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52.
JING‐WEN LI CAROL K. L. YEUNG PI‐WEN TSAI RONG‐CHIEN LIN CHIA‐FEN YEH CHENG‐TE YAO LIANXIAN HAN LE MANH HUNG PING DING QISHAN WANG SHOU‐HSIEN LI 《Molecular ecology》2010,19(3):494-507
Allopatry is conventionally considered the geographical mode of speciation for continental island organisms. However, strictly allopatric speciation models that assume the lack of postdivergence gene flow seem oversimplified given the recurrence of land bridges during glacial periods since the late Pliocene. Here, to evaluate whether a continental island endemic, the Taiwan hwamei (Leucodioptron taewanus, Passeriformes Timaliidae) speciated in strict allopatry, we used weighted‐regression‐based approximate Bayesian computation (ABC) to analyse the genetic polymorphism of 18 neutral nuclear loci (total length: 8500 bp) in Taiwan hwamei and its continental sister species, the Chinese hwamei (L. canorum canorum). The nonallopatry model was found to fit better with observed genetic polymorphism of the two hwamei species (posterior possibility = 0.82). We also recovered unambiguous signals of nontrivial bidirectional postdivergence gene flow (Nem » 1) between Chinese hwamei and Taiwan hwamei until 0.5 Ma. Divergence time was estimated to be 3.5 to 2 million years earlier than that estimated from mitochondrial cytochrome b sequences. Finally, using the inferred nonallopatry model to simulate genetic variation at 24 nuclear genes examined showed that the adiponectin receptor 1 gene may be under divergent adaptation. Our findings imply that the role of geographical barrier may be less prominent for the speciation of continental island endemics, and suggest a shift in speciation studies from simply correlating geographical barrier and genetic divergence to examining factors that facilitate and maintain divergence, e.g. differential selection and sexual selection, especially in the face of interpopulation gene flow. 相似文献
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54.
MEI‐TING WANG YU‐CHENG HSU CHENG‐TE YAO SHOU‐HSIEN LI 《Molecular ecology resources》2005,5(2):439-442
From a partial genomic library enriched for GATA short tandem repeats, we developed 12 polymorphic microsatellite loci from the green‐backed tit (Parus monticolus). We characterized these loci by genotyping 30 adult individuals with unknown relationship. The number of alleles ranged from four to 17 per locus (mean = 9.3 alleles) and the observed heterozygosity for each locus ranged from 0.633 to 0.933 (mean = 0.789). All loci conformed to Hardy–Weinberg expectations. Four of 66 possible pairwise comparisons between loci showed significant gametic disequilibrium. 相似文献
55.
Soraya Leal-Bertioli Kenta Shirasawa Brian Abernathy Marcio Moretzsohn Carolina Chavarro Josh Clevenger Peggy Ozias-Akins Scott Jackson David Bertioli 《Genetics》2015,199(4):1093-1105
Arachis hypogaea L. (cultivated peanut) is an allotetraploid (2n = 4x = 40) with an AABB genome type. Based on cytogenetic studies it has been assumed that peanut and wild-derived induced AABB allotetraploids have classic allotetraploid genetic behavior with diploid-like disomic recombination only between homologous chromosomes, at the exclusion of recombination between homeologous chromosomes. Using this assumption, numerous linkage map and quantitative trait loci studies have been carried out. Here, with a systematic analysis of genotyping and gene expression data, we show that this assumption is not entirely valid. In fact, autotetraploid-like tetrasomic recombination is surprisingly frequent in recombinant inbred lines generated from a cross of cultivated peanut and an induced allotetraploid derived from peanut’s most probable ancestral species. We suggest that a better, more predictive genetic model for peanut is that of a “segmental allotetraploid” with partly disomic, partly tetrasomic genetic behavior. This intermediate genetic behavior has probably had a previously overseen, but significant, impact on the genome and genetics of cultivated peanut. 相似文献
56.
