Ethylene in a compacted field soil and its effect on growth,tuber quality,and yield of potatoes

Ethylene (C₂H₄) produced by soil microorganisms at concentrations sufficient to affect root development has previously been identified in the gas phase of anaerobic or partially anaerobic soils. This research was initiated to establish the existence of and to determine concentrations of C₂H₄ in soil in relation to matric potential, oxygen (O₂) and compaction, and effects on growth and tuber yield of potatoes (Solanum tuberosum L.). Ethylene initially appeared at the 10-cm depth after 2.5-cm/day increments of water were applied by furrow irrigation for 3 days. Levels of C₂H₄ increased to 18.4 ppm and O₂ decreased to 8% after 12.5 cm of water had been applied in 2.5-cm increments for 5 days. Ethylene was found in two partially compacted plots. High C₂H₄ concentrations and low O₂ levels in the soil atmosphere were associated with reduced top growth, leaf injury, lower tuber quality, and a 20% decrease in potato yields. Since C₂H₄ and low O₂ levels occur simultaneously in soil, further research is needed to identify their individual effects on root and tuber development.     

Reaction of lotic periphyton to experimental acidification

Two hypotheses that could explain increases in the biomass and production of lotic periphytic communities in acidified habitats were tested: 1) a greater bioavailability of P due to its greater release from sediments at low pH, and 2) utilization of S from the H₂SO₄ addition. The experiments were performed in semi-natural conditions by submitting the periphyton to either continuous or episodic acidification. The uptake of P and S by periphyton were determined at different times during the treatments. The increases in P and S uptake, in acidified habitats, are compatible with both hypotheses and could account for the increase in periphytic biomass and production.     

Reinvestigation of the effect of heat pretreatment of corn fiber and corn germ on the levels of extractable tocopherols and tocotrienols

We previously reported that heat pretreatment of corn fiber (150 degrees C, 1 h) caused a tenfold increase in the levels of extractable gamma-tocopherol. The current study was a reinvestigation of the previous effect, using improved methods (HPLC with fluorescence detection, diode-array UV detection, and mass spectrometry) for tocol analysis. Heat pretreatment did not cause an increase in the levels of any of the tocopherols or tocotrienols in corn fiber oil, but lowered the levels of three of the tocols and had no effect on the levels of the other two tocols. Heat pretreatment of corn germ had a similar effect. UV and mass spectra indicated that the peak that we had identified as gamma-tocopherol in our previous report was probably a mixture of oxidation products of triacylglycerols. Thus, heat treatment of corn germ or other corn-oil containing fractions at high temperatures leads to decreases in gamma-tocopherol, gamma-tocotrienol, and delta-tocotrienol and to the production of triacylglycerol oxidation products.     

Topical effect of various agents on gelatinase activity in the tear film of normal dogs

OBJECTIVE: To evaluate the topical effect of various agents, currently used in the treatment of melting ulcers, on gelatinase activity present in the tear film of normal dogs. ANIMAL STUDIED: Eight normal adult beagles. PROCEDURES: Each animal received the following agents: cyclosporine A 1%, N-acetylcysteine 10%, ciprofloxacin 0.3%, ethylenediaminetetraacetic acid (EDTA) 1%, doxycycline 0.001%, polysulfated glycosaminoglycans (PSGAG) 5%, autoserum, and artificial tears during a 48-h period following a Latin square design. Tear samples were collected with micro-capillary pipettes following a corneal surface irrigation of each eye with sterile saline on four different occasions. Basal and total gelatinase activities were evaluated by optical density after processing in a commercial gelatinase activity assay. From the optical density ratio, a semi-quantitative measure of gelatinase activity was obtained. Basal and total activities were measured in all samples. RESULTS: The lowest total gelatinase activity, representing a percent decline in the enzyme activity although not significant, was observed 1 h after the last treatment in seven out of the eight ophthalmic agents; EDTA (68%), ciprofloxacin (76%), cyclosporine A (68%), doxycycline (47%), artificial tears (26%), PSGAG (25%), and N-acetylcysteine (20%). However, only the reduction observed with EDTA 6 h after the last treatment was significantly lower compared to the reduction observed with the artificial tears. CONCLUSION: This study indicated that only EDTA was able to significantly reduce the gelatinase activity in a persistent manner in the tear film of normal canine eyes. Further studies will be required to evaluate the effect of EDTA under ulcerative conditions and to more accurately ascertain the potential in vivo effect of the other agents.     

