In order to understand the transmission mechanism of West Nile virus(WNv)in birds(especially crows)and mosquitoes populations,this paper extends the traditional ordinary differential model of WNv to a reaction-diffusi...In order to understand the transmission mechanism of West Nile virus(WNv)in birds(especially crows)and mosquitoes populations,this paper extends the traditional ordinary differential model of WNv to a reaction-diffusion system with more complex cross-diffusion.We explore the relationship between the basic reproduction number and cross-diffusion coefficients involving various parameters,and investigate the effect of vertical transmission of the virus on the transmission mechanism.We use the method of upper and lower solutions to investigate the existence of the coexistence solutions.The theoretical analysis and numerical simulation show that the WNv carried by birds and mosquitoes will coexist when the low-risk threshold R0*≥1,which is a disadvantage to the prevention and control of this virus,and disappear when the high-risk threshold R*0≤1,which is an advantage to that.展开更多
Organic luminophores with superior solid-state luminescence are urgently required in various fields,such as lighting,display,sensing,and solar energy conversion.However,to achieve their highly efficient luminescence s...Organic luminophores with superior solid-state luminescence are urgently required in various fields,such as lighting,display,sensing,and solar energy conversion.However,to achieve their highly efficient luminescence still remains a challenge.Herein,a newly designed Nile red derivative,Nile-DPA-VB,is successfully obtained to exhibit aggregation-induced emission characteristics with the photoluminescent quantum yield(PLQY)of 11.45%.Such PLQY could be further promoted to 53.45%when Nile-DPA-VB is polymerized undergoing precipitation polymerization process,where the confined aggregation microenvironment severely restricts the intramolecular motions of Nile-DPA-VB.Remarkably,Nile-DPA-VB is ultrasensitive to the polarity and steric effect,enabling the real-time monitoring of aggregation microenvironment evolution for precipitation polymerization.The microphase separation and dynamic hardening for the nucleation and growth processes are visually demonstrated,which contribute dominantly to the high-efficiency luminescence.Finally,by doping the as-prepared fluorescent polymeric particles into polymethyl methacrylate,functional films with high luminescence and high haze are achieved to show the potential in lighting.These findings clearly demonstrate the significant role of polymerization in constructing high-efficiency solid-state luminescent materials for practice.展开更多
The NEW GIFT Nile tilapia （Oreochromis niloticus niloticus L.） is a nationally certificated new strain selected over 14 years and 9 generations from the base strain of GIFT Nile tilapia, introduced in 1994. This new...The NEW GIFT Nile tilapia （Oreochromis niloticus niloticus L.） is a nationally certificated new strain selected over 14 years and 9 generations from the base strain of GIFT Nile tilapia, introduced in 1994. This new variety has been extended in most of areas of China. The management of genetically improved strains, including the genetic markers for identification is needed urgently. RAPD analysis was conducted and their conversion to SCAR markers was developed. From NEW GIFT Nile tilapia, two strain-specific RAPD bands, S304624 bp and S36568 bp were identified. The strain-specific RAPD bands were gel-purified, cloned, and sequenced. Locus-specific primers were then designed to amplify the strain-specific bands. PCR amplification was conducted to test the variations in allele frequencies of two converted SCAR markers among the NEW GIFT Nile tilapia and its base strains, as well as 7 additional farmed strains worldwide. The frequency of SCAR marker Ⅰ （553 bp） was 85.7% in NEW GIFT Nile tilapia, but 16.7% in the base strain. The frequency of SCAR marker Ⅱ （558 bp） was 91.4% in NEW GIFT Nile tilapia, but 0% 70% in the 7 other strains. In order to confirm the utility of these two markers, an examination was conducted for a wild population from Egypt, resulted the frequency of SCAR Ⅰ and Ⅱ was 10% and 70%, respectively, much lower than that of New GIFT strain. The increase in allele frequency of these two SCAR markers suggests that these markers might be genetically linked to the quantitative trait loci （QTL） underlining the performance traits by long term selection, and indicate the bright potential of SCAR marker technology for tracking generations during selection progress and for distinguishing among genetically improved strain and other strains.展开更多
River Nile is one of the longest transboundery rivers and it is shared and used by Burundi,Democratic Republic of Congo,Egypt,Ethiopia,Eritrea,Kenya,Rwanda,Sudan,Tanzania and Uganda.As of today,the Nile is a crucial r...River Nile is one of the longest transboundery rivers and it is shared and used by Burundi,Democratic Republic of Congo,Egypt,Ethiopia,Eritrea,Kenya,Rwanda,Sudan,Tanzania and Uganda.As of today,the Nile is a crucial resource for the economic development of the Nile Basin countries and a vital source of livelihood for 160 million inhabitants as well as 300 million people living in the 10 riparian countries.The Nile Basin Initiative(NBI) is one of the international cooperative river basin management program and regional partnership where all the Nile Basin countries except Eritrea unite to pursue long-term sustainable development,improved land use practices and management.This review therefore focused on the challenges not faced on NBI in terms of integrated use of the river and conducted analysis of strengths,weaknesses,opportunities and threats(SWOT) based on secondary data.The result of the review revealed that for decades,the Nile Basin people have been facing many complex environmental,social,economic and political challenges that have made it difficult for the proper management and sustainability of Nile water.The initiative provides training to develop skills in government ministries,non-governmental organizations and local communities in each country.It is also working to raise awareness of critical environmental issues by strengthening networks of environmental education practitioners;developing curriculum in the education sector.The challenges of NBI include the involvement and funding of World Bank,lack of sufficient staff,procedural and policies conflicts,lack of coordination and linkage with other regional institutions and lack of recognition as river basin organization.Considering the complex nature of the project,it is recommended that the NBI should come up with a strong multi-disciplinary monitoring and evaluation team to follow up all implemented projects.The NBI should carry out participatory land use planning in communities along the river basin.Moreover,livelihood analysis should be carried out especially in communities along the Nile to come up with poverty eradication projects which are socially acceptable,applicable,economically viable and affordable.展开更多
