树皮草炭混配基质对生菜生长的影响

采用草炭与熟化树皮混配作基质栽培生菜 ,结果表明 :适当增加树皮比例 ,可促进生菜生长发育 ,树皮∶草炭为 7∶3时 ,单位叶面积干鲜质量、叶绿素含量、根数与根质量、产量及净菜率均最高。而树皮含量高于或低于 70 %时 ,生长发育会不同程度延缓。树皮含量越高 ,生菜单株耗水量越低 ,即节水效果越好 ,同时 ,生菜植株中N、K含量随之提高 ,但P、Ca、Mg各处理间无显著差异。     

Combined administration of ghrelin and GHRH synergistically stimulates GH release in Holstein preweaning calves

Ghrelin is a gut peptide which participates in growth regulation through its somatotropic, lipogenic and orexigenic effects. Synergism of ghrelin and growth hormone-releasing hormone (GHRH) on growth hormone (GH) secretion has been reported in humans and rats, but not in domestic animals in vivo. In this study, effects of a combination of ghrelin and GHRH on plasma GH and other metabolic parameters, and changes in plasma active and total ghrelin levels were studied in Holstein bull calves before and after weaning. Six calves were intravenously injected with vehicle (0.1% BSA-saline), ghrelin (1 microg/kg BW), GHRH (0.25 microg/kg BW) or a combination of ghrelin plus GHRH at the age of 5 weeks and 10 weeks (weaning at 6 weeks of age). Ghrelin stimulated GH release with similar potency as GHRH and their combined administration synergistically stimulated GH release in preweaning calves. After weaning, GH responses to ghrelin and GHRH became greater compared with the values of preweaning calves, but a synergistic effect of ghrelin and GHRH was not observed. The GH areas under the concentration curves for 2h post-injection were greater in weaned than in preweaning calves (P<0.05) if ghrelin or GHRH were injected alone, but were similar if ghrelin and GHRH were injected together. Basal plasma active and total ghrelin levels did not change around weaning, but transiently increased after ghrelin injection. Basal plasma insulin, glucose and non-esterified fatty acid levels were reduced after weaning, but no changes by treatments were observed. In conclusion, ghrelin and GHRH synergistically stimulated GH release in preweaning calves, but this effect was lost after weaning.     

Granulocyte colony-stimulating factor has no adverse effects on atherosclerotic lesions in high cholesterol-fed miniature Swine

Granulocyte colony-stimulating factor (G-CSF) is widely used to mobilize peripheral blood stem cells, and expected to restore cardiac function for patients with coronary artery diseases as a consequence of progression of atherosclerosis. Safety issues related to the administration of G-CSF to these patients, however, are still under study. The animal model for atherosclerosis was produced by feeding miniature swine a high-cholesterol diet for 3 months. G-CSF (5 or 10 microg/kg/day) was given to the animal model by daily subcutaneous injections for 10 days and 20 main arteries were evaluated pathologically. In addition, the general toxicological effects were studied on clinical signs, body weight, hematology, blood chemistry and pathology. In the G-CSF-treated groups, a variety of changes related to the major pharmacological activity of G-CSF including an increase in white blood cell (WBC) counts were observed. In many arteries, atherosclerotic lesions similar to Type I-V of the proposed classification by the American Heart Association were observed. No effects of the G-CSF treatment were seen on the histopathological findings, incidence, severity or distribution of atherosclerotic lesions. In addition, no infiltration of neutrophils to the lesions was observed. These findings suggest that the administration of G-CSF causes neither exacerbation or modification of atherosclerotic lesions nor adverse changes despite that a sufficient increase in WBC counts could be achieved in the peripheral blood.     

A 12-month feeding study of reproduction/development in rats fed meat/milk powder supplemented diets derived from the progeny of cloned cattle produced by somatic cell nuclear transfer

The present 12-month feeding study was carried out with rat groups fed a diet supplemented with meat or milk (meat/milk) derived from the progeny of clones produced by somatic cell nuclear transfer (SCNT) technology. It was conducted to obtain data concerning the chronic toxicities of these edible products during the process of development and reproduction in rats fed such products. The rats were subjected to clinical observations for general health condition and examinations such as sensory/reflex function, grip strength, motor activity, body weight, food consumption, ophthalmology and urinalysis. Moreover, sexually matured rats fed the test diets were mated and examined for items such as the reproductive performances of the dams and health of their pups. After the feeding period, factors related to rat health status, based on the findings for hematology, blood biochemistry, necropsy, organ weight and histology, were examined. There were no biologically significant differences in these factors between the rat groups fed meat/milk powder supplemented diets derived from the progeny and those fed meat/milk powder supplemented diets derived from conventionally bred cattle. Therefore, the present chronic toxicity study suggests that meat and milk derived from the progeny of SCNT cattle might be equivalent to those derived from conventionally bred cattle in use as dietary supplements for rats.     

