Evidence for distinct polygenic regulation of antibody responses to some unrelated antigens in lines of mice selected for high or low antibody responses to somatic antigen of Salmonella

The effect of the selective breeding of mice for high or low antibody production to complex immunogens is largely nonspecific, since it modifies the responsiveness of high (H) and low (L) lines to many antigens unrelated to the selection antigen. However, the nonspecific effect of the polygenic control operating in these lines is not a general feature. For example, the group of genes in selection IV, carried out for responsiveness to somatic antigen of Salmonella, does not modify the responses to sheep erythrocytes (SE). Despite equivalent responses in H and L mice of selection IV, a large variability was found in individual responses of F₂ interline hybrids, which demonstrates the presence of alleles with high or low effect on responses to SE. A selective breeding (Selection IV-A) was therefore initiated from this F₂ population for responsiveness to SE. A progressive interline divergence occurred during the first seven generations of selection; the interline separation was due to polygenic regulation (about four independent loci from a preliminary estimate).Equivalent responses to the s antigen of Salmonella are observed in the two lines. This constitutes additional evidence for distinct polygenic regulation of responses to SE and to somatic antigen. Moreover, the pattern of responses to several unrelated antigens (nonspecific effect) also differs between Selections IV and IV-A.Abbreviations H high responder lines - L low responder lines - s somatic antigen of Salmonella - f flagellar antigen of Salmonella - R response to selection - S selection differential - F₀ foundation population - h² heritability (realized) - RGG rabbit gamma globulin - CE chicken erythrocyte - HE human erythrocyte - PE pigeon erythrocyte - SE sheep erythrocyte     

In Vitro Evaluation of a Soluble Leishmania Promastigote Surface Antigen as a Potential Vaccine Candidate against Human Leishmaniasis

PSA (Promastigote Surface Antigen) belongs to a family of membrane-bound and secreted proteins present in several Leishmania (L.) species. PSA is recognized by human Th1 cells and provides a high degree of protection in vaccinated mice. We evaluated humoral and cellular immune responses induced by a L. amazonensis PSA protein (LaPSA-38S) produced in a L. tarentolae expression system. This was done in individuals cured of cutaneous leishmaniasis due to L. major (CCLm) or L. braziliensis (CCLb) or visceral leishmaniasis due to L. donovani (CVLd) and in healthy individuals. Healthy individuals were subdivided into immune (HHR-Lm and HHR-Li: Healthy High Responders living in an endemic area for L. major or L. infantum infection) or non immune/naive individuals (HLR: Healthy Low Responders), depending on whether they produce high or low levels of IFN-γ in response to Leishmania soluble antigen. Low levels of total IgG antibodies to LaPSA-38S were detected in sera from the studied groups. Interestingly, LaPSA-38S induced specific and significant levels of IFN-γ, granzyme B and IL-10 in CCLm, HHR-Lm and HHR-Li groups, with HHR-Li group producing TNF-α in more. No significant cytokine response was observed in individuals immune to L. braziliensis or L. donovani infection. Phenotypic analysis showed a significant increase in CD4+ T cells producing IFN-γ after LaPSA-38S stimulation, in CCLm. A high positive correlation was observed between the percentage of IFN-γ-producing CD4+ T cells and the released IFN-γ. We showed that the LaPSA-38S protein was able to induce a mixed Th1 and Th2/Treg cytokine response in individuals with immunity to L. major or L. infantum infection indicating that it may be exploited as a vaccine candidate. We also showed, to our knowledge for the first time, the capacity of Leishmania PSA protein to induce granzyme B production in humans with immunity to L. major and L. infantum infection.     

Improvement of Photorhabdus temperata bioinsecticides production in low‐cost media through adequate fermentation technology

To develop a cost effective process for bioinsecticides production by Photorhabdus temperata, dissolved oxygen (DO) requirements were investigated in both the complex and the optimized media using diluted seawater as a source of micronutrients. By varying DO concentrations, tolerance to hydrogen peroxide was shown to be medium dependant. Indeed, P. temperata cells grown in the complex medium, exhibited higher tolerance than cells grown in the optimized medium (OM). Tolerance to H₂O₂ was shown to be related to intracellular reactive oxygen species (ROS) accumulation during soya bean meal or glucose assimilation, as shown by flow cytometry analysis. To avoid oxidative stress damages in P. temperata cells cultured in the OM, DO concentration should be constant 50% saturation throughout the fermentation. However, a DO‐shift control strategy was demonstrated to be beneficial for P. temperata bioinsecticide production in the complex medium. By using such a strategy biomass, culturability, and oral toxicity reached 16.5 × 10⁸, 1.15 × 10⁸ cells/mL and 64.2%, respectively, thus was 16.19, 26.37, and 12.2% more than in the cultures carried out at a constant 50% saturation. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012     

