37 research outputs found
Clone- and age-dependent toxicity of a glyphosate commercial formulation and its active ingredient in Daphnia magna.
This article is part of Marek Cuhra's doctoral thesis which is available in Munin at http://hdl.handle.net/10037/7869Low levels of glyphosate based herbicide
induced significant negative effects on the aquatic invertebrate
Daphnia magna. Glyphosate herbicides such as brands
of Roundup, are known to be toxic to daphnids. However,
published findings on acute toxicity show significant discrepancies
and variation across several orders of magnitude.
To test the acute effects of both glyphosate and a commercial
formulation of Roundup (hereafter Roundup), we conducted
a series of exposure experiments with different clones and
age-classes of D. magna. The results demonstrated EC50 (48)
values in the low ppm-range for Roundup as well as for the
active ingredient (a.i.) isopropylamine salt of glyphosate
(glyphosate IPA) alone. Roundup showed slightly lower
acute toxicity than glyphosate IPA alone, i.e. EC50 values of
3.7–10.6 mg a.i./l, as compared to 1.4–7.2 mg a.i./l for
glyphosate IPA. However, in chronic toxicity tests spanning
the whole life-cycle, Roundup was more toxic. D. magna
was exposed to sublethal nominal concentrations of 0.05,
0.15, 0.45, 1.35 and 4.05 mg a.i./l for 55 days. Significant
reduction of juvenile size was observed even in the lowest
test concentrations of 0.05 mg a.i./l, for both glyphosate and
Roundup. At 0.45 mg a.i./l, growth, fecundity and abortion
rate was affected, but only in animals exposed to Roundup.
At 1.35 and 4.05 mg a.i./l of both glyphosate and Roundup,
significant negative effects were seen on most tested
parameters, including mortality. D. magna was adversely
affected by a near 100 % abortion rate of eggs and
embryonic stages at 1.35 mg a.i./l of Roundup. The results
indicate that aquatic invertebrate ecology can be adversely
affected by relevant ambient concentrations of this major
herbicide. We conclude that glyphosate and Roundup toxicity
to aquatic invertebrates have been underestimated and
that current European Commission and US EPA toxicity
classification of these chemicals need to be revised
In vitro host range, multiplication and virion forms of recombinant viruses obtained from co-infection in vitro with a vaccinia-vectored influenza vaccine and a naturally occurring cowpox virus isolate
Background: Poxvirus-vectored vaccines against infectious diseases and cancer are currently under
development. We hypothesized that the extensive use of poxvirus-vectored vaccine in future might result
in co-infection and recombination between the vaccine virus and naturally occurring poxviruses, resulting
in hybrid viruses with unpredictable characteristics. Previously, we confirmed that co-infecting in vitro a
Modified vaccinia virus Ankara (MVA) strain engineered to express influenza virus haemagglutinin (HA) and
nucleoprotein (NP) genes with a naturally occurring cowpox virus (CPXV-NOH1) resulted in recombinant
progeny viruses (H Hansen, MI Okeke, Ø Nilssen, T Traavik, Vaccine 23: 499–506, 2004). In this study we
analyzed the biological properties of parental and progeny hybrid viruses.
Results: Five CPXV/MVA progeny viruses were isolated based on plaque phenotype and the expression
of influenza virus HA protein. Progeny hybrid viruses displayed in vitro cell line tropism of CPXV-NOH1,
but not that of MVA. The HA transgene or its expression was lost on serial passage of transgenic viruses
and the speed at which HA expression was lost varied with cell lines. The HA transgene in the progeny
viruses or its expression was stable in African Green Monkey derived Vero cells but became unstable in
rat derived IEC-6 cells. Hybrid viruses lacking the HA transgene have higher levels of virus multiplication
in mammalian cell lines and produced more enveloped virions than the transgene positive progenitor virus
strain. Analysis of the subcellular localization of the transgenic HA protein showed that neither virus strain
nor cell line have effect on the subcellular targets of the HA protein. The influenza virus HA protein was
targeted to enveloped virions, plasma membrane, Golgi apparatus and cytoplasmic vesicles.
