The impacts of Phalaris arundinacea (reed canarygrass) invasion on wetland plant richness in the Oregon Coast Range, USA depend on beavers     

Thaïs E. Perkins  Mark V. Wilson 《Biological conservation》2005,124(2):291-295

Invasive plants can threaten diversity and ecosystem function. We examined the relationship between the invasive Phalaris arundinacea (reed canarygrass) and species richness in beaver wetlands in Oregon, USA. Four basins (drainages) were chosen and three sites each of beaver impoundments, unimpounded areas and areas upstream of debris jams were randomly chosen in each basin for further study (n = 36). Analysis of covariance (ANCOVA) showed that the relationship between Phalaris and species richness differed significantly (p = 0.01) by site type. Dam sites (beaver impoundments) exhibited a strong inverse relationship between Phalaris and species richness (b_D = −0.15), with one species lost for each 7% increase in Phalaris cover. In contrast, there was essentially no relationship between Phalaris cover and species richness in jam sites (debris jam impoundments formed by flooding; b_J = +0.01) and unimpounded sites (b_U = −0.03). The cycle of beaver impoundment and abandonment both disrupts the native community and provides an ideal environment for Phalaris, which once established tends to exclude development of herbaceous communities and limits species richness. Because beaver wetlands are a dominant wetland type in the Coast Range, Phalaris invasion presents a real threat to landscape heterogeneity and ecosystem function in the region.  相似文献   

(E)-1-(2,3,6-trimethylphenyl)buta-1,3-diene: a potent grape-derived odorant in wine     

Janusz A  Capone DL  Puglisi CJ  Perkins MV  Elsey GM  Sefton MA 《Journal of agricultural and food chemistry》2003,51(26):7759-7763

(E)-1-(2,3,6-Trimethylphenyl)buta-1,3-diene (TPB) was identified as a potent odorant in acid hydrolysates of crude glycoconjugate fractions isolated from grapes and grape vine leaves. TPB was also identified in a Semillon wine, using gas chromatography/mass spectrometry, by co-injection with an authentic sample. TPB had an aroma detection threshold of 40 ng/L in a neutral white wine and the concentration of TPB in four out of five white wines analyzed ranged from 50 to 210 ng/L.  相似文献   

Agreement of stall-side and laboratory major crossmatch tests with the reference standard method in horses     

Melissa S. Fenn  Araba D. Bortsie-Aryee  Gillian A. Perkins  Sabine Mann  Joy E. Tomlinson  Emma M. Wood  Susan E. Mix  Tracy Stokol 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2020,34(2):941-948

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A preliminary study on the effect of manuka honey on second-intention healing of contaminated wounds on the distal aspect of the forelimbs of horses     

Bischofberger AS  Dart CM  Perkins NR  Dart AJ 《Veterinary surgery : VS》2011,40(7):898-902

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Multiple immunofluorescence labelling enables simultaneous identification of all mature fibre types in a single equine skeletal muscle cryosection     

Tulloch LK  Perkins JD  Piercy RJ 《Equine veterinary journal》2011,43(4):500-503

Skeletal muscle is composed of a heterogeneous mixture of several fibre types, each with specific physiological properties. In equine muscle, identification of these individual fibres (fibre typing) is important for both exercise physiology and pathological studies. Traditionally, fibre typing has been achieved by adenosine triphosphatase (ATPase) histochemistry or by immunoperoxidase labelling with antibodies directed at myosin heavy chain isoforms. ATPase histochemistry can be temperamental and lacks specificity, and both techniques require staining of serial cryosections to reveal the entire fibre type compliment of a single sample, which is time consuming and prone to inaccuracy. Here we describe an immunofluorescence labelling technique that enables rapid, accurate and specific identification of the 3 mature equine muscle fibre types in a single cryosection.  相似文献   

Effect of development of the ovine forestomachs on the anatomy of portal vessels and on the intrahepatic distribution of portal blood     

T J Heath  N R Perkins 《Research in veterinary science》1985,39(2):216-221

The two main tributaries of the ovine portal vein are the splenic vein, which carries blood mainly from the spleen and forestomachs, and the cranial mesenteric vein. In newborn lambs, these veins are of similar size and they converge at an angle of about 120 degrees. Blood which is carried from the intestines in the cranial mesenteric vein is not completely mixed with that from the splenic vein and it is preferentially distributed to the right side of the liver. As the fore-stomachs develop, the splenic vein becomes relatively larger than the cranial mesenteric and its direction of flow becomes oriented more caudally. Thus in the portal vein of sheep, blood in the cranial mesenteric vein meets a larger volume of blood flowing in almost the opposite direction from the splenic vein. As a result, the extent of mixing of blood in the portal vein of adult sheep is much greater than in young lambs.  相似文献   

