First Report of Xanthomonas arboricola pv. pruni in Ornamental Prunus laurocerasus in the Netherlands.

In 2008, Dutch ornamental plant growers observed a leaf spot of cherry laurel (Prunus laurocerasus) at a greater incidence (5 to 50%) than the usual sporadic level (<1%). For advice on disease control, ~5 to 10% of these growers contacted Dutch regulatory officials. In November and December 2008, six symptomatic samples from northern and southern parts of the Netherlands were submitted for diagnosis. Leaf spots were chlorotic, most had a necrotic brown center with a distinct margin, and the spots readily abscised, resulting in a "shot-hole" appearance. Leaf spots from the samples were surface sterilized (2 s in 70% vol/vol alcohol), blotted dry on tissue paper, chopped into pieces (1 to 2 mm in diameter), and incubated for 30 min in 10 mM phosphate-buffered saline (PBS) (1). A 20-µl aliquot of extract per sample was streaked by dilution plating on four plates of yeast peptone glucose agar medium (1), and the plates were incubated for 2 to 3 days at 28°C. Isolations from all six samples yielded Xanthomonas-like colonies. After purification, characterization of all six isolates revealed oxidative, nonfermentative metabolism of glucose by rod-shaped, gram-negative bacterial cells. All six isolates were identified as Xanthomonas arboricola pv. pruni based on biochemical tests (1), fatty acid analysis (4), and immunofluorescence (IF) using polyclonal antibodies (Plant Research International, the Netherlands). Pathogenicity was tested on potted peach plants (cvs. Peregrine and Vaes Oogst) and on detached leaves of P. laurocerasus (cv. Novita) (1). The six field isolates from 2008 were each inoculated (108 CFU/ml) onto four leaves per plant of each of two peach plants (replicates). As positive control treatments, two reference strains (ATCC 19312 and PD740) were each inoculated onto the same number of leaves and plants, and as a noninoculated negative control treatment, leaves of two peach plants were treated with sterile 10 mM PBS buffer (1). All leaves inoculated with the six field isolates and the two reference strains developed typical bacterial spot symptoms in 3 to 4 weeks. Negative control plants showed no symptoms. The detached leaf assay performed with the same treatments on each of two leaves (replicates) showed identical results. The bacterium was reisolated from leaf spots associated with each of the eight symptomatic treatments and identity of the reisolates was confirmed by IF. Additionally, genotypic variation of 35 Dutch isolates of X. arboricola pv. pruni was assessed by BOX-PCR assay with the BOX A1R primer set (3), and Gyrase B gene sequencing (2). Both methods revealed 100% homology among the 35 isolates, suggesting a single, recent introduction of X. arboricola pv. pruni into the Netherlands. In a 2009 survey to assess distribution of the disease in the Netherlands, X. arboricola pv. pruni was found in 41 fields. Infected hosts included P. laurocerasus cvs. Otto Luyken, Rotundifolia, Novita, Etna, Anbri, Herbergii, Mischeana, and Caucasia. X. arboricola pv. pruni is a quarantine organism in countries affiliated under the EPPO (European and Mediterranean Plant Protection Organization). Phytosanitary measures were taken to prevent movement of infested plants from nurseries where X. arboricola pv. pruni was detected. References: (1) Anonymous. EPPO Bull. 36:129, 2006. (2) N. Parkinson et al. Int. J. Syst. Evol. Microbiol. 59:264, 2009. (3) J. Versalovic et al. Methods Mol. Cell. Biol. 5:25, 1994. (4) S. A. Weller et al. EPPO Bull. 30:375, 2000.

Neuronal processing of translational optic flow in the visual system of the shore crab Carcinus maenas.

