Protection by glia-conditioned medium in a cell model of Huntington disease

The physiological role of huntingtin and the pathogenic mechanisms that produce the disease are unknown. Mutant huntingtin changes its normal localization and produces cytoplasmic and intranuclear inclusions, changes gene transcription, alters synaptic transmission, impairs mitochondrial activity and activates caspases and other pro-apoptotic molecules, promotes excitotoxicity, energy deficits, synthesis and release reduction of neurotrophic factors and oxidative stress. Previous studies confirm that the mutant huntingtin difficult neurotrophic function of astrocytes leading to neuronal dysfunction in Huntington’s disease. Our objective was to study the neuroprotective potential role of glia-conditioned medium (GCM) in an in vitro model of Huntington’s disease. We used conditionally-immortalized striatal neuronal progenitor cell lines (STHdhQ7/Q7 and STHdhQ111/Q111) expressing endogenous levels of normal and mutant huntingtin with 7 and 111 glutamines, respectively. We studied the protection of fetal and postnatal glia conditioned medium (GCM) on H2O2 (2 µM), glutamate (5 mM) and 3-nitropropionic acid (2.5 mM) related toxicity. We also compared the neuroprotective effects of GCM versus that of the growth factors bFGF, BDNF and GDNF. Fetal GCM protects from every toxin, reducing the cell death and increasing the cell survival. Fetal GCM reduces the caspases fragmentation of the protein PARP, the expression of chaperone Hsp70 and the accumulation of ROS and polyubiquitinated proteins. In addition, in Q111 striatal cells treated with H2O2 (2 µM) for 24 hours, the intracellular GSH levels are higher in the presence of GCM. Notably, the 13-day and 2-month postnatal GCM, totally protects from H2O2 induced cell death in mutant striatal cells. GCM neuroprotective effects are more potent than those of the already identified neurotrophic factors. We conclude that GCM protects Q111 cells from neuronal neurotoxins and the effects of GCM are more potent than those of any known neurotrophic factor. GCM may contain new and more potent, as yet unidentified, neurotrophic molecules, potentially useful in patients with Huntington’s disease.

Fatal bleeding in patients receiving anticoagulant therapy for venous thromboembolism: findings from the RIETE registry

BACKGROUND

Fatal bleeding is a serious consequence of anticoagulant therapy, but factors associated with fatal bleeding during the first 3 months of treatment of venous thromboembolism (VTE) are uncertain.

METHODS

Using data from RIETE, an ongoing registry of consecutive patients with acute VTE, we assessed risk factors for fatal bleeding among all patients. We then used this information to derive a clinical model that would stratify a patient's risk of fatal bleeding during the first 3 months of treatment.

RESULTS

Of 24 395 patients, 546 (2.24%) had a major bleed and 135 (0.55%) had a fatal bleed. The gastrointestinal tract was the most common site (40% of fatal bleeds), followed by intracranial bleeding (25%). Fatal bleeding was independently associated with the following factors at the time of VTE diagnosis: age >75 years (OR, 2.16), metastatic cancer (OR, 3.80), immobility > or = 4 days (OR, 1.99), a major bleed within the past 30 days (OR, 2.64), an abnormal prothrombin time (OR, 2.09), a platelet count < 100 x 10(9) L(-1) (OR, 2.23), creatinine clearance < 30 mL min(-1) (OR, 2.27), anemia (OR, 1.54), and distal deep vein thrombosis (OR, 0.39). INR at the time of bleeding is not known. A clinical prediction rule for risk of fatal bleeding that included nine baseline factors was derived. Fatal bleeding occurred in 0.16% (95% CI, 0.11-0.23) of the low-risk, 1.06% (95% CI, 0.85-1.30) of the moderate-risk, and 4.24% (95% CI, 2.76-6.27) of the high-risk category.

CONCLUSIONS

Patient characteristics and laboratory variables can identify patients at high risk for fatal bleeding during treatment of VTE.

NP7 protects from cell death induced by oxidative stress in neuronal and glial midbrain cultures from parkin null mice

Parkin mutations produce Parkinson's disease (PD) in humans and nigrostriatal dopamine lesions related to increased free radicals in mice. We examined the effects of NP7, a synthetic, marine derived, free radical scavenger which enters the brain, on H(2)O(2) toxicity in cultured neurons and glia from wild-type (WT) and parkin null mice (PK-KO). NP7, 5-10 microM, prevented the H(2)O(2) induced apoptosis and necrosis of midbrain neuronal and glial cultures from WT and PK-KO mice. NP7 suppressed microglial activation and the H(2)O(2) induced drop-out of dopamine neurons(.) Furthermore, NP7 prevented the increased phosphorylation of ERK and AKT induced by H(2)O(2). NP7 may be a promising neuroprotector against oxidative stress in PD.

