Pseudomonas acidovorans: a bacterium capable of mineralizing 2-chloroaniline

Prolonged adaptation of Ca-alginate immobilized cells of Pseudomonas acidovorans CA28 to a mixture of 3-chloroaniline (3-CA)¹) and 2-CA and subsequently to 2-CA as sole substrate led to the isolation of another strain, termed CA50 with the additional capability of utilizing 2-CA as sole source of carbon, nitrogen, and energy. Batch-degradation of 190 mg/l of 2-CA at pH 6.1 by this newly isolated strain was achieved within 3 days, at higher concentrations up to 0.6 g/l increasing lag-phases and degradation periods were observed. Except chloride and ammonium no further metabolites were detectable in the medium. Mineralization of 2-CA proceeds via the modified ortho-cleavage pathway as demonstrated by the presence of catechol 1,2-dioxygenase (C120) activity, which is characterized by its substrate specificity and elution behaviour on DEAE-cellulose.     

Critical steps in degradation of chloroaromatics by rhodococci I. Initial enzyme reactions involved in catabolism of aniline,phenol and benzoate by Rhodococcus sp. An 117 and An 213

Two bacterial isolates (i.e. strains An 117 and An 213) capable of growing with aniline, phenol as well as benzoate as the sole carbon and energy source were studied with respect to (i) their taxonomic position, (ii) the enzyme reactions which initiate catabolism of the respective aromatic compounds, and (iii) the general type of regulation of the respective enzymes. Both isolates were established to be representatives of the actinomycete-genus Rhodococcus. Experiments with resting cells and cell-free extracts, respectively, revealed that in the two strains under study catabolism of each of the unsubstituted aromatic compounds occurs via the β-ketoadipate pathway (with catechol as the central metabolite) due to the action of inducible enzymes. Although being potent inducers of the ring-cleaving catechol 1,2-dioxygenase in strains An 117 and An 213, all of the monochlorinated derivatives of aniline, phenol and benzoate, respectively, failed to support cell growth of the organisms. Cis, cis-muconic acid proved to be non-metabolizable by resting An 117 and An 213 cells, although substantial (inducible) muconate cycloisomerase activity was detectable in crude extracts prepared from the respective cell preparations. NADPH-depending phenol hydroxylase activity could be demonstrated in crude extracts from phenol-grown An 117 and An 213 cells. Evidence is presented that in both Rhodococcus strains under study substantial de novo synthesis of at least the initial aromatics-oxygenating enzymes can be induced by phenol and aniline, respectively, even in the presence of either succinate (An 117) or acetate (An 213) which are known to be ortho-pathway catabolites.     

Unspecific degradation of halogenated phenols by the soil fungus Penicillium frequentans Bi 7/2

Resting phenol-grown mycelia of the fungus Penicillium frequentans strain Bi 7/2 were shown to be capable of metabolizing various monohalogenated phenols as well as 3,4-dichlorophenol. 2,4.dichlorophenol could be metabolized in the presence of phenol as cosubstrate. In the first degradation step the halogenated phenols were oxidized to the corresponding halocatechols. Halocatechols substituted in para-position (4-halocatechols) were further degraded under formation of 4-carboxymethylenbut-2-en-4-olide. A partial dehalogenation took place splitting the ring system. 3-Halocatechols were cleaved to 2-halomuconic acids as dead end metabolites without a dehalogenation step. Dichlorophenols were only transformed to the corresponding catechols. In addition 3,5-dichlorocatechol was O-methylated to give two isomers of dichloroguaiacol. The halogenated catechols with the exception of 4-fluorocatechol partly polymerized oxidatively in the culture fluid to form insoluble dark-brown products. The degradation of halophenols are due to the action of unspecific intracellular enzymes responsible for phenol catabolism (phenol hydroxylase. catechol-1,2-dioxygenase, muconate cycloisomerase I).     

