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1.
Chromosome number determinations from 118 populations of eight species of the aster genus Virgulus are reported for the first time. Based on these counts and literature reports the geographic distributions of diploids and tetraploids in V. concolor, V. novae-angliae, V. oblongifolius, and V. patens have been determined. In the first three species, diploids were widely distributed, while tetraploids were more restricted. In V. patens, diploids were restricted to the southwestern portion of the species’ range, while tetraploids were found throughout the range. Both V. adnatus and V. walteri were found only at the tetraploid level throughout their ranges. Two other species with restricted distributions were consistently found to be high level polyploids: V. georgianus with 2n = 50, V. grandiflorus with 2n = 60. The following new combinations are listed: Virgulus georgianus (Alexander ex Small) Semple; Virgulus subsect. Brachyphylli (Torr. & Gray) Semple; and Virgulus sect. Polyliguli (Semple & Brouillet) Semple.  相似文献   

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Summary Protoplasts were isolated from hypocotyl of V. mungo (L.) Hepper or hypocotyl-derived callus of V. sublobata (Phaseolus sublobata Roxb.) and V. unguiculata (L.) Walp (syn. V. sinensis (L.) Saviex Hassk) using an enzyme solution comprising Cellulase 2.5%, Macerozyme, Hemicellulase and Driselase each at a 0.5% level in 0.5 M sorbitol. Isolated protoplasts were cultured in Murashige and Skoog's (1962) basal liquid medium supplemented with BA, NAA, 2,4-D (1 mg/l each) and sucrose (14%). After four weeks, protoplast colonies were transferred to the same medium with a reduced level of sucrose (7%). Colonies proliferated into actively growing calli. Further attempts to regenerate plants from such calli were not successful. However, protoclones of V. unguiculata differentiated roots on auxin/cytokinin supplemented media. Alternative methods for shoot differentiation from protoplastderived cultures were tried by the use of Agrobacterium tumefaciens shooter strains pGV 2215 or pGV 2298 or wild type strain B6S3.  相似文献   

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The prevailing common knowledge says that animals, and especiallymammals, use hormones to coordinate biochemical activities ofdifferent types of cells, while neuromediators serve as signallingmolecules for communication within the animal’s body andwith the outside world. On the other hand, higher plants utilizehormone-like substances to coordinate their growth and development,but they lack the sophisticated systems for integrative processingand exchange of information. Is it true or false? This book by  相似文献   

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Abstract. 1. Nest thermoregulation follows a similar pattern in Vespa simillima Smith and V. tropica L. There is a gradual decline in the daily fluctuations of nest temperature to a constant steady state which is maintained during the production of the first sexuals, followed by a sudden loss of stability at the end of the colony cycle.
2. The larvae are not major producers of heat, as they are unable to raise their body temperature by more than 1–2°C above ambient. However, they act as heat reservoirs and providers of food in the form of larval secretions. This feeding may allow workers to raise their body temperature during non-foraging periods.
3. The adults are capable of raising their body temperature many degrees above ambient and the presence of even one adult, in this case a V.analis F. mother queen, was able to raise the nest temperature.
4. Supplementary carbohydrate food promotes thermogenesis and enhances colony development.  相似文献   

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W. P. Warner 《CMAJ》1946,54(6):564-568
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A precursor in tetrapyrrole biosynthesis, 5-aminolevulinic acid (ALA), was applied via presowing soaking in Vigna catjung, V. mungo, and V. radiata. ALA increased plant growth and influenced dry matter accumulation in leaves, stems, and pods through increased chlorophyll content and photosynthetic CO2 absorption. At harvest, ALA treated plants had increased number of pods per plant, seeds per pod, 100 seed dry matter, biological yield, and the harvest index. Therefore, pretreatment of seeds with optimal concentration of ALA is recommended for improving the growth and productivity of tropical legumes. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

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Vibrio parahaemolyticus, V. cholerae, and V. vulnificus were isolated from 10.3%, 1.0%, and 0.1% of 885 blue mussel samples, respectively. Four of the samples contained trh(+) V. parahaemolyticus, while no tdh-positive isolates were detected. The V. cholerae isolates were non-O:1/non-O:139 serotypes and were ctxA negative.  相似文献   

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Vibrio parahaemolyticus, V. cholerae, and V. vulnificus were isolated from 10.3%, 1.0%, and 0.1% of 885 blue mussel samples, respectively. Four of the samples contained trh+ V. parahaemolyticus, while no tdh-positive isolates were detected. The V. cholerae isolates were non-O:1/non-O:139 serotypes and were ctxA negative.  相似文献   

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What we see depends on where we look. This paper characterizes the modulatory effects of point of regard in three-dimensional space on responsiveness of visual cortical neurons in areas V1, V2, and V4. Such modulatory effects are both common, affecting 85% of cells, and strong, frequently producing changes of mean firing rate by a factor of 10. The prevalence of neurons in area V4 showing a preference for near distances may be indicative of the involvement of this area in close scrutiny during object recognition. We propose that eye-position signals can be exploited by visual cortex as classical conditioning stimuli, enabling the perceptual learning of systematic relationships between point of regard and the structure of the visual environment.  相似文献   

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