Chromosome 2 sequence of the human malaria parasite Plasmodium falciparum

Chromosome 2 of Plasmodium falciparum was sequenced; this sequence contains 947,103 base pairs and encodes 210 predicted genes. In comparison with the Saccharomyces cerevisiae genome, chromosome 2 has a lower gene density, introns are more frequent, and proteins are markedly enriched in nonglobular domains. A family of surface proteins, rifins, that may play a role in antigenic variation was identified. The complete sequencing of chromosome 2 has shown that sequencing of the A+T-rich P. falciparum genome is technically feasible.

Risk factors for cancer of the testis in young men

An individual matched case-control study of testis cancer in 131 men under age 40 was conducted to investigate antecedent risk factors including events during prenatal life. Ten patients were born with an undescended testis compared to only two controls (p less equal to 0.02), a previously reported risk factor. Two new risk factors were uncovered: six patients-mothers received hormones during the index pregnancy compared to only one control-mother, and eight patient-mothers and two control-mothers reported excessive nausea as a complication of the index pregnancy. A hypothesis linking these three factors is presented: viz, that a major risk factor for testis cancer is a relative excess of certain hormones (in particular estrogen) at the time of differentiation of the testes.

Automated high resolution optical mapping using arrayed, fluid-fixed DNA molecules

New mapping approaches construct ordered restriction maps from fluorescence microscope images of individual, endonuclease-digested DNA molecules. In optical mapping, molecules are elongated and fixed onto derivatized glass surfaces, preserving biochemical accessibility and fragment order after enzymatic digestion. Measurements of relative fluorescence intensity and apparent length determine the sizes of restriction fragments, enabling ordered map construction without electrophoretic analysis. The optical mapping system reported here is based on our physical characterization of an effect using fluid flows developed within tiny, evaporating droplets to elongate and fix DNA molecules onto derivatized surfaces. Such evaporation-driven molecular fixation produces well elongated molecules accessible to restriction endonucleases, and notably, DNA polymerase I. We then developed the robotic means to grid DNA spots in well defined arrays that are digested and analyzed in parallel. To effectively harness this effect for high-throughput genome mapping, we developed: (i) machine vision and automatic image acquisition techniques to work with fixed, digested molecules within gridded samples, and (ii) Bayesian inference approaches that are used to analyze machine vision data, automatically producing high-resolution restriction maps from images of individual DNA molecules. The aggregate significance of this work is the development of an integrated system for mapping small insert clones allowing biochemical data obtained from engineered ensembles of individual molecules to be automatically accumulated and analyzed for map construction. These approaches are sufficiently general for varied biochemical analyses of individual molecules using statistically meaningful population sizes.

Whole-genome shotgun optical mapping of Deinococcus radiodurans

A whole-genome restriction map of Deinococcus radiodurans, a radiation-resistant bacterium able to survive up to 15,000 grays of ionizing radiation, was constructed without using DNA libraries, the polymerase chain reaction, or electrophoresis. Very large, randomly sheared, genomic DNA fragments were used to construct maps from individual DNA molecules that were assembled into two circular overlapping maps (2.6 and 0.415 megabases), without gaps. A third smaller chromosome (176 kilobases) was identified and characterized. Aberrant nonlinear DNA structures that may define chromosome structure and organization, as well as intermediates in DNA repair, were directly visualized by optical mapping techniques after gamma irradiation.

