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81.
ISOLDA LUNA‐VEGA J. DANIEL TEJERO‐DÍEZ RAÚL CONTRERAS‐MEDINA MICHAEL HEADS GERARDO RIVAS 《Biological journal of the Linnean Society. Linnean Society of London》2012,106(4):940-955
We analyzed the geographical and elevational distributions of two Polypodium complexes from Mexico and Central America. Distribution data of nine species of the Polypodium colpodes complex and the Polypodium plesiosorum complex were obtained from almost 1500 herbarium specimens, field collections in Mexico and Costa Rica, and literature studies. The presence of each species was recorded for each Mesoamerican country, in 1° × 1° grid‐cells and biogeographical provinces. The rarity of species was also evaluated. Although the two complexes show extensive overlap, the P. colpodes complex is distributed mainly along the Pacific versant of Mexico and Central America, whereas the P. plesiosorum complex occurs mainly along the Atlantic versant. Those biogeographical provinces with maximum species diversity are Chiapas (seven species), Sierra Madre del Sur (six species), and the Trans‐Mexican Volcanic belt (six species). Grid‐cells with more species are located mainly in the mountains of central‐southern Mexico and northern Central America. Richness does not decrease or increase with latitude. Elevation distributions showed that most Polypodium species are concentrated in the montane interval and three species groups were recognized based on elevational preferences. Polypodium colpodes and P. plesiosorum are the most widely distributed species, whereas Polypodium castaneum and Polypodium flagellare are the only two species that possess the three attributes of rarity (narrow geographical distribution, high habitat specificity, and scarce local populations). Polypodium species of both complexes are present mainly in the montane regions of the study area and show some degree of geographical sympatry, especially in southern Mexico and northern Central America. This overlapping is explained by the elevation tolerance within montane systems and because most species inhabit three or more vegetation types. The distributional patterns of these complexes coincided with the three regional highlands of Mesoamerica, which are separated from each other by the Isthmus of Tehuantepec and by the lowlands of Nicaragua. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ?? , ??–??. 相似文献
82.
83.
Talbot M. Andrews Aaron W. Lukaszewski Zachary L. Simmons April Bleske-Rechek 《Evolution and human behavior》2017,38(4):461-467
Women's body attractiveness is influenced by specific anthropometric cues, including body mass index (BMI), waist-to-hip ratio (WHR), waist-to-stature ratio (WSR), and shoulder-to-waist ratio (SWR). Despite the existence of multiple functional hypotheses to explain these preferences, it remains unclear which cue-based inferences are most influential in regulating evaluations of women's body attractiveness. We argue that (i) the common link to the morphological cues that influence women's body attractiveness is that they all reliably indicate high reproductive value (as defined by youth and low parity); and (ii) ancestrally, selection pressures related to tracking between-women differences in reproductive value would have been among the strongest acting on adaptations for body evaluation. An empirical study then tested the resulting prediction that cue-based estimates of reproductive value function as powerful regulators of women's body attractiveness judgments. Subjects viewed standardized photos of women in swimsuits (with heads obscured), and were assigned to either estimate components of their reproductive value (age or number of offspring) or rate their attractiveness. Structural equation modeling revealed that a latent variable capturing estimated reproductive value was almost perfectly correlated with a latent variable capturing body attractiveness. Moreover, unique associations of women's BMI, WHR, and WSR with their body attractiveness were entirely mediated via estimated reproductive value. These findings provide strong support for the longstanding hypothesis that women's body attractiveness is primarily explained by cue-based estimates of reproductive value – expected future utility as a vehicle of offspring production. 相似文献
84.
