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PubMed1992

Debate and argument: on modularity and development in autism: a reply to Burack.

Burack (this issue) reopens questions first raised by my 1989a article in this Journal, on whether children with autism have a specific delay in the development of a theory of mind, or whether the data reflect deviance rather than delay. His paper is of considerable value in highlighting points for debate. In my response, I focus on three issues: First, the logical possibility that delay and deviance can occur together. Second, the evidence that autism may instantiate this possibility. Finally, the important question of the modularity of theory of mind.

Autistic Disorder↗
PubMed1996

Modular structure of the Rhizobium meliloti DctB protein.

To investigate the modular structure of the Rhizobium meliloti dicarboxylic acid sensor protein, DctB, three truncated DctB proteins (DctB4, DctB5 and DctB4G) were constructed, overproduced in Escherichia coli and purified. The DctB4G protein was composed of 446 amino acids of the DctB C-terminus and displayed strong autophosphorylation activity in vitro. This activity was sustained when a further 120 amino acids at the N-terminus of the polypeptide were deleted (DctB5). This protein which has an intact transmitter domain exhibits specific but inefficient phospho-transfer capabilities. Removal of 58 amino acids from the DctB4G C-terminus which included blocks F and G2 of the transmitter domain, rendered the resultant protein (DctB4) incompetent in autophosphorylation. Phosphorylation activity was restored to DctB4 through intramolecular complementation with DctB. Therefore, it would appear that the R. meliloti DctB protein is active as a dimer (or higher order oligomer). Furthermore, the intramolecular complementation experiments indicate that the amino acids 171-291, a predicted periplasmic stretch, play an important role in the dimerization process.

Bacterial Proteins↗
PubMed1996

A modular xylanase from mesophilic Cellulomonas fimi contains the same cellulose-binding and thermostabilizing domains as xylanases from thermophilic bacteria.

The xynC gene from mesophilic Cellulomonas fimi encodes a large 125 kDa modular xylanase (XYLC), consisting of six distinct functional domains. In addition to a single Family 10 catalytic domain, XYLC contains a domain homologous with the nodulation protein, NodB, from nitrogen-fixing bacteria and thermostabilizing and cellulose-binding domains found previously only in xylanases from thermophilic bacteria.

Actinomycetales↗
PubMed1978

A modular approach to dental studies.

At the commencement of the 1979 Academic Year a "modular approach" to degree studies in Dentistry will be instituted at the University of Papua New Guinea. This course of studies will be comprised of four progression modules and includes a one-year programme of community service and clinical experience in a dental clinic of the Department of Health.

Curriculum↗
PubMedDate not supplied

A practical, modular hyperthermia phantom.

A catheterized, three-component slab phantom has been fabricated for use in mapping specific absorption rate (SAR) distributions from hyperthermia applicators. A planar array of 21 closely spaced catheters, located at one surface of the 1-cm-thick slab, can be positioned at depths of 0-7 cm below the phantom surface, in 1-cm steps, through appropriate placement and orientation of this slab within the three-slab set. Owing to its modular design, the phantom can be prepared, and also purged of degraded material rapidly and without damage to the catheter tracks.

Humans↗
PubMed1995

Time-domain modeling of peripheral auditory processing: a modular architecture and a software platform.

A software package with a modular architecture has been developed to support perceptual modeling of the fine-grain spectro-temporal information observed in the auditory nerve. The package contains both functional and physiological modules to simulate auditory spectral analysis, neural encoding, and temporal integration, including new forms of periodicity-sensitive temporal integration that generate stabilized auditory images. Combinations of the modules enable the user to approximate a wide variety of existing, time-domain, auditory models. Sequences of auditory images can be replayed to produce cartoons of auditory perceptions that illustrate the dynamic response of the auditory system to everyday sounds.

Auditory Perception↗
PubMed1995

Choice of STATs and other substrates specified by modular tyrosine-based motifs in cytokine receptors.

