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1.
Surface-spread polytene (SSP) chromosomes of salivary glands from late third-instar larvae were used for the construction of an electron microscopic (EM) photo map of the entire genome of D. hydei. In comparison with the light microscopic chromosome map of Berendes (1963), based on squash preparations, the EM micrographs depict some 40%–50% more bands. — Two different types of chromosome constrictions are described. One type is assumed to be caused by differential distribution of chromosomal proteins; the other one appears to represent underreplicated sections in the salivary gland chromosomes.Dedicated to Prof. Dr. H.J. Becker on the occasion of his 60th birthday  相似文献   

2.
In the nuclei ofLupinus polyphyllus strongly marked chromocentres occur. In electron micrographs of anther cell nuclei these chromocentres appear either as a homogeneous network or subdivided into two distinct regions, a network-like (NR) and a banded one (GR). In both a 100 Å fiber is the basic unit. The GR is composed of 4 to 6 parallely arranged electron dense bands (240–280 Å wide) and interbands (260–300 Å wide) of low electron density. They appear to correspond to a cylindrical structure with disc-like components and connective sections. These observations are discussed in relation to chromosome structure during interphase and mitosis.
Herrn Prof. Dr. L.Geitler zur Vollendung seines 80. Lebensjahres gewidmet.  相似文献   

3.
A method is described for excising by a glass knife single bands of isolated polytene chromosomes of the salivary glands of Chironomus tentans larvae. DNA strands were isolated from cut-out bands and their contour lengths were determined on electron micrographs. The mean contour length of DNA strands isolated from the double band I-8A was about twice that of the single band I-11B, namely 63 versus 34 m. The described method may be applicable for molecular studies on single bands (e.g., by DNA cloning).  相似文献   

4.
A review of species in the genus Praon Haliday, 1833 is presented. Twenty described species are keyed and illustrated with scanning electron micrographs and line drawings. The Praon species presented in this work have been identified from 67 aphid taxa occurring on 120 plant taxa. Furthermore, 87 original parasitoid–aphid–plant associations of the species mentioned in the key are presented. Phylogenetic relationships among Praon species are reconstructed using parsimony and cladistic distance methods. Praon abjectum is the sister taxon to the remaining Praon species. We recognized three species group: “Parapraon”, “dorsale-yomenae” and “rosaecola”. Monophyly is suggested for “Parapraon” species group and paraphyly for “dorsale-yomenae” group. Finally, by phylogenetic reconstruction, a close phylogenetic relationship between “Parapraon” and “dorsale-yomenae” species group was found.  相似文献   

5.
An obligate fungus Albugo candida (Pers. ex Lév.) Ktze. (race unidentified) was successfully grown on host callus tissues of Brassica juncea cv. Varuna. Of the various type of diseased explants used, young (green) hypertrophied inflorescence axis bearing non-erumpent zoosporangial blisters allowed the fungus to multiply asexually over the host calli on modified MS-medium (Murashige and Skoog, 1962). The dual cultures were maintained up to 6–8 subcultures without loss of viability of zoosporangia on MS-medium supplemented with 10.0 mg L–1 IBA, 0.05 mg L–1 kinetin, 25.0 mg L–1 AA, 1.0 mg L–1 biotin, 1.0 mg L–1 thiamine-HCl and 1.0 g L–1 casein hydrolysate. The fungus grew only on the callus cells and not axenically on the medium. Pathogenicity test and histopathology of cultures proved the existence of the viable fungus in vitro.Abbreviations AA ascorbic acid - BAP 6-benzyl aminopurine - CH casein hydrolysate acid hydrolysed - 2,4-D-2,4 dichlorophenoxy acetic acid - FAA formaldehyde acetic acid - IAA indole-3-acetic acid - IBA indole-3-butyric acid - HgCl2 mercuric chloride - Kinetin 6-furfuryl aminopurine - MS Murashige and Skoog (1962) - NAA alpha naphthalene acetic acid - rh relative humidity - sdw sterile distilled water - wt. weights  相似文献   

