Inhibitory effect of penicillin on caecal urease activity in chickens fed on a low protein diet plus urea

1. The effects of dietary penicillin on the urease activities of small intestine, large intestine, caecum and their contents, liver and kidney in chickens fed a diet containing 5 g/kg protein plus urea were examined.

2. About 0.88 of the total urease activity determined was observed in intestinal contents, of which 0.95 of the activity was accounted for by caecal contents, 0.05 by colo‐rectal contents and none by small intestinal contents. Intestinal tissues (caecum included), liver and kidney accounted for 0.03, 0.06 and 0.02, respectively, of the total urease activity.

3. Dietary penicillin decreased urease activity to 0.17 in caecal contents and to 0.05 in colo‐rectal contents of the corresponding control values (P< 0.01). The urease activity of caecal tissue was lowered by penicillin to half that of control activity (P < 0.05) but none of the activities of other tissues were affected.

4. It is concluded that, even when the urease activity is stimulated by dietary urea, 20 mg/kg dietary penicillin can strikingly lower it in the caecum, where most of the urease activity in the chicken body is to be found.     

Variable response of growth and arbuscular mycorrhizal colonization of maize plants to preceding crops in various types of soils

The effects of the preceding crops, sunflower (mycorrhizal host) and mustard (nonhost), on arbuscular mycorrhizal (AM) colonization and growth of succeeding maize were examined in 17 soils in an attempt to clarify the influence of soil characteristics on the effects of preceding crops. Shoot weight and P uptake of maize planted after sunflower were much higher than those after mustard in 14 soils, although the preceding crop had little effect on soil-P availability. AM colonization of maize after sunflower was much higher than that after mustard. The effect of the preceding crop was eliminated by soil sterilization. These results suggested that the differences in maize growth were caused by differences in the AM colonization. Correlation analysis of the effect of the preceding crop and soil properties showed that the difference in the effects on maize growth could not be explained by soil chemical properties, but only by the AM colonization of the preceding sunflower crop. In one of the 17 soils, however, the effect was not evident despite the higher AM colonization of sunflower. This soil was sterilized, and the effect of inoculation by AM fungi (AMF) on maize was examined. However, it was found that the inoculation increased AM colonization but did not improve maize growth at any P level, suggesting that the effect of AMF was unusually inhibited in this soil by unknown soil physicochemical properties. In most soils, however, the preceding mycorrhizal host crop, sunflower, improved the growth and AM colonization of maize depending on the AM colonization of sunflower.     

Morphological modifications among oribatid mites (Acari: Oribatida) in relation to habitat differentiation in mangrove forests

We examined morphological modifications among oribatid species in five microhabitats in mangrove forests in the Ryukyu Islands of Japan. A total of 89 oribatid species were recorded from canopy (leaves and branches), bark of flooded trunks (trunks of 0–50 cm high and knee roots), bark of other trunks higher than 50 cm, and littoral algae in mangrove forests, and the forest-floor soil in an adjacent bank forest. There were no significant differences in the body length, body width, and notogastral length among oribatid species from the five microhabitats. The mean sensillus length of the oribatid species from the forest-floor soil was about twice as long as that from the other microhabitats. Claw morphology was characterized by two attributes: number (monodactyly and tridactyly) and length. In the canopy and trunks, the proportion of tridactyl species was higher than that of monodactyl species. On the other hand, the proportion of tridactyl species in the forest-floor soil accounted for only about 20%, and that in the flooded trunks and littoral algae approximated to zero. The mean claw length was larger in the oribatid species from the flooded trunks and littoral algae than in both monodactyl and tridactyl species from every other microhabitat. Trydactyl species with short claws in the arboreal environments might have been selected by a compromise between grip and mobility for unpredictable environmental changes such as wind and rain. The dominance of monodactyl species with a longer claw in the littoral environments implies a consequence of selection for regular tidal flooding, which requires oribatids to grip tighter on the substrate. The modifications in claw morphology of oribatid mites in mangrove forest might be interpreted as adaptations to a difference in the predictability of the environmental conditions of microhabitats.     

Occurrence of intraportally-infused urea-15N in the urine of domestic fowl.

1. Measurements were made in situ to determine the occurrence of intraportally infused urea-15N in ureteral urine of the fowl. 2. Of the total amount of infused urea-15N, 15% was excreted intact into the urine (90% of urinary total 15N) whereas 9% remained unchanged in the blood (78% of blood non-protein-15N). 3. The proportions of non-protein-15N in the blood, liver and kidney were 12, 3 and 1%, respectively of the infused 15N. Protein-15N was 3% of that infused in blood and much less in liver and kidney. 4. About 1% of the infused 15N was observed in the urinary uric acid, and 3% of the infused 15N in non-protein N, other than urea, ammonia and glutamine amide N, of blood and liver. 5. No appreciable amounts of 15N were present in ammonia and glutamine amide N of blood, liver or kidney and in uric acid of liver or kidney. 6. The caecal contents contained about 1% of the infused 15N with 15% of this as ammonia-15N. 7. It is concluded that intraportal urea is mostly excreted unchanged into ureteral urine of the fowl.     

