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Digitale Medien

The importance of sampling scale in the assessment of intraspecific life-history differences in plains killifish, Fundulus zebrinus, populations (Pisces: Cyprinodontidae) (1990)

Schmeidler, Norbert J. ; Brown, Karen L.

Springer

Environmental biology of fishes 29 (1990), S. 263-275

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ISSN: 1573-5133

Schlagwort(e): Demography ; Genetics ; Geographic variation ; Stochasticity ; Fluctuating environments ; Allele frequencies ; River ecology

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Synopsis The purpose of this study was to determine the effects of unpredictable environmental fluctuations on the demographic and genetic structure of Fundulus zebrinus populations. Collections of F. zebrinus were taken from three rivers in the Arkansas River basin: the Arkansas, Chikaskia, and Ninnescah. Fish were sampled from three sites on each river on nine collection dates throughout 1984 and 1985. Totals of 2100 fish and 6000 fish were included in electrophoretic and demographic analyses, respectively. The results of the study indicate that within a limited geographic region (i.e. within rivers) spatial differences and temporal changes in both demographic and genetic population characteristics occur frequently and are primarily stochastic. However, on a larger spatial scale (i.e. across rivers), general trends emerge for demographic and especially for genetic population characteristics. These results illustrate the importance of sampling scale for conclusions of life-history evolution in fluctuating environments. In addition, it was found that regulation of Fundulus zebrinus populations includes an important density-independent component. Stochastic demographic differences across space and changes through time and spatially and temporally heterogeneous allele frequencies, are both indicative of density-independent regulation. Variation in population parameters, both demographic and genetic, was observed between populations sampled from each river. These population differences were attributed to differences between the rivers themselves.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00001184

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Digitale Medien

Regulation of expression of the growth-state-related genes 2F1 and 2A9 during entry of quiescent smooth muscle cells into the cell cycle (1991)

Kindy, Mark S. ; Brown, Karen E. ; Sonenshein, Gail E.

New York, N.Y. : Wiley-Blackwell

Journal of Cellular Biochemistry 46 (1991), S. 345-350

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ISSN: 0730-2312

Schlagwort(e): SMCs ; mRNA ; mitochondrial ADP/ATP carrier ; calcyclin ; cell cycle ; Life and Medical Sciences ; Cell & Developmental Biology

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Biologie , Chemie und Pharmazie , Medizin

Notizen: Vascular smooth muscle cells (SMCs) play a key role in the development of major arteries. Furthermore, abnormal growth of vascular smooth muscle cells has been implicated in the progression of major diseases of the cardiovascular system. Here, we report detection in primary cultures of bovine vascular smooth muscle cells of mRNA for two growth-state-related genes, 2F1 and 2A9, which code for a mitochondrial ADP/ATP carrier and calcyclin, respectively, and on the characterization of their cell cycle expression. Cultures of exponentially growing smooth muscle cells were made quiescent by serum deprivation. Upon readdition of serum, cells entered the cell cycle synchronously; DNA synthesis began 12 h post-serum addition. Levels of 2F1 and 2A9 RNA were low in quiescent cells and increased between 2 and 4 h post-serum addition. No changes in the rates of transcription of the 2F1 or 2A9 genes were detected by nuclear run-off assays during the time course. Thus the regulation of changes in expression of 2F1 and 2A9 in early G1 is mediated post-transcriptionally.

Zusätzliches Material: 3 Ill.