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51.
Essential oil from the leaves of Chloroxylon swietenia DC. was obtained by hydrodistillation and cold extraction, and the chemical composition was determined by gas chromatography and gas chromatography-mass spectrometry. The major identified components were limonene, geijerene, pregeijerene, germacrene D and trans-beta-ocimene. Laboratory bioassays of the essential oil and four constituents of essential oil isolates were evaluated for insecticidal, antifeedant and oviposition deterrent effects on tobacco cutworm, Spodoptera litura (F.). Toxicity was determined by topical application of the isolates at varying concentrations. Pure oil, geijerene and pregeijerene were found to be more toxic, with LD50 values of 28.6, 35.4 and 40.7 microg per larva respectively. Maximum feeding deterrence was noted for geijerene and pregeijerene, with DC(50) values of 82.5 and 95.1 microg cm(-2) respectively. Furthermore, pure oil, geijerene and pregeijerene displayed oviposition deterrence, even at low concentrations. These results indicate that these natural products may lead to useful, biodegradable, environmentally safe insect control agents. 相似文献
52.
Effect of Dietary Estradiol‐17β on the Feminization of Silver Perch,Bidyanus bidyanus (Mitchell, 1838) 下载免费PDF全文
The silver perch, Bidyanus bidyanus (Mitchell 1838), displays sexual dimorphism in size, with females reaching larger maximum size than males. In an attempt to produce all‐female populations, larvae at 30 d posthatching were fed an estradiol‐17β (E2) diet at dosages of 0, 60, and 120 mg/kg for 30 d. Histological examination of gonads revealed that all E2‐supplemented diets resulted in significantly higher (P < 0.05) feminization rates (97.22–100%) than did the control (39.69%) but with no difference between the two E2 diets (P > 0.05). Female and male gonads were observed in fish fed the 60 mg E2/kg diet. No significant differences were observed in the survival rate, weight gain, gonad weight and length, specific growth rate (SGR), or gonadosomatic indexes, except for gonad length and SGR at the end of the experiment. Although the ovary length of fish fed the 60 mg E2/kg diet was significantly shorter than that of the control groups, no abnormalities were detected. In contrast, fish fed 120 mg E2/kg grew faster than the other fish and showed sexual dimorphism. Our results suggest that supplementation of E2 at 60–120 mg/kg diet could be applied to establish all‐female populations of silver perch. 相似文献
53.
Wavell Standa-Gunda Tendayi Mutimukuru Richard Nyirenda Ravi Prabhu Mandy Haggith Jerome K Vanclay 《Small-Scale Forestry》2003,2(2):313-326
Participatory modelling can be a useful process to encourage critical examination of livelihood options and foster sustainable
natural resource use through enhanced social learning, collective action and mobilization. The broom-grass group in the Mafungautsi
Forest Reserve serves as a case study of the process and outcomes of such participatory modelling. Innovative group facilitation
methods enhanced participation in the modelling process. The modelling process complements broader efforts to achieve higher
levels of adaptive collaborative management.
This work was conducted as part of the Adaptive Co-Management project of CIFOR, the Center for International Forestry Research.
We are grateful to the UK’s Department for International Development (DFID) and the European Community for financial support
of this project. 相似文献
54.
Ravi Prabhu Mandy Haggith Happyson Mudavanhu Robert Muetzelfeldt Wavell Standa-Gunda Jerome K. Vanclay 《Small-Scale Forestry》2003,2(2):185-210
ZimFlores (version 4) is the outcome of a participatory modelling process and seeks to provide a shared factual basis for
exploring land-use options for the communal lands surrounding the Mafungautsi forest. The ZimFlores experience underscores
the importance of a sharing a common problem and a common location in which all participants have an interest. Participatory
modelling has proved an effective way to consolidate a diverse body of knowledge and make it accessible. Results demonstrate
the importance of model outputs that are diagnostic, and which offer insights into the issues under consideration.
