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941.
942.
Summary The ultrastructure of active and inactive corpora allata from last instar larvae of the southwestern corn borer, Diatraea grandiosella, was examined. Active glands were obtained from pre-, early, and mid-diapausing larvae; inactive ones from late and non-diapausing larvae. Each gland contains 13 to 18 cells which have the following common features: well developed smooth endoplasmic reticulum, scattered rough endoplasmic reticulum and free ribosomes, microtubules, vacuolated nucleoli, and interlocking plasma membranes. The gland contains intercellular deposits, and is supplied by regular and neurosecretory axons.Special ultrastructural features of the corpus allatum from the five groups of larvae examined were as follows: pre-diapause: extensive vesicular smooth endoplasmic reticulum, numerous cup-shaped mitochondria and Golgi bodies with stacked cisterns and vesicles, few small lipid droplets, large nuclei with dispersed chromatin, absence of lysosomes; early diapause: stacked, whorled, and vesicular smooth endoplasmic reticulum of equal abundance, numerous rod-shaped mitochondria, some Golgi bodies but without distinct stacks of cisterns, few lipid droplets and lysosomes, chromatin dispersed and also attached to the nuclear envelope; mid-diapause: similar to early diapause except for the presence of more stacked, smooth endoplasmic reticulum, chromatin in large chunks mostly attached to the nuclear envelope; late diapause: whorled smooth endoplasmic reticulum and rod-shaped mitochondria predominating, complicated Golgi bodies with stacks of cisterns and large empty sacs, few large lipid droplets, some lysosomes containing mainly whorled bodies, chromatin in large chunks attached to the nuclear envelope; non-diapause: similar to late diapause except for less extensive smooth endoplasmic reticulum, more abundant mitochondria, fewer intercellular deposits. Although these observations suggest that the smooth endoplasmic reticulum, and possibly mitochondria, and Golgi bodies are involved in juvenile hormone production, specific sites of synthesis or storage of the hormone were not revealed.Supported in part by grant no. PCM 74-18155 A01 from the National Science Foundation. Contribution from the Missouri Agricultural Experiment Station as journal series no. 8234. We thank Ms. L. Yin for her skillful assistance, and Dr. M.F. Brown of the College of Agriculture Electron Microscope Facility for his advice and the use of equipment. 相似文献
943.
Changes in population levels of Meloidogyne hapla, M. incognita, Pratylenchus coffeae, and P. penetrans were studied in 12 strawberry fields in the Dahu region of Taiwan. Ten potential rotation crops and two cultural practices were evaluated for their effect on nematode populations and influence on strawberry yield. Rotation with rice or taro and the cultural practice of flooding and bare fallowing for four months were found to reduce nematode soil populations to two or fewer nematodes per 100 ml soil. Average strawberry yields increased between 2.4% to 6.3% following taro compared to the bare fallow treatment. Corn suppressed M. incognita and M. hapla populations and resulted in an increased in strawberry yield compared to bare fallow. Other phytopathogens also present in these fields limited taro as the rotation choice for nematode management. Results of this research and economic analysis of the input requirements for various rotation crops, corn and bare fallow were recommended as the most appropriate rotation strategies for nematode management in strawberry in this region. 相似文献
944.
Michael E. Horn Robin L. Harkey Amanda K. Vinas Carol F. Drees Donna K. Barker Jeffrey R. Lane 《In vitro cellular & developmental biology. Plant》2006,42(4):359-366
Summary Hybrid embryos resulting from crosses between a highly regenerable maize germplasm (Hi II) and certain elite inbreds were
treated with Agrobacterium tumefaciens containing the uidA (GUS) and pat genes under the control of different constitutive promoters. Six of the elite inbred lines were derived from a Lancaster
background and three were derived from an Iowa Stiff Stalk background. Hybrid embryos from all three Stiff Stalk lines gave
transgenic events at various frequencies, two of them at a comparable frequency to that observed with Hi II embryos. Embryos
from only one Lancaster/Hi II hybrid were successfully transformed and the frequency was quite low. Additional Lancaster elite
inbreds were then tested as a hybrid with Hi II and failed to produce a single transgenic event. The transgenic Hi II/elite
events showed many characteristics of ‘hybrid vigor’ including more aggressive rooting, thicker stems, and taller stature
than plants derived from Hi II events. The hybrid T0 plants exhibited excellent tassel development in the greenhouse with abundant pollen shed. Seed set in the greenhouse was
significantly (3–5-fold) higher than with Hi II transformats. Attempts to transform embryos derived from self or sibling crosses
of the four inbred lines that were successful as hybrids with Hi II did not produce any transgenic events. T0 plants having ∼50% elite genomic contribution perform nearly as well in the greenhouse as seed-derived elite inbred parents
and offer a significantly reduced time line for recombinant protein product development from transgenic plants. 相似文献
945.