Water quality of the river Nile and trace elements of the water, sediments and fish tissues were investigated in the current work. Eighteen different sampling points were selected along the whole course of the River N...Water quality of the river Nile and trace elements of the water, sediments and fish tissues were investigated in the current work. Eighteen different sampling points were selected along the whole course of the River Nile from its spring at Aswan to its estuaries at Rosetta and Damietta. Higher mean value of conductivity, alkalinity, chemical oxygen demand (COD), total organic carbon (TOC), ammonia (NH3), nitrate (NO3), total solid (TS), sulphate (SO4), chloride (Cl), orthophosphate were recorded in the water of Damietta and Rosetta branches comparing to other sites. Also trace metals in the water, sediments and tissues of Clarias gariepinus increased significantly (P Fe > Cu > Pb > Mn > Cr> Cd > Hg. In the gill tissues theses metals were accumulated in the following order Fe > Zn > Mn > Pb > Cr > Cu > Cd> Hg. The low accumulation of metals in muscle may be due to lack of binding affinity of these metals with the proteins of muscle. This is particularly important because muscles contribute the greatest mass of the flesh that is consumed as food.展开更多
Objectives The main objective of the present article is to assess and evaluate the characteristics of the Nile water system , and identify the major sources of pollution and its environmental and health consequences. ...Objectives The main objective of the present article is to assess and evaluate the characteristics of the Nile water system , and identify the major sources of pollution and its environmental and health consequences. The article is also aimed to highlight the importance of water management via re-use and recycle of treated effluents for industrial purpose and for cultivation of desert land. Method An intensive effort was made by the authors to collect, assess and compile the available data about the River Nile. Physico-chemical analyses were conducted to check the validity of the collected data. For the determination of micro-pollutants, Gas Chromatography (GC) and High Performance Liquid Chromatography (HPLC) were used. Heavy metals were also determined to investigate the level of industrial pollution in the river system. Results The available data revealed that the river receives a large quantity of industrial, agriculture and domestic wastewater. It is worth mentioning that the river is still able to recover in virtually all the locations, with very little exception. This is due to the high dilution ratio. The collected data confirmed the presence of high concentrations of chromium and manganese in all sediment samples. The residues of organo-chlorine insecticides were detected in virtually all locations. However, the levels of such residues are usually below the limit set by the WHO for use as drinking water. The most polluted lakes are Lake Maryut and Lake Manzala. Groundwater pollution is closely related to adjacent (polluted) surface waters. High concentrations of nutrients, E.coli, sulfur, heavy metals, etc. have been observed in the shallow groundwater, largely surpassing WHO standards for drinking water use. Conclusion A regular and continuous monitoring scheme shall be developed for the River Nile system. The environmental law shall be enforced to prohibit the discharge of wastewater (agricultural, domestic or industrial) to River Nile system.展开更多
The quality of a water body is usually characterized by sets of physical, chemical, and biological parameters, which are mutually interrelated. Since August 1997, monthly records of 33 parameters, monitored at 102 loc...The quality of a water body is usually characterized by sets of physical, chemical, and biological parameters, which are mutually interrelated. Since August 1997, monthly records of 33 parameters, monitored at 102 locations on the Nile Delta drainage system, are stored in a National Database operated by the Drainage Research Institute (DRI). Correlation patterns may be found between water quantity and water quality parameters at the same location, or among water quality parameters within a monitoring location or among locations. Serial correlation is also detected in water quality variables. Through the investigation of the level of information redundancy, assessment and redesign of water quality monitoring network aim to improve the overall network efficiency and cost effectiveness. In this study, the potential of the Artificial Neural Network (ANN) on simulating interrelation between water quality parameters is examined. Several ANN inputs, structures and training possibilities are assessed and the best ANN model and modeling procedure is selected. The prediction capabilities of the ANN are compared with the linear regression models with autocorrelated residuals, usually used for this purpose. It is concluded that the ANN models are more accurate than the linear regression models having the same inputs and output.展开更多
Urban sprawl is threatening the limited highly fertile land in the Nile delta of Egypt. Landsat TM satellite images of 1984, 1992 and ETM+ of 2006 have been used to study the impact of urban sprawl on agricultural lan...Urban sprawl is threatening the limited highly fertile land in the Nile delta of Egypt. Landsat TM satellite images of 1984, 1992 and ETM+ of 2006 have been used to study the impact of urban sprawl on agricultural land of the Northern Nile delta, Egypt. Visual interpretation using on screen digitizing and change detection techniques were applied for monitoring the urban sprawl. Combining the land capability map and the urban thematic layer using GIS made it possible to point out the risk of urban expansion on the expense of the highly capable soil class. The results show that a total expansion of urban area amounted to 689.20 km2(6.3% of total area) during the study period 1984–2006. The urban expansion during the 1984–2006 was on the expense of the most fertile soils where, the high capable soils(Class I) lost 247.14 km2(2.26 % of total area) and the moderate capable soils lost 32.73 km2(0.3% of total area), while the low capable soils lost only 57.39 km2(0.53% of total area). The urban encroachment over the non capable soils was very limited during the study period 1984–1992, where 7.33 km2 only was lost. The pattern of urban sprawl has been changed during the 1992 to 2006 whereas much larger area(50.64 km2) of the non capable soils was converted to urban. It can be concluded that the urban sprawl is one of the dominant degradation process on the land of Nile Delta.展开更多
An 8-week feeding experiment was performed to evaluate the effect of dietary genistein on growth performance,body composition,and digestive enzymes activity of juvenile Nile tilapia(Oreochromis niloticus).Four isonitr...An 8-week feeding experiment was performed to evaluate the effect of dietary genistein on growth performance,body composition,and digestive enzymes activity of juvenile Nile tilapia(Oreochromis niloticus).Four isonitrogenous and isoenergetic diets were formulated containing four graded supplements of genistein:0,30,300,and 3 000 μg/g.Each diet was randomly assigned in triplicate to tanks stocked with 15 juvenile tilapia(10.47±1.24 g).The results show that 30 and 300 μg/gdietary genistein had no significant effect on growth performance of Nile tilapia,but the higher level of genistein(3 000 μg/g)significantly depressed the final body weight and specific growth rate.There was no significant difference in survival rate,feed intake,feed efficiency ratio or whole body composition among all dietary treatments.An assay of digestive enzymes showed that the diet containing 3 000 μg/ggenistein decreased stomach and hepatopancreas protease activity,and amylase activity in the liver and intestine,while a dietary level of300 μg/g genistein depressed stomach protease and intestine amylase activities.However,no significant difference in stomach amylase activity was found among dietary treatments.Overall,the results of the present study indicate that a high level of dietary genistein(3 000 μg/g,or above) would significantly reduce the growth of Nile tilapia,partly because of its inhibitory effect on the activity of major digestive enzymes.Accordingly,the detrimental effects of genistein,as found in soybean products,should not be ignored when applied as an alternative ingredient source in aquaculture.展开更多
