Field Assessment of Outcrossing from Transgenic Pea (Pisum Sativum L.) Plants
The frequency of outcrossing from a transgenic line of peas into three cultivars ('Carneval', 'Montana', 'Tipu') was studied in the field in 1997 and 1999. Two dominant traits, normal leaf form and a highly-expressed β-glucuronidase (gusA) gene, were used as markers of pollen transfer. Because of heterogeneity in the commercial seed sources, leaf form alone was unreliable for assessing pollen migration into 'trap' plants. Of approximately 9000 offspring tested, only five plants scored positive for the presence of both markers. All five were located in 'trap' plots situated near the transgenic line. This represents a mean outcrossing rate of 0.07%.
Bean α-amylase inhibitor 1 in transgenic peas (Pisum sativum) provides complete protection from pea weevil (Bruchus pisorum) under field conditions
Two α-amylase inhibitors, called αAI-1 and αAI-2, that share 78% amino acid sequence identity and have a differential specificity toward mammalian and insect α-amylases are present in different accessions of the common bean (Phaseolus vulgaris). Using greenhouse-grown transgenic peas (Pisum sativum), we have shown previously that expression of αAI-1 in pea seeds can provide complete protection against the pea weevil (Bruchus pisorum). Here, we report that αAI-1 also protects peas from the weevil under field conditions. The high degree of protection is explained by our finding that αAI-1 inhibits pea bruchid α-amylase by 80% over a broad pH range (pH 4.5–6.5). αAI-2, on the other hand, is a much less effective inhibitor of pea bruchid α-amylase, inhibiting the enzyme by only 40%, and only in the pH 4.0–4.5 range. Nevertheless, this inhibitor was still partially effective in protecting field-grown transgenic peas against pea weevils. The primary effect of αAI-2 appeared to be a delay in the maturation of the larvae. This contrasts with the effect of αAI-1, which results in larval mortality at the first or second instar. These results are discussed in relationship to the use of amylase inhibitors with different specificities to bring about protection of crops from their insect pests or to decrease insect pest populations below the economic injury level.
The etiology and surgical management of tracheal collapse in calves.
The mean ages of 10 calves with tracheal collapse were 2.7 weeks at onset of clinical signs and 9.4 weeks at presentation for treatment. Inspiratory and expiratory dyspnea and stunted growth were the most common clinical signs. There were abnormalities of the cranial ribs consistent with healing fractures with redundant callus in eight lateral thoracic radiographs. Tracheal collapse in calves may result from cranial thoracic trauma during or soon after birth. Short polypropylene ring prostheses made from 60 ml syringe barrels were placed on the tracheas of four calves with cervical tracheal collapse. There were cranial rib masses in all calves and resection of the right first and second ribs was necessary in one calf to allow placement of prostheses. Dyspnea was relieved in all calves. One calf died of unrelated causes in year 3, and one calf had recurrence of clinical signs at month 5 and was euthanatized. In both calves, tracheal stenosis resulted from continued growth and infolding of the trachea within the constraints of the prostheses. One calf was alive at month 11, and one calf died of acute bronchopneumonia on day 2. Removal of tracheal prostheses in calves is recommended after 2 to 3 months if clinical signs recur.