Mood, dissociation and false memories using the Deese-Roediger-McDermott procedure

Who is likely to have a false memory? Does being in a certain transient state, such as a negative mood, mean that a person is more like to have a false memory? These important questions are examined using the Deese-Roediger-McDermott (DRM) procedure. The amount of false memories was compared with people's score on a dissociation measure and by mood. Unlike past research, which has used different procedures to explore false memories, we found that dissociation was not associated with false memories. We argue that this is because the DRM procedure requires two processes for a false memory (the generation of the critical lure and mistaking its source), while most false memory procedures only require one process (source monitoring error) because the errant information is suggested to the participant. This pattern of results suggests that only errors with the source monitoring process are associated with dissociation. We found that mood was related to false memories, but it was dependent on the specific task demands. If participants were told to recall as many words as they could, then people in a negative mood had more false memories. However, if they were told to recall as many words as they felt like recalling, then there were more false memories for people in a positive mood. This can be explained by the mood-as-input hypothesis. Results are discussed in relation to both theories and applications of memory.

Oral manifestations of Sjögren's syndrome

Sjögren's syndrome is a common autoimmune rheumatic disease. The most common symptoms of Sjögren's syndrome are extreme tiredness, along with dry eyes (keratoconjunctivitis sicca) and dry mouth (xerostomia). Saliva plays an essential role in numerous functions of the mouth. Xerostomia can be caused by medications, chronic diseases like Sjögren's syndrome, and medical treatments, such as radiation therapy and bone marrow transplant. Xerostomia can eventually lead to difficulty in swallowing, severe and progressive tooth decay, or oral infections. Despite having excellent oral hygiene, individuals with Sjögren's syndrome have elevated levels of dental caries, along with the loss of many teeth, early in the disease. Sjögren's syndrome alters the protein profile and brings about a change in the composition of saliva. There is an increase in the levels of lactoferrin, beta(2)-microglobulin, sodium, lysozyme C, and cystatin C, and a decrease in salivary amylase and carbonic anhydrase. Up to 90% of individuals with Sjögren's syndrome have antibodies targeting the Ro 60 and La autoantigens. Natural aging, regardless of Sjögren's syndrome, is also another factor that brings about a significant change in the composition of saliva. The most prevailing cause of xerostomia in elderly persons is the use of anticholinergic medications. Currently, there is no cure for Sjögren's syndrome, and treatment is mainly palliative.

Improved prediction of bacterial transcription start sites

MOTIVATION

Identifying bacterial promoters is an important step towards understanding gene regulation. In this paper, we address the problem of predicting the location of promoters and their transcription start sites (TSSs) in Escherichia coli. The accepted method for this problem is to use position weight matrices (PWMs), which define conserved motifs at the sigma-factor binding site. However this method is known to result in large numbers of false positive predictions.

RESULTS

Our approaches to TSS prediction are based upon an ensemble of support vector machines (SVMs) employing a variant of the mismatch string kernel. This classifier is subsequently combined with a PWM and a model based on distribution of distances from TSS to gene start. We investigate the effect of different scoring techniques and quantify performance using area under a detection-error tradeoff curve. When tested on a biologically realistic task, our method provides performance comparable with or superior to the best reported for this task. False positives are significantly reduced, an improvement of great significance to biologists.

AVAILABILITY

The trained ensemble-SVM model with instructions on usage can be downloaded from http://eresearch.fit.qut.edu.au/downloads

Social Recognition Memory: The Effect of Other People's Responses for Previously Seen and Unseen Items

When people discuss their memories, what one person says can influence what another person reports. In 3 studies, participants were shown sets of stimuli and then given recognition memory tests to measure the effect of one person's response on another's. The 1st study (n = 24) used word recognition with participant-confederate pairs and found that the effect of confederate responses on participant responses was larger for previously unseen items than for previously seen items (omega(p) = .23). This finding was replicated in the 2nd study, which used photographs of cars (n = 24). In the 3rd study (n = 54), which used photographs of faces with participant pairs, the effect was also larger for unseen items. Results indicate that people rely more on other people's memories for unremembered objects than for remembered objects. This is important for both theories of memory and applications (e.g., witnesses talking, students studying together).