<Emphasis Type="Italic">Slc11a1</Emphasis> (<Emphasis Type="Italic">Nramp1</Emphasis>) alleles interact with acute inflammation loci to modulate wound-healing traits in mice

Lines of mice were obtained by selective breeding for maximum (AIRmax) or minimum (AIRmin) acute inflammation. They present distinct neutrophil influx and show frequency disequilibrium of the solute carrier family 11a member 1 (Slc11a1) alleles. This gene is involved in ion transport at the endosomes within macrophages and neutrophils, interfering in their activation. Homozygous AIRmax and AIRmin sublines for the Slc11a1 gene were produced to examine the interaction of this gene with the acute inflammatory loci. The present work investigated wound-healing traits in AIRmax and AIRmin mice, in F₁ and F₂ intercrosses, and in Slc11a1 sublines. Two-millimeter ear punches were made in the mice and hole closure was measured during 40 days. AIRmax mice demonstrated significant tissue repair while AIRmin mice did not. Significant differences between the responses of male and female mice were also observed. Wound-healing traits demonstrated a correlation with neutrophil influx in F₂ populations. AIRmax ^SS showed higher ear-wound closure than AIRmax ^RR mice, suggesting that the Slc11a1 S allele favored ear tissue repair. QTL analysis has detected two inflammatory loci modulating ear wound healing on chromosomes 1 and 14. These results suggest the involvement of the acute inflammation modifier QTL in the wound-healing phenotype.     

Genetic diversity of Colletotrichum gloeosporioides species complex associated with Citrus wither‐tip of twigs in Tunisia using microsatellite markers

Anthracnose Citrus disease has been associated with several symptoms worldwide and it is recently compromising Citrus production in the Mediterranean area. Four species complexes are mainly involved: Colletotrichum boninense, C. acutatum, C. gloeosporioides and C. truncatum. In this study, we investigated the genetic diversity of Colletotrichum spp. in Tunisia associated with wither‐tip of twigs on Citrus. Specific primers ITS4‐CgInt allowed the identification of C. gloeosporioides species complex in all the 54 isolates, sampled from three regions and four Citrus species. Overall, our genotypic analysis using 10 SSR markers showed a moderate diversity level in Tunisian C. gloeosporioides population and highlighted that C. gloeosporioides reproduce mainly clonally. In addition, heterothallic isolates were present in our population, suggesting that the pathogen population may undergo parasexual recombinations. The highest genetic diversity in C. gloeosporioides was recorded in Nabeul and on orange, which likely constitutes the area and the host of origin for the Citrus anthracnose disease in Tunisia. In addition, no population subdivision was detected at the geographic, host species or cultivars’ origin levels. However, our study identified two genetic subpopulations and indicated a rapid C. gloeosporioides population change at temporal scale that should be further examined over several consecutive growing seasons in order to understand its population dynamics.     

Life history of the predatory mite Phytoseius plumifer and the effect of nutrition on its biology (Acarina: Phytoseiidae)

Phytoseius plumifer could develop and reproduce when fed on the different stages of the red spider mite T. cinnabarinus. The female immature stages lasted for an average of 4.8, 3.8 and 4.5 days respectively when fed on eggs, immatures and adults of the prey at an average temperature of 29.5±1°C. The average number of deposited eggs per female was significantly greater when it fed on immatures and adults (about 45 eggs) than when it fed on prey eggs (about 29 eggs). During the whole life-span the predator female fed on an average of 969 eggs or 438 immatures or 346 adults, of these more than 93% were consumed during the adult stage. Males lived for shorter time and consumed fewer prey than females.The predator could develop and reproduce successfully on date-palm pollen but at a slower rate. On this diet the immature stages lasted 10.5 days and female laid an average of 16.6 eggs. On hollyhock and cotton pollen, or sweet potato leaves, larvae failed to develop to adults.