Childhood eating and weight in eating disorders: a multi-centre European study of affected women and their unaffected sisters

BACKGROUND

Previous studies have suggested that childhood eating and weight problems may be risk factors for eating disorders. Robust evidence is still lacking.

AIMS

To investigate whether childhood eating and weight problems increase the risk of eating disorders in affected women compared to their unaffected sisters.

METHODS

Women (150) with anorexia (AN) or bulimia nervosa (BN) recruited from clinical and community samples were compared to their unaffected sister closest in age on maternal reports of childhood eating and weight.

RESULTS

Women with BN were significantly more overweight at the ages of 5 and 10 (both OR = 2.8, p < 0.01), ate a lot (OR = 1.3, p < 0.01), were less picky (OR = 0.6, p < 0.05) and ate quickly (OR = 2.3, p < 0.05) between the ages of 6 and 10 compared to their healthy sisters. Significantly more women with AN were described as having a higher weight at 6 months (OR = 0.8, p < 0.01) and 1 year (OR = 0.6, p < 0.01) compared to their healthy sisters. Childhood eating was comparable in the women with AN and their unaffected sisters.

CONCLUSIONS

Traits of childhood overeating were more common in bulimic women compared to their unaffected siblings. Subjects with AN did not differ from their sisters on eating variables. The increased risk of BN due to childhood overweight suggests that prevention strategies for childhood obesity and overweight may therefore be applicable in BN.

The JAZ family of repressors is the missing link in jasmonate signalling

Jasmonates are essential phytohormones for plant development and survival. However, the molecular details of their signalling pathway remain largely unknown. The identification more than a decade ago of COI1 as an F-box protein suggested the existence of a repressor of jasmonate responses that is targeted by the SCF(COI1) complex for proteasome degradation in response to jasmonate. Here we report the identification of JASMONATE-INSENSITIVE 3 (JAI3) and a family of related proteins named JAZ (jasmonate ZIM-domain), in Arabidopsis thaliana. Our results demonstrate that JAI3 and other JAZs are direct targets of the SCF(COI1) E3 ubiquitin ligase and jasmonate treatment induces their proteasome degradation. Moreover, JAI3 negatively regulates the key transcriptional activator of jasmonate responses, MYC2. The JAZ family therefore represents the molecular link between the two previously known steps in the jasmonate pathway. Furthermore, we demonstrate the existence of a regulatory feed-back loop involving MYC2 and JAZ proteins, which provides a mechanistic explanation for the pulsed response to jasmonate and the subsequent desensitization of the cell.

Contribution of NTRK2 to the genetic susceptibility to anorexia nervosa, harm avoidance and minimum body mass index

Anorexia nervosa (AN) and bulimia nervosa (BN) are eating disorders (ED) with complex genetic and environmental components. Genetic studies and animal models support the participation of brain-derived neurotrophic factor (BDNF) in the vulnerability to AN and BN. We investigated the genetic contribution of the BDNF-specific receptor neurotrophic tyrosine kinase receptor type 2 (NTRK2) to the susceptibility to ED. We have screened the entire NTRK2 gene in 91 patients with ED and have identified 14 single-nucleotide polymorphisms (SNPs). A population-based association study with six SNPs from the NTRK2 locus was performed in 164 ED patients and 121 controls. Significant evidence of association for markers -69C>G and IVS13+40G>A was detected. We also observed a strong association between the C-A-insC haplotype (-69/IVS13+40/2784-2785) and binge-eating/purging AN (ANP, P=0.006; OR=2.27), and a reduced frequency of haplotype G-A-delCl in BN patients (P=0.034; OR=0.6). The analysis of ED-related phenotypes revealed a clear association between NTRK2, high scores of Harm avoidance measured by the temperament and character inventory (TCI-R; P=0.003) and minimum body mass index (minBMI; P<0.001). Our data support a contribution of NTRK2 to the genetic susceptibility of ED, mainly ANP, and ED-related phenotypic traits, such as Harm avoidance and minBMI.

Parkin gene inactivation alters behaviour and dopamine neurotransmission in the mouse

Mutations of the parkin gene are the most frequent cause of early onset autosomal recessive parkinsonism (EO-AR). Here we show that inactivation of the parkin gene in mice results in motor and cognitive deficits, inhibition of amphetamine-induced dopamine release and inhibition of glutamate neurotransmission. The levels of dopamine are increased in the limbic brain areas of parkin mutant mice and there is a shift towards increased metabolism of dopamine by MAO. Although there was no evidence for a reduction of nigrostriatal dopamine neurons in the parkin mutant mice, the level of dopamine transporter protein was reduced in these animals, suggesting a decreased density of dopamine terminals, or adaptative changes in the nigrostriatal dopamine system. GSH levels were increased in the striatum and fetal mesencephalic neurons from parkin mutant mice, suggesting that a compensatory mechanism may protect dopamine neurons from neuronal death. These parkin mutant mice provide a valuable tool to better understand the preclinical deficits observed in patients with PD and to characterize the mechanisms leading to the degeneration of dopamine neurons that could provide new strategies for neuroprotection.

