The structure and evolution of the spider monkey delta-globin gene

We have isolated the delta-globin gene of the New-World spider monkey, Ateles geoffroyi, and compared its nucleotide sequence with those of other primate delta- and beta-globin genes. Among primate delta-globin genes, the rate of nonsynonymous substitutions is much less than the rate of synonymous substitutions. This suggests that primate delta- globin genes may remain under evolutionary conservation, perhaps because hemoglobin A2 has an as yet unknown physiological importance.      

Biochemical pathways in prokaryotes can be traced backward through evolutionary time

For the first time, a credible prokaryotic phylogenetic tree is being assembled by Woese and others using quantitative sequence analysis of oligonucleotides in the highly conservative rRNA. This provides an evolutionary scale against which the evolutionary steps that led to the arrangement and regulation of contemporary biochemical pathways can be measured. This paper presents an emerging evolutionary picture of aromatic amino acid biosynthesis within a large superfamily assemblage of prokaryotes that is sufficiently developed to illustrate a new perspective that will be applicable to many other biochemical pathways.      

DNA typing of HLA-DR antigens in systemic lupus erythematosus

HLA-DR typing is technically difficult in systemic lupus erythematosus (SLE), where patients have low numbers of peripheral B cells, often of poor viability and weak in antigenic expression. In this series, one third of SLE patients could not be HLA-DR typed by serological techniques, highlighting the potential for systematic bias in DR antigen assignment in studies of HLA and SLE. This potential bias was examined by comparing serological DR results with DNA-DR typing, achieved by examining Taq I fragments of DR, DQ, and DQ which permitted unequivocal DR phenotyping of all patients, including the 35% for whom conventional DR typing was technically impossible. This showed the success of serological DR antigen assignment was indeed nonrandom, with HLA-DR2 and -DR3 significantly more readily identifiable than DR5 and DRw13. Our study suggests that technical problems may well have contributed to conflicting reports regarding the association of DR2 or DR3 with SLE. Here, DNA-DR phenotyping showed HLA-DR3 is significantly (P<.05) associated with an increased risk for SLE (54% in 46 patients, 36% in 134 controls) and HLA-DR2 is not.     

Assembly of cyanobacterial and higher plant ribulose bisphosphate carboxylase subunits into functional homologous and heterologous enzyme molecules in Escherichia coli

The genes for the large (rbcL) and small (rbcS) subunits of ribulose-1,5 bisphosphate carboxylase-oxygenase (RuBPCase) from the cyanobacterium Synechococcus PCC 6301, and the rbcS gene of wheat, have been expressed in Escherichia coli in order to study homologous and heterologous enzyme assembly. Synechococcus L subunits expressed in E. coli in the absence of S subunits assemble into oligomeric structures without detectable enzyme activity. Co-expression of L and S subunits, achieved after infection with an M13 recombinant phage containing the rbcS gene, restores enzyme activity, thus demonstrating the essential role of S in the formation of an active RuBPCase. The S subunit, however, is neither required for the solubility nor for the assembly of the L subunits into oligomeric forms. The specific activity of the homologous Synechococcus RuBPCase can be modulated by changing the intracellular pool size of S by phage infection. Heterologous assembly between L subunits of Synechococcus and S subunits of wheat can be demonstrated and results in a functional enzyme. The hybrid RuBPCase has approximately 10% of the activity of the homologous Synechococcus enzyme.     

