The bleaching induced by the phenylpyridazinone herbicide Metflurazon in Chlorella is a metabolic and reversible process

The treatment of synchronized cells of the green alga Chlorella fusca under photoautotrophic conditions with metflurazon (SAN H 6706; 4-chloro-5-dimethylamino-2-(α,α,α-trifluoro-m-tolyl-3(2H)-pyridazinone)) induces a bleaching process and results in white-appearing cells. This process of bleaching was followed by quantitative analysis of cell growth and cell division, photosynthetic oxygen evolution, respiratory oxygen consumption, and of pigment pattern at 0, 6, 12, 18, 24, 48, and 72 hr after incubation with different concentrations of metflurazon. Increasing concentrations of metflurazon gradually affected cell growth of Chlorella measured as increase in cell diameter. Cell division was inhibited completely with 1, 10, and 100 μM metflurazon. Photosynthetic oxygen evolution and respiratory oxygen consumption were not inhibited by 1 μM metflurazon during the first 6 hr; after this time a gradually increased inhibition was observed. Both parameters were inhibited by 100 μM metflurazon immediately after herbicide addition. A detailed analysis of the pigment content during the bleaching process revealed that: (a) The bleaching of Chlorella cells by metflurazon is not a simple photochemical process like the photobleaching of boiled cells, but is directed by the active metabolism of Chlorella itself. (b) The bleaching process is characterized by two phases: an accumulation of pigments followed by their degradation. The accumulation phase extends to 6 hr after herbicide addition. (c) During the accumulation phase, chlorophyll is accumulated to 380 and 106% in cells treated with 1 and 100 μM metflurazon, respectively, compared to the initial pigment content. The breakdown of chlorophyll, however, during the degradation phase is 5 times faster in the 1 μM treatment than in the 100 μM treatment. This difference resulted in the faster appearance of white cells with the low metflurazon concentration. (d) During the accumulation phase in the 1 μM treatment, the biosynthesis of chlorophylls, xanthophylls, and carotenes is inhibited by 56, 74, and 78%, respectively, when compared to a nontreated control. When related to the initial amounts, chlorophylls, xanthophylls, and carotenes are accumulated to 380, 230, and 153%, respectively. However, the synthesis of violaxanthin is specifically inhibited, followed by α-carotene. During the degradation phase, violaxanthin and α-carotene again, are the most rapidly disappearing pigments. Continuous culturing of white Chlorella cells resulted in a regeneration to green cells after 96, 240, 384 hr for 1, 10, and 100 μM metflurazone, respectively. The bleaching of Chlorella by metflurazon is evidently dependent on a functioning metabolism and is itself a regulated disassembly of the photosynthetic apparatus, which is reversible and not lethal.     

Effect of yohimbine hydrochloride on serum prolactin concentration in the rat: possible antagonist for fescue toxicosis

Yohimbine hydrochloride is an indole alkaloid which blocks alpha 2-adrenergic and dopamine receptors and stimulates serotonergic receptors. Yohimbine was selected for testing as a possible antagonist in fescue toxicosis. Reduced body weight gains in cattle with chronic fescue toxicosis may be due to ergot alkaloids produced by fungi which infect the fescue grass. Ergot alkaloids stimulate dopamine receptors, antagonize serotonin, and lower serum prolactin concentrations. It was hypothesized that yohimbine may reverse or counteract the effects of the toxic fescue. Investigation was made of the treatment effects of multiple doses of yohimbine given in rats by intraperitoneal and oral routes. Given intraperitoneally once a day for 8 days, yohimbine hydrochloride increased serum prolactin concentrations. When given orally in feed for 7 days, the drug decreased the serum prolactin concentration. The effects of yohimbine on prolactin concentrations were dependent on the dosages and routes of administration. The inability of yohimbine, when given orally, to increase serum prolactin levels decreased its potential usefulness for prolonged treatment of fescue toxicosis.     

