Evolutionary plasticity of monooxygenase-mediated resistance

The cytochrome P450 monooxygenases are an important metabolic system involved in the detoxification of xenobiotics, and are thus one of the major mechanisms by which insects evolve insecticide resistance. However, comparatively little is known about the evolutionary constraints of this insecticide resistance mechanism. We investigated the genetic basis of resistance in a strain of house fly (NG98) from Georgia, USA that had evolved 3700-fold resistance to the pyrethroid insecticide permethrin, and compared this to other permethrin resistant strains of house flies from the US and Japan. Resistance in NG98 was due to kdr on autosome 3 and monooxygenase-mediated resistance on autosomes 1, 2, and 5. These results indicate that the genes which evolve to produce monooxygenase-mediated resistance to permethrin are different between different populations, and that the P450 monooxygenases have some degree of plasticity in response to selection. Monooxygenase-mediated resistance appears to evolve using different P450s, and possibly different regulatory signals controlling P450 expression, even in strains selected with the same insecticide.     

旋毛虫T3223-6 cDNA的表达及鉴定

利用PCR技术将T3223-6 cDNA扩增克隆到原核表达载体pET-28a,将重组质粒转入克隆菌Nova-blue,提取质粒进行酶切和测序鉴定后转入表达菌BL21star(DE3).用1 mM IPTG诱导培养重组表达菌,对菌体裂解物进行SDS-PAGE分析,检测重组蛋白的表达情况.用旋毛虫感染猪血清和正常血清,通过western blotting检测重组蛋白的反应原性.结果表明:经IPTG诱导后重组转化菌的裂解产物出现44 kD左右的表达带,大小与理论值相符;western blotting检测结果显示重组蛋白可以被旋毛虫感染猪血清识别,具有反应原性.     

Inhibition of growth hormone secretagogue receptor antagonist, [D-Lys-3]-GHRP-6, in adipogenesis of ovine and rat adipocytes

Ghrelin and growth hormone secretagogues receptor (GHS‐R or ghrelin receptor) have been reported as being one of the factors of adipogenesis in adipocytes. To investigate the involvement of ghrelin and GHS‐R in adipocytes, the effect of the GHS‐R antagonist, [D‐Lys‐3]‐GHRP‐6 (His‐D‐Trp‐D‐Lys‐Trp‐D‐Phe‐Lys‐NH₂), on the process of adipogenesis in ovine and rat adipocytes was evaluated. [D‐Lys‐3]‐GHRP‐6 (10^?7 mol/L) significantly inhibited adipogenic differentiation of ovine and rat preadipocytes prepared from adipose tissues. The level of peroxisome proliferator activated receptor (PPAR)‐γ2 mRNA, an adipogenic marker, was decreased during the differentiation of adipocytes treated with [D‐Lys‐3]‐GHRP‐6 for 10 days. Ghrelin stimulated adipogenesis, also causing an increment of glycerol‐3‐phosphate dehydrogenase and upregulation of PPAR‐γ2. Furthermore, the antilipolytic effect of ghrelin was attenuated by treatment with [D‐Lys‐3]‐GHRP‐6 in both types of isolated adipocytes. Overall, the results of the present study highlight that GHS‐R in adipogenesis can be blocked by treatment with [D‐Lys‐3]‐GHRP‐6.     

Widespread Detection of Phytophthora Taxon Salixsoil in the Littoral Zone of Lake Constance, Germany

An unnamed ITS clade 6 Phytophthora was frequently isolated from rhizosphere soil of reed (Phragmites australis) growing on the littoral zone of Lake Constance. The isolates closely resembled P. gonapodyides, having internally proliferating, non-papillate sporangia, a rather high temperature optimum for growth (30 °C), and being sexually sterile. ITS sequence analysis revealed that they were identical to the as yet unnamed Phytophthora taxon Salixsoil, originally isolated from Salix roots in the UK and Alnus debris in Denmark. The taxon was readily isolated from permanently as well as occasionally flooded reed sites using standard baiting procedures, indicating a wide distribution in the Lake Constance littoral zone. In an in vitro leaf inoculation assay P. taxon Salixsoil proved to be more aggressive towards Salix alba than P. gonapodyides. The new taxon may be of significance as a root pathogen of woody plants in moist or flooded situations occurring in alluvial forest/plant communities. We propose that due to its close resemblance to P. gonapodyides the taxon might have passed unnoticed in the past, and possibly is much more widely distributed than previously recognised.     