Transplantation of cultured astrocytes attenuates degenerative changes in rats with kainic acid-induced brain damage

Viability of astrocyte grafts introduced into CA1 pyramidal layer of the left dorsal hippocampus after injection of kainic acid into this brain region and the effects of these grafts on the hippocampus and amygdala were studied on Wistar rats. In rats with astrocyte grafts the degree of destruction in fields CA1-CA2 of the dorsal and ventral hippocampus, fields CA3-CA4 of the ventral hippocampus, and central and basolateral amygdala was lower compared to animals with kainic acid-induced hippocampal damage and control rats; destructions in the dentate fascia were absent. Our results suggest that astrocyte grafts stimulate neurogenesis in the mature brain of recipient rats with kainic acid-induced brain damage. __________ Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 140, No. 12, pp. 627–632, December, 2005     

The facilitative effects of bilobalide,a unique constituent of <Emphasis Type="Italic">Ginkgo biloba</Emphasis>, on synaptic transmission and plasticity in hippocampal subfields

Bilobalide, a unique constituent of Ginkgo biloba, has been reported to potentiate population spikes in hippocampal CA1 pyramidal cells and to protect the brain against cell death. In this study, the effects of bilobalide on synaptic transmission and its plasticity in rat hippocampal subfields were electrophysiologically investigated. Bilobalide (50 μM) significantly potentiated the input–output relationship at Schaffer collateral (SC)-CA1 synapses but not at medial perforant path (MPP)-dentate gyrus (DG), lateral perforant path (LPP)-DG, or mossy fiber (MF)-CA3 synapses. Facilitative effects of bilobalide on synaptic plasticity were only observed at MPP-DG synapses, in which the induction of long-term depression was blocked in the presence of bilobalide. However, no effect on synaptic plasticity was observed at SC-CA1 synapses. These results suggest that bilobalide has differential effects on synaptic efficacy in each hippocampal subfield.     

Ammon's horn commissural responses in young rabbits.

Different responses evoked by stimulation of contralateral hippocampus at various levels are examined in new-born rabbits up to 1 month of age. Commissural fibres coming from the CA3-CA4 reach the contralateral regio superior (CA1) essentially at the st. oriens levels. CA1 responses elicited by stimulation of the contralateral CA1 in the st. oriens (commissural CA3 fibres) or in the st. radiatum (Schaffer's collaterals) are present at any age. For the regio inferior (CA3-CA4), the distribution of commissural fibres is more diffuse. Before 5--6 days, CA3-CA4 fields do not respond to a contralateral stimulation and do not give contralateral responses, showing that fibres and cells are not yet organized.     

Calbindin D28k-containing nonpyramidal cells in the rat hippocampus: their immunoreactivity for GABA and projection to the medial septum.

Calbindin D28k-containing non-pyramidal cells were found in all layers and subfields of the hippocampus, with the highest frequency in stratum radiatum of the CA1-CA3 subfields. A large number of these neurons had a vertically oriented dendritic tree, often restricted to to stratum radiatum. In stratum oriens and near to the border of strata radiatum and lacunosum moleculare cells with horizontally running dendrites were also found. Multipolar cells were most common in stratum radiatum of the CA3 region. The GABAergic nature of the calbindin D28k-containing non-pyramidal cells was studied using the "mirror" technique. Adjacent thick sections were immunostained for calbindin D28k and GABA, and halved neurons were identified on the common surfaces. The majority of calbindin D28k-containing non-pyramidal cells were shown to be GABAergic. The GABA-negative calbindin cells were found in relatively large numbers in stratum oriens of the CA1-CA3 region, and occasionally in strata radiatum and pyramidale of CA2, and in stratum radiatum of the CA3c region near to the border of the dentate hilus. However, even in these cells a weak immunostaining, only slightly but consistently above background level, was always observed. Earlier studies have demonstrated that the somata of GABAergic neurons with distant projections may contain a level of GABA that is below the detection threshold of immunocytochemistry. Here we provide direct evidence that the calbindin-containing non-pyramidal cells were among those projecting to the medial septum. Following horseradish peroxidase injections into the medial septum 80% of the retrogradely labelled non-pyramidal cells were found to be immunoreactive for calbindin D28k, and 20% contained neuropeptide Y. These results suggest that the calbindin D28k-containing and apparently GABA-immunonegative non-pyramidal cells in stratum oriens of the CA1-CA3 regions may also be GABAergic, but have a distant projection, that is, to the medial septum.     

