Urine from Treated Cattle Drives Selection for Cephalosporin Resistant Escherichia coli in Soil

The U.S. Food and Drug Administration recently issued new rules for using ceftiofur in food animals in part because of an increasing prevalence of enteric bacteria that are resistant to 3^rd-generation cephalosporins. Parenteral ceftiofur treatment, however, has limited effects on enteric bacteria so we tested the hypothesis that excreted ceftiofur metabolites exert significant selection pressure for ceftiofur-resistant Escherichia coli in soil. Test matrices were prepared by mixing soil with bovine feces and adding urine containing ceftiofur metabolites (CFM) (0 ppm, ∼50 ppm and ∼100 ppm). Matrices were incubated at 23°C or 4°C for variable periods of time after which residual CFM was quantified using a bioassay. Bla _CMY-2 plasmid-bearing ceftiofur resistant (cef^R) E. coli and one-month old calves were used to study the selection effects of CFM and transmission of cef^R bacteria from the environment back to animals. Our studies showed that urinary CFM (∼13 ppm final concentration) is biologically degraded in soil within 2.7 days at 23°C, but persists up to 23.3 days at 4°C. Even short-term persistence in soil provides a >1 log₁₀ advantage to resistant E. coli populations, resulting in significantly prolonged persistence of these bacteria in the soil (∼two months). We further show that resistant strains readily colonize calves by contact with contaminated bedding and without antibiotic selection pressure. Ceftiofur metabolites in urine amplify resistant E. coli populations and, if applicable to field conditions, this effect is far more compelling than reported selection in vivo after parenteral administration of ceftiofur. Because ceftiofur degradation is temperature dependent, these compounds may accumulate during colder months and this could further enhance selection as seasonal temperatures increase. If cost-effective engineered solutions can be developed to limit ex vivo selection, this may limit proliferation for ceftiofur resistant enteric bacteria while preserving the ability to use this important antibiotic in food animal production.     

Influence of irradiation quality on photosynthetic pigments, saccharides, nitrate reductase activity, thylakoid organization and growth of Ulva pertusa

A floating green alga Ulva pertusa Kjallman was grown in the laboratory under various irradiations: "white light" (as reference, broad spectral band, WLC), red radiation (600-700 nm, RRC) and blue radiation (400-500 nm, BRC). During 15 d of culture, the specific growth rate of WLC varied highly when compared to BRC and RRC. The contents of chlorophyll (Chl) and proteins, and the nitrate reductase (NR) activity were significantly higher in BRC than in RRC while the content of saccharides was slightly higher in RRC than BRC. U. pertusa in WLC had the highest contents of saccharides, proteins, and Chl, and the highest NR activity. In the WLC, closely arranged well organized thylakoids were seen whereas in the BRC, although the number of thylakoid layers was similar to WLC, they were widely separated from each other. In contrast to this, in the RRC, the thylakoids were less prominent and were also densely covered with ribosomes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Additive interaction of <Emphasis Type="Italic">Helicoverpa armigera</Emphasis> Nucleopolyhedrovirus and Azadirachtin

Mortality of Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) was higher in the combined treatment of Nucleopolyhedrovirus (NPV) and Azadirachtin (AZA) and mortality was increased when AZA concentration was doubled. Larval mortality decreased as the age of the larvae increased in all the treatments. The time for 100% kill of third instar larvae was significantly reduced to 72 h when AZA (0.1 ppm) was combined with NPV (10³ PIB/ml) when compared to 168 and 120 h for the same dose NPV and AZA individual treatments, respectively. The average leaf disc consumption, consumption index (CI), relative growth rate (RGR), the efficiency of conversion of ingested (ECI) and digested (ECD) food values were drastically reduced in the combined treatment of NPV and AZA than in the individual treatments. Larval as well as pupal durations were significantly extended and the adult longevity and fecundity were significantly reduced in the combined treatment of NPV and AZA. Weight of 14 day old control larvae was 420 mg and it was reduced to 299 and 248 mg after NPV (5 × 10² PIB/ml) and AZA (0.025 ppm) treatments, respectively. The larval weight was drastically decreased to 99 mg after the combined treatment at the same dose. The additive interaction between both the treatments, AZA and NPV, was found to be in a dose dependent manner and were highly compatible in disrupting the survival, feeding and biology of H. armigera.     

Study of the in vitro development of the parthenogenetic egg of daphnia carinata king (Cladocera: Daphnidae)

The embryonic development of Daphnia carinata King was studied under laboratory conditions. Detailed observations were made at frequent intervals and conspicuous morphological changes were recorded. The results were compared with those of other allied tropical and temperate forms. While the basic pattern of development is similar to that of other daphnids, the duration of the total period of development as well as of the individual stages in this species differed from those of other tropical and temperate forms.     

Stabilization of type I collagen against collagenases (type I) and thermal degradation using iron complex

The widespread application of collagen as a biomaterial warrants research in understanding the stabilization of the same. In this study, interaction of iron-tetrakis (hydroxymethyl) phosphonium (THP) complex with type I collagen has been investigated. DSC and hydrothermal measurement studies reveal that the shrinkage temperature of iron-THP treated rat tail tendon (RTT) collagen is 33 degrees C higher than that of native RTT collagen. Fe-THP complex also brings about high degree of enzymatic stability to type I collagen. The effect of Fe-THP on the conformation of collagen was studied using circular dichroism and it was found that no major alterations in the triple helical structure of collagen occur on treatment with Fe-THP. It is observed from viscosity experiment results that though Fe-THP complex is able to bring about long range ordering of collagen, as evident from the thermal and enzymatic stability imparted to collagen, this ordering does not lead to any aggregation of collagen. Since THPS is reducing in nature, it is expected to keep iron in the +2 state and if THP chelates to Fe(II), the hydrolytic behavior of iron can also be controlled.     

3β-Hydroxylup-20(29)-ene-27,28-dioic acid dimethyl ester,a novel natural product from Plumbago zeylanica inhibits the proliferation and migration of MDA-MB-231 cells

Plumbago zeylanica, a traditional Indian herb is being used for the therapy of rheumatism and has been approved for anti-tumor activity. However, the molecular mechanisms involved in the biological action are not very well understood. In this study, the anti-invasive activities of P. zeylanica methanolic extract (PME) and pure compound 3β-hydroxylup-20(29)-ene-27,28-dioic acid (PZP) isolated from it are investigated in vitro. PME and PZP were noted to have the ability to induce apoptosis as assessed by flow cytometry. Further, the molecular mechanism of apoptosis induced by PME and PZP was found by the loss of mitochondrial membrane potential with the down regulation of Bcl-2, increased expression of Bad, release of cytochrome c, activation of caspase-3 and cleavage of PARP leading to DNA fragmentation. Importantly, both PME and PZP were observed to suppress MDA-MB-231 cells adhesion to the fibronectin-coated substrate and also inhibited the wound healing migration and invasion of MDA-MB-231 cells through the reconstituted extracellular matrix. Gelatin zymography revealed that PME and PZP decreased the secretion of matrix metalloproteinases-2 (MMP-2) and metalloproteinases-9 (MMP-9). Interestingly both PME and PZP exerted an inhibitory effect on the protein levels of p-PI3K, p-Akt, p-JNK, p-ERK1/2, MMP-2, MMP-9, VEGF and HIF-1α that are consistent with the observed anti-metastatic effect. Collectively, these data provide the molecular basis of the anti-proliferative and anti-metastatic effects of PME and PZP.