Water- and sediment-quality effects on Pimephales promelas spawning vary along an agriculture-to-urban land-use gradient

Many streams in the U.S. are “impaired” due to anthropogenic influence. For watershed managers to achieve practical understanding of these impairments, a multitude of factors must be considered, including point and nonpoint-source influence on water quality. A spawning assay was developed in this study to evaluate water- and sediment-quality effects that influenced Pimephales promelas (fathead minnow) egg production over a gradient of urban and agricultural land use in 27 small watersheds in Eastern Wisconsin. Six pairs of reproducing fathead minnows were contained in separate mesh cartridges within one larger flow-through chamber. Water- and sediment quality were sampled for an array of parameters. Egg production was monitored for each pair providing an assessment of spawning success throughout the 21-day test periods. Incidences of low dissolved oxygen (DO) in many of these streams negatively impacted spawning success. Nine of 27 streams experienced DO less than 3.1 mg/L and 15 streams experienced DO less than 4.8 mg/L. Low DO was observed in urban and agricultural watersheds, but the upper threshold of minimum DO decreased with increasing urban development. An increase in specific conductance was related to a decrease in spawning success. In previous studies for streams in this region, specific conductance had a linear relation with chloride, suggesting the possibility that chloride could be a factor in egg production. Egg production was lower at sites with substantial urban development, but sites with low egg production were not limited to urban sites. Degradation of water- and sediment-quality parameters with increasing urban development is indicated for multiple parameters while patterns were not detected for others. Results from this study indicate that DO must be a high priority watershed management consideration for this region, specific conductance should be investigated further to determine the mechanism of the relation with egg production, and water- and sediment-quality degrade in relation to urban influence.     

Entorhinal cortex lesions disrupt the transition between the use of intra- and extramaze cues for navigation in the water maze.

[Correction Notice: An erratum for this article was reported in Vol 117(5) of Behavioral Neuroscience (see record 2007-16848-001). The definitions "Present = intramaze landmark present during Stage 2" and "Absent = intramaze landmark absent during Stage 2" appear incorrectly in the caption to Figure 3. These terms and definitions should appear in the caption to Figure 4.] This study with rats examined the effects of excitotoxic lesions to the entorhinal cortex (EC) and hippocampus (HPC) on using extramaze and intramaze cues to navigate to a hidden platform in a water maze. HPC lesions resulted in a disruption to the use of extramaze cues, but not intramaze cues, whereas EC lesions had no effect on the use of these cues when they were encountered for the fast time. However, prior navigation training in which 1 type of cue was relevant disrupted navigation with the other type in rats with EC lesions. Results show that the EC contributes to the processing of spatial information, but that this contribution is most apparent when there is a conflict between 2 sources of navigational cues in the water maze. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cumulative physiological events influence the inflammatory response of the bovine udder to Escherichia coli infections during the transition period

A high proportion of intramammary coliform infections present at parturition develop disease characterized by severe inflammatory signs and sepsis during the first 60 to 70 d of lactation. In the lactating bovine mammary gland, the innate immune system plays a critical role in determining the outcome of these infections. Since the beginning of the 1990s, research has increased significantly on bovine mammary innate defense mechanisms in connection with the pathogenesis of coliform mastitis. Neutrophils are key effector cells of the innate immune response to intramammary infection, and their function is influenced by many physiological events that occur during the transition period. Opportunistic infections occur when the integrity of the host immune system is compromised by physical and physiological conditions that make the host more susceptible. The innate immune system of many periparturient cows is immunocompromised. It is unlikely that periparturient immunosuppression is the result of a single physiological factor; more likely, several entities act in concert, with profound effects on the function of many organ systems of the periparturient dairy cow. Their defense system is unable to modulate the complex network of innate immune responses, leading to incomplete resolution of the pathogen and the inflammatory reaction. During the last 30 yr, most efforts have been focused on neutrophil diapedesis, phagocytosis, and bacterial killing. How these functions modulate the clinical outcome of coliform mastitis, and how they can be influenced by hormones and metabolism has been the subject of intensive research and is the focus of this review. The afferent (sensing) arm of innate immunity, which enables host recognition of a diverse array of pathogens, is the subject of intense research interest and may contribute to the variable inflammatory response to intramammary infections during different stages of lactation. The development of novel interventions that modulate the inflammatory response or contribute to the elimination of the pathogen or both may offer therapeutic promise in the treatment of mastitis in periparturient cows.     

