Parthenogenomics: Insights on mutation rates and nucleotide diversity in parthenogenetic Panagrolaimus nematodes

Asexual reproduction is assumed to lead to the accumulation of deleterious mutations, and reduced heterozygosity due to the absence of recombination. Panagrolaimid nematode species display different modes of reproduction. Sexual reproduction with distinct males and females, asexual reproduction through parthenogenesis in the genus Panagrolaimus, and hermaphroditism in Propanagrolaimus. Here, we compared genomic features of free-living nematodes in populations and species isolated from geographically distant regions to study diversity, and genome-wide differentiation under different modes of reproduction. We firstly estimated genome-wide spontaneous mutation rates in a triploid parthenogenetic Panagrolaimus, and a diploid hermaphroditic Propanagrolaimus via long-term mutation accumulation lines. Secondly, we calculated population genetic parameters including nucleotide diversity, and fixation index (F ST) between populations of asexually and sexually reproducing nematodes. Thirdly, we used phylogenetic network methods on sexually and asexually reproducing Panagrolaimus populations to understand evolutionary relationships between them. The estimated mutation rate was slightly lower for the asexual population, as expected for taxa with this reproductive mode. Natural polyploid asexual populations revealed higher nucleotide diversity. Despite their common ancestor, a gene network revealed a high level of genetic differentiation among asexual populations. The elevated heterozygosity found in the triploid parthenogens could be explained by the third genome copy. Given their tendentially lower mutation rates it can be hypothesized that this is part of the mechanism to evade Muller's ratchet. Our findings in parthenogenetic triploid nematode populations seem to challenge common expectations of evolution under asexuality.

Introgression of a synthetic sex ratio distortion transgene into different genetic backgrounds of Anopheles coluzzii

The development of genetically modified mosquitoes (GMM) and their subsequent field release offers innovative approaches for vector control of malaria. A non-gene drive self-limiting male-bias Ag(PMB)1 strain has been developed in a 47-year-old laboratory G3 strain of Anopheles gambiae s.l. When Ag(PMB)1 males are crossed to wild-type females, expression of the endonuclease I-PpoI during spermatogenesis causes the meiotic cleavage of the X chromosome in sperm cells, leading to fertile offspring with a 95% male bias. However, World Health Organization states that the functionality of the transgene could differ when inserted in different genetic backgrounds of Anopheles coluzzii which is currently a predominant species in several West-African countries and thus a likely recipient for a potential release of self-limiting GMMs. In this study, we introgressed the transgene from the donor Ag(PMB)1 by six serial backcrosses into two recipient colonies of An. coluzzii that had been isolated in Mali and Burkina Faso. Scans of informative Single Nucleotide Polymorphism (SNP) markers and whole-genome sequencing analysis revealed a nearly complete introgression of chromosomes 3 and X, but a remarkable genomic divergence in a large region of chromosome 2 between the later backcrossed (BC6) transgenic offspring and the recipient paternal strains. These findings suggested to extend the backcrossing breeding strategy beyond BC6 generation and increasing the introgression efficiency of critical regions that have ecological and epidemiological implications through the targeted selection of specific markers. Disregarding differential introgression efficiency, we concluded that the phenotype of the sex ratio distorter is stable in the BC6 introgressed An. coluzzii strains.

Rapid adaptation to high temperatures in Chironomus riparius

Effects of seasonal or daily temperature variation on fitness and physiology of ectothermic organisms and their ways to cope with such variations have been widely studied. However, the way multivoltines organisms cope with temperature variations from one generation to the next is still not well understood. The aim of this study was to investigate whether the multivoltine midge Chironomus riparius Meigen (1803) responds mainly via acclimation as predicted by current theories or whether rapid genetic adaptation is involved. To investigate this issue, a common garden approach has been applied. A mix of larvae from five European populations was raised in the laboratory at three different pre-exposure temperatures (PET): 14, 20, and 26°C. After three and five generations, respectively, larvae were exposed to three treatment temperatures (TT): 14, 20, and 26°C. Mortality was monitored for the first 48 hr and after emergence. After three generations, significant mortality rate differences depended on an interaction of PET and TT. This finding supports the hypothesis that chironomids respond rapidly to climatic variation via adaptive mechanisms and to a lesser extent via phenotypic plasticity. The result of the experiment indicates that three generations were sufficient to adapt to warm temperature, decreasing the mortality rate, highlighting the potential for chironomids to rapidly respond to seasonally changing conditions.

