Podcasts about epsps

In this AHRI Snapshots, we catch up with Principal Research fellow, Dr Qin Yu about her latest paper on glyphosate resistance in goosegrass. This paper was published in Nature Communications in August 2023, which is an impressive achievement. This paper is complicated, but essentially the researchers have found a hot spot on the genome of goosegrass that is a herbicide resistance generator.In this research, the team found that in glyphosate-resistant goosegrass the EPSPS gene was translocated to the sub-telomer region and duplicated many times there, leading to glyphosate resistance occurring.This work is useful not only in resistance gene discovery, but also in the development of gene-based next generation herbicides, like RNAi, as well as genetic reversal of resistance.It will also contribute to studying the weediness and adaptation of this global weed species.  Paper: ‘Subtelomeric 5-enolpyruvylshikimate-3-phosphate synthase copy number variation confers glyphosate resistance in Eleusine indica'You can follow AHRI on Twitter here. To learn more about AHRI's research and team, check out the website here.

Nesse episódio eu conversei com Professor Arthur Arrobas (UFPR) e com o Engenheiro Agrônomo Marcel Melo (Bayer/HRAC-BR). Nós falamos sobre o projeto de mapeamento de caruru, com resistência a herbicidas, no estado do Paraná.  Esse mapeamento tem por objetivo avaliar a susceptibilidade de biótipos de caruru provenientes de lavouras de soja do Paraná e do sul do Mato Grosso do Sul aos herbicidas inibidores da EPSPs, ALS, PROTOX, GS e mimetizadores de auxinas. Quer saber mais sobre o projeto de mapeamento caruru e os principais resultados encontrados até o momento para o estado do Paraná? Fique ligado e ouça esse episódio do MIPD47. Lembrando que esse podcast tem o apoio do Comitê de Ação a Resistência aos Herbicidas (HRAC-BR) e da Sociedade Brasileira da Ciência das Plantas Daninhas (SBCPD).

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.10.18.512768v1?rss=1 Authors: Trigo, F. F., Kawaguchi, S.-y. Abstract: Analogue signaling is the phenomenon by which subthreshold activity in the dendrites and soma of neurons is transmitted down the axon. Although it has been demonstrated in many different preparations, the extent and physiological role of analogue signaling for subthreshold, somatodendritic spontaneous activity have not been studied in detail. In order to address this we performed simultaneous, whole-cell recordings of the soma and axon of young cerebellar interneurons. We show that the somatodendritic spontaneous glutamatergic events are transmitted down the axon for significant distances and produce a measurable change in the voltage of the axonal varicosities. By combining electrophysiological recordings in the culture preparation and in slices, we further show that the analogously transmitted EPSPs can affect GABA release significantly, and that this effect is not due to a modification in the axonal AP shape or amplitude. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.09.30.510270v1?rss=1 Authors: Olah, G., Lakovics, R., Shapira, S., Leibner, Y., Szucs, A., Barzo, P., Molnar, G., Segev, I., Tamas, G. Abstract: Human-specific cognitive abilities depend on information processing in the cerebral cortex, where neurons are significantly larger and sparser compared to rodents. We found that, in synaptically-connected layer 2/3 pyramidal cells (L2/3 PCs), soma-to-soma signal propagation delay is similar in humans and rodents. Thus, to compensate for the increase in neurons size, membrane potential changes must propagate faster in human axons and/or dendrites. Dual somato-dendritic and somato-axonal patch recordings show that action potentials (APs) propagation speed is similar in human and rat axons, but the forward propagation of the EPSPs and the back-propagating APs are ~1.7-fold faster in human dendrites. Faithful biophysical models of human and rat L2/3 PCs, combined with pharmacological manipulations of membrane properties, showed that the larger dendritic diameter, combined with differences in cable properties, underlie the accelerated signal propagation in human cortical circuits. The implication for information processing in the human brain are discussed. Copy rights belong to original authors. Visit the link for more info Podcast created by PaperPlayer