Deletion of Cyp6d4 does not alter toxicity of insecticides to Drosophila melanogaster

Cytochrome P450-dependent monooxygenases are important in the activation and detoxification of numerous insecticides. In this study, a Drosophila melanogaster Cyp6d4 null mutant was used to determine the role of this P450 in insecticide metabolism. This null mutant was generated by imprecise excision of a mobile P element located upstream to the P450 gene Cyp6d4. Comparative analysis between the non-functional mutant and relevant control strains shows that Cyp6d4 does not appear to be involved in the metabolism of chlorfenapyr, cypermethrin, diazinon, imidacloprid, malathion, oxamyl, parathion, or pyrethrum extract, even though these insecticides are known to be activated or detoxified by P450-monooxygenases. No obvious abnormalities in development were seen in the Cyp6d4 null mutant, indicating that Cyp6d4 is not critical for the metabolism of vital endogenous substrates.     

Conservation of Zingiber germplasm through in vitro rhizome formation

The effects of various concentrations of maleic hydrazide (MH; 2, 4, 6, 8 mg/l) and three light treatments (16-h, 24-h, 0-h) on in vitro rhizome formation and conservation of ginger (Zingiber officinale Rosc. cv. Rio de Janeiro) were studied. In vitro rhizome formation occurred in all the above treatments. Addition of MH (2–8 mg/l) to the control medium (CM) comprising Murashige and Skoog's (1962) salts, 9% sucrose, 0.8% agar-agar, 0.1 mg/l α-naphthaleneacetic acid (NAA), 1 mg/l N⁶-benzyladenine (BA), did not show any significant positive effects on rhizome formation as well as survival of cultures. A significant effect of light treatments was observed on survival of cultures but not on rhizome formation. More than 50% cultures survived up to 14 months on CM under 16-h and 24-h light conditions as compared to 20% cultures on same medium incubated under dark. A total of 33 genotypes of cultivated and wild species of Zingiber were subsequently tested for conservation through in vitro rhizome formation on CM under 16-h light condition. All genotypes produced rhizomes of varying size with numbers ranging from 3 to 15 per culture and were conserved for at least 12 months; some genotypes could be conserved even up to 16–20 months. Viability of rhizomes was determined by in vitro regeneration of shoots upon subculture and their subsequent establishment in soil. Following the protocol described in the present paper, some 160 genotypes of cultivated and wild species of Zingiber, collected from different geographical regions of India, are being conserved at In Vitro Genebank of National Bureau of Plant Genetic Resources, New Delhi.     

In vitro multiplication of statice plantlets using sugar-free media

Clumps of statice (Limonium latifolium) plantlets grown photomixotrophically were used as explants and cultured for 25 days on a sugar-free modified Murashige and Skoog (MS) medium in Magenta-type vessels with the number of air exchanges of the vessel (NAE) being 3.8 h⁻¹, at a photosynthetic photon flux (PPF) of 100 μmol m⁻² s⁻¹ and a CO₂ concentration of 1500 μmol mol⁻¹ in the culture room. A factorial experiment was conducted with three levels of 6-benzylaminopurine (BA) concentration, namely 0, 0.25 and 0.5 mg L⁻¹, and two types of supporting material, agar and Florialite (a porous material). The control treatment was a photomixotrophic culture using a sugar- and BA (0.25 mg L⁻¹) containing agar medium in the vessel with NAE of 0.2 h⁻¹, at a PPF of 50 μmol m⁻² s⁻¹ and a CO₂ concentration of 400 μmol mol⁻¹ in the culture room. Leaf area, chlorophyll concentration and net photosynthetic rate were greater in the sugar-free medium treatment with a BA concentration of 0.25 mg L⁻¹ and Florialite than those in the control treatment. The number of shoots and dry weight per clump in the sugar-free medium treatment were comparable to those in the control treatment. Among the sugar-free medium treatments, the number of shoots increased with increasing BA concentration, however, the leaf area, dry weight, chlorophyll concentration and net photosynthetic rate decreased with increasing BA concentration. The use of Florialite significantly enhanced the growth and root induction as well as net photosynthetic rate, compared with the treatments that use agar. These results indicated that sugar-free medium micropropagation could be commercially applied to the multiplication of statice plantlets.     

苏椒六号的选育

苏椒六号是中早熟辣椒一代杂种,适于近郊早春保护地栽培和远郊露地,地膜栽培,果大,长灯笼形,辣味中等,抗ＴＭＶ,耐ＣＭＶ,产量３０００～４０００ｋｇ／６６７ｍ＾２。