Maintenance of Behavioral Variation under Predation Risk: Effects on Personality, Plasticity, and Predictability.

AbstractClassic evolutionary theory predicts that predation will shift trait means and erode variance within prey species; however, several studies indicate higher behavioral trait variance and trait integration in high-predation populations. These results come predominately from field-sampled animals comparing low- and high-predation sites and thus cannot isolate the role of predation from other ecological factors, including density effects arising from higher predation. Here, we study the role of predation on behavioral trait (co)variation in experimental populations of guppies (Poecilia reticulata) living with and without a benthic ambush predator (Jaguar cichlid) to better evaluate the role of predation and where density was equalized among replicates twice per year. At 2.5 years after introduction of the predators (∼10 overlapping generations), 40 males were sampled from each of the six replicate populations and extensively assayed for activity rates, water column use, and latency to feed following disturbance. Individual variation was pronounced in both treatments, with substantial individual variation in means, temporal plasticity, and predictability (inverse residual variance). Predators had little effect on mean behavior, although there was some evidence for greater use of the upper water column in predator-exposed fish. There was greater variance among individuals in water column use in predator-exposed fish, and they habituated more quickly over time; individuals higher in the water column fed slower and had a reduced positive correlation with activity, although again this effect was time specific. Predators also affected the integration of personality and plasticity-among-individual variances in water column use increased, and those in activity decreased, through time-which was absent in controls. Our results contrast with the extensive guppy literature showing rapid evolution in trait means, demonstrating either increases or maintenance of behavioral variance under predation.

Behavioural ecology meets oncology: quantifying the recovery of animal behaviour to a transient exposure to a cancer risk factor.

Wildlife is increasingly exposed to sublethal transient cancer risk factors, including mutagenic substances, which activates their anti-cancer defences, promotes tumourigenesis, and may negatively impact populations. Little is known about how exposure to cancer risk factors impacts the behaviour of wildlife. Here, we investigated the effects of a sublethal, short-term exposure to a carcinogen at environmentally relevant concentrations on the activity patterns of wild Girardia tigrina planaria during a two-phase experiment, consisting of a 7-day exposure to cadmium period followed by a 7-day recovery period. To comprehensively explore the effects of the exposure on activity patterns, we employed the double hierarchical generalized linear model framework which explicitly models residual intraindividual variability in addition to the mean and variance of the population. We found that exposed planaria were less active compared to unexposed individuals and were able to recover to pre-exposure activity levels albeit with a reduced variance in activity at the start of the recovery phase. Planaria showing high activity levels were less predictable with larger daily activity variations and higher residual variance. Thus, the shift in behavioural variability induced by an exposure to a cancer risk factor can be quantified using advanced tools from the field of behavioural ecology. This is required to understand how tumourous processes affect the ecology of species.

Predation impacts brain allometry in female guppies (Poecilia reticulata).

Cognitive and sensory abilities are vital in affecting survival under predation risk, leading to selection on brain anatomy. However, how exactly predation and brain evolution are linked has not yet been resolved, as current empirical evidence is inconclusive. This may be due to predation pressure having different effects across life stages and/or due to confounding factors in ecological comparisons of predation pressure. Here, we used adult guppies (Poecilia reticulata) to experimentally test how direct predation during adulthood would impact the relative brain size and brain anatomy of surviving individuals to examine if predators selectively remove individuals with specific brain morphology. To this end, we compared fish surviving predation to control fish, which were exposed to visual and olfactory predator cues but could not be predated on. We found that predation impacted the relative size of female brains. However, this effect was dependent on body size, as larger female survivors showed relatively larger brains, while smaller survivors showed relatively smaller brains when compared to control females. We found no differences in male relative brain size between survivors and controls, nor for any specific relative brain region sizes for either sex. Our results corroborate the important, yet complex, role of predation as an important driver of variation in brain size.

Understanding the unexplained: The magnitude and correlates of individual differences in residual variance.