Mechanism of spreading depression: a review of recent findings and a hypothesis

Spreading depression of Leão (SD) can be provoked by numerous nonspecific mechanical, electrical, and chemical stimuli. A similar, if not identical, phenomenon can be provoked by hypoxia. SD is characterized by drastic depolarization of neurons, severe reduction of membrane resistance, and redistribution of ions across cell membranes. Glial cells also depolarize but retain membrane resistance. Tetraethylammonium hastens the onset of hypoxic SD but reduces the sustained potential shift and K+ outflow from cells; 4-aminopyridine also accelerates SD but has no effect on the voltage shift. N-Methyl-D-aspartate receptor antagonists delay the onset of SD, while nickel and cobalt reduce the amplitude of SD-related redistribution of Ca2+. Yet, no specific blocker of SD has been found. Microdialysis of high-K+ solution in hippocampal CA1 region induces recurrent waves of SD propagating semi-independently in adjacent tissue layers, and a prolonged unstable depressed state that has not previously been described. Neither the release of K+ ions nor of glutamate is the unique agent of SD propagation. On the basis of recent findings we propose a hypothetical sequence of events that reconcile many of the previously seemingly paradoxical observations.

Roles of Chondrocytes in Endochondral Bone Formation and Fracture Repair

The formation of the mandibular condylar cartilage (MCC) and its subchondral bone is an important but understudied topic in dental research. The current concept regarding endochondral bone formation postulates that most hypertrophic chondrocytes undergo programmed cell death prior to bone formation. Under this paradigm, the MCC and its underlying bone are thought to result from 2 closely linked but separate processes: chondrogenesis and osteogenesis. However, recent investigations using cell lineage tracing techniques have demonstrated that many, perhaps the majority, of bone cells are derived via direct transformation from chondrocytes. In this review, the authors will briefly discuss the history of this idea and describe recent studies that clearly demonstrate that the direct transformation of chondrocytes into bone cells is common in both long bone and mandibular condyle development and during bone fracture repair. The authors will also provide new evidence of a distinct difference in ossification orientation in the condylar ramus (1 ossification center) versus long bone ossification formation (2 ossification centers). Based on our recent findings and those of other laboratories, we propose a new model that contrasts the mode of bone formation in much of the mandibular ramus (chondrocyte-derived) with intramembranous bone formation of the mandibular body (non-chondrocyte-derived).

Chondrocytes Directly Transform into Bone Cells in Mandibular Condyle Growth

For decades, it has been widely accepted that hypertrophic chondrocytes undergo apoptosis prior to endochondral bone formation. However, very recent studies in long bone suggest that chondrocytes can directly transform into bone cells. Our initial in vivo characterization of condylar hypertrophic chondrocytes revealed modest numbers of apoptotic cells but high levels of antiapoptotic Bcl-2 expression, some dividing cells, and clear alkaline phosphatase activity (early bone marker). Ex vivo culture of newborn condylar cartilage on a chick chorioallantoic membrane showed that after 5 d the cells on the periphery of the explants had begun to express Col1 (bone marker). The cartilage-specific cell lineage-tracing approach in triple mice containing Rosa 26(tdTomato) (tracing marker), 2.3 Col1(GFP) (bone cell marker), and aggrecan Cre(ERT2) (onetime tamoxifen induced) or Col10-Cre (activated from E14.5 throughout adult stage) demonstrated the direct transformation of chondrocytes into bone cells in vivo. This transformation was initiated at the inferior portion of the condylar cartilage, in contrast to the initial ossification site in long bone, which is in the center. Quantitative data from the Col10-Cre compound mice showed that hypertrophic chondrocytes contributed to ~80% of bone cells in subchondral bone, ~70% in a somewhat more inferior region, and ~40% in the most inferior part of the condylar neck (n = 4, P < 0.01 for differences among regions). This multipronged approach clearly demonstrates that a majority of chondrocytes in the fibrocartilaginous condylar cartilage, similar to hyaline cartilage in long bones, directly transform into bone cells during endochondral bone formation. Moreover, ossification is initiated from the inferior portion of mandibular condylar cartilage with expansion in one direction.

