We will consider a number of different consequences of survival circuit activation below. Here, we focus on information processing related to trigger detection. Above we briefly noted the species-specific nature of innate trigger stimuli. While the original idea

of the ethologists focused on complex Gestalt configural stimuli and pattern recognition, simpler features are now emphasized. check details Thus, a rat can recognize a predator (cat, fox) by specific chemical constituents of predator odors (Wallace and Rosen, 2000, Vyas et al., 2007, Dielenberg et al., 2001, Markham et al., 2004 and Blanchard et al., 2003) and does not have to recognize the predator as a complex perceptual pattern. Moreover, humans can recognize certain emotions

by the eyes alone and do not need to process the face as a whole (e.g., Whalen et al., 2004), RO4929097 in vivo and evidence exists that this can be handled subcortically (Liddell et al., 2005, Morris et al., 1999, Tamietto et al., 2009 and Luo et al., 2007). These findings are consistent with the notion that that relatively simple sensory processing by subcortical areas can provide the requisite inputs to structures such as the amygdala, bypassing or short-circuiting cortical areas (LeDoux, 1996). In contrast to innate trigger stimuli, learned triggers are less restricted by species characteristics. Thus, many (though not all, as noted above) stimuli can be associated with harm and become a trigger Dichloromethane dehalogenase of defense circuits later. In the field of emotion, the term automatic appraisal is sometimes used when discussing how significant stimuli elicit so-called emotional responses automatically (without deliberate control), and is contrasted with cognitive or reflective appraisal, where processing that is

deliberate, controlled and often conscious, determines stimulus meaning and predisposes actions (e.g., Arnold, 1960, Bowlby, 1969, Frijda, 1986, Lazarus, 1991a, Lazarus, 1991b, Leventhal and Scherer, 1987, Lazarus and Folkman, 1984, Smith and Ellsworth, 1985, Scherer, 1988, Scherer et al., 2001, Sander et al., 2005 and Jarymowicz, 2009). The stimulus significance evaluations by survival circuits are obviously more in line with automatic, unconscious appraisal mechanisms. However, while stimulus evaluations by survival circuits is clearly an example of automatic appraisal, one should not be too quick to assume that what psychologists refer to as automatic appraisals in humans is identical to survival circuit processing. The latter probably refers to a narrower set of phenomena than the former, at least in humans, if not other species, though the range of phenomena in question clearly overlap. So far we’ve seen that unconditioned and conditioned emotional stimuli can be thought of in other terms, as unconditioned and conditioned survival circuit triggers.

This “critical period” usually takes place during the late postdoctoral years, but the program is also appropriate for advanced graduate students and new Assistant Professors. Fellows are responsible for administering their own summer research (e.g., animal protocols, research budget, equipment selection, Anti-cancer Compound Library supplier and installation) and are generously supported by the Grass Foundation and by a range of companies that provide much of the equipment and software necessary to conduct cutting-edge research. Why is this program at the Marine Biological Laboratory?

In our opinion, there is not a better place to expose beginning neuroscientists to the excitement of research than the Marine Biological Laboratory. Founded in 1888, the MBL is a private, not-for-profit corporation and is home to scientists who are recognized authorities in their fields. The 270 year-round scientists and Z-VAD-FMK chemical structure staff are joined each year by more than 400 visiting scientists, summer staff, and research associates from hundreds of institutions around the world.

Among the scientists with a significant affiliation with the MBL are 54 Nobel Prize winners, 196 Members of the National Academy of Sciences, and 171 Members of the American Academy of Arts and Sciences. Resonating with Humphry Davy’s conception of science, the MBL embraces the philosophy that “the single greatest discovery is the realization that every discovery paves the way to future discoveries” (http://www.mbl.edu/videos). The MBL is not only recognized for the quality and contributions of its researchers but also for Carnitine dehydrogenase its commitment to the education of students. Its outstanding educational programs include a variety of world-renowned summer courses focused on various biological disciplines, and hundreds of scientists from around the world come to Woods Hole during the summer to engage in the research and educational activities of the MBL. The study of the nervous

system at the MBL was first recognizable in 1891 by Herbert Henry Donaldson’s presentation of a talk entitled “Methods of Studying the Nervous System” (Maienschein, 1990). Subsequently, Charles Otis Whitman (a zoologist who made major contributions in the areas of evolution, embryology, and animal behavior), the first MBL director, asked the comparative anatomist Howard Ayers to organize a neurological seminar. During the 19th century, comparative anatomical analyses in fishes and amphibians led to major breakthroughs in the understanding of the vertebrate nervous system. Although the seminar continued for only 3 years, 1896–1898 (Maienschein, 1990), the interest in neurological work has continued at the Marine Biology Laboratory. Notably, the studies on the Limulus lateral eye by H.

