Genotoxic activity of 1,3-butadiene and nitrogen dioxide and their photochemical reaction products in Drosophila and in the mouse bone marrow micronucleus assay.

The genotoxic activity of a photochemical reaction mixture of 1,3-butadiene and nitrogen dioxide was investigated in vivo in the mouse bone marrow micronucleus assay and the somatic mutation and recombination test in Drosophila (the wing spot test). Butadiene alone was not mutagenic in Drosophila, but induced micronuclei in mice at 10 ppm after 23 h of exposure. Nitrogen dioxide was not genotoxic in either test system. The photochemical reaction products were toxic but probably not mutagenic in Drosophila and not genotoxic in mouse bone marrow. The in vivo results do not confirm earlier in vitro results that demonstrated a strong direct-acting mutagenic activity of the photochemical products in Salmonella.     

Origin of fungal biomass degrading enzymes: Evolution,diversity and function of enzymes of early lineage fungi

The aim of this study was to elucidate the evolution of enzyme secretome of early lineage fungi to contribute to resolving the basal part of Fungal Kingdom and pave the way for industrial evaluation of their unique enzymes. By combining results of advanced sequence analysis with secretome mass spectrometry and phylogenetic trees, we provide evidence for that plant cell wall degrading enzymes of higher fungi share a common ancestor with enzymes from aerobic ancient fungi. Sequence analysis (HotPep, confirmed by dbCAN-HMM models) enabled prediction of enzyme function directly from sequence. For the first time, oxidative enzymes are described here in early lineage fungi (Chytridiomycota & Cryptomycota), which supports the conceptually new understanding that fungal LPMOs were also present in the early evolution of the Fungal Kingdom. Phylogenetic analysis of fungal AA9 proteins suggests an LPMO-common-ancestor with Ascomycetes and Basidiomycetes and describes a new clade of AA9s. We identified two very strong biomass degraders, Rhizophlyctis rosea (soil-inhabiting) and Neocallimastix californiae (rumen), with a rich spectrum of cellulolytic, xylanolytic and pectinolytic enzymes, characteristically including several different enzymes with the same function. Their secretome composition suggests horizontal gene transfer was involved in transition to terrestrial and rumen habitats. Methods developed for recombinant production and protein characterization of enzymes from zoosporic fungi pave the way for biotechnological exploitation of unique enzymes from early lineage fungi with potential to contribute to improved biomass conversion. The phyla of ancient fungi through evolution have developed to be very different and together they constitute a rich enzyme discovery pool.     

Assessment of the specificity of Burkholderia and Pseudomonas qPCR assays for detection of these genera in soil using 454 pyrosequencing

In this study, two highly specific quantitative PCR assays targeting the bacterial genera Burkholderia and Pseudomonas were developed and evaluated on soil samples. The primers were targeting different multivariate regions of the 16S rRNA gene and designed to be compatible with quantitative PCR and the high throughput 454 pyrosequencing technique. The developed assays were validated using the standard methods. All tests with the new developed assays showed very high specificity. Pyrosequencing was used for direct analysis of the PCR product and applied as a specificity measurement of the primers. The Pseudomonas primers showed a 99% primer specificity, which covered 200 different Pseudomonas sequence clusters in 0.5 g of soil. In contrast to that the same approach using the genus-specific Burkholderia primers showed only 8% primer specificity. This discrepancy in primer specificity between the normal procedures compared with pyrosequencing illustrates that the common validation procedures for quantitative PCR primers may be misleading. Our results exemplify the fact that current 16S RNA gene sequence databases might lack resolution within many taxonomic groups and emphasize the necessity for a standardized and functional primer validation protocol. A possible solution to this could be to supplement the normal verification of quantitative PCR assays with a pyrosequencing approach.     

Malaria vectors and transmission dynamics in coastal south-western Cameroon

Background

Malaria is a major public health problem in Cameroon. Unlike in the southern forested areas where the epidemiology of malaria has been better studied prior to the implementation of control activities, little is known about the distribution and role of anophelines in malaria transmission in the coastal areas.

Methods

A 12-month longitudinal entomological survey was conducted in Tiko, Limbe and Idenau from August 2001 to July 2002. Mosquitoes captured indoors on human volunteers were identified morphologically. Species of the Anopheles gambiae complex were identified using the polymerase chain reaction (PCR). Mosquito infectivity was detected by the enzyme-linked immunosorbent assay and PCR. Malariometric indices (plasmodic index, gametocytic index, parasite species prevalence) were determined in three age groups (<5 yrs, 5–15 yrs, >15 yrs) and followed-up once every three months.

