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371.
The structures of two new constituents, a beta-glycoside (1) and a steroid (2), isolated from the twigs and thorns of Castela polyandra, were established by a combination of spectroscopic and single-crystal X-ray analysis. 相似文献
372.
During herpes simplex virus 1 (HSV-1) infection, empty procapsids are assembled and subsequently filled with the viral genome by means of a protein complex called the terminase, which is comprised of the HSV-1 UL15, UL28, and UL33 proteins. Biochemical studies of the terminase proteins have been hampered by the inability to purify the intact terminase complex. In this study, terminase complexes were isolated by tandem-affinity purification (TAP) using recombinant viruses expressing either a full-length NTAP-UL28 fusion protein (vFH476) or a C-terminally truncated NTAP-UL28 fusion protein (vFH499). TAP of the UL28 protein from vFH476-infected cells, followed by silver staining, Western blotting, and mass spectrometry, identified the UL15, UL28, and UL33 subunits, while TAP of vFH499-infected cells confirmed previous findings that the C terminus of UL28 is required for UL28 interaction with UL33 and UL15. Analysis of the oligomeric state of the purified complexes by sucrose density gradient ultracentrifugation revealed that the three proteins formed a complex with a molecular mass that is consistent with the formation of a UL15-UL28-UL33 heterotrimer. In order to assess the importance of conserved regions of the UL15 and UL28 proteins, recombinant NTAP-UL28 viruses with mutations of the putative UL28 metal-binding domain or within the UL15 nuclease domain were generated. TAP of UL28 complexes from cells infected with each domain mutant demonstrated that the conserved cysteine residues of the putative UL28 metal-binding domain and conserved amino acids within the UL15 nuclease domain are required for the cleavage and packaging functions of the viral terminase, but not for terminase complex assembly. 相似文献
373.
The sequences of the linked alpha 2- and alpha 1-globin genes of the equine
BI and BII haplotypes are greater than 99% identical within a 1.2-kb region
extending from approximately 75 bp upstream of the putative cap site to a
point approximately 150 bp 3' to the poly A addition signal. Differences
between the alpha 2 and alpha 1 genes that are common to both haplotypes
indicate that a major gene conversion occurred approximately 12 Myr ago and
that this has been followed by shorter, more localized, conversions.
Interhaplotype (allelic) comparisons at the alpha loci suggest that the BI
and BII haplotypes have probably existed independently greater than or
equal to 0.5 Myr and that the alpha 1 genes may have undergone a recent
interchromosomal gene conversion.
相似文献
374.
Stone-play, a newly innovated cultural behavior, has been observed among the free-ranging Arashiyama B troop Japanese macaques
near Kyoto, Japan since 1979. Conditions in which the non-purposeful handling of stones might possibly give rise to tool behavior
are discussed. The progression of this behavior is traced through three phases: transmission, tradition, and transformation.
During the first two phases, through social learning, the behavior was established within the group as a regular item of their
behavioral repertoire and was most frequently observed after eating provisioned grain. In the third phase, observations suggest
a “faddish” shift in the practice of certain behavioral sub-types between 1984 and 1985. During this period young individuals
increasingly began to carry stones away from the feeding station, mixing stone manipulation with forage-feeding activities
in the forest. Observations suggest under such conditions, stone handling is likely to lead to the occasional use of stone
as a tool. This conclusion probably can be applied to species other thanMacaca fuscata. Consideration of the eco-setting and social learning correlates of stone handling suggests how the instrumental use of stone
might emerge from a tradition of non-instrumental manipulation. 相似文献
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380.
Functional sensory and motor areas in the developing mammalian neocortex are formed through a complex interaction of cortically intrinsic mechanisms, such as gene expression, and cortically extrinsic mechanisms such as those mediated by thalamic input from the senses. Both intrinsic and extrinsic mechanisms are believed to be involved in cortical patterning and the establishment of areal boundaries in early development; however, the nature of the interaction between intrinsic and extrinsic processes is not well understood. In a previous study, we used a perinatal bilateral enucleation mouse model to test some aspects of this interaction by reweighting sensory input to the developing cortex. Visual deprivation at birth resulted in a shift of intraneocortical connections (INCs) that aligned with ectopic ephrin A5 expression in the same location ten days later at postnatal day (P) 10. A prevailing question remained: Does visual deprivation first induce a change in gene expression, followed by a shift in INCs, or vice versa? In the present study, we address this question by investigating the neuroanatomy and patterns of gene expression in post-natal day (P) 1 and 4 mice following bilateral enucleation at birth. Our results demonstrate a rapid reduction in dorsal lateral geniculate nucleus (dLGN) size and ephrin A5 gene expression 24-hours post-enucleation, with more profound effects apparent at P4. The reduced nuclear size and diminished gene expression mirrors subtle changes in ephrin A5 expression evident in P1 and P4 enucleated neocortex, 11 and 8 days prior to natural eye opening, respectively. Somatosensory and visual INCs were indistinguishable between P1 and P4 mice bilaterally enucleated at birth, indicating that perinatal bilateral enucleation initiates a rapid change in gene expression (within one day) followed by an alteration of sensory INCs later on (second postnatal week). With these results, we gain a deeper understanding of how gene expression and sensory input together regulate cortical arealization and plasticity during early development. 相似文献