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41.
M A Khalifa 《Journal of biosocial science》1986,18(3):325-336
The population of Sudan (North) is at a very early stage of fertility transition and experiences high, stable fertility at a close to natural level. The high observed fertility is found to be a function of the high proportion of married women and ineffective contraceptive procedures. The data used in this study were drawn from the 1979 Sudan Fertility Survey (SUDFS), in which 3115 ever-married women 50 years old from 12,028 households were interviewed. 90% of Sudanese women breast fed for at least 6 months and 80% for at least 12. The main inhibitor of fertility is perceived to be lactational amenorrhea averaging about 11.8 months, which is reported to be high, although among younger women the duration of amenorrhea is shorter due to earlier introduction of supplementary foods. An average of 5.2 months of postpartum sexual abstinence is evidenced, but this is shorter than the period of amennorhea, and therefore has no effect on the birth interval. Neither does marital instability or mean length of separation, which are both close to nonexistent. Sudanese women are comparatively very infecund. 22% gave birth within the 1st year of marriage, 62% within the 2nd, and 83% the 3rd. The proportion of ever-users of contraception is high (e.g. 15.4% among the 25-34 among category), but current use was low (8.1% for the same). The use of contraception is responsible for a reduction of 4.2% of the fertility per married woman. The duration of temporary separation between spouses, due to temporary or seasonal migration of husbands, and the pathological causes of high primary sterility, which contribute to the low fecundability, need further investigation. 相似文献
42.
Sheep reticulocytes from phlebotomized animals have a total transferrin binding potential that may exceed by an order of magnitude the surface binding capacity. Steady state uptake of transferrin at 37 degrees C is generally less than 50% of the total transferrin binding capacity. During long-term incubation of the reticulocytes, all transferrin binding ability is lost, the ability to internalize being lost most rapidly. The loss in ability to bind transferrin during long-term incubation is independent of the number of surface transferrin binding sites, since removal of surface receptors with pronase does not affect the rate of loss of the internal pool of receptors during long-term incubation. Moreover, after removing surface receptors with pronase, only a fraction of the original number of receptors is restored to the surface, despite the presence of a large pool of internal receptors. These data suggest that only a fraction of the internal pool of receptors is capable of recycling to the cell surface in sheep reticulocytes. 相似文献
43.
The new triterpene 3α,11α-dihydroxy-23-oxo-lup-20(29)-en-28-oic acid was isolated from Acanthopanax trifoliatus. Its structure has been determined on the basis of spectroscopic data and chemical transformations. 相似文献
44.
F M Diab H Hoogstraal H Y Wassef M S Al Khalifa N A Al Asgah 《The Journal of parasitology》1985,71(5):630-634
Nymphal and larval Hyalomma (Hyalommina) arabica Pegram, Hoogstraal, and Wassef, 1982, described herein, closely resemble those of Hyalomma (Hyalommina) rhipicephaloides Neumann, differing chiefly in body size (both stages), nymphal basis capituli and scutal proportional dimensions, and distinctness of larval coxal spurs. Females of these species are also structurally similar but males differ in major critical characters. Nymphs and larvae of both species parasitize the spiny mouse (Acomys spp.), but immatures of the third African- Arabian species of this subgenus, Hyalomma (Hyalommina) punt Hoogstraal, Kaiser, and Pedersen, are unknown. Hyalomma (Hyalommina) arabica occurs in valleys and hills of western Saudi Arabia and western Yemen; H. (H.) rhipicephaloides in the Red Sea and Dead Sea areas; and H. (H.) punt in northeastern Somalia and eastern Ethiopia. The ibex (Capra ibex nubiana Cuvier) is probably the original host of adult H. (H.) arabica and H. (H.) rhipicephaloides; the related domestic goat is an important host of adults of the 3 species, which also parasitize domestic sheep. Gazelles are recorded hosts of adults of H. (H.) rhipicephaloides and H. (H.) punt and the latter is also recorded from goats, sheep, camels and cattle. 相似文献
45.
J Marichy A Adam J Damas J Lecomte 《Comptes rendus des séances de la Société de biologie et de ses filiales》1985,179(6):748-751
Blister fluids removed from benign cutaneous burns contain the components of the prekallikrein-kininogens system in a non activated state. Their occurrence in the fluids is explained by a diffusion from the blood plasma. 相似文献
46.
Total cellular calcium content (determined by atomic absorption spectrometry) of Rat-1 cells transformed by temperature-sensitive Rous sarcoma virus decreases with cell density, but is found not significantly different at permissive and at non-permissive temperature. Kinetic analysis of 45Ca efflux from preloaded cells exhibits three separable pools of exchangeable calcium. The ratio of pool size of the fast-exchanging Ca-compartment (bound to cell surface) to pool size of the intermediate Ca-compartment (cytoplasmic) was found to decrease from 2.5 to 1.3 upon shift from non-permissive to permissive temperature. The slowly exchanging Ca-pool (presumably mitochondrial) did not change significantly upon temperature shift. These and further data demonstrate a close correlation between distribution of cellular Ca among different cellular compartments and characteristics of cellular proliferation, both attributable to the function(s) of a single oncogene. 相似文献
47.
