苏州地区双三制下土壤养分状况和水稻对肥料的反应

苏州地区是我国著名的水稻高产地区之一,向以稻麦两熟为主.近些年来,稻-稻-麦三熟制的面积有了很大的发展,不少社队的复种指数达到了240%左右.探讨在这种高强度栽培制度下,土壤的养分供应状况及肥料效果问题,是有一定意义的.本文是我们在1974-1977年间对此问题进行研究中所获资料的总结.     

Chemical composition and mosquito larvicidal activity of essential oils from leaves of different Cinnamomum osmophloeum provenances

Chemical compositions of leaf essential oils from eight provenances of indigenous cinnamon (Cinnamomum osmophloeum Kaneh.) were compared. According to GC-MS and cluster analyses, the leaf essential oils of the eight provenances and their relative contents were classified into five chemotypes-cinnamaldehyde type, linalool type, camphor type, cinnamaldehyde/cinnamyl acetate type, and mixed type. The larvicidal activities of leaf essential oils and their constituents from the five chemotypes of indigenous cinnamon trees were evaluated by mosquito larvicidal assay. Results of larvicidal tests demonstrated that the leaf essential oils of cinnamaldehyde type and cinnamaldehyde/cinnamyl acetate type had an excellent inhibitory effect against the fourth-instar larvae of Aedes aegypti. The LC(50) values for cinnamaldehyde type and cinnamaldehyde/cinnamyl acetate type against A. aegypti larvae in 24 h were 36 ppm (LC(90) = 79 ppm) and 44 ppm (LC(90) = 85 ppm), respectively. Results of the 24-h mosquito larvicidal assays also showed that the effective constituents in leaf essential oils were cinnamaldehyde, eugenol, anethole, and cinnamyl acetate and that the LC(50) values of these constituents against A. aegypti larvae were <50 ppm. Cinnamaldehyde had the best mosquito larvicidal activity, with an LC(50) of 29 ppm (LC(90) = 48 ppm) against A. aegypti. Comparisons of mosquito larvicidal activity of cinnamaldehyde congeners revealed that cinnamaldehyde exhibited the strongest mosquito larvicidal activity.     

Metabolic transformation of sesamol and ex vivo effect on 2,2'-azo-bis(2-amidinopropane)dihydrochloride-induced hemolysis

Sesamol (3,4-methylenedioxyphenol), a phenolic constituent in roasted sesame, was reported to exhibit various beneficial activities. To understand the metabolic transformation of sesamol in vivo, rats were given sesamol intravenously and orally. The blood samples were withdrawn via cardiopuncture at specific time points. The serum samples were assayed by high-performance liquid chromatography method before and after hydrolysis with sulfatase and beta-glucuronidase. Our results indicated that following either intravenous or oral administration, sesamol declined rapidly and the sulfate/glucuronide of sesamol emerged instantaneously. The peak serum concentration and systemic exposure of sesamol were markedly lower than sesamol sulfate/glucuronide. Ex vivo evaluation revealed that sesamol exerted profoundly higher capability against 2,2'-azo-bis(2-amidinopropane)dihydrochloride-induced hemolysis than the serum metabolites. In conclusion, sulfate and glucuronide of sesamol were the principle metabolites of sesamol in the bloodstream of rats. The conjugated metabolites of sesamol warrant more bioactivity investigations to understand the in vivo effect of sesamol.     

Femtomolar sensitivity of a NO sensor from Clostridium botulinum

Nitric oxide (NO) is extremely toxic to Clostridium botulinum, but its molecular targets are unknown. Here, we identify a heme protein sensor (SONO) that displays femtomolar affinity for NO. The crystal structure of the SONO heme domain reveals a previously undescribed fold and a strategically placed tyrosine residue that modulates heme-nitrosyl coordination. Furthermore, the domain architecture of a SONO ortholog cloned from Chlamydomonas reinhardtii indicates that NO signaling through cyclic guanosine monophosphate arose before the origin of multicellular eukaryotes. Our findings have broad implications for understanding bacterial responses to NO, as well as for the activation of mammalian NO-sensitive guanylyl cyclase.     

Enhanced Anti-Obesity Activities of Red Mold Dioscorea When Fermented Using Deep Ocean Water as the Culture Water

Deep ocean water (DOW) has, in previous studies, been found to be a novel anti-obesity drink and useful in raising Monascus-produced monascin and ankaflavin levels. This may resolve the limited anti-obesity ability of red mold dioscorea (RMD) known as the Monascus purpureus-fermented Disocorea batatas. This study aims to compare the anti-obesity effect of DOW-cultured RMD (DOW-RMD) and ultra-pure water-cultured RMD (UPW-RMD) in rats fed on a high fat diet. Moreover, the effect of ions composition of DOW and DOW-influenced functional metabolites change of RMD on the differentiation and lipogenesis regulation were investigated using 3T3-L1 pre-adipocytes. In the animal test, compared to UPW-RMD, DOW-RMD possessed better ability to inhibit increases in weight gain, and better feed efficiency, body-fat pad and cross-sectional area of adipocytes. In the cell test, the anti-obesity abilities of DOW-RMD in inhibiting PPARγ and C/EBPα expression in differentiation and lipoprotein lipase activity in lipogenesis were contributed to by the DOW-increased monascin and ankaflavin levels and the ions of DOW, respectively.     