Behavioral and physiological ecologists have long been interested in explaining the causes and consequences of trait variation, with a focus on individual differences in mean values. However, the majority of phenotypic variation typically occurs within individuals, rather than among individuals (as indicated by average repeatability being less than 0.5). Recent studies have further shown that individuals can also differ in the magnitude of variation that is unexplained by individual variation or environmental factors (i.e., residual variation). The significance of residual variation, or why individuals differ, is largely unexplained, but is important from evolutionary, methodological, and statistical perspectives. Here, we broadly reviewed literature on individual variation in behavior and physiology, and located 39 datasets with sufficient repeated measures to evaluate individual differences in residual variance. We then analyzed these datasets using methods that permit direct comparisons of parameters across studies. This revealed substantial and widespread individual differences in residual variance. The magnitude of individual variation appeared larger in behavioral traits than in physiological traits, and heterogeneity was greater in more controlled situations. We discuss potential ecological and evolutionary implications of individual differences in residual variance and suggest productive future research directions.

Repeatability and heritability of social reaction norms in a wild agamid lizard.

In the evolutionary transition from solitary to group living, it should be adaptive for animals to respond to the environment and choose when to socialize to reduce conflict and maximize access to resources. Due to the associated proximate mechanisms (e.g. neural network, endocrine system), it is likely that this behavior varies between individuals according to genetic and non-genetic factors. We used long-term behavioral and genetic data from a population of eastern water dragons (Intellagama lesueurii) to explore variation in plasticity of social behavior, in response to sex ratio and density. To do so, we modeled individual variation in social reaction norms, which describe individuals' mean behavior and behavioral responses to changes in their environment, and partitioned variance into genetic and non-genetic components. We found that reaction norms were repeatable over multiple years, suggesting that individuals consistently differed in their behavioral responses to changes in the social environment. Despite high repeatability of reaction norm components, trait heritability was below our limit of detection based on power analyses (h2 < 0.12), leading to very little power to detect heritability of plasticity. This was in contrast to a relatively greater amount of variance associated with environmental effects. This could suggest that mechanisms such as social learning and frequency-dependence may shape variance in reaction norms, which will be testable as the dataset grows.

Context-dependent trait covariances: how plasticity shapes behavioral syndromes.

The study of behavioral syndromes aims to understand among-individual correlations of behavior, yielding insights into the ecological factors and proximate constraints that shape behavior. In parallel, interest has been growing in behavioral plasticity, with results commonly showing that animals vary in their behavioral response to environmental change. These two phenomena are inextricably linked-behavioral syndromes describe cross-trait or cross-context correlations, while variation in behavioral plasticity describes variation in response to changing context. However, they are often discussed separately, with plasticity analyses typically considering a single trait (univariate) across environments, while behavioral trait correlations are studied as multiple traits (multivariate) under one environmental context. Here, we argue that such separation represents a missed opportunity to integrate these concepts. Through observations of multiple traits while manipulating environmental conditions, we can quantify how the environment shapes behavioral correlations, thus quantifying how phenotypes are differentially constrained or integrated under different environmental conditions. Two analytical options exist which enable us to evaluate the context dependence of behavioral syndromes-multivariate reaction norms and character state models. These models are largely two sides of the same coin, but through careful interpretation we can use either to shift our focus to test how the contextual environment shapes trait covariances.

Experimental translocations to low predation lead to non-parallel increases in relative brain size.

Predation is a near ubiquitous factor of nature and a powerful selective force on prey. Moreover, it has recently emerged as an important driver in the evolution of brain anatomy, though population comparisons show ambiguous results with considerable unexplained variation. Here, we test the reproducibility of reduced predation on evolutionary trajectories of brain evolution. We make use of an introduction experiment, whereby guppies (Poecilia reticulata) from a single high predation stream were introduced to four low predation streams. After 8-9 years of natural selection in the wild and two generations of common garden conditions in the laboratory, we quantified brain anatomy. Relative brain region sizes did not differ between populations. However, we found a general increase and striking variation in relative brain size of introduced populations, which varied from no change to a 12.5% increase in relative brain weight, relative to the ancestral high predation population. We interpret this as evidence for non-parallel evolution, which implies a weak or inconsistent association of relative brain size with fitness in low predation sites. The evolution of brain anatomy appears sensitive to unknown environmental factors, or contingent on either chance events or historical legacies of environmental change.

Bayesian updating during development predicts genotypic differences in plasticity.