183 (Wilcoxon test: p = 0.782). In control rats injected with vehicle the average mEPSC amplitude was similar in the contra and ipsilateral NVP-BKM120 chemical structure cortices (Contra: 11.10 ± 0.10 pA, n = 11 cells; Ipsi: 10.94 ± 0.08 pA, n = 16 cells, five rats; Wilcoxon test: p = 0.2375) (Figure 7E) in all animals tested (p = 0.73) (Figure 7E) indicating that visual stimulation

per se, does not produce plastic changes in mEPSC amplitude. The distribution of mEPSCs in the ipsilateral (nonstimulated) cortex was similar to the distribution of the contralateral mEPSCs (Wilcoxon test: p = 0.4298) (Figure 7E), and also similar to the distribution of ipsilateral mEPSCs from rats treated with methoxamine or isoproterenol, supporting the idea that neuromodulators promote changes in activated synapses only. Finally, we examined the role of NMDA receptors and tested the effects of systemic injection of the competitive antagonist CPP (15 mg/kg UMI-77 clinical trial i.p 20 min prior monocular stimulation), a dose that blocks experience-dependent plasticity without affect visual responses (Frenkel et al., 2006 and Sato

and Stryker, 2008). The CPP injections consistently abolished the differences in mEPSC amplitude between the contra- and ipsilateral cortices in rats treated with methoxamine (n = 5; Wilcoxon test: p = 0.8489) or isoproterenol (n = 5; Wilcoxon test: p = 0.9686) (Figure 7F), which is consistent with a role of NMDAR in the visually induced plasticity promoted by neuromodulators. A two-way ANOVA test confirmed the significance of the differences in mEPSC amplitude across treatments (F(9,196) = 10.4139, p < 0.001) (Figure 7G). The frequency of the mEPSCs, on the other hand, was not affected (two-way unless ANOVA, F(9,196) = 0.9163, p = 0.512) (Figure 7H). Altogether the results indicate that activation of α and β adrenoreceptors can be used to globally

potentiate and depress synapses in a controlled manner. The results described above (Figure 7) suggest that monocular stimulation induced LTD throughout the contralateral cortex when delivered in conjunction with methoxamine, and induced LTP when delivered with isoproterenol. To further examine this idea we tested whether the treatment with neuromodulators and monocular stimulation, as it induced plasticity in vivo, occludes subsequent pairing-induced LTD or LTP in vitro. In control rats (stimulated but injected with vehicle, n = 5 rats) (Figure 8B) both hemispheres expressed comparable magnitude of LTP (p = 0.23) and LTD (p = 0.56). In stimulated rats injected with methoxamine (n = 7 rats) (Figure 8C) LTD was robust in the ipsilateral hemisphere (nonstimulated cortex) but absent in the contralateral one (p < 0.0001), consistent with the idea that LTD was already induced in these synapses. Interestingly, pairing at 0mV potentiated synapses in the contralateral, but not in the ipsilateral, hemisphere (p < 0.0001).

The investigation of another one of these interactors is presented here. This protein interacts with DBT in vitro, in S2 cells, and in fly heads, and it is essential for normal cycles of PER nuclear accumulation and circadian behavior. Selleckchem Kinase Inhibitor Library Genetic analysis in flies and cell biological analysis in Drosophila S2 cells demonstrate

that it stimulates DBT’s clock functions, including phosphorylation-dependent degradation of PER. Immunofluorescent analysis indicates that this DBT-interacting protein accumulates rhythmically in cytosolic foci at times when PER begins to accumulate in the nuclei of circadian cells. Furthermore, structural analysis demonstrates that this interactor is a noncanonical FK506-binding protein, thus highlighting a hitherto uncharacterized role for this class of proteins in the circadian clock. DBT proteins from S2 cells stably transformed with plasmid expressing MYC-tagged DBT proteins were immunoprecipitated