A field and laboratory study of the responses of cytoprotection and osmoregulation to salinity stress in mosquitofish (<Emphasis Type="Italic">Gambusia affinis</Emphasis>)

The mosquitofish (Gambusia affinis) naturally inhabits freshwater (FW; 1–3‰) and seawater (SW; 28–33‰) ponds in constructed wetland. To explore the physiological status and molecular mechanisms for salinity adaptation of the mosquitofish, cytoprotective responses and osmoregulation were examined. In the field study, activation of protein quality control (PQC) mechanism through upregulation of the abundance of heat shock protein (HSP) 90 and 70 and ubiquitin-conjugated proteins was found in the mosquitofish gills from SW pond compared to the individuals of FW pond. The levels of aggregated proteins in mosquitofish gills had no significant difference between FW and SW ponds. Furthermore, the osmoregulatory responses revealed that the body fluid osmolality and muscle water contents of the mosquitofish from two ponds were maintained within a physiological range while branchial Na⁺/K⁺-ATPase (NKA) expression was higher in the individuals from SW than FW ponds. Subsequently, to further clarify whether the cellular stress responses and osmoregulation were mainly induced by hypertonicity, a laboratory salinity acclimation experiment was conducted. The results from the laboratory experiment were similar to the field study. Branchial PQC as well as NKA responses were induced by SW acclimation compared to FW-acclimated individuals. Taken together, induction of gill PQC and NKA responses implied that SW represents an osmotic stress for mosquitofish. Activation of PQC was suggested to provide an osmoprotection to prevent the accumulation of aggregated proteins. Moreover, an increase in branchial NKA responses for osmoregulatory adjustment was required for the physiological homeostasis of body fluid osmolality and muscle water content.     

Calcium balance in embryos and larvae of the freshwater-adapted teleost,Oreochromis mossambicus

Changes in Ca²⁺ content and flux, and the development of skin chloride cells in embryos and larvae of tilapia, Oreochromis mossambicus, were studied. Tilapia embryos hatched within 96h at an ambient temperature of 26–28°C. Total body Ca²⁺ content was maintained at a constant level, about 4–8 nmol per individual, during embryonic development. However, a rapid increase in body Ca²⁺ level was observed after hatching, 12.8 to 575.3 nmol per individual from day 1 to day 10 after hatching. A significant influx and efflux of Ca²⁺ occurred during development, with the average influx rate for Ca²⁺ increasing from 5.9 pmol mg⁻¹ h⁻¹ at 48h postfertilization to 47.8 pmol mg⁻¹ h⁻¹ at 1 day posthatching. The skin was proposed as the main site for Ca²⁺ influx before the development of gills, and the increased Ca²⁺ influx may be ascribed to gradual differentiation of skin surface and chloride cells during embryonic development. Ca²⁺ efflux was 16–56 pmol mg⁻¹ h⁻¹ in 1-day-old larvae. The resulting net influx of Ca²⁺, 10–12 pmol mg⁻¹ h⁻¹, accounted for the increased Ca²⁺ content after hatching. When comparing the measured and estimated ratios of efflux and influx, active transport was suggested to be involved in the uptake of Ca²⁺. Chloride cells, which may be responsible for the active uptake of Ca²⁺, started to differentiate in the skin of embryos 48h after fertilization, and the density of chloride cells increased following the development. A possibility of active transport for Ca²⁺ in early developmental stages of tilapia is suggested.     

Nocardia seriolae infection in the three striped tigerfish, Terapon jarbua (Forsskål)

An epizootic in pond cultured three striped tigerfish, Terapon jarbua , in Taiwan was caused by Nocardia seriolae . Diseased fish first showed clinical signs and mortalities in February and March 2003. The cumulative mortality within 2 months was 2.4% (1200 of 50 000) and affected fish were 7 months old with total lengths from 18 to 25 cm. Most affected fish were pale and lethargic with haemorrhages and ulcers on the skin. The most significant gross pathological changes were varying degrees of ascites and enlargement of the spleen, kidney and liver. Obvious white nodules, varying in size, were found in these organs. Bacteria were either coccal or filamentous in appearance, with bead-like forms. Isolates from diseased fish were characterized using the API ZYM (Analytical profile index; Bio Mérieux, France) systems and conventional tests and identified as Nocardia sp. The isolate was designated NS127 and was confirmed as N. seriolae by a polymerase chain reaction assay that gave the expected specific 432 bp amplicon. In addition, its 16S rDNA sequence gave 100% sequence identity with N. seriolae . A partial sequence of the 16S rRNA gene, heat shock protein gene and RNA polymerase gene (rpo B) of NS127 and the type strain of N. seriolae BCRC 13745 formed a monophyletic clade with a high sequence similarity and bootstrap value of 99.9%. White nodules induced in experimental fish were similar to naturally infected cases and N. seriolae was re-isolated on brain heart infusion agar. This is the first report of N. seriolae -infection in three striped tigerfish in aquaculture.