This paper describes a search for neurones sensitive to optic flow in the visual system of the shore crab Carcinus maenas using a procedure developed from that of Krapp and Hengstenberg. This involved determining local motion sensitivity and its directional selectivity at many points within the neurone's receptive field and plotting the results on a map. Our results showed that local preferred directions of motion are independent of velocity, stimulus shape and type of motion (circular or linear). Global response maps thus clearly represent real properties of the neurones' receptive fields. Using this method, we have discovered two families of interneurones sensitive to translational optic flow. The first family has its terminal arborisations in the lobula of the optic lobe, the second family in the medulla. The response maps of the lobula neurones (which appear to be monostratified lobular giant neurones) show a clear focus of expansion centred on or just above the horizon, but at significantly different azimuth angles. Response maps such as these, consisting of patterns of movement vectors radiating from a pole, would be expected of neurones responding to self-motion in a particular direction. They would be stimulated when the crab moves towards the pole of the neurone's receptive field. The response maps of the medulla neurones show a focus of contraction, approximately centred on the horizon, but at significantly different azimuth angles. Such neurones would be stimulated when the crab walked away from the pole of the neurone's receptive field. We hypothesise that both the lobula and the medulla interneurones are representatives of arrays of cells, each of which would be optimally activated by self-motion in a different direction. The lobula neurones would be stimulated by the approaching scene and the medulla neurones by the receding scene. Neurones tuned to translational optic flow provide information on the three-dimensional layout of the environment and are thought to play a role in the judgment of heading.

Effects of light intensity and pattern contrast on the ability of the land crab, Cardisoma guanhumi, to separate optic flow-field components.

Using a novel suite of computer-generated visual stimuli that mimicked components of optic flow, the visual responses of the tropical land crab, Cardisoma guanhumi, were investigated. We show that crabs are normally successful in distinguishing the rotational and translational components of the optic flow field, showing strong optokinetic responses to the former but not the latter. This ability was not dependent on the orientation of the crab, occurring both in "forwards-walking" and "sideways-walking" configurations. However, under conditions of low overall light intensity and/or low object/background contrast, the separation mechanism shows partial failure causing the crab to generate compensatory eye movements to translation, particularly in response to low-frequency (low-velocity) stimuli. Using this discovery, we then tested the ability of crabs to separate rotational and translational components in a combined rotation/translation flow field under different conditions. We demonstrate that, while crabs can successfully separate such a combined flow field under normal circumstances, showing compensatory eye movements only to the rotational component, they are unable to make this separation under conditions of low overall light intensity and low object/background contrast. Here, the responses to both flow-field components show summation when they are in phase, but, surprisingly, there is little reduction in the amplitude of responses to rotation when the translational component is in antiphase. Our results demonstrate that the crab's visual system finds separation of flow-field components a harder task than detection of movement, since the former shows partial failure at light intensities and/or object/background contrasts at which movement of the world around the crab is still generating high-gain optokinetic responses.

Local mechanisms for the separation of optic flow-field components in the land crab, Cardisoma guanhumi: a role for motion parallax?

Although a number of global mechanisms have been proposed over the years that explain how crabs might separate the rotational and translational components of their optic flow field, there has been no evidence to date that local mechanisms such as motion parallax are used in this separation. We describe here a study that takes advantage of a recently developed suite of computer-generated visual stimuli that creates a three-dimensional world surrounding the crab in which we can simulate translational and rotational optic flow. We show that, while motion parallax is not the only mechanism used in flow-field separation, it does play a role in the recognition of translational optic flow fields in that, under conditions of low overall light intensity and low contrast ratio when crabs find the distinction between rotation and translation harder, smaller eye movements occur in response to translation when motion parallax cues are present than when they are absent. Thus, motion parallax is one of many cues that crabs use to separate rotational and translational optic flow by showing compensatory eye movements to only the former.

PC-based visual stimuli for behavioural and electrophysiological studies of optic flow field detection.

A PC-based visual-stimulus-generation package for behavioural and electrophysiological studies of responses to optic flow is described. Developed for studies of crab vision, the package is particularly well suited for use with animals that have very large fields of view, i.e. +/-120 degrees. Programs, written in the Borland Delphi language, use the OpenGL graphics library to create realistic representations of motion in a three dimensional environment. Large-field stimuli include simulations of self-motion (rotation and translation, separately or in combination) relative to a square-wave grating or other, user-selected, background. The package also includes representations of approaching and receding objects, and rotating spiral patterns for the investigation of neural responses to looming/anti-looming. Additionally, the package provides local motion stimuli, translating or rotating targets presented at many points in the receptive field, which can be used to derive response maps of large-field motion-sensitive interneurones. In all these stimuli, inconsistencies in animation timing that have hitherto hindered the use of standard PCs running Microsoft Windows for such applications have been minimised by using an improved real-time clock to control the animation cycle.

Evidence of strong earthquake shaking in the lower wabash valley from prehistoric liquefaction features.