Nesse episódio eu conversei com o Professor Dirceu Agostinetto da Universidade Federal de Pelotas (UFPEL) e com a Engenheira Agrônoma e Doutora em Plantas daninhas Claudia Oliveira (Syngenta/HRAC-BR). Nós conversamos sobre o projeto de mapeamento de caruru com resistência a herbicidas.  Atualmente tem se observado ineficiência no controle de caruru em lavouras de soja do Rio Grande do Sul (RS). Nesse cenário, é importante realizar estudos para avaliar a eficiência dos herbicidas em condições ideias, para definir se as dificuldades de controle são decorrentes de falhas na tecnologia de aplicação ou da evolução e disseminação de biótipos resistentes. Esse mapeamento tem por objetivo avaliar a susceptibilidade de biótipos de caruru provenientes de lavouras de soja do Rio Grande do Sul aos herbicidas inibidores da EPSPs, ALS, PROTOX, GS e mimetizadores de auxinas. Quer saber mais sobre o projeto de mapeamento de resistência em caruru e os principais resultados encontrados até o momento? Fique ligado e ouça esse episódio do MIPD47. Lembrando que esse podcast tem o apoio do Comitê de Ação a Resistência aos Herbicidas (HRAC-BR) e da Sociedade Brasileira da Ciência das Plantas Daninhas (SBCPD).

O glyphosate é uma molécula única, também uma das mais estudadas e mais eficientes entre os herbicidas já introduzidos no mercado para controle de plantas daninhas, e que, por isso, seu uso continua em expansão em todas as principais áreas agrícolas do mundo. Trata-se de um inibidor da atividade da enzima EPSPSs, a qual é catalisadora das reações de síntese dos aminoácidos aromáticos fenilalanina, tirosina e triptofano. Neste episódio da nossa série "Destrinchando Herbicidas" nós trouxemos o Professor Dr. Caio Carbonari, um dos mais renomados pesquisadores de herbicidas e plantas daninhas do Brasil, para nos explicar a importância e o funcionamento do glyphosate e com toda certeza você vai se surpreender com o impacto do glyphosate na agricultura e no manejo de plantas daninhas. E não podemos esquecer que esse também é o nosso episódio de número 100, portanto um episódio mais que especial para nosso podcast, portanto aperta o play e conheça mais sobre o herbicida mais utilizado do mundo. #moa #herbicidas #papoagro #podcastdoagro #agro #herbicida #papoagropodcast Quer saber mais o que rolou nesse episódio? É so acessar o site do Papo Agro ou o agregador de podcast que você preferir. www.papoagro.com.br Rede Agrocast: @redeagrocast Academia do Agro: @academiadoagro Agro Resenha: @agroresenha Bendito Agro: @benditoagro Bug Bites: @bugbitespodcast Cachaça, Prosa & Viola :@cpvpodcast Esalqast: @esalqast Mundo Agro Podcast: @mundoagropodcast Notícias do Front: @noticias_do_front Papo Agro: @papoagropodcast RumenCast: @rumencast

O glyphosate é uma molécula única, também uma das mais estudadas e mais eficientes entre os herbicidas já introduzidos no mercado para controle de plantas daninhas, e que, por isso, seu uso continua em expansão em todas as principais áreas agrícolas do mundo. Trata-se de um inibidor da atividade da enzima EPSPSs, a qual é catalisadora das reações de síntese dos aminoácidos aromáticos fenilalanina, tirosina e triptofano.  Neste episódio da nossa série "Destrinchando Herbicidas" nós trouxemos o Professor Dr. Caio Carbonari, um dos mais renomados pesquisadores de herbicidas e plantas daninhas do Brasil, para nos explicar a importância e o funcionamento do glyphosate e com toda certeza você vai se surpreender com o impacto do glyphosate na agricultura e no manejo de plantas daninhas. E não podemos esquecer que esse também é o nosso episódio de número 100, portanto um episódio mais que especial para nosso podcast, portanto aperta o play e conheça mais sobre o herbicida mais utilizado do mundo. #moa #herbicidas #papoagro #podcastdoagro #agro #herbicida #papoagropodcast Quer saber mais o que rolou nesse episódio? É so acessar o site do Papo Agro ou o agregador de podcast que você preferir. www.papoagro.com.br Rede Agrocast: @redeagrocast Academia do Agro: @academiadoagro Agro Resenha: @agroresenha Bendito Agro: @benditoagro Bug Bites: @bugbitespodcast Cachaça, Prosa & Viola :@cpvpodcast Esalqast: @esalqast Mundo Agro Podcast: @mundoagropodcast Notícias do Front: @noticias_do_front Papo Agro: @papoagropodcast RumenCast: @rumencast See omnystudio.com/listener for privacy information.

