Acaricidal activity of spinosad and abamectin against two-spotted spider mites

Spinosad is a bioinsecticide with a high degree of selective toxicity towards insects of different orders, but its toxicity towards the two-spotted spider mite (TSSM), Tetranychus urticae Koch (Acari: Tetranychidae) is under debate. In this study, we compared the acaricidal properties of spinosad with the commercial bioacaricide abamectin on the life stages of TSSM. Adulticide and ovicide bioassays were performed on a susceptible laboratory strain using direct spraying of leaf disks with five rates of spinosad (20, 25, 30, 35 and 40 mg/l), five rates of abamectin (0.125, 0.25, 0.5, 1 and 2.5 mg/l), sublethal concentrations or a combination of spinosad and abamectin. Both adulticidal and ovicidal effects of spinosad against T. urticae in the laboratory were apparent, based on morality rates of the adults, reduction of female fecundity and death of offspring. Abamectin was also found to significantly reduce female fecundity and killed offspring when applied directly on the eggs. Interestingly, sublethal concentrations of spinosad reduced female fecundity stronger than abamectin. When a mixture of spinosad and abamectin was applied at LC_50, mortality was 74%, fecundity reduction was comparable to abamectin alone and egg hatching rate was lower than by either compound alone. In conclusion, spinosad was more harmful than abamectin for TSSM life stages and the combined application is recommended.     

A general solution for the time delay introduced by a low-pass Butterworth digital filter: An application to musculoskeletal modeling

Low-pass Butterworth digital filters are commonly used in biomechanics-related research. In general, the input signal is filtered in the forward and reverse directions so that a temporal shift in the output signal does not occur. There are times, however, when introducing a specific time delay is an important consideration when modeling a physiological event. Filtering the data in the forward direction only can be used as an efficient method to account for a specific time delay. Specific delays are possible by carefully selecting the filter order and cut-off frequency. The purpose of this paper is to present the analytical formulation of a general solution for the time delay introduced by a low-pass Butterworth digital filter.     

Macrophage apoAI protects against dyslipidemia-induced dermatitis and atherosclerosis without affecting HDL

Tissue cholesterol accumulation, macrophage infiltration, and inflammation are features of atherosclerosis and some forms of dermatitis. HDL and its main protein, apoAI, are acceptors of excess cholesterol from macrophages; this process inhibits tissue inflammation. Recent epidemiologic and clinical trial evidence questions the role of HDL and its manipulation in cardiovascular disease. We investigated the effect of ectopic macrophage apoAI expression on atherosclerosis and dermatitis induced by the combination of hypercholesterolemia and absence of HDL in mice. Hematopoietic progenitor cells were transduced to express human apoAI and transplanted into lethally irradiated LDL receptor^−/−/apoAI^−/− mice, which were then placed on a high-fat diet for 16 weeks. Macrophage apoAI expression reduced aortic CD4⁺ T-cell levels (−39.8%), lesion size (−25%), and necrotic core area (−31.6%), without affecting serum HDL or aortic macrophage levels. Macrophage apoAI reduced skin cholesterol by 39.8%, restored skin morphology, and reduced skin CD4⁺ T-cell levels. Macrophage apoAI also reduced CD4⁺ T-cell levels (−32.9%) in skin-draining lymph nodes but had no effect on other T cells, B cells, dendritic cells, or macrophages compared with control transplanted mice. Thus, macrophage apoAI expression protects against atherosclerosis and dermatitis by reducing cholesterol accumulation and regulating CD4⁺ T-cell levels, without affecting serum HDL or tissue macrophage levels.     

Enzymatic hydrolysis of rice straw and corn stalks for monosugars production

Rice straw and corn stalks were used as fermentation substrate for the evaluation of cellulases activity secreted by different organisms. The substrates were pretreated with alkaline hydrogen peroxide (AHP) for 6 h at 30 and 60 °C. From the fermentation studies, rice straw and corn stalks substrates showed the highest cellulases activity after 96 h at 60 °C of pre-treatment.     

