Ahmed I. Gadallah

Protein synthesis by ribosomes from fertilized and unfertilized eggs of houseflies, Musca domestica

Abstract The ribosomes from unfertilized and fertilized housefly eggs have been isolated and their ability to initiate protein synthesis in a cell-free system has been investigated. There is a greater proportion of polymeric forms in the ribosomes from fertilized eggs, and these have a greater capacity to initiate protein synthesis.

Isolation and identification of egg ribosomes of the housefly, Musca domestica

Abstract Ribosomes from Musca domestica eggs have been isolated and studied. They exist in monomeric, dimeric, and polymeric forms and were identified by sucrose density-gradient separation and electron micrographs. Further studies showed that the ribosomes were sensitive to RNAse but not DNAse.

Characteristics of homologous and heterologous DNA-RNA hybrids from unfertilized and fertilized eggs of houseflies, Musca domestica☆

Abstract DNA and 14C-labelled RNA were isolated from fertilized and unfertilized eggs of houseflies (Musca domestica). The two forms of nucleic acid were obtained from newly oviposited eggs and from eggs which had been incubated for 6 hours at 37°C., corresponding to the late embryonic developmental period. RNA-denatured DNA hybrids were prepared by hybridization in solution and with the DNA immobilized on membrane filters. The degree of hybridization of homologous and heterologous forms was determined by assaying the 14C-labelled RNA incorporated into the RNA-DNA hybrids. When the hybrids were formed by homologous RNA-DNA the degrees of hybridization of the forms from newly oviposited eggs and from incubated eggs were similar. A small decrease of doubtful significance was noted when heterologous hybrids were prepared from the nucleic acids of newly oviposited fertilized and unfertilized eggs. However, when heterologous hybrids were prepared from newly oviposited unfertile eggs and incubated fertile eggs, the degree of hybridization was only about 75 per cent of that found with homologous hybrids. When the hybridization involved RNA or DNA from newly oviposited fertile eggs and DNA or RNA from incubated fertile eggs, the hybridization was about 85 per cent of that for homologous hybrids.

DNA-RNA hybrids from ovaries of normal and sterilized Musca domestica

Abstract DNA and C14-labelled RNA were isolated from normal and thiotepa-sterilized ovaries of houseflies (Musca domestica). The two forms of nucleic acid were obtained during different stages of oogenesis. RNA-DNA hybrids were prepared by hybridization of RNA with DNA immobilized on membrane filters. The degrees of hybridization of homologous and heterologous forms were determined by assaying the C14-labelled RNA incorporated into the RNA-DNA hybrids. The RNA from normal and sterilized fly ovaries hybridized with the homologous DNA to about the same degree. However, with heterologous hybrids, that is, RNA from one type of ovary and DNA from the other, there was a lesser degree of hybridization indicating that only a portion of the RNA was able to recognize complementary sites in the heterologous DNA.

Characteristics of nucleic acids from ovaries of virgin and mated houseflies, Musca domestica

Abstract Ribosomal RNA (rRNA) from ovaries of virgin and mated houseflies is composed of 27·2s, 17·4s, and 4·0s particles. Purine-pyrimidine ratios of rRNA synthesis and DNA-rRNA hybridization studies indicate that there are no changes in nucleotide sequences in the newly synthesized rRNA or DNA.

Changes in soluble protein, dehydrogenases, and esterases of unfertilized and fertilized eggs of Musca domestica

Abstract The proteins, including dehydrogenases and esterases, of fertilized and unfertilized housefly eggs have been studied by acrylamide gel electrophoresis and their enzymatic activities measured. A considerable increase in the activity of lactic acid dehydrogenase (LDH) and acetylcholinesterase (AchE) was evident during embryonic development in the fertilized eggs. When the crude protein extract from the unfertilized eggs was purified by DEAE cellulose column chromatography, the activity of LDH increased but the activity of AchE remained relatively the same. The activities of malic acid dehydrogenase (MDH) and glucose-6-phosphate dehydrogenase (G-6-PDH) were similar in fertilized and unfertilized eggs. At late embryogenesis, changes in protein patterns between fertilized and unfertilized eggs were barely detectable. During the period of development five LDH isoenzymes and six esterases were found in the fertilized eggs, whereas in the unfertilized eggs two LDH isoenzymes and four esterases were found. MDH and G-6-PDH isoenzyme bands were similar in both types of eggs with two distinct isoenzyme bands near the origin.

Amino acid incorporation by fig fruit ribosomes in a cell-free system☆

Abstract An amino acid-incorporating system from fig fruit tissue has been prepared and the requirements needed for such an activity were established. The pH 5 enzymes, prepared from the same tissue, successfully supported the incorporation of 14 C- l -phenylalanine by ribosomes. Puromycin and RNAse, but not DNAse, inhibited the protein synthesis activity. The addition of poly U increased the incorporation rate. A gradual increase in the rate of 14 C- l -phenylalanine incorporation began in the dimer (120 S) fraction and continued in the higher polysomal aggregates.

Characteristics of DNA-RNA hybrids prepared from the eggs of normal and thiotepa chemosterilized houseflies, Musca domestica L

Abstract DNA and 14 C-labeled RNA were isolated from the eggs of normal and thiotepa chemosterilized house flies. RNA-DNA hybrids were prepared by hybridization in solution and with the DNA immobilized on membrane filters. The degree of hybridization was determined by assaying the RNA- 14 C incorporated into the RNA-DNA hybrid. The RNA from normal or chemosterilized fly eggs hybridized with the homologous form of DNA to about the same degree. However, for heterologous hybrids with RNA from one type of egg and DNA from the other, the lesser degree of hybridization indicated that only a portion of the RNA was able to recognize complementary sites in the heterologous DNA. Therefore, as a result of aziridinyl chemosterilization of the adult houseflies, both the RNA and the DNA from the eggs were altered so that they were complementary to each other, but were complementary to only a limited degree to the RNA and DNA from normal eggs.

Effect of alkylating agents on transfer ribonucleic acid methylases of Musca domestica during oögenesis and embryogenesis

Abstract The transfer ribonucleic acid methylases ( t RNA) during the period of oogenesis and embrygenesis of Musca domestica , from normal and chemosterilized adult housefly has been studied. As shown by enzyme activity measurement, the rate of t RNA methylases activity was higher in normal tissues than it was in the chemosterilized one.