946.
Screening toxicity study in young carp (Cyprinus carpio L.) on feed amended with fumonisin B1 总被引:1,自引:0,他引:1
Fumonisin B1 (FB1) is one of several mycotoxins produced by Fusarium moniliforme, a major fungal pathogen of corn and widely spread throughout the world. FB1 produces a wide range of biological effects, some of which are specific for particular organs or species and some are common to all investigated animals. In this study we have evaluated subchronic toxicosis features in young carp (Cyprinus carpio L.) exposed to 0.5 and 5.0 mg FB1 kg–1 body weight for 42 days through nutritionally balanced diet. During the trial we observed loss of body weight in both treated groups, together with higher incidence of infective bacterial dermatological lesions erythrodermatitis cyprini (Aeromonas salmonicida subsp. nova) in the group treated with the higher FB1 dose. Several hematological parameters (erythrocyte count, platelet count) and serum chemical concentrations (creatinin, total bilirubin) and activities (aspartate aminotransferase, AST and alanine aminotransferase, ALT) were greater in the fumonisin treated groups than in the control group. Our results indicate that long-term dietary exposure to 0.5 and 5.0 mg FB1 kg–1 body weight is not lethal to young carp, but can produce adverse physiological effects. These findings also suggest that primary target organs of FB1 in the carp are kidney and liver, as it has already been observed in other animal species tested. Specifically changed red blood cell-parameters reveal that FB1 probably causes erythrocyte membrane defect or interferes with carp's respiratory process.This revised version was published online in October 2005 with corrections to the Cover Date. 相似文献
947.
土壤微生物碳源代谢特征是评价土壤质量变化的重要指标。依托山西省东部晋中市寿阳县农业环境与作物高效用水科学观测试验站,采用Biolog-ECO微孔板技术探究覆膜(FM)与裸地不覆膜处理(LD)对旱作春玉米拔节期、灌浆期和收获期3个关键生育期不同土层深度下(0-10 cm、10-20 cm和20-30 cm)土壤微生物碳源代谢的影响。结果表明:1) FM措施可以显著增加土壤微生物对碳源的利用能力,显著提高了土壤微生物的优势度指数,但降低了土壤微生物的均匀度指数。2)在0-10 cm和10-20 cm土层,FM与LD处理土壤微生物碳源利用情况均表现为灌浆期较高,而20-30 cm土层,表现为收获期较高,差异均主要体现在碳水类、羧酸类、氨基酸类3大类碳源上。3)拔节期和灌浆期0-10 cm土层中FM处理的土壤微生物碳源利用能力显著高于LD处理;然而收获期0-10 cm土层中恰好相反,呈现出LD处理下土壤微生物碳源利用能力显著高于FM处理。4)此外,Pearson相关分析表明,FM处理土壤微生物对碳水类碳源和羧酸类碳源2大类碳源的利用能力主要与土壤有机碳(SOC)和全氮(TN)含量相关性较好,呈现出正相关关系;对氨基酸类碳源的利用能力主要与土壤含水量、pH、SOC、NH4+-N和NO3--N含量相关性较好。LD处理下,土壤微生物对碳水类、羧酸类和氨基酸类碳源的利用能力与土壤中TN含量的相关性较好,且呈现正相关关系。 相似文献
948.
