Fenestrated capillaries in the ventral sebaceous gland of the Djungarian hamster, Phodopus sungorus

The ventral sebaceous gland of the Djungarian hamster is a macroscopically visible organ situated in the midventral area of the abdominal wall. It consists of densely packed acini arranged in lobules with common excretory ducts. The rich vascular network of the gland is characterized by fenestrated capillaries. Fenestrated endothelium has not yet been reported as a characteristic and regular finding within sebaceous glands. Results are discussed with regard to proliferation rate of sebocytes and the demand of fluid and nutrient supply.     

Honeydew amino acids in relation to sugars and their role in the establishment of ant-attendance hierarchy in eight species of aphids feeding on tansy (Tanacetum vulgare)

Abstract. The ratio of the concentration of honeydew total amino acids to total sugars in the honeydew of eight species of aphids, all feeding on tansy, Tanacetum vulgare (L.), was determined and correlated with honeydew production and ant‐attendance. The honeydew of the five ant‐attended aphid species [Metopeurum fuscoviride (Stroyan), Trama troglodytes (v. Hayd), Aphis vandergooti (Börner), Brachycardus cardui (L.), Aphis fabae (Scopoli)] was rich in total amino acids, ranging from 12.9 to 20.8 nmol µL^?1 compared with the unattended aphid Macrosiphoniella tanacetaria (Kalt.) with only 3 nmol µL^?1. Asparagine, glutamine, glutamic acid and serine (all nonessential amino acids) were the predominant amino acids in the honeydew of all species. The total concentration of amino acids in the phloem sap of tansy was much higher (78.7 nmol µL^?1) then in the honeydew samples, and the predominant amino acids were glutamate (34.3%) and threonine (17.7%). A somewhat unexpected result was the finding that those aphid species with the highest total amino acid concentration in the honeydew always had the highest concentration of sugars. The lowest amino acid–sugar combined value was 104–28.8 nmol µL^?1 in the non ant‐attended species M. tanacetaria, and the highest value was an average of 270–89.9 nmol µL^?1 for the three most intensely attended aphid species M. fuscoviride, A. vandergooti and T. troglodytes. There is no evidence that any single amino acid or group of amino acids in the honeydew acted as an attractant for ant‐attendance in these eight aphid species. The richness of the honeydew (rate of secretion × total concentration of sugars), along with the presence of the attractant sugar melezitose, comprised the critical factors determining the extent of ant‐attendance of the aphids feeding on T. vulgare. The high total amino acid concentration in sugar‐rich honeydews can be explained by the high flow‐through of nutrients in aphids that are particularly well attended by ants.     

A new repetitive protein from Xenopus laevis skin highly homologous to pancreatic spasmolytic polypeptide

A cDNA sequence has been used to derive the precursor structure of a highly repetitive protein in Xenopus laevis skin. From the sequence of a whole family of secretory proteins can be predicted containing a classical hydrophobic signal sequence at the NH2-terminal end of the precursor. The proteins contain four domains with high homology to porcine pancreatic spasmolytic polypeptide. These four cysteine-rich, presumably physiologically active domains are separated in the molecule by a repetitive element, locating two such domains to the NH2 terminus of the precursor protein and the remaining two to the COOH-terminal end. The separating spacer consists of very unusual, precise, threonine and proline-rich repeats containing 9 residues which could be targets for extensive O-glycosylation. Additionally, processing at two pairs of basic residues is suggested to liberate two polypeptides ("spasmolysins") and "spasmolysin-glycoprotein."     

Phylogenetic distribution in the genus Mus of t-complex-specific DNA and protein markers: inferences on the origin of t-haplotypes

We have examined the phylogenetic distribution of two t-specific markers among representatives of various taxa belonging to the genus Mus. The centromeric TCP-1a marker (a testicular protein variant specific for all t-haplotypes so far studied) has also been apparently detected in several non-t representatives of the Mus IVA, Mus IVB, and probably M. cervicolor species. By contrast, a t-specific restriction- fragment-length polymorphism allele (RFLP) of the telomeric alpha- globin pseudogene DNA marker alpha-psi-4 was found only in animals belonging to the M. musculus-complex species either bearing genuine t- haplotypes or, like the M. m. bactrianus specimen studied here, likely to do so. This t-specific alpha-psi-4 RFLP allele was found to be as divergent from the RFLP alleles of the latter, non-t, taxonomical groups as it is from Mus 4A, Mus 4B, or M. spretus ones. These results suggest the presence of t-haplotypes and of t-specific markers in populations other than those belonging to the M. m. domesticus and M. m. musculus subspecies, implying a possible origin for t-haplotypes prior to the radiation of the most recent offshoot of the Mus genus (i.e., the spretus/domesticus divergence), some 1-3 Myr ago.      

Mechanisms in volume regulation in Ehrlich ascites tumor cells

The Ehrlich ascites tumor cell has been used as a model of an unspecialized mammalian cell, in an attempt to disclose the mechanisms involved in the regulation of cellular water and salt content. In hypotonic medium Ehrlich cells initially swell as nearly perfect osmometers, but subsequently recover their volume within about 10 min with an associated net loss of KCl, amino acids, taurine and cell water. The net loss of KCl takes place mainly via separate, conductive K+ and Cl- transport pathways, and the net loss of taurine through a passive leak pathway. Ca2+ and calmodulin appear to be involved in the activation of the K+ and Cl- channels, as well as the taurine leak pathway. In hypertonic medium Ehrlich cells initially shrink as osmometers, but subsequently recover their volume with an associated net uptake of KCl and water. In this case, the net uptake of KCl is the result of the activation of an electroneutral, Na+- and Cl- -dependent cotransport system with subsequent replacement of cellular Na+ by extracellular K+ via the Na+/K+ pump. In the present review we describe the ion and taurine transporting systems which have been identified in the plasma membrane of the Ehrlich ascites tumor cell. We have emphasized the selectivity of these transport pathways and their activation mechanisms. Finally, we propose a model for the activation of the conductive K+ and Cl- transport pathways in Ehrlich cells which includes Ca2+, leukotrienes, and inositol phosphate as intracellular second messengers.     

Myocardial infarction in young women--clinical analysis]

Authors studied an incidence of myocardial infarction in women, specially aged below 50 years. Infarct localisation, complications during the treatment, coronary disease risk factors and mortality were estimated. In the most young women with myocardial infarction 2-3 risk factors were found, simultaneously specially cigarette smoking--all studied women aged below 50 years smoked cigarettes. Hospital course of myocardial infarction was as a rule not complicated. Mortality in young and in all observed women was however twice higher in comparison to control group of males.     

Identification of a fibroblast growth factor-binding protein in Drosophila melanogaster.

As assessed by competitive binding and protein-crosslinking experiments, Drosophila melanogaster cells possess basic fibroblast growth factor (bFGF)-specific binding proteins that are similar to FGF receptors on vertebrate cells in molecular weight and binding affinity; these D. melanogaster cells, however, have no detectable binding proteins for acidic fibroblast growth factor (aFGF). Consistent with the presence of bFGF-specific binding proteins, D. melanogaster cells degrade bFGF but not aFGF. These results indicate the conservation of heparin-binding growth factors and receptors between vertebrates and D. melanogaster.