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71.
Paclobutrazol [(2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)pentan-3-ol], a triazole growth retardant, increased the 1-aminocyclopropane-1-carboxylic acid (ACC) level and resulted in reduced ethylene production, estimated as ethylene release in a closed system or by vacuum-extraction, in the primary leaves of Phaseolus vulgaris L. cv. Juliska seedlings exposed to light. At the light/dark transition, a definite enhancement of the endogenous ethylene level was observed by vacuum-extraction of primary leaves of treated plants and the ethylene deficiency of retardant-treated leaves ceased. The concentration of ACC after the light/dark transition followed the pattern for ethylene, and the increase in ACC content was paralleled by a decrease in malonyl-ACC.
It is concluded that the internal level of ethylene is not necessarily lower in the primary leaves of paclobutrazol-treated bean plants, but under special environmental conditions in vivo it may reach that of the control. 相似文献
It is concluded that the internal level of ethylene is not necessarily lower in the primary leaves of paclobutrazol-treated bean plants, but under special environmental conditions in vivo it may reach that of the control. 相似文献
72.
73.
Summary We study the leg morphology and feeding postures of two subspecies of the Blue Tit (Parus caeruleus; Tenerife island and the Iberian Peninsula) and the Coal Tit (Parus ater; Iberian Peninsula). We search for evidence supporting the hypothesis of convergent evolution in morphological and ecological traits and we discuss the role of ecomorphological hypotheses as predictors of foraging differences at the intraspecific level. To overcome the problems introduced by environmental characteristics not related to locomotion and competition, we make observations under controlled situations to manage food quality and food access. We determine that the island Blue Tit has a longer tarsometatarsus, larger foot span and a more proximal insertion of the tibialis cranialis muscle (flexor of the tarsometatarsus) than the mainland Blue Tit. These morphological differences are consistent with the more frequent use of hanging and clinging head-up postures by the Iberian Blue Tit. Several ecomorphological hypotheses obtained at the interspecific level with other taxa, have proved to be of high predictive value for explaining ecological differences considering morphological evolution. The Tenerife Blue Tit and the Iberian Coal Tit clearly show close convergence in both feeding postures and leg structure, although some differences in morphology were found between these two species. Convergence in foraging methods between the island Blue Tit and the mainland Coal Tit can be explained without considering current interspecific competition as a determinant of niche space. 相似文献
74.
We have analysed the viability of cellular clones induced by mitotic recombination in Drosophila melanogaster/D. simulans hybrid females during larval growth. These clones contain a portion of either melanogaster or simulans genomes in homozygosity. Analysis has been carried out for the X and the second chromosomes, as well as for the 3L chromosome arm. Clones were not found in certain structures, and in others they appeared in a very low frequency. Only in abdominal tergites was a significant number of clones observed, although their frequency was lower than in melanogaster abdomens. The bigger the portion of the genome that is homozygous, the less viable is the recombinant melano-gaster/simulans hybrid clone. The few clones that appeared may represent cases in which mitotic recombination took place in distal chromosome intervals, so that the clones contained a small portion of either melanogaster or simulans chromosomes in homozygosity. Moreover, Lhr, a gene of D. simulans that suppresses the lethality of male and female melanogaster/simulans hybrids, does not suppress the lethality of the recombinant melanogaster/simulans clones. Thus, it appears that there is not just a single gene, but at least one per tested chromosome arm (and maybe more) that cause hybrid lethality. Therefore, the two species, D. melanogaster and D. simulans, have diverged to such a degree that the absence of part of the genome of one species cannot be substituted by the corresponding part of the genome of the other, probably due to the formation of co-adapted gene complexes in both species following their divergent evolution after speciation. The disruption of those coadapted gene complexes would cause the lethality of the recombinant hybrid clones. 相似文献
75.
