Pre-implantation Pregnancy Disruption in Female Meadow Voles Microtus pennsylvanicus (Rodentia: Muridae): Male Competition or Female Mate Choice?

I investigated alternative hypotheses concerning the functions of pre-implantation male-induced pregnancy disruption in meadow voles. Disruptions may be viewed as: 1. Postcopulatory male competition; 2. A mechanism for postcopulatory mate choice by females; and 3. A means of benefitting females by terminating investment in litters that may be harmed by new males. Female voles were paired with a second male 3 d after mating with their first mate. Behavioural interactions between the female and each male were compared for females that disrupted or retained the pregnancy sired by the first male. Whether they were the females' first or second mates, males siring litters showed similar high levels of approach and moderately high aggression, behaviour that differed from the females' other mates. Disrupted females huddled sooner with their second mates than females that retained their original pregnancies, and females tended to approach males that approached them. These results suggest that females influence whether a disruption occurs by the amount of contact they initiate with the second male, and thus pregnancy disruption may facilitate postcopulatory mate choice by females. This pre-implantation disruption did not enhance female reproductive success: pup survival was the same whether or not a disruption occurred, and males living with pups they had sired (after a disruption) spent as much time with them as males with unrelated pups (females did not disrupt).     

Differences in adhesiveness among type 1 fimbriate strains of Enterobacteriaceae revealed by an in vitro HEp2 cell adhesion model

Ten type 1 fimbriate strains of Enterobacteriaceae were examined in an in vitro adhesion assay with HEp2 epithelial cells. The range of HEp2 cell adhesiveness, which was characteristic for each strain, was affected by motility, type 1 fimbriation and production of mannose sensitive haemagglutinin. Nevertheless, not all type 1 fimbriate strains adhered well in this model. The findings are discussed with regard to the possibility that different type 1 fimbriate enterobacteria, though all are mannose sensitive, recognize different mannose-containing receptors present or available on the surfaces of the HEp2 cells.     

Phase II study of vaccinia melanoma cell lysates (VMCL) as adjuvant to surgical treatment of stage II melanoma

Summary Patients with stage II melanoma were vaccinated with vaccinia virus-induced melanoma cell lysates (VMCL). The vaccine contained viable vaccinia virus, membranous fragments and no intact nuclei. A number of antigens defined by monoclonal antibodies were detected in the vaccine including the ganglioside GD3 and DR antigens. Administration of the vaccine was associated with depression of natural killer cell activity against melanoma and K562 target cells in the first 3–6 months of treatment. Leucocyte dependent antibody (LDA) activity against melanoma cells was induced or increased in titre in approximately half of the patients studied. Continued vaccination was associated in a number of patients with a decrease in LDA titres. Studies on a small sample of patients revealed that this was associated with the development of serum factors which inhibited LDA activity. LDA activity appeared directed to non-MHC antigens on melanoma cells which were of at least two specificities. One specificity which was shared with antigens on a number of non-melanoma carcinoma cells was removed by absorption on fetal brain and may be similar to oncofetal antigens described by other workers. Reactivity against melanocytes was induced in some patients and may underlie the development of vitiligo in several patients. These results suggest that vaccines prepared from VMCL may be a favourable method for increasing immune responses against melanoma.     

Enhancement of antidepressant potency by a potentiator of AMPA receptors

1. AMPA receptor potentiators (ARPs) exhibit antidepressant-like activity in preclinical tests (for example, the forced swim test) that are highly predictive of efficacy in humans. Unlike most currently used antidepressants, ARPs do not elevate extracellular levels of biogenic amines (e.g., 5HT, NE) in prefrontal cortex at doses that are active in the forced swim test.2. The present series of experiments examined the effects of combining the ARP, LY 392098, with biogenic amine-based antidepressants in the forced swim test. Male, NIH Swiss mice were placed in a cylinder of water and observed for attempted escape behaviors and immobility.3. LY 392098 dose-dependently decreased immobility as did a range of classical antidepressants. At doses of LY 392098 below those that decreased immobility, this compound significantly increased the potency with which fluoxetine and citalopram (SSRI antidepressants), imipramine (tricyclic antidepressant), duoxetine (norepinephrine/serotonin uptake blocker), nisoxetine (norepinephrine uptake inhibitor), and rolipram (PDE4 inhibitor) decreased immobility in the forced swim test with potency shifts upward of 5-fold (fluoxetine, imipramine, and rolipram). Likewise, ineffective doses of the traditional antidepressants potentiated the effects LY 392098 with shifts in the dose-effect functions that were 10-fold or more for citalopram, fluoxetine, imipramine, and duloxetine.4. Combined with other evidence for a role of AMPA receptors in the efficacy of antidepressants, the current data suggest that the addition of an ARP may augment the activity and perhaps the onset of the therapeutic effects of biogenic amine and second messenger-based antidepressants.     

Molecular modeling of glycosyltransferases involved in the biosynthesis of blood group A,blood group B,Forssman, and iGb3 antigens and their interaction with substrates

A terminal alpha1-3 linked Gal or GalNAc sugar residue is the common structure found in several oligosaccharide antigens, such as blood groups A and B, the xeno-antigen, the Forssman antigen, and the isogloboside 3 (iGb3) glycolipid. The enzymes involved in the addition of this residue display strong amino acid sequence similarities, suggesting a common fold. From a recently solved crystal structure of the bovine alpha3-galactosyltransferase complexed with UDP, homology modeling methods were used to build the four other enzymes of this family in their locked conformation. Nucleotide-sugars, the Mn2+ ion, and oligosaccharide acceptors were docked in the models. Nine different amino acid regions are involved in the substrate binding sites. After geometry optimization of the complexes and analysis of the predicted structures, the basis of the specificities can be rationalized. In the nucleotide-sugar binding site, the specificity between Gal or GalNAc transferase activity is due to the relative size of two clue amino acids. In the acceptor site, the presence of up to three tryptophan residues define the complexity of the oligosaccharide that can be specifically recognized. The modeling study helps in rationalizing the crystallographic data obtained in this family and provides insights on the basis of substrate and donor recognition.     