mRNA polyadenylate-binding protein: gene isolation and sequencing and identification of a ribonucleoprotein consensus sequence. 总被引:111,自引:30,他引:81 下载免费PDF全文
S A Adam T Nakagawa M S Swanson T K Woodruff G Dreyfuss 《Molecular and cellular biology》1986,6(8):2932-2943
We identified and produced antibodies to the major proteins that interact with poly(A)+ RNAs in the yeast Saccharomyces cerevisiae. The major proteins which were cross-linked by UV light to poly(A)+ RNA in intact yeast cells had apparent molecular weights of 72,000, 60,000, and 50,000. The poly(A) segment of the RNA was selectively cross-linked to the 72,000-molecular-weight protein (72K protein). Mice immunized with purified UV-cross-linked RNA-protein (RNP) complexes produced antibodies to the three major RNP proteins. A yeast genomic DNA library constructed in the lambda gt11 expression vector was screened with the anti-RNP serum, and recombinant bacteriophage clones were isolated. One recombinant phage, lambda YPA72.1, bearing a 2.5-kilobase insert, produced a large beta-galactosidase-RNP fusion protein. Affinity-selected antibodies from the anti-RNP serum on this fusion protein recognized a single 72K protein which was cross-linked to the poly(A) segment of RNA in the intact cell. Furthermore, the fusion protein of lambda YPA72.1 had specific poly(A)-binding activity. Therefore, lambda YPA72.1 encodes the 72K poly(A)-binding protein. Immunofluorescence microscopy showed that this protein was localized in the cytoplasm. Hybrid-selected mRNA translated in vitro produced the 72K poly(A)-binding protein, and mRNA blot analysis detected a single 2.1-kilobase mRNA. DNA blot analysis suggested a single gene for the poly(A)-binding protein. DNA sequence analysis of genomic clones spanning the entire gene revealed a long open reading frame encoding a 64,272-molecular-weight protein with several distinct domains and repeating structural elements. A sequence of 11 to 13 amino acids is repeated three times in this protein. Strikingly, this repeated sequence (RNP consensus sequence) is highly homologous to a sequence that is repeated twice in a major mammalian heterogeneous nuclear RNP protein, A1. The conservation of the repetitive RNP consensus sequence suggests an important function and a common evolutionary origin for messenger RNP and heterogeneous nuclear RNP proteins. 相似文献
48.
NMR, CD and IR spectroscopies of a tridecanucleotide containing a no-base residue: coexistence of B and Z conformations. 总被引:3,自引:3,他引:0 下载免费PDF全文
S Pochet T Huynh-Dinh J M Neumann S Tran-Dinh S Adam J Taboury E Taillandier J Igolen 《Nucleic acids research》1986,14(2):1107-1126
The synthesis of the tridecadeoxynucleotide d(CGm5CGCGxACATGT), where x is the 1-cyano-2-deoxy-beta-D-erythropentofuranose, is described. The NMR, IR, CD studies at various salt concentrations and temperatures of this oligomer show that the B and Z conformations are simultaneously present in the same short DNA fragment. A single apurinic residue is sufficient for the coexistence of the B and Z helices on this oligomer. 相似文献
49.
Interaction of transition metal ions with Z form poly d(A-C).poly d(G-T) and poly d(A-T) studied by I.R. spectroscopy. 总被引:7,自引:6,他引:1 下载免费PDF全文
Interactions between Ni2+, Co2+ and purine bases have been studied by I.R. spectroscopy in the case of double stranded regularly alternating purine-pyrimidine polynucleotides poly d(A-T), poly d(A-C).poly d(G-T) and poly d(G-C). The spectra of polynucleotide films have been recorded in hydration and salt content conditions which correspond to the obtention of the classical right-handed (A,B) and left-handed (Z) helical conformations. Selective deuteration of the 8C site of purines has been obtained and is used to detect interactions between the transition metal ions and the adenine or guanine bases. The spectral region between 1500 and 1250 cm-1 corresponding to base in-plane vibrations and involving also the glycosidic linkage torsion is discussed in detail. The selective interaction between the transition metal ion and the 7N site of the purine base is considered to be partly responsible for the stabilization of the base in a syn conformation, which favours the adoption by the polynucleotide (poly d(G-C), poly d(A-C).poly d(G-T) or poly d(A-T)) of a Z type conformation. 相似文献
50.
Adam H. Arzt Wayne L. Silver J. Russell Mason Larry Clark 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1986,158(4):479-487
Summary Electro-olfactograms (EOGs) were used to assess olfactory responding by aquatic larval and terrestrial adult tiger salamanders (Ambystoma tigrinum) to airborne volatile compounds, and volatile and non-volatile compounds in aqueous solution. Both forms of salamander showed saturation effects to presentations of airborne stimuli (Fig. 2). Saturation was not observed, however, to stimulus presentations in aqueous solution (Figs. 2, 3). When threshold values and concentration-response curve parameters were compared, non-volatile amino acids in solution were more potent stimuli for larvae while airborne volatiles were more potent stimuli for adults (Tables 1, 2). We infer that metamorphosis in the tiger salamander is accompanied by changes in olfactory response characteristics, due possibly to changes in receptor population, changes in perireceptor properties (e.g. mucus) or to changes in stimulus access.Abbreviations
EOG
electro-olfactogram
-
PPM
(ppm) parts per million 相似文献