Nonrandom processes maintain diversity in tropical forests

An ecological community's species diversity tends to erode through time as a result of stochastic extinction, competitive exclusion, and unstable host-enemy dynamics. This erosion of diversity can be prevented over the short term if recruits are highly diverse as a result of preferential recruitment of rare species or, alternatively, if rare species survive preferentially, which increases diversity as the ages of the individuals increase. Here, we present census data from seven New and Old World tropical forest dynamics plots that all show the latter pattern. Within local areas, the trees that survived were as a group more diverse than those that were recruited or those that died. The larger (and therefore on average older) survivors were more diverse within local areas than the smaller survivors. When species were rare in a local area, they had a higher survival rate than when they were common, resulting in enrichment for rare species and increasing diversity with age and size class in these complex ecosystems.     

Evaluation of the specificity of three enzyme-linked immunosorbent assays for detection of antibodies against Salmonella in bovine bulk milk

Background

The Swedish Salmonella control program has been running for decades and has resulted in a low prevalence of Salmonella in Swedish food producing animals. Routine bacteriology is used to detect Salmonella, however, bacteriology is time consuming, costly and has a low sensitivity. Different enzyme-linked immunosorbent assays (ELISAs) have been developed for detection of antibodies against Salmonella Dublin and S. Typhimurium in bovine bulk milk, individual milk samples as well as in sera. Screening bulk milk for antibodies against Salmonella spp. could improve the cost-effectiveness of the surveillance in Swedish dairy cattle, but as characteristics of tests may vary in different populations, tests should always be evaluated in the specific population where they will be used. Hence, the aim of this study was to evaluate the specificities of three bovine ELISAs when used to analyse bulk milk samples from Swedish dairy cattle. A second aim was to compare the performance of the two Dublin ELISAs tested.

Methods

Bulk milk samples for analysis were randomly selected from samples collected within the Swedish bulk milk sampling scheme and analyzed with the three ELISAs; a Danish in-house Dublin ELISA, PrioCHECK® Salmonella Ab bovine Dublin ELISA and PrioCHECK® Salmonella Ab bovine ELISA (hereafter named mixed ELISA). The specificities of the ELISAs were calculated assuming a disease-free status in Sweden i.e. that all test positive samples were assumed to be false positive results. This assumption can be used when a disease is known to be infrequent.

Results

The calculated specificities of the two Dublin ELISAs and the mixed ELISA, when using the producer’s recommended cut-off value of the corrected optic-density percent (ODC%) were 99.4% (95% Confidence Interval (CI): 98.8% -99.8%), 99.4% (95% CI: 98.8% -99.8%) and 97.9% (95% CI: 96.8% -98.7%), respectively. The correlation between the ODC% values of the two Dublin ELISAs was 0.83.

Conclusions

We conclude that the evaluated ELISAs have sufficiently high specificities to be used as supplement to bacteriological examinations in the Swedish Salmonella control program in cattle as well as a primary screening test in routine surveillance for S. Dublin.     

First evidence of palytoxin and 42-hydroxy-palytoxin in the marine cyanobacterium Trichodesmium

Marine pelagic diazotrophic cyanobacteria of the genus Trichodesmium (Oscillatoriales) are widespread throughout the tropics and subtropics, and are particularly common in the waters of New Caledonia. Blooms of Trichodesmium are suspected to be a potential source of toxins in the ciguatera food chain and were previously reported to contain several types of paralyzing toxins. The toxicity of water-soluble extracts of Trichodesmium spp. were analyzed by mouse bioassay and Neuroblastoma assay and their toxic compounds characterized using liquid chromatography coupled with tandem mass spectrometry techniques. Here, we report the first identification of palytoxin and one of its derivatives, 42-hydroxy-palytoxin, in field samples of Trichodesmium collected in the New Caledonian lagoon. The possible role played by Trichodesmium blooms in the development of clupeotoxism, this human intoxication following the ingestion of plankton-eating fish and classically associated with Ostreopsis blooms, is also discussed.     

Risk factors associated with interdog aggression and shooting phobias among purebred dogs in Denmark

The prevalence of behaviour problems is reported from a questionnaire study among members of the Danish Kennel Club (DKC). In total, 4359 dog owners were included in the analyses. With logistic regression, we analysed four behaviour problems: dominance towards the owner, interdog dominance aggression, separation anxiety and shooting phobia. Compared to Labrador Retrievers, the following breeds and breed groups had higher odds of being reported to have interdog dominance aggression: Belgian Sheepdogs, Dachshunds, Dalmatians, German Shepherds, Hovawarts, Pinschers, Rottweilers, Scent dogs and Spitz dogs. Poodles, retrieving/flushing dogs, Sheepdogs, Spitz dogs and terriers had higher odds of shooting phobia. The odds of interdog dominance aggression were higher among dogs owned by younger dog owners compared to dogs owned by older dog owners. Dogs living in the capital area of Copenhagen had increased odds of interdog dominance aggression as compared to dogs living in other parts of Denmark. Dogs belonging to owners with limited knowledge of the breed before acquiring the dog had higher odds of interdog dominance aggression. Dogs attending obedience training classes had reduced odds of shooting phobia. Dogs belonging to dog breeders had reduced odds of being reported to have the investigated behaviour problems.     

