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The end of the LINE?: lack of recent L1 activity in a group of South American rodents.

ABSTRACT: L1s (LINE-1: Long Interspersed Nuclear Element 1) are present in all mammals examined to date. They occur in both placental mammals and marsupials and thus are thought to have been present in the genome prior to the mammalian radiation. This unusual conservation of a transposable element family for over 100 million years has led to speculation that these elements provide an advantage to the genomes they inhabit. We have recently identified a group of South American rodents, including rice rats (Oryzomys), in which L1s appear to be quiescent or extinct. Several observations support this conclusion. First, genomic Southern blot analysis fails to reveal genus-specific bands in Oryzomys. Second, we were unable to find recently inserted elements. Procedures to enrich for young elements did not yield any with an intact open reading frame for reverse transcriptase; all elements isolated had numerous insertions, deletions, and stop codons. Phylogenetic analysis failed to yield species-specific clusters among the L1 elements isolated, and all Oryzomys sequences had numerous private mutations. Finally, in situ hybridization of L1 to Oryzomys chromosomes failed to reveal the characteristic L1 distribution in Oryzomys with either a homologous or heterologous probe. Thus, Oryzomys is a viable candidate for L1 extinction from a mammalian host.

SUBMITTER: Casavant NC

PROVIDER: S-EPMC1461046 | biostudies-other | 2000 Apr

REPOSITORIES: biostudies-other

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The end of the LINE?: lack of recent L1 activity in a group of South American rodents.

Casavant N C NC Scott L L Cantrell M A MA Wiggins L E LE Baker R J RJ Wichman H A HA

Genetics 20000401 4

L1s (LINE-1: Long Interspersed Nuclear Element 1) are present in all mammals examined to date. They occur in both placental mammals and marsupials and thus are thought to have been present in the genome prior to the mammalian radiation. This unusual conservation of a transposable element family for over 100 million years has led to speculation that these elements provide an advantage to the genomes they inhabit. We have recently identified a group of South American rodents, including rice rats ( ...[more]

PMID: 10747071

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Project description:BACKGROUND:Physical inactivity and sedentary behavior are major concerns for public health. Although global initiatives have been successful in monitoring physical activity (PA) worldwide, there is no systematic action for the monitoring of correlates of these behaviors, especially in low- and middle-income countries. Here we describe the prevalence and distribution of PA domains and sitting time in population sub-groups of six south American countries. METHODS:Data from the South American Physical Activity and Sedentary Behavior Network (SAPASEN) were used, which includes representative data from Argentina (n?=?26,932), Brazil (n?=?52,490), Chile (n?=?3719), Ecuador (n?=?19,851), Peru (n?=?8820), and Suriname (n?=?5170). Self-reported leisure time (?150?min/week), (?150?min/week), transport (?10?min/week), and occupational PA total (?10?min/week), as well as sitting time (?4?h/day) were captured in each national survey. Sex, age, income, and educational status were exposures. Descriptive statistics and harmonized random effect meta-analyses were conducted. RESULTS:The prevalence of PA during leisure (Argentina: 29.2% to Peru: 8.6%), transport (Peru: 69.7% to Ecuador: 8.8%), and occupation (Chile: 60.4 to Brazil 18.3%), and ?4?h/day of sitting time (Peru: 78.8% to Brazil: 14.8%) differed widely between countries. Moreover, total PA ranged between 60.4% (Brazil) and 82.9% (Chile) among men, and between 49.4% (Ecuador) and 74.9% (Chile) among women. Women (low leisure and occupational PA) and those with a higher educational level (low transportation and occupational PA as well as high sitting time) were less active. Concerning total PA, men, young and middle-aged adults of high educational status (college or more) were, respectively, 47%?[OR?=?0.53 (95% CI?=?0.36-0.78), I2 =?76.6%], 25%?[OR?=?0.75 (95% CI?=?0.61-0.93), I2 =?30.4%] and 32%?[OR?=?0.68 (95% CI?=?0.47-1.00), I2 =?80.3%] less likely to be active. CONCLUSIONS:PA and sitting time present great ranges and tend to vary across sex and educational status in South American countries. Country-specific exploration of trends and population-specific interventions may be warranted.

Dataset Information

The end of the LINE?: lack of recent L1 activity in a group of South American rodents.

Publications

The end of the LINE?: lack of recent L1 activity in a group of South American rodents.

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