Unique zinc mass in mandibles separates drywood termites from other groups of termites

Previously, the presence of metals in arthropod mandibles has been linked with harder cuticle, and in termites, a 20% increase in hardness has been found for mandibles containing major quantities of zinc. The current study utilises electron microscopy and energy-dispersive X-ray microanalysis to assess incidence and abundance of metals in all extant subfamilies of the Isoptera. The basal clades contain no zinc and little to no manganese in the cutting edge of the mandible cuticle, suggesting that these states are ancestral for termites. However, experimentation with mandibles in vitro indicates the presence of some elements of the cuticular biochemistry necessary to enable uptake of zinc. The Termopsidae, Serritermitidae, Rhinotermitidae and Termitidae all contain minor quantities of manganese, while trace to minor quantities of zinc occur in all except the Serritermitidae. In contrast, all Kalotermitidae or drywood termites contain major levels of zinc in the mandible edge. Diet and life type are explored as links to metal profiles across the termites. The presence of harder mandibles in the drywood termites may be related to lack of access to free water with which to moisten wood. Scratch tests were applied to a set of mandibles. The coefficient of friction for Cryptotermes primus (Kalotermitidae) mandibles, when compared with species from other subfamilies, indicates that zinc-containing mandibles are likely to be more scratch resistant.     

Fungal laccases: from structure-activity studies to environmental applications

Laccases are multicopper oxidases mainly secreted by filamentous fungi. Producing radical forms from organic substrates, they are involved in numerous reactions leading to the degradation and polymerization of xenobiotics. Our studies have led to a better knowledge of the structural, catalytic and genetic properties of laccases and allowed to develop a strategy for their evolution through genetic engineering. Here, we show that fungal laccases, wild or engineered, may be potent tools to develop bioremediation processes of soils polluted by organic compounds, and assays to assess the ecotoxicological impact of these pollutants on soil fungi.     

Analysis of chromium and copper by cathodic stripping voltammetry with mixed ligands

Cathodic adsorptive stripping voltammetry is one of the most sensitive analytical methods for ultratrace analysis. The detection limit is usually lower than 10⁻⁹ mol/L. Most adsorptive stripping procedures have been focused on the one ligand/one analyte approach. In order to reduce analysis time and sample volume, the possibility of simultaneously determining several metals by cathodic stripping voltammetry using a mixture of ligands was explored, e.g., by Colombo and van den Berg (1997). Here, we describe a new procedure for quantifying chromium and copper using 2,2′-bipyridine and 8-hydroxyquinoline (oxine). The effect of various operational parameters such as buffer type, ligand concentration, potential and time collection were assessed and optimized. Possible interferences by trace metals and organic matter were also investigated. Applicability for fresh water is illustrated. Electronic Publication     

Brood defense and filial cannibalism in the spottail darter (<Emphasis Type="Italic">Etheostoma squamiceps)</Emphasis>: the effects of parental status and prior experience

Male spottail darters (Etheostoma squamiceps) defend nest sites in which females deposit eggs over the course of several weeks. In laboratory experiments, I tested three predictions of the hypothesis that the presence of eggs increases the value of a nest site to male spottail darters: (1) males should preferentially defend nests with eggs over empty nests, and males that sired the eggs should (2) spend more time defending them and (3) consume less of their broods than should alloparent males. Parent males were tested using eggs they were guarding in the field; alloparents included males that were not defending eggs immediately prior to the experiment (inexperienced), and males that were defending eggs in the field when captured but were given eggs sired by a different male (experienced). In choice experiments in which males were offered nest sites differing only in the presence of eggs, males preferred to defend nest sites with eggs regardless of parental status. Parent males spent significantly more time defending eggs and consumed less of their broods than did inexperienced alloparent males. Experienced alloparent males were similar to parent males in brood defense but had levels of filial cannibalism similar to inexperienced males, suggesting that prior experience may influence brood defense but not egg consumption.     

Block Copolymers Containing (R)-3-Hydroxybutyrate and Isosorbide Succinate or (S)-Lactic Acid Mers

A new aliphatic block copolyester was synthesized in bulk from transesterification techniques between poly((R)-3-hydroxybutyrate) (PHB) and poly(isosorbide succinate) (PIS). Additionally, other two block copolyesters were synthesized in bulk either from transesterification reactions involving PHB and poly(l-lactide) (PLLA) or from ring-opening copolymerization of l-lactide and hydroxyl-terminated PHB, as result of a previous transesterification reactions with isosorbide. Two-component blends of PHB and PIS or PLLA were also prepared as comparative systems. SEC, MALDI-TOF mass spectrometry (MALDI-TOFMS), ¹H and ¹³C NMR spectroscopy, WAXD, solubility tests, and TG thermal analysis were used for characterization. The block copolymer structures of the products were evidenced by MALDI-TOFMS, ¹³C NMR, and WAXD data. The block copolymers and the corresponding binary blends presented different solubility properties, as revealed by solubility tests. Although the incorporation of PIS sequences into PHB main backbone did not enhance the thermal stability of the product, it reduced its crystallinity, which could be advantageous for faster biodegradation rate. These products, composed of PHB and PIS or PLLA sequences, are an interesting alternative in biomedical applications.     

