Decreasing eel stocks: survival of the fattest?     

C. G. J. Belpaire  G. Goemans  C. Geeraerts  P. Quataert  K. Parmentier  P. Hagel  J. De Boer 《Ecology of Freshwater Fish》2009,18(2):197-214

Abstract –  Since the 1980s, the European eel Anguilla anguilla stock is in steep decline. Lipid reserves are essential to cover energetic requirements for silver eel migration and reproduction. Two large and independent data sets from Belgium and The Netherlands show an average one-third decrease in fat contents of yellow eels over the past 15 years. Also Le Cren's relative condition factor decreased. On the basis of the somatic energy reserves, reproductive potential of eels from various latitudes over Europe was estimated, assuming fat levels in yellow eel are indicative of those in silver eels. Only large individuals, females as well as males, with high lipid content seem to be able to contribute to the spawning stock. The decrease in fat content in yellow eels may be a key element in the stock decline and raises serious concerns about the chances of the stock to recover.  相似文献   

Plasma aldosterone concentrations and plasma renin activity in healthy dogs and dogs with hyperadrenocorticism     

Javadi S  Kooistra HS  Mol JA  Boer P  Boer WH  Rijnberk A 《The Veterinary record》2003,153(17):521-525

The mean (se) basal plasma aldosterone concentrations were significantly lower in 31 dogs with pituitary-dependent hyperadrenocorticism (PDH) (75 [9] pmol/litre) than in 12 healthy dogs (118 [14] pmol/litre), whereas in five dogs with hyperadrenocorticism due to an adrenocortical tumour they were significantly higher (205 [109] pmol/litre). The mean basal renin activity was not significantly different between the dogs with PDH (303 [48] fmol/litre/second), the dogs with an adrenocortical tumour (141 [63] fmol/litre/second), and the control dogs (201 [25] fmol/litre/second). At three and four hours after the intravenous administration of 0.1 mg/kg dexamethasone, the concentrations of aldosterone decreased significantly to about 60 per cent of their initial values in the control dogs but did not change in the dogs with PDH or an adrenocortical tumour. In the dogs with PDH the renin activity increased significantly after the administration of dexamethasone.  相似文献   

An oligonucleotide array for the identification and differentiation of bacteria pathogenic on potato     

Fessehaie A  De Boer SH  Lévesque CA 《Phytopathology》2003,93(3):262-269

ABSTRACT Oligonucleotides, 16 to 24 bases long, were selected from the 3' end of the 16S gene and the 16S-23S intergenic spacer regions of bacteria pathogenic on potato, including Clavibacter michiganensis subsp. sepedonicus, Ralstonia solanacearum, and the pectolytic erwinias, including Erwinia carotovora subsp. atroseptica and carotovora and E. chrysanthemi. Oligonucleotides were designed and formatted into an array by pin spotting on nylon membranes. Genomic DNA from bacterial cultures was amplified by polymerase chain reaction using conserved ribosomal primers and labeled simultaneously with digoxigenin-dUTP. Hybridization of amplicons to the array and subsequent serological detection of digoxigenin label revealed different hybridization patterns that were distinct for each species and subspecies tested. Hybridization of amplicons generally was restricted to appropriate homologous oligonucleotides and cross-hybridization with heterologous oligonucleotides was rare. Hybridization patterns were recorded as separate gray values for each hybridized spot and revealed a consistent pattern for multiple strains of each species or subspecies isolated from diverse geographical regions. In preliminary tests, bacteria could be correctly identified and detected by hybridizing to the array amplicons from mixed cultures and inoculated potato tissue.  相似文献   

Clavibacter michiganensis subsp. Sepedonicus Elicits a Hypersensitive Response in Tobacco and Secretes Hypersensitive Response-Inducing Protein(s)     

Nissinen R  Lai FM  Laine MJ  Bauer PJ  Reilley AA  Li X  De Boer SH  Ishimaru CA  Metzler MC 《Phytopathology》1997,87(7):678-684