Roles of alpha and beta carbonic anhydrases of Helicobacter pylori in the urease-dependent response to acidity and in colonization of the murine gastric mucosa

Carbon dioxide occupies a central position in the physiology of Helicobacter pylori owing to its capnophilic nature, the large amounts of carbon dioxide produced by urease-mediated urea hydrolysis, and the constant bicarbonate supply in the stomach. Carbonic anhydrases (CA) catalyze the interconversion of carbon dioxide and bicarbonate and are involved in functions such as CO₂ transport or trapping and pH homeostasis. H. pylori encodes a periplasmic α-CA (α-CA-HP) and a cytoplasmic β-CA (β-CA-HP). Single CA inactivation and double CA inactivation were obtained for five genetic backgrounds, indicating that H. pylori CA are not essential for growth in vitro. Bicarbonate-carbon dioxide exchange rates were measured by nuclear magnetic resonance spectroscopy using lysates of parental strains and CA mutants. Only the mutants defective in the α-CA-HP enzyme showed strongly reduced exchange rates. In H. pylori, urease activity is essential for acid resistance in the gastric environment. Urease activity measured using crude cell extracts was not modified by the absence of CA. With intact CA mutant cells incubated in acidic conditions (pH 2.2) in the presence of urea there was a delay in the increase in the pH of the incubation medium, a phenotype most pronounced in the absence of H. pylori α-CA. This correlated with a delay in acid activation of the urease as measured by slower ammonia production in whole cells. The role of CA in vivo was examined using the mouse model of infection with two mouse-adapted H. pylori strains, SS1 and X47-2AL. Compared to colonization by the wild-type strain, colonization by X47-2AL single and double CA mutants was strongly reduced. Colonization by SS1 CA mutants was not significantly different from colonization by wild-type strain SS1. However, when mice were infected by SS1 Δ(β-CA-HP) or by a SS1 double CA mutant, the inflammation scores of the mouse gastric mucosa were strongly reduced. In conclusion, CA contribute to the urease-dependent response to acidity of H. pylori and are required for high-grade inflammation and efficient colonization by some strains.     

Input-output relations in the entorhinal cortex-dentate-hippocampal system: evidence for a non-linear transfer of signals

In the current study we analyzed the input-output relations in the entorhinal-dentate-hippocampal system, a major network involved in long-term memory. In anesthetized guinea pigs, the system was driven by activation of perforant path neurons in the entorhinal cortex (ENT), via presubicular fibers directly stimulated in the dorsal psalterium. Perforant path neuron discharge activated in parallel the dentate gyrus (DG) and hippocampal field CA2. Whereas the output from the DG activated hippocampal field CA3, the output from the sole field CA2 was sufficient for activation of field CA1. Signals from field CA3 operated in concert with CA2, likely contributing to discharge field CA1. These findings indicate the existence of two in parallel disynaptic systems: an ENT-CA2-CA1 and an ENT-DG-CA3 system. The convergence of the latter with the former gives origin the classical trisynaptic circuit, the ENT-DG-CA3-CA1 system. The input-output relations between the population excitatory postsynaptic potentials (pEPSP) evoked in the DG, CA3, CA2 and CA1 and the population spike (PS) evoked in the structure upstream (the input) were described by smooth sigmoid curves. In contrast, the input-output relations of the PS versus the pEPSP within each structure were described by steep sigmoid curves. The net input-output functions of the DG (ENT-DG system), field CA2 (ENT-CA2 system), field CA3 (ENT-DG-CA3 system) and field CA1 (ENT-CA2-CA1&ENT-DG-CA3-CA1 system) were described by sigmoid curves. While the DG and field CA2 exhibited steep sigmoids, fields CA3 and CA1 had less steep sigmoid functions. The present study demonstrates that all structures downstream to the ENT operate according to sigmoid input-output functions, characterized by specific parameters. These different behaviors may contribute to different memory processes. We additionally demonstrate that field CA1 can be activated by field CA2, independently from field CA3. This functional dissociation between CA3 and CA1 may subserve specific roles of each field in memory encoding/retrieval.     