Defining reference sequences for Nocardia species by similarity and clustering analyses of 16S rRNA gene sequence data

Background

The intra- and inter-species genetic diversity of bacteria and the absence of ‘reference’, or the most representative, sequences of individual species present a significant challenge for sequence-based identification. The aims of this study were to determine the utility, and compare the performance of several clustering and classification algorithms to identify the species of 364 sequences of 16S rRNA gene with a defined species in GenBank, and 110 sequences of 16S rRNA gene with no defined species, all within the genus Nocardia.

Methods

A total of 364 16S rRNA gene sequences of Nocardia species were studied. In addition, 110 16S rRNA gene sequences assigned only to the Nocardia genus level at the time of submission to GenBank were used for machine learning classification experiments. Different clustering algorithms were compared with a novel algorithm or the linear mapping (LM) of the distance matrix. Principal Components Analysis was used for the dimensionality reduction and visualization.

Results

The LM algorithm achieved the highest performance and classified the set of 364 16S rRNA sequences into 80 clusters, the majority of which (83.52%) corresponded with the original species. The most representative 16S rRNA sequences for individual Nocardia species have been identified as ‘centroids’ in respective clusters from which the distances to all other sequences were minimized; 110 16S rRNA gene sequences with identifications recorded only at the genus level were classified using machine learning methods. Simple kNN machine learning demonstrated the highest performance and classified Nocardia species sequences with an accuracy of 92.7% and a mean frequency of 0.578.

Conclusion

The identification of centroids of 16S rRNA gene sequence clusters using novel distance matrix clustering enables the identification of the most representative sequences for each individual species of Nocardia and allows the quantitation of inter- and intra-species variability.     

Quality control in the apoA-I secretory pathway: deletion of apoA-I helix 6 leads to the formation of cytosolic phospholipid inclusions

From a total of 47 known apolipoprotein A-I (apoA-I) mutations, only 18 are linked to low plasma HDL apoA-I concentrations, and 78% of these map to apoA-I helices 6 and 7 (residues 143-186). Gene transfer and transgenic mouse studies have shown that several helix 6 apoA-I mutations have reduced hepatic HDL production. Our objective was to examine the impact of helix 6 modifications on intracellular biosynthetic processing and secretion of apoA-I. Cells were transfected with wild-type or mutant apoA-I, radiolabeled with [(35)S]Met/Cys, and then placed in unlabeled medium for up to 4 h. Results show that >90% of newly synthesized wild-type apoA-I was secreted by 60 min. Over the same length of time, only 20% of helix 6 deletion mutant (Delta 6 apoA-I) was secreted, whereas 80% remained cell associated. Microscopic and biochemical studies revealed that cell-associated Delta 6 apoA-I was located predominantly within the cytoplasm as lipid-protein inclusions, whereas wild-type apoA-I was localized in the endoplasmic reticulum/Golgi. Results using other helix deletions or helix 6 substitution mutations indicated that only complete removal of helix 6 resulted in massive cytoplasmic accumulation. These data suggest that alterations in native apoA-I conformation can lead to aberrant trafficking and accumulation of apolipoprotein-phospholipid structures. Thus, conformation-dependent alterations in intracellular trafficking and turnover may underlie the reduced plasma HDL concentrations observed in individuals harboring deletion mutations within helix 6.     

Potential chemoprevention of diethylnitrosamine-initiated and 2-acetylaminofluorene-promoted hepatocarcinogenesis by zerumbone from the rhizomes of the subtropical ginger (Zingiber zerumbet)

