Metabolism, uptake and translocation of 14C-paraquat in resistant and susceptible biotypes of Crassocephalum crepidioides (Benth.) S. Moore

The metabolism, uptake and translocation of paraquat in resistant (R) and susceptible (S) biotypes of Crassocephalum crepidioides (Benth.) S. Moore (redflower ragleaf) at the 10-leaf stage was investigated. A study on the properties of leaf surface was carried out to examine the relationship between leaf surface characters and paraquat absorption. The extractable paraquat was not metabolized by the leaf tissue of either the resistant or susceptible biotypes. Differential metabolism, therefore, does not appear to play a role in the mechanism of resistance. Both biotypes did not show any significant difference in the amount of cuticle and trichome densities. Furthermore, both biotypes are identical in the structure of stomata, trichomes and epicuticular wax. The results of the leaf surface studies are in agreement with the findings of the uptake study. Both biotypes demonstrated no significant difference in absorption between the resistant and susceptible biotypes. However, 10% of the absorbed ¹⁴C-paraquat into the S biotype was translocated basipetally, but not in the R biotype. The results of this study suggest that in C. crepidioides , differential translocation may contribute to the mechanism of resistance at the 10-leaf stage.     

Interference between triazine-resistant Brassica napus and Panicum miliaceum

Atrazine carryover often limits growers to production of atrazine-tolerant crops the year following application, and allows the increase of triazine-tolerant weed species such as Panicum miliaceum L. (wild proso millet). Tiriazine-resistant Brassica napus L. cv. ‘Triton’ (oilseed rape) was tested to characterize the nature of interspecific interference with P. miliaceum. In a greenhouse study, atrazine at 2.2 kg ha^?1 depressed oilseed rape fruit (siliqua) number and fruit dry weight, and delayed flowering, but did not significantly affect height or weight of shoots, Oilseed rape fruit weight was reduced at 200 P. miliaceum plants m^?2. fruit number and shoot weight were inhibited at 400 weeds m^?2. and height was reduced and flowering delayed at 600 weeds m^?2. Number and weight of fruits were reduced by one-third after 8 weeks of interference as compared to oilseed rape grown with the weed for 4 weeks. Oilseed rape height was reduced by 29% and shoot weight by 55% by 600 weeds m^?2 and 2–2 kg ha^?1 atrazine, while fruit number and weight were reduced by 72%. Oilseed rape shoot weight was reduced by 74% by 600 weeds m^?2 for 12 weeks of interference, while fruit number and weight were reduced by 85% and 82%. respectively. In a field study, fluazifop reduced early season P. miliaceum cover by 72%, but did not increase oilseed rape cover. Mid-season P. miliaceum shoot weight was decreased by 97% by fluazifop and oilseed rape shoot weight was increased by 34%. P. miliaceum control increased oilseed rape biomass by 38% at 89 days, but biomass of oilseed rape sown at 11.2 kg ha^?1 with 2.2 kg atrazine ha^?1 was not decreased by P. miliaceum interference at 89 days.     

Characterization of cereal bare patch isolates of Rhizoctonia solani by random amplified polymorphic DNA analysis

RAPD-PCR was used to characterize isolates of Rhizoctonia solani from bare patches in cereal and pasture crops at two locations in Western Australia, Newdegate and Esperance. All of the isolates belonged to anastomosis group 8, pectic zymogram group 1-1 or 2. The pectic zymogram assignment could be confirmed by RAPD-PCR. There was no difference in RAPD-PCR pattern between highly virulent and weakly virulent isolates at Newdegate, or between isolates from different patches at Newdegate. The Newdegate isolates were identical to isolates from Esperance, and to isolates from various locations in South Australia.     