Das Blutgefäßsystem des Enddarms vom Schwein (Sus scrofa f. domestica)

The circulatory system of the large intestine of 27 pigs was examined by means of corrosion anatomy (vascular casts), histology and electron microscopy. The results were as follows: The Aa. et Vv. breves et longae leave the mesenteric vessels and reach the wall of the intestine at the mesenteric margin. The short vessels enter the deeper layers of the wall, whereas the Aa. et Vv. longae, by taking a variable subserous course, reach the submucosa af ter penetrating the muscular layers. The tela submucosa contains an arterial and a venous vascular plexus. Where the submucosa is larger, there is a three-dimensional vascular network, a deep and superficial vascular plexus that are closely interconnected. The deep plexus is applied to the inner circular muscles, whereas the superficial plexus is adjacent to the muscularis mucosae. The deep arterial plexus receives its af flux from the Aa. breves et longae and provides part of the circular muscle layers with recurrent muscle branches. The vascularization of the mucosa is derived from the (superficial) submucosal plexus. The arteries that ascend the tunica mucosa ramify, in the form of a brush, into some arterioles. In the basal part of the mucosa, they turn into a periglandular capillary system, i.e. a network around each Lieberkühn crypt. Close to the lumen, a polygonal subepithelial capillary system is formed. Below the epithelium of the mucosal surf ace, the capillaries turn into postcapillary venules. These are running vertically through the submucosa, with few infiowing side branches, and finally enter the submucosal plexus. An intermuscular plexus is formed by anastomoses between the circular and the longitudinal muscular layers from the branches of the subserous-submucosal connections. This intermuscular plexus provides the capillaries for the tunica muscularis. The subepithelial capillaries are, above all, furnished with a so-called fenestrated endothelium, whereas the capillaries of the pericryptal mucosa mainly show a continuous endothelium. The latter contains multiple vesicles that can fuse to form transcytoplasmic channels. In the wall of the large intestine of the pig, there are no sure indications as to the existence of either arterio-venous anastomoses or haemodynamic regulatory structures.     

The occurrence of hypotaurine in ovarian follicle walls in sheep and in the Fallopian tube of sheep and other animals

Inhalt: In den Ovarien von Schafen kommen während des Brunstzyklus in den Folli-kelwandungen Hypotaurin und Inositol in Konzentrationen von 0–7 mg % bzw. 40 mg % vor. Hypotaurin wurde auβerdem in den Eileitern von Schaf, Pferd, Rind, Schwein und Kaninchen gefunden; in zwei Fällen gelang auch der Nachweis von Hypotaurin in der Fimbrienplatte der Hündin. Es wird die Hypothese aufgestellt, daβ bei mit Progesteron bebandelten Tieren das Fehlen von Hypotaurin möglicherweise die Entwicklung und den Transport der Eier ungünstig beeinfluβt.     

On the mode of action of the fungicide etridiazole

Etridiazole (5-ethoxy-3(trichloromethyl)-1,2,4-thiadiazole) is a fungicide primarily effective against fungi of the Oomycete group. After addition of the compound to the medium, growth of Mucor mucedo was impaired almost immediately. Oxygen uptake of the mycelia decreased only slightly at growth-inhibiting concentrations. Respiration of isolated mitochondria of Mucor was inhibited about 50% by high concentrations of the fungicide, while the respiratory control quotient remained constant. In contrast, rat liver mitochondria were not very sensitive to etridiazole. Etridiazole stimulates the hydrolysis of membrane-bound phospholipids to free fatty acids and lysophosphatides in isolated mitochondria of Mucor. Procaine, a well-known inhibitor of phospholipases, acts as an antidote for etridiazole in growth tests as well as in the hydrolysis of phosphatidylcholine by isolated mitochondria. Calcium ions in millimolar concentrations act like procaine. Therefore, it was assumed that the fungistatic effect of etridiazole was mainly caused by an activation of phospholipases in the mitochondrial membranes. Moreover, under the influence of etridiazole, a lipid peroxidation of membranes is observed. Tocopherol acts as an antidote. This could be the primary toxic effect in the mechanism of action of this fungicide. The enzymes involved are not yet identified.     