Characterization of the bovine innate immune response to intramammary infection with Klebsiella pneumoniae

Gram-negative bacteria are responsible for almost one-half of the clinical cases of mastitis that occur annually. Of those gram-negative bacteria that induce mastitis, Klebsiella pneumoniae remains one of the most prevalent. Detection of infectious pathogens and the induction of a proinflammatory response are critical components of host innate immunity. The objective of the current study was to characterize several elements of the bovine innate immune response to intramammary infection with Klebsiella pneumoniae. The inflammatory cytokine response and changes in the levels of soluble CD14 (sCD14) and lipopolysaccharide (LPS)-binding protein (LBP), 2 proteins that contribute to host recognition of gram-negative bacteria, were studied. The contralateral quarters of 7 late-lactating Holstein cows were challenged with either saline or K. pneumoniae, and milk and blood samples were collected. Initial increases in the chemoattractants C5a and IL-8, as well as TNF-alpha, were evident in infected quarters within 16 h of challenge and were temporally coincident with increases in milk somatic cells. Augmented levels of TNF-alpha and IL-8 were observed in infected quarters until >48 h postchallenge, respectively. Elevated levels of IL-12, IFN-gamma, and the antiinflammatory cytokine, IL-10, which were first detected between 12 and 20 h postinfection, persisted in infected quarters throughout the study (>96 h). Initial increases in milk LBP and sCD14 were detected 16 and 20 h, respectively, after challenge. Together, these data demonstrate that intramammary infection with K. pneumoniae elicits a host response characterized by the induction of proinflammatory cytokines and elevation of accessory molecules involved in LPS recognition.     

Effect of mastitis on milk perchlorate concentrations in dairy cows

Recent surveys have identified the presence of perchlorate, a natural compound and environmental contaminant, in forages and dairy milk. The ingestion of perchlorate is of concern because of its ability to competitively inhibit iodide uptake by the thyroid and to impair synthesis of thyroid hormones. A recent study established that milk perchlorate concentrations in cattle highly correlate with perchlorate intake. However, there is evidence that up to 80% of dietary perchlorate is metabolized in clinically healthy cows, thereby restricting the available transfer of ingested perchlorate into milk. The influence of mastitis on milk perchlorate levels, where there is an increase in mammary vascular permeability and an influx of blood-derived components into milk, remains unknown. The present study examined the effect of experimentally induced mastitis on milk perchlorate levels in cows receiving normal and perchlorate-supplemented diets. Over a 12-d period, cows were ruminally infused with 1 L/d of water or water containing 8 mg of perchlorate. Five days after the initiation of ruminal infusions, experimental mastitis was induced by the intramammary infusion of 100 μg of bacterial lipopolysaccharide (LPS). Contralateral quarters infused with phosphate-buffered saline served as controls. A significant reduction in milk perchlorate concentration was observed in the LPS-challenged glands of animals ruminally infused with either water or perchlorate. In control glands, milk perchlorate concentrations remained constant throughout the study. A strong negative correlation was identified between mammary vascular permeability and milk perchlorate concentrations in LPS-infused glands. These findings, in the context of a recently published study, suggest that an active transport process is operative in the establishment of a perchlorate concentration gradient across the blood-mammary gland interface, and that increases in mammary epithelial and vascular endothelial permeability lead to a net outflow of milk perchlorate. The overall finding that mastitis results in lower milk perchlorate concentrations suggests that changes in udder health do not necessitate increased screening of milk for perchlorate.     

Attentional bias to brief threat-related faces revealed by saccadic eye movements.

According to theories of emotion and attention, we are predisposed to orient rapidly toward threat. However, previous examination of attentional cueing by threat showed no enhanced capture at brief durations, a finding that may be related to the sensitivity of the manual response measure used. Here we investigated the time course of orienting attention toward fearful faces in the exogenous cueing task. Cue duration (20 ms or 100 ms) and response mode (saccadic or manual) were manipulated. In the saccade mode, both enhanced attentional capture and impaired disengagement from fearful faces were evident and limited to 20 ms, suggesting that saccadic cueing effects emerge rapidly and are short lived. In the manual mode, fearful faces impacted only upon the disengagement component of attention at 100 ms, suggesting that manual cueing effects emerge over longer periods of time. Importantly, saccades could reveal threat biases at brief cue durations consistent with current theories of emotion and attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

GluR-A-deficient mice display normal acquisition of a hippocampus-dependent spatial reference memory task but are impaired during spatial reversal.

