Oxygen transfer properties and dimensions of red blood cells in high-altitude camelids,dromedary camel and goat

Summary To estimate the advantage of the small red blood cells (RBC) of high-altitude camelids for O₂ transfer, the kinetics of O₂ uptake into and release from the RBC obtained from llama, vicuña and alpaca were investigated at 37°C with a stopped-flow technique. O₂ transfer conductance of RBC (G) was estimated from the rate of O₂ saturation change and the corresponding O₂ pressure difference between medium and hemoglobin. For comparison, O₂ kinetics for the RBC of a lowaltitude camelid (dromedary camel) and the pygmy goat were determined and previously measured values for human RBC were used. O₂ transfer of RBC was found to be strongly influenced by extracellular diffusion, except with O₂ release into dithionite solutions of sufficiently high concentration (>30 mM). TheG values measured in these standard conditions,G _st (in mmol · min^–1 · Torr^–1 · (ml RBC)^–1) were: high-altitude camelids, 0.58 (averaged for llama, alpaca and vicuña since there were no significant interspecific differences); camel 0.42; goat, 0.42; man, 0.39. The differences can in part be attributed to expected effects of the size and shape of the RBC (volume, surface area, mean thickness), as well as to the intracellular O₂ diffusivity which depends on the concentration of cellular hemoglobin. The highG _st of RBC of highaltitude camelids may be considered to enhance O₂ transfer in lungs and tissues. But the O₂ transfer conductance of blood, , equal toG _st multiplied by hematocrit (in mmol · min^–1 · Torr^–1 · (ml blood)^–1), was only slightly higher as compared to other species: 0.20 (llama, alpaca, vicuña), 0.14 (camel), 0.18 (goat), 0.17 (man).Abbreviations DPG 2,3-diphosphoglycerate - G conductance - Hb hemoglobin - RBC red blood cells - percent saturation of hemoglobin     

Isolation and characterization of the nuclear gene encoding the Rieske iron-sulfur protein (RIP1) from Saccharomyces cerevisiae

The nuclear gene encoding the Rieske iron-sulfur protein of the cytochrome bc1 complex of the mitochondrial respiratory chain has been isolated and characterized from Saccharomyces cerevisiae. We used a segment of the iron-sulfur protein gene from Neurospora crassa (Harnisch, U., Weiss, H., and Sebald, W. (1985) Eur. J. Biochem. 149, 95-99) to detect the yeast gene by Southern analysis. Five different but overlapping clones were then isolated by probing a yeast genomic library carried on YEp 13 by colony lift hybridization. Several approaches confirmed that the isolated DNA contained the gene for the Rieske iron-sulfur protein. The yeast gene, which contains no introns, can be expressed in Escherichia coli. A 900-base pair HindIII-EcoRI fragment was subcloned into pUC19 and directed the synthesis of immunodetectable protein. The gene was also identified by disruption of its chromosomal copy by homologous integration. A 400 base pair PstI-EcoRI fragment cloned adjacent to a HIS3 marker in pUC18 was used as an integrating vector. HIS+ transformants were obtained which were unable to grow on the nonfermentable carbon source glycerol. Southern analysis of the respiration deficient (gly-) strains confirmed that the chromosomal copy of the gene was disrupted, and immunoblots of extracts of the transformants indicated a lack of iron-sulfur protein. A respiration-deficient integrant was transformed to GLY+ by a 2-kilobase pair HindIII-BglII fragment, including a complete copy of the gene, carried on a multicopy episomal vector. Immunoblots with monoclonal antibodies to the iron-sulfur protein indicated overproduction of the protein in the complemented strain and revealed expression of approximately equal amounts of mature iron-sulfur protein and of a protein approximately 3 kDa larger than the mature protein in the complemented strain. A 1.2-kilobase pair segment of DNA from the clone which complemented the disrupted strains was sequenced and found to contain an open reading frame of 645 nucleotides, capable of encoding a 21,946-dalton protein. The gene is flanked by consensus signal sequences for initiation and termination which are common in yeast and is preceded by a possible upstream activating sequence. Amino acid sequence analysis of the amino-terminal end of the mature iron-sulfur protein agreed exactly with that predicted by the nucleotide sequence starting at Lys-31.(ABSTRACT TRUNCATED AT 400 WORDS)     

