Genetic and epigenetic diversity and structure of Phragmites australis from local habitats of the Songnen Prairie using amplified fragment length polymorphism markers.

The genetic and epigenetic diversity and structure of naturally occurring Phragmites australis populations occupying two different habitats on a small spatial scale in the Songnen Prairie in northeastern China were investigated by assessing amplified fragment length polymorphisms (AFLPs) and methylation-sensitive amplified polymorphisms (MSAPs) through fluorescent capillary detection. The two groups of P. australis were located in a seasonal waterlogged low-lying and alkalized meadow with a pH of 8-8.5 and in an alkaline patch without accumulated rainwater and with a pH greater than 10. These groups showed high levels of genetic diversity at the habitat level based on the percentage of polymorphic bands (90.32, 82.56%), Nei's gene diversity index (0.262, 0.248), and the Shannon diversity index (0.407, 0.383). Although little is known about the between-habitat genetic differentiation of P. australis on a small spatial scale, our results implied significant genetic differentiation between habitats. Extensive epigenetic diversity within habitats, along with clear differentiation, was found. Specifically, the former habitat (Habitat 1, designated H1) harbored higher levels of genetic and epigenetic diversity than the latter (Habitat 2, designated H2), and population-level diversity was also high. This study represents one of few attempts to predict habitat-based genetic differentiation of reeds on a small scale. These assessments of genetic and epigenetic variation are integral aspects of molecular ecological studies on P. australis. Possible causes for within- and between-habitat genetic and epigenetic variations are discussed.

Cloning, characterization, expression, and feeding response of thyrotropin receptor in largemouth bass (Micropterus salmoides).

Thyrotropin receptor (TSHR) is a G-protein-coupled receptor that regulates the synthesis, storage, and secretion of thyroid hormones in the thyroid tissue. The aims of the present study were to characterize the full-length TSHR cDNA in largemouth bass (Micropterus salmoides), and to determine the TSHR gene transcription levels in different tissues. In addition, the response of TSHR transcription levels to daily feeding in thyroid tissue was investigated. The results showed that the full-length cDNA sequence was 2743 bp with an open reading frame of 2340 bp encoding a 779-amino acid peptide. BLAST analysis indicated that the amino acid sequence displayed 58.4-90.2% identity and 5.6-125.8 divergence, compared with other known fish species. The most abundant TSHR transcription levels were found in the spleen, head kidney, and kidney. Feeding did not affect the transcription level of TSHR in thyroid tissue over the course of the day. Thus, the current study suggests that there was no relationship between daily nutritional status and TSHR transcription level in the thyroid tissue of largemouth bass. The spleen, head kidney, and kidney exhibited the most abundant TSHR transcription levels.