6.
Summary The effects of ancymidol, abscisic acid (ABA), uniconazole, and paclobutrazol on asparagus somatic embryogenesis were evaluated. Calli induced from seedlings of genotype G447 were transferred to embryo induction medium (MS plus 3% sucrose, 0.1 mg L–1 NAA, 0.5 mg L–1 kinetin and 3% gelrite), with different concentrations of these compounds. After 8 weeks, the recovered bipolar or globular embryos were placed on germination medium (MS plus 6% sucrose, 0.1 mg L–1 NAA, 0.1 mg L–1 kinetin, 0.75 mg L–1 ancymidol, 40 mg L–1 adenine sulphate dihydrate, 0.17 mg L–1 sodium phosphate monobasic and 3% gelrite) for conversion to plantlets. Inclusion of ancymidol, ABA, uniconazole and paclobutrazol in the embryo induction medium did not affect the total number of somatic embryos produced relative to the control without these compounds. However, ancymidol, ABA and uniconazole significantly improved embryo development by increasing the production of bipolar embryos 250–750% and decreasing that of globular embryos 8–35% relative to the control. The bipolar embryos produced with any of the four compounds in the embryo induction medium converted to plantlets at rates 700–1100% greater than the control. None of the globular embryos converted to plantlets. Ancymidol (0.75 mg L–1) and ABA (0.05 mg L–1) were the most effective treatments; 61 and 46 bipolar embryos g–1 callus were produced, and 38% and 37% of the bipolar embryos converted to plantlets, respectively. These results indicated that ancymidol, ABA, uniconazole and paclobutrazol significantly enhanced the production of asparagus somatic embryos and their conversion to plantlets, and ancymidol and ABA were more effective than uniconazole and paclobutrazol.Abbreviations Ancymidol a-cyclopropyl-a(4-methoxyphenyi)-5-pyrimidine methanol - NAA 1-naphthaleneacetic acid - Paclobutrazol I-(4-chlorophenyl)-4,4-dimethyl-2(1H-1,2,4-triazol-1-yl)-pentan-3-ol - Uniconazole (E)-(p-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)-1-pentan-3-ol - ABA abscisic acid - GA gibberellic acid  相似文献   

7.
Accessory cells were studied in early spermatogenesis of flatfishes Glyptocephalus stelleri and Pleuronectes pinnifasciatus using transmission electron microscopy. The morphological organization of accessory cells in G. stelleri was similar to that of Sertoli cells. In P. pinnifasciatus, these cells had morphological organization, which had not been previously described.Translated from Ontogenez, Vol. 36, No. 1, 2005, pp. 61–63.Original Russian Text Copyright © 2005 by Neznanova, Ivankov, Reunov.  相似文献   

8.
The method of ultrathin sections of unsquashed salivary gland polytene chromosomes of Ch. thummi was applied to their ultrastructural mapping. There was a good agreement between electron micrographs and Hägele's light microscopic map (1970) with respect to the pattern and number of bands. 94% of bands were identified in larval and prepupal chromosomes. In Ch. thummi, band thickness varied from 0.05–0.5 m. Most characteristic were 0.2–0.3 m bands. Morphologically, bands were classified as: continuous (frequently with holes and gaps), discrete, dotted and continuous-discrete, discrete-dotted.Band morphology is related to band size, such that smaller bands, as a rule, were also dotted. Bands beginning to puff likewise became dotted. Interbands in unsquashed chromosome sections were from 0.05–0.15 m. The smallest interbands contained only fibrils, in the larger interbands few granules could be observed. This makes interbands distinguishable from a typical puff with many such granules.  相似文献   

