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11.
Interest in the use of low-copy nuclear genes for phylogenetic analyses of
plants has grown rapidly, because highly repetitive genes such as those
commonly used are limited in number. Furthermore, because low- copy genes
are subject to different evolutionary processes than are plastid genes or
highly repetitive nuclear markers, they provide a valuable source of
independent phylogenetic evidence. The gene for granule-bound starch
synthase (GBSSI or waxy) exists in a single copy in nearly all plants
examined so far. Our study of GBSSI had three parts: (1) Amino acid
sequences were compared across a broad taxonomic range, including grasses,
four dicotyledons, and the microbial homologs of GBSSI. Inferred structural
information was used to aid in the alignment of these very divergent
sequences. The informed alignments highlight amino acids that are conserved
across all sequences, and demonstrate that structural motifs can be highly
conserved in spite of marked divergence in amino acid sequence. (2)
Maximum-likelihood (ML) analyses were used to examine exon sequence
evolution throughout grasses. Differences in probabilities among
substitution types and marked among-site rate variation contributed to the
observed pattern of variation. Of the parameters examined in our set of
likelihood models, the inclusion of among-site rate variation following a
gamma distribution caused the greatest improvement in likelihood score. (3)
We performed cladistic parsimony analyses of GBSSI sequences throughout
grasses, within tribes, and within genera to examine the phylogenetic
utility of the gene. Introns provide useful information among very closely
related species, but quickly become difficult to align among more divergent
taxa. Exons are variable enough to provide extensive resolution within the
family, but with low bootstrap support. The combined results of amino acid
sequence comparisons, maximum-likelihood analyses, and phylogenetic studies
underscore factors that might affect phylogenetic reconstruction. In this
case, accommodation of the variable rate of evolution among sites might be
the first step in maximizing the phylogenetic utility of GBSSI.
相似文献
12.
Jodie Belilla Miguel Iniesto David Moreira Karim Benzerara José María López-García Ana I. López-Archilla Guillaume Reboul Philippe Deschamps Emmanuelle Gérard Purificación López-García 《Environmental microbiology》2021,23(11):7168-7182
The Dallol protovolcanic area on the Danakil Depression (Afar region, Ethiopia) exhibits unique hydrothermal manifestations in hypersaline context, yielding varied polyextreme physicochemical conditions. Previous studies identified a wide archaeal diversity in less extreme brines but failed to identify microorganisms thriving in either high-chaotropicity, low-water-activity brines or hyperacidic-hypersaline Na-Fe-rich brines. Recently, we accessed several small lakes under intense degassing activity adjacent to the Round Mountain, west to the Dallol dome [Western Canyon Lakes (WCL); WCL1-5]. They exhibited intermediate parameter combinations (pH ~ 5, 34%–41% (weight/volume) NaCl-dominated salts with relatively high levels of chaotropic Mg-Ca salts) that should allow to better constrain life limits. These lakes were overwhelmingly dominated by Archaea, encompassing up to 99% of prokaryotic 16S rRNA gene amplicon sequences in metabarcoding studies. The majority belonged to Halobacteriota and Nanohaloarchaeota, the latter representing up to half of prokaryotic sequences. Optical and epifluorescence microscopy showed active cells in natural samples and diverse morphotypes in enrichment cultures. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy revealed tiny cells (200–300 nm diameter) epibiotically associated with somewhat larger cells (0.6–1 μm) but also the presence of silica-dominated precipitates of similar size and shape, highlighting the difficulty of distinguishing microbes from mineral biomorphs in this kind of low-biomass systems. 相似文献
13.
14.
Kitagawa D Flückiger I Polanowska J Keller D Reboul J Gönczy P 《Developmental cell》2011,20(4):550-562
Highlights? PP2A phosphatase is essential for centriole formation in C. elegans ? PP2A subunits genetically and physically interact with the SAS-5/SAS-6 complex ? PP2A-mediated dephosphorylation of SAS-5 is required for SAS-5/SAS-6 centriolar targeting ? Human PP2A is required for HsSAS-6 centriolar targeting and centriole formation 相似文献
15.
16.
Hall GL Logie KM Parsons F Schulzke SM Nolan G Murray C Ranganathan S Robinson P Sly PD Stick SM;AREST CF Berry L Garratt L Massie J Mott L Poreddy S Simpson S 《PloS one》2011,6(8):e23932
Background
In school-aged children with cystic fibrosis (CF) structural lung damage assessed using chest CT is associated with abnormal ventilation distribution. The primary objective of this analysis was to determine the relationships between ventilation distribution outcomes and the presence and extent of structural damage as assessed by chest CT in infants and young children with CF.Methods
Data of infants and young children with CF diagnosed following newborn screening consecutively reviewed between August 2005 and December 2009 were analysed. Ventilation distribution (lung clearance index and the first and second moment ratios [LCI, M1/M0 and M2/M0, respectively]), chest CT and airway pathology from bronchoalveolar lavage were determined at diagnosis and then annually. The chest CT scans were evaluated for the presence or absence of bronchiectasis and air trapping.Results
Matched lung function, chest CT and pathology outcomes were available in 49 infants (31 male) with bronchiectasis and air trapping present in 13 (27%) and 24 (49%) infants, respectively. The presence of bronchiectasis or air trapping was associated with increased M2/M0 but not LCI or M1/M0. There was a weak, but statistically significant association between the extent of air trapping and all ventilation distribution outcomes.Conclusion
These findings suggest that in early CF lung disease there are weak associations between ventilation distribution and lung damage from chest CT. These finding are in contrast to those reported in older children. These findings suggest that assessments of LCI could not be used to replace a chest CT scan for the assessment of structural lung disease in the first two years of life. Further research in which both MBW and chest CT outcomes are obtained is required to assess the role of ventilation distribution in tracking the progression of lung damage in infants with CF. 相似文献17.