ABSTRACT Strains of Clavibacter michiganensis subsp. sepedonicus, causal agent of bacterial ring rot of potato, showed marked differences in virulence on host plants. When infiltrated into tobacco leaves, virulent strains caused a rapid localized necrotic response (within 24 to 48 h) characteristic of the hypersensitive response (HR), whereas nonpathogenic strains did not. Concentrated cell-free culture supernatants (CCS) from virulent strains caused a necrotic reaction on tobacco, whereas CCS from nonpathogenic strains did not. The necrosis-inducing activity was heat stable and protease sensitive. Inhibitors of eukaryotic metabolism suppressed the necrotic reaction of tobacco to CCS. No necrotic response was observed when host plants were infiltrated with either cells or CCS from virulent strains. HR-inducing protein(s) from a virulent strain separated from the majority of other proteins on DEAE cellulose at 250 to 300 mM NaCl. Ammonium sulfate-precipitated proteins from a virulent strain produced a necrotic reaction at a total protein concentration of 18 mug/ml, whereas those from a nonpathogenic strain did not, even at a concentration of 180 mug/ml. We conclude that virulent strains of C. michiganensis subsp. sepedonicus elicit a typical HR in tobacco and secrete proteinaceous elicitor(s) of the nonhost HR.  相似文献   

Potato root diffusate-induced secretion of soluble, basic proteins originating from the subventral esophageal glands of potato cyst nematodes     

Smant G  Goverse A  Stokkermans JP  De Boer JM  Pomp HR  Zilverentant JF  Overmars HA  Helder J  Schots A  Bakker J 《Phytopathology》1997,87(8):839-845

ABSTRACT In preparasitic second-stage juveniles (J(2)) of potato cyst nematode Globodera rostochiensis, six proteins with molecular masses of 30, 31a/b, 32, 39, and 49 kDa were recognized on Western blots by a monoclonal antibody (MGR48) specific for the subventral esophageal glands. All of these subventral gland proteins (svp's) focused in the basic range (pI 6.8 to 8.6) of an immobilized pH gradient. Western blotting showed that the svp's were present in preparasitic and parasitic J(2) and not in later juvenile stages and adult females. Minor svp quantities also were observed in adult males. Immunogold labeling of preparasitic J(2) showed that the svp's were localized in the rough endoplasmic reticulum and secretory granules of the subventral esophageal glands. Potato root diffusate triggered the secretion of svp's through the stylet, and 5-methoxy-N,N-dimethyltryptamine-hydrogen-oxalate had only a quantitative, additional effect. The forward flow of svp's through the metacorporal pump chamber was confirmed by the presence of svp's in the circular lumen of the esophagus (procorpus), as established by immunoelectron microscopy. Our data provide conclusive evidence that secretory proteins of the subventral glands of G. rostochiensis can be secreted through the stylet and support the hypothesis that the subventral esophageal glands play an important role in the early events of this nematode-plant interaction.  相似文献   

Some biochemical parameters for qualification of bull semen     

van der Horst CJ  Elgersma A  de Boer MJ  Bestebroer AC 《The Veterinary quarterly》1979,1(2):97-108

Summary Since the macroscopical and microscopical examination of bull semen does not in all cases appear to give conclusive indications concerning the fertilizing capacity, an investigation of some biochemical parameters was undertaken. It was shown that the following biochemical examination could furnish some more information about the quality of the semen: 1. Determination of the phenylalanine- α-ketoglutarate transaminase activity both in the seminal plasma and in the whole semen. A high transaminase activity in the plasma points to leakage out of the spermatozoa, thus indicating an affection of the spermatozoa. In that case larger amounts of basic amino acids and of leucine were often found in the seminal plasma than would normally be observed. 2. Gas chromatographic examination of the steroids occurring both in the seminal plasma and in the spermatozoa. In a number of infertile bulls small peaks of progesterone were found together with those of other, unidentified compounds. 3. Investigation of the carbohydrate metabolism in the semen. In a number of fertile bulls the following deviations were found: a. the presence of quite a lot of fructose in the spermatozoa; b. the presence of glucuronic acid and / of other foreign compounds in the spermatozoa or in the plasma; c. an elevated pH in the seminal plasma some 2 to 3 hours after ejaculation; d. a low phenylalanine-α -ketoglutarate transaminase activity in the whole semen (the spermatozoa had been disrupted by freezing). 4. Investigation of the presence of reducing aldehydes (glycolaldehyde and glyceraldehyde) inside the spermatozoa. The determinations mentioned under 1, 3c and 3d can easily be carried out in the laboratories of each District Animal Health Service and of the A.I. stations; the same is true of the occurrence of amino acids in the seminal plasma and of fructose and aldehydes inside the spermatozoa if facilities are available for electrophoresis and chromatography.  相似文献   

Studies in epidemiology of maedi/visna in sheep.     

