Micro-grafting shoot-tip culture of citrus on three trifoliolate rootstocks

Simple techniques and growth regulator treatments to improve micro-grafting success of ‘Mexican’ lime, ‘Valencia’ orange and ‘Star Ruby’ grapefruit were studied. Most scion cultivars grafted best on ‘Carrizo’ citrange [Poncirus trifoliata (L.) Rat. x Citrus sinensis (L.) Osbeck]. Dipping the shoot-tip in 2,4-D or kinetin before grafting doubled the percentage of successful grafts. Highest grafting success occurred when the scion shoot-tip was placed in an inverted-T incision on the epicotyl of the rootstock.     

In vitro propagation of ‘Troyer’ citrange from epicotyl segments

Isolated epicotyl, root meristem and root segment tissues of ‘Troyer’ citrange [Poncirus trifoliata (L.) Rat. × Citrus sinensis (L.) Osbeck] were established in continuous culture to compare their regeneration potential. Callus was obtained from these explants on a Murashige—Skoog (MS) medium containing NAA (10 mg l^?1) and BAP (0.1–10 mg l^?1). Formation of shoots from root segments was direct without callus formation on MS medium containing BAP (10 mg l^?1) and NAA (1 mg l^?1). Shoot formation from epicotyl callus occurred on MS medium containing 0.25 mg l^?1 BAP and 0.1 mg l^?1 NAA. Formation of shoots from epicotyl segments occurred on MS medium containing BAP (0.5 mg l^?1) and NAA (0.1–1.0 mg l^?1), while rooting of regenerated shoots occurred in treatments containing 2.0 mg l^?1 NAA alone. This system provides a rapid method for propagation of ‘Troyer’ citrange.     

Onset,kinetics and duration of in vivo and in vitro delayed hypersensitivity responses of neonatal calves sensitized with mycobacterial components

Newborn calves developed delayed skin-test responses 10 days after a single intradermal inoculation at birth with 150 μg of purified derivative of Mycobacterium bovis associated with 150 μg of mycobacterial immunopotentiating glycolipid P3 and oil droplets. Development of tuberculin skin-test reactivity was detected simultaneously with increased lymphocyte transformation responses. Longitudinal studies revealed that two of three calves tested at 17 months of age were still skin-test positive. The kinetics of cellular hypersensitivity responses in neonatal calves sensitized with mycobacterial components are compared to the results of acquired cellular resistance and delayed hypersensitivity studies in phylogenetically disparate species. We concluded that bovine neonates have the capacity to rapidly develop cellular immune responses following stimulation with mycobacterial antigens.     

Isolation of virus and antibody containing immune complexes from mink with Aleutian disease by affinity chromatography of equine complement clq

Affinity chromatography on immobilized equine complement Clq was used for the isolation of complement-binding immune complexes in sera of mink infected with Aleutian disease virus. Immune complexes were isolated and quantitated from 4 of 5 infected mink, as early as 2 weeks after infection and before hypergammaglobulinemia had appeared. The quantity of immunoglobulin G in these immune complexes ranged from 180 to 370 micrograms/ml serum. There were no Clq-binding immune complexes found in mink which were negative for Aleutian disease antibody. Using 125I-labeled BSA-anti-BSA complexes, we demonstrated that the affinity columns bound selectively immune complexes which had formed in antibody excess, whereas immune complexes in antigen excess were not bound. By neutralization of sensitized virus with anti-mink IgG serum, non Clq-binding immune complexes were also detected, which indicates that circulating immune complexes in persistently infected mink are heterogeneous as far as their reactivity with equine Clq is concerned.     

Allelopathy in citrus orchards

The involvement of allelopathy in citrus orchards is indicated by the discovery of a phenolic phytotoxin in soils and partly decomposed citrus root residues. The phytotoxin, which was tentatively identified as homovanillic acid, is produced by the anaerobic decomposition of citrus roots in the deeper soil horizons. It caused an arrest in rough lemon (Citrus jambhiri) radicle elongation and a severe swelling of the root tip.     

