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2.
Nabil N. Youssef 《Journal of morphology》1975,146(3):307-323
The fine structure of the intersegmental glands of the sixth abdominal sternum in 1-week old females of Nomia melanderi is presented. The plasma membrane of the secretory cell is unfolded in many places and is covered by a basement membrane. The microvillous surface is invaginated to form a rather long sinuous cavity. The endoplasm is almost entirely filled by secretory granules. Many secretory granules are located close to the inner surface of the invaginated plasma membrane. The invagination contains a porous ductule, apparently of cuticulin origin, that is connected directly with the inner layer of the transport duct of the duct-forming cell. This type of arrangement allows the direct flow of the secretory substance to the outside in a continuous way. The cylindrical duct-forming cell, besides having typical cell organelles, contains a cuticular transport duct. This duct is composed of a thin cuticulin layer surrounded by a rather thick epicuticular one. The results suggest that the secretory cell has two secretory cycles. The first occurs while the gland is differentiating (at the pupal stage) and is involved in secretion of the cuticulin that forms the porous ductule. The second cycle, which starts by the beginning of nesting, is involved in the secretion of a substance that is carried to the outside via the transport duct of the duct-forming cell. 相似文献
3.
Cells of S. cerevisiae strain "14-12" of different ages were immobilized in sodium alginate and used for conversion of glucose to ethanol. Immobilized cells of 48 hr old were the most potential. Employment of high counts of alginate-entrapped cells shortened the period required for production of the maximal alcohol yield. However, the percentage surviving cells decreased with increasing initial cell counts. Maximal accumulation of ethanol (4.18 g/100 ml) was obtained after 4 days of static fermentation with 1.8 X 10(8) immobilized yeast cells. The residual viable cell count was found to represent 3-fold the surviving percentage in a control experiment using an inoculum of the free yeast cells. Immobilized yeast cells could convert about 85% of the available sugars to ethanol over 28 days of the repeated-batch fermentation. The immobilized cells retained 50% of their viability for 16 days. After 48 days of repeated fermentation only 6% of the yeast cells were viable, and on the 52nd day no viable cells could be detected. 相似文献
4.
Ethanol tolerance ofSaccharomyces cerevisiae and its relationship to lipid content and composition 总被引:2,自引:0,他引:2
Saccharomyces cerevisiae strain 14-12 is a highly ethanol-tolerant organism. It can grow in the presence of 13% ethanol but growth is completely prevented at 14% ethanol. A relationship was detected between yeast lipids and ethanol tolerance. A gradual decrease of lipid content was recorded as the concentration of supplemented ethanol increased. Moreover, free fatty acids were comparatively decreased in these lipid extracts. When separately added to media with 14% ethanol different lipids produced varied stimulatory effects on yeast growth. Maximum yield of yeast growth was obtained at 14% ethanol in the presence of lecithin, palmitic acid and cholesterol. Yeast lipids produced in the presence of these fractions are characterized by a relatively high percentage of free fatty acids. The change in the percentage of free fatty acids was shown to be the controlling factor in ethanol tolerance. 相似文献
5.
Y. A. Youssef 《Folia microbiologica》1974,19(5):381-385
The dominating rhizosphere fungi of broad bean (Vicia faba Linn.) variety “Giza 1”, and cotton (Gossypium barbadense Linn.) variety “Giza 47”, were grown in liquid medium. After 10 days, filtrates were obtained and sterilized by filtration through sintered-glass filter. Plants were grown in sterile sand which was supplemented with nutrient solution. Every plant was irrigated with fungal filtrate, unconsumed medium, and water. The filtrates of the rhizosphere fungi of both broad bean and cotton stimulated plant growth. 相似文献
6.
Youssef Dalia El-Bakatoushi Ranya Elframawy Asmaa El-Sadek Laila Badan Ghada El 《Journal of plant research》2023,136(3):305-322
Journal of Plant Research - The current study examined the phylogenetic pattern of medicinal species of the family Apiaceae based on flavonoid groups production, as well as the overall mechanism of... 相似文献
7.
Ahmed Youssef Moussa 《Journal of invertebrate pathology》1978,31(2):204-216
Reovirus particles were isolated from adults in laboratory colonies of the housefly, Musca domestica. These particles were spherical in outline, 57–76 nm in diameter, and were found only in hemocyte cytoplasm, where virions have been disclosed by a new technique. Virions were present in large numbers, and viral inclusion bodies were identified. The virus particles had pentagonal and hexagonal shapes resembling a simple icosahedral structure. The virus was shown to be infectious and pathogenic to adult flies through injection or by feeding them suspensions from flies that had died of the virus. Electron micrographs of midgut sections from infected flies showed that the midgut cells were packed with dark undulating threads which were not present in uninfected flies. However, no virus particles or inclusion bodies could be seen in these cells. On the basis of their association with infected flies, and the similarity to results from other studies on reoviruses and insect viruses, it is suggested that these threads are an alternative replicative form of the reovirus. When the virus suspensions from heavily infected flies were dialyzed against weak alkaline solutions, the threads showed an inner component of coiled material, 12 nm in diameter, inside an envelope with a diameter of 50–83 nm, mean 60.3 ± 7.5, composed of subunits 7–8 nm long and 7–8 nm across. 相似文献
8.