Met66 in the brain-derived neurotrophic factor (BDNF) precursor is associated with anorexia nervosa restrictive type

Several lines of evidence support a role for brain-derived neurotrophic factor (BDNF) alterations in the etiology of eating disorders (EDs). BDNF heterozygous knockout mice show alterations in eating behavior, increased body weight and adipocyte hypertrophy. BDNF also regulates the synaptic efficiency through the modulation of key neurotransmitter systems previously known to be involved in ED. These findings, together with the fact that this neurotrophin is expressed in the hypothalamus nuclei associated with weight regulation and feeding control, led us to propose BDNF as a candidate gene for ED. To investigate the possible involvement of this neurotrophin in eating behavior, we screened the BDNF gene in 95 ED patients and identified four sequence variants. Two of them, -374A/T and -256G/A, were found in two patients with anorexia nervosa (AN) and consisted of single-nucleotide mutations within the 5' untranslated region (5'UTR). The other two polymorphisms resulted in a C to T transition located at the 5'UTR of the BDNF gene and an amino-acid substitution within the BDNF precursor protein (Val66Met). We performed a case-control study for these two Single-nucleotide polymorphisms in a sample of 143 ED patients and 112 unrelated controls and found a strong association of restricting AN (ANR) with the Met allele of the Val66Met BDNF polymorphism (2p=0.002). There was also evidence for a significant effect of this sequence variant on the minimum body mass index (MBMI) (2p=0.006). These results suggest that the BDNF Met66 variant may be a susceptibility factor to ED, mainly to ANR and low MBMI.

Male Wistar rats show uniform wind-up responses in carrageenan-induced inflammation but not in the normal situation

The technique of recording spinal cord withdrawal reflexes as single motor units (SMUs) does not require intense preparatory surgery and allows the study of the nociceptive system in physiological conditions. It has been used to show that the wind-up phenomenon depends on the level of excitability of spinal cord neurones, the integrity of the spinal cord and the parameters of the stimulation used. We have now used SMU recordings to assess whether wind-up is also an heterogeneous phenomenon depending on the muscle studied, and, if so, how the presence of hyperalgesia affects its generation. The experiments were performed in normal and carrageenan-induced inflammation in male Wistar rats anesthetized with alpha-chloralose. Wind-up was recorded in units from peroneus longus, tibialis anterior and extensor digitorum longus. The results showed that in normal animals, the curves of C-fibre mediated wind-up reached saturation at different times and the shape of the curves was different depending on the muscle studied and on the intensity of stimulation used. In inflammation, however, C-fibre mediated wind-up became very uniform in the muscles studied, with a similar shape and saturation point. A-fibre mediated wind-up was only observed in animals with inflammation and no differences were observed between muscles. We conclude that in the absence of preparatory surgery and inflammation, C-fibre wind-up is heterogeneous, and supports a modular organization of nociceptive spinal reflexes. In hyperalgesia, however, wind-up curves are similar in units from different muscles, confirming a loss of modular organization that also affects the generation of wind-up.

Phylogenetic relationships in Pleurothallidinae (Orchidaceae): combined evidence from nuclear and plastid DNA sequences

To evaluate the monophyly of subtribe Pleurothallidinae (Epidendreae: Orchidaceae) and the component genera and to reveal evolutionary relationships and trends, we sequenced the nuclear ribosomal DNA internal transcribed spacers (ITS1 and ITS2) and 5.8S gene for 185 taxa. In addition, to improve the overall assessments along the spine of the topology, we added plastid sequences from matK, the trnL intron, and the trnL-F intergenic spacer for a representative subset of those taxa in the ITS study. All results were highly congruent, and so we then combined the sequence data from all three data sets in a separate analysis of 58 representative taxa. There is strong support in most analyses for the monophyly of Pleurothallidinae and in some for inclusion of Dilomilis and Neocognauxia of Laeliinae. Although most genera in the nine clades identified in the analyses are monophyletic, all data sets are highly congruent in revealing the polyphyly of Pleurothallis and its constitutent subgenera as presently understood. The high degree of homoplasy in morphological characters, especially floral characters, limits their usefulness in phylogenetic reconstruction of the subtribe.