Establishing trees in an Appalachian silvopasture: response to shelters, grass control, mulch, and fertilization

In order to successfully introduce trees into existing pastures, it is important to determine and recommend a whole range of tree establishment practices. In the spring of 1995, approximately 350 bare-root seedlings each of black walnut (Juglans nigra L.) and honeylocust (Gleditsia triacanthos L.) were planted in six randomized paddocks within a silvopastoral study area at the Agroforestry Research and Demonstration Site in Blacksburg, Virginia. Three seedling establishment studies were tested, including (1) a tree protection study, (2) a water retention study, and (3) a fertilization study. Seedlings were planted using two different tree shelters (60 cm-tall poultry wire cage and 1.2 m-tall plastic Tubex), two water retention treatments (mulch and herbicide spray), and one fertilizer treatment. All treatments were compared to untreated controls. Tree survival, damage, and stem volume were compared for each species. Tree survival was comparable among all studies over three growing seasons. Tree establishment using poultry wire and Tubex shelters resulted in significant reduction of deer damage and significant increase in stem volume from 1996 to 1998. Tubex shelters had a pronounced positive impact on tree height and also on stem form; height of both black walnut and honeylocust was twice the height of control seedlings. Mulch and herbicide treatments for moisture control resulted in significant stem volume increases over thecontrol treatment from 1997 to 1998. However, mulching was less effective than the herbicide treatment. There was no significant tree growth response resulting from fertilization during this same period. This revised version was published online in June 2006 with corrections to the Cover Date.     

Pregnancy Rates to Fixed Embryo Transfer of Vitrified IVP Bos indicus,Bos taurus or Bos indicus × Bos taurus Embryos

The pregnancy rates obtained after the transfer of cryopreserved in vitro‐produced (IVP) embryos are usually low and/or inconsistent. The objective of this study was to evaluate the pregnancy rates of Holstein, Gyr and Holstein × Gyr cattle after the transfer of vitrified IVP embryos produced with X‐sorted sperm. Seventy‐two Gyr and 703 Holstein females were subjected to ovum pickup (OPU) sessions, followed by in vitro embryo production using semen from sires of the same breeds. Embryos (1636 Holstein, 241 Gyr and 1515 Holstein × Gyr) were exposed to forskolin for 48 h prior to vitrification. The pregnancy rate achieved with Gyr dam and sire was 46.1%, which was similar (p = 0.11) to that of Holstein dam and Gyr sire (40.3%). Crossing Gyr dams with Holstein sires resulted in a pregnancy rate of 38.9% and did not differ (p = 0.58) from the pregnancy rate obtained with the cross between Holstein dams and Gyr sires. The rate obtained with Holstein dam and sire was 32.5%. The average pregnancy rate was 36.6%, and no difference was found in the proportion of female foetuses (88.8%, in average) among breeds (p > 0.05). In conclusion, transfer of cryopreserved X‐sorted embryos represents an interesting choice for dairy cattle. Despite the small differences between pregnancy rates, we highlight the efficiency of this strategy for all of the racial groups studied.     

Prevalence of hereditary diseases in three-year-old horses of the Freiberger breed

The objective of this study was to investigate clinical signs indicating diseases with known or suspected hereditary components like equine sarcoid, insect bite hypersensitivity, osteochondrosis, allergic airway diseases, podotrochleosis, prognatism and wind-sucking in the franches-montagnes horse.We performed a clinical examination on 702 three-year-old, privately owned franches-montagnes horses, which were shown at the Swiss-Field-Tests in 2004.With the help of the owners a questionnaire on health, environment and feeding habits of the animals was completed. In 11.9% of the horses, sarcoids were detected, 6.2% carried one tumor and 5.7% had several. The prevalence was higher in chestnuts (16.6%) than in bays (10.1%). The prevalence of sarcoids in offspring from sires with known sarcoids (data from Station-Tests 1994-2005) was not significantly higher than in descendants from stallions without a known history of sarcoids. Clinical signs of insect bite hypersensitivity were only found in six horses (0.9%). In 12.0% hoof abnormalities like brittle horn, ring hoofs or hoof cracks of different degrees were recorded. The angle between hoof base and hoof wall was 56.7 +/- 0.1 degrees, the average hoof width was 13.7 +/- 0.3 cm in the front feet. For both of these measures we found no significant difference between left and right feet. With the exception of a high sarcoid prevalence, our results indicate that the franches-montagnes horse is a healthy breed overall.     

