The Architecture of SARS-CoV-2 Transcriptome

SARS-CoV-2 is a betacoronavirus responsible for the COVID-19 pandemic. Although the SARS-CoV-2 genome was reported recently, its transcriptomic architecture is unknown. Utilizing two complementary sequencing techniques, we present a high-resolution map of the SARS-CoV-2 transcriptome and epitranscriptome. DNA nanoball sequencing shows that the transcriptome is highly complex owing to numerous discontinuous transcription events. In addition to the canonical genomic and 9 subgenomic RNAs, SARS-CoV-2 produces transcripts encoding unknown ORFs with fusion, deletion, and/or frameshift. Using nanopore direct RNA sequencing, we further find at least 41 RNA modification sites on viral transcripts, with the most frequent motif, AAGAA. Modified RNAs have shorter poly(A) tails than unmodified RNAs, suggesting a link between the modification and the 3' tail. Functional investigation of the unknown transcripts and RNA modifications discovered in this study will open new directions to our understanding of the life cycle and pathogenicity of SARS-CoV-2.

Direct activation of capsaicin receptors by products of lipoxygenases: endogenous capsaicin-like substances

Capsaicin, a pungent ingredient of hot peppers, causes excitation of small sensory neurons, and thereby produces severe pain. A nonselective cation channel activated by capsaicin has been identified in sensory neurons and a cDNA encoding the channel has been cloned recently. However, an endogenous activator of the receptor has not yet been found. In this study, we show that several products of lipoxygenases directly activate the capsaicin-activated channel in isolated membrane patches of sensory neurons. Among them, 12- and 15-(S)-hydroperoxyeicosatetraenoic acids, 5- and 15-(S)-hydroxyeicosatetraenoic acids, and leukotriene B(4) possessed the highest potency. The eicosanoids also activated the cloned capsaicin receptor (VR1) expressed in HEK cells. Prostaglandins and unsaturated fatty acids failed to activate the channel. These results suggest a novel signaling mechanism underlying the pain sensory transduction.

Cognitive-perceptual, interpersonal, and disorganized features of schizotypal personality

While two factors are currently thought to underlie individual differences in schizotypal personality, three factors may best explain schizotypal traits. This study used confirmatory factor analysis to assess five competing models of schizotypal personality in the general population: null model, one-factor model, simple two-factor model, Kendler two-factor model, and three-factor model. The computer program LISREL was used to analyze Schizotypal Personality Questionnaire subscale scores that reflect the nine traits of schizotypal personality. The scores were obtained from (1) a sample of 822 undergraduates and (2) a replication sample of 102 subjects drawn from the community. Results indicate replicable support for a three-factor model reflecting cognitive-perceptual, interpersonal, and disorganized latent factors. Low intercorrelations between the first two factors and the lack of fit by a one-factor model are partially inconsistent with recent notions that a single vulnerability dimension underlies schizotypal personality. It is argued that future investigations should assess the correlates of all three schizotypal factors in clinical and nonclinical samples in addition to the two more traditional factors. It is hypothesized that three factors of schizophrenic symptomatology observed in recent studies may reflect an exaggeration of three analogous factors found in the general population.

Lack of the burst firing of thalamocortical relay neurons and resistance to absence seizures in mice lacking alpha(1G) T-type Ca(2+) channels

T-type Ca(2+) currents have been proposed to be involved in the genesis of spike-and-wave discharges, a sign of absence seizures, but direct evidence in vivo to support this hypothesis has been lacking. To address this question, we generated a null mutation of the alpha(1G) subunit of T-type Ca(2+) channels. The thalamocortical relay neurons of the alpha(1G)-deficient mice lacked the burst mode firing of action potentials, whereas they showed the normal pattern of tonic mode firing. The alpha(1G)-deficient thalamus was specifically resistant to the generation of spike-and-wave discharges in response to GABA(B) receptor activation. Thus, the modulation of the intrinsic firing pattern mediated by alpha(1G) T-type Ca(2+) channels plays a critical role in the genesis of absence seizures in the thalamocortical pathway.

