Isolation and characterization of a fluorene-degrading bacterium: identification of ring oxidation and ring fission products.

An Arthrobacter sp. strain, F101, able to use fluorene as the sole source of carbon and energy, was isolated from sludge from an oil refinery wastewater treatment plant. During growth in the presence of fluorene, four major metabolites were detected and isolated by thin-layer chromatography and high-performance liquid chromatography. 9-Fluorenol, 9H-fluoren-9-one, and 3,4-dihydrocoumarin were identified by UV spectra, mass spectrometry, and 300-MHz proton nuclear magnetic resonance. The fourth metabolite has been characterized, but precise identification was not possible. Since strain F101 is not able to grow with fluorenone, two different pathways of fluorene biodegradation are suggested: one supports cell growth and produces 3,4-dihydrocoumarin as an intermediate and probably the unidentified metabolite, and the other produces 9-fluorenol and 9H-fluoren-9-one and appears to be a dead-end route.     

Observation of correlated X-ray scattering at atomic resolution

Tools to study disordered systems with local structural order, such as proteins in solution, remain limited. Such understanding is essential for e.g. rational drug design. Correlated X-ray scattering (CXS) has recently attracted new interest as a way to leverage next-generation light sources to study such disordered matter. The CXS experiment measures angular correlations of the intensity caused by the scattering of X-rays from an ensemble of identical particles, with disordered orientation and position. Averaging over 15 496 snapshot images obtained by exposing a sample of silver nanoparticles in solution to a micro-focused synchrotron radiation beam, we report on experimental efforts to obtain CXS signal from an ensemble in three dimensions. A correlation function was measured at wide angles corresponding to atomic resolution that matches theoretical predictions. These preliminary results suggest that other CXS experiments on disordered ensembles—such as proteins in solution—may be feasible in the future.     

Magnetic Resonance Imaging Assessment of Effective Ablated Volume following High Intensity Focused Ultrasound

Under magnetic resonance (MR) guidance, high intensity focused ultrasound (HIFU) is capable of precise and accurate delivery of thermal dose to tissues. Given the excellent soft tissue imaging capabilities of MRI, but the lack of data on the correlation of MRI findings to histology following HIFU, we sought to examine tumor response to HIFU ablation to determine whether there was a correlation between histological findings and common MR imaging protocols in the assessment of the extent of thermal damage. Female FVB mice (n = 34), bearing bilateral neu deletion tumors, were unilaterally insonated under MR guidance, with the contralateral tumor as a control. Between one and five spots (focal size 0.5 × 0.5 × 2.5 mm³) were insonated per tumor with each spot receiving approximately 74.2 J of acoustic energy over a period of 7 seconds. Animals were then imaged on a 7T MR scanner with several protocols. T1 weighted images (with and without gadolinium contrast) were collected in addition to a series of T2 weighted and diffusion weighted images (for later reconstruction into T2 and apparent diffusion coefficient maps), immediately following ablation and at 6, 24, and 48 hours post treatment. Animals were sacrificed at each time point and both insonated/treated and contralateral tumors removed and stained for NADH-diaphorase, caspase 3, or with hematoxylin and eosin (H&E). We found the area of non-enhancement on contrast enhanced T1 weighted imaging immediately post ablation correlated with the region of tissue receiving a thermal dose CEM43 ≥ 240 min. Moreover, while both tumor T2 and apparent diffusion coefficient values changed from pre-ablation values, contrast enhanced T1 weighted images appeared to be more senstive to changes in tissue viability following HIFU ablation.     

West Nile Complement Fixing antibodies in Nigerian domestic animals and humans

A survey for West Nile Complement Fixing (CF) antibody was carried out in humans and domestic animals in Nigeria. Human sera were obtained from two communities namely Ibadan and Ogbomoso but animal sera were collected from Ibadan and Maiduguri. The overall CF antibody to West Nile virus in the two localities surveyed was 65%. Of 170 persons tested, 53% and 75% were positive in Ibadan and Ogbomoso respectively. Antibody prevalence increased with age in both communities. Tests for antibody against other flaviviruses revealed that monotypic complement fixation reactions were found frequently in young people, but broadly reacting sera were common among the older age groups. Sex distribution of West Nile CF antibody showed that 49/82 (60%) of females and 62/88 (75%) of males had West Nile CF antibody. Tests on animal sera showed that 33% contained CF antibody to West Nile virus. Prevalence of CF antibody in different animal species was 62% in camels, 4% in cattle and 0% in goats.     

