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At least 811 records · Page 45Linked to original sources
PubMed2001

Powerful ideas driven by simple tools: lessons from experimental embryology.

In developmental biology, as in all scientific fields, conceptual advances are tightly coupled to technological innovation. In this review, we trace the evolution of techniques in experimental embryology, from classical ablation to the latest methods utilizing in vivo electroporation, with lens induction as a linking theme.

Animals↗
PubMed2005

Sequencing of Aspergillus nidulans and comparative analysis with A. fumigatus and A. oryzae.

The aspergilli comprise a diverse group of filamentous fungi spanning over 200 million years of evolution. Here we report the genome sequence of the model organism Aspergillus nidulans, and a comparative study with Aspergillus fumigatus, a serious human pathogen, and Aspergillus oryzae, used in the production of sake, miso and soy sauce. Our analysis of genome structure provided a quantitative evaluation of forces driving long-term eukaryotic genome evolution. It also led to an experimentally validated model of mating-type locus evolution, suggesting the potential for sexual reproduction in A. fumigatus and A. oryzae. Our analysis of sequence conservation revealed over 5,000 non-coding regions actively conserved across all three species. Within these regions, we identified potential functional elements including a previously uncharacterized TPP riboswitch and motifs suggesting regulation in filamentous fungi by Puf family genes. We further obtained comparative and experimental evidence indicating widespread translational regulation by upstream open reading frames. These results enhance our understanding of these widely studied fungi as well as provide new insight into eukaryotic genome evolution and gene regulation.

Aspergillus fumigatus↗
PubMed1998

Formation and evolution of scroll waves in photosensitive excitable media.

Experimental and computational studies of the formation and evolution of scroll waves in three-dimensional excitable media are presented. Scroll waves are initiated in the photosensitive Belousov-Zhabotinsky reaction by perturbing traveling waves transverse to their direction of propagation. Scroll rings are generated by perturbing circular waves, which expand or contract depending on the strength of an imposed excitability gradient and its direction relative to the rotational direction of the scroll wave. (c) 1998 American Institute of Physics.

Journal Article↗
PubMed2004

[Dynamic evolution of MMP-13, TIMP-1, type I and III collagen and their interaction in experimental liver fibrosis].

OBJECTIVE: To obtain a detailed pattern of the dynamic evolution and interactions among MMP-13, TIMP-1, type I and III collagen during experimental liver fibrosis. METHODS: Wistar rats were randomly allocated into a normal group, and a model group. To induce liver fibrosis, rats were intraperitoneally injected with dimethylnitrosamine (DMN) three consecutive times in the first week, then two consecutive times per week, totally for 6 weeks. In the normal control group, rats were treated with saline by the same means. Animals were sacrificed 1, 4, 10, 17, 28, 42, 56 days after starting DMN injections. Conventional histological examinations were performed after hematoxylin and eosin, and Masson stain. Fibrosis stages were classified into 0 to 4. Hydroxyproline contents were determined after liver tissues were hydrolyzed in HCl at 160 degrees C for 2 h and then measured with spectrometry at 560 nm wavelength. mRNA levels of MMP-13, TIMP-1, type I and III collagen were determined by semi-quantitive RT-PCR. RESULTS: In the model group, hepatic type I pro-collagen mRNA expression started to increase on the 10th day after DMN administration (t = 2.85, P < 0.05), type III started to increase on the 28th day (t = 4.16, P< 0.01), and TIMP-1 mRNA expression started to increase on the 4th day (t = 2.60, P < 0.05). They all remained much higher than in the normal group throughout the remaining study period. Hepatic MMP-13 mRNA expression started to increase on the 17th day after DMN administration and remained at a higher level than in the normal group until he 28th day (t = 4.08, P < 0.01), then gradually returned to normal level at the end of the study period. CONCLUSION: Although hepatic MMP-13 expression transiently increased during liver fibrosis, enhanced expression of TIMP-1 from the early periods of liver fibrosis inhibited the collagen degrading ability of MMP-13, therefore, over-expressed collagen accumulated in the liver. Thus, it is hypothesized that TIMPs play a pivotal role in liver fibrosis.

Animals↗