The bovine foot skin microbiota is associated with host genotype and the development of infectious digital dermatitis lesions

BACKGROUND

Bovine Digital Dermatitis (BDD) is a prevalent infectious disease, causing painful foot skin lesions and lameness in cattle. We describe herein the bovine foot skin microbiota and its associations with BDD using 16S rRNA gene amplicon and shotgun metagenomic sequencing on samples from 259 dairy cows from three UK dairy farms.

RESULTS

We show evidence of dysbiosis, and differences in taxonomy and functional profiles in the bovine foot skin microbiome of clinically healthy animals that subsequently develop BDD lesions, compared to those that do not. Our results suggest that taxonomical and functional differences together with alterations in ecological interactions between bacteria in the normal foot skin microbiome may predispose an animal to develop BDD lesions. Using genome-wide association and regional heritability mapping approaches, we provide first evidence for interactions between host genotype and certain members of the foot skin microbiota. We show the existence of significant genetic variation in the relative abundance of Treponema spp. and Peptoclostridium spp. and identify regions in the bovine genome that explain a significant proportion of this variation.

CONCLUSIONS

Collectively this work shows early changes in taxonomic and functional profiles of the bovine foot-skin microbiota in clinically healthy animals which are associated with subsequent development of BDD and could be relevant to prevention of disease. The description of host genetic control of members of the foot skin microbiota, combined with the association of the latter with BDD development offer new insights into a complex relationship that can be exploited in selective breeding programmes. Video Abstract.

Next generation sequencing of transcribed genes in ruminant γδ T cell populations

Bovine γδ T cells are distinguished by expression of WC1, hybrid pattern recognition receptors and co-receptors to the T cell receptor (TCR), or their absence. WC1 molecules bind pathogens and the ability of γδ T cells to respond to pathogens largely correlates with their expression of particular WC1 genes. Following activation, the TCR and WC1 molecules co-localize and knocking down WC1 abrogates the ability of WC1-expressing γδ T cells to respond to antigen. It is known that these two major populations, WC1⁺ and WC1^-, differ in their TCR gene expression and previous studies showed other differences using semi-quantitative RT-PCR and serial analysis of gene expression. Differences in genes expressed would influence the functional outcome when WC1⁺ vs. WC1^- γδ T cells respond to pathogens. To identify unique aspects of their transcriptome, here we performed RNA-Seq of flow cytometrically sorted bovine WC1⁺ and WC1^- γδ T cells and compared them to all mononuclear cells in blood. The greatest differences in gene expression were found between γδ T cells and other mononuclear cells and included those involved in lymphocyte activation and effector processes. Only minor differences occurred between ex vivo WC1⁺ vs. WC1^- γδ T cells with those gene products being involved in cell adhesion and chemotaxis. After culturing cells from primed animals with Leptospira antigens major difference in the transcriptome was evident, with over 600 genes significantly differentially expressed including those focused on cytokine signaling. Unexpectedly, antigen-responding and non-responding populations of WC1⁺ γδ T cells had few differences in their transcriptomes outside of cytotoxic factors although they had more WC1-1, WC1-2 and WC1-13 transcripts. Through differential gene expression we were able to define properties of ex vivo and stimulated WC1⁺ cells which will be useful in understanding their functional biology.

Transcriptional programming and gene regulation in WC1+ γδ T cell subpopulations

γδ T cells represent a high proportion of lymphocytes in the blood of ruminants with the majority expressing lineage-specific glycoproteins from the WC1 family. WC1 receptors are coded for by a multigenic array whose genes have variegated but stable expression among cells in the γδ T cell population. WC1 molecules function as hybrid pattern recognition receptors as well as co-receptors for the TCR and are required for responses by the cells. Because of the variegated gene expression, WC1⁺ γδ T cells can be divided into two main populations known as WC1.1⁺ and WC1.2⁺ based on monoclonal antibody reactivity with the expressed WC1 molecules. These subpopulations differ in their ability to respond to specific pathogens. Here, we showed these populations are established in the thymus and that WC1.1⁺ and WC1.2⁺ subpopulations have transcriptional programming that is consistent with stratification towards Tγδ1 or Tγδ17. WC1.1⁺ cells exhibited the Tγδ1 phenotype with greater transcription of Tbx21 and production of more IFNγ while the WC1.2⁺ subpopulation tended towards Tγδ17 programming producing higher levels of IL-17 and had greater transcription of Rorc. However, when activated both WC1⁺ subpopulations' cells transcribed Tbx21 and secreted IFNγ and IL-17 reflecting the complexity of these subpopulations defined by WC1 gene expression. The gene networks involved in development of these two subpopulations including expression of their archetypal genes wc1-3 (WC1.1⁺) and wc1-4 (WC1.2⁺) were unknown but we report that SOX-13, a γδ T cell fate-determining transcription factor, has differential occupancy on these WC1 gene loci and suggest a model for development of these subpopulations.

Subpopulations of swine γδ T cells defined by TCRγ and WC1 gene expression

γδ T cells constitute a major portion of lymphocytes in the blood of both ruminants and swine. Subpopulations of swine γδ T cells have been distinguished by CD2 and CD8α expression. However, it was not clear if they have distinct expression profiles of their T-cell receptor (TCR) or WC1 genes. Identifying receptor expression will contribute to understanding the functional differences between these subpopulations and their contributions to immune protection. Here, we annotated three genomic assemblies of the swine TCRγ gene locus finding four gene cassettes containing C, J and V genes, although some haplotypes carried a null TRGC gene (TRGC4). Genes in the TRGC1 cassette were homologs of bovine TRGC5 cassette while the others were not homologous to bovine genes. Here we evaluated three principal populations of γδ T cells (CD2⁺/SWC5^-, CD2^-/SWC5⁺, and CD2^-/SWC5^-). Both CD2^- subpopulations transcribed WC1 co-receptor genes, albeit with different patterns of gene expression but CD2⁺ cells did not. All subpopulations transcribed TCR genes from all four cassettes, although there were differences in expression levels. Finally, the CD2⁺ and CD2^- γδ T-cell populations differed in their representation in various organs and tissues, presumably at least partially reflective of different ligand specificities for their receptors.

Gamma Delta TCR and the WC1 Co-Receptor Interactions in Response to Leptospira Using Imaging Flow Cytometry and STORM

The WC1 cell surface family of molecules function as hybrid gamma delta (γδ) TCR co-receptors, augmenting cellular responses when cross-linked with the TCR, and as pattern recognition receptors, binding pathogens. It is known that following activation, key tyrosines are phosphorylated in the intracytoplasmic domains of WC1 molecules and that the cells fail to respond when WC1 is knocked down or, as shown here, when physically separated from the TCR. Based on these results we hypothesized that the colocalization of WC1 and TCR will occur following cellular activation thereby allowing signaling to ensue. We evaluated the spatio-temporal dynamics of their interaction using imaging flow cytometry and stochastic optical reconstruction microscopy. We found that in quiescent γδ T cells both WC1 and TCR existed in separate and spatially stable protein domains (protein islands) but after activation using Leptospira, our model system, that they concatenated. The association between WC1 and TCR was close enough for fluorescence resonance energy transfer. Prior to concatenating with the WC1 co-receptor, γδ T cells had clustering of TCR-CD3 complexes and exclusion of CD45. γδ T cells may individually express more than one variant of the WC1 family of molecules and we found that individual WC1 variants are clustered in separate protein islands in quiescent cells. However, the islands containing different variants merged following cell activation and before merging with the TCR islands. While WC1 was previously shown to bind Leptospira in solution, here we showed that Leptospira bound WC1 proteins on the surface of γδ T cells and that this could be blocked by anti-WC1 antibodies. In conclusion, γδ TCR, WC1 and Leptospira interact directly on the γδ T cell surface, further supporting the role of WC1 in γδ T cell pathogen recognition and cellular activation.

