Nitrogen absorption,translocation and distribution from urea applied in autumn to leaves of young potted apple (Malus domestica) trees

We studied the absorption, assimilation, translocation and distribution of nitrogen (N) from urea applied in autumn to leaves of 1-year-old potted Fuji/M26 apple (Malus domestica Borkh) trees. In early October, all leaves of each tree were painted with either 3% urea (enriched to 10 atom % with 15N) or water (control trees). Four trees were harvested before the treatment and N and amino acid contents were determined. Four trees from each treatment were harvested at 2, 4, 7, 10, 15 and 20 days after urea or water application. Total N, amino acids and 15N in leaves, bark, xylem, shank and roots were analyzed to determine uptake and mobilization of N from urea. Most uptake of 15N by leaves occurred during the first 2 days following application of urea. The mean rate of absorption during these 2 days was 0.29 g m-2 day-1. Amino acids in leaves, bark and roots increased significantly after urea application compared with control values. The highest concentrations of amino acids in leaves and bark occurred 4 days after application, whereas the highest concentrations of amino acids in roots occurred 10 days after application. Total 15N content in leaves peaked 2 days after urea application and then decreased, whereas 15N content in roots and bark increased throughout the experiment. Total 15N content in xylem and shank was low. Leaves absorbed 35% of the 15N applied as urea, and 63.6% of absorbed 15N was translocated out of leaves within 20 days after urea application. We conclude that N from urea was converted to amino acids in leaves after foliar application in autumn, and roots and bark were the main sinks of N from urea applied to leaves.     

Biochemical and hematologic values for 18 clinically healthy radiated tortoises (Geochelone radiata) on St Catherines Island, Georgia

BACKGROUND: The radiated tortoise (Geochelone radiata) is a critically endangered species in its native land, the southern portion of the island of Madagascar. Captive breeding programs have generated data on the breeding behavior and ecology of G radiata; however, hematologic and biochemical data also are critically important in managing populations. OBJECTIVE: The purpose of this study was to evaluate sex and seasonal effects on hematologic and biochemical data from captive radiated tortoises. METHODS: Whole blood was collected in January and August 2001 from 18 radiated tortoises (10 male, 8 female) housed at the Wildlife Survival Center on St Catherines Island, Georgia, as part of a routine health assessment. Routine hematologic and plasma biochemical analyses and electrophoresis were done using standard methods. Data from male and female tortoises were compared within and between seasons using 2-way ANOVA. RESULTS: RBC and HCT values were significantly higher in summer than in winter and were higher in males than in females. Total protein concentration did not differ significantly between males and females; however, female tortoises had significantly higher concentrations of alpha1- and beta-globulins in winter and summer compared to males. Male tortoises had significantly higher sodium and uric acid concentrations and LDH activity during winter, and higher urea concentration and LDH and CK activities in summer, compared with females. Female tortoises had significantly higher triglyceride and phosphorus concentrations in winter, and higher phosphorus, cholesterol, and triglyceride concentrations in summer, compared with males. CONCLUSION: Sex and seasonal differences in hematologic and biochemical values for radiated tortoises likely reflect vitellogenesis and egg production in females, and altered hydration status and activity in summer. Data from the tortoises in this study will be useful for the seasonal health assessment of this species.     

Antimicrobial activity of gallium maltolate against Staphylococcus aureus and methicillin-resistant S. aureus and Staphylococcus pseudintermedius: An in vitro study

Gallium is a trivalent semi-metallic element that has shown antimicrobial activity against several important human pathogens. This antimicrobial activity is likely related to its substitution in important iron-dependent pathways of bacteria. The genus Staphylococcus, which includes human and animal pathogens that cause significant morbidity and mortality, requires iron for growth and colonization. In this study, gallium maltolate, at various concentrations between 50 and 200μM, inhibited the in vitro growth of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) at time-points between 8 and 36h after inoculation. The inhibitory activity of gallium maltolate against clinical isolates of MRSA and methicillin-resistant Staphylococcus pseudintermedius (MRSP) from a veterinary teaching hospital was determined.