O glyphosate é uma molécula única, também uma das mais estudadas e mais eficientes entre os herbicidas já introduzidos no mercado para controle de plantas daninhas, e que, por isso, seu uso continua em expansão em todas as principais áreas agrícolas do mundo. Trata-se de um inibidor da atividade da enzima EPSPSs, a qual é catalisadora das reações de síntese dos aminoácidos aromáticos fenilalanina, tirosina e triptofano.  Neste episódio da nossa série "Destrinchando Herbicidas" nós trouxemos o Professor Dr. Caio Carbonari, um dos mais renomados pesquisadores de herbicidas e plantas daninhas do Brasil, para nos explicar a importância e o funcionamento do glyphosate e com toda certeza você vai se surpreender com o impacto do glyphosate na agricultura e no manejo de plantas daninhas. E não podemos esquecer que esse também é o nosso episódio de número 100, portanto um episódio mais que especial para nosso podcast, portanto aperta o play e conheça mais sobre o herbicida mais utilizado do mundo. #moa #herbicidas #papoagro #podcastdoagro #agro #herbicida #papoagropodcast Quer saber mais o que rolou nesse episódio? É so acessar o site do Papo Agro ou o agregador de podcast que você preferir. www.papoagro.com.br Rede Agrocast: @redeagrocast Academia do Agro: @academiadoagro Agro Resenha: @agroresenha Bendito Agro: @benditoagro Bug Bites: @bugbitespodcast Cachaça, Prosa & Viola :@cpvpodcast Esalqast: @esalqast Mundo Agro Podcast: @mundoagropodcast Notícias do Front: @noticias_do_front Papo Agro: @papoagropodcast RumenCast: @rumencast See omnystudio.com/listener for privacy information.

Nesse episódio eu conversei com Fernanda Satie Ikeda, ela que é Eng. Agrônoma, Doutora em Fitotecnia e pesquisadora da EMBRAPA Agrossilvipastoril, em Sinpo Mato Grosso. Nós conversamos sobre uma planta daninha exótica que foi percebida no Brasil na safra 2015, no estado Mato Grosso e que gerou uma preocupação muito grande nos técnicos, pesquisadores e principalmente os produtores. Conhecida como Amaranthus palmeri essa planta daninha preocupa pela sua agressividade, em termos de crescimento e produção de sementes, bem como pelo histórico de danos em culturas em outros países. Essa planta daninha já chegou ao Brasil com resistência ao glifosato e logo em seguida foi identificada plantas com resistência múltipla a herbicidas inibidores da EPSPs (glifosato) e ALS (imazetapir, clorimuron e cloransulam) dificultando o seu manejo em lavouras tais como algodão, soja e milho, por exemplo. Depois de muito trabalho árduo a disseminação dessa espécie foi mantida restrita ao estado do Mato Grosso e atualmente a área de infestação vem diminuindo a cada safra. Quer saber mais sobre o A. palmeri? Fique com a gente e ouça esse episódio do MIPD47.

Glyphosat stellt eine enorme Bedrohung für unsere Gesundheit dar. Bei 70 Prozent der Menschen finden sich erhöhte Werte. Auch die Bienen und damit der ganze Planet sind in Gefahr. Welches die häufigsten Quellen sind, welchen Schaden Glyphosat im Körper anrichtet und wie man sich davor schützen kann bespreche ich mit Nico DaVinci.     Stell dich kurz vor Was ist Glyphosat? Es wird oft gesagt, dass Glyphosat nicht schädlich ist. Wie kommt es zu diesen Aussagen und was ist dran? Wie wirkt Glyphosat auf unseren Körper? Chelator, Shikimatweg, Aluminium phenylalanine, tyrosine, and tryptophan, Ubiquinone, Vitamin E, K, Folic Acid(B9), lignans (protect plants from diseases), phytochemicals Blocks enzyme EPSPS, which inhibits the synthesis of the aromatic AA phenylalanine, tyrosine, and tryptophan. Humans don’t have EPSPS, but bakteria, fungs, algae have. GPS downregulates all genes involved in the building of the armomatic AA, not only the shikimate pathway. Instead it upregulates 50 genes for cell motility and chemotaxis of bacteria (movement through gradients) Schlaf Gewicht zunehmen Glycin Nahrungsmittelunverträglichkeiten und Autoimmunkrankheiten Wirkung aufs Mikrobiom Worin finden wir Glyphosat? Welche Lebensmittel enthalten am meisten? Welche Werte sind ok? Wie kann ich mich vor Glyphosat schützen? Wie kann ich es effektiv ausleiten? Wo kann man Dich erreichen Was setzt du selber von alledem um? Wie ernährst du dich? Wo kann man Dich erreichen?   Hol dir die geballte Pflanzenpower für dein Gehin und Immunsystem >> hier klicken Hol dir jetzt die pure Energie!