Universal behavior of load distribution in scale-free networks

We study a problem of data packet transport in scale-free networks whose degree distribution follows a power law with the exponent gamma. Load, or "betweenness centrality," of a vertex is the accumulated total number of data packets passing through that vertex when every pair of vertices sends and receives a data packet along the shortest path connecting the pair. It is found that the load distribution follows a power law with the exponent delta approximately 2.2(1), insensitive to different values of gamma in the range, 2 < gamma < or = 3, and different mean degrees, which is valid for both undirected and directed cases. Thus, we conjecture that the load exponent is a universal quantity to characterize scale-free networks.

Akt/PKB promotes cancer cell invasion via increased motility and metalloproteinase production

The Akt/protein kinase B (PKB) serine/threonine kinase is well known as an important mediator of many cell survival signaling pathways. Here, we demonstrate for the first time a major role of Akt/PKB in the cell invasion properties of the highly metastatic cell line HT1080. Using confocal microscopic analyses of live samples, we found Akt/PKB to be localized in the leading edge membrane area of migrating HT1080 cells. This localization was dependent on phosphoinositide 3-kinase and required the lipid binding ability of the phosphoinositide binding pleckstrin homology domain of Akt/PKB. We examined the possible function of Akt/PKB in HT1080 invasion. Surprisingly, Akt/PKB potently promoted HT1080 invasion, by increasing cell motility and matrix metalloproteinase-9 (MMP-9) production, in a manner highly dependent on its kinase activity and membrane-translocating ability. The increase in MMP-9 production was mediated by activation of nuclear factor-kappaB transcriptional activity by Akt/PKB. However, Akt/PKB did not affect the cell-cell or cell-matrix adhesion properties of HT1080. Our findings thus establish Akt/PKB as a major factor in the invasive abilities of cancer cells.

G-protein beta gamma-subunits activate the cardiac muscarinic K+-channel via phospholipase A2

Muscarinic receptors of cardiac pacemaker and atrial cells are linked to a potassium channel (IK.ACh) by a pertussis toxin-sensitive GTP-binding protein. The dissociation of G-proteins leads to the generation of two potential transducing elements, alpha-GTP and beta gamma. IK.ACh is activated by G-protein alpha- and beta gamma-subunits applied to the intracellular surface of inside-out patches of membrane. beta gamma has been shown to activate the membrane-bound enzyme phospholipase A2 in retinal rods. Arachidonic acid, which is produced from the action of phospholipase A2 on phospholipids, is metabolized to compounds which may act as second messengers regulating ion channels in Aplysia. Muscarinic receptor activation leads to the generation of arachidonic acid in some cell lines. We therefore tested the hypothesis that beta gamma activates IK.ACh by stimulation of phospholipase A2. When patches were first incubated with antibody that blocks phospholipase A2 activity, or with the lipoxygenase inhibitor, nordihydroguaiaretic acid, beta gamma failed to activate IK.ACh. Arachidonic acid and several of its metabolites derived from the 5-lipoxygenase pathway, activated the channel. Blockade of the cyclooxygenase pathway did not inhibit arachidonic acid-induced channel activation. We conclude that the beta gamma-subunit of G-proteins activates IK.ACh by stimulating the production of lipoxygenase-derived second messengers.

A comparison of twice-daily exenatide and biphasic insulin aspart in patients with type 2 diabetes who were suboptimally controlled with sulfonylurea and metformin: a non-inferiority study

AIMS/HYPOTHESIS

The aim of this 52-week, open-label, non-inferiority trial was to compare the safety and efficacy of exenatide (an incretin mimetic) with that of biphasic insulin aspart.

MATERIALS AND METHODS

Patients on metformin and a sulfonylurea were randomised to exenatide (n = 253; 5 microg twice daily for 4 weeks, 10 microg thereafter) or biphasic insulin aspart (n = 248; twice-daily doses titrated for optimal glucose control), while continuing with metformin and sulfonylurea treatment.

