Titanium Dioxide Nanoparticle Circulation in an Aquatic Ecosystem

Nanotechnology is a dynamically developing field of scientific and industrial interest across the entire world, and the commercialization of nanoparticles (NPs) is rapidly expanding. Incorporation of nanotechnologies into a range of manufactured goods results in increasing concern regarding the subsequent release of engineered NPs into the environment. One of the biggest threats of using NPs is the transfer and magnification of these particles in the trophic chain. The aim of the studies was the evaluation of the distribution of TiO₂ NP contamination in the aquatic ecosystem under laboratory conditions. Bioaccumulation of TiO₂ NPs by plants (Elodea canadensis) and fish (Danio rerio) in the source of contamination was investigated. The studies were focused on the consequences of short-term water contamination with TiO₂ NPs and the secondary contamination of the components of the investigated model ecosystem (plants, sediments). It was found that in the fish and the plants exposed to NP contamination, the amount of Ti was higher than in the control, indicating an effective bioaccumulation of NPs or ions originating from NPs. It was clearly shown that the NPs present in the sediments are available to plants and fish. Additionally, the aquatic plants, an important trophic level in the food chain, can accumulate NPs and be a source of NPs for higher organisms. It was concluded that even an incidental contamination of water by NPs may result in long-term consequences induced by the release of NPs.     

Bovine brucellosis serum agglutination test prevalence and breed disposition according to prevalent management systems in the Lake Victoria zone of Tanzania

A total of 13078 cattle 8 months of age and older belonging to 558 units in the Lake Victoria zone of Tanzania were screened for brucellosis using the serum agglutination test (SAT). This exercise was executed as a Tanzanian Agriculture Ministry's directive for screening all adult bovines in the country reared under controlled grazing and receiving good veterinary supervision and inputs so that brucellosis control measures could be instituted. In this category two types of management systems were encountered: Dairy, comprising 15 units totalling 3626 Exotic (Friesian and Ayrshire) and Grade (Zebu and Exotic) crosses, and Ranch, comprising two units totalling 6756 mainly dual-purpose Mpwapwa (MPW) animals. These three animal types have much higher milk production potential than the indigenous Tanganyika shorthorn Zebu (TSZ). This latter beef type is reared under local management system and owned wholly by subsistence stock owners practising uncontrolled communal grazing and having little or no veterinary supervision and inputs. However, TSZ animals from 541 farm units totalling 2705 members were also screened from the east and south sub-zones because of their close proximity to the Dairy/Ranch units and also the Serengeti Wildlife National Park. This exercise revealed an overall prevalence rate of 10.8%. There was moreover a significant difference in the seroprevalence rates among the management systems (P < 0.001). The lowest prevalence rate (4.3%) was found in the Local management system, with Dairy intermediate (6.3%) and Ranch highest (15.8%). There was also significant variation in prevalence rates between TSZ and Grade animals, and between MPW and Exotic animals (P < 0.001).     

Morphometry of lodicules in the genus <Emphasis Type="Italic">Triticum</Emphasis> L.

Morphology of ripe lodicules in wheat taxonomic species was analyzed for all ploidy levels. From the initial set of sixteen characters, the best representatives and discriminants were selected. Length of main lobe and hairiness of this lobe as well as cushion appeared as the most stable selected characters. A non-metric multidimensional scaling procedure distinguished wheat diploids in the ordination space with Triticum urartu in a separate position. Other wheats, which were recognized as narrow endemics or hybrid recombinants, were seen as extremes in this space and they surround the centre with most of threshable taxa. Morphology of the lodicule differs between unthreshable and threshable wheats as well as between units having AABB and AAGG genomes. The development of hairs, lateral lobe and cushion is a factor creating main differences between lodicules of various taxa. Wheat species characterized by the best discriminants create in the space an original sphere of points described by correlation and regression parameters of three ordination axes. Large intra-specific variation of lodicule morphology is a source of flexibility of wheat breeding system.     