Acquisition and reversal of a spatial discrimination were assessed in an appetitive, elevated plus-maze task in 4 groups of mice: knockout mice lacking the AMPA receptor subunit GluR-A (GluR1), wild-type controls, mice with cytotoxic hippocampal lesions, and controls that had undergone sham surgery. In agreement with previous studies using tasks such as the water maze, GluR-A-/- mice were unimpaired during acquisition of the spatial discrimination task, whereas performance in the hippocampal group remained at chance levels. In contrast to their performance during acquisition, the GluR-A-/- mice displayed a mild deficit during reversal of the spatial discrimination and were profoundly impaired during discrete trial, rewarded-alternation testing on the elevated T maze. The latter result suggests a short-term. flexible spatial working memory impairment in GluR-A-/- mice, which might also underlie their mild deficit during spatial reversal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociating context and space within the hippocampus: Effects of complete, dorsal, and ventral excitotoxic hippocampal lesions on conditioned freezing and spatial learning.

Rats with complete excitotoxic hippocampal lesions or selective damage to the dorsal or ventral hippocampus were compared with controls on measures of contextually conditioned freezing in a signaled shock procedure and on a spatial water-maze task. Complete and ventral lesions produced equivalent, significant anterograde deficits in conditioned freezing relative to both dorsal lesions and controls. Complete hippocampal lesions impaired water-maze performance; in contrast, ventral lesions improved performance relative to the dorsal group, which was itself unexpectedly unimpaired relative to controls. Thus, the partial lesion effects seen in the 2 tasks never resembled each other. Anterograde impairments in contextual freezing and spatial learning do not share a common underlying neural basis; complete and ventral lesions may induce anterograde contextual freezing impairments by enhancing locomotor activity under conditions of mild stress. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Increased levels of LPS-binding protein in bovine blood and milk following bacterial lipopolysaccharide challenge

Several species of gram-negative bacteria, including Escherichia coli, Klebsiella pneumoniae, and various species of Enterobacter, are common mastitis pathogens. All of these bacteria are characterized by the presence of endotoxin or lipopolysaccharide (LPS) in their outer membrane. The bovine mammary gland is highly sensitive to LPS, and LPS has been implicated, in part, in the pathogenesis of gram-negative mastitis. Recognition of LPS is a key event in the innate immune response to gram-negative infection and is mediated by the accessory molecules CD14 and LPS-binding protein (LBP). The objective of the current study was to determine whether LBP levels increased in the blood and mammary gland following LPS challenge. The left and right quarters of five midlactating Holstein cows were challenged with either saline or LPS (100 microg), respectively, and milk and blood samples collected. Basal levels of plasma and milk LBP were 38 and 6 microg/ml, respectively. Plasma LBP levels increased as early as 8 h post-LPS challenge and reached maximal levels of 138 microg/ ml by 24 h. Analysis of whey samples derived from LPS-treated quarters revealed an increase in milk LBP by 12 h. Similar to plasma, maximal levels of milk LBP (34 microg/ml) were detected 24 h following the initial LPS challenge. Increments in milk LBP levels paralleled a rise in soluble CD14 (sCD14) levels and initial rises in the levels of these proteins were temporally coincident with maximal neutrophil recruitment to the inflamed gland. Because LBP and sCD14 are known to enhance LPS-induced host cell activation and to facilitate detoxification of LPS, these data are consistent with a role for these molecules in mediating mammary gland responses to LPS.     

Innate immune response to intramammary Mycoplasma bovis infection

The objective of the current study was to characterize the systemic and local innate immune response of dairy cows to IMI with Mycoplasma bovis, a pathogen of growing concern to the dairy industry. Ten Holstein cows were each infused in 1 quarter with M. bovis and studied for a 10-d period. Acute phase protein synthesis, which reflects 1 parameter of the systemic response to infection, was induced within 108 h of infection, as evidenced by increased circulating concentrations of lipopolysaccharide binding protein and serum amyloid A. Transient neutropenia was observed from 84 to 168 h postinfection, whereas a constant state of lymphopenia and thrombocytopenia was observed from 84 h until the end of the study. Milk somatic cell counts initially increased within 66 h of M. bovis infusion and remained elevated, relative to control (time 0) concentrations, for the remainder of study. Increased milk concentrations of BSA, which reflect increased permeability of the mammary epithelial-endothelial barrier, were evident within 78 h of infection and were sustained from 90 h until the end of the study. Milk concentrations of several cytokines, including IFN-γ, IL-1β, IL-10, IL-12, tumor growth factor-α, and tumor necrosis factor-α, were elevated in response to infection over a period of several days, whereas increases in milk IL-8 were of a more limited duration. Complement activation, reflected by increased milk concentrations of complement factor 5a, was also observed over several days. Despite the indication by these observed changes that the cows mounted a prolonged inflammatory response to M. bovis intramammary infection, all quarters remained infected throughout the study with persistently high concentrations of this bacterium. Thus, a sustained inflammatory response is not sufficient to eradicate M. bovis from the mammary gland and may reflect the ongoing struggle of the host to clear this persistent pathogen.