Evaluation of the ability of intact platelets to accumulate acridine orange

A new approach to the evaluation of the uptake of fluorescent probes by intact cells is described. Acridine orange (AO) was used because it can be selectively accumulated by serotonin-containing granules of platelets. Analysis of the fluorescence signal allows the estimation of the relative volume of the granules and the equilibrium coefficients for AO transport across the cytoplasm and granule membranes. The following results were obtained for human and rabbit platelets: the relative volumes of the granules were 14 +/- 1% and 29 +/- 2%, the ratios of intragranular-extracellular probe concentration were 2260 +/- 382 and 30,000 +/- 5550, and the cytoplasm-extracellular medium concentration ratios were 375 +/- 60 and 225 +/- 60, respectively.     

On the chromosomic polymorphism ofRattus rattus L. a study on West-European populations

Riassunto Nell'ambito del problema del polimorfismo cromosomico diRattus rattus è stato studiato il cariotipo di varie popolazioni europee (Italia, Svizzera, Francia ed Inghilterra) riferibili alle sottospeciefrugivorus, rattus edalexandrinus. Il numero diploide osservato è sempre stato2n=38 e non è emersa nessuna differenza morfologica tra i cariogrammi delle varie popolazioni.

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This research was supported by the Gruppo di Studio per le popolazioni insulari del C.N.R..     

Biosynthesis of animal and plant bufadienolides. Parallel experiments with pregn-5-en-3-ß-ol-20-one-20-14C inScilla maritima andBufo paracnemis

Zusammenfassung Pregnenolon-20-¹⁴C wird von roten Meerzwiebeln als Vorstufe für herzwirksame Glykoside verwendet, dagegen kannBufo paracnemis diese Produkte, subkutan appliziert, nicht in die üblichen Krötengifte überführen.     

Epigenetic inactivation of SFRP genes allows constitutive WNT signaling in colorectal cancer

Aberrant WNT pathway signaling is an early progression event in 90% of colorectal cancers. It occurs through mutations mainly of APC and less often of CTNNB1 (encoding beta-catenin) or AXIN2 (encoding axin-2, also known as conductin). These mutations allow ligand-independent WNT signaling that culminates in abnormal accumulation of free beta-catenin in the nucleus. We previously identified frequent promoter hypermethylation and gene silencing of the genes encoding secreted frizzled-related proteins (SFRPs) in colorectal cancer. SFRPs possess a domain similar to one in the WNT-receptor frizzled proteins and can inhibit WNT receptor binding to downregulate pathway signaling during development. Here we show that restoration of SFRP function in colorectal cancer cells attenuates WNT signaling even in the presence of downstream mutations. We also show that the epigenetic loss of SFRP function occurs early in colorectal cancer progression and may thus provide constitutive WNT signaling that is required to complement downstream mutations in the evolution of colorectal cancer.     

Historical review and redescription of three poorly known species of the catfish genus Trichomycterus from south-eastern Brazil (Siluriformes: Trichomycteridae)

ABSTRACT

This study is primarily directed to the most poorly known species of the genus Trichomycterus, comprising five nominal species (T. florensis, T. immaculatus, T. nigricans, T. paquequerensis and T. santaeritae) endemic to south-eastern Brazil. One of them, T. nigricans, is the type species of the genus, involved in taxonomic problems for over 150 years. A detailed historical review, accompanied by examination of type specimens and recent collections, revealed that the correct type locality of T. nigricans is in the vicinity of Rio de Janeiro, not Santa Catarina as commonly appears in the literature; specimens previously misidentified as T. nigricans from Santa Catarina belong to a possibly undescribed species of the genus Cambeva; T. paquequerensis is a synonym of T. immaculatus, and T. florensis is a synonym of T. santaeritae; and the hypothesis that T. santaeritae is closely related to the Amazon Sarcoglanidinae is refuted. The three valid species are redescribed. These species are members of a clade also including T. caipora that is highly supported by molecular data, diagnosed by a pronounced posterior maxillary process and caudal fin emarginate at least in larger specimens. A subclade comprising T. caipora, T. nigricans and T. santaeritae is diagnosed by a long maxilla and a bifid anterior extremity of hypobranchial 3.     

