Uptake and metabolism of the phenylpyridazinone herbicide metflurazon during the bleaching and regeneration process of the green alga,Chlorella fusca

The uptake and metabolism of the pyridazinone herbicide metflurazon by the green alga Chlorella fusca was studied using a new and sensitive technique which is based on reverse-phase high-performance liquid chromatography. During the metflurazon-induced bleaching process, the agent is rapidly taken up and metabolized to the monomethyl derivative, norflurazon, by N-demethylation. Norflurazon accumulates during the treatment in the culture medium because Chlorella cells demethylate norflurazon to the less-phytotoxic SAN 9774 only to a very minor extent. It is shown that only 10% of the initial 1 μM metflurazon is sufficient to induce the bleaching process. This amount is much too small to directly inhibit the photosynthetic electron transport, so that a contribution of this site of action to the bleaching process is not likely. Treated Chlorella cells are able to regenerate to photosynthetically active cells. This phenomenon is based on the inability of the regenerating algae to further take up and demethylate metflurazon. Fully regenerated cells are resistant to metflurazon because a treatment with 1 μM metflurazon neither affects growth nor inhibits photosynthetic activity. This resistance results from an altered permeability of the cell membrane with respect to phenylpyridazinones and an inhibited N-demethylation of metflurazon. These results clearly show that metflurazon itself is nonphytotoxic, and has to be demethylated to norflurazon to exert its bleaching activity.     

Mycoplasma gallisepticum vaccination-challenge: an egg-production model.

Specific-pathogen-free layer hens in maximum lay were exposed by aerosol to a broth culture of Mycoplasma gallisepticum R' strain. Egg-production loss of greater than 50% was evident 7-14 days following challenge of unvaccinated chickens, with a gradual recovery during the next several days. Various vaccine preparations were tested to determine the effect in the model. All vaccinated chickens exhibited significantly (P < or = 0.05) lower egg-production loss than the unvaccinated controls. The model provides a method for testing treatment effects on egg-production losses resulting from controlled exposure to M. gallisepticum and may be useful in simulating field exposure.     

新出现和再流行的禽病

家禽疾病一直对社会经济和公众健康产生重要影响。近年来，人们对于食源性细菌感染和抗药菌株的出现更加关注，而且在一些国家中还掀起了重大的政治事件。本就新出现和再次流行的家禽疾病综述了其主要的研究进展。     

Demonstration of the genetic stability of a Mycoplasma gallisepticum strain following in vivo passage.

A Mycoplasma gallisepticum strain designated 6/85 (MGI) exhibiting reduced virulence for both chickens and turkeys was sequentially passaged 10 times in each species. DNA extracted from organisms before passage and those isolated after the third, sixth, and 10th passages was studied by restriction endonuclease DNA analysis using BamHI, BglII, EcoRI, HindIII, and PstI endonucleases. The virulent-type strain designated S6 was used as a comparison. Comparison of DNA fragment patterns of MGI and S6 strains showed distinct differences, although some similarities were evident. Passage of the strain in vivo did not affect DNA fragment patterns of the MGI strain. Electrophoretic protein patterns produced by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed very similar band patterns in both the MGI and S6 strains. The most notable differences were seen in bands located in the molecular-mass regions of approximately 46.5, 50-54, 58-64, and 105-140 kilodaltons. Alteration of band pattern profiles following in vivo passage of the MGI strain was apparent in a single band at approximately 86 kilodaltons that appeared to stain more intensely following passage.     

Passive immunoneutralization of endogenous inhibin increases ovulation rate in miniature Shiba goats

We reported previously that passive immunization against inhibin enhances follicular growth and increases the ovulation rate. However, the ovulation rate was not comparable to the number of follicles. Therefore, the aim of this study was to attempt to increase the ovulation rate by increasing the interval between inhibin immunization and PGF2alpha injection. Five miniature Shiba goats were treated with 10 ml inhibin antiserum (inhibin-AS) developed against [Tyro30]-inhibin alpha (1-30). A control group (n=5) was treated with normal goat serum. All animals were injected intramuscularly with 125 microg PGF2alpha 72 h after treatment to induce estrus and ovulation. Blood samples were collected for hormonal assay and the ovulation rate was determined by laparotomy. In contrast to the control group, there was a significant increase in plasma concentrations of FSH in the immunized group. After luteolysis, plasma concentrations of estradiol-17beta increased markedly to a preovulatory peak about 2 folds higher (P<0.01) than that of controls. In addition, the ovulation rate was greater in the immunized group (14.4 +/- 2.2) than in the control group (2.2 +/- 0.6), and the mean number of follicles > or = 4 mm in diameter was 10.0 +/- 0.8 in the inhibin-AS group compared with 2.4 +/- 0.3 in control group. The present results demonstrate that immunoneutralization of endogenous inhibin increased FSH secretions in miniature shiba goats. The increased FSH secretion enhanced follicular growth and increased the ovulation rate. Additionally, increasing the interval between inhibin-AS and PGF2alpha injections (to 72 h) resulted in a greater ovulation rate compared with the previous protocol (48 h). Therefore, inhibin-AS treatment proved to be an effective alternative to exogenous gonadotropin methods for induction of superovulation in goats.     

