969 resultados para Lineage Specification


Relevância:

20.00% 20.00%

Publicador:

Resumo:

This paper tells about the recognition of temporal expressions and the resolution of their temporal reference. A proposal of the units we have used to face up this tasks over a restricted domain is shown. We work with newspapers' articles in Spanish, that is why every reference we use is in Spanish. For the identification and recognition of temporal expressions we base on a temporal expression grammar and for the resolution on a dictionary, where we have the information necessary to do the date operation based on the recognized expressions. In the evaluation of our proposal we have obtained successful results for the examples studied.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

We have studied the effect of inactivated microbial stimuli (Candida albicans, Candida glabrata, Saccharomyces boulardii, and Staphylococcus aureus) on the in vitro differentiation of lineage negative (Lin−) hematopoietic progenitor mouse cells. Purified Lin− progenitors were co-cultured for 7 days with the stimuli, and cell differentiation was determined by flow cytometry analysis. All the stimuli assayed caused differentiation toward the myeloid lineage. S. boulardii and particularly C. glabrata were the stimuli that induced in a minor extent differentiation of Lin− cells, as the major population of differentiated cells corresponded to monocytes, whereas C. albicans and S. aureus induced differentiation beyond monocytes: to monocyte-derived dendritic cells and macrophages, respectively. Interestingly, signaling through TLR2 by its pure ligand Pam3CSK4 directed differentiation of Lin− cells almost exclusively to macrophages. These data support the notion that hematopoiesis can be modulated in response to microbial stimuli in a pathogen-dependent manner, being determined by the pathogen-associated molecular patterns and the pattern-recognition receptors involved, in order to generate the populations of mature cells required to deal with the pathogen.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

All living organisms require accurate mechanisms to faithfully inherit their genetic material during cell division. The centromere is a unique locus on each chromosome that supports a multiprotein structure called the kinetochore. During mitosis, the kinetochore is responsible for connecting chromosomes to spindle microtubules, allowing faithful segregation of the duplicated genome. In most organisms, centromere position and function is not defined by the local DNA sequence context but rather by an epigenetic chromatin-based mechanism. Centromere protein A (CENP-A) is central to this process, as chromatin assembled from this histone H3 variant is essential for assembly of the centromere complex, as well as for its epigenetic maintenance. As a major determinant of centromere function, CENP-A assembly requires tight control, both in its specificity for the centromere and in timing of assembly. In the last few years, there have been several new insights into the molecular mechanism that allow this process to occur. We will review these here and discuss the general implications of the mechanism of cell cycle coupling of centromere inheritance.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The basic determinant of chromosome inheritance, the centromere, is specified in many eukaryotes by an epigenetic mark. Using gene targeting in human cells and fission yeast, chromatin containing the centromere-specific histone H3 variant CENP-A is demonstrated to be the epigenetic mark that acts through a two-step mechanism to identify, maintain and propagate centromere function indefinitely. Initially, centromere position is replicated and maintained by chromatin assembled with the centromere-targeting domain (CATD) of CENP-A substituted into H3. Subsequently, nucleation of kinetochore assembly onto CATD-containing chromatin is shown to require either the amino- or carboxy-terminal tail of CENP-A for recruitment of inner kinetochore proteins, including stabilizing CENP-B binding to human centromeres or direct recruitment of CENP-C, respectively.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Hox genes are essential for the patterning of the axial skeleton. Hox group 10 has been shown to specify the lumbar domain by setting a rib-inhibiting program in the presomitic mesoderm (PSM). We have now produced mice with ribs in every vertebra by ectopically expressing Hox group 6 in the PSM, indicating that Hox genes are also able to specify the thoracic domain. We show that the information provided by Hox genes to specify rib-containing and rib-less areas is first interpreted in the myotome through the regional-specific control of Myf5 and Myf6 expression. This information is then transmitted to the sclerotome by a system that includes FGF and PDGF signaling to produce vertebrae with or without ribs at different axial levels. Our findings offer a new perspective of how Hox genes produce global patterns in the axial skeleton and support a redundant nonmyogenic role of Myf5 and Myf6 in rib formation.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Phylo-zonations (or lineage-zonations) are based upon morphological changes within individual evolutionary lineages. These zonations, although potentially of use for stratigraphic subdivision and correlation, often suffer from a lack of quantitative exactness in the definitions of chronospecies. Thus exact reproducibility is hindered for stratigraphic determinations. The potential of morphometrically defined phylo-zonations is demonstrated on a temperate South Pacific Late Cenozoic lineage of planktonic foraminifera (Globorotalia conoidea through intermediate forms to Globorotalia inflata in DSDP Site 284) exhibiting phyletic gradualism. Our sampling interval is about 0.1 m.y. during the last 8 m.y. Changes in the number of chambers in the final whorl, test conicalness, percentage of keeled forms, and test roundness or inflatedness, are used to quantitatively define the following five chronospecies: G. conoidea (Late Miocene; 6.1->8.3 m.y.), G. conomiozea (latest Miocene ; 5.3-6.1 m.y.), G. puncticulata sphericomiozea (earliest Pliocene; 4.5-5.3 m.y.), G. puncticulata puncticulata (Early-Middle Pliocene; 2.9-4.5 m.y.), and G. inflata (Late Pliocene-Quaternary; 0-2.9 m.y.). This phylo-zonation is directly applicable to temperate cool subtropical Southern Hemisphere areas where the evolution took place (Kennett, 1967, 1973; Scott, 1979). It is still not known if the lineage occurs elsewhere; thus the applicability of the phylo-zonation over broader areas is still uncertain. Trends in general size and aperture shape seem to be climatically controlled, and thus may be only of local stratigraphic utility. The practical applications of morphometric phylo-zonation for stratigraphy is to a large extent dependent upon the amount of time and effort required to statistically define the trends. Experiments with large numbers of subsamples from this lineage demonstrate that accurate stratigraphic determinations are possible from measurements on only 15 specimens per sample, except for those very close to chronospecies boundaries.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Morphological evolution in the late Neogene planktonic foraminifer Sphaeroidinella lineage involves a sudden increase of the percentage of specimens equipped with supplementary apertures (from <30% to >70%) in the mid-Pliocene (about 3.5 Ma). This evolutionary transition, marked by the first occurrence of specimens with large supplementary apertures in the lineage, is denoted the Sphaeroidinella event. Changes in the proportions of the supplementary apertures in the lineage were studied in 24 samples from ODP Hole 926A drilled in the equatorial Atlantic Ocean. In addition, detailed chronological models have been compiled for this section as well as for Pliocene sections from DSDP Holes 214, 502A, and 503B, where evolution in the lineage have been analyzed previously. Stratigraphic correlation of the studied sequences suggests that the Sphaeroidinella event took place at about 3.6 Ma in the eastern equatorial Pacific (Hole 503B) and at 3.5-3.6 Ma in the Caribbean (Hole 502A), while in the Atlantic Ocean (Hole 926A) and in the Indian Ocean (Hole 214) the event occurred after 3.5 Ma. The inferred diachrony of the mid-Pliocene Sphaeroidinella transition, which is considered to represent a prime example of punctuated anagenesis, suggests that this evolutionary modality may have an allopatric component. Its short duration (on average less than 50 kyr) and the detailed biochronology that could be established for this event qualifies it as a useful biostratigraphic tool in the low-latitude Pliocene oceans.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Federal Highway Administration, Structures and Applied Mechanics Division, Washington, D.C.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Transportation Systems Center, Cambridge, Mass.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

National Highway Traffic Safety Administration, Washington, D.C.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Vita.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

1st edition issued with title : Recommended specifications for ...