Univalent chromosomes at meiotic metaphase I have a tendency to misdivide at the centromeres. Fusion of the misdivision products may produce Robertsonian translocations. The fine structure of the centromeres in Robertsonian wheat-rye translocation chromosomes was analyzed by fluorescence in situ hybridization (FISH) using two centromere-specific DNA clones: pRCS1, derived from rice, and pAWRC1, derived from rye. Clone pRCS1 hybridizes to the centromeres of all grasses including wheat and rye, whereas clone pAWRC1 is rye specific and hybridizes only to the centromeres of rye. Four of the six wheat-rye translocations derived from a single centric misdivision event (1st generation translocations) had hybrid centromeres, with approximately half of the centromere derived from rye and half from wheat. In the two other 1st generation translocations, the entire centromere was derived from rye. Among eight reconstructed wheat and rye chromosomes that originated from two consecutive centric misdivision-fusion events (2nd generation translocations), T1BS.1BL (derived from T1BS.1RL and T1RS.1BL) and one of three T2BS.2BL (derived from T2RS.2BL and T2BS.2RL) had hybrid centromeres. T1RS.1RL (derived from T1BS.1RL and T1RS.1BL), two of three T2BS.2BL, and all three T2RS.2RL (derived from T2RS.2BL and T2BS.2RL) had rye centromeres. All three 3rd generation translocations had hybrid centromeres with approximately half of the centromere derived from rye. There were no indications that the composite structure of the centromere in these chromosomes affected their behavior in mitosis or meiosis. These observations support the notion of a compound structure of the centromere in higher organisms, and indicate that during the centric breakage-fusion event, centromere breakage may occur in different positions along the segment of the chromosome that interacts with the spindle fibers. Normal behavior of the 1st, 2nd, and 3rd generation centric translocations in mitosis and meiosis indicates that, at least in wheat and rye, centromeres are not chromosome specific. 相似文献
85.
Pegylated alpha interferon is an effective treatment for virulent venezuelan equine encephalitis virus and has profound effects on the host immune response to infection 下载免费PDF全文
Venezuelan equine encephalitis virus (VEEV) is a highly infectious alphavirus endemic in parts of Central and South America. The disease is transmitted by mosquitoes, and the natural reservoir is the small rodent population, with epidemics occurring in horses and occasionally humans. Following infection, VEEV replicates in lymphoid tissues prior to invasion of the central nervous system. Treatment of VEEV-infected BALB/c mice with polyethylene glycol-conjugated alpha interferon (PEG IFN-alpha) results in a greatly enhanced survival from either a subcutaneous or an aerosol infection. Virus is undetectable within PEG IFN-alpha-treated individuals by day 30 postinfection (p.i.). Treatment results in a number of changes to the immune response characteristics normally associated with VEEV infection. Increased macrophage activation occurs in PEG IFN-alpha-treated BALB/c mice infected with VEEV. The rapid activation of splenic CD4, CD8, and B cells by day 2 p.i. normally associated with VEEV infection is absent in PEG IFN-alpha-treated mice. The high tumor necrosis factor alpha production by macrophages from untreated mice is greatly diminished in PEG IFN-alpha-treated mice. These results suggest key immunological mechanisms targeted by this lethal alphavirus that can be modulated by prolonged exposure to IFN-alpha. 相似文献
86.
It is well-established that males of many nonhuman vertebrate species exhibit hormonal reactions to stimuli from potential mates. The present studies were designed to test replication of preliminary findings suggesting that human males may exhibit such reactions as well. In Experiment 1, young men (n=115) provided saliva samples before and after either conversing with a woman confederate or sitting alone for 15 min. Changes from baseline in salivary testosterone concentrations were significantly greater among the men exposed to women, but only among subjects tested in the afternoon. In Experiment 2, male subjects (n=99) interacted with either a male or a female confederate with saliva samples collected before and after these interactions and all experimental sessions conducted in the afternoon. Men who interacted with women exhibited significant elevations of testosterone relative to both their own baseline concentrations and to change scores among the men who interacted with other men. In addition, women confederates' ratings of men's extraversion and degree of self-disclosure were positively correlated with changes in testosterone. In both experiments, furthermore, changes in cortisol concentrations from baseline were significantly greater among men who spoke with women relative to men in the control conditions. The results provide evidence that social interactions with potential mates can in fact trigger specific patterns of endocrine responses in human males. 相似文献
87.
Olga Obrezanova Andreas Arnell Ramón Gómez de la Cuesta Maud E Berthelot Thomas RA Gallagher Jesús Zurdo Yvette Stallwood 《MABS-AUSTIN》2015,7(2):352-363
Aggregation is a common problem affecting biopharmaceutical development that can have a significant effect on the quality of the product, as well as the safety to patients, particularly because of the increased risk of immune reactions. Here, we describe a new high-throughput screening algorithm developed to classify antibody molecules based on their propensity to aggregate. The tool, constructed and validated on experimental aggregation data for over 500 antibodies, is able to discern molecules with a high aggregation propensity as defined by experimental criteria relevant to bioprocessing and manufacturing of these molecules. Furthermore, we show how this tool can be combined with other computational approaches during early drug development to select molecules with reduced risk of aggregation and optimal developability properties. 相似文献
88.
