Statistical method for testing the neutral mutation hypothesis by DNA polymorphism.

Cannon, Barbara, and Jan Nedergaard. Brown Adipose Tissue: Function and Physiological Significance. Physiol Rev 84: 277–359, 2004; 10.1152/physrev.00015.2003.—The function of brown adipose tissue i...

Brown Adipose Tissue: Function and Physiological Significance

The evidentiary basis of the currently accepted classification of living amphibians is discussed and shown not to warrant the degree of authority conferred on it by use and tradition. A new taxonomy of living amphibians is proposed to correct the deficiencies of the old one. This new taxonomy is based on the largest phylogenetic analysis of living Amphibia so far accomplished. We combined the comparative anatomical character evidence of Haas (2003) with DNA sequences from the mitochondrial transcription unit H1 (12S and 16S ribosomal RNA and tRNAValine genes, ≈ 2,400 bp of mitochondrial sequences) and the nuclear genes histone H3, rhodopsin, tyrosinase, and seven in absentia, and the large ribosomal subunit 28S (≈ 2,300 bp of nuclear sequences; ca. 1.8 million base pairs; x = 3.7 kb/terminal). The dataset includes 532 terminals sampled from 522 species representative of the global diversity of amphibians as well as seven of the closest living relatives of amphibians for outgroup comparisons. The...

https://bioone.org/journals/Bulletin-of-the-American-Museum-of-Natural-History/volume-2006/issue-297/0003-0090(2006)297[0001:TATOL]2.0.CO;2/THE-AMPHIBIAN-TREE-OF-LIFE/10.1206/0003-0090(2006)297[0001:TATOL]2.0.CO;2.pdf

The amphibian tree of life

Polyploids — organisms that have multiple sets of chromosomes — are common in certain plant and animal taxa, and can be surprisingly stable. The evidence that has emerged from genome analyses also indicates that many other eukaryotic genomes have a polyploid ancestry, suggesting that both humans and most other eukaryotes have either benefited from or endured polyploidy. Studies of polyploids soon after their formation have revealed genetic and epigenetic interactions between redundant genes. These interactions can be related to the phenotypes and evolutionary fates of polyploids. Here, I consider the advantages and challenges of polyploidy, and its evolutionary potential.

/pdf/the-advantages-and-disadvantages-of-being-polyploid-3szbdyr9u1.pdf

The advantages and disadvantages of being polyploid

EVidenceModeler (EVM) is presented as an automated eukaryotic gene structure annotation tool that reports eukaryotic gene structures as a weighted consensus of all available evidence. EVM, when combined with the Program to Assemble Spliced Alignments (PASA), yields a comprehensive, configurable annotation system that predicts protein-coding genes and alternatively spliced isoforms. Our experiments on both rice and human genome sequences demonstrate that EVM produces automated gene structure annotation approaching the quality of manual curation.

/pdf/automated-eukaryotic-gene-structure-annotation-using-3fo28wpira.pdf

Automated Eukaryotic Gene Structure Annotation Using EVidenceModeler and the Program to Assemble Spliced Alignments

Endocrine disruption by environmental gestagens in amphibians - A short review supported by new in vitro data using gonads of Xenopus laevis.

Thermogenesis induced by cafeteria feeding in young growing rats.

Laboratory rodents can be induced to overeat voluntarily when exposed to a choice of highly palatable human foods so-called "cafeteria diet". The hyperphagia of these animals is associated with marked increases in energy expenditure and reduced levels of energetic efficiency. Increases in Diet-Induced-Thermogenesis (DIT) in response to overfeeding have been demonstrated in several species including man. The studies with the cafeteria-fed rats confirm the large potential for DIT in young animals. In older (26-week-old rats) a dramatic decline in the capacity for DIT is observed. Increases in energy expenditure resulting from hyperphagia appear to be mediated by the sympathetic nervous system, which causes activation of heat production in brown adipose tissue (BAT). The high thermogenic potential of BAT is due to the physiological uncoupling of oxidative phosphorylation in the inner mitochondrial membrane. This activity is enhanced by overfeeding, which causes hypertrophy. DIT and BAT are controlled by hormonal action: noradrenaline appears to be the primary activator of BAT and insulin may be required for DIT and may even activate thermogenesis. Other hormones such as glucagon, thyroid, melatonin, TSH, endorphins and sex hormones are also implicated in one way or another in the regulation of energy balance and the control of thermogenesis.

The role of brown fat in diet-induced thermogenesis.

African clawed frogs of the widespread polytypic species Xenopus laevis Daudin, 1802 (ranging large parts of sub-Saharan Africa) have been spreading since the 1940s, and have established reproductive populations in Europe, Asia and the Americas, where they can have negative impact as competitors of native amphibians and as disease vectors for chytridomycosis or ranaviruses. Here we use two mitochondrial (cytochrome b, 16S rDNA) and one nuclear (RAG 1: Recombination Associated Gene 1) DNA markers to infer the potential origin of invasive clawed frogs from Sicily that represent the largest invasive population in Europe. Identical mtDNA haplotypes match with those of Xenopus laevis, and Sicilian clawed frogs very probably belong to a lineage from the Cape Region of South Africa, most likely originating from a laboratory stock. Nuclear data support this conclusion. Identical mtDNA sequences (cyt b, 16S) of frogs sampled across their range in Sicily suggest the occurrence of a single source population ...

Identification and potential origin of invasive clawed frogs Xenopus (Anura: Pipidae) in Sicily based on mitochondrial and nuclear DNA.

Binding of (-)-[3H]dihydroalprenolol [( 3H]DHA) to isolated brown adipose tissue (BAT) microsomal membranes was used to estimate beta-adrenoreceptor density, and this was found to be saturable, reversible, and stereospecific. Scatchard analysis indicated a single class of binding sites of equilibrium dissociation constant 2.2 nM, with a maximum number of binding sites of 160-170 fmol/mg protein. These values were unaffected by the age or sex of the animals, and similar Kd values were obtained for binding to heart and lung membranes. The kinetically derived Kd from forward and reverse reactions was 1.4 nM for BAT. Hofstee analysis of displacement of [3H]DHA produced linear plots for propranolol but curvilinear plots for atenolol and ICI 118,551. Atenolol showed 50-fold selectivity for beta 1-receptors and ICI 118,551 50-fold selectivity for beta 2-receptors in heart, lung, and BAT membranes. These plots indicated beta 1:beta 2-receptor ratios of 59:41 for BAT and heart and 25:75 for lung. It is possible that both beta-adrenoreceptor subtypes in BAT may be involved in the activation of thermogenesis in the tissue.

Matthias Stöck

Papers

Endocrine disruption by environmental gestagens in amphibians - A short review supported by new in vitro data using gonads of Xenopus laevis.

Thermogenesis induced by cafeteria feeding in young growing rats.

The role of brown fat in diet-induced thermogenesis.

Identification and potential origin of invasive clawed frogs Xenopus (Anura: Pipidae) in Sicily based on mitochondrial and nuclear DNA.

Beta-adrenoreceptors in rat brown adipose tissue: proportions of beta 1- and beta 2-subtypes.