The origin of the Jingwei gene and the complex modular structure of its parental gene, yellow emperor, in Drosophila melanogaster

Jingwei (jgw) is the first gene found to be of sufficiently recent origin in Drosophila to offer insights into the origin of a gene. While its chimerical gene structure was partially resolved as including a retrosequence of alcohol dehydrogenase (ADH:), the structure of its non-ADH: parental gene, the donor of the N-terminal domain of jgw, is unclear. We characterized this non-ADH: parental locus, yellow emperor (ymp), by cloning it, mapping it onto the polytene chromosomes, sequencing the entire locus, and examining its expression patterns in Drosophila melanogaster. We show that ymp is located in the 96-E region; the N-terminal domain of ymp has donated the non-ADH: portion of jgw via a duplication. The similar 5' portions of the gene and its regulatory sequences give rise to similar testis-specific expression patterns in ymp and jgw in Drosophila teissieri. Furthermore, between-species comparison of ymp revealed purifying selection in the protein sequence, suggesting a functional constraint in ymp. While the structure of ymp provides clear information for the molecular origin of the new gene jgw, it unexpectedly casts a new light on the concept of genes. We found, for the first time, that the single locus of the ymp gene encompasses three major molecular mechanisms determining structure of eukaryotic genes: (1) the 5' exons of ymp are involved in an exon-shuffling event that has created the portion recruited by jgw; (2) using alternative cleavage sites and alternative splicing sites, the 3' exon groups of ymp produce two proteins with nonhomologous C-terminal domains, both exclusively in the testis; and (3) in the opposite strand of the third intron of ymp is an essential gene, musashi (msi), which encodes an RNA-binding protein. The composite gene structure of ymp manifests the complexity of the gene concept, which should be considered in genomic research, e.g., gene finding.

Group II introns designed to insert into therapeutically relevant DNA target sites in human cells

Mobile group II intron RNAs insert directly into DNA target sites and are then reverse-transcribed into genomic DNA by the associated intron-encoded protein. Target site recognition involves modifiable base-pairing interactions between the intron RNA and a >14-nucleotide region of the DNA target site, as well as fixed interactions between the protein and flanking regions. Here, we developed a highly efficient Escherichia coli genetic assay to determine detailed target site recognition rules for the Lactococcus lactis group II intron Ll.LtrB and to select introns that insert into desired target sites. Using human immunodeficiency virus-type 1 (HIV-1) proviral DNA and the human CCR5 gene as examples, we show that group II introns can be retargeted to insert efficiently into virtually any target DNA and that the retargeted introns retain activity in human cells. This work provides the practical basis for potential applications of targeted group II introns in genetic engineering, functional genomics, and gene therapy.

Reactive hall response

The zero temperature Hall constant R(H), described by reactive (nondissipative) conductivities, is analyzed within linear response theory. It is found that in a certain limit R(H) is directly related to the density dependence of the Drude weight, implying a simple picture for the change of sign of charge carriers in the vicinity of a Mott-Hubbard transition. This novel formulation is applied to the calculation of R(H) in quasi-one-dimensional and ladder prototype interacting electron systems.

[Invasion behavior of hepatocellular carcinoma cells correlates with their rheological properties]

We investigated the viscoelasticity, mechanics of adhesion to collagen I coated surfaces and mechanics of adhesin to liver sinosoidal endothelial cells(LECs) among primary culture human hepatocytes, hepatocellular carcinoma(HCC) cells as well as HCC-Inv cells, namely HCC cells capable of invading the artificial basement membrane, Matrigel. The results showed that the above-mentioned rheological properties of HCC cells differed obviously from those of normal hepatocytes. HCC-Inv cells exhibited higher viscoelastic coefficients, higher adhesion forces to collagen I coated surfaces as well as higher adhesion forces to LECs than those of normal hepatocytes and HCC cells. Immunocytochemistry showed the differences in cell morphology and cytoskeleton structure between HCC cells and HCC-Inv cells. A brief discussion was presented in relation to the changes in cell rheological properties of hepatocellular carcinoma cells and their pathological significance.

Lessons to be learned: a case study approach: ascites and elevated serum CA 125 due to a pancreatic carcinoma. A diagnostic dilemma

A 72 year-old lady with unrecognised cancer of the body of the pancreas presented with a 4-month history of progressive loss of weight and ascites. The results of laboratory investigations were either negative or within normal limits--apart from a raised serum CA 125 level; no tumour mass was detected on diagnostic imaging. She underwent exploratory laparotomy for a suspected ovarian tumour, but this proved not to be the correct diagnosis. A serum CA 19-9 level was subsequently requested and found to be significantly raised; a second contrast CT scan then showed the presence of ill-defined peri-aortic tissue. A further exploratory laparotomy was carried out in order to establish the true nature of the problem; a large pancreatic carcinoma was revealed.

