Antibody class switching mediated by yeast endonuclease-generated DNA breaks     

Zarrin AA  Del Vecchio C  Tseng E  Gleason M  Zarin P  Tian M  Alt FW 《Science (New York, N.Y.)》2007,315(5810):377-381

Antibody class switching in activated B cells uses class switch recombination (CSR), which joins activation-induced cytidine deaminase (AID)-dependent double-strand breaks (DSBs) within two large immunoglobulin heavy chain (IgH) locus switch (S) regions that lie up to 200 kilobases apart. To test postulated roles of S regions and AID in CSR, we generated mutant B cells in which donor Smu and accepter Sgamma1 regions were replaced with yeast I-SceI endonuclease sites. We found that site-specific I-SceI DSBs mediate recombinational IgH locus class switching from IgM to IgG1 without S regions or AID. We propose that CSR evolved to exploit a general DNA repair process that promotes joining of widely separated DSBs within a chromosome.  相似文献   

Strong, transparent, multifunctional, carbon nanotube sheets     

Zhang M  Fang S  Zakhidov AA  Lee SB  Aliev AE  Williams CD  Atkinson KR  Baughman RH 《Science (New York, N.Y.)》2005,309(5738):1215-1219

Individual carbon nanotubes are like minute bits of string, and many trillions of these invisible strings must be assembled to make useful macroscopic articles. We demonstrated such assembly at rates above 7 meters per minute by cooperatively rotating carbon nanotubes in vertically oriented nanotube arrays (forests) and made 5-centimeter-wide, meter-long transparent sheets. These self-supporting nanotube sheets are initially formed as a highly anisotropic electronically conducting aerogel that can be densified into strong sheets that are as thin as 50 nanometers. The measured gravimetric strength of orthogonally oriented sheet arrays exceeds that of sheets of high-strength steel. These nanotube sheets have been used in laboratory demonstrations for the microwave bonding of plastics and for making transparent, highly elastomeric electrodes; planar sources of polarized broad-band radiation; conducting appliqués; and flexible organic light-emitting diodes.  相似文献   

Inversions and gene order shuffling in Anopheles gambiae and A. funestus     

Sharakhov IV  Serazin AC  Grushko OG  Dana A  Lobo N  Hillenmeyer ME  Westerman R  Romero-Severson J  Costantini C  Sagnon N  Collins FH  Besansky NJ 《Science (New York, N.Y.)》2002,298(5591):182-185

In tropical Africa, Anopheles funestus is one of the three most important malaria vectors. We physically mapped 157 A. funestus complementary DNAs (cDNAs) to the polytene chromosomes of this species. Sequences of the cDNAs were mapped in silico to the A. gambiae genome as part of a comparative genomic study of synteny, gene order, and sequence conservation between A. funestus and A. gambiae. These species are in the same subgenus and diverged about as recently as humans and chimpanzees. Despite nearly perfect preservation of synteny, we found substantial shuffling of gene order along corresponding chromosome arms. Since the divergence of these species, at least 70 chromosomal inversions have been fixed, the highest rate of rearrangement of any eukaryote studied to date. The high incidence of paracentric inversions and limited colinearity suggests that locating genes in one anopheline species based on gene order in another may be limited to closely related taxa.  相似文献   

Multi-scale processes influencing global carbon storage and land-carbon-climate nexus: A critical review     

Owais Ali WANI  Shamal Shasang KUMAR  Nazir HUSSAIN  Anas Ibni Ali WANI  Subhash BABU  Parvej ALAM  Megna RASHID  Simona Mariana POPESCU  Sheikh MANSOOR 《土壤圈》2023,33(2):250-267

Carbon(C) is a key constitutive element in living organisms(plants, microbes, animals, and humans). Carbon is also a basic component of agriculture because it plays a dynamic role in crop growth, development, nutrient cycling, soil fertility, and other agricultural features. The presence of C enhances soil physical, chemical, and biological properties. The C cycle supports all life on the Earth by transferring C between living organisms and the environment. The global climate is changing, and th...  相似文献   