Interactions between genotypes and environments are central to evolutionary genetics, but such interactions are typically described, rather than predicted from theory. Recent Bayesian models of development generate specific predictions about genotypic differences in developmental plasticity (changes in the value of a given trait as a result of a given experience) based on genotypic differences in the value of the trait that is expressed by naïve subjects. We used these models to make a priori predictions about the effects of an aversive olfactory conditioning regime on the response of Drosophila melanogaster larvae to the odor of ethyl acetate. As predicted, across 116 genotypes initial trait values were related to plasticity. Genotypes most strongly attracted to the odor of ethyl acetate when naïve reduced their attraction scores more as a result of the aversive training regime than those less attracted to the same odor when naïve. Thus, as predicted, the variance across genotypes in attraction scores was higher before than after the shared experience. These results support predictions generated by Bayesian models of development and indicate that such models can be successfully used to investigate how variation across genotypes in information derived from ancestors combines with personal experience to differentially affect developmental plasticity in response to specific types of experience.

Methodologies for the airbrush application of MALDI matrices.

There is still a need to develop reliable and robust matrix deposition methods for matrix-assisted laser desorption/ionisation mass spectrometry that are applicable to a range of matrices, solvents and analyte types. This paper presents a robust methodology for the airbrush application of matrices along with the implications of varying the set-up and airbrush parameters. A small number of organic analytes and metal salts are analysed in both positive and negative ion modes to exemplify this methodology. In the analyses with the airbrush deposited matrices, performance was enhanced when compared to standard pipette deposition with the need for a search for sweat spots greatly diminished due to the increase homogeneity of the matrix surface and resultant analyte spots. As expected, the graphite matrices were shown to specifically outperform the organic matrices in negative ion mode.

Is behavioural plasticity consistent across different environmental gradients and through time?

Despite accumulating evidence for individual variation in behavioural plasticity, there is currently little understanding of the causes and consequences of this variation. An outstanding question is whether individual reaction norm (RN) slopes are consistent across different environmental variables-that is, whether an individual that is highly responsive to one environmental variable will be equally responsive to a second variable. Another important and related question is whether RNs are themselves consistently expressed through time or whether they are simply state dependent. Here, we quantified individual activity rates of zebrafish in response to independent manipulations of temperature and food availability that were repeated in discrete 'bursts' of sampling through time. Individuals that were thermally responsive were not more responsive to food deprivation, but they did exhibit greater unexplained variation. Individual RN slopes were consistent (repeatable) over time for both temperature (Rslope = 0.92) and food deprivation responses (Rslope = 0.4), as were mean activity rates in the standard environment (Rintercept = 0.83). Despite the high potential lability of behaviour, we have demonstrated consistency of behavioural RN components and identified potential energetic constraints leading to high consistency of thermal RNs and low consistency of food deprivation RNs.

Towards powerful experimental and statistical approaches to study intraindividual variability in labile traits.

There is a long-standing interest in behavioural ecology, exploring the causes and correlates of consistent individual differences in mean behavioural traits ('personality') and the response to the environment ('plasticity'). Recently, it has been observed that individuals also consistently differ in their residual intraindividual variability (rIIV). This variation will probably have broad biological and methodological implications to the study of trait variation in labile traits, such as behaviour and physiology, though we currently need studies to quantify variation in rIIV, using more standardized and powerful methodology. Focusing on activity rates in guppies (Poecilia reticulata), we provide a model example, from sampling design to data analysis, in how to quantify rIIV in labile traits. Building on the doubly hierarchical generalized linear model recently used to quantify individual differences in rIIV, we extend the model to evaluate the covariance between individual mean values and their rIIV. After accounting for time-related change in behaviour, our guppies substantially differed in rIIV, and it was the active individuals that tended to be more consistent (lower rIIV). We provide annotated data analysis code to implement these complex models, and discuss how to further generalize the model to evaluate covariances with other aspects of phenotypic variation.

Live cell imaging of cytoplasmic dynein movement in transfected embryonic rat neurons.

Live cell imaging of the movement of various membrane-bounded organelle cargos has enhanced our understanding of their function. Eukaryotic cells utilize microtubules and two classes of microtubule-based motor proteins, cytoplasmic dynein and members of the kinesin family, to deliver a variety of membrane-bounded organelles and other cargos to their appropriate locations. In order to better understand the functions and regulation of cytoplasmic dynein, we developed a method to study its location and motility in living cells. The technique takes advantage of the long thin axons of cultured hippocampal neurons. We use calcium phosphate to transfect fluorescent-tagged dynein intermediate chain (IC) subunits (DYNC1I) into cultured neurons. When the ICs are expressed at low levels, they are effective probes for the location of the cytoplasmic dynein complex in axons when living cells are imaged with fluorescence microscopy. The fluorescent subunit probes can be used to identify specific cargos of dynein complexes with different IC isoforms as well as the kinetic properties of cytoplasmic dynein.