GABAergic basket-pyramidal and basket-granular systems of the hippocampal formation in the cat

The localization of GABA transaminase, the marker enzyme of axon terminals of GABAergic neurons, was studied in slices of cat hippocampus by the histological method. By its specific staining, the reaction product was consistently localized in synaptic basket terminals on granular cells of the dentate fascia and of pyramidal neurons of hippocampal areas CA1-CA3. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 6, pp. 644–646, June, 1995 Presented by Yu. A. Romanov, Member of the Russian Academy of Medical Sciences     

Action of the hyperpolarization-activated current (I h) blocker ZD 7288 in hippocampal CA1 neurons

 The effects of ZD 7288, a ”bradycardic” agent, in young rat hippocampal slices in vitro were studied. ZD 7288 (1–1000 μM) reduced the hyperpolarization-activated current (I _h) in CA1 pyramidal neurons by a voltage-independent blocking mechanism. Under current-clamp conditions, the bradycardic agent (10 μM) caused membrane hyperpolarization (by 5.9 ± 0.5 mV) and a reduction of membrane conductance (by 17.9 ± 4.1%). These data are consistent with the block of an inward current which is active at rest. The drug-induced hyperpolarization depressed the cell’s excitability by increasing the threshold current necessary to induce firing. When the drug-induced hyperpolarization was compensated for by injection of a tonic depolarizing current, ZD 7288 caused a reduction of the inhibitory post-synaptic potential (IPSP) in EPSP-IPSP sequences. Since Cs⁺, another known blocker of I _h, is able to reverse long-term depression (LTD) of the CA3-CA1 synapse in hippocampal slices, we tested the effect of ZD 7288 on synaptic transmission. We found that ZD 7288 did not significantly modify LTD, suggesting that Cs⁺-induced inhibition of LTD maintenance is not directly related to block of I _h. Received: 14 February 1997 / Received after revision: 4 July 1997 / Accepted: 21 July 1997     

Quantitative receptor autoradiography of eight different transmitter-binding sites in the hippocampus of the common marmoset, Callithrix jacchus

The regional and laminar distributions of eight different transmitter-binding sites were measured in the marmoset hippocampus by means of quantitative in vitro receptor autoradiography. Receptors for 5-HT₁, l-glutamate, N-methyl-d-aspartate (NMDA) and GABA_A were similarly distributed. The highest concentrations of these receptors were found in the pyramidal layer of CA1 and the molecular layer of the dentate gyrus. The 5-HT₂ receptors showed the highest concentrations in the oriens layer of CA2. The highest concentrations of muscarinic M1 receptors were seen in the pyramidal layer of CA1. Muscarinic M2 receptors were most densely concentrated in the pyramidal layers of CA1, CA2 and CA3. The noradrenergic ₁ receptors were most densely packed in the radiatum-lacunosum-molecular layer of CA2 and the molecular layer of the dentate gyrus. Statistically significant co-distributions of serotoninergic, glutamatergic and GABAergic receptors point to possible interactions between these receptor systems in the same hippocampal regions and layers. Comparisons of marmoset distribution patterns for GABA_A, NMDA, l-glutamate and 5-HT₁ receptors with those in human hippocampi and those of other primates showed similarities between them. Clear differences in the patterns of ₁, M1, M2 and 5-HT₂ receptors could be seen between marmoset and human hippocampi, indicating a high degree of species specificity in a presumably conservative brain region. More similarities, however, could be found between marmoset and human hippocampi than between those of rat and human brains, especially in relation to 5-HT₁ and GABA_A receptors and l-glutamate-binding sites. In addition to the functional significance of receptor distribution patterns, such studies represent a valuable tool for the analysis of neurochemical aspects of brain evolution.Abbreviations 5-HT 5-Hydroxytryptamine - GABA gamma-aminobutyric acid - NMDA N-methyl-d-aspartate - NMS N-methyl-scopolamine - CA1-CA4 subfields of the cornu ammonis - DG dentate gyrus - SEM standard error of the mean - AChE acetylcholinesterase - ChAT choline acetyltransferase - GAD-IR glutamate-decarboxylase-immunoreactive     