A conserved MYB transcription factor involved in phosphate starvation signaling both in vascular plants and in unicellular algae

Plants have evolved a number of adaptive responses to cope with growth in conditions of limited phosphate (Pi) supply involving biochemical, metabolic, and developmental changes. We prepared an EMS-mutagenized M(2) population of an Arabidopsis thaliana transgenic line harboring a reporter gene specifically responsive to Pi starvation (AtIPS1::GUS), and screened for mutants altered in Pi starvation regulation. One of the mutants, phr1 (phosphate starvation response 1), displayed reduced response of AtIPS1::GUS to Pi starvation, and also had a broad range of Pi starvation responses impaired, including the responsiveness of various other Pi starvation-induced genes and metabolic responses, such as the increase in anthocyanin accumulation. PHR1 was positionally cloned and shown be related to the PHOSPHORUS STARVATION RESPONSE 1 (PSR1) gene from Chlamydomonas reinhardtii. A GFP::PHR1 protein fusion was localized in the nucleus independently of Pi status, as is the case for PSR1. PHR1 is expressed in Pi sufficient conditions and, in contrast to PSR1, is only weakly responsive to Pi starvation. PHR1, PSR1, and other members of the protein family share a MYB domain and a predicted coiled-coil (CC) domain, defining a subtype within the MYB superfamily, the MYB-CC family. Therefore, PHR1 was found to bind as a dimer to an imperfect palindromic sequence. PHR1-binding sequences are present in the promoter of Pi starvation-responsive structural genes, indicating that this protein acts downstream in the Pi starvation signaling pathway.

Binge eating disorder onset by unusual parasitic intestinal disease: a case-report

We report a case of binge eating disorder (BED) in a 19-year-old Spanish woman, whose onset followed a nowadays uncommon parasitic intestinal disease (Taenia solium by cysticercosis). The patient exhibited bizarre and frequent hyperphagia episodes and extreme loss of weight, common symptoms of this condition. The patient continued to have frequent binge episodes and inappropriate eating patterns, gaining weight consequently over a normal range, despite successful treatment of the condition. No purging behavior was detected. A classical conditioning behavioral model, was useful for the understanding and formulation of this case. To the authors' knowledge, this is the first reported case where a parasitic infestation triggered the onset of BED.

Influence of cytokinins on the expression of phosphate starvation responsive genes in Arabidopsis

The increase in the ratio of root growth to shoot growth that occurs in response to phosphate (Pi) deprivation is paralleled by a decrease in cytokinin levels under the same conditions. However, the role of cytokinin in the rescue system for Pi starvation remains largely unknown. We have isolated a gene from Arabidopsis thaliana (AtIPS1) that is induced by Pi starvation, and studied the effect of cytokinin on its expression in response to Pi deprivation. AtIPS1 belongs to the TPSI1/Mt4 family, the members of which are specifically induced by Pi starvation, and the RNAs of which contain only short, non-conserved open reading frames. Pi deprivation induces AtIPS1 expression in all cells of wild-type plants, whereas in the pho1 mutant grown on Pi-rich soils, AtIPS1 expression in the root was delimited by the endodermis. This supports the view that pho1 is impaired in xylem loading of Pi, and that long-distance signals controlling the Pi starvation responses act via negative control. Exogenous cytokinins repress the expression of AtIPS1 and other Pi starvation-responsive genes in response to Pi deprivation. However, cytokinins did not repress the increase in root-hair number and length induced by Pi starvation, a response dependent on local Pi concentration rather than on whole-plant Pi status. Our results raise the possibility that cytokinins may be involved in the negative modulation of long-distance, systemically controlled Pi starvation responses, which are dependent on whole-plant Pi status.

Interception and retention of macroscopic bryophyte fragments by branch substrates in a tropical cloud forest: an experimental and demographic approach

Although the significance of canopy plant communities to ecosystem function is well documented, the process by which such communities become established in trees remains poorly known. Colonization of tree surfaces by canopy-dwelling plants often begins with the establishment of bryophytes, so the conditions that affect the dispersal of bryophytes in the forest canopy merit study. We assessed success rates of one mechanism of bryophyte propagation, the aerial dispersal of macroscopic fragments, using an experimental approach. We quantified interception and retention of marked fragments released from a 36 cm×36 cm grid 50 cm above branches of saplings and mature trees of the species Ocotea tonduzii in a montane cloud forest in Costa Rica. Only 1% of bryophyte fragments dropped over sapling crowns in this manner were retained for the 6-month duration of the study, while branches in the forest canopy with intact epiphyte loads and branches that had been stripped of their epiphytes retained 24% and 5%, respectively. Our results suggest that larger-diameter branches and the presence of other epiphytes can both improve the retention of bryophyte fragments on canopy branches. Further work will be needed to address the relative roles of other dispersal mechanisms (spores, gemmae, microscopic bryophyte fragments) and the dynamics of growth and establishment of macroscopic bryophyte fragments following their interception.

