Temporary depletion of CD11c+ dendritic cells delays lymphoinvasion after intraperitonal scrapie infection

The involvement of immune cells in prion capture and transport to lymphoid tissues still remains unclear. To investigate the role of dendritic cells (DC), we used DTR^+/+ mice, a transgenic model designed to trigger short-term ablation of DC. Transient depletion of DC around the time of intraperitoneal infection delayed prion replication in the spleen, as followed by PrPsc amount, a specific hallmark of prion diseases. Consequently, neuroinvasion and incubation time of prion disease were delayed. In contrast, no differences were observed after oral infection. These results suggest that DC act as vectors for prions from the peripheral entry site to the spleen.     

Environmental stability and the distribution of the sexes: insights from life history experiments with the geographic parthenogen Eucypris virens (Crustacea: Ostracoda)

In many species with mixed reproduction, parthenogens cover a wider geographic range than sexuals. In freshwater ostracods this pattern referred to as geographic parthenogenesis is traditionally explained by ascribing a higher potential for dispersal to parthenogens. For example, the postglacial invasion hypothesis states that the lack of males in northern Europe is caused by the relatively slow range expansion of sexual lineages after deglaciation. An alternative explanation for the contemporary distribution of the sexes is based on spatial and temporal variations in ecological habitat stability. To test this hypothesis, we compared life history data of Eucypris virens individuals originating from bisexual and all-female populations. Populations with males are only found around the Mediterranean, whereas parthenogens cover most of Europe. The animals were hatched and grown in environments mimicking temperature and photoperiod conditions observed in Belgium and Spain. The data confirm the higher potential for population growth in parthenogens. In particular their faster hatching response, possibly higher fecundity (as derived from a difference in body height) and the absence of a cost of males should allow them to out-compete sexuals under stable conditions. However, the comparison of the hatchling accumulation curves of bisexual and all-female populations suggests that sexuals have an advantage in highly unpredictable environments. Indeed, under conditions mimicking those in southern Europe, bisexual populations exhibit a bet-hedging strategy, while parthenogenetic resting eggs hatch on average earlier and more synchronously. Overall, the life history data stress the importance of short term environmental fluctuations for the distribution of the sexes in E. virens , and probably many other inhabitants of ephemeral water bodies.     

Effects of aging on hematology and serum clinical chemistry in chimpanzees (Pan troglodytes)

A number of age-related changes in physiological functions have been identified in macaques and humans. However, few studies have examined physiological aging in chimpanzees, despite the increasing age of the chimpanzee population. We documented age-related changes in seven hematology and 17 clinical chemistry parameters in 49 adult chimpanzees (17 males, 32 females) as a comparative viewpoint with human and macaque aging. Longitudinal data were analyzed using weighted linear and quadratic mixed effects regression models. Male chimpanzees exhibited a significant age-related increase in anemia risk, based on significant decreases in hemoglobin (F(1,49)=12.45, P=0.0009) and hematocrit (F(1,49)=15.42, P=0.0003). Both sexes exhibited significant age-related decreases in both kidney and liver function. Decreases in kidney function were noted by significant increases in blood urea nitrogen (F(1,45)=3.92, P=0.036) and creatinine (F(1,50)=5.63, P=0.022) as well as changes in electrolyte (i.e., sodium, potassium, phosphorous, chloride) balance. Declining liver function was based on significant increases in globulin (F(1,46)=32.34, P<0.0001) and decreases in albumin (F(1,48)=23.42, P<0.0001). These changes were most evident beginning at 25-30 years of age in males and 30-35 years of age in females. We recommend amending chimpanzee age classes to categorize males over 25 years and females over 30 years as aged.     

Characterization of anticoagulant heparinoids by immunoprofiling

Heparinoids are used in the clinic as anticoagulants. A specific pentasaccharide in heparinoids activates antithrombin III, resulting in inactivation of factor Xa and–when additional saccharides are present–inactivation of factor IIa. Structural and functional analysis of the heterogeneous heparinoids generally requires advanced equipment, is time consuming, and needs (extensive) sample preparation. In this study, a novel and fast method for the characterization of heparinoids is introduced based on reactivity with nine unique anti-heparin antibodies. Eight heparinoids were biochemically analyzed by electrophoresis and their reactivity with domain-specific anti-heparin antibodies was established by ELISA. Each heparinoid displayed a distinct immunoprofile matching its structural characteristics. The immunoprofile could also be linked to biological characteristics, such as the anti-Xa/anti-IIa ratio, which was reflected by reactivity of the heparinoids with antibodies HS4C3 (indicative for 3-O-sulfates) and HS4E4 (indicative for domains allowing anti-factor IIa activity). In addition, the immunoprofile could be indicative for heparinoid-induced side-effects, such as heparin-induced thrombocytopenia, as illustrated by reactivity with antibody NS4F5, which defines a very high sulfated domain. In conclusion, immunoprofiling provides a novel, fast, and simple methodology for the characterization of heparinoids, and allows high-throughput screening of (new) heparinoids for defined structural and biological characteristics.     