MiR-125b inhibits cell biological progression of Ewing's sarcoma by suppressing the PI3K/Akt signalling pathway

OBJECTIVES

Increasing evidence has suggested the close relationship between microRNAs (miRNAs) dysregulation and the carcinogenesis of Ewing's sarcoma (ES), among of which miR-125b has been reported to be decreased in ES tissues recently. Strikingly, ectopic expression of miR-125b could suppress cell proliferation of ES cell line A673, suggesting the tumor suppressor role of miR-125b in ES. However, the other accurate mechanistic functions and relative molecule mechanisms are largely unknown.

MATERIALS AND METHODS

Herein, we completed a series of experiments to investigate the role of miR-125b in Ewing's sarcoma. We restored the expression of miR-125b in ES cell line A673 through transfection with miR-125b mimics. To further understand the role of miR-125b in ES, we detected the effects of miR-125b on the cell proliferation, migration and invasion, cell cycle as well as cell apoptosis.

RESULTS

We found that restored expression of miR-125b in ES cell line A673 inhibited cell proliferation, migration and invasion, arrested cell cycle progression, and induced cell apoptosis. Moreover, bioinformatic prediction suggested the oncogene, phosphoinositide-3-kinase catalytic subunit delta (PIK3CD), was a target gene of miR-125b in ES cells. Further quantitative RT-PCR and western blot assays identified over-expression of miR-125b suppressed the expression of PIK3CD mRNA and protein. PIK3CD participates in regulating the PI3K signaling pathway, which has been reported to play an important role in the development of ES. Suppression of PIK3CD down-regulated the expression of phospho-AKT and phospho-mTOR proteins and inhibited the biologic progression of A673 cells.

CONCLUSIONS

Collectively, these data suggest that miR-125b functions as a tumor suppressor by targeting the PI3K/Akt/mTOR signaling pathway, and may provide potential therapy strategy for ES patients by targeting miRNA expression.

The association between internet addiction and self-injurious behaviour among adolescents

OBJECTIVE

To examine the association between internet addiction and self-injurious behaviour (SIB) in adolescence.

METHODS

Population-based cross-sectional survey of 1618 high school students aged 13-18 years in Guangzhou city, Guangdong Province, PR China. Deliberate SIB was measured using self-reported questionnaire; internet addiction was assessed using the Internet Addiction Test (IAT).

RESULTS

263 (16.3%) participants reported having committed some form of SIB in the past 6 months. 73 (4.5%) had committed SIB 6 times or more, and 157 (9.7%) 1-5 times. The majority of respondents were classified as normal users of the internet (n = 1392, 89.2%), with 158 (10.2%) moderately and 10 (0.6%) severely addicted to the internet. After adjusting for potential confounders, the odds ratio for SIB was 2.0 (95% CI 1.1 to 3.7) for those who were classified as moderately and severely addicted to the internet when compared to the normal group.

CONCLUSIONS

SIB is common in adolescence in the study population in China. Addiction to the internet is detrimental to mental health and increases the risk of self-injury among adolescents. Clinicians need to be aware of potential co-morbidities of other addictions among adolescent self-injured patients.

Mechanical circulatory support is associated with loss of platelet receptors glycoprotein Ibα and glycoprotein VI

Essentials Relationship of acquired von Willebrand disease (VWD) and platelet dysfunction is explored. Patients with ventricular assist devices and on extracorporeal membrane oxygenation are investigated. Acquired VWD and platelet receptor shedding is demonstrated in the majority of patients. Loss of platelet adhesion receptors glycoprotein (GP) Ibα and GPVI may increase bleeding risk.

