We have previously identified megdkaryocyte stimulating factor (MSF) gene expression by synovial fibroblasts as the origin of lubricin in the synovial cavity. Lubricin is a mucinous glycoprotein responsible for the boundary lubrication of articular cartilage. MSF has a significant homology to vitronectin and is composed of 12 exons. RNA was purified from human synovial fibroblasts and articular chondrocytes grown in vitro from tissue explants obtained from subjects without degenerative joint disease. RT-PCR was used with multiple complimentary primer pairs spanning the central mucin expressing exon 6 of the MSF gene and individual exons on both the N-and C-terminal sides of exon 6. Exons 2, 4 and 5 appear to be variably expressed by synovial fibroblasts and articular chondrocytes. Lubricating mucin, in the form of MSF, is expressed by both chondrocytes and synovial fibroblasts in vitro.Both lubricin and superficial zone protein (SZP), a related proteoglycan, share a similar primary structure but could differ in posttranslational modifications with 0-linked oligosaccharides which are predominant in lubricin and with limited amounts chondroitin and keratan sulfate found in SZP. Since most of the MSF exons are involved in the expression of lubricating mucin. a strong homology to vitronectin persists. It is therefore appropriate to consider that both SZP and lubricin occupy a new class of biomolecules termed tvihonectins. Screening of a human genome bacterial artificial chromsoine (BAC) library with a cDN A primer pair complimentary for exon 6 identified two clones. Both clones were complimentary for chromosome lq25 by in situ hybridization. This same locus was previously implicated in camptodactyl-arthropathy-pericarditis syndrome (CAP) by genetic mapping. It is hypothesized that CAP, a large joint arthropathy, may be associated with ineffective boundary lubrication provided by synovial fluid. 0

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Resonance Raman spectra of the gram-negative organism, Escherichia coli, have been obtained with 222.5-, 230.6-, and 251.0-nm excitation, and the results have been compared with those reported earlier for 242.4-nm excitation. Major changes in bacterial spectra have been observed with changes in exciting wavelength. The origins of the major peaks in each spectrum have been explained primarily in terms of contributions of nucleic acid bases and aromatic amino acids. As an aid in making assignments, spectra of aromatic amino acids, nucleosides, and mixtures of the two have been obtained at each wavelength used to excite bacterial spectra. Background fluorescence has been observed to be negligible below 251 nm. Selective excitation of bacterial nucleic acid and protein components has been done with ease. Results suggest that an extension of the exciting wavelength range to 190–220 nm will allow the selective excitation of additional cell components.

Ultraviolet-excited (242 nm) resonance Raman spectra have been obtained for the first time for five types of bacteria: Escherichia coli, Pseudomonas fluorescens, Staphylococcus epidermidis, Bacillus subtilis, and Enterobacter cloacae. Detailed, highly reproducible spectra show substantial differences in both the intensities and the energies of peaks, which suggests that such spectra provide unique “fingerprints” reflecting the unique combinations of chemotaxonomic markers present in each type of organism. Many of the spectral features excited by 242-nm radiation probably arise from cellular RNA, DNA, and the amino acids tyrosine and tryptophan. Background fluorescence has been shown to be negligible.

The intrinsic steady-state fluorescence and fluorescence decay of Staphylococcus epidermidis, Pseudomonas fluorescens, Enterobacter cloacae, Escherichia coli, and Bacillus subtilis have been observed. Excitation spectra were obtained while emission at 430, 455, 487 and 514 nm was being monitored. Emission spectra were obtained with the use of excitation wavelengths of 340, 365, 405, 430 and 460 nm. Fluorescence lifetimes were measured at 430, 487, and 514 nm while selective excitation was caused at 340, 405, and 430 nm. The complex nature of the excitation and emission spectra reflects the presence of a number of different fluorophores. Attempts have been made to describe portions of the bacterial fluorescence in terms of the measured fluorescence properties including lifetimes of molecular components known for their widespread occurrence in bacteria and their relatively high quantum yields. Candidate fluorophores which have been considered include the pteridines, the structurally related flavins, and the pyridine coenzymes. The observation that characteristic sets of lifetimes have been obtained for each organism suggests that measurements of fluorescence lifetimes may be helpful in the rapid characterization of bacteria. Results are especially definitive in cases such as Pseudomonas fluorescens, where one marker fluorophore, a pteridine, is produced in large amounts.

We report the cloning of a 3656-bp cDNA encoding a putative human very low density lipoprotein (VLDL)/apolipoprotein E (ApoE) receptor. The gene encoding this protein was mapped to chromosome 9pter-p23. Northern analysis of human RNA identified cognate mRNAs of 6.0 and 3.8 kb with most abundant expression in heart and skeletal muscle, followed by kidney, placenta, pancreas, and brain. The pattern of expression generally paralleled that of lipoprotein lipase mRNA but differed from that of the low density lipoprotein (LDL) receptor and the low density lipoprotein receptor-related protein/alpha 2-macroglobulin receptor (LRP), which are members of the same gene family. VLDL/ApoE receptor message was not detected in liver, whereas mRNAs for both LDL receptor and LRP were found in hepatic tissue. In mouse 3T3-L1 cells, VLDL/ApoE receptor mRNA was induced during the transformation of the cells into adipocytes. Expression was also detected in human choriocarcinoma cells, suggesting that at least part of the expression observed in placenta may be in trophoblasts, cells which would be exposed to maternal blood. Expression in brain may be related to high levels of ApoE expression in that organ, an observation of potential relevance to the recently hypothesized role for ApoE in late onset Alzheimer disease. Our results suggest that the putative VLDL/ApoE receptor could play a role in the uptake of triglyceride-rich lipoprotein particles by specific organs including striated and cardiac muscle and adipose tissue and in the transport of maternal lipids across the placenta. The findings presented here, together with recent observations from other laboratories, bring up the possibility that a single gene, the VLDL/ApoE receptor, may play a role in the pathogenesis of certain forms of atherosclerosis, Alzheimer disease, and obesity.