9.
Both conventional and genetic engineering techniques can significantly improve the performance of animal cell cultures for the large-scale production of pharmaceutical products. In this paper, the effect of such techniques on cell yield and antibody production of two NS0 cell lines is presented. On the one hand, the effect of fed-batch cultivation using dialysis is compared to cultivation without dialysis. Maximum cell density could be increased by a factor of ~5–7 by dialysis fed-batch cultivation. On the other hand, suppression of apoptosis in the NS0 cell line 6A1 bcl-2 resulted in a prolonged growth phase and a higher viability and maximum cell density in fed-batch cultivation in contrast to the control cell line 6A1 (100)3. These factors resulted in more product formation (by a factor ~2). Finally, the adaptive model-based OLFO controller, developed as a general tool for cell culture fed-batch processes, was able to control the fed-batch and dialysis fed-batch cultivations of both cell lines.Abbreviations A membrane area (dm2) - c Glc,F glucose concentration in nutrient feed (mmol L–1) - c Glc,FD glucose concentration in dialysis feed (mmol L–1) - c Glc,i glucose concentration in inner reactor chamber (mmol L–1) - c Glc,o glucose concentration in outer reactor chamber (dialysis chamber) (mmol L–1) - c Lac,FD lactate concentration in dialysis feed (mmol L–1) - c Lac,i lactate concentration in inner reactor chamber (mmol L–1) - c Lac,o lactate concentration in outer reactor chamber (dialysis chamber) (mmol L–1) - c LS,FD limiting substrate concentration in dialysis feed (mmol L–1) - c LS,i limiting substrate concentration in inner reactor chamber (mmol L–1) - c LS,o limiting substrate concentration in outer reactor chamber (dialysis chamber) (mmol L–1) - c Mab monoclonal antibody concentration (mg L–1) - F D feed rate of dialysis feed (L h–1) - F Glc feed rate of nutrient concentrate feed (L h–1) - K d maximum death constant (h–1) - k d,LS death rate constant for limiting substrate (mmol L–1) - k Glc monod kinetic constant for glucose uptake (mmol L–1) - k Lac monod kinetic constant for lactate uptake (mmol L–1) - k LS monod kinetic constant for limiting substrate uptake (mmol L–1) - K Lys cell lysis constant (h–1) - K S,Glc monod kinetic constant for glucose (mmol L–1) - K S,LS monod kinetic constant for limiting substrate (mmol L–1) - µ cell-specific growth rate (h–1) - µ d cell-specific death rate (h–1) - µ d,min minimum cell-specific death rate (h–1) - µ max maximum cell-specific growth rate (h–1) - P Glc membrane permeation coefficient for glucose (dm h–1) - P Lac membrane permeation coefficient for lactate (dm h–1) - P LS membrane permeation coefficient for limiting substrate (dm h–1) - q Glc cell-specific glucose uptake rate (mmol cell–1 h–1) - q Glc,max maximum cell-specific glucose uptake rate (mmol cell–1 h–1) - q Lac cell-specific lactate uptake/production rate (mmol cell–1 h–1) - q Lac,max maximum cell-specific lactate uptake rate (mmol cell–1 h–1) - q LS cell-specific limiting substrate uptake rate (mmol cell–1 h–1) - q LS,max maximum cell-specific limiting substrate uptake rate (mmol cell –1 h–1) - q Mab cell-specific antibody production rate (mg cell–1 h–1) - q MAb,max maximum cell-specific antibody production rate (mg cell–1 h–1) - t time (h) - V i volume of inner reactor chamber (culture chamber) (L) - V o volume of outer reactor chamber (dialysis chamber) (L) - X t total cell concentration (cells L–1) - X viable cell concentration (cells L–1) - Y Lac/Glc kinetic production constant (stoichiometric ratio of lactate production and glucose uptake) (–)  相似文献   

10.
Thiobacillus A2 was grown in glucose- or ammonium-limited chemostats and relative contributions of the Embden-Meyerhof (EM), Entner-Doudoroff (ED) and pentose phosphate (PP) pathways to glucose catabolism estimated by 14C-glucose radiorespirometry. In fast growing strain GFI, the EM pathway predominated (41–79%) under all growth conditions with the PP pathway contributing 18–30%. The ED pathway was apparently absent under some conditions of glucose limitation. In contrast, wild type Thiobacillus A2 exhibited predominance of the EM pathway (43–48%) under ammonium-limitation but apparent predominance of the PP pathway (43–55%) under glucose-limitation, although all three pathways were calculated to operate. Under some conditions of glucose limitation the EM pathway was possibly considerably depressed. No clear pattern of response of the three pathways to altered environmental conditions could be deduced, although marked change in pathway activities were obviously induced. Growth yield was apparently unaffected by variation in pathways. The problems of interpreting such complex radiorespirometric data are discussed.Abbreviations EM Embden-Meyerhof - ED Entner-Doudoroff - KDPG 2-keto-3-deoxy-6-phosphogluconate - 6-PG 6-phosphogluconate - PK phosphoketolase - PP pentose phosphate  相似文献   