SUMMARY

Background Ventricular assist devices (VADs) and extracorporeal membrane oxygenation (ECMO) are associated with bleeding that is not fully explained by anticoagulant or antiplatelet use. Exposure of platelets to elevated shear in vitro leads to increased shedding. Objectives To investigate whether loss of platelet receptors occurs in vivo, and the relationship with acquired von Willebrand syndrome (AVWS). Methods Platelet counts, coagulation tests and von Willebrand factor (VWF) analyses were performed on samples from 21 continuous flow VAD (CF-VAD), 20 ECMO, 12 heart failure and seven aortic stenosis patients. Levels of platelet receptors were measured by flow cytometry or ELISA. Results The loss of high molecular weight VWF multimers was observed in 18 of 19 CF-VAD and 14 of 20 ECMO patients, consistent with AVWS. Platelet receptor shedding was demonstrated by elevated soluble glycoprotein (GP) VI levels in plasma and significantly reduced surface GPIbα and GPVI levels in CF-VAD and ECMO patients as compared with healthy donors. Platelet receptor levels were also significantly reduced in heart failure patients. Conclusions These data link AVWS and increased platelet receptor shedding in patients with CF-VADs or ECMO for the first time. Loss of the platelet surface receptors GPIbα and GPVI in heart failure, CF-VAD and ECMO patients may contribute to ablated platelet adhesion/activation, and limit thrombus formation under high/pathologic shear conditions.

A shotgun optical map of the entire Plasmodium falciparum genome

The unicellular parasite Plasmodium falciparum is the cause of human malaria, resulting in 1.7-2.5 million deaths each year. To develop new means to treat or prevent malaria, the Malaria Genome Consortium was formed to sequence and annotate the entire 24.6-Mb genome. The plan, already underway, is to sequence libraries created from chromosomal DNA separated by pulsed-field gel electrophoresis (PFGE). The AT-rich genome of P. falciparum presents problems in terms of reliable library construction and the relative paucity of dense physical markers or extensive genetic resources. To deal with these problems, we reasoned that a high-resolution, ordered restriction map covering the entire genome could serve as a scaffold for the alignment and verification of sequence contigs developed by members of the consortium. Thus optical mapping was advanced to use simply extracted, unfractionated genomic DNA as its principal substrate. Ordered restriction maps (BamHI and NheI) derived from single molecules were assembled into 14 deep contigs corresponding to the molecular karyotype determined by PFGE (ref. 3).

Association between postprandial changes in colonic intraluminal pressure and transit

The aim of this study was to correlate the movement of colonic luminal contents with the changes in intraluminal pressure. Studies were performed in 9 healthy volunteers. Intraluminal pressure was measured with perfused catheter ports in the transverse, splenic flexure, descending, and sigmoid colon. Movement of the luminal contents was measured by following the movement of technetium 99m-ethylenetriamine-pentaacetic acid that was instilled as a bolus in the splenic flexure. During fasting there was very little change in pressure or in the movement of intraluminal contents. After eating a 1000-kcal meal, the tracer moved from the splenic flexure into the transverse colon and the sigmoid colon. Nonpropagating colonic motor activity increased in all colonic segments immediately after eating the meal (p less than 0.05). The increase in motility was significantly greater in the descending colon than in the transverse and sigmoid colon (p less than 0.05). In one-half of the subjects propagating contractions occurred postprandially. The movement of the intraluminal tracer occurred during both types of motility. The nonpropagating contractions were associated with a gradual movement of the luminal contents. The direction of the movement of the contents was determined by the differences in pressure in the different segments of the colon. The propagating contractions were associated with a rapid movement of intraluminal contents. These studies suggest that (a) colonic motility and transit are quiescent during fasting and (b) the transverse colon acts as a mixing and storage area, as retrograde transit into the transverse colon is the characteristic postprandial pattern.

Interstitial volume changes during spreading depression (SD) and SD-like hypoxic depolarization in hippocampal tissue slices

1. Relative interstitial volume (ISV) was estimated from the concentration changes of iontophoretically administered tetramethyl- and tetraethylammonium (TMA+ and TEA+). Spreading depression (SD) was provoked by high K+, and hypoxic SD-like depolarization (HSD) was induced by withdrawing oxygen. 2. Probe ion concentrations increased dramatically and about equally during SD and HSD, except that in a few hypoxic trials signals became transiently smaller than control. Interstitial volume appeared to decrease on the average by approximately 70%. 3. The ISV that remains patent in CA1 region at the height of SD is < 4% of total tissue volume. Probe ions may occasionally have passed through cell membranes for a short time during hypoxic SD.