Resistance of Erysiphe graminis on barley and wheat to sterol C-14-demethylation inhibitors1

Isolates of Erysiphe graminis f. sp. hordei and tritici with decreased sensitivity to triadimefon showed cross-resistance to other inhibitors of sterol C-14-demethylation, such as triadimenol, propiconazol, diclobutrazol, prochloraz and nuarimol. The isolates exhibited a moderate degree of resistance to these compounds. No cross-resistance was detected to tridemorph, fenpropimorph and pyrazophos. The resistant hordei isolates were more sensitive to ethirimol than the sensitive isolate. The competitive abilities of resistant hordei and tritici isolates were inferior to that of the sensitive isolates. In the presence of the fungicides no differences in germination, appressorium formation and penetration between the sensitive and resistant isolates were observed; 48 h after inoculation the sensitive isolate showed several morphological alterations and further fungal development was arrested. At four to five times higher doses of triadimefon, similar morphological alterations were detected in the resistant isolate. Low concentrations of triazole fungicides which slightly affected mycelium growth of both the sensitive and the resistant isolate of f.sp. hordei severely inhibited development of conidiophores of the sensitive isolate whereas that of the resistant isolate was hardly affected.     

Effect of tricyclazole on growth and secondary metabolism in Pyricularia oryzae

Tricyclazole [5-methyl-1,2,4-triazolo (3,4-b)-benzothiazole] controls rice blast disease caused by Pyricularia oryzae at concentrations (5–10 μg/ml) which do not inhibit growth of the pathogen in vitro. However, concentrations of 1 μg/ml or less inhibit melanin formation in the fungus. Production of pyriculol by the pathogen is usually enhanced by 10 μg/ml of tricyclazole, whereas production of 3,4-dihydro-4,8-dihydroxy-1(2H)-naphthalenone is strongly inhibited or markedly reduced and delayed. Evidence suggests that tricyclazole blocks aspects of polyketide metabolism in P. oryzae which may have a role in pathogenicity.     

A pattern in the appearance of cucumber powdery mildew in Dutch glasshouses

An inquiry was held in 1982, 1983 and 1984 to collect information on the survival and dispersal of cucumber powdery mildew. Growers who planted a crop in December, January or February were asked when they observed mildew for the first time in their crop. A gradual increase in the number of infected crops was observed from planting until May. The earliest observations of infected crops were immediately after planting. The weeks of the first observation of mildew, the disease-free periods and the apparent rates of increase of infected crops are presented for various districts. In the districts with the highest crop density (Pijnacker), mildew was generally observed early in the growing season, while the apparent rate of increase of infected crops was higher than in other districts. In the district with the lowest crop density (Northern Netherlands), mildew was observed late in the growing season and the apparent rate of increase of infected crops was low. Possible means of survival and dispersal of inoculum are discussed. It is suggested that overwintering of inoculum is possible because cucumber plants are grown all year round. Dispersal of cucumber powdery mildew is suggested to take place by transportation of infected planting stock, visitors and wind.     

A method for intervertebral space distraction before stabilization combined with complete ventral slot for treatment of disc-associated wobbler syndrome in dogs

Objective— To evaluate the use of a modified K-wire spacer for maintaining intervertebral distraction after ventral decompression and during stabilization as a treatment for disc-associated wobbler syndrome in large breed dogs.
Study Design— A retrospective study.
Animals— Dogs (n=7) with disc-associated wobbler syndrome.
Methods— Medical records (2003–2006) of dogs treated by a modified surgical method were evaluated. Data retrieved were signalment, onset and duration of clinical signs, neurologic abnormalities, diagnostic methods, surgical procedure, immediate, and long-term (≥1 year) postoperative clinical and radiographic outcome.
Results— Mean duration of clinical signs was 4.8 months. Neurologic signs included ataxia (2), ambulatory tetraparesis (2), and non-ambulatory tetraparesis (3). Three dogs had disc protrusion in 2 sites, 2 dogs had the procedure in 1 location and stabilization of both affected sites. All dogs improved dramatically and remained for 1–3 years. One dog had recurrence of cervical discomfort 13 months later.
Conclusions— Despite the limited number of dogs, overall initial successful outcome with only 1 dog having mild recurrence 13 months later supports further use and evaluation of this technique.
Clinical Relevance— Distraction using a K-wire spacer after ventral decompression followed by stabilization should be considered in dogs with disc-associated wobbler syndrome to prevent collapse of the intervertebral space.     

