Novel mutations in families with unusual and variable disorders of the skeletal muscle sodium channel.

Mutations in the skeletal muscle sodium channel gene (SCN4A) have been described in paramyotonia congenita (PMC) and hyperkalaemic periodic paralysis (HPP). We have found two mutations in SCN4A which affect regions of the sodium channel not previously associated with a disease phenotype. Furthermore, affected family members display an unusual mixture of clinical features reminiscent of PMC, HPP and of a third disorder, myotonia congenita (MC). The highly variable individual expression of these symptoms, including in some cases apparent non-penetrance, implies the existence of modifying factors. Mutations in SCN4A can produce a broad range of phenotypes in muscle diseases characterized by episodic abnormalities of membrane excitability.     

Vaccinia virus encodes a polypeptide homologous to epidermal growth factor and transforming growth factor

Epidermal growth factor (EGF) and transforming growth factor type I (TGF) are polypeptides of 53 and 50 amino acid residues, respectively. Both bind to EGF receptor, a 1,200-residue transmembranous glycoprotein, leading to phosphorylation of the receptor, enhancement of its tyrosine-specific kinase activity and ultimately to stimulation of cell growth. We report here that a 140-residue polypeptide encoded by one of the early genes of vaccinia virus (VV) is related closely to EGF and TGF. The presence of putative signal and transmembranous sequences further suggests that the viral protein might be an integral membrane protein, but that, as in the case of EGF itself, the membrane-associated form may be the precursor of a soluble growth factor. Production of EGF-like growth factors by virally infected cells could account for the proliferative diseases associated with members of the poxvirus family such as Shope fibroma virus, Yaba tumour virus, and molluscum contagiosum virus (MCV).     

DNA in wheat seeds from European archaeological sites

We have used hybridization analysis to detect ancient DNA in wheat seeds collected from three archaeological sites in Europe and the Middle East. One of these samples, carbonizedT. spelta dated to the first millennium BC, has yielded PCR products after amplification with primers directed at the leader regions of the HMW (high molecular weight) glutenin alleles. Sequences obtained from these products suggest that the DNA present in the Danebury seeds is chemically damaged, as expected for ancient DNA, and also indicate that it should be possible to study the genetic variability of archaeological wheat by ancient DNA analysis. Finally, we describe a PCR-based system that enables tetraploid and hexaploid wheats to be distinguished.     

Glutamine synthetase activity in subdivisions of brain of the shark, Squalus acanthias

Specific activity of glutamine synthetase in Squalus acanthias (spiny dogfish) central nervous system regions was highest in the cerebellum and lowest in the spinal cord. The levels of activity may relate to the excitability of each region by regulating the glutamate pool.     

John Dewey's pragmatist alternative to the belief-acceptance dichotomy

Defenders of value-free science appeal to cognitive attitudes as part of a wedge strategy, to mark a distinction between science proper and the uses of science for decision-making, policy, etc. Distinctions between attitudes like belief and acceptance have played an important role in defending the value-free ideal. In this paper, I will explore John Dewey's pragmatist philosophy of science as an alternative to the philosophical framework the wedge strategy rests on. Dewey does draw significant and useful distinctions between different sorts of cognitive attitudes taken by inquirers, but none can be used to support the wedge strategy.     

Inter-simple sequence repeat (ISSR) variation in three populations of Gaura neomexicana ssp. coloradensis (Onagraceae), F.E. Warren Air Force Base, Cheyenne, Wyoming

We investigated genetic variation within and between 3 populations of Gaura neomexicana ssp. coloradensis , a federally listed threatened species, using inter-simple sequence repeats. The data matrix included 24 individuals scored for 88 bands, with 3.4% missing data. Cluster analysis showed that members of the 3 populations are very similar and are intermixed in the phenogram. Principal coordinate analysis indicated that members of the Crow Creek population are different from the Diamond Creek and ""unnamed drainage"" populations. This could be the result of historic differences, current changes in vegetation at the Crow Creek site, or an artifact of limited sampling. In any case, for management purposes it is best to preserve the dwindling population at Crow Creek as well as the thriving populations at the other 2 sites.     

Boltzmann's H-theorem, its discontents, and the birth of statistical mechanics

A comparison is made of the traditional Loschmidt (reversibility) and Zermelo (recurrence) objections to Boltzmann's H-theorem, and its simplified variant in the Ehrenfests’ 1912 wind-tree model. The little-cited 1896 (measure-theoretic) objection of Zermelo (similar to an 1889 argument due to Poincaré) is also analysed. Significant differences between the objections are highlighted, and several old and modern misconceptions concerning both them and the H-theorem are clarified. We give particular emphasis to the radical nature of Poincaré's and Zermelo's attack, and the importance of the shift in Boltzmann's thinking in response to the objections taken together.