TRPM channels are required for rhythmicity in the ultradian defecation rhythm of <Emphasis Type="Italic">C. elegans</Emphasis>

Background  

Ultradian rhythms, rhythms with a period of less than 24 hours, are a widespread and fundamental aspect of life. The mechanisms underlying the control of such rhythms remain only partially understood. Defecation in C. elegans is a very tightly controlled rhythmic process. Underlying the defecation motor programme is an oscillator which functions in the intestinal cells of the animal. This mechanism includes periodic calcium release and subsequent intercellular calcium waves which in turn regulate the muscle contractions that make up the defecation motor programme. Here we investigate the role of TRPM cation channels in this process.     

Comparison of Worm Control Strategies in Grazing Sheep in Denmark

Control of nematode parasites with reduced reliance on the use of anthelmintics was studied in 16 ewes with suckling twin lambs on contaminated pasture in Denmark. Ewes and lambs were treated with albendazole at turn-out 3 May. Ewes were removed from the groups on 26 July, and lambs were slaughtered on 11 October. The animals were allocated to 4 groups of 8 lambs and their 4 ewes. Group TS was treated with albendazole at weeks 3, 6 and 8 after turnout and set-stocked; group TM was similarly treated but moved to clean pasture in conjunction with the last drenching; group US was untreated and set-stocked, and group UM was left untreated but moved to clean pasture week 8 after turn-out. Supplementary feed was offered in June and August due to scarcity of pasture. Strategic treatments of ewes and lambs weeks 3, 6 and 8 after turn-out, with or without a move to clean pasture, were highly effective in controlling nematode infections for most of the season. This was reflected in better weight gains and carcass characteristics in the treated compared to untreated lambs, resulting in an average increase in the value of the product by 36%. The effect of moving without treatment (UM) on faecal egg counts was limited but peak pasture infectivity was reduced to less than 10% compared to the set-stocked group and weight gains of lambs were significantly better despite poor feed availability in late season. The study showed that under set-stocked conditions repeated anthelmintic treatments of both ewes and lambs in early season may ensure sufficient nematode control whereas moving animals to clean pasture without dosing was less efficient. The latter may, however, still be a viable option in organic and other production systems where routine use of anthelmintics is banned, particularly if weaning and moving are combined or a second move is performed.     

<i>In vitro</i> evaluation of antifungal activity of Agave (<i>Agave scabra</i>, Salm Dyck) extracts against post-harvest mushrooms

The agricultural sector, and particularly the horticultural production, has a singular importance in agriculture, considering that it ranks second on agricultural products, nationally and worldwide. Fungal diseases are one of the major causes of vegetable loss during storage, reducing their nutritional value, quality and sale price. Vegetables are usually exposed to diverse treatments with chemical products before storage; as a result, fungal populations develop an increased resistance over time becoming more difficult to control. Because of this, research efforts toward finding more suitable chemicals to control fungal diseases are needed. Natural extracts may be an alternative solve this problem. In the present investigation the fungicidal activity of aqueous and ethanol extracts of Agave scabra was evaluated on the growth of Botrytis cinerea, Mucor sp., Aspergillus niger, Fusarium sp. and Penicillium sp., whose strains were isolated from potato and tomato. To assess their effects, the agar-dilution and agar-well techniques were performed. The ethanol extract was more effective against Botrytis cinerea and Mucor sp. when the agar-well method was used. However, when using the agar-dilution method the ethanol extract of Agave scabra inhibited the growth of Botrytis cinerea, Mucor sp. and Penicillium sp.     

