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41.
Barley, Hordeum vulgare L., is well adapted to subarctic Alaska growing conditions, but little is known about its response to grasshopper defoliation. A field experiment was conducted to study dry matter and grain yield in response to a combination of grasshopper defoliation and weeds in 2002 and 2003 near Delta Junction, AK (63 degrees 55' N, 145 degrees 20' W). Barley plants at third to fourth leaf stage were exposed to a combination of two levels of weeds (present or absent) and four densities of grasshoppers (equivalent to 0, 25, 50, and 75 grasshoppers per m2) of third to fourth instars of Melanoplus sanguinipes (F). Dry matter accumulation by the barley plants was determined at three times during the growing seasons: approximately 10 d after introduction of the grasshoppers, shortly after anthesis, and at maturity. Dry matter accumulation and grain yield were much lower in 2003 than in 2002, probably due to very low levels of soil moisture early in the growing season of 2003. Head clipping accounted for a greater portion of yield loss in 2003 than in 2002. The percentage of reduction in harvestable yield due to grasshoppers remained fairly constant between years (1.9 and 1.4 g per grasshopper per m2 in 2002 and 2003, respectively) despite a large difference in overall yield. Examination of the yield components suggest that yields were reduced by the early season drought in 2003 primarily through fewer seeds per head, whereas grasshoppers in both years reduced average seed weight, but not numbers of seeds. 相似文献
42.
Through adaptive cross-generational plasticity, stressed plants can alter their offspring in specific ways that promote seedling success. As yet, very little is known about the expression of such plasticity, and whether it varies within a plant due to offspring position. The effects of parental light deprivation on distinct reproductive structures were tested in the annual Polygonum hydropiper, which produces both long terminal racemes and inconspicuous axial inflorescences. Inbred replicate parents from four genetic lines were grown in full greenhouse sunlight and simulated shade, and the initial mass, germination rate, and seedling growth traits of their terminal and axial offspring measured under uniform growth chamber conditions. Although parent light environment did not significantly influence seedlings from axial achenes, growth traits of those from terminal achenes were significantly enhanced as a result of parental light deprivation. In shaded conditions where resources are limiting, P. hydropiper plants appear to prioritize terminal achenes through increased provisioning as well as specific growth changes. These results show that the expression of cross-generational plasticity may vary depending on architectural position of offspring on the maternal plant. 相似文献
43.
Plastic and constant developmental traits contribute to adaptive differences in co-occurring Polygonum species 总被引:3,自引:0,他引:3
Adaptive differences among species are often thought to result from developmentally constant trait differences that enhance fitness in alternative environments. Species differences in patterns of individual phenotypic plasticity can also have ecological consequences. Indeed, functionally related constant and plastic traits may interact to determine the phenotype's adaptive value in particular conditions. We compared juvenile shade avoidance traits (height and its components, internode length and node number) across two field density treatments in Polygonumpersicaria and P. hydropiper, annual plant species that co‐occur in pastures comprised of a mosaic of plant densities. We used selection analyses to test trait contributions to fitness in alternative density treatments. Seedlings of both species expressed plasticity for internode elongation in response to density; P. persicaria plants increased internode length and consequently height significantly more in high density than did those of P. hydropiper. As predicted by the shade avoidance hypothesis, increased height was adaptive for both species in high density stands, so P. persicaria plants had higher fitness in this environment. By contrast, node numbers were relatively constant across density treatments in both species: P. hydropiper seedlings consistently produced more nodes than did those of P. persicaria. This constant trait difference contributed to P. hydropiper's greater relative fitness at low density, where more nodes and hence leaves enable plants to better exploit available light. Differences between species in these juvenile shade‐avoidance traits did not result from the evolutionary constraints of lack of heritable variation or costs of plasticity. We discuss how these interspecific trait differences may have been generated by divergent selective histories resulting from differences in herbivore resistance. These results illustrate how adaptive differences in both plastic and constantly expressed traits may jointly contribute to ecological distribution, including coexistence in patchy habitats. 相似文献
44.
Plantago is the most important genus of Plantaginaceae family and is used in traditional medicine around the world for different purposes.