Synthesis of new N-isobutyryl-L-cysteine/MEA conjugates: evaluation of their free radical-scavenging activities and anti-HIV properties in human macrophages

Four novel N-isobutyryl-l-cysteine/2-mercaptoethylamine (MEA, cysteamine) conjugates have been designed and synthesized. The antioxidant activities of these new series were evaluated by three different free radical scavenging methods (DPPH test, ABTS test, and deoxyribose assay) and their metal binding capacity was evaluated by the ethidium bromide fluorescence binding assay. These results were compared with those obtained with their pro-GSH acetyl analogues recently developed in our laboratory. We observed that most of these compounds exhibit free radical-scavenging activities similar to those of Trolox, but always superior than NAC. While none of these new derivatives had pro-GSH activities, they displayed anti-HIV properties in human monocyte-derived macrophages infected in vitro. The present study demonstrates that these new N-isobutyryl derivatives, which are expected to have a greater bioavailability than their acetyl analogues, may have useful applications in HIV infection in respect to their antioxidant and anti-HIV activities.     

Comparative analysis of multiple disease resistance in ryegrass and cereal crops

Ryegrass (Lolium spp.) is among the most important forage crops in Europe and Australia and is also a popular turfgrass in North America. Previous genetic analysis based on a three-generation interspecific (L. perenne x L. multiflorum) ryegrass population identified four quantitative trait loci (QTLs) for resistance to gray leaf spot (Magneporthe grisea) and four QTLs for resistance to crown rust (Puccinia coronata). The current analysis based on the same mapping population detected seven QTLs for resistance to leaf spot (Bipolaris sorokiniana) and one QTL for resistance to stem rust (Puccinia graminis) in ryegrass for the first time. Three QTLs for leaf spot resistance on linkage groups (LGs) 2 and 4 were in regions of conserved synteny to the positions of resistance to net blotch (Drechslera teres) in barley (Hordeum vulgare). One ryegrass genomic region spanning 19 cM on LG 4, which contained three QTLs for resistance to leaf spot, gray leaf spot, and stem rust, had a syntenic relationship with a segment of rice chromosome 3, which contained QTLs for resistance to multiple diseases. However, at the genome-wide comparison based on 72 common RFLP markers between ryegrass and cereals, coincidence of QTLs for disease resistance to similar fungal pathogens was not statistically significant.     

Role of recombination in the evolution of the model plant pathogen Pseudomonas syringae pv. tomato DC3000, a very atypical tomato strain

Pseudomonas syringae pv. tomato strain DC3000 (PtoDC3000) is one of the most intensively studied bacterial plant pathogens today. Here we report a thorough investigation into PtoDC3000 and close relatives isolated from Antirrhinum majus (snapdragon), Apium graveolens (celery), and Solanaceae and Brassicaceae species. Multilocus sequence typing (MLST) was used to resolve the precise phylogenetic relationship between isolates and to determine the importance of recombination in their evolution. MLST data were correlated with an analysis of the locus coding for the type III secreted (T3S) effector AvrPto1 to investigate the role of recombination in the evolution of effector repertoires. Host range tests were performed to determine if closely related isolates from different plants have different host ranges. It was found that PtoDC3000 is located in the same phylogenetic cluster as isolates from several Brassicaceae and Solanaceae species and that these isolates have a relatively wide host range that includes tomato, Arabidopsis thaliana, and cauliflower. All other analyzed tomato isolates from three different continents form a distinct cluster and are pathogenic only on tomato. Therefore, PtoDC3000 is a very unusual tomato isolate. Several recombination breakpoints were detected within sequenced gene fragments, and population genetic tests indicate that recombination contributed more than mutation to the variation between isolates. Moreover, recombination may play an important role in the reassortment of T3S effectors between strains. The data are finally discussed from a taxonomic standpoint, and P. syringae pv. tomato is proposed to be divided into two pathovars.     

Analysis of vaginal lactobacilli from healthy and infected Brazilian women

Culture-dependent PCR-amplified rRNA gene restriction analysis and culture-independent (PCR-denaturing gradient gel electrophoresis) methodologies were used to examine vaginal lactobacilli from Brazilian women who were healthy or had been diagnosed with vulvovaginal candidiasis (VVC) or bacterial vaginosis. Only Lactobacillus crispatus was detected accordingly by both methods, and H(2)O(2)-producing lactobacilli were not associated with protection against VVC.