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981.
Lance S. Davidow Matthew Breen Shannon E. Duke Paul B. Samollow John R. McCarrey Jeannie T. Lee 《Chromosome research》2007,15(2):137-146
X-chromosome inactivation (XCI) evolved in mammals to deal with X-chromosome dosage imbalance between the XX female and the
XY male. In eutherian mammals, random XCI of the soma requires a master regulatory locus known as the ‘X-inactivation center’
(XIC/Xic), wherein lies the noncoding XIST/Xist silencer RNA and its regulatory antisense Tsix gene. By contrast, marsupial XCI is imprinted to occur on the paternal X chromosome. To determine whether marsupials and
eutherians share the XIC-driven mechanism, we search for the sequence equivalents in the genome of the South American opossum, Monodelphis domestica. Positional cloning and bioinformatic analysis reveal several interesting findings. First, protein-coding genes that flank
the eutherian XIC are well-conserved in M. domestica, as well as in chicken, frog, and pufferfish. However, in M. domestica we fail to identify any recognizable XIST or TSIX equivalents. Moreover, cytogenetic mapping shows a surprising break in synteny with eutherian mammals and other vertebrates.
Therefore, during the evolution of the marsupial X chromosome, one or more rearrangements broke up an otherwise evolutionarily
conserved block of vertebrate genes. The failure to find XIST/TSIX in M. domestica may suggest that the ancestral XIC is too divergent to allow for detection by current methods. Alternatively, the XIC may have arisen relatively late in mammalian evolution, possibly in eutherians with the emergence of random XCI. The latter
argues that marsupial XCI does not require XIST and opens the search for alternative mechanisms of dosage compensation. 相似文献
982.
中国人的婚姻质量状况 总被引:5,自引:0,他引:5
目的:调查中国人婚烟满意状况。方法:用中国人婚姻质量问卷对1303名已婚者进行调查,其中夫妻配对资料224对。结果:无论是男性还是女性,总体满意度都处于中等水平,基本上呈正态分布,仅在性格相容和子女婚姻两个维度有统计学差异;约60%以上的人觉得自己的婚姻比较满意,30%的人认为基本满意,5%的体验到非常满意,只有2%左右的人感到不满意;夫妻婚姻质量具有较高的相关性,主观满意度一致的人数占60%以上,不一致或很不一致的人数只占100%。结论:中国人的总体婚姻质量处于中等水平,90%的夫妻对自己的婚姻感到满意,只有2%左右的人感到不满意。 相似文献
983.
Evaluation of Etest MBL for detection of blaIMP-1 and blaVIM-2 allele-positive clinical isolates of Pseudomonas spp. and Acinetobacter spp 总被引:10,自引:0,他引:10
Lee K Yong D Yum JH Lim YS Bolmström A Qwärnström A Karlsson A Chong Y 《Journal of clinical microbiology》2005,43(2):942-944
The Etest MBL (AB BIODISK, Solna, Sweden) correctly differentiated all 57 isolates of Acinetobacter spp. and Pseudomonas aeruginosa with the bla(IMP-1) allele and 135 of 137 (98.5%) Acinetobacter spp. and Pseudomonas spp. isolates with the bla(VIM-2) allele. The Etest MBL was reliable for detecting the IMP-1- and VIM-2-producing Pseudomonas and Acinetobacter isolates. 相似文献
984.
Yu HB Rao PS Lee HC Vilches S Merino S Tomas JM Leung KY 《Infection and immunity》2004,72(3):1248-1256
Aeromonas hydrophila is a gram-negative opportunistic pathogen in fish and humans. Many bacterial pathogens of animals and plants have been shown to inject anti-host virulence determinants into the hosts via a type III secretion system (TTSS). Degenerate primers based on lcrD family genes that are present in every known TTSS allowed us to locate the TTSS gene cluster in A. hydrophila AH-1. A series of genome walking steps helped in the identification of 25 open reading frames that encode proteins homologous to those in TTSSs in other bacteria. PCR-based analysis showed the presence of lcrD homologs (ascV) in all of the 33 strains of A. hydrophila isolated from various sources. Insertional inactivation of two of the TTSS genes (aopB and aopD) led to decreased cytotoxicity in carp epithelial cells, increased phagocytosis, and reduced virulence in blue gourami. These results show that a TTSS is required for A. hydrophila pathogenesis. This is the first report of sequencing and characterization of TTSS gene clusters from A. hydrophila. The TTSS identified here may help in developing suitable vaccines as well as in further understanding of the pathogenesis of A. hydrophila. 相似文献
985.
Scrapie is a transmissible spongiform encephalopathy in which there is an accumulation of the abnormal form of the prion protein, PrPsc, in the lymphoreticular system and nervous system. There is a particular accumulation of PrPsc on follicular dendritic cells within the germinal centre of B-cell follicles. Because accumulation of PrPsc in the nervous system leads to neuronal cell loss we have examined PrPsc accumulation in the prescapular and mesenteric lymph nodes in relation to lymph node architecture of scrapie-challenged sheep. We demonstrate that an accumulation of PrPsc in the lymph node fails to result in gross defects in the microanatomy and phenotype of T- and B-cell areas in the lymph nodes. 相似文献
986.