Response properties of hind limb single motor units in normal rats and after carrageenan-induced inflammation

The properties of single motor units from hind limb muscles and the changes in situations of hyperalgesia are not known in detail. We have therefore characterized the properties of single motor units in normal Wistar male rats and in rats with carrageenan-induced inflammation, under alpha-chloralose anaesthesia. Units were studied from three different muscles: peroneus longus, tibialis anterior and extensor digitorum longus. The properties of single motor units were not homogeneous in the three muscles studied in normal animals, showing different sizes of cutaneous receptive fields, thresholds for natural and electrical stimulation, and encoding of responses at different intensities of stimulation. Intraplantar injections of carrageenan induced a significant inflammation of the paw and a change in spontaneous behaviour observed in open field experiments. After inflammation, the responses to cutaneous stimulation of the single motor units became more homogeneous. The threshold for mechanical stimulation was lower for peroneus longus and tibialis anterior but not for extensor digitorum longus units when compared to normal animals. The receptive fields were larger when mapped with a 500 mN von Frey hair but not when mapped using a threshold intensity hair. The threshold for thermal stimulation was lower after inflammation than in normal conditions in all cases, whereas the threshold for electrical stimulation was lower in tibialis anterior and extensor digitorum longus units. An enhancement of responses related to the increase of stimulus intensity was seen in normal animals in all muscles for mechanical and electrical stimuli (but not for thermal). After inflammation, a relationship between firing rate and intensity of stimulation was seen in all cases studied. The firing of single motor units showed over 50% adaptation in the normal condition and over 75% after inflammation when stimulated for 10 s at mechanical threshold intensity. After inflammation, the rate of adaptation was significantly lower when suprathreshold intensity was used for mechanical stimulation. No differences were seen in the adaptation of units to thermal stimulation. We conclude that, in situations of hyperalgesia due to inflammation, the threshold, encoding of stimulus intensity and adaptation of single motor units from different muscles changed, resulting in a narrower range of responses and a more homogeneous population of units.

Nuclear events in ethylene signaling: a transcriptional cascade mediated by ETHYLENE-INSENSITIVE3 and ETHYLENE-RESPONSE-FACTOR1

Response to the gaseous plant hormone ethylene in Arabidopsis requires the EIN3/EIL family of nuclear proteins. The biochemical function(s) of EIN3/EIL proteins, however, has remained unknown. In this study, we show that EIN3 and EILs comprise a family of novel sequence-specific DNA-binding proteins that regulate gene expression by binding directly to a primary ethylene response element (PERE) related to the tomato E4-element. Moreover, we identified an immediate target of EIN3, ETHYLENE-RESPONSE-FACTOR1 (ERF1), which contains this element in its promoter. EIN3 is necessary and sufficient for ERF1 expression, and, like EIN3-overexpression in transgenic plants, constitutive expression of ERF1 results in the activation of a variety of ethylene response genes and phenotypes. Evidence is also provided that ERF1 acts downstream of EIN3 and all other components of the ethylene signaling pathway. The results demonstrate that the nuclear proteins EIN3 and ERF1 act sequentially in a cascade of transcriptional regulation initiated by ethylene gas.

Arabidopsis homologs of a c-Jun coactivator are present both in monomeric form and in the COP9 complex, and their abundance is differentially affected by the pleiotropic cop/det/fus mutations

The CONSTITUTIVE PHOTOMORPHOGENIC9 (COP9) complex is a nuclear localized, multisubunit protein complex essential for repression of light-mediated development in Arabidopsis. Mutations that abolish the complex result in constitutive photomorphogenic development in darkness and pleiotropic developmental defects in both light and darkness. Here, we report the identification of two apparently redundant genes, AJH1 and AJH2, that encode a subunit of the COP9 complex. Both AJH1 and AJH2 share high amino acid sequence identity (62 and 63%, respectively) with JAB1, a specific mammalian coactivator of AP-1 transcription. The proteins encoded by these two genes are present in both complex and monomeric forms, whereas complex formation is in part mediated by the direct interaction with FUSCA6. In addition, the stability of the monomeric AJH proteins requires functional COP1 and DEETIOLATED1 loci. Together with the fact that the previously known subunit FUSCA6 is an Arabidopsis homolog of human GPS1, a negative regulator of AP-1 transcription, our data suggest that the COP9 complex may contain both negative and positive regulators of transcription. Therefore, the COP9 complex may achieve its pleiotropic effects on Arabidopsis development by modulating activities of transcription factors in response to environmental stimuli.