Many members of the cytokine receptor superfamily initiate intracellular signaling by activating members of the Jak family of tyrosine kinases. Activation of the same Jaks by multiple cytokines raises the question of how these cytokines activate distinct intracellular signaling pathways. Selection of particular substrates--the transcriptional activator Stat3 and protein tyrosine phosphatase PTP1D--that characterize responses to the ciliary neurotrophic factor-interleukin-6 cytokine family depended not on which Jak was activated, but was instead determined by specific tyrosine-based motifs in the receptor components--gp130 and LIFR--shared by these cytokines. Further, these tyrosine-based motifs were modular, because addition of a Stat3-specifying motif to another cytokine receptor, that for erythropoietin, caused it to activate Stat3 in a ligand-dependent fashion.

Amino Acid Sequence↗
PubMed1992

Evidence for a modular structure of the homologous repetitive C-terminal carbohydrate-binding sites of Clostridium difficile toxins and Streptococcus mutans glucosyltransferases.

The homologous C-terminal repeats of Clostridium difficile toxins (ToxA and ToxB) and streptococcal glucosyltransferases appear to mediate protein-carbohydrate interactions at cellular binding sites with sugar moieties as substrates. A consensus sequence of 134 repeating units from gram-positive bacteria indicates that these repeats have a modular design with (i) a stretch of aromatic amino acids proposed to be involved in the primary carbohydrate-protein interaction, (ii) an amplification of this interaction by repetition of the respective sequences, and (iii) a second domain, not characterized, that is responsible for carbohydrate specificity.

Amino Acid Sequence↗
PubMed1993

Cloning and sequencing of the low-affinity penicillin-binding protein 3r-encoding gene of Enterococcus hirae S185: modular design and structural organization of the protein.

The clinical isolate Enterococcus hirae S185 has a peculiar mode of resistance to penicillin in that it possesses two low-affinity penicillin-binding proteins (PBPs): the 71-kDa PBP5, also found in other enterococci, and the 77-kDa PBP3r. The two PBPs have the same low affinity for the drug and are immunochemically related to each other. The PBP3r-encoding gene has been cloned and sequenced, and the derived amino acid sequence has been compared by computer-assisted hydrophobic cluster analysis with that of the low-affinity PBP5 of E. hirae R40, the low-affinity PBP2' of Staphylococcus aureus, and the PBP2 of Escherichia coli used as the standard of reference of the high-M(r) PBPs of class B. On the basis of the shapes, sizes, and distributions of the hydrophobic and nonhydrophobic clusters along the sequences and the linear amino acid alignments derived from this analysis, the dyad PBP3r-PBP5 has an identity index of 78.5%, the triad PBP3r-PBP5-PBP2' has an identity index of 29%, and the tetrad PBP3r-PBP5-PBP2'-PBP2 (of E. coli) has an identity index of 13%. In spite of this divergence, the low-affinity PBPs are of identical modular design and possess the nine amino acid groupings (boxes) typical of the N-terminal and C-terminal domains of the high-M(r) PBPs of class B. At variance with the latter PBPs, however, the low-affinity PBPs have an additional approximately 110-amino-acid polypeptide stretch that is inserted between the amino end of the N-terminal domain and the carboxy end of the membrane anchor. While the enterococcal PBP5 gene is chromosome borne, the PBP3r gene appears to be physically linked to the erm gene, which confers resistance to erythromycin and is known to be plasmid borne in almost all the Streptococcus spp. examined.

Amino Acid Sequence↗
PubMed1996

Identification and characterization of a small modular domain in the herpes simplex virus host shutoff protein sufficient for interaction with VP16.

The herpes simplex virus transactivator VP16 and the virion host shutoff protein vhs are viral structural components that direct the activation of immediate-early gene expression and the arrest of host protein synthesis, respectively, during an infection. Recent studies show that VP16 and vhs physically interact with each other in vitro and in infected cells, suggesting that their respective regulatory functions are coupled. In this report, we used the yeast two-hybrid system and affinity chromatography with purified VP16 fusion proteins to precisely map a region in vhs that directs interaction with VP16. Deletion analysis of vhs demonstrated that a 21-amino-acid-long domain spanning residues 310 to 330 (PAAGGTEMRVSWTEILTQQIA) was sufficient for directing complex formation with VP16 in vivo and in vitro when fused to a heterologous protein. Site-directed mutagenesis of this region identified tryptophan 321 as a crucial determinant for interaction with VP16 in vitro and in vivo and additional residues that are important for stable complex formation in vitro. These findings indicate that vhs residues 310 to 330 constitute an independent and modular binding interface that is recognized by VP16.