Many people contributed in many ways to help realize ZimFlores. Some of the people who contributed include Elias Ayuk, Ivan
Bond, Ephraim Chabayanzara, Muyeye Chambwera, Vijay Datadin, Wil de Jong, Peter Frost, James Gambiza, Jode Garbe, Peter Gondo,
Emmanuel Guveya, Chiedza Gwata, John Hansell, Gideon Kamumvuri, Godwin Kowero, Dominic Kwesha, Chris Legg, Tim Lynam, Hilton
Madevu, Simba Mandota, Everisto Mapedza, Frank Matose, Gutura Matoso, Chipo Mlambo, John Mudekwe, Maxwell Mukwekwerere, Dorcas
Mungwari, Tendayi Mutimukuru, Mkhululi Ngwenya, Richard Nyirenda, Bill Ritchie, Lizwelabo Sibanda, Manasa Sibanda, Fergus
Sinclair, Jivas Sithutha, Jasper Taylor, Michael Thomas, Zivanai Tsvuura and Steve Twomlow. We are grateful to the UK’s Department
for International Development (DFID) and the European Community for financial support of this project. 相似文献
55.
Rao AR Sarada R Baskaran V Ravishankar GA 《Journal of agricultural and food chemistry》2006,54(13):4593-4599
Botryococcus braunii is a green colonial microalga that is used mainly for the production of hydrocarbons, exopolysaccharides, and carotenoids. In the present study, the antioxidant properties of acetone extracts of B. braunii were evaluated using in vitro model systems such as 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxy radical scavenging, and lipid peroxidation in human low-density lipoprotein and rat tissues. Acetone extracts of B. braunii (equivalent to 10 ppm total carotenoid) exhibited 71 and 67% antioxidant activity in DPPH and hydroxyl radical scavenging model systems, respectively. Similarly, the extract also showed 72, 71, and 70% antioxidant activity in the liver, brain, and kidney of rats. Low-density lipoprotein oxidation induced by Cu2+ ions was also protected (22, 38, and 51%) by the algal extract in a dose-dependent manner (4, 6, and 8 ppm levels of total carotenoid). Thiobarbituric acid reactive substances concentration in the blood, liver, and kidney of rats was also significantly decreased in B. braunii treated samples compared with those of control. Carotenoids (violaxanthin, astaxanthin, lutein, zeaxanthin, chlorophylls a and b, and alpha, beta-carotene) identified in the B. braunii acetone extract may be exhibiting antioxidant activity. Among the carotenoids, lutein represents more than 75% of the total carotenoids. B. braunii extract was shown to be effective for protecting biological systems against various oxidative stresses in vitro. This is the first report on the antioxidant properties of B. braunii. 相似文献
56.
57.
Ravi S. Gadagi P. U. Krishnaraj J. H. Kulkarni Tongmin Sa 《Scientia Horticulturae》2004,100(1-4):323-332
The investigation was carried out to examine the performance of Azospirillum isolates on growth and N uptake of Gaillardia pulchella with two nitrogen levels. Azospirillum strain OAD-2 inoculation significantly increased plant height, number of leaves per plant, branches per plant and total dry mass accumulation in G. pulchella than other inoculations and/or uninoculated control. The application of 150 kg N ha−1 further enhanced the above plant growth parameters significantly over application of 112 kg N ha−1. The N uptake of G. pulchella was enhanced due to Azospirillum strain OAD-2 inoculation, which was further augmented in the presence of nitrogen. The combination of Azospirillum strain OAD-2 and 150 kg N ha−1 showed the highest N uptake at 120 DAT. Plant growth and yield parameters also increased when inoculated with the non-diazotrophic, but efficient IAA producing, Azospirillum strain OAD-57. From this investigation, it can be concluded that Azospirillum strains OAD-2 and OAD-11 can play an important role in the N nutrition of G. pulchella. 相似文献
58.
