Ultrastructural alterations of the hepatopancreas in Porcellio scaber under stress

Cellular ultrastructure varies in accordance with physiological processes, also reflecting responses to environmental stress factors. Ultrastructural changes of the hepatopancreatic cells in the terrestrial isopod Porcellio scaber exposed to sublethal concentrations of zinc or cadmium in their food were identified by transmission electron microscopy. The exclusive structural characteristic of the hepatopancreas of animals exposed to metal-dosed food was grain-like electrondense deposits (EDD) observed in the intercellular spaces and in vesicles of B cells. In addition, hepatopancreatic cells of metal-exposed animals displayed non-specific, stress-indicating alterations such as cellular disintegration, the reduction of energetic reserves (lipid droplets, glycogen), electron dense cytoplasm, ultrastructural alterations of granular endoplasmic reticulum (GER), the Golgi complex and mitochondria.     

Behavioural response in paired food choice experiments with Oniscus asellus (Crustacea, Isopoda) as an indicator of different food quality

This paper describes a study of behavioural response in terrestrial isopod Oniscus asellus when offered two food pellets of different quality. One group had a choice of sterilised food and food pellets covered with mould. The other group had a choice of uncontaminated and cadmium-dosed food. During the behavioural test, the animals were monitored by a video camera and each visit to food pellets and time spent around it was counted. The results show that animals spent significantly less time near sterilised and cadmium-dosed food than with uncontaminated or mould-covered food. Discrimination between offered food pellets showed that avoidance behaviour can be used as an indicator of different food quality.     

The in vitro activity of vaginal Lactobacillus with probiotic properties against Candida

Lactobacilli, the predominant vaginal microorganisms in healthy premenopausal women, control other members of the vaginal microflora and thus protect against bacterial vaginosis and urinary tract infections. It has been claimed that some lactobacilli are also protective against Candida vaginitis. Little is known, however, about the mechanisms by which these lactobacilli can control vaginal populations of Candida and prevent vaginitis. To address this question, vaginal Lactobacillus strains with known antagonistic properties against bacteria were tested for their cell surface properties, adhesion to vaginal cell lines in vitro and antagonistic activities against Candida. A small proportion of the lactobacilli tested adhered strongly to cultured vaginal epithelial cells and inhibited growth of Candida albicans but not of C. pseudotropicalis. This anticandidal activity was in some Lactobacillus strains related to hydrogen peroxide (H2O2) production, but catalase treatment did not suppress this activity in other Lactobacillus strains, suggesting alternative mechanism(s). Moreover, tested vaginal Candida strains were resistant to relatively high concentrations of H2O2 that markedly exceeded those produced by even the most active Lactobacillus strains.     

Pseudomonas aeruginosa biofilm is a potent inducer of phagocyte hyperinflammation

Objective

Pseudomonas aeruginosa effectively facilitate resistance to phagocyte killing by biofilm formation. However, the cross talk between biofilm components and phagocytes is still unclear. We hypothesize that a biofilm provides a concentrated extracellular source of LPS, DNA and exopolysaccharides (EPS), which polarize neighbouring phagocytes into an adverse hyperinflammatory state of activation.

Methods

We measured the release of a panel of mediators produced in vitro by murine neutrophils and macrophages exposed to various biofilm components of P. aeruginosa cultures.

Results

We found that conditioned media from a high biofilm-producing strain of P. aeruginosa, PAR5, accumulated high concentrations of extracellular bacterial LPS, DNA and EPS by 72 h. These conditioned media induced phagocytes to release a hyperinflammatory pattern of mediators, with enhanced levels of TNF-α, IL-6, IL12p40, PGE₂ and NO. Moreover, the phagocytes also upregulated COX-2 and iNOS with no influence on the expression of arginase-1.

Conclusions

Phagocytes exposed to biofilm microenvironment, called by us biofilm-associated neutrophils/macrophages (BANs/BAMs), display secretory properties similar to that of N1/M1-type phagocytes. These results suggest that in vivo high concentrations of LPS and DNA, trapped in biofilm by EPS, might convert infiltrating phagocytes into cells responsible for tissue injury without direct contact with bacteria and phagocytosis.