11.
Georg Imsiecke 《Zoomorphology》1993,113(4):233-244
Summary The route followed by food particles in Spongilla lacustris was clarified by light and electron microscopic examination of sponges fed with Chlamydomonas reinhardtii. The algal cells are phagocytosed by prosendopinacocytes and choanocytes. After some time they are transferred to archaeocytes, amoebocytes, and lophocytes. Changes in algal structure during digestion were observed and the egestion of algal remnants was documented in life for the first time. In light micrographs, digestion of the algal cells is manifest first in shrinkage of the cells, then in disintegration to form several spherical green fragments 2–3 m in diameter, and finally, after 12–18 h, in a reddish brown discoloration of the fragments. Signs of the digestive process in electron micrographs include disappearance of the cell-wall layers, the flagella, and the pyrenoid and its starch sheath, as well as a progressive increase in the density of the cytoplasm and karyoplasm.  相似文献   

12.
Age and growth of the whiskery shark, Furgaleus macki, from southwestern Australia were examined using vertebral ageing and tag-recapture data. The readability of bands on the vertebral centra varied markedly between individuals. Four readers were used to make band counts, with the most experienced reader having the lowest index of average percent error and the highest level of agreement with final counts. Marginal increment analysis indicated that opaque bands form in January. With parturition occurring from August to October, size data suggests that the first band is probably formed 15–17 months after birth. The age at maturity was estimated to be 4.5 years for males, and 6.5 years for females. The oldest male was 10.5 years, and oldest female was 11.5 years. Von Bertalanffy growth parameters for males were L =121.5cm fork length, K=0.423 year–1, t 0=–0.472 years, were L =120.7cm fork length, K=0.369 year–1, t 0=–0.544 years for females, and were L =118.1cm fork length, K=0.420 year–1, t 0=–0.491 years for combined sexes. Data from a tag recapture study were analysed using a maximum likelihood method to verify the estimates of growth parameters from vertebral ageing. Von Bertalanffy growth parameters from the tag recapture study were L =128.2cm fork length, K=0.288 year–1, t 0=–0.654 years. The two methods of estimating growth parameters produced similar results, with rapid growth until approximately 5 years of age, after which there was little increase in length.  相似文献   

13.
S. cerevisiae was grown in a blackstrap molasses containing medium in batch and fed-batch cultures. The following parameters were varied: pH (from 4.0 to 6.5), dissolved oxygen (DO) (from 0 to 5.0 mg O2L–1) and sucrose feeding rate. When glucose concentration (S) was higher than 0.5 g L–1 a reduction in the specific invertase activity of intact cells (v) and an oscillatory behavior of v values during fermentation were observed. Both the invertase reduction and the oscillatory behavior of v values could be related to the glucose inhibitory effect on invertase biosynthesis. The best culture conditions for attainingS. cerevisiae cells suitable for invertase production were: temperature=30°C; pH=5.0; DO=3.3 mg O2L–1; (S)=0.5 g L–1 and sucrose added into the fermenter according to the equations: (V–Vo)=t2/16 or (V–Vo)=(Vf–Vo)·(e0.6t–1)/10.This work was supported by FAPESP  相似文献   