ExInt: an Exon/Intron database

The Exon/Intron (ExInt) database incorporates information on the exon/intron structure of eukaryotic genes. Features in the database include: intron nucleotide sequence, amino acid sequence of the corresponding protein, position of the introns at the amino acid level and intron phase. From ExInt, we have also generated four additional databases each with ExInt entries containing predicted introns, introns experimentally defined, organelle introns or nuclear introns. ExInt is accessible through a retrieval system with pointers to GenBank. The database can be searched by keywords, locus name, NID, accession number or length of the protein. ExInt is freely accessible at http://intron.bic.nus.edu.sg/exint/exint.html

Effects of oxidative damage of membrane protein thiol groups on erythrocyte membrane viscoelasticities

In three oxidative damaging systems: the diamide-mercaptoethanol redox modification system (DM), the pyrogallol oxygen free radicals system (PG) and the hypoxanthine-xanthine oxidase oxygen free radical system (HXO), the effect of erythrocyte membrane oxidative damage on membrane viscoelasticities was investigated with micropipette aspiration method. The experimental results indicated that erythrocyte membrane oxidative damage has a great influence upon the membrane mechanical properties. The oxidative damage led to decrease of contents of membrane protein thiol radical. The scanning of SDS-PAGE presented that membrane proteins form the higher molecular weight component (HMP) by the cross-linking of membrane protein thiol radicals that might hinder the conformational change of membrane protein. This might be the reason for the increased membrane elastic modulus and viscous coefficient upon treating erythrocytes with the oxidative damaging systems. A significant negative logarithm regression relation was found between the membrane elastic modulus, mu, or viscoefficient, eta, and the contents of membrane protein thiol radicals. These experimental results suggested that thiol radicals oxidative damage reaction due to the superoxides anions (*O2-) may be an important molecular mechanism inducing changes of membrane viscoelasticities or whole cell deformability of erythrocyte under physiological and pathological oxidative stress.

Association of intron phases with conservation at splice site sequences and evolution of spliceosomal introns

How exon-intron structures of eukaryotic genes evolved under various evolutionary forces remains unknown. The phases of spliceosomal introns (the placement of introns with respect to reading frame) provide an opportunity to approach this question. When a large number of nuclear introns in protein-coding genes were analyzed, it was found that most introns were of phase 0, which keeps codons intact. We found that the phase distribution of spliceosomal introns is strongly correlated with the sequence conservation of splice signals in exons; the relatively underrepresented phase 2 introns are associated with the lowest conservation, the relatively overrepresented phase 0 introns display the highest conservation, and phase 1 introns are intermediate. Given the detrimental effect of mutations in exon sequences near splice sites as found in molecular experiments, the underrepresentation of phase 2 introns may be the result of deleterious-mutation-driven intron loss, suggesting a possible genetic mechanism for the evolution of intron-exon structures.

Origin of new genes and source for N-terminal domain of the chimerical gene, jingwei, in Drosophila

This paper deals with a general question posed by the origin of new processed chimerical genes: when a new retrosequence inserts into a new genome position, how does it become activated and acquire novel protein function by recruiting new functional domains and regulatory elements? Jingwei (jgw), a newly evolved functional gene with a chimerical structure in Drosophila, provides an opportunity to examine such questions. The source of its exon encoding C-terminal peptide has been identified as an Adh retrosequence, which extends the concept of exon shuffling from recombination to retroposition as a general molecular mechanism for the origin of a new gene. However, the origin of 5' exons remains unclear. We examined two hypotheses concerning the origin of these non-Adh-derived jgw exons: (i) these exons might originate from a unique genomic sequence that fortuitously evolved a standard intron-exon structure and regulatory sequence for jgw; (ii) these exons might be a duplicate of an unrelated previously existing gene. Genomic Southern analysis, in conjunction with construction and screening of a genomic bookshelf (sub-library), was conducted in a group of Drosophila species. The results demonstrated that there are duplicate genes containing the same structure as the recruited portion of jgw. We name this duplicate gene in Drosophila teissieri and Drosophila yakuba and its orthologous gene in Drosophila melanogaster as yellow-emperor (ymp). Thus, the 5' exons/introns originated from a previously existing gene that provided new modules with specific sub-function to create jgw.

[Investigation on the adhesive properties of different cycle hepatoma cells]

OBJECTIVE

To study the adhesive forces of HTC cells on different concentration of artificial basement membrane (collagen IV coated)and synchronous G1&S phase HTC cells on a certain concentration of artificial basement membrane.

METHODS

The adhesive forces of HTC cells were investigated by micropipette aspiration technique. The synchronous G1 and S phase cells were achieved through thymine-2-desoryriboside and cochicine sequential blockage method and double thymine-2-desoryriboside blockage method respectively.

RESULTS

HTC cells with 72.10% of G1 phase and 98.94% of S phase were achieved through thymine-2-desoryriboside and cochicine sequential blockage method and double thymine-2-desoryriboside blockage method respectively. The adhesive force of HTC cells on artificial basement membrane was in direct proportion to the concentration of collagen IV. G1 phase HTC cells had higher adhesive forces than S phase cells.

CONCLUSION

These studies suggested that the increase of basement membrane might be conducive to the chemotactic motion and adhesion of tumor cells; G1 phase cells were more capable of adhering to and getting through basement membrane than S phase cells, and reflected the differences of receptors between G1 phase cells and S phase cells.