     

Microbiological investigation of a hospital outbreak of invasive group A streptococcal disease in Krakow,Poland

The present study reports the epidemiological investigations undertaken in one of Krakow’s city hospitals regarding the source of infection and the routes of transmission of a group A streptococcus (Streptococcus pyogenes), using fluorescent in situ hybridization as a rapid method for detecting S. pyogenes carriage in the medical personnel involved. Four patients from the gynaecology department and two patients from the surgery department presented with clinical signs of infection. Characteristics of the S. pyogenes strains isolated from patients and from one medical staff member, including the emm gene and superantigens encoding genes, are described. All patients (four confirmed and two probable cases) survived; the operating theatre aid was identified as an S. pyogenes carrier and the source of the infections.     

Mucosal bacterial microflora and mucus layer thickness in adolescents with inflammatory bowel disease

AIM: To assess the mucosa-associated bacterial microflora and mucus layer in adolescents with inflammatory bowel disease (IBD).METHODS: Sixty-one adolescents (mean age 15 years, SD ± 4.13) were included in the study. Intestinal biopsies from inflamed and non-inflamed mucosa of IBD patients and from controls with functional abdominal pain were cultured under aerobic and anaerobic conditions. The number of microbes belonging to the same group was calculated per weight of collected tissue. The mucus thickness in frozen samples was measured under a fluorescent microscope.RESULTS: The ratios of different bacterial groups in inflamed and non-inflamed mucosa of IBD patients and controls were specific for particular diseases. Streptococcus spp. were predominant in the inflamed mucosa of Crohn’s disease (CD) patients (80% of all bacteria), and Lactobacillus spp. were predominant in ulcerative colitis patients (90%). The differences were statistically significant (P = 0.01-0.001). Lower number of bifidobacteria was observed in the whole IBD group. A relation was also found between clinical and endoscopic severity and decreased numbers of Lactobacillus and, to a lesser extent, of Streptococcus in biopsies from CD patients. The mucus layer in the inflamed sites was significantly thinner as compared to controls (P = 0.0033) and to non-inflamed areas in IBD patients (P = 0.031).CONCLUSION: The significantly thinner mucosa of IBD patients showed a predominance of some aerobes specific for particular diseases, their numbers decreased in relation to higher clinical and endoscopic activity of the disease.     

Isopod gut microflora parameters as endpoints in toxicity studies

Terrestrial isopods Porcellio scaber (Crustacea) were fed for five weeks on food contaminated by 250, 500, or 1,000 microg of Cd/g or for 10 d on diets with 50 or 250 microg Cd/g food. In both experiments, fecal production rate and colony forming units (CFUs) in the guts were determined. In addition, at the end of 10 d, each distinct colony morphotype obtained in gut samples was purified and characterized. Isolates were separated into 25 groups based on morphological and biochemical characteristics. These bacterial groups were used as units for calculating Shannon equitability indices (J) for each gut. The relative frequencies of the 25 bacterial units were determined in both cadmium groups (50 or 250 microg Cd/g food) and in the control. Cadmium-induced perturbations observed in the gut microbial communities were (1) increased number of morphologically distinct bacterial isolates in the group fed low-cadmium-dosed food (50 microg Cd/g) and reduced number of morphologically distinct bacterial isolates in the group fed high-cadmium-dosed food (250 microg Cd/g) compared with the control, (2) increased or decreased relative frequencies of almost all 25 bacterial units provoked by cadmium-contaminated food, (3) time-dependent increased numbers of gut CFUs in cadmium-fed animals (dose dependence was not observed), and (4) significant changes in community structure described by Shannon equitability indices at lower levels of food contamination (50 microg Cd/g) only. Gut microflora parameters are proposed as additional endpoints in the standardized single-species toxicity test with the terrestrial isopod P. scaber as a means of increasing the ecological relevance of the results.