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1.
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
2.
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
3.
Interactions between crown-gall tumors on the primary pinto bean leaf and the pinto bean seedling (Phaseolus vulgaris L. ‘Pinto‘) were estimated by quantitative measurements of tumor initiation and growth as affected by certain modifications of the host. Effects of the tumors on the host were estimated by measurements of host growth and correlation responses. The presence of crown-gall tumors was found to reduce the growth of the leaf in area but to nearly double the weight of the leaf 9 days after inoculation with Agrobacterium tumefaciens (Smith and Town.) Conn, strain B6. The presence of tumors on only one of the two primary leaves resulted in a decrease in the weight of the leaf without tumors, showing the tumors to be effective mobilization centers. Tumors also delayed the abscission of petiole explants and delayed the growth of the epicotyl bud, both reminiscent of auxin effects. The excision of the cotyledons, the epicotyl bud, or one of the pair of primary leaves at the time of inoculation increased the number of tumors initiated per leaf. Removing the epicotyl bud or one of the primary leaves, or placing a cytokinin on one of the leaves, altered leaf growth but failed to alter tumor growth, indicating that tumor growth is not affected by the changes responsible for the compensatory growth effects induced by these treatments. Tumor growth was shown to be generally correlated with leaf growth from day 2 through 8 after inoculation, suggesting that the factors normally limiting leaf growth in a determinate type leaf are also active in limiting tumor growth. The changes in the plant cell responsible for the enhanced rate of growth seen in crown-gall tumor cells, therefore, appear to occur in regulatory systems other than those normally limiting leaf growth. The regulatory systems that are affected may be identical with those activated in compensatory host growth effects. 相似文献
4.
The present study was designed to investigate the potential protective effect of melatonin as an antioxidant separately or in combination with antigens (cercarial; CAP or soluble worm; SWAP) against Schistosoma mansoni infection in hamsters. Each hamster was sensitized with an initial immunization of 0.6 ml of the extracted antigen (30 μg protein/mL). After four days,a second injection of 0.4 mL was given (20 μg protein/mL). Then,each hamster was exposed to 260±20 S.mansoni cercariae followed with melatonin... 相似文献
5.
Mukhtar Ahmed Daoud Ali Abdel Halim Harrath Tajamul Hussain Nasser Al-Daghri Majed S. Alokail Ravindranath H. Aladakatti Mukhtar Ahmed G. Ghodesawar 《Comptes rendus biologies》2014,337(4):250-257
Boswellia papyrifera and Boswellia carterii diffuses smoke polluting air that adversely affects indoor environment that certainly harm human health. Therefore, this study aims at ascertaining the effect of these plants on gonadal hormones and molecular changes in rat spermatozoa. The animals were exposed to 4 g/kg body weight of B. papyrifera and B. carterii daily for 120 days along with suitable controls. Significant decreases in FSH, LH and testosterone levels were evidenced, along with a reduction of protein, sialic acid, and carnitine levels. In sperm physiology, sperm count, motility, speed decrease, whereas sperm anomalies increase. TEM observation indicates morphological changes in plasma and acrosomal membranes, cytoplasmic droplet in the tail region, vacuolated, and disorganization of the mitochondrial sheath. These findings demonstrate that B. papyrifera and B. carterii smoke affects the process of sperm formation and maturation, which indicates the detrimental effects of these plants on the reproductive system. 相似文献
6.
M A Khalifa 《Journal of biosocial science》1989,21(3):301-320
Using individual birth history data from the Sudan Fertility Survey, 1979, parity-related differences in fertility are demonstrated, as well as differences between socioeconomic groups. Rural women, women with no education and those married to uneducated husbands show rapid parity progression and its cumulative effects on fertility which are consistent over all birth intervals. Urban women, women with some education and those married to educated husbands, however, go rapidly through their second and third birth intervals and then more slowly at higher parities. A limitation of the study was the inability to control fully for the effects of breast-feeding and contraception. There is evidence for a reduction in high parity births, starting in the 1970s. 相似文献
7.
Marcela Herrera Shannon G. Klein Sebastian Schmidt‐Roach Sara Campana Maha J. Cziesielski Jit Ern Chen Carlos M. Duarte Manuel Aranda 《Global Change Biology》2020,26(10):5539-5553
Enhancing the resilience of corals to rising temperatures is now a matter of urgency, leading to growing efforts to explore the use of heat tolerant symbiont species to improve their thermal resilience. The notion that adaptive traits can be retained by transferring the symbionts alone, however, challenges the holobiont concept, a fundamental paradigm in coral research. Holobiont traits are products of a specific community (holobiont) and all its co‐evolutionary and local adaptations, which might limit the retention or transference of holobiont traits by exchanging only one partner. Here we evaluate how interchanging partners affect the short‐ and long‐term performance of holobionts under heat stress using clonal lineages of the cnidarian model system Aiptasia (host and Symbiodiniaceae strains) originating from distinct thermal environments. Our results show that holobionts from more thermally variable environments have higher plasticity to heat stress, but this resilience could not be transferred to other host genotypes through the exchange of symbionts. Importantly, our findings highlight the role of the host in determining holobiont productivity in response to thermal stress and indicate that local adaptations of holobionts will likely limit the efficacy of interchanging unfamiliar compartments to enhance thermal tolerance. 相似文献
8.
