Temporal change of the aggregation response in Triatoma infestans

Adults and larvae of Triatoma infestans spend daylight hours assembled in shaded places. An assembling factor has been demonstrated in the excrement of this species. We analysed different aspects of the dynamics of the response of bugs. Recently fed insects do not aggregate around faeces. They start to show a significant assembling response from the 8th hour after feeding onwards. Just deposited faeces do not evoke assembling, but a significant rejection instead. This reaction switches 3 h after deposition, when the faeces become attractive to the insects. The attractiveness of faeces persists for about 10 days and can be recovered after this time by rehydration. These findings are discussed in relation to the biological role of faeces and the dynamics of the use of refuges by T. infestans.     

Repeated plasticization and recovery of cuticular stiffness in the blood-sucking bug Triatoma infestans in the feeding context

Triatominae bugs experience changes in the mechanical properties of their cuticle prior to feeding. This process-plasticization-allows a rapid stretching of the unsclerotized abdominal cuticle of triatominae larvae and it is evoked by sensory inputs related to feeding. We tested: (a) whether the cuticle recovers its original mechanical properties after plasticization, (b) whether repeated stimulation would be able to evoke recurrent plasticization along the same larval instar, (c) the temporal course of recovering cuticular stiffness. We injected Ringer solution into the body cavity of the bugs at constant pressure, using the injection rate (ml/min) as a measure of the cuticle extensibility. To trigger plasticization, individuals were allowed to feed on blood from an artificial feeder at 32+/-2 degrees C. After plasticization occurred, the abdominal cuticle gradually recovered its original mechanical properties. Bugs were capable of plasticizing for a second time when repeatedly stimulated. The effects of plasticization vanished between 1 and 2 h after stimulation. Although one full meal could suffice to accomplish moult in other Triatomine species, Triatoma infestans is able to feed repeatedly during a single larval instar. Accordingly to this, their cuticle recovers stiffness in some hours and becomes able to respond repeatedly to sensory inputs associated with feeding.     

Hg(II)-coordination by sugar-acids: role of the hydroxy groups

A solution study on the ability of some derivatised sugars [glucuronic acid (GluA), galacturonic acid (GalA) and glucosaminic acid (GlNA)] to complex the Hg(II) ion is reported. The stability constants of the complex species were determined by potentiometric measurements while (1)H NMR experiments allow to define the coordination sites of sugar molecules. GluA coordinates the metal ion through the carboxylic oxygen and the O-4 hydroxyl group and is found to form more stable complexes with respect to GalA in which metal ligation is from the carboxylic oxygen and the O-5 ring oxygen. GlNA forms stable complexes chelating Hg(II) ion through carboxylic oxygen and the alpha-amino group. The ternary 2,2'-bipyridine containing systems were also investigated by means of potentiometric studies. The ML(2) complexes were also isolated in the solid state and characterised by IR spectroscopy.     

Astroglial cells in the central nervous system of the adult brown anole lizard, Anolis sagrei, revealed by intermediate filament immunohistochemistry

We analyzed the distribution of intermediate filament molecular markers, glial fibrillary acidic protein (GFAP), and vimentin in the brain and spinal cord of the adult brown anole lizard, Anolis sagrei. The GFAP immunoreactivity is strong and the positive structures are basically represented by fibers of different lengths and thicknesses which are arranged in a regular radial pattern throughout the central nervous system. In the brain regions that have a thicker neural wall, the radial orientation is not so evident as in the thinner areas. These fibers emerge from radial ependymoglia (tanycytes) whose cell bodies are generally GFAP-immunopositive. The glial fibers give rise to endfeet that are apposed to the subpial surface and to blood vessel walls. In the spinal cord, the optic tectum and the lateroventral regions of the mesencephalon and medulla oblongata, star-shaped astrocytes coexist with radial structures. Vimentin-immunoreactive structures are absent in the brain and spinal cord. In A. sagrei the immunohistochemical response of the astroglial intermediate filaments appears typical of a mature astroglial cell lineage, since they fundamentally express GFAP immunoreactivity. A Western-blot analysis reveals a GFAP-positive single band, common to the different nervous areas. This immunohistochemical study shows that the star-shaped astrocytes have a different distribution in saurians and while the glial pattern of A. sagrei is more evolved than in urodeles it remains immature as compared with crocodilians, avians, and mammals. This condition suggests that reptiles represent a fundamental step in the phylogenetic evolution of the vertebrate glial cells.     