Serologic and cross-protection studies with several infectious bronchitis virus isolates from Delmarva-reared broiler chickens   总被引：3，自引：0，他引：3  

J Gelb  B E Perkins  J K Rosenberger  P H Allen 《Avian diseases》1981,25(3):655-666

Five isolates, from broiler-type chickens, capable of causing acute respiratory disease were identified as infectious bronchitis virus (IBV). The agar-gel precipitin (AGP) test was effective in identifying the isolates as IBV. Virus-neutralization (VN) and cross-challenge tests indicated two of the isolates to be Massachusetts types and one to be a JMK type. The remaining isolates were different from strains normally encountered in chickens reared on the Delmarva Peninsula. One isolate, although serologically similar to the Connecticut strain, was able to infect Connecticut-virus-immune chickens. Another isolate was similar to Arkansas 99, a strain not previously reported in Delmarva.  相似文献   

Modulation of Ovarian Function in Female Dogs Immunized with Bovine Luteinizing Hormone Receptor     

BB Saxena  A Clavio  M Singh  P Rathnam  Y Bukharovich  T Reimers Jr    A Saxena  & Scott Perkins 《Reproduction in domestic animals》2002,37(1):9-17

Adult female dogs were immunized with 0.5 mg bovine luteinizing hormone receptor (LH-R) encapsulated in a silastic subdermal implant and subsequently with four intramuscular booster injections of 0.1 mg LH-R each. Circulating LH-R antibody was detected in the sera 3 weeks post-implant. The appearance of LH-R antibody was associated with a decline in the serum progesterone concentrations to a range of 0–0.5 ng/ml until day 365 in the immunized dogs in comparison with a range of 5–10 ng in the control animals, suggesting a lack of ovulation and corpus luteum function in immunized dogs. The immunized dogs did not show signs of `standing heat' and failed to ovulate when induced by LH-RH challenge. Serum oestradiol levels, however, remained in the range of 30–40 pg/ml in both the immunized and the control dogs. With the decline in the antibody titres, the hormonal profile and vaginal cytology returned to a fertile state and the dogs exhibited signs of `standing heat', as well as vaginal bleeding. Dogs immunized with LH-R did not show any serious metabolic, local or systemic adverse effects. The hypothalamic–pituitary gonadal axis remained intact as indicated by little difference in pituitary LH levels between control and immunized animals, and by the release of LH by LH-RH challenge. These studies demonstrate that active immunization of female dogs with LH-R could immunomodulate ovarian function to cause a reversible state of infertility. It may be postulated that, due to extensive interspecies homology, a recombinant LH receptor-based immunocontraceptive vaccine may also be effective in other vertebrates.  相似文献   

Comparisons of Uptake and Depuration of 2-Methylisoborneol in Male, Female, Juvenile, and 3MC-induced Channel Catfish Ictalurus punctatus     

Everett J.  Perkins Daniel  Schlenk 《Journal of the World Aquaculture Society》1997,28(2):158-164

The occurrence of off-flavors in farm-raised channel catfish is a major burden to the catfish culture industry, causing millions of dollars worth of market-ready fish to be rejected each year. Off-flavors are believed to be the result of exposure and subsequent accumulation of certain volatile microbial metabolites such as 2-methylisoborneol. In this study, the uptake and elimination of [¹⁴C]-2-methylisoborneol equivalents were examined in juvenile and mature channel catfish. The described method is presented as a simple and inexpensive procedure for comparing treatment effects on off-flavor elimination rates. In addition, the effects of the cytochrome P4501A inducing agent 3-methylcholanthrene on 2-methylisoborneol depuration was studied in juvenile fish. Uptake was determined during a 24–h static exposure to waterborne 2-methylisoborneol (7.6 ± 3.7 μg/L). Uptake equilibrium had been established in all groups by 12 h, with total uptake higher in juvenile fish. Depuration rates were not different between untreated groups (t_½ a = 12.r122.4 h; t_½β= 91.3–143.7 h); however, the depuration half-lives for 3-methylcholanthrene treated juveniles were significantly longer than those of controls.  相似文献   

Effect of radiographic positioning on the heart shadow in dogs     

R L Perkins 《Modern veterinary practice》1979,60(10):801-805

Dorsoventral thoracic radiographs of 9 dogs were taken from 0 degree to 20 degrees to the right and to the left of a vertical line from mid-sternum to the mid-thoracic vertebrae. Certain measurements indicated that angles greater than 5 degrees from the vertical introduced significant distortions of the heart shadow and thoracic wall in some instances. A method is proposed for determining from a DV thoracic radiograph when improper positioning has produced an angulation greater than 5 degrees.  相似文献