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101.
Male hermit crabs perform precopulatory mate-guarding behavior during their reproductive season. As females generally cannot reject guarding attempts by males, male guarding prevents females from inspecting and choosing other male mates. However, as guarding males are often replaced by other males through competition for females during the guarding phase, females may be able to select males by delaying their copulation. To examine the possibility of female choice by hermit crabs, we investigated whether female Pagurus filholi that were being guarded in the field were ready to copulate and spawn. We found that about 30% of females guarded in the field were ready to spawn, indicating that guarded females delayed copulation with their current male. Our results suggest that by delaying copulation females may exploit male–male competition to choose dominant males. However, delaying copulation reduced the spawning potential of females. Hence, there is a trade-off between waiting for the opportunity to mate with a dominant male and decreased spawning success if females exploit male–male competition. 相似文献
102.
6-Pyruvoyltetrahydropterin synthase (PTPS) catalyzes the second step of tetrahydrobiopterin (BH4) synthesis. We previously identified PTPS orthologs (bPTPS-Is) in bacteria which do not produce BH4. In this study we disrupted the gene encoding bPTPS-I in Synechococcus sp. PCC 7942, which produces BH4-glucoside. The mutant was normal in BH4-glucoside production, demonstrating that bPTPS-I does not participate in BH4 synthesis in vivo and bringing us a new PTPS ortholog (bPTPS-II) of a bimodular polypeptide. The recombinant Synechococcus bPTPS-II was assayed in vitro to show PTPS activity higher than human enzyme. Further computational analysis revealed the presence of mono and bimodular bPTPS-II orthologs mostly in green sulfur bacteria and cyanobacteria, respectively, which are well known for BH4-glycoside production. In summary we found new bacterial PTPS orthologs, having either a single or dual domain structure and being responsible for BH4 synthesis in vivo, thereby disclosing all the bacterial PTPS homologs. 相似文献
103.
Ali MM Nagatsugi F Sasaki S Nakahara R Maeda M 《Nucleosides, nucleotides & nucleic acids》2006,25(2):159-169
Attempts have been made to conjugate a variety of molecules with oligonucleotides to achieve useful functions. In this study, we have established a new efficient method for post-synthetic conjugation of oligonucleotides with the use of the 2-amino-6-vinylpurine nucleoside. Amino nucleophiles form the corresponding conjugates under acidic conditions, whereas thiol nucleophiles reacted efficiently under alkaline conditions. Thus, glutathione and HS-Cys-(Arg)8 without protecting groups were efficiently conjugated to the 2-amino-6-vinylpurine-bearing ODN under alkaline conditions. The use of 2-amino-6-vinylpurine as an agent for conjugation is advantageous in that it is stable during the reaction and may be applied to conjugation of ODNs with multiple functional molecules. 相似文献
104.
Hye-Lim KimMi-Bee Park Yumin KimYun Gyeong Yang Soo-Woong LeeNingning Zhuang Kon Ho Lee Young Shik Park 《FEBS letters》2012,586(20):3596-3600
We have studied the regulatory function of Dictyostelium discoideum Ax2 phenylalanine hydroxylase (dicPAH) via characterization of domain structures. Including the full-length protein, partial proteins truncated in regulatory, tetramerization, or both, were prepared from Escherichia coli as his-tag proteins and examined for oligomeric status and catalytic parameters for phenylalanine. The proteins were also expressed extrachromosomally in the dicPAH knockout strain to examine their in vivo compatibility. The results suggest that phenylalanine activates dicPAH, which is functional in vivo as a tetramer, although cooperativity was not observed. In addition, the results of kinetic study suggest that the regulatory domain of dicPAH may play a role different from that of the domain in mammalian PAH.
Structured summary of protein interactions
dicPAH and dicPAHbind by molecular sieving (View Interaction: 1, 2, 3, 4) 相似文献105.
Tumor suppression in the absence of p53-mediated cell-cycle arrest, apoptosis, and senescence 总被引:1,自引:0,他引:1
Cell-cycle arrest, apoptosis, and senescence are widely accepted as the major mechanisms by which p53 inhibits tumor formation. Nevertheless, it remains unclear whether they are the rate-limiting steps in tumor suppression. Here, we have generated mice bearing lysine to arginine mutations at one (p53(K117R)) or three (p53(3KR); K117R+K161R+K162R) of p53 acetylation sites. Although p53(K117R/K117R) cells are competent for p53-mediated cell-cycle arrest and senescence, but not apoptosis, all three of these processes are ablated in p53(3KR/3KR) cells. Surprisingly, unlike p53 null mice, which rapidly succumb to spontaneous thymic lymphomas, early-onset tumor formation does not occur in either p53(K117R/K117R) or p53(3KR/3KR) animals. Notably, p53(3KR) retains the ability to regulate energy metabolism and reactive oxygen species production. These findings underscore the crucial role of acetylation in differentially modulating p53 responses and suggest that unconventional activities of p53, such as metabolic regulation and antioxidant function, are critical for suppression of early-onset spontaneous tumorigenesis. 相似文献
106.