Intron-exon structures of eukaryotic model organisms

To investigate the distribution of intron-exon structures of eukaryotic genes, we have constructed a general exon database comprising all available intron-containing genes and exon databases from 10 eukaryotic model organisms: Homo sapiens, Mus musculus, Gallus gallus, Rattus norvegicus, Arabidopsis thaliana, Zea mays, Schizosaccharomyces pombe, Aspergillus, Caenorhabditis elegans and Drosophila. We purged redundant genes to avoid the possible bias brought about by redundancy in the databases. After discarding those questionable introns that do not contain correct splice sites, the final database contained 17 102 introns, 21 019 exons and 2903 independent or quasi-independent genes. On average, a eukaryotic gene contains 3.7 introns per kb protein coding region. The exon distribution peaks around 30-40 residues and most introns are 40-125 nt long. The variable intron-exon structures of the 10 model organisms reveal two interesting statistical phenomena, which cast light on some previous speculations. (i) Genome size seems to be correlated with total intron length per gene. For example, invertebrate introns are smaller than those of human genes, while yeast introns are shorter than invertebrate introns. However, this correlation is weak, suggesting that other factors besides genome size may also affect intron size. (ii) Introns smaller than 50 nt are significantly less frequent than longer introns, possibly resulting from a minimum intron size requirement for intron splicing.

Generation of a widespread Drosophila inversion by a transposable element

Although polymorphic inversions in Drosophila are very common, the origin of these chromosomal rearrangements is unclear. The breakpoints of the cosmopolitan inversion 2j of D. buzzatii were cloned and sequenced. Both breakpoints contain large insertions corresponding to a transposable element. It appears that the two pairs of target site duplications generated upon insertion were exchanged during the inversion event, and that the inversion arose by ectopic recombination between two copies of the transposon that were in opposite orientations. This is apparently the mechanism by which transposable elements generate natural inversions in Drosophila.

Generation of a widespread Drosophila inversion by a transposable element

Although polymorphic inversions in Drosophila are very common, the origin of these chromosomal rearrangements is unclear. The breakpoints of the cosmopolitan inversion 2j of D. buzzatii were cloned and sequenced. Both breakpoints contain large insertions corresponding to a transposable element. It appears that the two pairs of target site duplications generated upon insertion were exchanged during the inversion event, and that the inversion arose by ectopic recombination between two copies of the transposon that were in opposite orientations. This is apparently the mechanism by which transposable elements generate natural inversions in Drosophila.

Probabilistic modeling of shear-induced formation and breakage of doublets cross-linked by receptor-ligand bonds

A model was constructed to describe previously published experiments of shear-induced formation and breakage of doublets of red cells and of latexes cross-linked by receptor-ligand bonds (. Biophys. J. 65:1318-1334; Tees and Goldsmith. 1996. Biophys. J. 71:1102-1114;. Biophys. J. 71:1115-1122). The model, based on McQuarrie's master equations (1963. J. Phys. Chem. 38:433-436), provides unifying treatments for three distinctive time periods in the experiments of particles in a Couette flow in which a doublet undergoes 1) formation upon two-body collision between singlets; 2) evolution of bonds at low shear rate; and 3) break-up at high shear rate. Neglecting the applied force at low shear rate, the probability of forming a doublet per collision as well as the evolution of probability distribution of bonds in a preformed doublet were solved analytically and found to be in quite good agreement with measurements. At high shear rate with significant force acting to accelerate bond dissociation, the predictions for break-up of doublets were obtained numerically and compared well with data in both individual and population studies. These comparisons enabled bond kinetic parameters for three types of particles cross-linked by two receptor-ligand systems to be calculated, which agreed well with those computed from Monte Carlo simulations. This work can be extended to analyze kinetics of receptor-ligand binding in cell aggregates, such as those of neutrophils and platelets in the circulation.

Titanium alloys in total joint replacement--a materials science perspective

Increased use of titanium alloys as biomaterials is occurring due to their lower modulus, superior biocompatibility and enhanced corrosion resistance when compared to more conventional stainless steels and cobalt-based alloys. These attractive properties were a driving force for the early introduction of alpha (cpTi) and alpha + beta (Ti-6A1-4V) alloys as well as for the more recent development of new Ti-alloy compositions and orthopaedic metastable beta titanium alloys. The later possess enhanced biocompatibility, reduced elastic modulus, and superior strain-controlled and notch fatigue resistance. However, the poor shear strength and wear resistance of titanium alloys have nevertheless limited their biomedical use. Although the wear resistance of beta-Ti alloys has shown some improvement when compared to alpha + beta alloys, the ultimate utility of orthopaedic titanium alloys as wear components will require a more complete fundamental understanding of the wear mechanisms involved. This review examines current information on the physical and mechanical characteristics of titanium alloys used in artifical joint replacement prostheses, with a special focus on those issues associated with the long-term prosthetic requirements, e.g., fatigue and wear.

Toward a resolution of the introns early/late debate: only phase zero introns are correlated with the structure of ancient proteins

We present evidence that a well defined subset of intron positions shows a non-random distribution in ancient genes. We analyze a database of ancient conserved regions drawn from GenBank 101 to retest two predictions of the theory that the first genes were constructed by exon shuffling. These predictions are that there should be an excess of symmetric exons (and sets of exons) flanked by introns of the same phase (positions within the codon) and that intron positions in ancient proteins should correlate with the boundaries of compact protein modules. Both these predictions are supported by the data, with considerable statistical force (P values < 0.0001). Intron positions correlate to modules of diameters around 21, 27, and 33 A, and this correlation is due to phase zero introns. We suggest that 30-40% of present day intron positions in ancient genes correspond to phase zero introns originally present in the progenote, while almost all of the remaining intron positions correspond to introns added, or moved, appearing equally in all three intron phases. This proposal provides a resolution for many of the arguments of the introns-early/introns-late debate.

