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361.
Protection of endangered desert plant species is frequently complicated by a lack of information about seeds, the most stress-resistant and populous life stage. We studied the relative locations of seeds and plants of a rare endangered herbaceous perennial, the Las Vegas bearpoppy ( Arctomecon californica ) in seven 1-ha sites randomly located within a 100-ha study area that was slated for development in Las Vegas, Nevada. We also measured the physical and biological attributes of the environment supporting the seeds and plants, including soil hardness, rock cover, cryptogamic crust cover, and associated vegetation. Arctomecon californica seed density was 0.651 seeds · m –2 , and seeds were found throughout the top 4 cm of soil. Seed viability among sites ranged from 26% to 79%; however, no significant changes between depths were detected. The spatial distribution of the seed bank coincided with the current A. californica adult distribution only in sites with both a high plant density and high numbers of seeds. Arctomecon californica adults occupied open areas within the gypsum environment that supported significantly less vegetative cover than the surrounding area. We observed a positive association between A. californica adults and shadscale ( Atriplex confertifolia ) and a negative association with 7 other plant species among sites. Sites with an indurated abiotic crust hosted higher numbers of A. californica adults than sites with softer soils. However, rock cover, cryptogamic crust cover, and soil hardness were poor explanatory factors for characterizing A. californica presence. We suggest that land managers should incorporate seed bank census into monitoring programs due to the extreme year-to-year fluctuations in A. californica plant population densities. A menudo la protección de especies de plantas desérticas en peligro de extinción se ve complicada por la falta de información sobre las semillas, la etapa de vida más abundante y resistente al estrés. Estudiamos la ubicación relativa de semillas y plantas de “Las Vegas bearpoppy” ( Arctomecon californica ), una planta perenne en peligro de extinción, en 7 sitios de 1 ha. localizados al azar dentro de un área de estudio de 100 ha que estaba destinada a la urbanización en Las Vegas, Nevada (E.U.A.). También medimos los atributos físicos y biológicos del ambiente que sostiene las semillas y plantas, tales como dureza del suelo, rocosidad, cobertura de costra cryptógama y vegetación asociada. La densidad de semillas de A. californica fue 0.651 semillas · m –2 y se observó en los 4 cm superiores del suelo. La viabilidad de las semillas varió del 26% al 79% entre los sitios; sin embargo, no detectamos cambios significativos entre profundidades. La distribución espacial del banco de semillas coincidió con la distribución actual de adultos de A. californica, sólo en sitios que tuvieron una alta densidad de plantas y altos números de semillas. Los adultos de A. californica ocuparon áreas abiertas dentro del ambiente de yeso que sostenía significativamente menos cobertura vegetal que las áreas circunvecinas. Observamos una asociación positiva entre los adultos de A. californica y el chamizo ( Atriplex confertifolia ) y una asociación negativa con siete otras especies de plantas entre sitios. Los sitios con una costra abiótica endurecida albergaron más adultos de A. californica que los sitios con suelos más blandos. No obstante, la cubierta rocosa, la costra cryptógama y la dureza del suelo fueron inadecuadas como factores para caracterizar la presencia de A. californica. Sugerimos que los manejadores de tierras deben incorporar censos de bancos de semillas en los programas de monitoreo, debido a las fluctuaciones extremas de un año a otro en la densidad poblacional de A. californica. Normal 0 MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman";} 相似文献
362.
Barton A Thomson W Ke X Eyre S Hinks A Bowes J Plant D Gibbons LJ;Wellcome Trust Case Control Consortium;YEAR Consortium;BIRAC Consortium Wilson AG Bax DE Morgan AW Emery P Steer S Hocking L Reid DM Wordsworth P Harrison P Worthington J 《Nature genetics》2008,40(10):1156-1159
The WTCCC study identified 49 SNPs putatively associated with rheumatoid arthritis at P = 1 x 10(-4) - 1 x 10(-5) (tier 3). Here we show that three of these SNPs, mapping to chromosome 10p15 (rs4750316), 12q13 (rs1678542) and 22q13 (rs3218253), are also associated (trend P = 4 x 10(-5), P = 4 x 10(-4) and P = 4 x 10(-4), respectively) in a validation study of 4,106 individuals with rheumatoid arthritis and an expanded reference group of 11,238 subjects, confirming them as true susceptibility loci in individuals of European ancestry. 相似文献
363.