Ethylene gas: perception, signaling and response

During the last decade a genetic approach based on the Arabidopsis 'triple response' to the hormone ethylene has allowed the identification of numerous components of the signal transduction pathway. Cloning of the genes and biochemical analysis of the proteins that they encode are uncovering the molecular mechanisms that allow a plant cell to perceive and respond to this gaseous regulator of plant growth/stress responses.

[Clinical characteristics of the peripheral form of epidemic neuropathy in the province of Cienfuegos]

INTRODUCTION

From October 1992 to September 1993 clinical observations of the civil population of Cienfuegos revealed the presence of epidemic neuropathy (EN) reaching about 2,000 patients. The clinical manifestations were not uniform. Although numerous studies have been carried out in our country, none have established the characteristics of EN 'the peripheral form'.

MATERIAL AND METHODS

We studied the first 50 patients assisted by the neurological services of the clinical surgical hospital Dr. Gustavo Aldereguia Lima of Cienfuegos diagnosed of EN 'peripheral form' according to the procedure established by Ministry of Public Health of Cuba. A clinical history was made for each patient consisting of: General data, history of toxic, nutritional, malabsorption factors and chronic illnesses; symptoms and a neurological examinations. Laboratory test, in a group of patients, were done in sera, urine, cerebrospinal fluid (CSF), gastric juice and neurophysiological studies that included computerized evoked potentials and electroencephalograms registers.

RESULTS

Upon analysis of the clinical history, nutritional factors was common to all the patients associated to toxic and malabsorption. The clinical forms were neuropathy (NP) 48%, myeloneuropathy (MNP) 42% and myelopathy (MP) 10%. Retrobulbar optic neuropathy was observed in 42% of the patients and auditory neuropathy in 22%.

CONCLUSIONS

The clinical characteristics of NP, in our cases, indicated that this disease fundamentally affects the sensorial neurons and the sensitive peripheral nerves, bilaterally, symmetrically, distally and predominantly in lower limbs. The pathological process has been associated with a distal axonopathy. However, clinic signs of myelopathy can be found up to 40% frequently combined with neuropathy or in isolated form, and seems to affect the posterior and lateral columns of the spinal cord, mainly at thoraciclumbar level. Neuropathy of central nervous system is unknown since no patient has died of EN.

Activation of the ethylene gas response pathway in Arabidopsis by the nuclear protein ETHYLENE-INSENSITIVE3 and related proteins

Mutations in the Arabidopsis ETHYLENE-INSENSITIVE3 (EIN3) gene severely limit a plant's response to the gaseous hormone ethylene. ein3 mutants show a loss of ethylene-mediated effects including gene expression, the triple response, cell growth inhibition, and accelerated senescence. EIN3 acts downstream of the histidine kinase ethylene receptor, ETR1, and the Raf-like kinase, CTR1. The EIN3 gene encodes a novel nuclear-localized protein that shares sequence similarity, structural features, and genetic function with three EIN3-LIKE (EIL) proteins. In addition to EIN3, EIL1 orEIL2 were able to complement ein3, suggesting their participation in the ethylene signaling pathway. Overexpression of EIN3 or EIL1 in wild-type or ethylene-insensitive2 plants conferred constitutive ethylene phenotypes, indicating their sufficiency for activation of the pathway in the absence of ethylene.

Activation of the ethylene gas response pathway in Arabidopsis by the nuclear protein ETHYLENE-INSENSITIVE3 and related proteins

Mutations in the Arabidopsis ETHYLENE-INSENSITIVE3 (EIN3) gene severely limit a plant's response to the gaseous hormone ethylene. ein3 mutants show a loss of ethylene-mediated effects including gene expression, the triple response, cell growth inhibition, and accelerated senescence. EIN3 acts downstream of the histidine kinase ethylene receptor, ETR1, and the Raf-like kinase, CTR1. The EIN3 gene encodes a novel nuclear-localized protein that shares sequence similarity, structural features, and genetic function with three EIN3-LIKE (EIL) proteins. In addition to EIN3, EIL1 orEIL2 were able to complement ein3, suggesting their participation in the ethylene signaling pathway. Overexpression of EIN3 or EIL1 in wild-type or ethylene-insensitive2 plants conferred constitutive ethylene phenotypes, indicating their sufficiency for activation of the pathway in the absence of ethylene.