Ru2 and Ru encode mouse orthologs of the genes mutated in human Hermansky-Pudlak syndrome types 5 and 6

Hermansky-Pudlak syndrome (HPS) is a genetically heterogeneous disease involving abnormalities of melanosomes, platelet dense granules and lysosomes. Here we have used positional candidate and transgenic rescue approaches to identify the genes mutated in ruby-eye 2 and ruby-eye mice (ru2 and ru, respectively), two 'mimic' mouse models of HPS. We also show that these genes are orthologs of the genes mutated in individuals with HPS types 5 and 6, respectively, and that their protein products directly interact. Both genes are previously unknown and are found only in higher eukaryotes, and together represent a new class of genes that have evolved in higher organisms to govern the synthesis of highly specialized lysosome-related organelles.     

Standardization of "exchange" techniques to measure estradiol receptors in extracts exposed to biospecific adsorbants]

The measurement of the binding of steroid hormone receptors to biospecific adsorbants requires the development of "exchange" techniques. Two types of techniques based on the principle of differential dissociation were standardized: solid phase exchange with hydroxylapatite and liquid phase exchange with adsorption of the ligand to charcoal dextran. In both cases, binding of oestradiol to its receptor was measured in calf uterine cytosol extracts. Results obtained by both techniques were comparable. The half-times of the oestradiol-receptor complex dissociation determined from exchange kinetics are on the same order as those obtained by direct methods used in previous studies.     

Genome sequencing and analysis of Aspergillus oryzae

The genome of Aspergillus oryzae, a fungus important for the production of traditional fermented foods and beverages in Japan, has been sequenced. The ability to secrete large amounts of proteins and the development of a transformation system have facilitated the use of A. oryzae in modern biotechnology. Although both A. oryzae and Aspergillus flavus belong to the section Flavi of the subgenus Circumdati of Aspergillus, A. oryzae, unlike A. flavus, does not produce aflatoxin, and its long history of use in the food industry has proved its safety. Here we show that the 37-megabase (Mb) genome of A. oryzae contains 12,074 genes and is expanded by 7-9 Mb in comparison with the genomes of Aspergillus nidulans and Aspergillus fumigatus. Comparison of the three aspergilli species revealed the presence of syntenic blocks and A. oryzae-specific blocks (lacking synteny with A. nidulans and A. fumigatus) in a mosaic manner throughout the genome of A. oryzae. The blocks of A. oryzae-specific sequence are enriched for genes involved in metabolism, particularly those for the synthesis of secondary metabolites. Specific expansion of genes for secretory hydrolytic enzymes, amino acid metabolism and amino acid/sugar uptake transporters supports the idea that A. oryzae is an ideal microorganism for fermentation.     

The development of a protoplanetary disk from its natal envelope

Class 0 protostars, the youngest type of young stellar objects, show many signs of rapid development from their initial, spheroidal configurations, and therefore are studied intensively for details of the formation of protoplanetary disks within protostellar envelopes. At millimetre wavelengths, kinematic signatures of collapse have been observed in several such protostars, through observations of molecular lines that probe their outer envelopes. It has been suggested that one or more components of the proto-multiple system NGC 1333-IRAS 4 (refs 1, 2) may display signs of an embedded region that is warmer and denser than the bulk of the envelope. Here we report observations that reveal details of the core on Solar System dimensions. We detect in NGC 1333-IRAS 4B a rich emission spectrum of H2O, at wavelengths 20-37 microm, which indicates an origin in extremely dense, warm gas. We can model the emission as infall from a protostellar envelope onto the surface of a deeply embedded, dense disk, and therefore see the development of a protoplanetary disk. This is the only example of mid-infrared water emission from a sample of 30 class 0 objects, perhaps arising from a favourable orientation; alternatively, this may be an early and short-lived stage in the evolution of a protoplanetary disk.     

Agonist-induced potentiation of acetylcholine sensitivity in denervated skeletal muscle

The entire surface membrane of denervated skeletal muscle is sensitive to the neuromuscular transmitter, acetylcholine (ACh), whereas in innervated muscle only the junctional area is sensitive. It has been proposed that this difference is due to a 'trophic' effect exerted by ACh in innervated muscle to keep the extrajunctional regions of the surface membrane insensitive to its depolarising action. Several studies have demonstrated an agonist-induced potentiation of ACh sensitivity, followed by desensitisation, at the endplate region of normal muscles. The potentiation has been attributed to a cooperative action of ACh on the receptors. Desensitisation of the extrajunctional regions of denervated muscles by ACh has also been described. We now provide evidence that the transmitter itself potentiates the ACh contracture and depolarisation responses of the denervated muscles of the rat in vitro and that it produces this effect by increasing the number of available ACh receptors on the surface membrane.