Spermatogenesis is a complex process in which spermatogonial stem cells differentiate and develop into mature spermatozoa.The transcriptional regulatory network involved in fish spermatogenesis remains poorly understo...Spermatogenesis is a complex process in which spermatogonial stem cells differentiate and develop into mature spermatozoa.The transcriptional regulatory network involved in fish spermatogenesis remains poorly understood.Here,we demonstrate in Nile tilapia that the Sox transcription factor family member Sox30 is specifically expressed in the testes and mainly localizes to spermatocytes and spermatids.CRISPR/Cas9-mediated sox30 mutation results in abnormal spermiogenesis,reduction of sperm motility,and male subfertility.Comparative transcriptome analysis shows that sox30 mutation alters the expression of genes involved in spermatogenesis.Further chromatin immunoprecipitation followed by high-throughput sequencing(Ch IP-seq),Ch IP-PCR,and luciferase reporter assays revealed that Sox30 positively regulates the transcription of ift140 and ptprb,two genes involved in spermiogenesis,by directly binding to their promoters.Our data,taken together,indicate that Sox30 plays an essential role in Nile tilapia spermatogenesis by directly regulating the transcription of the spermiogenesis-related genes ift140 and ptprb.展开更多
West Nile virus(WNV), a flavivirus of the Flaviviridae family, is maintained in nature in an enzootic transmission cycle between avian hosts and ornithophilic mosquito vectors, although the virus occasionally infects ...West Nile virus(WNV), a flavivirus of the Flaviviridae family, is maintained in nature in an enzootic transmission cycle between avian hosts and ornithophilic mosquito vectors, although the virus occasionally infects other vertebrates. WNV causes sporadic disease outbreaks in horses and humans, which may result in febrile illness, meningitis, encephalitis and flaccid paralysis. Until recently, its medical and veterinary health concern was relatively low; however, the number, frequency and severity of outbreaks with neurological consequences in humans and horses have lately increased in Europe and the Mediterranean basin. Since its introduction in the Americas, the virus spread across the continent with worrisome consequences in bird mortality and a considerable number of outbreaks among humans and horses, which have resulted in the largest epidemics of neuroinvasive WNV disease ever documented. Surprisingly, its incidence in human and animal health is very different in Central and South America, and the reasons for it are not yet understood. Even though great advances have been obtained lately regarding WNV infection, and although efficient equine vaccines are available, no specific treatments or vaccines for humanuse are on the market. This review updates the most recent investigations in different aspects of WNV life cycle: molecular virology, transmission dynamics, host range, clinical presentations, epidemiology, ecology, diagnosis, control, and prevention, and highlights some aspects that certainly require further research.展开更多
Objective:To evaluate the prevalence of West Nile virus seropositivity in the general population of Mashhad.Northeast of Iran.Methods:One hundred and eighty two individuals living in the city of Mashhad were studied u...Objective:To evaluate the prevalence of West Nile virus seropositivity in the general population of Mashhad.Northeast of Iran.Methods:One hundred and eighty two individuals living in the city of Mashhad were studied using cluster sampling method.Both IgM and IgG antibodies against WNV were detected by ELISA method.Results:In this study,the overall IgG seroprevalence of positive West Nile virus was 11%;however.IgM antibody was not found in the participants.Conclusions:Our study suggested that the prevalence rate of West virus is considerable in Mashhad city.It seems necessary for clinicians and health care workers to be aware of WNV infection in the Northeast Iran.展开更多
The present study was conducted to evaluate the effect of baker yeast, Saccharomyces cerevisiae （SC） and exogenous digestive enzymes （pepsin, papain and a-amylase, EDE） dietary supplementation on growth performanc...The present study was conducted to evaluate the effect of baker yeast, Saccharomyces cerevisiae （SC） and exogenous digestive enzymes （pepsin, papain and a-amylase, EDE） dietary supplementation on growth performance, feed utilization and hematological indices of Nile tilapia, Oreochromis niloticus fingerlings. A total of 630 Nile tilapia fingerlings with an average body weight of 26.4 ± 0.2 g were divided in the seven experimental net-pen treatments （three replicates each）. The experiment was conducted for 119 days. Seven isonitrogenous （26.50%） digestible protein and isocaloric （13.40 MJ kgl） digestible energy experimental diets were formulated. The control diet had no SC and EDE added. Diets 2-3 each contained SC at levels of 2 and 4 g 100 g diet-t, respectively, while diets 4-5 each contained EDE at levels of （0.64, 1.28, 0.16） and （1.28, 2.56, 0.32） g 100 gdiefI of pepsin, papain and a-amylase, respectively. Diet 6 contained mixture of SC and EDE at levels of 1 g yeast and 0.32, 0.64, 0.08 g of pepsin, papain and a-amylase, respectively 100 gdiet1 and diet D7 contained 2 g yeast and 0.64, 1.28, 0.16 g of pepsin, papain and a-amylase, respectively 100 g dietl. Growth performance and feed utilization efficiency of Nile tilapia were significantly （P 〈 0.05） higher in all treatments receiving SC and/or EDE supplemented-diets than the control diet which suggests that the addition of SC and EDE enhanced the growth performance. Red blood cells counts, hematocrit and hemoglobin were significantly （P 〈 0.05） highest in all treatments receiving mixture of SC and EDE supplemented-diets （D6 ＋ D7）. The same trend was observed for total plasma protein and total plasma globulin levels. The results of present study suggested that Nile tilapia fingerlings fed diets containing the mixture of I g yeast, SC and 0.32, 0.64, 0.08 g of pepsin, papain and a-amylase, respectively 100 gdiet^-1, for 119 days had enhanced growth performance, diet utilization efficiency and hematological indices.展开更多
There is considerable concern that isoflavones,such as genistein in fish feed composed of soybean protein,affects somatic growth in fish.Our previous works demonstrated that 30 and 300 μg/g dietary genistein had no s...There is considerable concern that isoflavones,such as genistein in fish feed composed of soybean protein,affects somatic growth in fish.Our previous works demonstrated that 30 and 300 μg/g dietary genistein had no significant effect on growth performance in Nile tilapia(Oreochromis niloticus),but the higher level of genistein(3 000 μg/g) significantly depressed growth.This study was conducted to further examine the effects of dietary genistein on the endocrine disruption on growth hormone/insulin-like growth factor-I(GH/IGF-I) axis in Nile tilapia(O.niloticus).Juvenile fish were fed by hand twice daily to satiation with one of four isonitrogenous and isoenergetic diets,each containing either 0,30,300 or3 000 μg/g genistein.Following an 8-week feeding period,plasma GH and IGF-I levels were investigated by radioimmunoassay and gene expression levels of gh,ghrelin,gnrhs,ghr,npy,npyrs,pacap,ghrs,igf-I,igf-Ir,and igfbp3 were examined by real-time PCR.The results show that no significant change in plasma GH and IGF-I levels in fish fed with diets containing 30 μg/gand 300 μg/g genistein.mRNA expression of genes along the GH/IGF-I axis remained unaffected,except for igf-Ir,which was stimulated by the 300 μg/g genistein diet.While in fish fed the 3 000 μg/g genistein diet,the plasma GH and IGF-I levels decreased,and mRNA expression of gh,ghr2,npyr1,igf-I,and igf-Ir were also significantly depressed.In contrast,npy and igfbp3 mRNA expression were enhanced.This study provides convincing evidence for growth impediment by genistein by disturbing the GH/IGF-I axis in Nile tilapia O.niloticus.展开更多