Goat γδ T cell subpopulations defined by WC1 expression, responses to pathogens and cytokine production

The major functions of γδ T cells in mammals overlap with those of αβ T cells but differ in that γδ T cells are rapid responders and see different types of antigens. While γδ T cells have been shown to be a major population of circulating lymphocytes in artiodactyl species such as cattle, sheep, and pigs, less is known about these cells in goats, an important agricultural species. We have recently shown that WC1, a γδ T cell-specific family of hybrid pattern recognition receptors/co-receptors, is a multigenic family in goats expanded beyond what occurs in cattle. This study was conducted to address some of the limitations of previous studies in determining the proportions of γδ T cells, WC1⁺ γδ T cells as well as the WC1.1⁺ and WC1.2⁺ subpopulations in blood and to evaluate their responses to various pathogens. Previously, the proportion of caprine γδ T cells was determined using a monoclonal antibody (mAb) 86D that we show here does not react with all γδ T cells thereby underestimating their contribution to the lymphocyte population. Using a mAb reactive with the TCRδ constant region we found the proportion of γδ T cells in blood was not significantly less than that of either CD4 or CD8 T cells and did not decrease with age after 6 months. γδ T cells that expressed WC1 ranged from ~20 to 85% of the total γδ T cells. Less than half of those were classified as WC1.1⁺ or WC1.2⁺ by mAb staining thus indicating a third major WC1⁺ population. We found that naïve γδ T cells proliferated in cultures of PBMC stimulated with antigens of Leptospira or Mycobacterium avium paratuberculosis (MAP) more than they did in control medium cultures or in those stimulated with M. bovis BCG antigens and that the responding γδ T cells included both WC1⁺ and WC1^- cells. In ex vivo PMA/ionomycin-stimulated cultures of WC1^- γδ T cells but not WC1⁺ cells produced both IL-17 and IFNγ. In longterm cultures with Leptospira or MAP both WC1^- and WC1⁺ cells proliferated but only WC1^- γδ T cells produced IL-17. In conclusion, goats have a substantial number of WC1^- and WC1⁺ γδ T cells in PBMC that do not decrease with animal age after 6 months; both populations respond to bacterial antigens as naïve cells but in these cultures only the WC1^- γδ cells produc IL-17 and IFNγ .

Gene characterization and expression of the γδ T cell co-receptor WC1 in sheep

Sheep are known to express the hybrid co-receptor/pattern recognition receptor WC1 on their γδ T cells but details of the ovine WC1 multigenic array and gene expression were unknown. Annotation of the sheep genome assembly (Oar_rambouillet_v1.0) yielded 15 complete and 42 partial WC1 genes predicted to code for six different protein structures. RT-PCR amplification of the most distal scavenger receptor cysteine rich (SRCR) domain known as a1, which serves as the gene signature, from genomic and cDNA templates verified the majority of annotated genes. As for cattle and goats, sheep a1 domain sequences included WC1.1 and WC1.2 types. A unique ovine gene, WC1-16, had multiple SRCR a-pattern domains in tandem similar to one found in goats. Intracytoplasmic domains of WC1 transcripts had splice variants that may affect signal transduction. The larger number of WC1 genes in sheep and differences in structures and splice variants relative to cattle could have implications in expression patterns and engagement of γδ T cells by pathogens or vaccine constructs.

Characterization of the domestic goat γδ T cell receptor gene loci and gene usage

Goats and cattle diverged 30 million years ago but retain similarities in immune system genes. Here, the caprine T cell receptor (TCR) gene loci and transcription of its genes were examined and compared to cattle. We annotated the TCR loci using an improved genome assembly (ARS1) of a highly homozygous San Clemente goat. This assembly has already proven useful for describing other immune system genes including antibody and leucocyte receptors. Both the TCRγ (TRG) and TCRδ (TRD) loci were similarly organized in goats as in cattle and the gene sequences were highly conserved. However, the number of genes varied slightly as a result of duplications and differences occurred in mutations resulting in pseudogenes. WC1⁺ γδ T cells in cattle have been shown to use TCRγ genes from only one of the six available cassettes. The structure of that Cγ gene product is unique and may be necessary to interact with WC1 for signal transduction following antigen ligation. Using RT-PCR and PacBio sequencing, we observed the same restriction for goat WC1⁺ γδ T cells. In contrast, caprine WC1⁺ and WC1^- γδ T cell populations had a diverse TCRδ gene usage although the propensity for particular gene usage differed between the two cell populations. Noncanonical recombination signal sequences (RSS) largely correlated with restricted expression of TCRγ and δ genes. Finally, caprine γδ T cells were found to incorporate multiple TRD diversity gene sequences in a single transcript, an unusual feature among mammals but also previously observed in cattle.

γδ T cells in livestock: Responses to pathogens and vaccine potential

The immediate objective of our research is to understand the molecular mechanisms underlying activation and potentiation of the protective functional response of WC1⁺ γδ T cells to pathogens afflicting livestock species. The long-term goal is to incorporate stimulation of these cells into the next generation of vaccine constructs. γδ T cells have roles in the immune response to many infectious diseases including viral, bacterial, protozoan and worm infections, and their functional responses overlap with those of canonical αβ T cells, for example they produce cytokines including interferon-γ and IL-17. Stimulation of non-conventional lymphocytes including γδ T cells and αβ natural killer T (NKT) cells has been shown to contribute to protective immunity in mammals, bridging the gap between the innate and adaptive immune responses. Because of their innate-like early response, understanding how to engage γδ T-cell responses has the potential to optimize strategies of those that aim to induce pro-inflammatory responses as discussed here.

Annotation of the WC1 gene family in Sus scrofa and evaluation of individual SRCR domain affinity for Mycobacterium bovis and Leptospira spp

γδ T cells respond to a variety of proteins and non-proteinaceous molecules independent of MHC presentation, making them less susceptible to immune evasion and thus; an attractive target for next-generation vaccines. Unfortunately, definitive methods to prime these cells remain elusive. WC1, a member of the group B Scavenger Receptor Cysteine-Rich (SRCR) superfamily, is expressed exclusively on the γδ T cells of swine and ruminants and functions as hybrid co-receptor and pattern recognition receptor for the γδ TCR. It is known that there are thirteen unique WC1 genes expressed in cattle, each containing up to eleven extracellular SRCR domains. Bovine WC1+ γδ T cells share restriction in their TCR gene usage, yet respond to different pathogens based on which WC1 molecule(s) they express. This can be attributed to the ability of the expressed WC1 molecule to directly bind whole pathogens via its SRCR domains. Because WC1 is expressed as a multigene array, we hypothesize that each WC1 gene has co-evolved with a different set of pathogens, and may be exploited to generate a protective immune response from WC1+ γδ T-cells. We sought to identify and characterize WC1 genes expressed in swine, and evaluate their pathogen binding potential. We have obtained cDNA evidence for ten swine WC1 genes, containing up to six extracellular SRCR domains. Through annotation with MAKER, we have confirmed the presence of seven of these genes in the current assembly, Sus scrofa 11.1, and identified four unique exon-intron gene structures. We have shown that SRCR domains from multiple WC1 genes differentially bind Leptospira spp, and Mycobacterium bovis BCG Danish and Pasteur strains.