Plantago coronopus L., Plantago major L., Plantago media L. and Plantago lanceolata L. are most commonly used species of Plantago in traditional medicine in Turkey. The main goal of this study was to investigate the eventual anti-mitotic and anti-genotoxic
effects of P. lanceolata L. leaf aqueous extracts (15 g/L and 30 g/L) on Allium cepa L. root tip meristem cells which were treated with 0.7% hydrogen peroxide. For this purpose, two different experiments were
performed under the same conditions. In the first experiment, Allium cepa onion bulbs were treated with 0.7% H2O2 for 1 h. After the H2O2 treatment, the onion bulbs were treated with two different concentrations (15 g/L and 30 g/L) of P. lanceolata extracts for 24 h. In the second experiment, A. cepa onion bulbs were treated with two different extract concentrations (15 g/L and 30 g/L) for 24 h and then with 0.7% H2O2 for 1 h. The test concentrations were determined according to doses which are recommended in alternative medicinal usage
by people. As positive and negative control 0.7% H2O2 and tap water was used, respectively. As a result, it was determined that aqueous extracts reduced mitotic index and chromosome
aberrations in treatment groups in comparison with controls. These results showed that P. lanceolata aqueous extracts have anti-mitotic and anti-genotoxic effects. 相似文献
45.
Kalfa N Fukami M Philibert P Audran F Pienkowski C Weill J Pinto G Manouvrier S Polak M Ogata T Sultan C 《PloS one》2012,7(3):e32505
More than 50% of children with severe 46,XY disorders of sex development (DSD) do not have a definitive etiological diagnosis. Besides gonadal dysgenesis, defects in androgen biosynthesis, and abnormalities in androgen sensitivity, the Mastermind-like domain containing 1 (MAMLD1) gene, which was identified as critical for the development of male genitalia, may be implicated. The present study investigated whether MAMLD1 is implicated in cases of severe 46,XY DSD and whether routine sequencing of MAMLD1 should be performed in these patients.Seventy children with severe non-syndromic 46,XY DSD of unknown etiology were studied. One hundred and fifty healthy individuals were included as controls. Direct sequencing of the MAMLD1, AR, SRD5A2 and NR5A1 genes was performed. The transactivation function of the variant MAMLD1 proteins was quantified by the luciferase method.TWO NEW MUTATIONS WERE IDENTIFIED: p.S143X (c.428C>A) in a patient with scrotal hypospadias with microphallus and p.P384L (c.1151C>T) in a patient with penile hypospadias with microphallus. The in vitro functional study confirmed no residual transactivating function of the p.S143X mutant and a significantly reduced transactivation function of the p.P384L protein (p = 0.0032). The p.P359S, p.N662S and p.H347Q variants are also reported with particularly high frequency of the p.359T- p.662G haplotype in the DSD patients.Severe undervirilization in XY newborns can reveal mutations of MAMLD1. MAMLD1 should be routinely sequenced in these patients with otherwise normal AR, SRD5A2 and NR5A1genes. 相似文献
46.
Daniel Biermann Andreas Heilmann Michael Didié Saskia Schlossarek Azadeh Wahab Michael Grimm Maria R?mer Hermann Reichenspurner Karim R. Sultan Anna Steenpass Süleyman Ergün Sonia Donzelli Lucie Carrier Heimo Ehmke Wolfram H. Zimmermann Lutz Hein Rainer H. B?ger Ralf A. Benndorf 《PloS one》2012,7(10)
Background
The angiotensin II receptor subtype 2 (AT2 receptor) is ubiquitously and highly expressed in early postnatal life. However, its role in postnatal cardiac development remained unclear.Methodology/Principal Findings
Hearts from 1, 7, 14 and 56 days old wild-type (WT) and AT2 receptor-deficient (KO) mice were extracted for histomorphometrical analysis as well as analysis of cardiac signaling and gene expression. Furthermore, heart and body weights of examined animals were recorded and echocardiographic analysis of cardiac function as well as telemetric blood pressure measurements were performed. Moreover, gene expression, sarcomere shortening and calcium transients were examined in ventricular cardiomyocytes isolated from both genotypes. KO mice exhibited an accelerated body weight gain and a reduced heart to body weight ratio as compared to WT mice in the postnatal period. However, in adult KO mice the heart to body weight ratio was significantly increased most likely due to elevated systemic blood pressure. At postnatal day 7 ventricular capillarization index and the density of α-smooth muscle cell actin-positive blood vessels were higher in KO mice as compared to WT mice but normalized during adolescence. Echocardiographic assessment of cardiac systolic function at postnatal day 7 revealed decreased contractility of KO hearts in response to beta-adrenergic stimulation. Moreover, cardiomyocytes from KO mice showed a decreased sarcomere shortening and an increased peak Ca2+ transient in response to isoprenaline when stimulated concomitantly with angiotensin II.Conclusion
The AT2 receptor affects postnatal cardiac growth possibly via reducing body weight gain and systemic blood pressure. Moreover, it moderately attenuates postnatal vascularization of the heart and modulates the beta adrenergic response of the neonatal heart. These AT2 receptor-mediated effects may be implicated in the physiological maturation process of the heart. 相似文献47.