W.A. Schumacher T.E. Steinbacher S. Youssef M.L. Ogletree 《Prostaglandins & other lipid mediators》1992,44(5)
The effects of the novel TxA2/prostaglandin endoperoxide (TP) receptor antagonist BMS 180,291 on platelet reactivity was determined ex vivo in conscious African green monkeys. Platelet aggregation responses to U-46,619 were decreased 50% and 100% at 23 to 24 hrs after BMS 180,291 oral doses of 1 and 3 mg/kg, respectively. In addition to inhibiting aggregation, a 3 mg/kg oral dose of BMS 180,291 also produced an 11±3-fold shift to the right in the U-46,619 concentration-response relationship for platelet shape change at 24 hrs after dosing. When the 3 mg/kg oral dose was continued for 11 days, the shift in this concentration-response relationship increased to 26±10- and 93±30-fold at 24 hrs after the 8th and 11th doses, respectively. This progressive inhibition corresponds to 93±3 and 99±1% blockade of platelet TP-receptors responsible for shape change, respectively. Comparable levels of TP-receptor blockade have been previously correlated with antithrombotic and antiischemic activities of TP-receptor antagonists in vivo. Platelet reactivity to U-46,619 had completely recovered on the 7th day after the final dose of BMS 180,291, indicating effective elimination from the circulation over this interval. In separate experiments, a 3-mg/kg i.v. dose of BMS 180,291 produced only marginal and transient hemodynamic effects in anesthetized African green monkeys. Overall, these data demonstrate that BMS 180,291 given orally once a day produces a sustained and therapeutically-relevant level of TP-receptor antagonism. 相似文献
9.
Youssef Hatefi 《Journal of cellular biochemistry》1975,3(3):201-213
Energy conservation and uncoupling in mitochondria are examined in the light of three important new findings: (a) Studies with the photoaffinity-labeling uncoupler 2-azido-4-nitrophenol have shown that mitochondria contain a specific uncoupler binding site (apparently a polypeptide of Mr = 30,000 ± 10%). (b) This site fractionates into an enzyme complex (complex V), which is capable of oligomycin- and uncoupler-sensitive ATP-Pi exchange. It is absent from electron transfer complexes I, III, and IV, which represent segments of the respiratory chain containing coupling sites 1, 2, and 3, respectively. (c) Trinitrophenol is a membrane-impermeable uncoupler (uncouples submitochondrial particles, but not mitochondria) and a poor protonophore. There is an excellent correlation between the uncoupling potencies and the affinities of uncouplers for the mitochondrial uncoupler-binding site. There is no correlation between uncoupling potency and protonophoric activity of uncouplers when a membrane-permeable uncoupler is compared with a membrane-impermeable one. 相似文献
10.
Bouchra Benmansour Feriel Youssef Manel Ben Ali Bander Albogami Fehmi Boufahja 《Saudi Journal of Biological Sciences》2022,29(5):3610-3616
Between 2018 and 2020, 696 fish belonging to two species of sharks from the Family Triakidae (Mustelus mustelus and M. punctulatus) were collected from the coasts of Tunisia and inspected for parasites. Six copepod taxa (Perissopus dentatus Steenstrup & Lütken, 1861, Eudactylinella alba Wilson, 1932, Kroyeria lineata Van Beneden, 1853, Nesippus orientalis Heller, 1865 and Lernaeopoda galei Krøyer, 1837, Kroyeria sp.), four isopod species (Anilocra physodes (Linnaeus, 1758), Emetha audouini (H. Milne Edwards, 1840), Ceratothoa parallela (Otto, 1828) and Ceratothoa oestroides (Risso, 1816)) and two monogenean species (Erpocotyle sp1. And Erpocotyle sp2) were collected. A large number of global host records was reported, including the occurrence of E. audouini on M. mustelus and of Erpocotyle sp.2 on M. punctulatus. The study of the diversity of parasites per host species revealed that M. mustelus had a higher parasitic richness compared to M. punctulatus. In this study, it was provided for the first records on ectoparasites on Triakidae sharks from Tunisian coasts and their infection indices. 相似文献