with an anti-MYC resin, and coimmunoprecipitating proteins were visualized by SDS-PAGE. One protein immunoprecipitated with full-length DBTWT or catalytically inactive DBTK/R, but not with C-terminally truncated forms of DBT, and it was identified by mass spectrometry to be CG17282 (Table S1 available online). CG17282 is a previously unstudied predicted gene in the Drosophila genome sequence. Several approaches were employed to confirm the interaction with DBT. Using glutathione S-transferase (GST)-fused DBT, we are able to pull down in vitro-translated CG17282 (Figure 1A). Moreover, CG17282 was also shown to bind with DBT-MYC expressed from a transgene in S2 cells by coimmunoprecipitation (Figure 1B). DBT-MYC expressed in Trichostatin A molecular weight fly heads with the circadian already driver timGAL4 coimmunoprecipitated with CG17282 ( Figure 1C). Finally, as will be explained below, we were intrigued by the apparent lack of known functional domains in the N-terminal region of CG17282 and decided to test whether this region could

mediate direct interaction with DBT. Because S2 cells express low levels of CG17282 and DBT, which could complicate interpretation of the binding data, we conducted pull-down experiments in HEK293 cells and found that DBT bound to the N-terminal region of CG17282 ( Figure 1D). In order to determine whether CG17282 binds directly to PER, in vitro-translated PER was incubated with GST-CG17282, and no interaction with PER was detected by GST pull-down (Figure S1). Therefore, it is unlikely that CG17282 binds PER directly. Because it encodes a DBT-binding protein, we have named this gene bride of dbt (bdbt), with a nod to a previous gene discovered as an interactor ( Reinke and Zipursky, 1988). We employed several genetic approaches to assess whether Bride of DBT (BDBT) has a role in the mechanism of circadian rhythms. Overexpression of the FLAG-tagged BDBT in clock cells of flies (timGAL4 > UAS-bdbt-flag) did not produce an effect on their locomotor activity rhythms or PER/DBT expression ( Table S2; Figures S2, S3A, and S3B).

This question demands further study, but one possibility is that both CNIHs and TARPs function as auxiliary proteins at synapses. In this scenario, most AMPARs are associated with TARPs, but a larger proportion of intracellular AMPARs are exclusively associated with CNIHs, perhaps when localized to the ER or Golgi. The studies of CNIHs are particularly interesting because the strength of synaptic transmission depends on the number of receptors localized to the synapse; the conductance of each receptor; and the amount of time the receptors conduct current after glutamate binding. That TARPs and CNIHs separately or

together influence the trafficking and function of AMPARs has immediate implications for the modulation of synaptic transmission and may contribute to LTP Panobinostat and LTD (Kessels and Malinow, 2009). However, the definitive word on whether or how CNIHs contribute to synaptic AMPAR function awaits detailed analysis of cornichon mutants in mice or other organisms. In the last decade,

additional proteins that associate with AMPARs have been identified, starting with C. elegans SOL-1, a CUB-domain transmembrane this website protein that dramatically slows the rate of AMPAR desensitization and increases the rate of recovery from desensitization ( Walker et al., 2006 and Zheng et al., 2004). More recently, CKAMP44 was found to accelerate the rate of AMPAR desensitization ( von Engelhardt et al., 2010), and SynDIG1 regulates the development of excitatory synapses ( Kalashnikova et al., 2010). These are exciting times for the study of synaptic function. We have witnessed tremendous progress as the field has rapidly progressed from a channel-centric view to that of a receptor complex, with channel function modulated by different families of auxiliary proteins. An understanding of how these complexes are assembled, stabilized, and regulated seems essential for a mechanistic understanding of learning and memory. “
“Increasing evidence

suggests that L-NAME HCl the well-known action of the vesicular proton pump (vATPase) in acidifying synaptic vesicles is perhaps not the entire story of its interesting life. In addition to recent suggestions of its effects on SNARE complex formation and fusion pore formation, now comes evidence that its postexocytic pumping of protons out of the cell accelerates endocytosis. Previous studies have demonstrated an activity-dependent acidification of cytoplasm in cell bodies and dendrites of neurons. The work of Zhang et al. (2010), presented in this issue of Neuron, is the first to measure pH changes in mature nerve terminals resulting from nerve activity. Using a transgenic mouse expressing soluble Yellow Fluorescent Protein (YFP, whose fluorescence is quenched by protons) in its motor nerve terminals, they confirm that repetitive stimulation (50 Hz) produces fast acidification like that observed in cell bodies and dendrites.