Zerumbone (ZER), a monosesquiterpene found in the subtropical ginger (Zingiber zerumbet Smith), possesses antiproliferative properties to several cancer cells lines, including the cervical, skin and colon cancers. In this study, the antitumourigenic effects of ZER were assessed in rats induced to develop liver cancer with a single intraperitoneal injection of diethylnitrosamine (DEN, 200 mg/kg) and dietary 2-acetylaminofluorene (AAF) (0.02%). The rats also received intraperitoneal ZER injections at 15, 30 or 60 mg/kg body wt. twice a week for 11 weeks, beginning week four post-DEN injection. The hepatocytes of positive control (DEN/AAF) rats were smaller with larger hyperchromatic nuclei than normal, showing cytoplasmic granulation and intracytoplasmic violaceous material, which were characteristics of hepatocarcinogenesis. Histopathological evaluations showed that ZER protects the rat liver from the carcinogenic effects of DEN and AAF. Serum alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (AP) and alpha-fetoprotein (AFP) were significantly lower (P < 0.05) in ZER-treated than untreated rats with liver cancer. The liver malondialdehyde (MDA) concentrations significantly (P < 0.05) increased in the untreated DEN/AAF rats indicating hepatic lipid peroxidation. There was also significant (P < 0.05) reduction in the hepatic tissue glutathione (GSH) concentrations. The liver sections of untreated DEN/AAF rats also showed abundant proliferating cell nuclear antigen (PCNA), while in ZER-treated rats the expression of this antigen was significantly (P < 0.05) lowered. By the TUNEL assay, there were significantly (P < 0.05) higher numbers of apoptotic cells in DEN/AAF rats treated with ZER than those untreated. Zerumbone treatment had also increased Bax and decreased Bcl-2 protein expression in the livers of DEN/AAF rats, which suggested increased apoptosis. Even after 11 weeks of ZER treatment, there was no evidence of abnormality in the liver of normal rats. This study suggests that ZER reduces oxidative stress, inhibits proliferation, induces mitochondria-regulated apoptosis, thus minimising DEN/AAF-induced carcinogenesis in rat liver. Therefore, ZER has great potential in the treatment of liver cancers.     

Excretory-secretory product of fasciola hepatica worm protects against Schistosoma mansoni infection in mice

The objective of this study was to evaluate the protective immunity of excretory-secretory products of Fasciola hepatica (FhES) worm against S.mansoni infection in mice. Evaluation of FhES antigen was through measuring worm burden, ova count, granuloma size and frequency as well as the histopathological picture of the liver. The study was extended to determine the level of free radical scavengers; lipid peroxide, glutathione (GSH), vitamin C, vitamin E, catalase and superoxide dismutase (SOD). Liver function enzymes such as aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) were also taken into consideration. Four groups of eight mice each were selected for this study. Group 1 served as control group. Group 2: normal healthy mice vaccinated with FhES product. Group 3: S.mansoni infected mice for 2 months and group 4: infected mice pre-vaccinated with FhES antigen. Vaccination schedule comprised of a single subcutaneous injection of FhES antigen emulsified with Freund's complete adjuvant in a dose 0.5 mg protein/mouse, followed by intraperitoneal injections of the same antigen without adjuvant in 3 doses/week for 3 successive weeks. The total antigen inoculation was 5 mg protein/mouse. The present results revealed a drastic change in all the measured parameters after S.mansoni infection and a noticeable improved level after vaccination with FhES antigen. It can be concluded that FhES antigen succeeded to protect mice against schistosomiasis by a significant reduction in worm burden, ova count, granuloma size and number, improvement in the histopathological architecture of the liver as well as amelioration in the antioxidant levels under investigation.     

Discovery of a new prokaryotic type I GTP cyclohydrolase family

GTP cyclohydrolase I (GCYH-I) is the first enzyme of the de novo tetrahydrofolate biosynthetic pathway present in bacteria, fungi, and plants, and encoded in Escherichia coli by the folE gene. It is also the first enzyme of the biopterin (BH4) pathway in Homo sapiens, where it is encoded by a homologous folE gene. A homology-based search of GCYH-I orthologs in all sequenced bacteria revealed a group of microbes, including several clinically important pathogens, that encoded all of the enzymes of the tetrahydrofolate biosynthesis pathway but GCYH-I, suggesting that an alternate family was present in these organisms. A prediction based on phylogenetic occurrence and physical clustering identified the COG1469 family as a potential candidate for this missing enzyme family. The GCYH-I activity of COG1469 family proteins from a variety of sources (Thermotoga maritima, Bacillus subtilis, Acinetobacter baylyi, and Neisseria gonorrhoeae) was experimentally verified in vivo and/or in vitro. Although there is no detectable sequence homology with the canonical GCYH-I, protein fold recognition based on sequence profiles, secondary structure, and solvation potential information suggests that, like GCYH-I proteins, COG1469 proteins are members of the tunnel-fold (T-fold) structural superfamily. This new GCYH-I family is found in approximately 20% of sequenced bacteria and is prevalent in Archaea, but the family is to this date absent in Eukarya.