RESULTS

Glycaemic control achieved with exenatide was non-inferior to that achieved with biphasic insulin aspart (mean+/-SEM, HbA(1c) change: exenatide -1.04 +/- 0.07%, biphasic insulin aspart -0.89 +/- 0.06%; difference -0.15 [95% CI -0.32 to 0.01]%). Exenatide-treated patients lost weight, while patients treated with biphasic insulin aspart gained weight [between-group difference -5.4 (95% CI -5.9 to -5.0) kg]. Both treatments reduced fasting serum glucose (exenatide -1.8 +/- 0.2 mmol/l, p < 0.001; biphasic insulin aspart -1.7 +/- 0.2 mmol/l, p < 0.001). Greater reductions in postprandial glucose excursions following morning (p < 0.001), midday (p = 0.002) and evening meals (p < 0.001) were observed with exenatide. The withdrawal rate was 21.3% (54/253) for exenatide and 10.1% (25/248) for biphasic insulin aspart. Nausea (33% incidence, 3.5% discontinuation) was the most common adverse event observed with exenatide.

CONCLUSIONS/INTERPRETATION

Exenatide treatment resulted in HbA(1c) reduction similar to biphasic insulin aspart and provided better postprandial glycaemic control, making it a potential alternative for the treatment of type 2 diabetes. Treatment with biphasic insulin aspart was associated with weight gain and lower risk of adverse gastrointestinal events. Although the availability of glucose-lowering agents associated with weight reduction may be considered a therapeutic advance, the long-term implications of progressive weight reduction observed with exenatide have yet to be defined.

Impact of collateral flow on tissue fate in acute ischaemic stroke

BACKGROUND

Collaterals may sustain penumbra prior to recanalisation yet the influence of baseline collateral flow on infarct growth following endovascular therapy remains unknown.

METHODS

Consecutive patients underwent serial diffusion and perfusion MRI before and after endovascular therapy for acute cerebral ischaemia. We assessed the relationship between MRI diffusion and perfusion lesion indices, angiographic collateral grade and infarct growth. Tmax perfusion lesion maps were generated and diffusion-perfusion mismatch regions were divided into Tmax >or=4 s (severe delay) and Tmax >or=2 but <4 s (mild delay).

RESULTS

Among 44 patients, collateral grade was poor in 7 (15.9%), intermediate in 20 (45.5%) and good in 17 (38.6%) patients. Although diffusion-perfusion mismatch volume was not different depending on the collateral grade, patients with good collaterals had larger areas of milder perfusion delay than those with poor collaterals (p = 0.005). Among 32 patients who underwent day 3-5 post-treatment MRIs, the degree of pretreatment collateral circulation (r = -0.476, p = 0.006) and volume of diffusion-perfusion mismatch (r = 0.371, p = 0.037) were correlated with infarct growth. Greatest infarct growth occurred in patients with both non-recanalisation and poor collaterals. Multiple regression analysis revealed that pretreatment collateral grade was independently associated with infarct growth.

CONCLUSION

Our data suggest that angiographic collateral grade and penumbral volume interactively shape tissue fate in patients undergoing endovascular recanalisation therapy. These angiographic and MRI parameters provide complementary information about residual blood flow that may help guide treatment decision making in acute cerebral ischaemia.

TASK-3, a new member of the tandem pore K(+) channel family

We have isolated from the rat cerebellum cDNA library a complementary DNA encoding a new member of the tandem pore K(+) channel family. Its amino acid sequence shares 54% identity with that of TASK-1, but less than 30% with those of TASK-2 and other tandem pore K(+) channels (TWIK, TREK, TRAAK). Therefore, the new clone was named TASK-3. Reverse transcriptase-polymerase chain reaction analysis showed that TASK-3 mRNA is expressed in many rat tissues including brain, kidney, liver, lung, colon, stomach, spleen, testis, and skeletal muscle, and at very low levels in the heart and small intestine. When expressed in COS-7 cells, TASK-3 exhibited a time-independent, noninactivating K(+)-selective current. Single-channel conductance was 27 pS at -60 mV and 17 pS at 60 mV in symmetrical 140 mM KCl. TASK-3 current was highly sensitive to changes in extracellular pH (pH(o)), a hallmark of the TASK family of K(+) channels. Thus, a change in pH(o) from 7.2 to 6.4 and 6.0 decreased TASK-3 current by 74 and 96%, respectively. Mutation of histidine at position 98 to aspartate abolished pH(o) sensitivity. TASK-3 was blocked by barium (57%, 3 mM), quinidine (37%, 100 microM), and lidocaine (62%, 1 mM). Thus, TASK-3 is a new member of the acid-sensing K(+) channel subfamily (TASK).