Amardeep Kour Abdul S. Shawl Suriya Rehman Phalisteen Sultan Parvaiz H. Qazi Pankaj Suden Ravi K. Khajuria Vijeshwar Verma 《World journal of microbiology & biotechnology》2008,24(7):1115-1121
Podophyllotoxin, a well-known naturally occurring aryltetralin lignan occurs in few plant species that is used as a precursor
for the chemical synthesis of the anticancer drugs like etoposide, teniposide and etopophose phosphate. The availiability
of this lignan is becoming increasingly limited because of the scarce occurance of its natural sources and also because synthetic
approaches for its production are still commercially unacceptable. This paper reports first time the production of podophyllotoxin
by an endophytic fungus Fusarium oxysporum isolated from the medicinal plant Juniperus recurva. Further confirmation and quantification of podophyllotoxin was performed by HPLC, LC-MS, and LC-MS/MS. 相似文献
48.
Promising directions in plant phenotypic plasticity 总被引:9,自引:0,他引:9
A research agenda for the next phase of plasticity studies calls for contributions from a diverse group of biologists, working both independently and collaboratively, to pursue four promising directions: examining dynamic, anatomical/architectural, and cross-generational plasticity along with simpler growth traits; carefully assessing the adaptive significance of those plasticity patterns; investigating the intricate transduction pathways that lead from environmental signal to phenotypic response; and considering the rich environmental context of natural systems. Progress in these areas will allow us to address broad and timely questions regarding the ecological and evolutionary significance of plasticity and the nature of phenotypic determination. 相似文献
49.
J M Lobaccaro S Lumbroso C Sultan 《Comptes rendus des séances de la Société de biologie et de ses filiales》1991,185(6):422-433
Androgen insensitivity syndromes are X-linked disorders. Restriction fragment length polymorphism analysis of the androgen receptor gene showed that deletions were infrequent. Some mutations have been described. In these conditions, in high-risk family, carrier diagnosis is impossible unless identification of mutations is made. It is thus necessary to detect androgen receptor gene polymorphism in order to differentiate the two maternal X chromosomes. Two androgen receptor gene polymorphisms have been reported (Hind III and exon 1). In this study we analyzed these two gene polymorphisms to detect carriers in at-risk families. The combined results of the two analyses allowed us to detect carriers in 45% of the studied families. In two families the prenatal diagnosis of androgen insensitivity syndrome was performed. 相似文献
50.
It has been suggested that rate of estrogen formation was higher in patients with androgen insensitivity syndrome (AIS). This work was designed to find out if peripheral aromatase activity could be related to a defect in androgen action in prepubertal children with male pseudohermaphroditism. Fibroblast estrogen production was assayed by a highly specific enzymatic determination. Foreskin fibroblast strains were raised from 17 children with partial androgen insensitivity (PAIS) as defined by dihydrotestosterone binding activity in cells. Results are expressed as pmol estrogens/mg proteins synthetized/day when cultured fibroblasts are incubated with D4-androstenedione. In normal prepubertal boys (n = 19), aromatase activity ranged between 5 and 10 pmol estrogens/mg proteins/day, while in postpubertal boys it varied between 15 and 34 pmol estrogens/mg proteins/day. In prepubertal boys with PAIS (n = 17) aromatase activity is highly elevated: 19.4 +/- 8.4 pmol/mg proteins/day. These results show that (a) peripheral aromatase activity is low before puberty and (b) fibroblast estrogen synthesis is significantly (p less than 0.001) increased in prepubertal children with PAIS. Our data suggest that low utilization of androgens by target cells stimulates the production of estrogen. Peripheral aromatase activity can thus be considered as a 'marker' of androgen insensitivity in prepubertal children with male pseudohermaphroditism. 相似文献