?Agri-Black?? ?C Einsatz einer photoselektiven Mulchfolie im ?kologischen Erdbeeranbau

The use of mulch films is gaining importance in strawberry production. In this paper, the photoselective PE-mulch film ??Agri-Black?? is compared with a common PE-film and with the traditional method ??open soil?+?straw mulch at blossom??. ??Agri-Black?? is produced with a blend of alternative colour pigments instead of carbon black and with a high amount of UV-absorbers which may lead to an altered germination behaviour of weeds and to an earlier harvest due to higher soil temperature. The effects on the growth of weeds through the planting holes of the films, long-term herbicide effects after removing the films, and the effects on yield and fruit quality of the strawberries were analysed. Weed growth through the planting holes was reduced by trend by ??Agri-Black?? in comparison to the common PE-film, but not significantly. Six weeks after removing the films, the total amount of weeds was significantly lower in parcels with ??Agri-Black?? than in parcels with the common PE-film. Regarding single species, no significant differences between the films were determined. Long lasting rainfalls before harvest, in combination with flat beds, did result in heavy plant damages in both film variants and thus in much lower yield than in the control variant ??open soil?+?straw mulch at blossom??. In the control variant, there were significantly more fruits damaged by slugs, compared to both film variants.     

Detection of Antinuclear Antibodies by Indirect Immunofluorescence in Dog Sera: Comparison of Rat Liver Tissue and Human Epithelial-2 Cells as Antigenic Substrate

Rat liver sections and a human epithelial cell line (HEp-2) were compared as substrates for the detection of antinuclear antibodies (ANA) in the serum of normal dogs and dogs with suspected autoimmune disease, using a standard indirect immunofluorescence (IIF) technique. Antibody reactivity against rat hepatocyte nuclei was frequently found at low serum dilutions in normal dog sera. Using rat liver sections, a minimum significant positive titer, allowing negativity in more than 95% of normal dog sera, was found to be 1/100. With this titer, ANA positivity could be verified in 64 of 112 (57%) reanalysed serum samples from dogs with suspected autoimmune disease, earlier determined as ANA-positive. No reactivity against nuclei of HEp-2 cells was observed in any of the normal dog sera analyzed at a screening dilution of 1/25. Using this dilution as a minimum significant positive titer, 63 of the 112 (56%) re-evaluated serum samples were positive. These 63 samples were from the same dogs as the 64 samples that were positive on rat liver sections. Thus, the 2 methods of ANA-IIF detected a nearly identical population of dogs with suspected autoimmune disease once the level of significance of a positive titer was adjusted to 195% specificity for each method. HEp-2 cells were found to be superior to rat liver cryostate sections as ANA substrate because of their low reactivity with normal sera, and the ease of discernment of the ANA fluorescence pattern. The recognition and documentation of specific pattern types may give clues to ANA subspecificities, which could prove useful if they are found to correlate with well-defined subgroups of immune mediated clinical diseases in dogs. J Vet Intern Med 1996;10:199–203. Copyright © 1996 by the American College of Veterinary Internal Medicine .     

Sensory properties of virgin olive oil polyphenols: identification of deacetoxy-ligstroside aglycon as a key contributor to pungency

Polyphenols are an important functional minor component of virgin olive oils that are responsible for the key sensory characteristics of bitterness, pungency, and astringency. Polyphenols were isolated from virgin olive oils by using liquid/liquid extraction and then separated by using reverse phase HPLC followed by fraction collection. The sensory qualities of the isolated polyphenols were evaluated, and almost all fractions containing polyphenols were described as bitter and astringent. However, the fraction containing deacetoxy-ligstroside aglycon produced a strong burning pungent sensation at the back of the throat. In contrast, the fraction containing the analogous deacetoxy-oleuropein aglycon, at an equivalent concentration, produced only a slight burning/numbing sensation, which was perceived more on the tongue. No other polyphenol fractions from the analyzed oils produced the intense burning sensation; thus, deacetoxy-ligstroside aglycon is the polyphenol responsible for the majority of the burning pungent sensation found in pungent extra virgin olive oils.     

Morbidity of purebred dogs in Denmark

Prevalences of diseases in purebred dogs are reported from a questionnaire study among members of the Danish Kennel Club (DKC) in 1997. The 4295 dogs in the study represented 24 breeds and 16 breed groups. Sixty percent of the dogs had at least one disease-event during their lifetime with a median of 2 and a maximum of 11. Diseases of the skin were the most-frequent (13.6%) followed by eye diseases (13.2%), accidents (12.6%) and diseases of the ear (12.6%). The prevalences of five diseases differed significantly between the breeds (diseases of the skin, eyes, ears, respiratory and skeletal systems). Males had significantly higher prevalences of respiratory diseases, skeletal diseases and diseases of the mouth and teeth. Tumours and diseases of the urinary system were most prevalent in females. Gender- and breed-specific prevalences are reported for the most-frequent diseases.     

FDA fast-tracking of pet population control drugs

Theriogenologists have been studying estrus prevention and termination of pregnancy in dogs for at least 2 decades. However, drugs approved for estrus suppression are few. No dog or cat abortifacients or male dog and cat sterilants have been approved. Marketed drugs with alternate indications that have antiestrus and antihormonal activity might be good candidates for study after obtaining an INAD from FDA. With the support of the original drug sponsor or manufacturer and appropriate safety and effectiveness studies, these products may be studied for additional label claims. New (not previously approved) drugs additionally need detailed information regarding the synthesis and manufacturing controls. Drugs offering substantial benefit over existing therapeutics may be eligible for expedited review. Prior to starting any studies in this area, clinical investigators and sponsors should communicate with FDA, an INAD must be granted, and the protocol submitted for evaluation. Approvability is evaluated after establishment of safety and effectiveness in clinical field trials.