For a healthier community

Understanding the concept of community is crucial to improving the health status of our citizens. This author used her knowledge of community, understanding of nursing principles, and strong commitment to volunteerism to create the first outreach clinic in Atlanta. Her career story unfolds as she tells of moving from a single community to a role of advocate for a national community population.

[Changes in trace elements contents of renal cells in cadmium poisoning]

OBJECTIVE

To understand the possible role of trace elements in renal damage caused by cadmium poisoning and its mechanism.

METHODS

An experimental animal model with renal damage caused by cadmium poisoning was prepared, and trace elements contents in subcellular components in renal cells, lipid peroxidation reaction, renal function and its ultrastructural changes were determined.

RESULTS

Uptake of cadmium could cause transfer of copper, zinc and manganese mainly distributed in the mitochondrion to cell nuclei and cytoplasm, and content of selenium and activity of glutathione-peroxidase (GSH-px) in cytosol declined and content of propandiolal increased.

CONCLUSION

It suggests that changes in trace elements contents, especially in selenium content, during renal damage caused by cadmium poisoning, could correlate with the increase of lipid peroxidation, and abnormal subcellular distribution of trace elements was one of the important roles in renal damage caused by cadmium poisoning.

Relationship between "proto-splice sites" and intron phases: evidence from dicodon analysis

The coding sequence at the boundaries of exons flanking nuclear introns shows some degree of conservation. To the extent that such sequences might be recognized by the splicing machinery, this conservation may be a derived result of evolution for efficient splicing. Alternatively, such conserved sequences might be remnants of proto-splice sites, which might have existed early in eukaryotic genes and served as the targets for the insertion of introns, as has been proposed by the introns-late theory. The distribution of intron phases, the position of the intron within a codon, is biased with an over-representation of phase 0 introns. Could any distribution of proto-splice sites account for today's intron phase distribution? Here, we examine the dicodon usage in six model organisms, based on current sequences in the GenBank database, and predict the phase distribution that would be expected if introns had been inserted into proto-splice sites. However, these predictions differ between the various model organisms and disagree with the observed intron phase distributions. Thus, we reject the hypothesis that introns are inserted into hypothetical proto-splice sites. Finally, we analyze the sequences around the splice sites of introns in all six of the species to show that the actual conservation of sequence in exon regions near introns is very small and differs considerably between these species, which is inconsistent with a general proto-splice sites model.

Cadmium Accumulation and Toxicity in The Bottlenose Dolphin Tursiops truncatus, The Common Dolphin Delphinus delphis, and Some Dolphin Prey Species in South Australia

Twenty Tursiops truncatus and 20 Delphinus delphis from South Australia were analysed for cadmium levels, as were some fish and squid species which form part of their diet. In the dolphins, cadmium was accumulated mainly in the kidneys (range 0-38 μg/g), with levels in many individuals exceeding 20 μg/g (wet weight). On average, levels in kidney were three-fold higher than in liver and 26-fold higher than in muscle. Cadmium concentrations related to dolphin body length, but the relationship with tooth development class was less clear. 80% of the prey fish species analysed from Spencer Gulf exceeded NH & MRC health recommendations of 0.2 μg/g (wet weight) for human consumption. Sepioteuthis australis from upper Spencer Gulf contained significantly higher cadmium levels than Ceduna samples (0.21 ± 0.01 μg/g versus 0.13 ± 0.01 μg/g, p&lt;0.001) (wet weight). On histological examination, 32% of adult dolphin kidneys showed pathological changes, proteinuria being the most common abnormality. High levels of cadmium were found in dolphins from widely spaced locations in South Australia.

The correlation between introns and the three-dimensional structure of proteins

We test the hypothesis that introns were used to construct the first genes from small exons, whose protein products represent compact elements of structure. For any three-dimensional structure, a computer program analyzes the structure into a set of modules, segments of the polypeptide chain bounded in space by a maximum diameter, separated by a set of 'boundary regions'. The 'boundary regions' are such that if the gene were divided by an intron in each 'boundary region', the protein would be divided into modules less than the specified diameter. Using a set of 32 ancient proteins, which have no introns in prokaryotes, we examine the intron positions in their eukaryotic homologs and show that the introns are correlated with modules of diameter 21, 28 and 33 A, with P values below 0.001.