Cutaneous responsiveness of rat single motor units activated by natural stimulation

Recordings of withdrawal reflexes have been used extensively to study sensory-motor integration and processing of nociceptive information in the spinal cord. We describe here a new technique for the manufacture of improved EMG electrodes that permit the characterisation of the physiological properties of single motor units as well as the easy location of the muscles studied. Individual motor units from three rat hind-limb muscles: peroneus longus, tibialis cranialis and extensor digitorum longus, were activated by thermal and mechanical stimulation applied to their cutaneous receptive fields, which were located mainly on the 4th and 5th toes. Thresholds for thermal and mechanical (Von Frey hairs) stimulation were similar in the three muscles studied, with a value of 44 +/- 1 degrees C and 100 mN (median), respectively. However, when a mechanical pincher with a stimulus area of 14 mm2 was used, the values seen were similar for peroneus longus and tibialis cranialis (342 +/- 23 and 330 +/- 71 mN, respectively, mean +/- S.E.M.) but lower for extensor digitorum longus (220 +/- 37 mN, mean +/- S.E.M.). The firing rate of the single motor units was similar for all types of stimulation at threshold intensity, and showed a linear relationship with stimulus intensity, except for units of the tibialis cranialis, which showed a greater degree of adaptation.

A single residue substitution causes a switch from the dual DNA binding specificity of plant transcription factor MYB.Ph3 to the animal c-MYB specificity

Transcription factor MYB.Ph3 from Petunia binds to two types of sequences, MBSI and MBSII, whereas murine c-MYB only binds to MBSI, and Am305 from Antirrhinum only binds to MBSII. DNA binding studies with hybrids of these proteins pointed to the N-terminal repeat (R2) as the most involved in determining binding to MBSI and/or MBSII, although some influence of the C-terminal repeat (R3) was also evident. Furthermore, a single residue substitution (Leu71 --> Glu) in MYB.Ph3 changed its specificity to that of c-MYB, and c-MYB with the reciprocal substitution (Glu132 --> Leu) essentially gained the MYB.Ph3 specificity. Molecular modeling and DNA binding studies with site-specific MYB.Ph3 mutants strongly supported the notion that the drastic changes in DNA binding specificity caused by the Leu --> Glu substitution reflect the fact that certain residues influence this property both directly, through base contacts, and indirectly, through interactions with other base-contacting residues, and that a single residue may establish alternative base contacts in different targets. Additionally, differential effects of mutations at non-base-contacting residues in MYB.Ph3 and c-MYB were observed, reflecting the importance of protein context on DNA binding properties of MYB proteins.

MYB.Ph3 transcription factor from Petunia hybrida induces similar DNA-bending/distortions on its two types of binding site

MYB.Ph3 from Petunia is a member of the MYB transcription factor family that recognizes two types of binding site, resembling direct and inverted repeats of the motif GTTA, respectively, and flanked on their 5' side by an A-rich sequence. In this study, it is shown that MYB.Ph3 induces similar conformational changes in both of its DNA-binding sites. Circular permutation assays indicate that the center of the distortions induced by MYB.Ph3 maps near the center of either MYB.Ph3-binding site. The degree of the distortion induced by MYB.Ph3 appears to be greatly affected by regions of the protein other than the DNA-binding domain, and differs from the distortion caused by animal c-MYB. Phasing analysis reveals that part of the distortion induced by MYB.Ph3 is DNA bending, oriented towards the minor groove, as is the case of its animal counterpart, c-MYB. DNA-binding by both MYB.Ph3 and animal c-MYB is more efficient in the presence of Ba2+, a divalent cation known to promote/stabilize DNA bending, than in the presence of other cations which do not favor this distortion, such as Na+ and Mg2+. In addition, both MYB proteins show higher affinity to selectively nicked DNA, which has increased DNA flexibility, strongly suggesting that DNA binding by these MYB proteins and DNA structural properties are mutually influenced.

Dual DNA binding specificity of a petal epidermis-specific MYB transcription factor (MYB.Ph3) from Petunia hybrida

The MYB.Ph3 protein recognized two DNA sequences that resemble the two known types of MYB DNA binding site: consensus I (MBSI), aaaAaaC(G/C)-GTTA, and consensus II (MBSII), aaaAGTTAGTTA. Optimal MBSI was recognized by animal c-MYB and not by Am305 from Antirrhinum, whereas MBSII showed the reverse behaviour. Different constraints on MYB.Ph3 binding to the two classes of sequences were demonstrated. DNA binding studies with mutated MBSI and MBSII and hydroxyl radical footprinting analysis, pointed to the N-terminal MYB repeat (R2) as the most involved in determining the dual DNA binding specificity of MYB.Ph3 and supported the idea that binding to MBSI and MBSII does not involve alternative orientations of the two repeats of MYB.Ph3. Minimal promoters containing either MBSI and MBSII were activated to the same extent by MYB.Ph3 in yeast, indicating that both types of binding site can be functionally equivalent. MYB.Ph3 binding sites are present in the promoter of flavonoid biosynthetic genes, such as the Petunia chsJ gene, which was transcriptionally activated by MYB.Ph3 in tobacco protoplasts. MYB.Ph3 was immunolocalized in the epidermal cell layer of petals, where flavonoid biosynthetic genes are actively expressed. This strongly suggests a role for MYB.Ph3 in the regulation of flavonoid biosynthesis.