Restriction fragment length polymorphisms in dairy and beef cattle at the growth hormone and prolactin loci

Two bovine populations, a Holstein-Friesian dairy stock and a synthetic (Baladi X Hereford X Simmental X Charolais) beef stock, were screened for restriction fragment length polymorphisms (RFLPs) at the growth hormone and prolactin genes. Most RFLPs at the growth hormone gene are apparently the consequence of an insertion/deletion event which was localized to a region downstream of the structural gene. The restriction map for the genomic region including the growth hormone gene was extended. Two HindIII RFLPs at the growth hormone locus, as well as several RFLPs at the prolactin gene, seemed to be the consequence of a series of point mutations. The results are discussed in terms of the possibility that minor genomic variability underlies quantitative genetic variation.     

Expression of neuronal acetylcholine receptor polypeptidesin vitro

1. Translation of poly(A) RNA extracted from the nervous tissue of locusts in a reticulocyte lysate system led to polypeptides with a broad spectrum of molecular weights. 2. Using anti-locust acetylcholine receptor (AChR) antisera, polypeptides with a molecular weight of about 50,000 were immunoprecipitated. These peptides comprised about 0.3% of the total translation products. 3. Cotranslational incubation with pancreatic rough microsomes resulted in a glycosylated 60,000-dalton immunoprecipitate. 4. Density-gradient analysis of in vitro synthesized and glycosylated receptor polypeptides indicated that no assembly of subunits had taken the place under the in vitro conditions.     

Structural analysis of the phytophagous insect guilds associated with the roots of Centaurea maculosa Lam. C. diffusa Lam., and C. vallesiaca Jordan in Europe:

Summary During extensive field surveys in central and eastern Europe, 21 herbivorous root insect species were found on Centaurea maculosa ssp. rhenana Boreau, 12 species on C. diffusa Lam. and 11 species on C. vallesiaca Jordan, representing 12 families in 4 orders. The large geographic distribution (species-area function), the high number of Centaurea spp. present (host speciation rate), and the high apparency of the rosettes and the rich food resources offered by the roots during winter, together with their poor accessibility, correlate with the high number of specialist feeders associated with the roots of C. maculosa and C. diffusa. The members of the taxonomically diverse root entomofauna exploit specific structures of the tap root (food niches). Interspecific competition among members of food niches, as well as species-specific responses to different phenological stages (for oviposition) and tissues (for larval development) are thought to be responsible for the high predictability in guild structure. The relatively low levels of host plant attack (two thirds of the roots were unattacked) and the fact that food niches remained unoccupied in most of the regions suggest, however, that the majority of the studied guilds do not represent equilibrium assemblages. Ecological (different habitats), climatic (transitional zone) and historical (ancient pre-Pleistocene communities) factors could account for the highest values of species diversity, infestation levels, species packing and food niche utilization, which are found on C. maculosa in E. Austria/NW. Hungary, compared to other regions. A positive correlation between species packing (number of root-feeding species per population) and infestation rates (percent of roots attacked) was only found for the more stable, semi-natural habitats. A comparative analysis of the regional root insect guilds of C. maculosa with corresponding data for the phytophagous insects associated with the flower heads revealed distinct taxonomical differences, but a high degree of numerical and structural similarity. The different geographical regions are similarly ranked for host plant attack, herbivore pressure, average species packing and level of food niche utilization.     

The murine interleukin-4 receptor: molecular cloning and characterization of secreted and membrane bound forms

Receptors for interleukin-4 (IL-4) are expressed at low levels on a wide variety of primary cells and cultured cell lines. Fluorescence-activated sorting of CTLL-2 cells resulted in the isolation of a subclone, CTLL 19.4, which expressed 10(6) IL-4 receptors per cell. These cells were used for the purification of IL-4 receptor protein and to prepare a hybrid-subtracted cDNA probe for isolation of cDNA clones. Three classes of IL-4 receptor cDNA were identified. The first encoded a 140 kd membrane bound IL-4 receptor containing extracellular, transmembrane, and cytoplasmic domains. The second class lacked the cytoplasmic region, and the third encoded a secreted form of the receptor. All cDNA clones expressed in COS-7 cells had IL-4 binding properties comparable to the native IL-4 receptor. The soluble form of the IL-4 receptor blocked the ability of IL-4 to induce CTLL cell proliferation and may represent a regulatory molecule specific for IL-4-dependent immune responses.     