Bovine T cell receptors and γδ WC1 co-receptor transcriptome analysis during the first month of life

Here we evaluated neonatal transcription of α, β, γ and δ TCR and the γδ T cell co-receptor family WC1 in peripheral blood mononuclear cells. A previous report showed a rapid and global shift in transcription of immunoglobulin genes in neonatal calves during the first month after birth but this was not found here for the T cell genes. Transcription frequency of genes within TRAV subgroups correlated with the number of members, indicating a stochastic choice. In contrast, of the approximately 60 TRDV genes those in two of eleven TRDV1 clades and TRDVb3 were transcribed significantly more than the others while those in only one TRBV subgroup were. Transcription of genes in the TRGV5-containing cassette predominated among TRGV genes as a result of their exclusive usage by the WC1⁺ γδ T cells with a preference for transcription of two of four TRGV genes in that cassette. Finally, we report no large differences in transcription frequencies among the 13 WC1 genes.

Classification the WC1 gene family in Sus scrofa and evaluation of individual SRCR domain affinity for Mycobacterium bovis and Leptospira spp

Unlike αβ T cells, γδ T cells respond to a variety non-proteinaceous molecules independent of MHC presentation. γδ T cells are less susceptible to immune evasion, making them an attractive target for next generation vaccines, however, little is known about the best way to prime them. WC1, a member of the group B Scavenger Receptor Cysteine Rich (SRCR) superfamily, is expressed exclusively on γδ T cells in swine and ruminants. Previous work in our lab has determined that there are 13 genes encoding for WC1 in cattle. We have also shown that WC1 functions as hybrid co-receptor and pattern recognition receptor for the γδ TCR. WC1+ γδ T cells share a restriction in TCR gene usage, yet respond to different pathogens based on which WC1 molecule(s) they express. This can be attributed to the ability of the expressed WC1 molecule to recognize and directly bind whole pathogens via its SRCR domains. Because WC1 is expressed as a multigene array, we hypothesize that each WC1 gene has co-evolved with a different set of pathogens. Swine belong to the same order as cattle, Artiodactyl, and are susceptible to infection with many of the same pathogens. The current swine assembly contains two predicted WC1 proteins, neither of which had been confirmed with cDNA evidence. Prior to this study only one full-length cDNA transcript had been successfully amplified. Using 5′/3′ RACE PCR and RT-PCR, we have obtained full length cDNA transcripts for seven WC1 genes with the SRCR domain patterns of a1-[b-c-d-e-d′] or d1-[b-c-d-e-d′]. Through bacterial pull-down assays, we have shown that multiple SRCR domains from different swine WC1 genes bind to vaccine strain Leptospira spp, and freshly grown Pasteur and Danish strains of Mycobacterium bovis.

Hemodialysis Clinic Social Networks, Sex Differences, and Renal Transplantation

This study describes patient social networks within a new hemodialysis clinic and models the association between social network participation and kidney transplantation. Survey and observational data collected between August 2012 and February 2015 were used to observe the formation of a social network of 46 hemodialysis patients in a newly opened clinic. Thirty-two (70%) patients formed a social network, discussing health (59%) and transplantation (44%) with other patients. While transplant-eligible women participated in the network less often than men (56% vs. 90%, p = 0.02), women who participated discussed their health more often than men (90% vs. 45.5%, p = 0.02). Patients in the social network completed a median of two steps toward transplantation compared with a median of 0 for socially isolated patients (p = 0.003). Patients also completed more steps if network members were closely connected (β = 2.23, 95% confidence interval [CI] 0.16-4.29, p = 0.03) and if network members themselves completed more steps (β = 2.84, 95% CI 0.11-5.57, p = 0.04). The hemodialysis clinic patient social network had a net positive effect on completion of transplant steps, and patients who interacted with each other completed a similar number of steps.

Interaction of γδ TCR with the WC1 hybrid co-receptor/pathogen recognition receptor in cattle

Ruminants have a larger proportion of γδ T lymphocytes in blood compared to mice and humans. These lymphocytes are first responders to pathogens such as Leptospira and Mycobacterium. Bovine γδ T cells that respond to these pathogens express members of a unique γδ T-cell specific molecular family WC1 that are hybrid pattern recognition receptors and signaling co-receptors. Only γδ T cells that express WC1 molecules that bind to the pathogens selectively respond by proliferation and cytokine production. WC1 molecules have also been shown to augment signaling when co-crosslinked with the TCR but cannot signal on their own. Silencing WC1 through shRNA results in inhibition of the response to leptospira. Together these data indicate that WC1 is crucial for activation of the cells and we wished to further understand how the TCR interacts with WC1. The TCR is transcribed from a recombination of variable, joining, and diversity genes resulting in hundreds to millions of different possible sequences while the WC1 family has only 137 different pathogen-binding SRCR domains coded for by 13 genes. Yet only γδ T cells that express particular WC1 family members respond to leptospira suggesting it has primacy. We hypothesize that WC1 molecules co-localize with the TCR following binding of the pathogen. To test this hypothesis we used Imaging flow cytometry. Using FRET analysis we are able to determine that not only are the TCR and WC1 co-localized in the synapse following activation but they also are interacting closely within 9nm of each other. To evaluate the role of the TCR in dictating specificity of the response we are using next generation sequencing of transcripts coding for the TCR gamma and delta chains in leptospira-responsive cells.

Lack of listing status awareness: results of a single-center survey of hemodialysis patients

This study surveyed hemodialysis patients in an urban transplant center serving a predominantly African American population to identify existing and potential barriers to transplantation. The survey used the Dialysis Patient Transplant Questionnaire (DPTQ) to collect self-reported data including interest in a deceased donor kidney transplant and self-reported listing status. We compared patients' survey data to their UNOS listing and computerized medical record at time of interview. Among the 116 patients surveyed, 83 (71.6%) reported interest in a deceased donor kidney transplant. Eighteen (52.9%) of the 34 patients undergoing pretransplantation workup were unaware of their true listing status, and 88.9% of these patients mistakenly believed they were wait listed. All of the patients who mistakenly thought they were listed were undergoing workup. Finding that a significant number of hemodialysis patients who want a deceased donor kidney transplant mistakenly think they are listed when they are not is a documentable deficiency in communication and a potential barrier to transplantation. The finding highlights a correctable problem in communication and work flow that could help to improve transplant center effectiveness. It also reveals that self-reported waiting list status significantly overestimated true waiting list status for our patients at time of interview.