Potassium channels in cardiac cells activated by arachidonic acid and phospholipids

Two types of potassium-selective channels activated by intracellular arachidonic acid or phosphatidylcholine have been found in neonatal rat atrial cells. In inside-out patches, arachidonic acid and phosphatidylcholine each opened outwardly rectifying potassium-selective channels with conductances of 160 picosiemens (IK.AA) and 68 picosiemens (IK.PC), respectively. These potassium channels were not sensitive to internally applied adenosine triphosphate (ATP), magnesium, or calcium. Lowering the intracellular pH from 7.2 to 6.8 or 6.4 reversibly increased IK.AA channel activity three- or tenfold, respectively. A number of fatty acid derivatives were tested for their ability to activate IK.AA. These potassium-selective channels may help explain the increase in potassium conductance observed in ischemic cells and raise the possibility that fatty acid derivatives act as second messengers.

Fast selective black blood MR imaging

To overcome the problems associated with gradient-echo (GRE) magnetic resonance (MR) angiography ("bright blood" imaging) and "black blood" imaging with presaturated spin-echo (SE) pulse sequences, the authors devised a new approach for black blood imaging. Their method, selective preinversion fast imaging with steady precession (turboFISP), uses a segmented GRE sequence for fast data acquisition. Nulling of vascular signal results, and stationary tissue appears bright. The method was compared with flow-compensated GRE imaging in a phantom and with GRE imaging and presaturated SE imaging in seven healthy volunteers and nine patients with various cardiac diseases. With phantoms, the selective preinversion turboFISP sequence produced better flow contrast than did GRE sequences. Selective preinversion turboFISP was often superior to SE imaging for depicting vessel lumina, particularly in patients with slowly flowing blood. Arteries appeared dark in selective black blood angiograms, but veins did not. Selective preinversion turboFISP can be used with bright blood GRE imaging to depict vessel lumina, and its capability for image acquisition within a breath hold and with cardiac gating minimizes artifacts from respiration and motion of the vessel wall.

The Arabidopsis sugar-insensitive mutants sis4 and sis5 are defective in abscisic acid synthesis and response

Although soluble sugar levels affect many aspects of plant development and physiology, little is known about the mechanisms by which plants respond to sugar. Here we report the isolation of 13 sugar-insensitive (sis) mutants of Arabidopsis that, unlike wild-type plants, are able to form expanded cotyledons and true leaves when germinated on media containing high concentrations of glucose or sucrose. The sis4 and sis5 mutants are allelic to the ABA-biosynthesis mutant aba2 and the ABA-insensitive mutant abi4, respectively. In addition to being insensitive to glucose and sucrose, the sis4/aba2 and sis5/abi4 mutants also display decreased sensitivity to the inhibitory effects of mannose on early seedling development. Mutations in the ABI5 gene, but not mutations in the ABI1, ABI2 or ABI3 genes, also lead to weak glucose- and mannose-insensitive phenotypes. Wild-type and mutant plants show similar responses to the effects of exogenous sugar on chlorophyll and anthocyanin accumulation, indicating that the mutants are not defective in all sugar responses. These results indicate that defects in ABA metabolism and some, but not all, defects in ABA response can also alter response to exogenous sugar.