Mentha longifolia Alleviates Exogenous Serotonin-Induced Diabetic Hypoglycemia and Relieves Renal Toxicity via ROS Regulation     

Ali  Tahir  Ishtiaq  Ayesha  Mushtaq  Iram  Ayaz  Neelum  Jan  Muhammad Ishtiaq  Khan  Wajiha  Khan  Uzma  Murtaza  Iram 《Plant foods for human nutrition (Dordrecht, Netherlands)》2021,76(4):501-506

Plant Foods for Human Nutrition - Diabetic kidney disease is one of the most common microvascular complications of diabetes mellitus with consequences of diabetic nephropathy. Here we amined to...  相似文献   

Carbon,nitrogen, and phosphorus stoichiometry mediate sensitivity of carbon stabilization mechanisms along with surface layers of a Mollisol after long-term fertilization in Northeast China     

Abrar  Muhammad Mohsin  Xu  Hu  Aziz  Tariq  Sun  Nan  Mustafa  Adnan  Aslam  Muhammad Wajahat  Shah  Syed Atizaz Ali  Mehmood  Khalid  Zhou  Baoku  Ma  Xingzhu  Chen  Xianni  Xu  Minggang 《Journal of Soils and Sediments》2021,21(2):705-723

Journal of Soils and Sediments - Soil organic carbon (SOC) is an important parameter determining soil fertility and sustaining soil health. How C, N, and P contents and their stoichiometric ratios...  相似文献   

Salinity and drought affect yield response of bell pepper similarly     

Ahmet Kurunc  Ali Unlukara  Bilal Cemek 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(6):514-522

Abstract

There is a growing realization that an increasing number of countries are approaching full utilization of their conventional water resources and that the quantity of good-quality water supplies available to agriculture is diminishing. Effects of irrigation regime and irrigation water salinity on bell pepper including yield, fruit number and quality, vegetative and root growth, evapotranspiration and water use efficiency were investigated in this study by conducting two different experiments. Six different salinity levels of irrigation water and four different irrigation regimes were used as treatments. Considering the results from irrigation water salinity experiment, it can be concluded that as soil salinity increases, water consumption, water use efficiency, yield and other vegetative growth parameters of bell pepper were decreased. A polynomial relationship between soil salinity and water consumption was observed. It was found that bell pepper is moderately sensitive to salinity with a 1.2 dS m^?1 threshold and a 10.9% slope value. In the irrigation regime experiment, limited irrigation caused decreases in water consumption, yield and vegetative growth of bell pepper. Yield response factors were close in the cases of irrigation regime (1.50) and irrigation water salinity (1.40). Total soluble solids of bell pepper were increased due to both irrigation water salinity and water application rate but not dry matter ratio. Considerable water consumption decreases because of salinity were determined. Therefore, the effect of irrigation water salinity should be considered in irrigation management to prevent excess saline water application and to protect the environment.  相似文献   

Ecogeographic survey and gap analysis of Lathyrus L. species     

Ali Shehadeh  Ahmed Amri  Nigel Maxted 《Genetic Resources and Crop Evolution》2013,60(7):2101-2113

The genetic diversity of the genus Lathyrus is of significant importance, particularly for its role in sustaining the livelihoods of local communities living under very harsh conditions and its potential to adapt to climate change. Grasspea (L. sativus) is the most widely used species and to a lesser extent L. cicera and L. ochrus, each is used for animal feed in many parts of the world and food in poorer regions, but human over-consumption of the seeds can lead to lathyrism, a disease caused by neurotoxins. This study has added substantial information and accuracy to the existing global Lathyrus database by combining diverse datasets and by adding information of major herbaria from Europe. This global Lathyrus database, available at ICARDA, was used to conduct gap analysis to guide future collecting missions and in situ conservation efforts for highest priority species originating from the Mediterranean Basin, and Caucasus, Central and West Asia region. The results showed the highest concentration of Lathyrus priority species are found in the Fertile Crescent countries, France, Italy and Greece. The area either side of the Lebanese/Syrian border near Tel Kalakh, Syria was identified as the hotspot and the overall priority location for establishing the first in situ genetic reserve. The gap analysis for ex situ conservation shows that only six species (representing 16.6 %) of the 36 priority species are adequately sampled. Only L. cicera has already been well sampled among the closely related species to cultivated species L. sativus, indicating further collecting of L. amphicarpos, L. belinensis, L. chrysanthus, L. hirticarpus, L. hirsutus and L. marmoratus is required. In addition, six secondary priority Lathyrus species have no ex situ collections (L. lentiformis, L. lycicus, L. phaselitanus, L. trachycarpus, L. tremolsianus and L. undulatus) and also require targeted collecting.  相似文献   