The efficacy of Endocrine Disrupting Compounds (EDCs), 17β-estradiol was tested on the fish Oreochromis niloticus in order to understand the intersex relationship of fish, in which sequential hermaphrodism can consis...The efficacy of Endocrine Disrupting Compounds (EDCs), 17β-estradiol was tested on the fish Oreochromis niloticus in order to understand the intersex relationship of fish, in which sequential hermaphrodism can consist of a male changing into a female (protandry) or a female changing into a male (protogyny). The fish were equally divided into 3 groups. The first group was the control group;the second and third groups were treated with 10 and 100 mg L-1 of 17β-estradiol, respectively, for 30 days. The overall result in this experiment had no significant effect on the growth parameters. Among the two treated groups, the low concentration group shows results similar to those of the control groups. The high concentration group shows changes to the male reproductive system with the appearance of the testis-ova present resulting in an intersex condition of the male gonads. With this experiment, it can be concluded that 17β-estradiol at high concentration reveals positive changes towards the male reproductive system of the fish, Oreochromis niloticus.展开更多
Flaviviral NS2B is a required cofactor for NS3 serine protease activity and plays an important role in promoting functional NS2B-NS3 protease configuration and maintaining critical interactions with protease catalysis...Flaviviral NS2B is a required cofactor for NS3 serine protease activity and plays an important role in promoting functional NS2B-NS3 protease configuration and maintaining critical interactions with protease catalysis substrates. The residues D80DDG in West Nile virus (WNV) NS2B are important for protease activity. To investigate the effects of D80DDG in NS2B on protease activity and viral replication, the negatively charged region D80DD and the conserved residue G83 of NS2B were mutated (D80DD/E80EE, D80DD/K80KK, D80DD/A80AA, G83F, G83S, G83D, G83K, and G83A), and NS3 D75A was designated as the negative control. The effects of the mutations on NS2B-NS3 activity, viral translation, and viral RNA replication were analyzed using kinetic analysis of site-directed enzymes and a transient replicon assay. All substitutions resulted in significantly decreased enzyme activity and blocked RNA replication. The negative charge of D80DD is not important for maintaining NS2B function, but side chain changes in G83 have dramatic effects on protease activity and RNA replication. These results demonstrate that NS2B is important for viral replication and that D80DD and G83 substitutions prevent replication; they will be useful for understanding the relationship between NS2B and NS3.展开更多
This study was undertaken to apply Geographic Information System “GIS” (ArcGIS 9.3) for calculating shoreline change rates and back-shore surface area due to these changes, particularly after constructing marine str...This study was undertaken to apply Geographic Information System “GIS” (ArcGIS 9.3) for calculating shoreline change rates and back-shore surface area due to these changes, particularly after constructing marine structures: including seawall, detached breakwaters and groins. Modelbuilder in ArcGIS software was used to design and develop an automated technique, module, for estimating such changes (rate and area). These changes are deduced from analysis of beach-nearshore profile surveys between 1970 and 2010 and shoreline position versus prevailing coastal processes. The results show that the major erosion occurred along the Delta promontories;the shoreline of Rosetta retreated (1.6 km) at an average rate of 60 m/yr with loss of back-shore area 6.4 km2;the coastline of Burullus bulge recessed at mean rate of 6 m/yr and decreasing in beach area of 1.31 km2;and at Damietta (Ras El-Bar) the shoreline moved backward (6 m/yr) with disappeared in beach area of 1.13 km2. The shape and orientation of these promontories contributed to create alternation between wave convergence zone that eventually causes erosion, and divergence zones that experienced shoreline accretion. Finally, the engineering structures didn’t solve or stop the erosion problem but shifted it from one place to another.展开更多
We developed a Gaussia luciferase (Gluc) reporter replicon of West Nile virus (WNV) and used it to quantify viral translation and RNA replication. The advantage of the Gluc replicon is that Gaussia luciferase is secre...We developed a Gaussia luciferase (Gluc) reporter replicon of West Nile virus (WNV) and used it to quantify viral translation and RNA replication. The advantage of the Gluc replicon is that Gaussia luciferase is secreted into the culture medium from cells transfected with Gluc replicon RNA, and the medium can be assayed directly for luciferase activity. Using a known Flavivirus inhibitor (NITD008), we demonstrated that the Gluc-WNV replicon could be used for antiviral screening. The Gluc-WNV-Rep will be useful for research in antiviral drug development programs, as well as for studying viral replication and pathogenesis of WNV.展开更多
Egypt faces a severe water scarcity in the last years. Increasing population cause rising in water demands and fast economic growth leads to ecosystem degradation. In addition, ineffective irrigation methods with wate...Egypt faces a severe water scarcity in the last years. Increasing population cause rising in water demands and fast economic growth leads to ecosystem degradation. In addition, ineffective irrigation methods with water misuse result in water quality degradation. River Nile is the main fresh water source in Egypt. This study evaluates, one of River Nile branches;Rosetta water quality through Geographical Information System (GIS) techniques. Fifteen water samples were analyzed for their chemical and biological properties. A mathematical model of Water Quality Index (WQI) has been built to integrate biochemical data as input parameters. This model describes the spatial distribution. On the other hand, the temporal of water quality status has been defined. A spatial variation of water quality index was generalized for the study area. The average water quality index values range between 58.8 and 67.2. Generally, the water quality index values within the study area were about the critical pollution level. The concentrations of most elements in the studied water samples were above the permissible levels for drinking water standards. This study concludes that Rosetta water is not suitable for drinking. Furthermore, it can be used for irrigation and domestic uses with specified treatments.展开更多
基金Supported by the Anhui Province Graduate Education Quality Engineering Project(2022jyjxggyj168)Anhui Province Higher Education Provincial-Level Quality Engineering Major Project(2022jcbs020)Anhui Province Higher Education Provincial-Level Quality Engineering General Project(2022jyxm527).