Seroprevalence of hepatitis E virus in domestic pigs and wild boars in Switzerland

Hepatitis E is considered an emerging human viral disease in industrialized countries. Studies from Switzerland report a human seroprevalence of hepatitis E virus (HEV) of 2.6-21%, a range lower than in adjacent European countries. The aim of this study was to determine whether HEV seroprevalence in domestic pigs and wild boars is also lower in Switzerland and whether it is increasing and thus indicating that this zoonotic viral infection is emerging. Serum samples collected from 2,001 pigs in 2006 and 2011 and from 303 wild boars from 2008 to 2012 were analysed by ELISA for the presence of HEV-specific antibodies. Overall HEV seroprevalence was 58.1% in domestic pigs and 12.5% in wild boars. Prevalence in domestic pigs was significantly higher in 2006 than in 2011. In conclusion, HEV seroprevalence in domestic pigs and wild boars in Switzerland is comparable with the seroprevalence in other countries and not increasing. Therefore, prevalence of HEV in humans must be related to other factors than prevalence in pigs or wild boars.

Behandlung einer chronischen Kupfervergiftung mit oralem Ammoniummolybdat und Natriumsulfat bei Milchschafen

Four weeks after the introduction of a new ration, a herd of sheep in the Swiss midland area was affected by depression, anorexia, decreased milk production, anemia, hemoglobinuria and frequent recumbency. Seventeen ewes died within a few days. A diagnosis of chronic copper poisoning was based on the results of feed analysis, histopathological findings and the toxicological examination of liver tissue. The remaining sheep were treated with oral ammonium molybdate and sodium sulfate, which together provide an inexpensive alternative to the chelator D-penicillamine.This combination not only prevents further copper intake, but also supports its elimination from the hepatocellular storage compartments. Serum copper levels have been determined to monitor the mobilization of copper following this antidote therapy.

A Swiss case-control study to assess Neospora caninum-associated bovine abortions by PCR, histopathology and serology

Neospora caninum is one of the most frequent infectious organisms causing abortion in cattle worldwide. The present case-control study was designed to assess the importance of bovine neosporosis for causing abortion in Swiss cattle and to identify selected risk factors. Infection was primarily diagnosed by a N. caninum-specific PCR and serology, complemented with histopathology and immunohistochemistry. A total of 113 case and 113 corresponding control-farms were studied for 1.5 year. During this time period, 242 abortions were reported and referred for bacteriological, virological, parasitological and pathohistological examinations. N. caninum was detected by PCR in the brains of 21% of all aborted fetuses. Microscopic lesions indicative for cerebral protozoa infection were detected in 84% of PCR-positive fetal brains. Bovine viral diarrhea virus (BVDV) was demonstrated in 7% of the cases, and bacterial infections were detected in 4% of the abortions. One or more N. caninum-abortions occurred in 20% of the herds (41 case-farms and 3 control-farms). Serological examination of aborting mother cows revealed a significantly higher percentage of N. caninum-seropositive animals (44%) in comparison to the prevalence in a randomly selected population (12%). However, in eight cases (4% of all investigated abortions) seronegative cows aborted N. caninum PCR-positive fetuses, and in 50 cases the fetus remained negative although the respective mother cow was N. caninum-seropositive. Repetitive serological investigations (at a 3-12 months interval) of 3551 cows from case- and control-farms showed a decrease of the overall N. caninum-seroprevalence from 17 to 12%. Ninety out of 3008 seronegative animals were converted to N. caninum-seropositivity. Conversely, 212 out of 543 initially seropositive animals became seronegative for their second serum sample. The obtained data underlined the importance of N. caninum as a causative agent for abortion in Swiss cattle. Furthermore, PCR was confirmed to be a valuable diagnostic tool for the primary diagnosis of N. caninum in aborted fetuses. On the other hand, the value of serology appears to be hampered by the temporal instability of N. caninum antibody concentrations in adult cattle, including especially seronegativity of some individual animals. Thus, seronegativity in a mother cow or heifer does not exclude N. caninum-associated abortions.