Efficacy of partially hydrolyzed corn syrup solids as a replacement for lactose in manufactured liquid diets for neonatal pigs

Feeding manufactured liquid diets to early-weaned pigs improves growth performance and reduces days to market weight compared with pigs receiving pelleted dry feed. Few alternative dietary ingredients are utilized in manufactured liquid diets other than byproducts of the dairy industry, especially for sources of carbohydrates. This experiment was designed to evaluate the efficacy of starch from partially hydrolyzed corn syrup solids (CSS), at two different levels of hydrolyzation, as a replacement for lactose in manufactured liquid diets. Forty-eight pigs were removed from sows at 1 d of age and randomly assigned to one of three treatments: 1) control with lactose as the carbohydrate source, 2) lactose replaced (gram for gram) with CSS (dextrose equivalent [DE]-20), and 3) lactose replaced with DE-42. In addition, 10 pigs were randomly removed from several litters to provide estimates of initial body composition and small intestinal variables. Twenty-four pigs were removed from the study on d 10 of treatment, and the remaining 24 pigs were removed on d 20 of treatment. Pigs averaged 9,845 +/- 191 g at d 20 of treatment regardless of dietary treatment (P > 0.20). No differences in ADG, ADFI, or feed efficiency were detected between treatment groups from d 0 to 20 (P > 0.19). Whole-body water, protein, lipid, and ash accretion rates were unaffected by dietary treatment from d 0 to 10 or from d 0 to 20 (P > 0.20). The replacement of lactose with CSS did not affect intestinal villi height or width, or crypt depth (P > 0.10). Pigs fed lactose tended to have greater lactase activity on d 10 than pigs fed CSS (P < 0.07). Also, pigs fed lactose tended to have lower oligosaccharidase activity than pigs fed the DE-20 diet on d 20 (P < 0.07). No other differences in lactase, maltase, or long oligosaccharidase specific activity on d 10 or 20 of treatment were detected (P > 0.12). Plasma urea nitrogen concentrations were unaffected by diet on d 10 and 20 of treatment. In addition, dry matter digestibility of the diets averaged approximately 85.6 +/- 0.8% and was unaffected by dietary treatment or day of treatment. These results suggest that partially hydrolyzed CSS can be used as a replacement for lactose in manufactured liquid diets for neonatal pigs.

Identification and mapping of sigma-54 promoters in Chlamydia trachomatis

The first sigma(54) promoters in Chlamydia trachomatis L2 were mapped upstream of hypothetical proteins CT652.1 and CT683. Comparative genomics indicated that these sigma(54) promoters and potential upstream activation binding sites are conserved in orthologous C. trachomatis D, C. trachomatis mouse pneumonitis strain, and Chlamydia pneumoniae (CWL029 and AR39) genes.

Development of a quantitative gene expression assay for Chlamydia trachomatis identified temporal expression of sigma factors

Chlamydia trachomatis is an important human pathogen which possesses a unique bi-phasic developmental cycle. We used lightcycler methodology to quantitatively measure gene transcript levels in C. trachomatis strain L2. By measuring 16S rRNA transcript levels, we determined C. trachomatis L2 to have a generation time of approximately 3 h and an inclusion burst size of 200-300 particles. The three chlamydial sigma factor genes rpoD (sigma66), rpsD (sigma28) and rpoN (sigma54) exhibited different patterns of temporal expression. rpoD was central to early chlamydial development, whereas rpsD and rpoN were temporally expressed, coinciding with elementary body (EB) to reticulate body (RB) conversion and RB to EB conversion, respectively.

A strand-specific endonucleolytic activity with DNA site preference for cleavage in Chlamydia trachomatis

Endonucleolytic activity was detected in high-salt extracts of Chlamydia trachomatis cell lysates. This nucleolytic activity showed specificity for one strand of a PCR fragment containing the strong chlamydial promoter that regulates synthesis of two short plasmid-specified RNAs. Strand specificity was also observed with supercoiled DNA containing the same region; once again, the same strand was cleaved. The sensitive strand is the nontemplate strand for two short transcripts which initiate at the same nucleotide. Alignment of sequences on either side of the nick sites revealed a consensus which may be required for recognition of the enzymatic activity.

The RNA polymerase of Chlamydia trachomatis has a flexible sequence requirement at the -10 and -35 boxes of its promoters

Mutated variants of the predicted promoter of the countertranscript of the Chlamydia trachomatis plasmid were tested by in vitro transcription with chlamydial extract. A 3-bp deletion within the -10 region of the putative promoter caused the RNA polymerase to initiate transcription 3 bases downstream. Many single mutations in the -10 and -35 regions did not alter promoter function. However, some multiple mutations in both hexamers rendered the promoter inefficient or ineffective. Taken together, these results indicate that (i) the sequence requirement for chlamydial promoters differs from that for Escherichia coli and (ii) chlamydial RNA polymerase can tolerate considerably more variation at the -10 and -35 regions. These results are paradoxical considering the homology between C. trachomatis sigma 66 and E. coli sigma 70.

