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61.
62.
Mitsue Shibata Satoshi Kikuchi Hiroshi Tanaka Masahiro Sueyoshi Hiroshi Yoshimaru Kaoru Niiyama 《Ecological Research》2009,24(1):1-9
The effects of local population density, sex morph [protogynous (PG) or protandrous (PA)], and individual tree size on the
demographic processes of seed production were investigated in a heterodichogamous maple, Acer mono Maxim. var. Marmoratum (Nichols.) Hara f. dissectum, in a temperate forest of Japan. As the distance from conspecific reproductive adults increased, the percentage of immature
seed fall and empty seeds increased significantly, indicating higher pollination success along with local population density.
Although the difference was not distinct, pollination success was affected by the local population density of the reciprocal
sex morph rather than that of both sex morphs. The trees at higher local population density sites suffered higher seed mortality
due to predation and decay, and tended to produce smaller seeds. Thus, the impacts of local population density operated both
positively and negatively on reproduction. As a factor of individual traits, tree size scarcely affected any demographic processes.
On the other hand, sex morph did affect pollination success. Trees of PG type had lower immature seed fall than those of PA
type, suggesting that the former has higher efficiency of pollen acceptance than the latter. The results on seed demography
presented here partly support previous suggestions that heterodichogamous plants exhibit reciprocal cross-pollination and
gender specialization as reproductive traits. 相似文献
63.
Serikawa T Suzuki N Kikuchi H Tanaka K Kitagawa T 《Biochimica et biophysica acta》2000,1467(2):419-430
Cationic liposomes are useful to transfer genes into eukaryotic cells in vitro and in vivo. However, liposomes with good transfection efficiency are often cytotoxic, and also require serum-free conditions for optimal activity. In this report, we describe a new formulation of cationic liposome containing DC-6-14, O,O'-ditetradecanoyl-N-(alpha-trimethylammonioacetyl)diethan olamine chloride, dioleoylphosphatidylethanolamine and cholesterol for gene delivery into cultured human cells. This liposome, dispersed in 5% serum-containing growth medium, efficiently delivered a plasmid DNA for GFP (green fluorescent protein) into more than 80% of the cultured human cell hybrids derived from HeLa cells and normal fibroblasts. Flow cytometric analysis revealed that the efficiency of the GFP gene expression was 40-50% in a tumor-suppressed cell hybrid, while it was greatly reduced in the tumorigenic counterpart. The enhanced GFP expression in tumor-suppressed cell hybrids was quantitatively well correlated with a prolonged presence of the plasmid DNA, which had been labeled with another fluorescent probe, ethidium monoazide, within the cells. These results suggest that a newly developed cationic liposome is useful for gene delivery in serum-containing medium into human cells and the stability of the plasmid DNA inside the cell is a crucial step in this liposome-mediated gene expression. The mechanisms by which cationic liposome mediates gene transfer into eukaryotic cells are also discussed. 相似文献
64.
Shotaro Hirase Yo Y Yamasaki Masashi Sekino Masato Nishisako Minoru Ikeda Motoyuki Hara Juha Meril Kiyoshi Kikuchi 《Molecular biology and evolution》2021,38(11):4683
How early stages of speciation in free-spawning marine invertebrates proceed is poorly understood. The Western Pacific abalones, Haliotis discus, H. madaka, and H. gigantea, occur in sympatry with shared breeding season and are capable of producing viable F1 hybrids in spite of being ecologically differentiated. Population genomic analyses revealed that although the three species are genetically distinct, there is evidence for historical and ongoing gene flow among these species. Evidence from demographic modeling suggests that reproductive isolation among the three species started to build in allopatry and has proceeded with gene flow, possibly driven by ecological selection. We identified 27 differentiation islands between the closely related H. discus and H. madaka characterized by high FST and dA, but not high dXY values, as well as high genetic diversity in one H. madaka population. These genomic signatures suggest differentiation driven by recent ecological divergent selection in presence of gene flow outside of the genomic islands of differentiation. The differentiation islands showed low polymorphism in H. gigantea, and both high FST, dXY, and dA values between H. discus and H. gigantea, as well as between H. madaka and H. gigantea. Collectively, the Western Pacific abalones appear to occupy the early stages speciation continuum, and the differentiation islands associated with ecological divergence among the abalones do not appear to have acted as barrier loci to gene flow in the younger divergences but appear to do so in older divergences. 相似文献
65.
Collagen gel contraction by fibroblasts requires cellular fibronectin but not plasma fibronectin 总被引:7,自引:0,他引:7
Fibroblasts embedded in three-dimensional lattices of collagen fibrils have been known to require serum constituents to induce a cell-mediated contraction of collagen gels. The gel contraction was studied with human skin fibroblasts cultured in the presence of fetal bovine serum (FBS). Removal of bovine serum fibronectin (sFN) from FBS did not affect the extent of gel contraction. Gel contraction occurred in serum-free defined media. Therefore, it is concluded that sFN is not required for gel contraction. That cellular FN (cFN) synthesized and secreted by fibroblasts plays a crucial role in gel contraction was suggested by the following experiments: (1) We obtained monoclonal antibodies (mAb A3A5) against fibroblast surface antigens, which suppressed the fibroblast-mediated gel contraction. Immunoblot analyses showed that mAb A3A5 recognizes cFN secreted by human fibroblasts and human plasma FN (pFN), but not bovine sFN in FBS used for culture. (2) Addition of rabbit antisera, which recognize human cFN, to a serum-free gel culture inhibited contraction. Uninvolvement of human pFN in gel contraction was further confirmed by the fact that neither pretreatment of fibroblasts with excess amounts of human pFN nor the presence of excess amounts of human pFN in gels affected the extent of gel contraction. This study seems to be the first demonstration of functional difference between cFN and pFN (or sFN) and proposes a novel mode of binding of fibroblasts with collagen fibrils via cFN during cell-mediated collagen morphogenesis. 相似文献
66.