Ken-ichi Itoh Kaoru Nakamura Tadashi Aoyama Ryusuke Matsuba Tsuyoshi Kakimoto Masahiko Murakami Rio Yamanaka Toshiya Muranaka Hiroshi Sakamaki Toshio Takido 《Biotechnology letters》2012,34(11):2083-2086
Aromatic ketones were reduced using suspension culture of Chlorella sp. MK201 under fluorescent light illumination producing the corresponding chiral alcohols in high yields with excellent enantiomeric excess (ee). For example, 2′,3′,4′,5′,6′-pentafluoroacetophenone at 0.25?mg/ml was converted to the corresponding (S)-alcohol in 80?% yield with?>99?% ee by 1?mg dry wt of Chlorella/ml in 12?h illumination (2,000 lux). 相似文献
107.
It is well accepted that the Mdm2 ubiquitin ligase acts as a major factor in controlling p53 stability and activity in vivo. Although several E3 ligases have been reported to be involved in Mdm2-independent p53 degradation, the roles of these ligases in p53 regulation in vivo remain largely unknown. To elucidate the physiological role of the ubiquitin ligase ARF-BP1, we generated arf-bp1 mutant mice. We found that inactivation of arf-bp1 during embryonic development in mice resulted in p53 activation and embryonic lethality, but the mice with arf-bp1 deletion specifically in the pancreatic β-cells (arf-bp1(FL/Y)/RIP-cre) were viable and displayed no obvious abnormality after birth. Interestingly, these mice showed dramatic loss of β-cells as mice aged, and >50% of these mice died of severe diabetic symptoms before reaching 1 year of age. Notably, the diabetic phenotype of these mice was largely reversed by concomitant deletion of p53, and the life span of the mice was significantly extended (p53(LFL/FL)/arf-bp1(FL/Y)/RIP-cre). These findings underscore an important role of ARF-BP1 in maintaining β-cell homeostasis in aging mice and reveal that the stability of p53 is critically regulated by ARF-BP1 in vivo. 相似文献
108.
Franc V Sebela M Rehulka P Končitíková R Lenobel R Madzak C Kopečný D 《Journal of Proteomics》2012,75(13):4027-4037
Cytokinin oxidase/dehydrogenase (CKO; EC 1.5.99.12) irreversibly degrades the plant hormones cytokinins. A recombinant maize isoenzyme 1 (ZmCKO1) produced in the yeast Yarrowia lipolytica was subjected to enzymatic deglycosylation by endoglycosidase H. Spectrophotometric assays showed that both activity and thermostability of the enzyme decreased after the treatment at non-denaturing conditions indicating the biological importance of ZmCKO1 glycosylation. The released N-glycans were purified with graphitized carbon sorbent and analyzed by MALDI-TOF MS. The structure of the measured high-mannose type N-glycans was confirmed by tandem mass spectrometry (MS/MS) on a Q-TOF instrument with electrospray ionization. Further experiments were focused on direct analysis of sugar binding. Peptides and glycopeptides purified from tryptic digests of recombinant ZmCKO1 were separated by reversed-phase chromatography using a manual microgradient device; the latter were then subjected to offline-coupled analysis on a MALDI-TOF/TOF instrument. Glycopeptide sequencing by MALDI-TOF/TOF MS/MS demonstrated N-glycosylation at Asn52, 63, 134, 294, 323 and 338. The bound glycans contained 3-14 mannose residues. Interestingly, Asn134 was found only partially glycosylated. Asn338 was the sole site to carry large glycan chains exceeding 25 mannose residues. This observation demonstrates that contrary to a previous belief, the heterologous expression in Y. lipolytica may lead to locally hyperglycosylated proteins. 相似文献
109.
Renata Juri?i? Grube?i? Dario Kremer Marijana Zovko Kon?i? Jadranka Vukovi? Rodríguez Marko Randi? 《Central European Journal of Biology》2012,7(6):1092-1100
The content of biologically active phenolic compounds (total polyphenols, tannins, flavonoids, and phenolic acids) were determined using spectrophotometry in four wild Croatian species of Daphne L. in the family Thymelaeaceae (Daphne alpina, D. cneorum, D. laureola, and D. mezereum). The concentration of total flavonoids (TF) was highest in the leaves of these Daphne species (0.12?C0.51% dry herb weight, DW) whereas the content of other phenolic compounds analyzed were highest in the roots, including total polyphenols (TP; 2.71?C19.03% DW), tannins (T; 1.14?C7.39% DW), and total phenolic acids (TPA; 0.12?C0.87% DW). D. alpina contained the highest amount of polyphenols, with the exception of flavonoids, where maximum concentrations were found in D. laureola. We also examined the antioxidant activity of leaf, stem, and root extracts. All extracts analyzed demonstrated high free radical scavenging activity with the highest concentration in the leaf extracts of D. alpina. Leaf extracts of D. cneorum showed the highest antioxidant activity in a ??-carotene bleaching assay. 相似文献
110.
Thomas F��rst Kigbafori D. Silu�� Mamadou Ouattara Dje N. N'Goran Lukas G. Adiossan Yao N'Guessan Fabian Zouzou Siaka Kon�� Eli��zer K. N'Goran J��rg Utzinger 《PLoS neglected tropical diseases》2012,6(10)