Background
If biology is modular then clusters, or communities, of proteins derived using only protein interaction network structure should define protein modules with similar biological roles. We investigate the link between biological modules and network communities in yeast and its relationship to the scale at which we probe the network. 相似文献18.
Roberto?H?Higa Roberto?C?Togawa Arnaldo?J?Montagner Juliana?CF?Palandrani Igor?KS?Okimoto Paula?R?Kuser Michel?EB?Yamagishi Adauto?L?Mancini Goran?NeshichEmail author 《BMC bioinformatics》2004,5(1):107
Background
The integration of many aspects of protein/DNA structure analysis is an important requirement for software products in general area of structural bioinformatics. In fact, there are too few software packages on the internet which can be described as successful in this respect. We might say that what is still missing is publicly available, web based software for interactive analysis of the sequence/structure/function of proteins and their complexes with DNA and ligands. Some of existing software packages do have certain level of integration and do offer analysis of several structure related parameters, however not to the extent generally demanded by a user. 相似文献19.
Jordi?Monfort Ginette?Tardif Pascal?Reboul Fran?ois?Mineau Peter?Roughley Jean-Pierre?Pelletier Johanne?Martel-PelletierEmail author 《Arthritis research & therapy》2005,8(1):R26
A major and early feature of cartilage degeneration is proteoglycan breakdown. Matrix metalloprotease (MMP)-13 plays an important
role in cartilage degradation in osteoarthritis (OA). This MMP, in addition to initiating collagen fibre cleavage, acts on
several proteoglycans. One of the proteoglycan families, termed small leucine-rich proteoglycans (SLRPs), was found to be
involved in collagen fibril formation/interaction, with some members playing a role in the OA process. We investigated the
ability of MMP-13 to cleave members of two classes of SLRPs: biglycan and decorin; and fibromodulin and lumican. SLRPs were
isolated from human normal and OA cartilage using guanidinium chloride (4 mol/l) extraction. Digestion products were examined
using Western blotting. The identities of the MMP-13 degradation products of biglycan and decorin (using specific substrates)
were determined following electrophoresis and microsequencing. We found that the SLRPs studied were cleaved to differing extents
by human MMP-13. Although only minimal cleavage of decorin and lumican was observed, cleavage of fibromodulin and biglycan
was extensive, suggesting that both molecules are preferential substrates. In contrast to biglycan, decorin and lumican, which
yielded a degradation pattern similar for both normal and OA cartilage, fibromodulin had a higher level of degradation with
increased cartilage damage. Microsequencing revealed a novel major cleavage site (... G177/V178) for biglycan and a potential cleavage site for decorin upon exposure to MMP-13. We showed, for the first time, that MMP-13
can degrade members from two classes of the SLRP family, and identified the site at which biglycan is cleaved by MMP-13. MMP-13
induced SLRP degradation may represent an early critical event, which may in turn affect the collagen network by exposing
the MMP-13 cleavage site in this macromolecule. Awareness of SLRP degradation products, especially those of biglycan and fibromodulin,
may assist in early detection of OA cartilage degradation. 相似文献
20.
Pelletier JP Boileau C Boily M Brunet J Mineau F Geng C Reboul P Laufer S Lajeunesse D Martel-Pelletier J 《Arthritis research & therapy》2005,7(5):R1091-R1102
This study sought to evaluate the levels of mRNA expression and protein synthesis of MMP-13, cathepsin K, aggrecanase-1 (ADAMTS-4),
aggrecanase-2 (ADAMTS-5) and 5-lipoxygenase (5-LOX) in cartilage in the experimental anterior cruciate ligament (ACL) dog
model of osteoarthritis (OA), and to examine the effects of treatment with licofelone, a 5-lipoxygenase (LOX)/cyclooxygenase
(COX) inhibitor, on the levels of these catabolic factors. Sectioning of the ACL of the right knee was performed in three
experimental groups: group 1 received no active treatment (placebo group); and groups 2 and 3 received therapeutic concentrations
of licofelone (2.5 or 5.0 mg/kg/day orally, respectively) for 8 weeks, beginning the day following surgery. A fourth group
consisted of untreated dogs that were used as normal controls. Specimens of cartilage were selected from lesional areas of
OA femoral condyles and tibial plateaus, and were processed for real-time quantitative PCR and immunohistochemical analyses.
The levels of MMP-13, cathepsin K, ADAMTS-4, ADAMTS-5 and 5-LOX were found to be significantly increased in OA cartilage.
Licofelone treatment decreased the levels of both mRNA expression and protein synthesis of the factors studied. Of note was
the marked reduction in the level of 5-LOX gene expression. The effects of the drug were about the same at both tested dosages.
In vivo treatment with therapeutic dosages of licofelone has been found to reduce the degradation of OA cartilage in experimental
OA. This, coupled with the results of the present study, indicates that the effects of licofelone are mediated by the inhibition
of the major cartilage catabolic pathways involved in the destruction of cartilage matrix macromolecules. Moreover, our findings
also indicate the possible auto-regulation of 5-LOX gene expression by licofelone in OA cartilage. 相似文献