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171.
To understand the detailed mechanisms underlying variations in seed productivity per cone, it is important to examine simultaneously the effects of two pollination mode components (pollen supply and quality) on two seed production processes (seed formation and maturation). We conducted artificial pollination experiments with four pollination treatments (selfing, polycross, no-pollination and open-pollination treatments) in each of two vertical crown layers (upper and lower) for 19 Pinus densiflora ramets. We measured formed seeds as a proportion of ovules (P(Form)), and filled seeds as a proportion of formed seeds (P(Fill)) per cone in each treatment and layer, and inferred the relative influences of pollination mode and resource availability on seed productivity. In the no-pollination treatment, no seeds were formed in any cones of all five ramets. The Generalized Linear Model showed that there were no significant differences in P(Form) both between selfing and polycross treatments and upper and lower layers. The mean P(Fill) values in the selfing treatment were significantly lower than those in the polycross treatment in both layers. The mean P(Fill)s of the two layers did not differ significantly in the selfing treatment, but did in the open-pollination and polycross treatments. The results show that pollen supply affects mainly seed formation, whereas pollen quality affects mainly seed maturation. Resource availability also affects mainly seed maturation, if pollen quality is higher than a certain threshold. 相似文献
172.
Fujinaga M Maeda J Yui J Hatori A Yamasaki T Kawamura K Kumata K Yoshida Y Nagai Y Higuchi M Suhara T Fukumura T Zhang MR 《Journal of neurochemistry》2012,120(1):115-124
Neurovascular degeneration contributes to the pathogenesis of Alzheimer's disease (AD). Because erythropoietin (EPO) promotes endothelial regeneration, we investigated the therapeutic effects of EPO in animal models of AD. In aged Tg2576 mice, EPO receptors (EPORs) were expressed in the cortex and hippocampus. Tg2576 mice were treated with daily injection of EPO (5000 IU/kg/day) for 5 days. At 14 days, EPO improved contextual memory as measured by fear-conditioning test. EPO enhanced endothelial proliferation and the level of synaptophysin expression in the brain. EPO also increased capillary density, and decreased the level of the receptor for advanced glycation endproducts (RAGE) in the brain, while decreasing in the amount of amyloid plaque and amyloid-β (Aβ). In cultured human endothelial cells, EPO enhanced angiogenesis and suppressed the expression of the RAGE. These results show that EPO improves memory and ameliorates endothelial degeneration induced by Aβ in AD models. This pre-clinical evidence suggests that EPO may be useful for the treatment of AD. 相似文献
173.
Hyung Suk Kim Karen M. Lyons Eiichi Saitoh Edwin A. Azen Oliver Smithies Nobuyo Maeda 《Mammalian genome》1993,4(1):3-14
We present the nucleotide sequences of four members of the six-member human salivary prolinerich protein (PRP) gene family. The four genes are PRB1 and PRB2, which encode basic PRPs, and PRB3 and PRB4, which encode glycosylated PRPs. Each PRB gene is approximately 4.0 kb in length and contains four exons, the third of which is entirely composed of 63-bp tandem repeats and encodes the proline-rich portion of the protein products. Exon 3 contains different numbers of tandem repeats in the different PRB genes. Variation in the numbers of these repeats is also responsible for length variations in different alleles of the PRB genes. We have determined a probable evolutionary history of the human PRP gene family by comparing the nucleotide sequences of the six PRP genes. The present-day six PRP loci probably evolved from a single ancestral gene by four sequential gene duplications, leading to six genes that fall into three subsets, each consisting of two genes. During this evolutionary process, multiple rearrangements and gene conversion occurred mainly in the region from the 3 end of IVS2 and the 3 end of exon 3. 相似文献
174.
Imai H Saito M Kirai N Hasegawa J Konishi K Hattori H Nishimura M Naito S Nakagawa Y 《Journal of biochemistry》2006,140(4):573-590
175.
176.
S. Shiraishi H. Maeda T. Toda K. Seido Y. Sasaki 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2001,102(6-7):935-941
Using a fluorescence-based PCR-SSCP (single-strand conformation polymorphism), we verified imperfectibility in the paternal
inheritance of chloroplast DNA (cpDNA) in Chamaecyparis
obtusa (Cupressaceae) controlled crosses. An intraspecific sequence polymorphism of the intergenic spacer region between the trnD and trnY genes was utilized as a molecular marker. Of 361 progenies, in which the cpDNA haplotypes of their female and male parents
were different, 352 (97.5%) possessed the same haplotypes as their male parents, and nine (2.5%) the same haplotypes as their
female parents. The parentage of the nine progenies with female parental types was diagnosed using DNA fingerprinting based
on fluorescence-based RAPD profiles. Their parentage showed convincing evidence of the low frequency of maternal inheritance.