Glyphosat stellt eine enorme Bedrohung für unsere Gesundheit dar. Bei 70 Prozent der Menschen finden sich erhöhte Werte. Auch die Bienen und damit der ganze Planet sind in Gefahr. Welches die häufigsten Quellen sind, welchen Schaden Glyphosat im Körper anrichtet und wie man sich davor schützen kann bespreche ich mit Nico DaVinci.     Stell dich kurz vor Was ist Glyphosat? Es wird oft gesagt, dass Glyphosat nicht schädlich ist. Wie kommt es zu diesen Aussagen und was ist dran? Wie wirkt Glyphosat auf unseren Körper? Chelator, Shikimatweg, Aluminium phenylalanine, tyrosine, and tryptophan, Ubiquinone, Vitamin E, K, Folic Acid(B9), lignans (protect plants from diseases), phytochemicals Blocks enzyme EPSPS, which inhibits the synthesis of the aromatic AA phenylalanine, tyrosine, and tryptophan. Humans don’t have EPSPS, but bakteria, fungs, algae have. GPS downregulates all genes involved in the building of the armomatic AA, not only the shikimate pathway. Instead it upregulates 50 genes for cell motility and chemotaxis of bacteria (movement through gradients) Schlaf Gewicht zunehmen Glycin Nahrungsmittelunverträglichkeiten und Autoimmunkrankheiten Wirkung aufs Mikrobiom Worin finden wir Glyphosat? Welche Lebensmittel enthalten am meisten? Welche Werte sind ok? Wie kann ich mich vor Glyphosat schützen? Wie kann ich es effektiv ausleiten? Wo kann man Dich erreichen Was setzt du selber von alledem um? Wie ernährst du dich? Wo kann man Dich erreichen?   Hol dir die geballte Pflanzenpower für dein Gehin und Immunsystem >> hier klicken

Glyphosat stellt eine enorme Bedrohung für unsere Gesundheit dar. Bei 70 Prozent der Menschen finden sich erhöhte Werte. Auch die Bienen und damit der ganze Planet sind in Gefahr. Welches die häufigsten Quellen sind, welchen Schaden Glyphosat im Körper anrichtet und wie man sich davor schützen kann bespreche ich mit Nico DaVinci.     Stell dich kurz vor Was ist Glyphosat? Es wird oft gesagt, dass Glyphosat nicht schädlich ist. Wie kommt es zu diesen Aussagen und was ist dran? Wie wirkt Glyphosat auf unseren Körper? Chelator, Shikimatweg, Aluminium phenylalanine, tyrosine, and tryptophan, Ubiquinone, Vitamin E, K, Folic Acid(B9), lignans (protect plants from diseases), phytochemicals Blocks enzyme EPSPS, which inhibits the synthesis of the aromatic AA phenylalanine, tyrosine, and tryptophan. Humans don’t have EPSPS, but bakteria, fungs, algae have. GPS downregulates all genes involved in the building of the armomatic AA, not only the shikimate pathway. Instead it upregulates 50 genes for cell motility and chemotaxis of bacteria (movement through gradients) Schlaf Gewicht zunehmen Glycin Nahrungsmittelunverträglichkeiten und Autoimmunkrankheiten Wirkung aufs Mikrobiom Worin finden wir Glyphosat? Welche Lebensmittel enthalten am meisten? Welche Werte sind ok? Wie kann ich mich vor Glyphosat schützen? Wie kann ich es effektiv ausleiten? Wo kann man Dich erreichen Was setzt du selber von alledem um? Wie ernährst du dich? Wo kann man Dich erreichen?   Hol dir die geballte Pflanzenpower für dein Gehin und Immunsystem >> hier klicken Hol dir jetzt die pure Energie!

