Enhancing chlamydospore production in Duddingtonia flagrans on solid substrate: The impact of mannitol and varied cultivation conditions

Duddingtonia flagrans is a nematophagous fungus which has shown promising results as a non-chemical parasitic control tool. The fungus disrupts the parasite's life cycle by trapping larvae in the environment through the networks generated from chlamydospores, thus preventing the reinfection of animals. One barrier to the development of a commercial product using this tool is the need to increase chlamydospore production in the laboratory for its administration to livestock. The purpose of this study was to evaluate the addition of mannitol to an enriched culture medium and the effect of adverse cultivation conditions on chlamydospore production. D. flagrans was cultivated on Petri dishes with corn agar for 4 weeks at 27 °C and 70% relative humidity (RH). Four groups were then formed, all with Sabouraud agar as a base, to which different growth inducers were added: GSA (glucose Sabouraud agar), GSA-MI (glucose Sabouraud agar + meso inositol), GSA-E (enriched glucose Sabouraud agar), and AE-M (enriched agar + mannitol). After 4 weeks, chlamydospores were recovered by washing the surface of each plate with distilled water and then quantified. The medium that yielded the highest amount of chlamydospores was subjected to different cultivation conditions: NC (normal conditions): 70% RH and 27 °C, AC (adverse conditions) 1: 20% RH and 40 °C, CA2: 60% RH and 27 °C, and CA3: 55% RH and 24 °C. It was determined that mannitol increases chlamydospore production (65x106 chlamydospores/plate), and when reducing humidity by 10% under cultivation conditions it resulted in an approximately 10% increase in chlamydospore production compared to the control group. These results suggest that the addition of polyols, as well as its cultivation under certain environmental conditions, can improve chlamydospore production on a laboratory scale.

Synergism of small molecules targeting VDAC with sorafenib, regorafenib or lenvatinib on hepatocarcinoma cell proliferation and survival

Voltage dependent anion channels (VDAC) in the outer mitochondrial membrane regulate the influx of metabolites that sustain mitochondrial metabolism and the efflux of ATP to the cytosol. Free tubulin and NADH close VDAC. The VDAC-binding small molecules X1 and SC18 modulate mitochondrial metabolism. X1 antagonizes the inhibitory effect of tubulin on VDAC. SC18 occupies an NADH-binding pocket in the inner wall of all VDAC isoforms. Here, we hypothesized that X1 and SC18 have a synergistic effect with sorafenib, regorafenib or lenvatinib to arrest proliferation and induce death in hepatocarcinoma cells. We used colony formation assays to determine cell proliferation, and a combination of calcein/propidium iodide, and trypan blue exclusion to assess cell death in the well differentiated Huh7 and the poorly differentiated SNU-449 cells. Synergism was assessed using the Chou-Talalay method. The inhibitory effect of X1, SC18, sorafenib, regorafenib and lenvatinib was concentration and time dependent. IC50s calculated from the inhibition of clonogenic capacity were lower than those determined from cell survival. At IC50s that inhibited cell proliferation, SC18 arrested cells in G0/G1. SC18 at 0.25-2 IC50s had a synergistic effect with sorafenib on clonogenic inhibition in Huh7 and SNU-449 cells, and with regorafenib or lenvatinib in SNU-449 cells. X1 or SC18 also had synergistic effects with sorafenib on promoting cell death at 0.5-2 IC50s for SC18 in Huh7 and SNU-449 cells. These results suggest that small molecules targeting VDAC represent a potential new class of drugs to treat liver cancer.

A review of the use of Duddingtonia flagrans as a biological controller of strongylid nematodes in horses

In horses, the nematodes of the Strongylidae family are the most important due to their prevalence and pathogenicity. Sanitary plans include parasite control based on chemical anthelmintics. Among these, the benzimidazole compounds have been used since the 1960s to control the nematode Strongylus vulgaris. Its inappropriate use resulted in the development of resistance in parasites with a shorter biological cycle, such as the small strongyles. Currently, the genera that make up this group show widespread resistance to all chemical treatments available in veterinary medicine, except for macrocyclic lactones, where less effective action has been detected. The need to find alternative routes for its control is recognized. International organizations and markets are increasingly restrictive in the allowed levels of drugs in products of animal origin, so one of the drawbacks is the permanence of chemical compounds in tissues. Therefore, other tools not chemically based are proposed, such as the biological control of gastrointestinal nematodes. Various research groups around the world have carried out tests on the control capacity of the nematophagous fungus Duddingtonia flagrans against this group of parasites. The objective of this review is to compile the different tests that are available on biological control in this species, in in vivo and in vitro tests, and the possible incorporation of this tool as an alternative method of antiparasitic control in an integrated control scheme of parasites.

Development of a construct-based risk assessment framework for genetic engineered crops

Experience gained in the risk assessment (RA) of genetically engineered (GE) crops since their first experimental introductions in the early nineties, has increased the level of familiarity with these breeding methodologies and has motivated several agencies and expert groups worldwide to revisit the scientific criteria underlying the RA process. Along these lines, the need to engage in a scientific discussion for the case of GE crops transformed with similar constructs was recently identified in Argentina. In response to this need, the Argentine branch of the International Life Sciences Institute (ILSI Argentina) convened a tripartite working group to discuss a science-based evaluation approach for transformation events developed with genetic constructs which are identical or similar to those used in previously evaluated or approved GE crops. This discussion considered new transformation events within the same or different species and covered both environmental and food safety aspects. A construct similarity concept was defined, considering the biological function of the introduced genes. Factors like environmental and dietary exposure, familiarity with both the crop and the trait as well as the crop biology, were identified as key to inform a construct-based RA process.