TheRT1.G locus in the rat encodes a Qa/TL-like antigen

A new antigenic system in the rat homologous to theQa/TL antigen system in the mouse has been characterized. It was detected by antibodies raised in donor-recipient combinations that were matched for theRT1. A, B, D, E loci in the major histocompatibility complex (MHC): (R11×BN)F₁ anti-BN.1L(LEW), (R18×BN)F₁ anti-BN.1L, and BN.1LV1(F344) anti-BN.1L. Absorption analyses using these antisera and a variety of inbred, congenic and recombinant strains identified three alleles,RT1.G ^a ,G ^b ,G ^c , of whichG ^c is a null allele. The strain distribution of these alleles was determined, using 37 strains of rats representative of all of the prototypic haplotypes and a number of congenic and recombinant strains. The use of the congenic and recombinant strains showed that theRT1.G locus was linked to the MHC and that the most probable gene order wasA-E-G. Testcross analysis showed that the map distance betweenA andG was 1.4 cM(4/285 recombinants). The RT1.G antigen has a heavy chain ofM _r 46 000 and is present on both T and B cells.     

Measurement of adrenolutin as an oxidation product of catecholamines in plasma

Using the reverse phase high-performance liquid chromatography (HPLC) with mobile phases composed of simple acids, we have developed an assay technique for the measurement of adrenolutin, one of the oxidation products of catecholamines, in rat plasma. Ion-pairing chromatography permits the separation and quantitation of plasma adrenolutin (M) in a linear manner. Sample preparation involved the precipitation of plasma proteins with perchloric acid and it is easier to handle a large number of samples at a time. However, we were unable to demonstrate the presence of adrenochrome, another oxidation product of catecholamines, in plasma since adrenochrome was rapidly destroyed in acid as well as in blood and was quickly changed, into adrenolutin. Adrenolutin peak in HPLC was confirmed by 1) the retention time; 2) co-injection of adrenolutin and; 3) the appearance of ³H-adrenolutin after injection of ³H-norepinephrine. Administration of different catecholamines as well as adrenochrome and adrenolutin in rats also increased the level of adrenolutin in plasma. Adrenolutin was found to be present in plasma in other species including dog, rabbit and pig. High level of adrenolutin, which may represent total concentration of aminolutin in plasma, suggests the presence of an efficient mechanism for the oxidation of catecholamines under in vivo conditions.     

Structures of acidic O-linked polylactosaminoglycans on human skim milk mucins

O-Linked glycans were isolated from human skim milk mucins or mucin-derived high-molecular weight glycopeptides and fractionated by anion exchange chromatography into neutral and acidic alditols. Major oligosaccharides contained in the acidic fraction were purified by high performance liquid chromatography and structurally characterized by a combination of fast atom bombardment mass spectrometry, methylation analysis and 500 MHz 1H-nuclear magnetic resonance spectroscopy. The structural aspects exhibited by these major species in the acidic fraction resemble those established previously for the neutral oligosaccharides from human skim milk mucins: 1) the size of the alditols varies from tri- to decasaccharides, 2) the core structure is of the ubiquitous type 2, 3) the backbone sequences are of the poly-N-acetyllactosamine type with a particular preponderance of linearly extended GlcNAc beta(1-3)Gal (major) or GlcNAc beta(1-6)Gal units (minor).     

The phylogenic position of Peptococcus niger based on 16S rRNA sequence studies

A 1330 base-pair fragment of a 16S rRNA gene has been amplified, cloned and sequenced. Comparison to other 16S rRNA sequences of eubacteria showed that P. niger represents a deep branch within the subdivision "Gram-positive with Gram-negative cell walls". It is not related to peptostreptococci, representatives of this genus studied so far are more closely related to clostridia.