Effects of deletion of the prolactin receptor on ovarian gene expression

Prolactin (PRL) exerts pleiotropic physiological effects in various cells and tissues, and is mainly considered as a regulator of reproduction and cell growth. Null mutation of the PRL receptor (R) gene leads to female sterility due to a complete failure of embryo implantation. Pre-implantatory egg development, implantation and decidualization in the mouse appear to be dependent on ovarian rather than uterine PRLR expression, since progesterone replacement permits the rescue of normal implantation and early pregnancy. To better understand PRL receptor deficiency, we analyzed in detail ovarian and corpora lutea development of PRLR-/- females. The present study demonstrates that the ovulation rate is not different between PRLR+/+ and PRLR-/- mice. The corpus luteum is formed but an elevated level of apoptosis and extensive inhibition of angiogenesis occur during the luteal transition in the absence of prolactin signaling. These modifications lead to the decrease of LH receptor expression and consequently to a loss of the enzymatic cascades necessary to produce adequate levels of progesterone which are required for the maintenance of pregnancy.     

CR1-mediated ATP Release by Human Red Blood Cells Promotes CR1 Clustering and Modulates the Immune Transfer Process

Humans and other higher primates are unique among mammals in using complement receptor 1 (CR1, CD35) on red blood cells (RBC) to ligate complement-tagged inflammatory particles (immune complexes, apoptotic/necrotic debris, and microbes) in the circulation for quiet transport to the sinusoids of spleen and liver where resident macrophages remove the particles, but allow the RBC to return unharmed to the circulation. This process is called immune-adherence clearance. In this study we found using luminometric- and fluorescence-based methods that ligation of CR1 on human RBC promotes ATP release. Our data show that CR1-mediated ATP release does not depend on Ca²⁺ or enzymes previously shown to mediate an increase in membrane deformability promoted by CR1 ligation. Furthermore, ATP release following CR1 ligation increases the mobility of the lipid fraction of RBC membranes, which in turn facilitates CR1 clustering, and thereby enhances the binding avidity of complement-opsonized particles to the RBC CR1. Finally, we have found that RBC-derived ATP has a stimulatory effect on phagocytosis of immune-adherent immune complexes.     

The Interactomes of Influenza Virus NS1 and NS2 Proteins Identify New Host Factors and Provide Insights for ADAR1 Playing a Supportive Role in Virus Replication

Influenza A NS1 and NS2 proteins are encoded by the RNA segment 8 of the viral genome. NS1 is a multifunctional protein and a virulence factor while NS2 is involved in nuclear export of viral ribonucleoprotein complexes. A yeast two-hybrid screening strategy was used to identify host factors supporting NS1 and NS2 functions. More than 560 interactions between 79 cellular proteins and NS1 and NS2 proteins from 9 different influenza virus strains have been identified. These interacting proteins are potentially involved in each step of the infectious process and their contribution to viral replication was tested by RNA interference. Validation of the relevance of these host cell proteins for the viral replication cycle revealed that 7 of the 79 NS1 and/or NS2-interacting proteins positively or negatively controlled virus replication. One of the main factors targeted by NS1 of all virus strains was double-stranded RNA binding domain protein family. In particular, adenosine deaminase acting on RNA 1 (ADAR1) appeared as a pro-viral host factor whose expression is necessary for optimal viral protein synthesis and replication. Surprisingly, ADAR1 also appeared as a pro-viral host factor for dengue virus replication and directly interacted with the viral NS3 protein. ADAR1 editing activity was enhanced by both viruses through dengue virus NS3 and influenza virus NS1 proteins, suggesting a similar virus-host co-evolution.     

Expanding the Repertoire of Gene Tools for Precise Manipulation of the Clostridium difficile Genome: Allelic Exchange Using pyrE Alleles

Sophisticated genetic tools to modify essential biological processes at the molecular level are pivotal in elucidating the molecular pathogenesis of Clostridium difficile, a major cause of healthcare associated disease. Here we have developed an efficient procedure for making precise alterations to the C. difficile genome by pyrE-based allelic exchange. The robustness and reliability of the method was demonstrated through the creation of in-frame deletions in three genes (spo0A, cwp84, and mtlD) in the non-epidemic strain 630Δerm and two genes (spo0A and cwp84) in the epidemic PCR Ribotype 027 strain, {"type":"entrez-nucleotide","attrs":{"text":"R20291","term_id":"774925","term_text":"R20291"}}R20291. The system is reliant on the initial creation of a pyrE deletion mutant, using Allele Coupled Exchange (ACE), that is auxotrophic for uracil and resistant to fluoroorotic acid (FOA). This enables the subsequent modification of target genes by allelic exchange using a heterologous pyrE allele from Clostridium sporogenes as a counter-/negative-selection marker in the presence of FOA. Following modification of the target gene, the strain created is rapidly returned to uracil prototrophy using ACE, allowing mutant phenotypes to be characterised in a PyrE proficient background. Crucially, wild-type copies of the inactivated gene may be introduced into the genome using ACE concomitant with correction of the pyrE allele. This allows complementation studies to be undertaken at an appropriate gene dosage, as opposed to the use of multicopy autonomous plasmids. The rapidity of the ‘correction’ method (5–7 days) makes pyrE ⁻ strains attractive hosts for mutagenesis studies.