Amino Acid Sequence↗
PubMed1993

The ZEBRA activation domain: modular organization and mechanism of action.

An RNA polymerase II activator often contains several regions that contribute to its potency, an organization ostensibly analogous to the modular architecture of promoters and enhancers. The regulatory significance of this parallel organization has not been systematically explored. We considered this problem by examining the activation domain of the Epstein-Barr virus transactivator ZEBRA. We performed our experiments in vitro so that the activator concentrations, stabilities, and affinities for DNA could be monitored. ZEBRA and various amino-terminal deletion derivatives, expressed in and purified from Escherichia coli, were assayed in a HeLa cell nuclear extract for the ability to activate model reporter templates bearing one, three, five, and seven upstream ZEBRA binding sites. Our data show that ZEBRA contains four modules that contribute to its potency in vitro. The modules operate interchangeably with promoter sites to determine the transcriptional response such that the loss of modules can be compensated for by increasing promoter sites. Potassium permanganate footprinting was used to show that transcriptional stimulation is a consequence of the activator's ability to promote preinitiation complex assembly. Kinetic measurements of transcription complex assembly in a reconstituted system indicate that ZEBRA promotes formation of a subcomplex requiring the TFIIA and TFIID fractions, where TFIIA acts as an antirepressor. We propose a model in which the concentration of DNA-bound activation modules in the vicinity of the gene initiates synergistic transcription complex assembly.

Cell Nucleus↗
PubMed1994

Reconstitution of transcriptional activation domains by reiteration of short peptide segments reveals the modular organization of a glutamine-rich activation domain.

The POU domain activator Oct-2 contains an N-terminal glutamine-rich transcriptional activation domain. An 18-amino-acid segment (Q18III) from this region reconstituted a fully functional activation domain when tandemly reiterated and fused to either the Oct-2 or GAL4 DNA-binding domain. A minimal transcriptional activation domain likely requires three tandem Q18III segments, because one or two tandem Q18III segments displayed little activity, whereas three to five tandem segments were active and displayed increasing activity with increasing copy number. As with natural Oct-2 activation domains, in our assay a reiterated activation domain required a second homologous or heterologous activation domain to stimulate transcription effectively when fused to the Oct-2 POU domain. These results suggest that there are different levels of synergy within and among activation domains. Analysis of reiterated activation domains containing mutated Q18III segments revealed that leucines and glutamines, but not serines or threonines, are critical for activity in vivo. Curiously, several reiterated activation domains that were inactive in vivo were active in vitro, suggesting that there are significant functional differences in our in vivo and in vitro assays. Reiteration of a second 18-amino-acid segment from the Oct-2 glutamine-rich activation domain (Q18II) was also active, but its activity was DNA-binding domain specific, because it was active when fused to the GAL4 than to the Oct-2 DNA-binding domain. The ability of separate short peptide segments derived from a single transcriptional activation domain to activate transcription after tandem reiteration emphasizes the flexible and modular nature of a transcriptional activation domain.

Amino Acid Sequence↗
PubMed1995

Modular structure of chromosomal proteins HMG-14 and HMG-17: definition of a transcriptional enhancement domain distinct from the nucleosomal binding domain.

Chromosomal proteins HMG-14 and HMG-17 are the only known nuclear proteins which specifically bind to the nucleosome core particle and are implicated in the generation and/or maintenance of structural features specific to active chromatin. The two proteins facilitate polymerase II and III transcription from in vitro- and in vivo-assembled circular chromatin templates. Here we used deletion mutants and specific peptides to identify the transcriptional enhancement domain and delineate the nucleosomal binding domain of the HMG-14 and -17 proteins. Deletion of the 22 C-terminal amino acids of HMG-17 or 26 C-terminal amino acids of HMG-14 reduces significantly the ability of the proteins to enhance transcription from chromatin templates. In contrast, N-terminal truncation mutants had the same transcriptional enhancement activity as the full-length proteins. We conclude that the negatively charged C-terminal region of the proteins is required for transcriptional enhancement. Chromatin transcription enhancement assays, which involve binding competition between the full-length proteins and peptides derived from their nucleosomal binding regions, indicate that the minimal nucleosomal binding domain of human HMG-17 is 24 amino acids long and spans residues 17 to 40. The results suggest that HMG-14 and -17 proteins have a modular structure and contain distinct functional domains.