Detection of Mild and Reversible Neurohistopathological Changes in the Brain of Juvenile (Preweaned) Beagle Dogs Treated with Vigabatrin for up to 91 Days.

Neurohistopathological changes in the brain were assessed in juvenile beagle dogs given vigabatrin at 30 or 100 mg/kg/day by oral gavage from postnatal day 22 (PND22) until 16 weeks of age (PND112), when brain myelination is considered to reach the adult stage in dogs. Separate subgroups were treated from PND22 to PND35 or PND36 to PND49 to assess early effects. In addition to extensive brain histopathology, there were assessments of toxicokinetics, clinical condition, body weight, organ weights, and macroscopic pathology. In animals treated for 14 days from PND22, minimal or slight vacuolation was seen in the neuropil of the septal nuclei, hippocampus, hypothalamus, thalamus, cerebellum, and globus pallidus at 100 mg/kg/day and minimal vacuolation in the thalamus, globus pallidus, and cerebellum at 30 mg/kg/day. In animals given 100 mg/kg/day for 91 days from PND22, minimal or slight vacuolation was observed only in the hippocampus, hypothalamus, and thalamus. No vigabatrin-related brain vacuolation was observed in animals given 30 or 100 mg/kg/day for 14 days from PND36. Clear evidence of recovery was observed after 14-day and 6-week off-dose periods that followed treatment from PND22 to PND35 or PND22 to PND112, respectively.

Live cell imaging reveals differential modifications to cytoplasmic dynein properties by phospho- and dephosphomimic mutations of the intermediate chain 2C S84.

Cytoplasmic dynein is a multisubunit motor protein responsible for intracellular cargo transport toward microtubule minus ends. There are multiple isoforms of the dynein intermediate chain (DYNC1I, IC), which is encoded by two genes. One way to regulate cytoplasmic dynein is by IC phosphorylation. The IC-2C isoform is expressed in all cells, and the functional significance of phosphorylation on IC-2C serine 84 was investigated by using live cell imaging of fluorescent protein-tagged IC-2C wild type (WT) and phospho- and dephosphomimic mutant isoforms in axonal transport model systems. Both mutations modulated dynein functional properties. The dephosphomimic mutant IC-2C S84A had greater colocalization with mitochondria than the IC-2C WT or the phosphomimic mutant IC-2C S84D. The dephosphomimic mutant IC-2C S84A was also more likely to be motile than the phosphomimic mutant IC-2C S84D or the IC-2C WT. In contrast, the phosphomimic mutant IC-2C S84D mutant was more likely to move in the retrograde direction than was the IC-2C S84A mutant. The phosphomimic IC-2C S84D was also as likely as the IC-2C WT to colocalize with mitochondria. Both the S84D phospho- and the S84A dephosphomimic mutants were found to be capable of microtubule minus-end-directed (retrograde) movement in axons. They were also observed to be passively transported in the anterograde direction. These data suggest that the IC-2C S84 has a role in modulating dynein properties.

Trk activation of the ERK1/2 kinase pathway stimulates intermediate chain phosphorylation and recruits cytoplasmic dynein to signaling endosomes for retrograde axonal transport.

The retrograde transport of Trk-containing endosomes from the axon to the cell body by cytoplasmic dynein is necessary for axonal and neuronal survival. We investigated the recruitment of dynein to signaling endosomes in rat embryonic neurons and PC12 cells. We identified a novel phosphoserine on the dynein intermediate chains (ICs), and we observed a time-dependent neurotrophin-stimulated increase in intermediate chain phosphorylation on this site in both cell types. Pharmacological studies, overexpression of constitutively active MAP kinase kinase, and an in vitro assay with recombinant proteins demonstrated that the intermediate chains are phosphorylated by the MAP kinase ERK1/2, extracellular signal-regulated kinase, a major downstream effector of Trk. Live cell imaging with fluorescently tagged IC mutants demonstrated that the dephosphomimic mutants had significantly reduced colocalization with Trk and Rab7, but not a mitochondrial marker. The phosphorylated intermediate chains were enriched on immunoaffinity-purified Trk-containing organelles. Inhibition of ERK reduced the amount of phospho-IC and the total amount of dynein that copurified with the signaling endosomes. In addition, inhibition of ERK1/2 reduced the motility of Rab7- and TrkB-containing endosomes and the extent of their colocalization with dynein in axons. NGF-dependent survival of sympathetic neurons was significantly reduced by the overexpression of the dephosphomimic mutant IC-1B-S80A, but not WT IC-1B, further demonstrating the functional significance of phosphorylation on this site. These results demonstrate that neurotrophin binding to Trk initiates the recruitment of cytoplasmic dynein to signaling endosomes through ERK1/2 phosphorylation of intermediate chains for their subsequent retrograde transport in axons.