Changes in thyroid function in puppies fed a high iodine commercial diet

Abnormally low(131)I uptakes were noticed in dogs fed with commercial diets at the University Animal Clinic in Buenos Aires, but the total iodine content of eight different commercial diets examined was found to provide an iodine intake above daily requirements. To investigate this anomaly, 18 dogs were distributed into three groups, fed either: (1) a home-prepared diet; (2) a commercial diet; (3) a home-prepared diet supplemented with potassium iodide equivalent to that found in the commercial diet. The(131)I uptake in dogs of groups B and C was significantly decreased, as was basal serum thyroxine (T(4)) and free thyroxine (FT(4)), whereas urinary iodide excretion and serum thyroid stimulating hormone (TSH), were increased. The thyroid releasing hormone (TRH)-TSH test showed an increased response in dogs from group B, while the TRH-T(4)test was inhibited in both groups B and C. The results demonstrate that the excessive amount of iodine present in some commercial diets in Argentina causes a significant impairment of thyroid function and hypothyroidism.

Protein kinase C V3 domain mutants with differential sensitivities to m-calpain are not resistant to phorbol-ester-induced down-regulation

Distinct linker sequences were introduced into the protease-sensitive V3 domain of protein kinase C-alpha and the mutant proteins were expressed in COS-1 cells. Partially purified preparations of these mutants were functionally similar to wild-type protein kinase C-alpha, however their susceptibility to m-calpain was quite distinct, with one mutant being insensitive to cleavage. The three mutants, after expression in COS-1 cells, were found to behave in a manner indistinguishable from wild-type protein kinase C-alpha with respect to subcellular distribution, acute responses to 12-O-tetradecanoyl-phorbol 13-acetate and 12-O-tetradecanoyl-phorbol-13-acetate-induced down-regulation. The data imply that down-regulation of protein kinase C-alpha is likely to involve a general degradative process rather than cleavage by a site-specific protease.

Differential calcium mobilization by vasopressin, angiotensin II, gastrin-releasing peptide, and adenosine triphosphate in adult and fetal hepatocytes. Relevance for the activation of calcium-dependent enzymes

Early signals elicited after membrane receptor binding of agonists, the transmembrane signaling pathway of which involves activation of phosphoinositide-specific phospholipase C, were compared in fetal (22 days gestation) and adult rat hepatocytes. Free cytosolic calcium changes varied depending on the agonist and type of stimulated cells. Angiotensin II and ATP elicited the maximal responses in both types of cells, whereas the maximal Ca2+ increase produced by vasopressin was twice as much in adult than in fetal hepatocytes. The opposite response was observed for bombesin- or gastrin-releasing peptide-stimulated cells. Triggering of fetal and adult hepatocytes with substances that maximally promote endoplasmic reticulum calcium release or phosphoinositide-specific phospholipase C activation revealed that at least for the actions mediated through the angiotensin II and P2 purinergic receptor, the agonist stimulation was near the maximal response capacity of the signaling pathway. Agreement was observed between the relative number of membrane receptors and the biological responses.

Effects of ketoconazole on the iodide uptake by FRTL-5 cells

Ketoconazole is an imidazole derivative used as an antimycotic agent with reported effects on the endocrine system, but very little is known about its possible actions on thyroid function. Our purpose was to study the influence of this substance on the basal and TSH-stimulated iodide uptake in the rat thyroid cell strain FRTL-5. Ketoconazole (1-50 mumol/l) was shown to slightly increase the basal iodide uptake but, at higher concentrations (75-100 mumol/l), it sharply decreased iodide uptake below the basal levels. When the cells were cultured under bTSH stimulation (30 UI/l), the inhibitory effect of ketoconazole was exerted at concentrations as low as 25 mumol/l. This inhibition was observed even if it was added to the culture medium immediately before the Na125I addition. Forskolin, a stimulator of adenylate cyclase activity, was unable to prevent the iodide uptake inhibition. Low doses of ketoconazole increased cAMP concentrations. In the presence of TSH this effect was more evident in an inverse dose-dependent way. Because of its dual action, it can be assumed that ketoconazole could influence the iodide uptake in the FRTL-5 cells through more than one mechanism.

Oleic acid promotes changes in the subcellular distribution of protein kinase C in isolated hepatocytes

The effect of oleate on the subcellular distribution of protein kinase C (PKC) was studied in isolated hepatocytes and in perfused rat liver in the presence of physiological concentrations of serum albumin. A time- and dose-dependent translocation of PKC from the cytosol towards the membranes was observed at oleate concentrations that fell within the range of concentrations reached under several physiological conditions. Analysis of the membrane-bound isoenzymes of PKC by hydroxylapatite chromatography revealed that the beta isoenzyme was preferentially translocated to this compartment in hepatocytes incubated with oleate. Activation of PKC after incubation of hepatocytes with oleate involved at least three different effectors of the enzyme: the fatty acid itself, the diacylglycerol synthesized from oleate, and the rise in the cytosolic calcium concentration elicited by oleate. As a result of PKC activation, protein phosphorylation of intact hepatocytes in response to oleate exhibited an enhancement in the phosphate content of a protein of 82 kDa, similar to that phosphorylated in the presence of phorbol dibutyrate.

Substrate-dependent inhibition of protein kinase C by specific inhibitors

Protein kinase C (PKC) and its proteolysis-derived protein kinase independent of Ca2+ and phospholipids (PKM), were purified from rat brain. By using histone H1 and protamine as substrates, we assayed the effect of several inhibitors of PKC and PKM. The inhibition turned out to be dependent on both the nature of the kinase and the type of substrate assayed. These results may help to interpret the different responses elicited by PKC inhibitors in vivo.