Despite strong evidence showing substantive functional roles for many neuropeptides, at the cellular level a number of mysteries remain. Even seemingly straightforward questions can be complicated, such as: how far from a neuronal neuropeptide release site does a peptide act? For the amino acid neurotransmitters GABA, glycine, and glutamate, release occurs to a large degree at a presynaptic active zone, the transmitter diffuses a few tens of nanometers, activates receptors on the postsynaptic neuron, AZD8055 and then the transmitter is rapidly degraded or transported intracellularly. Amino acid transmitters act rapidly

at ionotropic receptors and at very discrete and spatially adjacent synaptic sites. Neuropeptides, in contrast, may be released from many additional release sites not restricted to the synaptic specialization, raising the question of where they act. For example, in classic Tanespimycin work on the frog sympathetic ganglia, a gonadotropin-releasing hormone (GnRH)-like peptide was released by preganglion axons and acted on cells some microns away from the release site (Jan and Jan, 1982). Even in the case of nonsynaptic release, a neuropeptide could still act on cells that are postsynaptic to the axon that releases it. For instance, GABAergic neuropeptide Y (NPY) cells of the arcuate nucleus

make synaptic contact with other nearby arcuate nucleus neurons that synthesize proopiomelanocortins (POMC); NPY hyperpolarizes the POMC neurons (Cowley et al., 2001), and therefore even though NPY may not be released synaptically, it can still exert an inhibitory effect on the cell postsynaptic to its parent axon. A second possibility that has received considerable attention is that the peptide can diffuse long distances to act far from the release site. Very long distance signaling has been found for a number of neuroactive peptides/proteins. For instance, leptin from adipose tissue, ghrelin from the stomach, and insulin

from the pancreas are released a long distance from the brain but act on receptors within the CNS as signals of energy homeostasis. The blood brain barrier may prohibit too entrance into the brain for many blood borne peptides; on the other hand, some regions of the brain such as the median eminence/arcuate nucleus may maintain a weak blood brain barrier which permits blood borne signals to enter the brain. Enhanced transport mechanisms may also exist for facilitating movement of some peptides into the brain. Long-distance signaling within the brain has been called volume transmission, and there is a substantial body of literature addressing this ( Fuxe et al., 2005, 2007; Jansson et al., 2002).

At the same time, through their mACT axonal projection, iPNs effectively send olfactory signals to the lateral horn (see below). Since both iPNs and vlpr neurons send processes to the lateral horn, IA-elicited Ca2+ signals within the lateral horn (Figure 1I) could be contributed by either or both of these neuronal

types. We next aimed to isolate putative postsynaptic signals of vlpr neurons from presynaptic selleck signals in iPNs within the same lateral horn using a laser transection protocol outlined in Figure 2A. Specifically, we first obtained lateral horn odor responses from control and experimental hemispheres. We then used Mz699-labeled iPN axons as a guide and applied spatially confined laser pulses from the two-photon laser (Ruta et al., 2010) to transect the mACT prior to its entry to the lateral horn on the experimental hemisphere. Following the laser transection, we again imaged lateral horn odor responses in both experimental and control hemispheres. Several lines of evidence suggested that our laser transection of mACT was complete and specific. First, we could observe a small selleckchem cavitation bubble at the mACT from basal GCaMP3 fluorescence with our two-photon microscope immediately following the laser application (Figure S3A), a hallmark of laser transection

(Vogel and Venugopalan, 2003). Second, retrospective immunostaining validated the complete transection of the mACT (Figure S3B, n = 15) with no visible effect on the integrity of the nearby iACT that conveys signals from the ePNs (data not shown). Third, odor-evoked GCaMP3 signals in

mACT near the lateral horn entry site (e.g., Figure 2B2, yellow arrow) were invariably abolished after laser transection of mACT (Figure 2B3, yellow arrow), validating that the responses observed in intact preparations were due to iPN contributions and were lost after mACT transection. Fourth, applying the same energy from the two-photon first laser at locations away from mACT did not cause similar changes in lateral horn Ca2+ signals (data not shown). Fifth, we did not detect changes of iPN responses in the antennal lobe before or after mACT transection (data not shown), suggesting that olfactory input still activates iPNs in the antennal lobe after mACT transection. Thus, we could assume that olfactory response in the lateral horn neuropil after mACT transection is mostly contributed by the vlpr neurons. How does iPN projection contribute to olfactory information processing at the lateral horn, and specifically, how are the responses of putative third-order vlpr neurons modulated by iPN input? To address these questions, we compared Ca2+ signals in response to isoamyl acetate application in the lateral horn (referred to as IA response hereafter) before and after laser transection (Figures 2B and 2C). In all cases, IA responses in the lateral horn were robust (Figure 2C).