Degradation of raw corn stover powder (RCSP) by an enriched microbial consortium and its community structure 总被引:3,自引:0,他引:3
Yujie Feng Yanling YuXin Wang Youpeng QuDongmei Li Weihua HeByung Hong Kim 《Bioresource technology》2011,102(2):742-747
A microbial consortium with a high cellulolytic activity was enriched to degrade raw corn stover powder (RCSP). This consortium degraded more than 51% of non-sterilized RCSP or 81% of non-sterilized filter paper within 8 days at 40 °C under facultative anoxic conditions. Cellulosome-like structures were observed in scanning electron micrographs (SEM) of RCSP degradation residue. The high cellulolytic activity was maintained during 40 subcultures in a medium containing cellulosic substrate. Small ribosomal gene sequence analyses showed the consortium contains uncultured and cultured bacteria with or without cellulolytic activities. Among these bacteria, some are anaerobic others aerobic. Analyses of the culture filtrate showed a typical anoxic polysaccharide fermentation during the culturing process. Reducing sugar concentration increased at early stage followed by various fermentation products that were consumed at the late stage. 相似文献
949.
The effects of plantain starch obtained from the unripe fruit of the plantMusa paradisiaca L. (Musaceae) on the mechanical and disintegration properties of paracetamol tablets have been investigated in comparison with
the effects of corn starch BP using a 23 factorial experimental design. The individual and combined effects of nature of starch binder (N), concentration of starch
binder (C), and the relative density of tablet (RD) on the tensile strength (TS), brittle fracture index (BFI), and disintegration
time (DT) of the tablets were investigated. The ranking of the individual effects on TS was RD>C≫N, on BFI was C≫RD>N and
on DT was N>C>RD. The ranking for the interaction effects on TS and DT was N-C≫N-RD>C-RD, while that on BFI was N-C≫C-RD>N-RD.
Changing nature of starch from a “low” (plantain starch) to a “high” (corn starch) level, increasing the concentration of
starch binding agent from 2.5% to 10.0% wt/wt, and increasing relative density of the tablet from 0.80 to 0.90, led to increase
in the values of TS and DT, but a decrease in BFI. Thus, tablets containing plantain starch had lower tensile strength and
disintegration time values than those containing corn starch, but showed better ability to reduce the lamination and capping
tendency in paracetamol tablet formulation. The interaction between N and C was significantly (P<.001) higher than those between N and RD and between C and RD. There is therefore the need to carefully choose the nature
(N) and concentration (C) of starch used as binding agent in tablet formulations to obtain tablets of desired bond strength
and disintegration properties. Furthermore, plantain starch could be useful as an alternative binding agent to cornstarch,
especially where faster disintegration is required and the problems of lamination and capping are of particular concern.
Published: October 22, 2005 相似文献
950.
Lalitha S Shade RE Murdock LL Bressan RA Hasegawa PM Nielsen SS 《Comparative biochemistry and physiology. Toxicology & pharmacology : CBP》2005,140(2):227-235
Three recombinant soybean cysteine proteinase inhibitors (rSCPIs), L1, R1 and N2, were assessed for their potential to inhibit the growth and development of three major agricultural crop pests known to utilize digestive cysteine proteinases: Western corn rootworm (Diabrotica virgifera virgifera, WCR), Colorado potato beetle (Leptinotarsa decemlineata, CPB) and cowpea weevil (Callosobruchus maculatus, CW). In vitro experiments showed that cysteine proteinase activities in the crude gut extracts of the WCR, CPB, and CW were inhibited to various degrees by the three rSCPIs. Of the three rSCPIs tested, N2 was most effective in inhibiting the crude gut extract of WCR, CPB, and CW (50% inhibition at 5 x 10(-8), 5 x 10(-8), and 3 x 10(-7) M, respectively). The L1 was the least potent of the three CPIs tested, with 50% inhibition at 5 x 10(-6) M of the crude gut extracts of WCR. Results of in vivo experiments conducted to assess the effect of the three rSCPIs on the vital growth parameters of WCR, CPB and CW were consistent with results of the in vitro experiments. 相似文献