Ovarian suppression by DDT and resistance in the house fly (Musca domestica L.)

Suggested by immunological theory, this study was initiated to test an hypothesis on physiological induction of resistance to insecticides. The hypothesis was proved untenable in the test system, but from the experimentation emerged evidence for a chronically toxic action of DDT expressed in reduced fecundity in female house flies fed sub-lethal amounts of this insecticide. This action can be a strong selective force, promptly revealing tolerant genotypes in the population. The usual selection for resistance does not necessarily also select for ovarian tolerance; even DDT-resistant flies can show ovarian suppression when fed DDT-contaminated food.It is possible that the route of administration of the DDT is important as the means by which the physiologic events described can occur as a chronic intoxication without the usual acutely toxic effects.

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Zusammenfassung Der vorliegenden Arbeit liegt die Frage zugrunde, ob Stubenfliegen, die bereits im Embryonalstadium DDT ausgesetzt werden, diesem gegenüber Resistenz erwerben können. Fütterung erwachsener Stubenfliegen mit C¹⁴-markiertem DDT führt zu dessen Inkorporation schon in den Eiern der Ovarien; die Inkorporation konnte in den schlüpfenden Larven weite verfolgt werden.In Versuchen, in denen je Versuchsglied stets nur die Nachkommenschaft eines Elternpaares (ein Eigelege) verwendet wurde, spalteten sich zwei gleichgrossen Populationen heraus: Während die eine die gleiche Anfälligkeit gegenüber DDT (0,12 g/Fliege) aufwies wie die Nachkommenschaft DDT-ungefütterter Eltern, war die andere Population dieser Dosis gegenüber tolerant.Die Ergebnisse von weiteren Versuchen belegen eindeutig, dass die durch DDT-Behandlung im Embryonalstadium hervorgerufene DDT-Toleranz primär nicht physiologisch bedingt ist, sondern primär auf genetischen Ursachen beruhen muss: Wurden DDT-gefütterte Weibchen mit DDT-anfälligen bzw. DDT-resistenten Männchen, denen kein DDT zum Futter gemischt worden war, gekreuzt, so war die gesamte Nachkommenschaft DDT-anfällig bzw. DDT-resistent.Es ergibt sich die Frage, welches Prinzip diese genotypisch verankerte Toleranz phänotypisch in Erscheinung treten lässt. Die in den Versuchen verwendeten DDT-Dosen waren ohne wesentlichen Einfluss auf den Eischlupf und die Mortalität von Larven und Fliegen. Dagegen senkte die Fütterung deutlich die Anzahl der zur Eiablage befähigten Weibchen und die Anzahl der von den anderen Weibchen gelegten Eier.

     

Differences in synovial fluid cytokine levels but not in synovial tissue cell infiltrate between anti-citrullinated peptide/protein antibody-positive and –negative rheumatoid arthritis patients

Introduction

Comparative data on synovial cell infiltrate and cytokine levels in anti citrullinated peptide/protein antibody (ACPA)-positive and ACPA negative rheumatoid arthritis (RA) patients are scarce. Our aim was to analyze synovial cell infiltrate and synovial fluid (SF) levels of cytokines in patients with RA according to the presence or absence of ACPA in serum.

Methods

A cross-sectional study in a single center including consecutive RA patients was performed. Patients were defined as ''ACPA negative'' if serum was negative to two different ACPAs [second generation commercial anti-cyclic citrullinated peptide antibodies (CCP2) and chimeric fibrin/filaggrin citrullinated antibodies]. Parallel synovial tissue (ST) biopsies and SF were obtained by knee arthroscopy. Synovial cell infiltrate and endothelial cells were analyzed by immunohistochemistry and SF levels of Th1, Th2, Th17 and pro-inflammatory cytokines by Quantibody(R) Human Array.

Results

A total of 83 patients underwent arthroscopy, with a mean age of 55.9 ± 12 years, and mean disease duration of 45 months (interquartile range, IQR 10.8 to 122). 62% were female and 77% were ACPA positive. No significant differences were found in clinical variables, acute phase reactants, synovial cell infiltrate or lymphoid neogenesis (LN) between ACPA positive and negative patients. However ACPA positive patients had significantly higher levels of IL-1β, IL-10, IL-17 F and CC chemokine ligand 20 (CCL-20) than ACPA negative patients.

Conclusions

In our cohort of patients with RA no significant differences were found in synovial cell infiltrate or synovial LN according to ACPA status. However, ACPA positive patients had higher levels of T-cell derived and pro-inflammatory cytokines than ACPA negative patients. As systemic and local inflammation was similar in the two groups, these findings support a distinct synovial physiopathology.     

