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191.
To evaluate the effect of balancing selection and intragenic recombination (or gene conversion) at six individual HLA loci, synonymous nucleotide diversity in different exon groups is examined within (πw) and between (πb) allelic lineages that may be defined by either serological or DNA sequence differences. Both π values are high in exons
which encode for the peptide binding region (PBR) and tend to decrease in other exons. The value of πw is significantly smaller than that of πb in any exon of any locus. However, even πw is much greater than nucleotide diversity at non-HLA loci. These observations provide additional strong evidence for the operation of balancing selection in PBR-encoding exons
and its indirect effects on polymorphism at linked neighboring regions. It appears that allelic lineages have generally evolved
in isolation but the linkage relationships within and between exons are incomplete throughout the long evolutionary history.
To quantify intragenic recombination and account for the large discrepancy between the HLA and non-HLA diversity, a population genetics model is analyzed with special reference to the evolution of modern humans. The analysis
suggests that the recombination rate between two sites 1000 base pairs apart is about 10–5 per generation and that the effective size of human populations (equivalent roughly to the number of breeding individuals
in a randomly mating population) has dropped from 105 to 104 in most of the Quaternary. One possibility for this reduction is discussed.
Received: 11 August 1997 / Revised: 8 October 1997 相似文献
192.
Upon bacterial infection, insects secrete a set of synthesized antibacterial proteins into the hemolymph and initiate synergistic
destruction of invaders. Cecropin is one such antibacterial protein which is also found in vertebrates. To study the evolutionary
history and mechanism of the Cecropin gene family, we determined DNA sequences of one isogenic In(3R)C and six isofemale lines of Drosophila melanogaster as well as one line of D. simulans and of D. yakuba. The phylogenetic analysis of these sequences together with those published for D. virilis and Sarcophaga peregrina reveals frequent gene re-organization. It was also found that silent nucleotide differences within D. melanogaster are quite heterogeneous across the gene region of approximately 3 kilobases and the extent of polymorphism is unusually usually
high. These data suggest that the Cecropin gene region of D. melanogaster underwent intragenic recombination as well as introgression from a closely related sibling species, D. simulans.
Received: 31 July 1997 / Revised: 24 October 1997 相似文献
193.
194.
Yoko Takanaka Toshiyuki Okano Masayuki Iigo Yoshitaka Fukada 《Journal of neurochemistry》1998,70(3):908-913
195.
Christensen Steen; Tokuoka Yoko; Silverthorne Jane; Wada Masamitsu 《Plant & cell physiology》1998,39(6):647-654
Light regulates development in the fern Adiantum capillus-venerisduring both the haploid gametophyte and diploid sporophyte phases.In this study, we have investigated the role of the photoreceptorphytochrome in haploid spore germination and regulation of expressionof mRNA encoding the major light-harvesting polypeptides ofphotosystem II {Lhcb mRNAs). Both of these responses appearto be induced by phytochrome and inhibited by blue light, acting.throughseparate photoreceptor(s). Characteristics of phytochrome actionwere similar for both responses, showing no induction in thevery low fluence range and an escape from far-redreversal for 50% of the response by 6 h. Overall, these resultsshow that phytochrome regulates both a morphological and a molecularprocess in haploid fern spores, and that these processes mayshare a common signal transduction pathway. (Received February 4, 1998; Accepted April 8, 1998) 相似文献
196.
High-efficiency cloning of
Arabidopsis
full-length cDNA by biotinylated CAP trapper 总被引:17,自引:5,他引:12
Motoaki Seki Piero Carninci Yoko Nishiyama Yoshihide Hayashizaki Kazuo Shinozaki 《The Plant journal : for cell and molecular biology》1998,15(5):707-720
Full-length cDNAs are essential for functional analysis of plant genes. We constructed high-content, full-length cDNA libraries from Arabidopsis thaliana plants based on chemical introduction of a biotin group into the diol residue of the CAP structure of eukaryotic mRNA, followed by RNase I treatment, to select full-length cDNA. More than 90% of the total clones obtained were of full length; recombinant clones were obtained with high efficiency (2.2 × 106/9 μg starting mRNA). Sequence analysis of 111 randomly picked clones indicated that 32 isolated cDNA groups were derived from novel genes in the A. thaliana genome. 相似文献
197.
