Influence of biofilm on the production of <Emphasis Type="Italic">Farfantepenaeus paulensis</Emphasis> in pens in the Patos Lagoon estuary

The objective of the present work was to determine the influence of artificial substrates that increase the area for biofilm development on the production performance of Farfantepenaeus paulensis juveniles in pens. Shrimp were stocked at a density of 20/m² in pen structures (bottom area?=?50 m²) that were installed in the Patos Lagoon estuary. Two treatments with three repetitions were analyzed, where artificial substrates (polyethylene nets—1-mm mesh size) were added to increase the area for biofilm development by 100%, and where no substrates were added. During the experimental period, the biomass and the composition of the biofilm were assessed. After 86 days of rearing, no significant differences were found in shrimp performance between the treatments (p?>?0.05). However, the examination of the chlorophyll a, dry weight, and composition of the biofilm indicated that the shrimp were actively consuming the biofilm attached to the artificial substrates. Significant decreases in the abundances of nematodes >?500 μm after the 56th day and of tintinnids and rotifers between day 28 and day 42, indicated that the shrimp were selectively predating on these organisms. Moreover, a decrease in the chlorophyll a concentration in the biofilm suggests that the shrimp were consuming the microalgae. Although the increase in the area for biofilm development did not improve shrimp performance, the shrimp presented the highest growth rates when they consumed most of the biofilm microorganisms.     

Alien species of aphids (Hemiptera: Aphididae) found in Serbia,new to the Balkan Peninsula

New alien species of aphids (Illinoia liriodendri (Monell), Wahlgreniella nervata (Gillete), Takecallis arundicolens (Clarke) and Tinocallis takachihoensis Higuchi) have been found for the first time in Serbia. These records are new for the Balkan Peninsula. Data of Ericaphis scammelli (Mason), species recently mentioned in Serbia, are also presented in the text. The species have been found during the last five years at four sites (Belgrade, Zemun, Mladenovac and Bojnik) on five cultivated plants. Ericaphis scammelli is a pest of blueberry and a vector of Blueberry scorch virus. The other four develop colonies on decorative plants: I. liriodendri has been found on Liriodendron tulipifera, W. nervata on Rosa sp., T. arundicolens on Pseudosasa japonica and T. takachihoensis on Ulmus x hollandica. The origin of three of the species (E. scammelli, I. liriodendri and W. nervata) is North America and two (T. arundicolens and T. takachihoensis) have come from East Asia. Their morphology, biology and the damage they inflict are discussed here, as well as their potential economic and environmental threat. Only parthenogenetic viviparous females of all 5 species have been collected. Their biology has not been studied enough in Europe and needs further examination. Original drawings of all species are presented.     

Genetic diversity of rhizobia associated with alfalfa in Serbian soils

We have evaluated the genetic diversity and phylogeny of alfalfa rhizobia, originating from different types of soils in Serbia and their ability to establish an effective symbiosis with alfalfa (Medicago sativa L.). A collection of 65 strains isolated from root nodules of alfalfa were characterized by rep-PCR analysis, partial and complete 16S rDNA gene and recA gene sequencing, as well as atpD gene sequencing and DNA–DNA hybridizations. The results of the sequence analyses revealed that Sinorhizobium meliloti is the dominant species in alfalfa nodules. Only one strain was identified as Sinorhizobium medicae, two strains as Rhizobium tibeticum and one strain as Rhizobium sp. Despite the fact that the majority of strains were identified as S. meliloti, a high genetic diversity at strain level was detected. Almost all isolates shared the ability to nodulate and fix nitrogen with M. sativa, except 11 of them, which were incapable of fixing nitrogen with this species. About 50% of the isolates showed values of symbiotic effectiveness (SE) above 50%, while 10% of the strains were highly effective with SE values above 70%. Some of the strains which were highly effective in nitrogen fixation at the same time could intensively solubilize phosphates, offering a possibility for multipurpose inoculum development. This was the first genetic study of rhizobia isolated from this region and also the first report of natural presence of R. tibeticum in root nodules of M. sativa.     

New aphid species for italy caught by suction trap

Six aphid species new for Italy were caught by suction trap in the Friuli-Venezia Giulia region, Italy. They are:Chaetosiphon chaetosiphon (Nevsky),Illinoia morrisoni (Swain),Myzodium modestum (Hottes),Pseudacaudella rubida (Börner),Schizaphis longicaudata Hille Ris Lambers andTrichosiphonaphis (Xenomyzus)polygonifoliae (Shinji). All species are provided here with characteristic morphological information and line drawings.     

Supplementation with bypass fat in silvopastoral systems diminishes the ratio of milk saturated/unsaturated fatty acids

This study was conducted to evaluate if supplementing bypass fat to cows under silvopastoral systems, increases the concentration of unsaturated fatty acids in milk, thus improving the saturated/unsaturated ratio without a negative effect on total milk yield in fat or protein. Two concentrations of two different sources of bypass fat were evaluated for 40 days, each in a group of 24 multiparous Lucerna (Colombian breed) cows. A cross-over design of 8 Latin squares 3 × 3.was used The variables submitted to analysis were body condition, daily milk production and milk composition. Body condition, milk yield and milk quality were not different but there was a significant decrease in the amount of saturated fatty acid in both experiments while the unsaturated fat increased significantly in experiment 1 and remained stable in experiment 2. Results, such as these have as far as we know, not been reported previously and they provide an approach for the improvement of milk as a “functional food”.     

