Trees outside forests in agricultural landscapes: spatial distribution and impact on habitat connectivity for forest organisms

Context

Various species of forest trees are commonly used for ornamental purposes and are therefore frequently found in nonforest ecosystems. They constitute an important component of the so-called trees outside forests (TOF). Not much is known, however, about the drivers of TOF spatial distribution either in urbanized or in agricultural landscapes since they are generally absent from forest inventories.

Objective

The present study focused on the spatial distribution of TOF across agricultural landscapes and their potential role in the dispersal of a forest pest insect, the pine processionary moth, Thaumetopoea pityocampa (PPM).

Methods

All the TOF belonging to the genera Pinus, Cedrus and Pseudotsuga were considered as potential hosts and inventoried within a 22 × 22 km study window. We fitted a nonstationary Poisson process to the empirical data and used the distance to the nearest building as a covariate.

Results

Both empirical and simulated data indicated that TOF associated to human artifacts/urbanized areas constituted the main source of landscape connectivity for the PPM in the open fields under study. Because they do not account for TOF, forest inventories dramatically underestimate landscape connectivity and provide an erroneous picture of the PPM habitat distribution.

Conclusions

We conclude that TOF, especially the ornamental component, must be taken into account when it comes to understanding forest insect landscape dynamics or genetics. The omnipresence of TOF also suggests a potentially huge role in pest dispersal and invasive species expansion.

     

Production and characterization of two Streptococcus suis capsular type 2 mutants.

Two avirulent mutants of Streptococcus suis capsular type 2 (M2 and M42) were produced from a highly virulent strain. Mutant M2, obtained after serial subcultures of the parent strain in the presence of rabbit anti-capsular type 2 serum, no longer possessed the type-specific capsular antigen, as demonstrated by serotyping methods and immunoelectron microscopy. The Lancefield group D antigen could not be detected on the cell surface of this mutant using the immunogold labelling technique. SDS-PAGE of lysozyme treated cells demonstrated that a 44 kDa protein which was present in the parent strain, was absent in mutant M2. Immunoblotting using rabbit whole cell homologous anti-serum revealed that the protein was strongly immunogenic. Mutant M2 was totally avirulent in mice, and the homologous antiserum completely failed to protect mice against challenge with the parent strain. However, mutant M42, obtained after passages of the parent strain at 42 degrees C, remained capsulated but lacked the same 44 kDa protein as mutant M2. The quantity of sialic acid present in the capsule was similar to that of the parent strain. Despite the presence of antibodies against the capsule, antiserum prepared against M42 only partially protected mice against a challenge with the parent strain. The 44 kDa cell wall protein could act as a virulence factor as well as an important immunogen of S. suis capsular type 2.     

O157:H7 and O104:H4 Vero/Shiga toxin-producing Escherichia coli outbreaks: respective role of cattle and humans

ABSTRACT: An enteroaggregative Verotoxin (Vtx)-producing Escherichia coli strain of serotype O104:H4 has recently been associated with an outbreak of haemolytic-uremic syndrome and bloody diarrhoea in humans mainly in Germany, but also in 14 other European countries, USA and Canada. This O104:H4 E. coli strain has often been described as an enterohaemorrhagic E. coli (EHEC), i.e. a Vtx-producing E. coli with attaching and effacing properties. Although both EHEC and the German O104:H4 E. coli strains indeed produce Vtx, they nevertheless differ in several other virulence traits, as well as in epidemiological characteristics. For instance, the primary sources and vehicles of typical EHEC infections in humans are ruminants, whereas no animal reservoir has been identified for enteroaggregative E. coli (EAggEC). The present article is introduced by a brief overview of the main characteristics of Vtx-producing E. coli and EAggEC. Thereafter, the O104:H4 E. coli outbreak is compared to typical EHEC outbreaks and the virulence factors and host specificity of EHEC and EAggEC are discussed. Finally, a renewed nomenclature of Vtx-producing E. coli is proposed to avoid more confusion in communication during future outbreaks and to replace the acronym EHEC that only refers to a clinical condition.     