BP ONeill TM Habermann TE Witzig M Rodriguez 《Cancer immunology, immunotherapy : CII》1999,16(3):211-215
Five patients at risk for primary central nervous system lymphoma (PCNSL) recurrence were treated with high-dose methylprednisolone,
(HDMP) to prevent ‘trafficking’ of malignant lymphocytes into the central nervous system (CNS). HDMP was chosen because of
its ability to stabilize the ‘blood brain barrier (BBB)’. Three men with newly diagnosed PCNSL, ages 62, 76 and 78 y, whose
survival was projected to be 6.6 months, began treatment after achieving complete response (CR) to initial radiation therapy
alone and survived 27, 37 and 59 months after treatment. In none was death from recurrent disease in CNS but one patient did
die of systemic non-Hodgkin’s lymphoma (NHL) five years after PCNSL diagnosis. A 20 y old man was treated with HDMP after
successful combined modality therapy and is alive 75+months after initial diagnosis without evidence of disease recurrence.
A 34 y old man relapsed after combined modality initial treatment and failed to respond to HDMP when treatment was begun after
unsuccessful salvage therapy; he died of disease 12 months after initial diagnosis. There were no treatment complications.
The promising results in this pilot study from the basis for a North Central Cancer Treatment Group (NCCTG) 96-73-51, a Phase
2 clinical trial of brain radiotherapy and HDMP for PCNSL patients 70 y of age and older, a group of patients at high risk
for toxicity from intensive combined modality therapy. 相似文献
57.
Ligand-independent dimerization of the human prolactin receptor isoforms: functional implications 总被引:4,自引:0,他引:4
Prolactin (PRL) contributes to the growth of normal and malignant breast tissues. PRL initiates signaling by engaging the PRL receptor (PRLr), a transmembrane (TM) receptor belonging to the cytokine receptor family. The accepted view has been that PRL activates the PRLr by inducing dimerization of the receptor, but recent reports show ligand-independent dimerization of other cytokine receptors. Using coimmunoprecipitation assays, we have confirmed ligand-independent dimerization of the PRLr in T47D breast cancer and HepG2 liver carcinoma cells. In addition, mammalian cells transfected with differentially epitope-tagged isoforms of the PRLr indicated that long, intermediate, and DeltaS1 PRLrs dimerized in a ligand-independent manner. To determine the domain(s) involved in PRLr ligand-independent dimerization, we generated PRLr constructs as follows: (1) the TM-ICD, which consisted of the TM domain and the intracellular domain (ICD) but lacked the extracellular domain (ECD), and (2) the ECD-TM, which consisted of the TM domain and the ECD but lacked the ICD. These constructs dimerized in a ligand-independent manner in mammalian cells, implicating a significant role for the TM domain in this process. These truncated PRLrs were functionally inert alone or in combination in cells lacking the PRLr. However, when introduced into cells containing endogenous PRLr, the ECD-TM inhibited human PRLr signaling, whereas the TM-ICD potentiated human PRLr signaling. These studies indicate that the ECD-TM and the TM-ICD are capable of modulating PRLr function. We also demonstrated an endogenous TM-ICD in T47D cells, suggesting that these findings are relevant to PRL-signaling pathways in breast cancer. 相似文献
58.
59.
An analysis was performed to determine the mechanism of depressed maternal weight gain and its effect on perinatal lethality following prenatal exposure to diethylstilbestrol (DES). Pregnant Sprague-Dawley rats were dosed orally by gavage with DES or corn oil (control) during various intervals of gestation. The maternal weight-gain patterns of control and treated dams and the number of live offspring were recorded. The amounts of feed and water intake and feces and urine output in pregnant dams were measured, and metabolic rate and thyroid hormone levels were also determined. DES (at 45 micrograms/kg/day) was embryo- and fetolethal during implantation and parturition, and there was an accompanying decline in maternal weight. Growth of adult males, nonpregnant females, and weanlings of both sexes was also depressed. During pregnancy, the net intake of feed and water was not altered by the drug, but maternal serum thyroxine and metabolic rate were significantly elevated. Reduced metabolic efficiency, then, is the likely mechanism for weight depression. Reduction of maternal weight gain during pregnancy by DES is a diagnostic indicator of fetolethality, but is probably not causally related to it. 相似文献
60.
OXYGEN RELATIONS OF THE ROOT NODULES OF ALNUS RUBRA BONG. 总被引:2,自引:1,他引:1