[The effect of hypertonic saline solution on the rheology after burn-blast combined injury]

To study the effect of hypertonic saline solution on the rheology and putative mechanism, we investigated the changes of plasma viscosity, blood viscosity and reduced viscosity in dogs treated with hypertonic saline solution after burn-blast combined injury and observed the effect of hypertonic saline solution therapy on the viscoelastic property of erythrocyte membranes measured by micropippette aspiration technique in rats with burn. The results showed that the blood viscosity and reduced viscosity increased significantly in dogs after injury, and plasma viscosity also increased significantly at 24 h after injury. Elastic moduli and viscous coefficients of erythrocyte membranes increased obviously in rats after burn. The hypertonic saline solution therapy could significantly improve blood viscosity and reduced viscosity, but it did not significantly improve elastic moduli and viscous coefficients of erythrocyte membranes. These suggested that the hardness of erythrocyte membranes increased, the deform property of erythrocyte membranes decreased, and the blood rheology became worse after burn blast combined injury. Hypertonic saline solution therapy could significantly improve the blood rheology. The effect did not bear a significant relationship with the change of single biomechanics property of erythrocyte membranes. It might be related with other factors.

[Effect of electric field on erythrocyte sedimentation rate. VI--dependence of electric field pattern]

An automatic analyzer of RBC rheological parameters and a microscopic morphological observation technique were employed to investigate the effect of three electric field patterns on erythrocyte sedimentation and aggregation in a physiological saline solution and in autologous plasma, respectively. Experimental results indicate that in a physiological saline solution: 1) Erythrocytes present a lightly aggregation and settle faster by an alternative current electric field; 2) There exists no erythrocyte aggregation by a direct current electric field of constant current and the enhancement of erythrocyte sedimentation is caused only by the action of electric force; 3) Time courses of erythrocyte sedimentation fit well with an exponential type curve by a direct current electric field of constant voltage, and this exponential type sedimentation curve is not caused by erythrocyte aggregation but caused by the decrease of circuit current with time duration. Also shown by experimental results is that the above three electric field patterns all affect the erythrocyte sedimentation in antologous plasma in different contents, which predicts some change in erythrocyte aggregation behavior in autologous plasma by an external electric field.

[Experimental study on erythrocyte of obstructive jaundice patient: its changes of membrane protein and mechanical properties]

The component of the erythrocyte membrane protein under three states obstruction, after surgical relief of obstruction, and normal) were analyzed qualitatively by using SDS-PAGE and the method of thin scanning. The result revealed that the membrane protein band 4.2 was absent under the state of obstruction and it recovered after surgical relief of obstruction. Then the mechanical properties of the above three cases of erythrocytes were tested by the micropipette aspiration system and the data were analyzed by Voigt model. The result showed that the elastic modulus and the coefficient of viscosity of the erythrocytes under the state of obstruction were greater than those of the normal; thus the deformability decreased, but "overcorrection" appeared after surgical relief of obstruction. The possible relations between the mechanical properties and the change of membrane protein were discussed.

Origin of genes

We discuss two tests of the hypothesis that the first genes were assembled from exons. The hypothesis of exon shuffling in the progenote predicts that intron phases will be correlated so that exons will be an integer number of codons and predicts that the exons will be correlated with compact regions of polypeptide chain. These predictions have been tested on ancient conserved proteins (proteins without introns in prokaryotes but with introns in eukaryotes) and hold with high statistical significance. We conclude that introns are correlated with compact features of proteins 15-, 22-, or 30-amino acid residues long, as was predicted by "The Exon Theory of Genes."

[Investigation on the viscoelastic properties of hepatocytes and their relavances to cytoskeleton structure]

Using micropipette aspiration technique, the authors investigated the viscoelastic properties of human fetal hepatocytes (HFH) and hepatocellular carcinoma (HCC) cells. And further, the effects of two cytoskeleton interferents, cytochalasin D and colchicine on the viscoelastic properties of HFHs were investigated. The results showed: the elastic coefficients K1 and K2 of HCC cells were significantly higher than those of HFHs; the action of cytochalasin D led to an obvious decrease in elastic coefficients K1, K2 as well as the viscous coefficient mu of HFHs; under the action of colchicine, the K1 value of HFHs increased while the K2 and mu values decreased obviously or tended to decrease. A brief discussion was presented about these results.

Alteration of transcriptional and post-transcriptional expression of gamma-glutamylcysteine synthetase by diethyl maleate

Gamma-glutamylcysteine synthetase (gamma-GCS), also known as glutamate-cysteine ligase (EC 6.3.2.2), is the rate-limiting enzyme in the synthesis of glutathione (GSH). The gene GLCLC encodes the catalytic subunit while GLCLR encodes the regulatory subunit. Although it has been shown that GLCLC can respond to a variety of stresses by increased transcription, it is not known whether a similar response occurs for GLCLR. Nor is it known whether post-transcriptional regulation of either gene product is altered during stress. The present investigation was undertaken to explore transcriptional and post-transcriptional regulation of GLCLC and GLCLR gene products when HepG2 cells were challenged with the radiation sensitizer diethyl maleate (DEM). Expression of steady-state GLCLC and GLCLR mRNA was enhanced 5-20-fold after DEM challenge. Nuclear run-off assays were performed on unstressed and stressed cells to determine whether the increased expression of GLCLC and GLCLR mRNA was due to altered transcriptional activity of these genes. The DEM treatment increased the transcription rates of both genes 2-5-fold. In unstressed HepG2 cells, the half-life of GLCLC mRNA transcripts was approximately 4 h. In contrast, the half-life of GLCLR transcripts was approximately 8 h. In cells treated with DEM, the half-lives of all transcripts were increased, indicating that message stabilization contributed to the increased expression of gene products. Finally, a PEST algorithm has identified a PEST (proline, glutamate, serine, threonine) motif within the catalytic subunit of gamma-GCS, suggesting that this subunit might exhibit conditional proteolytic regulation. These results imply that regulation of the products of the GLCLC and GLCLR genes may be altered at multiple levels during exposure to stress.