Growth,transpiration, root‐born cytokinins and gibberellins,and nutrient compositional changes in sesame exposed to low root‐zone temperature under different ratios of nitrate: Ammonium supply     

Imad‐eldin A. Ali  Uzi Kafkafi  Isomaro Yamaguchi  Yukihiro Sugimoto  Shinobu Inanaga 《Journal of plant nutrition》2013,36(1):123-140

The growth of sesame (Sesamum indicum L.) was studied at three root temperature regimes (25/25, 20/10 and 15/15°C day/night) factorially combined with three NO₃ ^‐: NH₄ ⁺ ratios (mM ratios, 10:0, 8:2, or 6:4), as a source of nitrogen (N), in the irrigation solution. The air temperature was kept constant at 30°C. Transpiration, nutrient composition, and level of root‐born cytokinins and gibberellins in the xylem exudate were monitored. The two low root temperature regimes, 15/15 and 20/10°C, restricted the growth of sesame, reduced transpiration and increased the accumulation of soluble carbohydrates in the shoot and in the roots compared to the 25/25°C regime. The NO₃:NH₄ ⁺ ratios had no effect on growth. Nutrient contents in the shoot at low root temperatures, particularly K⁺, NO₃ ^‐, and H₂PO₄ ^‐ were decreased markedly, but Na⁺ increased relative to it's content in the 25/25°C regime. Increasing NH₄ ⁺ proportion in the irrigation solution raised total N concentration in the plant tissues at all root temperatures. The amounts of cytokinins and gibberellins in the xylem exudate decreased at the low root temperature regimes relative to the 25/25°C regime. Low root temperature reduced xylem transport of nutrients and root born‐phytohormones, most probably because of reduced water flow through the plant relative to the 25/25°C regime.  相似文献   

Interspecific Facilitative Root Interactions and Rhizosphere Effects on Phosphorus and Iron Nutrition Between Mixed Grown Chickpea and Barley     

Aydin Gunes  Esra G. Bagci  Ali Inal 《Journal of plant nutrition》2013,36(9):1455-1469

A glasshouse study was conducted to investigate the effects of interspecific complementary and competitive root interactions and rhizosphere effects on phosphorus (P) and iron (Fe) nutrition of mixed grown chickpea (Cicer arietinum L.) and barley (Hordeum vulgare L.). In order to provide more physiological evidence on the mechanisms of interspecific facilitation, we determined phosphatase activities in plant and rhizosphere, and root ferric reducing capacity (FR), Fe-solubilizing activity (Fe-SA) and rhizosphere pH. The results of the experiment revealed that biomass yield of barley was significantly increased by associated chickpea as compared to monocultured barley, while mixed cropping caused a slight decreases in the biomass yield of chickpea. The rhizosphere was strongly acidified under chickpea and chickpea/barley mixed cropping and this acidification, in turn, increased the available P, Fe(II) and DTPA-Fe concentrations in the rhizosphere. Fe-solubilizing activity (Fe-SA) and ferric reducing (FR) capacity of the roots were higher in both species grown in mixed culture relative to their monoculture which may improve Fe nutrition of both species. Leaf acid phosphatase (APase, EC 3.1.3.2) activity was higher in both plants under mixed cropping that may improve P nutrition of barley by chickpea.  相似文献