For instance, a subset of neurons, i.e., those that become place cells, could possess dendritic segments with greater excitability (Frick et al., 2004 and Losonczy et al., 2008), organized such that a spatially uniform set of synaptic inputs is converted into a spatially tuned input as seen by the soma (Jia et al., 2010). These results should therefore lead to new classes of models (O’Keefe and Burgess, 2005, McNaughton et al., 2006, Solstad et al., 2006 and de Almeida et al., 2009) of place field formation based on grid cell (Hafting et al., 2005) or other inputs as well as models of memory formation

in general. Specifically, a role for intrinsic parameters should be added to that of external (e.g., sensory-driven) input. If intrinsic features are critical for selecting which cells become place BGB324 price cells, how do different environments become represented by different subsets of place cells (O’Keefe and Conway, 1978, Muller and Kubie, 1987, Thompson and Best, 1989 and Leutgeb et al., 2005)? In such a “global remapping,” many cells silent in one maze have place fields in another. Furthermore, ∼20%

of eventual place cells in a given novel environment are initially silent there (Hill, 1978 and Frank et al., 2004). Alisertib Thus, the selection factors cannot be permanently associated with each neuron. Instead, they may be randomized after a new map has been learned so that the next novel maze can be encoded by a statistically independent subset of place cells (Leutgeb et al., 2005). For this, the ability to alter burst propensity

(Staff et al., 2000 and Moore et al., 2009), the threshold (Figenschou et al., 1996), dendritic excitability (Frick et al., 2004 and Losonczy et al., 2008), or other forms of excitability (Oh Sodium butyrate et al., 2003) could be especially relevant (Zhang and Linden, 2003). However, it is still possible that a subset of neurons is silent in all environments (Thompson and Best, 1989). Lastly, what role do CSs play? Across repeated sessions in a given environment, the map is consistent (Thompson and Best, 1990), even with intervening sessions in other mazes (Leutgeb et al., 2005). But if the intrinsic features critical for place cell determination change, how is the correct map recalled when the animal encounters a familiar versus novel environment? The specific location of each place field appears to be determined very early during exploration of a novel maze (Figures 4A and 4H), and plasticity induced by the rhythmically occurring (Figures 2E, trace 1, 6C, S2B, and S2C), spatially tuned (Figure 6E) CSs may then refine (McHugh et al., 1996, Frank et al., 2004 and Karlsson and Frank, 2008) and stabilize (Kentros et al., 1998) that map for long-term storage—a process that should include converting the intrinsically based firing in a novel environment into synaptic-based firing as the environment becomes familiar.

, 2003, Jinno, 2009 and Takács et al., 2008) and was proposed to serve a hub function through an axon targeting distant regions (Buzsáki et al., 2004, Sik et al., 1994 and Sik et al., 1995). We next immunostained hippocampal sections containing EGins with a variety of classic interneuron markers. Given the late maturation of interneurons’ neurochemical content, only sections from adult mice were included here. Although parvalbumin (PV), calbindin (CB), vasoactive intestinal peptide (VIP), calretinin (CR), or nitric oxide

synthase (NOS) are prominently expressed by most hippocampal interneuron classes, almost none of the EGins were positive for these markers (Figures 3B and 3G–K). In contrast, a significant fraction of them were immunopositive for somatostatin (SOM) www.selleckchem.com/products/PLX-4032.html (45% ± 6%, n = 9 animals; Figures 3A and 3L). SOM-expressing hippocampal interneurons constitute a heterogenous population that includes O-LM and HIPP cells, hippocampo-subicular and hippocampo-septal projection neurons (Jinno et al., 2007) LY294002 in vitro as well as bistratified interneurons. In addition to SOM, O-LM cells also express PV (Ferraguti et al., 2004) and receive strong VIP positive inputs (Acsády et al., 1996). None of the EGins was positive for both SOM and PV (Figures 3C–3E and Figure S2B). Moreover, EGins did not receive strong VIP positive inputs (Figure S2A).

