Growth indices and stomatal control of transpiration in Acacia koa stands planted at different densities

We examined the influences of selected environmental variables on stomatal behavior and regulation of transpiration in 26-month-old Acacia koa Gray (koa) stands planted at spacings of 1 x 1 m or 2.5 x 2.5 m and grown without irrigation. Field measurements were made during recovery from an extended 60-day dry period with only 38 mm of precipitation. Biomass and leaf area were also measured at 3-month intervals over the first 24 months after planting and again following completion of the transpiration (T) and stomatal conductance (g(s)) measurements at about 26 months after planting. Transpiration was measured as sap flow through intact branches by a heat balance method. After a 22-day period during which 130 mm of rain were recorded, average T was substantially higher in the 2.5 x 2.5 m stand on both a leaf area and ground area basis even though leaf area index was about 3.5 times higher in the 1 x 1 m stand. After an additional 25 mm of rain during an 8-day period, T was still slightly higher on a leaf area basis in the 2.5 x 2.5 m stand but was about 3 times higher on a ground area basis in the 1 x 1 m stand. A strong stomatal response to humidity limited the increase in T with increasing evaporative demand. Values of g(s) in koa phyllodes were comparable to those reported for leaves of other mesic tropical forest trees, but were several times higher than those reported for Acacia species native to arid and semi-arid regions. The 1 x 1 m planting yielded three times more biomass per unit ground area than the 2.5 x 2.5 m planting. However, greater stand density, which resulted in more rapid depletion of soil water between rainfall inputs, was associated with lower growth efficiency and lower radiation conversion efficiency.     

The occurrence of Clostridium perfringens in the intestine of chicks

Commercial broiler chicks brooded either on wire or on used or new litter demonstrated a 75% (62/75) incidence of recovery of "perfringens-like" colonies from the intestine during a 5-week period. Eleven Clostridium spp. were identified from among these "perfringens-like" organisms, which were cultured on SPS selective agar medium. Clostridium perfringens was positively identified only infrequently (five isolates) from among the "perfringens-like" colonies. In contrast, "perfringens-like" colonies were not recovered from the intestinal contents of specific-pathogen-free chicks reared in an isolation unit. However, C. perfringens was isolated from the yolk sac of one embryonated egg and from the intestine of a single 7-day-old chick, indicating the possibility of vertical transmission of this potential pathogen.     

Forests planted for ecosystem restoration or conservation

Although the phrase, planting for ecosystem restoration, is of recent origin, many of the earliest large-scale tree plantings were made for what we now refer to as restoration or conservation goals. Forest restoration activities may be needed when ecosystems are disturbed by either natural or anthropogenic forces. Disturbances can impact (1) basic components of the system (e.g., plant and animal composition, soil pools, and atmospheric pools), (2) ecosystem processes, i.e., interactions among basic components, or (3) both components and processes. Early efforts at restoration or site rehabilitation focused primarily on reducing off-site impacts, such as sediment introduced into streams from ecosystems that had been severely disturbed. More recent restoration programs include ecosystems in which only some of the components are missing or some of the processes have been impacted. Restoration activities can begin immediately after the disturbance has ended. Although forest restoration projects can include many activities, planting is almost always a key component.When planning an ecosystem restoration project, land managers need to be aware that commonly used plant establishment and management procedures may need to be altered to meet project objectives. Some systems may have been so severely impacted that ameliorative activities, e.g., fertilization, liming, land contouring, and microsite preparation, will be necessary prior to planting. Managers may also need to take special measures to reduce herbivory, control competing vegetation, or reduce physical damage from wind or sun. Choice of species needs careful consideration. Desired species may not grow well on degraded sites, may need a nurse species to become established, or may not provide an opportunity to harvest a short-term crop to reduce restoration costs. New methods may need to be developed for projects that require underplanting or interplanting. The end result of restoration should be an ecosystem with the same level of heterogeneity inherent in an undisturbed system; thus, managers should consider how pre- and postplanting activities will affect system variability.As our understanding of ecosystems has increased, so has our expectation that restored ecosystems have the same components and function in the same manner as do undisturbed systems. These expectations require that land managers have more sophisticated information than was considered necessary previously. In the absence of more pertinent information, we can prescribe restoration activities based on results from related ecosystems or on theoretical considerations. Additional research, careful monitoring, and adaptive management are critical to our long-term success.     