Central pattern generator for escape swimming in the notaspid sea slug Pleurobranchaea californica

Escape swimming in the notaspid opisthobranch Pleurobranchaea is an episode of alternating dorsal and ventral body flexions that overrides all other behaviors. We have explored the structure of the central pattern generator (CPG) in the cerebropleural ganglion as part of a study of neural network interactions underlying decision making in normal behavior. The CPG comprises at least eight bilaterally paired interneurons, each of which contributes and is phase-locked to the swim rhythm. Dorsal flexion is mediated by hemiganglion ensembles of four serotonin-immunoreactive neurons, the As1, As2, As3, and As4, and an electrically coupled pair, the A1 and A10 cells. When stimulated, A10 commands fictive swimming in the isolated CNS and actual swimming behavior in whole animals. As1-4 provide prolonged, neuromodulatory excitation enhancing dorsal flexion bursts and swim cycle number. Ventral flexion is mediated by the A3 cell and a ventral swim interneuron, IVS, the soma of which is yet unlocated. Initiation of a swim episode begins with persistent firing in A10, followed by recruitment of As1-4 and A1 into dorsal flexion. Recurrent excitation within the As1-4 ensemble and with A1/A10 may reinforce coactivity. Synchrony among swim interneuron partners and bilateral coordination is promoted by electrical coupling among the A1/A10 and As4 pairs, and among unilateral As2-4, and reciprocal chemical excitation between contralateral As1-4 groups. The switch from dorsal to ventral flexion coincides with delayed recruitment of A3, which is coupled electrically to A1, and with recurrent inhibition from A3/IVS to A1/A10. The alternating phase relation may be reinforced by reciprocal inhibition between As1-4 and IVS. Pleurobranchaea's swim resembles that of the nudibranch Tritonia; we find that the CPGs are similar in many details, suggesting that the behavior and network are primitive characters derived from a common pleurobranchid ancestor.

Role of calcium channels in spreading depression in rat hippocampal slices

In the CA1 region of rat hippocampal slices, spreading depression (SD) was provoked by a brief period of hypoxia or by localized application of high potassium solution. We measured extracellular DC voltage (Vo), extracellular potassium concentration ([K+]o) and/or extracellular Ca2+ concentration ([Ca2+]o). SD was provoked under control conditions and also when voltage-gated Ca2+ channels were blocked by application of 2 mM Ni2+ or Co2+. In some experiments, CPP, DNQX, or the two together were also applied to block glutamate receptor-coupled channels. When SD was provoked by hypoxia, these treatments significantly increased the latency of SD onset and decreased the amplitudes of the accompanying delta Vo, delta [Ca2+]o and delta [K+]o. Hypoxia-induced SD was never blocked completely, however and delta [Ca2+]o was reduced at most by 50%. When SD was provoked by application of high K+ solution near the recording site, Ni2+ or Co2+ partially suppressed the Vo and [Ca2+]o shifts but did not block SD altogether. When high K+ solution was applied at a distance, Ni2+ or Co2+ blocked the propagation of SD to the recording site. We conclude that during SD, a significant proportion of the calcium ions flowing into neurons does not pass through voltage-gated or glutamate receptor-linked channels.