Identification of a t(X;17)(q28;q21) generating a KANSL1‐MTCP1 gene fusion leading to dysregulated expression of MTCP1 in acute myeloid leukemia

Chromosomal translocations and generating fusion genes are closely associated with disease initiation and progression in acute myeloid leukemia (AML). In this study, we identified a novel t(X;17)(q28;q21) chromosomal rearrangement in a patient with acute monocytic leukemia. Using RNA‐sequencing, we identified a KANSL1‐MTCP1 and a KANSL1‐CMC4 fusion gene. 5′‐UTR sequences of the KANSL1 gene were found to become fused upstream of the coding sequence region of the MTCP1 and CMC4 genes, respectively, resulting in an aberrantly high expression of these genes. Functional studies revealed that overexpression of the MTCP1 gene induced an increased cell proliferation and partial blockage of cell differentiation, suggesting that the aberrant expression of MTCP1 is of critical importance in leukemogenesis.     

TrFIA检测CA242对结直肠癌的临床价值

目的：观察采用时间分辨荧光免疫分析检测的CA242在恶性肿瘤普查、诊断和预后的应用价值。方法：收集我院2004年10月～2006年3月的住院病例。包括恶性肿瘤组共226例,良性病变组共74例,正常组50例。采集患者静脉血,常规离心分离血清进行检测。CA242采用TrFIA,CA242正常值为〈20U／ml。结果：使用TrFIA检测CA242在恶性肿瘤组表达水平较良性病变组与正常对照组的表达水平及阳性例数明显升高,其差别明显,P〈0．05,有统计学意义。CA242与其他肿瘤标记物比较,以CEA的灵敏度（45．21％）和CA242的特异度（92．86％）最高。当CA242与另外一项肿瘤标志物联用时,采用平行联检CA242-CEA诊断的灵敏度（59．57％）最高,而采用系列联检CA242-CAl99和CA242-CA50的特异度可以达到100％。当CA242与其他其二项肿瘤标志物联用时,CA242-CEA-CA50平行联检灵敏度最高达67．74％。三项联合应用时,系列联检特异度都是100％。当CA242与其他三项指标联合时,平行联检在本文所用方法中灵敏度最高（69．23％）,系列联检特异度是100％。结论：采用TrFIA检测糖链抗原CA242对直肠癌等的普查、诊断、预后的判断提供了一定的应用价值。     

Restoration of spatial working memory by genetic rescue of GluR-A-deficient mice

Gene-targeted mice lacking the AMPA receptor subunit GluR-A (also called GluR1 encoded by the gene Gria1,) have deficits in hippocampal CA3-CA1 long-term potentiation (LTP) and have profoundly impaired hippocampus-dependent spatial working memory (SWM) tasks, although their spatial reference memory remains normal. Here we show that forebrain-localized expression of GFP-tagged GluR-A subunits in GluR-A-deficient mice rescues SWM, paralleling its rescue of CA3-CA1 LTP. This provides powerful new evidence linking hippocampal GluR-A-dependent synaptic plasticity to rapid, flexible memory processing.     

