Isolation and characterization of acetonitrile utilizing bacteria

Summary Bacteria utilizing high concentrations of acetonitrile as the sole carbon source were isolated and identified asChromobacterium sp. andPseudomonas aeruginosa. Maximum growth was attained after 96 h of incubation andP. aeruginosa grew slightly faster thanChromobacterium sp. The strains were able to grow and oxidize acetonitrile at concentrations as high as 600 mM. However, higher concentrations inhibited growth and oxygen uptake. Degradation studies with (¹⁴C)acetonitrile indicated 57% of acetonitrile was degraded byPseudomonas aeruginosa as compared to 43% byChromobacterium. The isolates utilized different nitrile compounds as carbon substrates.     

Synthesis of 3'-deoxy-3'-C-methyl nucleoside derivatives

2',3'-Dideoxy-3'-C-methyl nucleosides bearing the five naturally occurring nucleic acid bases were synthesized. Additionally, the 3'-deoxy-3'-C-methyl nucleoside analogues bearing 5-aminoimidazole-4-carboxamide as well as 1,2,4-triazole-3-carboxamide moieties were prepared. The synthesis of the corresponding 2',3'-dideoxy-3'-C-methyl triazole derivative was also accomplished. The dideoxynucleoside derivatives were prepared by radical deoxygenation from their 3'-deoxy-3'-C-methyl parent ribonucleosides. When evaluated for their antiviral activity in cell culture experiments, none of these compounds showed any significant antiviral activity.     

Hydrogen peroxide generated by over-expression of cytosolic superoxide dismutase in transgenic plums enhances bacterial canker resistance and modulates plant defence responses

Molecular Biology Reports - H2O2 generated during the oxidative burst, plays important roles in plant defenses responses against pathogens. In this study we examined the role of H2O2 on bacterial...     

Maize root responses to drought stress depend on root class and axial position

In this study we tested the hypotheses that root classes would exhibit distinctive anatomical and architectural responses to drought stress, and that those responses would vary along the root axes. The root systems of four maize (Zea mays L.) sweet corn genotypes designated SC1, SC2, SC3 and SC4 were phenotyped under well-watered and drought treatments in greenhouse mesocosms, permitting increasing stratification of moisture availability as the drought progressed. Anatomical and architectural responses to drought were evaluated for each root class. Lignin distribution was assessed by image processing of UV-illuminated root cross-sections acquired by laser ablation tomography. The two cultivars with less biomass reduction under drought, SC3 and SC4, substantially enhanced lateral root development along the apical segments of axial roots when plants were grown with drought stress. These segments grew into the deeper part of the mesocosm where more moisture was available. Apical segments of the axial and large lateral roots from drought-stressed plants were thicker and had greater theoretical axial water conductance than basal segments, especially in SC3 and SC4. Basal segments of crown roots of SC3 and SC4 showed increased lignification of the stele under drought. Root anatomical and architectural responses to drought are complex and vary among cultivars and root classes, and along root axes. Drought-induced proliferation of lateral roots on apical segments of axial roots would be expected to enhance deep water acquisition, while lignification of axial roots could help preserve axial water transport.

     

Food partitioning and spatial subsidy in shelter‐limited fishes inhabiting patchy reefs of Patagonia

The diets of the most conspicuous reef‐fish species from northern Patagonia, the carnivorous species Pseudopercis semifasciata, Acanthistius patachonicus, Pinguipes brasilianus and Sebastes oculatus were studied. Pinguipes brasilianus had the narrowest diet and most specialized feeding strategy, preying mostly on reef‐dwelling organisms such as sea urchins, limpets, bivalves, crabs and polychaetes. The diet of A. patachonicus was characterized by the presence of reef and soft‐bottom benthic organisms, mainly polychaetes, crabs and fishes. Pseudopercis semifasciata showed the broadest spectrum of prey items, preying upon reef, soft‐bottom and transient organism (mainly fishes, cephalopods and crabs). All S. oculatus guts were empty, but stable‐isotope analyses suggested that this species consumed small fishes and crabs. In general, P. brasilianus depended on local prey populations and ate different reef‐dwelling prey than the other species. Pseudopercis semifasciata, A. patachonicus and probably S. oculatus, however, had overlapping trophic niches and consumed resources from adjacent environments. The latter probably reduces the importance of food as a limiting resource for these reef‐fish populations, facilitating their coexistence in spite of their high trophic overlap.     