Purification and Properties of Extracellular Poly(3-hydroxybutyrate) Depolymerase Produced by <Emphasis Type="Italic">Aspergillus fumigatus</Emphasis> 202

An extracellular poly(3-hydroxybutyrate) (PHB) depolymerase produced by a thermotolerant fungal soil isolate, Aspergillus fumigatus 202, was purified and characterized. Maximum PHB depolymerase production was obtained at the end of 48 h with initial medium pH 7.0 and 45 °C in Bushnell Haas Minerals medium containing PHB as sole source of carbon. The PHB depolymerase was purified using size exclusion chromatography to a fold purification of 20.62 and 61.62% yield. SDS-PAGE and isoelectric focusing revealed the molecular weight and pI of the purified enzyme as 63,744 Da and 4.2, respectively. N-terminal amino acid sequence of purified enzyme was HAXDAYLVK. This non-glycosylated enzyme was most active at pH 9.0 and 45 °C. Purified enzyme was inactivated by N-bromosuccinimide and dithiothreitol suggesting the involvement of tryptophan residues and disulfide bonds at its active site. Nonionic detergents like Tween 20, Tween 80 and Triton X-100 inhibited the enzyme activity. Ions like Ca⁺² and Mg⁺² (5 mM) increased the enzyme activity 1.5 times. Fe⁺² effectively inhibited the enzyme activity to 88% whereas Hg⁺² completely inhibited the enzyme.     

Low‐concentration hydrogen peroxide decontamination for Bacillus spore contamination in buildings

Remediation and recovery efforts after a release of Bacillus anthracis (anthrax) spores may be difficult and costly. In addition, response and recovery technologies may be focused on critical resources, leaving the small business or homeowner without remediation options. This study evaluates the efficacy of relatively low levels of hydrogen peroxide vapor (HPV) delivered from off‐the‐shelf equipment for the inactivation of Bacillus spores within an indoor environment. Decontamination evaluations were conducted in a house using both Bacillus atrophaeus var. globigii (Bg; as surrogates for B. anthracis) inoculated on the carpet and galvanized metal as coupons and Geobacillus stearothermophilus (Gs) as biological indicators on steel. The total decontamination time ranged from 4 to 7 days. Using the longer exposure times, low concentrations of HPV (average levels below 20 parts per million) effectively inactivated Bg and Gs spores on the materials tested. The HPV was generated with commercial humidifiers and household‐strength hydrogen peroxide solutions. The presence of home furnishings did not have a significant impact on HPV efficacy. This simple, inexpensive, and effective decontamination method could have significant utility for remediation following a B. anthracis spore release, such as following a terrorist attack.     

Screening of phthalic acid esters in raw materials,premixes and feed additives

Phthalates are animal carcinogens and may cause death or tissue deformities. Samples of feedstuffs collected in 2005 and 2006 from industrial feed manufacturers in the Czech Republic were analysed for contamination with phthalic acid esters (PAEs), specifically di-2-ethylhexyl phthalate (DEHP) and di-n-butyl phthalate (DBP). Samples of feed additives, premixes and raw materials were collected (year 2005, n = 26). For soybean oil, the total volume of phthalates measured (DBP + DEHP) reached a level of 131.42 mg kg⁻¹; for rapeseed oil, fish meal and animal fats, the levels measured were 15.00, 7.96 and 58.87 mg kg⁻¹, respectively. The lowest level of DBP + DEHP was found in corn (2.03 mg kg⁻¹). Since phthalates were detected, samples of feed additives (n = 28) and raw materials (n = 28) were collected again in 2006. The highest levels of DBP + DEHP were found in raw materials containing fat. Phthalate levels in rapeseed oil samples ranged from 1.38 to 32.40 mg kg⁻¹ DBP + DEHP. For feed additives, contamination levels in vitamins and amino acids ranged from 0.06 to 3.15 and 1.76 to 4.52 mg kg⁻¹ DBP + DEHP, respectively. Here, we show that the levels of PAEs found in cereals such as wheat, barley and corn may be regarded as being alarmingly high, because cereals make up the largest proportion of compound feed of farm animals.     

Photo-polymerization of triclosan in aqueous solution induced by ultraviolet radiation

The formation of 2,8-dichlorodibenzo-p-dioxin and other harmful degradation products in the photo-degradation process of triclosan is of increasing concern. Here we worked on the identification of polymerized products at high triclosan concentration and on the mechanism of photoreaction. Five dimmers and two trimers of triclosan were detected by liquid chromatography-mass spectrum analysis. 2,8-dichlorodibenzo-p-dioxin was also identified by comparing with an authentic standard. Relatively low pH and high concentration favored the polymerization of triclosan. Three main routes of photoreaction were postulated, namely dechlorination, ring closure and polymerization.