文摘In order to understand the transmission mechanism of West Nile virus(WNv)in birds(especially crows)and mosquitoes populations,this paper extends the traditional ordinary differential model of WNv to a reaction-diffusion system with more complex cross-diffusion.We explore the relationship between the basic reproduction number and cross-diffusion coefficients involving various parameters,and investigate the effect of vertical transmission of the virus on the transmission mechanism.We use the method of upper and lower solutions to investigate the existence of the coexistence solutions.The theoretical analysis and numerical simulation show that the WNv carried by birds and mosquitoes will coexist when the low-risk threshold R0*≥1,which is a disadvantage to the prevention and control of this virus,and disappear when the high-risk threshold R*0≤1,which is an advantage to that.
基金supported by the National Natural Science Foundation of China(52373171,52173154,52221006,22375014)the Beijing Natural Science Foundation Grant(JQ23006),and the Fundamental Research Funds for the Central Universities(ZY2404).
文摘Organic luminophores with superior solid-state luminescence are urgently required in various fields,such as lighting,display,sensing,and solar energy conversion.However,to achieve their highly efficient luminescence still remains a challenge.Herein,a newly designed Nile red derivative,Nile-DPA-VB,is successfully obtained to exhibit aggregation-induced emission characteristics with the photoluminescent quantum yield(PLQY)of 11.45%.Such PLQY could be further promoted to 53.45%when Nile-DPA-VB is polymerized undergoing precipitation polymerization process,where the confined aggregation microenvironment severely restricts the intramolecular motions of Nile-DPA-VB.Remarkably,Nile-DPA-VB is ultrasensitive to the polarity and steric effect,enabling the real-time monitoring of aggregation microenvironment evolution for precipitation polymerization.The microphase separation and dynamic hardening for the nucleation and growth processes are visually demonstrated,which contribute dominantly to the high-efficiency luminescence.Finally,by doping the as-prepared fluorescent polymeric particles into polymethyl methacrylate,functional films with high luminescence and high haze are achieved to show the potential in lighting.These findings clearly demonstrate the significant role of polymerization in constructing high-efficiency solid-state luminescent materials for practice.
基金National Tilapia Industry Technical System(nycytx-48-3)National Tilapia Seed Program(nyhyzx07-044-01)
文摘The NEW GIFT Nile tilapia （Oreochromis niloticus niloticus L.） is a nationally certificated new strain selected over 14 years and 9 generations from the base strain of GIFT Nile tilapia, introduced in 1994. This new variety has been extended in most of areas of China. The management of genetically improved strains, including the genetic markers for identification is needed urgently. RAPD analysis was conducted and their conversion to SCAR markers was developed. From NEW GIFT Nile tilapia, two strain-specific RAPD bands, S304624 bp and S36568 bp were identified. The strain-specific RAPD bands were gel-purified, cloned, and sequenced. Locus-specific primers were then designed to amplify the strain-specific bands. PCR amplification was conducted to test the variations in allele frequencies of two converted SCAR markers among the NEW GIFT Nile tilapia and its base strains, as well as 7 additional farmed strains worldwide. The frequency of SCAR marker Ⅰ （553 bp） was 85.7% in NEW GIFT Nile tilapia, but 16.7% in the base strain. The frequency of SCAR marker Ⅱ （558 bp） was 91.4% in NEW GIFT Nile tilapia, but 0% 70% in the 7 other strains. In order to confirm the utility of these two markers, an examination was conducted for a wild population from Egypt, resulted the frequency of SCAR Ⅰ and Ⅱ was 10% and 70%, respectively, much lower than that of New GIFT strain. The increase in allele frequency of these two SCAR markers suggests that these markers might be genetically linked to the quantitative trait loci （QTL） underlining the performance traits by long term selection, and indicate the bright potential of SCAR marker technology for tracking generations during selection progress and for distinguishing among genetically improved strain and other strains.
文摘River Nile is one of the longest transboundery rivers and it is shared and used by Burundi,Democratic Republic of Congo,Egypt,Ethiopia,Eritrea,Kenya,Rwanda,Sudan,Tanzania and Uganda.As of today,the Nile is a crucial resource for the economic development of the Nile Basin countries and a vital source of livelihood for 160 million inhabitants as well as 300 million people living in the 10 riparian countries.The Nile Basin Initiative(NBI) is one of the international cooperative river basin management program and regional partnership where all the Nile Basin countries except Eritrea unite to pursue long-term sustainable development,improved land use practices and management.This review therefore focused on the challenges not faced on NBI in terms of integrated use of the river and conducted analysis of strengths,weaknesses,opportunities and threats(SWOT) based on secondary data.The result of the review revealed that for decades,the Nile Basin people have been facing many complex environmental,social,economic and political challenges that have made it difficult for the proper management and sustainability of Nile water.The initiative provides training to develop skills in government ministries,non-governmental organizations and local communities in each country.It is also working to raise awareness of critical environmental issues by strengthening networks of environmental education practitioners;developing curriculum in the education sector.The challenges of NBI include the involvement and funding of World Bank,lack of sufficient staff,procedural and policies conflicts,lack of coordination and linkage with other regional institutions and lack of recognition as river basin organization.Considering the complex nature of the project,it is recommended that the NBI should come up with a strong multi-disciplinary monitoring and evaluation team to follow up all implemented projects.The NBI should carry out participatory land use planning in communities along the river basin.Moreover,livelihood analysis should be carried out especially in communities along the Nile to come up with poverty eradication projects which are socially acceptable,applicable,economically viable and affordable.