Amino Acid Sequence↗
PubMed1992

Using the steatocrit to determine optimal fat content in modular feeds.

The steatocrit was measured in infants with protracted diarrhoea who were receiving intragastric modular feeds. Measurements were made when fat intake was constant to determine steatocrit variability and during increases in fat intake to determine fat tolerance limits. Steatocrit variability was expressed as the range between a subject's lowest and highest steatocrit value. The median between-stool and between-day variabilities were 2% and 11% respectively. Variability was also measured in seven healthy breast fed infants. In the five still displaying appreciable physiological steatorrhoea, the between-day variability (median 8%) and between-stool variability (median 9%) were not significantly different from the protracted diarrhoea group. In the fat tolerance investigations in the protracted diarrhoea group, the steatocrit increased with increases in the module fat content. Fat intake and steatocrit were significantly positively related. A significant negative correlation was seen between steatocrit and weight gain, the latter becoming negligible at steatocrit values around 30%.

Breast Feeding↗
PubMed1994

Cloning, molecular characterization, and expression of the genes encoding the lytic functions of lactococcal bacteriophage phi LC3: a dual lysis system of modular design.

The genes encoding the lysis proteins of Lactococcus lactis bacteriophage phi LC3 were cloned, sequenced, and expressed in Escherichia coli. The phi LC3 lysis genes, lysA and lysB, encode a membrane-disrupting protein (LysA) of 88 amino acids, and a cell wall degrading protein (LysB) of 429 amino acids, which shares significant sequence similarity with lysins from the Streptococcus pneumoniae phages Cp-1, Cp-7, and Cp-9, and Lactobacillus delbrueckii phage mv1. Both LysA and LysB function in E. coli, as judged by lysis of the E. coli host cells and by lytic activity against lactococcal cells when the cloned lysA and lysB genes are expressed. The LysA protein possesses two putative transmembrane helices and highly charged N- and C-termini, and is structurally similar to phage holins that are known to induce lesions in the inner membrane through which phage endolysin can be released to its cell wall substrate. The C-terminal end of LysB contains two highly homologous sequence repeats of 43 amino acids. The LysB repeats show strong sequence similarity to repeats found in lytic enzymes from other Gram-positive bacteria and from Bacillus subtilis phage phi 29 and PZA, as well as in some functionally unrelated proteins, and they are possibly involved in binding of the enzyme to the cell wall substrate. The organization of the dual phi LC3 lysis system supports earlier suggestions that exchange of modular units is an important principle in protein evolution.

Amino Acid Sequence↗
PubMed1977

Use of a generalized modular data handling system in nuclear medicine.

Addition of a CAMAC modular data handling system to a small computer used for gamma-camera work has allowed the acquisition and processing of a broad variety of nuclear medicine data. Significant contributions have been made ranging from clinical renal evaluation to radiopharmaceutical development. Digital rectilinear scanning and computer acquisition of physiological signals such as the electrocardiogram are other applications. The system provides an inexpensive means of matching present-day nuclear computers to the diversity of data.

Computers↗
PubMed1977

A modular computer system for the nuclear medicine/ultrasound laboratory.

Computer-controlled graphic displays are a necessity in many nuclear medicine studies. The authors propose using a set-up consisting of three modules: (a) a display system based on television technology; (b) an instrument interface employing list mode and having a low information loss rate; and (c) flexible modular software which can easily be tailored to the needs of both radiologists and technicians. The authors consider a mini-computer system with broad, flexible applications to be a valuable tool, particularly for those function studies which can only be done by means of nuclear medicine techniques.

Computers↗
PubMed1978

Modular single-needle haemodialysis; ultrafiltration characteristics.

In vitro and in vivo work has been carried out examining a modular single-needle system for fistula haemodialysis. Ultrafiltration characteristics of the single-needle system are defined and conclusions upon flow patterns are reached. Applying the mean blood pressure formula to the extracorporeal system pressures, the transmembrane pressure can be calculated and the ultrafiltration rate forecast. High transmembrane pressures can be modified, with sacrifice of blood flow, by amendment of the blood flow phase durations.

Humans↗