364.
Laura Pavesi Dave J. Wildish Peter Gasson Miranda Lowe Valerio Ketmaier 《Journal of Natural History》2015,49(17-18):1047-1071
An unknown talitrid was discovered in 2011 in the Swale, UK, living in driftwood. Sequencing of multiple mitochondrial and nuclear genes (cytochrome oxidase I, 18S rDNA and 28S rDNA) confirms that the unknown taxon was close to Orchestia mediterranea A. Costa 1857. The driftwood in which it was found was of Douglas fir (Pseudotsuga menziesii), probably imported from North America. Relative growth methods allow us to reject the null hypothesis that the unknown taxon was a juvenile Orchestia mediterranea. This is because the unknown taxon initiates sexual maturation at an earlier moult number (neoteny) and is predicted to reach terminal moult stages at a much smaller size (dwarfism) than its closest relative O. mediterranea. Both molecular and morphological data confirm that the unknown taxon from the Swale, UK, is a new driftwood specialist taxon, distantly related to the driftwood specialist genus Macarorchestia. Additional data for body length and sex ratios are presented for Macarorchestia. In addition, relative growth methods have shown that the driftwood species Orchestia microphtalma Amanieu and Salvat 1964 is closer to the genus Macarorchestia rather than to the wrack generalist one, Orchestia. This evidence is in line with the molecular results that do not cluster morphologically defined species of Orchestia monophyletically. 相似文献
365.
Roman Goetzke Antonio Sechi Laura De Laporte Sabine Neuss Wolfgang Wagner 《Cellular and molecular life sciences : CMLS》2018,75(18):3297-3312
Mechanical stimulation affects growth and differentiation of stem cells. This may be used to guide lineage-specific cell fate decisions and therefore opens fascinating opportunities for stem cell biology and regenerative medicine. Several studies demonstrated functional and molecular effects of mechanical stimulation but on first sight these results often appear to be inconsistent. Comparison of such studies is hampered by a multitude of relevant parameters that act in concert. There are notorious differences between species, cell types, and culture conditions. Furthermore, the utilized culture substrates have complex features, such as surface chemistry, elasticity, and topography. Cell culture substrates can vary from simple, flat materials to complex 3D scaffolds. Last but not least, mechanical forces can be applied with different frequency, amplitude, and strength. It is therefore a prerequisite to take all these parameters into consideration when ascribing their specific functional relevance—and to only modulate one parameter at the time if the relevance of this parameter is addressed. Such research questions can only be investigated by interdisciplinary cooperation. In this review, we focus particularly on mesenchymal stem cells and pluripotent stem cells to discuss relevant parameters that contribute to the kaleidoscope of mechanical stimulation of stem cells. 相似文献
366.
Van Houdt JK Nowakowska BA Sousa SB van Schaik BD Seuntjens E Avonce N Sifrim A Abdul-Rahman OA van den Boogaard MJ Bottani A Castori M Cormier-Daire V Deardorff MA Filges I Fryer A Fryns JP Gana S Garavelli L Gillessen-Kaesbach G Hall BD Horn D Huylebroeck D Klapecki J Krajewska-Walasek M Kuechler A Lines MA Maas S Macdermot KD McKee S Magee A de Man SA Moreau Y Morice-Picard F Obersztyn E Pilch J Rosser E Shannon N Stolte-Dijkstra I Van Dijck P Vilain C Vogels A Wakeling E Wieczorek D 《Nature genetics》2012,44(4):445-9, S1
367.
