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1.
Isolate M of Potato virus A (PVA‐M; genus Potyvirus) is avirulent in Nicandra physaloides L. (family Solanaceae). The inoculated leaves are infected but no systemic infection is observed. Forty plants of ‘Black Pod’ (BP) and ‘Black Pod Alba’ (BPA), two variants of N. physaloides described in this study, were inoculated with PVA‐M. Two plants of BP and one plant of BPA were systemically infected. Mosaic, blistering and dark green islands developed on the systemically infected leaves, and flowers showed colour‐break symptoms. PVAprogeny were sequence‐characterised for the 6K2 protein and viral genome‐linked protein (VPg) encoding regions known to control the long distance movement of PVA in N. physaloides. All virus progeny (designated as PVA‐Mm) in the systemically infected leaves of the plants inoculated with PVA‐M contained only a single amino acid substitution (Vail 16Met) in the central part of VPg due to a nucleotide substitution G6033A, as compared to PVA‐M. Other PVA isolates that infected N. physaloides systemically also contained Metll6 in VPg. In a previous study using chimeric viruses, Metl16 in VPg was shown to be a major determinant for vascular movement of PVA in N. physaloides, and this study reveals that the mutation for Metl16 can occur in vivo during replication of the avirulent PVA‐M in infected plants. Immunolocalisation studies on BP and BPA plants showed that the pods (berries) and seed coat contained PVA‐Mm in the developing seeds, but no virus was detected in embryons. Up to 27% of the mature seeds contained PVA‐Mm but no transmission to seedlings was observed in a total of 450 seeds tested, and no test plants were infected following mechanical inoculation with extracts prepared from the seeds. 相似文献
2.
ERKKI KORPIMÄKI 《Ibis》1987,129(1):58-68
Timing of breeding in Tengmalm's Owl was studied in western Finland for 13 years. During 1973-85, half of the females started laying before 4 April, near the seasonal low of main food abundance (voles), and earlier than in southern Finland or as early as in southeastern Norway. The reason for this latitudinal trend is the shallow snow cover of the study area. The annual variation in the median laying dates was one month and was negatively correlated with the spring abundance of Microtus voles. The mean clutch size was related to the start of laying with early clutches being larger than late ones. These findings accord with the 'food limitation hypothesis', which states that laying begins as soon as the female can accumulate enough energy stores for forming eggs. Early breeding is adaptive, since juveniles of early clutches probably survive better during their first winter. In adults, early nesting improves the chances of rearing two broods per year, allows them to moult after breeding and gives more time to accumulate fat reserves to survive the winter. Tengmalm's Owl is one of the earliest breeders among North European birds. This is possible because of its hole-nesting and resident habits, small body-size in relation to the main prey and the greatest sexual size dimorphism among European owls. 相似文献
3.
Abstract.
- 1 Among-population differences in pupal mass were studied in a geometrid, Epirrita autumnata. Some Epirrita autumnata populations regularly reach outbreak densities while others are never known to do so. Because adults do not feed, pupal mass of females correlates strongly with fecundity.
- 2 Larvae were collected from twelve field sites. Ten of our sample populations originated within the outbreak range of the species and represented different phases of outbreaks. Two populations originated outside the outbreak range.
- 3 Pupal mass of field-collected E. autumnata varied significantly among populations. The peak phase populations had the smallest pupae and the biggest were found in low density populations outside the outbreak range.
- 4 Offspring of moths from each population were reared under identical conditions in two larval densities. Significant differences were not found in pupal mass among populations. That is, the inherent size, correlated with fecundity of moths, was not different between populations originating within and outside the outbreak range, nor among collections from different densities or phases of the outbreaks.
- 5 Rearing density did not interact in a consistent way with population.
- 6 As far as size and fecundity are concerned, the results do not support Chitty's hypothesis that differences in genetic composition of the population at low and high density phases generate cyclic fluctuations of population density.
- 7 Because no hereditary or maternal differences were found in size and fecundity between E.autumnata originating within and outside the outbreak range, variation in reproductive capacity cannot explain why outbreaks occur only in some populations.
4.
Abstract The chloroplast ultrastructure, especially the thylakoid organization, the polypeptide composition of the thylakoid membranes and photosynthetic O2 evolution rate, chlorophyll (Chl) content and Chi a/b ratio were studied in leaves of nine plants growing in contrasting biotopes in the wild in South Finland. All the measurements were made at the beginning of the period of main growth on leaves approaching full expansion, when the CO2-saturated O2 evolution rate (measured at 20°C and 1500 μmol photons m?2s?1) was at a maximum, ranging from 19.2 to 6.9 μmol O2 cm?2 h?1. Among the species, the Chi a/b ratio varied between 3.75 and 2.71. In the mesophyll chloroplasts, the ratio of the total length of appressed to non-appressed thylakoid membranes varied between 1.07 and 1.79, the number of partitions per granum varied between 2.8 and 12.0 and the grana area between 21 and 42% of the chloroplast area. There was a significant relationship between the rate of O2 evolution of the leaf discs and the thylakoid organization in the mesophyll chloroplasts. The higher the O2 evolution rate, the lower was the ratio of the total length of appressed to non-appressed thylakoid membranes and also the lower the grana area. Although the relationship of the photosynthetic rate with the Chi content and the Chi a/b ratio of the leaves was not as clear, a significant negative correlation existed between the Chi a/b ratio and the ratio of appressed to non-appressed thylakoid membranes, indicating lateral heterogeneity in the distribution of different Chl- protein complexes. 相似文献
5.
6.