Inhibition of aflatoxin biosynthesis in Aspergillus flavus by diferuloylputrescine and p-coumaroylferuloylputrescine

A mixture of diferuloylputrescine/p-coumaroylferuloylputrescine (85:15, w/w) demonstrated inhibitory activity against aflatoxin B1 biosynthesis in Aspergillus flavus isolate AF13. Inhibition was concentration dependent, with a 50% effective dose of 30 microg of diferuloylputrescine/p-coumaroylferuloylputrescine per milliliter of medium. Aflatoxin inhibition levels of up to 93% were achieved using this conjugated polyamine material. This diconjugated polyamine mixture did not display inhibitory effects on A. flavus growth (mycelial weight) at any of the concentrations tested. A survey of hand-dissected corn (Zea mays) kernel tissues, including endosperm, germ, pericarp, and wax, revealed that the highest concentrations of these conjugated polyamines were localized in the pericarp of the seed. Analysis of a number of corn accessions did not reveal a correlation between diferuloylputrescine/ p-coumaroylferuloylputrescine concentration and resistance/susceptibility to A. flavus infection. The localization of these diconjugated polyamine components in the pericarp, which functions as a physical barrier and surrounds the internal food storage reserves, suggests a defensive role for these materials.     

Vitamin C supplementation and fear‐reduction in Japanese quail: Short‐term cumulative effects

1. Fear‐related behaviour was measured in individually‐housed Japanese quail which had received either untreated drinking water (UDW) or a vitamin C solution (ascorbyl‐2‐polyphosphate, APP, 1 g L‐ascorbic acid/1) for 1 or 4 d. Behavioural tests were carried out at 24 or 27 d of age. Water consumption was measured daily and plasma ascorbic acid (AA) content was assayed after differential treatment for 1 or 4 d.

2. The quail in the APP treatment groups drank significantly more than did those receiving untreated drinking water.

3. Supplementation with APP raised plasma AA concentrations substantially above those found in UDW quail. The lower AA concentrations found after APP treatment for 4 d rather than one may have reflected either inter‐assay variation or limited intestinal absorption following excess ingestion.

4. Quail treated with APP showed less home‐cage avoidance of a novel object and shorter tonic immobility fear reactions than did the UDW birds. The UDW quail showed remarkably similar avoidance and TI scores on test days 1 and 4. Conversely, continued treatment with APP further reduced avoidance scores but, although TI durations fell slightly with continued treatment there were no significant day effects.

5. It was concluded that APP supplementation can reduce underlying fearfulness but that it may not be necessary to continue treatment for longer than 24 h immediately prior to a known frightening event.     

Locked jaw syndrome in dogs and cats: 37 cases (1998-2005)

A consecutive series of cases of dogs and cats with locked jaw syndrome (inability to open or close the mouth) are reported in this study. Dogs were significantly overrepresented (84.0%) and adult dogs were more frequently affected (81.0%). Temporomandibular joint ankylosis due to fracture was the most common cause (54.0%) of locked jaw syndrome. Additional potential causes of locked jaw syndrome are masticatory muscle myositis, neoplasia, trigeminal nerve paralysis and central neurological lesions, temporomandibular joint luxation and dysplasia, osteoarthritis, retrobulbar abscess, tetanus, and severe ear disease. Treatment of locked jaw is directed towards the primary cause. It is important to treat the tonic spasm in order to minimize periarticular fibrosis. Surgical intervention is recommended for temporomandibular joint ankylosis. Masticatory muscle myositis treatment is initiated by gradually opening the mouth, with medical treatment based on immunosuppressive therapy. Fracture and masticatory muscle myositis are associated with a relatively good prognosis in regard to short-term outcome as compared to animals with central neurologic lesions or osteosarcoma which have a poor prognosis.