Rydberg gas theory of a glow discharge plasma: I. Application to the electrical behaviour of a fast flowing glow discharge plasma.

Current-voltage (I-V) curves have been measured, independent of the main discharge, for electricity passing through the steady state fast flowing 'afterglow' plasma of a low power dc glow discharge in Ar. Voltage profiles along the axial line of conduction have been mapped using fixed probes and potentiometry, and the mass spectra of cations emerging from the downstream sampling Cone, also acting as a probe anode, were recorded simultaneously. Floating double probe experiments were also carried out. The electrical behavior is consistent with the well established I-V characteristics of such discharges, but does not comply with classical plasma theory predictions. The plasma decays along the line of conduction, with a lifetime of approximately 1 ms, despite carrying a steady state current, and its potential is below that of the large surface area anode voltage; a situation which cannot exist in the presence of a conventional free ion-electron plasma, unless the electron temperature is super cold. Currents, large by comparison with the main discharge current, and independent of it, are induced to flow through the downstream plasma, from the Anode (acting as a cathode) to the anodic ion exit Cone, induced by electron impact ionisation at the anode, but without necessarily increasing the plasma density. It appears to be conducted by direct charge transfer between a part of the anode surface (acting as cathode to the auxiliary circuit) and the plasma, without secondary electron emission or heating, which suggests the direct involvement of Rydberg atom intermediates. The reaction energy defect (= the work function of the electrode surface) fits with the plasma potential threshold observed for the cathodic reaction to occur. A true free ion-electron plasma is readily detected by the observation of cations at the anode surface, when induced at the downstream anode, at high bias voltages, by the electron impact ionisation in the boundary region. In contrast to the classical model, the complex electrical (and mass spectrometric) behaviour fits qualitatively, but can be understood well, with the Rydberg gas model described in papers II and III (R. S. Mason, and R. S. Mason and P. Douglas, PCCP, 2010, DOI: 10.1039/b918081h and b918083d) over a wide range of probe bias voltages. The full cycle of behavior is then described for the development of a true secondary discharge within the downstream plasma.

The effect of coal and diesel particulates on the weathering loss of Portland Limestone in an urban environment.

Due to reductions in domestic usage, legislation and changes in fuel use, coal derived particulates in the UK urban atmosphere have been significantly reduced. However, a large increase in road usage and an expansion in the use of diesel engines, has meant that the majority of particulates, now present in the urban atmosphere, originate from vehicle exhausts. Particulate matter, resulting from coal combustion, has been recorded as being present in black patinas observed on some historic stone buildings and monuments and has been associated with accelerated weathering of stone surfaces as a result of enhanced gypsum formation. In contrast, the effects of particulates resulting from vehicle exhaust on stone are much less understood. To investigate this, a comparative study was undertaken using the technique of microcatchments under ambient atmospheric conditions. This compared the elemental composition and volume of precipitation runoff from Portland Limestone coated with three different particulate treatments. Treatments consisted of coal and diesel particulates, both separately and in combination. Combining these treatments attempts to investigate any synergistic effects that may occur when coal derived particulates are overlain by layers formed by particulates from more contemporary sources. It was found that diesel-coated samples were much darker in appearance and showed a significant reduction (P<0.05) in the overall rate of weathering loss when compared to untreated samples. Microcatchment runoff volume was reduced from diesel-coated Portland Limestone compared to untreated stone. Enhanced surface temperatures may be increasing the rate of moisture loss from the pore network between rainfall events. Since, generally, the pores must be full before runoff can occur, the reduction may be due to the differential volume of empty pore space between diesel-coated and untreated Portland Limestone.

Amelioration of the effects of Citrobacter rodentium infection in mice by pretreatment with probiotics.