Small (SKCa) Ca2+-activated K+ channels in cultured rat hippocampal pyramidal neurones

 Small (SK_Ca) Ca²⁺-activated K⁺ channels were identified in membrane patches excised from cultured CA1-CA3 pyramidal neurones of the neonatal rat hippocampus. When recorded in low-K⁺ extracellular solution ([K⁺]_o=2.5 mM), SK_Ca channels had a low conductance (@3 pS at 0 mV), were activated by ≥175 nM Ca²⁺ (P _o=0.54 at 500 nM Ca²⁺) and there were two open-time components (2.1 and @70 ms) to their activity. These properties of single SK_Ca channels are similar to those of slow after-hyperpolarization channels (sAHP) previously inferred from fluctuation analysis of the sAHP current. It is concluded that the SK_Ca channel reported here may be the channel that generates the sAHP in hippocampal pyramidal neurones. Received: 9 July 1998 / Received after revision: 5 October 1998 / Accepted: 7 October 1998     

Injectable in situ cross-linking hyaluronic acid/carboxymethyl cellulose based hydrogels for drug release

A series of injectable in situ cross-linking hyaluronic acid/carboxymethyl cellulose based hydrogels (HA/CMC) was prepared via disulfide bonds by the oxidation of dissolved oxygen. The results showed that HA/CMC hydrogels exhibited tunable gelling time, appropriate rheology properties, high swelling ratio, good stability, and sustained drug release ability. The gelling time of HA/CMC hydrogels ranged from 1.4 to 7.0 min, and the values of the storage modulus, complex shear modulus, dynamic viscosity, and yield stress of HA3/CMC3 hydrogel were about 5869 Pa, 5870 Pa, 587 Pa·s, and 1969 Pa, respectively. The degradation percentage of HA1/CMC1, HA2/CMC2, and HA3/CMC3 hydrogels were about 60, 49, and 41% after incubating 42 days, and the in vitro cumulative release percentage of BSA from HA1/CMC1, HA2/CMC2, and HA3/CMC3 drug-loaded hydrogels were about 99, 91, and 82% after 30 days. The series of injectable in situ cross-linking HA/CMC hydrogels exhibited good comprehensive performance, signifying that these hydrogels could be potentially used in the fields of short- and medium-term controlled drug release, cell encapsulation, regenerative medicine, and tissue engineering.     

Study on the haplotypes of MICA and MICB microsatellite and HLA-B locus in the Guangzhou Han population

The purpose of this study was to investigate the genetic polymorphisms and haplotypes of microsatellite locus in exon 5 of the MICA gene and intron 1 of the MICB gene and human leukocyte antigen-B (HLA-B) gene based on 106 samples of the Guangzhou Han population through means of polymerase chain reaction and the fluorescent technique (6-FAM). The corresponding haplotype frequencies, linkage disequilibrium values and relative linkage disequilibrium values were estimated based on population data. The results show that the genotype distributions of MICA and MICB microsatellite and HLA-B satisfy the Hardy-Weinberg equilibrium. In total, five alleles of MICA microsatellite locus and 14 alleles of MICB microsatellite locus were observed. MICA A5 was the most common allele (0.2877), whereas A4 was the least common (0.1321). MICB CA14 was the most common allele (0.3255), and CA19 and CA28 were the two least common (0.0047). CA27 was not observed at all. Five kinds of MICA-MICB haplotypes, 18 kinds of MICA-HLA-B haplotypes and 12 kinds of MICB-HLA-B haplotypes occurred at frequencies of more than 1%. The common haplotypes of MICA-MICB, MICA-HLA-B and MICB-HLA-B were A5-CA14, A5.1-CA18, A4-CA26, A9-CA15, A5-B*15(62), A5.1-B*1301/1302, A4-B*1301/1302, A6-B*51, A6-B*4403, A9-B*3802, CA14-B*4601, CA18-B*1301/1302 and CA26-B*1301/1302, and these haplotypes showed strong linkage disequilibrium. The polymorphisms and haplotype distributions of MICA and MICB microsatellite and HLA-B locus in the Guangzhou Han population have their own distinct genetic characteristics. The microsatellite locus of exon 5 of the MICA gene and intron 1 of the MICB gene could therefore be used as genetic markers in the studies of anthropology, gene linkage analysis in genetic diseases, individual identification and paternity testing in forensic medicine.