饲料酶制剂在动物营养中的应用--最新动态及展望 总被引:3,自引:0,他引:3
1饲料酶制剂 家禽及猪饲料添加酶制剂以提高生产性能已经有许多年历史。但仅在过去的20年里,人们对酶昕作用的底物的结构及化学性质才有更好的了解,这才使针对特定的底物来调制酶制剂成为可能:在生物技术方面,特别是在发酵和微生物技术方面已有了突破性进展,这也才使最近10年里能够生产足够物美价廉的饲用酶制剂成为现实,以保证在家禽口粮中的应用。 相似文献
59.
Hofmann-Lehmann R Cattori V Tandon R Boretti FS Meli ML Riond B Lutz H 《Veterinary immunology and immunopathology》2008,123(1-2):119-123
FeLV was discovered 40 years ago and vaccines have been commercially available for almost two decades. So far, most FeLV pathogenesis and vaccine studies were conducted assaying parameters, such as virus isolation and antigen detection. Accordingly, regressive infection was characterized by transient or undetectable viremia, while persistent viremia is typically observed in cats with progressive infection. Using real-time polymerase chain reaction assays, the spectrum of host response categories to FeLV infection was recently refined by investigating proviral and plasma viral RNA loads. Cats believed to be immune to FeLV infection were found to turn provirus-positive after virus exposure. Moreover, efficacious FeLV vaccines were found unable to prevent provirus-integration and minimal viral replication. Remarkably, no difference was found in initial proviral and plasma viral RNA loads between cats with different infection outcomes. Only subsequently, the infection outcome is associated with FeLV loads. FeLV provirus was found to persist for years; reoccurrence of viremia and disease development was observed in some cats. Thus, aviremic provirus-positive cats are FeLV carriers and, following reactivation, may act as an infection source. However, integrated viral DNA may also be essential for solid protection and long-lasting maintenance of protective immunity. In conclusion, real-time TaqMan PCR and RT-PCR assays are highly sensitive and specific. They yield a more sensitive measure for FeLV exposure than antigen detection, virus isolation or immunofluoresence assays. We recommend the use of real-time PCR assays to identify FeLV exposed cats, particularly in catteries, and investigate obscure clinical cases that may be FeLV-associated. The use of sensitive molecular methods will contribute to a more in-depth understanding of the FeLV pathogenesis. 相似文献
60.
Cattori V Pepin AC Tandon R Riond B Meli ML Willi B Lutz H Hofmann-Lehmann R 《Veterinary immunology and immunopathology》2008,123(1-2):124-128
Cats exposed to feline leukemia virus (FeLV), a naturally occurring gammaretrovirus develop either progressive or regressive infection. Recent studies using analyses with enhanced sensitivity have correlated loads throughout FeLV with the clinical outcome, though remarkably, during the acute phase of infection, proviral and viral RNA burdens in the peripheral blood do not differ between groups. We hypothesized that viral loads in specific leukocyte subsets influence the infection outcome. Using a method established to determine the proviral and cell-associated viral RNA loads in specific leukocyte subsets, we evaluated viral loads in eleven FeLV-exposed specific pathogen-free (SPF) cats 2.5 years post-infection. Six cats had undergone regressive infection whereas five were persistently viremic. Aviremic cats had lower total proviral blood loads than the persistently infected cats and FeLV proviral DNA was shown to be integrated into genomic DNA in four out of four animals. Lymphocytes were predominantly infected vs. moncytes and granulocytes in aviremic cats. In contrast, persistently viremic cats were provirus-positive in all leukocyte subsets. The acute phase kinetics of FeLV infection were analyzed in two additional cats; an early lymphoreticular phase with productive infection in lymphocytes in both cats and in monocytes in one cat was followed by infection of the granulocytes; both cats became persistently infected. These results indicate that FeLV persistent viremia is associated with secondary viremia of bone marrow origin, whereas regressive cats only sustain a non-productive infection in low numbers of lymphocytes. 相似文献