Moreover, heteroplasmy was observed in the open-pollinated seeds collected in a seed orchard. The confirmation of maternal
plastid transmission in the full-sib families and the observation of heteroplasmy in seeds reveal that the paternal inheritance
of cpDNA is not an exclusive phenomenon and that the mode of its inheritance is biparental in C. obtusa.
Received: 15 April 2000 / Accepted: 13 July 2000 相似文献
177.
Microbial toxins in plant-pathogen interactions: Biosynthesis,resistance mechanisms,and significance
In the history of phytopathology, microbial toxins have been the objects of extensive studies as possible pathogenicity or virulence factors for the producer pathogens. The recent development of molecular genetic techniques provided an experimental basis to thoroughly test the role of these secondary metabolites in pathogenesis. Some of them did prove to be highly associated with disease initiation or enhanced virulence in certain plant-pathogen interactions. In this review, we describe recent progresses in the field of plant-pathogen interactions focusing on two toxins; i.e., tabtoxin from Pseudomonas syringae and trichothecenes from Fusarium and other fungi. These microbial toxins have convincingly been shown to play causal roles in plant disease development. Studies on the biosynthesis and resistance mechanisms of these producers are outlined, and the significance of this knowledge is discussed in relation to practical applications in agriculture. 相似文献
178.
179.
Kuwata H Fujimoto C Yoda E Shimbara S Nakatani Y Hara S Murakami M Kudo I 《The Journal of biological chemistry》2007,282(28):20124-20132
Group IIA secretory phospholipase A(2) (sPLA(2)-IIA) is a prototypic sPLA(2) enzyme that may play roles in modification of eicosanoid biosynthesis as well as antibacterial defense. In several cell types, inducible expression of sPLA(2) by pro-inflammatory stimuli is attenuated by group IVA cytosolic PLA(2) (cPLA(2)alpha) inhibitors such as arachidonyl trifluoromethyl ketone, leading to the proposal that prior activation of cPLA(2)alpha is required for de novo induction of sPLA(2). However, because of the broad specificity of several cPLA(2)alpha inhibitors used so far, a more comprehensive approach is needed to evaluate the relevance of this ambiguous pathway. Here, we provide evidence that the induction of sPLA(2)-IIA by pro-inflammatory stimuli requires group VIB calcium-independent PLA(2) (iPLA(2)gamma), rather than cPLA(2)alpha, in rat fibroblastic 3Y1 cells. Results with small interfering RNA unexpectedly showed that the cytokine induction of sPLA(2)-IIA in cPLA(2)alpha knockdown cells, in which cPLA(2)alpha protein was undetectable, was similar to that in replicate control cells. By contrast, knockdown of iPLA(2)gamma, another arachidonyl trifluoromethyl ketone-sensitive intracellular PLA(2), markedly reduced the cytokine-induced expression of sPLA(2)-IIA. Supporting this finding, the R-enantiomer of bromoenol lactone, an iPLA(2)gamma inhibitor, suppressed the cytokine-induced sPLA(2)-IIA expression, whereas (S)-bromoenol lactone, an iPLA(2)beta inhibitor, failed to do so. Moreover, lipopolysaccharide-stimulated sPLA(2)-IIA expression was also abolished by knockdown of iPLA(2)gamma. These findings open new insight into a novel regulatory role of iPLA(2)gamma in stimulus-coupled sPLA(2)-IIA expression. 相似文献
180.
Chieko Hosaka Makoto Kunisada Michiyo Koyanagi‐Aoi Taro Masaki Chihiro Takemori Mariko Taniguchi‐Ikeda Takashi Aoi Chikako Nishigori 《Pigment cell & melanoma research》2019,32(5):623-633
Induced pluripotent stem cell (iPSC) technology offers a novel approach for conversion of human primary fibroblasts into melanocytes. During attempts to explore various protocols for differentiation of iPSCs into melanocytes, we found a distinct and self‐renewing cell lineage that could differentiate into melanocytes, named as melanocyte precursor cells (MPCs). The MPCs exhibited a morphology distinctive from that of melanocytes, in lacking either the melanosomal structure or the melanocyte‐specific marker genes MITF, TYR, and SOX10. In addition, gene expression studies in the MPCs showed high‐level expression of WNT5A, ROR2, which are non‐canonical WNT pathway markers, and its related receptor TGFβR2. In contrast, MPC differentiation into melanocytes was achieved by activating the canonical WNT pathway using the GSK3β inhibitor. Our data demonstrated the distinct characteristic of MPCs' ability to differentiate into melanocytes, and the underlying mechanism of interfacing between canonical WNT signaling pathway and non‐canonical WNT signaling pathway. 相似文献