The effect of mode of exposure to Beauveria bassiana on conidia acquisition and host mortality of Colorado potato beetle, Leptinotarsa decemlineata

The effects of the mode of exposure of second instar Colorado potato beetles to Beauveria bassiana on conidia acquisition and resulting mortality were investigated in laboratory studies. Larvae sprayed directly with a B, bassiana condial suspension, larvae exposed to B, bassiana-treated foliage, and larvae both sprayed and exposed to treated foliage experienced 76, 34, and 77% mortality, respectively. The total number of conidia and the proportion of germinating conidia were measured over time for four sections of the insect body: the ventral surface of the head (consisting mostly of ventral mouth parts), the ventral abdominal surface, the dorsal abdominal surface, and the legs. From observations at 24 and 36 h posttreatment, mean totals of 161.1 conidia per insect were found on sprayed larvae, 256.1 conidia on larvae exposed only to treated foliage, and 408.3 conidia on larvae both sprayed and exposed to treated foliage, On sprayed larvae, the majority of conidia were found on the dorsal abdominal surface, whereas conidia were predominantly found in the ventral abdominal surface and mouth parts on larvae exposed to treated foliage, Between 24 and 36 h postinoculation the percentage of conidia germinating on sprayed larvae increased slightly from 80 to 84%), On the treated foliage, the percentage of germinated conidia on larvae increased from 35% at 24 h to 50% at 36 h posttreatment, Conidia germination on sprayed larvae on treated foliage was 65% at 24 h and 75% at 36 h posttreatment, It is likely that the gradual acquisition of conidia derived from the continuous exposure to B. bassiana inoculum on the foliar surface was responsible for the increase in germination over time on larvae exposed to treated foliage, The density and germination of conidia were observed 0, 4, 8, 12, 16, 20, and 24 h after being sprayed with or dipped in conidia suspensions or exposing insects to contaminated foliage, Conidia germinated twice as fast on sprayed insects as with any other treatment within the first 12 h, This faster germination may be due to the pressure of the sprayer enhancing conidial lodging on cuticular surfaces. (C) 2001 Academic Press.

Apoptotic deletion of Th cells specific for the 19-kDa carboxyl-terminal fragment of merozoite surface protein 1 during malaria infection

Immunity induced by the 19-kDa fragment of merozoite surface protein 1 is dependent on CD4(+) Th cells. However, we found that adoptively transferred CFSE-labeled Th cells specific for an epitope on Plasmodium yoelii 19-kDa fragment of merozoite surface protein 1 (peptide (p)24), but not OVA-specific T cells, were deleted as a result of P. yoelii infection. As a result of infection, spleen cells recovered from infected p24-specific T cell-transfused mice demonstrated reduced response to specific Ag. A higher percentage of CFSE-labeled p24-specific T cells stained positive with annexin and anti-active caspase-3 in infected compared with uninfected mice, suggesting that apoptosis contributed to deletion of p24-specific T cells during infection. Apoptosis correlated with increased percentages of p24-specific T cells that stained positive for Fas from infected mice, suggesting that P. yoelii-induced apoptosis is, at least in part, mediated by Fas. However, bystander cells of other specificities also showed increased Fas expression during infection, suggesting that Fas expression alone is not sufficient for apoptosis. These data have implications for the development of immunity in the face of endemic parasite exposure.

Parasite infection rather than tactile stimulation is the proximate cause of cleaning behaviour in reef fish

Cleaning behavior is a popular example of non-kin cooperation. However, quantitative support for this is generally sparse and the alternative, that cleaners are parasitic: has also been proposed. Although the behaviour involves some of the most complex and highly developed interspecific communication signals known, the proximate causal factors for why clients Seek cleaners are controversial. However, this information is essential to understanding the evolution of cleaning. I tested whether clients seek cleaners in response to parasite infection or whether clients seek cleaners for tactile stimulation regardless of parasite load. Parasite loads oil client fish were manipulated and clients exposed to cleaner fish and control fish hehind glass. I found that parasitized client fish spent more time than unparasitized fish next to a cleaner fish. In addition; parasitized clients spent more rime next to cleaners than next to control fish whereas unparasitized fish were not attracted to cleaners. This study shows, I believe for the first time, which is somewhat surprising, that parasite infection alone causes clients to seek cleaning by cleaners and provides insight into how this behaviour evolved.

