Biomedical subjects

Rachel Ben-Shlomo

Publications and source records attributed to Rachel Ben-Shlomo.

3 recordsLinked to original sources

PubMed2006

Gene diversity and mode of reproduction in the brooded larvae of the coral Heteroxenia fuscescens.

The soft coral Heteroxenia fuscescens is a common shallow-reef brooding species in the Red Sea. By means of amplified fragment length polymorphism markers, we studied modes of reproduction of planulae (sexual vs. vegetative) and levels of gene diversity of a population residing in the northern Gulf of Eilat, Red Sea. Eighty-nine larvae were collected from 9 mother colonies at 3 locations over a distance of 5 km. Amplifications revealed 221 putative loci, of which 81.4% were polymorphic; gene diversity was 0.29, allowing good identification of individual genotypes. No 2 identical DNA samples were present, so no asexual reproduction of planulae was indicated. The sampled planulae did not exhibit any genetic structure characteristic to a specific location, indicating one large gene pool and extensive gene flow among H. fuscescens specimens inhabiting the northern Gulf of Eilat.

Animals↗

PubMed2005

Light pulse-induced heme and iron-associated transcripts in mouse brain: a microarray analysis.

Synchronization of circadian oscillators with the outside world is achieved by the acute effects of light on the levels of one or more clock components. In mammals the PAS transcription factors Clock, NPAS2, and BMAL1 regulate gene expression as a function of the day-night cycle. Both PAS domains of NPAS2 were found to bind heme as a prosthetic group, form a gas-regulated sensor, and exert heme-status control of DNA binding in vitro. In a microarray analysis comparing overall changes in brain transcript levels between mice subjected to light pulses during the dark phase with animals maintained in darkness, we traced consistent changes in more than 200 different transcripts. Of these, 20 are associated with heme and iron biosynthesis and catabolism. A model for the pathway of induction of heme and iron homeostasis-related transcripts resulting from light pulses suggests that light signals (as stressors) induce transcription of heme oxygenase 2 (Hmox2) and cytochrome P450 oxidoreductase (Por), which may serve as a primary line of cellular defense. HMOX2 degrades heme from proteins such as hemoglobin. This degradation generates CO, a signal molecule, and may also change the redox state of the cell by reducing the NADPH/NADP ratio. This could lead to up-regulation of globin gene transcription, thereby releasing iron that in turn controls production of ferritins, and further up-regulating aminolevulinate synthase 2 (Alas2).

Animals↗

PubMed2002

Circadian rhythm entrainment in flies and mammals.

Circadian rhythms are a fundamental adaptation of living cells to the daily and seasonal fluctuation in light and temperature. Circadian oscillations persist in constant conditions; however, they are also phase-adjusted (entrained) by day-night cycles. It is this entrainability that provides for the proper phasing of the program, to the sequence of external changes that it has evolved to exploit. Synchronization of circadian oscillators with the outside world is achieved because light, temperature, or other external temporal cues, have acute effects on the levels of one or more of the clock's components. The consequences are ripples through the interconnected molecular loops, leading to a stable phase realignment of the endogenous rhythm generator and the external conditions. This review summarized the evolving knowledge of the different types, modes, and molecular processes of entrainment in flies and mammals.

Animals↗