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.04.186478v1?rss=1 Authors: Zhang, X., Schloegl, A., Vandael, D., Jonas, P. Abstract: To understand the mechanisms of information coding in single neurons, it is necessary to analyze subthreshold synaptic events, action potentials (APs), and the interrelation between these two forms of activity in different behavioral states. However, detecting excitatory postsynaptic potentials (EPSPs) or currents (EPSCs) in awake, behaving animals remains challenging, because of unfavorable signal-to-noise ratio, high frequency, fluctuating amplitude, and variable time course of synaptic events. Here, we developed a new method for synaptic event detection, termed MOD (Machine-learning Optimal-filtering Detectionprocedure), which combines concepts of supervised machine learning and optimal Wiener filtering. First, experts were asked to manually score short epochs of data. Second, the algorithm was trained to obtain the optimal filter coefficients of a Wiener filter and the optimal detection threshold. Third, scored and unscored data were processed with the optimal filter, and events were detected as peaks above threshold. Finally, the area under the curve (AUC) of the receiver operating characteristics (ROC) curve was used to quantify accuracy and efficiency of detection. Additionally, cross-validation was performed to exclude overfitting of the scored data, a potential concern with machine-learning approaches. We then challenged the new detection method with EPSP traces in vivo in mice during spatial navigation and EPSC traces in vitro in slices under conditions of enhanced transmitter release. When benchmarked using a 1/(1-AUC) metric, MOD outperformed previous methods (template-fit and deconvolution) by a factor of up to 3. Thus, MOD may become an important tool for large-scale analysis of synaptic activity in vivo and in vitro. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.06.06.137844v1?rss=1 Authors: Bernstein, H. L., Lu, Y.-L., Botterill, J. J., Duffy, A. M., LaFrancois, J. J., Scharfman, H. E. Abstract: Glutamatergic dentate gyrus (DG) mossy cells (MCs) innervate the primary cell type, granule cells (GCs), and GABAergic neurons which inhibit GCs. Prior studies suggest that the net effect of MCs is mainly to inhibit GCs, leading one to question why direct excitation of GCs is often missed. We hypothesized that MCs do have excitatory effects, but each GC is only excited weakly, at least under most experimental conditions. To address this hypothesis, MC axons were stimulated optogenetically in slices. A brief optogenetic stimulus to MC axons in the inner molecular layer (IML) led to a short-latency field EPSP (fEPSP) in the IML, suggesting there was a direct excitatory effect on GCs. Population spikes were negligible however, consistent with weak excitation. FEPSPs reflected AMPA/NMDA receptor-mediated EPSPs in GCs. EPSPs reached threshold after GC depolarization or facilitating NMDA receptors. GABAA and GABAB receptor-mediated IPSPs often followed EPSPs. At the network level, an optogenetic stimulus led to a brief, small facilitation of the PP-evoked population spike followed by a longer, greater inhibition. These data are consistent with rapid and selective GC firing by MCs (MC [->] GC) and disynaptic inhibition (MC [->] GABAergic neuron [->] GC). Notably, optogenetic excitation was evoked for both dorsal and ventral MCs, ipsilateral and contralateral MC axons, and two Cre lines. Together the results suggest a way to reconcile past studies and provide new insight into the balance of excitation and inhibition of GCs by MCs. Copy rights belong to original authors. Visit the link for more info

The AHRI research paper: Glyphosate resistance in Tridax procumbens via a novel EPSPS Thr-102-Ser substitution", by Li et al, was published in the Journal of Agricultural and Food Chemistry 2018. This paper is a collaborative effort with researchers coming from China to AHRI and with modelling from Alex Nyporko from Kiev, Ukraine. Lead author Dr Jingbo Li from Hunan University and second author Dr Qiong Peng were visiting fellows in AHRI supported by the China Scholarship Council. In this research, it was first established that Tridax, a global tropical weed species, evolved glyphosate resistance in the Ord River irrigation area in north-western Western Australia. This is the first report of glyphosate resistance in Tridax. The mechanism of glyphosate resistance was studied.  Various possible resistance mechanisms were NOT responsible for resistance (EPSPS gene amplification, different glyphosate uptake or translocation). In this glyphosate-resistant Tridax population, the glyphosate resistance mechanism is a mutation in the EPSPS gene causing substitution at amino acid 102 (Thr-102-Ser). This is the first time that a single amino acid substitution at Thr 102 has been reported to endow glyphosate resistance. Note that Tridax is a tetraploid and this Thr-102-Ser amino acid substitution, as expected in a tetraploid species,  confers only a modest level of glyphosate resistance. This finding of a resistance endowing amino acid substitution at amino acid 102 adds to the many reports of glyphosate resistance due to amino acid substitutions at Proline 106.  The 102 site is within the highly conserved and catalytically important EPSPS region. We have previously reported in Eleusine that a double mutation at amino acids 102 and 106, the TIPS mutations, confer high-level glyphosate resistance but at substantial fitness cost (Yu et al Plant Physiology 2015). Dr Heping Han explains the research in the podcast. You can also learn more about this research in AHRI insight: https://ahri.uwa.edu.au/rare-but-predictable-a-new-target-site-mutation-for-glyphosate-resistance-discovered/ Authors: Jingbo Li, Qiong Peng, Heping Han, Alex Nyporko, Tymofii Kulynych, Qin Yu, Stephen Powles.