Atmospheric brown clouds: impacts on South Asian climate and hydrological cycle

South Asian emissions of fossil fuel SO(2) and black carbon increased approximately 6-fold since 1930, resulting in large atmospheric concentrations of black carbon and other aerosols. This period also witnessed strong negative trends of surface solar radiation, surface evaporation, and summer monsoon rainfall. These changes over India were accompanied by an increase in atmospheric stability and a decrease in sea surface temperature gradients in the Northern Indian Ocean. We conducted an ensemble of coupled ocean-atmosphere simulations from 1930 to 2000 to understand the role of atmospheric brown clouds in the observed trends. The simulations adopt the aerosol radiative forcing from the Indian Ocean experiment observations and also account for global increases in greenhouse gases and sulfate aerosols. The simulated decreases in surface solar radiation, changes in surface and atmospheric temperatures over land and sea, and decreases in monsoon rainfall are similar to the observed trends. We also show that greenhouse gases and sulfates, by themselves, do not account for the magnitude or even the sign in many instances, of the observed trends. Thus, our simulations suggest that absorbing aerosols in atmospheric brown clouds may have played a major role in the observed regional climate and hydrological cycle changes and have masked as much as 50% of the surface warming due to the global increase in greenhouse gases. The simulations also raise the possibility that, if current trends in emissions continue, the subcontinent may experience a doubling of the drought frequency in the coming decades.

Phospholipase C isozymes selectively couple to specific neurotransmitter receptors

A variety of extracellular signals are transduced across the cell membrane by the enzyme phosphoinositide-specific phospholipase C-beta (PLC-beta) coupled with guanine-nucleotide-binding G proteins. There are four isoenzymes of PLC-beta, beta1-beta4, but their functions in vivo are not known. Here we investigate the role of PLC-beta1 and PLC-beta4 in the brain by generating null mutations in mice: we found that PLCbeta1-/- mice developed epilepsy and PLCbeta4-/- mice showed ataxia. We determined the molecular basis of these phenotypes and show that PLC-beta1 is involved in signal transduction in the cerebral cortex and hippocampus by coupling predominantly to the muscarinic acetylcholine receptor, whereas PLC-beta4 works through the metabotropic glutamate receptor in the cerebellum, illustrating how PLC-beta isoenzymes are used to generate different functions in the brain.

Randomised controlled trial of recombinant tissue plasminogen activator versus urokinase in the treatment of acute pulmonary embolism

The effect of intravenous recombinant human tissue-type plasminogen activator (rt-PA) was compared with that of urokinase in 45 patients with angiographically documented pulmonary embolism (PE) in a randomised controlled trial. The two principal end-points were clot lysis at 2 h, as assessed by angiography, and pulmonary reperfusion at 24 h, as assessed by perfusion lung scanning. All patients received the full dose of rt-PA but urokinase infusions were terminated prematurely (on average after 18 h) in 9 patients because of allergy in 1 and uncontrollable bleeding in 8. By 2 h, 82% of rt-PA-treated patients showed clot lysis, compared with 48% of urokinase-treated patients (p = 0.008; 95% CI for the difference = 10-58%). Improvement in lung scan reperfusion at 24 h was identical in the two treatment groups. The reduction in fibrinogen did not differ significantly between the rt-PA and urokinase groups (45% vs 39% at 2 h and 34% vs 40% at 24 h). The results indicate that in the dose regimens employed, rt-PA acts more rapidly and is safer than urokinase in the treatment of acute PE.

Prevalence and mutational determinants of high tumor mutation burden in breast cancer

BACKGROUND

High tumor mutation burden (TMB) can benefit immunotherapy for multiple tumor types, but the prevalence of hypermutated breast cancer is not well described. The aim of this study was to evaluate the frequency, mutational patterns, and genomic profile of hypermutated breast cancer.

PATIENTS AND METHODS

We used de-identified data from individuals with primary or metastatic breast cancer from six different publicly available genomic studies. The prevalence of hypermutated breast cancer was determined among 3969 patients' samples that underwent whole exome sequencing or gene panel sequencing. The samples were classified as having high TMB if they had ≥10 mutations per megabase (mut/Mb). An additional eight patients were identified from a Dana-Farber Cancer Institute cohort for inclusion in the hypermutated cohort. Among the patients with high TMB, the mutational patterns and genomic profiles were determined. A subset of patients was treated with regimens containing PD-1 inhibitors.