Major carbohydrate antigen of Echinococcus multilocularis induces an immunoglobulin G response independent of alphabeta+ CD4+ T cells

Echinococcus multilocularis causes alveolar echinococcosis, one of the most lethal helminthic (accidental) infections in humans, as the life cycle predominantly includes wildlife rodents as intermediate hosts. The physical barrier between the proliferating parasitic metacestode and the host tissue is the acellular laminated layer (LL), which is characterized by its rich high-molecular-weight polysaccharide composition. Conversely to a crude protein-rich vesicular fluid antigen, a major carbohydrate antigen of the LL--the Em2(G11) antigen--did not stimulate murine T-cell proliferation in vitro. In fact, the persistent metacestode growth and antigenic stimulation induced a Th2 shift in vivo following conventional infection by intraperitoneal inoculation of 100 metacestode vesicles into C57/BL6 mice. Concurrently, the expression of Th1 cytokines (interleukin-2 and gamma interferon) remained persistently low until the late stage of chronic infection. In comparison to a recombinant proteinic II/3 antigen, the specific immunoglobulin G (IgG) response against the Em2(G11) antigen (including all IgG isotypes) maintained persistently low avidity. Furthermore, the Em2(G11) antigen induced a specific IgM and IgG response in T-cell-deficient athymic nude, TCRbeta(-/-), major histocompatibility complex class II (MHCII)(-/-)(CD4-deficient), and CD40(-/-) mice. The Em2(G11)-specific IgG synthesized in nude TCRbeta(-/-) and MHCII(-/-) mice was predominantly of the IgG3 and IgG2a isotypes and of the IgG3 and IgG2b isotypes in CD40(-/-) mice. This finding suggested that in vivo, the IgG response to major carbohydrate antigen Em2(G11) of E. multilocularis could take place independently of alphabeta+ CD4+ T cells and in the absence of CD40-CD40 ligand interactions; thus, the Em2(G11) antigen of the acellular LL represents a T-cell-independent antigen. Functionally, the encapsulating LL, and especially its major carbohydrate antigen, Em2(G11), seems to be one of the key factors in the parasite's survival strategy and acts by modulating the host immune response by virtue of its T-cell-independent nature.

[Molecular and immunodiagnostic studies of bovine neosporosis in Switzerland]

Cyst-forming coccidia may cause significant losses in livestock, primarily due to abortion, loss of young animals and neuromuscular diseases. Rather recently, Neospora caninum has been recognized as one of the major protozoal abortion-inducing parasites in cattle. The present study addressed the performance of different diagnostic tools (in vitro-cultivation; histology; immunohistochemistry; serology; PCR) suitable for the direct or indirect detection of N. caninum. By PCR, Neospora-DNA was detected in 24 brains (29%) from 83 bovine abortion, many of these brains were simultaneously characterized by histopathological findings typical for a protozoal, cerebral parasitosis. The diagnostic methods were furthermore assessed using samples of different tissues and body fluids from three experimentally Neospora-infected pregnant cows and their foetuses. The diaplacental passage of N. caninum to the foetus was successful in two of the three cases. In these two cases, PCR was positive for different foetal organs and, additionally, for the abomasal and amniotic fluid. The successfully infected cows developed anti-Neospora serum antibodies between 10 and 17 days post infection, foetuses remained serologically negative in all cases. The results obtained in the present study demonstrated the usefulness of PCR, complemented by serology, for the specific diagnosis of bovine neosporosis. Such tests may prove suitable to perform epidemiological investigations. Taken together, our data indicated that prenatal neosporosis may be an important cause of infectious bovine abortion in Switzerland.

Permanent implantation of a reinforced polytetrafluoroethylene vascular graft for treatment of artificial defects of the teat cistern mucosa in cows

OBJECTIVE

To evaluate use of a reinforced polytetrafluoroethylene vascular graft for treatment of an artificial defect of mucosa of the teat cistern in lactating cows.

DESIGN

Prospective study.

ANIMALS

9 clinically normal lactating dairy cows.

PROCEDURE

A 20-mm wide circumferential area of mucosa was sharply excised from the cistern of 1 teat on each cow 10 days after spontaneous calving, and the lesion was covered by a graft. After 14 days of passive milk drainage, routine milking was resumed. Follow-up examinations were performed during the next 2 lactation periods and included evaluation of wound healing, location and sonographic appearance of the implant, milk flow and yield, and somatic cell counts. Cows were slaughtered, and teats and mammary glands were examined microscopically.

RESULTS

Implants had partially to totally collapsed within 30 to 90 days. Milk flow was significantly increased by day 15 of the first lactation, but decreased significantly by day 300 of lactation 1. At the end of lactation 1, milk flow had ceased in 3 out of 7 quarters. Only 3 of 9 quarters drained through grafted teats were milkable at the end of the study. Somatic cell counts of these quarters were significantly increased in the first lactation period. At necropsy, 2 grafts were in the teat cistern, but only 1 was incorporated into the mucosa by connective tissue. The mucosa was thickened in all teats with grafts, and there was epithelial metaplasia and granulation tissue proliferation.

