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1.
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.
Summary The N-metabolism ofArthrocnemum fruticosum (L.) Moq., growing in a saline area north-east of the Dead Sea in Jordan, was studied over its vegetative growth period from
March to September 1981. Plant and soil samples were taken at monthly intervals. Water content, Na+, K+, Cl−, NH
4
+
, NO
2
−
and NO
3
−
concentrations were determined in the soil extracts, and the same determinations plus ash weight, soluble carbohydrates,
proline, proteins andin vivo nitrate reductase in the plant roots and shoots.
Soil humidity decreased and salinity increased from March to August, with re-wetting occurring in late July. K+ and Cl− were much lower in the soils than Na+. Plant relative dry weight increased during summer due to the absorption of Na+ in addition to increased organic dry weight. The uptake of Na+ was not balanced by a similar uptake of Cl−.
Ammonium and nitrate decreased in soil and plants in parallel with increasing salinity. Nitrite was only found in the roots
and always in very low quantities. Proline was found only in March. The total soluble carbohydrates in the roots showed a
short increase in June when the sodium in the plants also increased. It was concluded that carbohydrates may be used to balance
osmotic shocks, but that another compatible compounds is necessary to maintatin long-term osmotic equilibrium.
The nitrate reductase activity, measuredin vivo, and the soluble protein changed roughly in parallel with the internal nitrate from May to August, suggesting that nitrogen
uptake and reduction in the plant is inhibited during summer when the soil is dry and very saline. This could be a direct
effect of drought and/or salinity on the plants, or an indirect onevia an inhibition of nitrifying bacteria. 相似文献
6.
Nabil N. Youssef Carl F. Roush William R. McManus 《Journal of invertebrate pathology》1984,43(1):11-20
First instar larvae of the leafcutting bee, Megachile rotundata, were fed on either artificial or natural provisions containing spores of Ascosphaera proliperda. Two isolates were used as a source of inocula: one originated from in vitro isolates obtained while culturing what was thought to be pure spores of A. aggregata, the second originated from in vitro cultures from Denmark. Histological and scanning electron microscopy studies revealed that the spores germinated in the gut lumen and the developing hyphae invaded all tissues, after which they penetrated through larval integument and began the sexual phase of the life cycle aerially. Virtually all fungus-exposed larvae developed symptoms of disease regardless of source of inoculum, type of provision, and spore dose (1.5 × 103 to 3 × 106) per insect. It was concluded that the fungus was pathogenic to the alfalfa leafcutting bee under laboratory conditions and future studies should be conducted to determine its etiology, cross infectivity, and natural distribution in other bee taxa. 相似文献
7.
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
8.
Citrus Tristeza Virus (CTV), usually occurs in nature as a mixture of genotypes. Six naturally infected citrus
(Citrus sinensis) trees grafted on sour orange rootstock were collected from three citrus growing governorates
in Egypt (Sharqia, Qalyubia and Garbia). In this study, RT-PCR, Single-Strand Conformation Polymorphism
(SSCP) and nucleotide sequence analysis were used for four independent CTV genomic regions (p65, p18,
p20, and p23) to detect and assess the sequence and genetic variabilities among CTV Egyptian isolates. RTPCR products (650 bp) for the CTV p23 gene obtained from the selected isolates were used for the SSCP analysis
and DNA sequencing. SSCP patterns of p23 gene for individual isolates yielded different complex haplotype patterns. Nucleotide sequence analysis of p23 region amplified from six isolates under study revealed that p23 shared
high nucleotide identity 98.7% with T36 isolate from USA, Florida. Phylogenetic analysis of p23 gene indicated a
close evolutionary relationship between all examined isolates and Qaha isolate (T36 isolate group), suggesting that
they may have originated from closely related ancestors. Nucleotide sequence analysis of the three genes located
on CTV 3′-coterminal overhang, p18, p20 and p65, amplified from isolate A3, Sharqia governorate, revealed that
the p18, p65, and p20 genes were related to the T3-KB isolate from South Africa with 99%–100% sequence
homology. Phylogenetic relationship analysis for p65, p18 and p20 ORFs clustered the current A3 isolate with
T3 genotype group. The recombination analysis identified three of six isolates from Sharqia, and Garbia as potential recombinant for p23 gene. The isolates T36 and T3 were identified as major donors for recombination events
in isolate A3. Our results concluded that p23 ORF likely to be as a hotspot region for recombination and originated through recombination event. The current study indicated that recombination is an important factor for the
origin of CTV strains in Egypt. 相似文献
9.
Tahsin Shoala Basma H. Amin Ismail A. S. Rashid Fayz A. Abdel-Rahman Mohamed E. Khalil Khamis Youssef 《Phyton》2023,92(4):1139-1152
Production of peaches (Prunus persica (L.) Batsch) for both local market and export is increasing each year in
Egypt. Brown rot disease, caused by Monilinia laxa and Monilinia fructigena, is considered one of the most
important postharvest rots affecting peaches in Egypt and economic losses are increasing. Antifungal activity
of glycyrrhizic acid nanoparticles (GA-NPs) and glycyrrhizic acid (GA) at 0.2 and 0.4 mmol/L was investigated
as a control for both these brown rot pathogens on peach fruits in both in vitro and in vivo studies. In the in vitro
studies, GA-NPs were the most effective as shown by the ability to decrease linear growth of both brown rot
pathogens in potato dextrose agar (PDA) amended with 0.4 mmol/L GA-NPs. Micrographs of M. fructigena
exposed to 0.4 mmol/LGA showed mycelial deformations, nodule formation, detachment of the cell wall, shrinkage and inhomogeneous cytoplasmic materials with large vacuoles. Mycelium of M. laxa exposed to 0.4 mmol/
LGA-NPs resulted in thinner and distorted hyphae, nodule formation, cell wall thinning, and swellings. The GANPs and GA treatments improved fruit quality by maintaining firmness and total soluble solids (TSS). GA-NPs
were more effective in decreasing decay incidence than their bulk material. The 0.4 mmol/L GA-NPs completely
inhibited the disease on naturally infected peach fruits for both seasons of 2018 and 2019. Furthermore,
0.4 mmol/L GA-NPs reduced the disease incidence in inoculated fruits by 95 (M. laxa) and 88% (M. fructigena)
in 2018 season and 96 (M. laxa) and 85% (M. fructigena) in 2019 season. In conclusion, GA-NPs could enhance
the resistance of peaches against brown rot caused by M. laxa and M. fructigena. 相似文献
10.
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