RESULTS

The median TMB was 2.63 mut/Mb. The median TMB significantly varied according to the tumor subtype (HR-/HER2- >HER2+ >HR+/HER2-, P < 0.05) and sample type (metastatic > primary, P = 2.2 × 10^-16). Hypermutated tumors were found in 198 patients (5%), with enrichment in metastatic versus primary tumors (8.4% versus 2.9%, P = 6.5 × 10^-14). APOBEC activity (59.2%), followed by mismatch repair deficiency (MMRd; 36.4%), were the most common mutational processes among hypermutated tumors. Three patients with hypermutated breast cancer-including two with a dominant APOBEC activity signature and one with a dominant MMRd signature-treated with pembrolizumab-based therapies derived an objective and durable response to therapy.

CONCLUSION

Hypermutation occurs in 5% of all breast cancers with enrichment in metastatic tumors. Different mutational signatures are present in this population with APOBEC activity being the most common dominant process. Preliminary data suggest that hypermutated breast cancers are more likely to benefit from PD-1 inhibitors.

Regulation of peripheral lymph node genesis by the tumor necrosis factor family member TRANCE

Proper lymph node (LN) development requires tumor necrosis factor-related activation-induced cytokine (TRANCE) expression. Here we demonstrate that the defective LN development in TRANCE(-/)- mice correlates with a significant reduction in lymphotoxin (LT)alphabeta(+)alpha(4)beta(7)(+)CD45(+)CD4(+)CD3(-) cells and their failure to form clusters in rudimentary mesenteric LNs. Transgenic TRANCE overexpression in TRANCE(-/)- mice results in selective restoration of this cell population into clusters, and results in full LN development. Transgenic TRANCE-mediated restoration of LN development requires LTalphabeta expression on CD45(+) CD4(+)CD3(-) cells, as LNs could not be induced in LTalpha(-/)- mice. LTalpha(-/)- mice also showed defects in the fate of CD45(+)CD4(+)CD3(-) cells similar to TRANCE(-/)- mice. Thus, we propose that both TRANCE and LTalphabeta regulate the colonization and cluster formation by CD45(+) CD4(+)CD3(-) cells in developing LNs, the degree of which appears to correlate with the state of LN organogenesis.

TREK-2, a new member of the mechanosensitive tandem-pore K+ channel family

Recently, several mammalian K(+) channel subunits (TWIK, TREK-1, TRAAK, and TASK) possessing four transmembrane segments and two pore-forming domains have been identified. We report the cloning of a new member of this tandem-pore K(+) channel from a rat cerebellum cDNA library. It is a 538-amino acid protein and shares 65% amino acid sequence identity with TREK-1. Therefore, the new clone was named TREK-2. Unlike TREK-1, whose mRNA has been reported to be expressed in many different tissues, TREK-2 mRNA is expressed mainly in the cerebellum, spleen, and testis as judged by reverse transcriptase-polymerase chain reaction and Northern blot analysis. Expression of TREK-2 in COS-7 cells induced a time-independent and non-inactivating K(+)-selective current. TREK-2 was partially blocked (36%) by 2 mm Ba(2+). In symmetrical 150 mm KCl, the single-channel conductances were 110 picosiemens at -40 mV and 68 picosiemens at +40 mV, and the mean open time was 0.9 ms at -40 mV. TREK-2 was activated by membrane stretch or acidic pH. At -40 mm Hg pressure, channel activity increased 10-fold above the basal level. TREK-2 was also activated by arachidonic acid and other naturally occurring unsaturated free fatty acids. These results show that TREK-2 is a new member of the tandem-pore K(+) channel family and belongs to the class of mechanosensitive and fatty acid-stimulated K(+) channels.