Occurrence of odorant polyfunctional thiols in the Super Alpha Tomahawk hop cultivar. Comparison with the thiol-rich Nelson Sauvin bitter variety

Tomahawk hop (Humulus lupulus) is a recently developed Super Alpha cultivar (14-18% α-acids w/w), already widely used by brewers to impart bitterness and a citrus-like aroma to beer. By comparison with two bitter varieties (Nelson Sauvin and Nugget) and two aromatic ones (Cascade and Saaz), the Tomahawk cultivar showed a very particular terpenoid profile, rich in both α- and β-selinenes (>600 mg/kg IST equiv in total), methyl geranate (>40 mg/kg IST equiv), and geraniol (>200 mg/kg). Tomahawk also proved to contain a wide variety of odorant polyfunctional thiols. The major β-sulfanyl acetate, 3-sulfanyl-2-ethylpropyl acetate, newly identified here, was found at similar levels in the famous Sauvignon-like Nelson Sauvin and Tomahawk varieties (15-44 μg/kg IST equiv). On the other hand, lower levels of total β-sulfanyl alcohols were measured in Tomahawk, although 3-sulfanylhexan-1-ol was found at a similar level and the 3-sulfanyl-4-methylpentan-1-ol previously claimed to be specific to the Nelson Sauvin variety was also evidenced in the Super Alpha cultivar (9-13 μg/kg IST equiv). As revealed by boiling and fermentation, Tomahawk hop also contains very interesting bound polyfunctional thiols that should be investigated for better use by brewers.     

Surgical treatment of disk-associated wobbler syndrome by a distractable vertebral titanium cage in seven dogs

Objective: To evaluate a distractable titanium cage for the treatment of disk‐associated wobbler syndrome (DAWS). Study Design: Prospective study. Animals: Dogs (n=7) with DAWS. Methods: After total discectomy of C5–C6 and C6–C7, the median part of the vertebral body of C6 was removed with preservation of the lateral walls and dorsal cortex. The removed cancellous bone was collected. The implant was placed in the bony defect of C6. After placement, the titanium cage was distracted and affixed by 4 screws. Finally, the implant was filled and covered with cancellous bone. Dogs had follow‐up examinations at 1, 3, 6, 12, and 24 months. Six months after surgery, cervical radiographs and computed tomography (CT) were performed. Results: Although no intraoperative complications occurred, correct placement of the cage was technically challenging. Revision surgery was necessary in 2 dogs because of implant loosening and aggravation of vertebral tilting. All dogs improved after discharge from the hospital. In 1 dog, recurrence of clinical signs caused by articular facet proliferation at an adjacent intervertebral disk space occurred. Radiographs at 6 months demonstrated cage subsidence in 4 dogs. In all dogs, CT was suggestive for fusion of the bone graft with the vertebral body. Conclusions: Although results are promising, technical adaptations will be necessary to make this specific surgical technique, designed for humans, suitable for routine use in dogs.     

Variations in physical and mechanical properties between tension and opposite wood from three tropical rainforest species

Growth strains were measured in situ in nine trees of three species from a French Guiana tropical rainforest in a clearly active verticality restoration process. The aim was to detect tension wood within the samples. Wood specimens were cut in the vicinity of the growth strain measurements in order to determine the microfibril angle and some mechanical and physical properties. As suspected, tensile growth strain was much higher in tension wood zones, as shown by the slightly higher longitudinal modulus of elasticity. Conversely, tension wood showed reduced compression strength. Longitudinal shrinkage was much higher in tension wood than in opposite wood. Clear relationships between the microfibril angle and longitudinal properties were noted in comparison (i) with those observed in gymnosperm compression wood and (ii) with expected relationships from the organization of wood fibres cell wall structure.     

Supplementation of dormant tallgrass-prairie forage: I. Influence of varying supplemental protein and(or) energy levels on forage utilization characteristics of beef steers in confinement