BACKGROUND: Citrobacter rodentium is a naturally occurring murine pathogen that causes colonic epithelial-cell hyperplasia, disrupts the colonic mucosa, and elicits a predominantly T helper 1 cellular immune response; it thereby serves as a model for the study of mechanisms of disease induced by human attaching-effacing pathogens. We sought to determine whether pretreatment of mice with a mixture of Lactobacillus rhamnosus and L. acidophilus probiotics would attenuate C. rodentium-induced colonic disease in mice. METHODS: Mice were administered sterile drinking water, probiotics (10(9) cfu/mL) in sterile drinking water, maltodextrin in sterile drinking water, orogastric C. rodentium (10(7) cfu in 0.1 mL), or maltodextrin in sterile drinking water for 1 week before C. rodentium infection, or they were pretreated with probiotics (10(9) cfu/mL) for 1 week before challenge with C. rodentium. RESULTS: Mice that received viable probiotics remained healthy. C. rodentium infection elicited mucosal inflammation, epithelial-cell hyperplasia, apoptosis in the colon, and interferon (IFN)- gamma production by splenocytes. Pretreatment with probiotics decreased levels of all but IFN- gamma production. CONCLUSIONS: Pretreatment with probiotics attenuates the effects of C. rodentium infection in mice. Understanding the mechanism of these beneficial effects will aid in determining the efficacy of probiotics in preventing infection with related attaching-effacing enteric pathogens in humans.

In-use efficacy of a chlorhexidine in alcohol surgical rub: a comparative study.

BACKGROUND: Although full surgical scrubs are performed prior to each case on an operating list, optimum regimens for hand cleaning have yet to be determined, and in-use efficacy evaluations are very limited. METHODS: A crossover study was undertaken comparing a chlorhexidine in detergent/alcohol regimen with povidine-iodine detergent scrub, within an orthopaedic operating environment. Depending on the skin asepsis regimen used, five surgical team members scrubbed or rubbed prior to each case for a complete operating list. Bactericidal efficacy was measured using the 'glove-juice' technique before and after hand asepsis, and at the completion of each case. RESULTS: The chlorhexidine regimen caused substantial and sustained reductions in hand bacterial counts (>50-fold prior to case 1) during surgical cases. Application of alcoholic chlorhexidine prior to each subsequent case reduced bacterial counts to the same level as the original scrub. In contrast, the povidine-iodine scrub reduced counts <3-fold prior to the first case and <2-fold in subsequent cases. The chlorhexidine regimen also resulted in persistent bactericidal effects between cases, as counts prior to application of cases 2 and higher were significantly lower than prior to case 1 (>7-fold for case 2 vs case 1). CONCLUSIONS: The chlorhexidine regimen demonstrated excellent bactericidal efficacy throughout an operating list, and was superior to povidine-iodine scrubbing in all aspects. The alcoholic chlorhexidine regimen is simpler and should have wide surgical application.

Probiotics reduce bacterial colonization and gastric inflammation in H. pylori-infected mice.

Probiotics are characterized by their ability to interact with commensal microflora in the gastrointestinal tract to produce beneficial health effects. In vitro studies suggest that Lactobacillus species have the potential to suppress the growth of Helicobacter pylori. The goal of this study was to determine if pretreatment of mice with a commercial mixture of live probiotics (L. rhamnosus, strain R0011, and L. acidophilus, strain R0052) would suppress colonization of H. pylori, strain SS1. Thirty C57BL/6 female mice were divided into four groups: Group A was fed sterile water, group B received probiotics in sterile drinking water, group C was challenged orogastrically with H. pylori, and group D was pretreated with probiotics in drinking water prior to and following challenge with H. pylori. Rectal swabs, stomach homogenates, and luminal contents from ileum and colon were plated onto colistin nalidixic acid plates. Serial dilutions of stomach homogenates were plated onto H. pylori-sensitive agar plates and incubated under microaerophilic conditions. Tissue samples from the stomach were analyzed histologically to determine the degree of H. pylori colonization, mucosal inflammation, and epithelial cell apoptosis. Probiotics in drinking water did not affect the overall well-being of mice. Lactobacillus species were excreted in stools over the entire duration of treatment. Pretreatment with probiotics reduced the number of mice with H. pylori growth from stomach homgenates (100 to 50%; P = 0.02). The percentage of mice with moderate-severe H. pylori-induced inflammation in the gastric antrum was reduced with probiotic pretreatment (71 to 29%; P = 0.14). However, pretreatment with probiotics did not prevent H. pylori-induced apoptosis in the gastric mucosa. This preparation of probiotics provided a safe and novel approach for reducing H. pylori colonization and bacterial-induced inflammation of mice.