Risk of Infection with Leishmania spp. in the Canine Population in the Netherlands

The dog is the main reservoir of Leishmania infantum, the causative agent of visceral leishmaniasis (VL) in humans in Southern Europe. In order to identify the risk of dogs from a Leishmania non-endemic area traveling to a Leishmania -endemic area becoming infected and the risk of transmitting infection to humans in non-endemic areas an investigation was performed, in which the results of a questionnaire were combined with the results of a serologic survey.     

SCF acts in endosomal sorting of the GH receptor

The ubiquitin ligase SCF^TrCP is required for internalisation of the growth hormone receptor (GHR) and acts via a direct interaction with the ubiquitin-dependent endocytosis motif. Details of how the ligase communicates its information to the clathrin-mediated internalisation machinery are unknown. For the EGF receptor, c-Cbl acts both at the cell surface and in endosomes. We hypothesised that SCF^TrCP is required for GHR degradation at both sites. This was tested by truncating GHR after a di-leucine-based internalisation motif (GHR349). This receptor enters the cells via the adapter complex AP2. We show that TrCP acts in an early stage of cargo selection: both TrCP silencing and mutation of the ubiquitin-dependent endocytosis motif force the GHR to recycle between endosomes and the plasma membrane, together with the transferrin receptor. Depletion of Tsg101 (ESCRT-I) has the same effect, while silencing of Hrs (ESCRT-0) prevents GH recycling. GH passes through late endosomal vesicles, marked by Lamp1. Coexpressing GHR and EGFR demonstrates that both receptors use the same route to the lysosomes. We show for the first time that SCF^TrCP is involved in cargo-specific sorting at endosomes and that Tsg101 rather than Hrs might direct the cargo into the ESCRT machinery.     

SCF(TrCP) acts in endosomal sorting of the GH receptor

The ubiquitin ligase SCF(TrCP) is required for internalisation of the growth hormone receptor (GHR) and acts via a direct interaction with the ubiquitin-dependent endocytosis motif. Details of how the ligase communicates its information to the clathrin-mediated internalisation machinery are unknown. For the EGF receptor, c-Cbl acts both at the cell surface and in endosomes. We hypothesised that SCF(TrCP) is required for GHR degradation at both sites. This was tested by truncating GHR after a di-leucine-based internalisation motif (GHR349). This receptor enters the cells via the adapter complex AP2. We show that TrCP acts in an early stage of cargo selection: both TrCP silencing and mutation of the ubiquitin-dependent endocytosis motif force the GHR to recycle between endosomes and the plasma membrane, together with the transferrin receptor. Depletion of Tsg101 (ESCRT-I) has the same effect, while silencing of Hrs (ESCRT-0) prevents GH recycling. GH passes through late endosomal vesicles, marked by Lamp1. Coexpressing GHR and EGFR demonstrates that both receptors use the same route to the lysosomes. We show for the first time that SCF(TrCP) is involved in cargo-specific sorting at endosomes and that Tsg101 rather than Hrs might direct the cargo into the ESCRT machinery.     

Variation in heat-shock proteins among species of desert fishes (Poeciliidae, Poeciliopsis)

Analysis of the heat-shock proteins (hsps) of six closely related species of Poeciliopsis demonstrated the existence of biochemical diversity in the hsp100, hsp70, hsp60, and hsp30 protein families among species. Each species expressed five to seven hsp70-related isoforms. Constitutive 70-kD isoforms were identical among species, but four different patterns of heat-inducible isoforms were seen in these six species. Members of the hsp70 family of molecular chaperones are included among the most highly conserved proteins known, and the possibility of variation in hsp70 among closely related species has rarely been addressed. The hsp30 family is known to be less conserved than the hsp70 family, and, as expected, the Poeciliopsis hsp30 patterns showed more variation. Most of the hsp30 isoforms characteristic of a particular species were unique to that species. Hsp100 and hsp60 were identical in five of the species, but alternate isoforms were found in P. monacha. The small size and limited geographical distribution of the P. monacha population have probably contributed to the uniqueness of the monacha pattern. Two of the species were shown to acquire thermotolerance, the ability to withstand normally lethal temperatures when subjected to a gradual temperature increase. Rapid-heating protocols commonly used to establish critical thermal maxima of organisms do not include this inducible component of thermoresistance and therefore do not adequately assess an organism's capacity to withstand thermal stress.      

Assessment of therapeutic responses to gametocytocidal drugs in Plasmodium falciparum malaria

Background

Effective mating between laboratory-reared males and wild females is paramount to the success of vector control strategies aiming to decrease disease transmission via the release of sterile or genetically modified male mosquitoes. However mosquito colonization and laboratory maintenance have the potential to negatively affect male genotypic and phenotypic quality through inbreeding and selection, which in turn can decrease male mating competitiveness in the field. To date, very little is known about the impact of those evolutionary forces on the reproductive biology of mosquito colonies and how they ultimately affect male reproductive fitness.

Methods

Here several male reproductive physiological traits likely to be affected by inbreeding and selection following colonization and laboratory rearing were examined. Sperm length, and accessory gland and testes size were compared in male progeny from field-collected females and laboratory strains of Anopheles gambiae sensu stricto colonized from one to over 25 years ago. These traits were also compared in the parental and sequentially derived, genetically modified strains produced using a two-phase genetic transformation system. Finally, genetic crosses were performed between strains in order to distinguish the effects of inbreeding and selection on reproductive traits.