Use of F1 progeny of Holstein × Zebu cross cattle as oocyte donors for in vitro embryo production and gene microinjection

This study was designed to determine the possibility of using F1 crossbreed cattle (HolsteinxZebu) as donors of oocytes for in vitro fertilization (IVF) and for pronuclear gene microinjection into in vitro-produced embryos. In the first part of the experiment oocytes from Bos taurus (Holstein), Bos indicus (Zebu) and F1 crossbred Bos taurusxBos indicus (HolsteinxZebu) genotypes were inseminated with Bos taurus (Holstein) semen and were allocated for in vitro embryo production using conventional IVF procedures. No differences were observed on the in vitro maturation (IVM) rates between breeds (HolsteinxHolstein:85%, ZebuxHolstein:84% and ZebuxHolsteinxHolstein:88%). Holstein cows yielded the highest number of cumulus oocyte complexes (6.8 per ovary) for in vitro maturation, differing (P<0.05) from ZebuxHolstein and ZebuxHolsteinxHolstein F1 by 5.1 and 5.8, respectively. However, the Holstein breed also yielded the lowest percentage of cleavage (45.1 vs 71.9% for ZebuxHolstein and 65.1% for ZebuxHolsteinxHolstein). Of the 3 genotypes, the hybrid F1 breed was the most efficient source of oocytes for the production of embryos capable of reaching morulae and blastocyst stages (76/250; P<0.001). In the second part of the study, 599 oocytes from the F1 breed were fertilized in vitro, 1 group of 150 oocytes was used for the determination of the optimal pronuclear visualization period. The highest number of oocytes with 2 pronuclei was observed between 24 to 28 h after IVF (27 to 42%). The remaining 399 oocytes were microinjected with a gene construct bearing the bacterial lacZ gene as the reporter for gene expression. Survival of embryos to microinjection was 73.8%, and 45.5% of them (50/110) cleaved in culture. Of the microinjected embryos, 1 out of 50 showed beta-galactosidase activity. These findings indicate that a tropical crossbreed of cattle (ZebuxHolsteinxHolstein) can be used as a source of oocytes for IVF programs and gene microinjection studies.

Production of transgenic mice and rabbits that carry and express the human tissue plasminogen activator cDNA under the control of a bovine alpha S1 casein promoter

One-cell embryos from mice and rabbits were microinjected with a hybrid gene composed of 1.6 kilobases (kb) promoter/regulatory sequences of the bovine alphaS1 casein gene fused to the complementary DNA (cDNA) encoding for the human tissue plasminogen activator (htPA) and 3'untranslated sequences from rabbit beta-globin and SV 40 genes. Transgenic mice and rabbits that carry the htPA gene were obtained. In mice, 11 founder females were generated, and 6 of them expressed low levels (about 50 mug/ml) of htPA in their milk. Some of the transgenic mice showed rearrangements of the microinjected DNA sequences as judged by Southern blot analysis. A position-dependent expression of the transgene is suspected to occur. The only live-born founder transgenic rabbit obtained was a male, and it transmitted the transgene in a Mendelian fashion to F1 females, which expressed htPA at very low levels (8 to 50 ng/ml). Although the 1.6-kb bovine alphaS1 casein promoter that was used directs the synthesis of htPA specifically to the mammary gland, it may not be sufficient for a high level of expression.

Organization of repeated sequences in species of the genus Avena

Four repetitive sequences from Avena murphyi have been isolated and their genome organization studied in different species of the genus Avena. A tandem sequence array was found for the Avena species that contain the C genome. Three other dispersed sequences present in the A and C genomes were arranged in a genomespecific manner. The fact that no major differences in the hybridization patterns were found between species with the same basic genome is consistent with the current taxonomy of Avena species.

Acute loxapine intoxication in a child

Thin-layer chromatography (TLC) was used to confirm the alleged ingestion of Loxitane (loxapine succinate) by a 20-month-old child. GC was used to further characterize TLC spots and to quantitate the loxapine concentration of the blood at 0.072 mg/dL, which was consistent with the child's presenting signs of lethargy and ataxia. The appropriate supportive symptomatic therapy, with monitoring for CNS and cardiovascular toxicities, resulted in an uneventful recovery.