14.
Endogenous phosphorylation of proteins from rat brain synaptosomal plasma membranes was studied in vitro. Cyclic AMP (cAMP) markedly stimulated32P incorporation in three protein bands with molecular weights of 75,000, 57,000, and 54,000, respectively. The effect of the behaviorally active peptide ACTH1–24 on this endogenous phosphorylation in vitro was studied using peptide concentrations from 10–10 to 10–4 M. In a number of protein bands, a biphasic effect of ACTH1–24 was observed: in concentrations of 10–4–10–5 M, a reduced amount of32P was found; in concentrations of 10–6–10–7 M, hardly any effect could be detected, whereas consistently at concentrations around 10–8 M, a significant decrease was again observed. The phosphoprotein bands affected by in vitro addition of ACTH1–24 were of a smaller molecular weight than those affected by in vitro addition of cAMP.  相似文献   

15.
From the liver of fish Dasyatis akajei, ferritin has been isolated by thermal denaturation and ammonium sulfate fractionation and then further purified by anion exchange chromatography and gel exclusion chromatography. The molecular weight of the liver ferritin of D. akajei (DALF) was measured to be 400 kDa by PAGE. Moreover, SDS-PAGE experimentation indicates that protein shell of DALF consists of the H and L subunits with molecular weight of 18 and 13 kDa, respectively. Using isoelectric focusing with pH ranging from 5.0 to 6.0, the ferritin purified by the PAGE exhibited three bands with different pI values in the gel slab. Diameters of the protein shell and iron core were also investigated by transmission electron microscope and determined to be 10–12 nm and 5–8 nm, respectively. A kinetic study of DALF reveals that the rate of self-regulation of the protein shell rather than the complex surface of the iron core plays an important role in forming a process for iron release with mixed orders.  相似文献   

16.
This study examines the influence of current velocity in the toxiceffect of copper in diatom-dominated biofilms grown in artificial channels.Effects on community structure, algal biomass and photosynthesis (carbonincorporation) caused by 15 g L–1 of copperwere tested at contrasting (1 and 15 cm s–1)velocities. Moreover, a possible threshold on the effect of copper on algalbiomass and photosynthesis related to current velocity was examined by usingprogressively increasing current velocity (1 to 50 cms–1) at 15 g L–1 Cu.Chlorophyll-a decreased ca. 50% as a result of addition of15 g L–1 Cu. Chlorophyll decrease occurredearlier at 15 cm s–1 than at 1 cms–1 when adding 15 g L–1Cu. Copper also caused a remarkable decrease in carbon incorporation(from 30 to ca. 50%), which was produced earlier at 15 cms–1 (three days) than at 1 cms–1 (seven days). Some taxa were affected by thecombination of copper and current velocity. Both Achnanthesminutissima and Stigeoclonium tenue becomedominant at 15 cm s–1 in the presence of copper.Significant inhibition of algal growth in 15 g L–1Cu occurred at low (1 cm s–1) and highvelocities (50 cm s–1), but not at intermediatevelocity (20 cm s–1). The experiments indicatethat current velocity triggers the effect that copper has on diatom-dominatedbiofilms, and that the effect is more remarkable at low and high than atintermediate current velocities.  相似文献   

17.
A strain of Kluyveromyces marxianus was grown in batch culture in lactose-based media at varying initial lactose concentrations (10–60 g L–1) at 30°C, pH 5.0, dissolved oxygen concentrations greater than 20%. Increasing the concentration of mineral salts three-fold at 40 g L–1 and 60 g L–1 initial lactose concentration showed only a small increase in the yield of biomass, from 0.38 g g–1 to 0.41 g g–1, indicating that the initial batch cultures were not significantly nutrient- (mineral salts)-limited. A relatively high biomass concentration (105 g L–1) was obtained in fed-batch culture following extended lactose feeding. An average specific growth rate (0.27 h–1), biomass yield (0.38 g g–1) and overall productivity (2.9 g L–1 h–1) were obtained for these fed-batch conditions. This fed-batch protocol provides a strategy for achieving relatively high concentrations and productivities of K. marxianus on other lactose-based substrate streams (e.g., whey) from the dairy industry.  相似文献   

