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161.
Lochlainn SO Fray RG Hammond JP King GJ White PJ Young SD Broadley MR 《The New phytologist》2011,189(2):409-414
Noccaea caerulescens (formerly Thlaspi caerulescens) is a widely studied metal hyperaccumulator. However, molecular genetic studies are challenging in this species because of its vernal-obligate biennial life cycle of 7-9months. Here, we describe the development of genetically stable, faster cycling lines of N. caerulescens which are nonvernal-obligate. A total of 5500 M(0) seeds from Saint Laurent Le Minier (France) were subjected to fast neutron mutagenesis. Following vernalization of young plants, 79% of plants survived to maturity. In all, 80,000 M(2) lines were screened for flowering in the absence of vernalization. Floral initials were observed in 35 lines, with nine flowering in <12wk. Two lines (A2 and A7) were selfed to the M(4) generation. Floral initials were observed 66 and 87d after sowing (DAS) in A2 and A7, respectively. Silicle development occurred for all A2 and for most A7 at 92 and 123 DAS, respectively. Floral or silicle development was not observed in wild-type (WT) plants. Leaf zinc (Zn) concentration was similar in WT, A2 and A7 lines. These lines should facilitate future genetic studies of this remarkable species. Seed is publicly available through the European Arabidopsis Stock Centre (NASC). 相似文献
162.
Stress responses play a key role in allowing animals to cope with change and challenge in the face of both environmental certainty
and uncertainty. Measurement of glucocorticoid levels, key elements in the neuroendocrine stress axis, can give insight into
an animal’s well-being and can aid understanding ecological and evolutionary processes as well as conservation and management
issues. We give an overview of the four main biological samples that have been utilized [blood, saliva, excreta (feces and
urine), and integumentary structures (hair and feathers)], their advantages and disadvantages for use with wildlife, and some
of the background and pitfalls that users must consider in interpreting their results. The matrix of choice will depend on
the nature of the study and of the species, on whether one is examining the impact of acute versus chronic stressors, and
on the degree of invasiveness that is possible or desirable. In some cases, more than one matrix can be measured to achieve
the same ends. All require a significant degree of expertise, sometimes in obtaining the sample and always in extracting and
analyzing the glucocorticoid or its metabolites. Glucocorticoid measurement is proving to be a powerful integrator of environmental
stressors and of an animal’s condition. 相似文献
163.
Schöpper H Palme R Ruf T Huber S 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2011,181(8):1089-1100
Stress, when extreme or chronic, can have a negative impact on health and survival of mammals. This is especially true for
females during reproduction when self-maintenance and investment in offspring simultaneously challenge energy turnover. Therefore,
we investigated the effects of repeated stress during early- and mid-gestation on the maternal stress axis, body weight gain
and reproductive output. Female guinea pigs (Cavia aperea f. porcellus, n = 14) were either stressed (treatment: exposure to strobe light in an unfamiliar environment on gestational day -7, 0, 7,
14, 21, 28, 35, 42) or left completely undisturbed (control) throughout pregnancy. Females of both groups received the same
respective diets, and reproductive parameters were evaluated upon parturition. Additionally, hormonal data were obtained from
blood and feces. The stress exposure induced a significant increase in plasma cortisol concentrations during the afternoon.
In contrast to this short-term response in plasma cortisol concentrations, we found no significant differences in the levels
of cortisol metabolites in feces collected after stress exposure between groups and even significantly decreased levels of
fecal cortisol metabolites on non-stress days over time in treatment females. Among treatment females, gain in body weight
was attenuated over gestation and body weight was lower compared to control females during lactation, especially in cases
of large litter sizes. No differences could be seen in the reproductive parameters. We conclude that repeated stress exposure
with strobe light during early- and mid-gestation results in a down-regulation of the hypothalamic–pituitary–adrenal axis
and lower weight gain in treatment females, but has no effect on reproductive output. 相似文献
164.