A region on equine chromosome 13 is linked to recurrent airway obstruction in horses

REASONS FOR STUDY: Equine recurrent airway obstruction (RAO) is probably dependent on a complex interaction of genetic and environmental factors and shares many characteristic features with human asthma. Interleukin 4 receptor a chain (IL4RA) is a candidate gene because of its role in the development of human asthma, confirmation of this association is therefore required. METHODS: The equine BAC clone containing the IL4RA gene was localised to ECA13q13 by the FISH method. Microsatellite markers in this region were investigated for possible association and linkage with RAO in 2 large Warmblood halfsib families. Based on a history of clinical signs (coughing, nasal discharge, abnormal breathing and poor performance), horses were classified in a horse owner assessed respiratory signs index (HOARSI 1-4: from healthy, mild, moderate to severe signs). Four microsatellite markers (AHT133, LEX041, VHL47, ASB037) were analysed in the offspring of Sire 1 (48 unaffected HOARSI 1 vs. 59 affected HOARSI 2-4) and Sire 2 (35 HOARSI 1 vs. 50 HOARSI 2-4), age 07 years. RESULTS: For both sires haplotypes could be established in the order AHT133-LEXO47-VHL47-ASB37. The distances in this order were estimated to be 2.9, 0.9 and 2.3 centiMorgans, respectively. Haplotype association with mild to severe clinical signs of chronic lower airway disease (HOARSI 2-4) was significant in the offspring of Sire 1 (P = 0.026) but not significant for the offspring of Sire 2 (P = 0.32). Linkage analysis showed the ECA13q13 region containing IL4RA to be linked to equine chronic lower airway disease in one family (P<0.01), but not in the second family. CONCLUSIONS: This supports a genetic background for equine RAO and indicates that IL4RA is a candidate gene with possible locus heterogeneity for this disease. POTENTIAL RELEVANCE: Identification of major genes for RAO may provide a basis for breeding and individual prevention for this important disease.     

Effects of genetic and environmental factors on chronic lower airway disease in horses

Background : Environment and genetics influence the manifestation of recurrent airway obstruction (RAO), but the associations of specific factors with mild, moderate, and severe clinical signs are unknown.
Hypothesis : We hypothesized that sire, feed, bedding, time outdoors, sex, and age are associated with clinical manifestations of mild, moderate, and severe lower airway disease.
Animals : Direct offspring of 2 RAO-affected Warmblood stallions (F1S1, n = 172; F1S2, n = 135); maternal half-siblings of F1S1 (mHSS1, n = 66); and an age-matched, randomly chosen control group (CG, n = 33).
Methods : A standardized questionnaire was used to assess potential risk factors and to establish a horse owner assessed respiratory signs index (HOARSI 1–4, from healthy to severe) according to clinical signs of lower airway disease.
Results : More F1S1 and F1S2 horses showed moderate to severe clinical signs (HOARSI 3 and HOARSI 4 combined, 29.6 and 27.3%, respectively) compared with CG and mHSS1 horses (9.1 and 6.2%, respectively; contingency table overall test, P < .001). Sire, hay feeding, and age (in decreasing order of strength) were associated with more severe clinical signs (higher HOARSI), more frequent coughing, and nasal discharge.
Conclusions and Clinical Relevance : There is a genetic predisposition and lesser but also marked effects of hay feeding and age on the manifestation of moderate to severe clinical signs, most markedly on coughing frequency. In contrast, mild clinical signs were not associated with sire or hay feeding in our populations.