Thyroid hormone regulates lipogenesis differently in rat liver and brown adipose tissue (BAT). In the hypothyroid state, lipogenesis is suppressed in liver but enhanced in BAT. Here we investigated the mechanisms underlying increased lipogenesis in hypothyroid BAT. Housing the animals at 28 degrees C decreased lipogenesis in hypothyroid BAT to euthyroid levels. Denervation resulted in a 90% reduction in lipogenesis in hypothyroid BAT such that levels were lower than in euthyroid tissue. Thyroid hormone treatment of hypothyroid rats stimulated fatty acid synthesis in denervated BAT, as in liver, but decreased it in intact BAT. Steady-state levels of mRNA encoding acetyl-CoA carboxylase, fatty-acid synthase, and spor 14 were measured in similar animals by Northern analysis. The expression of these mRNAs mirrored the lipogenic data, showing that both thyroid hormone and the sympathetic nervous system work at a pretranslational level in this tissue. These data suggest that the increased BAT lipogenesis found with hypothyroidism is mediated by the sympathetic nervous system to counter the reduction in metabolic rate in these animals.

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Tropical and subtropical Caulerpa species are epidemic to northern and southern Taiwan seashore. We here describe the molecular characteristics of rRNA gene, including the internal transcribed spacers (ITS) in this genus and a comparison was made with associated species sequences registered in the GenBank. A total of nine specimens (C. racemosa var. microphysa, macrophysa, peltata, laetevirens, C. serrulata and C. elongata) were investigated. Samples were collected and distinguished first from morphological characteristics. The genomic DNA was individually extracted using CTAB protocol. To amplify the 18S rRNA, ITS1, 5.8S rRNA, ITS2 and 28S rRNA sequences, a primer pair NS7 and ITS4, sequences located in nuclear rRNA region, was used. The range of 980–1100 bp DNA fragment from genomic DNA of individual plant was generated from polymerase chain reaction (PCR). Amplified fragments were sequenced automatically with ABI sequencer. The sequences were aligned with those of other Caulerpa species retrieved from the GenBank. The phylogenetic tree was constructed using Clustal method. The comparison of whole sequence and 18S rRNA and ITS1 region among these specimens shows that the interspecies divergence within C. racemosa var. microphysa, macrophysa, peltata and laetevirens is larger than those of intraspecies of C. taxifolia, C. serrulata and C. elongata. It is supposed that they (C. racemosa var. microphysa, macrophysa, peltata and laetevirens) should be in the position of different species in Caulerpa genus from the present rRNA sequences analysis. The sequences of 5.8S region are shown more conserve than that of 18S region. The identity of ITS1 and ITS2 regions in present species are low, comparing with C. taxifolia, C. maxicana.