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71.
Chloe E. Snider Andrew D. Stephens Jacob G. Kirkland Omar Hamdani Rohinton T. Kamakaka Kerry Bloom 《The Journal of cell biology》2014,207(2):189-199
Condensin is enriched in the pericentromere of budding yeast chromosomes where it is constrained to the spindle axis in metaphase. Pericentric condensin contributes to chromatin compaction, resistance to microtubule-based spindle forces, and spindle length and variance regulation. Condensin is clustered along the spindle axis in a heterogeneous fashion. We demonstrate that pericentric enrichment of condensin is mediated by interactions with transfer ribonucleic acid (tRNA) genes and their regulatory factors. This recruitment is important for generating axial tension on the pericentromere and coordinating movement between pericentromeres from different chromosomes. The interaction between condensin and tRNA genes in the pericentromere reveals a feature of yeast centromeres that has profound implications for the function and evolution of mitotic segregation mechanisms. 相似文献
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Manjunatha N. Belaganahalli Sushila Maan Narender S. Maan Ian Pritchard Peter D. Kirkland Joe Brownlie Houssam Attoui Peter P. C. Mertens 《PloS one》2014,9(10)
Viruses belonging to the species Wallal virus and Warrego virus of the genus Orbivirus were identified as causative agents of blindness in marsupials in Australia during 1994/5. Recent comparisons of nucleotide (nt) and amino acid (aa) sequences have provided a basis for the grouping and classification of orbivirus isolates. However, full-genome sequence data are not available for representatives of all Orbivirus species. We report full-genome sequence data for three additional orbiviruses: Wallal virus (WALV); Mudjinabarry virus (MUDV) and Warrego virus (WARV). Comparisons of conserved polymerase (Pol), sub-core-shell ‘T2’ and core-surface ‘T13’ proteins show that these viruses group with other Culicoides borne orbiviruses, clustering with Eubenangee virus (EUBV), another orbivirus infecting marsupials. WARV shares <70% aa identity in all three conserved proteins (Pol, T2 and T13) with other orbiviruses, consistent with its classification within a distinct Orbivirus species. Although WALV and MUDV share <72.86%/67.93% aa/nt identity with other orbiviruses in Pol, T2 and T13, they share >99%/90% aa/nt identities with each other (consistent with membership of the same virus species - Wallal virus). However, WALV and MUDV share <68% aa identity in their larger outer capsid protein VP2(OC1), consistent with membership of different serotypes within the species - WALV-1 and WALV-2 respectively. 相似文献
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Chimpanzee fetal G gamma and A gamma globin gene nucleotide sequences provide further evidence of gene conversions in hominine evolution 总被引:5,自引:0,他引:5
The fetal globin genes G gamma and A gamma from one chromosome of a
chimpanzee (Pan troglodytes) were sequenced and found to be closely similar
to the corresponding genes of man and the gorilla. These genes contain
identical promoter and termination signals and have exons 1 and 2 separated
by the conserved short intron 1 (122 bp) and exons 2 and 3 separated by the
more rapidly evolving, larger intron 2 (893 bp and 887 bp in chimpanzee G
gamma and A gamma, respectively). Each intron 2 has a stretch of simple
sequence DNA (TG)n serving possibly as a "hot spot" for recombination. The
two chimpanzee genes encode polypeptide chains that differ only at position
136 (glycine in G gamma and alanine in A gamma) and that are identical to
the corresponding human chains, which have aspartic acid at position 73 and
lysine at 104 in contrast to glycine and arginine at these respective
positions of the gorilla A gamma chain. Phylogenetic analysis by the
parsimony method revealed four silent (synonymous) base substitutions in
evolutionary descent of the chimpanzee G gamma and A gamma codons and none
in the human and gorilla codons. These Homininae (Pan, Homo, Gorilla)
coding sequences evolved at one-tenth the average mammalian rate for
nonsynonymous and one-fourth that for synonymous substitutions. Three
sequence regions that were affected by gene conversions between chimpanzee
G gamma and A gamma loci were identified: one extended 3' of the hot spot
with G gamma replaced by the A gamma sequence, another extended 5' of the
hot spot with A gamma replaced by G gamma, and the third conversion
extended from the 5' flanking to the 5' end of intron 2, with G gamma
replaced here by the A gamma sequence. A conversion similar to this third
one has occurred independently in the descent of the gorilla genes. The
four previously identified conversions, labeled C1-C4 (Scott et al. 1984),
were substantiated with the addition of the chimpanzee genes to our
analysis (C1 being shared by all three hominines and C2, C3, and C4 being
found only in humans). Thus, the fetal genes from all three of these
hominine species have been active in gene conversions during the descent of
each species.