Neuronal elements that mediate escape swimming and suppress feeding behavior in the predatory sea slug Pleurobranchaea

1. The white, bilaterally paired A1 interneurons of the cerebropleural ganglion of Pleurobranchaea californica fire rhythmic bursts of action potentials during escape swimming behavior. We studied the role of the A1s in swimming behavior and pattern generation in whole animal and isolated CNS preparations. 2. The escape swim is a cyclic sequence of dorsal and ventral flexions of the body. During the swim, A1 bursts precede and accompany the dorsal flexion phase of the cycle. Hyperpolarization of A1 to prevent spike activity interrupts swimming behavior in the whole animal and fictive swimming in the isolated CNS. Stimulated A1 activity was not observed to cause swimming in whole animals, and was only occasionally sufficient to trigger fictive swimming activity in the isolated CNS. 3. In quiescent whole animal preparations, stimulation of a single A1 normally causes a single dorsal flexion followed by body flexion to the side contralateral to the stimulated cell; characteristically, A1 spike activity stimulates feedback inhibition coinciding with the end of dorsal flexion and the onset of contralateral flexion. 4. A1 spike activity suppresses feeding behavior and causes proboscis retraction in whole animal preparations induced to feed. A1 activity also suppresses fictive feeding driven by stimulation of the critical phasic paracerebral neurons (PCps) of the motor network of feeding in the isolated CNS. Concomitantly, A1 spikes cause potent inhibition of the PCp interneurons. 5. The A1s are specifically excited by noxious mechanical and chemical stimuli, but are not affected by feeding stimuli or the occurrence of feeding behavior. 6. We conclude that the A1 neurons are elements of an escape swimming pattern generator, and that they are probably homologous to the similar C2 neurons of the nudibranch Tritonia diomedea. One of their functions outside of generating the swim pattern may be the suppression of feeding behavior in response to noxious stimulation. These observations provide a neural mechanism for the original observations of the dominance of escape swimming behavior over feeding.

Ion channel involvement in hypoxia-induced spreading depression in hippocampal slices

Rat hippocampal tissue slices were made hypoxic in control medium and in medium containing the ion channel blockers tetraethylammonium (TEA), 4-aminopyridine (4-AP), or tetrodotoxin (TTX). Postsynaptic evoked potentials, extracellular DC potential Vec, and in some experiments extracellular potassium concentration [K+]o were monitored in stratum pyramidale of the CA1 region. TEA (10 mM) decreased the latency of hypoxia-induced spreading depression (SD), and reduced the amplitudes of the changes in Vec and [K+]o. 4-AP (50 microM) also decreased the latency of SD but had no effect on the Vec shift. In most slices, TTX (1 microM) increased SD latency but had no effect on the Vec shift. In some slices, TTX blocked the occurrence of SD.

Escape swim network interneurons have diverse roles in behavioral switching and putative arousal in Pleurobranchaea

Escape swimming in the predatory sea slug Pleurobranchaea is a dominant behavior that overrides feeding, a behavioral switch caused by swim-induced inhibition of feeding command neurons. We have now found distinct roles for the different swim interneurons in acute suppression of feeding during the swim and in a longer-term stimulation of excitability in the feeding network. The identified pattern-generating swim neurons A1, A3, A10, and their follower interneuron A-ci1, suppress feeding motor output partly by excitation of the I1 feeding interneurons, which monosynaptically inhibit both the feeding command neurons, PC(P), PSE, and other major interneurons, the I2s. This mechanism exerts broad inhibition of the feeding network suitable to an escape response; broader than feeding suppression in learned and satiation-induced food avoidance and acting through a different presynaptic pathway. Four intrinsic neuromodulatory neurons of the swim network, the serotonergic As1-4, add little to direct suppression of feeding. Rather, they monosynaptically excite the serotonergic metacerebral giant (MCG) neurons of the feeding network, themselves intrinsic neuromodulators of feeding, as well as a cluster of adjacent serotonergic feeding neurons, with both fast and slow EPSPs. They also provide mild neuromodulatory excitation of the PC(P)/PSE feeding command neurons, and I1 and I2 feeding interneurons, which is masked by inhibition during the swim. As1-4 also excite the serotonergic pedal ganglion G neurons for creeping locomotion. These observations further delineate the nature of the putative serotonergic arousal system of gastropods and suggest a central coordinating role to As1-4.