Nucleotide variation and conservation at the dpp locus, a gene controlling early development in Drosophila

A study of polymorphism and species divergence of the dpp gene of Drosophila has been made. Eighteen lines from a population of D. melanogaster were sequenced for 5200 bp of the Hin region of the gene, coding for the dpp polypeptide. A comparison was made with sequence from D. simulans. Ninety-six silent polymorphisms and three amino acid replacement polymorphisms were found. The overall silent polymorphism (0.0247) is low, but haplotype diversity (0.0066 for effectively silent sites and 0.0054 for all sites) is in the range found for enzyme loci. Amino acid variation is absent in the N-terminal signal peptide, the C-terminal TGF-beta peptide and in the N-terminal half of the pro-protein region. At the nucleotide level there is strong conservation in the middle half of the large-intron and in the 3' untranslated sequence of the last exon. The 3' untranslated conservation, which is perfect for 110 bp among all the divergent species, is unexplained. There is strong positive linkage disequilibrium among polymorphic sites, with stretches of apparent gene conversion among originally divergent sequences. The population apparently is a migration mixture of divergent clades.

Intron positions correlate with module boundaries in ancient proteins

We analyze the three-dimensional structure of proteins by a computer program that finds regions of sequence that contain module boundaries, defining a module as a segment of polypeptide chain bounded in space by a specific given distance. The program defines a set of "linker regions" that have the property that if an intron were to be placed into each linker region, the protein would be dissected into a set of modules all less than the specified diameter. We test a set of 32 proteins, all of ancient origin, and a corresponding set of 570 intron positions, to ask if there is a statistically significant excess of intron positions within the linker regions. For 28-A modules, a standard size used historically, we find such an excess, with P < 0.003. This correlation is neither due to a compositional or sequence bias in the linker regions nor to a surface bias in intron positions. Furthermore, a subset of 20 introns, which can be putatively identified as old, lies even more explicitly within the linker regions, with P < 0.0003. Thus, there is a strong correlation between intron positions and three-dimensional structural elements of ancient proteins as expected by the introns-early approach. We then study a range of module diameters and show that, as the diameter varies, significant peaks of correlation appear for module diameters centered at 21.7, 27.6, and 32.9 A. These preferred module diameters roughly correspond to predicted exon sizes of 15, 22, and 30 residues. Thus, there are significant correlations between introns, modules, and a quantized pattern of the lengths of polypeptide chains, which is the prediction of the "Exon Theory of Genes."

Rats perform better on spatial than brightness delayed matching-to-sample water-escape due to an unlearned bias to use spatial cues

Rats readily acquire water-escape spatial delayed matching-to-sample (DMTS) tasks and show excellent performance with retention intervals as long as 120 m (17). They also acquire the task more readily with a 5-min retention interval (RI) than with a 1-min RI (16). To determine if these observations are unique to spatial DMTS, or are also true of nonspatial water-escape DMTS, 75-day-old rats were compared on acquisition and subsequent retention of spatial and brightness DMTS. A larger proportion of the rats tested on the spatial problem were able to acquire the task, made fewer acquisition errors, and demonstrated better retention when tested at RIs of 1, 5, 15, 30, 60, and 120 min than did the rats tested on the brightness problem. Acquisition RI did not affect the rate of acquisition on either task. Examination of perserveration errors, the occurrence of intrusions, and position-congruent performance (escape platform in the same physical location on both runs of a trial) revealed that the choices of brightness-trained rats were often more influenced by spatial than brightness cues, suggesting that rats have an unlearned bias to use spatial cues in water-escape DMTS tasks.

Scopolamine- and morphine-induced deficits in water maze alternation: failure to attenuate with glucose

Glucose has previously been shown to improve performance on memory tasks and to ameliorate performance deficits induced by scopolamine or morphine. To test the generality of these observations, Sprague-Dawley rats were trained to alternate choices to reach an escape platform in a two-choice circular water maze. The rats attained a high level of alternation, alternating on a mean of 9 of 10 daily trials. Daily glucose injections (100 and 250 mg/ kg) failed to facilitate acquisition of the alternation. Single injections of scopolamine (0.5, 1.0, and 2.0 mg/kg), but not methylscopolamine (0.5 mg/kg), and daily injections of scopolamine (0.5 mg/kg) or morphine (5.0 mg/kg) impaired alternation performance. The scopolamine- and morphine-induced deficits in alternation behavior were not ameliorated by pretrial glucose injections at doses which have previously been found to be effective (100 and 250 mg/kg). The mechanism of glucose facilitation of memory is currently unknown. The present results show that glucose given at previously established effective doses does not activate the mechanism or produces too weak an effect to be observed in water maze alternation.