Bitter-sweet symphony: defining the role of dendritic cell gp120 receptors in HIV infection

Background: Dendritic cells (DC) are believed to be one of the first cell types infected during HIV transmission. Recently a single C-type lectin receptor (CLR), DC-SIGN, has been reported to be the predominant receptor on monocyte derived DC (MDDC) rather than CD4. The role of other CLRs in HIV binding and HIV binding by CLRs on other types of DC in vivo is largely unknown. Objectives and study design: Review HIV binding to DC populations, both in vitro and in vivo, in light of the immense interest of a recently re-identified CLR called DC-SIGN. Results and conclusions: From recent work, it is clear that immature MDDC have a complex pattern of HIV gp120 binding. In contrast to other cell types gp120 has the potential to bind to several receptors on DC including CD4 and several types of C type lectin receptor, not just exclusively DC-SIGN. Given the diverse types of DC in vivo future work will need to focus on defining the receptors for HIV binding to these different cell types. Mucosal transmission of HIV in vivo targets immature sessile DCs, including Langerhans cells which lack DC-SIGN. The role of CLRs and DC-SIGN in such transmission remains to be defined. (C) 2001 Elsevier Science B.V. All rights reserved.

Replication of bovine papillomavirus type 1 (BPV-1) DNA in Saccharomyces cerevisiae following infection with BPV-1 virions

Saccharomyces cerevisiae protoplasts exposed to bovine papillomavirus type 1 (BPV-1) virions demonstrated uptake of virions on electron microscopy. S. cerevisiae cells looked larger after exposure to BPV-1 virions, and cell wall regeneration was delayed. Southern blot hybridization of Hirt DNA from cells exposed to BPV-1 virions demonstrated BPV-1 DNA, which could be detected over 80 days of culture and at least 13 rounds of division. Two-dimensional gel analysis of Hirt DNA showed replicative intermediates, confirming that the BPV-1 genome was replicating within S. cerevisiae. Nicked circle, linear, and supercoiled BPV-1 DNA species were observed in Hirt DNA preparations from S. cerevisiae cells infected for over 50 days, and restriction digestion showed fragments hybridizing to BPV-1 in accord with the predicted restriction map for circular BPV-1 episomes. These data suggest that BPV-1 can infect S. cerevisiae and that BPV-1 episomes can replicate in the infected S. cerevisiae cells.

Analysis of the microbial community structure and function of a laboratory scale enhanced biological phosphorus removal reactor

A laboratory scale sequencing batch reactor (SBR) operating for enhanced biological phosphorus removal (EBPR) and fed with a mixture of volatile fatty acids (VFAs) showed stable and efficient EBPR capacity over a four-year-period. Phosphorus (P), poly-beta-hydroxyalkanoate (PHA) and glycogen cycling consistent with classical anaerobic/aerobic EBPR were demonstrated with the order of anaerobic VFA uptake being propionate, acetate then butyrate. The SBR was operated without pH control and 63.67+/-13.86 mg P l(-1) was released anaerobically. The P% of the sludge fluctuated between 6% and 10% over the operating period (average of 8.04+/-1.31%). Four main morphological types of floc-forming bacteria were observed in the sludge during one year of in-tensive microscopic observation. Two of them were mainly responsible for anaerobic/aerobic P and PHA transformations. Fluorescence in situ hybridization (FISH) and post-FISH chemical staining for intracellular polyphosphate and PHA were used to determine that 'Candidatus Accumulibacter phosphatis' was the most abundant polyphosphate accumulating organism (PAO), forming large clusters of coccobacilli (1.0-1.5 mum) and comprising 53% of the sludge bacteria. Also by these methods, large coccobacillus-shaped gammaproteobacteria (2.5-3.5 mum) from a recently described novel cluster were glycogen-accumulating organisms (GAOs) comprising 13% of the bacteria. Tetrad-forming organisms (TFOs) consistent with the 'G bacterium' morphotype were alphaproteobacteria , but not Amaricoccus spp., and comprised 25% of all bacteria. According to chemical staining, TFOs were occasionally able to store PHA anaerobically and utilize it aerobically.

Expression of the hepatitis C virus structural proteins in mammalian cells induces morphology similar to that in natural infection

Like many positive-strand RNA viruses, replication of the hepatitis C virus (HCV) is associated with cytoplasmic membrane rearrangements. However, it is unclear which HCV Proteins induce these ultrastructural features. This work examined the morphological changes induced by expression of the HCV structural proteins, core, E1 and E2, expressed from a Semliki Forest Virus (SFV) recombinant RNA replicon. Electron microscopy of cells expressing these proteins showed cytoplasmic vacuoles containing membranous and electron-dense material that were distinct from the type I cytoplasmic vacuoles induced during SFV replicon replication. Immunogold labelling showed that the core and E2 proteins localized to the external and internal membranes of these vacuoles. At times were also associated with some of the internal amorphous material. Dual immunogold labelling with antibodies raised against the core protein and against an endoplasmic reticulum (ER)-resident protein (protein disulphide isomerase) showed that the HCV-induced vacuoles were associated with ER-labelled membranes. This report has identified an association between the HCV core and E2 proteins with induced cytoplasmic vacuoles which are morphologically similar to those observed in HCV-infected liver tissue, suggesting that the HCV structural proteins may be responsible for the induction of these vacuoles during HCV replication in vivo.