18.
The performance of a continuous bioreactor containing Clostridium beijerinckii BA101 adsorbed onto clay brick was examined for the fermentation of acetone, butanol, and ethanol (ABE). Dilution rates from 0.3 to 2.5 h–1 were investigated with the highest solvent productivity of 15.8 g l–1 h–1 being obtained at 2.0 h–1. The solvent yield at this dilution rate was found to be 0.38 g g–1 and total solvent concentration was 7.9 g l–1. The solvent yield was maximum at 0.45 at a dilution rate of 0.3 h–1. The maximum solvent productivity obtained was found to be 2.5 times greater than most other immobilized continuous and cell recycle systems previously reported for ABE fermentation. A higher dilution rate (above 2.0 h–1) resulted in acid production rather than solvent production. This reactor was found to be stable for over 550 h. Scanning electron micrographs (SEM) demonstrated that a large amount of C. beijerinckii cells were adsorbed onto the brick support.  相似文献   

19.
Biofilms are a natural form of cell immobilization that result from microbial attachment to solid supports. Biofilm reactors with polypropylene composite-supports containing up to 25% (w/w) of various agricultural materials (corn hulls, cellulose, oat hulls, soybean hulls or starch) and nutrients (soybean flour or zein) were used for ethanol production. Pure cultures ofZymomonas mobilis, ATCC 31821 orSaccharomyces cerevisiae ATCC 24859 and mixed cultures with either of these ethanol-producing microorganisms and the biofilm-formingStreptomyces viridosporus T7A ATCC 39115 were evaluated. An ethanol productivity of 374g L–1 h–1 (44% yield) was obtained on polypropylene composite-supports of soybean hull-zein-polypropylene by usingZ. mobilis, whereas mixed-culture fermentations withS. viridosporus resulted in ethanol productivity of 147.5 g L–1 h–1 when polypropylene composite-supports of corn starch-soybean flour were used. WithS. cerevisiae, maximum productivity of 40 g L–1 h–1 (47% yield) was obtained on polypropylene composite-supports of soybean hull-soybean flour, whereas mixed-culture fermentation withS. viridosporus resulted in ethanol productivity of 190g L–1 h–1 (35% yield) when polypropylene composite-supports of oat hull-polypropylene were used. The maximum productivities obtained without supports (suspension culture) were 124 g L–1 h–1 and 5 g L–1 h–1 withZ. mobilis andS. cerevisiae, respectively. Therefore, forZ. mobilis andS. cerevisiae, ethanol productivities in biofilm fermentations were three- and eight-fold higher than suspension culture fermentations, respectively. Biofilm formation on the chips was detected by weight change and Gram staining of the support material at the end of the fermentation. The ethanol production rate and concentrations were consistently greater in biofilm reactors than in suspension cultures.This is Journal Paper No. J-16356 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project No. 3253  相似文献   

20.
In order to characterize the functional diversity in CYP63 cluster of tandemly linked P450 genes (pc-1, pc-2, and pc-3) in Phanerochaete chrysosporium, here we report the functional characterization of pc-3 (CYP63A3), a newly cloned member of this group. pc-3 expression was favored in nutrient-limited versus nutrient-rich media in 3–6-day-old cultures and was upregulated by starch as a carbon source or by oxygenation of cultures. pc-3 was induced by various xenobiotics in defined nutrient-limited (3–9-fold) and nutrient-rich (2–5-fold) cultures. Particularly, a range of unsubstituted and substituted aliphatic hydrocarbons (alkanes and fatty acids) induced the expression under the two nutrient conditions albeit in a differential manner. Interestingly, pc-3 was also inducible by certain oxygenated mono aromatics (nitrophenol, benzoate, and resorcinol), lower molecular weight (2 to 4 ring size) polycyclic aromatic hydrocarbons (PAHs) and alkali-treated lignin derivatives in nutrient-rich malt extract cultures. The study further establishes that the three CYP63 genes (CYP63A1, A2, and A3) are independently regulated despite being members of the tandem gene cluster with high gene structural similarity (13–14 introns) and protein sequence homology (59–85%). The pc-3 cDNA (1,812 bp) was expressed in E. coli as a His-tagged protein (∼ 74 kDa). This constitutes the first report on heterologous expression of a P450 monooxygenase enzyme from this model white-rot fungus.  相似文献   

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