Octopus microvasculature: permeability to ferritin and carbon.

The permeability of Octopus microvasculature was investigated by intravascular injection of carbon and ferritin. Vessels were tight to carbon while ferritin penetrated the pericyte junction, and was found extravascularly 1-2 min after its introduction. Vesicles occurred rarely in pericytes; fenestrae were absent. The discontinuous endothelial layer did not consitute a permeability barrier. The basement membrane, although retarding the movement of ferritin, was permeable to it; carbon did not penetrate the basement membrane. Evidence indicated that ferritin, and thus similarly sized and smaller water soluble materials, traverse the pericyte junction as a result of bulk fluid flow. Comparisons are made with the convective (or junctional) and slower, diffusive (or vesicular) passage of materials known to occur across the endothelium of continuous capillaries in mammals. Previous macrophysiological determinations concerning the permeability of Octopus vessels are questioned in view of these findings. Possible reasons for some major structural differences in the microcirculatory systems of cephalopods and vertebrates are briefly discussed.     

Interferon blocks interleukin 1-induced prostaglandin release from human peripheral monocytes

We have studied the short-term effects of interleukin 1, lipopolysaccharide, and interferon on prostaglandin release from freshly isolated human peripheral monocytes. When the cells were pretreated for 8 to 9 hr with either E. coli lipopolysaccharide or recombinant interleukin 1 (beta), prostaglandin release increased. Inclusion of recombinant IFN-alpha or IFN-gamma during the pretreatment phase blocked subsequent prostaglandin release. Interferons were effective at concentrations in the range of 1 to 10 antiviral units/ml, and the inhibition was manifested within several hours after exposure to the lymphokine. Similar trends were observed by measuring thromboxane release. These data suggest antagonistic roles for interleukin 1 and interferon in the regulation of eicosanoid release from monocytes.     

Urea levels in plasma and erythrocytes of the southern fiddler skate, Trygonorhina fasciata guanerius

Plasma and erythrocyte samples from Trygonorhina fasciata guanerius were analysed for urea content. The erythrocyte urea concentration is higher than plasma urea concentration. The difference in concentration is probably due to the presence of urea normally bound to protein within the erythrocyte. Erythrocyte urea concentrations followed environmentally induced changes in plasma urea concentrations. Naturally occurring plasma urea concentrations, exceeding 500 mMolar, are some of the highest recorded for an elasmobranch.     

Overlapping deletions spanning the proximal two-thirds of the mouse t complex

Chromosome deletion complexes in model organisms serve as valuable genetic tools for the functional and physical annotation of complex genomes. Among their many roles, deletions can serve as mapping tools for simple or quantitative trait loci (QTLs), genetic reagents for regional mutagenesis experiments, and, in the case of mice, models of human contiguous gene deletion syndromes. Deletions also are uniquely suited for identifying regions of the genome containing haploinsufficient or imprinted loci. Here we describe the creation of new deletions at the proximal end of mouse Chromosome (Chr) 17 by using the technique of ES cell irradiation and the extensive molecular characterization of these and previously isolated deletions that, in total, cover much of the mouse t complex. The deletions are arranged in five overlapping complexes that collectively span about 25 Mbp. Furthermore, we have integrated each of the deletion complexes with physical data from public and private mouse genome sequences, and our own genetic data, to resolve some discrepancies. These deletions will be useful for characterizing several phenomena related to the t complex and t haplotypes, including transmission ratio distortion, male infertility, and the collection of t haplotype embryonic lethal mutations. The deletions will also be useful for mapping other loci of interest on proximal Chr 17, including T-associated sex reversal ( Tas) and head-tilt ( het). The new deletions have thus far been used to localize the recently identified t haplolethal ( Thl1) locus to an approximately 1.3-Mbp interval.     

Rheological properties of cross-linked hyaluronan-gelatin hydrogels for tissue engineering

Hydrogels that mimic the natural extracellular matrix (ECM) are used in three-dimensional cell culture, cell therapy, and tissue engineering. A semi-synthetic ECM based on cross-linked hyaluronana offers experimental control of both composition and gel stiffness. The mechanical properties of the ECM in part determine the ultimate cell phenotype. We now describe a rheological study of synthetic ECM hydrogels with storage shear moduli that span three orders of magnitude, from 11 to 3 500 Pa, a range important for engineering of soft tissues. The concentration of the chemically modified HA and the cross-linking density were the main determinants of gel stiffness. Increase in the ratio of thiol-modified gelatin reduced gel stiffness by diluting the effective concentration of the HA component.