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PubMed1987

Sequence elements essential for rho-dependent transcription termination at lambda tR1.

To determine the location of DNA sequences required for the utilization of rho factor in transcription termination at the tR1 terminator of phage lambda, we constructed and analyzed a series of deletion mutants affecting several distinct regions of the cro-gene sequence. Two distinct sequence blocks, rutA and rutB, are shown to be particularly important for rho action at tR1 during in vitro transcription. They are located in the region between the sequence encoding the translation termination codon of cro mRNA and the start of tR1. Although other sequences contribute to rho action, their function can be replaced by unrelated heterologous DNA sequences encoding highly structured RNA segments, while the function of the rut sequences cannot. The lambda tR1 rut sequences encode RNA segments that contain a high proportion of cytidylate residues and that lack extensive intramolecular base pairing. Thus, the rut transcript segments are likely to be parts of the site on the nascent cro RNA that binds specifically with rho factor as an essential step in the termination process. This view is supported further by the findings (Chen, C.-Y. A., Galluppi, G. R., and Richardson, J. P. (1986) Cell 46, 1023-1028) that rho action at tR1 is specifically inhibited by DNA oligonucleotides that form hybrid helices with rut transcript segments. We also examined the effect of the auxiliary transcription factor NusA on transcription of our mutant templates and show that deletion of the boxA sequence of cro gene does not diminish the ability of NusA to reduce rho action at tR1.

Bacterial Proteins↗
PubMed1988

Characterization of the cis and trans elements essential for rat insulin II gene expression.

We have constructed 14 different linker-scanner (LS) mutants throughout the enhancer and promoter of a rat insulin II-CAT fusion gene. These LS mutants were transiently transfected into an insulin-producing (HIT) cell line and three mutants (LS-261/252, LS-102/91, LS-54/45) displayed drastically reduced levels of CAT activity. Therefore, at least three regions are essential for the in vivo expression of an insulin-CAT fusion gene. To identify the trans-acting factors which interact with this cell-specific promoter, we performed band-shifting assays with either HIT or HeLa nuclear extracts and an end-labelled insulin fragment (-100 to +49). Three binding activities were common to both extracts, and another one was unique to HIT cells. DNase I protection studies localized one binding activity to -60 to -40 bp 5' to the cap site. We show that this factor is common to both cell lines and is identical to a previously characterized transcription factor (COUP) which binds to the chicken ovalbumin upstream promoter.

Animals↗
PubMed1988

Neonatal transport: communication--the essential element.

The Bronson Methodist Hospital Neonatal Transport System (Kalamazoo, MI) has identified effective communication as a necessity when providing optimal patient care. Our experience shows that good communication comes only from good relationships between our neonatal intensive care unit (NICU) staff and each referring hospital's staff. This article describes the two educational methods used to aid these relationships: the development of site visits and the distribution of informative publications. By using these methods, our relationships with our 17 referring hospital staffs have improved, which has had a direct bearing on more effective communication during neonatal transport.

Books↗
PubMed1988

The effect of fatigue on essential element distribution in the rabbit masseter.

The rabbit masseter is composed of mainly fast fatiguable type IIB fibers which give a positive mATPase reaction at pH 9.3. To study the effect of fatigue on the distribution of some crucial elements, the masseter was stimulated electrically for 45 minutes. The contralateral muscle served as a control. Control and experimental tissues were rapidly excised, and frozen in isopentane cooled to -150 degrees C in liquid nitrogen. Sections were cut in a cryostat and prepared by freeze-drying. Water content of fatigued muscle was significantly higher than controls: 79.3% versus 77.3%. The fatigued state was verified by glycogen depletion viewed in PAS-stained sections. Ice crystal artifacts were more prominent in stimulated muscle, suggesting cytoplasmic edema and/or a change in water state. Element analysis of myofibers, using an scanning electron microscope equipped with a computer assisted energy dispersive X-ray spectrometer was performed at 15 kV for 100 seconds. Counts were recorded for Na, Mg, P, S, Cl, K and Ca (Mg and Ca counts were too low to evaluate). Counts were converted to concentrations using a gelatin element standard. The most striking finding in fatigued muscle was a decrease in K concentration (33%) and an increase in Na (100%) and Cl (75%). P and S values were slightly lower. An interpretation of these findings is made in relation to a) changes in water structure and b) conformational changes in myofibril macromolecules.

Animals↗