Polymorphisms in the interleukin-4 receptor α chain gene influence susceptibility to HIV-1 infection and its progression to AIDS

Interleukin (IL) 4 is a key T helper-2 cytokine that downregulates and upregulates CCR5 and CXCR4, respectively, the main coreceptors for HIV. Our objective is to investigate whether single-nucleotide polymorphisms (SNPs) in the IL-4 receptor α chain gene (IL4RA) affect HIV infection and its progression to AIDS. The I50V SNP in exon 5 and the haplotypes of six SNPs in exon 12 (E375A, C406R, S411L, S478P, Q551R, and V554I) were studied by polymerase chain reaction and sequencing in 30 HIV⁺ long-term nonprogressors (LTNP), 36 HIV⁺ typical progressors (TP), 55 highly exposed but uninfected individuals (EU), 25 EU-sexuals (EU-Sex; mostly women) and 30 EU-hemophiliacs (EU-Hem; hepatitis C virus⁺), and 97 healthy controls (HC), all Caucasians and lacking CCR5Δ32 homozygosity. V50 homozygosity was increased in LTNP (44%) compared with the other groups [p=0.005; relative risk ratio=3.4, 95% confidence interval (CI)=1.12–10.6, p=0.03]. The most common (C) exon 12 haplotype, ECSSQV, predominated in all groups, but uncommon (U) haplotypes were increased in HIV⁺ individuals (n=64), especially in those (51 of 64) infected via parenteral exposure (35.3%) compared with HC (20.4%) and EU-Hem (18.4%) [p=0.01; odds ratio (OR)=2.14, 95% CI=1.25–3.67, p=0.01]. EU-Sex also had an increased frequency of U-haplotypes (34.8%) (OR=2.10, 95% CI=1.03–4.21, p=0.01) as well as an increased frequency of CU + UU genotypes (60.9%) compared with HC (38.2%) and EU-Hem (26.6%) (p=0.043). Distributions of genotypes fitted Hardy–Weinberg equilibrium. Data suggest that V50 homozygosity associates with slow progression and that exon 12 U-haplotypes might be associated with both susceptibility to infection via parenteral route and resistance to infection via sexual exposure. Further studies are required to confirm these findings.     

Zootechnical performance of cloned cattle and offspring: preliminary results

This paper presents information on the evolution of sets of cloned heifers of Holstein breed in comparison to that of control heifers derived from artificial insemination (AI) in the same farm, as well as data on a set of cloned bulls and their semen characteristics. Preliminary observations on a group of calves sired by a cloned bull and offspring of cloned females are reported. Mean birth weight in the clone group (50 females) was statistically higher than that of 68 contemporary female controls obtained by AI (49.27 +/- 10.98 vs. 40.57 +/- 5.55 kg, respectively, p < 0.05). Growth rate was within normal values for Holstein heifers (from 0.7 to 0.8 kg/day) and daily gain was not influenced by the high or low birth weight of clones. Within animals of the same clone, variability of daily gain was reduced compared to their control counterparts. Semen production from three cloned bulls was within the parameters expected for young bull of the same age. A direct comparison of morphological analysis was made between the frozen thawed semen of the donor bull and of his three clones collected at the same age. The overall semen picture appeared within acceptable limits and the clones presented similar percentages of sperm abnormalities (80% of morphologically normal spermatozoa) as the donor. These preliminary results suggest no deleterious effect of cloning on the semen picture of cloned sires. Frozen semen from one clone bull was used for an AI trial, resulting in 65% pregnancies, 25 live calves were naturally delivered. Concerning the offspring of both female and male clones, the phenotypical and clinical observation of the calves in the first week of age did not reveal any clinical abnormality, suggesting that the deviations observed in clones are not transmitted to the progeny.     

Importance of Shallow Water Habitats for Demersal Fishes and Decapod Crustaceans in Penobscot Bay, Maine

We characterized demersal fish and decapod crustacean habitats in 14 shallow (< 12m) areas in Penobscot Bay, Maine, by mapping the distribution of subtidal substrata with an acoustic sea bottom profiler. We identified the aquatic vegetation and the fishes and decapods associated with these habitats. Samples of fishes and decapods in each habitat were collected with a small beam trawl. The seabed at most of the stations sampled was composed of a mosaic of substrata. More species of fishes tow^-1 and higher abundances of fishes and decapods were found in stations with vegetation present, particularly eelgrass, Zostera marina. Decapod species richness tow^-1 was similar between vegetated and unvegetated habitats. Shallow habitats in Penobscot Bay were dominated by juvenile fishes and function as nursery areas. The greater species diversity and higher abundances of epibenthic fishes and decapod crustaceans observed in vegetated habitats, particularly beds of Zostera marina, compared with unvegetated areas in Penobscot Bay conform to the hypothesis that increased habitat complexity results in increased species richness and abundance.The first author is also senior author     

A limited survey of aflatoxins and fumonisins in retail maizebased products in the UK using immunoassay detection

A total of 27 maize-based products destined for human consumption were collected from retail outlets within the city of Glasgow in the UK and were analysed for the presence of aflatoxins using immunoaftinity column chromatography with fluorescence detection and for fumonisins by competitive ELISA. Aflatoxins were detected at a trace level below 4 in eight (30%) of the 27 samples tested, no sample contained aflatoxins at a high level although one sample of sweetcorn did contain aflatoxins at a level of 5-10 Fumonisins were detected in eight (30%) of the samples at levels from 1 to 8mgkg^-1 and a further eight samples contained fumonisin at a level below 1 mgkg^-1 but above the detectable level. The highest concentration of fumonisins was found in a sample of fine corn meal at 8-12mgkg^-1.