67.
Yo Morimoto Jun-ya Shibata Mizuki Takahata Omar Myint Masanori Kohda 《Journal of Ethology》2010,28(3):429-436
Like many other gobies, male Isaza (Gymnogobius isaza) which are endemic to Lake Biwa, Japan, exclusively care for broods in nests. This goby may have an optimal range of brood
size (i.e., an average clutch size of about 2000–3000 eggs) within which they may produce larger numbers of hatching young
because much larger broods may be destroyed by fungal infection before hatching. This optimal brood size hypothesis (Takahashi
et al. in J Ethol 22:153–159, 2004) predicts that (1) after spawning, both males and females will refuse additional spawning by other gravid females (second
females) to keep brood sizes within optimal ranges, (2) larger fish will repel second females more successfully than will
smaller fish, and thus, (3) both sexes prefer larger mates. To examine these predictions, we first observed Isaza’s aggressive
behaviors in aquaria and investigated whether fish attacked and repelled second females that were introduced after spawning,
and, if so, what were the sizes of fish that did so. Large fish, regardless of sex, aggressively prevented second females
from entering the nest, but second females larger than the pairs displaced the pair females forcibly and spawned eggs into
their clutches. Mate choice experiments showed that males preferred large females. Although females’ choice of large mates
was not confirmed, many results may largely coincide with the predictions of the optimal brood size hypothesis. Thus, Isaza
males’ choice of large mates will be advantageous for defending against brood parasitism by conspecific females and for achieving
optimal clutch size. 相似文献
68.
Insecticide applications to soil contribute to the development of Burkholderia mediating insecticide resistance in stinkbugs 下载免费PDF全文
Kanako Tago Yoshitomo Kikuchi Sinji Nakaoka Chie Katsuyama Masahito Hayatsu 《Molecular ecology》2015,24(14):3766-3778
Some soil Burkholderia strains are capable of degrading the organophosphorus insecticide, fenitrothion, and establish symbiosis with stinkbugs, making the host insects fenitrothion‐resistant. However, the ecology of the symbiotic degrading Burkholderia adapting to fenitrothion in the free‐living environment is unknown. We hypothesized that fenitrothion applications affect the dynamics of fenitrothion‐degrading Burkholderia, thereby controlling the transmission of symbiotic degrading Burkholderia from the soil to stinkbugs. We investigated changes in the density and diversity of culturable Burkholderia (i.e. symbiotic and nonsymbiotic fenitrothion degraders and nondegraders) in fenitrothion‐treated soil using microcosms. During the incubation with five applications of pesticide, the density of the degraders increased from less than the detection limit to around 106/g of soil. The number of dominant species among the degraders declined with the increasing density of degraders; eventually, one species predominated. This process can be explained according to the competitive exclusion principle using Vmax and Km values for fenitrothion metabolism by the degraders. We performed a phylogenetic analysis of representative strains isolated from the microcosms and evaluated their ability to establish symbiosis with the stinkbug Riptortus pedestris. The strains that established symbiosis with R. pedestris were assigned to a cluster including symbionts commonly isolated from stinkbugs. The strains outside the cluster could not necessarily associate with the host. The degraders in the cluster predominated during the initial phase of degrader dynamics in the soil. Therefore, only a few applications of fenitrothion could allow symbiotic degraders to associate with their hosts and may cause the emergence of symbiont‐mediated insecticide resistance. 相似文献
69.
Park SH Kim CM Je BI Park SH Park SJ Piao HL Xuan YH Choe MS Satoh K Kikuchi S Lee KH Cha YS Ahn BO Ji HS Yun DW Lee MC Suh SC Eun MY Han CD 《Planta》2007,227(1):1-12
OSH6 (Oryza sativa Homeobox6) is an ortholog of lg3 (Liguleless3) in maize. We generated a novel allele, termed OSH6-Ds, by inserting a defective Ds element into the third exon of OSH6, which resulted in a truncated OSH6 mRNA. The truncated mRNA was expressed ectopically in leaf tissues and encoded the N-terminal region of OSH6, which includes
the KNOX1 and partial KNOX2 subdomains. This recessive mutant showed outgrowth of bracts or produced leaves at the basal node
of the panicle. These phenotypes distinguished it from the OSH6 transgene whose ectopic expression led to a “blade to sheath transformation” phenotype at the midrib region of leaves, similar
to that seen in dominant Lg3 mutants. Expression of a similar truncated OSH6 cDNA from the 35S promoter (35S::ΔOSH6) confirmed that the ectopic expression of this product was responsible for the aberrant bract development. These data suggest
that OSH6-Ds interferes with a developmental mechanism involved in bract differentiation, especially at the basal nodes of panicles.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
70.