This podcast with AHRI Principal Research Fellow Dr Qin Yu focuses on explaining some of the more tricky aspects of the paper: A double EPSPS gene mutation endowing glyphosate resistance shows a remarkably high resistance cost This paper was a collaboration between AHRI researchers Heping Han, Qin Yu, and Steve Powles, as well as past AHRI researchers Adam Jalaludin and Martin Vila-Aiub. AHRI researcher Heping Han and others with GRDC support recently found a large fitness penalty in glyphosate-resistant crowsfoot grass. We have previously reported on this glyphosate resistance here. At the time we could see by looking at the pictures of the plants that the ones with the homozygous TIPS mutation were severely stunted. The researchers have now further investigated this and found that the homozygous TIPS plants have 50% reduction in seed set and this escalates to 85% in plants that are in competition with a rice crop. The TIPS mutation that causes high-level glyphosate resistance affects plant fitness. The TIPS mutation is a double mutation of the glyphosate target site, the 102 and the 106 mutation. The 106 mutation has been found in a number of species and has no fitness penalty associated with it, but the 102 + 106 mutation comes with a big fitness penalty. Most of the known glyphosate resistance mechanisms cause fairly low level, 4 to 8-fold, resistance. The TIPS mutation causes huge, 140 to 180-fold resistance with some plants surviving more than 57 L/ha glyphosate. The last AHRI insight of 2017 focuses on explaining this paper. You can read it here. By listening to this podcast first, you'll have a good understanding of the background information and better understand the commentary in AHRI insight and the paper. Music: bensound.com

Abstract In this study, two topics causing major public concern related to transgenic plants were investigated: The possibility of a horizontal gene transfer from plant to bacteria and the impact of transgenic plants after herbicide treatment on root associated bacteria. The transgenic plant chosen for this study was Roundup Ready® (RR) soybean, which is tolerant to the herbicide glyphosate and is the most commonly used genetically modified crop worldwide. Glyphosate, the active ingredient of Roundup Ready®, inhibits the EPSPS enzyme (5-enolpyruvylshikimate-3-phosphate synthase). EPSPS is an enzyme involved in the shikimic acid pathway leading to the aromatic amino acid biosynthesis and its inhibition leads to growth reduction of plants and microorganisms. RR crops are glyphosate tolerant due to the introduction of the CP4-EPSPS gene coding for a glyphosate insensitive EPSPS enzyme. The transgenic construct is under expression of a CaMV 35S promoter a nos transcriptional termination element from Agrobacterium tumefaciens. Horizontal gene transfer experiments with the EPSPS gene of the RR soybean were performed under controlled laboratory conditions and were targeted to the nitrogen fixing symbiont of soybean Bradyrhizobium japonicum. This bacterium comprises the requirements of a possible receptor for the glyphosate resistance trait, as it is sensitive to the herbicide and thus the acquirement of glyphosate resistance would signify a positive adaptation to glyphosate accumulated in the roots after herbicide application. Two key conditions for gene transfer from the CP4-EPSPS gene from the RR soybean to B. japonicum were evaluated in this study: The required specific conditions for B. japonicum to undergo natural transformation and the expression of the CP4-EPSPS gene in B. japonicum. For that purpose, the CP4-EPSPS gene was cloned into a B. japonicum chromosomal integration vector and was transferred by biparental mating into the B. japonicum genome. Subsequently, the expression of the CP4-EPSPS gene in B. japonicum was tested under increasing glyphosate selection pressure. Results of these experiments indicated that B. japonicum is not naturally transformable under any conditions known from the more than 40 so far reported naturally transformable bacteria. Furthermore, the CP4-EPSPS genetic construct, as contained in RR soybean, has been shown in this study to be not active in B. japonicum. Consequently, if there would be a gene transfer of the plant CP4-EPSPS to B. japonicum, this genetic construct does not confer glyphosate resistance to B. japonicum and does not constitute any adaptive advantage to the bacterium under glyphosate selection pressure. As the genetic trait of glyphosate resistance has been found in several bacteria, it would be more probable that the common mating exchange between bacterial groups could disperse the glyphosate resistance within an environment. Moreover, in the specific case of B. japonicum, a high spontaneous mutation rate for glyphosate resistance was observed, suggesting that B. japonicum can also adapt to the glyphosate selection pressure by mutation under natural conditions. The impact of transgenic plants with their respective herbicide treatments on root associated bacteria was investigated in a greenhouse experiment. The composition and diversity of bacterial communities of RR soybean rhizospheres were analyzed and compared between glyphosate-treated and untreated plants. Samples from five harvests with two glyphosate applications were analysed by 16S rRNA gene T-RFLP analysis complemented with the evaluation of three clone libraries. Multivariate statistical analysis of the data was used to visualize changes in the microbial populations in response to glyphosate applications and in order to find groups of organisms responsible for the observed community shifts. A comparison of the rhizosphere communities revealed that a Burkholderia related group was significantly inhibited by glyphosate application, while the abundance of a group of Gemmatimonadetes related sequences increased significantly after the herbicide treatment. The significant increment of Gemmatimonadetes abundance after glyphosate application could indicate that these organisms are able to metabolize the herbicide. Shannon diversity indices were calculated based on the T-RFLP results with the aim to compare bacterial diversity in the rhizosphere of glyphosate-treated and non treated RR soybeans. Interestingly, the bacterial community associated to RR soybean roots after glyphosate application not only demonstrated effective resilience after the disturbance but in addition the bacterial diversity also increased in comparison to the untreated control samples. It is possible, that in an environment with organisms which are able to metabolize glyphosate, the key for enhancing diversity could be the succession of metabolites, which can be further utilized by a diverse range of bacteria.

