玉米F_2群体中偏分离RFLP标记在染色体上的分布及原因分析

研究了利用玉米85个 DNA 限制性片段长度多态性(RFLP)标记在玉米自交系7922与5003杂交 F2群体中的分离。结果表明,8.33%的标记显著或极显著地偏离了预期的孟德尔比例而表现偏分离,发现了2个偏分离的染色体热点,即第1染色体上的 umc128-umc107和第3染色体上的 asg24-asg48,其偏分离形成的主要原因是存在配子体选择。     

Evaluation of the Tibia as a Source of Autogenous Cancellous Bone in the Horse

A 1 cm defect was created in the proximal medial cortex of 12 tibiae, cancellous bone was removed from the site, and the bones were fractured by loading in torsion. The fractures did not occur through the donor sites and the fracture patterns and loads to fracture were similar for the treated tibiae and their untreated mates. Cancellous bone was harvested from the proximal medial aspect of both tibiae in nine adult horses. The soft tissue wounds were monitored for more than 10 days in seven horses and healing of the osseous defects was evaluated radiographically at regular intervals to month 6 in two horses. The site provided convenient access with the horses in lateral or dorsal recumbency, the anatomic landmarks were reliable, and the surgical procedure was simple and short. Complications occurred in only three incisions.     

Biocontrol efficacy of Colletotrichum truncatum for hemp sesbania (Sesbania exaltata) is enhanced with unrefined corn oil and surfactant

In greenhouse and field experiments, an oil-in-water emulsion of unrefined corn oil and Silwet L-77 increased the biological weed control efficacy of Colletotrichum truncatum (Schw.) Andrus et Moore for control of the weed, hemp sesbania ( Sesbania exaltata [Raf.] Rydb. ex A.W. Hill). The surfactant – corn oil emulsion stimulated germination and appressoria formation in vivo and in vitro and delayed the need for dew. We hypothesize that the corn oil protected the conidia from desiccation during the dew-free period and the surfactant stimulated spore germination and appressoria formation. In field experiments conducted over 3 years, a single application of a 50% (v/v) unrefined corn oil tank mixture containing 0.2% (v/v) Silwet L-77 surfactant controlled hemp sesbania in soybeans an average of 95%. Aqueous fungal suspensions or adjuvants alone did not visually affect or control hemp sesbania. The soybean yields were significantly higher in the plots where weeds were effectively controlled. These results suggest that formulating C. truncatum in unrefined corn oil and surfactant greatly increases its infectivity and the biocontrol potential of this pathogen.     

Leukocyte differentiation antigens in canine cutaneous and oral plasmacytomas

Seventeen cutaneous and oral tumours with light microscopic features of plasmacytomas from 16 dogs were studied. Clinically, most neoplasms were benign, although three recurred after excision and three were locally invasive. Tumours most often arose on the pinnae, digits, gingiva, and inguinal regions near areas of chronic inflammation and exhibited variable degrees of plasmacytic differentiation microscopically. Diagnosis of plasmacytoma was confirmed in paraffin-embedded tissues with a panel of leukocyte differentiation antigen markers that included cross-reactive antibodies for Mb-1 (CD79a), CD3, and vimentin and canine-specific antibodies for CD45RA and CD18. Immunoreactivity for Mb-1 and CD45RA, including staining of multinucleate cells and cells with karyomegaly, confirmed a B-cell origin of neoplasms, while staining for CD3 and CD18 revealed an extensive network of infiltrative T-cells and dendritic cells in tumours suggestive of a directed immune response. These findings (i) demonstrate the value of using a panel of antibodies for leukocyte antigens to differentiate plasmacytomas from other cutaneous and oral round cell tumours, and (ii) suggest that immune recognition and responsiveness within tumours may play a role in the behaviour of plasmacytomas in dogs by affecting tumour cell growth and differentiation.     

Effects of Nylon and Polyglactin 910 Suture Material on Perilimbal Corneal Wound Healing in the Dog

The effects of fine suture materials on corneal wound healing in the dog were studied. In 20 dogs, standardized perforating perilimbal clear corneal wounds were made and closed with either monofilament Polyglactin 910 or nylon. Five dogs each were euthanized 8,12,16, and 21 days postoperatively. Results of gross, biomicroscopic, and histologic examinations at 8,12,16, and 21 days showed nylon and Polyglactin 910 to cause similar inflammatory responses. Epithelialization and suppuration around the suture tracts were observed more frequently when Polyglactin 910 was used. Both materials were associated with a foreign body (granulomatous) response. There was no loss of wound integrity with either material. Strengths of the incised corneal tissues with and without the sutures intact were determined. At day 16 postsurgery, there was a statistically significant difference in tissue strengths between cases in which sutures were and were not intact. This difference was not apparent at 21 days postsurgery, which suggested that the suture dependent phase ends between the 16th and 21st postsurgical days. In addition, at day 16 there was no statistical difference between the tissue strength of wounds sutured with nylon or Polyglactin 910. Corneal suture materials studied should remain in place for at least 16 days, and absorbable material is only appropriate if it retains tensile strength for 16 days.     

The effects of climate variability on zooplankton and basking shark (Cetorhinus maximus) relative abundance off southwest Britain

At small spatial scales basking sharks (Cetorhinus maximus) forage selectively on zooplankton along thermal fronts, but the factors influencing broader scale patterns in their abundance and distribution remain largely unknown. Using long‐term sightings data collected off southwest Britain between 1988 and 2001, we show that the number of basking sharks recorded was highly correlated with abiotic factors, principally sea surface temperature (SST) and the lagged effect of SST in the previous month, but only very weakly to zooplankton density. This suggests that the changes in number of basking sharks recorded over large spatio‐temporal scales are more closely related to the availability of climate‐driven thermal resources than prey availability, whereas the converse is supported by previous studies at local scales. Taken together, these results imply scale‐dependent behavioural responses in basking sharks, with small‐scale foraging movements linked by broad scale responses to temperature variation.     