Exon shuffling and the origin of the mitochondrial targeting function in plant cytochrome c1 precursor

Since most of the examples of "exon shuffling" are between vertebrate genes, the view is often expressed that exon shuffling is limited to the evolutionarily recent lineage of vertebrates. Although exon shuffling in plants has been inferred from the analysis of intron phases of plant genes [Long, M., Rosenberg, C. & Gilbert, W. (1995) Proc. Natl. Acad. Sci. USA 92, 12495-12499] and from the comparison of two functionally unknown sunflower genes [Domon, C. & Steinmetz, A. (1994) Mol. Gen. Genet. 244, 312-317], clear cases of exon shuffling in plant genes remain to be uncovered. Here, we report an example of exon shuffling in two important nucleus-encoded plant genes: cytosolic glyceraldehyde-3-phosphate dehydrogenase (cytosolic GAPDH or GapC) and cytochrome c1 precursor. The intron-exon structures of the shuffled region indicate that the shuffling event took place at the DNA sequence level. In this case, we can establish a donor-recipient relationship for the exon shuffling. Three amino terminal exons of GapC have been donated to cytochrome c1, where, in a new protein environment, they serve as a source of the mitochondrial targeting function. This finding throws light upon an old important but unsolved question in gene evolution: the origin of presequences or transit peptides that generally exist in nucleus-encoded organelle genes.

[Monocellular quantitative study on the adhesive ability of eosinophils in the course of eosinophils activation]

OBJECTIVE

To observe the dynamic changes of eosinophils (EOS) adhesive ability in the course of eosinophils activation.

METHODS

The adhesive ability EOS to vascular endothelial cell (EC) was measured by the use of a microminpulation technique.

RESULTS

The critical separation stress (Sc) between rest EOS and EC was 0.61 +/- 0.07kPa. Treatment of EOS with platelet activaty factor (PAF) caused a significant increase in Sc. The Sc was 4.1 +/- 0.6kPa within 30 minutes of EOS exposure to PAF, and had no tendency to increase continuously by exposure time prolonged.

CONCLUSIONS

The increase of EOS adhesive ability belongs to a kind of rapid response while EOS is activated. The increase could be an important basis of EOS adhesion to EC and EOS entry into bronchial mucosa.

Introns and gene evolution

In one scenario of gene evolution, exon shuffling has a fundamental role in increasing gene diversity. As DNA sequences accumulate in the databases, the picture of the intron/exon structures of genes becomes more and more clear. We discuss in this review some features of this picture that suggest that introns have been present since the early stages of evolution, and that exon shuffling was a fundamental process in the construction of ancient as well as modern genes.

Intron phase correlations and the evolution of the intron/exon structure of genes

Two issues in the evolution of the intron/exon structure of genes are the role of exon shuffling and the origin of introns. Using a large data base of eukaryotic intron-containing genes, we have found that there are correlations between intron phases leading to an excess of symmetric exons and symmetric exon sets. We interpret these excesses as manifestations of exon shuffling and make a conservative estimate that at least 19% of the exons in the data base were involved in exon shuffling, suggesting an important role for exon shuffling in evolution. Furthermore, these excesses of symmetric exons appear also in those regions of eukaryotic genes that are homologous to prokaryotic genes: the ancient conserved regions. This last fact cannot be explained in terms of the insertional theory of introns but rather supports the concept that some of the introns were ancient, the exon theory of genes.

Evolution of the intron-exon structure of eukaryotic genes

The origin and evolution of intron-exon structures continue to be controversial topics. Two alternative theories, the 'exon theory of genes' and the 'insertional theory of introns', debate the presence or absence of introns in primordial genes. Both sides of the argument have focused on the positions of introns with respect to protein and gene structures. A new approach has emerged in the study of the evolution of intron-exon structures: a population analysis of genes. One example is the statistical analysis of intron phases--the position of introns within or between codons. This analysis detected a significant signal of exon shuffling in the DNA sequence database containing both ancient and modern exon sequences: intron phase correlations, that is, the association together within genes of introns of the same phase. The results of this analysis suggest that exon shuffling played an important role in the origin of both ancient and modern genes.

Alterations in immune function following head injury in children

OBJECTIVE

To investigate cellular and humoral immunity in children immediately after severe head injury and during the early recovery period.

DESIGN

Prospective, observational study with factorial design.

SETTING

Pediatric ICU of a university teaching hospital.

PATIENTS

Fifteen children (median age 9.6 yrs, range 1.7 to 18) with head injury and Glasgow Coma Score of < or = 7.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Skin testing with seven standard antigens was performed and blood samples were obtained for the following measurements: total lymphocyte count and subsets; proliferative response to phytohemagglutinin, concanavalin A, and pokeweed mitogen; and immunoglobulin concentrations on days 1, 7, and 14 and 3 months after injury. The effect of patient plasma on phytohemagglutinin-induced proliferative responses of normal donor lymphocytes was also assessed at these times. Anergy was present in 71% of patients on day 1, 54% of patients on day 7, 31% of patients on day 14, and 18% of patients at 3 months. Total, helper, and suppressor T-cell counts were decreased on day 1, and the T-cell response to phytohemagglutinin was decreased on days 1, 7, and 14 compared with values at 3 months. B-cell counts were increased on day 1, followed by an increase in serum immunoglobulin concentrations 1 to 2 wks later. The B-cell response to pokeweed mitogen was unchanged over the 3-month study period. The phytohemagglutinin responses of normal donor lymphocytes were decreased when incubated with patient plasma obtained on day 7 after injury.