Small intestinal volvulus in a free-ranging female dugong (Dugong dugon)

An adult female dugong (Dugong dugon) was found dead and floating in Moreton Bay, Queensland, Australia. This animal was found to have a 360° mesenteric volvulus with infarction of the associated segment of small intestine, and fibrinous peritonitis. Mortality was attributed to the volvulus and its sequelae. The cause was not apparent on gross or histological examination.

Characteristics of children enrolled in treatment trials for NF1-related plexiform neurofibromas

OBJECTIVE

To describe the characteristics of children enrolled in treatment trials for neurofibromatosis type 1 (NF1)-related plexiform neurofibroma (PN), PN tumor burden, PN-related complications, and treatment outcomes and to highlight the differences between characteristics of children with NF1 vs children with cancers entered on early phase drug trials.

METHODS

Pre-enrollment characteristics and complications of PN were retrospectively analyzed in a cohort of 59 children with NF1-related PN treated on 1 of 7 clinical trials at the NIH between 1996 and 2007. Outcome was analyzed in a subset of 19 patients enrolled in phase I trials. Comparisons to children with cancer were made from a similar analysis performed recently.

RESULTS

The median age at enrollment was 8 years. The median PN volume was 555 mL. Most patients had no prior chemotherapy or radiation, but nearly half had previous surgery for PN. PN-associated complications and NF1 manifestations were common, including pain (53%), other tumors (18%), and hypertension (8%). Investigational drug therapy was well tolerated. A median of 10 treatment cycles was administered. Patients with NF1-related PN were younger, had better performance score, had less prior therapy, and remained on study longer than cancer patients.

CONCLUSIONS

Children with NF1-related plexiform neurofibroma (PN) enrolled in clinical trials had large tumors with substantial morbidity. Clinical trials in these children provide information about drug tolerance, cumulative toxicity, and pharmacokinetics in a younger population than early phase pediatric cancer trials. This report may aid in the evaluation of the applicability of traditional pediatric cancer trial designs and endpoints for NF1-related PN.

Interspecific competition between the nematode-trapping fungus,Duddingtonia flagrans, and selected microorganisms and the effect of spore concentration on the efficacy of nematode trapping

The fungus,Duddingtonia flagrans, is able to trap and kill free-living nematode larvae of the cattle parasiteCooperia oncophorawhen chlamydospores are mixed in cattle faeces. Isolates ofBacillus subtilis(two isolates),Pseudomonasspp. (three isolates) and single isolates of the fungal generaAlternaria,Cladosporium,Fusarium,TrichodermaandVerticilliumwere isolated from cattle faeces and shown to reduceD. flagransgrowth on agar plates. When these isolates were added to cattle faeces containingD. flagransand nematode larvae ofC. oncophora, developing from eggs, none of the isolates reduced nematode mortality attributed toD. flagrans. Similarly, the coprophilic fungusPilobolus kleinii, which cannot be cultivated on agar, also failed to suppress the ability ofD. flagransto trap and kill developing larvae ofC. oncophora. Increasing chlamydospore doses ofD. flagransin faecal cultures resulted in higher nematode mortality. Thus, no evidence of interspecific or intraspecific competition was observed. The consequences of these findings are discussed.

Limits on gravitational-wave emission from selected pulsars using LIGO data

We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsars by a coherent multidetector analysis of the data collected during the second science run of the LIGO interferometric detectors. These are the first direct upper limits for 26 of the 28 pulsars. We use coordinated radio observations for the first time to build radio-guided phase templates for the expected gravitational-wave signals. The unprecedented sensitivity of the detectors allows us to set strain upper limits as low as a few times 10(-24). These strain limits translate into limits on the equatorial ellipticities of the pulsars, which are smaller than 10(-5) for the four closest pulsars.

Efficiency of feeding Duddingtonia flagrans chlamydospores to grazing ewes on reducing availability of parasitic nematode larvae on pasture

Gastrointestinal nematodes are of concern in sheep production because of production and economic losses. Control of these nematodes is primarily based on the use of anthelmintic treatment and pasture management. The almost exclusive use of anthelmintic treatment has resulted in development of anthelmintic resistance which has led to the need for other parasite control options to be explored. The blood sucking abomasal parasitic nematode Haemonchus contortus causes severe losses in small ruminant production in the warm, humid sub-tropic and tropics. This study evaluated the effectiveness of a nematode trapping fungus, Duddingtonia flagrans, in reducing availability of parasitic nematode larvae, specifically H. contortus, on pasture. Chlamydospores of D. flagrans were mixed with a supplement feed which was fed daily to a group of crossbred ewes for the duration of the summer grazing season. A control group was fed the same supplement feed without chlamydospores. A reduction in infective larval numbers was observed in fecal cultures of the fungus-fed group. Herbage samples from the pasture grazed by the fungus-fed group also showed a reduction in infective larvae. There were no significant (P > 0.05) differences in overall fecal egg count, packed cell volume or animal weight between fungus-fed and control groups. Tracer animals were placed on the study pastures at the end of the study to assess pasture infectivity. Although tracer animals were only two per group, those that grazed with the fungus-fed group had substantially reduced (96.8%) nematode burdens as compared to those from the control group pasture. Results demonstrated that the fungus did have activity against nematode larvae in the feces which reduced pasture infectivity and subsequently nematode burdens in tracer animals. This study showed that D. flagrans, fed daily to grazing ewes, was an effective biological control agent in reducing a predominantly H. contortus larval population on pasture.

Evaluation of Duddingtonia flagrans in reducing infective larvae of Haemonchus contortus in feces of sheep

Consequences of nematode infections due to Haemonchus contortus are a serious constraint for the sheep industry worldwide. Development of anthelmintic resistance and increasing concern about the impact of anthelmintic use dictate the need of alternative control. Such an alternative is using the nematode trapping fungus Duddingtonia flagrans to reduce infective larvae levels on pasture. Two trials were conducted to determine the effect of D. flagrans in reducing infective larvae (predominantly H. contortus) in feces. The first trial determined the dose effect of D. flagrans in reducing infective larvae in feces. Eighteen ewes were dewormed to remove existing infections and randomly assigned to six treatment groups: 5 x 10(4), 1 x 10(5), 2.5 x 10(5), 5 x 10(5), 1 x 10(6) or no (control) spores of D. flagrans per kg of body weight mixed in their feed for 7 days. Fecal samples were collected daily from these and from infected donor ewes. Feces from individual-treated ewes were mixed with equal amounts of donor ewe feces, theoretically approximating oral dose spore concentrations of 2.5 x 10(4), 5 x 10(4), 1.25 x 10(5), 2.5 x 10(5), 5 x 10(5) and no spores, and were cultured. Across dosages and during the 7 days of fungus feeding, percent reduction of infective larvae ranged from 76.6 to 100.0%. The second trial determined the effect of D. flagrans at the dose of 10(5) spores per kg body weight on reducing infective larvae in feces from naturally infected lambs. Twenty lambs were randomly assigned to either treatment or control groups based on fecal egg count. Treatment lambs were fed spores mixed in feed for 7 days. Feces were collected daily and cultured. During the 7 days of fungus feeding, the percent reduction of infective larvae ranged from 82.8 to 99.7%. Results of these trials demonstrated that the nematode trapping fungus D. flagrans was highly effective in reducing infective larvae in sheep feces and should be considered as a biological control agent for integrated nematode control programs.

