Effect of silver nanoparticles on growth performance, metabolism and microbial profile of broiler chickens

This study evaluated the potential of silver nanoparticles (AgNano) as an antimicrobial growth-promoting supplement for broiler chickens. One hundred forty-four seven-day-old broiler chicks were distributed randomly to AgNano treatments at 0, 10 and 20 mg/kg (Control, Group AgNano10, and Group AgNano20, respectively) provided via the drinking water from day 7 to 36 post-hatching. Body weight and feed consumption were measured weekly. In addition, balance and respiration experiments were carried out to determine nitrogen (N) utilisation and energy retention. At days 22 and 36, blood samples and intestinal content were collected to evaluate the effects of AgNano on plasma concentration of immunoglobulins and the intestinal microflora, respectively. The provision of water solutions containing different concentrations of AgNano had no effect on postnatal growth performance and the energy metabolism of broiler chickens. However, in Group AgNano10 N intake (p = 0.05) and retention (p = 0.03) was increased, but N excretion and efficiency of utilisation was not affected. The populations of bacteria in the intestinal samples were not affected by AgNano supplementation. The concentration of immunoglobulin (IgG) in the blood plasma of broilers supplemented with AgNano decreased at day 36 (p = 0.012). The results demonstrated that AgNano affects N utilisation and plasma IgG concentration; however, it does not influence the microbial populations in the digestive tract, the energy metabolism and growth performance of chickens.     

The macrocyclizing protease butelase 1 remains autocatalytic and reveals the structural basis for ligase activity

Plant asparaginyl endopeptidases (AEPs) are expressed as inactive zymogens that perform maturation of seed storage protein upon cleavage‐dependent autoactivation in the low‐pH environment of storage vacuoles. The AEPs have attracted attention for their macrocyclization reactions, and have been classified as cleavage or ligation specialists. However, we have recently shown that the ability of AEPs to produce either cyclic or acyclic products can be altered by mutations to the active site region, and that several AEPs are capable of macrocyclization given favorable pH conditions. One AEP extracted from Clitoria ternatea seeds (butelase 1) is classified as a ligase rather than a protease, presenting an opportunity to test for loss of cleavage activity. Here, making recombinant butelase 1 and rescuing an Arabidopsis thaliana mutant lacking AEP, we show that butelase 1 retains cleavage functions in vitro and in vivo. The in vivo rescue was incomplete, consistent with some trade‐off for butelase 1 specialization toward macrocyclization. Its crystal structure showed an active site with only subtle differences from cleaving AEPs, suggesting the many differences in its peptide‐binding region are the source of its efficient macrocyclization. All considered, it seems that either butelase 1 has not fully specialized or a requirement for autocatalytic cleavage is an evolutionary constraint upon macrocyclizing AEPs.     

Interaction of Discoidin Domain Receptor 1 with a 14-3-3-Beclin-1-Akt1 Complex Modulates Glioblastoma Therapy Sensitivity

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First evidence of hybridization between endangered sterlets (Acipenser ruthenus) and exotic Siberian sturgeons (Acipenser baerii) in the Danube River

Most natural populations of Eurasian sturgeons have declined dramatically during recent decades, reaching historic low levels today. During the same period, sturgeon has become very popular in European aquaculture. Because many hatcheries are located near rivers, their unintentional escape is often documented, especially during floods. Until now, no cases of successful hybridization of these escaped fish with wild stocks have been reported. In this study, the genetic structure of a highly threatened population of sterlets (Acipenser ruthenus) from the Upper Danube was analysed as a requirement for their conservation. Surprisingly, we observed genotypes and morphotypes of Siberian sturgeon (Acipenser baerii), as well as hybrids between this species and native sterlets. This hybridization poses a serious threat for the survival of this isolated sterlet population in the upper part of the Danube. For the first time, natural reproduction is documented for Siberian sturgeon outside their natural range in Europe. This finding demonstrates the risk of extinction by hybridisation of endangered populations. We would like to stress that taking into consideration the risks for native sturgeon populations, farmed sturgeon should not be released into the wild, and all measures should be taken to prevent their accidental escape.     

Secondary metabolites in Cladina stellaris in relation to reindeer grazing and thallus nutrient content

We analysed concentrations of phenols and key macro-nutrients in a dominant mat-forming lichen, Cladina stellaris, in dry heath forests subjected to heavy reindeer grazing in Finnish Lapland. Lichen samples were collected in the beginning of two growth seasons from six to eight sites with old reindeer exclosures that served as control plots within sites. The concentration of perlatolic acid in lichen apices (top 10 mm) was higher in grazed plots than in control ones, whereas usnic acid did not seem to respond unequivocally to grazing. Moreover, there was a strong negative relationship between nitrogen and phenolic content of Cladina stellaris in intact plots but this relationship was absent in grazed ones. Changes in nitrogen and phosphorus contents caused by reindeer grazing were not correlated with changes in the level of phenolics in lichen thalli. The present result demonstrated that the carbon-nutrient balance (CNB) hypothesis may well explain some of the variation in lichen phenolic content but is not sufficient for explaining changes caused by reindeer grazing. We hypothesized that physical changes in the lichen microenvironment induced by reindeer have more profound impact on lichen phenolic content than alterations in thallus nutrient content.     