Hormonal control of second flushing in Douglas-fir shoots

Spring-flushing, over-wintered buds of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) produce new buds that may follow various developmental pathways. These include second flushing in early summer or dormancy before flushing during the following spring. Second flushing usually entails an initial release of apical dominance as some of the current-season upper lateral buds grow out. Four hypotheses concerning control of current bud outgrowth in spring-flushing shoots were tested: (1) apically derived auxin in the terminal spring-flushing shoot suppresses lateral bud outgrowth (second flushing); (2) cytokinin (0.5 mM benzyladenine) spray treatments given midway through the spring flush period induce bud formation; (3) similar cytokinin spray treatments induce the outgrowth of existing current lateral buds; and (4) defoliation of the terminal spring-flushing shoot promotes second flushing. Hypothesis 1 was supported by data demonstrating that decapitation-released apical dominance was completely restored by treatment with exogenous auxin (22.5 or 45 mM naphthalene acetic acid) (Thimann-Skoog test). Hypothesis 2 was marginally supported by a small, but significant increase in bud number; and Hypothesis 3 was strongly supported by a large increase in the number of outgrowing buds following cytokinin applications. Defoliation produced similar results to cytokinin application. We conclude that auxin and cytokinin play important repressive and promotive roles, respectively, in the control of second flushing in the terminal spring-flushing Douglas-fir shoot.     

Antimicrobial activity of gallium against virulent Rhodococcus equiin vitro and in vivo

Rhodococcus equi, a facultative intracellular bacterium, causes severe pneumonia in foals. Evidence suggests that most foals become infected very early in life, when they have immature or ineffective innate immune responses. This study evaluated the antimicrobial activity of gallium against R. equi, as a potential chemoprophylactic and therapeutic agent. Rhodococcus equi was grown in media with various concentrations of gallium nitrate (GN), with and without excess iron. GN significantly inhibited growth and killed R. equi, and these effects were abolished with excess iron. Antimicrobial effects of Ga appear to be related to its interference with iron metabolism. Mice were treated orally with gallium maltolate (GaM), 10 or 50 mg/kg BW, or distilled H2O prior to and after experimental infection with R. equi. Six days post-infection, organs were harvested and R. equi concentrations assessed, and serum gallium concentrations determined. GaM was absorbed in a dose-dependent manner, and R. equi tissue burdens were greater in control mice than in all GaM-treated mice. GaM may aid in the control of disease by preventing development of overwhelming R. equi tissue burdens prior to the establishment of requisite innate and adaptive immune responses.     

Comparison of biofragmentable anastomosis ring and sutured anastomoses for subtotal colectomy in cats with idiopathic megacolon

OBJECTIVE: To report use of a biofragmentable anastomosis ring (BAR) device in cats with idiopathic megacolon (FIM) and compare outcome after subtotal colectomy with sutured colocolic anastomosis. STUDY DESIGN: Retrospective study. ANIMALS: Nineteen cats with megacolon. METHODS: Medical records (January 1990-January 2004) of cats treated surgically for idiopathic megacolon with sutured (SUT) or BAR anastomosis were retrieved and reviewed. Operative, short- and long-term complications, and survival times were recorded and Kaplan-Meier survival analysis used to assess outcome. RESULTS: There were 11 SUT and 8 BAR cats. One BAR cat had anastomotic dehiscence 36 hours after surgery. Mild serosal tearing during BAR insertion in 6 cats was corrected by suture reinforcement. One SUT cat developed anastomotic stricture at 32 days. Short-term complication rates at 3 and 7 days were 18% and 45% in the SUT group and 25% and 87.5% in the BAR group, respectively (P=.058). Two SUT cats had persistent loose stool consistency and were euthanatized 254 and 1661 days after surgery. One BAR cat had recurrence of constipation which was managed medically. Long-term complication rates were not significantly different between SUT and BAR (P=.61). The 1 and 4-year survival rates were 90% for SUT and 100% for BAR (P=.29). CONCLUSIONS: No difference was detected for short and long-term complication rates and survival times between SUT and BAR groups. CLINICAL RELEVANCE: The BAR device can be used for colocolic anastomosis in cats with idiopathic megacolon. Serosal tearing during BAR insertion was a common intraoperative complication. Regardless of anastomotic technique, survival outcome after colonic resection is excellent for cats with FIM.     