Polyphenol oxidase and peroxidase expression in four pineapple varieties (Ananas comosus L.) after a chilling injury

Pineapple internal browning (IB) is a chilling injury that produces enzymatic browning associated with flesh translucency. Pineapple biodiversity allowed the investigation of how polyphenol oxidase (PPO) and peroxidase (POD) activities with their different isoforms are involved in the IB mechanism. Fruits of four varieties that expressed IB symptoms differently, Smooth Cayenne (SCay) and the hybrids MD2, Flhoran 41 (Flh 41), and Flhoran 53 (Flh 53), were stressed by cold. The susceptible varieties showed classical brown spots but different patterns of IB, whereas MD2 and controls showed no IB. Enzymatic activities were measured on fruit protein extracts and PPO and POD isoforms separated on mini-gels (PhastSystem). Only PPO activity was significantly enhanced in the presence of IB. Up to six PPO isoforms were identified in the susceptible varieties. PPO was barely detectable in the nonsusceptible variety MD2 and in controls. The number of PPO isoforms and the total PPO activity after chilling are varietal characteristics.     

rDNA cytogenetics and some structural variability in an <Emphasis Type="Italic">Avena barbata</Emphasis> Pott ex Link × <Emphasis Type="Italic">A. sativa</Emphasis> subsp. <Emphasis Type="Italic">nuda</Emphasis> (L.) Gillet et Magne amphiploid after 5-azaC treatment

The paper reports on the study of DNA methylation patterns in chromosomes of an octoploid selection obtained from an amphiploid Avena barbata × Avena sativa ssp. nuda, their alteration and plant structural changes induced by 5-azacytidine (5-azaC) treatment. Subtelomere/telomere regions and some chromosomes remained heavily methylated after this practise. The increased concentration of 5-azaC strengthened the demethylation process. NOR rDNA loci on five and 5S rDNA doubled loci on three pairs of chromosomes were detected. Some 5S loci were colocalised with NORs. The number of active NORs was increased by one homologous pair after demethylation and this was related to minor loci. The NORs were mainly located on A/D genomes. Patterns of nucleoli fusion varied between main and lateral roots and demethylation increased the number of uninucleolar nuclei. Seed germination was inhibited and plant growth decreased under demethylation. 5-azaC also induced distinct anomalies in endosperm development. Extensive parts of the tissue were composed of defected cells or remained empty. Polyploidised clones of starchy or aleurone cells were observed, as were aleurone cells exhibiting new rare phenotypes.     

Histological and morphometric evaluation of the urethra and penis in male New Zealand White rabbits

This stereudy aimed at performing a histological and morphometric evaluation of the urethra and penis of male rabbits. Seven male New Zealand White rabbits weighing 2.1–3 kg were used in the study. The whole urethra, from the urinary bladder to the external urethral orifice, was dissected from the rabbits, and the tissue was sliced into sections at an interval of 2 mm. The sections were stained with haematoxylin–eosin, Masson–Goldner trichrome stain, Van Gieson's stain and Movat–Russell modified pentachrome stain. A detailed evaluation of the morphology and morphometry was performed. The parameters assessed were the type and height of epithelium, thickness and composition of connective tissue, and thickness and structure of muscularis. The histological structure of the rabbit urethra was found to be similar to humans. However, although the rabbits were found to have the same type of penis as the humans, the internal structure of the corpora cavernosa, the relative thickness of the tunica albuginea and the rudimentary glands of the penis were found to differ in these animals. The results of the present study may be useful in the designing of implants, drug testing or surgical procedures on the physiological and pathological urethra.     

High-pressure effects on the proteolytic enzymes of sea bass (Dicentrarchus labrax L.) fillets

High-pressure processing is a nonthermal technique ensuring food product safety and enabling a longer shelf life. The purpose of this experiment was to evaluate the effect of high pressure on the main proteolytic enzymes involved in fish muscle degradation during storage. Enzymes were extracted with sarcoplasmic proteins from Dicentrarchus labrax sea bass white muscle. Activity of cathepsins B, D, H, and L was quantified in protein extract, whereas calpain activity was evaluated after isolation from its endogenous inhibitor. High-pressure processing up to 500 MPa enhanced the activity of cathepsin B, H, and L, whereas the activity of cathepsin D increased up to 300 MPa and decreased above 300 MPa. With regard to calpain activity, high-pressure processing led to a decrease of activity, which was zero above 400 MPa. We suggest a leading explanation based on simultaneous deactivation of enzymes and an increase of liberation from lysosomes for cathepsins and on dissociation of subunits for calpains.