Blocking of human T lymphocyte functions by anti-Leu-2 and anti-Leu-3 antibodies: differential inhibition of proliferation and suppression

We have shown previously that monoclonal antibodies to the Leu-2 and Leu-3 T cell antigens block the response of their respective subsets in allogeneic MLR. The present study was an effort to explore the mechanism of inhibition and to determine if anti-Leu-2 and anti-Leu-3 antibodies affect the responses to stimuli in addition to alloantigens. Our results indicate that antibodies to Leu-2 and Leu-3 have profound inhibitory effects on proliferation by their respective T cell subsets responding to a variety of stimuli, including specific soluble antigens and alloantigen. This effect was characterized by the following features: a) For optimal inhibition of proliferation, antibody must be present at the onset of antigenic stimulation. b) Inhibition is augmented by increasing the concentration of antibody or decreasing the concentration of antigen. c) Fab fragments of both anti-Leu-2a and anti-Leu-3a antibodies also block proliferation. In addition to their effects on T cell proliferation, anti-Leu-3 antibody blocked T cell-dependent lg synthesis induced in MLR, and anti-Leu-2 antibody prevented the induction, in vitro, of Leu-2+3- suppressor cells of lg synthesis. Taken together, these results suggest that antibodies to antigenic determinants on the Leu-2 and Leu-3 molecules competitively block segments of these structures that bind to alloantigen or nominal antigen. On the other hand, anti-Leu-2a antibody failed to block suppression of the MLR by in vivo activated, antigen-specific Leu-2+3- suppressor cells, which suggests that the Leu-2a epitope does not transmit antigen-specific signals from these differentiated suppressor T cells.     

Spermiogenesis in Lumbricus herculeus : An Electron Microscope Study

Small pieces of the sperm sacs of Lumbricus herculeus were fixed for 4 hours in chrome-osmium, embedded in methacrylate, sectioned with a Porter-Blum microtome, and studied with a R.C.A. EMU-2C electron microscope. Each spermatid of a group developing synchronously is attached by a cytoplasmic strand to a common nutrient protoplasmic mass. This mass contains mitochondria and yolk bodies but is anucleate. The proximal centriole, that is, the centriole nearer the nucleus, is at first associated with a small peg which becomes firmly attached to the nuclear membrane. Later these two bodies become separated during the development of the middle-piece which is differentiated in the usual manner from a nebenkern formed by the fusion of 6 or 7 mitochondria. The acrosome develops in relation to the dictyosome (Golgi body), itself composed of 8 or more individual flattened sacs and situated in the cytoplasm opposite the point of attachment of the spermatid to the nutrient mass. Soon after its formation, the acrosome becomes incorporated into a cytoplasmic appendage or acrosome carrier. The carrier moves from its original position, along the lateral border of the elongating nucleus, to the distal margin of the nucleus where the acrosome is deposited. No evidence was found of a centriole located at the point of junction between nucleus and acrosome as suggested by earlier workers.     

Conformational states of ribulosebisphosphate carboxylase and their interaction with chaperonin 60.

Conformational states of ribulosebisphosphate carboxylase (Rubisco) from Rhodospirillum rubrum were examined by far-UV circular dichroism (CD), tryptophan fluorescence, and 1-anilino-naphthalenesulfonate (ANS) binding. At pH 2 and low ionic strength (I = 0.01), Rubisco adopts an unfolded, monomeric conformation (UA1 state) as judged by far-UV CD and tryptophan fluorescence. As with other acid-unfolded proteins [Goto, Y., Calciano, L. J., & Fink, A. L. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 573-577], an intermediate conformation (A1 state) is observed at pH 2 and high ionic strength. The A1 state has an alpha-helical content equivalent to 64% of that present in the native dimer (N2 state). However, fluorescence measurements indicate that the tertiary structure of the A1 state is largely disordered. A site-directed mutant, K168E, which exists as a stable monomer [Mural, R. J., Soper, T. S., Larimer, F. W., & Hartman, F. C. (1990) J. Biol. Chem. 265, 6501-6505] was used to characterize the "native" monomer (N1 state). The far-UV CD spectra of the N1 and N2 states are almost identical, indicating a similar secondary structure content. However, the tertiary structure of the N1 state is less ordered than that of the N2 state. Nevertheless, when appropriately complemented in vitro, K168E forms an active heterodimer. Upon neutralization of acid-denatured Rubisco or dilution of guanidine hydrochloride-denatured Rubisco, unstable folding intermediates (I1 state) are rapidly formed. At concentrations at or below the "critical aggregation concentration" (CAC), the I1 state reverts spontaneously but slowly to the native states with high yield (greater than 65%). The CAC is temperature-dependent. At concentrations above the CAC, the I1 and the A1 states undergo irreversible aggregation. The commitment to aggregation is rapid [ef. Goldberg, M. E., Rudolph, R., & Jaenicke, R. (1991) Biochemistry 30, 2790-2797] and proceeds until the concentration of folding intermediate(s) has fallen to the CAC. In the presence of a molar excess of chaperonin 60 oligomers, the I1 state forms a stable binary complex. No stable binary complex between chaperonin 60 and the N1 state could be detected. Formation of the chaperonin 60-I1 binary complex arrests the spontaneous folding process. The I1 state becomes resistant to interaction with chaperonin 60 with kinetics indistinguishable from those associated with the appearance of the native states. In vitro complementation analysis indicated that the product of the chaperonin-facilitated process is monomeric.(ABSTRACT TRUNCATED AT 400 WORDS)     