Colgin LL Kubota D Brucher FA Jia Y Branyan E Gall CM Lynch G 《Journal of neurophysiology》2004,92(6):3385-3398
Spontaneous negative-going potentials occurring at an average frequency of 0.7 Hz were recorded from the dentate gyrus of slices prepared from the temporal hippocampus of young adult rats. These events (here termed "dentate waves") in several respects resembled the dentate spikes described for freely moving rats during immobile behaviors and slow-wave sleep. Action potentials were observed on the descending portion of the in vitro waves and, as expected from this, whole cell recordings established that the waves were composed of depolarizing currents. Dentate waves appeared to be locally generated within the granule cell layer and were greatly reduced by antagonists of AMPA-type glutamate receptors or by lesions to the entorhinal cortex. Simultaneous recordings indicated that the waves were often synchronized in the inner and outer blades of the dentate gyrus. Knife cuts through the perforant path and the commissural/associational system did not eliminate synchronization, leaving electrotonic propagation via gap junctions as its probable cause. In accord with this, cuts that separated the two blades of the dentate eliminated synchronization between them, and a compound that inhibits gap junctions reduced wave activity. Dentate waves were regularly accompanied by sharp waves in field CA3 and were reduced in size by the acetylcholinesterase inhibitor, physostigmine. It is hypothesized that dentate waves occur when spontaneous glutamate release from dentate afferents produces action potentials in neighboring granule cells that then summate electrotonically into a population event; once initiated, the waves propagate, again electrotonically, and thereby engage a significant portion of the granule cell population. 相似文献
987.
Wang H Lee JK Moursi AM Anderson D Winnard P Powell H Lannutti J 《Journal of biomedical materials research. Part A》2004,68(1):61-70
Microstructural factors may play a role in the osseointegration of calcium phosphates. In this paper, direct microstructural interactions between crystalline calcium phosphates and the biological milieu are reported. Degradation via exposure to osteoblast culture closely resembles in vivo interactions with subcutaneous tissues in a bovine model at early time periods. That these interactions were common to both experiments constitutes one of the few known examples of in vitro-in vivo correspondence. Interestingly, the degradation of phase pure hydroxyapatite (HA) in vitro was more rapid than that of biphasic HA in vivo. In both cases, grain extraction/pullout was frequently observed. This suggests a connection to smaller-scale observations of epitaxial CHA nucleation and growth on pre-existing HA grains. A microstructure in which the grain boundary is dissolving/corroding can apparently be disassembled by forces transmitted through biological structures. These observations are distinct from those of simple non-biological solutions and prove that biological environments can interact with the material beneath the ceramic-cell/ceramic-tissue interface. Many often ignored microstructural factors-grain size, shape, grain boundary strength and the presence of impurity phases-may in fact control degradation. We also suggest that even relatively modest initial grain sizes will, in combination with the mild/absent foreign body response to calcium phosphates, result in lengthy in vivo particle resistence. 相似文献
988.
Paul Kruszka Tommy Hu Sungkook Hong Rebecca Signer Benjamin Cogné Betrand Isidor Sarah E. Mazzola Jacques C. Giltay Koen L. I. van Gassen Eleina M. England Lynn Pais Charlotte W. Ockeloen Pedro A. Sanchez‐Lara Esther Kinning Darius J. Adams Kayla Treat Wilfredo Torres‐Martinez Maria F. Bedeschi Maria Iascone Stephanie Blaney Oliver Bell Tiong Y. Tan Marie‐Ange Delrue Julie Jurgens Brenda J. Barry Elizabeth C. Engle Sarah K. Savage Nicole Fleischer Julian A. Martinez‐Agosto Kym Boycott Elaine H. Zackai Maximilian Muenke 《American journal of medical genetics. Part A》2019,179(10):2075-2082
Zinc finger protein 462 (ZNF462) is a relatively newly discovered vertebrate specific protein with known critical roles in embryonic development in animal models. Two case reports and a case series study have described the phenotype of 10 individuals with ZNF462 loss of function variants. Herein, we present 14 new individuals with loss of function variants to the previous studies to delineate the syndrome of loss of function in ZNF462. Collectively, these 24 individuals present with recurring phenotypes that define a multiple congenital anomaly syndrome. Most have some form of developmental delay (79%) and a minority has autism spectrum disorder (33%). Characteristic facial features include ptosis (83%), down slanting palpebral fissures (58%), exaggerated Cupid's bow/wide philtrum (54%), and arched eyebrows (50%). Metopic ridging or craniosynostosis was found in a third of study participants and feeding problems in half. Other phenotype characteristics include dysgenesis of the corpus callosum in 25% of individuals, hypotonia in half, and structural heart defects in 21%. Using facial analysis technology, a computer algorithm applying deep learning was able to accurately differentiate individuals with ZNF462 loss of function variants from individuals with Noonan syndrome and healthy controls. In summary, we describe a multiple congenital anomaly syndrome associated with haploinsufficiency of ZNF462 that has distinct clinical characteristics and facial features. 相似文献
989.
990.
K. K. H. Lee 《Anatomy and embryology》1992,186(1):67-74
Summary The regulative potential of the fore-limb region following the removal of the limb bud was investigated in 11.5-day rat embryos. Fore-limb buds were amputated from a total of 54 embryos. Five embryos were immediately examined via scanning electron microscopy (SEM) to assess the quality of the operation and the reproducibility of the technique. In all cases, the forelimb bud and adjacent tissues extending down to the celomic cavity at the same level were completely removed. The remaining 49 operated embryos were cultured in vitro and examined at different time intervals. Gross inspection of embryos which had been cultured for 24 h, revealed that 24 out of 37 had developed a pair of limb bud-like protrusions at the operation site. Twelve formed only a single protrusion, while nothing was found in the remaining embryo. These protrusions were examined in greater detail under SEM and light microscopy. SEM observations showed that these protrusions were covered with an intact layer of ectoderm. In embryos with a pair of protrusions, these outgrowths developed opposite somites 7 to 13. The failure of either one of these two outgrowths to form, produced our second type of experimental embryo, those which had just a single protrusion. Histological examination revealed that an apical ectodermal ridge (AER) was discernible on the protrusions of 36% of the embryos. Finally, we have established how these protrusions were constructed from SEM observations of operated embryos cultured for 6 h and 10 h. 相似文献