Mass analysis by scanning transmission electron microscopy and electron diffraction validate predictions of stacked beta-solenoid model of HET-s prion fibrils

Fungal prions are infectious filamentous polymers of proteins that are soluble in uninfected cells. In its prion form, the HET-s protein of Podospora anserina participates in a fungal self/non-self recognition phenomenon called heterokaryon incompatibility. Like other prion proteins, HET-s has a so-called "prion domain" (its C-terminal region, HET-s-(218-289)) that is responsible for induction and propagation of the prion in vivo and for fibril formation in vitro. Prion fibrils are thought to have amyloid backbones of polymerized prion domains. A relatively detailed model has been proposed for prion domain fibrils of HET-s based on a variety of experimental constraints (Ritter, C., Maddelein, M. L., Siemer, A. B., Luhrs, T., Ernst, M., Meier, B. H., Saupe, S. J., and Riek, R. (2005) Nature 435, 844-848). To test specific predictions of this model, which envisages axial stacking of beta-solenoids with two coils per subunit, we examined fibrils by electron microscopy. Electron diffraction gave a prominent meridional reflection at (0.47 nm)(-1), indicative of cross-beta structure, as predicted. STEM (scanning transmission electron microscopy) mass-per-unit-length measurements yielded 1.02 +/- 0.16 subunits per 0.94 nm, in agreement with the model prediction (1 subunit per 0.94 nm). This is half the packing density of approximately 1 subunit per 0.47 nm previously obtained for fibrils of the yeast prion proteins, Ure2p and Sup35p, whence it follows that the respective amyloid architectures are basically different.     

Influence of lactation parameters on the N-glycosylation of recombinant human C1 inhibitor isolated from the milk of transgenic rabbits

The large-scale production of recombinant biopharmaceutical glycoproteins in the milk of transgenic animals is becoming more widespread. However, in comparison with bacterial, plant cell, or cell culture production systems, little is known about the glycosylation machinery of the mammary gland, and hence on the glycosylation of recombinant glycoproteins produced in transgenic animals. Here the influence is presented of several lactation parameters on the N-glycosylation of recombinant C1 inhibitor (rhC1INH), a human serum glycoprotein, expressed in the milk of transgenic rabbits. Enzymatically released N-glycans of series of rhC1INH samples were fluorescently labeled and fractionated by HPLC. The major N-glycan structures on rhC1INH of pooled rabbit milk were similar to those on native human C1 inhibitor and recombinant human C1 inhibitor produced in transgenic mouse milk, with only the degree of sialylation and core fucosylation being lower. Analyses of individual animals furthermore showed slight interindividual differences; a decrease in the extent of sialylation, core fucosylation, and oligomannose-type glycosylation with the progress of lactation; and a positive correlation between expression level and oligomannose-type N-glycan content. However, when large quantities of rhC1INH were isolated for preclinical and clinical studies, highly consistent N-linked glycan profiles and monosaccharide compositions were found.     

Non-Invasive monitoring of diaphragmatic timing by means of surface contact sensors: An experimental study in dogs

Background

The predictive role of many cytokines has not been well defined in Acute Respiratory Distress Syndrome (ARDS).

Methods

We measured prospectively IL-4, IL-6, IL-6 receptor, IL-8, and IL-10, in the serum and bronchoalveolar lavage fluid (BALF) in 59 patients who were admitted to ICU in order to identify predictive factors for the course and outcome of ARDS. The patients were divided into three groups: those fulfilling the criteria for ARDS (n = 20, group A), those at risk for ARDS and developed ARDS within 48 hours (n = 12, group B), and those at risk for ARDS but never developed ARDS (n = 27, group C).

Results

An excellent negative predictive value for ARDS development was found for IL-6 in BALF and serum (100% and 95%, respectively). IL-8 in BALF and IL-8 and IL-10 serum levels were higher in non-survivors in all studied groups, and were associated with a high negative predictive value. A significant correlation was found between IL-8 and APACHE score (r = 0.60, p < 0.0001). Similarly, IL-6 and IL-6r were highly correlated with PaO2/FiO2 (r = -0.27, p < 0.05 and r = -0.55, p < 0.0001, respectively).

Conclusions

BALF and serum levels of the studied cytokines on admission may provide valuable information for ARDS development in patients at risk, and outcome in patients either in ARDS or in at risk for ARDS.     

Diversity of Saccharomyces strains in wine fermentations: analysis for two consecutive years

An ecological study of Saccharomyces cerevisiae strains in spontaneous alcoholic fermentation has been conducted in the same winery for two consecutive years (1994 and 1995). Yeast cells were identified and characterized using mitochondrial DNA restriction analysis. Although a great diversity of wild strains was observed, a sequential substitution of S. cerevisiae strains during the different phases of fermentation was detected. Furthermore, the most frequent strains were encountered in both years, and the dynamic populations were not influenced by climatic conditions. Finally, the Rsa I restriction enzyme produced a species-specific pattern which allowed the identification of all the isolates as S. cerevisiae .     