The evolutionary history of the amylase multigene family in Drosophila pseudoobscura

In Drosophila pseudoobscura, the amylase (Amy) multigene family is contained within a series of inversions, or gene arrangements, on the third chromosome. The Standard (ST), Santa Cruz (SC), and Tree Line (TL) inversions are central to the phylogeny of arrangements, and have clusters of other arrangements derived from them. The gene arrangements belonging to each of these three clusters have a characteristic number of Amy genes, ranging from three in ST to two in SC to one in TL. This distribution pattern can reflect a history of either duplications or deletions, although the data available in the past did not permit a decision between these alternatives. We provide unambiguous evidence that three Amy genes were present before the divergence of the ST, SC, and TL arrangements. Thus, the current status of the Amy multigene family is the result of deletions in the TL and SC arrangements, which created three new pseudogenes: TL Amy2-psi, TL Amy3-psi, and SC Amy3- psi. Analysis of pseudogene sequences revealed that, in the SC and ST arrangements, pseudogene evolution has been retarded, most likely due to the homogenization effect of gene conversion. Finally, by determining the original copy number, we have reconstructed the evolutionary history of the Amy multigene family and linked it with the evolution of the central gene arrangements.      

USE OF SENSORY EVALUATION FOR MEASURING DEODORIZING EFFECTS OF AN AIR CONDITIONER

The application of sensory methodology for measuring deodorizing effect of an air conditioner equipped with electric plasma was introduced. Deodorizing effect was measured using chemical and sensory methods at different time (0, 30 and 60 min) and mode (control, blowing and cooling) of an air conditioner. Smoke from a roll of cigarette in a closed room was used as a source of odor and the concentrations of acetic acid and ammonia were measured as odorous chemical components. As one of the sensory methods triangle test was used and as a first step to obtain deodorizing effects by triangle test, the threshold of each panelist was obtained as the log dilution ratio of odor concentration at which the difference from odorless air was detected. The odor concentration at each time and mode was calculated using the threshold of the panel and the deodorizing effect was obtained on the basis of the odor concentration. In addition to a triangle test, scaling methods such as category scaling or magnitude estimation were used to measure deodorizing effect of an air conditioner. Deodorizing effects by scaling methods were calculated based on odor intensity with time at each mode. The regression analysis was done between the efficacy of deodorizing effect by sensory test and those by acetic acid and ammonia, the R² values of the regression equations for triangle test, category scale, and magnitude estimation were 0.84, 0.72 and 0.69, respectively. Deodorizing effect by triangle test explained the decrease of acetic acid and ammonia better than those by category scaling or magnitude estimation while high cost and time consuming labor involved in triangle tests reduced the merit. The results of this study demonstrated that various sensory methods could be used to measure deodorizing effect of air conditioners and further researches on fast and reliable methods are needed to establish the official procedures.