The Effects of Essential Fatty Acid Supplementation on Intradermal Test Reactivity in Atopic Dogs: a Preliminary Study

Abstract— Twenty-one perennially affected atopic dogs with previous intradermal test reactivity to two or more environmental allergens were retested while receiving either a combination of evening primrose oil and fish oil (EfaVet Regular, Efamol Vet) or a concentrated supplement containing gammalinolenic acid and eicosapentaenoic acid (HGF capsules). Significant differences in the mean number of positive reactions before and during therapy were not found. In addition, the mean histamine, Dermatophagoides pteronyssinus and housedust wheal diameters before and during therapy were not significantly different. However, the mean human dander wheal diameter was significantly reduced (P < 0.05) at the second test, and the mean Dermatophagoides farinae wheal diameter was significantly reduced (P < 0.05) in a group of seven dogs which had received long-term essential fatty acid supplementation with HGF capsules. These results indicate that essential fatty acid supplementation does not abrogate but may reduce intradermal test reactivity in atopic dogs. Résumé— Vingt et un chiens atopiques, présentant des symptômes non saisonniers, ayant eu des tests cutanés positifs à au moins un pneumallergène ont été testés alors qu'ils recevaient une association d'huile d'onagre et d'huile de poisson (Efa Vet Regular, Efamol Vet) ou un supplément concentré d'acides gammalinolénique et éicosapentaénoique (capsules HGF). Aucune différence significative dans le nombre moyen de réactions positives avant et après traitement n'a été observée. En outre les diamètres moyens des réactions à l'histamine. Dermatophagoïdes pteronyssinus et la poussère de maison avant et après traitement n'étaient pas significativement différents. Toutefois, le diamètre moyen des réactions aux squames humaines étaient significativement réduits (P < 0,05) lors du second test, et le diamètre moyen des réactions àDermatophagoïdes farinaeétait significativement réduit (P < 0,05) dans un groupe de sept chiens ayant reçu une supplémentation à long terme de capsules HGF. Ces résultate montrent qu'une supplementation en acides gras essentiel n'anihile pas les tests cutanés mais peu modérer la réactivité cutanée chez certains chiens atopiques. Resumen Veintiún perros atópicos de tipo estacional que presentaban reactividad positiva en la prueba de inyacciones intradérmicas con respecto a dos o más alergenos ambientales, fueron sometidos a una segunda prueba recibiendo simultáneamente una combinación de aceite de Evening Primrose y aceite de pescado (Efa Vet Regular, Efamol Vet) o un concentrado que contenía ácidos gammalinoleico y ecosapentanoico (HGF cápsulas). No se encontraron diferencias significativas en la media de las reacciones positivas antes y después de la medicación. Tampoco se encontraron diferencias significativas entre las medidas del diámetro de la roncha producida por la histamina, el Dermatophagoides pteronyssinus y el alergeno del polvo. Sin embargo, la media del diámetro producido por el alergeno de la caspa humana se vió considerablemente reducida en el segundo test (P < 0.05), así como la del Dermatophagoides farinae (P < 0.05) en un grupo de siete perros los cuales recibieron suplementación con ácidos grasos esenciales a largo plato con HGF cápsulas. Éstos resultados indican que el uso de ácidos grasos esenciales no produce supresión de las reacciones positivas del test intradérmico en perros atópicos, pero sí de las mismas.     

Comminuted First Phalanx Fractures in 30 Horses: Surgical vs. Nonsurgical Treatments

Comminuted first phalanx fractures were diagnosed in 30 horses. One leg was involved in each horse. Five horses were presented with open fractures. Nine horses had a portion of intact cortex (strut) extending from the proximal to distal joint. Ten horses were euthanized, including one with an open fracture, without treatment. The remaining 20 horses were treated by open reduction with a neutralization plate (8 horses, including one with an open fracture), open reduction with lag screw fixation (3 horses), lag screw fixation through stab incisions (2 horses), external coaptation with a cast (3 horses), and external skeletal fixation using a weight supporting shoe (4 horses, including 3 with open fractures).
Thirteen horses were euthanized following treatment because of persistent infection (9), chronic lameness (2), and third metacarpal bone fractures (2). Seven horses survived longer than 1 year after treatment. Six were lame and used as breeding animals, and one horse went on to race successfully. All four horses with open fractures that were treated were subsequently euthanized.
Significantly more horses with an intact strut of bone survived after treatment (4 of 7 [57%]) when compared to horses without an intact strut of bone that were treated (3 of 13 [23%]) (p < 0.05).
Invasive surgical approaches used for the repair of comminuted first phalanx fractures in this study were associated with an unacceptable infection rate (55%). Techniques involving less trauma to the compromised soft tissue around the fracture should afford a better chance for a successful outcome.     

Ulnar Subluxation Following Repair of a Fractured Radius in a Foal

Compression plating of a transverse mid-diaphyseal radial fracture in a 4-month-old Arabian filly resulted in subluxation of the ulna. Two screws transfixed the radius to the ulna and resulted in synostoses. This was followed by uncoordinated growth of the radius and ulna, and subluxation of the ulna. Progressive remodeling of the ulna subsequently reestablished articular congruity between the humerus and ulna.