G F De Boer  C Terpstra  D J Houwers  J Hendriks 《Research in veterinary science》1979,26(2):202-208

Lambs born to ewes from flocks with a high incidence of maedi/visna were separated from their dams at birth (group 1), or after 10 h (group 2), six weeks (group 3) or one year (group 4) and were observed for periods of up to eight years. Group 1 lambs remained free of infection while 28 per cent, 76 per cent and 81 per cent respectively of lambs in the other groups developed clinical, serological or histopathological evidence of infection during the observation period. It is therefore concluded that vertical transmission, if it occurs at all, is of little significance in the epidemiology of the disease. The number of serologically, virologically and histopathologically maedi/visna positive sheep, the time of onset of disease and the severity of lesions were related to the duration of exposure to the parent flock. In a separate trial no evidence was obtained for the transmission of maedi/visna by Muellerius capillaris larvae.  相似文献   

Review and retrospective analysis of degenerative lumbosacral stenosis in 156 dogs treated by dorsal laminectomy.     

N Suwankong  B P Meij  G Voorhout  A H de Boer  H A W Hazewinkel 《Veterinary and comparative orthopaedics and traumatology》2008,21(3):285-293

The medical records of 156 dogs with degenerative lumbosacral stenosis (DLS) that underwent decompressive surgery were reviewed for signalment, history, clinical signs, imaging and surgical findings. The German Shepherd Dog (GSD) was most commonly affected (40/156, 25.6%). Pelvic limb lameness, caudal lumbar pain and pain evoked by lumbosacral pressure were the most frequent clinical findings. Radiography showed lumbosacral step formation in 78.8% (93/118) of the dogs which was associated with elongation of the sacral lamina in 18.6% (22/118). Compression of the cauda equina was diagnosed by imaging (epidurography, CT, or MRI) in 94.2% (147/156) of the dogs. Loss of the bright nucleus pulposus signal of the L7-S1 disc was found on T2-weighted MR images in 73.5% (25/34) of the dogs. The facet joint angle at L7-S1 was significantly smaller, and the tropism greater in GSD than in the other dog breeds. The smaller facet joint angle and higher incidence of tropism seen in the GSD may predispose this breed to DLS. Epidurography, CT, and MRI allow adequate visualization of cauda equina compression. During surgery, disc protrusion was found in 70.5% (110/156) of the dogs. Overall improvement after surgery was recorded in the medical records in 79.0% (83/105) of the dogs. Of the 38 owners that responded to questionnaires up to five years after surgery, 29 (76%) perceived an improvement.  相似文献   

Pathogenic bacteria and parasites in wildlife and surface water     

Heuvelink AE  Zwartkruis JT  van Heerwaarden C  Arends B  Stortelder V  de Boer E 《Tijdschrift voor diergeneeskunde》2008,133(8):330-335

In the period October 2003 to August 2005, 897 faecal samples were collected from wild animals and examined for Salmonella spp., Campylobacter spp., and Shiga toxin producing Escherichia coli (STEC) O157, the prevalence of which was found to be 0.1%, 13.8%, and 0.5 %, respectively. Campylobacter spp. were isolated mainly from faecal samples collected from corvidae (59.8%), and meadow birds and waterfowl (22.4%). A subset of these samples was also examined for Cryptosporidium and Giardia oocysts and cysts. None of the 247 samples examined contained C. parvum oocysts, and only 1 sample (roe faeces) contained G. lamblia assemblage A cysts. In the period September to November 2006, samples of running or still surface water were collected at 10 sites on 5 days, to investigate the presence of Salmonella spp., Campylobacter spp., and STEC O157. Twenty (40.8%) of the surface water samples were positive for one or more bacterial pathogens. Seven (14.3%) samples were positiveforSalmonella spp., 14 (28.6%) samples were positive for Campylobacter spp., and 1 (2.0%) sample was positivefor E. coli O157. Samples collected at only 2 of the 10 sites were negative for the pathogens tested; samples collected at the other 8 sites were positive for the pathogens at least once. To gain a better picture of the potential human health risk, this study should be followed up with a more quantitative study of the occurrence of human pathogens in wildlife, taking into account the different natural habitats and behaviour of the different animal populations and a possible seasonal effect. Furthermore, the contamination of surface water with human pathogens should be investigated more extensively.  相似文献   

What the practicing veterinarian should know about rat bite fever     

Abma R  Boer H  Douma G  van Hoeck B  Lipman L  Gaastra W 《Tijdschrift voor diergeneeskunde》2008,133(16):668-670

  相似文献