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Many animal lineages exhibit allometry in sexual size dimorphism (SSD), known as ‘Rensch’s rule’. When applied to the interspecific level, this rule states that males are more evolutionary plastic in body size than females and that male‐biased SSD increases with body size. One of the explanations for the occurrence of Rensch’s rule is the differential‐plasticity hypothesis assuming that higher evolutionary plasticity in males is a consequence of larger sensitivity of male growth to environmental cues. We have confirmed the pattern consistent with Rensch’s rule among species of the gecko genus Paroedura and followed the ontogeny of SSD at three constant temperatures in a male‐larger species (Paroedura picta). In this species, males exhibited larger temperature‐induced phenotypic plasticity in final body size than females, and body size and SSD correlated across temperatures. This result supports the differential‐plasticity hypothesis and points to the role phenotypic plasticity plays in generating of evolutionary novelties. 相似文献
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Ján Lí?KA Július BRTKO Michal DUBOVICKY Dana MACEJOVá Viktória KISSOVá ?tefan POLáK Eduard UJHáZY 《Experimental Animals》2016,65(1):1-9
The mammary gland is a dynamic organ that undergoes structural and functional changesassociated with growth, reproduction, and post-menopausal regression. The postnataltransformations of the epithelium and stromal cells of the mammary gland may contribute toits susceptibility to carcinogenesis. The increased cancer incidence in mammary glands ofhumans and similarly of rodents in association with their development is believed to bepartly explained by proliferative activity together with lesser degree of differentiation,but it is not completely understood how the virgin gland retains its higher susceptibilityto carcinogenesis. During its developmental cycle, the mammary gland displays many of theproperties associated with breast cancer. An early first full-term pregnancy may have aprotective effect. Rodent models are useful for investigating potential breastcarcinogens. The purpose of this review is to help recognizing histological appearance ofthe epithelium and the stroma of the normal mammary gland in rats, and throughout itsdevelopment in relation to tumorigenic potential. 相似文献
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Arne B Gjuvsland Enikö Zörgö Jeevan KA Samy Simon Stenberg Ibrahim H Demirsoy Francisco Roque Ewa Maciaszczyk‐Dziubinska Magdalena Migocka Elisa Alonso‐Perez Martin Zackrisson Robert Wysocki Markus J Tamás Inge Jonassen Stig W Omholt Jonas Warringer 《Molecular systems biology》2016,12(12)
A major rationale for the advocacy of epigenetically mediated adaptive responses is that they facilitate faster adaptation to environmental challenges. This motivated us to develop a theoretical–experimental framework for disclosing the presence of such adaptation‐speeding mechanisms in an experimental evolution setting circumventing the need for pursuing costly mutation–accumulation experiments. To this end, we exposed clonal populations of budding yeast to a whole range of stressors. By growth phenotyping, we found that almost complete adaptation to arsenic emerged after a few mitotic cell divisions without involving any phenotypic plasticity. Causative mutations were identified by deep sequencing of the arsenic‐adapted populations and reconstructed for validation. Mutation effects on growth phenotypes, and the associated mutational target sizes were quantified and embedded in data‐driven individual‐based evolutionary population models. We found that the experimentally observed homogeneity of adaptation speed and heterogeneity of molecular solutions could only be accounted for if the mutation rate had been near estimates of the basal mutation rate. The ultrafast adaptation could be fully explained by extensive positive pleiotropy such that all beneficial mutations dramatically enhanced multiple fitness components in concert. As our approach can be exploited across a range of model organisms exposed to a variety of environmental challenges, it may be used for determining the importance of epigenetic adaptation‐speeding mechanisms in general. 相似文献
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Recent progress in bioinformatics research has led to the accumulation of huge quantities of biological data at various data sources.
The DNA microarray technology makes it possible to simultaneously analyze large number of genes across different samples.
Clustering of microarray data can reveal the hidden gene expression patterns from large quantities of expression data that in turn
offers tremendous possibilities in functional genomics, comparative genomics, disease diagnosis and drug development. The k-
¬means clustering algorithm is widely used for many practical applications. But the original k-¬means algorithm has several
drawbacks. It is computationally expensive and generates locally optimal solutions based on the random choice of the initial
centroids. Several methods have been proposed in the literature for improving the performance of the k-¬means algorithm. A
meta-heuristic optimization algorithm named harmony search helps find out near-global optimal solutions by searching the entire
solution space. Low clustering accuracy of the existing algorithms limits their use in many crucial applications of life sciences. In
this paper we propose a novel Harmony Search-K means Hybrid (HSKH) algorithm for clustering the gene expression data.
Experimental results show that the proposed algorithm produces clusters with better accuracy in comparison with the existing
algorithms. 相似文献
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Losses due to postharvest decay may occur at any time during postharvest handling, from harvest to consumption affecting the produce quality and quantity. Accurate identification of the pathogen causing postharvest disease is essential to the selection of an appropriate disease control approach. Nine isolates of Fusarium recovered from orange fruit were identified as Fusarium solani. The fungus is involved with fruit decay. The obtained cultures were purified and grown on potato-dextrose agar (PDA), malt yeast agar (MYA), and Czapek's nutrient media (CNM) under light for identification. A pathogenicity test was carried out to fulfil Koch's postulates. The pathogen could only enter ripe orange fruit through wounds and cracks causing the rot disease. The identification of the fungal isolates was confirmed to be F. solani by DNA sequencing, which was 99 to 100% homologous to those deposited in the Gen- Bank. The identity of nine fungal isolates was confirmed to be F. solani by DNA sequencing of the internal transcribed spacer (ITS) rDNA region (GenBank Accession Nos. DQ486874 to DQ486881 and KC758879). To our knowledge, this is the first morphogenetic identification of F. solani isolated from orange fruit in Egypt. 相似文献