Free radical scavenging ability and antioxidant efficiency of curcumin and its substituted analogue 总被引:5,自引:0,他引:5
Free radical reactions of curcumin and its ethoxy substituted derivative (C1) 1,7-bis-(4-hydroxy-3-ethoxy phenyl)-1,6-heptadiene-3,5-dione have been studied using a pulse radiolysis technique in homogeneous aqueous-organic solutions like acetonitrile-water and isopropanol-water mixtures, as well as in neutral TX-100 and cationic CTAB micellar solutions. The phenoxyl radicals of curcumin or C1 were generated by one-electron transfer to several oxidants like N(3)(.), Br(2)(-.), CCl(3)O(2)(.), glutathione radicals which exhibit absorption from a 300-600-nm wavelength region with the maximum at 490-500 nm. Other important properties of the phenoxyl radicals such as extinction coefficient, radical lifetime and their formation and decay rate constants were also determined in these systems. The antioxidant property of curcumin and C1 were estimated in terms of their ability to inhibit the lipid peroxidation in liposomes and also in terms of trolox equivalent antioxidant capacity (TEAC). The results were compared with alpha-tocopherol. 相似文献
7.
Reactions between horseradish peroxidase (HRP) compound I and II and some natural phenolic antioxidants were studied at pH 7. The bimolecular rate constants for these reactions were determined using a sequential mixing stopped-flow spectrometer. The rate constants for the reactions of compound I were found to be two orders of magnitude higher than those for compound II. The phenols under study showed a significant difference in their one-electron reduction potential values. As the rate constants also changed systematically with their one-electron potentials, the Marcus theory of electron transfer was applied to the above determined rate constants and the thermodynamic driving force (deltaG(o)), from which the reorganization energy (lambda) for the electron transfer from phenols to both compound I and II was estimated. 相似文献
8.
SUN YOUNG KIM EUN JIN YANG JUN GONG JOONG KI CHOI 《The Journal of eukaryotic microbiology》2010,57(6):460-467
ABSTRACT. The identification of Favella ehrenbergii, a marine planktonic ciliate, has largely been based on its lorica features. This approach is potentially problematic given the polymorphic lorica during this organism's life cycle. We isolated a population of F. ehrenbergii from the coastal waters of Incheon, Korea, and revealed its infraciliature using the protargol staining method. Phylogenetic analysis based on small subunit rRNA gene sequences was also performed. Results showed that this population possessed 16 collar membranelles (CM) and about 100 somatic kineties. These features are highly conserved, even in later dividers. As such, the number of CM and somatic kineties can be used as key characteristics for identification of Favella species. 相似文献
9.
B. Santhosh Kumar Santosh K. Tiwari R. Saikant G. Manoj Amit Kunwar G. Sivaram Zakia Abid Adeel Ahmad K. Indira Priyadarsini Aleem A. Khan 《Journal of trace elements in medicine and biology》2010,24(4):263-270
Aim of the present study was to evaluate in vitro toxicity and in vivo antibacterial, anti-inflammatory, antiulcer, and antioxidant activities of two organoselenium compounds, selenocystine (SeCys) and ebselen (Ebs). The study was conducted in experimentally induced ulcers in rodent model infected with Helicobacter pylori (H. pylori). In vitro toxicological studies on normal spleenic lymphocytes revealed that SeCys and Ebs were non-toxic to the cells even at 100 μM concentration. Antibacterial activity was observed at 500 μg/mL concentration of either of the compounds against H. pylori. In vivo studies after treatment with SeCys and Ebs (500 μg/kg/day) resulted in significant reduction in ROS production and inhibition of lipid peroxidation in gastric tissue. The antioxidant and anti-inflammatory activities of both the compounds were also confirmed by their ability to lower GSH reduction, to induce the expression of antioxidant genes such as GPx-4, and MnSOD and to suppress inflammatory genes namely COX-2, TNF-α and TGF-β. In addition, the immunomodulatory activity of both the compounds was evident by enhance of the CD4 levels and maintenance of the IgG, IL-6 and IL-10 levels. Persistent treatment (500 μg/kg, for 28 days) with both the compounds showed considerable (p < 0.05) ulcer healing property supporting its role in gastro protection. In conclusion, the results of our study suggest that both SeCys and Ebs possess broad spectrum of activities without any potential toxicity. 相似文献
10.
Kunwar A Narang H Priyadarsini KI Krishna M Pandey R Sainis KB 《Journal of cellular biochemistry》2007,102(5):1214-1224
A mononuclear 1:1 copper complex of curcumin had been found to be superior to curcumin in its anti-oxidant properties. This paper describes the radio-protective effects of the complex in splenic lymphocytes from swiss mice. The complex was found to be very effective in protecting the cells against radiation-induced suppression of glutathione peroxidase, catalase and superoxide dismutase (SOD) activities. Both curcumin and the complex protected radiation-induced protein carbonylation and lipid peroxidation in lymphocytes with the complex showing better protection than curcumin. It also showed better overall protection by decreasing the radiation-induced apoptosis. The kinetics of activation of PKCdelta and NFkappaB after irradiation in presence or absence of these compounds was looked at to identify the molecular mechanism involved. The modulation of irradiation-induced activation of PKCdelta and NFkappaB by curcumin and the complex was found different at later time periods although the initial response was similar. The early responses could be mere stress responses and the activation of crucial signaling factors at later time periods may be the determinants of the fate of the cell. In this study this delayed effect was observed in case of complex but not in case of curcumin. The delayed effect of the complex along with the fact that it is a better free radical scavenger must be the reason for its better efficacy. The complex was also found to be less cytotoxic then curcumin at similar concentration. 相似文献