A real-time PCR assay for the detection of Neisseria gonorrhoeae by LightCycler

The detection of Neisseria gonorrhoeae by the polymerase chain reaction (PCR) is now recognized as a sensitive and specific method of diagnosing infection by the organism. In this Study 152 urine specimens were examined for N. gonorrhoeae by a real-time PCR method using the LightCycler platform and results were compared to an in-house PCR assay using an ELISA-based detection method. N. gonorrhoeae DNA was detected in 29 (19%) specimens by LightCycler PCR (LC-PCR) and in 31 (20%) specimens by the in house PCR method. The LightCycler assay proved to be specific and 94% sensitive when compared to the in house PCR method. These features combined with the rapid turn-around time for results makes the LC-PCR particularly suitable for the detection of N. gonorrhoeae in a routine clinical laboratory. (C) 2002 Elsevier Science Inc. All rights reserved.

The modelling of froth zone recovery in batch and continuously operated laboratory flotation cells

This paper proposes an integrated methodology for modelling froth zone performance in batch and continuously operated laboratory flotation cells. The methodology is based on a semi-empirical approach which relates the overall flotation rate constant to the froth depth (FD) in the flotation cell; from this relationship, a froth zone recovery (R,) can be extracted. Froth zone recovery, in turn, may be related to the froth retention time (FRT), defined as the ratio of froth volume to the volumetric flow rate of concentrate from the cell. An expansion of this relationship to account for particles recovered both by true flotation and entrainment provides a simple model that may be used to predict the froth performance in continuous tests from the results of laboratory batch experiments. Crown Copyright (C) 2002 Published by Elsevier Science B.V. All rights reserved.

Glycogen-accumulating organisms in laboratory-scale and full scale wastewater treatment processes

Laboratory-scale sequencing batch reactors (SBRs) as models for wastewater treatment processes were used to identify glycogen-accumulating organisms (GAOs), which are thought to be responsible for the deterioration of enhanced biological phosphorus removal (EBPR). The SBRs (called Q and T), operated under alternating anaerobic-aerobic conditions typical for EBPR, generated mixed microbial communities (sludges) demonstrating the GAO phenotype. Intracellular glycogen and poly-beta-hydroxyalkanoate (PHA) transformations typical of efficient EBPR occurred but polyphosphate was not bioaccumulated and the sludges contained 1.8% P (sludge Q) and 1.5% P (sludge T). 16S rDNA clone libraries were prepared from DNA extracted from the Q and T sludges. Clone inserts were grouped into operational taxonomic units (OTUs) by restriction fragment length polymorphism banding profiles. OTU representatives were sequenced and phylogenetically analysed. The Q sludge library comprised four OTUs and all six determined sequences were 99.7% identical, forming a cluster in the gamma-Proteobacteria radiation. The T sludge library comprised eight OTUs and the majority of clones were Acidobacteria subphylum 4 (49% of the library) and candidate phylum OPU (39% of the library). One OTU (two clones, of which one was sequenced) was in the gamma-Proteobacteria radiation with 95% sequence identity to the Q sludge clones. Oligonucleotide probes (called GAOQ431 and GAOQ989) were designed from the gamma-Proteobacteria clone sequences for use in fluorescence in situ hybridization (FISH); 92 % of the Q sludge bacteria and 28 % of the T sludge bacteria bound these probes in FISH. FISH and post-FISH chemical staining for PHA were used to determine that bacteria from a novel gamma-Proteobacteria cluster were phenotypically GAOs in one laboratory-scale SBR and two fullscale wastewater treatment plants. It is suggested that the GAOs from the novel cluster in the gamma-Proteobacteria radiation be named 'Candidatus Competibacter phosphatis'.

Urine D-arabinitol/L-arabinitol ratio in diagnosing Candida infection in patients with haematological malignancy and HIV infection

Adult patients with hematologic malignancies along with HIV infected patients were prospectively studied to determine the performance of urine D-arabinitol/L-arabinitol (DA/LA) ratio in diagnosing invasive candidiasis. Ten evaluable febrile neutropenic patients had proven invasive candidiasis and elevated DA/LA ratios were found in 5. Invasive candidiasis with normal DA/LA ratios was most frequently due to Candida krusei infection. This Candida species is a non-producer of arabinitol. Only 4 of 81 febrile neutropenic patients given either antifungal prophylaxis or empiric antifungal treatment had elevated DA/LA ratios. Only 1 of 15 HIV positive patients with either oropharyngeal or esophageal candidiasis had elevated DA/LA ratios. Widespread use of fluconazole prophylaxis in bone marrow transplantation patients at the study hospital has led to an increased prevalence of C. krusei infection. This is the likely reason for the low sensitivity of the test in proven and suspected invasive Candida infections reported here. (C) 2002 Elsevier Science Inc. All rights reserved.