Earthquake-induced liquefaction features in Holocene sediments provide evidence of strong prehistoric shaking, magnitude m(b) 6.2 to 6.7, in the Wabash Valley bordering Indiana and Illinois. The source of the one or more earthquakes responsible was almost certainly in or near the Wabash Valley. The largest event is interpreted to have occurred between 7500 and 1500 years ago on the basis of archeological, pedological, and stratigraphic relations.

Pediatric penetrating head and neck trauma.

Penetrating head and neck trauma in children causes uncommon and potentially life-threatening injuries. We reviewed the charts of 21 patients who sustained penetrating injuries to the face or upper neck. Seventeen males and 4 females, aged 32 weeks' gestation to 19 years (mean = 10.2 years) comprised the study population. There were 15 gun-shot wounds, 1 shotgun injury, and 5 stab wounds. Significant problems included 7 vascular injuries, 6 central nervous system injuries, 5 ocular injuries, 3 airway compromises, 2 facial nerve injuries, 1 cervical esophageal penetration, and 2 cases of pneumothorax. Three deaths occurred, but the majority of the patients survived and sustained minimal permanent disability. Included in this review is a unique case of an intrauterine gunshot wound to the face at approximately 32 weeks' gestation. The treatment protocol, differences from adult patients, and management highlights are reviewed.

Temporal bone pneumatization in cystic fibrosis patients.

Cystic fibrosis patients commonly have nasal polyps and sinusitis, but surprisingly are spared from an increased occurrence of otitis media. Twenty cystic fibrosis patients whose ages ranged from 13 to 26 years were studied. Only one of these patients had a history of otitis. Minimal temporal bone pneumatization, as determined by computed tomography, was used as an indicator of childhood otitis. The computed tomography had been done as part of the medical evaluation of their symptomatic paranasal sinusitis. On the average, pneumatization volume was larger for the cystic fibrosis patients than for the normal population (p = 0.033, Student's t-test). That is, these data indicate that cystic fibrosis patients had significantly less otitis than the normal population. Assuming that these cystic fibrosis patients are representative, the data may imply that the gene for good musculoskeletal eustachian differentiation is linked with the gene for cystic fibrosis. The data also imply that poor mucociliary transport does not necessarily induce otitis media.

Relationship of eustachian tube bony landmarks and temporal bone pneumatization.

Anatomic and functional differences of the eustachian tube have been suggested as etiologic factors in patients with otitis media. We studied eustachian tube lengths and vectors of the tensor veli palatini muscle in 25 unilateral specimens from adult human cadavers. The extent of temporal bone pneumatization, as determined by computed tomography and plain lateral radiographs, was used as an indicator of prior otitis media. Increased length of the cartilaginous eustachian tube was associated positively (r = .53, p less than .01) with volume of pneumatization. However, neither the length of the bony eustachian tube nor the vector of maximum pull of the tensor veli palatini muscle was associated statistically with the extent of pneumatization. It may be that the longer cartilaginous eustachian tube is more protective of the middle ear.

Fecal blood loss during isoxicam and piroxicam administration for 28 days.

After an 11-day baseline period, groups of eight healthy men received isoxicam, 200 mg once a day, or piroxicam, 20 mg once a day, for 28 days. Fecal blood loss (FBL) was quantitated by the 51Cr-labeled erythrocyte method. FBLs for both isoxicam and piroxicam were only slightly higher than baseline for the first 3 drug dosing days, confirming the results of a previously published 4-day study of piroxicam, but FBL subsequently steadily increased, with maxima occurring for most subjects receiving isoxicam in 2 or 3 weeks and for most subjects receiving piroxicam in 3 or 4 weeks. This implies that dosing for 7 days or less, as is frequent in FBL studies of nonsteroidal anti-inflammatory drugs, may be insufficient to detect the peak drug-induced FBL. In week 4, FBL for both drugs was elevated approximately 0.6 ml/day over baseline. FBLs in week 4 were comparable to those reported for naproxen and less than those reported for indomethacin and acetylsalicylic acid. Statistical analyses of weekly plasma drug minimum concentrations suggest steady state was reached at week 2 for isoxicam and week 3 for piroxicam. There were large between-subject variations in steady-state plasma drug concentrations for both drugs. One subject in each drug group indulged in excessive alcohol consumption during the medication period, with a concomitant significant increase in FBL, which suggests exacerbation of the drug effect.