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61.
Receptor tyrosine kinases (RTKs) are key components of cell–cell signalling required for growth and development of multicellular
organisms. It is therefore likely that the divergence of RTKs and associated components played a significant role in the evolution
of multicellular organisms. We have carried out the present study in hydra, a diploblast, to investigate the divergence of
RTKs after parazoa and before emergence of triploblast phyla. The domain-based screening using Hidden Markov Models (HMMs)
for RTKs in Genomescan predicted gene models of the Hydra magnipapillata genome resulted in identification of 15 RTKs. These RTKs have been classified into eight families based on domain architecture
and homology. Only 5 of these RTKs have been previously reported and a few of these have been partially characterized. A phylogeny-based
analysis of these predicted RTKs revealed that seven subtype duplications occurred between ‘parazoan–eumetazoan split’ and
‘diploblast–triploblast split’ in animal phyla. These results suggest that most of the RTKs evolved before the radiata–bilateria
divergence during animal evolution. 相似文献
62.
Although gossip serves several important social functions, it has relatively infrequently been the topic of systematic investigation. In two experiments, we advance a cognitive-informational approach to gossip. Specifically, we sought to determine which informational components engender gossip. In Experiment 1, participants read brief passages about other people and indicated their likelihood to share this information. We manipulated target familiarity (celebrity, non-celebrity) and story interest (interesting, boring). While participants were more likely to gossip about celebrity than non-celebrity targets and interesting than boring stories, they were even more likely to gossip about celebrity targets embedded within interesting stories. In Experiment 2, we additionally probed participants'' reactions to the stories concerning emotion, expectation, and reputation information conveyed. Analyses showed that while such information partially mediated target familiarity and story interest effects, only expectation and reputation accounted for the interactive pattern of gossip behavior. Our findings provide novel insights into the essential components and processing mechanisms of gossip. 相似文献
63.
64.
De Rooy DP Willemze A Mertens B Huizinga TW Van der Helm-van Mil AH 《Arthritis research & therapy》2011,13(5):R180
Introduction
Studies investigating genetic risk factors for susceptibility to rheumatoid arthritis (RA) studied anti-citrullinated peptide antibody (CCP)-positive RA more frequently than anti-CCP-negative RA. One of the reasons for this is the perception that anti-CCP-negative RA may include patients that fulfilled criteria for RA but belong to a wide range of diagnoses. We aimed to evaluate the validity of this notion and explored whether clinical subphenotypes can be discerned within anti-CCP-negative RA. 相似文献65.
66.
67.
Paul C. Sereno 《Cladistics : the international journal of the Willi Hennig Society》2009,25(6):624-659
Current strategies to compare or synthesize morphology-based cladistic hypotheses do not empower individual cladists to (i) understand the origin, authorship, or structure of character data, (ii) efficiently locate and collate previously published character data, or (iii) effectively compare character data from competing cladistic hypotheses. This paper outlines the requisite terminology, methods and indices to effectively compile and compare morphological character data between competing cladistic hypotheses and to isolate and measure the most important factors behind differing cladistic results—character selection and character-state scoring. When the procedures outlined here are facilitated by appropriate software, morphology-based cladistics may overcome long-recognized limitations in data comparison and synthesis. 相似文献
68.
LSB Mellau RJ Jørgensen PC Bartlett JMD Enemark AK Hansen 《Acta veterinaria Scandinavica》2004,45(3):139
The objective of this experiment was to determine the effect of dietary grain on calcium homeostasis. Six rumen-fistulated dairy cows with 3 or more previous lactations and no history of parturient paresis were randomly assigned to a sequence of diets in a crossover study with 4 periods of 10 days each. Dietary treatments were: A control ration consisting of wrap grass silage alone (1), the control ration supplemented with ammonium chloride and ammonium sulphate salt solution (2), control ration following a period with supplementation (3) and control ration supplemented with increasing amounts of barley from 4 to 10 kg/cow per day, expected to produce subclinical rumen acidosis (4). Daily intake of the diets was adjusted to 14 kg DM/cow per day. On day 11, the calcium-regulating mechanisms in cows were challenged until recumbency by a standardized intravenous EDTA infusion and cows were left to recover spontaneously. Anion supplementation and the feeding of highly fermentable carbohydrate lowered urine pH below 7.0 due to subclinical acidosis. During spontaneous recovery from EDTA induced hypocalcaemia, the cows more quickly regained a whole blood free calcium concentration of 1.00 mmol/L if they had most recently been supplemented with either anionic salts or with increasing amounts of barley, as compared to the basic ration. It is concluded that so-called slug-feeding or 'steaming up' with highly fermentable carbohydrates before parturition in milk fever susceptible cows enhanced calcium homeostasis similar to the effect seen in cows on anionic diets. 相似文献
69.
Sereno PC 《Systematic biology》1999,48(2):329-351
A general rationale for the formulation and placement of taxonomic definitions in phylogenetic taxonomy is proposed, and commonly used terms such as "crown taxon" or "node-based definition" are more precisely defined. In the formulation of phylogenetic definitions, nested reference taxa stabilize taxonomic content. A definitional configuration termed a node-stem triplet also stabilizes the relationship between the trio of taxa at a branchpoint, in the face of local change in phylogenetic relationships or addition/deletion of taxa. Crown-total taxonomies use survivorship as a criterion for placement of node-stem triplets within a taxonomic hierarchy. Diversity, morphology, and tradition also constitute heuristic criteria for placement of node-stem triplets. 相似文献
70.
Three-dimensional shape representation in monkey cortex 总被引:7,自引:0,他引:7
Using fMRI in anesthetized monkeys, this study investigates how the primate visual system constructs representations of three-dimensional (3D) shape from a variety of cues. Computer-generated 3D objects defined by shading, random dots, texture elements, or silhouettes were presented either statically or dynamically (rotating). Results suggest that 3D shape representations are highly localized, although widely distributed, in occipital, temporal, parietal, and frontal cortices and may involve common brain regions regardless of shape cue. This distributed network of areas cuts across both "what" and "where" processing streams, reflecting multiple uses for 3D shape representation in perception, recognition, and action. 相似文献