文摘Water quality of the river Nile and trace elements of the water, sediments and fish tissues were investigated in the current work. Eighteen different sampling points were selected along the whole course of the River Nile from its spring at Aswan to its estuaries at Rosetta and Damietta. Higher mean value of conductivity, alkalinity, chemical oxygen demand (COD), total organic carbon (TOC), ammonia (NH3), nitrate (NO3), total solid (TS), sulphate (SO4), chloride (Cl), orthophosphate were recorded in the water of Damietta and Rosetta branches comparing to other sites. Also trace metals in the water, sediments and tissues of Clarias gariepinus increased significantly (P Fe > Cu > Pb > Mn > Cr> Cd > Hg. In the gill tissues theses metals were accumulated in the following order Fe > Zn > Mn > Pb > Cr > Cu > Cd> Hg. The low accumulation of metals in muscle may be due to lack of binding affinity of these metals with the proteins of muscle. This is particularly important because muscles contribute the greatest mass of the flesh that is consumed as food.
文摘Objectives The main objective of the present article is to assess and evaluate the characteristics of the Nile water system , and identify the major sources of pollution and its environmental and health consequences. The article is also aimed to highlight the importance of water management via re-use and recycle of treated effluents for industrial purpose and for cultivation of desert land. Method An intensive effort was made by the authors to collect, assess and compile the available data about the River Nile. Physico-chemical analyses were conducted to check the validity of the collected data. For the determination of micro-pollutants, Gas Chromatography (GC) and High Performance Liquid Chromatography (HPLC) were used. Heavy metals were also determined to investigate the level of industrial pollution in the river system. Results The available data revealed that the river receives a large quantity of industrial, agriculture and domestic wastewater. It is worth mentioning that the river is still able to recover in virtually all the locations, with very little exception. This is due to the high dilution ratio. The collected data confirmed the presence of high concentrations of chromium and manganese in all sediment samples. The residues of organo-chlorine insecticides were detected in virtually all locations. However, the levels of such residues are usually below the limit set by the WHO for use as drinking water. The most polluted lakes are Lake Maryut and Lake Manzala. Groundwater pollution is closely related to adjacent (polluted) surface waters. High concentrations of nutrients, E.coli, sulfur, heavy metals, etc. have been observed in the shallow groundwater, largely surpassing WHO standards for drinking water use. Conclusion A regular and continuous monitoring scheme shall be developed for the River Nile system. The environmental law shall be enforced to prohibit the discharge of wastewater (agricultural, domestic or industrial) to River Nile system.
文摘The quality of a water body is usually characterized by sets of physical, chemical, and biological parameters, which are mutually interrelated. Since August 1997, monthly records of 33 parameters, monitored at 102 locations on the Nile Delta drainage system, are stored in a National Database operated by the Drainage Research Institute (DRI). Correlation patterns may be found between water quantity and water quality parameters at the same location, or among water quality parameters within a monitoring location or among locations. Serial correlation is also detected in water quality variables. Through the investigation of the level of information redundancy, assessment and redesign of water quality monitoring network aim to improve the overall network efficiency and cost effectiveness. In this study, the potential of the Artificial Neural Network (ANN) on simulating interrelation between water quality parameters is examined. Several ANN inputs, structures and training possibilities are assessed and the best ANN model and modeling procedure is selected. The prediction capabilities of the ANN are compared with the linear regression models with autocorrelated residuals, usually used for this purpose. It is concluded that the ANN models are more accurate than the linear regression models having the same inputs and output.
文摘Urban sprawl is threatening the limited highly fertile land in the Nile delta of Egypt. Landsat TM satellite images of 1984, 1992 and ETM+ of 2006 have been used to study the impact of urban sprawl on agricultural land of the Northern Nile delta, Egypt. Visual interpretation using on screen digitizing and change detection techniques were applied for monitoring the urban sprawl. Combining the land capability map and the urban thematic layer using GIS made it possible to point out the risk of urban expansion on the expense of the highly capable soil class. The results show that a total expansion of urban area amounted to 689.20 km2(6.3% of total area) during the study period 1984–2006. The urban expansion during the 1984–2006 was on the expense of the most fertile soils where, the high capable soils(Class I) lost 247.14 km2(2.26 % of total area) and the moderate capable soils lost 32.73 km2(0.3% of total area), while the low capable soils lost only 57.39 km2(0.53% of total area). The urban encroachment over the non capable soils was very limited during the study period 1984–1992, where 7.33 km2 only was lost. The pattern of urban sprawl has been changed during the 1992 to 2006 whereas much larger area(50.64 km2) of the non capable soils was converted to urban. It can be concluded that the urban sprawl is one of the dominant degradation process on the land of Nile Delta.
基金Supported by the National Natural Science Foundation of China(No.31170322)
文摘An 8-week feeding experiment was performed to evaluate the effect of dietary genistein on growth performance,body composition,and digestive enzymes activity of juvenile Nile tilapia(Oreochromis niloticus).Four isonitrogenous and isoenergetic diets were formulated containing four graded supplements of genistein:0,30,300,and 3 000 μg/g.Each diet was randomly assigned in triplicate to tanks stocked with 15 juvenile tilapia(10.47±1.24 g).The results show that 30 and 300 μg/gdietary genistein had no significant effect on growth performance of Nile tilapia,but the higher level of genistein(3 000 μg/g)significantly depressed the final body weight and specific growth rate.There was no significant difference in survival rate,feed intake,feed efficiency ratio or whole body composition among all dietary treatments.An assay of digestive enzymes showed that the diet containing 3 000 μg/ggenistein decreased stomach and hepatopancreas protease activity,and amylase activity in the liver and intestine,while a dietary level of300 μg/g genistein depressed stomach protease and intestine amylase activities.However,no significant difference in stomach amylase activity was found among dietary treatments.Overall,the results of the present study indicate that a high level of dietary genistein(3 000 μg/g,or above) would significantly reduce the growth of Nile tilapia,partly because of its inhibitory effect on the activity of major digestive enzymes.Accordingly,the detrimental effects of genistein,as found in soybean products,should not be ignored when applied as an alternative ingredient source in aquaculture.