Comparison of the cytotoxic potency of T101 Fab, F(ab')2 and whole IgG immunotoxins

The in vitro killing of the human CEM cell line was studied by using ricin A-chain immunotoxins constructed with either the whole IgG or the Fab and F(ab')2 fragments of the same T101 (anti-CD5) antibody. In the presence of ammonium chloride as an activator, the "whole" immunotoxin as well as the "fragment" immunotoxins did not show any significant difference in the cell killing efficacy. In contrast, without the activator, the efficacy of the T101 immunotoxin was greatly improved when fragments were used. Indeed, at a saturating dose, a cytoreduction of three orders of magnitude was obtained with the fragment immunotoxins vs less than one order of magnitude for the whole immunotoxin, as assessed in a clonogenic assay. This enhancing effect was related to better cell killing kinetics, because with a similar amount of A-chain molecules bound per cell, T101 fragment immunotoxins achieved a twofold faster protein synthesis inactivation rate than the corresponding whole IgG immunotoxin. No significant difference in activity was shown between monovalent (Fab) and divalent (F(ab')2) forms of fragment immunotoxins. The observation that T101 fragment immunotoxins were more potent than intact immunotoxins was extended to another fragment immunotoxin constructed with an antibody (F111.98) directed against a different epitope of the CD5 Ag. In another model (anti-CD22 1G11 antibody on Raji cells), the fragment immunotoxin did not show any superiority over the IgG immunotoxin which was by itself very potent, strongly suggesting an Ag-dependent phenomenon.     

Rhinoceros Auklet pair‐mates migrate independently but synchronize their foraging activity during the pre‐laying period

Pair bonds are considered important for successful breeding in monogamous birds but their maintenance may be challenging for migratory species, as mates can be separated for months during the non‐breeding period. To investigate whether mates of monogamous migratory seabirds stay together throughout the non‐breeding period and how and when they start synchronizing their activity before breeding, we tracked seven pairs and 22 individuals of Rhinoceros Auklets Cerorhinca monocerata with geolocators and saltwater immersion loggers. Mates migrated across similar areas during the non‐breeding period but with a sustained temporal shift, putting them an average of 377 km apart and resulting in an average difference of return date at the colony of 5.6 days, with no sex biases. These values did not differ significantly from those between ‘pairs’ of randomly selected, non‐mated birds. Mates showed synchronized on‐water/in‐air at‐sea activities once both birds returned and spent the first night together at the colony. The synchronization of activities was highest on the day following the nights when both mates visited the colony, and decreased with elapsed time. Mates then left the colony together for a pre‐laying exodus of 8–9 days and males returned 2–4 days earlier than females before incubation started. Mates kept synchronizing at‐sea activity during the early part of the exodus. We interpret this as the mates staying together at sea during the pre‐laying period, increasing the males’ chances of copulation at sea. The patterns of mate association observed in Rhinoceros Auklets contrast with those of the Procellariiformes, presumably reflecting differences in the place and timing of copulation.     

Visualization of NO3?/NO2? Dynamics in Living Cells by Fluorescence Resonance Energy Transfer (FRET) Imaging Employing a Rhizobial Two-component Regulatory System

Nitrate (NO₃⁻) and nitrite (NO₂⁻) are the physiological sources of nitric oxide (NO), a key biological messenger molecule. NO₃⁻/NO₂⁻ exerts a beneficial impact on NO homeostasis and its related cardiovascular functions. To visualize the physiological dynamics of NO₃⁻/NO₂⁻ for assessing the precise roles of these anions, we developed a genetically encoded intermolecular fluorescence resonance energy transfer (FRET)-based indicator, named sNOOOpy (sensor for NO₃⁻/NO₂⁻ in physiology), by employing NO₃⁻/NO₂⁻-induced dissociation of NasST involved in the denitrification system of rhizobia. The in vitro use of sNOOOpy shows high specificity for NO₃⁻ and NO₂⁻, and its FRET signal is changed in response to NO₃⁻/NO₂⁻ in the micromolar range. Furthermore, both an increase and decrease in cellular NO₃⁻ concentration can be detected. sNOOOpy is very simple and potentially applicable to a wide variety of living cells and is expected to provide insights into NO₃⁻/NO₂⁻ dynamics in various organisms, including plants and animals.     

Codetection of Respiratory Syncytial Virus in Habituated Wild Western Lowland Gorillas and Humans During a Respiratory Disease Outbreak

Pneumoviruses have been identified as causative agents in several respiratory disease outbreaks in habituated wild great apes. Based on phylogenetic evidence, transmission from humans is likely. However, the pathogens have never been detected in the local human population prior to or at the same time as an outbreak. Here, we report the first simultaneous detection of a human respiratory syncytial virus (HRSV) infection in western lowland gorillas (Gorilla gorilla gorilla) and in the local human population at a field program in the Central African Republic. A total of 15 gorilla and 15 human fecal samples and 80 human throat swabs were tested for HRSV, human metapneumovirus, and other respiratory viruses. We were able to obtain identical sequences for HRSV A from four gorillas and four humans. In contrast, we did not detect HRSV or any other classic human respiratory virus in gorilla fecal samples in two other outbreaks in the same field program. Enterovirus sequences were detected but the implication of these viruses in the etiology of these outbreaks remains speculative. Our findings of HRSV in wild but human-habituated gorillas underline, once again, the risk of interspecies transmission from humans to endangered great apes.