Groesser L Herschberger E Ruetten A Ruivenkamp C Lopriore E Zutt M Langmann T Singer S Klingseisen L Schneider-Brachert W Toll A Real FX Landthaler M Hafner C 《Nature genetics》2012,44(7):783-787
Nevus sebaceous is a common congenital cutaneous malformation. Affected individuals may develop benign and malignant secondary tumors in the nevi during life. Schimmelpenning syndrome is characterized by the association of nevus sebaceous with extracutaneous abnormalities. We report that of 65 sebaceous nevi studied, 62 (95%) had mutations in the HRAS gene and 3 (5%) had mutations in the KRAS gene. The HRAS c.37G>C mutation, which results in a p.Gly13Arg substitution, was present in 91% of lesions. Nonlesional tissues from 18 individuals had a wild-type sequence, confirming genetic mosaicism. The HRAS c.37G>C mutation was also found in 8 of 8 associated secondary tumors. Mosaicism for HRAS c.37G>C and KRAS c.35G>A mutations was found in two individuals with Schimmelpenning syndrome. Functional analysis of HRAS c.37G>C mutant cells showed constitutive activation of the MAPK and PI3K-Akt signaling pathways. Our results indicate that nevus sebaceous and Schimmelpenning syndrome are caused by postzygotic HRAS and KRAS mutations. These mutations may predispose individuals to the development of secondary tumors in nevus sebaceous. 相似文献
368.
369.
Guichard C Amaddeo G Imbeaud S Ladeiro Y Pelletier L Maad IB Calderaro J Bioulac-Sage P Letexier M Degos F Clément B Balabaud C Chevet E Laurent A Couchy G Letouzé E Calvo F Zucman-Rossi J 《Nature genetics》2012,44(6):694-698
Hepatocellular carcinoma (HCC) is the most common primary liver malignancy. Here, we performed high-resolution copy-number analysis on 125 HCC tumors and whole-exome sequencing on 24 of these tumors. We identified 135 homozygous deletions and 994 somatic mutations of genes with predicted functional consequences. We found new recurrent alterations in four genes (ARID1A, RPS6KA3, NFE2L2 and IRF2) not previously described in HCC. Functional analyses showed tumor suppressor properties for IRF2, whose inactivation, exclusively found in hepatitis B virus (HBV)-related tumors, led to impaired TP53 function. In contrast, inactivation of chromatin remodelers was frequent and predominant in alcohol-related tumors. Moreover, association of mutations in specific genes (RPS6KA3-AXIN1 and NFE2L2-CTNNB1) suggested that Wnt/β-catenin signaling might cooperate in liver carcinogenesis with both oxidative stress metabolism and Ras/mitogen-activated protein kinase (MAPK) pathways. This study provides insight into the somatic mutational landscape in HCC and identifies interactions between mutations in oncogene and tumor suppressor gene mutations related to specific risk factors. 相似文献
370.
Estrada K Styrkarsdottir U Evangelou E Hsu YH Duncan EL Ntzani EE Oei L Albagha OM Amin N Kemp JP Koller DL Li G Liu CT Minster RL Moayyeri A Vandenput L Willner D Xiao SM Yerges-Armstrong LM Zheng HF Alonso N Eriksson J Kammerer CM Kaptoge SK Leo PJ Thorleifsson G Wilson SG Wilson JF Aalto V Alen M Aragaki AK Aspelund T Center JR Dailiana Z Duggan DJ Garcia M Garcia-Giralt N Giroux S Hallmans G Hocking LJ Husted LB Jameson KA Khusainova R Kim GS Kooperberg C Koromila T Kruk M Laaksonen M 《Nature genetics》2012,44(5):491-501
Bone mineral density (BMD) is the most widely used predictor of fracture risk. We performed the largest meta-analysis to date on lumbar spine and femoral neck BMD, including 17 genome-wide association studies and 32,961 individuals of European and east Asian ancestry. We tested the top BMD-associated markers for replication in 50,933 independent subjects and for association with risk of low-trauma fracture in 31,016 individuals with a history of fracture (cases) and 102,444 controls. We identified 56 loci (32 new) associated with BMD at genome-wide significance (P < 5 × 10(-8)). Several of these factors cluster within the RANK-RANKL-OPG, mesenchymal stem cell differentiation, endochondral ossification and Wnt signaling pathways. However, we also discovered loci that were localized to genes not known to have a role in bone biology. Fourteen BMD-associated loci were also associated with fracture risk (P < 5 × 10(-4), Bonferroni corrected), of which six reached P < 5 × 10(-8), including at 18p11.21 (FAM210A), 7q21.3 (SLC25A13), 11q13.2 (LRP5), 4q22.1 (MEPE), 2p16.2 (SPTBN1) and 10q21.1 (DKK1). These findings shed light on the genetic architecture and pathophysiological mechanisms underlying BMD variation and fracture susceptibility. 相似文献