Early pregnancy diagnosis by means of ultrasonography as a method of improving reproductive efficiency in goats

Eighteen cyclic Shiba goats were used in this study. Estrus was synchronized with a single injection of 125 microg of a synthetic analogue of prostaglandin F(2)alpha (PGF(2)alpha) after detection of at least one corpus luteum by B-mode ultrasonography. Blood samples were collected from each animal on days 0, 7 and 21 post-mating for progesterone assay. Animals in estrus were either allowed to be mated by fertile bucks twice during estrus (group I; n=12) or not at all (group II; n=6). Ultrasonographic examinations were performed transrectally or transabdominally using a real-time B-mode scanner equipped with a 7.5 or 5 MHz transducer. All animals exhibited estrus 56.0 +/- 2.7 h after injection of PGF2alpha. The results show that the accuracy of the progesterone assay in diagnosing pregnancy on day 21 after mating was 80% for pregnancy and 100% for non-pregnancy, retrospectively. Ultrasonographic examinations showed that gestational sac and embryos heartbeats were detected on days 20.2 +/- 0.6 and 24.3 +/- 0.7 of gestation, respectively. Placentomes were detected on day 35.4 +/- 1.0 of gestation as small nodules (0.7 +/- 0.2 cm in size). At two months pregnancy, skeletal structures like skull, thorax and long bones were clear. Biparietal diameter of the skull and length of long bones could be used as an estimate of gestational age. The accuracy of detection of fetal number using real-time B-mode ultrasonography was 91.7% on day 60 of gestation. In conclusion, progesterone assay at day 21 post-mating (cut-off value, 1 ng/ml) can be used for pregnancy diagnosis in goats. However, B-mode transrectal ultrasonography was more efficient due to detection of embryo and confirmation of its viability by heartbeats. In addition, fetal number and gestational age could be determined only by ultrasonography.     

Screening study for potential lead compounds for natural product-based fungicides: I. Synthesis and in vitro evaluation of coumarins against Botrytis cinerea

An efficient, one-pot synthesis of angular and linear dihydropyranocoumarins, along with C-6 and C-8 prenylated coumarins is reported. These compounds, together with single- and furanocoumarins, were tested for their potential antifungal activity against the phytopathogen Botrytis cinerea Pers ex Fr. The results show that furanocoumarins may be able to control the fungus B cinerea.     

High infection rates of the tick Hyalomma anatolicum anatolicum with Trypanosoma theileri

A crossbred calf (3 months old) obtained from a farm where regular control of ticks was practised and found to be free of blood parasites was inoculated with 20 ml pooled blood collected from four field cattle which had very low Trypanosoma theileri parasitaemias (one parasite per 70 microl blood as determined by the haematocrit centrifugation technique). Trypanosoma theileri was present in the blood 6 days after injection and a peak parasitaemia of 42 parasites per 70 microl blood was recorded by day 12. Hyalomma anatolicum anatolicum nymphs were applied on the ears of the calf on day 8 and they dropped engorged by days 13 and 14. The resulting adult ticks were examined for the presence of T. theileri by severing a leg and making a smear of the clear haemolymph which exuded from the wound. The smear was fixed in methanol and stained with Giemsa stain. The infection rate with T. theileri in the ticks was 43.3% (26 out of 60). The intensity of infection was very high and various developmental stages of the flagellates were observed (epimastigotes, sphaeromastigotes, trypomastigotes and other intermediate stages). The haemolymph from 12 ticks was also collected in tissue culture medium and the trypanosomes survived for 25 weeks before eventually dying. The results demonstrated unequivocally the high vectorial capacity of the tick H. a. anatolicum for T. theileri.