Betweenness centrality correlation in social networks

Scale-free (SF) networks exhibiting a power-law degree distribution can be grouped into the assortative, dissortative, and neutral networks according to the behavior of the degree-degree correlation coefficient. Here we investigate the betweenness centrality (BC) correlation for each type of SF networks. While the BC-BC correlation coefficients behave similarly to the degree-degree correlation coefficients for the dissortative and neutral networks, the BC correlation is nontrivial for the assortative ones found mainly in social networks. The mean BC of neighbors of a vertex with BC g(i) is almost independent of g(i), implying that each person is surrounded by almost the same influential environments of people no matter how influential the person may be.

Isolation and characterization of a thermophilic lipase from bacillus thermoleovorans ID-1

A thermophilic microorganism, Bacillus thermoleovorans ID-1, isolated from hot springs in Indonesia, showed extracellular lipase activity and high growth rates on lipid substrates at elevated temperatures. On olive oil (1.5%, w/v) as the sole carbon source, the isolate ID-1 grew very rapidly at 65 degrees C with its specific growth rate (2.50 h(-1)) and its lipase activity reached the maximum value of 520 U l(-1) during the late exponential phase and then decreased. In addition to this, isolate ID-1 could grow on a variety of lipid substrates such as oils (olive oil, soybean oil and mineral oil), triglycerides (triolein, tributyrin) and emulsifiers (Tween 20, 40). The excreted lipase of ID-1 was purified 223-fold to homogeneity by ammonium sulfate precipitation, DEAE-Sephacel ion-exchange chromatography and Sephacryl S-200 gel filtration chromatography. As a result, the relative molecular mass of the lipase was determined to be 34 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme showed optimal activity at 70-75 degrees C and pH 7.5 and exhibited 50% of its original activity after 1 h incubation at 60 degrees C and 30 min at 70 degrees C and its catalytic function was activated in the presence of Ca(2+) or Zn(2+).

Neurogenesis in adolescent brain is potently inhibited by ethanol

Adolescence is a period of progressive changes in brain that likely contribute to the maturation of behavior. Human adolescents consume large amounts of ethanol. To investigate the effects of ethanol on adolescent neural progenitor cells, male rats (35-40 days old) were treated with an acute dose of ethanol (1.0, 2.5 or 5.0 g/kg, i.g.) or vehicle that resulted in peak blood levels of 33, 72, and 131 mg/dl, respectively. Bromodeoxyuridine (300 mg/kg i.p.) was administered to label dividing cells and rats were killed at 5 h to assess proliferation or at 28 days to assess cell survival and differentiation. After 5 h, bromodeoxyuridine-immunoreactivity was reduced by 63, 97 and 99% in the rostral migratory stream and 34, 71 and 99% in the subventricular zone by 1.0, 2.5 and 5.0 g/kg of ethanol respectively. In the dentate gyrus, ethanol reduced bromodeoxyuridine-immunoreactivity by 29, 40, and 78% at the three doses respectively. The density of doublecortin immunoreactivity was decreased after 3 days and the number of bromodeoxyuridine+ cells remained decreased at 28 days when most hippocampal bromodeoxyuridine+ cells coexpressed neuronal nuclei, a neuronal marker. These studies indicate that the adolescent brain is very sensitive to acute ethanol inhibition of neurogenesis.

PLC-beta1, activated via mGluRs, mediates activity-dependent differentiation in cerebral cortex

During development of the cerebral cortex, the invasion of thalamic axons and subsequent differentiation of cortical neurons are tightly coordinated. Here we provide evidence that glutamate neurotransmission triggers a critical signaling mechanism involving the activation of phospholipase C-beta1 (PLC-beta1) by metabotropic glutamate receptors (mGluRs). Homozygous null mutation of either PLC-beta1 or mGluR5 dramatically disrupts the cytoarchitectural differentiation of 'barrels' in the mouse somatosensory cortex, despite segregation in the pattern of thalamic innervation. Furthermore, group 1 mGluR-stimulated phosphoinositide hydrolysis is dramatically reduced in PLC-beta1-/- mice during barrel development. Our data indicate that PLC-beta1 activation via mGluR5 is critical for the coordinated development of the neocortex, and that presynaptic and postsynaptic components of cortical differentiation can be genetically dissociated.