Dual action of n-alcohols on neuronal nicotinic acetylcholine receptors

Alcohol is known to modulate the activity of a variety of neuroreceptors and ion channels. Recently, neuronal nicotinic acetylcholine receptors (nnAChRs) have become a specific focus of study because not only are they potently modulated by alcohol but also they regulate the release of various transmitters, including gamma-aminobutyric acid (GABA) and dopamine, which play an important role in the behavioral effects of ethanol. Whereas the potency of normal alcohols (n-alcohols) to potentiate GABA(A) receptors and to inhibit N-methyl-D-aspartate receptors increases with carbon chain length, we have found that n-alcohols, depending on the carbon chain length, exert a dual action, potentiation and inhibition, on nnAChRs in primary cultured rat cortical neurons. The mechanism of dual action of n-alcohols on nnAChRs was further analyzed using human embryonic kidney cells expressing the alpha 4 beta 2 subunits. Shorter chain alcohols from methanol to n-propanol potentiated acetylcholine (ACh)-induced currents, whereas longer chain alcohols from n-pentanol to n-dodecanol inhibited the currents. n-Butanol either potentiated or inhibited the currents depending on the concentrations of ACh and butanol. The parameters for both potentiation (log EC(200)) and inhibition (log IC(50)) were linearly related to carbon number, albeit with different slopes. The slope for potentiation was -0.299, indicating a change in free energy change (Delta Delta G) of 405 cal/mol/methylene group, whereas the slope for inhibition was -0.584, indicating a Delta Delta G of 792 cal/mol. These results suggest that potentiating and inhibitory actions are exerted through two different binding sites. Ethanol decreased the potency of n-octanol to inhibit ACh currents, possibly resulting from an allosteric mechanism.

Differential alterations in nicotinic receptor alpha6 and beta3 subunit messenger RNAs in monkey substantia nigra after nigrostriatal degeneration

Our previous studies showed that alpha4, alpha6, alpha7, beta2, beta3 and beta4 nicotinic acetylcholine receptor messenger RNAs are present in monkey substantia nigra, with a particularly intense and localized labelling of the alpha6 and beta3 subunit messenger RNAs to this brain region. Because loss of nigrostriatal neurons is a central feature of Parkinson's disease and evidence suggests that nicotinic agonists potentiate antiparkinsonian effects of L-dopa, experiments were done to determine whether nicotinic receptor subunit messenger RNAs and binding sites were altered in the basal ganglia after nigrostriatal degeneration. Squirrel monkeys (Saimiri sciureus) were rendered parkinsonian by systemic injection of the selective dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3, 6-tetrahydropyridine. Behavioral studies showed that this treatment decreased baseline motor activity to 36+/-11% of control. One month after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine administration, caudate and putamen dopamine levels were reduced to 51+/-15% and 43+/-6% of control, respectively, while the number of tyrosine hydroxylase-positive neurons in the substantia nigra was 75+/-6% of control. Despite the reduction in nigral cell number after nigrostriatal degeneration, there were no changes in alpha4, alpha7, beta2 and beta4 messenger RNA levels in the substantia nigra. In contrast, alpha6 mRNA levels were significantly increased (143+/-10%) and the beta3 transcript decreased (62+/-6%) in the substantia nigra after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. Declines were also observed in [125I]epibatidine binding in both the caudate-putamen and substantia nigra, with no change in alpha7 receptor binding. These results may suggest a dissociation in the regulation of receptor messenger RNA and binding sites, and/or that there are differential alterations in the different receptor subtypes measured using [125I]epibatidine. The changes in the two nicotinic receptor subunit messenger RNAs, alpha6 and beta3, which exhibit a selective localization to the substantia nigra, may indicate that nicotinic receptors containing these subunits are altered after nigrostriatal degeneration.

Neonatal mortality in an aquaporin-2 knock-in mouse model of recessive nephrogenic diabetes insipidus

Hereditary non-X-linked nephrogenic diabetes insipidus (NDI) is caused by mutations in the aquaporin-2 (AQP2) water channel. In transfected cells, the human disease-causing mutant AQP2-T126M is retained at the endoplasmic reticulum (ER) where it is functional and targetable to the plasma membrane with chemical chaperones. A mouse knock-in model of NDI was generated by targeted gene replacement using a Cre-loxP strategy. Along with T126M, mutations H122S, N124S, and A125T were introduced to preserve the consensus sequence for N-linked glycosylation found in human AQP2. Breeding of heterozygous mice yielded the expected Mendelian distribution with 26 homozygous mutant offspring of 99 live births. The mutant mice appeared normal at 2-3 days after birth but failed to thrive and generally died by day 6 if not given supplemental fluid. Urine/serum analysis showed a urinary concentrating defect with serum hyperosmolality and low urine osmolality that was not increased by a V2 vasopressin agonist. Northern blot analysis showed up-regulated AQP2-T126M transcripts of identical size to wild-type AQP2. Immunoblots showed complex glycosylation of wild-type AQP2 but mainly endoglycosidase H-sensitive core glycosylation of AQP2-T126M indicating ER-retention. Biochemical analysis revealed that the AQP2-T126M protein was resistant to detergent solubilization. Kidneys from mutant mice showed collecting duct dilatation, papillary atrophy, and unexpectedly, some plasma membrane AQP2 staining. The severe phenotype of the AQP2 mutant mice compared with that of mice lacking kidney water channels AQP1, AQP3, and AQP4 indicates a critical role for AQP2 in neonatal renal function in mice. Our results establish a mouse model of human autosomal NDI and provide the first in vivo biochemical data on a disease-causing AQP2 mutant.

Characterization of the recombinant human neuronal nicotinic acetylcholine receptors alpha3beta2 and alpha4beta2 stably expressed in HEK293 cells

HEK293 cells were stably transfected with the cDNAs encoding full-length human neuronal nicotinic acetylcholine receptor (nAChR) subunit combinations alpha3beta2 or alpha4beta2. [(3)H]-(+/-)Epibatidine ([(3)H]-(+/-)EPI) bound to membranes from A3B2 (alpha3beta2) and A4B2.2 (alpha4beta2) cells with K(d) values of 7.5 and 33.4 pM and B(max) values of 497 and 1564 fmol/mg protein, respectively. Concentration-dependent increases in intracellular free Ca(2+) concentration were elicited by nAChR agonists with a rank order of potency of EPI>1,1-dimethyl-4-phenylpiperazinium (DMPP)>nicotine (NIC)=suberyldicholine (SUB)>cytisine (CYT)=acetylcholine (ACh) for A3B2 cells and EPI>CYT=SUB=NIC=DMPP>ACh for A4B2.2 cells. Antagonists of nAChRs blocked NIC-induced responses with a rank order of potency of d-tubocurarine (d-Tubo)=mecamylamine (MEC)>dihydro-beta-erythroidine (DHbetaE) in A3B2 cells and MEC=DHbetaE>d-Tubo in A4B2.2 cells. Whole-cell patch clamp recordings indicate that the decay rate of macroscopic ACh-induced currents is faster in A3B2 than in A4B2.2 cells and that A3B2 cells are less sensitive to ACh than A4B2.2 cells. ACh currents elicited in alpha3beta2 and alpha4beta2 human nAChRs are maximally potentiated at 20 and 2 mM external Ca(2+), respectively. Our results indicate that stably expressed alpha3beta2 and alpha4beta2 human nAChRs are pharmacologically and functionally distinct.