基金supported by grants from the National Natural Science Foundation of China (31772831 and 31302170, 31861123001)the National Key Research and Development Program of China (2018YFD0900202)
文摘Spermatogenesis is a complex process in which spermatogonial stem cells differentiate and develop into mature spermatozoa.The transcriptional regulatory network involved in fish spermatogenesis remains poorly understood.Here,we demonstrate in Nile tilapia that the Sox transcription factor family member Sox30 is specifically expressed in the testes and mainly localizes to spermatocytes and spermatids.CRISPR/Cas9-mediated sox30 mutation results in abnormal spermiogenesis,reduction of sperm motility,and male subfertility.Comparative transcriptome analysis shows that sox30 mutation alters the expression of genes involved in spermatogenesis.Further chromatin immunoprecipitation followed by high-throughput sequencing(Ch IP-seq),Ch IP-PCR,and luciferase reporter assays revealed that Sox30 positively regulates the transcription of ift140 and ptprb,two genes involved in spermiogenesis,by directly binding to their promoters.Our data,taken together,indicate that Sox30 plays an essential role in Nile tilapia spermatogenesis by directly regulating the transcription of the spermiogenesis-related genes ift140 and ptprb.
基金Supported by Grants No.RTA2011-00036,SAF2008-04232 and FAU2008-00006 from the Spanish Ministerio de Ciencia e Innovaciónthe European Community’s Seventh Framework Programme(No.FP/2007-2013)under Grant Agreement 28394
文摘West Nile virus(WNV), a flavivirus of the Flaviviridae family, is maintained in nature in an enzootic transmission cycle between avian hosts and ornithophilic mosquito vectors, although the virus occasionally infects other vertebrates. WNV causes sporadic disease outbreaks in horses and humans, which may result in febrile illness, meningitis, encephalitis and flaccid paralysis. Until recently, its medical and veterinary health concern was relatively low; however, the number, frequency and severity of outbreaks with neurological consequences in humans and horses have lately increased in Europe and the Mediterranean basin. Since its introduction in the Americas, the virus spread across the continent with worrisome consequences in bird mortality and a considerable number of outbreaks among humans and horses, which have resulted in the largest epidemics of neuroinvasive WNV disease ever documented. Surprisingly, its incidence in human and animal health is very different in Central and South America, and the reasons for it are not yet understood. Even though great advances have been obtained lately regarding WNV infection, and although efficient equine vaccines are available, no specific treatments or vaccines for humanuse are on the market. This review updates the most recent investigations in different aspects of WNV life cycle: molecular virology, transmission dynamics, host range, clinical presentations, epidemiology, ecology, diagnosis, control, and prevention, and highlights some aspects that certainly require further research.
基金supported by Mashhad University of Medical Sciences.Mashhad.Iran(grant No.88290)Arboviruses and Viral Hemorrhagic Fevers Laboratory(National Ref.Lab).Pasteur Institute of Tehran.Iran
文摘Objective:To evaluate the prevalence of West Nile virus seropositivity in the general population of Mashhad.Northeast of Iran.Methods:One hundred and eighty two individuals living in the city of Mashhad were studied using cluster sampling method.Both IgM and IgG antibodies against WNV were detected by ELISA method.Results:In this study,the overall IgG seroprevalence of positive West Nile virus was 11%;however.IgM antibody was not found in the participants.Conclusions:Our study suggested that the prevalence rate of West virus is considerable in Mashhad city.It seems necessary for clinicians and health care workers to be aware of WNV infection in the Northeast Iran.
文摘The present study was conducted to evaluate the effect of baker yeast, Saccharomyces cerevisiae （SC） and exogenous digestive enzymes （pepsin, papain and a-amylase, EDE） dietary supplementation on growth performance, feed utilization and hematological indices of Nile tilapia, Oreochromis niloticus fingerlings. A total of 630 Nile tilapia fingerlings with an average body weight of 26.4 ± 0.2 g were divided in the seven experimental net-pen treatments （three replicates each）. The experiment was conducted for 119 days. Seven isonitrogenous （26.50%） digestible protein and isocaloric （13.40 MJ kgl） digestible energy experimental diets were formulated. The control diet had no SC and EDE added. Diets 2-3 each contained SC at levels of 2 and 4 g 100 g diet-t, respectively, while diets 4-5 each contained EDE at levels of （0.64, 1.28, 0.16） and （1.28, 2.56, 0.32） g 100 gdiefI of pepsin, papain and a-amylase, respectively. Diet 6 contained mixture of SC and EDE at levels of 1 g yeast and 0.32, 0.64, 0.08 g of pepsin, papain and a-amylase, respectively 100 gdiet1 and diet D7 contained 2 g yeast and 0.64, 1.28, 0.16 g of pepsin, papain and a-amylase, respectively 100 g dietl. Growth performance and feed utilization efficiency of Nile tilapia were significantly （P 〈 0.05） higher in all treatments receiving SC and/or EDE supplemented-diets than the control diet which suggests that the addition of SC and EDE enhanced the growth performance. Red blood cells counts, hematocrit and hemoglobin were significantly （P 〈 0.05） highest in all treatments receiving mixture of SC and EDE supplemented-diets （D6 ＋ D7）. The same trend was observed for total plasma protein and total plasma globulin levels. The results of present study suggested that Nile tilapia fingerlings fed diets containing the mixture of I g yeast, SC and 0.32, 0.64, 0.08 g of pepsin, papain and a-amylase, respectively 100 gdiet^-1, for 119 days had enhanced growth performance, diet utilization efficiency and hematological indices.