Ronald J. Prokopy Chris Bergweiler Luis Galarza Jeri Schwerin 《Journal of Insect Behavior》1994,7(5):663-677
Females of the apple maggot fly,Rhagoletis pomonella, were allowed for 3 days to alight upon and oviposit in green or red 18- to 20-mm hawthorn host fruit (Crategus mollis) or green or red 45- to 55-mm apple host fruit (Malus pumila) hung from branches of potted host trees in field enclosures. Subsequently, when females were released individually on potted host trees harboring fruit of one of these types, their ability to find fruit of unfamiliar size proved unaffected by prior experience with fruit but their ability to find fruit of unfamiliar color was significantly affected. Specifically, females exposed to red hawthorns or red apples were less able to find green hawthorns or green apples than were females experienced with either of the latter fruit types. Fruit odor was found to have no effect on female ability to find familiar compared with unfamiliar green fruit. In contrast, a difference in size (or surface chemistry) between familiar and unfamiliar fruit but not a difference in fruit color had a significant negative influence on the propensity of alighting females to bore into unfamiliar fruit. Three bouts of experience with alighting upon and ovipositing into fruit over a period of about 1 h had no detectable effect on female ability to find unfamiliar fruit but did reduce propensity to bore into unfamiliar fruit. Our findings are discussed in relation to insect ability to learn visual and chemical stimuli of resources and insect propensity to form host races. We also discuss the potential impact of our findings on nonpesticidal, behavioral methods of managingR. pomonella in commercial apple orchards. 相似文献
76.
Julio Sáez-Vásquez Monique Raynal Luis Meza-Basso Michel Delseny 《Plant molecular biology》1993,23(6):1211-1221
In order to identify genes involved in cold acclimation, we have constructed a cDNA library from Brassica napus (cv. Samouraï) cold-acclimated etiolated seedlings. By differential screening, a cDNA clone named pBnC24 (Brassica napus Cold), corresponding to a new cold-inducible plant gene, was isolated. Northern blot hybridizations using total RNA from acclimated and unacclimated seedlings confirmed that BnC24 represents a cold-regulated gene. In contrast with a number of cold-inducible plant genes, BnC24 does not seem to be responsive to abscisic acid (ABA). In addition, further screening of the cold-acclimated cDNA library using pBnC24 cDNA as a probe, allowed the isolation of a second type of homologous cDNA. Sequence analysis showed that the two BnC24 genes encode basic 24 kDa proteins, which are highly hydrophilic and rich in alanine, lysine and arginine. The nucleotide and deduced amino acid sequences of these clones do not show any homology with other previously described cold-induced plants genes. However they have strong homology with a recently discovered human tumour gene, bbc1 (breast basic conserved), which seems to be highly conserved in eukaryotes. 相似文献
77.
Familial mediterranean fever (FMF) in Moroccan Jews: Demonstration of a founder effect by extended haplotype analysis 总被引:12,自引:9,他引:3 下载免费PDF全文
Ivona Aksentijevich Elon Pras Luis Gruberg Yang Shen Katherine Holman Sharon Helling Leandrea Prosen Grant R. Sutherland Robert I. Richards Michael Dean Mordechai Pras Daniel L. Kastner 《American journal of human genetics》1993,53(3):644-651
Familial Mediterranean fever (FMF) is an autosomal recessive disease causing attacks of fever and serositis. The FMF gene (designated “MEF”) is on 16p, with the gene order 16cen–D16S80–MEF–D16S94–D16S283–D16S291–16pter. Here we report the association of FMF susceptibility with alleles at D16S94, D16S283, and D16S291 among 31 non-Ashkenazi Jewish families (14 Moroccan, 17 non-Moroccan). We observed highly significant associations at D16S283 and D16S291 among the Moroccan families. For the non-Moroccans, only the allelic association at D16S94 approached statistical significance. Haplotype analysis showed that 18/25 Moroccan FMF chromosomes, versus 0/21 noncarrier chromosomes, bore a specific haplotype for D16S94–D16S283–D16S291. Among non-Moroccans this haplotype was present in 6/26 FMF chromosomes versus 1/28 controls. Both groups of families are largely descended from Jews who fled the Spanish Inquisition. The strong haplotype association seen among the Moroccans is most likely a founder effect, given the recent origin and genetic isolation of the Moroccan Jewish community. The lower haplotype frequency among non-Moroccan carriers may reflect differences both in history and in population genetics. 相似文献
78.
