A specific progesterone receptor of myometrial cytosol from the rhesus monkey.

A specific progesterone receptor of myometrial cytosol from the rhesus monky is described. Characterization of the receptor by sucrose density gradient centrifugation revealed 2 peaks at 4s and 7.5s. The 4s peak seen in all groups (castrate; castrate plus estrogen treated; castrate plus estrogen and progesterone treated) contained little specific progesterone binding but the 7.5s peak, seen only in the estrogen-treated animal, was specific for progesterone. Competition studies revealed the reeceptor affinities to be: progesterone 100, 5alpha dehydroprogesterone 81.9 melengestrol acetate 72.5, norgestrel 53, desoxycorticosterone 25.9, 5beta-dihydroprogesterone 1.2, and 17 hydroxyprogesterone less than 1. Receptor levels measured from Scatchard plot analysis of of equilibrium data were 7 fM/mg cytosol protein (castrate), 45.2 fM/mg (p less than .01, estrogen treated), and 10.5 (estrogen plus progesterone treated). The association constant (approximately 5 x 10(-9)M) was similar in all 3 groups.     

Commuting between Golgi cisternae--mind the GAP!

Intracellular transport has remained central to cell biology now for more than 40 years. Despite this, we still lack an overall mechanistic framework that describes transport in different parts of the cell. In the secretory pathway, basic questions, such as how biosynthetic cargo traverses the pathway, are still debated. Historically, emphasis was first put on interpreting function from morphology at the ultrastructural level revealing membrane structures such as the transitional ER, vesicular carriers, vesicular tubular clusters, Golgi cisternae, Golgi stacks and the Golgi ribbon. This emphasis on morphology later switched to biochemistry and yeast genetics yielding many of the key molecular players and their associated functions that we know today. More recently, microscopy studies of living cells incorporating biophysics and system analysis has proven useful and is often used to readdress earlier findings, sometimes with surprising outcomes.     

Inosine stimulates chemotaxis, Ca2+-transients and actin polymerization in immature human dendritic cells via a pertussis toxin-sensitive mechanism independent of adenosine receptors

Inosine is an endogenous purine nucleoside, which is formed by adenosine deaminidase during adenosine breakdown and is released into the extracellular space from the sympathetic nervous system or injured cells. Here, we studied the biological activity of inosine on human dendritic cells (DC), which are specialized antigen presenting cells characterized by their ability to migrate from the blood to peripheral tissues, and then to secondary lymphoid organs where they initiate adaptive immune responses. In immature DC, inosine concentration-dependently stimulated Ca(2+)-transients, actin polymerization, and chemotaxis. Experiments with adenosine receptor antagonists and pertussis toxin (PTX) as well as desensitization studies suggested that the activity of inosine was mediated by a G protein-coupled receptor pathway independent of adenosine receptors. DC, induced to mature by lipopolysaccharide, lost their ability to respond towards inosine with these activities. Moreover, inosine did neither influence membrane expression of CD54, CD80, CD83, CD86, HLA-DR, and MHC class I molecules nor modulated secretion of interleukin (IL)-12, IL-10, and tumor necrosis factor alpha in immature and lipopolysaccharide-matured DC. In aggregate, our study indicates that inosine may be involved in the trafficking control system of immature DC, and mediates its chemotactic activity by a PTX-sensitive mechanism independent of adenosine receptors.     

A strategy for constructing high-resolution genetic maps of the human genome: a genetic map of chromosome 17p, ordered with meiotic breakpoint-mapping panels.

Genetic linkage analyses with genotypic data obtained from four CEPH reference families initially assigned 24 new PCR-based markers to chromosome 17 and located the markers at specific intervals of an existing genetic map of chromosome 17p. Each marker was additionally genotyped with an ordered set of obligate, phase-known recombinant chromosomes. The breakpoint-mapping panels for each family consisted of two parents, one sib with a nonrecombinant chromosome, and one or more sibs with obligate recombinant chromosomes. The relative order of markers was determined by sorting segregation patterns of new markers and ordered anchor markers and by minimizing double-recombination events. Consistency of segregation patterns with multiple flanking loci constituted support for order. A genetic map of chromosome 17p was completed with 39 markers in 23 clusters, with an average space of 3 cM between clusters. The collection of informative genotypes was highly efficient, requiring fivefold fewer genotypes than would be collected with all the CEPH families. Given the availability of large numbers of highly informative PCR-based markers, meiotic breakpoint mapping should facilitate construction of a human genomic map with 1-cM resolution.     

Muscle capillary supply in harbor seals.

The purpose of this study was to examine muscle capillary supply in harbor seals. Locomotory and nonlocomotory muscles of four harbor seals (mass = 17.5-41 kg) were glutaraldehyde-perfusion fixed and samples processed for electron microscopy and analyzed by morphometry. Capillary-to-fiber number and surface ratios were 0.81 +/- 0.05 and 0.16 +/- 0.01, respectively. Capillary length and surface area per volume of muscle fiber were 1,495 +/- 83 mm/mm(3) and 22.4 +/- 1.6 mm(2)/mm(3), respectively. In the locomotory muscles, we measured capillary length and surface area per volume mitochondria (20.1 +/- 1.7 km/ml and 2,531 +/- 440 cm(2)/ml). All these values are 1.5-3 times lower than in muscles with similar or lower volume densities of mitochondria in dogs of comparable size. Compared with terrestrial mammals, the skeletal muscles of harbor seals do not match their increased aerobic enzyme capacities and mitochondrial volume densities with greater muscle capillary supply. They have a smaller capillary-to-fiber interface and capillary supply per fiber mitochondrial volume than terrestrial mammals of comparable size.     

NADPH production in the oxidative pentose phosphate pathway as source of reducing equivalents in glycolysis of human red cells in vitro.

Studies have been carried out on human erythrocytes in vitro to clarify the deficit of pyruvate formation under conditions when 2,3 DPG is degraded. The results lead to the conclusion that there exist a cross connection between the glycolytic and the oxidative pentose phosphate pathway which is mediated by the NADP/NADPH couple. NADPH serves as additional reducing equivalent in the reaction of the LDH. In the absence of glucose the pool of the metabolites of the pentose phosphate pathway is able to supply glucose-6-phosphate for the production of NADPH by recombination. The reaction of NADPH at the LDH is probably of significance under in vivo conditions.     

Can spectral cues contribute to species separation in closely related grasshoppers?

 The acridid grasshoppers Chorthippus biguttulus and Ch. mollis, which are closely related and often sympatric species, were compared intra- and interspecifically with regard to the spectra of their calling and courtship songs and of the sound-induced vibrations of the tympanal membrane, as well as the threshold curves of the tympanal nerve. In the low-frequency range but not in the ultrasound region, the maxima of these various curves fall at distinctly different frequencies in the two species. It is shown that the low-frequency sensitivity of the auditory system in both species, especially in females, is well matched to the conspecific song spectra but not to those of the heterospecific songs. Whether these characteristics actually contribute to species discrimination remains to be determined by behavioural tests. Accepted: 23 August 1996