Conclusion: Our results suggest that homologous recombination between poxvirus-vectored vaccine
and naturally circulating poxviruses, genetic instability of the transgene, accumulation of non-transgene
expressing vectors or hybrid virus progenies, as well as cell line/type specific selection against the
transgene are potential complications that may result if poxvirus vectored vaccines are extensively used
in animals and man
Demographic responses of Daphnia magna fed transgenic Bt-maize
The food/feed quality of a variety of genetically modified (GM) maize expressing Cry1Ab Bt-toxin was tested over the life-cycle of Daphnia magna, an arthropod commonly used as model organism in ecotoxicological studies. Demographic responses were compared between animals fed GM or unmodified (UM) near isogenic maize, with and without the addition of predator smell. Age-specific data on survival and birth rates were integrated and analysed using life tables and Leslie matrices. Survival, fecundity and population growth rate (PGR) data generally disfavoured transgenic Bt-maize as feed for D. magna compared to animals fed the unmodified (UM) near isogenic line of maize. Decomposition of age-specific effects revealed that the most important contributions to a reduced PGR in the GM-fed group came from both fecundity and survival differences early in life. We conclude that juvenile and young adult stages are the most sensitive experimental units and should be prioritized in future research. These stages are often omitted in toxicological/ecotoxicological studies and in feeding trials
An investigation of horizontal transfer of feed introduced DNA to the aerobic microbiota of the gastrointestinal tract of rats
Background: Horizontal gene transfer through natural transformation of members of the microbiota of the lower gastrointestinal tract (GIT) of mammals has not yet been described. Insufficient DNA sequence similarity for homologous recombination to occur has been identified as the major barrier to interspecies transfer of chromosomal DNA in bacteria. In this study we determined if regions of high DNA similarity between the genomes of the indigenous bacteria in the GIT of rats and feed introduced DNA could lead to homologous recombination and acquisition of antibiotic resistance genes.
Results: Plasmid DNA with two resistance genes (nptII and aadA) and regions of high DNA similarity to 16S rRNA and 23S rRNA genes present in a broad range of bacterial species present in the GIT, where constructed and added to standard rat feed. Six rats, with a normal microbiota, were fed DNA containing pellets daily over four days before sampling of the microbiota from the different GI compartments (stomach, small intestine, cecum and colon). In addition, two rats were included as negative controls. Antibiotic resistant colonies growing on selective media were screened for recombination with feed introduced DNA by PCR targeting unique sites in the putatively recombined regions.
Conclusions: The analyses showed that extensive ingestion of DNA (100 \ub5g plasmid) per day did not lead to increased proportions of kanamycin resistant bacteria, nor did it produce detectable transformants among the aerobic microbiota examined for 6 rats (detection limit <1 transformant per 1.1 x 108 cultured bacteria). The key methodological challenges to HGT detection in animal feedings trials are identified and discussed
The Seralini affair: degeneration of Science to Re-Science?
A paper reporting findings relevant to safety of the genetically modified (GM) maize NK603 and the herbicide
Roundup (Séralini et al., Food Chem Toxicol. 50:4221–4231, 2012) was retracted against the wishes of the authors, and
subsequently republished in another peer-reviewed journal (Séralini et al. Environ Sci Europe, doi:10.1186/s12302-
014-0014-5, 2014). These events exemplify a trend in which disputes, between interest groups vying for retraction
and republication of papers that report controversial results, overshadow the normal scientific process in which
peer-reviewed publication stimulates new research, generating new empirical evidence that drives the evolution of
scientific understanding. This paper reviews the current status of research on safety of NK603 maize and Roundup
herbicide for human and livestock health, and attempts to glean from recent developments insights relevant to risk
assessment policy for GM crops and pesticides, as well as relevant to the scientific process in general. Our analysis
of currently published evidence confirms NK603 and Roundup are kidney and liver toxicants at levels below current
regulatory thresholds. Consequently, the regulatory status of NK603, glyphosate and Roundup requires reevaluation.
Additionally, preliminary evidence indicates Roundup and NK603, individually and in combination, may increase
tumor incidence and mortality. Follow-up long-term carcinogenicity studies, using test animal strains and numbers of
animals that assure robust conclusions, are required to confirm/refute this preliminary evidence. The inherent tension
between the scientific process and commercial interests of product developers necessitates implementation of safeguards
that protect the scientific process and prevent degeneration of Science to Re-Science (typified by retraction
and republication disputes)
Life cycle fitness differences in Daphnia magna fed Roundup-Ready soybean or conventional soybean or organic soybean
A lifelong feeding study with soybean from different production systems was carried out in the crustacean Daphnia magna (water flea), an acknowledged model organism for ecotoxicological studies. Experimental diets were prepared with soybean meal from different agriculture production systems: (i) genetically modified Roundup‐Ready soy (Glyphosate‐Tolerant), (ii) conventional soy and (iii) soy from organic agriculture (agriculture with neither synthetic pesticides nor synthetic fertilizers). Overall, feed produced from organic soybeans resulted in the highest fitness (higher survival, better growth and fecundity) in the model organism. Animals fed Roundup‐Ready soybean consistently performed less well compared to animals fed either conventional or organic soybeans. We conclude that accumulation of herbicide residues in Roundup‐Ready soy and related nutritional differences between the soy types may have caused the observed fitness differences. The results accentuate the need for further research clarifying qualitative aspects, including potential large‐scale consequences for food and feed quality, of this dominant crop