Weed control modifies Tuber melanosporum mycelial expansion in young oak plantations

Context

Black truffle (Tuber melanosporum) cultivation is a promising agro-forestry alternative for Mediterranean rural areas, but adequate weed control at seedling establishment still remains a challenge in black truffle plantations.

Aims

The aim of this study is to evaluate the effects of several weed control strategies on early development of Quercus ilex seedlings and the symbiotic T. melanosporum.

Materials and methods

In a young black truffle-inoculated holm oak plantation, we assessed for 3 years the effects of two types of mechanical weed control and five mulches in a young Q. ilex plantation inoculated with T. melanosporum. Herbaceous cover, seedling growth and abundance of T. melanosporum mycelium, based on PCR analysis of soil DNA extracts using T. melanosporum-specific primers, were estimated to determine the effectiveness of these treatments in controlling weeds and supporting the growth of both the host tree and the target fungus.

Results

The amount of T. melanosporum mycelium in the soil 30 cm around the seedlings was larger under double-layer white mulch than in the rest of treatments tested. Under the white colour mulches, which had the largest light reflection, we registered the cooler soil temperature, and the best weed control was observed on the single- and double-layer black truffles and double-layer white mulch.

Conclusion

The effects of double-layer white mulch on herbaceous cover, soil temperature, reflected light, and the expansion of T. melanosporum bring us closer to being able to substitute traditional tilling of truffle orchards for the less expensive mulching treatments.     

Peptide neurotoxins from fish-hunting cone snails

To paralyze their more agile prey, the venomous fish-hunting cone snails (Conus) have developed a potent biochemical strategy. They produce several classes of toxic peptides (conotoxins) that attack a series of successive physiological targets in the neuromuscular system of the fish. The peptides include presynaptic omega-conotoxins that prevent the voltage-activated entry of calcium into the nerve terminal and release of acetylcholine, postsynaptic alpha-conotoxins that inhibit the acetylcholine receptor, and muscle sodium channel inhibitors, the mu-conotoxins, which directly abolish muscle action potentials. These distinct peptide toxins share several common features: they are relatively small (13 to 29 amino acids), are highly cross-linked by disulfide bonds, and strongly basic. The fact that they inhibit sequential steps in neuromuscular transmission suggests that their action is synergistic rather than additive. Five new omega-conotoxins that block presynaptic calcium channels are described. They vary in their activity against different vertebrate classes, and also in their actions against different synapses from the same animal. There are susceptible forms of the target molecule in peripheral synapses of fish and amphibians, but those of mice are resistant. However, the mammalian central nervous system is clearly affected, and these toxins are thus of potential significance for investigating the presynaptic calcium channels.     

Extruded Flaxseed Meal Enhances the Nutritional Quality of Cereal-based Products

Human consumption of flaxseed is increasing due to its health benefit properties and extrusion processes can enhance its nutritional quality. Extruded flaxseed meal (EFM) obtained in a pilot plant was characterized and incorporated in flour mixes and cereal-based bars to demonstrate its nutritious usefulness. Amino acid content was not affected by extrusion and, despite lysine was the limitating amino acid, the chemical score (CS) was 83 %. Thiamin and riboflavin decreased slightly as consequence of extrusion, phytic acid did not change and trypsin inhibitor activity was undetectable. Proximate composition and nutritional quality determined by biological and chemical indexes were compared among EFM, flour mixes (FM) and cereal bars (CB). They presented high protein levels (26, 20 and 17 %, respectively), good biological value (BV) (80, 79 and 65, respectively), acceptable true protein digestibility (TD) (73, 79 and 78, respectively), and high dietary fiber (33, 20.5 and 18 %, respectively). The ratio of ω6:ω3 for CB was within the WHO/FAO recommendations. These results open a new venue for the usefulsess of nutritious/healthy extruded flaxseed flours into ready-to-eat cereal-based products with improved nutritional quality.     

Genetics of resistance to wheat leaf rust, stem rust, and powdery mildew in Aegilops sharonensis

Aegilops sharonensis (Sharon goatgrass) is a wild relative of wheat and a rich source of genetic diversity for disease resistance. The objectives of this study were to determine the genetic basis of leaf rust, stem rust, and powdery mildew resistance in A. sharonensis and also the allelic relationships between genes controlling resistance to each disease. Progeny from crosses between resistant and susceptible accessions were evaluated for their disease reaction at the seedling and/or adult plant stage to determine the number and action of genes conferring resistance. Two different genes conferring resistance to leaf rust races THBJ and BBBB were identified in accessions 1644 and 603. For stem rust, the same single gene was found to confer resistance to race TTTT in accessions 1644 and 2229. Resistance to stem rust race TPMK was conferred by two genes in accessions 1644 and 603. A contingency test revealed no association between genes conferring resistance to leaf rust race THBJ and stem rust race TTTT or between genes conferring resistance to stem rust race TTTT and powdery mildew isolate UM06-01, indicating that the respective resistance genes are not linked. Three accessions (1644, 2229, and 1193) were found to carry a single gene for resistance to powdery mildew. Allelism tests revealed that the resistance gene in accession 1644 is different from the respective single genes present in either 2229 or 1193. The simple inheritance of leaf rust, stem rust, and powdery mildew resistance in A. sharonensis should simplify the transfer of resistance to wheat in wide crosses.