CLINICAL RELEVANCE

Use of a polytetrafluoroethylene graft can preserve patency in the first lactation period. However, the graft may not be sufficiently incorporated into the mucosa if routine machine milking is resumed 2 weeks after implantation. )

Detection and prevalence of Helicobacter infection in pet cats

The presence of spiral bacteria in the feline stomach has been recognized for over a century, but the identities and degrees of prevalence of such organisms in privately owned cats are still poorly documented. The aims of this study were (i) to adapt different diagnostic tools and evaluate their practicality for diagnosing feline gastric Helicobacter colonization, (ii) to determine the prevalence of gastric Helicobacter-like organisms in pet cats, (iii) to identify the feline species, and (iv) to correlate the presence of a Helicobacter infection with gastritis. Biopsy samples were taken gastroscopically from the antra and the corpora of clinically healthy pet cats. Helicobacter-like organisms were detected by Gram staining, Warthin-Starry staining, and rapid urease testing in biopsy specimens and by [13C]urea breath testing in 79, 77, 78, and 85% of cases, respectively. PCR analysis revealed that 78% of the cats (38 of 49) were infected by Helicobacter heilmannii; however, none of them was harboring Helicobacter pylori or Helicobacter felis. Culture was positive for one cat; the organism was identified as Helicobacter pametensis by dot blot DNA hybridization. By a combination of the detection methods, 91% of the pet cats were found to be Helicobacter positive. For 46 cats (79%) diagnostic tests were concordant. All cats showed mild to moderate gastritis in either the antrum or the corpus, regardless of the presence or density of gastric bacteria. In summary, pet cats are frequently colonized by H. heilmannii without a significant correlation between infection and degree of gastritis.

Preparation for emergency relief after biological warfare

Upon invitation by the World Health Organization during the Gulf War, a task force "Scorpio" independent from the nations involved in the armed conflict was formed whose task was to determine whether, which and to what extent biological warfare agents had been used. risk assessment concluded that anthrax and Clostridium botulinum toxin were the major risks. The 21 civilian experts had rapidly to decide on the doctrine of operation, to assemble material which could be used and to be immunized or protected otherwise against the potential risks. Biological warfare agents may be used anywhere any time, be it by terrorists or during open or clandestine hostilities. The general population cannot rely on the military to take care of civilian relief, thus international and national organizations may wish to establish similar task forces basing on the "Scorpio" model on a national or regional basis.

Borna disease in naturally infected cattle

Based on the immunohistochemical demonstration of viral antigen and on the histological brain lesions, Borna disease was diagnosed in a cow and a bull which had suffered from a severe, subacute progressive disorder of the central nervous system. Virus-specific antigen was characteristically localized in neurons, predominantly in the perikaryon and dendrites. In a serum sample available from one of the animals a Borna disease virus antibody titre of 1 in 80 was demonstrated. This is the first report of the natural disease in cattle.

Electron microscopy of the endometrium of camels in normal and some diseased conditions

Ultrastructure of the camel's endometrium in normal and diseased conditions, was studied using the electron microscope. The samples were obtained from 6 normal uteri and 10 uteri with inflammatory lesions. Three ovaries of the latter 10 uteri showed ovarian cysts. All the animals were non-pregnant. No cyclic changes were taken in consideration because the camel is an induced ovulator animal. The surface and the glandular epithelium of the normal uteri consisted of one layer of tall columnar cells, resting on an undulating membrane. The free borders of cells showed microvilli, motile cilia and zeiotic blebs. Desmosomes and gap junctions were seen as means of connections between the neighboring cells. The nuclei were large, oval and situated in the lower half of the cells. Two types of mitochondria were seen. One type was small, rounded and dilated, and the other was large and elongated. Many lipid droplets and scanty glycogen granules were common findings in the normal cells. Granulated bodies similar to those described in the epithelium of the human uterus and containing acid phosphatase were found. Many other cytoplasmic organelles and granules were seen. The endometrial stroma consisted mainly of stromal cells of irregular shape, and collagen fibres. The collagen fibres were present in amounts larger than many other species. In the diseased uteri, the changes in the epithelium consisted mainly of hyperplasia of the cells and marked increase of all cytoplasmic inclusions and vacuoles. There was also marked increase in the number of the crossing lymphocytes through the epithelial layer. The collagen fibres of the stroma increased in amount and the stromal cells became similar in shape to the fibroblasts. A large number of mast cells as well as other types of inflammatory cells infiltrated the stroma. Non-specific bacterial infections were detected on bacteriological examination of the inflamed uteri. Neither bacteria nor other microbial agents could be seen ultrastructurally. In an uterus associated with ovarian cysts, the microvilli of its epithelium showed marked changes in their shape and length.