尾叶桉壮苗培育技术

对尾叶桉育苗的全套技术进行总结。成功培育苗木的关键是：合理的营养土配方及细致的水肥管理,同时掌握好合理的播种密度及不同天气条件下的管理措施     

Combustion gas toxicity,hygroscopicity, and adhesive strength of plywood treated with flame retardants

Summary The results of tests of combustion toxicity, hygroscopicity, and adhesive strength for fire retardant-treated plywood are described. The plywood was prepared from veneers treated with diammonium phosphate and ammonium bromide, and from glue mixed with poly (ammonium phosphate). Furthermore, the plywood boards were coated with boric acid. High ammonium phosphate and low or 0 ammonium bromide contents with the boric acid-coatings gave the greatest improvement in the combustion toxicity. Influence of almost all the treatments on the hygroscopicity was not significant. In all treatments the dry adhesive strength and the cyclic boil adhesive strength were slightly and considerably reduced, respectively.     

Ligation of caeca improves nitrogen utilisation and decreases urinary uric acid excretion in chickens fed on a low protein diet plus urea

1. The effect of the ligation of the caeca on nitrogen utilisation and nitrogen excretion was examined in conventional chickens fed a diet containing 50 g protein/kg plus urea.

2. Ligation of the caeca significantly improved nitrogen balance and utilisation by up to more than 2 times as much as those of controls (P< 0.05).

3. The treatment significantly decreased uric acid excretion by 77 mg nitrogen/day (P< 0.01) and also total nitrogen excretion (P<0.05): the former decrease almost explained the latter.

4. No effect of the ligation of caeca on urea and ammonia excretion was observed.

5. It is concluded that nitrogen metabolism in chickens is affected by possible changes in caecal fermentation by preventing entry into the caeca of substances from urine and digesta.     

Adverse effects of low concentrations of dietary RNA addition on the growth,food intake and kidney weight of young chickens

1. The effects of 0, 10 and 50 g/kg of RNA in diets on the growth and food intake of chicks from 6 to 21 d of age were examined. Their effects on renal tissue were examined by light microscopy at the end of experiment.

2. Total food intake and growth decreased with the increase in dietary RNA content and kidney weight was significandy increased by 50 g/kg RNA addition. A significant increase in liver weight was also observed in chickens fed on the diet‐supplemented with 10 g RNA/kg.

3. The enlarged kidney caused by dietary RNA contained many crystals which were composed mainly of calcium salts but did not contain purines.

4. It is concluded that relatively low dietary RNA concentrations decrease food intake and growth and cause enlarged kidneys which contains many crystals composed mainly of calcium salts.     

Superficial keratectomy and topical mitomycin C as therapy for a corneal squamous cell carcinoma in a dog

A 10-year-old female West Highland white terrier was presented with refractory hyperplastic keratitis of the left cornea of one month's duration. At this time, a vascularised and rough lesion 5 mm in diameter was observed on the left cornea. No other abnormality was recognised on the affected eye. The corneal neoplasm was surgically removed and histologically diagnosed as a squamous cell carcinoma. For two months after the surgery, 0.04 percent mitomycin C (MMC) eye drops were applied as adjuvant chemotherapy. Primary corneal squamous cell carcinoma with no history of keratoconjunctivitis sicca is rare in dogs. In the present report, surgical removal of the neoplasm was combined with the topical administration of the anticancer drug mitomycin C and a good prognosis was obtained. The result indicates that the combination treatment used in this case may be an appropriate therapeutic choice for corneal squamous cell carcinoma in dogs.     

Effects of caecal ligation and colostomy on water intake and excretion in chickens

1. The effect of caecal ligation and colostomy on water intake and excretion were examined in chickens fed a low-protein diet or a low-protein diet supplemented with urea. 2. When fed a low-protein diet, the water intake and the ratio of water intake to food intake were increased by colostomy (P < 0.05) but not changed further by caecal ligation of colostomised chickens. 3. When fed a low-protein diet supplemented with urea, the amount of water intake and the ratio of water intake to food intake were not changed by either treatment. 4. Total water excretion was much higher in the colostomised plus caeca-ligated chickens than in other 3 groups fed both types of diet (P < 0.05). 5. The amount of faecal water excretion was increased by cecal ligation in colostomised chickens fed either diet (P < 0.01). 6. No effect of any treatment on water balance was observed in chickens fed either diet. 7. It is concluded that the lower intestine plays a useful role in the water economy of chickens fed a low-protein diet or a low-protein diet supplemented with urea.