The mycoflora and toxicity of feedstuffs from a production plant in córdoba, Argentina

Feedstuffs used for poultry nutrition in Argentina were analyzed for fungal flora and natural incidence of mycotoxins. Survey of 120 samples of poultry feeds, taken from May 1998 to April 1999, showed the presence of 15 genera of filamentous fungi. The predominant genera wereFusarium spp. andPenicillium ssp., isolated in 67.5 % of the samples, followed byAspergillus spp. (57.5 %). Yeast, were significantly isolated from most of the samples. Species identification was carried down for the toxigenic genera. Fungal total counts of poultry feeds ranged from 2.0 × 10³ to 3.0 × 10⁵ CFU g^-1 The fungal total counts during two months of sampling, were slightly over the limit value of 1 × 105 CFU g^-1, which ensure the hygienic quality of the feed. Potentially toxicogenic species presented moderate mean colony counts. Many of the fungi isolated from poultry feeds are mycotoxin producers. Fumonisins had the highest incidence, and were found in 97 % of the analyzed samples followed by aflatoxin B₁ (46 %), zearalenone (18 %) and deoxynivalenol (6 %). On the co-occurrence of both carcinogenic mycotoxins, all of the FBs contaminated feed samples were co-contaminated with AFB₁. The results show the relevance of the samples screening for viable fungi propagules and the surveillance of their associated mycotoxins in poultry feeds.     

Synthesis and biological evaluation of indole-based,anti-cancer agents inspired by the vascular disrupting agent 2-(3′-hydroxy-4′-methoxyphenyl)-3-(3″,4″,5″-trimethoxybenzoyl)-6-methoxyindole (OXi8006)

The discovery of a 2-aryl-3-aroyl indole-based small-molecule inhibitor of tubulin assembly (referred to as OXi8006) inspired the design, synthesis, and biological evaluation of a series of diversely functionalized analogues. In the majority of examples, the pendant 2-aryl ring contained a 3-hydroxy-4-methoxy substitution pattern, and the fused aryl ring featured a 6-methoxy group. Most of the variability was in the 3-aroyl moiety, which was modified to incorporate methoxy (33–36), nitro (25–27), halogen (28–29), trifluoromethyl (30), or trifluoromethoxy (31–32) functionalities. In two analogues (34 and 36), the methoxy substitution pattern in the fused aryl ring varied, while in another derivative (35) the phenolic moiety was translocated from the pendant 2-aryl ring to position-7 of the fused aryl ring. Each of the compounds were evaluated for their cytotoxicity (in vitro) against the SK-OV-3 (ovarian), NCI-H460 (lung), and DU-145 (prostate) human cancer cell lines and for their ability to inhibit tubulin assembly. Four of the compounds (30, 31, 35, 36) proved to be potent inhibitors of tubulin assembly (IC₅₀ <5 μM), and three of these compounds (31, 35, 36) were strongly cytotoxic against the three cancer cell lines. The most active compound (36) in this series, which incorporated a methoxy group at position-7, was comparable in terms of inhibition of tubulin assembly and cytotoxicity to the lead compound OXi8006.     

Plasmid pGW16, a derivative of pKM101, increases post-UV DNA synthesis, but sensitises some strains of Escherichia coli to UV

Plasmid pKM101, which carries muc genes that are analogous in function to chromosomal umu genes, protected Escherichia coli strains AB1157 uvrB+ umuC+, JC3890 uvrB umuC+, TK702 uvrB+ umuC and TK501 uvrB umuC against ultraviolet irradiation (UV). Plasmid pGW16, a derivative of pKM101 selected for its increased spontaneous mutator effect, also gave some protection to the UmuC-deficient strains, TK702 and TK501. However, it sensitised the wild-type strain AB1157 to low, but protected against high doses of UV, whilst sensitising strain JC3890 to all UV doses tested. Even though its UV-protecting effects varied, pGW16 was shown to increase both spontaneous and UV-induced mutation in all strains. Another derivative of pKM101, plasmid pGW12, was shown to have lost all spontaneous and UV-induced mutator effects and did not affect post-UV survival. Plasmids pKM101 and pGW16 increased post-UV DNA synthesis in strains AB1157 and TK702, whereas pGW12 had no effect. Similarly, the wild-type UV-protecting plasmids R46, R446b and R124 increased post-UV DNA synthesis in strain TK501, but the non-UV-protecting plasmids R1, RP4 and R6K had no effect. These results accord with the model for error-prone DNA repair that requires umu or muc gene products for chain elongation after base insertion opposite non-coding lesions. They also suggest that the UV-sensitizing effects of pGW16 on umu+ strains can be explained in terms of overactive DNA repair resulting in lethal, rather than repaired UV-induced lesions.     