Therefore, we can exclude that a large number of EGins become O-LM why cells. Given this last result and the fact that the distribution and axonal arborization pattern of EGins resembled that of long-range projecting neurons, we next tested for the expression of mGluR1α and M2 receptor, both being additional characteristic markers of interneurons with extrahippocampal projections (Jinno et al., 2007). We found that a large majority of EGins was positive for mGluR1α (72.2% ± 7.7%, n = 5 mice; Figures 3A and 3L) and that a significant fraction of them expressed the M2 receptor (18.4% ± 2.5%, n = 4 mice; Figures 3F and 3L). In addition we tested for the coexpression of SOM and mGluR1α and found

that 53.4% ± 7.5% (n = 4 mice) of EGins coexpressed both markers, further indicating a long-range projecting phenotype. Because neurochemical marker expression is developmentally regulated, systematic testing and quantification of their presence within EGins was difficult to assess at P7. Nevertheless, SOM, mGluR1α, and M2 receptor immunoreactivities were found in EGins at early postnatal stages (Figures 2D–2F). In order to further exclude that EGins develop into basket-like or O-LM interneurons, we have patch-clamped and filled with neurobiotin EGins focusing on the CA3 region of slices prepared from adult mice (P25, n = 65 neurons). Out of 65 filled cells 38 were sufficiently recovered and 12 reconstructed. None of these cells showed any axonal or dendritic characteristics of O-LM or perisomatic interneurons (Figure S3).

monocytogenes strains (results not shown) using a rapid method described previously ( Borucki et al., 2003), were used to assess single and mixed species biofilm formation with L. plantarum WCFS1 ( Fig. 1). In BHI, the single species biofilms of L. monocytogenes EGD-e and LR-991 reached 8.5 and 9 log10 cfu/well, respectively, after 48-72 h, while PARP inhibitor the single species biofilm of L. plantarum contained 6.5 log10 cfu/well after 24 h, which decreased over time resulting in 5 log10 cfu/well after 72 h

( Fig. 1A). The number of L. monocytogenes in the mixed species biofilm in BHI was similar to the single species biofilm and 10-100 fold higher than the number of L. plantarum. Interestingly, in the mixed species biofilm, the amount of L. plantarum did not decrease over time as was seen in the L. plantarum single species biofilm. We were able to modulate the composition of the biofilms with the addition of glucose and/or manganese sulfate to BHI. These components increase the planktonic growth capabilities of L. plantarum and not of L. monocytogenes (results not shown). Single species biofilm formation of L. monocytogenes in BHI-Mn was similar to biofilm formation in BHI ( Fig. 1B). check details However, single species biofilms of L. plantarum in BHI-Mn contained 8 log10 cfu/well, which did not decrease over time as seen with biofilm formation in BHI. Furthermore, in BHI-Mn, equal numbers of L. monocytogenes and L. plantarum in the mixed species biofilm were observed

(approximately 8 log10 cfu/well). In BHI-Mn-G, L. monocytogenes single species biofilms contained 7.5-8 log10 cfu/well, while L. plantarum single species biofilms reached approximately 9 log10 cfu/well after 48-72 h ( Fig. 1C). The contribution of L. plantarum to the mixed species biofilm was also 10-100 times higher than the contribution of L. monocytogenes. L. plantarum reached approximately

9 log10 cfu/well after 48-72 h, while the contribution of L. monocytogenes decreased after 48-72 h to 6.5-7 log10 cfu/well. The decrease in L. monocytogenes viable counts in the mixed species biofilm might be related with the enhanced acidification by L. plantarum of the medium containing glucose, which reached approximately pH 3.4 after 48-72 h. In contrast, acidification during L. monocytogenes ADP ribosylation factor single species biofilm formation in medium containing glucose stopped at approximately pH 4.3. Single and mixed species biofilm formation in BHI and BHI containing manganese sulfate resulted in a final pH of approximately 5.3-5.5. The formation of single and mixed species biofilms was microscopically verified using bacteria expressing different fluorescent proteins. The formation of both single (Appendix 2) and mixed species biofilms (Fig. 2) was observed in all conditions. The biofilms of L. monocytogenes and L. plantarum grown in single and mixed species conditions consisted of a dense structure of multiple heterogeneous layers of cells showing a morphology very similar to planktonic grown cells of the two species.