Protein phosphatase 2A (PP2A) is a heterotrimeric complex comprising a catalytic, scaffolding, and regulatory subunit. The regulatory subunits are essential for substrate specificity and localization of the complex and are classified into B/B55, B'', and B” non-related families in higher plants. In Arabidopsis thaliana, the close paralogs B''η, B''θ, B''γ, and B''ζ were further classified into a subfamily of B'' called B''η. Here we present results that consolidate the evidence for a role of the B''η subfamily in regulation of innate immunity, energy metabolism and flowering time. Proliferation of the virulent Pseudomonas syringae in B''θ knockout mutant decreased in comparison with wild type plants. Additionally, B''θ knockout plants were delayed in flowering, and this phenotype was supported by high expression of FLC (FLOWERING LOCUS C). B''ζ knockout seedlings showed growth retardation on sucrose-free medium, indicating a role for B''ζ in energy metabolism. This work provides insight into functions of the B''η subfamily members, highlighting their regulation of shared physiological traits while localizing to distinct cellular compartments. 相似文献
89.
A systematic comparative and structural analysis of protein phosphorylation sites based on the mtcPTM database 下载免费PDF全文
mtcPTM is an online repository of human and mouse phosphosites in which data are hierarchically organized to preserve biologically
relevant experimental information, thus allowing straightforward comparisons of phosphorylation patterns found under different
conditions. The database also contains the largest available collection of atomic models of phosphorylatable proteins. Detailed
analysis of this structural dataset reveals that phosphorylation sites are found in a heterogeneous range of structural and
sequence contexts. mtcPTM is available on the web . 相似文献
90.
Phylogenetic analyses of the rbcL sequences from haptophytes and heterokont algae suggest their chloroplasts are unrelated 总被引:2,自引:0,他引:2
Using the large subunit of RuBisCo (rbcL) sequences from cyanobacteria,
proteobacteria, and diverse groups of algae and green plants, we evaluated
the plastid relationship between haptophytes and heterokont algae. The rbcL
sequences were determined from three taxa of heterokont algae
(Bumilleriopsis filiformis, Pelagomonas calceolata, and Pseudopedinella
elastica) and added to 25 published sequences to obtain a data set
comprising 1,434 unambiguously aligned sites (approximately 98% of the
total rbcL gene). Higher levels of mutational saturation in third codon
positions were observed by plotting the pairwise substitutions with and
without corrections for multiple substitutions at the same site for first
and second codon positions only and for third positions only. In accordance
with this finding phylogeny reconstructions were completed by omitting
third codon positions, thus using 956 bp in weighted-parsimony and
maximum-likelihood analyses. The midpoint-rooted phylogenies showed two
major clusters, one containing cyanobacteria, glaucocystophytes, a
phototrophic euglenoid, chlorophytes, and embryophytes (the green lineage),
the other containing proteobacteria, haptophytes, red algae, a cryptophyte,
and heterokont algae (the non-green lineage). In the nongreen lineage, the
haptophytes formed a sister group to the clade containing heterokont algae,
red algae, and the cryptophyte Guillardia theta. This branching pattern was
well supported in terms of bootstrap values in weighted- parsimony and
maximum-likelihood analyses (100% and 92%, respectively). However, the
phylogenetic relationship among red algae, heterokonts, and a cryptophyte
taxon was not especially well resolved. A four- cluster analysis was
performed to further explore the statistical significance of the
relationship between proteobacteria, red algae (including and excluding
Guillardia theta), haptophytes, and heterokont algae. This test strongly
favored the hypothesis that the heterokonts and red algae are more closely
related to each other than either is to proteobacteria or haptophytes.
Hence, this molecular study based on a plastid-encoded gene provides
additional evidence for a distant relationship between haptophytes and the
heterokont algae. It suggests an evolutionary scenario in which the
ancestor of the haptophyte lineage engulfed a phototrophic eukaryote and,
more recently, the heterokont lineage became phototrophic by engulfing a
red alga.
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