Miniature Swine as a Clinically Relevant Model of Graft-Versus-Host Disease

Miniature swine provide a preclinical model of hematopoietic cell transplantation (HCT) for studies of graft-versus-host disease. HCT between MHC-matched or ‑mismatched pigs can be performed to mimic clinical scenarios with outcomes that closely resemble those observed in human HCT recipients. With myeloablative conditioning, HCT across MHC barriers is typically fatal, with pigs developing severe (grade III or IV) GVHD involving the gastrointestinal tract, liver, and skin. Unlike rodent models, miniature swine provide an opportunity to perform extended longitudinal studies on individual animals, because multiple tissue biopsies can be harvested without the need for euthanasia. In addition, we have developed a swine GVHD scoring system that parallels that used in the human clinical setting. Given the similarities of GVHD in pigs and humans, we hope that the use of this scoring system facilitates clinical and scientific discourse between the laboratory and the clinic. We anticipate that results of swine studies will support the development of new strategies to improve the identification and treatment of GVHD in clinical HCT scenarios.Abbreviations: BMT, bone marrow transplantation; GVHD, graft-versus-host disease; GVL, graft-versus-leukemia; HCT, hematopoietic cell transplantation; TBI, total-body irradiation     

What Makes a Protein Sequence a Prion?

Typical amyloid diseases such as Alzheimer''s and Parkinson''s were thought to exclusively result from de novo aggregation, but recently it was shown that amyloids formed in one cell can cross-seed aggregation in other cells, following a prion-like mechanism. Despite the large experimental effort devoted to understanding the phenomenon of prion transmissibility, it is still poorly understood how this property is encoded in the primary sequence. In many cases, prion structural conversion is driven by the presence of relatively large glutamine/asparagine (Q/N) enriched segments. Several studies suggest that it is the amino acid composition of these regions rather than their specific sequence that accounts for their priogenicity. However, our analysis indicates that it is instead the presence and potency of specific short amyloid-prone sequences that occur within intrinsically disordered Q/N-rich regions that determine their prion behaviour, modulated by the structural and compositional context. This provides a basis for the accurate identification and evaluation of prion candidate sequences in proteomes in the context of a unified framework for amyloid formation and prion propagation.     

Cell dynamic adhesion and elastic properties probed with cylindrical atomic force microscopy cantilever tips

Cell adhesion is required for essential biological functions such as migration, tissue formation and wound healing, and it is mediated by individual molecules that bind specifically to ligands on other cells or on the extracellular matrix. Atomic force microscopy (AFM) has been successfully used to measure cell adhesion at both single molecule and whole cell levels. However, the measurement of inherent cell adhesion properties requires a constant cell-probe contact area during indentation, a requirement which is not fulfilled in common pyramidal or spherical AFM tips. We developed a procedure using focused ion beam (FIB) technology by which we modified silicon pyramidal AFM cantilever tips to obtain flat-ended cylindrical tips with a constant and known area of contact. The tips were validated on elastic gels and living cells. Cylindrical tips showed a fairly linear force-indentation behaviour on both gels and cells for indentations >200 nm. Cylindrical tips coated with ligands were used to quantify inherent dynamic cell adhesion and elastic properties. Force, work of adhesion and elasticity showed a marked dynamic response. In contrast, the deformation applied to the cells before rupture was fairly constant within the probed dynamic range. Taken together, these results suggest that the dynamic adhesion strength is counterbalanced by the dynamic elastic response to keep a constant cell deformation regardless of the applied pulling rate.     

Understanding the epidemiological factors that intensify the incidence of maize rough dwarf disease in Spain

Currently the dominant limiting factor to maize production in Spain is caused by Maize rough dwarf virus (MRDV). This study aimed to evaluate the epidemiology factors involved in the increased incidence of MRD disease in Spain. We examined the maize planthopper dynamics and MRDV incidence throughout two maize growing seasons in six locations using a set of eight maize varieties: four Bt‐varieties (BT‐var) and their isogenic counterparts (NBT‐var). Our results indicate that MRDV incidence is greatly influenced by the first colonisation of maize by Laodelphax striatellus but not by Metadelphax propinqua and by the susceptibility of the maize varieties. No significant differences were observed between the BT‐var and NBT‐var, although BT‐var exhibited 1% less MRDV infection than NBT‐var. Cultivated wheat and Lolium perenne were found for the first time to be natural hosts of MRDV. However, wheat does not seem to be a preferred host for the development of L. striatellus. Partial sequencing of genome segments S1–S9 and full sequencing of segment S10 revealed that the Spanish MRDV isolate shares nucleotide identities ranging from 93% to 97% with the available sequences of segments S7–S10 of the Italian MRDV isolate. The highest nucleotide identities with other fijiviruses were observed with Rice black‐streaked dwarf virus. Molecular variability analysis of MRDV isolates collected over a ten years period showed high nucleotide (>97%) and amino sequence identities (>99%) on segment S10, suggesting a low temporal variability.