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- Lettevall, Erland, et al.
(författare)
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Social structure and residency in aggregations of male sperm whales
- 2002
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Ingår i: Canadian Journal of Zoology-Revue Canadienne De Zoologie. - 0008-4301. ; 80:7, s. 1189-1196
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Tidskriftsartikel (refereegranskat)abstract
- Sperm whales (Physeter macrocephalus) are sexually dimorphic in several respects, including size, latitudinal distribution, and social structure. Females are known to have complex social structures, including long-term bonds, but the social structures of sexually mature or maturing males have received much less attention. Using data from aggregations of males off Norway, Nova Scotia, New Zealand, and the Galapagos Islands, we examined aggregation size, residence times within aggregations, clustering at the surface, and long-term bonds. Results were generally consistent among study areas. The aggregations found in each area contained around 10-30 males at any time, and were usually a few tens of kilometres across. Mean residence times within aggregations ranged from a few days to a few weeks. Close clustering at the surface was rare, but present at each site. There was no evidence for preferred companionship between individuals at any temporal scale in any of the study areas. The rarity of clustering and the apparent lack of long-term relationships amongst male sperm whales contrast strongly with results of studies on females, suggesting that both close spatial proximity at the surface and permanent bonds between individuals may be a consequence of the need for care of the young.
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- Yu, Wenqiang, et al.
(författare)
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Poly(ADP-ribosyl)ation regulates CTCF-dependent chromatin insulation
- 2004
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 36:10, s. 1105-1110
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Tidskriftsartikel (refereegranskat)abstract
- Chromatin insulators demarcate expression domains by blocking the cis effects of enhancers or silencers in a position-dependent manner1, 2. We show that the chromatin insulator protein CTCF carries a post-translational modification: poly(ADP-ribosyl)ation. Chromatin immunoprecipitation analysis showed that a poly(ADP-ribosyl)ation mark, which exclusively segregates with the maternal allele of the insulator domain in the H19 imprinting control region, requires the bases that are essential for interaction with CTCF3. Chromatin immunoprecipitation−on−chip analysis documented that the link between CTCF and poly(ADP-ribosyl)ation extended to more than 140 mouse CTCF target sites. An insulator trap assay showed that the insulator function of most of these CTCF target sites is sensitive to 3-aminobenzamide, an inhibitor of poly(ADP-ribose) polymerase activity. We suggest that poly(ADP-ribosyl)ation imparts chromatin insulator properties to CTCF at both imprinted and nonimprinted loci, which has implications for the regulation of expression domains and their demise in pathological lesions.
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