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Zusammenfassung Phytoseius plumifer konnte sich entwickeln und fortpflanzen, wenn er mit verschiedenen Stadien der Roten Spinnmilbe, Tetranychus cinnabarinus, gefüttert wurde. Die Entwicklungs-stadien des Weibchens dauerten bei einer Mitteltemperatur von 29,5±1° je nach Fütterung mit Eiern, Jungtieren oder Adulten der Beute durchschnittlich 4,8, 3,8 oder 4,5 Tage. Die durchschnittliche Anzahl von einem Weibchen abgelegter Eier war signifikant größer, wenn sie mit Larven und Erwachsenen gefüttert wurden (etwa 45 Eier), als wenn sie mit Eiern der Beutetiere ernährt wurden (etwa 29 Eier). Während der Gesamtlebensdauer verzehrte ein Raubmilben-Weibchen im Durchschnitt 969 Eier oder 438 unreife oder 346 erwachsene Beutetiere, von denen mehr als 93% während des Imaginalstadiums verbraucht wurden. Männchen lebten kürzere Zeit und vertilgten weniger Beute als die Weibchen.Der Räuber konnte sich an Dattelpalmen-Pollen entwickeln und erfolgreich fortpflanzen, jedoch mit einer geringeren Rate. Bei dieser Ernährung dauerte die Entwicklung bis zur Imago 10,5 Tage und ein Weibchen legte im Durchschnitt 16,6 Eier. Mit Stechpalmen- und Baumwoll-Pollen oder an Süßkartoffel-Blättern entwickelten sich die Larven nicht bis zur Imago.

     

Enzyme-Linked Immunofiltration Assay To Estimate Attachment of Thiobacilli to Pyrite

An enzyme-linked immunofiltration assay (ELIFA) has been developed in order to estimate directly and specifically Thiobacillus ferrooxidans attachment on sulfide minerals. This method derives from the enzyme-linked immunosorbent assay but is performed on filtration membranes which allow the retention of mineral particles for a subsequent immunoenzymatic reaction in microtiter plates. The polyclonal antiserum used in this study was raised against T. ferrooxidans DSM 583 and recognized cell surface antigens present on bacteria belonging to the genus Thiobacillus. This antiserum and the ELIFA allowed the direct quantification of attached bacteria with high sensitivity (10⁴ bacteria were detected per well of the microtiter plate). The mean value of bacterial attachment has been estimated to be about 10⁵ bacteria mg⁻¹ of pyrite at a particle size of 56 to 65 μm. The geometric coverage ratio of pyrite by T. ferrooxidans ranged from 0.25 to 2.25%. This suggests an attachment of T. ferrooxidans on the pyrite surface to well-defined limited sites with specific electrochemical or surface properties. ELIFA was shown to be compatible with the measurement of variable levels of adhesion. Therefore, this method may be used to establish adhesion isotherms of T. ferrooxidans on various sulfide minerals exhibiting different physicochemical properties in order to understand the mechanisms of bacterial interaction with mineral surfaces.     

Storage and reproductive strategy of the carpet-shell clam,Ruditapes decussatus in the Gulf of Gabès (Tunisia)

In this study, the variations of glycogen concentrations in Ruditapes decussatus from Sfax coasts (Tunisia) were described in relation to the reproductive cycle. Separate analyses were made of gonad, adductor muscle and ‘remainder’. The timing of gametogenic development and spawning was evaluated using qualitative histology associated with image analysis including (1) the estimation of the gonadal occupation index (GOI), (2) surface area occupied by reserve tissues and (3) variation in oocyte diameter. The reproductive cycle of R. decussatus exhibited partial asynchronization between sexes, the major difference being observed in the duration of the spawning period. Contrary to previous studies, we observed continuous partial spawning (e.g. 50% of ripe oocytes still subsisted at the partial spawning stage). During the gametogenic cycle, GOI varied significantly in males and in females. Most oocytes were ripe and ready to spawn when their diameter reached or exceeded 45?µm. The expansion of gonad was inversely proportional to the development of the foot tissue. Glycogen concentration showed significant temporal variations between tissues, indicating the clear differentiation in energy storage between the clam organs.