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91.
92.
Geographic isolation is a significant factor to consider when characterizing human populations. The knowledge of the genetic structure of isolated populations has been of great importance to disease-locus positioning and gene identification. To investigate the genetic structure of the Azorean population, we conducted a survey based on the frequencies of surnames listed in the 2001 telephone book. We calculated the following parameters: isonymy (I), the random component of inbreeding (F(ST)), genetic diversity according to Fisher (alpha), Karlin-McGregor's migration rate (v), and Nei's distance. For the 1,271 subscribers and 163 different surnames, Graciosa island presented the lowest value of abundance of surnames (alpha = 15.75), suggesting great genetic isolation compared to the other eight islands. Migration, calculated on the basis of the diversity of surnames within islands, ranged from 0.2747 (Corvo island) to 0.0026 (S?o Miguel island), indicating that people migrated preferentially toward the economically more developed islands. The value of the random component of inbreeding obtained for the whole population (F(ST) = 0.0039) indicates little genetic differentiation (Wright's F(ST) < 0.05). Moreover, isonymy similarity revealed using the UPGMA method shows three subclusters corresponding to the geographic distribution of the islands. 相似文献
93.
Tsahar E del Rio CM Arad Z Joy JP Izhaki I 《Physiological and biochemical zoology : PBZ》2005,78(2):239-245
Nectar-feeding birds have remarkably low nitrogen requirements. These may be due either to adaptation to a low-protein diet or simply to feeding on a fluid diet that minimizes metabolic fecal nitrogen losses. We measured minimal nitrogen requirements (MNR) and total endogenous nitrogen loss (TENL) in the omnivorous European starling Sturnus vulgaris, fed on an artificial nectar-like fluid diet of varying concentrations of sugar and protein. The MNR and TENL of the birds were similar and even slightly higher than allometrically expected values for birds of the starlings' mass (140% and 103%, respectively). This suggests that the low measured nitrogen requirements of nectar-feeding birds are not simply the result of their sugary and watery diets but a physiological adaptation to the low nitrogen input. We also measured the effect of water and protein intake on the nitrogenous waste form in the excreta and ureteral urine in European starlings. Neither high water intake nor low protein intake increased the fraction of nitrogen excreted as ammonia. Ammonia was excreted at consistently low levels by the starlings, and its concentration was significantly higher in ureteral urine than in excreta. We hypothesize that ureteral ammonia was reabsorbed in the lower intestine, indicating a postrenal modification of the urine. 相似文献
94.
The carbon isotope composition of an animals breath reveals the composition of the nutrients that it catabolizes for energy. Here we describe the use of Keeling plots, a method widely applied in ecosystem ecology, to measure the 13C of respired CO2 of small vertebrates. We measured the 13C of Rufous Hummingbirds (Selasphorus rufus) in the laboratory and of Mourning (Zenaida macroura) and White-winged (Z. asiatica) Doves in the field. In the laboratory, when hummingbirds were fed a sucrose based C3 diet, the 13C of respired CO2 was not significantly different from that of their diet (13CC3 diet). The 13C of respired CO2 for C3 fasted birds was slightly, albeit significantly, depleted in 13C relative to 13CC3 diet. Six hours after birds were shifted to a sucrose based C4 diet, the isotopic composition of their breath revealed that birds were catabolizing a mixture of nutrients derived from both the C3 and the C4 diet. In the field, the 13C of respired CO2 from Mourning and White-winged Doves reflected that of their diets: the CAM saguaro cactus (Carnegeia gigantea) and C3 seeds, respectively. Keeling plots are an easy, effective and inexpensive method to measure 13C of respired CO2 in the lab and the field. 相似文献
95.
Anna K. Snyder Jason W. Deberry Laura Runyen-Janecky Rita V. M. Rio 《Proceedings. Biological sciences / The Royal Society》2010,277(1692):2389-2397
Host-associated microbial interactions may involve genome complementation, driving-enhanced communal efficiency and stability. The tsetse fly (Diptera: Glossinidae), the obligate vector of African trypanosomes (Trypanosoma brucei subspp.), harbours two enteric Gammaproteobacteria symbionts: Wigglesworthia glossinidia and Sodalis glossinidius. Host coevolution has streamlined the Wigglesworthia genome to complement the exclusively sanguivorous tsetse lifestyle. Comparative genomics reveal that the Sodalis genome contains the majority of Wigglesworthia genes. This significant genomic overlap calls into question why tsetse maintains the coresidence of both symbionts and, furthermore, how symbiont homeostasis is maintained. One of the few distinctions between the Wigglesworthia and Sodalis genomes lies in thiamine biosynthesis. While Wigglesworthia can synthesize thiamine, Sodalis lacks this capability but retains a thiamine ABC transporter (tbpAthiPQ) believed to salvage thiamine. This genetic complementation may represent the early convergence of metabolic pathways that may act to retain Wigglesworthia and evade species antagonism. We show that thiamine monophosphate, the specific thiamine derivative putatively synthesized by Wigglesworthia, impacts Sodalis thiamine transporter expression, proliferation and intracellular localization. A greater understanding of tsetse symbiont interactions may generate alternative control strategies for this significant medical and agricultural pest, while also providing insight into the evolution of microbial associations within hosts. 相似文献
96.