Adipose tissue gene expression in obese dogs after weight loss

Body weight (BW) mainly depends on a balance between fat storage (lipogenesis) and fat mobilization (lipolysis) in adipocytes. BW changes play a role in insulin resistance (IR), the inability of insulin target tissue to respond to physiological levels of insulin. This results in inhibition of lipogenesis and stimulation of lipolysis. Weight gain leads to IR whereas, weight loss improves insulin sensitivity (IS). The aim of this study was to evaluate the effect of weight loss and recovery of IS on the expression of genes involved in lipogenesis and lipolysis in weight losing dogs. Gene expression was studied in both subcutaneous and visceral adipose tissue. Obese dogs received a hypoenergetic low fat high protein diet (0.6 x NRC recommendation). Before and after weight loss, IS was assessed using the euglycaemic hyperinsulinaemic clamp. Gene expression of IRS-2, SREBP, intracellular insulin effectors, ACC, FAS, FABP, ADRP, PEPCK, lipogenesis key proteins, perilipin and HSL, lipolysis key proteins were quantified using real-time RT-PCR in subcutaneous and visceral fat. BW decreased from 15.2 +/- 0.5 to 11.4 +/- 0.4 kg (p < 0.05) over 78 +/- 8 days. When obese, dogs were insulin resistant. After weight loss, IS was improved. In the subcutaneous adipose tissue, the expression of only the IRS-2 was increased. In the visceral adipose tissue, the expression of the genes involved in the lipogenesis was decreased whereas one of the genes implied in the lipolysis did not change. The expression profile of genes involved in lipid metabolism, as measured after weight loss, is indicative for a lower lipogenesis after weight loss than in obese dogs. Our results also confirm dramatic differences in the lipid metabolism of visceral and subcutaneous fat. They should be completed by comparing gene expression during weight losing and normal weight steady state.     

Effect of feeding forest foliages, rice straw and concentrate-based total mixed ration on nutrient utilization and growth in mithun (Bos frontalis)

The study aimed to evaluate the effect of feeding Borrena hirticulata (BH), Ficus hirta (FH), rice straw (RS) and concentrate-based total mixed ration (TMR) on nutrient utilization, rumen fermentation and growth in mithun. Growing male mithun calves were randomly allotted to 2 feeding groups (6 in each), TMR₁ and TMR₂. The TMRs consisted of RS 300 g kg^− 1, concentrate 400 g kg^− 1 and BH 300 g kg^− 1 (TMR₁) or FH 300 g kg^− 1 (TMR₂) on a dry matter (DM) basis. Both TMRs were fed ad libitum to the animals for 121 d and a digestibility study was conducted during the last 7 d of the experiment. To assess rumen fermentation, rumen fluid was collected at 2 h interval for 24 h. Apparent digestibility of DM, crude protein (CP) and crude fibre (CF) did not differ significantly between the TMRs. Nevertheless, apparent digestibility of ether extract was found to be significantly (P < 0.01) greater in TMR₂ (0.59) compared to TMR₁ (0.54). Body weight gain (BWG; g d^− 1), DM intake (kg d^− 1), CP intake (g d^− 1) and feed efficiency (kg feed kg^− 1 gain) were found to be significantly (P < 0.05) greater in TMR₁ (548, 5.14, 713 and 9.28) compared to TMR₂ (496, 4.91, 703 and 10.03). An insignificant positive association (r = 0.35) between DM intake and BWG, but a significant (P < 0.01) positive association (r = 0.74) between CP intake and BWG were evident. Rumen pH (5.71 to 7.18) and ammonia-nitrogen (8.0 to 25.0 mg/dl) did not differ significantly between the TMRs, but differed significantly (P < 0.01) at different h post-feeding. In contrast, rumen total volatile fatty acid (42 to 105 mM) and total nitrogen (40.4 to 90.3 mg/dl) differed significantly (P < 0.05) between the TMRs and at different h post-feeding. The study revealed that BH, FH, RS and concentrate-based TMRs may be fed to mithun for satisfactory growth.