Role of tyrosine M210 in the initial charge separation of reaction centers of Rhodobacter sphaeroides

Femtosecond spectroscopy was used in combination with site-directed mutagenesis to study the influence of tyrosine M210 (YM210) on the primary electron transfer in the reaction center of Rhodobacter sphaeroides. The exchange of YM210 to phenylalanine caused the time constant of primary electron transfer to increase from 3.5 +/- 0.4 ps to 16 +/- 6 ps while the exchange to leucine increased the time constant even more to 22 +/- 8 ps. The results suggest that tyrosine M210 is important for the fast rate of the primary electron transfer.     

Computer-assisted image analysis of the distributions of peptidergic terminals in the central nucleus of the amygdala: A preliminary study

When viewed under dark-field illumination, peptidergic terminals in sections stained by the Sternberger PAP immunocytochemical method are seen as individual points of light. Under high magnification, the degree of brightness of various areas of immunoreactive terminals is seen to be a function of the density of terminals in these areas. By analyzying the relative brightness of the immunostained central nucleus of the amygdala (CNA) with an EyeCom II PDP-$\text{11}\text{34}$ image analysis system, we have obtained a relative evaluation of the density distribution of neurotensin (NT)-, substance P (SP), VIP-, angiotensin II (AII), m-enkephalin (m-ENK) and somatostatin (SS)-immunoreactive terminals in terms of normal morphology and following a brain lesion. The EyeCom II system divides the presented image into 307200 picture elements (pixels) and assigns one of 256 grey values to the average brightness with each pixel. We have aggregated the grey level frequencies into 5 levels where level 1 corresponds to the highest terminal density and level 5 to the lowest density. At level 1, only NT- and VIP-immunoreactive terminals occupy a significant percentage of the cross-sectional area of the CNA (20%). About 15% of the area of the CNA has VIP terminals with level 5 density. The distributions of the top 20% of the terminal density range of NT, SP, AII and VIP support a classical medial/lateral division of the nucleus. The distribution of the same range of SS- and ENK terminals suggests a dorsoventral division of the CNA. A preliminary study indicates that comparison of grey level frequency histograms generated by image analysis from homologous lesioned and unlesioned sections of the CNA can yield useful information regarding post-lesion changes in the distribution of immunoreactive terminals.     

Nucleotide sequence of an exceptionally long 5.8S ribosomal RNA from Crithidia fasciculata.

In Crithidia fasciculata, a trypanosomatid protozoan, the large ribosomal subunit contains five small RNA species (e, f, g, i, j) in addition to 5S rRNA [Gray, M.W. (1981) Mol. Cell. Biol. 1, 347-357]. The complete primary sequence of species i is shown here to be pAACGUGUmCGCGAUGGAUGACUUGGCUUCCUAUCUCGUUGA ... AGAmACGCAGUAAAGUGCGAUAAGUGGUApsiCAAUUGmCAGAAUCAUUCAAUUACCGAAUCUUUGAACGAAACGG ... CGCAUGGGAGAAGCUCUUUUGAGUCAUCCCCGUGCAUGCCAUAUUCUCCAmGUGUCGAA(C)OH. This sequence establishes that species i is a 5.8S rRNA, despite its exceptional length (171-172 nucleotides). The extra nucleotides in C. fasciculata 5.8S rRNA are located in a region whose primary sequence and length are highly variable among 5.8S rRNAs, but which is capable of forming a stable hairpin loop structure (the "G+C-rich hairpin"). The sequence of C. fasciculata 5.8S rRNA is no more closely related to that of another protozoan, Acanthamoeba castellanii, than it is to representative 5.8S rRNA sequences from the other eukaryotic kingdoms, emphasizing the deep phylogenetic divisions that seem to exist within the Kingdom Protista.     

Microtubules,dendritic spines and spine apparatuses

Summary Using techniques for enhanced microtubular preservation, including albumin pretreatment (Gray, 1975), occipital cortex of rats was studied electron microscopically at various ages of development. A close structural relationship was seen between microtubules, sacs of SER and the postsynaptic thickening in primordial spines and with the dense plate material of spine apparatuses. Stereoscopic preparations in addition show a more complicated substructure than previously described for the plate. Microtubules may contribute to the formation of the plate of the spine apparatus which in turn is associated with the postsynaptic thickening of the mature spine. Possible functional correlates are discussed.Dr. L.E. Westrum is an affiliate of the CDMRC at the University of Washington and a recipient of a Burroughs-Wellcome (USA) — Wellcome Trust (U.K.) Research Travel Grant. The research was also supported in part by NIH Grants NS 09678, NS 04053 (NINCDS) and DE 04942 (NIDR), DHHS     

Marginal bundles of axoplasmic microtubules at nodes of Ranvier within muscle

Summary Using a special albumin technique, nodes of Ranvier have been examined within frog skeletal muscle, sciatic nerve and rat and frog cerebrum. Initial segments have been examined in cerebrum of frog and rat. Microtubules usually run longitudinally through these regions, but within the bare area of the intramuscular node of Ranvier, annular or helical bundles of microtubules run in a marginal band at right angles to the more centrally placed longitudinal microtubules. These nodal bare areas show a pronounced convexity and it is suggested that the annular microtubules serve to maintain this convexity during muscle contraction.Dr. Westrum is an affiliate of the CDMRC, University of Washington and a recipient of a Wellcome Trust (U.K.) Burroughs Wellcome Fund (U.SA.) Research Travel Grant. This research was also supported, in part, by NIH research Grants NS 09678 and NS 04053 from the NINCDS and DE 04942 from the NIDR, USPHS/DHEW. The authors also wish to thank Julie Barron for excellent technical assistance     

Value of 1-alpha-hydroxy vitamin D3 in treatment of primary hyperparathyroidism before parathyroidectomy.

The postoperative course of six patients with primary hyperparathyroidism and obvious radiological evidence of bone disease pretreated with 1-alpha-hydroxy vitamin D3 (1 alpha HCC) was indistinguishable from that of six patients with a similar clinical and radiological picture who were not pretreated. 1alphaHCC may increase the hypercalcaemia in some cases and cannot be recommended for the routine preparation of such patients for surgery.     

Characteristics of bacteria isolated by the anaerobic roll-tube method from cheeses and ground beef.

In this study the methods of Hungate were used to quantitate the anaerobic bacteria present in commercially available ground beef, cheddar cheese, and German hand cheese. Of 235 anaerobic roll-tube isolates from ground beef and German hand cheese, all were facultative anaerobes. Of 213 anaerobic roll-tube isolates from cheddar cheese, 91% were facultative anaerobes and 9% were obligate anaerobes. Using results of biochemical tests, 14 or the 17 obligately anaerobic isolates from cheddar cheese were Propionibacterium acnes, two were strains of Propionibacterium that could not be speciated, and one was tentatively identified as a strain of Streptococcus evolutus. Obligate anaerobes were estimated to be present in the cheddar cheese at a level of about 10(6)/g. The possible significance of these levels of P. acnes in nonsterile foods is discussed.