Comparison of staple and Gambee techniques for enterotomy closure in the normal bovine jejunum

Two suturing techniques for closure of jejunal enterotomies--the stapling and the Gambee technique--were compared in 7 bulls. Stapling was less time consuming (P less than 0.0001) and reduced the overall duration of surgery by 15%. Furthermore, the lumen diameter was significantly less decreased in the stapled intestine at 8 weeks after surgery (P less than 0.05). The diameter of the intestine increased significantly between 8 and 13 weeks after the Gambee suture had been applied (P less than 0.05) and the difference in diameter between intestines sutured according to Gambee and the stapled intestines disappeared. The intestinal diameter did not change significantly between 13 and 18 weeks in both techniques. The application of Gambee sutures resulted in fewer adhesions (P less than 0.01) and less thickening of the intestinal wall (P less than 0.0001). The surgery did not seem to affect the performance of the bulls significantly.

Comparison of staple and suture techniques for partial typhlectomy in the cow: a prospective clinical study of 40 cases

Two techniques for partial typhlectomy were evaluated on 20 cows each suffering from dilatation/torsion of the cecum. In a preliminary study on two cows the suitability of a stainless steel staple pattern using two TA 90 cartridges of 4.8 mm and 3.5 mm staples respectively was examined and the technique standardized. In the main clinical study the stapling pattern (group I) was compared with a simple continuous full thickness appositional suture oversewn with a continuous Cushing suture (group II). The cartridges with the 4.8 mm staples were used in 7 clinical cases, with intestinal wall edema and the 3.5 mm staples were used in 13 cases. Arterial bleeding from the cecal stump occurred in 20 out of 22 cases (including the results of the preliminary study). The number of arteries that had to be ligated was statistically significantly higher (p less than 0.05) with the 4.8 mm staples than with the 3.5 mm staples. The additional ligation of bleeding vessels prolonged the surgical procedure. Seventeen out of 20 cows (85%) of each group were discharged from the clinic. The duration of the hospital stay was 6 days for both groups. Fourteen cows (70%) of each group were still alive upon inquiry. One cow of the stapling group was slaughtered because of a severe fibrinous peritonitis at the resection site. In the other 11 cows there was no evidence of a connection between the surgery and the slaughtering.

[Karl Kraus and psychoanalysis. A historical documentary study]

Through numerous quotations from Karl Kraus's journal Die Fackel the author points out that the traditional psychoanalytic picture (as transmitted by Jones) of Karl Kraus as one of Freud's fiercest adversaries is to be reconsidered.

[Therapy of chronic respiratory insufficiency]

In patients with chronic respiratory insufficiency the treatment of the underlying pulmonary disease is of primary importance. However, many patients often also need symptomatic management to recompensate or stabilize impaired pulmonary gas exchange. The most suitable measures for this purpose are (1) ventilatory support by periodic intermittent positive pressure breathing (IPPB), (2) long-term oxygen administration and (3) respiratory stimulant drugs. IPPB provides good results if restricted to well defined indications (paO2 below 60 mm Hg, paCO2 above 45 mm Hg, forced expiratory volume [FEV1] below 40% of vital capacity or below 1000 ml). Long-term domiciliary oxygen therapy for at least 15 h daily prevents the early decompensation of cor pulmonale and improves physical performance. With the introduction of industrial O2-concentrators this form of therapy becomes more practicable and less expensive compared with the conventional method delivering compressed oxygen. However, the indication should be confined to patients with chronic and severe hypoxemia (paO2 below 50 mm Hg), pulmonary hypertension and secondary polycythemia. Respiratory stimulant drugs are useful in protecting patients from central respiratory depression during oxygen breathing. Aminophylline seems to be the most suitable drug simultaneously acting as a bronchodilator and vasodilator in the pulmonary circulation. To achieve a potent stimulant effect, serum theophylline levels above 10 microgram/ml through repeated intravenous administrations of aminophylline are required. Individual differences in the pharmacokinetic action of theophylline may sometimes need drug monitoring to prevent toxic side effects.