Androgen receptors in coeliac ganglion in late pregnant rat

The ovarian function is controlled by endocrine factors and neural influence. In late pregnant rat, androstenedione, from the coeliac ganglion, has a luteotrophic effect in the ex vivo coeliac ganglion-superior ovarian nerve-ovary system. In this work we investigate the presence of androgen receptors in the coeliac ganglion of late pregnant rats by immunohistochemistry. We also explore, from a physiological point of view, the potential participation of these receptors in the androstenedione ganglionic action on progesterone release and metabolism, as well as on nitrites release in the ovary compartment. The coeliac ganglion was isolated after being fixed in situ and immunohistochemistry was performed. In the system, three experimental groups were used with the addition of (a) androstenedione, (b) flutamide, and (c) androstenedione plus flutamide in the ganglion compartment. Progesterone and nitrite concentrations were determined in the ovary compartment at different incubation times. Corpora lutea samples isolated at the end of incubation were used to determine the expressions and activities of the progesterone synthesis (3β-hydroxysteroid-dehydrogenase, 3β-HSD) and degradation (20α-hydroxysteroid-dehydrogenase, 20α-HSD) enzymes. Immunohistochemistry revealed cytoplasmatic androgen receptor immunoreactivity in neural somas in the coeliac ganglion. In the coeliac ganglion-superior ovarian nerve-ovary system, androstenedione addition increased 3β-HSD and decreased 20α-HSD, showed a tendency to decrease 20α-HSD expression, and increased nitrites release in relation to control. Androstenedione plus flutamide decreased progesterone and nitrites release in relation to the androstenedione group. This work demonstrates the presence of androgen receptors in neurons of celiac ganglion and provides evidence for the luteotrophic action of androstenedione via a neural pathway that may be mediated by these receptors.     

TP53 mutations in colorectal cancer from Tunisia: relationships with site of tumor origin,microsatellite instability and KRAS mutations

Loss of TP53 function through gene mutation is a critical event in the development and progression of colorectal cancer (CRC). Here we examined 51 primary CRC tumors from Tunisia for mutations in TP53 exons 4–9 using PCR-direct sequencing. TP53 status and mutation site/type were than correlated with nuclear protein accumulation, familial and clinicopathologic variables and data on KRAS mutations and microsatellite instability (MSI-H). The TP53 mutation analysis was possible in the tumor of 47 patients and a deleterious somatic mutation has been detected in 59.6 % of the patients (28/47) including 20 (71.4 %) missense mutations, 7 nonsense mutations (25 %) and 1 (3.6 %) frameshift mutation. 89.3 % (25/28) of the detected mutations were in exons 5–8, whereas 10.7 % (3/28) were in exon 4. Among the 27 non frameshift mutations, 89 % (24/27) were transitions and 11 % (3/27) were transversions. 64.3 % (18/27) of the altered amino acids corresponded to arginine. 74 % (20/27) were G>C to A>T transitions, and more than half (14/27) occur at hotspots codons with CpG sites. TP53 mutations correlated closely with TP53 accumulation (p = 0.0090) and inversely with MSI phenotype (p = 0.0658). A KRAS somatic mutation was identified in 25 % (7/28) of the TP53 mutated tumors. All these mutations were G>A transitions in codon 12 and all the tumors with combined alterations but one were distally located and MSS. In conclusion, frequency and types of TP53 mutations and correlations with TP53 protein accumulation, and MSI were as reported for non-Tunisian patients. However, no significant associations have been detected between TP53 mutations and clinicopathological data in Tunisian patients as previously reported.     