We have used a combination of densimetric, calorimetric, and uv absorption techniques to obtain a complete thermodynamic characterization for the formation of nucleic acid homoduplexes of known sequence and conformation. The volume change ΔV accompanying the formation of four duplexes was interpreted to reflect changes in hydration based on the electrostriction phenomenon. In 10 mM sodium phosphate buffer at pH 7, the magnitude of the measured ΔV's ranged from ?2.0 to +7.2 ml/mol base pair and followed the order of poly(rA) · poly(dT) ~ poly(dA) · poly(dT) < poly(rA) · poly(dU) ~ poly(rA) · poly(rU). Inclusion of 100 mM NaCl in the same buffer gave the range of ?17.4 to ?2.3 mL/mol base pair and the following order: poly(dA) · poly(dT) < poly(rA) · poly(dT) < poly(rA) · poly(rU) ~ poly(rA) ~ polyr(dU). Standard thermodynamic profiles of forming these duplexes from their corresponding complementary single strands indicated similar free energies that resulted from the compensation of favorable enthalpies with unfavorable entropies along with a similar counterion uptake at both ionic strengths. The differences in these compensating effects of entropy and enthalpy correlated very well with the volume change measurements in a manner suggesting that the homoduplexes in the B conformation are more hydrated than are those in the A conformation. Moreover, the increased thermal stability of these homoduplexes resulted from an increase in the salt concentration corresponding to larger hydration levels as reflected by the ΔV results. © 1993 John Wiley & Sons, Inc. 相似文献
79.
Tatiana L. Hernández-Palma Luis Alberto Rueda-Solano Janne K. Valkonen Bibiana Rojas 《Journal of evolutionary biology》2023,36(7):1040-1049
Deimatic displays, where sudden changes in prey appearance elicit aversive predator reactions, have been suggested to occur in many taxa. These (often only putative) displays frequently involve different components that may also serve antipredator functions via other mechanisms (e.g., mimicry, warning signalling, body inflation). The Colombian four-eyed frog, Pleurodema brachyops, has been suggested to gain protection against predation through putative deimatic displays where they inflate and elevate the posterior part of their body revealing eye-like colour markings. We exposed stationary artificial frogs to wild predators to test whether the two components (eyespot/colour markings, defensive posture) of their putative deimatic display, and their combination, provide protection from predation without the sudden change in appearance. We did not detect any obvious additive effect of defensive posture and eyespots/colour markings on predation risk, but found a marginally significant trend for model frogs in the resting posture to be less attacked when displaying eyespots/colour markings than when they were not, suggesting that the presence of colour markings/eyespots may provide some protection on its own. Additionally, we found that models in a resting posture were overall more frequently attacked on the head than models in a defensive posture, indicating that a defensive posture alone could help redirect predator attacks to non-vital parts of the body. The trends found in our study suggest that the different components of P. brachyops' coloration may serve different functions during a deimatic display, but further research is needed to elucidate the role of each component when accompanied by sudden prey movement. 相似文献
80.
Mayrel Palestino-Domínguez Alejandro Escobedo-Calvario Soraya Salas-Silva Moises Vergara-Mendoza Veronica Souza-Arroyo Roberto Lazzarini Roxana Miranda-Labra Leticia Bucio-Ortiz María Concepción Gutiérrez-Ruiz Luis E. Gomez-Quiroz 《Journal of biochemical and molecular toxicology》2023,37(4):e23302
Alcohol-induced pancreas damage remains as one of the main risk factors for pancreatitis development. This disorder is poorly understood, particularly the effect of acetaldehyde, the primary alcohol metabolite, in the endocrine pancreas. Hepatocyte growth factor (HGF) is a protective protein in many tissues, displaying antioxidant, antiapoptotic, and proliferative responses. In the present work, we were focused on characterizing the response induced by HGF and its protective mechanism in the RINm5F pancreatic cell line treated with ethanol and acetaldehyde. RINm5F cells were treated with ethanol or acetaldehyde for 12 h in the presence or not of HGF (50 ng/ml). Cells under HGF treatment decreased the content of reactive oxygen species and lipid peroxidation induced by both toxics, improving cell viability. This effect was correlated to an improvement in insulin expression impaired by ethanol and acetaldehyde. Using a specific inhibitor of Erk1/2 abrogated the effects elicited by the growth factor. In conclusion, the work provides mechanistic evidence of the HGF-induced-protective response to the alcohol-induced damage in the main cellular component of the endocrine pancreas. 相似文献