Naoto Takahashi Hisaya Hasegawa Mami Komiyama Takehiro Ohki Yukari Yada Yasunori Koike Ryou Kawamata Yoko Honma Mariko Momoi 《Cytokine》2009,45(1):39-43
Neonatal toxic shock syndrome (TSS)-like exanthematous disease (NTED) is an emerging neonatal infectious disease caused by TSS toxin-1 (TSST-1). Although NTED and TSS are caused by the same superantigenic exotoxin, NTED is less severe than TSS. The mechanism of this reduced severity in NTED has not been elucidated. Thirteen patients with NTED were enrolled in the study. We investigated serum cytokine profile using a cytometric bead array system with a cytokine panel. Expression of Vβ2 and CD45RO in CD4+ T cells was investigated in mononuclear cells by using flowcytometry. Ten patients with other bacterial infections and eight patients without any infections were also enrolled as control groups. The mean serum level of IL-10 was 1209.9 pg/mL in patients with NTED at the time of admission into the study. The other inhibitory cytokine, IL-4, exhibited a minimum level. The high level of IL-10 rapidly decreased within 3–9 days of the onset of NTED. The cytokine profile of NTED, with its high IL-10 level, was clearly different from that of the other bacterial infections. The increased level of IL-10 seems to be related to the reduced severity of NTED. Th2 shift is not thought to be the cause of this IL-10 excretion. 相似文献
198.
Soji Morishita Kochi Takahashi Marito Araki Yumi Hironaka Yoshitaka Sunami Yoko Edahiro Miyuki Tsutsui Akimichi Ohsaka Satoshi Tsuneda Norio Komatsu 《PloS one》2015,10(3)
Detection of the JAK2V617F mutation is essential for diagnosing patients with classical myeloproliferative neoplasms (MPNs). However, detection of the low-frequency JAK2V617F mutation is a challenging task due to the necessity of discriminating between true-positive and false-positive results. Here, we have developed a highly sensitive and accurate assay for the detection of JAK2V617F and named it melting curve analysis after T allele enrichment (MelcaTle). MelcaTle comprises three steps: 1) two cycles of JAK2V617F allele enrichment by PCR amplification followed by BsaXI digestion, 2) selective amplification of the JAK2V617F allele in the presence of a bridged nucleic acid (BNA) probe, and 3) a melting curve assay using a BODIPY-FL-labeled oligonucleotide. Using this assay, we successfully detected nearly a single copy of the JAK2V617F allele, without false-positive signals, using 10 ng of genomic DNA standard. Furthermore, MelcaTle showed no positive signals in 90 assays screening healthy individuals for JAK2V617F. When applying MelcaTle to 27 patients who were initially classified as JAK2V617F-positive on the basis of allele-specific PCR analysis and were thus suspected as having MPNs, we found that two of the patients were actually JAK2V617F-negative. A more careful clinical data analysis revealed that these two patients had developed transient erythrocytosis of unknown etiology but not polycythemia vera, a subtype of MPNs. These findings indicate that the newly developed MelcaTle assay should markedly improve the diagnosis of JAK2V617F-positive MPNs. 相似文献
199.
Kenji Ezoe Akiko Yabuuchi Tetsuya Tani Chiemi Mori Tetsuya Miki Yuko Takayama Zeki Beyhan Yoko Kato Takashi Okuno Tamotsu Kobayashi Keiichi Kato 《PloS one》2015,10(5)
Cryopreservation of mature oocytes and embryos has provided numerous benefits in reproductive medicine. Although successful cryopreservation of germinal-vesicle stage (GV) oocytes holds promise for further advances in reproductive biology and clinical embryology fields, reports regarding cryopreservation of immature oocytes are limited. Oocyte survival and maturation rates have improved since vitrification is being performed at the GV stage, but the subsequent developmental competence of GV oocytes is still low. The purpose of this study was to evaluate the effects of supplementation of the maturation medium with cyclic adenosine monophosphate (cAMP) modulators on the developmental competence of vitrified-warmed GV bovine oocytes. GV oocytes were vitrified-warmed and cultured to allow for oocyte maturation, and then parthenogenetically activated or fertilized in vitro. Our results indicate that addition of a cAMP modulator forskolin (FSK) or 3-isobutyl-1-methylxanthine (IBMX) to the maturation medium significantly improved the developmental competence of vitrified-warmed GV oocytes. We also demonstrated that vitrification of GV oocytes led to a decline in cAMP levels and maturation-promoting factor (MPF) activity in the oocytes during the initial and final phases of maturation, respectively. Nevertheless, the addition of FSK or IBMX to the maturation medium significantly elevated cAMP levels and MPF activity during IVM. Taken together, our results suggest that the cryopreservation-associated meiotic and developmental abnormalities observed in GV oocytes may be ameliorated by an artificial increase in cAMP levels during maturation culture after warming. 相似文献
200.
Shingo Kitamura Minori Enomoto Yuichi Kamei Naoko Inada Aiko Moriwaki Yoko Kamio Kazuo Mishima 《Journal of physiological anthropology》2015,34(1)