Hemme CL Mouttaki H Lee YJ Zhang G Goodwin L Lucas S Copeland A Lapidus A Glavina del Rio T Tice H Saunders E Brettin T Detter JC Han CS Pitluck S Land ML Hauser LJ Kyrpides N Mikhailova N He Z Wu L Van Nostrand JD Henrissat B He Q Lawson PA Tanner RS Lynd LR Wiegel J Fields MW Arkin AP Schadt CW Stevenson BS McInerney MJ Yang Y Dong H Xing D Ren N Wang A Huhnke RL Mielenz JR Ding SY Himmel ME Taghavi S van der Lelie D Rubin EM Zhou J 《Journal of bacteriology》2010,192(24):6494-6496
Modern methods to develop microbe-based biomass conversion processes require a system-level understanding of the microbes involved. Clostridium species have long been recognized as ideal candidates for processes involving biomass conversion and production of various biofuels and other industrial products. To expand the knowledge base for clostridial species relevant to current biofuel production efforts, we have sequenced the genomes of 20 species spanning multiple genera. The majority of species sequenced fall within the class III cellulosome-encoding Clostridium and the class V saccharolytic Thermoanaerobacteraceae. Species were chosen based on representation in the experimental literature as model organisms, ability to degrade cellulosic biomass either by free enzymes or by cellulosomes, ability to rapidly ferment hexose and pentose sugars to ethanol, and ability to ferment synthesis gas to ethanol. The sequenced strains significantly increase the number of noncommensal/nonpathogenic clostridial species and provide a key foundation for future studies of biomass conversion, cellulosome composition, and clostridial systems biology. 相似文献
97.
The enantioselective epoxidation of 6-cyano-2,2-dimethylchromene (Chrom) catalysed by the Jacobsen catalyst, using sodium hypochlorite (NaOCl) as oxygen source, at room temperature, was performed in a series of 1,3-dialkylimidazolium and tetra-alkyl-dimethylguanidium based ionic liquids. All the room temperature ionic liquids (RTILs) could be used as reaction media for the enantioselective epoxidation of the alkene giving, generally, moderate to good epoxide yields and enantiomeric excesses (ee%).For the series of ionic liquids derived from the 1,3-dialkylimidazolium cation, it was observed some relationship between the RTILs physical properties and the catalytic reaction parameters, exemplified by linear correlations between (i) the ee% and the α Kamlet-Taft parameter (hydrogen bond acidity of the solvent) for CH2Cl2 and [C4mnim][BF4] ionic liquids (n = 1 or 2), and (ii) the ee% and the β Kamlet-Taft parameter (hydrogen bond basicity of the solvent) for CH2Cl2 and [C4mim][X] ionic liquids (X = PF6, NTf2 or BF4).All the RTILs could be reused in further catalytic cycles, with the exception of [C8mim][PF6]. The reutilisation of the Jacobsen catalyst for four times generally led to a decrease in the epoxide yield and to a slight decrease in the enantioselectivity. The recycling of the catalyst could be improved by imparting an ionic character to the complex through abstraction of the axially coordinated chloride anion (Cat 2). Other oxygen sources, such as iodosylbenzene, hydrogen peroxide and urea-hydrogen peroxide adduct, were also tested coupled with Jacobsen catalyst, but the best results were achieved with NaOCl. 相似文献
98.
The CYP2D6 gene codes for a P450 monooxygenase which is involved in the biotransformation of a large number of commonly prescribed drugs. Adverse drug effects and therapeutic failure can be related to abnormal CYP2D6 activity. We investigated the allele and genotype frequencies of cytochrome P4502D6 in a Spanish population to predict the prevalence of ultra-rapid and poor metabolizer phenotypes in our population and to design a feasible CYP2D6 genotyping protocol. The study included 105 healthy unrelated Spanish Caucasian volunteers. CYP2D6 genotyping was performed by a combination of long-PCR, direct sequencing and allele-specific real-time PCR. The frequency of the wild-type CYP2D6*1 allele was 31%. The alleles coding for slightly (CYP2D6*2) or moderately (*9 and *10) reduced activity showed frequencies of 40.47, 2.38 and 1.90%, respectively. Frequencies of defective alleles *3, *4, *5 and *6 were 0.95, 13.8, 3.33 and 0.95%, respectively. The defective CYP2D6 alleles *7, *8, *12, *14, *15 and *21 were not found. Duplicated CYP2D6 alleles were detected at a frequency of 4.27%. Our protocol allows the identification of the four inactive CYP2D6 alleles (*3, *4, *5 and *6) and the detection of alleles with CYP2D6 *1, CYP2D6 *2 and CYP2D6*4 gene duplications. Testing for this reduced CYP2D6 allele set would facilitate its use in clinical practice by assisting in the development of individualized pharmacotherapy. 相似文献
99.
100.