Safety and immunogenicity of a pentavalent diphtheria, tetanus, pertussis, hepatitis B and polio combination vaccine in infants

INTRODUCTION

The objectives of this study were to evaluate the safety and immunogenicity of a new combination vaccine (DTaP-HB-IPV) containing diphtheria, tetanus, acellular pertussis and hepatitis B (HB) and a new inactivated poliovirus vaccine (IPV) manufactured by GlaxoSmithKline (GSK). This vaccine was given in an all IPV or sequential IPV and oral polio vaccine (OPV) schedule. Another combination vaccine, DTaP-HB (GSK), was similarly evaluated given with OPV or IPV.

METHODS

Four hundred infants were randomized into one of four study groups and immunized at 2, 4 and 6 months of age. Group A received three doses of DTaP-HB-IPV; Group B received DTaP-HB-IPV at 2 and 4 months and DTaP-HB with OPV (Orimune) at 6 months; Group C received three doses of DTaP-HB with licensed IPV (IPOL) administered separately; Group D received separate doses of OPV, DTaP (Infanrix; GSK) and HB (Engerix; GSK). All subjects received conjugate Haemophilus influenzae type b vaccine (Hib) (OmniHIB) at 2, 4 and 6 months of age given at a separate injection site. Subjects who returned at 12 to 18 months of age (229) received booster immunization with DTaP and Hib. Safety was evaluated after each vaccine dose. Blood was drawn before the first dose and one month after the third dose as well as before and after the booster dose.

RESULTS

There were no vaccine-related serious adverse events in any group after any vaccine dose. Minor systemic and local adverse events were also not significantly different among the four groups after any dose. There were no differences in the immune response rates for Hib, HB, polio (types 1, 2 and 3), diphtheria, tetanus or pertussis antigens (pertussis toxin, filamentous hemagglutinin, pertactin) among groups, although there were some quantitative differences in specific antibody titers among groups. DTaP-HB-IPV and DTaP-HB combination vaccines had safety and immunogenicity equivalent to those of standard individually administered vaccines. The new IPV was not inferior to IPOL.

CONCLUSION

Use of the pentavalent combination vaccine would greatly reduce the number of required injections during the first 2 years of life, thereby simplifying the immunization schedule, enhancing compliance and facilitating acceptance of additional injections engendered by introduction of newer vaccines.

High-resolution restriction maps of bacterial artificial chromosomes constructed by optical mapping

Large insert clone libraries have been the primary resource used for the physical mapping of the human genome. Research directions in the genome community now are shifting direction from purely mapping to large-scale sequencing, which in turn, require new standards to be met by physical maps and large insert libraries. Bacterial artificial chromosome libraries offer enormous potential as the chosen substrate for both mapping and sequencing studies. Physical mapping, however, has come under some scrutiny as being "redundant" in the age of large-scale automated sequencing. We report the development and applications of nonelectrophoretic, optical approaches for high-resolution mapping of bacterial artificial chromosome that offer the potential to complement and thereby advance large-scale sequencing projects.

Interstitial space, electrical resistance and ion concentrations during hypotonia of rat hippocampal slices