基金Supported by the National Natural Science Foundation of China(No.31170322)
文摘There is considerable concern that isoflavones,such as genistein in fish feed composed of soybean protein,affects somatic growth in fish.Our previous works demonstrated that 30 and 300 μg/g dietary genistein had no significant effect on growth performance in Nile tilapia(Oreochromis niloticus),but the higher level of genistein(3 000 μg/g) significantly depressed growth.This study was conducted to further examine the effects of dietary genistein on the endocrine disruption on growth hormone/insulin-like growth factor-I(GH/IGF-I) axis in Nile tilapia(O.niloticus).Juvenile fish were fed by hand twice daily to satiation with one of four isonitrogenous and isoenergetic diets,each containing either 0,30,300 or3 000 μg/g genistein.Following an 8-week feeding period,plasma GH and IGF-I levels were investigated by radioimmunoassay and gene expression levels of gh,ghrelin,gnrhs,ghr,npy,npyrs,pacap,ghrs,igf-I,igf-Ir,and igfbp3 were examined by real-time PCR.The results show that no significant change in plasma GH and IGF-I levels in fish fed with diets containing 30 μg/gand 300 μg/g genistein.mRNA expression of genes along the GH/IGF-I axis remained unaffected,except for igf-Ir,which was stimulated by the 300 μg/g genistein diet.While in fish fed the 3 000 μg/g genistein diet,the plasma GH and IGF-I levels decreased,and mRNA expression of gh,ghr2,npyr1,igf-I,and igf-Ir were also significantly depressed.In contrast,npy and igfbp3 mRNA expression were enhanced.This study provides convincing evidence for growth impediment by genistein by disturbing the GH/IGF-I axis in Nile tilapia O.niloticus.
文摘The efficacy of Endocrine Disrupting Compounds (EDCs), 17β-estradiol was tested on the fish Oreochromis niloticus in order to understand the intersex relationship of fish, in which sequential hermaphrodism can consist of a male changing into a female (protandry) or a female changing into a male (protogyny). The fish were equally divided into 3 groups. The first group was the control group;the second and third groups were treated with 10 and 100 mg L-1 of 17β-estradiol, respectively, for 30 days. The overall result in this experiment had no significant effect on the growth parameters. Among the two treated groups, the low concentration group shows results similar to those of the control groups. The high concentration group shows changes to the male reproductive system with the appearance of the testis-ova present resulting in an intersex condition of the male gonads. With this experiment, it can be concluded that 17β-estradiol at high concentration reveals positive changes towards the male reproductive system of the fish, Oreochromis niloticus.
基金Supported by Important National Science& Technology Specific Projects (2012ZX10004403,2012ZX10004219)
文摘Flaviviral NS2B is a required cofactor for NS3 serine protease activity and plays an important role in promoting functional NS2B-NS3 protease configuration and maintaining critical interactions with protease catalysis substrates. The residues D80DDG in West Nile virus (WNV) NS2B are important for protease activity. To investigate the effects of D80DDG in NS2B on protease activity and viral replication, the negatively charged region D80DD and the conserved residue G83 of NS2B were mutated (D80DD/E80EE, D80DD/K80KK, D80DD/A80AA, G83F, G83S, G83D, G83K, and G83A), and NS3 D75A was designated as the negative control. The effects of the mutations on NS2B-NS3 activity, viral translation, and viral RNA replication were analyzed using kinetic analysis of site-directed enzymes and a transient replicon assay. All substitutions resulted in significantly decreased enzyme activity and blocked RNA replication. The negative charge of D80DD is not important for maintaining NS2B function, but side chain changes in G83 have dramatic effects on protease activity and RNA replication. These results demonstrate that NS2B is important for viral replication and that D80DD and G83 substitutions prevent replication; they will be useful for understanding the relationship between NS2B and NS3.
文摘This study was undertaken to apply Geographic Information System “GIS” (ArcGIS 9.3) for calculating shoreline change rates and back-shore surface area due to these changes, particularly after constructing marine structures: including seawall, detached breakwaters and groins. Modelbuilder in ArcGIS software was used to design and develop an automated technique, module, for estimating such changes (rate and area). These changes are deduced from analysis of beach-nearshore profile surveys between 1970 and 2010 and shoreline position versus prevailing coastal processes. The results show that the major erosion occurred along the Delta promontories;the shoreline of Rosetta retreated (1.6 km) at an average rate of 60 m/yr with loss of back-shore area 6.4 km2;the coastline of Burullus bulge recessed at mean rate of 6 m/yr and decreasing in beach area of 1.31 km2;and at Damietta (Ras El-Bar) the shoreline moved backward (6 m/yr) with disappeared in beach area of 1.13 km2. The shape and orientation of these promontories contributed to create alternation between wave convergence zone that eventually causes erosion, and divergence zones that experienced shoreline accretion. Finally, the engineering structures didn’t solve or stop the erosion problem but shifted it from one place to another.
基金supported by the National Natural Science Foundation of China (grant No. 31170158 and 31000090)the '100 Talents Project' of Chinese Academy of Sciences, China (grant No. Y002171YC1)
文摘We developed a Gaussia luciferase (Gluc) reporter replicon of West Nile virus (WNV) and used it to quantify viral translation and RNA replication. The advantage of the Gluc replicon is that Gaussia luciferase is secreted into the culture medium from cells transfected with Gluc replicon RNA, and the medium can be assayed directly for luciferase activity. Using a known Flavivirus inhibitor (NITD008), we demonstrated that the Gluc-WNV replicon could be used for antiviral screening. The Gluc-WNV-Rep will be useful for research in antiviral drug development programs, as well as for studying viral replication and pathogenesis of WNV.
文摘Egypt faces a severe water scarcity in the last years. Increasing population cause rising in water demands and fast economic growth leads to ecosystem degradation. In addition, ineffective irrigation methods with water misuse result in water quality degradation. River Nile is the main fresh water source in Egypt. This study evaluates, one of River Nile branches;Rosetta water quality through Geographical Information System (GIS) techniques. Fifteen water samples were analyzed for their chemical and biological properties. A mathematical model of Water Quality Index (WQI) has been built to integrate biochemical data as input parameters. This model describes the spatial distribution. On the other hand, the temporal of water quality status has been defined. A spatial variation of water quality index was generalized for the study area. The average water quality index values range between 58.8 and 67.2. Generally, the water quality index values within the study area were about the critical pollution level. The concentrations of most elements in the studied water samples were above the permissible levels for drinking water standards. This study concludes that Rosetta water is not suitable for drinking. Furthermore, it can be used for irrigation and domestic uses with specified treatments.