相似文献
76.
Two distinct conformational states define the interaction of human RAD51‐ATP with single‐stranded DNA
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Andrea Candelli Edwige B Garcin Mauro Modesti Luca Pellegrini Gijs JL Wuite Erwin JG Peterman 《The EMBO journal》2018,37(7)
An essential mechanism for repairing DNA double‐strand breaks is homologous recombination (HR). One of its core catalysts is human RAD51 (hRAD51), which assembles as a helical nucleoprotein filament on single‐stranded DNA, promoting DNA‐strand exchange. Here, we study the interaction of hRAD51 with single‐stranded DNA using a single‐molecule approach. We show that ATP‐bound hRAD51 filaments can exist in two different states with different contour lengths and with a free‐energy difference of ~4 kBT per hRAD51 monomer. Upon ATP hydrolysis, the filaments convert into a disassembly‐competent ADP‐bound configuration. In agreement with the single‐molecule analysis, we demonstrate the presence of two distinct protomer interfaces in the crystal structure of a hRAD51‐ATP filament, providing a structural basis for the two conformational states of the filament. Together, our findings provide evidence that hRAD51‐ATP filaments can exist in two interconvertible conformational states, which might be functionally relevant for DNA homology recognition and strand exchange. 相似文献
77.
78.
The effect of bovine pestivirus infection on the superovulatory response of Friesian heifers 总被引:1,自引:0,他引:1
The pathogenesis of reproductive loss associated with bovine pestivirus infection during the preovulatory period was investigated using superovulated heifers. Twenty-five Friesian heifers were selected and randomly assigned to either a control group (n = 12) which did not become infected or to a treatment group (n = 13) which became infected following intranasal instillation of 2 ml of serum inoculum containing 5.5 log(10) TCID(50)/ml non-cytopathic virus, 9 d prior to artificial insemination (AI). Transrectal ultrasonography was used to monitor follicular development and ovulation during the superovulatory period. Animals were superovulated using a standard protocol of twice-daily injections of FSH-P and then were inseminated twice commencing 12 h after the onset of estrus. The intensity of expression of estrus was higher in the control heifers than in the pestivirus-infected heifers. Of 13 pestivirus-infected heifers, only 3 heifers displayed standing estrus compared with that in the control group, in which 10 of 12 heifers exhibited standing estrus. The mean number of ova/embryos recovered from the control group heifers was 5.75 +/-2.31, of which 4.00 +/- 0.72 were evaluated as transferable quality embryos. In comparison, heifers in the pestivirus-infected group yielded only a mean of 0.60 +/-0.34 ova/embryos, of which 0.23 +/- 0.22 were transferable quality embryos. Based on ultrasonographic examination, 24 h after the first AI 82% of the presumptive ovulatory follicles had ovulated in the control group compared with an ovulation rate of only 17% in the treated group. The results of this experiment demonstrated that bovine pestivirus infection during the preovulatory period could adversely affect ovulation, thus leading to a significant reduction in the number of palpable corpora lutea and in the number and quality of embryos recovered. 相似文献
79.
C Zinner M Krueger JL Reed M Kohl-Bareis H-C Holmberg B Sperlich 《Biology of sport / Institute of Sport》2016,33(1):71-76
In this study, we tested the hypothesis that breathing hyperoxic air (FinO2 = 0.40) while exercising in a hot environment exerts negative effects on the total tissue level of haemoglobin concentration (tHb); core (Tcore) and skin (Tskin) temperatures; muscle activity; heart rate; blood concentration of lactate; pH; partial pressure of oxygen (PaO2) and carbon dioxide; arterial oxygen saturation (SaO2); and perceptual responses. Ten well-trained male athletes cycled at submaximal intensity at 21°C or 33°C in randomized order: first for 20 min while breathing normal air (FinO2 = 0.21) and then 10 min with FinO2 = 0.40 (HOX). At both temperatures, SaO2 and PaO2, but not tHb, were increased by HOX. Tskin and perception of exertion and thermal discomfort were higher at 33°C than 21°C (p < 0.01), but independent of FinO2. Tcore and muscle activity were the same under all conditions (p > 0.07). Blood lactate and heart rate were higher at 33°C than 21°C. In conclusion, during 30 min of submaximal cycling at 21°C or 33°C, Tcore, Tskin and Tbody, tHb, muscle activity and ratings of perceived exertion and thermal discomfort were the same under normoxic and hyperoxic conditions. Accordingly, breathing hyperoxic air (FinO2 = 0.40) did not affect thermoregulation under these conditions. 相似文献
80.