1. Intracellular microelectrodes were used to obtain recordings from neurons in layer II/III of rat frontal cortex. A bipolar electrode positioned in layer IV of the neocortex was used to evoke postsynaptic potentials. Graded series of stimulation were employed to selectively activate different classes of postsynaptic responses. The sensitivity of postsynaptic potentials and iontophoretically applied neurotransmitters to the non-N-methyl-D-asparate (NMDA) antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) was examined. 2. As reported previously, low-intensity electrical stimulation of cortical layer IV evoked short-latency early excitatory postsynaptic potentials (eEPSPs) in layer II/III neurons. CNQX reversibly antagonized eEPSPs in a dose-dependent manner. Stimulation at intensities just subthreshold for activation of inhibitory postsynaptic potentials (IPSPs) produced long-latency (10 to 40-ms) EPSPs (late EPSPs or 1EPSPs). CNQX was effective in blocking 1EPSPs. 3. With the use of stimulus intensities at or just below threshold for evoking an action potential, complex synaptic potentials consisting of EPSP-IPSP sequences were observed. Both early, Cl(-)-dependent and late, K(+)-dependent IPSPs were reduced by CNQX. This effect was reversible on washing. This disinhibition could lead to enhanced excitability in the presence of CNQX. 4. Iontophoretic application of quisqualate produced a membrane depolarization with superimposed action potentials, whereas NMDA depolarized the membrane potential and evoked bursts of action potentials. At concentrations up to 5 microM, CNQX selectively antagonized quisqualate responses. NMDA responses were reduced by 10 microM CNQX. D-Serine (0.5-2 mM), an agonist at the glycine regulatory site on the NMDA receptor, reversed the CNQX depression of NMDA responses.

1. Intracellular recordings were obtained from neurons in layer II/III of rat frontal cortex. Single-electrode current- and voltage-clamp techniques were employed to compare the sensitivity of excitatory postsynaptic potentials (EPSPs) and iontophoretically evoked responses to N-methyl-D-aspartate (NMDA) to the selective NMDA antagonist D-2-amino-5-phosphonovaleric acid (D-2-APV). The voltage dependence of the amplitudes of the EPSPs before and after pharmacologic changes in the neuron's current-voltage relationship was also examined. 2. NMDA depolarized the membrane potential, increased the neuron's apparent input resistance (RN), and evoked bursts of action potentials. The NMDA-induced membrane current (INMDA) gradually increased with depolarization from -80 to -40 mV. The relationship between INMDA and membrane potential displayed a region of negative slope conductance in the potential range between -70 and -40 mV which was sufficient to explain the apparent increase in RN and the burst discharges during the NMDA-induced depolarization. 3. Short-latency EPSPs (eEPSPs) were evoked by low-intensity electrical stimulation of cortical layer IV. Changes in the eEPSP waveform following membrane depolarization and hyperpolarization resembled those of NMDA-mediated responses. However, the eEPSP was insensitive to D-2-APV applied at concentrations (up to 20 microM) that blocked NMDA responses. 4. EPSPs with latencies between 10 and 40 ms [late EPSPs (lEPSPs)] were evoked by electrical stimulation using intensities just subthreshold to the activation of IPSPs. The amplitude of the lEPSP increased with hyperpolarization and decreased with depolarization. 5. The lidocaine derivative QX-314, injected intracellularly, suppressed sodium-dependent action potentials and depolarizing inward rectification. Simultaneously, the amplitude of the eEPSP significantly decreased with depolarization. Neither the amplitude of a long-latency EPSP nor the amplitude of inhibitory postsynaptic potentials (IPSPs) was significantly affected by QX-314. 6. Cesium ions (0.5-2.0 mM) added to the bathing solution reduced or blocked hyperpolarizing inward rectification. Under these conditions, the amplitude of the eEPSP increased with hyperpolarization. The amplitude of the lEPSP was unaltered or enhanced. 7. The lEPSP was reversibly blocked by D-2-APV (5-20 microM), although the voltage-dependence of its amplitude did not resemble the action of NMDA on neocortical neurons.

