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961.
Hermit crabs have two antipredator tactics: taking refuge in its shell and fleeing. We examined the following two hypotheses using the hermit crab Pagurus filholi : (1) hermit crabs change their preference for shell types that they take refuge in and/or change the timing of fleeing (i.e. the duration of refuge in the shell) when they perceive a predator threat; (2) the type of shell that a hermit crab occupies affects the fleeing tactic of the individual. Under the stimulus of a crushed conspecific, hermit crabs changed neither their preference for shell species nor their refuge duration. On the other hand, under the stimulus of the predatory crab Gaetice depressus , hermit crabs increased their preference for Batillaria cumingi shells, which provide superior protection against predators, and shortened their refuge duration in the shells even when they occupied those effective against predation. Refuge duration was longer in B. cumingi shells than in the more vulnerable shells of Homalopoma sangarense . These results suggest that both antipredator defences (changing shell and timing of fleeing) are induced by the stimulus of a predator, and the timing of fleeing is affected by the shell type occupied. 相似文献
962.
Song Jianyu; Yamamoto Kimiko; Shomura Ayahiko; Itadani Hiraku; Zhong Hui Sun; Yano Masahiro; Sasaki Takuji 《DNA research》1998,5(2):95-101
To understand the functions of rice homologues of the Arabidopsisflowering-time gene CONSTANS (CO) and salt-tolerance gene STO,we performed a similarity search of the single-run sequencedata of cDNA clones accumulated by the Rice Genome ResearchProgram, and isolated seven rice cDNA clones (S3574, C60910,S12569, R2931, R1479, R1577, and E10707) coding for proteinscontaining one or two zinc-finger-like motifs. Comparison ofthe deduced amino acid sequences between these cDNAs and theCO gene revealed significant similarities (46%-;61%) in theregion of zinc-finger motifs. A domain having a high contentof basic amino acids at the C-terminus of the CO protein wasfound in the corresponding region of proteins predicted fromcDNAs S3574, C60910, and S12569. Two amino acid sequences, "CCADEAAL"and "FCV(L)EDRA," which were present inside each zinc-fingerin the Arabidopsis regulatory protein STO, were also found ineach of the two zinc-finger regions of proteins predicted fromcDNAs R2931, R1479, R1577, and E10707. Using restriction fragmentlength polymorphism (RFLP) linkage analysis, we determined thechromosomal location of the seven cDNA clones. The positionof R2931 on the RFLP linkage map was closely linked to Hd-3,one of the putative quantitative trait loci (QTL) controllingheading date in rice. 相似文献
963.
Masamitsu Wada 《Journal of plant research》1998,111(4):587-590
Branches were induced in centrifugedAdiantum protonemal cells by partial irradiation with polarized red light. Nuclear behavior and microtubule pattern change during
branch formation were investigated. A branch formed at any part where a red microbeam was focused along a long apical cell.
The nucleus moved towards the irradiated area and remained there until a branch developed. The pattern of microtubules changed
from parallel to oblique at the irradiated area and then a transverse arrangement of microtubules appeared on both sides of
the area. It appeared as if the nucleus was suspended between two microtubule rings. This nuclear behavior and the changes
in microtubule pattern were different from those observed during branch formation under whole cell irradiation. From the results
of this work we suggest that there is an importance for precise control of experimental conditions. 相似文献
964.
965.
966.
Regulation of the Escherichia coli hfq gene encoding the host factor for phage Q beta. 总被引:9,自引:4,他引:5
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The host factor (HF-I) for phage Q beta RNA replication is a small protein of 102 amino acid residues encoded by the hfq gene at 94.8 min on the Escherichia coli chromosome. The synthesis rate of HF-I at the exponential-growth phase is higher than at the stationary phase, and it increases concomitantly with the increase in cell growth rate. The intracellular level of HF-I is about 30,000 to 60,000 molecules per cell, the majority being associated with ribosomes as one of the salt wash proteins. Taken together, we suggest that HF-I is one of the growth-related proteins. 相似文献
967.
Akihiro Wada Toshiya Hirayama Saori Kitao Jun-ichi Fujisawa Yuji Hidaka Yasutsugu Shimonishi 《Microbiology and immunology》1994,38(7):535-541
A cDNA encoding the receptor protein for a heat-stable enterotoxin (STa) produced by enterotoxigenic Escherichia coli was cloned from intestinal epithelial cells of a 10-week-old pig. The cDNA had an open reading frame of 3,219 base pairs and coded for a protein with 1,073 amino acid residues. The mature protein consisted of 1,050 amino acid residues with a molecular mass of ca. 121 kDa and was 87% and 82% identical with the human and rat protein, respectively. The CHO cell line overexpressing the pig recombinant STa receptor specifically bound to a photoaffinity-labeled analog of STa and showed marked elevation of the cellular content of cGMP in response to STa. 相似文献
968.
969.
Coordination of karyokinesis of two nuclei in individual filamentous binucleate cells of the fern,Adiantum capillus-veneris was investigated. To induce binucleate cells, the protonemata were treated with caffeine, which is known as an inhibitor
of plant cytokinesis, during the first synchronous division of cells that was induced by blue light (BL). The next synchronous
division of cells in the resultant binucleate cells was analysed.
In most cases, the two nuclei were associated with each other and were located in the apical region of the long protonemal
cells (approximately 400–600 μm in length, 20 μm in width). In some cells, one nucleus was located in the apical region and
the other was located in the middle of the cylinderical region. In such cells, karyokinesis of the apical nucleus preceded
that of the basal nucleus, even though karyokinesis of associated nuclei progressed synchronously. Mitotic binucleate cells
were centrifuged in order to gather two dissociated heterophasic nuclei. Progression of karyokinesis in the re-associated
nuclei became coordinated within 1 h in most cells.
These results suggest that mitosis-regulating factor(s) may diffuse to only limited distances inAdiantum protonemata. 相似文献
970.
The rplI gene encoding the ribosomal protein L9 was found 4 kbp downstream from the desA gene, but on the opposite strand, in the genome of the cyanobacterium Synechocystis PCC6803. The deduced amino acid sequence is homologous to the sequences of the L9 proteins from Escherichia coli and chloroplasts of Arabidopsis and pea. The gene is present as a single copy in the chromosome and is transcribed as a mRNA of 0.64 kb. An open reading frame of unknown function (ORF291) was found in the upstream region of the rplI gene. 相似文献