Structure of equine corticotropin releasing factor

A 41 amino acid peptide, probably identical in structure to human corticotropin releasing factor, was isolated from 70 equine hypothalami by methanol extraction, immunoaffinity chromatography and single step of reverse phase HPLC. The amino acid sequence was determined by gas phase sequence analysis. Probable carboxyl terminal amidation was demonstrated by similar retention times for equine and human corticotropin releasing factor on reverse phase HPLC at pH 8. The likely structure of equine corticotropin releasing factor is: Ser-Glu-Glu-Pro-Pro- Ile-Ser-Leu-Asp-Leu-Thr-Phe-His-Leu-Leu-Arg-Glu-Val-Leu-Glu-Met-Ala-Arg-Ala-Glu-Gln-Leu-Ala-Gln-Gln-Ala-His-Ser-Asn- Arg-Lys-Leu-Met-Glu-Ile-Ile-NH₂. The purified peptide is equipotent with human corticotropin releasing factor in an in vitro bioassay and in a human plasma binding protein assay.     

A protein of Halobacterium halobium immunologically related to the v-myc gene product

A 70 kDa protein of Halobacterium halobium cross-reacts with an antiserum directed against the v-myc gene product of the avian myelocytomatosis virus (MC29). This cross-reaction is in agreement with hybridization studies which indicate that H. halobium possesses DNA and RNA sequences homologous to the v-myc gene.     

Linear dichroism and orientational studies of carotenoid Langmuir-Blodgett films

The linear dichroism of single monolayers of lutein, zeaxanthin and a mixture of lutein and synthetic phosphatidylcholine has been measured. The angle of orientation of the carotenoid molecules was found to lie between 45° and 51° relative to the plane of the solid support. Although the adsorbed monolayers were mostly in a monomeric state, microscopic observations, as well as the II-A isotherms, indicated the existence of crystalline islets. The results have been interpreted in connection with Haidinger's polarization brushes.     

The structure of agarose gels,and the accommodation within them of irregularly shaped particles

This paper shows how the number of cross-linkage points (nodes) in a random reticulum, such as an ideal polysaccharide gel, may be calculated in accordance with mathematical principles. The influence of nodal configurations upon the statistical geometry of the reticulum is discussed, and it is shown from experimental evidence that the nodal configurations in agarose gel are nonrandom. A method is given for calculating the accommodation probability of an irregularly shaped particle in a reticulum, which is relevant to the theory of gel chromatography and to the distribution of cells in tissues permeating a network of capillaries or veins.     

Carbamylcholine, TRH, PGF2 alpha and fluoride enhance free intracellular Ca++ and Ca++ translocation in dog thyroid cells

Effects on Ca++ translocation and [Ca++]i were studied in dog thyro?d cell monolayers using both 45Ca++ efflux and the indicator quin-2. Carbamylcholine, a non hydrolysable analog of acetylcholine, through muscarinic receptors, and to a lesser extent TRH and PGF2 alpha increased both these parameters. [Ca++]i increased by 171, 100 and 75% respectively over a basal level of 66 +/- 17 nM (mean +/- SD). The response to carbamylcholine was biphasic. A transient increase in [Ca++]i was followed by a more sustained phase where the [Ca++]i was slightly higher than the basal level. Only the first phase was insensitive to extracellular Ca++ depletion. This phase is probably due to a release of Ca++ from an intracellular store. NaF also induced a sustained rise in [Ca++]i dependent on extracellular Ca++ and affected 45Ca++ efflux. Our data provide direct evidence of an implication of intracellular Ca++ in the response of dog thyro?d cells to all these agents.     

Mass characteristics of DNA obtained from chromosomes of a human carcinoma cell line

Sedimentation studies of DNA from chromosomes extracted from human mitotic cells showed that highmolecular-weight DNA can be obtained if cell hypotonic treatments and prolonged metaphase blocks are avoided. Two types of large double-stranded DNA were observed. One of these (M _r = 2.5×10⁸) appeared as a size class with characteristics reminiscent of the chromosomal DNA subunit hypothesis. However, this DNA is the decay product of larger molecules, whose minimum molecular weight is 6×10⁸.     

Constructional morphology: The analysis of constraints in evolution dedicated to A. Seilacher in honour of his 60. birthday

Evolutionary change is opportunistic, but its course is strongly constrained in several fundamental ways. These constraints (historical/phylogenetic, functional/adaptive, constructional/morphogenetic) and their dynamic relationships are discussed here and shown to constitute the conceptual framework of Constructional Morphology. Notwithstanding recent published opinions which claim that the discovery of constraints renders Neodarwinian selection theory obsolete, we regard the insights of Constructional Morphology as being entirely consistent with this theory. As is shown here in the case of the Hyracoidea, formal analysis of the constraints which have framed the evolution of various characters extends our understanding of the evolution of a taxon.     

Catalysis by heteropentalenes of electron transfer to oxygen from ferredoxin-NADP oxidoreductase reduced by NADPH

A range of heteropentalene and bipyridinium compounds have been tested as catalysts of electron transfer to oxygen from spinach ferredoxin-NADP⁺ oxidoreductase reduced by NADPH. For a particular class of compound, the rate of oxygen reduction increased with increasing midpoint potential of the compound under conditions in which reduction of the compound was rate-limiting. Compounds with similar midpoint potentials from different structural classes showed marked differences in rate, attributed to specificity in the interaction with ferredoxin-NADP⁺ oxidoreductase.