Localization of nicotinic receptor subunit mRNAs in monkey brain by in situ hybridization

Nicotinic receptors are implicated in memory, learning, locomotor activity, and addiction. Identification of the specific receptor subtypes that mediate these behaviors is essential for understanding their role in central nervous system (CNS) function. Although expression of nicotinic receptor transcript has been studied in rodent brain, their localization in the monkey CNS, which may be a better model for the human brain, is not yet known. We therefore investigated the distribution of alpha4, alpha6, alpha7, beta2, beta3, and beta4 receptors subunit mRNAs in the monkey brain by using in situ hybridization. alpha4 and alpha7 mRNAs were very widely expressed, with a substantial degree of overlap in their distribution, except for the reticular nucleus of the thalamus in which alpha7 mRNA was much more prominently expressed. beta2 and beta4 mRNA were also widely distributed, although beta4 was more prominently localized in thalamic nuclei than beta2. The distribution of alpha6 and beta3 mRNA was very distinct from that of the other transcripts, being restricted to catecholaminergic nuclei, the cerebellum, and a few other areas. Although there were similarities in distribution of the nicotinic receptor subunit mRNAs in monkey and rodent brain, there were prominent differences in areas such as the caudate, putamen, locus coeruleus, medial habenula, and cerebellum. In fact, the distribution of alpha4 and alpha7 mRNAs in the monkey caudate and putamen was more similar to that reported in the human than rodent brain. These findings have implications for the development of drug therapies for neurological disorders, such as Alzheimer's and Parkinson's disease, in which nicotinic receptors are decreased.

Nephrogenic diabetes insipidus in mice lacking aquaporin-3 water channels

Aquaporin-3 (AQP3) is a water channel expressed at the basolateral plasma membrane of kidney collecting-duct epithelial cells. The mouse AQP3 cDNA was isolated and encodes a 292-amino acid water/glycerol-transporting glycoprotein expressed in kidney, large airways, eye, urinary bladder, skin, and gastrointestinal tract. The mouse AQP3 gene was analyzed, and AQP3 null mice were generated by targeted gene disruption. The growth and phenotype of AQP3 null mice were grossly normal except for polyuria. AQP3 deletion had little effect on AQP1 or AQP4 protein expression but decreased AQP2 protein expression particularly in renal cortex. Fluid consumption in AQP3 null mice was more than 10-fold greater than that in wild-type litter mates, and urine osmolality (<275 milliosmol) was much lower than in wild-type mice (>1,200 milliosmol). After 1-desamino-8-d-arginine-vasopressin administration or water deprivation, the AQP3 null mice were able to concentrate their urine partially to approximately 30% of that in wild-type mice. Osmotic water permeability of cortical collecting-duct basolateral membrane, measured by a spatial filtering optics method, was >3-fold reduced by AQP3 deletion. To test the hypothesis that the residual concentrating ability of AQP3 null mice was due to the inner medullary collecting-duct water channel AQP4, AQP3/AQP4 double-knockout mice were generated. The double-knockout mice had greater impairment of urinary-concentrating ability than did the AQP3 single-knockout mice. Our findings establish a form of nephrogenic diabetes insipidus produced by impaired water permeability in collecting-duct basolateral membrane. Basolateral membrane aquaporins may thus provide blood-accessible targets for drug discovery of aquaretic inhibitors.

Defective secretion of saliva in transgenic mice lacking aquaporin-5 water channels

Aquaporin-5 (AQP5) is a water-selective transporting protein expressed in epithelial cells of serous acini in salivary gland. We generated AQP5 null mice by targeted gene disruption. The genotype distribution from intercross of founder AQP5 heterozygous mice was 70:69:29 wild-type:heterozygote:knockout, indicating impaired prenatal survival of the null mice. The knockout mice had grossly normal appearance, but grew approximately 20% slower than litter-matched wild-type mice when placed on solid food after weaning. Pilocarpine-stimulated saliva production was reduced by more than 60% in AQP5 knockout mice. Compared with the saliva from wild-type mice, the saliva from knockout mice was hypertonic (420 mosM) and dramatically more viscous. Amylase and protein secretion, functions of salivary mucous cells, were not affected by AQP5 deletion. Water channels AQP1 and AQP4 have also been localized to salivary gland; however, pilocarpine stimulation studies showed no defect in the volume or composition of saliva in AQP1 and AQP4 knockout mice. These results implicate a key role for AQP5 in saliva fluid secretion and provide direct evidence that high epithelial cell membrane water permeability is required for active, near-isosmolar fluid transport.

Evaluation of a three-year school-based intervention to increase adolescent sun protection

The efficacy of a school-based intervention was evaluated using a randomized controlled trial in Australia. In consecutive grades (8, 9, and 10), students in the intervention group received components of a program that addressed issues related to the need to protect yourself from the sun, behavioral strategies related to using sun-protective measures, personal and social images of having a tan, the use of sun-safe clothing, and how to change their schools through forms of structural change. Pre- and postintervention measures among junior high school students showed greatest improvement in the intervention group's knowledge scores and minimal changes in sun protection behavior from Grade 8 to Grade 9, which were not maintained through Grade 10. Results of the study highlight some limitations of school-based interventions for changing sun protection behaviors.

The Evolutionary History and Diversity of Australian Mammals

Palaeodiversity and relationships of all groups of Australian mammals are reviewed. The fossil record spanning this time is of variable quality. &apos;Dark Ages&apos; about which nothing is known in terms of Australian mammal evolution include the late Triassic to late Jurassic, late Cretaceous to late Paleocene and middle Eocene to middle Oligocene. Very little is known about the early Cretaceous and late Miocene. The late Oligocene to middle Miocene record documents the highest levels of biodiversity known for the continent, comparable to that which characterises the lowland rainforests of Borneo and Brazil. Order Monotremata spans at least the last 110 million years and includes four families. The enigmatic Ausktribosphenos from 115 million-year-old sediments in Victoria may represent an archaic monotreme, specialised peramurid or previously undocumented order of mammals but is unlikely to represent a placental as suggested in the initial description. Order Microbiotheria is represented in the early Eocene (~55 mya) by two genera similar in morphology to early Eocene taxa from Argentina. Order Peramelemorphia spans the early Eocene to Holocene and includes at least five families. Order Dasyuromorphia spans at least the late Oligocene to Holocene and includes at least three families. Other dasyuromorphian-like marsupials are indeterminate in terms of family-level affinities. Order Notoryctemorphia spans the early Miocene to Holocene with one family. Order Yalkaparidontia spans the late Oligocene to middle Miocene with one genus. Order Diprotodontia spans the late Oligocene to Holocene, represented throughout by three major groups: Phalangerida (eight families), Vombatomorphia (seven families) and Macropodoidea (at least three families). A possible placental condylarth (Tingamarra) has been recorded from the early Eocene. An archaeonycteridid bat (Australonycteris) is known from the early Eocene. Among bats, the late Oligocene to middle Miocene is dominated by rhinolophoids, many of which have European, Asian and African affinities. Mystacinids, megadermatids, hipposiderids and molossids are well-represented in the Oligocene to Miocene deposits. Vespertilionids are uncommon in the Oligocene to Miocene but become more diverse in the Pliocene to Holocene. Emballonurids and rhinolophids appear for the first time in the Plio-Pleistocene. Pteropodids are unknown prior to the Holocene. Murids span the early Pliocene to Holocene. In the oldest assemblage at Riversleigh, one undescribed lineage resembles archaic forms otherwise only known from the fossil records of Africa and Eurasia.