R-Factor-Mediated Nuclease Activity Involved in Thymineless Elimination

R-factor 1818 (R-1818) had no effect on the efficiency of plating of ligase-deficient phage T4 mutants on strains of Escherichia coli containing excess, normal, or defective ligase. However, if the R(+) bacterial strain that overproduced ligase was first starved of thymine, its ability to propagate ligase-deficient phage was reduced by as much as fivefold compared with the burst size on the thymine-starved R(-) strain. In contrast, it was found that after ultraviolet irradiation of the host the phage burst size was higher on the R(+) ligase overproducing strain than the R(-) derivative. The maximal level of R-factor elimination produced by thymine starvation was inversely related to the ligase level of the host. Ultraviolet irradiation did not cure the R factor from strains containing wild-type levels of ligase, but did cause elimination from strains with excess or defective ligase. The results suggest that R-1818 codes for a nuclease that is induced by thymine starvation and which, possibly in conjunction with host-mediated nucleases, is responsible for its elimination under these conditions.     

Preliminary evaluation of non-native rainbow trout (Oncorhynchus mykiss) impact on the Cederberg ghost frog (Heleophryne depressa) in South Africa’s Cape Fold Ecoregion

We evaluated the impact of non-native rainbow trout Oncorhynchus mykiss on a population of endemic Cedarberg ghost frog Heleophryne depressa in the upper Krom River (Olifants-Doring River Catchment, Cape Fold Ecoregion). We compared H. depressa abundance (using kick-sampling and underwater video analysis) and environmental conditions between sites above and below a waterfall that marks the upper distribution limit of O. mykiss. Heleophryne depressa abundance was significantly greater above the waterfall than that below it, and, because there was no significant difference in measured environmental variables, O. mykiss presence is identified as the most likely explanation for the observed decrease in H. depressa abundance.     

Comparison of the Escherichia coli umu+-encoded function with plasmid R46-mediated error-prone repair in DNA-damaged cells

Escherichia coli strain TK701 umu+ was more resistant than strain TK702 umu when tested against bleomycin (BLM), cis-platinum(II) diamminodichloride (PDD), ultraviolet light and methyl methanesulphonate (MMS), which produce single-strand DNA damage. However, the umu mutant was no more sensitive to mitomycin C (MTC) or proflavine (PF), which cause double-strand DNA binding. Strain TK702 umu was nonmutable by any of the agents, whereas mutations were induced in the wild-type strain by PDD, UV, MMS and MTC. The E. coli umu+ function therefore mimics plasmid R46-mediated error-prone repair in protecting only against single-strand DNA damage, whilst enhancing mutagenesis by both single- and double-strand damaging agents. Comparison of plasmid R46-mediated protection and mutagenesis in umu+ and umu strains indicated that the plasmid confers a greater error-prone DNA-repair activity in the mutant. Results are discussed in terms of analogy between host umu+ and plasmid muc+ functions.     

Metal contamination and human health risk associated with the consumption of Labeo rosae from the Olifants River system,South Africa

The Olifants River, a tributary of the Limpopo River system, is one of the most polluted rivers in South Africa. In May 2011 the concentrations of metals in fish muscle tissue from two impoundments, Loskop and Flag Boshielo dams, on the Olifants River were measured and a human health risk assessment conducted to investigate whether it was safe to consume Labeo rosae from these impoundments. Labeo rosae is one of the most common pan fish in these impoundments and is readily available to rural communities. Metals are accumulating in the muscle tissue of L. rosae even although the fish populations appear to be healthy. At Loskop Dam all L. rosae analysed exceeded the recommended hazard quotient (HQ) of 1 for antimony, and less than 50% exceeded that for lead. At Flag Boshielo Dam, the recommended HQ was exceeded for lead in less than 50% of L. rosae analysed, and more than 50% exceeded that for antimony. The weekly consumption of 150?g of L. rosae muscle tissue from these impoundments may pose an unacceptable health risk to rural communities.