R17 coat protein binding site: a convenient reporter for in vitro transcription

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In vitro transcription in Chlamydia psittaci and Chlamydia trachomatis

Extracts of Chlamydia psittaci and Chlamydia trachomatis were used to transcribe molecularly cloned chlamydial genes in vitro. The extracts were prepared by lysing reticulate bodies, obtaining the 10,000 x g centrifugation pellet, and eluting RNA polymerase from the pellet by treatment with 2M KCl to yield a fraction designated SS2. Some in vitro transcription was initiated from non-chlamydial promoters and a small amount of transcription was from endogenous DNA template in SS2. However, optimal transcription from exogenous templates required chlamydial promoter sequences, and primer extension analysis indicated that chlamydia promoter-specific in vitro transcription was initiated from the same start sites recognized in vivo. A monoclonal antibody that was generated against Escherichia coli sigma 70 and which immunologically cross-reacts with C. trachomatis sigma 66 inhibited in vitro transcription of vector and cloned chlamydial DNA, suggesting that transcriptional initiation in the SS2 fraction is mediated by sigma 66. An in vitro transcription assay based on detection of transcripts of specific lengths was applied to the chlamydial system; this assay and others described here should be useful in defining chlamydial promoters and other transcriptional regulatory elements.

A medium for the continuous cultivation of bloodstream forms of Trypanosoma lewisi at 37 C

Trypanosoma lewisi has been maintained continuously at 37 C for more than 2 yr in Iscove's modified Dulbecco's medium with 10% fetal calf serum and a feeder layer of rat fibroblasts. In this medium the continuously reproducing hematozoic culture forms resemble bloodstream forms of T. lewisi in that they appear morphologically similar in Giemsa-stained preparations examined by light microscopy and have a surface coat that is absent in culture forms grown at ambient temperatures, when examined by electron microscopy. To determine whether these hematozoic culture forms also are similar functionally to bloodstream forms, comparative tests of the 2 forms were made of infectivity for the natural rat host, growth in vitro in the described culture medium, sensitivity to inhibition of reproduction by the rat antibody ablastin, and agglutinability by the 2 trypanocidal antibodies produced during a natural course of infection in the rat. Initially, differences between the 2 forms were minor, but after 16 mo in vitro greater differences began to emerge. Most marked was a reduction in infectivity by 22 mo, although sensitivity to ablastin, the single most important characteristic of bloodstream forms of T. lewisi, was still appreciable at this time. Nevertheless, despite this limitation, the culture system described supports hematozoic culture forms of T. lewisi for a considerably longer time than has been reported thus far.

Spindle microtubule differentiation and deployment during micronuclear mitosis in Paramecium

Spindles underwent a 12-fold elongation before anaphase B was completed during the closed mitoses of micronuclei in Paramecium tetraurelia. Two main classes of spindle microtubules have been identified. A peripheral sheath of microtubules with diameters of 27-32 nm was found to be associated with the nuclear envelope and confined to the midportion of each spindle. Most of the other microtubules had diameters of approximately 24 nm and were present along the entire lengths of spindles. Nearly all of the 24-nm microtubules were eliminated from spindle midportions (largely because of microtubule disassembly) at a relatively early stage of spindle elongation. Disassembly of some of these microtubules also occurred at the ends of spindles. About 60% of the total microtubule content of spindles was lost at this stage. Most, perhaps all, peripheral sheath microtubules remained intact. Many of them detached from the nuclear envelope and regrouped to form a compact microtubule bundle in the spindle midportion. There was little, if any, further polymerization of 24-nm microtubules after the disassembly phase. Polymerization of microtubules with diameters of 27-32 nm continued as spindle elongation progressed. Most microtubules in the midportions of well-elongated spindles were constructed from 14-16 protofilaments. A few 24-nm microtubules with 13 protofilaments were also present. The implications of these findings for spatial control of microtubule assembly, disassembly, positioning, and membrane association, that apparently discriminate between microtubules with different protofilament numbers have been explored. The possibility that microtubule sliding occurs during spindle elongation has also been considered.