Central administration of neuropeptide B, but not prolactin-releasing peptide, stimulates cortisol secretion in sheep

Two neuropeptides, neuropeptide B (NPB) and prolactin-releasing peptide (PrRP), have been suggested to play important roles in control of the hypothalamic-pituitary-adrenal (HPA) axis in rodents. The aim of the present study was to clarify the central actions of NPB or PrRP in sheep. Ovariectomized ewes were surgically implanted with a cannula directed to the lateral ventricle. They received intracerebroventricular (icv) administration of 400 mul of artificial cerebrospinal fluid, NPB (0.05, 0.5 or 5 nmol), PrRP (0.5, 5 or 50 nmol) or corticotropin-releasing hormone (CRH, 0.5 or 5 nmol) through the cannula, and blood samples were taken 30 and 0 min prior to and 15, 30, 60 and 90 min after the injection. Cortisol concentrations in plasma were determined by enzyme immunoassay. Administration of 0.5 nmol NPB resulted in a significant increase in the cortisol concentration compared with the vehicle control, whereas the cortisol concentration after lower or higher doses of NPB did not differ from the control value. Thus, an icv injection of NPB produced a bell-shaped dose-response of cortisol concentration. Administration of PrRP had no significant effect on the cortisol concentrations at any dose examined. Icv injection of CRH dose-dependently increased plasma cortisol concentrations. These results demonstrate that central NPB stimulates cortisol secretion, suggesting that this neuropeptide plays some roles in control of the HPA axis in sheep. On the other hand, unlike its role in rodents, PrRP is unlikely to be involved in control of the HPA axis in this species.     

Growth and spawning of hatchery-reared Chinese white prawn Penaeus (Fenneropenaeus) chinensis released in the Ariake Sea, Japan

SUMMARY: Growth and reproduction of hatchery-reared Chinese white prawn Penaeus chinensis released in the Ariake Sea, Japan, were examined. Chinese white prawn grew rapidly, reaching a body length of 154 mm in males and 198 mm in females by November (219–229 days after hatching). Maximum body length of sampled individuals was 164 mm in males and 223 mm in females. Growth curve of the Chinese white prawn was fitted to the Pitcher and MacDonald's formula, L_t = 155.0{1 − e ^{2.925sin[2π(t − 16.151)/365] − 0.0623( t − 10.712)}} for males and the logistic curve, L_t = 200.3/[1 + e ^{(1.985–0.034 t )}] for females (where L_t is the body length t days after release and t is the number of days after release). Females reached sexual maturity in late February and spawning occurred until April. Minimum size at ripe and spawned stages was 189 mm and 193 mm body length, respectively.     

Quantitative mapping of kelp forests (Laminaria spp.) before and after harvest in coastal waters of the Shiretoko Peninsula,Hokkaido, Japan

In the Shiretoko Peninsula, a World Natural Heritage site, the sustainable management of kelp forests has drawn public attention because of the economic and ecological importance of kelp. We spatially estimated the distributions of kelp forests in the Shiretoko Peninsula before and after harvest. Field surveys were conducted in coastal waters (23.74 km²) at the ends of July and August 2008, immediately before and after harvest. Data on the presence or absence and thickness of the kelp forests were collected via acoustic observation. The data were interpolated using geostatistical methods. Before harvest, the kelp forests were continuously distributed over 5.64 km² (thickness 33–132 cm), especially near the north part of the study area. After harvest, they were sparsely distributed over 2.73 km² (thickness 35–105 cm). In the southern part of the study area, the influence of harvests was observed as declines in forest area. In addition, relatively thickly forested areas formed the majority of the part most likely to be harvested. Selective harvesting for area and size was confirmed though quantitative mapping of kelp forests. The quantitative mapping of both the distribution and harvest of kelp forests was successful.     

Magnesium oxide nanoparticles induce systemic resistance in tomato against bacterial wilt disease

Bacterial wilt is a serious problem affecting many important food crops. Recent studies have indicated that treatment with biotic or abiotic stress factors may increase the resistance of plants to bacterial infection. This study investigated the effects of magnesium oxide nanoparticles (MgO NP) on disease resistance in tomato plants against Ralstonia solanacearum, as well as its antibacterial activity. The roots of tomato seedlings were inoculated with R. solanacearum and then immediately treated with MgO NP; the treated plants showed very little inhibition of bacterial wilt. In contrast, when roots were drenched with a MgO NP suspension prior to inoculation with the pathogen, the incidence of disease was significantly reduced. Rapid generation of reactive oxygen species such as O₂^?˙ radicals was observed in tomato roots treated with MgO NP. Further O₂^?˙ was rapidly generated when tomato plant extracts or polyphenols were added to the MgO NP suspension, suggesting that the generation of O₂^?˙ in tomato roots might be due to a reaction between MgO NP and polyphenols present in the roots. Salicylic acid‐inducible PR1, jasmonic acid‐inducible LoxA, ethylene‐inducible Osm, and systemic resistance‐related GluA were up‐regulated in both the roots and hypocotyls of tomato plants after treatment of the plant roots with MgO NP. Histochemical analyses showed that β‐1,3‐glucanase and tyloses accumulated in the xylem and apoplast of pith tissues of the hypocotyls after MgO NP treatment. These results indicate that MgO NP induces systemic resistance in tomato plants against R. solanacearum.