1. The degree to which mammalian brain cells swell in hypotonic environments has not previously been determined. We exposed hippocampal tissue slices prepared from anaesthetized rats to artificial cerebrospinal fluid from which varying amounts of NaCl had been deleted. Interstitial volume (ISV) change was determined from the volume of dilution of the marker ions tetramethylammonium (TMA+) or tetraethylammonium (TEA+). Tissue electrical resistance was measured as the voltage generated by constant current pulses. 2. ISV decreased as a function of lowered extracellular osmolality (osmotic pressure, pi o), indicating cell swelling. After reaching a minimum, ISV recovered partially, suggesting regulatory volume decrease of cells. After restoring normal pi o the ISV expanded, indicating post-hypotonic cell shrinkage. The electrical resistance of the tissue (Ro) increased when pi o was lowered, due to the reduced ionic strength, as well as restricted ISV. 3. To control for low NaCl concentration, reduced NaCl was replaced by mannitol or fructose. In isosmotic, NaCl-deficient solution, ISV showed inconsistent change, and Ro corrected for ionic strength tended to decrease. 4. Extracellular K+ concentration decreased slightly in low pi o except when spreading depression caused it to increase. Extracellular Ca2+ concentration decreased substantially, consistently and reversibly. Administration of isosmotic low-NaCl concentration solutions caused a similar decrease in extracellular Ca2+ concentrations. We propose that low Na+ concentration in extracellular fluid impaired the extrusion of Ca2+. 5. In severely hypotonic solution, ISV was reduced to 25% of its control volume, corresponding to a mean cell volume increase of at least 11%, probably more. From plotting relative changes in ISV against osmolarity we concluded that, within the range tested, hypotonic cell swelling was not opposed by the close approach of plasma membranes of neighbouring cells.

Activation of phosphatidylinositol 3-kinase/Akt-mammalian target of Rapamycin signaling pathway in the hippocampus is essential for the acquisition of morphine-induced place preference in rats

Hippocampus is a critical structure for the acquisition of morphine-induced conditioned place preference (CPP), which is a usual learning paradigm for assessing drug reward. However, the precise mechanisms remain largely unknown. Phosphatidylinositol 3-kinase (PI3K) and its downstream targets, including Akt, mammalian target of Rapamycin (mTOR) and 70-kDa ribosomal S6 kinase (p70S6K), are critical molecules implicated in learning and memory. Here, we tested the role of PI3K/Akt-mTOR-p70S6K signaling pathway in morphine-induced CPP in the hippocampus. Our results showed that the acquisition of morphine CPP increased phosphorylation of Akt in the hippocampal CA3, but not in the nucleus accumbens (NAc), the ventral tegmental area (VTA) or the CA1. Moreover, the phosphorylated Akt exclusively expressed in the CA3 neurons. Likewise, levels of phosphorylated mTOR and p70S6K were significantly enhanced in the CA3 following morphine CPP. The alterations of these phosphorylated proteins are positively correlated with the acquisition of morphine CPP. More importantly, microinjection of PI3K inhibitor (LY294002) or mTOR inhibitor (Rapamycin) into the CA3 prevented the acquisition of CPP and inhibited the activation of PI3K-Akt signaling pathway. In addition, pre-infusion of β-FNA (β-funaltrexamine hydrochloride), a selective irreversible μ opioid receptor antagonist, into CA3 significantly prevented the acquisition of CPP and impaired Akt phosphorylation. All these results strongly implied that the PI3K-Akt signaling pathway activated by μ opioid receptor in hippocampal CA3 plays an important role in acquisition of morphine-induced CPP.

Default network connectivity as a vulnerability marker for obsessive compulsive disorder

BACKGROUND

Aberrant functional connectivity within the default network is generally assumed to be involved in the pathophysiology of obsessive compulsive disorder (OCD); however, the genetic risk of default network connectivity in OCD remains largely unknown.

METHOD

Here, we systematically investigated default network connectivity in 15 OCD patients, 15 paired unaffected siblings and 28 healthy controls. We sought to examine the profiles of default network connectivity in OCD patients and their siblings, exploring the correlation between abnormal default network connectivity and genetic risk for this population.

RESULTS

Compared with healthy controls, OCD patients exhibited reduced strength of default network functional connectivity with the posterior cingulate cortex (PCC), and increased functional connectivity in the right inferior frontal lobe, insula, superior parietal cortex and superior temporal cortex, while their unaffected first-degree siblings only showed reduced local connectivity in the PCC.

CONCLUSIONS

These findings suggest that the disruptions of default network functional connectivity might be associated with family history of OCD. The decreased default network connectivity in both OCD patients and their unaffected siblings may serve as a potential marker of OCD.