Results

Sperm length was found to steadily decrease with the age of mosquito colonies but was recovered in refreshed strains and crosses between inbred strains therefore incriminating inbreeding costs. In contrast, testes size progressively increased with colony age, whilst accessory gland size quickly decreased in males from colonies of all ages. The lack of heterosis in response to crossing and strain refreshing in the latter two reproductive traits suggests selection for insectary conditions.

Conclusions

These results show that inbreeding and selection differentially affect reproductive traits in laboratory strains overtime and that heterotic ‘supermales’ could be used to rescue some male reproductive characteristics. Further experiments are needed to establish the exact relationship between sperm length, accessory gland and testes size, and male reproductive success in the laboratory and field settings.     

Decomposition and transfer of plant residue 14C between size and density fractions in soil

The aim of our study was to follow the transfer of ¹⁴C-labeled ryegrass between size and density fractions of soil organic matter in a sandy and a loam soil. Our hypotheses were a) that the applied ¹⁴C would be transferred from light and soluble fractions to intermediate and heavy macroorganic matter fractions (>150 m) and finally become stabilized in microaggregates (<150 m), and b) that the physical protection of ¹⁴C associated with microaggregates against decomposition would decrease with increasing saturation of the microaggregates with soil organic matter. Generally, the hypotheses were confirmed. Immediately after application most of the label was present in the soluble and light macroorganic matter fractions. Newly synthesized microbial biomass fed on the labeled components of the fractions. The amounts of ¹⁴C in the soluble and light macroorganic matter fractions decreased rapidly, while the amounts of ¹⁴C in the intermediate and heavy macroorganic matter fractions and in microaggregates remained more or less stable. At the end of the incubation most of the residual soil ¹⁴C was found in the microaggregates. In the sandy soil ¹⁴C was concentrated in the 20–150 m fraction, whereas in the loam a larger proportion was present in the <20 m fraction.The mineralization rates of ¹⁴C-labeled material were similar in the light intermediate and heavy fractions of macroorganic matter and in the microaggregates 0 and 180 days after the application of ¹⁴C-labeled ryegrass. In all fractions, ¹⁴C mineralized more rapidly than total C. The results indicate that considerable amounts of ¹⁴C must have transferred from the soluble and light macroorganic matter fractions and newly synthesized microbial biomass to the intermediate and heavy macroorganic matter fractions and the microaggregates, and that ¹⁴C was not yet physically protected against microbial degradation during the whole incubation period. The degree of physical protection of ¹⁴C against decomposition in the microaggregate fraction <20 m was negatively correlated with the degree of saturation of this particle size fraction with soil organic matter.     

Variation in mitochondrial DNA in a cline of allele frequencies and shell phenotype in the dog-whelk Nucella lapillus (L.)

Genetic constitution in the intertidal gastropod Nucella lapillus (L.) influences shell shape, growth rate and physiology. Clinal variation in these traits along a 5 km stretch of coastline in south Devon can be related to environmental variation in temperature and desiccation stress. We have examined mtDNA variation along this shore to investigate whether the cline represents primary or secondary contact. Two distinct mtDNA haplotypes were found which exhibit coincident step clines with karyotypic, allozymic and phenotypic variation and covary with the environmental pressures of temperature and desiccation. These results are interpreted in the context of the wider scale distribution of genetic and phenotypic variation in N. lapillus. It is suggested that the shore studied may represent one of a number of regions of secondary contact within a mosaic hybrid zone in N. lapillus , where coadapted phenotypic variation correlates with habitat and the position of the clines represents an environmental transition.     

Patterns of inflammation and the use of reversibility testing in smokers with airway complaints

Background

Although both smoking and respiratory complaints are very common, tools to improve diagnostic accuracy are scarce in primary care. This study aimed to reveal what inflammatory patterns prevail in clinically established diagnosis groups, and what factors are associated with eosinophilia.

Method

Induced sputum and blood plasma of 59 primary care patients with COPD (n = 17), asthma (n = 11), chronic bronchitis (CB, n = 14) and smokers with no respiratory complaints ('healthy smokers', n = 17) were collected, as well as lung function, smoking history and clinical work-up. Patterns of inflammatory markers per clinical diagnosis and factors associated with eosinophilia were analyzed by multiple regression analyses, the differences expressed in odds ratios (OR) with 95% confidence intervals.

Results

Multivariately, COPD was significantly associated with raised plasma-LBP (OR 1.2 [1.04–1.37]) and sTNF-R55 in sputum (OR 1.01 [1.001–1.01]), while HS expressed significantly lowered plasma-LBP (OR 0.8 [0.72–0.95]). Asthma was characterized by higher sputum eosinophilic counts (OR 1.3 [1.05–1.54]), while CB showed a significantly higher proportion of sputum lymphocytic counts (OR 1.5 [1.12–1.9]). Sputum eosinophilia was significantly associated with reversibility after adjusting for smoking, lung function, age, gender and allergy.

Conclusion

Patterns of inflammatory markers in a panel of blood plasma and sputum cells and mediators were discernable in clinical diagnosis groups of respiratory disease. COPD and so-called healthy smokers showed consistent opposite associations with plasma LBP, while chronic bronchitics showed relatively predominant lymphocytic inflammation compared to other diagnosis groups. Only sputum eosinophilia remained significantly associated with reversibility across the spectrum of respiratory disease in smokers with airway complaints.