Cross-sectional survey in pig breeding farms in Hesse, Germany: seroprevalence and risk factors of infections with Toxoplasma gondii, Sarcocystis spp. and Neospora caninum in sows

A cross-sectional survey was performed to estimate the prevalences of antibodies to Toxoplasma gondii (ELISA, IFAT), Sarcocystis spp. (ELISA, using S. miescheriana as antigen) and Neospora caninum (ELISA, immunoblotting) in sows from breeding farms in southern Hesse, Germany. A total of 2041 plasma samples of sows from 94 randomly selected farms was examined. Data on farm profiles, husbandry management and sows were collected by a questionnaire and exploratively analysed. For T. gondii the ELISA results agreed well with the results obtained by IFAT (kappa=0.71). Antibodies to T. gondii were detected by ELISA in 19% of the sows. Sixty-nine percent of the farms had at least one seropositive sow, and a within-farm seroprevalence of >or=50% was observed in 14% of all farms. The prevalence of anti-T. gondii antibodies was positively correlated with the age of sows. The within-herd seroprevalence was significantly higher in farms with reproductive disorders than in those without such problems. On the farm level, the farm type 'piglet production' (versus 'pedigree breeding' or 'farrow-to-finish') was the only risk factor associated with the presence of T. gondii-seropositive sows. Antibodies to Sarcocystis spp. were found in 29% of the sows. Seventy-two percent of the farms harboured at least one seropositive sow, and a within-farm seroprevalence of >or=50% was detected in 23% of all farms. The seroprevalence increased significantly with the age of sows. On the farm level, only the farm type 'piglet production' (versus 'pedigree breeding') and the replacement of sows by purchasing (versus raising on the own farm) were identified as risk factors for seropositivity. Antibodies to N. caninum were detected in one sow using both the screening ELISA and the confirmatory immunoblotting technique. This may indicate the first natural N. caninum infection in pigs.     

Effect of raw humus under two adult Scots pine stands on ectomycorrhization, nutritional status, nitrogen uptake, phosphorus uptake and growth of Pinus sylvestris seedlings

Ectomycorrhiza (EM) formation improves tree growth and nutrient acquisition, particularly that of nitrogen (N). Few studies have coupled the effects of naturally occurring EM morphotypes to the nutrition of host trees. To investigate this, pine seedlings were grown on raw humus substrates collected at two forest sites, R2 and R3. Ectomycorrhiza morphotypes were identified, and their respective N uptake rates from organic (2-(13)C, (15)N-glycine) and inorganic ((15)NH(4)Cl, Na(15)NO(3), (15)NH(4)NO(3), NH(4)(15)NO(3)) sources as well as their phosphate uptake rates were determined. Subsequently, the growth and nutritional status of the seedlings were analyzed. Two dominant EM morphotypes displayed significantly different mycorrhization rates in the two substrates. Rhizopogon luteolus Fr. (RL) was dominant in R2 and Suillus bovinus (Pers.) Kuntze (SB) was dominant in R3. (15)N uptake of RL EM was at all times higher than that of SB EM. Phosphate uptake rates by the EM morphotypes did not differ significantly. The number of RL EM correlated negatively and the number of SB EM correlated positively with pine growth rate. Increased arginine concentrations and critical P/N ratios in needles indicated nutrient imbalances of pine seedlings from humus R2, predominantly mycorrhizal with RL. We conclude that different N supply in raw humus under Scots pine stands can induce shifts in the EM frequency of pine seedlings, and this may lead to EM formation by fungal strains with different ability to support tree growth.     

Use of 25-hydroxyvitamin D3 and dietary calcium to improve tenderness of beef from the round of beef cows

The objective of this trial was to determine how 25-hydroxyvitamin D(3) (25-OH D(3)) supplementation, altering supplemental dietary calcium, or their combination influence postmortem biochemical and tenderness changes in muscles from the round of mature cows. Twenty-seven Angus cows (3 to 7 yr old) were allotted randomly to 9 pens with 3 cows per pen. Treatments were arranged in a 3 x 3 factorial design with 3 dosages of 25-OH D(3) (0, 250, or 500 mg of 25-OH D(3) administered as a 1-time oral bolus 7 d before slaughter) and 3 percentages of supplemental limestone (0.5, 0.75, and 1.0%) replenished in the diet for 3 d before slaughter and after a 2-wk limestone withdrawal. Plasma samples were obtained during the feeding period. Upon slaughter, adductor, gracilus, pectineus, sartorius, semimembranosus, vastus intermedius, and vastus lateralis muscles were obtained and aged for 1, 3, or 7 d. Calcium concentrations were increased in plasma when 250 or 500 mg of 25-OH D(3) were administered (P 相似文献