Constitutional Mutations of the hSNF5/INI1 Gene Predispose to a Variety of Cancers 总被引:8,自引:0,他引:8 下载免费PDF全文
Nicolas Svenet Eammon Sheridan Daniel Amram Pascale Schneider Rupert Handgretinger Olivier Delattre 《American journal of human genetics》1999,65(5):1342-1348
Biallelic, truncating mutations of the hSNF5/INI1 gene have recently been documented in malignant rhabdoid tumor (MRT), one of the most aggressive human cancers. This finding suggests that hSNF5/INI1 is a new tumor-suppressor gene for which germline mutations might predispose to cancer. We now report the presence of loss-of-function mutations of this gene in the constitutional DNA from affected members but not from healthy relatives in cancer-prone families. Furthermore, a constitutional mutation is documented in a patient with two successive primary cancers. In agreement with the two-hit model, the wild-type hSNF5/INI1 allele is deleted in the tumor DNA from mutation carriers. In all tested cases, DNA from parents demonstrated normal hSNF5/INI1 sequences, therefore indicating the de novo occurrence of the mutation, which was shown to involve the maternal allele in one case and the paternal allele in two other cases. These data indicate that constitutional mutation of the hSNF5/INI1 gene defines a new hereditary syndrome predisposing to renal or extrarenal MRT and to a variety of tumors of the CNS, including choroid plexus carcinoma, medulloblastoma, and central primitive neuroectodermal tumor. This condition, which we propose to term "rhabdoid predisposition syndrome," may account for previous observations of familial and multifocal cases of the aforementioned tumor types. It could also provide the molecular basis for cases of Li-Fraumeni syndrome without p53 germline mutations. 相似文献
165.
Suspensions of Dictyostelium discoideum amoebae display free-running light scattering oscillations at the onset of development. We describe a device to monitor these oscillations in several samples in parallel. The apparatus consists of a thermostated cuvette holder where up to eight cuvettes containing cell suspension are inserted. Cells are aerated and kept in suspension via an airlift. Infrared light emitted from a five-diode array passes through the suspension and is detected by an array of five light detecting diodes. The resulting signal is digitized and recorded with a sampling rate of two measuring points/second. The parallel analysis approach allows determination of the effects of adding of agents or of variations in the external conditions in the same batch of amoebae at the same developmental time point. This represents an advantage over the conventional single cuvette approach, as oscillation characteristics themselves are developmentally regulated. Moreover, as the new experimental setup enables simultaneous analyses of up to eight samples, the behavior of wild-type and several mutant strains can be compared under identical experimental conditions. 相似文献
166.
167.
168.
Rupert C. Barneby 《Brittonia》1991,43(3):168-170
Lupinus elaphoglossum Barneby, related toL. crotalarioides Mart. ex Benth., but differing in leaves and stipules, is described and illustrated. 相似文献
169.
Christopher J. Williamson Rupert Perkins Marian L. Yallop César Peteiro Noemí Sanchez Karl Gunnarsson 《欧洲藻类学杂志》2018,53(3):290-306
This study characterizes the photoacclimation and photoregulation mechanisms that allow calcified macroalgae of the genus Corallina (Corallinales, Rhodophyta) to dominate rock pool habitats across the NE Atlantic despite the highly variable irradiance regimes experienced. Rapid light curves (RLCs) were performed with pulse amplitude modulation (PAM) fluorometry in situ across a full seasonal cycle in the UK intertidal with C. officinalis and C. caespitosa. Latitudinal comparisons were performed across the full extent of C. officinalis’ range in the NE Atlantic (Iceland–northern Spain), and for C. caespitosa in northern Spain. Ex situ RLCs with dark recovery were further employed to assess the optimal, as compared with actual, photophysiology across seasons and latitudes. Corallina species were shown to photoacclimate at seasonal timescales to changing irradiance, increasing light-harvesting during low-light autumn/winter periods and protecting photosystems during high-light summer conditions. Seasonal photoacclimation was achieved through alteration in the number of photosystem (PS) units (PSII and light harvesting antennae) over time. Non-photochemical quenching (NPQ) served as an important photoregulation mechanism utilized by Corallina to prevent or minimize photoinhibition over shorter time scales (seconds–hours), though the efficiency of NPQ was dependent on the seasonal-acclimated state. With increasing latitude the efficiency of photoregulation decreased, representing potential differential photoadaptation of Corallina across species ranges in the NE Atlantic. In contrast, highly conserved inter-specific patterns in photophysiological responses to irradiance were apparent. This study demonstrates the photophysiological mechanisms allowing Corallina to optimize use of the variable irradiance conditions apparent in rock pool environments, when and how they are employed, and their limitations. 相似文献
170.