CONCLUSIONS

Severe head injury in children is associated with depressed cell-mediated immunity. Plasma immunosuppressive factors may contribute to T-cell dysfunction.

Colonization of mechanical ventilation bags during use

BACKGROUND

Colonization of patients' mechanical ventilation bags was examined to evaluate two criteria (days in use and appearance) for replacing the disposable adapter that interfaces with the patient.

METHODS

Adapters used 1 to 2, 3 to 4 and 6 to 7 days formed groups I, II, and III, respectively (n = 29 to 67 per group). Another group (IA) contained 33 adapters used 1 to 2 days from patients intubated at least 7 days. Appearance of adapters was noted and adapters were swab cultured on nonselective medium.

RESULTS

Analysis of variance indicated a difference in log colony-forming units per adapter between groups I and II (p = 0.032), but colony-forming units per adapter varied widely. Group III had a lower mean colony-forming unit count than group II. Groups I and II differed in variables other than days of use, but these confounding variables were eliminated by substituting group IA for group I. When adapter appearance versus colonization was examined by chi 2 test, a significant difference was found between adapters that looked "clean" and those with precipitate or with mucus or blood.

CONCLUSIONS

For the subjects studied, colonization of adapters increased significantly between 1 to 2 and 3 to 4 days of use but varied widely. Appearance may be more useful than days in use as a criterion for changing adapters.

Performance of case-finding tools for depression in the nursing home: influence of clinical and functional characteristics and selection of optimal threshold scores

OBJECTIVE

To compare case-finding tools for depression in the nursing home setting and to evaluate effects of subject function, cognition, and disease number on test performance.

DESIGN

Cross-sectional survey.

SETTING

One academic and four community homes.

SUBJECTS

One hundred thirty-four randomly selected, mildly cognitively impaired, functionally dependent residents.

METHODS AND MEASURES

The Geriatric Depression Scale (GDS), Short Geriatric Depression Scale (SGDS), Center for Epidemiologic Studies Depression Scale (CES-D), and Brief Carrol Depression Rating Scale (BCDRS) were administered. The Structured Clinical Interview for DSM-III-R diagnoses was administered independently,. Operating characteristics and the effects of subject characteristics on test performance were evaluated using McNemar's test and logistic regression. Selection of "optimal" threshold scores was guided by Kraemer's quality indices and clinical judgment.

RESULTS

Thirty-five subjects (26%) had major depression. No differences were found among the instruments in sensitivity (range 0.74-0.89), specificity (range 0.62-0.77), or area under the receiver operating curve (ROC) (range 0.85-0.91). Resident characteristics did not affect test performance. Quality indices showed the GDS and BCDRS met criteria for moderate to substantial agreement with the criterion standard, whereas the SGDS and the CES-D achieved only fair agreement. No change in threshold scores was warranted.

CONCLUSIONS

The GDS and BCDRS performed well in the nursing home. As the GDS can serve as a both a case-finding and severity instrument, it is preferred. Use of brief, interviewer-administered tools may improve detection of depression in the nursing home.

Effect of electric field on erythrocyte sedimentation rate. IV. Volume fraction dependence of human red cells in plasma

We measured the volume fraction dependence of erythrocyte sedimentation for human red cells in autologous plasma while the volume fraction, Hct, ranges from 0.220 to 0.650. A modified electrophoretic instrument was employed to investigate the electric effect of an upward DC field on erythrocyte sedimentation at a constant source supply of Vs = 60.0 +/- 0.5 V. The sedimentation curves all coincided well with the sigmoidal type equation, l = lmax/¿l + (t50/t)n¿, at Vs = 0, or 60.0 V. Here, lmax is the length of plasma level, l, when the time, t, tends to infinity; t50 is the elapsed time when the plasma level falls to lmax/2, and n is a constant (n > 0). A non-linear least-squares method was employed to fit experimental data. It was found that lmax decreased and t50 increased with the increase of Hct, while n ranged from 1.53 to 3.95. The volume fraction dependence of sedimentation velocity, Vmax, defined as the maximum slope of the sedimentation curve, fits well with an exponential-type curve, both at Vs = 60.0 V and at Vs = 0 V: Vmax = Vs (1-Hct)exp(-BHct), where Vs is the velocity at infinite dilution and B is a phenomenological parameter. In the range of Hct = 0.220-0.650, Vs and B are 326.1 mm/hr and 4.30, respectively, at Vs = 60.0 V, while they are 130.4 mm/hr and 2.46, respectively, at Vs = 0 V.

Natural selection and the origin of jingwei, a chimeric processed functional gene in Drosophila

The origin of new genes includes both the initial molecular events and subsequent population dynamics. A processed Drosophila alcohol dehydrogenase (Adh) gene, previously thought to be a pseudogene, provided an opportunity to examine the two phases of the origin of a new gene. The sequence of the processed Adh messenger RNA became part of a new functional gene by capturing several upstream exons and introns of an unrelated gene. This novel chimeric gene, jingwei, differs from its parent Adh gene in both its pattern of expression and rate of molecular evolution. Natural selection participated in the origin and subsequent evolution of this gene.