Estimating the weight of the Pleistocene marsupial lion, Thylacoleo carnifex (Thylacoleonidae:Marsupialia): implications for the ecomorphology of a marsupial super-predator and hypotheses of impoverishment of Australian marsupial carnivore faunas

Using demonstrated relationships between body mass and humeral and femoral circumferences, we calculate the weight of the only specimen of Thylacoleo carnifex known from a near-complete skeleton. Body weights of 112–143 kg were estimated for this individual, from Moree, north-western New South Wales. Extrapolating on the basis of geometric similtude, we further estimated the weight of the largest T. carnifex for which we had cranial data at 128–164 kg. Moreover, estimates for at least three of the thirteen available specimens exceeded 124–160 kg, suggesting that individuals of this size were common. Our estimates of average weight for the species range from 101 to 130 kg. These results clearly show that Pleistocene Australia had a 'large' cat equivalent and that 'large' terrestrial predator niches were not then occupied exclusively by reptiles.They may also diminish the argument that soil-nutrient deficiency constrained the evolution of large mammalian carnivores on this continent in the Pleistocene. Similarly, we posit that prima facie evidence for reptilian domination of terrestrial carnivore niches during the Miocene is wanting, although it is conceded that far more detailed investigation is required to comprehensively test these hypotheses. Earlier studies have drawn parallels between T. carnifex and sabre-toothed predators, thought to have specialised in hunting particularly large and powerful prey. Taken in the context of upwardly revised weight estimates, we argue that Pleistocene marsupial lions may have dispatched even Diprotodon-sized animals. But again, more comprehensive study, including thorough biomechanical design analysis of the post-cranial skeleton in particular, will be required to thoroughly illuminate the predatory habitus and general ecology of Australia's largest and most specialised marsupial carnivore.

Regulation of nicotinic receptor subtypes following chronic nicotinic agonist exposure in M10 and SH-SY5Y neuroblastoma cells

The present study further investigated whether nicotinic acetylcholine receptor (nAChR) subtypes differ in their ability to up-regulate following chronic exposure to nicotinic agonists. Seven nicotinic agonists were studied for their ability to influence the number of chick alpha4beta2 nAChR binding sites stably transfected in fibroblasts (M10 cells) following 3 days of exposure. The result showed a positive correlation between the Ki values for binding inhibition and EC50 values for agonist-induced alpha4beta2 nAChR up-regulation. The effects of epibatidine and nicotine were further investigated in human neuroblastoma SH-SY5Y cells (expressing alpha3, alpha5, beta2, and beta4 nAChR subunits). Nicotine exhibited a 14 times lower affinity for the nAChRs in SH-SY5Y cells as compared with M10 cells, whereas epibatidine showed similar affinities for the nAChRs expressed in the two cell lines. The nicotine-induced up-regulation of nAChR binding sites in SH-SY5Y cells was shifted to the right by two orders of magnitude as compared with that in M10 cells. The epibatidine-induced up-regulation of nAChR binding sites in SH-SY5Y cells was one-fourth that in M10 cells. The levels of mRNA of the various nAChR subunits were measured following the nicotinic agonist exposure. In summary, the various nAChR subtypes show different properties in their response to chronic stimulation.

Severely impaired urinary concentrating ability in transgenic mice lacking aquaporin-1 water channels

Water channel aquaporin-1 (AQP1) is strongly expressed in kidney in proximal tubule and descending limb of Henle epithelia and in vasa recta endothelia. The grossly normal phenotype in human subjects deficient in AQP1 (Colton null blood group) and in AQP4 knockout mice has suggested that aquaporins (other than the vasopressin-regulated water channel AQP2) may not be important in mammalian physiology. We have generated transgenic mice lacking detectable AQP1 by targeted gene disruption. In kidney proximal tubule membrane vesicles from knockout mice, osmotic water permeability was reduced 8-fold compared with vesicles from wild-type mice. Although the knockout mice were grossly normal in terms of survival, physical appearance, and organ morphology, they became severely dehydrated and lethargic after water deprivation for 36 h. Body weight decreased by 35 +/- 2%, serum osmolality increased to >500 mOsm, and urinary osmolality (657 +/- 59 mOsm) did not change from that before water deprivation. In contrast, wild-type and heterozygous mice remained active after water deprivation, body weight decreased by 20-22%, serum osmolality remained normal (310-330 mOsm), and urine osmolality rose to >2500 mOsm. Urine [Na+] in water-deprived knockout mice was <10 mM, and urine osmolality was not increased by the V2 agonist DDAVP. The results suggest that AQP1 knockout mice are unable to create a hypertonic medullary interstitium by countercurrent multiplication. AQP1 is thus required for the formation of a concentrated urine by the kidney.

Phase II trial of topotecan administered as 72-hour continuous infusion in children with refractory solid tumors: a collaborative Pediatric Branch, National Cancer Institute, and Children's Cancer Group Study

The antitumor activity of topotecan administered as a 72-h continuous i.v. infusion was evaluated in children with refractory neuroblastoma and sarcomas of soft tissue and bone. We also attempted to increase the dose intensity of topotecan by including an intrapatient dose escalation in the trial design. Ninety-three children (85 eligible and evaluable for response) with recurrent or refractory neuroblastoma, osteosarcoma, Ewing's sarcoma/peripheral neuroectodermal tumor, rhabdomyosarcoma, or other soft-tissue sarcomas received topotecan administered as a 72-h i.v. infusion every 21 days. The initial dose was 1.0 mg/m2/day, with subsequent intrapatient dose escalation to 1.3 mg/m2/day for those patients who did not experience dose-limiting toxicity after their first cycle of topotecan. There was one complete response in a patient with neuroblastoma (n = 26) and one partial response in a patient with Ewing's sarcoma/peripheral neuroectodermal tumor (n = 25). No complete or partial responses were observed in 17 patients with osteosarcoma, 15 patients with rhabdomyosarcoma, or 2 patients with other soft-tissue sarcomas; however, 8 patients had prolonged (15-48 weeks) stable disease while receiving topotecan. Topotecan was well tolerated. The most commonly observed toxicities were myelosuppression (dose-limiting) and nausea and vomiting. Intrapatient dose escalations were performed in 68% of the patients who received more than one cycle of topotecan, and 1.3 mg/m2/day was tolerated by 79% of the patients who received the higher dose and were evaluable for hematological toxicity. In conclusion, topotecan administered as a 72-h continuous infusion every 21 days is inactive (objective response rate, < 20%) in children with refractory or recurrent neuroblastoma and sarcomas of soft tissue or bone.

