adrenergic stimulation of the functionof isolated left ventricular papillary muscle. Three groups wereexamined: sedentary mature (SM; 12-mo old), sedentary old (SO;23-24 mo old), and exercised old (EO; 23-24 mo old) that weretreadmill trained for 4-8 wk. The isometric contractile propertieswere studied at 0.2 Hz and 0.75 mM calcium. Without -adrenergicstimulation, there were no group differences for peak tension, maximumrate of tension development(+dP/dt), or maximum rateof tension dissipation(dP/dt). The time to peak tension was longer (P < 0.05) forboth EO and SO than for SM rats. Half relaxation time(RT1/2) was prolonged(P < 0.05) for SO compared with SMand EO (which did not differ). The three groups did not differ in the-adrenergic stimulation by isoproterenol of peak tension,dP/dt, time to peak tension, orcontraction duration. The inotropic response(+dP/dt) of SM was greater(P < 0.05) than that in SO or EOrats (which did not differ); however, the lusitropic response(RT1/2) was lesser(P < 0.05) in SO than in SM or EO rats (which did not differ). Thus exercise training of old rats improved the lusitropic response to isoproterenol without altering theage-associated impairment in inotropic response. 相似文献
97.
George T. Fantry Qiao-Xi Zheng Peter E. Darwin rew H. Rosenstein Stephen P. James 《Helicobacter》1996,1(2):98-106
Background Helicobacter pylori infection has been implicated strongly in the pathogenesis of gastritis, peptic ulcer disease, gastric adenocarcinoma, and gastric lymphoma, but the reasons for these widely different clinical outcomes are unknown. The aim of this study was to determine whether these differences could be due in part to mixed infection in the same individual, with bacteria having differences in pathogenic factors associated with ulcers.
Materials and Methods. The cagA gene of H. pylori was used to test for mixed infection because it is present in only some strains, and its presence has been associated with ulcers. Polymerase chain reaction (PCR) assays for the cagA gene were applied to H. pylori culture isolates and endoscopic gastric aspirates. Individual bacterial clones were tested for genetic similarity by random primer amplification and restriction endonuclease digestion of urease gene PCR products.
Results. The majority of H. pylori -positive patients had strongly cagA -positive culture isolates and endoscopic samples (62.5% and 69.6%, respectively). However, many of these patients had evidence of mixed infection with cagA negative and cagA positive strais in cultures isolates and endoscopic samples (25% and 17.4%, respectively). Mixed infection was found to be due to genetically unrelated strains in two patients in whom genetic analysis was performed.
Conclusion. Mixed infection with differences in substrain pathogenic factors might occur in H. pylori infection and might contribute to differences in clinical outcome. 相似文献
Materials and Methods. The cagA gene of H. pylori was used to test for mixed infection because it is present in only some strains, and its presence has been associated with ulcers. Polymerase chain reaction (PCR) assays for the cagA gene were applied to H. pylori culture isolates and endoscopic gastric aspirates. Individual bacterial clones were tested for genetic similarity by random primer amplification and restriction endonuclease digestion of urease gene PCR products.
Results. The majority of H. pylori -positive patients had strongly cagA -positive culture isolates and endoscopic samples (62.5% and 69.6%, respectively). However, many of these patients had evidence of mixed infection with cagA negative and cagA positive strais in cultures isolates and endoscopic samples (25% and 17.4%, respectively). Mixed infection was found to be due to genetically unrelated strains in two patients in whom genetic analysis was performed.
Conclusion. Mixed infection with differences in substrain pathogenic factors might occur in H. pylori infection and might contribute to differences in clinical outcome. 相似文献
98.
Primate terminal complement inhibitor homologues of human CD59 总被引:6,自引:0,他引:6
William L. Fodor Scott A. Rollins Stella Bianco-Caron Willis V. Burton Edward R. Guilmette Russell P. Rother George B. Zavoico Stephen P. Squinto 《Immunogenetics》1995,41(1):51-51
The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession numbers L22862 (African green monkey CD59) and L22863 (baboon CD59) 相似文献
99.
Plantations of radiata pine (P. radiata D.Don) on soils previously under legume based pastures have a high incidence of stem deformity compared with forest soils.
A comparison of soil properties and tree nutrition of 5 to 7 year-old radiata pine on former pastures in the first part of
the study showed that stem deformity was strongly correlated with mineralisation of soil N and in particular with nitrification.
Other soil properties that have changed as a result of pasture improvement, e.g. pH, available P and Mn, were only partially
correlated with stem deformity. In the second part of the study, the role of N availability and other soil properties in the
expression of deformity was further investigated in a separate field experiment on soils formerly under native eucalypt forest,
tobacco cropping, and improved pasture. Young radiata pine plantings were treated with lime, phosphorus, and nitrogen applied
as urea and sodium nitrate. Liming increased soil pH by around 1.5 units, raised exchangeable Ca2+ and decreased available Mn. Soil mineral N content was only marginally affected by liming. Superphosphate increased soil
available P and raised levels of P in foliage. Changes in soil pH, availability of P, Mn, and B did not affect growth or stem
deformity at any of the sites. In contrast, application of N fertilisers at 200 and 600 kg N ha-1 increased mineral N content and stimulated nitrification, particularly at the forest site. The high rate of N fertiliser
increased basal area at the forest site by 45%, but also raised the level of stem deformity from 12% to 56%. At the tobacco
and pasture sites, this treatment did not increase growth and did not significantly raise stem deformity above the already
high basic level of deformity (63%). Implications of stem deformity in young plantations of radiata pine on potential utilisation
later in the rotation are discussed. 相似文献
100.
Cloning of the mgtE Mg2+ transporter from Providencia stuartii and the distribution of mgtE in gram-negative and gram-positive bacteria. 总被引:1,自引:1,他引:0 下载免费PDF全文
D E Townsend A J Esenwine J George rd D Bross M E Maguire R L Smith 《Journal of bacteriology》1995,177(18):5350-5354
The MM281 strain of Salmonella typhimurium possesses mutations in each of its three Mg2+ transport systems, requires 100 mM Mg2+ for growth, and was used to screen a genomic library from the gram-negative bacterium Providencia stuartii for clones that could restore the ability to grow without Mg2+ supplementation. The clones obtained also conferred sensitivity to Co2+, a phenotype similar to that seen with the S. typhimurium corA Mg2+ transport gene. The sequence of the cloned P. stuartii DNA revealed the presence of a single open reading frame, which was shown to express a protein with a gel molecular mass of 37 kDa in agreement with the deduced size of 34 kDa. Despite a phenotype similar to that of corA and the close phylogenetic relationship between P. stuartii and S. typhimurium, this new putative Mg2+ transporter lacks similarity to the CorA Mg2+ transporter and is instead homologous to MgtE, a newly discovered Mg2+ transport protein from the gram-positive bacterium Bacillus firmus OF4. The distribution of mgtE in bacteria was studied by Southern blot hybridization to PCR amplification products. In contrast to the ubiquity of the corA gene, which encodes the dominant constitutive Mg2+ influx system of bacteria, mgtE has a much more limited phylogenetic distribution. 相似文献