Three experiments were conducted to evaluate effects of supplemental protein vs energy level on dormant forage intake and utilization. In Exp. 1, 16 ruminally cannulated steers were blocked by weight (avg wt = 242 kg) and assigned randomly to a negative control or to one of three isocaloric supplement treatments fed at .4% BW: 1) control, no supplement (NS); 2) 12% CP, low protein (LP); 3) 28% CP, moderate protein (MP); 4) 41% CP, high protein (HP). In Exp. 2 and 3, 16 ruminally cannulated steers were blocked by weight (avg wt = 332 kg, Exp. 2; 401 kg, Exp. 3) and assigned randomly to a 2 x 2 factorial arrangement of treatments. The treatments contrasted low (LP) and high (HP) levels of supplemental protein (.66 g CP/kg BW vs 1.32 g CP/kg BW) with low (LE) and high (HE) levels of supplemental ME (9.2 kcal/kg BW vs 18.4 kcal/kg BW). In Exp. 1, forage DMI as well as ruminal DM and indigestible ADF fill at 4 h postfeeding were greater (P less than .10) with the MP and HP steers than with control and LP steers. Total DM digestibility increased (P less than .10) for supplemented steers (35.5% for control vs 47.3 for supplemented steers); however, LP depressed (P less than .10) NDF digestibility. In Exp. 2, forage DMI, indigestible ADF flow and liquid flow were depressed (P less than .10) in LP-HE supplemented steers. In Exp. 3, HP steers had greater (P less than .10) forage DMI, indigestible ADF fill values (4 h postfeeding), liquid volume and tended (P = .11) to have greater ruminal DM fill (4 h postfeeding). In summary, increased levels of supplemental protein increased intake and utilization of dormant tallgrass-prairie forage (less than 3% CP). Increasing supplemental energy without adequate protein availability was associated with depressed intake and digestibility.     

Serotypes and intimin types of intestinal and faecal strains of eae+ Escherichia coli from weaned pigs

Enteropathogenic Escherichia coli (EPEC) that are known to cause severe diarrhoea in children and young rabbits are well characterized, but there are few reports on the serotypes and intimin (eae) types of EPEC in weaned pigs. Based on detection of the eae gene by PCR and by DNA-hybridisation with LEE specific gene probes, 20 intestinal and 17 faecal eae(+) strains from diarrhoeal (164) and non-diarrhoeal (57) weaned pigs from 13 Hungarian farms, representing 12.8% of diarrhoeal and 14.0% of non-diarrhoeal pigs, were identified. The dominant serotype was O123:H11 (40%) among intestinal, and O108:H9 (23%) among faecal strains. The majority (85%) of the intestinal strains possessed eae-beta and 10% carried eae-gamma gene. In contrast, significantly (p<0.025) fewer faecal strains (53%) harboured the eae-beta gene, and 23% were eae-gamma positive. In vitro adhesion tests of intestinal and faecal eae(+) strains indicated adhesion of 20/37 of the strains to PK15 (porcine kidney) cells while only 3/37 strains adhered to HeLa cells. The ultrastructure of intimate bacterial attachment of representative porcine eae(+) strains to PK15 cells showed no pedestal formation, in contrast to the human EPEC (O127:H5, eae-alpha) strain. In conclusion, the data do not demonstrate a significant role for the eae(+)E. coli in porcine post-weaning diarrhoea, but provide new information on a dominant porcine serotype (O123:H11, eae-beta), and on differences of serotypes and intimin types of porcine eae(+) strains according to their site of isolation. Furthermore there was an indication that the PK15 cell line could be used as a model to study in vitro adherence of eae(+)E. coli of some human and porcine origin.     

Isolation of Microsporum canis from the hair coat of pet dogs and cats belonging to owners diagnosed with M. canis tinea corporis

Microsporum canis has been frequently isolated from human cases of tinea capitis and tinea corporis. The infection may be acquired from infected animals with cutaneous lesions but also from asymptomatic carriers or from the environment. As asymptomatic M. canis carriers are considered to be a critical factor in the epidemiology of dermatophytosis in humans, this study investigated the relationship between the presence of dermatophytes on the hair coats of dogs and cats without cutaneous lesions and the occurrence of the disease in their respective owners. A total of 136 dogs and 248 cats were sampled from January 1999 to January 2005. Seventy-eight animals (22 dogs and 56 cats) belonged to individuals affected by tinea corporis caused by M. canis and 306 (114 dogs and 192 cats) to individuals without dermatophytosis. Age, sex, breed, habitat and season were recorded for each animal and examined as potential risk factors. Dermatophytes were isolated from 20.5% of the dogs and 28.2% of the cats. Microsporum canis was isolated from 36.4% of dogs cohabiting with owners diagnosed with tinea corporis but it was never isolated from dogs whose owners had no lesions. By contrast, M. canis was isolated from 53.6% of cats cohabiting with owners diagnosed with tinea corporis and from 14.6% of cats whose owners had no signs of the disease. These results clearly indicate that both cats and dogs should be considered as a major source of pathogenic dermatophytes for humans even when they do not present clinical signs of dermatophytosis.