Results

In all, 2,773 malaria vectors comprising Anopheles gambiae (78.2%), Anopheles funestus (17.4%) and Anopheles nili (7.4%) were captured. Anopheles melas was not anthropophagic. Anopheles gambiae had the highest infection rates. There were 287, 160 and 149 infective bites/person/year in Tiko, Limbe and Idenau, respectively. Anopheles gambiae accounted for 72.7%, An. funestus for 23% and An. nili for 4.3% of the transmission. The prevalence of malaria parasitaemia was 41.5% in children <5 years of age, 31.5% in those 5–15 years and 10.5% in those >15 years, and Plasmodium falciparum was the predominant parasite species.

Conclusion

Malaria transmission is perennial, rainfall dependent and An. melas does not contribute to transmission. These findings are important in the planning and implementation of malaria control activities in coastal Cameroon and West Africa.

     

Metabolic activation of promutagens, detectable in Ames' Salmonella assay, by 5000 X g supernatant of rat ventral prostate

Induction of aryl hydrocarbon hydroxylase (AHH) and 7-ethoxyresorufin-O-deethylase (7-EOD) activities as well as of benzo[a]pyrene (BP) metabolite formation in rat prostatic microsomes has been demonstrated after treatment with beta-naphthoflavone (BNF). The capacity to convert promutagenic compounds to ultimate mutagenic metabolites in the Ames' Salmonella assay by 5000 X g supernatant of rat ventral prostate was investigated. Male rats were treated with BNF, polychlorinated biphenyls (PCB; Arochlor 1254), phenobarbital (PB) and the vehicle, corn oil. PCB or BNF pretreatment increased the AHH- and 7-EOD activities 100-200-fold in the rat prostate 5000 X g supernatant (S-5 fraction). Epoxide hydrolase (EH) and glutathione-S-transferase (GST) activities were not affected while UDP-glucuronosyltransferase (UDP-GT) was increased 2.2- and 2.5-fold by PCB and BNF, respectively. PB did not significantly affect any of the enzyme activities measured. A dose-dependent increase in mutagenic response versus amount of 5000 X g supernatant and promutagen (aflatoxin B1 (AFB), 2-aminofluorene (2-AF), BP) was observed. The most pronounced activation was obtained with S-5 fraction from BNF- or PCB-treated rats. The great sensitivity of prostatic AHH to certain inducers and the capacity of the prostate to produce mutagenic metabolites might be of importance for initiation of prostatic cancer by environmental factors.     

Microextraction of Nuclear Proteins from Single Maize Embryos

The analysis of DNA binding proteins can be difficult when only small quantities of tissue expressing the desired protein are available. We present a protocol for the preparation of nuclear extracts from as little as 100 mg of tissue. This protocol is well suited for extraction of DNA binding proteins from tissues that are difficult to obtain in large quantities such as maize embryos.     

Transforming growth factor beta differentially regulates expression of integrin subunits in guinea pig airway epithelial cells.

The integrin family is composed of a large number of heterodimers, each one mediating distinct interactions with extracellular matrix and/or cell surface ligands. The expression of integrins appears to be tightly regulated in vivo, but the mechanisms by which cells control the formation and surface expression of specific pairs of subunits have not been well characterized. Two integrin subunits, the alpha subunit alpha v, and the beta subunit beta 1, could pose special problems in regulation because of their capacity to associate with multiple partners. In the present study, we have examined the effects of the cytokine transforming growth factor beta 1 (TGF-beta 1) on the expression of alpha v- and beta 1-containing integrins in primary cultures of guinea pig airway epithelial cells, e.g. cells that we have previously found to express multiple potential partners for both alpha v and beta 1. TGF-beta 1 increased the surface expression of both alpha v- and beta 1-containing heterodimers after periods of stimulation from 24 to 72 h. These increases in surface expression were associated with significant increases in the concentrations of mRNA encoding each of the partners of alpha v and beta 1, but with only minimal increases in mRNA encoding alpha v and beta 1 themselves. Airway epithelial cells metabolically labeled with [35S]methionine during stimulation with TGF-beta 1 demonstrated only a minimal increase in the synthesis of new alpha v protein at a time when synthesis of alpha v's beta subunit partners and surface expression of alpha v-containing heterodimers were dramatically increased. These data suggest that, at least in some cells, promiscuous integrin subunits (both alpha and beta) may normally be synthesized in excess. Thus, the surface expression of specific integrin heterodimers can be regulated primarily through regulation of the synthesis of the specific partners of these subunits.