Characterization of the immune response of domestic fowl following immunization with proteins extracted from Dermanyssus gallinae

Dermanyssus gallinae is the most significant ectoparasite of European poultry egg laying production systems due to high costs of control and associated production losses as well as adverse effects on bird welfare. In this study, soluble proteins were extracted from unfed D. gallinae (DGE) using a urea-based detergent and ultra-filtration, passed through a 0.22 μm filter and blended aseptically with adjuvant. One group of laying hens was immunized with DGE and adjuvant (Montanide ISA 50 V) whilst another group (Control) received physiological saline and adjuvant. All birds were immunized on two occasions, 21 days apart. Antibody response to immunization was determined by ELISA and western blotting using immunoglobulins (Igs) extracted from egg yolk. DGE immunization of hens resulted in a significant (P < 0.05) IgY response compared to controls, although there was no significant difference in IgM response between treatments. A number of proteins were identified by western blotting using IgY antibodies from DGE immunized birds, most prominently at 40 and 230 kDa. Analysis of proteins from approximately corresponding bands on SDS-PAGE confirmed the identity of tropomyosin, whilst other proteins showed high sequence homology with myosin and actin from other arachnid and insect species. Immunization of hens with DGE resulted in a 50.6% increase in mite mortality (P < 0.001) 17 h after feeding when tested by an in vitro mite feeding model. Data in this study demonstrate that somatic antigens from D. gallinae can be used to stimulate a protective immune response in laying hens. Further work is needed to identify other proteins of interest that could confer higher protection against D. gallinae, as well as optimization of the vaccination and in vitro testing protocol.     

Evaluation of a real-time quantitative polymerase chain reaction assay for detection and quantitation of virulent Rhodococcus equi

OBJECTIVE: To evaluate a real-time quantitative polymerase chain reaction (QPCR) assay in the detection and quantitation of virulent Rhodococcus equi. SAMPLE POPULATION: 1 virulent, 2 intermediately virulent, and 2 avirulent strains of R. equi and 16 isolates of bacteria genetically related to R. equi. PROCEDURE: The QPCR assay was evaluated for detection and quantitation of the virulence-associated gene (vapA) of R. equi in pure culture and in samples of tracheobronchial fluid, which were inoculated with known numbers of virulent R. equi. Results were compared with those derived via quantitative microbial culture and standard polymerase chain reaction methods. RESULTS: The QPCR assay detected the vapA gene in pure culture of R. equi and in tracheobronchial fluid samples that contained as few as 20 CFUs of virulent R. equi/mL and accurately quantitated virulent R. equi to 10(3) CFUs/mL of fluid. The assay was highly specific for detection of the vapA gene of virulent R. equi and was more sensitive than standard polymerase chain reaction for detection of R. equi in tracheobronchial fluid. CONCLUSIONS AND CLINICAL RELEVANCE: The QPCR assay appears to be a rapid and reliable method for detecting and quantitating virulent R. equi. The accuracy of the QPCR assay is comparable to that of quantitative microbial culture. The increased sensitivity of the QPCR method in detection of virulent R. equi should facilitate rapid and accurate diagnosis of R. equi pneumonia in foals.