Characteristics and DNA-Sequence of a Cryptic Haloalkanoic Acid Dehalogenase from Agrobacterium tumefaciens RS5

Agrobacterium tumefaciens RS5 harbors two different hydrolytic haloalkanoic acid dehalogenase genes, one coding for a nonstereospecific enzyme (DhlS5II) and a second for a cryptic L-isomer-specific dehalogenase (DhlS5I). The latter gene was cloned and expressed in Escherichia coli. Biochemical characterization and sequence analysis of dhlS5I shows its membership to the class of the L-isomer-specific hydrolytic dehalogenases. Highest homology of 72% was found to the dehalogenase LdexYL from Pseudomonas sp. YL. Both enzymes share an unusual high temperature optimum of 65°C. Controlled by a vector promoter, high specific dehalogenase activities up to 32 U mg⁻¹ protein were obtained in E. coli, and putatively, owing to its own σ⁷⁰-dependent promoter, a constitutive low-level expression of dhlS5I of 0.4 U mg⁻¹ protein was measured. Received: 27 June 1997 / Accepted: 4 August 1997     

Fiber digestibility in juvenile Galapagos tortoises (Geochelone nigra) and implications for the development of captive animals

Digestive strategies have been recognized to be a key factor for healthy growth in juvenile Galapagos giant tortoises (Geochelone nigra). The aim of present study was to investigate digestive coefficients with special regard to fiber fractions. Four captive bred Galapagos giant tortoises 4–5 years of age were fed a controlled diet for 32 days. The diet consisted of 77% hay, 15% tortoise pellets, and 8% apples on a dry matter basis. On a dry matter basis diet analysis showed: 95.7% organic matter, 11.3% crude protein, 20.5% crude fiber, 22.6% acid detergent fiber, 5.0% acid detergent lignin, and 17.6% cellulose. Based on total fecal collection during 7 days average dry matter digestibilities were calculated: 65% for dry matter, 67% for organic matter, 63% for crude protein, 55% for crude fiber, 49% for acid detergent fiber, 41% for acid detergent lignin, 54% for cellulose. An increase in crude fiber content resulted in a reduced digestibility in comparative evaluations of data for different tortoise species, and in a comparison of tortoises and mammalian hindgut fermenters. Compared to some mammalian hindgut‐fermenting herbivore species (domestic horses, Asian elephants, Indian rhinoceroses) on a diet of hay and concentrates, the juvenile Galapagos giant tortoises showed a digestion of similar efficiency. If a reduction in dietary digestibility is warranted in juvenile Galapagos giant tortoises, it is concluded that dietary fiber levels should be increased and it is proposed that crude fiber levels of 30–40% on a dry matter basis should be achieved. Zoo Biol 24:185–191, 2005. © 2005 Wiley‐Liss, Inc.     

Nitrosative stress leads to protein glutathiolation, increased s-nitrosation, and up-regulation of peroxiredoxins in the heart

Nitric oxide (NO) is produced by different isoforms of nitric oxide synthases (NOSs) and operates as a mediator of important cell signaling pathways, such as the cGMP signaling cascade. Another mechanism by which NO exerts biological effects is mediated through S-nitrosation of target proteins. To explore thiol-based protein modifications in a situation of defined nitrosative stress, we used a transgenic mouse model with cardiac specific overexpression of inducible nitric oxide synthase (iNOS) and concomitant myoglobin deficiency (iNOS(+)/myo(-/-)). In comparison with the wild type hearts, protein glutathiolation detected by immunoblotting was significantly enhanced in iNOS(+)/myo(-/-) hearts, whereas protein S-nitrosation as measured by the biotin switch assay and two-dimensional PAGE revealed that nearly all of the detected proteins ( approximately 60) remained unchanged with the exception of three proteins. Tandem mass spectrometry revealed these proteins to be peroxiredoxins (Prxs), which are known to possess peroxidase activity, whereby hydrogen peroxide, peroxynitrite, and a wide range of organic hydroperoxides are reduced and detoxified. Immunoblotting with specific antibodies revealed up-regulation of Prx VI in the iNOS(+)/myo(-/-) hearts, whereas expression of Prx II and Prx III remained unchanged. Furthermore, the analysis of the cardiac S-nitrososubproteome identified several new proteins possibly being involved in NO-signaling pathways. Our data indicate that S-nitrosation and glutathiolation of cardiac proteins may contribute to the phenotype of NO-induced heart failure. The up-regulation of antioxidant proteins like Prx VI appears to be an additional mechanism to antagonize an excess of reactive oxygen/nitrogen species. Furthermore, S-nitrosation of Prxs may serve a new function in the signaling cascade of nitrosative stress.     

Croton campanulatus (Euphorbiaceae s.s.), a new species from the Brazilian Atlantic rain forest

Croton campanulatus, a new species from southeastern Brazil in the states of Minas Gerais and Rio de Janeiro, is here described and illustrated. Morphological data indicate that this species belongs to Croton section Cleodora based on its arborescent habit, pistillate flowers with imbricate sepals, reduced petals, and multifid styles that are fused at the base.     

The LPS receptor, CD14, in experimental autoimmune encephalomyelitis and multiple sclerosis.

Innate immune receptors are crucial for defense against microorganisms. Recently, a cross-talk between innate and adaptive immunity has been considered. Here, we provide first evidence for a role of the key innate immune receptor, LPS receptor (CD14) in pathophysiology of experimental autoimmune encephalomyelitis, the animal model of multiple sclerosis. Indicating a functional importance in vivo, we show that CD14 deficiency increased clinical symptoms in active experimental autoimmune encephalomyelitis. Consistent with these observations, CD14 deficient mice exhibited a markedly enhanced infiltration of monocytes and neutrophils in brain and spinal cord. Moreover, we observed an increased immunoreactivity of CD14 in biopsy and post mortem brain tissues of multiple sclerosis patients compared to age-matched controls. Thus, the key innate immune receptor, CD14, may be of pathophysiological relevance in experimental autoimmune encephalomyelitis and multiple sclerosis.