Characterization of human recombinant neuronal nicotinic acetylcholine receptor subunit combinations alpha2beta4, alpha3beta4 and alpha4beta4 stably expressed in HEK293 cells

Human embryonic kidney (HEK293) cells were transfected with cDNA encoding the human beta4 neuronal nicotinic acetylcholine (ACh) receptor subunit in pairwise combination with human alpha2, alpha3 or alpha4 subunits. Cell lines A2B4, A3B4.2 and A4B4 were identified that stably express mRNA and protein corresponding to alpha2 and beta4, to alpha3 and beta4 and to alpha4 and beta4 subunits, respectively. Specific binding of [3H]epibatidine was detected in A2B4, A3B4.2 and A4B4 cells with Kd (mean +/- S.D. in pM) values of 42 +/- 10, 230 +/- 12 and 187 +/- 29 and with Bmax (fmol/mg protein) values of 1104 +/- 338, 2010 +/- 184 and 3683 +/- 1450, respectively. Whole-cell patch-clamp recordings in each cell line demonstrated that (-)nicotine (Nic), ACh, cytisine (Cyt) and 1, 1-dimethyl-4-phenylpiperazinium iodide (DMPP) elicit transient inward currents. The current-voltage (I-V) relation of these currents showed strong inward rectification. Pharmacological characterization of agonist-induced elevations of intracellular free Ca++ concentration revealed a distinct rank order of agonist potency for each subunit combination as follows: alpha2beta4, (+)epibatidine (Epi) > Cyt > suberyldicholine (Sub) = Nic = DMPP; alpha3beta4, Epi > DMPP = Cyt = Nic = Sub; alpha4beta4, Epi > Cyt = Sub > Nic > DMPP. The noncompetitive antagonists mecamylamine and d-tubocurarine did not display subtype selectivity. In contrast, the Kb value for the competitive antagonist dihydro-beta-erythroidine (DHbetaE) was highest at alpha3beta4 compared with alpha2beta4 or alpha4beta4 receptors. These data illustrate that the A2B4, A3B4.2 and A4B4 stable cell lines are powerful tools for examining the functional and pharmacological properties of human alpha2beta4, alpha3beta4 and alpha4beta4 neuronal nicotinic receptors.

Generation and phenotype of a transgenic knockout mouse lacking the mercurial-insensitive water channel aquaporin-4

Aquaporin-4 (AQP4) is a mercurial-insensitive, water-selective channel that is expressed in astroglia and basolateral plasma membranes of epithelia in the kidney collecting duct, airways, stomach, and colon. A targeting vector for homologous recombination was constructed using a 7-kb SacI AQP4 genomic fragment in which part of the exon 1 coding sequence was deleted. Analysis of 164 live births from AQP4[+/-] matings showed 41 [+/+], 83 [+/-], and 40 [-/-] genotypes. The [-/-] mice expressed small amounts of a truncated AQP4 transcript and lacked detectable AQP4 protein by immunoblot analysis and immunocytochemistry. Water permeability in an AQP4-enriched brain vesicle fraction in [+/+] mice was high and mercurial insensitive, and was decreased by 14-fold in [-/-] mice. AQP4 deletion did not affect growth or tissue morphology at the light microscopic level. Northern blot analysis showed that tissue-specific expression of AQPs 1, 2, 3, and 5 was not affected by AQP4 deletion. Maximum urine osmolality after a 36-h water deprivation was (in mosM, n = 15) [+/+] 3,342+/-209, [+/-] 3, 225+/-167, and [-/-] 2,616+/-229 (P < 0.025), whereas urine osmolalities before water deprivation did not differ among the genotypes. Rotorod analysis of 35- 38-d-old mice revealed no differences in neuromuscular function (performance time in s, n = 8): [+/+] 297+/-25, [+/-] 322+/-28, [-/-] 288+/-37. These results indicate that AQP4 deletion in CD1 mice has little or no effect on development, survival, growth, and neuromuscular function, but produces a small defect in urinary concentrating ability consistent with its expression in the medullary collecting duct.

The expression of voltage-dependent calcium channel beta subunits in human cerebellum

The beta subunits of voltage-dependent calcium channels, exert marked regulatory effects on the biophysical and pharmacological properties of this diverse group of ion channels. However, little is known about the comparative neuronal expression of the four classes of beta genes in the CNS. In the current investigation we have closely mapped the distribution of beta1, beta2, beta3 and beta4 subunits in the human cerebellum by both in situ messenger RNA hybridization and protein immunohistochemistry. To our knowledge, these studies represent the first experiments in any species in which the detailed localization of each beta protein has been comparatively mapped in a neuroanatomically-based investigation. The data indicate that all four classes of beta subunits are found in the cerebellum and suggest that in certain neuronal populations they may each be expressed within the same cell. Novel immunohistochemical results further exemplify that the beta voltage-dependent calcium channel subunits are regionally distributed in a highly specific manner and studies of Purkinje cells indicate that this may occur at the subcellular level. Preliminary indication of the subunit composition of certain native voltage-dependent calcium channels is suggested by the observation that the distribution of the beta3 subunit in the cerebellar cortex is identical to that of alpha(1E). Our cumulative data are consistent with the emerging view that different native alpha1/beta subunit associations occur in the CNS.

Preparation and purification of antibodies specific to human neuronal voltage-dependent calcium channel subunits

Neuronal voltage-dependent calcium channels (VDCCs) each comprising of alpha 1, alpha 2 delta, and beta subunits, are one mechanism by which excitable cells regulate the flux of calcium ions across the cell membrane following depolarisation Studies have shown the expression of several alpha 1 and beta subtypes within neuronal tissue. The comparative distribution of these in normal human brain is largely unknown. The aim of this work is to prepare antibodies directed specifically to selected subunits of human neuronal VDCCs for use in biochemical and mapping studies of calcium channel subtypes in the brain. Previous studies have defined DNA sequences specific for each subunit Comparison of these sequences allows the selection of unique amino acid sequences for use as immunogens which are prepared as glutathione-S-transferase (GST) fusion proteins in E. coli. Polyclonal antibodies raised against these fusion proteins are purified by Protein A chromatography, followed by immunoaffinity chromatography and extensive adsorptions using the appropriate fusion protein-GST Sepharose 4B columns. The resultant antibodies are analysed for specificity against the fusion proteins by ELISA, and by immunofluorescence and Western immunoblot analysis of recombinant HEK293 cells stably transfected with cDNAs encoding alpha 1, alpha 2 delta and beta subunits.

A comparison of a 12-hour and eight-hour shift system

Despite the increasing use of, and discussion about, 12-hour shifts there has been little assessment of its impact in the UK. A study was carried out to compare two medical wards that had been operating a 12-hour shift for more than one year with two medical wards that had continued with a conventional shift system over the same period. Staff questionnaires and interviews, patient interviews, documentation review and analysis of a number of organisational issues were undertaken to evaluate the effect of the shift pattern worked. There were no significant differences between the shift patterns. However, some aspects of the 12-hour shift produced more favourable responses from the staff: less fatigue was reported by those working the 12-hour shift and documentation was more complete on these wards. However, the length of time available for the handover was identified as a problematic area. This work demonstrates the complexities in evaluating patterns of work.