Disturbance-dependent Yellow-legged Gull (Larus michahellis) predation on Larid chicks decreases with chick age

Predation is one of the key factors shaping the dynamics of animal populations. In birds, nest loss due to predation can be a significant cause of low reproductive success. Ground-nesting birds are among the bird groups most susceptible to predation, mainly because their nests are easily accessible to a broad suite of potential predators. For these birds, anthropogenic disturbances can generate changes in nest predation risk by altering their antipredator behaviour and also by altering the behaviour of the predator species, i.e. the predator becoming much more aware of predation opportunities due to frequent disturbances and/or motivated to repeat predation attempts when some are successful. To date, most previous studies investigating this have focused on a single effect, either predation or disturbance, on chick survival. It remains unknown how the risk of predation with and without disturbance varies with chick age. In this study, we used behavioural observations to assess how the interaction between predators and disturbance affects predation risk in chicks and how this interacts with chick age. Specifically, we investigated the effect of disturbance caused by humans and stray dogs on the predation of Slender-billed Gull Chroicocephalus genei chicks by Yellow-legged Gulls Larus michahellis, and whether this depended on the age of the chicks. Our results revealed that disturbance had a significant positive effect on predation measures of Slender-billed Gull chicks by Yellow-legged Gulls, but that this effect was mediated both by disturbance type and the age of chicks. Stray dogs entering the colony had a stronger disturbance effect on chicks than passing humans, increasing predation risk by Yellow-legged Gulls. Our results also showed that chick age interacts with disturbance type to determine the predation risk. This is probably mediated by chicks' capacity to escape predation by gathering in a single large crèche that runs into the water when disturbed. To preserve Slender-billed Gull colonies in one of its few remaining breeding sites in Tunisia, and as gulls tend to react even when the disturbance occurs relatively far from the colonies, it is crucial to (1) restrict human access to dikes and islets where large colonies breed and (2) construct artificial islets attractive to gulls and inaccessible to stray dogs.     

Physiological and biochemical changes in different sugar beet genotypes infected with root-knot nematode

Ten genotypes of sugar beet plant either monogerm or multigerm seeds were screened under greenhouse conditions for both susceptibility and biochemical reaction to root-knot nematode (RKN) Meloidogyne incognita. All the tested genotypes were susceptible to nematode infection according to the number of root galls and gall indices. All infected genotypes exhibited significant reduction in chlorophyll a, b and carotenoids compared to non-infected ones. The total indole acetic acid and total phenolic compounds contents (mean of both shoot and root) increased significantly in most infected genotypes compared to non-infected genotypes except Disk-01-99 and Monte Rosa as well as LP16 and LP15 genotypes, respectively. Also, total polyamine contents (putrescine, spermidine and spermine) showed significant increases in response to infection with nematodes in all genotypes. The same trend was observed in lipid peroxidation expressed with malondialdehyde content in all tested genotypes. Activities of polyphenol oxidase, peroxidase, superoxide dismutase and catalase enzymes were also induced in most infected genotypes compared with non-infected genotypes. Generally, infection with RKNs induced the appearance of new protein bands at molecular masses 303, 288, 42 and 37?KDa in all infected genotypes. The differentiation in the appearance and/or disappearance of protein bands according to susceptibility to infection reflects the variation between genotypes in defense against infection.     

Inactivation of template-directed misfolding of infectious prion protein by ozone

Misfolded prions (PrP(Sc)) are well known for their resistance to conventional decontamination processes. The potential risk of contamination of the water environment, as a result of disposal of specified risk materials (SRM), has raised public concerns. Ozone is commonly utilized in the water industry for inactivation of microbial contaminants and was tested in this study for its ability to inactivate prions (263K hamster scrapie = PrP(Sc)). Treatment variables included initial ozone dose (7.6 to 25.7 mg/liter), contact time (5 s and 5 min), temperature (4°C and 20°C), and pH (pH 4.4, 6.0, and 8.0). Exposure of dilute suspensions of the infected 263K hamster brain homogenates (IBH) (0.01%) to ozone resulted in the in vitro destruction of the templating properties of PrP(Sc), as measured by the protein misfolding cyclic amplification (PMCA) assay. The highest levels of prion inactivation (≥4 log(10)) were observed with ozone doses of 13.0 mg/liter, at pH 4.4 and 20°C, resulting in a CT (the product of residual ozone concentration and contact time) value as low as 0.59 mg · liter(-1) min. A comparison of ozone CT requirements among various pathogens suggests that prions are more susceptible to ozone degradation than some model bacteria and protozoa and that ozone treatment may be an effective solution for inactivating prions in water and wastewater.