1. To investigate excitatory postsynaptic potentials (EPSPs), intracellular recordings were performed in layer II/III neurons of the rat medial frontal cortex. The average resting membrane potential of the neurons was more than -75 mV and their average input resistance was greater than 20 M omega. The amplitudes of the action potentials evoked by injection of depolarizing current pulses were greater than 100 mV. The electrophysiological properties of the neurons recorded were similar to those of regular-spiking pyramidal cells. 2. Current-voltage relationships, determined by injecting inward and outward current pulses, displayed considerable inward rectification in both the depolarizing and hyperpolarizing directions. The steady-state input resistance increased with depolarization and decreased with hyperpolarization, concomitant with increases and decreases, respectively, in the membrane time constant. 3. Postsynaptic potentials were evoked by electrical stimulation via a bipolar electrode positioned in layer IV of the neocortex. Stimulus-response relationships, determined by gradually increasing the stimulus intensity, were consistent among the population of neurons examined. A short-latency EPSP [early EPSP (eEPSP)] was the response with the lowest threshold. Amplitudes of the eEPSP ranged from 4 to 8 mV. Following a hyperpolarization of the membrane potential, the amplitude of the eEPSP decreased. Upon depolarization, a slight increase in amplitude and duration was observed, accompanied by a significant increase in time to peak. 4. The membrane current underlying the eEPSP (eEPSC) was measured using the single-electrode voltage-clamp method. The amplitude of the eEPSC was apparently independent of the membrane potential in 8 of 12 neurons tested. In the other 4 neurons, the amplitude of the eEPSC increased with hyperpolarization and decreased with depolarization. 5. Higher stimulus intensities evoked, in addition to the eEPSP, a delayed EPSP [late EPSP (lEPSP)] in greater than 90% of the neurons tested. The amplitude of the lEPSP ranged from 12 to 20 mV, and the latency varied between 20 and 60 ms. The amplitude of the lEPSP varied with membrane potential, decreasing with depolarization and increasing following hyperpolarization. The membrane current underlying the lEPSP (lEPSC) displayed a similar voltage dependence. 6. At stimulus intensities that led to the activation of inhibitory postsynaptic potentials (IPSPs), the lEPSP was no longer observed.

The present study examined the role of N-methyl-D-aspartic acid (NMDA) receptors in synaptic plasticity in regular-spiking cells of rat frontal cortex. Intracortical stimulation, at levels subthreshold for elicitation of action potentials, evoked a late excitatory postsynaptic potential (EPSP) in layer II III neurons that was sensitive to the selective NMDA antagonist -2-amino-5-phosphonovaleric acid (APV). This late EPSP showed marked short-term frequency-dependent depression, suggesting that it is polysynaptic in origin. Polysynaptic late EPSPs were selectively enhanced following high-frequency stimulation. This sustained increase in synaptic efficacy, or long-term potentiation, was expressed in regular spiking cells and appeared to result from activation of NMDA receptors on excitatory interneurons. These data demonstrate the existence of an NMDA-modulated polysynaptic circuit in the neocortex which displays several types of use-dependent plasticity.

Responses to bath-applications of 4-aminopyridine (4-AP) and -aminobutyric acid (GABA) were recorded intracellularly from neurones in the rat isolated superior cervical ganglion. 4-aminopyridine (0.1–1.0 mmol/l) usually induced spontaneous action potentials and excitatory postsynaptic potentials (EPSPs), which were blocked by hexamethonium. Membrane potential was unchanged; spike duration was slightly increased. Vagus nerve B-and C-fibre potentials were prolonged. In 4-AP solution (0.1–0.3 mmol/l), GABA (0.1 mmol/l), 3-aminopropanesulphonic acid or muscimol evoked bursts of spikes and EPSPs in addition to a neuronal depolarization. These bursts, which were not elicited by glycine, glutamate, taurine or (±)-baclofen, were completely antagonised by hexamethonium, tetrodotoxin or bicuculline methochloride. It is concluded that: (a) 4-AP has a potent presynaptic action on sympathetic ganglia; (b) presynaptic actions of GABA can be recorded postsynaptically in the presence of 4-AP; and (c) the presynaptic GABA-receptors revealed in this condition are similar to those on the postsynaptic membrane.