Noura Hamed Khalifa Al Shaqsi Horiya Ali Said Al Hoqani Mohammad Amzad Hossain Mohammed Abdullah Al Sibani 《Biochemistry and Biophysics Reports》2020
Chitin is an organic polymer and it is the most frequent marine natural polysaccharide after cellulose. The main natural sources of chitin are exoskeletons of insects, mollusks, the cell walls of certain fungi and crustaceans such as crabs, shrimps and lobsters. The waste of these marine exoskeletons are pollutant for the environment, but these waste raw materials could be useful for production of commercial products like chitin. Chitin is an important raw material used for water treatment, agricultural, biomedical, biotechnological purposes, food and paper industry and cosmetics. Based on the variety of importance, the present targets of this study are to optimize the demineralization process for the removal of calcium and phosphate contents from the waste of Portunidae segnis (P. segnis) by using acid at ambient temperature and to characterize the isolated demineralized sample as well as the percentage of remaining calcium and phosphorus contents by using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). The prepared waste carbs coarse powder samples of P. segnis were demineralized with seven different concentrations of hydrochloric acid at ambient temperature for 1 h. All the demineralization samples by the different concentrations were analyzed by using sensitive ICP-OES. The results based on ICP-OES showed that among the seven different concentrations used in the demineralization process for the isolation of chitin, the best was 2 M of HCl concentration for the production of chitin. The results also showed that the optimized concentration 2 M HCl gave the minimum concentration of calcium and phosphorus compared to other concentrations applied in this experiment. In conclusion, the optimized concentration for demineralization process could be used commercially for the isolation or commercial production of chitin for agricultural, biomedical and biotechnological purposes. 相似文献
9.
Chunmei Li Eliane Beauregard-Lacroix Christine Kondratev Justine Rousseau Ah Jung Heo Katherine Neas Brett H. Graham Jill A. Rosenfeld Carlos A. Bacino Matias Wagner Maren Wenzel Fuad Al Mutairi Hamad Al Deiab Joseph G. Gleeson Valentina Stanley Maha S. Zaki Yong Tae Kwon Michel R. Leroux Philippe M. Campeau 《American journal of human genetics》2021,108(1):134-147
10.
Bacopa monnieri (Linn.) Wettst. commonly known as waterhyssop, Brahmi plant, traditionally used for memory enhancement, nerve tonic, epilepsy, central nervous system (CNS), antidepressant, anxiety, blood pressure and antioxidant activities. Due to pharmaceutical demands its lost natural habitat. At this juncture we describe a resourceful protocol for micropropagation of water hyssop plant. Surface sterilized leaf and nodal explants were inoculated on basal MS semi-solid medium added with PGRs; auxins, cytokinins. Highest calli formation from leaf explants was obtained on NAA (2.5 mg−1) and showed (94.22%) accompanied via 2,4-D showed (2.5 mg−1; 82.43%), maximum calli formation in nodal explants was obtained on 2,4-D showed (2.5 mg−1; 71.14%) followed by NAA (2.5 mg−1) showed (62.15%), in internodes explants uppermost calli formation was obtained from 2,4-D showed (2.5 mg−1; 65.21%) followed by NAA (2.5 mg−1) showed (52.14%). The maximum somatic embryogenic callus, calli induction and formation (84%) was observed on 2,4-D + KIN (2.0 + 1.5 mg−1) amended solid medium. Uppermost shoot formation was observed in combination of IAA + BAP (1.0 + 1.0 mg−1) showed (78.54%) shoot formation followed by IBA (2.0 mg−1) alone showed (75.37%). The maximum shoot elongation was noticed from NAA + BAP (3.0 + 3.0 mg−1) with 21.21 cm followed by NAA (2.0 mg−1) showed (15.22 cm) although, chief root formation was obtained from IBA (2.0 mg−1) with 83.75% root formation along higher number of roots (47.43%) per shoot. Followed by IAA (2.0 mg−1) showed root induction (73.43%) and no of roots (38.54%) per shoot. In hardening under pot condition plants survivability (100%) was observed under glass house conditions, the present in vitro PTC techniques is extremely significant to gratifying its natural conservation. 相似文献